Sos substrate having low defect density in the vicinity of interface

Abstract

A bonded SOS substrate having a semiconductor film on or above a surface of a sapphire substrate is obtained by a method with the steps of implanting ions from a surface of a semiconductor substrate to form an ion-implanted layer; activating at least a surface from which the ions have been implanted; bonding the surface of the semiconductor substrate and the surface of the sapphire substrate at a temperature of 50° C. to 350° C.; heating the bonded substrates at a maximum temperature from 200° C. to 350° C. to form a bonded body; and irradiating visible light from a sapphire substrate side or a semiconductor substrate side to the ion-implanted layer of the semiconductor substrate for embrittling an interface of the ion-implanted layer, while keeping the bonded body at a temperature higher than the temperature at which the surfaces of the semiconductor substrate and the sapphire substrate were bonded.

1 . A silicon on sapphire (SOS) substrate comprising a single crystal silicon film having a thickness of 100 nm or less on or above a sapphire substrate, wherein a defect density of a surface of the single crystal silicon film measured by a Secco defect detection method and a selection etching defect detection method is 10 4  pieces/cm 2  or less. 
     
     
         2 . The SOS substrate according to  claim 1 , comprising a silicon oxide film between the single crystal silicon film and the sapphire substrate, wherein the defect density of the surface of the single crystal silicon film is 10 4  pieces/cm 2  or less. 
     
     
         3 . The SOS substrate according to  claim 1 , comprising a silicon oxide film between the single crystal silicon film and the sapphire substrate. 
     
     
         4 . The SOS substrate according to  claim 1 , wherein a thickness variation of the single crystal silicon film is 20 nm or less. 
     
     
         5 . The SOS substrate according to  claim 1 , wherein the SOS substrate is obtained by a bonding method. 
     
     
         6 . A bonded SOS substrate comprising a semiconductor film on the surface of a sapphire substrate obtained by a method comprising the steps of:
 providing the sapphire substrate and a semiconductor substrate;   implanting ions from a surface of the semiconductor substrate to form an ion-implanted layer;   activating at least a surface selected from the surface of the sapphire substrate and the surface of the semiconductor substrate from which the ions have been implanted;   bonding the surface of the semiconductor substrate and the surface of the sapphire substrate at a temperature of from 50° C. to 350° C.;   heating the bonded substrates at a maximum temperature of from 200° C. to 350° C. to form a bonded body; and   irradiating visible light from a sapphire substrate side or a semiconductor substrate side to the ion-implanted layer of the semiconductor substrate for making an interface of the ion-implanted layer brittle, while keeping a temperature of the bonded body higher than the temperature at which the surfaces of the semiconductor substrate and the sapphire substrate were bonded, so as to transfer the semiconductor film to the sapphire substrate.   
     
     
         7 . The bonded SOS substrate according to  claim 6 , wherein the step of activating comprises one or more selected from the group consisting of ozone water treatment, UV ozone treatment, ion beam treatment and plasma treatment. 
     
     
         8 . The bonded SOS substrate according to  claim 6 , wherein the temperature of the bonded body during irradiation of the visible light is from 30° C. to 100° C. higher than the temperature at which the bonded body was formed. 
     
     
         9 . The bonded SOS substrate according to  claim 6 , comprising a step of applying a mechanical impact to the interface of the ion-implanted layer to split the bonded body along the interface after the step of irradiating visible light. 
     
     
         10 . The bonded SOS substrate according to  claim 6 , comprising a step of applying a mechanical impact to a side near the interface of the bonded body before the step of irradiating visible light. 
     
     
         11 . The bonded SOS substrate according to  claim 6 , wherein the semiconductor substrate is a single crystal silicon substrate or a silicon substrate on which an oxide film has been grown. 
     
     
         12 . The bonded SOS substrate according to  claim 6 , wherein the visible light is a laser beam. 
     
     
         13 . The bonded SOS substrate according to  claim 6 , wherein the visible light is of a RTA (Rapid Thermal Anneal) including spike anneal. 
     
     
         14 . The bonded SOS substrate according to  claim 6 , wherein the visible light is flash lamp light. 
     
     
         15 . The bonded SOS substrate according to  claim 6 , wherein the implanted ions are hydrogen atom ions (H + ) and a dose amount thereof is from 1×10 16  atoms/cm 2  to 1×10 17  atoms/cm 2 . 
     
     
         16 . The bonded SOS substrate according to  claim 6 , wherein the implanted ions are hydrogen atom molecule ions (H 2   + ) and a dose amount thereof is from 5×10 15  atoms/cm 2  to 5×10 16  atoms/cm 2 . 
     
     
         17 . The bonded SOS substrate according to  claim 6 , further comprising a step of chemically etching and/or polishing a surface of the transferred semiconductor film. 
     
     
         18 . (canceled)