Method for forming ZnO film, method for forming ZnO semiconductor layer, method for fabricating semiconductor device, and semiconductor device

• US 7,049,190 B2
• Filed: 03/17/2003
• Issued: 05/23/2006
• Est. Priority Date: 03/15/2002
• Status: Expired due to Fees

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Takeda, Katsutoshi, Isomura, Masao
• Primary Examiner(s): Fourson, George
• Assistant Examiner(s): Toledo, Fernando L.
• Application Number:
  US10/390,563
• Publication Number:
  US 20040038446A1
• Time in Patent Office: 1,163 Days
• Field of Search: 438/216, 438/261, 438/287, 438/591
• US Class Current: 438/216
• CPC Class Codes: C30B 23/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/16 Oxides
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02472 Oxides
• CPC Class Codes: H01L 21/02516 Crystal orientation
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 29/22 including, apart from doping materials or other impurities, only AIIBVI compounds
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/78603 characterised by the insulating substrate or support H01L29/78657 takes precedence
• CPC Class Codes: H01L 29/78621 with LDD structure or an extension or an offset region or characterised by the doping profile
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

A ZnO buffer layer having an electric conductivity of 1×10⁻⁹ S/cm or lower or alternatively a ZnO buffer layer having a diffraction peak of a crystal face other than (002) and (004) in X-ray diffraction is formed on a substrate by sputtering. A ZnO semiconductor layer is formed on the ZnO buffer layer. The ZnO semiconductor layer is formed under the condition that the flow rate ratio of an oxygen gas in a sputtering gas is lower than that in the formation of the ZnO buffer layer.

Claims

1. A method for fabricating a semiconductor device, comprising the steps of:

using a non-doped ZnO target and forming a first ZnO film on a substrate by sputtering with a sputtering gas containing oxygen and also forming a second ZnO film on the first ZnO film by sputtering with the flow rate ratio of the oxygen gas in the sputtering gas being decreased continuously;

forming a groove dividing the second ZnO film;

providing a gate electrode over the groove via an insulating layer; and

providing, on the second ZnO film, a source electrode and a drain electrode facing each other with the groove therebetween.

2. The method for fabricating a semiconductor device according to claim 1 in which the step for forming a said first ZnO film by sputtering, further comprises:

oxygen gas, or a mixture of an inert gas and an oxygen gas as a said sputtering gas; and

changing the flow rate ratio of the oxygen gas in the sputtering gas during the film formation.

3. The method for forming a said first ZnO film according to claim 2, wherein the flow rate ratio of the oxygen gas is changed continuously.

4. The method for forming said first ZnO film according to claim 2, wherein the flow rate ratio of the oxygen gas is increased and decreased alternately.