Method for manufacturing a semiconductor film

Abstract

A method for manufacturing a semiconductor film includes a step of preparing a first member including a semiconductor substrate, a semiconductor layer, and a separation layer provided between the semiconductor substrate and the semiconductor layer, a step of bonding or attracting a second member which is hardly heated by induction heating, onto the semiconductor layer of the first member, and a step of separating the semiconductor layer from the semiconductor substrate at the separation layer by heating the semiconductor substrate by induction heating.

What is claimed is:  
     
         1 . A method for manufacturing a semiconductor film, comprising the steps of: 
 preparing a first member including a semiconductor substrate, a semiconductor layer, and a separation layer provided between the semiconductor substrate and the semiconductor layer;    bonding or attracting a second member which is hardly heated by induction heating, onto the semiconductor layer of the first member; and    separating the semiconductor layer from the semiconductor substrate at the separation layer by heating the semiconductor substrate by induction heating.    
     
     
         2 . A method according to  claim 1 , wherein said step for preparing the first member comprises a step of forming a porous silicon layer, serving as a separation layer, by anodizing a surface of a nonporous silicon substrate, and a step of forming a nonporous silicon layer on the porous silicon layer according to epitaxial growth.  
     
     
         3 . A method according to  claim 1 , wherein said step for preparing the first member comprises a step of forming an ion-implanted layer, serving as a separation layer, except for a silicon layer where ions are not implanted on a surface thereof, by implanting at least one type of ions selected from hydrogen, nitrogen and helium to a predetermined depth from a surface of a silicon substrate.  
     
     
         4 . A method according to  claim 3 , wherein said step for preparing the first member further comprises a step of forming a protective film on the surface of the silicon substrate before implanting the ions.  
     
     
         5 . A method according to  claim 1 , wherein said step of heating the semiconductor substrate by induction heating comprises a step of mounting the bonded or attracted first and second members on an induction-heating mount around which a coil is wound, and causing a current to flow in the semiconductor substrate by supplying the coil with a high-frequency current.  
     
     
         6 . A method according to  claim 1 , further comprising a step of forming slits in the separation layer before heating the semiconductor substrate by induction heating.  
     
     
         7 . A method according to  claim 1 , wherein, in said step of heating the semiconductor substrate by induction heating, a tensile force, a compressive force or a shearing force is simultaneously applied to the separation layer.  
     
     
         8 . A method according to  claim 1 , wherein, in said step of heating the semiconductor substrate by induction heating, a pressure or a hydrostatic pressure by a fluid is simultaneously applied to the separation layer.  
     
     
         9 . A method according to  claim 1 , wherein, in said step of heating the semiconductor substrate by induction heating, the second member is simultaneously cooled.  
     
     
         10 . A method according to  claim 1 , further comprising a step of removing a residue of the separation layer remaining on the semiconductor layer according to etching, after separating the semiconductor layer.  
     
     
         11 . A method according to  claim 1 , further comprising a step of reutilizing a remaining semiconductor substrate for preparing another first member, after separating the semiconductor layer.  
     
     
         12 . A method according to  claim 11 , further comprising a step of removing a residue of the separation layer remaining on the semiconductor substrate according to etching, before reutilizing the semiconductor substrate.  
     
     
         13 . A method for manufacturing a semiconductor film comprising the steps of: 
 preparing a first member including a semiconductor substrate, a semiconductor layer, and a separation layer provided between the semiconductor substrate and the semiconductor layer;    bonding or attracting a second member whose resistivity is higher than a resistivity of the semiconductor substrate, onto the semiconductor layer of the first member; and    separating the semiconductor layer from the semiconductor substrate at the separation layer by heating the semiconductor substrate by induction heating.    
     
     
         14 . A method according to  claim 13 , wherein said step for preparing the first member comprises a step of forming a porous silicon layer, serving as a separation layer, by anodizing a surface of a nonporous silicon substrate, and a step of forming a nonporous silicon layer on the porous silicon layer according to epitaxial growth.  
     
     
         15 . A method according to  claim 13 , wherein said step for preparing the first member comprises a step of forming an ion-implanted layer, serving as a separation layer, except for a silicon layer where ions are not implanted on a surface thereof, by implanting at least one type of ions selected from hydrogen, nitrogen and helium to a predetermined depth from a surface of a silicon substrate.  
     
     
         16 . A method according to  claim 15 , wherein said step for preparing the first member further comprises a step of forming a protective film on the surface of the silicon substrate before implanting the ions.  
     
     
         17 . A method according to  claim 13 , wherein said step of heating the semiconductor substrate by induction heating comprises a step of mounting the bonded or attracted first and second members on an induction-heating mount around which a coil is wound, and causing a current to flow in the semiconductor substrate by supplying the coil with a high-frequency current.  
     
     
         18 . A method according to  claim 13 , further comprising a step of forming slits in the separation layer before heating the semiconductor substrate by induction heating.  
     
     
         19 . A method according to  claim 13 , wherein, in said step of heating the semiconductor substrate by induction heating, a tensile force, a compressive force or a shearing force is simultaneously applied to the separation layer.  
     
     
         20 . A method according to  claim 13 , wherein, in said step of heating the semiconductor substrate by induction heating, a pressure or a hydrostatic pressure by a fluid is simultaneously applied to the separation layer.  
     
     
         21 . A method according to  claim 13 , wherein, in said step of heating the semiconductor substrate by induction heating, the second member is simultaneously cooled.  
     
     
         22 . A method according to  claim 13 , further comprising a step of removing a residue of the separation layer remaining on the semiconductor layer according to etching, after separating the semiconductor layer.  
     
     
         23 . A method according to  claim 13 , further comprising a step of reutilizing a remaining semiconductor substrate for preparing another first member, after separating the semiconductor layer.  
     
     
         24 . A method according to  claim 23 , further comprising a step of removing a residue of the separation layer remaining on the semiconductor substrate according to etching, before reutilizing the semiconductor substrate.  
     
     
         25 . A method for manufacturing a semiconductor film comprising the steps of: 
 preparing a first member including a semiconductor substrate, a semiconductor layer whose resistivity is higher than a resistivity of the semiconductor substrate, and a separation layer provided between the semiconductor substrate and the semiconductor layer; and    separating the semiconductor layer from the semiconductor substrate at the separation layer by heating the first member by induction heating.    
     
     
         26 . A method according to  claim 25 , further comprising a step of bonding or attracting a second member which is hardly heated by induction heating, onto the semiconductor layer of the first member, before heating the first member by induction heating.  
     
     
         27 . A method according to  claim 25 , further comprising a step of bonding or attracting a second member whose resistivity is higher than a resistivity of the first member, onto the semiconductor layer of the first member, before heating the first member by induction heating.  
     
     
         28 . A method according to  claim 25 , wherein the resistivity of the semiconductor layer is at least 10 times the resistivity of the semiconductor substrate.  
     
     
         29 . A method according to  claim 25 , wherein the resistivity of the semiconductor layer is at least 1 Ω.cm, and the resistivity of the semiconductor substrate is equal to or less than 0.1 Ω.cm.  
     
     
         30 . A method according to  claim 25 , wherein said step for preparing the first member comprises a step of forming a porous silicon layer, serving as a separation layer, by anodizing a surface of a p + -type nonporous silicon substrate, and a step of forming a p − -type nonporous silicon layer on the porous silicon layer according to epitaxial growth.  
     
     
         31 . A method according to  claim 25 , wherein said step for preparing the first member comprises a step of forming a p − -type silicon layer on a p + -type silicon substrate according to epitaxial growth, and forming an ion-implanted layer, serving as a separation layer, except for a p − -type silicon layer where ions are not implanted on a surface thereof, by implanting at least one type of ions selected from hydrogen, nitrogen and helium to a predetermined depth from a surface of the p − -type silicon layer.  
     
     
         32 . A method according to  claim 31 , wherein said step of preparing the first member further comprises a step of forming a protective film on the surface of the p − -type silicon layer before implanting the ions.  
     
     
         33 . A method according to  claim 25 , wherein said step of heating the semiconductor substrate by induction heating comprises a step of mounting the first member on an induction-heating mount around which a coil is wound, and causing a current to flow in the semiconductor substrate by supplying the coil with a high-frequency current.  
     
     
         34 . A method according to  claim 25 , further comprising a step of forming slits in the separation layer before heating the first member by induction heating.  
     
     
         35 . A method according to  claim 25 , wherein, in said step of heating the first member by induction heating, a tensile force, a compressive force or a shearing force is simultaneously applied to the separation layer.  
     
     
         36 . A method according to  claim 25 , wherein, in said step of heating the first member by induction heating, a pressure or a hydrostatic pressure by a fluid is simultaneously applied to the separation layer.  
     
     
         37 . A method according to  claim 25 , further comprising a step of removing a residue of the separation layer remaining on the semiconductor layer according to etching, after separating the semiconductor layer.  
     
     
         38 . A method according to  claim 25 , further comprising a step of reutilizing a remaining semiconductor substrate for preparing another first member, after separating the semiconductor layer.  
     
     
         39 . A method according to  claim 38 , further comprising a step of removing a residue of the separation layer remaining on the semiconductor substrate according to etching, before reutilizing the semiconductor substrate.  
     
     
         40 . A method for manufacturing a solar cell comprising the steps of: 
 forming a porous silicon layer by anodizing a surface of a p + -type nonporous silicon substrate;    sequentially forming a p − -type nonporous silicon layer and an n + -type nonporous silicon layer on the porous silicon layer according to epitaxial growth;    attracting an attraction mount which is hardly heated by induction heating, on the n + -type nonporous silicon layer;    separating the p − -type and n + -type nonporous silicon layers from the p + -type nonporous silicon substrate at the porous silicon layer by heating the p + -type nonporous silicon substrate by induction heating; and    forming electrodes on the separated p − -type and n + -type nonporous silicon layers.    
     
     
         41 . A method according to  claim 40 , wherein said step of heating the p + -type nonporous silicon substrate by induction heating comprises a step of mounting the p + -type nonporous silicon substrate attracted on the attraction mount on an induction-heating mount around which a coil is wound, and causing a current to flow in the p + -type nonporous silicon substrate by supplying the coil with a high-frequency current.  
     
     
         42 . A method according to  claim 41 , wherein, in said step of heating the p + -type nonporous silicon substrate by induction heating, the attraction mount is simultaneously cooled.  
     
     
         43 . A method according to  claim 40 , further comprising a step of removing a residue of the porous silicon layer remaining on the p − nonporous silicon layer, before forming electrodes after separating the p − -type and n + -type nonporous silicon layers from the p + -type nonporous silicon substrate.  
     
     
         44 . A method according to  claim 40 , wherein said step of forming the electrodes comprises a step of performing heat welding of a surface of the p − -type nonporous silicon layer onto an aluminum plate and simultaneously forming a p + -type nonporous silicon layer by diffusing aluminum into the p − -type nonporous silicon layer, and a step of forming collecting electrodes on the surface of the n + -type nonporous silicon layer.  
     
     
         45 . A method according to  claim 44 , further comprising a step of forming an antireflection layer on the n + -type nonporous silicon layer on which the collecting electrodes are formed.  
     
     
         46 . A method according to  claim 40 , wherein the p − -type and n + -type nonporous silicon layers are formed according to liquid deposition.  
     
     
         47 . A method according to  claim 40 , further comprising a step of reutilizing a remaining p + -type nonporous silicon substrate for manufacturing another solar cell, after separating the p − -type and n + -type nonporous silicon layers.  
     
     
         48 . A method according to  claim 47 , further comprising a step of removing a residue of the porous silicon layer remaining on the p + -type nonporous silicon substrate, before reutilizing the p + -type nonporous silicon substrate.  
     
     
         49 . A method for manufacturing an SOI (silicon-on-insulator) substrate comprising the steps of: 
 forming a porous silicon layer by anodizing a surface of a p + -type nonporous silicon substrate;    forming a p − -type nonporous silicon layer on the porous silicon layer according to epitaxial growth;    forming a silicon-oxide layer on the surface of the p − -type nonporous silicon layer;    forming a multilayer structure by bonding another nonporous silicon substrate on a surface of the silicon-oxide layer; and    separating the p − -type nonporous silicon layer from the p + -type nonporous silicon substrate at the porous silicon layer by heating the multilayer structure by induction heating.    
     
     
         50 . A method according to  claim 49 , further comprising a step of attracting an attraction mount which is hardly heated by induction heating onto the multilayer structure, before heating the multilayer structure by induction heating.  
     
     
         51 . A method according to  claim 50 , wherein, in said step of heating the multilayer structure by induction heating, the attraction mount is simultaneously cooled.  
     
     
         52 . A method according to  claim 49 , wherein said step of heating the multilayer structure by induction heating comprises a step of mounting the multilayer structure on an induction-heating mount around which a coil is wound, and causing a current to flow in the p + -type nonporous silicon substrate by supplying the coil with a high-frequency current.  
     
     
         53 . A method according to  claim 49 , further comprising a step of removing a residue of the porous silicon layer remaining on the p − -type nonporous silicon layer by etching, after separating the p + -type nonporous silicon layer from the p + -type nonporous silicon substrate.  
     
     
         54 . A method according to  claim 53 , further comprising a step of smoothing the surface of the p − -type nonporous silicon layer by performing annealing in a reductive-gas atmosphere after removing the residue of the porous silicon layer.  
     
     
         55 . A method according to  claim 49 , further comprising a step of performing thermal oxidation of inner walls of the porous silicon layer before forming the p − -type nonporous silicon layer on the porous silicon layer according to epitaxial growth, and a step of smoothing the surface of the porous silicon layer by performing heat treatment in a hydrogen atmosphere.  
     
     
         56 . A method according to  claim 49 , wherein the p − -type nonporous silicon layer is formed according to chemical vapor deposition (CVD).  
     
     
         57 . A method according to  claim 49 , further comprising a step of reutilizing a remaining p + -type nonporous silicon substrate for manufacturing another SOI substrate, after separating the p-type nonporous silicon layer.  
     
     
         58 . A method according to  claim 57 , further comprising a step of removing a residue of the porous silicon layer remaining on the p + -type nonporous silicon substrate, before reutilizing the p + -type nonporous silicon substrate.