Semiconductor substrate and method of manufacturing the same

• US 6,534,380 B1
• Filed: 07/17/1998
• Issued: 03/18/2003
• Est. Priority Date: 07/18/1997
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ohshima, Hisayoshi, Ooka, Tadao, Izumi, Toshifumi, Matsui, Masaki, Yamanaka, Akitoshi, Yamauchi, Shoichi, Onoda, Kunihiro
• Primary Examiner(s): Pham, Long
• Assistant Examiner(s): TOLEDO, FERNANDO L
• Application Number:
  US09/116,956
• Time in Patent Office: 1,705 Days
• Field of Search: 438/455, 438/458, 438/149, 438/406, 438/409, 438/967, 438/150, 438/407, 438/960, 438/459, 438/691, 438/692, 438/959, 438/977, 438/770
• US Class Current: 438/455
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: Y10S 438/96 Porous semiconductor

Abstract

Before a semiconductor substrate and a base substrate is directly bonded to one another, in a protective film removing step, a contamination protective film formed on the semiconductor substrate to protect it from contamination during an ion implanting step is removed. Consequently, even when flatness of the contamination protective film is degraded during the ion implanting step or even when contaminants remain in a segregated state in the vicinity of the surface of the contamination protective film, the state of the bonding between the semiconductor substrate and the base substrate after the bonding step can be made uniform over the entire area of the bonding. As a result, a high-quality semiconductor substrate can be manufactured at low cost.

Claims

1. A method of manufac turing a semicon ductor substrate composed of a base substrate and a semiconductor layer disposed on the base substrate in an insulated state from the base substrate, the method comprising:

forming a contamination protective layer on a semiconductor substrate material;

formning an ion-implanted layer in the semiconductor substrate material by implanting ions through the contamination protective layer;

removing at least a part of the contamination protective layer from the semiconductor substrate material to secure a flat contamination-free surface;

providing hydrophilicity to the flat contamination-free surface and to a base substrate treatment surface of the base substrate;

directly bonding the semiconductor substrate material and the base substrate at the substrate material treatment surface and at the base substrate treatment surface;

detaching the semiconductor substrate material from the base substrate at the ion-implanted layer by a heat treatment,

wherein in the removing at least the part of the contamination protective layer, only an upper part of the contamination protective layer is removed.

2. The method of claim 1, wherein the upper part of the contamination protective layer is removed by a method selected from a chemical etching method and a combined method of chemical etching and mechanical polishing.

3. The method of claim 1, wherein by the removing at least the part of the contamination protective layer, the surface of the contamination protective layer is flattened and contaminants embedded in the contamination protective layer by the forming the ion-implanted layer are removed.

4. A method of manufacturing a plurality of semiconductor substrates, each of which has a base substrate and a single crystal semiconductor layer disposed on the base substrate through an insulating layer, the method comprising:

forming a protective layer on a surface of a single crystal semiconductor substrate material;

forming a defective layer in the semiconductor substrate material through the protective layer covering the surface by ion implantation to define a single crystal thin film in a surface region of the semiconductor substrate material, the single crystal thin film to be the single crystal semiconductor layer of the semiconductor substrate;

preparing the base substrate having the insulating layer thereon, the base substrate having a quality inferior to that of the semiconductor substrate material;

bonding the base substrate to the single crystal thin film of the semiconductor substrate material with the insulating layer interposed therebetween;

detaching the semiconductor substrate material from the base substrate at the defective layer so that the semiconductor substrate composed of the base substrate and the single crystal semiconductor layer disposed on the base substrate through the insulating layer is provided; and

reusing the semiconductor substrate material for forming another semiconductor substrate,

wherein the protective layer is removed before the base substrate is bonded to the semiconductor substrate material.

5. The method of claim 4, wherein the reusing the semiconductor substrate material includes:

forming a covering layer made of one of an oxide material and a nitride material on a detachment surface of the semiconductor substrate material; and

removing the covering layer from the semiconductor substrate material by etching.

6. The method of claim 4, wherein, the reusing the semiconductor substrate material includes:

bonding another substrate material to the semiconductor substrate material to form a spliced substrate material when a thickness of the semiconductor substrate material is equal to or smaller than a predetermined thickness; and

using the spliced substrate material to form another semiconductor substrate.

19. The method of claim 4, wherein the protective layer is made of an oxide material.

7. A method of manufacturing a plurality of semiconductor substrates, each of which has a base substrate and a single crystal semiconductor layer disposed on the base substrate through an insulating layer, the method comprising:

forming a protective layer on a surface of a single crystal semiconductor substrate material;

forming a defective layer in the semiconductor substrate material through the protective layer covering the surface by ion implantation to define a single crystal thin film in a surface region of the semiconductor substrate material, the single crystal thin film to be the single crystal semiconductor layer of the semiconductor substrate;

preparing the base substrate having the insulating layer thereon, the base substrate having a quality inferior to that of the semiconductor substrate material;

bonding the base substrate to the single crystal thin film of the semiconductor substrate material with the insulating layer interposed therebetween;

detaching the semiconductor substrate material from the base substrate at the defective layer so that the semiconductor substrate composed of the base substrate and the single crystal semiconductor layer disposed on the base substrate through the insulating layer is provided; and

reusing the semiconductor substrate material for forming another semiconductor substrate,

wherein the protective layer is removed before the base substrate is bonded to the semiconductor substrate material

further comprising steps of forming a trench in the semiconductor substrate material and filling the trench with a material before forming the defective layer, the trench having a depth deeper than that where the defective layer is to be formed.

8. A method of manufacturing a plurality of semiconductor substrates, each of which has a base substrate and a semiconductor layer disposed on the base substrate through an insulating layer, the method comprising:

selecting a donor substrate, the donor substrate comprising a semiconductor material and having a front side and a back side;

forming a protective layer on the front side and the back side of the donor substrate;

forming a first ion-implanted layer in the donor substrate at a first depth by ion-implantation through the protective layer on the front side of the donor substrate, the first ion-implanted layer defining a first semiconductor layer between the front surface and the first ion-implanted layer;

forming a second ion-implanted layer in the semiconductor substrate material at a second depth by ion-implantation performed through the protective layer on the back side of the donor substrate, the second ion-implanted layer defining a second semiconductor layer between the back side and the second ion-implanted layer;

removing the protective layer from the front side and the back side of the donor substrate;

bonding first and second base substrates to the first and second semiconductor layers of the semiconductor substrate material; and

thermally treating the donor substrate to induce separation of the first and second semiconductor layers from a central portion of the donor substrate; and

separating a first semiconductor substrate from the donor substrate, the first semiconductor substrate comprising the first base substrate and the first semiconductor layer, and separating a second semiconductor substrate from the donor substrate, the second semiconductor substrate comprising the second base substrate and the second semiconductor layer.

9. The method of claim 8, further comprising heating at least one of the first and second base substrates respectively holding the first and second semiconductor layers which are detached from the semiconductor substrate material, at a temperature higher than that of the heat treatment in the detaching the first and second base substrates.

11. The method of claim 8, wherein:

in the forming the first ion-implanted layer, ions are implanted into the semiconductor substrate material from the first surface; and

in the forming the second ion-implanted layer, ions are implanted into the semiconductor substrate material from the second surface.

12. The method of claim 8, wherein the first and second ion-implnated layers are respectively formed at the first and second depths different from one another in the semiconductor substrate material by implanting ions from the same surface side.

13. The method of claim 12, wherein an ion implantation enregey for forming the first ion-implanted layer is different from that for forming the second ion-implanted layer.

14. The method of claim 12, wherein at least one of a combination of constituent elements and a molecular number of ions for forming the first ion-implanted layer is different from that for forming the second ion-implanted layer.

15. The method of claim 8, wherein:

the first and second base substrates respectively have first and second insulating layers thereon; and

the first and second base substrates are respectively bonded to the first and second semiconductor layers via the first and second insulating layers.

16. The method of claim 8, wherein the first protective layer and the second protective layer are made of an oxide material.

17. The method of claim 8, further comprising, before the first ion-implanted layer is formed, forming a contamination protective film on an entire surface of the semiconductor substrate material, the contamination protective film being composed of the first protective film covering the first surface, the second protective film covering the second surface, and a peripheral protective film covering a peripheral side surface of the semirconductor substrate material.

18. The method of claim 17, wherein the contamination protective film has a thickness in a range of about 50 nm to 100 nm.

10. The method of claim 10, wherein the heating at least one of the first and second base substrates increases a bonding strength between the one of the first and second base substrates and a corresponding one of the first and second semiconductor layers.

20. A method of manufacturing a semiconductor substrate composed of a base substrate and a semiconductor layer disposed on the base substrate in an insulated state from the base substrate, the method comprising:

forming a contamination protective layer on a semiconductor substrate material;

forming an ion-implanted layer in the semiconductor substrate material by implanting ions through the contamination protective layer;

removing at least a part of the contamination protective layer from the semiconductor substrate material by etching to thereby expose an etched surface of the contamination protective layer;

flattening the etched surface to expose a treatment surface of the contamination protective layer;

directly bonding the semiconductor substrate material and the base substrate through the substrate material treatment surface; and

detaching the semiconductor substrate material from the base substrate at the ion-implanted layer by a heat treatment.

21. The method of claim 20, wherein the etched surface is flattened by a method other than the etching.

22. The method of claim 21, wherein the etched surface is flattened by a chemical-mechanical polishing treatment.

23. The method of claim 20, wherein the contamination protective film is removed completely by flattening the etched surface.