Smoothing method for cleaved films made using a release layer

A semiconductor substrate producing method comprising: forming a first porous silicon layer on at least one surface of a silicon substrate; forming a non-porous layer over said first porous layer; forming a second porous layer having a larger porosity than the first porous silicon layer at a constant depth from a surface of said first porous silicon layer, said second porous layer forming step comprising implanting ions into said first porous silicon layer with a given projection range; bonding said non-porous layer and a support substrate together, the support substrate being different than the silicon substrate; separating said silicon substrate into two portions at said second porous layer; removing at least said first porous layer provided over said support substrate to expose said non-porous layer; and smoothing said exposed non-porous layer by subjecting a surface of said non-porous layer using an etchant species and thermal treatment.

A semiconductor substrate producing method comprising: forming on a surface of a silicon substrate a first porous silicon layer, a second porous silicon layer and a third porous silicon layer, wherein the second porous silicon layer is located under the first porous silicon layer and has a porosity higher than the first porous silicon layer, and the third porous silicon layer is located under the second porous silicon layer and has a porosity lower than the second porous silicon layer; forming a non-porous monocrystalline semiconductor layer on the first porous silicon layer; bonding the non-porous monocrystalline semiconductor layer located on the silicon substrate to another substrate; and separating the silicon substrate and the other substrate at the second porous silicon layer so that the non-porous monocrystalline semiconductor layer remains on the other substrate; and removing the first porous silicon layer from the non-porous monocrystalline semiconductor layer; and subjecting a surface of the non-porous monocrystalline semiconductor layer with thermal energy and an etchant to remove a surface roughness from a first value to a second predetermined value.

A semiconductor substrate producing method comprising: forming on a surface of a silicon substrate a first porous silicon layer; implanting ions into the first porous silicon layer to form a second porous silicon layer having a porosity higher than the first porous silicon layer at a constant depth from a surface of the first porous silicon layer; forming a non-porous monocrystalline semiconductor layer on the first porous silicon layer; bonding the non-porous monocrystalline semiconductor layer located on the silicon substrate to another substrate; and separating the silicon substrate and the other substrate at the second porous silicon layer so that the non-porous monocrystalline semiconductor layer remains on the other substrate; and applying a combination of thermal treatment and an etchant to a surface of the non-porous monocrystalline semiconductor layer to reduce a surface roughness to a predetermined value.

A semiconductor substrate producing method comprising: forming a first porous silicon layer on at least one surface of a silicon substrate; forming a non-porous layer on said first porous layer; forming a second porous layer having a larger porosity than the first porous silicon layer within said first porous silicon layer by implanting ions into said first porous silicon layer; bonding said non-porous layer and a support substrate together, the support substrate being different than the silicon substrate; separating said silicon substrate into two portions at said second porous layer; removing said first and second porous layers provided over said support substrate to expose said non-porous layer; and smoothing said exposed non-porous layer by heating a surface of said non-porous layer within an atmosphere containing hydrogen and an etchant.

A method of producing a semiconductor substrate, comprising: providing a silicon substrate having a porous silicon layer on a surface of said silicon substrate; providing a bonding substrate; bonding said silicon substrate and said bonding substrate together; separating said silicon substrate into two portions at said porous silicon layer, said bonding substrate separated from said silicon substrate having a first porous material on a surface of said bonding substrate, said silicon substrate separated from said bonding substrate having a second porous material on said surface of said silicon substrate; removing said porous material from at least one of said substrates to expose a non-porous layer of said at least one of said substrates; smoothing said exposed non-porous layer by heating a surface of said non-porous layer within an atmosphere containing hydrogen atoms and an etchant.