Semiconductor device substrate and process for preparing the same
First Claim
1. A process for preparing a semiconductor device substrate which 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 buffered hydrofluoric acid and at least one of an alcohol and an hydrogen peroxide solution, thereby selectively removing the porous Si layer.
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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.
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Citations
23 Claims
- 1. A process for preparing a semiconductor device substrate which 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 buffered hydrofluoric acid and at least one of an alcohol and an hydrogen peroxide solution, thereby selectively removing the porous Si layer.
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4. A process for preparing a semiconductor device substrate which 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 monocrystalline Si layer on the porous Si surface layer, a step of bonding the monocrystalline Si layer to one surface layer of a second substrate composed of Si material through an insulating layer, a step of removing the first substrate to a depth just before the porous Si layer is exposed, or to a depth where the porous Si layer is partially exposed, a first etching step of selectively etching the first substrate by 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 buffered hydrofluoric acid and at least one of an alcohol and a hydrogen peroxide solution, thereby selectively removing the porous Si layer.
- 13. A process for preparing a semiconductor device substrate which 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 Si porous surface layer, a step of forming a monocrystalline Si layer on the porous Si surface layer, a step of bonding the surface of the monocrystalline Si layer to one surface of a second substrate composed of a light-transmissive material through an insulating layer, a first etching step of forming an etching resistant mask on the bonded second layer and then removing the first Si substrate by selective etching except for the porous Si layer, a second etching step of impregnating the porous Si layer exposed by the removal of the first Si 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 buffered hydrofluoric acid or a second liquid mixture of buffered hydrofluoric acid and at least one of an alcohol and a hydrogen peroxide solution, thereby selectively removing the porous Si layer, and a step of removing the etching-resistant mask and increasing a bonding strength obtained in the bonding step when it fails to reach a desired one.
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14. A process for preparing a semiconductor device substrate which 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 surface of the monocrystalline Si layer to one surface of a second substrate composed of a light-transmissive material through an insulating layer, a step of removing the first substrate to a depth just before the porous Si layer is exposed, or to a depth where the porous Si layer is partially exposed, a first etching step of removing the first substrate by selective etching except for the porous Si layer, 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 buffered hydrofluoric acid or a second liquid mixture of buffered hydrofluoric acid and at least one of an alcohol and a hydrogen peroxide solution, thereby selectively removing the porous Si layer, and a step of increasing a bonding strength obtained in the bonding step when it fails to reach a desired one.
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17. A process for preparing a semiconductor device substrate which 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 surface of the monocrystalline Si layer to one surface of a second substrate composed of a light-transmissive material, a first etching step of removing the first substrate by selective etching, 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 buffered hydrofluoric acid or a second liquid mixture of buffered hydrofluoric acid and at least one of an alcohol and a hydrogen peroxide solution, thereby selectively removing the porous Si layer, and a step of increasing a bonding strength obtained in the bonding step when it fails to reach a desired one.
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18. A process for preparing a semiconductor device substrate which 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 surface of the monocrystalline Si layer to one surface of a second substrate composed of a light-transmissive material, a step of removing the first substrate to a depth just before the porous Si layer is exposed or to a depth where the porous Si layer is partially exposed, a first etching step of removing the first substrate selective etching except for the porous Si layer, 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 buffered hydrofluoric acid or a second liquid mixture of buffered hydrofluoric acid and at least one of an alcohol and a hydrogen peroxide solution, thereby selectively removing the porous Si layer, and a step of increasing a bonding strength obtained in the bonding step when it fails to reach a desired one.
Specification