Mounting of semiconductor-on-diamond wafers for device processing

Abstract

The present invention discloses a semiconductor-on-diamond-on-carrier substrate wafer ( 55 ). The semiconductor-on-diamond-on-carrier wafer ( 55 ) comprises: a semiconductor-on-diamond wafer ( 40 ) having a diamond side and semiconductor side; a carrier substrate ( 50 ) disposed on the diamond side of the semiconductor-on-diamond wafer ( 40 ) and including at least one layer having a lower coefficient of thermal expansion (CTE) than diamond; and an adhesive layer ( 48 ) disposed between the diamond side of the semiconductor-on-diamond wafer ( 40 ) and the carrier substrate ( 50 ) to bond the carrier substrate ( 50 ) to the semiconductor-on-diamond wafer ( 40 ). The semiconductor-on-diamond-on-carrier substrate wafer ( 55 ) has the following characteristics: a total thickness variation of no more than 40 μm; a wafer bow of no more than 100 μm; and a wafer warp of no more than 40 μm.

1 . A method of mounting a semiconductor-on-diamond wafer on a carrier substrate, the method comprising:
 disposing a semiconductor-on-diamond wafer on an optical flat, the semiconductor-on-diamond wafer including a diamond layer and a semiconductor layer and arranged so that the semiconductor layer faces the optical flat;   disposing an adhesive layer on the diamond layer of the semiconductor-on-diamond wafer;   disposing a carrier substrate on the adhesive layer, the carrier substrate including a layer having a lower coefficient of thermal expansion (CTE) than diamond;   pressing the carrier substrate against the optical flat and bonding the carrier substrate to the semiconductor-on-diamond wafer to form a semiconductor-on-diamond-on carrier substrate wafer while the carrier substrate is pressed against the optical flat; and   separating the semiconductor-on-diamond-on-carrier substrate wafer from the optical flat.   
     
     
         2 . A method according to  claim 1 , wherein, after the step of separating the semiconductor-on-diamond-on-carrier substrate wafer from the optical flat, the semiconductor-on-diamond-on-carrier substrate wafer has the following characteristics:
 a total thickness variation of no more than 40 μm;   a wafer bow of no more than 100 μm; and   a wafer warp of no more than 40 μm.   
     
     
         3 . A method according to  claim 1 , wherein the step of bonding includes curing the adhesive layer at a temperature between 10° C. and 40° C. 
     
     
         4 . A method according to  claim 1 , wherein the adhesive layer includes a UV glue that is cured when exposed to UV light and the step of bonding includes exposing UV light to the adhesive layer. 
     
     
         5 . A method according to  claim 1 , wherein the adhesive includes a thermal release adhesive material, further comprising:
 heating the thermal release adhesive material to thereby release the carrier substrate from the semiconductor-on-diamond wafer.   
     
     
         6 . A method according to  claim 1 , wherein the adhesive includes a polymer adhesive material and the step of boding includes curing the adhesive by heating. 
     
     
         7 . A method according to  claim 1 , wherein the carrier substrate comprises an additional layer having a higher CTE than diamond. 
     
     
         8 . A method according to  claim 7 , wherein the additional layer having a higher coefficient of thermal expansion (CTE) than diamond is formed of silicon. 
     
     
         9 . A method according to  claim 7 , wherein an adhesive layer is provided between the layer having a lower CTE than diamond and the additional layer having a higher CTE than diamond. 
     
     
         10 . A method according to  claim 1 , further comprising:
 disposing a thermal release tape between the semiconductor layer of the semiconductor-on-diamond wafer and the optical flat.   
     
     
         11 . A method according to  claim 1 , further comprising:
 disposing a protective coating layer on the semiconductor layer of the semiconductor-on-diamond wafer.   
     
     
         12 . A method according to  claim 1 , further comprising:
 disposing a thermal release adhesive layer between the carrier substrate and the semiconductor-on-diamond wafer.   
     
     
         13 . A method of fabricating semiconductor device structures, comprising:
 fabricating one or more semiconductor device structures on the semiconductor layer of the semiconductor-on-diamond-on-carrier substrate wafer formed according the method of  claim 1  while maintaining the semiconductor-on-diamond-on-carrier substrate wafer at a device fabrication temperature at which bonding of the carrier substrate and semiconductor-on-diamond wafer is maintained; and   releasing the carrier substrate from the semiconductor-on-diamond wafer after fabrication of the one or more semiconductor device structures by heating the semiconductor-on-diamond-on-carrier substrate wafer to a temperature in excess of the device fabrication temperature such that bonding of the carrier substrate and semiconductor-on-diamond wafer is broken.   
     
     
         14 . A semiconductor-on-diamond-on-carrier substrate wafer, comprising:
 a semiconductor-on-diamond wafer having a diamond side and a semiconductor side;   a carrier substrate disposed on the diamond side of the semiconductor-on-diamond wafer and including at least one layer having a lower coefficient of thermal expansion (CTE) than diamond; and   an adhesive layer disposed between the diamond side of the semiconductor-on-diamond wafer and the carrier substrate to bond the carrier substrate to the semiconductor-on-diamond wafer,   wherein the semiconductor-on-diamond-on-carrier substrate wafer has the following characteristics:   a total thickness variation of no more than 40 μm;   a wafer bow of no more than 100 μm; and   a wafer warp of no more than 40 μm.   
     
     
         15 . A semiconductor-on-diamond-on-carrier substrate wafer according to  claim 14 , wherein the carrier substrate comprises a layer having a higher coefficient of thermal expansion (CTE) than diamond. 
     
     
         16 . A semiconductor-on-diamond-on-carrier substrate wafer according to  claim 14 , further comprising:
 a thermal release adhesive layer disposed between the carrier substrate and the semiconductor-on-diamond wafer.   
     
     
         17 . A semiconductor-on-diamond-on-carrier substrate wafer according to  claim 14 , wherein the adhesive layer includes a UV glue that is cured by UV light. 
     
     
         18 . A semiconductor-on-diamond-on-carrier substrate wafer according to  claim 14 , further comprising:
 a protective coating layer disposed on the semiconductor side of the semiconductor-on-diamond wafer.   
     
     
         19 . A semiconductor-on-diamond-on-carrier substrate wafer according to  claim 14 , wherein the semiconductor-on-diamond-on-carrier substrate wafer meets the characteristics for total thickness variation, wafer bow, and wafer warp over a diameter of at least 50 mm, 75 mm, 100 mm, or 150 mm. 
     
     
         20 . A semiconductor-on-diamond-on-carrier substrate wafer according to  claim 14 , wherein the semiconductor-on-diamond wafer incudes gallium nitride.