Ultra-thin semiconductor membranes

• US 4,952,446 A
• Filed: 12/14/1988
• Issued: 08/28/1990
• 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, Charles A., Lee, Kevin C., Silcox, John
• Primary Examiner(s): Cannon, James C.
• Application Number:
  US07/284,822
• Time in Patent Office: 622 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, 428/333, 428/337, 428/446, 428/220, 437/225, 437/247, 437/966, 437/974
• US Class Current: 428/220
• CPC Class Codes: H01L 21/26506 in group IV semiconductors
• CPC Class Codes: H01L 21/2654 in AIIIBV compounds
• 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 21/425 producing ion implantation
• 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 arsenide. 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 undamaged semiconductor material.

Claims

1. A monocrystalline unsupported thin semiconductor material having a thickness variance of less than 10% over an area having a diameter greater than 100 times the thickness and having a thickness of less than one micron wherein the starting material used to form the thin material is a semiconductor material which was damaged by ion implantation, anodically etched to form the thin material and subsequently annealed to repair the damage.

2. The semiconductor material of claim 1 which is silicon.

3. The semiconductor material of claim 1 which is germanium.

4. A thin unsupported annealed monocrystalline semiconductor material selected from the group consisting of germanium, doped diamond, indium arsenide, AlN, GaN, InN, ZnS, CdS, AlP, GaP, ZnSe, CdSe, AlAs, ZnTe, CdTe, AlSb, GaSb, InSb, Al_x Ga_l-x As, InAs_x P_l-x, Ga_x In_l-x As_y P_l-y having a thickness of less than about 3500Å

.

5. The thin semiconductor material of claim 4 which is germanium.

6. The thin semiconductor material of claim 4 having a thickness of between about 1500A and 50A.

7. The thin semiconductor material of claims 4, 5 or 6 having thickness variance of less than 10% over an area having a diameter greater than 100 times the thickness.

8. A thin unsupported etching process-produced monocrystalline silicon device-quality semiconductor material having electrical characteristics essentially identical to the virgin semiconductor material used to form the thin semiconductor material or containing dopant ions comprising donor ions and having a thickness of less than one micron.