Method for manufacturing semiconductor device

• US 9,373,708 B2
• Filed: 05/21/2015
• Issued: 06/21/2016
• Est. Priority Date: 05/13/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Sasagawa, Shinya, Nakayama, Hitoshi, Fujiki, Hiroshi
• Primary Examiner(s): Mandala, Victor A
• Assistant Examiner(s): Rundio, Regan J
• Application Number:
  US14/718,763
• Publication Number:
  US 20150255584A1
• Time in Patent Office: 397 Days
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• 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 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

To establish a processing technique in manufacture of a semiconductor device including an In—Sn—Zn—O-based semiconductor. An In—Sn—Zn—O-based semiconductor layer is selectively etched by dry etching with the use of a gas containing chlorine such as Cl₂, BCl₃, SiCl₄, or the like. In formation of a source electrode layer and a drain electrode layer, a conductive layer on and in contact with the In—Sn—Zn—O-based semiconductor layer can be selectively etched with little removal of the In—Sn—Zn—O-based semiconductor layer with the use of a gas containing oxygen or fluorine in addition to a gas containing chlorine.

Claims

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

forming an oxide semiconductor layer over an oxide insulating layer;

performing a heat treatment of the oxide semiconductor layer in an inert atmosphere and then in an oxidation atmosphere by switching the inert atmosphere to the oxidation atmosphere with a temperature of the heat treatment maintained; and

selectively removing the oxide semiconductor layer by dry etching using a gas containing chlorine so that part of the oxide insulating layer is exposed,

wherein the oxide semiconductor layer comprises an In—

Sn—

Zn—

O-based semiconductor layer, and

wherein a thickness of an exposed region of the oxide insulating layer is smaller than a thickness of a region of the oxide insulating layer overlapped with the oxide semiconductor layer.

2. The method according to claim 1, wherein a taper angle of an end portion of the oxide semiconductor layer is greater than or equal to 10°

and less than or equal to 70°

after the dry etching.

3. The method according to claim 1, wherein a gas containing oxygen, a gas containing fluorine, a rare gas, or a hydrocarbon gas is used in the dry etching in addition to the gas containing chlorine.

4. The method according to claim 1, wherein the gas containing chlorine is Cl₂, SiCl₄, or BCl₃.

5. The method according to claim 1, wherein the oxide semiconductor layer is formed at a substrate temperature of 100°

C. to 600°

C. inclusive.

6. The method according to claim 1,

wherein the inert atmosphere is a nitrogen atmosphere, and

wherein the oxidation atmosphere is an oxygen atmosphere.

7. A method for manufacturing a semiconductor device comprising the steps of:

forming an oxide semiconductor layer over an oxide insulating layer at a substrate temperature of 100°

C. to 600°

C. inclusive;

performing a heat treatment of the oxide semiconductor layer in an inert atmosphere and then in an oxidation atmosphere by switching the inert atmosphere to the oxidation atmosphere with a temperature of the heat treatment maintained;

selectively removing the oxide semiconductor layer by dry etching using a gas containing Cl₂ and BCl₃ so that part of the oxide insulating layer is exposed, wherein a thickness of an exposed region of the oxide insulating layer is smaller than a thickness of a region of the oxide insulating layer overlapped with the oxide semiconductor layer;

forming a conductive layer over the oxide semiconductor layer;

forming a source electrode layer and a drain electrode layer by processing the conductive layer, wherein the source electrode layer and the drain electrode layer overlap with an end portion having a taper angle of the oxide semiconductor layer;

forming a gate insulating layer over the source electrode layer and the drain electrode layer; and

forming a gate electrode over the gate insulating layer,

wherein the oxide semiconductor layer comprises an In—

Sn—

Zn—

O-based semiconductor layer, and

wherein the taper angle of the end portion of the oxide semiconductor layer is greater than or equal to 10° and

less than or equal to 70°

after the dry etching.

8. The method according to claim 7, wherein a gas containing oxygen, a gas containing fluorine, a rare gas, or a hydrocarbon gas is used in the dry etching in addition to the gas containing Cl₂ and BCl₃.

9. The method according to claim 7, wherein dry etching or wet etching is used for processing the conductive layer to form the source electrode layer and the drain electrode layer.

10. The method according to claim 7,

wherein the inert atmosphere is a nitrogen atmosphere, and

wherein the oxidation atmosphere is an oxygen atmosphere.

11. A method for manufacturing a semiconductor device comprising the steps of:

forming an oxide semiconductor layer over an oxide insulating layer;

performing a heat treatment of the oxide semiconductor layer in an inert atmosphere and then in an oxidation atmosphere by switching the inert atmosphere to the oxidation atmosphere with a temperature of the heat treatment maintained;

selectively removing the oxide semiconductor layer by a first dry etching with the use of a gas containing chlorine so that part of the oxide insulating layer is exposed, wherein a thickness of an exposed region of the oxide insulating layer is smaller than a thickness of a region of the oxide insulating layer overlapped with the oxide semiconductor layer;

forming a conductive layer over the oxide semiconductor layer;

processing the conductive layer by a second dry etching with the use of a gas containing fluorine, oxygen, and chlorine so that a source electrode layer and a drain electrode layer are formed, and so that part of the oxide semiconductor layer between the source electrode layer and the drain electrode layer is exposed, wherein the source electrode layer and the drain electrode layer overlap with an end portion having a taper angle of the oxide semiconductor layer;

forming a gate insulating layer over the source electrode layer and the drain electrode layer; and

forming a gate electrode over the gate insulating layer,

wherein the oxide semiconductor layer comprises an In—

Sn—

Zn—

O-based semiconductor layer,

wherein the taper angle of the end portion of the oxide semiconductor layer is greater than or equal to 10° and

less than or equal to 70°

after the first dry etching, and

wherein the part of the oxide semiconductor layer exposed by the second dry etching is thinner than a region overlapped with the source electrode layer and the drain electrode layer.

12. The method according to claim 11, wherein the oxide semiconductor layer is formed at a substrate temperature of 100°

C. to 600°

C. inclusive.

13. The method according to claim 11, wherein an inductively coupled plasma etching apparatus is used in the first dry etching and the second dry etching.

14. The method according to claim 11,

wherein the inert atmosphere is a nitrogen atmosphere, and

wherein the oxidation atmosphere is an oxygen atmosphere.