Semiconductor device substrate and process for preparing the same

TLDR: In this article, a process for preparing a semiconductor device substrate comprises a step of making at least one surface of a first substrate composed of Si material porous, oxidizing inside walls of pores in the resulting porous Si surface layer, forming a monocrystalline Si layer on the porous Si layer, and bonding the mon-coalescence Si layer to one substrate through an insulating layer therebetween.

Abstract: A process for preparing a semiconductor device substrate comprises a step of making at least one surface of a first substrate composed of Si material porous, a step of oxidizing inside walls of pores in the resulting porous Si surface layer, a step of forming a monocrystalline Si layer on the porous Si surface layer, a step of bonding the monocrystalline Si layer to one surface of a second substrate through an insulating layer therebetween, a first etching step of removing the first substrate by selective etching except for the porous Si layer, and a second etching step of impregnating the porous Si layer exposed by the removal of the first substrate with hydrofluoric acid or a first liquid mixture of hydrofluoric acid and at least one of an alcohol and a hydrogen peroxide solution, or by buffered hydrofluoric acid or a second liquid mixture of bufffered hydrofluoric acid and at least one of an alcohol and an hydrogen peroxide solution, thereby selectively removing the porous Si layer.