INSULATED-GATE FIELD EFFECT SEMICONDUCTOR DEVICE HAVING LOW AND STABLE GATE THRESHOLD VOLTAGE

• US 3,806,778 A
• Filed: 12/21/1972
• Issued: 04/23/1974
• Est. Priority Date: 12/24/1971
• Status: Expired due to Term

• Current Assignee: Hideo Tsunemitsu, Keiichi Shimakura
• Original Assignee: Hideo Tsunemitsu, Keiichi Shimakura
• Inventors: Tsunemitsu, Hideo, Shimakura, Keiichi
• Primary Examiner(s): Rolinec, Rudolph V.
• Assistant Examiner(s): Wojciechowicz, E.
• Application Number:
  US05/317,295
• Time in Patent Office: 488 Days
• Field of Search: 317/235,46,46.5
• US Class Current: 257/406
• CPC Class Codes: H01L 23/291 Oxides or nitrides or carbides, e.g. ceramics, glass
• 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: H01L 29/40114 the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

An insulated-gate field effect transistor includes a gate electrode composed of a tantalum layer and an aluminum layer. An insulating film composed of a tantalum oxide layer and an aluminum oxide layer is disposed about the gate electrode and insulates the gate electrode from the source and drain electrodes. In the fabrication of the device, the aluminum oxide and tantalum oxide layers are formed by anodic oxidation.

Claims

2. The device of claim 1, in which said tantalum layer has a thickness of between 100 and 1,000 angstroms, and said aluminum layer has a thickness of at least 1 micron.

3. An insulated-gate field effect semiconductor device comprising a semiconductor substrate, source and drain regions formed in said substrate, a gate insulator film and a first insulating film covering a part of the surface of said substrate, a gate electrode disposed on said gate insulator film, source and drain electrodes connected respectively to said source and drain regions and extending onto the surface of said first insulating film, and a second insulating film disposed on the surface of said first insulating film not covered with said electrodes, said electrodes comprising a tantalum layer and an aluminum layer, and said second insulating film comprising a tantalum oxide layer and an aluminum oxide layer.

4. The device of claim 3, in which the thickness of said tantalum layer and said aluminum layer range from 500 to 1,000 angstroms and from 1 to 1.7 micron, respectively.

5. A method of producing an insulated-gate field effect transistor, comprising the steps of forming source and drain regions in a semiconductor substrate, covering the surface of said substrate with a gate insulator film and an insulating film, forming openings in said insulating film for making electrical connection to said source and drain regions, depositing a tantalum layer over the surface of said substrate coated with said gate insulator film and said insulating film, depositing an aluminum layer over the surface of said tantalum layer, selectively converting a predetermined portion of said aluminum layer into an aluminum oxide layer by anodic oxidation, and selectively converting a predetermined portion of said tantalum layer into a tantalum oxide layer by anodic oxidation, the unoxidized portions of said aluminum layer and said tantalum layer constituting double metallic layer gate, source, and drain electrodes, said tantalum oxide layer and said aluminum oxide layer constituting an insulating film disposed between and providing insulation betWeen said double metallic layer gate electrode and said double metallic layer source and drain electrodes.