Abstract:
A microelectronic component with circuitry includes a substrate (possibly semiconductor) having an opening in a top surface. The circuitry includes a conductive via (possibly metal) in the opening. The opening has a first sidewall of a first material, and the conductive via has a second sidewall of a second material (possibly metal). At least at one side of the opening, the first and second sidewalls are spaced from each other at the top surface of the substrate but the first and second sidewalls meet below the top surface of the substrate at a meeting location. Between the meeting location and the top surface of the substrate, the first and second sidewalls are separated by a third material (possibly foam) which is a dielectric different from the first material. The third material lowers thermal stress in case of thermal expansion compared to a structure in which the third material were replaced with the second material.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to packaging of microelectronic devices and interposer structures, especially conductive via structures and methods of forming such via structures in semiconductor and interposer packages. 
         [0002]    Microelectronic elements generally comprise a thin slab of a semiconductor material, such as silicon or gallium arsenide, commonly called a die or a semiconductor chip. Semiconductor chips are commonly provided as individual, prepackaged units. In some unit designs, the semiconductor chip is mounted to a substrate or chip carrier, which is in turn mounted on a circuit panel, such as a printed circuit board. 
         [0003]    The active circuitry is fabricated in a first face of the semiconductor chip (e.g., a second surface). To facilitate electrical connection to the active circuitry, the chip is provided with bond pads on the same face. The bond pads are typically placed in a regular array either around the edges of the die or, for many memory devices, in the die center. The bond pads are generally made of a conductive metal, such as copper, or aluminum, around 0.5 μm thick. The bond pads could include a single layer or multiple layers of metal. The size of the bond pads will vary with the device type but will typically measure tens to hundreds of microns on a side. 
         [0004]    Through-silicon vias (TSVs) are used to connect the bond pads with a second face of the semiconductor chip opposite the first face (e.g., a first surface). A conventional via includes a hole penetrating through the semiconductor chip and a conductive material extending through the hole from the first face to the second face. The bond pads may be electrically connected to vias to allow communication between the bond pads and conductive elements on the second face of the semiconductor chip. 
         [0005]    Conventional TSV holes may reduce the portion of the first face that can be used to contain the active circuitry. Such a reduction in the available space on the first face that can be used for active circuitry may increase the amount of silicon required to produce each semiconductor chip, thereby potentially increasing the cost of each chip. 
         [0006]    Conventional vias may have reliability challenges because of a non-optimal stress distribution radiating from the vias and a mismatch of the coefficient of thermal expansion (CTE) between a semiconductor chip, for example, and the structure to which the chip is bonded. For example, when conductive vias within a semiconductor chip are insulated by a relatively thin and stiff dielectric material, significant stresses may be present within the vias due to CTE mismatch between the conductive material of the via and the material of the substrate. In addition, when the semiconductor chip is bonded to conductive elements of a polymeric substrate, the electrical connections between the chip and the higher CTE structure of the substrate will be under stress due to CTE mismatch. 
         [0007]    Size is a significant consideration in any physical arrangement of chips. The demand for more compact physical arrangements of chips has become even more intense with the rapid progress of portable electronic devices. Merely by way of example, devices commonly referred to as “smart phones” integrate the functions of a cellular telephone with powerful data processors, memory and ancillary devices such as global positioning system receivers, electronic cameras, and local area network connections along with high-resolution displays and associated image processing chips. Such devices can provide capabilities such as full internet connectivity, entertainment including full-resolution video, navigation, electronic banking and more, all in a pocket-size device. Complex portable devices require packing numerous chips into a small space. Moreover, some of the chips have many input and output connections, commonly referred to as “I/Os.” These I/Os must be interconnected with the I/Os of other chips. The interconnections should be short and should have low impedance to minimise signal propagation delays. The components which form the interconnections should not greatly increase the size of the assembly. Similar needs arise in other applications as, for example, in data servers such as those used in internet search engines. For example, structures which provide numerous short, low-impedance interconnects between complex chips can increase the bandwidth of the search engine and reduce its power consumption. 
         [0008]    Despite the advances that have been made in semiconductor via and interposer via formation and interconnection, there is still a need for improvements in order to minimise the size of semiconductor chips and interposer structures, while enhancing electrical interconnection reliability. These attributes of the present invention may be achieved by the construction of the components and the methods of fabricating components as described hereinafter. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    In accordance with an aspect of the invention, a component can include a substrate and a conductive via extending within an opening in the substrate. The substrate can have first and second opposing surfaces. The opening can extend from the first surface towards the second surface and can have an inner wall extending away from the first surface. A dielectric material can be exposed at the inner wall. The conductive via can define a relief channel within the opening adjacent the first surface. The relief channel can have an edge within a first distance frost the inner wall in a direction of a plane parallel to and within five microns below the first surface, the first distance being the lesser of one micron and five percent of a maximum width of the opening in the plane. The edge can extend along the inner wall to span at least five percent of a circumference of the inner wall. 
         [0010]    In a particular embodiment, the substrate can have an effective CTE in a plane of the substrate of no more than 20 ppm/° C. In one example, the substrate can consist essentially of one of: a semiconductor material, ceramic, glass, or a composite material. In an exemplary embodiment, the substrate can include a composite material having an effective CTE in a plane of the substrate that is tuned to match a CTE of the conductive via. In a particular example, the substrate can have an active device region adjacent the first surface, and the plane can be located below the active device region. In one embodiment, the plane can be located 1 micron below the active device region. 
         [0011]    In one embodiment, the substrate can have an active device region adjacent the first surface, and at least some active semiconductor devices within the active device region can be within a distance in the plane from the opening of three times the maximum width of the opening. In one example, the substrate can have an active device region adjacent the first surface, and at least some active semiconductor devices within the active device region can be within a distance in the plane from the opening of two times the maximum width of the opening. In an exemplary embodiment, the substrate can have an active device region adjacent the first surface, and at least some active semiconductor devices within the active device region can be within a distance in the plane from the opening of one times the maximum width of the opening. 
         [0012]    In a particular example, the substrate can consist essentially of the dielectric material. In one embodiment, the substrate can consists essentially of glass or ceramic. In a particular embodiment, the substrate can consist essentially of a semiconductor material, and the dielectric material can be a dielectric layer overlying the semiconductor material within the opening. In one example, a portion of the inner wall can be exposed within the relief channel. In an exemplary embodiment, a width of the relief channel in a radial direction from the inner wall in the relief plane can be less than 5 microns. In a particular example, a width of the relief channel in a radial direction from the inner wall in the relief plane can be less than 1 micron. In one embodiment, a width of the relief channel in a radial direction from the inner wall in the relief plane can be less than 0.2 microns. 
         [0013]    In a particular embodiment, a depth of the relief channel below the first surface of the substrate can be at most two times the maximum width of the opening. In one example, a depth of the relief channel below the first surface of the substrate can be at most equal to the maximum width of the opening. In an exemplary embodiment, a depth of the relief channel below the first surface of the substrate can be at most half the maximum width of the opening. In a particular example, the relief channel can be an inner relief channel, the substrate can have a dielectric material, and a first surface of the dielectric material can be exposed at and can define the inner wall of the opening. The substrate can have an outer relief channel adjacent the first surface of the substrate and adjacent a second surface of the dielectric material opposite the first surface thereof. 
         [0014]    In one embodiment, a depth of the outer relief channel below the first surface of the substrate can be greater than a depth of the inner relief channel below the first surface of the substrate. In a particular embodiment, the component can also include a dielectric material disposed within the outer relief channel. In one example, the relief channel can be one relief channel of a plurality of discrete relief channels separated from one another by a portion of material of the conductive via. In an exemplary embodiment, the plurality of discrete relief channels together can extend across at least 50% of the circumference of the conductive via. In a particular example, the plurality of discrete relief channels can include at least one ring-shaped channel. 
         [0015]    In one embodiment, the relief channel can extend around the entire circumference of the conductive via. In a particular example, a portion of the inner wall can be exposed within the relief channel throughout the entire circumference of the conductive via. In an exemplary embodiment, a width of the relief channel in a radial direction from the inner wall in the plane can vary around the circumference of the conductive via. In one example, the plane can be located 5 microns below the first surface. In a particular embodiment, the relief channel can extend to a top surface of a BEOL layer or the component. In one embodiment, a BEOL layer of the component can overlie the relief channel. In a particular example, the relief channel can define a tapered inner edge that is oblique to the first surface of the substrate. 
         [0016]    In an exemplary embodiment, the component can also include solder joined to the conductive via within the relief channel. In one example, the component can also include a polymer disposed within the relief channel. In a particular embodiment, the polymer can be completely surrounded by material of the conductive via. In one embodiment, the component can also include a barrier metal layer disposed adjacent the inner wall. In a particular example, a portion of the barrier metal layer can be exposed within the relief channel. In an exemplary embodiment, the component can also include a conductive post extending from a top surface of the conductive via. In one example, the conductive post can consist essentially of at least one of: copper, a copper alloy, and nickel. In a particular embodiment, the conductive post may not overlie the relief channel. 
         [0017]    In one embodiment, the conductive post can have a tapered shape, the conductive post having a first width at a base of the conductive post adjacent the top surface of the conductive via and a second width at a tip of the conductive post remote from the top surface, the first and second widths being in a direction parallel to the first surface of the substrate, the second width being different than the first width. In a particular example, at least a portion of the conductive post can have an outer surface defining a curvilinear cross-sectional shape in a plane that is perpendicular to the first surface of the substrate. In an exemplary embodiment, the component can also include a plurality of conductive posts extending from a top surface of the conductive via. 
         [0018]    In one example, the conductive via can have a non-circular cross-sectional shape in a plane that is parallel to the first surface of the substrate. In a particular embodiment, the conductive via can have an elongated cross-sectional shape, the conductive via defining a length in a first direction and a width in a second direction transverse to the first direction, the first and second directions being within a plane that is parallel to the first surface of the substrate, the length being greater than the width. In one embodiment, the opening can be a through opening that extends between the first and second surfaces. 
         [0019]    In a particular example, the opening can have a tapered shape, the opening having a first width at the first surface and a second width at the second surface, the first and second widths being in a direction parallel to the first surface of the substrate, the first width being less than the second width. In an exemplary embodiment, at least a portion of the opening can be bounded by a surface defining a curvilinear cress-sectional shape in a plane that is perpendicular to the first surface of the substrate. 
         [0020]    In one example, the relief channel can be a first relief channel and the plane can be a first plane. The conductive via can also include a second relief channel within the opening adjacent the second surface, the second relief channel having an edge within a second distance from the inner wall in a direction of a second plane parallel to and within five microns below the second surface, the second distance being the lesser of one micron and five percent of a maximum width of the opening in the second plane, the edge of the second relief channel extending along the inner wall to span at least five percent of the circumference of the inner wall. 
         [0021]    In a particular embodiment, the conductive via can have an outer contact surface located below the first surface of the substrate. In one embodiment, the component can be configured to reduce stress in the conductive via within the plane below 200 MPa resulting from application of external stress to the conductive via. In a particular example, a system can include a component as described above and one or more additional electronic components electrically connected to the component. In an exemplary embodiment, the system can also include a housing, said component and said additional electronic components being mounted to said housing. 
         [0022]    In accordance with another aspect of the invention, a component can include a substrate including a semiconductor region having first and second opposed surfaces, an opening extending within the substrate from the first surface towards the second surface, a solid metal conductive via extending within the opening, and an active device region adjacent the first surface of the semiconductor region. The opening can have an inner wall extending away from the first surface. An inorganic dielectric material can be exposed at the inner wall. The opening can have a maximum width in a direction of a plane parallel to and within five microns below the first surface. At least some active semiconductor devices within the active device region can be within a distance from the inner wall in the plane of three times the maximum width of the opening. 
         [0023]    In one example, at least some active semiconductor devices within the active device region can be within a distance from the inner wall in the plane of two times the maximum width of the opening. In a particular embodiment, at least some active semiconductor devices within the active device region can be within a distance from the inner wall in the plane of one times the maximum width of the opening. In one embodiment, the conductive via can define a relief channel within the opening adjacent the first surface, the relief channel having an edge within a first distance from the inner wall in a direction of the plane, the first distance being the lesser of one micron and five percent of the maximum width of the opening in the plane, the edge extending along the inner wall to span at least five percent of a circumference of the inner wall. 
         [0024]    In accordance with yet another aspect of the invention, a component can include a substrate including a semiconductor region having first and second opposed surfaces, a plurality of openings each extending within the substrate from the first surface towards the second surface, and a plurality of solid metal conductive vias, each conductive via extending within a respective one of the openings. Each opening can have an inner wall extending away from the first surface and an inorganic dielectric material being exposed at the inner wall. Each opening can have a maximum width in a direction of a plane parallel to and within five microns below the first surface. The plurality of conductive vias can define a minimum pitch in the plane between centers of any two adjacent ones of the conductive vias, the minimum pitch being less than three times the maximum width of each of the openings in which the adjacent conductive vias extend. 
         [0025]    In a particular example, the minimum pitch can be less than two times the maximum width of each of the openings in which the adjacent conductive vias extend. In an exemplary embodiment, the minimum pitch can be less than 1.2 times the maximum width of each of the openings in which the adjacent conductive vias extend. In one example, at least some of the conductive vias can each define a relief channel within the respective opening adjacent the first surface. Each relief channel can have an edge within a first distance from the respective inner wall in a direction of the plane, the first distance being the lesser of one micron and five percent of the maximum width of the respective opening in the plane, the edge extending along the respective inner wall to span at least five percent of a circumference of the inner wall. 
         [0026]    In accordance with still another aspect of the invention, a component can include a substrate including a semiconductor region having first and second opposed surfaces, an opening extending within the substrate from the first surface towards the second surface, a solid metal conductive via extending within the opening and having an outer contact surface located below the first surface of the substrate in a direction perpendicular to the first surface, and solder joined to the conductive via at the outer contact surface and extending within the opening below the first surface of the substrate. The opening can have an inner wall extending away from the first surface, an inorganic dielectric material being exposed at the inner wall. 
         [0027]    In a particular embodiment, the conductive via can define a relief channel within the opening adjacent the outer contact surface. The relief channel can have an edge within a first distance from the inner wall in a direction of a plane parallel to and within five microns below the first surface, the first distance being the lesser of one micron and five percent of a maximum width of the opening in the plane, the edge extending along the inner wall to span at least five percent of a circumference of the inner wall. 
         [0028]    In accordance with another aspect of the invention, a component can include a substrate having a first surface, a second surface opposite from the first surface, and an opening extending from the first surface towards the second surface, and a conductive via extending within the opening and defining at least one capillary channel within the opening adjacent the first surface. The opening can have an inner wall extending away from the first surface. At least one of the capillary channels can have an edge within a first distance from the inner wall in a direction of a plane parallel to and within five microns below the first surface, the first distance being the lesser of one micron and five percent of a maximum width of the opening in the plane, the edge extending along the inner wall to span at least five percent of a circumference of the inner wall. Each capillary channel can have a maximum width in the direction in the plane of less than five microns. 
         [0029]    In one embodiment, the component can also include solder joined to the conductive via within the at least one capillary channel. In a particular example, the component can also include a conductive post extending from an outer contact surface of the conductive via. In an exemplary embodiment, the conductive post can have at least one capillary channel extending into the conductive post from a base surface thereof. The component can also include solder joining the conductive via and the conductive post and extending within the at least one capillary channels of the conductive via and the conductive post. In one example, the solder may not extend onto the first surface of the substrate. 
         [0030]    In accordance with yet another aspect of the invention, a method of fabricating a component can include forming a conductive via extending within an opening in a substrate, the opening extending from a first surface of the substrate towards a second surface opposite from the first surface, and removing material of the conductive via to define a relief channel within the opening adjacent the first surface. The opening can have an inner wall extending away from the first surface, a dielectric material being exposed at the inner wall. The relief channel can have an edge within a first distance from the inner wall in a direction of a plane parallel to and within five microns below the first surface, the first distance being the lesser of one micron and five percent of a maximum width of the opening in the relief plane, the edge extending along the inner wall to span at least five percent of a circumference of the inner wall. 
         [0031]    In a particular embodiment, the substrate can have an active device region adjacent the first surface, and the plane can be located below the active device region. In one embodiment, the substrate can consist essentially of the dielectric material. In a particular example, the substrate can consist essentially of glass or ceramic. In an exemplary embodiment, the substrate can consist essentially of a semiconductor material. The method can also include, before the step of forming the conductive via, forming a layer of the dielectric material overlying the substrate material within the opening, the dielectric layer defining the inner wall of the opening. 
         [0032]    In one example, the opening can be a through opening that extends between the first and second surfaces. In a particular embodiment, the opening can have a tapered shape, the opening having a first width at the first surface and a second width at the second surface, the first and second widths being in a direction parallel to the first surface of the substrate, the first width being less than the second width. In one embodiment, at least a portion of the opening can be bounded by a surface defining a curvilinear cross-sectional shape in a plane that is perpendicular to the first surface of the substrate. In a particular example, the opening can be formed by isotropic etching of the substrate followed by anisotropic etching of the substrate. 
         [0033]    In an exemplary embodiment, the relief channel can be a first relief channel and the plane can be a first plane. The method can also include removing material of the conductive via to define a second relief channel within the opening adjacent the second surface. The second relief channel can have an edge within a second distance from the inner wall in a direction of a second plane parallel to and within five microns below the second surface, the second distance being the lesser of one micron and five percent of a maximum width of the opening in the second plane, the edge of the second relief channel extending along the inner wall to span at least five percent of the circumference of the inner wall. 
         [0034]    In one example, the method can also include depositing a polymer material within the relief channel. In a particular embodiment, the step of depositing the polymer material can be performed such that a portion of an outer contact surface of the conductive via is exposed at an outer surface of the polymer. In one embodiment, the method can also include forming an electrically conductive post in contact with the outer contact surface of the conductive via. In a particular example, the electrically conductive post may not overlie at least one of the relief channels. In an exemplary embodiment, the method can also include forming a plurality of electrically conductive posts in contact with the outer contact surface of the conductive via. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIGS. 1A and 1B  are a side sectional view and a top plan view illustrating a component in accordance with an embodiment of the invention. 
           [0036]      FIGS. 2A-2G  are side sectional views illustrating stages of fabrication in accordance with the embodiment depleted in  FIGS. 1A and 1B . 
           [0037]      FIGS. 2H and 2I  are top plan views illustrating stages of fabrication in accordance with an alternative embodiment of the conductive via shown in  FIGS. 1A and 1B . 
           [0038]      FIGS. 3A and 3B  are a top plan view and a side sectional view illustrating an alternative embodiment of the conductive via shown in  FIGS. 1A and 1B . 
           [0039]      FIGS. 4A and 4B  are a top plan view and a side sectional view illustrating another alternative embodiment of the conductive via shown in  FIGS. 1A and 1B . 
           [0040]      FIGS. 5A-5C  and  6 A- 6 C are top plan views illustrating further alternative embodiments of the conductive via shown in  FIGS. 1A and 1B . 
           [0041]      FIG. 7  is a side sectional view illustrating a component in accordance with yet another embodiment of the invention. 
           [0042]      FIG. 8  is a side sectional view illustrating an alternative embodiment of the component shown in  FIG. 7 , having reduces stress structures at the first and second surfaces of the component. 
           [0043]      FIGS. 9A ,  9 B, and  9 C are side sectional views illustrating alternative embodiments of the component shown in  FIGS. 1A and 1B , having sloped relief channels. 
           [0044]      FIGS. 10A and 10B  are side sectional views illustrating alternative embodiments of the component shown in  FIGS. 1A and 1B , having conductive joining material at the first surface of the component. 
           [0045]      FIG. 11A  is a side sectional view illustrating a component in accordance with still another embodiment of the invention. 
           [0046]      FIG. 11B  is a side sectional view illustrating an alternative embodiment of the component shown in  FIG. 11A , having a conductive pad at the first surface of the component. 
           [0047]      FIG. 12  is a side sectional view illustrating an alternative embodiment of the component shown in  FIG. 11A , having conductive joining material at the first surface of the component. 
           [0048]      FIG. 13  is a side sectional view illustrating a component in accordance with another embodiment of the invention. 
           [0049]      FIGS. 14A-14D  are side sectional views illustrating stages of fabrication in accordance with the embodiment depicted in  FIG. 13 . 
           [0050]      FIG. 15  is a side sectional view illustrating a component in accordance with yet another embodiment of the invention. 
           [0051]      FIGS. 16A-16D  are side sectional views illustrating stages of fabrication in accordance with the embodiment depicted in  FIG. 15 . 
           [0052]      FIGS. 17A and 17B  are side sectional views illustrating alternative embodiments of the component shown in  FIG. 15 . 
           [0053]      FIG. 18  is a side sectional view illustrating a stage of fabrication in accordance with the embodiments depicted in  FIGS. 17A and 17B . 
           [0054]      FIG. 19  is a side sectional view illustrating a component in accordance with another embodiment of the invention. 
           [0055]      FIGS. 20A and 20B  are side sectional views illustrating stages of fabrication in accordance with the embodiment depicted in  FIG. 19 . 
           [0056]      FIGS. 21A-21C  are side sectional views illustrating alternative embodiments of the component shown in  FIG. 19 . 
           [0057]      FIG. 22  is a side sectional views illustrating a stage of fabrication in accordance with any of the embodiments depicted in  FIGS. 21A-21C . 
           [0058]      FIG. 23  is a side sectional view illustrating a component in accordance with yet another embodiment of the invention. 
           [0059]      FIGS. 24A and 24B  are side sectional views illustrating stages of fabrication in accordance with the embodiment depicted in  FIG. 23 . 
           [0060]      FIG. 25  is a side sectional view illustrating a component in accordance with still another embodiment of the invention. 
           [0061]      FIGS. 26A and 26B  are side sectional views illustrating alternative embodiments of the conductive via shown in  FIGS. 3A and 3B . 
           [0062]      FIGS. 27A-27D  are side sectional views illustrating alternative embodiments of the component shown in  FIG. 21A . 
           [0063]      FIG. 28A  is a top perspective view illustrating a component in accordance with yet another embodiment of the invention. 
           [0064]      FIG. 28B  is a top perspective view illustrating an alternative embodiment of the component shown in  FIG. 28A . 
           [0065]      FIG. 29  is a schematic depiction of a system according to one embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0066]    As illustrated in  FIG. 1A , a component  10  can include a substrate  20  having a first surface  21  and a second surface  22  opposite therefrom, and a conductive via  40  disposed within an opening  30  extending from the first surface towards the second surface. 
         [0067]    In some embodiments, the substrate  20  may be a semiconductor chip, a wafer, or the like. The substrate  20  preferably has a coefficient of thermal expansion (“CTE”) less than 10*10 −6 /° C. (or ppm/° C.). In a particular embodiment, the substrate  20  can have a CTE less than 7 ppm/° C. The substrate  20  may consist essentially of an inorganic material such as silicon. The thickness of the substrate  20  between the first surface  21  and the second surface  22  typically is less than 500 μm, and can be significantly smaller, for example, 130 μm, 70 μm or even smaller. In a particular embodiment, the substrate  20  can be made from a material such as semiconductor material, ceramic, glass, liquid crystal polymer, a composite material such as glass-epoxy or a fiber-reinforced composite, a laminate structure, or a combination thereof. 
         [0068]    In one example, the substrate  20  can include a composite material that has an effective CTE that is tunable during fabrication of the substrate to approximately match the CTE of the metal of the conductive vias that extend therein, such as copper or nickel. For example, the substrate  20  can have an effective CTE that is tunable to a value between 10-20 ppm/° C. In a particular embodiment, the substrate  20  can have an effective CTE that is tunable to a value between 15-18 ppm/° C. 
         [0069]    In  FIG. 1A , the directions parallel to the first surface  21  are referred to herein as “horizontal” or “lateral” directions, whereas the directions perpendicular to the first surface are referred to herein as upward or downward directions and are also referred to herein as the “vertical” directions. The directions referred to herein are in the frame of reference of the structures referred to. Thus, these directions may lie at any orientation to the normal or gravitational frame of reference. A statement that one feature is disposed at a greater height “above a surface” than another feature means that the one feature is at a greater distance in the same orthogonal direction away from the surface than the other feature. Conversely, a statement that one feature is disposed at a lesser height “above a surface” than another feature means that the one feature is at a smaller distance in the same orthogonal direction away from the surface than the other feature. 
         [0070]    As used in this disclosure, a statement that an electrically conductive element is “exposed at” a surface of a substrate indicates that the electrically conductive element is available for contact with a theoretical point moving in a direction perpendicular to the surface of the substrate toward the surface of the substrate from outside the substrate. Thus, a terminal or other conductive element which is exposed at a surface of a substrate may project from such surface; may be flush with such surface; or may be recessed relative to such surface and exposed through a hole or depression in the substrate. 
         [0071]    The substrate  20  can further include an insulating dielectric layer  23  overlying the first surface  21  and/or the second surface  22 . Such a dielectric layer can electrically insulate conductive elements from the substrate  20 . This dielectric layer can be referred to as a “passivation layer” of the substrate  20 . The dielectric layer can include an inorganic or organic dielectric material or both. The dielectric layer may include an electrodeposited conformal coating or other dielectric material, for example, a photoimageable polymeric material, for example, a solder mask material. 
         [0072]    In embodiments where the semiconductor element  20  includes a semiconductor substrate, made for example from silicon, one or a plurality of semiconductor devices (e.g., transistors, diodes, etc.) can be disposed in an active device region  24  thereof located at and/or below the first surface  21 . 
         [0073]    In the embodiments described herein, a dielectric layer overlying the first surface  21  and/or the second surface  22  can have a thickness that is substantially less than a thickness of the substrata  20 , such that the substrate can have an effective CTE that is approximately equal to the CTE of the material of the substrate, even if the CTE of the dielectric layer is substantially higher than the CTE of the substrate material. In one example, the substrate  20  can have an effective CTE less than 10 ppm/° C. 
         [0074]    The substrate  20  can include one or more openings  30  extending from the first surface  21  partially or completely through a thickness T of the substrate towards the second surface  22 . In the embodiment shown in  FIG. 1A , the opening  30  extends partially through the substrate  20  between the first and second surfaces  21 ,  22 . The openings  30  can be arranged in any top-view geometric configuration, including for example, an m×n array, each of m and n being greater than 1. 
         [0075]    Each opening  30  includes an inner surface  31  that extends from the first surface  21  at least partially through the substrate  20  at an angle between 0 and 90 degrees to the horizontal plane defined by the first surface. In one example (e.g.,  FIG. 8 ), the inner surface  31  of one or more of the openings  30  can extend between the first surface  21  and the second surface  22 . The inner surface  31  can have a constant slope or a varying slope. For example, the angle or slope of the inner surface  31  relative to the horizontal plane defined by the first surface  21  can decrease in magnitude (i.e., become less positive or less negative) as the inner surface penetrates further towards the second surface  22 . In a particular embodiment, each opening  30  can be tapered in a direction from the first surface  21  towards the second surface  22 . In some examples, each opening  30  can have any three-dimensional shape, including for example, a frusto-conical shape, a cylinder, a cube, a prism, an elliptic paraboloid, a hyperboloid, or a structure bounded by a curvilinear inner surface, among others. As used herein, when a three-dimensional structure is described as having or being bounded by a curvilinear surface, a cross-section of that surface in a plane that is generally perpendicular to the first and second surfaces of the substrate is a curve having a varying slope (e.g., a second order polynomial). 
         [0076]    In particular embodiments, the opening  30  and any of the other openings described herein can have various shapes, as described for example in U.S. patent application Ser. Nos. 12/842,717 and 12/842,651, filed Jul. 23, 2010, which are hereby incorporated by reference herein, and such openings can be formed using exemplary processes as described in the aforementioned applications. 
         [0077]    The opening  30  can include a conductive via  40  disposed therein and extending from the first surface  21  towards the rear surface  22 . In a particular embodiment, first and second conductive vias  40  of a particular component  10  can be connectable to respective first and second electric potentials. The conductive via  40  can include a metal having a relatively high CTE, such as copper, aluminum, tungsten, an alloy including copper, an alloy including nickel, or an alloy including tungsten, among others. In a particular example where a conductive via  40  extends within a substrate  20  that includes a composite material, the substrate can have an effective CTE less than 20 ppm/° C., and the conductive via  40  can extend within a semiconductor region of the substrate. Such a semiconductor region can consist essentially of a material having an effective CTE in a plane of the substrate of no more than than 10 ppm/° C. 
         [0078]    The component  10  can also include an insulating dielectric layer  60  overlying the inner surface  31  of the opening  30  and extending from the first surface  21  towards the second surface  22 , such that the conductive via  40  extends within the insulating dielectric layer. Such an insulating dielectric layer  60  can separate and electrically insulate the conductive via  40  from the material of the substrate  20 , at least within the opening  30 . The insulating dielectric layer  60  and the insulating dielectric layer  23  can be formed together as a single insulating dielectric layer, or they can be formed separately as individual insulating dielectric layers. 
         [0079]    In one example, such an insulating dielectric layer  60  can be conformally coat the inner surface  31  exposed within the opening  30 . The insulating dielectric material  60  can include an inorganic or organic dielectric material or both. In some embodiments, more than one type of insulating dielectric material can be used, such as silicon dioxide and silicon nitride, or a polymer and a nitride. In a particular embodiment, the insulating dielectric material  60  can include a compliant dielectric material, such that the insulating dielectric material has a sufficiently low modulus of elasticity and sufficient thickness such that the product of the modulus and the thickness provide compliancy. 
         [0080]    In the embodiment shown in  FIGS. 1A and 1B , an inward-facing surface of the insulating dielectric layer  60  defines an inner wall  32  of the opening. In embodiments in which the insulating dielectric layer  60  is omitted, the inner wall  32  of the opening can be coincident with the inner surface  31  of the opening. 
         [0081]    In particular embodiments in which the substrate consists essentially of dielectric material (e.g., glass or ceramic), the dielectric layers  60  and/or  23 , or any of the other dielectric layer described herein, may be omitted. The dielectric layers  60  and/or  23  may also be omitted in embodiments in which it is desired that the conductive via  40  is not electrically insulated from the material of the substrate  20 , for example, when the conductive via is configured to carry a reference potential. In a particular embodiment, for example, when the conductive via  40  is configured to carry a reference potential, the substrate  20  can consist essentially of a semiconductor material, a surface of the semiconductor material can be exposed at and can define the inner wall  32  of the opening, and a portion of the conductive via  40  can be in contact with the semiconductor material within the opening  30 . 
         [0082]    The opening  30  can further include a layer  43  that can be a barrier metal layer, an adhesion layer, and/or a seed layer extending between the conductive via  40  and the inner wall  32  of the opening (which, in the embodiment of  FIGS. 1A and 1B , is an inward-facing surface of the insulating dielectric layer  60 ). The layer  43  can extend within the opening  30  from the first surface  21  towards the rear surface  22 . 
         [0083]    The layer  43  can prevent or reduce diffusion of metal from the conductive via  40  into the material of the substrate  20 . The layer  43  can function as a barrier layer to avoid transport of material between the conductive via  40  and the insulating layer  60 . The layer  43  may also or alternatively serve as an adhesion layer. The layer  43  typically has a thickness of less than 100 nanometers, although the thickness in a particular structure can be greater than or equal to 100 nanometers. The layer  43  can include a metal different than the metal or metals of the conductive via  40 . Examples of metals that can be suitable for use in the layer  43  can include nickel, an alloy including nickel, titanium nitride, tantalum nitride, tantalum silicon nitride, tantalum, tungsten silicon nitride, and combinations thereof. 
         [0084]    The conductive via  40  can include one or more outer contact surfaces  50  exposed at either or both of the first and second surfaces  21 ,  22  of the substrate  20  for interconnection with an external element. As shown in  FIG. 1A , each outer contact surface  50  be coated by a layer  51  that can be a barrier metal layer similar to the layer  43  described above. 
         [0085]    The conductive via  40  can define one or more relief channels  55  within the opening adjacent the first surface  21  of the substrate  20 . In a particular embodiment, such as that shown in  FIGS. 1A and 1B , the surfaces of the conductive via  40  that are exposed within the relief channels  55  can be coated by a portion of the layer  51 . In some cases, areas of maximum stress in the component  10  can be at or near the first surface  21  of the substrate  20 , so the presence of the relief channels  55  at or near the first surface can reduce the maximum stress experienced by the component in the vicinity of the conductive vias  40 . 
         [0086]    In a conventional component including conductive vias in a semiconductor substrate, it may be necessary to limit the location of active semiconductor devices within an active device region to be at least three conductive via diameters away from any part of the conductive vias. On the other hand, in a component  10  including a conductive via  40  having a relief channel, the reduced maximum stress experienced by the component near the conductive vias can permit a design where an active device region  24  can extend to a location relatively close to a conductive via. 
         [0087]    For example, in a particular embodiment of the component  10 , an active device region  24  can be located outside of a keep-out zone that extends from the conductive via  40  to a standoff distance D 5  away from any part of the conductive via. In one embodiment, the standoff distance D 5  can be less than three times a maximum width W 1  of the of the opening  30 , the maximum width W 1  extending between opposite portions of the inner wall  32 . In a particular embodiment, the standoff distance D 5  can be less than two times the maximum width W 1  of the opening  30 . In one example, the standoff distance D 5  can be less than the maximum width W 1  of the opening  30 . In an exemplary embodiment, the standoff distance D 5  can be less than one-half the maximum width W 1  of the opening  30 . 
         [0088]    In one embodiment, at least one of the relief channels  55  can have an edge  56  within a first distance D 1  from the inner wall that is the lesser of one micron and five percent of the maximum width W 1  of the opening  30  in a direction D 2  in a relief plane P parallel to the first surface  21  of the substrate  20  and located within a depth D 3  of five microns of the first surface. In one embodiment, one or more of the relief channels  25  can extend below the first surface  21  of the substrate  20  to a depth D 4  that is at most two times the maximum width W 1  of the opening  30 . In a particular example, the depth D 4  can be at most equal to the maximum width W 1  of the opening  30 . In one example, the depth D 4  can be at most half the maximum width W 1  of the opening  30 . 
         [0089]    The edge  56  of at least one of the relief channels  55  can extend a second distance in a circumferential direction C along the inner wall  32  of at least five percent of a circumference of the inner wall. As shown in  FIG. 1B , the edge  56  of the outer one of the relief channels  55  extends around the entire circumference of the inner wall  32 , but that need not be the case. 
         [0090]    In a particular embodiment, the component  10  having the relief channels  55  can be configured to reduce resulting stress emanating from the conductive via  40  within the relief plane P to a level below 200 MPa when external stress is applied to the component. 
         [0091]    A method of fabricating the component  10  ( FIGS. 1A and 1B ) will now be described, with reference to  FIGS. 2A-2G . Referring to  FIG. 2A , to form one or more openings  30  extending from the first surface  21  towards the second surface  22  of the substrate  20 , material can be removed from the first surface of the substrate. 
         [0092]    The opening  30  can be formed for example, by selectively etching the substrate  20 , after forming a mask layer where it is desired to preserve remaining portions of the first surface  21 . For example, a photoimageable layer, e.g., a photoresist layer, can be deposited and patterned to cover only portions of the first surface  21 , after which a timed etch process can be conducted to form the opening  30 . 
         [0093]    The inner surfaces  31  of the opening  30 , extending downwardly from the first surface  21  towards the second surface  22 , may be sloped, i.e., may extend at angles other a normal angle (right angle) to the first surface. Wet etching processes, e.g., isotropic etching processes and sawing using a tapered blade, among others, can be used to form an opening  30  having sloped inner surfaces  31 . Laser dicing, mechanical milling, among others, can also be used to form an opening  30  having sloped inner surfaces  31 . 
         [0094]    Alternatively, instead of being sloped, the inner surface  31  of each opening  30  may extend in a vertical or substantially vertical direction downwardly from the first surface  21  substantially at right angles to the first surface (as shown in  FIG. 1A ). Anisotropic etching processes, laser dicing, laser drilling, mechanical removal processes, e.g., sawing, milling, ultrasonic machining, among others, can be used to form openings  30  having essentially vertical inner surfaces  31 . 
         [0095]    In a particular embodiment, the opening  30  can be formed, for example, by first using an anisotropic etch process such as a fast DRIE etch or a reactive ion etch to produce an initial opening having a relatively rough initial inner surface, and then using a chemical etch or electropolishing to remove the roughness or scallops extending along the initial inner surface. In one example, the opening  30  can be formed, for example, by isotropic etching of the substrate followed by anisotropic etching of the substrate. 
         [0096]    A portion of a passivation layer (e.g., the insulating dielectric layer  23  shown in  FIG. 1A ) overlying the first surface  21  of the substrate  20  can also removed during the formation of the opening  30 , and such portion can be etched through during the etching of the substrate, or as a separate etching step. Etching, laser drilling, mechanical milling, or other appropriate techniques can be used to remove the portion of such a passivation layer. 
         [0097]    After formation of the opening  30 , the insulating dielectric layer  60  shown in  FIG. 1A  can be deposited overlying or coating the inner surfaces  31  of the opening  30 , such that the conductive via  40  will extend within the insulating dielectric layer when it are deposited within the opening. As described above, the dielectric layers  23  and  60  can be deposited in a single process. In order to simplify the figures used in describing the method of forming the component  10 , the insulating dielectric layers  23  and  60  are not shown in  FIGS. 2A-2G . 
         [0098]    In a particular embodiment, a mask can be applied to portions of the first surface  21  of the substrate  20  having openings  30  in which it is desired not to form such an insulating dielectric layer  60 . Such uncoated ones of the openings  30  can be later filled with conductive vias  40  that have portions directly contacting material of the substrate  20 . Such a conductive via  40  can be electrically coupled to a ground electric potential. In a particular embodiment in which the substrate consists essentially of dielectric material (e.g., glass or ceramic), the dielectric layers  60  and/or  23 , or any of the other dielectric layers described herein, may be partially or entirely omitted. In such embodiments having one or more openings  30  without dielectric layers  60  and/or  23 , the inner wall  32  of such an opening  30  can be coincident with the inner surface  31  of the opening. 
         [0099]    Various methods can be used to form such an insulating dielectric layer  60  overlying the inner surfaces  31  of the opening  30 , and such methods are described below. In particular examples, chemical vapor deposition (CVD) or atomic layer deposition (ALD) can be used to deposit a thin insulating dielectric layer overlying the inner surfaces  31  of the openings  30 . In one example, tetraethylorthosilicate (TEOS) can be used during a low-temperature process for depositing such an insulating dielectric layer. In exemplary embodiments, a layer of silicon dioxide, borophoshosilicate glass (BPSG), borosilicate glass (BSG), or phosphosilicate glass (PSG) can be deposited overlying the inner surfaces  31  of the openings  30 , and such glass can be doped of undoped. 
         [0100]    In one example, a flowable dielectric material can be applied to the first surface  21  of the substrate  20 , and the flowable material can then more evenly distributed across the inner surfaces  31  of the opening  30  during a “spin-coating” operation, followed by a drying cycle which may include heating. In another example, a thermoplastic film of dielectric material can be applied to the first surface  21  after which the assembly is heated, or is heated in a vacuum environment, i.e., placed in an environment under lower than ambient pressure. 
         [0101]    In still another example, the assembly including the substrate  20  can be immersed in a dielectric deposition bath to form a conformal dielectric coating or insulating dielectric material  60 . As used herein, a “conformal coating” is a coating of a particular material that conforms to a contour of the surface being coated, such as when the insulting dielectric material  60  conforms to a contour of the inner surfaces  31  of the opening  30 . An electrochemical deposition method can be used to form the conformal dielectric material  60 , including for example, electrophoretic deposition or electrolytic deposition. 
         [0102]    In one example, an electrophoretic deposition technique can be used to form a conformal dielectric coating, such that the conformal dielectric coating is only deposited onto exposed conductive and semiconductive surfaces of the assembly. During deposition, the semiconductor device wafer is held at a desired electric potential and an electrode is immersed into the bath to hold the bath at a different desired potential. The assembly is then held in the bath under appropriate conditions for a sufficient time to form an electrodeposited conformal dielectric material  60  on exposed surfaces of the substrate that are conductive or semiconductive, including but not limited to along the inner surfaces  31  of the opening  30 . Electrophoretic deposition occurs so long as a sufficiently strong electric field is maintained between the surface to be coated thereby and the bath. As the electrophoretically deposited coating is self-limiting in that after it reaches a certain thickness governed by parameters, e.g., voltage, concentration, etc. of its deposition, deposition stops. 
         [0103]    Electrophoretic deposition forms a continuous and uniformly thick conformal coating on conductive and/or semiconductive exterior surfaces of the substrate  20 . In addition, the electrophoretic coating can be deposited so that it does not form on a remaining passivation layer  23  overlying the first surface  21  of the substrate  20 , due to its dielectric (nonconductive) property. Stated another way, a property of electrophoretic deposition is that it does not normally form on a layer of dielectric material, and it does not form on a dielectric layer overlying a conductor provided that the layer of dielectric material has sufficient thickness, given its dielectric properties. Typically, electrophoretic deposition will not occur on dielectric layers having thicknesses greater than about 10 microns to a few tens of microns. A conformed dielectric material  60  can be formed from a cathodic epoxy deposition precursor. Alternatively, a polyurethane or acrylic deposition precursor could be used. A variety of electrophoretic coating precursor compositions and sources of supply are listed in Table 1 below. 
         [0000]    
       
         
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
             
             
               
                 ECOAT NAME 
                 POWERCRON 645 
                 POWERCRON 648 
                 CATHOGUARD 325 
               
               
                   
               
             
          
           
               
                 MANUFACTURERS 
               
             
          
           
               
                 MFG 
                 PPG 
                 PPG 
                 BASF 
               
               
                 TYPE 
                 CATHODIC 
                 CATHODIC 
                 CATHODIC 
               
               
                 POLYMER BASE 
                 EPOXY 
                 EPOXY 
                 EPOXY 
               
               
                 LOCATION 
                 Pittsburgh, PA 
                 Pittsburgh, PA 
                 Southfield, MI 
               
             
          
           
               
                 APPLICATION DATA 
               
             
          
           
               
                 Pb/Pf-free 
                 Pb-free 
                 Pb or Pf-free 
                 Pb-free 
               
               
                 HAPs, g/L 
                   
                 60-84 
                 COMPLIANT 
               
               
                 VOC, g/L (MINUS WATER) 
                   
                 60-84 
                 &lt;95  
               
               
                 CURE 
                 20 min/175 C. 
                 20 min/175 C. 
               
             
          
           
               
                 FILM PROPERTIES 
               
             
          
           
               
                 COLOR 
                 Black 
                 Black 
                 Black 
               
               
                 THICKNESS, μm 
                 10-35 
                 10-38 
                 13-36 
               
               
                 PENCIL HARDNESS 
                   
                 2H+ 
                 4H 
               
             
          
           
               
                 BATH CHARACTERISTICS 
               
             
          
           
               
                 SOLIDS, % wt. 
                 20 (18-22)  
                 20 (19-21)  
                 17.0-21.0 
               
               
                 pH (25 C.) 
                 5.9 (5.8-6.2) 
                 5.8 (5.6-5.9) 
                 5.4-6.0 
               
               
                 CONDUCTIVITY (25 C.) μS 
                 1000-1500 
                 1200-1500 
                 1000-1700 
               
               
                 P/B RATIO 
                 0.12-0.14 
                 0.12-0.16 
                 0.15-0.20 
               
               
                 OPERATION TEMP., C. 
                 30-34 
                 34 
                 29-35 
               
               
                 TIME, sec 
                 120-180 
                  60-180 
                 120+ 
               
               
                 ANODE 
                 SS316 
                 SS316 
                 SS316 
               
               
                 VOLTS 
                   
                 200-400 
                 &gt;100  
               
               
                   
               
               
                 ECOAT NAME 
                 ELECTROLAC 
                 LECTRASEAL DV494 
                 LECTROBASE 101 
               
               
                   
               
             
          
           
               
                 MANUFACTURERS 
               
             
          
           
               
                 MFG 
                 MACDERMID 
                 LVH COATINGS 
                 LVH COATINGS 
               
               
                 TYPE 
                 CATHODIC 
                 ANODIC 
                 CATHODIC 
               
               
                 POLYMER BASE 
                 POLYURETHANE 
                 URETHANE 
                 URETHANE 
               
               
                 LOCATION 
                 Waterbury, CT 
                 Birmingham, UK 
                 Birmingham, UK 
               
             
          
           
               
                 APPLICATION DATA 
               
             
          
           
               
                 Pb/Pf-free 
                   
                 Pb-free 
                 Pb-free 
               
               
                 HAPs, g/L 
               
               
                 VOC, g/L (MINUS WATER) 
               
               
                 CURE 
                 20 min/149 C. 
                 20 min/175 C. 
                 20 min/175 C. 
               
             
          
           
               
                 FILM PROPERTIES 
               
             
          
           
               
                 COLOR 
                 Clear (+dyed) 
                 Black 
                 Black 
               
               
                 THICKNESS, μm 
                   
                 10-35 
                 10-35 
               
               
                 PENCIL HARDNESS 
                 4H 
               
             
          
           
               
                 BATH CHARACTERISTICS 
               
             
          
           
               
                 SOLIDS, % wt. 
                 7.0 (6.5-8.0) 
                 10-12 
                  9-11 
               
               
                 pH (25 C.) 
                 5.5-5.9 
                 7-9 
                   4.3 
               
               
                 CONDUCTIVITY (25 C.) μS 
                 450-600 
                 500-800 
                 400-800 
               
               
                 P/B RATIO 
               
               
                 OPERATION TEMP., C. 
                 27-32 
                 23-28 
                 23-28 
               
               
                 TIME, sec 
                   
                   
                  60-120 
               
               
                 ANODE 
                 SS316 
                 316SS 
                 316SS 
               
               
                 VOLTS 
                 40, max 
                   
                  50-150 
               
               
                   
               
             
          
         
       
     
         [0104]    In another example, the dielectric material  60  can be formed electrolytically. This process is similar to electrophoretic deposition, except that the thickness of the deposited layer is not limited by proximity to the conductive of semiconductive surface from which it is formed. In this way, an electrolytically deposited dielectric layer can be formed to a thickness that is selected based on requirements, and processing time is a factor in the thickness achieved. 
         [0105]    As shown in  FIG. 2A , the layer  43  can then be formed overlying the inner surfaces  31  of the opening  30  (and the insulating dielectric layers  60  and  23  if they are present). For example, the layer  43  or portions of the layer  43  can be formed using atomic layer deposition (ALD), physical vapor deposition (PVD), or electroless or electrolytic deposition methods. Then, the conductive via  40  can be formed overlying and electrically coupled to the layer  43 . As shown, material of the layer  43  and the conductive via  40  can be deposited onto portions of the first surface  21  that are outside of the opening  30 . 
         [0106]    To form any one of the layer  43  and the conductive via  40 , an exemplary method involves depositing a metal layer by one or more of sputtering a primary metal layer onto exposed surfaces of the insulating dielectric layers  60  and/or  23 , plating, or mechanical deposition. Mechanical deposition can involve the directing a stream of heated metal particles at high speed onto the surface to be coated. In other embodiments, sub-micron metal powder can be screened or selectively screened into the cavities, for example, using a pulse laser, and the metal flow will fill the cavities. This step can be performed by blanket deposition onto the insulating dielectric layers  60  and/or  23 , for example. 
         [0107]    Referring now to  FIG. 2B , an initial exposed surface  14  ( FIG. 2A ) of the conductive via  40  can be planarized so that the resulting exposed surface  45  is closer to the first surface  21  of the substrate  20 . The initial exposed surface  44  of the conductive via  40  can be planarized by various exemplary methods. In one embodiment, a grinding process can be used, for example, to planarize the initial exposed surface  44 . The grinding process can remove both a portion of the material of the conductive via  40  above the first surface  21  of the substrate  20 . The initial exposed surface  44  can also be planarized by lapping, polishing, or by high-precision milling. 
         [0108]    In a particular example, chemical mechanical polishing (“CMP”) can be used to planarize the initial exposed surface  44  of the conductive via  40 . An exemplary CMP process can include sanding the initial exposed surface  44  with an abrasive pad, using a slurry. Such a slurry can typically include an oxidizing agent and a passivation agent. An exemplary CMP process can include using an abrasive slurry, including, for example, a micro-silica paste, to planarize the initial exposed surface  44 . 
         [0109]    Referring now to  FIG. 2C , a mask layer  25  can be formed overlying an exposed surface  45  of the conductive via  40  at the first surface  21  of the substrate  20 . The mask layer  25  can have gaps  26  at the areas of the exposed surface  45  where it is desired to form the relief channels  55  and the outer contact surfaces  50  adjacent the relief channels. For example, a photoimageable layer, e.g., a photoresist layer, can be deposited and patterned to cover portions of the exposed surface  45 . 
         [0110]    As shown in  FIG. 2D , material of the conductive via  40  can be removed from the exposed surface  45  at the gaps  26  within the mask layer  25 , thereby forming the relief channels  55  and the outer contact surfaces  50 . Portions of the material of the conductive via  40  can be removed, for example, using an etching process or any of the other material removal processes described above with reference to forming the opening  30 . 
         [0111]    Referring now to  FIG. 2E , the mask layer  25  ( FIG. 2D ) can be removed, leaving the relief channels  55  and the outer contact surfaces  50  adjacent the relief channels. In  FIG. 2F , if it is desired to remove excess metal of the layer  43  and/or the conductive via  40  that overlies the first surface  21  of the substrate  20  outside of the opening  30 , such excess metal can be removed via any of the removal processes described above with reference to forming the opening  30  or planarizing the initial exposed surface  44  of the conductive via  40 . 
         [0112]    Then, as shown in  FIG. 2G , the outer contact surfaces  50  and the exposed surfaces  52  of the relief channels  55  can be coated by a layer  51  that can be a barrier metal layer similar to the layer  43  described above, a passivation layer, or a coupling layer such as an adhesion layer to make the via  40  configured to receive an additional conductive layer thereon. Such a layer  51  can be deposited via any of the metal deposition processes described above with reference to the conductive via  40  or the layer  43 . 
         [0113]    In one alternative method, material of the conductive via  40  can be removed from the exposed surface  45  without using a mash layer  25  as shown in  FIG. 2C . In such a method, the exposed surface  45  of the conductive via  40  can be polished, for example, using a CMP process as described above, until the interface between the conductive via and the layer  43  (e.g. a barrier metal layer) is exposed at the first surface  21  of the substrate  20 . Then, the exposed surface  45  can be etched. Etching of the exposed surface  45  of conductive via  40  can progress more quickly at the interface between the conductive via and the layer  43  than at other portions of the exposed surface, thereby forming a channel  55  within the conductive via adjacent to this interface. An example conductive via  940   a  resulting from this alternative method is shown and described below with reference to  FIG. 9A . After the channel  53  is formed, the method can proceed as described above with reference to  FIG. 2G . 
         [0114]    In another alternative method, shown in  FIGS. 2H and 2I , material of a conductive via  40 ′ can be deposited into the opening  30  such that one or more channel portions or voids  55 ′ are formed at the radial periphery  40   a  of the conductive via adjacent the outer contact surface  50 ′. As shown in  FIG. 2H , an insulating dielectric layer  60  such as that described above with reference to  FIG. 1A  can be deposited overlying or coating the inner surfaces  31  of the opening  30 . Then, a barrier layer  43   a  can be formed as described above overlying the dielectric layer  60 , and a seed layer  43   b  can be formed overlying the barrier layer  43   a.  A mask layer can be applied to an exposed surface of the seed layer  43   b  at the first surface  21 , the mask layer can be patterned, and the seed layer can be etched to form gaps  43   c  in the seed layer between adjacent portions of the mask layer. The gaps  43   c  can extend down below the first surface  21  to a desired depth, such as the depth D 4  shown in  FIG. 1A . As can be seen in  FIG. 2H , there can be a plurality of discontinuous gaps  43   c  distributed in a circumferential direction C along the seed layer  43   b,  but that need not be the case. 
         [0115]    As shown in  FIG. 2I , the conductive via  40 ′ can then be formed overlying and electrically coupled to the seed layer  43   b.  The metal of the conductive via  40 ′ will deposit more quickly on the seed layer  43   b  than on the portions of the barrier layer  43   a  exposed within the gaps  43   c,  so that as the conductive via is formed, the gaps will become channel portions or voids  55 ′. As can be seen in  FIG. 2I , there can be a plurality of discontinuous channel portions  55 ′ distributed in the circumferential direction C about the radial periphery  40   a  of the conductive via  40 ′, but that need not be the case. In a particular example, the channel portions  55 ′ can have a width W 4  in a radial direction R of less than one micron. In an exemplary embodiment, the width W 4  can be less than 0.5 microns. 
         [0116]      FIGS. 3A through 6C  illustrate variations of the conductive via  40  of  FIGS. 1A and 1B  having alternate configurations. In order to simplify the figures, the optional insulating dielectric layers  23  and  60  and the optional barrier layers  43  and  51  shown un  FIG. 1A  are not shown in  FIGS. 3A through 6C . The conductive via  340  shown in  FIGS. 3A and 3B  is the same as the conductive via  40  described above, except that the conductive via  340  includes a single relief channel  335  having an edge  356  extending around the entire circumference of the inner wall  332  of the opening  330 . 
         [0117]    The conductive via  440  shown in  FIGS. 4A and 4B  is the same as the conductive via  40  described above, except that the conductive via  440  includes a first relief channel  455   a  having an edge  456  extending around the entire circumference of the inner wall  432  of the opening  430 , and a second relief channel  455   b  located approximately at the center of the conductive via  440 . The second relief channel  455   b  can be a relief region having only a single outer edge  457 , such that no portion of the outer contact surfaces  450  is located within the area circumscribed by the outer edge  457 . 
         [0118]    The conductive via  540   a  shown in  FIG. 5A  is the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive via  540   a  includes a relief channel  555   a  having an oblong or oval shape, wherein the relief channel defines a first dimension L 1  that is greater than a second dimension L 2 , the first and second dimensions being located in the relief plane P shown and described with respect to  FIG. 1A . As shown in  FIG. 5A , the conductive via  540   a  can have an oblong or oval cross-sectional shape in a plane generally parallel to the first surface of the substrate. In other embodiments, the invention contemplates other cross-sections of conductive vias having relief channels, including for example, square, rectangular, triangular, hexagonal, non-circular, curvilinear, or any other shape. 
         [0119]    The conductive via  540   b  shown in  FIG. 5B  is the same as the conductive via  540   a  described above with respect to  FIG. 5A , except that the relief channel  555   b  of the conductive via  540   b  has a first width W 2  at a first side of the conductive via that is greater that a second width W 3  at a second opposite side of the conductive via, the first and second widths being located in the relief plane P shown in  FIG. 1A . 
         [0120]    The conductive via  540   c  shown in  FIG. 5C  is the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive via  540   c  includes a relief channel  555   c  having an irregularly-shaped inner edge  557  opposite the outer edge  556 . In other embodiments, the invention contemplates relief channels having other inner edge shapes, including for example, square, rectangular, triangular, hexagonal, curvilinear, or any other shape. 
         [0121]    The conductive via  640   a  shown in  FIG. 6A  is the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive via  640   a  includes a first relief channel  655   a  having an edge  656  extending around the entire circumference of the inner wall  632  of the opening  630 , and a second relief channel  655   a ′ extending through the center of the conductive via  640  between opposing sides of the first relief channel. 
         [0122]    The conductive via  640   b  shown in  FIG. 6B  is the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive via  640   b  includes a plurality of discrete relief channels  655   b  separated from one another along the circumference of the inner wall  632  of the opening  630 , the relief channels  655   b  being distributed about the circumference of the inner wall of the opening. Each of the discrete relief channels  655   b  defines an edge  656   b  that extends around a portion of the circumference of the inner wall  632  of the opening  630 . As shown in  FIG. 6B , the conductive via  640   b  can have eight relief channels  655   b.  In other embodiments, the conductive via  640   b  can have any number of relief channels  655   b,  including, for example, two, three, four, six, ten, twelve, or twenty relief channels. 
         [0123]    The conductive via  640   c  shown in  FIG. 6C  is the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive via  640   c  includes a relief channel  665   c  that only extends around a portion of the circumference of the inner wall  632  of the opening  630 . As shown in  FIG. 6C , the relief channel  655   c  can extend around approximately 50% of the circumference of the inner wall  632  of the opening  630 . In other examples, the relief channel  655   c  can extend around any portion of the circumference of the inner wall  632  of the opening  630 , including, for example, 5%, 10%, 20%, 33%, 66%, or 75%. 
         [0124]      FIGS. 7 through 12  illustrate further variations of the conductive via  40  of  FIGS. 1A and 1B  having alternate configurations. Similar to  FIGS. 3A through 6C , the optional insulating dielectric layers  23  and  60  and the optional barrier layers  43  and  51  are not shown in  FIGS. 7 through 12 , except that  FIG. 9A  shows a barrier layer  943 , and  FIG. 10B  shows a barrier layer  1051 . The conductive via  740  shown in  FIG. 7  is an alternative side sectional view of the conductive via  40  shown in  FIG. 1B . The conductive via  740  has outer contact surfaces  750  that extend above the first surface  721  of the substrate  720 . 
         [0125]      FIG. 8  shows a variation of the conductive via of  FIG. 7  having relief channels  855  in both ends of the conductive via  840  at each of the respective first and second surfaces  821 ,  822  of the substrate  820 . The conductive via  840  is disposed in a through-opening  830  that extends through a thickness of the substrate  820  from the first surface  821  to the second surface  822 . In a particular embodiment (not shown), a conductive via having relief channels in only one end of the conductive via can be disposed within a through-opening. In such an embodiment, the other end of the conductive via that does not contain the relief channels can have any configuration, including, for example, a flat conductive contact surface or a conductive post exposed at the respective surface of the substrate. 
         [0126]      FIGS. 9A and 9B  show conductive vias  940   a  and  940   b,  respectively. The conductive vias  940   a  and  940   b  are the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive vias  940   a  and  940   b  each include a relief channel  955  having a tapered inner edge  957 , the tapered inner edge not being perpendicular to the first surface  921  of the substrate  920 . In the embodiments shown in  FIGS. 9A and 9B , the tapered inner edge  957  is not parallel to the outer edge  956  of the relief channel  955 , and the outer edge  956  is perpendicular to the first surface  921  of the substrate  920 . The conductive via  940   a  of  FIG. 9A  has a barrier or seed layer  943  (such as the layer  43  described above) surrounding the conductive via, while the conductive via  940   b  of  FIG. 9B  is shown without such a barrier or seed layer. 
         [0127]      FIG. 9C  shows a conductive via  940   c  that is the same as the conductive via  940   a  described above with respect to  FIG. 9A , except that the substrate  921  also includes an outer relief channel  958  adjacent an insulating dielectric layer  960 . In one example, the outer relief channel  958  can be filled with a low-k insulating dielectric material  961  such as that commonly used in semiconductor manufacturing. Other dielectric materials  961  may be deposited to fill the outer relief channel  958  which, in some cases, may have a Young&#39;s modulus lower than the Young&#39;s modulus of the material of the substrate  920  (e.g., semiconductor material) or the material of the insulating dielectric layer  960 , such that a degree of compliancy is achieved. The outer relief channel  958  can extend to a depth D 8  below the first surface  921  of the substrate  920 . In a particular embodiment, the depth D 8  to which the outer relief channel  958  extends can be greater than a depth D 7  to which the relief channel  955  extends below the first surface  921  of the substrate  920 , although that need not be the case. 
         [0128]    In one example, the outer relief channel  958  can be etched into a portion of the substrate  920  adjacent the insulating dielectric layer  960 . In an exemplary embodiment, the outer relief channel  958  can be etched into both a portion or the substrate  920  and a portion of the insulating dielectric layer  960 . In a particular example, the outer relief channel  958  can be etched into the substrate  920  using reactive ion etching, and the relief channel  955  can be etched into the material of the conductive via  940   c  using a chemical etching process. The outer relief channel  958  can be a single continuous relief channel, or it can be a plurality of discrete relief channels  958  separated from one another along the outer circumference of the insulating dielectric layer  960 , the relief channels  950  being distributed about the outer circumference of the insulating wall  960 . 
         [0129]      FIGS. 10A and 10B  show conductive vias  1040   a  and  1040   b,  respectively. The conductive vias  1040   a  and  1040   b  are the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive vias  1040   a  and  1040   b  each include a conductive joining material (e.g., solder, a conductive adhesive, or a conductive paste) overlying at least the outer contact surface  1050  of the conductive via. 
         [0130]    Connection between the conductive vias  1040   a  or  1040   b  (or any of the other conductive elements described herein) and components external to the substrate  1020  can be through the respective conductive joining material  1011   a  or  1011   b.  Such conductive joining material can comprise a fusible metal baying a relatively low melting temperature, e.g., solder, tin, or a eutectic mixture including a plurality of metals. Alternatively, such conductive joining material can include a wettable metal, e.g., copper or other noble metal or non-noble metal having a melting temperature higher than that of solder or another fusible metal. Such wettable metal can be joined with a corresponding feature, e.g., a fusible metal feature of an interconnect element. In a particular embodiment, such conductive joining material can include a conductive material interspersed in a medium, e.g., a conductive paste, e.g., metal-filled paste, solder-filled paste or isotropic conductive adhesive or anisotropic conductive adhesive. 
         [0131]    The conductive via  1040   a  of  FIG. 10A  has a conductive joining material  1011   a  adjacent the outer contact surface  1050  of the conductive via, but the conductive joining material does not extend into the relief channel  1055 . In embodiments such as that shown in  FIG. 10A  where the relief channel  1055  is left unfilled, when the conductive via  1040   a  is joined with another conductive element, the relief channel  1055  can serve as a moat to receive excess conductive joining material  1011   a  that can be squeezed out from between the outer contact surface  1050  and a confronting contact surface of another conductive element. 
         [0132]    Having excess conductive joining material  1011   a  flow into the relief channel  1055  can help to prevent the conductive joining material from flowing onto the first surface  1021  of the substrate  1020  and potentially shorting out adjacent conductive vias  1040   a  (i.e., creating a direct electrically conductive path between adjacent conductive vias). By reducing the tendency of excess conductive joining material  1011   a  to flow onto the first surface  1021  of the substrate  1020 , adjacent conductive vias  1040   a  can be spaced closer together without having adjacent conductive vias short out. Such a design can improve reliability or the component for a given spacing or pitch between adjacent conductive vias. Also, such a design can allow a reduced pitch (spacing between) of bonding structures such as conductive posts or exposed pads of the conductive vias  1040   a,  without having excess conductive joining material  1011   a  short out adjacent ones of the bonding structures. 
         [0133]    The conductive via  1040   b  of  FIG. 10B  has a conductive joining material  1011   b  overlying the outer contact surface  1050 , overlying a portion of the first surface  1021  of the substrate  1020 , and extending into the relief channel  1055 . The conductive via  1040   b  also has a barrier layer  1051  (such as the layer  51  described above) that can extend between the conductive via and the conductive joining material  1011   b.    
         [0134]    The conductive via  1140  shown in  FIG. 11A  is the same as the conductive via  40  described above with respect to  FIGS. 1A and 1B , except that the conductive via  1140  has a low stress material  1112  disposed in the relief channels  1155  at the first surface  1121  of the substrate  1120 . The low stress material  1112  can be conductive (e.g., solder or a conductive adhesive paste), nonconductive (e.g., a polymer or another dielectric material), or a porous conductive or nonconductive material such as a polymer foam. Such a material can have a low modulus of elasticity, or the material can have enough collapsible pores that can compress under a load. 
         [0135]    In one example, one or more of the relief channels  1155  can be capillary channels, each capillary channel having a maximum width in a direction in the relief plane P shown and described with respect to  FIG. 1A  of less than five microns. In an embodiment where the low stress material  1112  is solder, such capillary channels can draw solder away from the outer contact surface  1150  of the conductive via  1140  when another conductive structure (e.g., the conductive post  2741   b  shown in  FIG. 27B ) is joined to the conductive via, such that a reduced volume of solder can be used to join the conductive via and the conductive structure to one another. The presence of the capillary channels can prevent solder from being squeezed out onto the first surface  1121  when another conductive structure is joined to the conductive via  1140 . 
         [0136]    In an example where a conductive post such as the conductive post  2741   b  shown in  FIG. 27B  is joined to the conductive via  1140 , a base of the conductive post can be joined to the outer contact surface  1150  of the conductive via. Such a conductive post can have at least one capillary channel extending into the conductive post from a base surface thereof adjacent the outer contact surface  1150 . In such an embodiment, the capillary channels in both the conductive via  1140  and the conductive post joined thereto can draw solder away from the interface between the conductive via and the conductive post, and a reduced volume of solder can be used to join the conductive via and the conductive post to one another. The presence of the capillary channels in both be conductive via and the conductive post can prevent solder from extending onto the first surface  1121  when the conductive post is joined to the conductive via  1140 . 
         [0137]    The conductive via  1140 ′ shown in  FIG. 11B  is the same as the conductive via  1140  described above with respect of  FIG. 11A , except that the conductive via  1140 ′ has a conductive pad  1159  overlying the relief channels  1155  and the outer contact surface  1150  at the first surface  1121  of the substrate  1120 . Such a conductive pad  1159  can be exposed at the first surface  1121  of the substrate  1120  for interconnection with a conductive element of another component. As shown in  FIG. 11B , the conductive pad  1159  can completely seal the relief channels  1150  at the first surface  1121 . In some embodiments, the conductive pad  1159  can partially seal one or more of the relief channels  1155 . 
         [0138]    In a particular example, the conductive pad  1159  can seal one or more of the relief channels  1155  at the first surface  1121 , enclosing a void  1113  within at least some of the sealed relief channels. In one embodiment, also illustrated in  FIG. 11B , a low stress material  1112 , such as solder or a polymer, can fill one or more of the relief channels  1155  that are sealed by the conductive pad  1159 . The conductive pad  1159  can be plated onto the outer contact surface  1150  and across the relief channels  1155 , such that the metal material of the conductive pad only partially extends into one or more of the relief channels, as shown in  FIG. 11B , thereby leaving voids  1113  within at least some of the relief channels. 
         [0139]    The conductive via  1240  shown in  FIG. 12  is the same as the conductive via  1140  described above with respect to  FIG. 11A , except that the conductive via  1240  has a low stress material  1212  disposed in relief channels  1255  at both the first surface  1221  and the second surface  1222  of the substrate  1220 . The low stress material  1212  can be conductive or nonconductive. 
         [0140]    The conductive via  1240  can further include a conductive joining material  1211  overlying the outer contact surfaces  1250 , overlying a portion of the first surface  1221  of the substrate  1220 , and overlying the low stress material  1212  that is disposed in the relief channels  1255 . In a particular embodiment, the conductive joining material  1211  can be the same material as the low stress material  1212 , and in such an embodiment, the conductive joining material and the low stress material at the first surface  1221  of the substrate  1220  can be deposited as a single continuous conductive joining material region. In a particular example, the low stress material  1212  can serve to prevent the conductive joining material  1211  from flowing into the relief channel a  1255  when an external structure is joined with the conductive via  1240  using the conductive joining material. 
         [0141]    In another example, a porous low stress material  1212  can be used to prevent the conductive joining material  1211  from contacting structures at the first surface  1221  of the substrate  1220  that are located near the conductive via  1240 . In such an embodiment, when an external structure is joined with the conductive via  1240  using the conductive joining material  1211 , the conductive joining material can flow into the pores of the low stress material rather than flowing onto the first surface  1221 . 
         [0142]      FIG. 13  shows a conductive via  1340  that is the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive via  1340  includes a conductive joining material  1311  overlying the outer contact surface  1350  of the conductive via and extending into the relief channel  1355 . The conductive via  1340  also has a barrier layer  1351  (such as the layer  51  described above) that can extend between the conductive via and the conductive joining material  1311 . The outer contact surface  1350  can be recessed below the first surface  1321  of the substrate  1320  by a distance D 5 . In the embodiment shown in  FIG. 13 , the conductive joining material  1311  does not overlie the first surface  1321  of the substrate  1320 . 
         [0143]    Similar to the embodiment shown in  FIG. 10A , when the conductive via  1340  is joined with another conductive element, having the outer contact surface  1350  of the conductive via recessed below the first surface  1321  of the substrate  1320  can help prevent the conductive joining material  1311  from flowing onto the first surface and potentially shorting out adjacent conductive vias  1340 . In the example shown in  FIG. 13 , the conductive joining material  1311  extends above the first surface  1321  of the substrate  1320 , but that need not be the case. For example, in other embodiments, the conductive joining material  1311  may have an exposed surface that is recessed below the first surface  1321  of the substrate  1320 . Similar to  FIGS. 3A through 6C , the optional insulating dielectric layers  23  and  60  and the optional barrier layer  43  is not shown in  FIGS. 13 through 14D . 
         [0144]    A method of fabricating the component  1310  ( FIG. 13 ) will now be described, with reference to  FIGS. 14A-14D . The method steps of  FIGS. 2A-2G  can be used to form the opening  1330  extending from the first surface  1321  into the substrate  1320 , the conductive via  1340 , the relief channels  1355 , and the layer  1351  shown in  FIG. 14A . Referring now to  FIG. 14B , a mask layer  1325  can be deposited overlying the barrier layer  1351  and portions of the first surface  1321  of the substrate  1320 . The mask layer  1325  can be patterned, and then, as shown in  FIG. 14C , gaps  1326  can be formed through the mask layer to expose the barrier layer  1351  overlying one or more conductive vias  1340 . 
         [0145]    Subsequently, as shown in  FIG. 14D , the conductive joining material  1311  can be deposited into the gaps  1326 , such that the conductive joining material is in contact with the barrier layer  1351  and extends into the relief channels  1355 . Finally, referring again to  FIG. 13 , the remaining portions of the mask layer  1325  can be removed from the first surface  1321  of the substrate  1320 , leaving a conductive joining material  1311  that extends above the first surface of the substrate. 
         [0146]      FIG. 15  shows a conductive via  1540  that is the same as the conductive via  1340  described above with respect to  FIG. 13 , except that the conductive via  1540  includes a dielectric layer  1523  overlying the first surface  1521  of the substrate  1520  outside the opening  1530  and a seed layer  1562  overlying the conductive via and a portion of the dielectric layer  1523 . The dielectric layer  1523  can be a passivation layer such as the layer  23  described above with reference to  FIGS. 1A and 1B . The conductive via  1540  can also have an adhesion or barrier layer  1551  (such as the layer  51  described above) that cam extend between the conductive via and the seed layer  1552 . In one example, the adhesion or barrier layer  1551  can be tantalum nitride/tantalum, e.g., alpha-tantalum with interstitial impurities, titanium nitride, titanium nitride/titanium, or a nickel-tungsten alloy, and the seed layer  1552  can be copper, nickel, or gold. In a particular embodiment, the adhesion or barrier layer  1551  and the seed layer  1552  can be a single layer, such as, for example, a single nickel alloy barrier and seed layer. The conductive joining material  1511  overlies the conductive via  1540  and a portion of the dielectric layer  1523 . Similar to  FIGS. 3A through 6C , the optional insulating dielectric layer  60  and the optional barrier layer  43  is not shown in  FIGS. 15 through 16D . 
         [0147]    A method of fabricating the component  1510  ( FIG. 15 ) will now be described, with reference to  FIGS. 16A-16D . The method steps of  FIGS. 2A-2G  can be used to form the dielectric layer  1523 , the opening  1530  extending from the first surface  1521  into the substrate  1520 , the conductive via  1540 , the relief channels  1555 , the adhesion or barrier layer  1551 , and the seed layer  1552  shown in  FIG. 16A . 
         [0148]    Referring now to  FIG. 16B , a mask layer  1525  can be deposited overlying the seed layer  1552 . The mask layer  1525  can be patterned, and then, as shown in  FIG. 16C , gaps  1526  can be formed through the mask layer to expose a portion of seed layer  1552  overlying one or more conductive vias  1540  and overlying a portion of the dielectric layer  1523 . Subsequently, as shown in  FIG. 16D , the conductive joining material  1511  can be deposited into the gaps  1526 , such that the conductive joining material is in contact with the seed layer  1552  and extends into the relief channels  1555 . Finally, referring again to  FIG. 15 , the remaining portions of the mask layer  1523  can be removed from the dielectric layer  1523 , leaving a conductive joining material  1511  that extends above the first surface of the substrate and above the dielectric layer  1523 . 
         [0149]      FIGS. 17A and 17B  show a component  1701  and a component  1702  that are the same as the component  1510  described above with respect to  FIG. 15 , except that the components  1701  and  1702  include a respective conductive joining material  1711  and  1711 ′ that does net extend into the relief channels  1755 . As can be seen in  FIG. 17A , the conductive joining material  1711  can overlie the conductive via  1740  and a portion of the dielectric layer  1723 . Alternatively, as can be seen in  FIG. 17B , the conductive joining material  1711 ′ can overlie the conductive via  1740 , but the conductive joining material may not overlie a portion of the dielectric layer  1723 . Similar to  FIG. 15 , the optional insulating dielectric layer  60  and the optional barrier layer  43  is not shown in  FIGS. 17A through 18 . 
         [0150]    A method or fabricating the components  1701  ( FIG. 17A) and 1702  ( FIG. 17B ) will now be described, with reference to  FIG. 18 . The method steps of  FIGS. 2A-2G  can be used to form the dielectric layer  1723 , the opening  1730  extending from the first surface  1721  into the substrate  1720 , the conductive via  1740 , the relief channels  1755 , the adhesion or barrier layer  1751 , and the seed layer  1752  shown in  FIG. 18 . In  FIG. 18 , the adhesion or barrier layer  1751  and the seed layer  1752  are shown as being deposited onto an exposed surface of the conductive via  1740 , and the dielectric layer  1723  is shown partially overlying the barrier layer and the seed layer. After the dielectric layer  1723  is deposited, the conductive joining material  1711  ( FIG. 17A ) or  1711 ′ ( FIG. 17B ) can be deposited into the gap  1726  in the dielectric layer  1723 . In a particular embodiment, a mask layer such as the mask layer  1525  shown in  FIGS. 16B-16D  can be deposited and patterned to control the deposition of the conductive joining material  1711  or  1711 ′ only to desired locations. 
         [0151]      FIG. 19  shows a component  1910  that is the same as the components  1701  and  1702  described above with respect to  FIGS. 17A and 17B , except that the component  1910  includes a conductive post  1941  overlying the conductive via  1940 , and the conductive joining material  1911  overlies an exposed surface of the conductive post. In one example, the conductive post  1941  (and the other conductive posts described herein with respect to other embodiments) can consist essentially of at least one of: copper, a copper alloy, and nickel. 
         [0152]    Similar to  FIGS. 17A and 17B , the optional insulating dielectric layer  60  and the optional barrier layer  43  is not shown in  FIGS. 19 through 20B . Also, the optional seed layer such as the seed layer  1752  shown in  FIG. 18  is not shown in  FIGS. 19 through 20B . 
         [0153]    A method of fabricating the component  1910  ( FIG. 19 ) will now be described, with reference to  FIGS. 20A and 20B . The method steps of  FIGS. 2A-2G  can be used to form the dielectric layer  1923 , the opening  1930  extending from the first surface  1921  into the substrate  1920 , the conductive via  1940 , the relief channels  1955 , and the adhesion or barrier layer  1951 . In a particular example, a seed layer such as the seed layer  1752  shown in  FIG. 18  may be deposited overlying the adhesion or barrier layer a  1951 . The method steps of  FIGS. 15B and 14C  can be used to form the mask layer  1925  and the gaps  1926  in the mask layer. 
         [0154]    Subsequently, as shown in  FIG. 20A , the conductive post  1941  can be deposited into the gaps  1926 , such that the conductive post is in contact with the adhesion or barrier layer  1951 . Similar to the conductive via  40  described above with reference to  FIGS. 1A and 1B , the conductive post  1941  can include a metal having a relatively high CTE, such as copper, aluminum, tungsten, an alloy including copper, an alloy including nickel, or an alloy including tungsten, among others. The conductive post  1941  can be made of the same electrically conductive material as the conductive via  1940 , or alternatively, the conductive post and the conductive via can be made of different electrically conductive materials. 
         [0155]    Then, referring to  FIG. 20B , the conductive joining material  1911  can be deposited into the gap  1926  in the mask layer  1925  overlying the exposed surface of the conductive post  1941 . Finally, referring again to  FIG. 19 , the remaining portions of the mask layer  1925  can be removed from the dielectric layer  1923 , leaving a conductive post  1941  that extends above the first surface of the substrate and above the dielectric layer  1923 , with a conductive joining material  1911  overlying an exposed surface of the conductive post. 
         [0156]      FIGS. 21A-21C  show components  2101 ,  2102 , and  2103  that are the same as the component  1910  described above with respect to  FIG. 19 , except that the components  2101 ,  2102 , and  2103  include a conductive post  2141  that extends a substantial distance above an exposed surface of the dielectric layer  2123 . The components  2101 ,  2102 , and  2103  can also have a barrier layer  2143  extending between the conductive post  2141  and the conductive joining material  2111 . The barrier layer  2143  can be similar to the barrier layer  1951  described above with reference to  FIG. 19 . Similar to  FIG. 19 , the optional insulating dielectric layer  60  and the optional barrier layer  43  is not shown in  FIGS. 21A through 22 . Also, the optional seed layer such as the seed layer  1752  shown in  FIG. 18  is not shown in  FIGS. 21A through 22 . 
         [0157]    As can be seen in  FIG. 21A , the conductive post  2141  can have an exposed vertically-extending surface  2142 . In one example, shown in  FIG. 21B , the conductive post  2141  can have a barrier layer  2144  overlying the vertically-extending surface  2142 . In one example, the barrier layer  2144  can be an electrically conductive barrier layer similar to the barrier layer  43  described above with reference to  FIG. 1A . In another example, the barrier layer  43  can be similar to a passivation layer, which can be made from an insulating dielectric material. 
         [0158]    In a particular embodiment, shown in  FIG. 21C , the conductive via  2140 ′ can include a relief channel  2155  having a tapered inner edge  2157  similar to that shown in  FIGS. 9A and 9B , the tapered inner edge not being perpendicular to the first surface  2121  of the substrate  2120 . The tapered inner edge  2157  may not be parallel to the outer edge  2156  of the relief channel  2155 , and the outer edge can be perpendicular to the first surface  2121  of the substrate  2120 . 
         [0159]      FIG. 22  shows a stage in fabrication of the components  2101  and  2102  shown in  FIGS. 21A and 21B . To fabricate the component  2101  shown in  FIG. 21A , the same method steps described above with respect to  FIGS. 19 through 20B  can be performed, except the mash layer  2125  and the gaps  2126  shown in  FIG. 22  can have a greater vertical height than the mask layer  1925  and the gaps  1920  shown in  FIGS. 20A and 20B . 
         [0160]    To fabricate the component  2102  shown in  FIG. 21B , the same method steps for fabrication of the component  2101  can be performed, and in addition, after the mask layer  2125  is removed, the barrier layer  2144  can be deposited overlying the vertically-extending surface  2142  of the conductive post  2141 . 
         [0161]    To fabricate the component  2103  shown in  FIG. 21C , the same method steps for fabrication of the component  2101  can be performed, but the relief channels  2155  of the conductive via  2140 ′ can be formed with a tapered inner edge  2157 . 
         [0162]      FIG. 23  shows a component  2310  that is the same as the component  1310  described above with respect to  FIG. 13 , except that the component  2310  includes two spaced-apart regions of conductive joining material  2311   a  and  2311   b,  and each region of conductive joining material can partially overlie the first surface  2321  of the substrate  2320 . Each region of conductive joining material  2311   a  and  2311   b  can extend into a portion of the relief channel  2355 . Similar to  FIGS. 3A through 6C , the optional insulating dielectric layer  60  and the optional barrier layer  43  is not shown in  FIGS. 23 through 24B . 
         [0163]    A method of fabricating the component  2310  ( FIG. 23 ) will now be described, with reference to  FIGS. 24A and 24B . The method steps of  FIGS. 2A-2G  can be used to form the opening  2330  extending from the first surface  2321  into the substrate  2320 , the conductive via  2340 , the relief channels  2355 , and the barrier layer  2351  shown in  FIG. 23 . Referring now to  FIG. 24A , a mask layer  2325  can be deposited overlying the barrier layer  2351  and portions of the first surface  2321  of the substrate  2320 . Gaps  2326   a  and  2326   b  can be formed through the mask layer to expose the barrier layer  2351  overlying the portions of the conductive via  2340  at which it is desired to deposit the respective regions of conductive joining material  2311   a  and  2311   b.    
         [0164]    Subsequently, as shown in  FIG. 24B , the conductive joining material  2311   a  and  2311   b  can be deposited into the respective gaps  2326   a  and  2326   b,  such that the regions of conductive joining material are in contact with portions of the barrier layer  2351  and extend into portions of the relief channels  2335 . Finally, referring again to  FIG. 23 , the remaining portions of the mask layer  2325  can be removed from the first surface  2321  of the substrate  2320 , leaving regions of conductive joining material  2311   a  and  2311   b  that extend above the first surface of the substrate. 
         [0165]    The component  2510  shown in  FIG. 25  is the same as the component  1110  described above with respect to  FIG. 11A , except that the competent  2510  has a plurality of conductive vias  2540  each having relief channels  2555 , and a low stress material  2512  can be disposed in the relief channels at the first surface  2521  of tee substrate  2520 . The low stress material  2512  can be conductive (e.g., solder or a conductive adhesive paste) nonconductive (e.g., a polymer or another dielectric material), or a porous conductive or nonconductive material such as a polymer foam. Such a material can have a low modulus of elasticity, or the material can have enough collapsible pores that can compress under a load. 
         [0166]    In embodiments where the semiconductor element  2520  includes a semiconductor substrate, made for example from silicon, one or a plurality of semiconductor devices (e.g., transistors, diodes, etc.) can be disposed in an active device region  2524  thereof located at and/or below the first surface  2521 . The component  2510  can also have BEOL layers  2560  overlying the first surface of the substrate  2520  and the exposed surface of the conductive vias  2540 . The BEOL layers  2560  can include an insulating dielectric material  2561  and conductive leads  2562  (conductive traces and conductive vias) extending between the conductive vias  2540  and conductive terminals  2564  exposed at a top surface  2566  of the BEOL layers  2560  for interconnection with an external component. 
         [0167]    In one embodiment, each conductive via can have a maximum width W 5  in a direction in a horizontal plane P′ parallel to the first surface, the maximum width being located within five microns of the first surface. The plurality of conductive vias  2540  can define a minimum pitch  2548  in the horizontal plane P′ between respective vertical central axes  2549  of any two adjacent ones of the conductive vias, the minimum pitch being less than three times the maximum width of each of the adjacent conductive vias. In a particular example, the minimum pitch  2548  between any two adjacent ones of the conductive vias  2540  can be less than two times the maximum width of each of the adjacent conductive vias. In an exemplary embodiment, the minimum pitch  2548  between any two adjacent ones of the conductive vias  2540  can be less than 1.2 times the maximum width of each of the adjacent conductive vias. 
         [0168]    The conductive vias  2640   a  and  2640   b  shown in  FIGS. 26A and 26B  are the same as the conductive via  340  described above with respect to  FIGS. 3A and 3B , except that the conductive vias  2640   a  and  2640   b  extend within a respective tapered opening  2630   a  and  2630   b  in a substrate  2620 . Such a tapered opening  2630   a  or  2630   b  can taper in either direction between the first and second surfaces  2621 ,  2622  of the substrate  2620 . As shown in  FIG. 26A , the tapered opening  2630   a  can have an elliptic paraboloid shape, a hyperboloid shape, or a curvilinear shape (i.e., the opening is bounded by an inner wall  2632   a  having a curvilinear shape). As shown in  FIG. 26B , the tapered opening  2630   b  can have a frusto-conical shape. In a particular example, a tapered opening such as the opening  2630   a  or  2630   b  can be formed by isotropic etching followed by anisotropic etching. 
         [0169]    In one example, a portion of the opening or the entire opening  2630   a  or  2630   b  can be bounded by a surface defining a curvilinear cross-sectional shape in a plane that is perpendicular to the first surface of the substrate, and such a curvilinear opening structure can be formed by isotropic etching of the substrate from one surface (either the first or second surface) to form a cavity extending partially through the substrate, then the substrate can be thinned by removing material from the opposite surface of the substrate, and then anisotropic etching can be performed from the opposite surface to extend the cavity into an opening extending completely through the substrate. 
         [0170]    A tapered opening  2630   a  or  2630   b  having a smaller diameter at the first surface  2621  than at the second surface  2622  can help protect structures at the first surface such as an active device region during temperature changes, because it may help prevent pumping, i.e., vertical motion of the conductive via relative to the substrate, when there is a significant difference between the coefficient of thermal expansion of the material of the conductive via and the material of the substrate. 
         [0171]    As shown in  FIGS. 26A and 26B , the openings  2630   a  and  2630   b  have relief channels  2655  extending into the exposed surface of the respective conductive via  2640   a  and  2640   b.  In a particular example, a tapered opening such as the opening  2630   a  or  2630   b  can be provided without a relief channel  2655 . 
         [0172]    The components  2701 ,  2702 ,  2703 , and  2704  shown in  FIGS. 27A-27D  are variations of the component  2101  shown in  FIG. 21A , but with a tapered opening  2730  that is the same as the tapered opening  2630   a  shown in  FIG. 26A  that can have an elliptic paraboloid shape, a hyperboloid shape, or a curvilinear shape. In a particular example, the tapered opening  2730  of  FIGS. 27A-27D  can have a frusto-conical shape like the tapered opening  2630   b  shown in  FIG. 26B . 
         [0173]    The component  2101  shown in  FIG. 27A  can have a conductive post  2741   a  that is the same as the conductive post  2141  shown in  FIG. 21A . In one example, the conductive post  2741   a  can have conductive joining material overlying an exposed surface of the conductive post. Similar to  FIG. 21A , the conductive post  2741   a  can overlie an exposed surface of the conductive via  2740 , but the conductive post may not overlie the relief channels  2755 . In a particular embodiment, the relief channels  2755  may be filled with a portion of a dielectric layer overlying the first surface  2721  of the substrate  2720  such as the dielectric layer  2123  shown in  FIG. 21A . 
         [0174]    The component  2102  shown in  FIG. 27B  is a variation of the component  2101  shown in  FIG. 27A . The component  2102  can have a conductive post  2741   b  that can overlie an exposed surface of the conductive via  2740  and the relief channels  2755 . In a particular embodiment, the relief channels  2755  may be filled with a low stress material  2712  disposed in the relief channels  2755  at the first surface  2721  of the substrate  2720 . The low stress material  2712  can be conductive (e.g., solder or a conductive adhesive paste), nonconductive (e.g., a polymer or another dielectric material), or a porous conductive or nonconductive material such as a polymer foam. Such a material can have a low modulus of elasticity, or the material can have enough collapsible pores that can compress under a load. 
         [0175]    The components  2103  and  2104  shown in  FIGS. 27C and 27D  are further variations of the component  2101  shown in  FIG. 27A . The components  2103  and  2104  can have a respective conductive post  2741   c  or  2741   d  that can overlie an exposed surface of the conductive via  2740 , but the respective conductive post may not overlie the relief channels  2755 . The conductive posts  2741   c  and  2741   d  shown in  FIGS. 27C and 27D  can have a tapered shape, for example, an elliptic paraboloid shape, a hyperboloid shape, or a curvilinear shape (i.e., the conductive post has an outer surface having a curvilinear shape in a direction generally perpendicular to the first surface of the substrate). In a particular example, the conductive posts  2741   c  and  2741   d  can have a frusto-conical shape. 
         [0176]    As shown in  FIG. 27C , the conductive post  2741   c  has a tapered shape that is wider at the base adjacent to the first surface  2721  of the substrate  2720  and narrower at the tip remote from the first surface. As shown in  FIG. 27D , the conductive post  2741   d  has a tapered shape that is narrower at the base adjacent to the first surface  2721  of the substrate  2720  and wider at the tip remote from the first surface. 
         [0177]    Referring now to  FIG. 28A , the component  2801  includes a conductive via  2840  that has some features of the conductive via  540   a  shown in  FIG. 5A  and the conductive  2740  and the conductive post  2741   c  shown in  FIG. 27C .  FIG. 28B  shows a component  2802  that is a variation of the component  2801  having an opening  2830 ′ with an alternative tapered shape, as described below. 
         [0178]    Similar to the conductive via  540   a  shown in  FIG. 5A , the conductive via  2840  can include a relief channel  2855 , and the conductive via can have an oblong or oval shape, wherein the conductive via defines a first dimension L 3  that is greater than a second dimension L 4 , the first and second dimensions being located in the relief plane P shown and described with respect to  FIG. 1A . In a particular example, L 3  can be several times greater than L 4 , such as, for example, 6 times or 8 times greater. 
         [0179]    As shown in  FIG. 28A , the relief channel  2855  and the opening  2830  in which the conductive via extends can each have an oblong or oval cross-sectional shape in a plane generally parallel to the first surface of the substrate. In one example, such a conductive via  2840  having an oblong or oval shape and a plurality of conductive posts  2841  extending therefrom can be used for power or ground (i.e., reference potential) distribution within the component  2301 . In a particular example, the conductive via  2840  can have an elongated cross-sectional shape, the conductive via defining a length (e.g., the first dimension L 3 ) in a first direction and a width (e.g., the second dimension L 4 ) in a second direction transverse to the first direction, the first and second directions being within a plane that is perpendicular to the first surface  2821  of the substrate  2820 , the length being greater than the width. 
         [0180]    One or a plurality of semi conductor devices (e.g., transistors, diodes, etc.) can be disposed in one or more active device regions  2824  thereof located at and/or below the first surface  2821 . The active device regions  2824  can be located between adjacent conductive vias  2840  in a single component  2801 . In the example shown in  FIG. 28A , one or more active device regions  2624  can be oriented substantially parallel to a direction of the first dimension L 3  or the conductive via  2840 , and one or more active device regions can be oriented substantially parallel to a direction of the second dimension L 4  of the conductive via. 
         [0181]    Similar to the component  2703  shown in  FIG. 27C , the component  2601  can include one or more conductive vias  2840  that extend within a respective tapered opening  2630  in a substrate  2820 . Such a tapered opening  2830  can taper in either direction between the first and second surfaces  2821 ,  2822  of the substrate  2320 . In the example shown in  FIG. 28A , the opening  2830  can have a cross-section in the plane of the first surface  2321  that has a smaller area than its cross-section in the plane of the second surface  2822 , such that the opening tapers from the second surface toward the first surface. 
         [0182]    In another example, as shown in  FIG. 28B , the opening  2830 ′ can have a cross-section in the plane of the first surface  2821  that has a larger area than its cross-section in the plane of the second surface  2822 , such that the opening tapers from the first surface toward the second surface. Such a tapered opening  2830  or  2830 ′ can have an elliptic paraboloid shape, a hyperboloid shape, or a curvilinear shape as described above. In a particular example, a tapered opening such as the opening  2830  or  2830 ′ can be formed by isotropic etching followed by anisotropic etching. 
         [0183]    Similar to the component  2703  shown in  FIG. 27C , the component  2801  can include one or more conductive posts  2841  that can over lie an exposed surface  2830  of a particular conductive via  2840 , but the conductive posts may not overlie the relief channel or channels  2835 . The conductive post  2841  can have a tapered shape, for example, an elliptic paraboloid shape, a hyperboloid shape, or a curvilinear shape as described above. In a particular example, the conductive posts  2841  can have a frusto-conical shape. 
         [0184]    As shown in  FIG. 28A , the conductive post  2841  has a tapered shape that is wider at the base adjacent to the first surface  2821  of the substrate  2320  and narrower at the tip remote from the first surface. In a particular example, the component  2840  can include one or more conductive posts having any other shape, such as the conductive post shapes described above with respect to the various embodiments herein. 
         [0185]    The components described above can be utilized in construction of diverse electronic systems, as shown in  FIG. 29 . For example, a system  2800  in accordance with a further embodiment of the invention includes a microelectronic assembly  2806  as described above in conjunction with other electronic components  2808  and  2810 . In the example depicted, component  2808  is a semiconductor chip whereas component  2810  is a display screen, but any other components can be used. Of course, although only two additional components are depicted in  FIG. 29  for clarity of illustration, the system may include any number of such components. The microelectronic assembly  2806  may be any of the components described above. In a further variant, any number of such microelectronic assemblies  2806  can be used. 
         [0186]    The microelectronic assembly  2806  and components  2808  and  2810  can be mounted in a common housing  2801 , schematically depicted in broken lines, and can be electrically interconnected with one another as necessary to form the desired circuit. In the exemplary system shown, the system can include a circuit panel  2802  such as a flexible printed circuit board, and the circuit panel can include numerous conductors  2804 , of which only one is depicted in  FIG. 29 , interconnecting the components with one another. However, this is merely exemplary; any suitable structure for making electrical connections can be used. 
         [0187]    The housing  2801  is depicted as a portable housing of the type usable, for example, in a cellular telephone or personal digital assistant, and screen  2810  can be exposed at the surface of the housing. Where structure  2806  includes a light-sensitive element such as an imaging chip, a lens  2811  or other optical device also can be provided for routing light to the structure. Again, the simplified system shown in  FIG. 29  is merely exemplary; other systems, including systems commonly regarded as fixed structures, such as desktop computers, routers and the like can be made using the structures discussed above. 
         [0188]    Although a silicon substrate having active device regions therein is only shown and described with reference to the embodiment shown in  FIGS. 1A and 1B , the substrate of any of the components described herein can be made of silicon or a dielectric material such as glass, ceramic, a composite material, or symmetric or asymmetric laminates, as described above. When the substrate is made of silicon, any such substrate in any of the embodiments described herein can include active semiconductor devices in one or more active device regions of the substrate. 
         [0189]    The openings, apertures, and conductive elements disclosed herein can be formed by processes such as those disclosed in greater detail in the co-pending, commonly assigned U.S. patent application Ser. Nos. 12/842,587, 12/842,612, 12/842,651, 12/842,669, 12/842,692, and 12/842,717, filed Jul. 23, 2010, and in published U.S. Patent Application Publication No. 2008/0246136, the disclosures of which are incorporated by reference herein. 
         [0190]    Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. 
         [0191]    It will be appreciated that the various dependent claims and the features set forth therein can be combined in different ways than presented in the initial claims. It will also be appreciated that the features described in connection with individual embodiments may be shared with others of the described embodiments.