METHOD OF MAKING SEMICONDUCTOR DEVICES

• US 3,716,429 A
• Filed: 06/18/1970
• Issued: 02/13/1973
• Est. Priority Date: 06/18/1970
• Status: Expired due to Term

• Current Assignee: John Joseph Hughes, Louis Sebastian Napoli
• Original Assignee: John Joseph Hughes, Louis Sebastian Napoli
• Inventors: Napoli, Louis Sebastian, Hughes, John Joseph
• Primary Examiner(s): Lanham, Charles W.
• Assistant Examiner(s): Tupman, W.
• Application Number:
  US05/047,425
• Time in Patent Office: 971 Days
• Field of Search: 29/578,580,583,579 317/8,8.1 156/17,3
• US Class Current: 438/460
• CPC Class Codes: H01L 21/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• CPC Class Codes: H01L 21/3081 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/3086 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 29/00 Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor H01L31/00 - H01L33/00, H10K10/00, H10N take precedence; details other than of semiconductor bodies or of electrodes thereof H01L23/00; devices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00
• CPC Class Codes: Y10S 148/051 Etching
• CPC Class Codes: Y10S 438/944 Shadow
• CPC Class Codes: Y10S 438/977 Thinning or removal of substrate

Abstract

Semiconductor devices having thin bodies of a semiconductor material are made from a wafer of the semiconductor material which is thicker than the bodies of the devices. The thicker wafer is provided with spaced thinner portions of the desired area and thickness of the bodies of the devices to be formed by etching recesses in one surface of the wafer. The recesses are formed with flat bottoms which are of the desired area of the bodies of the devices. A masking layer is coated on the bottom of each of the recesses. The active region of each of the devices is formed at the other surface of the wafer over each of the recesses. The semiconductor material between the thin portions of the wafer is then removed by etching the wafer from the one surface of the wafer so as to separate the thin portions of the wafer to form the individual devices. During the last etching process the masking layers on the bottom of the recess protect the thin portions of the wafer from being etched.

Claims

1. A method of making a semiconductor device which includes a thin body of a semiconductor material having an active region at a surface thereof comprising the steps of a. providing a wafer of the semiconductor which has a pair of opposed surfaces and which is larger than the body of the device to be formed, b. coating one surface of the wafer with a film of a metal which is not attacked by an etchant for the semiconductor material of the wafer, c. providing an opening in the metal film to expose a portion of the one surface of the wafer of an area corresponding to the desired area of the body of the device, d. contacting the exposed portion of the one surface of the wafer with an etchant to form a recess in said surface with the bottom surface of the recess being of an area at least as large as the desired area of the body of the device and the side wall of the recess being spaced from the edge of the opening in the metal film so that a portion of the metal film around the edge of the opening extends over and overhangs in cantilever fashion the recess, e. passing vapors of a masking material into the recess through the opening in the metal film with the overhanging portion of the metal film shadow masking the side wall of the recess and condensing the vapors on the bottom surface of the recess to coat the bottom surface of the recess with a masking layer, f. forming the active region of the semiconductor device at a surface of the wafer in the region of the wafer coated by the masking layer, and then g. removing the material of the wafer not coated by the masking layer so as to leave the portion of the wafer coated with the masking layer and the active region.

2. A method according to claim 1 wherein said recess is formed prior to the active region of the semiconductor device being formed.

3. A method according to claim 1 wherein said active region of the semiconductor device is formed prior to said recess being formed in said wafer.

4. The method according to claim 1 wherein said active region of the semiconductor device is formed at a surface thereof opposite to the surface in which said recess is formed.

5. The method according to claim 1 wherein said active region of the semiconductor device is formed at the bottom surface of said recess.

6. The method of claim 1 in which the masking layer is of a material which is not attacked by an etchant for the material of the wafer and the material of the wafer not coated by the masking layer is removed by contacting the one surface of the wafer with an etchant.

7. The method of cLaim 6 in which the metal layer is removed prior to etching away the material of the wafer not coated by the masking layer.

8. The method of claim 7 in which the layer is removed by lapping.