Method for locating devices

Abstract

The disclosure relates to a process for locating devices, the process comprising the following steps: a) providing a carrier substrate comprising: a device layer; and alignment marks; b) providing a donor substrate; c) forming a weak zone in the donor substrate, the weak zone delimiting a useful layer; d) assembling the donor substrate and the carrier substrate; and e) fracturing the donor substrate in the weak zone so as to transfer the useful layer to the device layer; wherein the alignment marks are placed in cavities formed in the device layer, the cavities having an aperture flush with the free surface of the device layer.

1 . A process for locating devices after transfer of a useful layer, the process comprising the following steps:
 a) providing a carrier substrate comprising:
 a device layer comprising a free surface; and 
 alignment marks; 
   b) providing a donor substrate;   c) forming a weak zone in the donor substrate, the weak zone delimiting a useful layer;   d) assembling the donor substrate and the carrier substrate; and   e) fracturing the donor substrate in the weak zone so as to transfer the useful layer to the device layer;   wherein the alignment marks are placed in cavities formed in the device layer, the cavities having an aperture flush with the free surface of the device layer.   
     
     
         2 . The process according to  claim 1 , in which the assembly step d) comprises a direct bonding step executed in an environment at a pressure below 20 mbars. 
     
     
         3 . The process according to  claim 2 , wherein the cavities extend into the carrier substrate. 
     
     
         4 . The process according to  claim 3 , wherein the alignment marks are placed at the bottom of the cavities. 
     
     
         5 . The process according to  claim 4 , wherein the device layer comprises devices distributed over an entire extent of the device layer. 
     
     
         6 . The process according to  claim 4 , wherein an opaque layer is present on the useful layer before the assembly step d). 
     
     
         7 . The process according to  claim 6 , wherein the opaque layer comprises at least one material selected from the following group: tungsten, titanium, tungsten silicide, titanium silicide, nickel silicide, nickel silicide and platinum. 
     
     
         8 . The process according to  claim 4 , wherein the step c) of forming the weak zone is executed by implanting at least one of the species selected from the following group: hydrogen and helium. 
     
     
         9 . The process according to  claim 4 , wherein the fracturing step e) comprises a heat treatment executed at a temperature between 200° C. and 500° C. 
     
     
         10 . The process according to  claim 1 , wherein the thickness of the useful layer is smaller than 8000 Å. 
     
     
         11 . The process according to  claim 1 , wherein the useful layer comprises sublayers of different doping. 
     
     
         12 . The process according to  claim 10 , wherein the thickness of the userful layer is smaller than 5000 Å. 
     
     
         13 . The process according to  claim 1 , wherein the cavities extend into the carrier substrate. 
     
     
         14 . The process according to  claim 1 , wherein the alignment marks are placed at the bottom of the cavities. 
     
     
         15 . The process according to  claim 1 , wherein the device layer comprises devices distributed over an entire extent of the device layer. 
     
     
         16 . The process according to  claim 1 , wherein an opaque layer is present on the useful layer before the assembly step d). 
     
     
         17 . The process according to  claim 1 , wherein the step c) of forming the weak zone is executed by implanting at least one of the species selected from the following group: hydrogen and helium. 
     
     
         18 . The process according to  claim 1 , wherein the fracturing step e) comprises a heat treatment executed at a temperature between 200° C. and 500° C.