Probe arrays and method for making

Abstract

Embodiments of invention are directed to the formation of microprobes (i.e. compliant electrical or electronic contact elements) on a temporary substrate, dicing individual probe arrays, and then transferring the arrays to space transformers or other permanent substrates. Some embodiments of the invention transfer probes to permanent substrates prior to separating the probes from a temporary substrate on which the probes were formed while other embodiments do the opposite. Some embodiments, remove sacrificial material prior to transfer while other embodiments remove sacrificial material after transfer. Some embodiments are directed to the bonding of first and second electric components together using one or more solder bumps with enhanced aspect ratios (i.e. height to width ratios) obtained as a result of surrounding the bumps at least in part with rings of a retention material. The retention material may act be a solder mask material.

1 . A method for fabricating a microprobe array, comprising: 
 fabricating at least a portion of each of a plurality of probes on a temporary substrate;    transferring the probes from the temporary substrate to a permanent substrate.    
     
     
         2 . The method of  claim 1 , wherein at least selected groups of probes on the temporary substrate have a spatial relationship that is to be maintained when they are transferred to the permanent substrate.  
     
     
         3 . The method of  claim 2  wherein a selectively located adhesion material is located on the permanent substrate in locations where probes of a selected group are to be attached.  
     
     
         4 . The method of  claim 2  wherein a selectively located adhesion material is located on an end of the probes after they are formed on the temporary substrate and thereafter the probes are transferred to the permanent substrate.  
     
     
         5 . The method of  claim 2  wherein a selectively located adhesion material is located on the permanent substrate in locations where probes of a selected group are to be attached and wherein a selectively located adhesion material is located on an end of the probes after they are formed on the temporary substrate and thereafter the probes are transferred to the permanent substrate.  
     
     
         6 . The method of  claim 1 , wherein transfer to the permanent substrate occurs prior to release of the probes from the temporary substrate.  
     
     
         7 . The method of  claim 6 , wherein transfer to the permanent substrate occurs after release of the probes from at least a portion of any sacrificial material that surrounded them during formation.  
     
     
         8 . The method of  claim 6 , wherein transfer to the permanent substrate occurs prior to release of the probes from any sacrificial material that surrounded them during formation.  
     
     
         9 . The method of  claim 1 , wherein transfer to the permanent substrate occurs after release of the probes from the temporary substrate.  
     
     
         10 . The method of  claim 9 , wherein transfer to the permanent substrate occurs prior to release of the probes from any sacrificial material that surrounded them during formation.  
     
     
         11 . The method of  claim 1 , wherein transfer to the permanent substrate occurs after release of the probes from at least a portion of any sacrificial material that surrounded them during formation.  
     
     
         12 . The method of  claim 1 , wherein the transferring of the probes from the temporary substrate to a permanent substrate, comprises: 
 a. transferring the probes from a temporary substrate to a second temporary substrate, and then    b. transferring the probes from the second temporary substrate to the permanent substrate.    
     
     
         13 . The method of  claim 1 , wherein the formation of the probes on the temporary substrate results in only partial formation of the probes and wherein completion of the formation of the probes occurs while the probes are attached to the permanent substrate.  
     
     
         14 . The method of  claim 1 , wherein prior to transferring the probes to the permanent substrate the probes undergo a heat treatment process capable of enhancing adhesion between layers of a material from which the probes are formed.  
     
     
         15 . The method of  claim 1 , wherein after transferring the probes to the permanent substrate the probes undergo a heat treatment process capable of enhancing adhesion between layers of material from which the probes are formed.  
     
     
         16 . The method of  claim 1 , wherein during transferring of the probes to the permanent substrate the probes are embedded in a conductive sacrificial material which is removed after transfer.  
     
     
         17 . The method of  claim 1 , wherein at least a substantial portion of the probes are fabricated from a plurality of layers of material, where each layer is fabricated on a previously formed layer, and where each layer comprises the deposition of at least one structural material which forms a portion of the probes and at least one sacrificial material that is removed after fabrication of the layers.  
     
     
         18 . The method of  claim 17  wherein the structural material comprises a metal and the sacrificial material comprises a metal.  
     
     
         19 . The method of  claim 17  wherein the probes are formed on a substrate that is sacrificial.  
     
     
         20 . The method of  claim 19  wherein the temporary substrate comprises a release layer and a non-sacrificial substrate portion that is reusable.  
     
     
         21 . The method of  claim 17  wherein the probes comprise a main body portion and a contact tip portion wherein the contact tip portion comprises a first material and the main body portion comprises a second material that is different from the first material.  
     
     
         22 . The method of  claim 21  wherein the tip portion is provide with a desired geometry via plating tip material into a mold formed by the mushrooming of a deposited conductive material over a dielectric material.  
     
     
         23 . The method of  claim 17  wherein the tip portion is formed prior to forming the main body portion and the main body portion is formed from a plurality of layers with a first layer formed on the tip portion and subsequent layers formed on previously formed layers.  
     
     
         24 . The method of  claim 1  wherein the probes are adhered directly to the permanent substrate via a bonding material.  
     
     
         25 . The method of  claim 24  wherein the bonding material comprises individual bumps of a solder material.  
     
     
         26 . The method of  claim 25  wherein the solder is reflowed and solidified prior to bringing it into bonding contact with the permanent substrate.  
     
     
         27 . The method of  claim 25  wherein the solder material is at least in part surrounded by a solder mask material which aids in inhibiting solder material from bridging between solder bonding regions that are intended to remain electrically isolated.  
     
     
         28 . The method of  claim 25  wherein individual bumps of the solder material are at least in part held by isolated columns of retention material that results in the solder bumps retaining more of their height upon reflow than would occur in the absence of the retention material.  
     
     
         29 . The method of  claim 28  wherein retention material inhibits the solder from bridging gaps between individual bumps.  
     
     
         30 . The method of  claim 1  wherein the probes are compliant.  
     
     
         31 . The method of  claim 30  wherein the compliance of the probes is primarily provided by the design of the probes in combination with a core material from which the probe is formed.  
     
     
         32 . The method of  claim 31  wherein a coating material of higher electrical conductive than the core material is made to coat at least a portion of the outer surface of the probes.  
     
     
         33 . The method of  claim 17  wherein each of the plurality of layers comprises an end-pointing detection pad region onto which material is not deposited.  
     
     
         34 . The method of  claim 1  wherein a plurality of permanent substrates are attached to a larger substrate.  
     
     
         35 . The method of  claim 35  wherein permanent substrates are attached to the large substrate via a bonding material that is made to flow and then resolidify.  
     
     
         36 . The method of  claim 35  wherein permanent substrate is attached to the larger substrate via a metallic frame that provides a compliant mounting for each probe die.  
     
     
         37 . The method of  claim 1 , wherein the position of the probes relative to the permanent substrate is set at least in part by shims that are formed along with the probes.  
     
     
         38 . The method of  claim 37  wherein the shims fit into recesses in the surface of the permanent substrate.  
     
     
         39 . The method of  claim 37  wherein the shims are formed of sacrificial material and are removed upon release of the probes from the sacrificial material.  
     
     
         40 . The method of  claim 37  wherein the shims are formed of structural material.  
     
     
         41 . The method of  claim 37  wherein the shims are formed within solder bumps that are used in adhering the probes to the permanent substrate.  
     
     
         42 . The method of  claim 1 , wherein the position of the probes relative to the permanent substrate is set at least in part by shims that are formed on the surface of the permanent substrate.  
     
     
         43 . The method of  claim 42  wherein the shims are formed of sacrificial material and are removed upon release of the probes from the sacrificial material.  
     
     
         44 . The method of  claim 1 , wherein the position of the probes relative to the permanent substrate is set at least in part by shims that are located between the permanent substrate and selected regions of sacrificial material that bridge gaps between the probes at the time of transfer.  
     
     
         45 . The method of  claim 1 , wherein the probes are held in a desired position relative to the permanent substrate at the time of transfer so as to control, at least in part, the positions of the probes relative to the permanent substrate during transfer.  
     
     
         46 . The method of  claim 45 , wherein the control of position is along at least one axis that is parallel to a plane of the bonding surface of the permanent substrate.  
     
     
         47 . The method of  claim 45 , wherein the control of position is along at an axis that is perpendicular to a plane of the bonding surface of the permanent substrate.  
     
     
         48 . The method of  claim 1 , wherein after transfer, the probes are worked and then ends of the probes that are distal from the permanent substrate are trimmed to establish a desired level of planarity of the array of distal probe ends.  
     
     
         49 . The method of  claim 49 , wherein the distal ends of the probes comprise tips for contacting a surface to be probed.  
     
     
         50 . The method of  claim 49 , wherein after trimming the distal ends, contact tips are formed on the distal ends of the probes.  
     
     
         51 . The method of  claim 49 , wherein after trimming the distal ends, contact tips are bonded to the distal ends of the probes.  
     
     
         52 . A method for bonding a first electric component to a second electric component, comprising: 
 forming a plurality of solder bumps on a first electric component, wherein the solder bumps are surrounded, at least in part by rings of a retention material;    bringing the solder bumps on the first component into contact with bonding locations on a second electric component;    heating the solder to cause melting and cooling the solder to bond the first and second components together, wherein the separation between the first and second components is larger than would have been achieved in similar circumstances in the absence of the columns of retention material.    
     
     
         53 . The method of  claim 52  wherein prior to bring the solder bumps into contact with the pads on the first substrate, reflowing the solder bumps.  
     
     
         54 . The method of  claim 52  wherein solder bumps have enhanced height to width aspect ratios due to the presence of the rings of retention material.  
     
     
         55 . The method of  claim 52  wherein retention material resists wetting by the solder and thereby functions as a solder mask material.  
     
     
         56 . A method for bonding a first electric component to a second electric component, comprising: 
 forming a plurality of solder bumps on a first electric component, wherein the solder bumps are surrounded, at least in part by rings of a retention material;    reflowing the solder material such that the height of the reflowed solder is greater than it would be in absence of the retention material;    bringing the solder bumps on the first component into contact with bonding locations on a second electric component; and    heating the solder to cause melting and cooling the solder to bond the first and second components together.