Ultra-thin semiconductor membranes

• US 4,946,735 A
• Filed: 12/14/1988
• Issued: 08/07/1990
• Est. Priority Date: 02/10/1986
• Status: Expired due to Fees

• Current Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Original Assignee: Cornell Research Foundation Incorporated (Cornell University)
• Inventors: Lee, Kevin C., Silcox, John, Lee, Charles A.
• Primary Examiner(s): Cannon, James C.
• Application Number:
  US07/284,821
• Time in Patent Office: 601 Days
• Field of Search: 148/33, 148/900, 148/DIG. 3, 148/DIG. 5, 148/DIG. 42, 148/DIG. 56, 148/DIG. 58, 148/DIG. 64, 148/DIG. 65, 148/DIG. 83 , 148/DIG. 119, 148/DIG. 135, 156/628, 156/662, 427/82, 427/85, 428/220, 428/333, 428/337, 428/409, 428/410, 428/446, 437/225, 437/247, 437/966, 437/974
• US Class Current: 428/220
• CPC Class Codes: H01L 21/3063 Electrolytic etching
• CPC Class Codes: H01L 21/30635 of AIIIBV compounds
• CPC Class Codes: H01L 21/324 Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering H01L21/20 - H01L21/288 and H01L21/302 - H01L21/322 take precedence
• CPC Class Codes: H01L 21/3245 of AIIIBV compounds
• CPC Class Codes: H01L 21/465 Chemical or electrical treatment, e.g. electrolytic etching to form insulating layers H01L21/469
• CPC Class Codes: H01L 21/477 Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering H01L21/38 - H01L21/449 and H01L21/461 - H01L21/475 take precedence
• CPC Class Codes: Y10S 148/003 Anneal
• CPC Class Codes: Y10S 148/005 Antimonides of gallium or indium
• CPC Class Codes: Y10S 148/042 Doping, graded, for tapered etching
• CPC Class Codes: Y10S 148/056 Gallium arsenide
• CPC Class Codes: Y10S 148/058 Ge germanium
• CPC Class Codes: Y10S 148/064 Gp II-VI compounds
• CPC Class Codes: Y10S 148/065 Gp III-V generic compounds-processing
• CPC Class Codes: Y10S 148/083 Ion implantation, general
• CPC Class Codes: Y10S 148/119 Phosphides of gallium or indium
• CPC Class Codes: Y10S 148/135 Removal of substrate
• CPC Class Codes: Y10S 148/90 Ion implanted
• CPC Class Codes: Y10S 438/924 To facilitate selective etching
• CPC Class Codes: Y10S 438/977 Thinning or removal of substrate
• CPC Class Codes: Y10T 428/261 In terms of molecular thickness or light wave length
• CPC Class Codes: Y10T 428/266 : of base or substrate
• CPC Class Codes: Y10T 428/31 : Surface property or characteristic of web, sheet or block
• CPC Class Codes: Y10T 428/315 : Surface modified glass [e.g., tempered, strengthened, etc.]

Abstract

This invention relates to ultra-thin semiconductor films which can be in the submicron range formed from semiconductor materials such as silicon, germanium and gallium aresenide. The films are formed by creating a thin slightly damaged surface on the polished reverse side of a film (e.g., a wafer) of the semiconductor by low dose ion implantation and then etching the semiconductor material on the front side of the film to remove the semiconductor material down to the ion implanted damaged layer. While the implanted ions can be chosen from functionally desirable ions which upon annealing remain in the film to alter the original electrical characteristics, the implanted ions can also be chosen so that upon annealing, the resultant ultra-thin semiconductor film has the same electrical characteristics as the original semiconductor material.

The ion implantation changes the etching characteristics of the ion implanted layer. Thus, when the partially damaged semiconductor material is exposed to an etchant the etching rate in the damaged region is decreased by a factor of several thousand as compared to the undamag

GOVERNMENT FUNDING

The invention described and claimed herein was at least in part supported by the National Submicron Facility under NSF Grant #ECS-8200312 to the NRRFSS.

Claims

1. A method for forming ultra thin semiconductor material films which comprises:

(a) implanting ions on the reverse side of a semiconductor material film to a predetermined depth of two microns or less, which is a depth less than the thickness of the film, in an amount sufficient to cause a damaged layer in the crystalline structure with damage sufficient to create a significant differential etching dissolution rate between the damaged layer and the remainder of the semiconductor material,

(b) etching the front side of the semiconductor material by an anodic etching process to remove at least a portion of the undamaged portion of the semiconductor material to expose the damaged layer,

(c) annealing the resultant exposed damaged layer at a temperature and for a time sufficient to heal the ion implantation damage to thereby provide a thin film of semiconductor material less than two microns in thickness.

2. A method as in claim 1 where the semiconductor material is silicon.

3. A method as in claim 1 wherein the semiconductor material is silicon or germanium and where the ions are selected from Groups III and V of the Periodic Table, an inert gas or hydrogen.

4. A method as in claim 1 wherein the semiconductor material is gallium arsenide and where the ions are selected from Groups II, IV or VI of the Periodic Table, an inert gas or hydrogen.

5. A method as in claim 1 wherein the semiconductor material is selected from the group consisting of silicon, germanium and gallium arsenide.

6. The method as in claims 1 or 5 wherein the resultant thin film has a thickness of less than 1500 Å

.

7. A thin annealed unsupported gallium arsenide monocrystalline semiconductor material having a thickness of less than one micron, doped with ions selected from group II and IV of the Periodic Table.

9. The thin semiconductor material of claims 7 or 8, having a thickness of less than 1500Å

.

8. A thin annealed germanium monocrystalline etching process-produced semiconductor material having a thickness of less than one micron.

10. A thin annealed undoped monocrystalline etching process-produced semiconductor material selected from the group consisting of silicon, gallium arsenide, germanium, indium arsenide, AlN, GaN, InN, ZnS, CdS, AlP, GaP, InP, ZnSe, CdSe, AlAs, ZnTe, CeTe, AlSb, GaSb, InSb, InAs_x P_1-x, Ga_x In_1-x As_y P_1-y having a thickness of less than one micron.

20. The thin annealed monocrystalline semiconductor material of claims 7, 8, 10, 11, 14, 15, 16, 17 or 19 having a thickness of less than 1500Å

.

11. A thin annealed unsupported monocrystalline semiconductor material doped with ions selected from Group II, IV or V of the Periodic Table having a thickness less than one micron and having the same electrical characteristic as the original doped semiconductor material used to create the thin semiconductor material.

12. A thin annealed unsupported monocrystalline undoped semiconductor material or a semiconductor material doped with ions selected from Groups II, IV or V of the Periodic Table having a thickness of less than 1500Å

and having the same electrical characteristics as the original undoped or doped semiconductor material used to create the thin semiconductor material.

13. A thin annealed unsupported monocrystalline semiconductor material having a thickness of less than one micron and doped with ions selected from Group V of the Periodic Table.

14. A thin annealed monocrystalline semiconductor film comprising gallium arsenide having a thickness of less than one micron, doped with donor ions.

15. A thin annealed unsupported monocrystalline semiconductor film comprising a material selected from the group consisting of silicon and germanium having a thickness of less than one micron doped with donor ions.

16. A thin annealed monocrystalline etching process-produced semiconductor material comprising a material selected from the group consisting of indium arsenide, AlN, GaN, InN, ZnS, CdS, AlP, GaP, InP, ZnSe, CdSe, AlAs, ZnTe, CdTe, AlSb, GaSb, InSb, InAs_x P_1-x'"'"' Ga_x In_1-X As_y P_1-y'"'"' and doped diamond, having a thickness of less than two microns.

17. A thin annealed monocrystalline semiconductor material as in claim 16 wherein the thin semiconductor material has the same electrical characteristics as the semiconductor material used to create the thin semiconductor material.

18. The thin annealed monocrystalline semiconductor material of claims 16 or 17 having a thickness of less than one micron.

19. A thin unsupported annealed undoped monocrystalline semiconductor material selected from the group consisting of silicon, allium arsenide, germanium, indium arsenide, AlA, GaN, InW, ZnS, CdS, AlP, GaP, InP, ZnSe, CdSe, AlAs, ZnTe, CdTe, AlSb, GaSb, InSb, InAs_x P_1-x, Ga_x In_1-x As_y P_1-y, and doped diamond, having a thickness of less than 1500Å

.

21. A thin annealed unsupported monocrystaline semiconductor material comprising gallium arsenide having a thickness of less than 1500Å

.

22. A thin annealed monocrystalline unsupported undoped semiconductor material or an unsupported semiconductor material doped with ions selected from groups II, IV or V of the Periodic Table having a thickness of less than one micron and having the same electrical characteristics as the original undoped or doped semiconductor material used to create the thin semiconductor material used to create the thin semiconductor material.