Method of and apparatus for forming three-dimensional structures integral with semiconductor based circuitry

Abstract

Enhanced Electrochemical fabrication processes are provided that can form three-dimensional multi-layer structures using semiconductor based circuitry as a substrate. Electrically functional portions of the structure are formed from structural material (e.g. nickel) that adheres to contact pads of the circuit. Aluminum contact pads and silicon structures are protected from copper diffusion damage by application of appropriate barrier layers.

I claim:  
     
         1 . An electrochemical fabrication process for producing a three-dimensional structure from a plurality of adhered layers, the process comprising: 
 (A) selectively depositing at least a portion of a layer onto the substrate, wherein the substrate may comprise previously deposited material;    (B) forming a plurality of layers such that successive layers are formed adjacent to and adhered to previously deposited layers, wherein said forming comprises repeating operation (A) a plurality of times;    wherein at least a plurality of the selective depositing operations comprise: 
 (1) locating a mask on or in proximity to a substrate;  
 (2) in presence of a plating solution, conducting an electric current between an anode and the substrate through the at least one opening in the mask, such that a selected deposition material is deposited onto the substrate to form at least a portion of a layer; and  
 (3) separating the selected preformed mask from the substrate;  
   wherein the substrate comprises a semiconductor wafer or single die containing electrical circuitry and having contact pads to which structural material is to connect; and    wherein the process of contacting the contact pads with structural material comprises in order: 
 (a) placing a protective coating over the contact pads;  
 (b) applying a layer of sacrificial material to a surface of the wafer,  
 (c) removing the protective coating from the contact pads; and  
 (d) applying a coating of structural material to the contact pads.  
   
     
     
         2 . The process of  claim 1  wherein a plurality of layers comprise at least one structural material and at least one sacrificial material.  
     
     
         3 . The process of  claim 1  wherein the applied layer of sacrificial material is thin compared to a desired coating thickness, and wherein after operation (b) and before operation (c), the process additional comprises: 
 (b2) thickening the thin layer to many times its original thickness via electroplating.  
 
     
     
         4 . The process of  claim 3 , wherein after performance of operation (b2) and before operation (c), the process additionally comprises: 
 (b3) planarizing the sacrificial material and the protective coating.    
     
     
         5 . The process of  claim 4 , wherein after performance of operation (d), the process additionally comprises: 
 (e) planarizing the structural and sacrificial materials.    
     
     
         6 . The process of  claim 5 , wherein after performance of operation (e), the process additionally comprises: 
 (e) forming a plurality of layers comprising at least one structural material and at least one sacrificial material.    
     
     
         7 . The process of  claim 1  additionally comprising: 
 (A) supplying a plurality of preformed masks, wherein each mask comprises a patterned dielectric material that includes at least one opening through which deposition can take place during the formation of at least a portion of a layer, and wherein each mask comprises a support structure that supports the patterned dielectric material; and  
 wherein the locating of a mask on or in proximity to a substrate comprises contacting the substrate and the dielectric material of a selected preformed mask.  
 
     
     
         8 . The process of  claim 1  wherein the locating of a mask on or in proximity to a substrate comprises forming and adhering a patterned mask to the substrate.  
     
     
         9 . The process of  claim 1  wherein prior to operation (d), the process further comprises applying a transition treatment to the contact pads.  
     
     
         10 . The process of  claim 9  wherein transition treatment comprises application of an adhesion promoter.  
     
     
         11 . The process of  claim 9  wherein transition treatment comprises application of a diffusion barrier.  
     
     
         12 . An electrochemical fabrication process for producing a three-dimensional structure from a plurality of adhered layers, the process comprising: 
 (A) selectively depositing at least a portion of a layer onto the substrate, wherein the substrate may comprise previously deposited material;    (B) forming a plurality of layers such that successive layers are formed adjacent to and adhered to previously deposited layers, wherein said forming comprises repeating operation (A) a plurality of times;    wherein at least a plurality of the selective depositing operations comprise: 
 (1) locating a mask on or in proximity to a substrate;  
 (2) in presence of a plating solution, conducting an electric current between an anode and the substrate through the at least one opening in the mask, such that a selected deposition material is deposited onto the substrate to form at least a portion of a layer; and  
 (3) separating the selected preformed mask from the substrate;  
   wherein the substrate comprises a semiconductor wafer or single die containing electrical circuitry and having contact pads to which structural material is to connect; and    wherein the process of contacting the contact pads with structural material comprises, in order: 
 (a) depositing sacrificial material onto a surface of the wafer or die in regions excluding contact pad regions; and  
 (b) depositing structural material to at least selected contact pad regions.  
   
     
     
         13 . The process of  claim 12  wherein a plurality of layers comprise at least one structural material and at least one sacrificial material.  
     
     
         14 . The process of  claim 12  wherein prior to performance of operation (a), the process additionally comprises placing a protective coating over the contact pads.  
     
     
         15 . The process of  claim 14  wherein after performance of operation (a), the process additionally comprises: 
 (a3) removing the protective coating from at least selected contact pads.  
 
     
     
         16 . The process of  claim 14  wherein operation (a) comprises depositing sacrificial material to a thickness less than a desired thickness using a first deposition operation and then increasing the thickness of the deposited sacrificial material using a different deposition operation.  
     
     
         17 . The process of  claim 16  wherein first deposition operation comprises something other than an electroplating operation and wherein the second deposition operation comprises at least an electroplating operation.  
     
     
         18 . The process of  claim 12  wherein after depositing the sacrificial material and depositing the structural material, planarizing the deposited materials to yield a substrate comprising selective regions of sacrificial and structural material on to which additional layers of a structural material and a sacrificial material will be deposited.  
     
     
         19 . The process of  claim 12  wherein the process further comprises applying a transition treatment to the contact pads.  
     
     
         20 . The process of  claim 19  wherein transition treatment comprises application of an adhesion promoter.  
     
     
         21 . The process of  claim 19  wherein transition treatment comprises application of a diffusion barrier.  
     
     
         22 . The process of  claim 12  wherein the structural material comprises nickel.  
     
     
         23 . The process of  claim 12  wherein the sacrificial material comprise copper.  
     
     
         24 . The process of  claim 12  additionally comprising: 
 (A) supplying a plurality of preformed masks, wherein each mask comprises a patterned dielectric material that includes at least one opening through which deposition can take place during the formation of at least a portion of a layer, and wherein each mask comprises a support structure that supports the patterned dielectric material; and  
 wherein the locating of a mask on or in proximity to a substrate comprises contacting the substrate and the dielectric material of a selected preformed mask.  
 
     
     
         25 . The process of  claim 12  wherein the locating of a mask on or in proximity to a substrate comprises forming and adhering a patterned mask to the substrate.  
     
     
         26 . An electrochemical fabrication process for producing a three-dimensional structure from a plurality of adhered layers, the process comprising: 
 (A) selectively depositing at least a portion of a layer onto the substrate, wherein the substrate may comprise previously deposited material;    (B) forming a plurality of layers such that successive layers are formed adjacent to and adhered to previously deposited layers, wherein said forming comprises repeating operation (A) a plurality of times;    wherein at least a plurality of the selective depositing operations comprise: 
 (1) locating a mask on or in proximity to a substrate;  
 (2) in presence of a plating solution, conducting an electric current between an anode and the substrate through the at least one opening in the mask, such that a selected deposition material is deposited onto the substrate to form at least a portion of a layer; and  
 (3) separating the selected preformed mask from the substrate;  
   wherein the substrate comprises a semiconductor wafer or single die containing electrical circuitry and having contact pads to which structural material is to connect and having a passivation layer; and    wherein the process of contacting the contact pads with structural material comprises in order: 
 (a) locating an electroless plating catalyst for a sacrificial material on at least a portion of the surface of the passivation layer;  
 (b) electroless plating the sacrificial material on to the passivation layer;  
   (c) applying a structural material over the contact pads.    
     
     
         27 . The process of  claim 26  wherein the sacrificial material comprises copper.  
     
     
         28 . The process of  claim 26  wherein the structural material comprises nickel.  
     
     
         29 . The process of  claim 26  wherein the applying of the structural material comprises electroplating the structural material.  
     
     
         30 . The process of  claim 26  wherein after operation (b), the process additionally comprises: 
 (b2) increasing the thickness of the sacrificial material by electroplating additional sacrificial material onto the electroless plated sacrificial material.  
 
     
     
         31 . The process of  claim 26  wherein after operation (c), the process additionally comprises: 
 (d) planarizing the deposited materials.  
 
     
     
         32 . The process of  claim 26  wherein a plurality of layers comprise at least one structural material and at least one sacrificial material.  
     
     
         33 . The process of  claim 26  additionally comprising: 
 (A) supplying a plurality of preformed masks, wherein each mask comprises a patterned dielectric material that includes at least one opening through which deposition can take place during the formation of at least a portion of a layer, and wherein each mask comprises a support structure that supports the patterned dielectric material; and  
 wherein the locating of a mask on or in proximity to a substrate comprises contacting the substrate and the dielectric material of a selected preformed mask.  
 
     
     
         34 . The process of  claim 26  wherein the locating of a mask on or in proximity to a substrate comprises forming and adhering a patterned mask to the substrate.