Highly conductive composition for wafer coating

Abstract

A conductive composition for coating a semiconductor wafer comprises conductive filler that has an average particle size of less than 2 microns and a maximum particle size of less than 10 microns, a first resin that has a softening point between 80-260 ° C., solvent, curing agent, and a second resin, wherein at room temperature the first resin is substantially soluble in the solvent.

1 . A semiconductor device formed by bonding a semiconductor die to a substrate using a B-staged adhesive, wherein before B-staging the adhesive comprises:
 a) 66 to 80 wt % conductive filler that has an average particle size of less than 2 microns and a maximum particle size of less than 10 microns,   b) 5 to 25 wt % first resin that has a softening point between 80-260° C.,   c) 5 to 25 wt % solvent,   d) 0 to 5 wt % curing agent, and   e) 0 to 20 wt % second resin,   
       and wherein at room temperature the first resin is substantially soluble in the solvent. 
     
     
         2 . The semiconductor device of  claim 1  wherein the semiconductor device is a discrete device. 
     
     
         3 . A method for making a semiconductor device, comprising:
 (a) providing a semiconductor wafer having a front side that is active and a back side opposed to the front side that is inactive,   (b) providing a conductive adhesive that comprises filler having a maximum particle size of less than 10 microns,   (c) applying the conductive adhesive to the back side of the semiconductor wafer to form a conductive adhesive layer with an exposed side opposite the front side of the semiconductor wafer,   (d) B-staging the conductive adhesive layer to form a B-staged wafer,   (e) securing the exposed side of the conductive adhesive layer of the B-staged wafer to a substrate to form a semiconductor device, and   (f) curing the semiconductor device;   wherein after B-staging the conductive adhesive layer has a surface roughness of less than 12 microns and after cure the conductive adhesive layer has an elastic modulus of greater than 500 MPa at 250° C., a thermal conductivity at room temperature of greater than 3.8 W/mK, and a volume resistivity of less than 0.0003 ohms-cm at room temperature.   
     
     
         4 . The method of  claim 3  wherein the conductive adhesive comprises:
 a) 66 to 80 wt % conductive filler that has an average particle size of less than 2 microns and a maximum particle size of less than 10 microns,   b) 5 to 25 wt % first resin that has a softening point between 80-260° C.,   c) 5 to 25 wt % solvent,   d) 0 to 5 wt % curing agent, and   e) 0 to 20 wt % second resin,   and wherein at room temperature the first resin is substantially soluble in the solvent.   
     
     
         5 . The method of  claim 3  wherein the semiconductor device is a discrete device. 
     
     
         6 . A semiconductor device formed by:
 (a) providing a semiconductor wafer having a front side that is active and a back side opposed to the front side that is inactive,   (b) providing a conductive adhesive that comprises filler having a maximum particle size of less than 10 μm,   (c) applying the conductive adhesive to the back side of the semiconductor wafer to form a conductive adhesive layer with an exposed side opposite the front side of the semiconductor wafer,   (d) B-staging the conductive adhesive layer to form a B-staged wafer,   (e) securing the exposed side of the conductive adhesive layer of the B-staged wafer to a substrate to form a semiconductor device, and   (f) curing the semiconductor device;   wherein after B-staging the conductive adhesive layer has a surface roughness of less than 12 microns and after cure the conductive adhesive layer has an elastic modulus of greater than 500 MPa at 250° C., a thermal conductivity of greater than 3.8 W/mK at room temperature, and a volume resistivity of less than 0.0003 ohms-cm at room temperature.   
     
     
         7 . The semiconductor device of  claim 6  wherein the conductive adhesive comprises:
 a) 66 to 80 wt % conductive filler that has an average particle size of less than 2 microns and a maximum particle size of less than 10 microns,   b) 5 to 25 wt % first resin that has a softening point between 80-260° C.,   c) 5 to 25 wt % solvent,   d) 0 to 5 wt % curing agent, and   e) 0 to 20 wt % second resin,   
       and wherein at room temperature the first resin is substantially soluble in the solvent.