Fluid cooled trace/via hybrid structure and method of manufacture

An interposer structure including a dielectric base material, and a metal based interconnect structure extending through the dielectric base material from a first side of the dielectric base material to an opposing second side of the dielectric base material. At least one metal line of the metal based interconnect structure extends from the first side of the dielectric base material to the second side of the dielectric base material and has a first non-linear portion. A fluidic passage extends through the dielectric base material, wherein the fluidic passage has a second non-linear portion.

BACKGROUND

Technical Field

The present invention generally relates to interconnect structures, and more particularly to forming interconnect structures that also include fluid cooling passageways.

Description of the Related Art

Copper wires and interconnects typically seen in printed circuit board (PCBs), interposers and package substrates. An interposer is a form of interconnect that is placed between a printed circuit board (PCB) and a processor. As chips continue to scale, chips become denser requiring a higher pin count for the input/output (I/O). An interposer is used to spread a connection to a wider pitch or to re-route to a different connection. In conventional interconnect structures that extend through a substrate, the metal lines are limited to being straight. Silicon interposers with microfluidic cooling paths have been explored as a way to cool stacks of microprocessor chips. Microfluidic cooling paths formed into silicon interposers are typically limited by expensive and complicated photolithography techniques. Similar to metal lines, microfluidic cooling paths are typically limited to being straight in geometry.

SUMMARY

In one embodiment, a method of forming an interconnect in combination with fluidic cooling structures is described herein that includes providing a sacrificial interconnect trace structure and a sacrificial fluidic cooling structure using an additive forming method; and forming a continuous seed metal layer on the sacrificial trace structure and the sacrificial fluidic cooling structure. The sacrificial interconnect trace structure is removed, wherein the sacrificial fluidic cooling structure remains. An interconnect metal layer is formed on the continuous seed layer that was present on the sacrificial trace structure. A dielectric material is formed on the interconnect metal layer to encapsulate a majority of the interconnect metal layer, wherein ends of the interconnect metal layer are exposed through one surface of the dielectric material to provide the interconnect extending into the dielectric material. The sacrificial fluid cooling structure can then be removed selectively to the continuous seed metal layer to provide fluidic passages through the dielectric material.

In another embodiment, the method of forming the interconnect in combination with the fluidic cooling structures may include providing a sacrificial interconnect trace structure having at least one first non-linear portion and a sacrificial fluidic cooling structure having at least one second non-linear portion using an additive forming method. The method continuous with forming a continuous seed metal layer on the sacrificial trace structure and the sacrificial fluidic cooling structure. The sacrificial interconnect trace structure is removed, wherein the sacrificial fluidic cooling structure remains. An interconnect metal layer is formed on the continuous seed layer that was present on the sacrificial trace structure. The interconnect metal layer has the at least one second non-linear portion. A dielectric material is formed on the interconnect metal layer to encapsulate a majority of the interconnect metal layer, wherein ends of the interconnect metal layer are exposed through one surface of the dielectric material to provide the interconnect extending into the dielectric material. The sacrificial fluid cooling structure is removed selectively to the continuous seed metal layer to provide fluidic passages having the at least one second non-linear portion that extend through the dielectric material.

In another aspect, an interposer structure is provided. The interposer structure may include a dielectric base material, and a metal based interconnect structure extending through the dielectric base material from a first side of the dielectric base material to an opposing second side of the dielectric base material. At least one metal line of the metal based interconnect structure extends from the first side of the dielectric base material to the second side of the dielectric base material and has a first non-linear portion. A fluidic passage extends through the dielectric base material, wherein the fluidic passage has a second non-linear portion.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and methods are disclosed herein; however, it is to be understood that the disclosed embodiments are merely illustrative of the claimed structures and methods that may be embodied in various forms. In addition, each of the examples given in connection with the various embodiments are intended to be illustrative, and not restrictive. Further, the figures are not necessarily to scale, some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the methods and structures of the present disclosure. For purposes of the description hereinafter, the terms “upper”, “lower”, “right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, and derivatives thereof shall relate to the embodiments of the disclosure, as it is oriented in the drawing figures. The term “positioned on” means that a first element, such as a first structure, is present on a second element, such as a second structure, wherein intervening elements, such as an interface structure, e.g. interface layer, may be present between the first element and the second element. The term “direct contact” means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary conducting, insulating or semiconductor layers at the interface of the two elements.

Silicon interposers with microfluidic/cooling paths have been explored as an effective way to cool chip stacking solutions, e.g., 2.5 dimensional and 3 dimensions chip stacking solutions. Typically, forming microfluidic cooling paths require expensive photolithography techniques to build the fluidic passages into the interposer structure. These structures are typically limited by thickness, because the through interposer vias must by manufactured from traditional photolithography, etching, and plating techniques. Copper wires and interconnects typically seen in printed circuit boards, interposers and package substrates are typically limited to being manufactured in straight horizontal and vertical directions.

In some embodiments, the methods and structures disclosed herein provide interconnect structures having fluidic passages extending through the dielectric body of the interconnect structure. In some embodiments, the methods and structures disclosed herein provide for forming electrically conductive lines having curvatures, angled portions and orthogonal portions through dielectric structures. In some embodiments, the methods and structures disclosed herein manufacture a copper trace, via, pad hybrid structure, including orthogonal and curved pathways. This can allow for shorter interconnect, lower latency and lower impedance in the electrical devices employing the structures and methods described herein. The fluidic passages extending through the dielectric body of the interconnect structure may also include curvatures, angled portions and orthogonal portions through dielectric structures.

FIGS. 1A and 1Billustrate some embodiments, of an interposer100a,100bwhich is one example of an interconnect structure within the scope of the present disclosure, that includes a metal based interconnect structure20a,20b,20c,20d,20e, and a fluidic passage30. In some embodiments, the interposer100a,100bincludes a dielectric base material, i.e., dielectric body13, and a metal based interconnect structure20a,20b,20c,20d,20eextending through said dielectric base material from a first side of the dielectric base material to an opposing second side of the dielectric base material. At least one fluidic passage30may also extends through the dielectric base material13in which one first opening of the at least one fluidic passage30is an entry point for a cooling medium to be introduced to the dielectric base material13, and at least one second opening of the at least one fluidic package30is an exit point for the cooling medium within the fluidic passage30to exit the dielectric base material. The entry and exit points for the fluid passage30may be on a same sidewall of the dielectric base material13, or may be present on opposing sidewalls of the dielectric base material13. The fluid passages30are suitable for water, water based coolants, alcohol based coolants, refrigerants, as well as other fluidic coolants typically employed to cool electronics. In other embodiments, the fluid passages30may be used to pass forced cool air through the dielectric material13.

Still referring toFIGS. 1A and 1B, in some embodiments, solder connections16, e.g., solder bumps, may be present on opposing sides of the dielectric body13on exposed surfaces of said metal based interconnect structure.

In some embodiments, the metal based interconnect structure20a,20b,20c,20d,20eextends through the dielectric body13an provide for electric communication across the interposer100a,100bfrom a first side of the interposer100a,100bthat may be in electric contact with a microprocessor200to a second side of the interposer100a,100b. The second side of the interposer100a,100bmay be in contact with a supporting substrate (not shown), in which the supporting substrate may include its own interconnect structure that is to be positioned in electrical communication with the metal based interconnect structure20a,20b,20c,20d,20eof the interposer100a,100b.

The metal based interconnect structure20a,20b,20c,20d,20emay be composed of any electrically conductive metal. “Electrically conductive” as used through the present disclosure means a material typically having a room temperature conductivity of greater than 105(S/m). In some embodiments, the metal based interconnect structure20a,20b,20c,20d,20emay be comprised of aluminum (Al), copper (Cu), tungsten (W), tantalum (Ta), platinum (Pt), gold (Au), tin (Sn), silver (Ag), and other elemental metals. In other embodiment, the metal based interconnect structure20a,20b,20c,20d,20emay be comprised of metal nitrides, such as tantalum nitride (TaN), titanium nitride (TiN), tungsten nitride (WN), and combinations thereof.

As noted above, the metal based interconnect structure20a,20b,20c,20d,20eincludes non-linear portions. Referring to the interposer100A that is depicted inFIG. 1A, the metal based interconnect structures20amay include angled portions. For example, linear line portions of the metal based interconnect structure20aintersect at orthogonal angles αl, as depicted inFIG. 1A. Orthogonal refers to right angles, i.e., angles of 90°. It is noted that this is only one example of the angle between intersecting linear portions of the metal based interconnect structures20a. For example, in one embodiment, the angle α1connecting intersecting liner portions of the metal based interconnect structures20amay range from 15° to 85°. In other embodiments, the angle α1connecting intersecting liner portions of the metal based interconnect structures20amay range from 30° to 60°. In some examples, the angle α1connecting intersecting liner portions of the metal based interconnect structures20amay be equal to 15°, 20°, 25°, 30°, 35°, 45°, 55°, 60°, 65°, 70°, 75°, 80°, 85° and 90°.

The fluidic passage30depicted inFIG. 1Amay also have a non-linear portion. For example, the fluidic passage30may include two linear portions that intersect at an orthogonal angle similar to the angled portions of the metal based interconnect identified by reference number12a. The fluidic passage30may include two substantially linear portions intersecting at any angle that has been described above for the intersecting angle of the metal based interconnects12adescribed with reference toFIG. 1A.

Referring to the interposer100B that is depicted inFIG. 1B, the metal based interconnect structures20a,20b,20c,20d,20emay include curved portions. A curve is a line that is not straight. In some embodiments, the curvature of the metal line of the metal based interconnect structure is a single arc extending continuously from a first side to a second side of the dielectric base material as identified by reference number20d. In another embodiment, the curvature of the metal based interconnect structure has multiple arcs, as depicted by the structures having reference numbers20b,20cand20e. For example, the curvature may be sigmoidal. In yet other embodiments, the curvature for the metal lines of the metal based interconnect structures may include a first arc at a first side of the dielectric body13, and a second arc at a second side of the dielectric body13A, wherein a linear portion of the metal based interconnect structure is present therebetween, as illustrated by the structure having reference number20b. In another embodiment, the metal based interconnect structure may be “U” shaped, in which both ends of the interconnect exit the dielectric base material13on a same side.

The fluidic passage30depicted inFIG. 1Bmay also have a non-linear portion. For example, the fluidic passage30may include at least one curvature. In some examples, the fluidic passage30may include at least one curvature having a geometry similar to the curvatures that have been described for the metal interconnect structures20b,20c,20d,20ethat are depicted inFIG. 1B. For example, the fluidic passage30may include a single arc extending continuously from a first side to a second side of the dielectric base material13. In another embodiment, the fluidic passage30may include multiple arcs. In yet another embodiment, the fluidic passage30includes a first arc at a first side of the dielectric base material13, and a second arc at a second side of the dielectric base material, wherein a linear portion of the passage is present therebetween. In another embodiment, the fluidic passage30may be “U” shaped, in which both ends of the passage exit the dielectric base material13on a same side.

It is noted that the angled structures that provide the metal based interconnect structures20ainFIG. 1A, and the curved structures that provide the metal based interconnect structures20b,20c,20d,20e, may be employed simultaneously with linear metal lines in the same dielectric body13. For example,FIG. 1Billustrates linear metal lines identified by reference number20f.

Although the structure depicted inFIGS. 1A and 1B, is an interposer, the methods and structures disclosed herein are equally applicable to other forms of interconnect structures, as well as printed circuit boards (PCBs) and components related to printed circuit boards (PCBs).

It is further noted the metal interconnect structures20a,20b,20c,20d,20and the fluidic passages30are positioned along different planes within the dielectric body13, and do not intersect. Further details of the methods of the present disclosure are now discussed with greater detail with reference toFIGS. 2-8B.

FIG. 2depicts providing a sacrificial interconnect trace structure10and a sacrificial fluidic cooling structure15using an additive forming method. The term ‘sacrificial” denotes a structure that facilitates the formation of a material layer within a final device structure, yet the sacrificial structure is not present in the final device structure. The sacrificial interconnect trace structure10provides a structure having a geometry, e.g., including lines having angles or curvatures, that provides the geometry of the later formed metal lines of the metal based interconnect structures, e.g., the structures identified by reference numbers20a,20b,20c,20d,20einFIGS. 1A and 1B. The sacrificial fluidic cooling structure15provides a structure having a geometry, e.g., including lines having angles or curvatures, that provides the geometry of the later formed fluidic passages30, e.g., the structures identified by reference number30inFIGS. 1A and 1B.

Additive Manufacturing (AM) is an appropriate name to describe the technologies that build 3D objects by adding layer-upon-layer of material, whether the material is dielectric, plastic, metal, of semiconductor composition or combination thereof. The sacrificial trace structure10and the sacrificial fluidic cooling structure15is formed using a three dimensional additive method selected from the group consisting of stereolithography, self-propagating waveguide formation, fused deposition modeling (FDM), selective laser sintering (SLS), continuous liquid interface production (CLIP), digital light processing (DLP), material jetting, and combinations thereof.

Stereolithography a technique or process for creating three-dimensional objects, in which a computer-controlled moving laser beam is used to build up the required structure, layer by layer, from a liquid polymer that hardens on contact with laser light. In some embodiments, a stereolithography technique provides a method to build a 3D microstructure in a layer-by-layer process, which can involve a platform (e.g., substrate) that is lowered into a photo-monomer bath in discrete steps. At each layer, a laser is used to scan over the area of the photo-monomer that is to be cured (i.e., polymerized) for that particular layer. Once the layer is cured, the platform is lowered by a specific amount (i.e., determined by the processing parameters and desired feature/surface resolution), and the process is repeated until the complete 3D structure is created.

Fused deposition modeling (FDM) is an additive manufacturing technology, which works on an “additive” principle by laying down material in layers; a plastic filament or metal wire is unwound from a coil and supplies material to produce a part. In some embodiments, FDM builds parts up layer-by-layer by heating and extruding thermoplastic filament.

Self-propagating waveguide formation typically includes the use of a polymer foam, or other cellular material. Self-propagating waveguide may for ordered open cellular polymer materials with micro-lattice structures and features. These materials can be formed by exposing a two-dimensional mask with a pattern of circular apertures that is covering a reservoir containing a photomonomer. More specifically, collimated UV light can be used to expose liquid polymer through a mask to form polymer waveguide. Within the photomonomer, self-propagating photopolymer waveguides originate at each aperture in the direction of the UV collimated beam and polymerize together at points of intersection. By simultaneously forming an interconnected array of these fibers in three-dimensions and removing the uncured monomer, three dimensional lattice-based open-cellular polymer materials can be fabricated,

In one embodiments, the sacrificial interconnect trace structure10and the sacrificial fluidic cooling structure15is comprised of a polymeric material. When the sacrificial interconnect trace structure10and the sacrificial fluidic cooling structure15is formed using stereolithography, the sacrificial interconnect trace structure10and the sacrificial fluidic cooling structure15can be composed of a photohardenable resin compositions comprises of at least one photo-polymerizable compound, such as a photo-polymerizable modified urethane (meth)acrylate compound, an oligoester acrylate compound, an epoxyacrylate compound, an epoxy compound, a polyimide compound, an aminoalkyd compound, and a vinyl ether compound, as a main component, and a photosensitive polymerization initiator. When the sacrificial trace structure10and the sacrificial fluidic cooling structure15is formed using FDM, the sacrificial trace structure10and the sacrificial fluidic cooling structure15can be composed of Acrylonitrile Butadiene Styrene (ABS), Polylactic acid (PLA), Polycarbonate (PC), Polyamide (PA), Polystyrene (PS), Polyether ether ketone (PEEK), lignin, rubber, and combinations thereof. When the sacrificial interconnect trace structure10and the sacrificial fluidic cooling structure15is formed using self-propagating waveguide formation, the sacrificial interconnect trace structure10and the sacrificial fluidic cooling structure15may be composed of thiol-ene polymer.

It is noted that the above compositions for the sacrificial interconnect trace structure10and the sacrificial fluidic cooling structure15and the additive manufacturing processes are provided for illustrative purposes and are not intended to limit the disclosed methods and structures to only the above examples. For example, in addition to the above examples, the sacrificial interconnect trace structure10and the sacrificial fluidic cooling structure15may also be formed using wire or textile layup, modular assembly, deformed perforated sheet lattice assembly, as well as other three dimensional additive methods.

Although the sacrificial trace structure10is depicted as having linear metal line portions, the sacrificial trace structure may include non-linear metal line portions, e.g., angled portions and curved portions, to provide metal interconnect structures similar to the non-linear metal lines of the metal interconnect structures20a,20b,20c,20d,20eas depicted inFIGS. 1A and 1B. The sacrificial fluidic cooling structure15may have any of the geometries for the fluidic passages30described above with reference toFIGS. 1A and 1B.

FIG. 3depicts one embodiment of forming a continuous seed metal layer11on the sacrificial trace structure10and the sacrificial fluidic cooling structure15. The continuous seed metal layer11may be composed of any metal, such as nickel, copper, aluminum, tungsten, titanium, platinum, gold, tin, silver, and combinations thereof. The thickness of the continuous seed metal layer11is selected to provide a seed layer for subsequent metal depositions, and have a thickness that is suitable to not be removed during the process step for removing the sacrificial trace structure10and the sacrificial fluidic cooling structure15. The continuous seed metal layer10and the sacrificial fluidic cooling structure15is a deposited metal layer having a conformal thickness. The term “conformal” denotes a layer having a thickness that does not deviate from greater than or less than 30% of an average value for the thickness of the layer. By continuous it is meant that the continuous seed metal layer10is free of breaks.

The continuous seed metal layer11may be deposited using a physical vapor deposition (PVD) process. For example, the continuous seed metal layer11may be composed of nickel deposited using electroless plating. Electroless nickel plating (EN) is an auto-catalytic chemical technique used to deposit a layer of nickel-phosphorus or nickel-boron alloy. The process may employ a reducing agent, e.g., hydrated sodium hypophosphite (NaPO2H2.H2O) which reacts with the metal ions to deposit metal. In other embodiments, the continuous seed metal layer11may be formed using electroplating and/or sputtering. In other embodiments, the continuous seed metal layer11may be formed using atomic layer deposition (ALD) or chemical vapor deposition (CVD), e.g., plasma enhanced chemical vapor deposition (PECVD). The thickness of the continuous seed metal layer11may have a thickness ranging from 5 nm to 100 μm. In another embodiment, the thickness of the continuous seed metal layer11may range from 1 μm to 100 μm. In another embodiment, the thickness of the continuous seed metal layer11may range from 10 nm to 50 nm. In some embodiments, the polymeric base material9may facilitate uniformity in the deposition of the continuous seed metal layer11on the portions of the sacrificial interconnect trace structure10that subsequently provide the metal lines of the metal interconnect structure of the interposer.

It is noted that in some embodiments, a block mask may be formed atop a portion of the sacrificial trace structure10prior to forming the continuous seed metal layer11to select which portions of the sacrificial interconnect trace structure10and the sacrificial fluidic cooling structure15that may be coated with the continuous seed metal layer11.

FIG. 4depicts one embodiment of removing the sacrificial interconnect trace structure10, wherein the continuous seed metal layer11remains. Masking is utilized to ensure that the process steps for removing the sacrificial interconnect trace structure10do not also remove the sacrificial fluidic cooling structure15. In some embodiments, masks for protecting the sacrificial fluidic cooling structure15may be formed from photoresist material using photolithography and developments processes.

In some embodiments, the sacrificial interconnect trace structure10may be removed by dissolving the polymeric material from which the sacrificial interconnect trace structure10was additively formed. In some embodiments, the sacrificial interconnect trace structure10may be removed by an etch process that is selective to the continuous seed metal layer11. As used herein, the term “selective” in reference to a material removal process denotes that the rate of material removal for a first material is greater than the rate of removal for at least another material of the structure to which the material removal process is being applied. For example, in one embodiment, a selective etch may include an etch chemistry that removes a first material selectively to a second material by a ratio of 100:1 or greater. The selective etch process may be a wet chemical etch or a dry etch.

FIG. 5illustrates one embodiment of forming an interconnect metal layer20on the continuous seed metal layer11. In one embodiment, the interconnect metal layer20may be deposited directly on the continuous seed metal layer11at a thickness that provides metal lines for the interconnect metal layer20that are hollow, as depicted inFIG. 5. In another embodiment, the interconnect metal layer20is deposited directly on the continuous metal seed layer11at a thickness to provide solid metal lines for the interconnect metal layer20of the interposer.

The interconnect metal layer20may be composed of any metal, such as the metal being deposited provides an electrically conducive material. For example, the interconnect metal layer20may be composed of copper, nickel, aluminum, titanium, tungsten, tantalum, platinum, gold, silver, tin and combinations thereof. In some embodiments, the interconnect metal layer20may be deposited using a physical vapor deposition (PVD) method, such as sputtering, evaporative deposition, and combinations thereof. In other embodiments, the interconnect metal layer20is formed using a plating method, such as electrolytic plating, electroless plating, and combinations thereof. In one embodiment, the interconnect metal layer20is formed composed of copper deposited using electroplating. One example of a plating bath composition that is suitable for electroplating the interconnect metal layer12of copper may include a copper sulfate (CuSO4) solution with sulfuric acid (H2SO4). In some embodiments, electroless deposition of copper (Cu) may rely on the presence of a reducing agent, for example formaldehyde (HCHO), which reacts with the copper (Cu) metal ions to deposit the metal. In some other embodiments, the metal for the interconnect metal layer20may be deposited using a chemical vapor deposition (CVD) process, such as plasma enhanced chemical vapor deposition (PECVD) and metal organic chemical vapor deposition (MOCVD). In yet other embodiments, the metal for the interconnect metal layer20may be deposited using atomic layer deposition (ALD).

Still referring toFIG. 5, a metal coating layer21is also formed on the sacrificial fluidic cooling structure15. The metal coating layer21may be formed using the process steps that provide the interconnect metal layer20. Therefore, the metal coating layer21may have the same composition as the interconnect metal layer20, and may be formed using the same forming process. For example, the metal coating layer21may have a conformal thickness that is directly formed on the outer surfaces of the sacrificial fluidic cooling structure15.

FIG. 6depicts one embodiment of a dielectric material13being formed on the interconnect metal layer20and the metal coating layer21. The dielectric material13for encapsulating the interconnect metal layer20and the metal coating layer21that is present on the sacrificial fluidic cooling structure15can be composed of any dielectric or polymeric material that can be deposited in a manner that fills the voids between the adjacent interconnect metal layers20and metal coating layer21/sacrificial cooling structure15, in which the dielectric material13provides the dielectric body13of the interposer. In some embodiments, the dielectric material13may be an oxide, nitride or oxynitride material. In some examples, the dielectric material13may be selected from the group consisting of SiO2, Si3N4, SiOxNy, SiC, SiCO, SiCOH, and SiCH compounds, the above-mentioned silicon containing materials with some or all of the Si replaced by Ge, carbon doped oxides, inorganic oxides, inorganic polymers, hybrid polymers, organic polymers such as polyimides, polyphenylene oxide, or SiLK™, other carbon containing materials, organo-inorganic materials such as spin-on glasses and silsesquioxane-based materials, and diamond-like carbon (DLC), also known as amorphous hydrogenated carbon, α-C:H). Additional choices for the interlevel dielectric layer include any of the aforementioned materials in porous form, or in a form that changes during processing to or from being porous and/or permeable to being non-porous and/or non-permeable. The dielectric material13may be deposited using spin on deposition, chemical vapor deposition (CVD), injection molding, transfer molding, deposition from solution, dip coating, spray coating, and a vacuum may be employed to draw the dielectric material13within narrow passageways to ensure that the dielectric material13fully encapsulates the interconnect metal layers20and the and metal coating layer21/sacrificial cooling structure15.

FIG. 6also depicts planarizing the opposing sidewalls of the dielectric material13to expose the ends of the interconnect metal layers20so that the interconnect metal lines extend through the dielectric body13and provide points for being engaged in electrical communication to the structures that are engaged to the interposer. The planarization process also exposes ends of the sacrificial cooping structure15. The planarization process may be provided by grinding, polishing, chemical mechanical planarization (CMP) or a combination thereof.

FIGS. 7A and 7Billustrate some embodiments of removing the sacrificial cooling structure15to provide the fluidic passage30.FIG. 7Aillustrates one embodiment of removing the sacrificial fluid cooling structure15selectively to the continuous seed metal layer11to provide fluidic passages30through the dielectric material13, in which the inlets to the fluidic passage30are on one side of the body of the dielectric material13. The sacrificial cooling structure15may be removed selectively to the portion of the continuous seed metal layer11, so that the continuous seed metal layer11remains after the sacrificial cooling structure is removed. In some embodiments, the sacrificial cooling structure15may be removed by dissolving the polymeric material from which the sacrificial cooling structure15was additively formed. In some embodiments, the sacrificial cooling structure15may be removed by a selective etch process. As used herein, the term “selective” in reference to a material removal process denotes that the rate of material removal for a first material is greater than the rate of removal for at least another material of the structure to which the material removal process is being applied. For example, in one embodiment, a selective etch may include an etch chemistry that removes a first material selectively to a second material by a ratio of 100:1 or greater. The selective etch process may be a wet chemical etch or a dry etch. Although, not depicted block masks may be employed to protect portions of the structure that need to be protected from the process sequencing that removes the sacrificial cooling structure15.

FIG. 7Bdepicts one embodiment of removing the sacrificial fluid cooling structure15selectively to the continuous seed metal layer11to provide fluidic passages30through the dielectric material13, in which the inlets to the fluidic passage30are on opposing sides of the body of the dielectric material13. In some embodiments, the structure including the fluidic channel depicted inFIG. 7Bcan be formed from the structure depicted inFIG. 7A, by sectioning off the end portions of the interposer.

In some embodiments, solder bump processing may be applied to the structure depicted inFIGS. 7A and 7B. Solder bumps (also referred to as “solder balls”), such as C4 (controlled collapse chip connection) bumps, can be used to bond a chip to a chip carrier or to a chip to an interposer and then bond the interposer to the chip carrier. More specifically, solder bumps/solder balls16, as depicted inFIG. 1, are formed on the exposed ends of the metal wires that provide the metal interconnect structure20a,20b,20c,20d,20e,20f. The term “solder”, as used herein, refers to any metal or metallic compound or alloy that is melted and then allowed to cool in order to join two or more metallic surfaces together. Generally speaking, solders have melting temperatures in the range of 150° C. to 250° C. Solder bumps may be small spheres of solder (solder balls) that are bonded to contact areas, interconnect lines or pads of semiconductor devices. In some embodiments, the solder bumps can be made from lead-free solder mixtures or lead tin solder. The solder bumps16may be deposited using injection molding soldering (IMS) or sputtering.

FIGS. 8A and 8Bdepicting a cooling fluid35passing through the fluidic passages30of the structure30depicted inFIG. 7A. The cooling fluid35may be water or water based. In some embodiments, the cooling fluid35may be alcohol based. In other embodiments, the cooling fluid35may include refrigerants. In even further embodiments, air may be substituted for the cooling fluid35, wherein forced air at cooling temperatures can be passed through the fluidic passages.