Patent Abstract:
Apparatus including a chip substrate having a first chip surface facing away from a second chip surface; an array of microelectronic elements on the first chip surface; and an array of conductors each in communication with one of the microelectronic elements, the conductors passing through the chip substrate and fully spanning a distance between the first and second chip surfaces. Process including: providing an apparatus including a chip substrate having a first chip surface facing away from a second chip surface, an array of microelectronic elements being on the first chip surface, an array of conductors each being in communication with one of the microelectronic elements and partially spanning an average distance between the first and second chip surfaces; bonding a temporary support carrier onto the array of microelectronic elements; removing a portion of the chip substrate, thereby reducing the average distance between the first and second chip surfaces; and forming an under bump metallization pad at the second chip surface in electrical communication with a conductor.

Full Description:
U.S. GOVERNMENT 
     The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of U.S. Defense Advanced Research Projects Agency (“DARPA”) CCIT Phase 2 contract No.: HR0011-04-C-0048. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to microelectronic element chips, and processes for their fabrication. 
     2. Related Art 
     Myriad microelectronic elements have been formed on conductive wafers such as silicon wafers. Multiple such devices may be formed on a single wafer, which then may be diced to separate the devices as chips. A single chip may contain a number of microelectronic elements integrated into a circuit. 
     As this vast chip technology continues to evolve, the potential magnitude of conductor interconnections between a chip and further circuitry with which the chip may be integrated accordingly continues to grow. Implementation of early chip technology included the practice of bonding wire conductor interconnections on top of microelectronic elements formed on the chip. With ever greater multiplicity of potential conductor interconnections with a chip, direct chip attachment (“DCA”) technology has been developed, including provision of conductor interconnections that may pass through the chip itself from one side of the wafer to the other. However, the need for sufficient conductor interconnections for the large numbers of microelectronic elements that may be formed on a single chip constitutes a continuing problem, and a limitation in chip design. 
     There is a continuing need for new types of chip structures for direct chip attachment that may facilitate further growth in the potential magnitude of microelectronic elements to be formed on a chip, and a need for processes that facilitate the fabrication of such chip structures. 
     SUMMARY 
     In an implementation example, an apparatus is provided, including a chip substrate having a first chip surface facing away from a second chip surface; an array of microelectronic elements on the first chip surface; and an array of conductors each in communication with one of the microelectronic elements, the conductors passing through the chip substrate and fully spanning a distance between the first and second chip surfaces. 
     In another example, a process is provided, including: providing an apparatus including a chip substrate having a first chip surface facing away from a second chip surface, an array of microelectronic elements being on the first chip surface, an array of conductors each being in communication with one of the microelectronic elements and partially spanning an average distance between the first and second chip surfaces; bonding a temporary support carrier onto the array of microelectronic elements; removing a portion of the chip substrate, thereby reducing the average distance between the first and second chip surfaces; and forming an under bump metallization pad at the second chip surface in electrical communication with a conductor. 
     Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention can be better understood with reference to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG. 1  is a cross-sectional view showing an implementation of an example of a microelectronic element array chip with direct chip attachment (“DCA”) pads (“Microelectronic Element Array with DCA Pads”). 
         FIG. 2  is a top view, taken on line  2 - 2 , of the Microelectronic Element Array with DCA Pads shown in  FIG. 1 . 
         FIG. 3  is a cross-sectional view, taken on line  3 - 3 , of the Microelectronic Element Array with DCA Pads as shown in  FIG. 1 . 
         FIG. 4  is a cross-sectional view showing an array of microelectronic elements formed on a top surface of a typical chip substrate. 
         FIG. 5  is a flow-chart showing an example of an implementation of a process for fabricating the Microelectronic Element Array with DCA Pads. 
         FIG. 6  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads during its fabrication. 
         FIG. 7  is a top view of the Microelectronic Element Array with DCA Pads during its fabrication, taken on line  7 - 7 . 
         FIG. 8  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads during its fabrication. 
         FIG. 9  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads during its fabrication. 
         FIG. 10  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads during its fabrication. 
         FIG. 11  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads during its fabrication. 
         FIG. 12  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads during its fabrication. 
         FIG. 13  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads during its fabrication. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a cross-sectional view showing an implementation of an example of a microelectronic element array chip with direct chip attachment (“DCA”) pads (“Microelectronic Element Array with DCA Pads”)  100 .  FIG. 2  is a top view, taken on line  2 - 2 , of the Microelectronic Element Array with DCA Pads  100  shown in  FIG. 1 .  FIG. 3  is a cross-sectional view, taken on line  3 - 3 , of the Microelectronic Element Array with DCA Pads  100  as shown in  FIG. 1 . 
     The Microelectronic Element Array with DCA Pads  100  includes a chip substrate  102  on which an array of microelectronic elements  104  is formed. Throughout this specification, the term “microelectronic element” means a device including electrical conductors that affect the device in operation. The term “microelectronic element” includes, as an example, semiconductor devices, passive filters, sensors, and optoelectronic devices including micro-electro-mechanical systems (“MEMS”). The term “semiconductor device” means, throughout this specification, a device that utilizes a doped semiconductor p-n hetero-junction between Group 3-5, 2-6, or 4-4 semiconductors that allows a controlled flow of electrons and/or holes across the hetero-junction. As examples, “semiconductor devices” include transistors and diodes. The term “MEMS” means, throughout this specification, a device on a chip substrate  102  that integrates mechanical elements, actuators for the mechanical elements, and electronics for controlling the actuators. In an implementation, a MEMS device may include sensors. As a further example, a MEMS device may include optical elements, such as mirrors controlled by the actuators. 
     Throughout this specification, the term “array” means an arrangement of a plurality of microelectronic elements  104  on a chip substrate  102 . As an example, the Microelectronic Element Array with DCA Pads  100  may include a five by five (5×5) array of twenty-five (25) microelectronic elements  104  on a chip substrate  102 , arranged in five rows and five columns as shown in  FIG. 2 . It is understood that an “array” may include any number of microelectronic elements  104  arranged in any number of rows and columns, that the rows and columns may have equal or unequal spacing or lengths, that the rows and columns may or may not be mutually orthogonal, that such an array may incorporate one or more complex repeating patterns of relative locations for microelectronic elements  104  on a chip substrate  102 , that an array may include individual microelectronic elements  104  or groups of such elements positioned at selected relative locations on a chip substrate, and that an array may include microelectronic elements randomly positioned on a chip substrate. 
     As an example, each microelectronic element  104  may include four element conductors  106  in communication with the microelectronic element and extending into the chip substrate  102  away from the microelectronic element. As an example, the microelectronic elements  104  may be MEMS micro-mirror elements. In this example, the four element conductors  106  in communication with each MEMS micro-mirror element may operate as controllers serving to power one or more actuators causing a micro-mirror in the MEMS micro-mirror element to be moved in a specified direction. It is understood that each microelectronic element  104  may include any selected number of element conductors  106 , and that different microelectronic elements  104  in the Microelectronic Element Array with DCA Pads  100  may have different numbers of element conductors. It is further understood that by “element conductors  106  in communication with the microelectronic element” is meant that the element conductors  106  are placed in positions relative to the microelectronic element  104  that are suitable for its operation. As examples, the element conductors  106  may form an electrical connection with circuit elements within the microelectronic elements  104  or may generate an electromagnetic field affecting the microelectronic elements  104  depending on their structure and operating design. 
     The element conductors  106  extend from points  108  where they communicate with the microelectronic elements  104  to points  110  after passing through the chip substrate  102 . As an example, the chip substrate  102  may be formed of a conductor such as polysilicon or a composition including silicon (“Si”). In this example, the element conductors may be surrounded by insulator layers  112 . 
       FIG. 3  shows a ten by ten (10×10) array of element conductors  106  in an implementation of a five by five (5×5) array of microelectronic elements  104  that each may need four (4) element conductors for operation of the microelectronic elements. It is seen in  FIG. 3  that as the magnitude of the array of microelectronic elements  104  to be formed on a chip substrate  102  is increased, and as the number of element conductors  106  needed for operation of each microelectronic element increases, the density and total number of element conductors needed for the Microelectronic Element Array with DCA Pads  100  may accordingly increase. As a further example, it is seen that as the dimensions of a Microelectronic Element Array with DCA Pads  100  increases, the number of element conductors  106  needed for the Microelectronic Element Array with DCA Pads  100  increases as a function of n×m, where n is the width and m is the height of the array represented by the arrows  114  and  116  respectively. The same increase as a function of n×m is seen with respect to the array of microelectronic elements  104  at the same density shown in  FIG. 3 . Meanwhile, the size of the perimeter of the chip substrate  102  increases only as a function of 2×n plus 2×m. Hence, as the size and density of the array are increased, the impracticality of wire bonding of element conductors on top of the microelectronic elements  104  and over the perimeter of the Microelectronic Element Array with DCA Pads  100 , and the resulting need for DCA bonding, correspondingly increase. 
       FIG. 4  is a cross-sectional view showing an array  400  of microelectronic elements  104  formed on a top surface  402  of a typical chip substrate  404 . As an example, the thickness of a chip substrate  404  having a diameter of 200 millimeters, as represented by the arrow  406 , may be about 725 micrometers plus or minus about 25 micrometers. Efforts to provide DCA pads for a microelectronic element  104  at a bottom surface  408  of a chip substrate  404  having a thickness of such a magnitude may be problematic. As an example, forming extensions of the element conductors  106  to reach the bottom surface  408  may be difficult, as attempting to fill an array of through wafer vias extending to the bottom surface  408  with a conductor may result in the formation of voids. Patterning of through wafer vias having high aspect ratios may accordingly be difficult. In an implementation, internal stresses in the chip substrate  404  may by generated by filling such an array of through wafer vias with a conductor, potentially causing distortion of the structure of the array  400  of microelectronic elements  104 . Such distortion may complicate further fabrication steps or make completion of the array  400  unfeasible. As another example, forming extensions of the element conductors  106  having lengths adequate to traverse the thickness of the chip substrate  404  as represented by the arrow  406  may result in degraded performance of the array  400  of microelectronic elements  104  due to the high lengths of the element conductors. 
     Referring again to  FIG. 1 , the Microelectronic Element Array with DCA Pads  100  accordingly includes a chip substrate  102  having a substantially reduced average thickness, as represented by the arrow  118 . As an example, the average thickness represented by the arrow  118  may be less than about 150 micrometers. In another implementation, the average thickness represented by the arrow  118  may be less than about 100 micrometers. The Microelectronic Element Array with DCA Pads  100  may be fabricated according to an implementation of a process discussed below that may be less susceptible to defective formation of extensions of the element conductors  106 , the extension being formed onto a bottom surface  120  of the Microelectronic Element Array with DCA Pads  100 . Furthermore, the Microelectronic Element Array with DCA Pads  100  may provide better performance in operation than the array  400  of microelectronic elements  104  formed on a typical chip substrate  404 . Since the average thickness represented by the arrow  118  is substantially less than the thickness represented by the arrow  406 , the element conductors  106  in the Microelectronic Element Array with DCA Pads  100  have a substantially shorter path length to the bottom surface  120  than do the element conductors  106  in the array  400  of microelectronic elements  104  to the bottom surface  408 . The thickness of the chip substrate  102  represented by the arrow  118  may be inadequate to mechanically support the Microelectronic Element Array with DCA Pads  100 . The example process for fabricating the Microelectronic Element Array with DCA Pads  100  discussed below may facilitate fabrication and DCA bonding of the Microelectronic Element Array with DCA Pads  100  without breakage or other damage to the Microelectronic Element Array with DCA Pads  100  otherwise potentially caused by the reduced thickness of the chip substrate  102 . 
     The Microelectronic Element Array with DCA Pads  100  may include a barrier layer  122 . The barrier layer  122  may in an implementation be formed of a dielectric composition that is not a conductor. Each element conductor  106  is in electrical communication with an under-bump metallization pad  124  passing through a hole in the barrier layer  122 . As an implementation, the under-bump metallization pads  124  may be mutually separated by an insulating protective layer  126 . As an example, each under-bump metallization pad  124  may be in electrical communication with a solder bump  128 . It is understood that the solder bump may be formed of a suitable conductor, which may be a solder composition or may be another conductive composition. 
       FIG. 1  shows the Microelectronic Element Array with DCA Pads  100  after DCA bonding to a substrate  130  forming part of another device with which the Microelectronic Element Array with DCA Pads  100  has been integrated. As examples, the substrate  130  may be a circuit board or another chip substrate. In an implementation, the substrate  130  may include bonding pads  132  formed of a conductor composition, in electrical communication with electrical circuitry within the substrate  130 , and in electrical communication with the solder bumps  128  and the under-bump metallization pads  124 . 
       FIG. 5  is a flow-chart showing an example of an implementation of a process  500  for fabricating the Microelectronic Element Array with DCA Pads  100 .  FIG. 6  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads  100  at a stage  600  during its fabrication.  FIG. 7  is a top view of the Microelectronic Element Array with DCA Pads  100  at stage  600  of its fabrication taken on line  7 - 7 .  FIG. 8  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads  100  at a stage  800  during its fabrication.  FIG. 9  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads  100  at a stage  900  during its fabrication.  FIG. 10  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads  100  at a stage  1000  during its fabrication.  FIG. 11  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads  100  at a stage  1100  during its fabrication.  FIG. 12  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads  100  at a stage  1200  during its fabrication.  FIG. 13  is a cross-sectional view showing an example of a Microelectronic Element Array with DCA Pads  100  at a stage  1300  during its fabrication. 
     The process  500  starts at step  502 . At step  504 , an array  400  of microelectronic elements  104  formed on a typical chip substrate  404 , as shown in  FIG. 4  and discussed above, may be provided or fabricated. The array  400  of microelectronic elements  104  formed on a chip substrate  404  includes a element conductor  106  in electrical communication with microelectronic elements  104  in the manner as discussed above in connection with  FIG. 1 . However, the element conductors  106  do not traverse the full thickness of the chip substrate  404  as represented by the arrow  406 , but instead terminate at points  110 . As an example, a barrier layer  122  may be interposed within the chip substrate  404  at the points  110 . In an implementation, the chip substrate  404  is formed of a conductive composition, and the element conductors  106  are surrounded by insulator layers  112  as discussed above in connection with  FIG. 1 . 
     In an implementation, the thickness of a chip substrate  404  having a diameter of 200 millimeters, as represented by the arrow  406 , may be about 725 micrometers plus or minus about 25 micrometers. It is understood that such a thickness of the chip substrate  404  is merely an example, and arrays  400  of microelectronic elements  104  on chip substrates  404  having other thicknesses may be utilized. The array  400  of microelectronic elements  104  as shown in  FIG. 4  may be fabricated utilizing conventional techniques for making such devices on a chip substrate  404 . As an example, the array  400  of microelectronic elements  104  formed on a chip substrate  404  may be commercially obtained. In an implementation, an array  400  of microelectronic elements  104  formed on a chip substrate  404  having such a thickness may be selected as a starting material for utilization in the process  500 , as the thick chip substrate  404  may provide good mechanical support for the array  400  of microelectronic elements  104  during the initial steps of the process  500  now discussed. 
     Referring to  FIGS. 6 and 7  showing fabrication of a Microelectronic Element Array with DCA Pads  100  at stage  600 , at step  506  a temporary support carrier  602  having perforations  604  is provided or fabricated. The temporary support carrier  602  includes a bottom surface  606  having suitable dimensions selected for bonding onto the top surface  402  of the array  400  of microelectronic elements  104 . The temporary support carrier further includes a top surface  608  opposite the bottom surface  606 . The perforations  604  reach both the bottom and top surfaces  606  and  608 , respectively. 
     At step  508 , the bottom surface  606  of the temporary support carrier  602  is bonded onto the top surface  402  of the array  400  of microelectronic elements  104 . In an implementation, a layer  610  of an adhesive composition may be interposed between the top surface  402  of the array  400  and the bottom surface  606  of the temporary support carrier  602  to form a bond. As an example, an adhesive composition suitable for subsequent dissolution by a solvent composition compatible with the array  400  of microelectronic elements  104  may be selected. By “compatible” is meant throughout this specification that the solvent composition will not cause any significant damage to the array  400 . The perforations  604  facilitate introduction of such a solvent composition to portions of the layer  610  that are exposed by the perforations  604  and are covered by the adhesive composition, in order to dissolve the adhesive as discussed further below. As an example, a protective passivation layer  612  may be formed on the top surface  402  of the array  400  before application of the layer  610  of an adhesive composition. Such a protective passivation layer  612  may protect the array  400  of microelectronic elements  104  from contamination or other damage by the layer  610  of an adhesive composition. In an implementation, the protective passivation layer  612  is formed of a composition suitable for subsequent removal as discussed below. As examples, the passivation layer may include silicon dioxide or silicon nitride or a mixture. 
     Referring to  FIG. 8  showing fabrication of a Microelectronic Element Array with DCA Pads  100  at stage  800 , at step  510  the bottom surface  408  of the chip substrate  404  as shown in  FIG. 6  is removed to expose the barrier layer  122 . As an example, the portion of the chip substrate  404  between the barrier layer  122  and the bottom surface  408  may be removed by a series of steps including backgrinding, polishing, and etching to the barrier layer  122 . In an implementation, the barrier layer  122  is formed of a composition including silicon dioxide, the chip substrate  404  is formed of a composition including silicon, and a wet etching composition that erodes silicon dioxide more slowly than it erodes silicon is selected. In another implementation, the barrier layer  122  may be omitted, and an etching process may be carried out over a controlled time period to stop at the bottom surface  120 . 
     Referring to  FIG. 9  showing fabrication of a Microelectronic Element Array with DCA Pads  100  at stage  900 , at step  512  the barrier layer  122  may be selectively etched to expose the element conductors  106  that are in contact with the barrier layer  122 . As an example, a photoresist may be applied onto the barrier layer  122 , and exposed to light through a mask configured to enable subsequent removal of those portions of the photoresist overlying the element conductors  106 . A suitable etching composition may then be applied onto the photoresist for selective removal of the exposed regions of the barrier layer  122 , leaving holes  902  in the barrier layer  122 . 
     Referring to  FIG. 10  showing fabrication of a Microelectronic Element Array with DCA Pads  100  at stage  1000 , at step  514  an array of under bump metallization (“UBM”) pads  124  are formed in electrical communication with the element conductors  106  at the points  110 . As an example, the UBM pads  124  may be formed by multiple cycles of a liftoff photoresist process with successive application of metallization layers. In an implementation, the UBM pads  124  may include one or more types of layers successively applied onto the element conductors  106 , including adhesion, diffusion barrier, solder bump wetting, and oxidation-protective layers. An adhesion layer may be applied to the element conductors  106  to facilitate adhesion of subsequently applied layers. A diffusion barrier layer may then be applied to reduce migration of a solder composition, discussed below, into the element conductors  106 . A solder wetting layer may then be applied to facilitate wetting of the UBM pads  124  by solder bumps  128  discussed below. An oxidation-protective layer may then be applied to reduce oxidation of the UBM pads  124 . It is understood that each of the adhesion, diffusion barrier, solder bump wetting, and oxidation-protective layers may be formed by multiple cycles of a liftoff photoresist process, and that one or more of such layers may be omitted or applied in a different order. After completion of the liftoff photoresist process, portions of the photoresist composition may be left behind on the barrier layer  122  surrounding the UBM pads  124 . In an implementation, these portions of the photoresist composition may be retained on the barrier layer  122 , forming an insulating layer  126  between the UBM pads  124 . 
     In an implementation (not shown), step  514  may include the formation of lateral conductors on the barrier layer  122  in electrical communication with the element conductors  106 , in order to transform the array of element conductors  106  as shown in  FIG. 3  into a different array layout selected for compatibility with an array of bonding pads  132  on a substrate  130  forming part of another device with which the Microelectronic Element Array with DCA Pads  100  is to be been integrated. As an example, a layer of a conductive composition may be applied onto the barrier layer  122 . The layer of conductive composition may then be patterned by application and lithographic exposure of a photoresist followed by etching of the regions unprotected by the photoresist, leaving behind lateral conductors on the surface of the barrier layer  122  each in electrical communication with an element conductor at a point  120 . The lateral conductors, as an example in the form of wires, may then be covered by an insulating layer. The insulating layer may then be selectively removed forming vias in communication with exposed ends of the lateral conductors distal to the element conductors  106 . The vias may then be filled with a conductive composition to form conductors arranged in a selected transformed array. The above-discussed aspects of step  514  earlier discussed and shown in  FIG. 10  may then be carried out. 
     Referring to  FIG. 11  showing fabrication of a Microelectronic Element Array with DCA Pads  100  at stage  1100 , at step  516  an array of solder bumps  128  may be formed on the UBM pads  124 . As an implementation, the solder bumps  128  may be formed by a liftoff photoresist process as earlier discussed. In examples, the solder bumps  128  may be formed of a conductor composition including tin, indium, or a mixture. Referring to  FIG. 11 , the photoresist layer  1102  may form wells into which the composition utilized for forming the solder bumps  128  may drop down and penetrate. As an implementation, the photoresist layer  1102  may form wells having walls that taper to a smallest width where ends  1103  of the solder bumps  128  will be formed. Portions  1104  of a conductor composition utilized for forming the solder bumps  128  may be deposited on the photoresist layer  1102 . The portions  1104  of the conductor composition may be subsequently removed along with the photoresist layer  1102 , due to differences in height of the solder bumps  128  and portions  1104  of the conductor composition on the photoresist layer  1102 . As an example, the photoresist layer  1102  may be temporarily left on the insulating protective layer  126  to protect the solder bumps  128  and UBM pads  124  from damage. In another implementation, an additional protective layer  1106  may be applied onto the solder bumps  128 , the portions  1104  of the conductor composition and the photoresist layer  1102  to further protect the solder bumps and the UBM pads  124  from damage. As an example, the protective layer  1106  may be formed of a photoresist composition. 
     In an implementation, step  516  may include dicing multiple arrays  400  of microelectronic elements  104 , as formed on a single wafer. As an example, dicing may be carried out after formation of the solder bumps  128 . In an implementation, dicing may be carried out prior to removal of the photoresist layer  1102 . As another example, the protective layer  1106  may be applied prior to dicing. The photoresist layer  1102  and the protective layer  1106  may protect the arrays  400  of microelectronic elements  104  from contamination by wafer debris and other damage during dicing. 
     Referring to  FIG. 12  showing fabrication of a Microelectronic Element Array with DCA Pads  100  at stage  1200 , at step  518  the photoresist layer  1102  and the portions  1104  of the conductor composition may be removed to expose the UBM pads  124  and the solder bumps  128  for DCA bonding onto a second substrate  130 . The photoresist layer  1106 , if present, may be removed at the same time. In an implementation, the temporary support carrier  602  may remain bonded at stage  1200  onto the top surface  402  of the array  400  of microelectronic elements  104 . In an example, removal of the temporary support carrier  602  from the array  400  of microelectronic elements  104  prior to bonding of the array  400  onto a second substrate  130  may result in deformation or breakage of the array  400  due to inadequate mechanical strength of the chip substrate  404 . 
     Referring to  FIG. 13  showing fabrication of a Microelectronic Element Array with DCA Pads  100  at stage  1300 , at step  520  the array  400  of microelectronic elements  104  is positioned on a second substrate  130  for DCA bonding of the array of UBM pads  124  and solder bumps  128  onto and in alignment with an array of conductors on the surface  1302  of the second substrate  130 . As an example, the second substrate  130  may include an array of bonding pads  132  formed of a conductor composition. In an implementation, bonding may be carried out by applying heat at a controlled temperature tolerable by the array  400  and the second substrate  130 . Pressure between the solder bumps  128  and the bonding pads  132  may, as an example, be applied. In an implementation, the solder bumps  128  may then be subjected to a reflow process. As an example, spaces  1304  between the array  400  and the second substrate  130  may be underfilled with an insulating composition. In an implementation, care is taken in such underfilling so that the temporary support carrier  602  and the microelectronic elements  104  are not contaminated by the insulating composition. As an example, the insulating composition may include silicon nitride. In another implementation, dicing of a wafer including multiple arrays  400  of microelectronic elements  104  is delayed until after completion of step  520 . 
     Referring to  FIG. 13 , at step  522  the temporary support carrier  602  may then be removed, yielding the Microelectronic Element Array with DCA Pads  100  DCA bonded onto the second substrate  130 . In an implementation, a solvent for the adhesive layer  610  may be applied to the perforations  604  and the temporary support carrier  602  may then be removed. In an implementation where a protective passivation layer  612  is present, it may then be suitably removed. The process  500  then ends at step  524 . 
     It will be understood that the foregoing description of numerous implementations has been presented for purposes of illustration and description. As an example, modifications may be made in the structures of the Microelectronic Element Arrays with DCA Pads  100  while providing the UBM pads and a chip substrate with a reduced path length of element conductors through the chip substrate for DCA bonding. This description is not exhaustive and does not limit the claimed invention to the precise forms disclosed. Modifications and variations are possible in light of the above description or may be acquired from practicing the invention. The claims and their equivalents define the scope of the invention.

Technology Classification (CPC): 7