Method for manufacturing semiconductor device

• US 8,609,478 B2
• Filed: 06/29/2010
• Issued: 12/17/2013
• Est. Priority Date: 06/30/2009
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Sasaki, Toshinari, Sakata, Junichiro, Ohara, Hiroki, Yamazaki, Shunpei
• Primary Examiner(s): Smith, Zandra
• Assistant Examiner(s): THOMAS, TONIAE M
• Application Number:
  US12/826,007
• Publication Number:
  US 20110003427A1
• Time in Patent Office: 1,267 Days
• Field of Search: 438/159, 438/483, 438/486, 257/E21.414
• US Class Current: 438/159
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02664 Aftertreatments planarisation in general H01L21/304
• 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 29/78606 with supplementary region or layer in the thin film or in the insulated bulk substrate supporting it for controlling or increasing the safety of the device H01L29/78642, H01L29/78645 take precedence
• CPC Class Codes: H01L 29/78618 characterised by the drain or the source properties, e.g. the doping structure, the composition, the sectional shape or the contact structure silicide contacts, electrodes in general H01L29/458
• 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

It is an object to provide a highly reliable semiconductor device which includes a thin film transistor having stable electric characteristics. It is another object to manufacture a highly reliable semiconductor device at lower cost with high productivity. In a method for manufacturing a semiconductor device which includes a thin film transistor where a semiconductor layer including a channel formation region using an oxide semiconductor layer, a source region, and a drain region are formed using an oxide semiconductor layer, heat treatment for reducing impurities such as moisture (heat treatment for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor layer.

Claims

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

forming a gate electrode layer;

forming a gate insulating layer over the gate electrode layer;

forming a first oxide semiconductor film over the gate insulating layer;

forming a second oxide semiconductor film over the first oxide semiconductor film;

heating the first oxide semiconductor film and the second oxide semiconductor film under an inert gas atmosphere so that a carrier concentration in the second oxide semiconductor film is increased;

selectively etching the first oxide semiconductor film and the second oxide semiconductor film so as to form a first oxide semiconductor layer and a second oxide semiconductor layer;

forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer;

forming a semiconductor layer, a source region, a drain region, a source electrode layer, and a drain electrode layer by selectively etching the first oxide semiconductor layer, the second oxide semiconductor layer, and the conductive film, wherein a part of the semiconductor layer has a depression; and

forming an oxide insulating film over the semiconductor layer, the source electrode layer, and the drain electrode layer, wherein the oxide insulating film is in contact with the part of the semiconductor layer so that a carrier concentration in the part of the semiconductor layer is reduced.

2. The method for manufacturing a semiconductor device, according to claim 1, wherein the inert gas atmosphere is a nitrogen atmosphere.

3. The method for manufacturing a semiconductor device, according to claim 1, wherein the inert gas atmosphere is a rare gas atmosphere.

10. The method for manufacturing a semiconductor device, according to claim 1 or 4, wherein the carrier concentration in the second oxide semiconductor after heating and before forming the oxide insulating film is 1×

10¹⁸/cm³ or higher.

11. The method for manufacturing a semiconductor device, according to any one of claims 1 and 4-6, wherein the first oxide semiconductor film and the second oxide semiconductor film are heated at 400°

C. or higher.

12. The method for manufacturing a semiconductor device, according to any one of claims 1 and 4-6, further comprising the step of slowly cooling the first oxide semiconductor film and the second oxide semiconductor film to higher than or equal to room temperature and lower than 100°

C. after heating the first oxide semiconductor film and the second oxide semiconductor film.

13. The method for manufacturing a semiconductor device, according to any one of claims 1 and 4-6, wherein the first oxide semiconductor film and the second oxide semiconductor film is heated at 400°

C. or higher and 450°

C. or lower.

14. The method for manufacturing a semiconductor device, according to any one of claims 1 and 4-6,

wherein the first oxide semiconductor film and the second oxide semiconductor film are heated in a first chamber heated to higher than or equal to 400°

C. and lower than or equal to 450°

C., and

wherein the first oxide semiconductor film and the second oxide semiconductor film are cooled in a second chamber of which temperature is lower than or equal to 100°

C.

15. The method for manufacturing a semiconductor device, according to any one of claims 1 and 4-6,

wherein the first oxide semiconductor film and the second oxide semiconductor film are heated in a first chamber heated to higher than or equal to 400°

C. and lower than or equal to 450°

C.,

wherein the first oxide semiconductor film and the second oxide semiconductor film are cooled in a second chamber filled with nitrogen or a rare gas, and

wherein temperature of the second chamber is lower than or equal to 100°

C.

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

forming a gate electrode layer;

forming a gate insulating layer over the gate electrode layer;

forming a first oxide semiconductor film over the gate insulating layer;

forming a second oxide semiconductor film over the first oxide semiconductor film;

heating the first oxide semiconductor film and the second oxide semiconductor film under reduced pressure so that a carrier concentration in the second oxide semiconductor film is increased;

selectively etching the first oxide semiconductor film and the second oxide semiconductor film so as to form a first oxide semiconductor layer and a second oxide semiconductor layer;

forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer;

forming a semiconductor layer, a source region, a drain region, a source electrode layer, and a drain electrode layer by selectively etching the first oxide semiconductor layer, the second oxide semiconductor layer, and the conductive film; and

forming an oxide insulating film over the semiconductor layer, the source electrode layer, and the drain electrode layer, wherein the oxide insulating film is in contact with a part of the semiconductor layer so that a carrier concentration in the part of the semiconductor layer is reduced.

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

forming a gate electrode layer;

forming a gate insulating layer over the gate electrode layer;

forming a first oxide semiconductor film over the gate insulating layer;

forming a second oxide semiconductor film over the first oxide semiconductor film;

heating the first oxide semiconductor film and the second oxide semiconductor film so as to dehydrate or dehydrogenate the first oxide semiconductor film and the second oxide semiconductor film;

selectively etching the first oxide semiconductor film and the second oxide semiconductor film so as to form a first oxide semiconductor layer and a second oxide semiconductor layer;

forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer;

forming a semiconductor layer, a source region, a drain region, a source electrode layer, and a drain electrode layer by selectively etching the first oxide semiconductor layer, the second oxide semiconductor layer, and the conductive film, wherein a part of the semiconductor layer has a depression; and

forming an oxide insulating film over the semiconductor layer, the source electrode layer, and the drain electrode layer, wherein the oxide insulating film is in contact with the part of the semiconductor layer so that a carrier concentration in the part of the semiconductor layer is reduced.

7. The method for manufacturing a semiconductor device, according to claim 5 or 6, wherein the first oxide semiconductor film and the second oxide semiconductor film are heated under an inert gas atmosphere.

8. The method for manufacturing a semiconductor device, according to claim 7, wherein the inert gas atmosphere is a nitrogen atmosphere.

9. The method for manufacturing a semiconductor device, according to claim 7, wherein the inert gas atmosphere is a rare gas atmosphere.

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

forming a first oxide semiconductor film on an insulating layer;

forming a second oxide semiconductor film over the first oxide semiconductor film;

heating the first oxide semiconductor film and the second oxide semiconductor film so as to at least partly remove hydrogen in the first oxide semiconductor film and the second oxide semiconductor film;

selectively etching the first oxide semiconductor film and the second oxide semiconductor film so as to form a first oxide semiconductor layer and a second oxide semiconductor layer;

forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer;

forming a semiconductor layer, a source region, a drain region, a source electrode layer, and a drain electrode layer by selectively etching the first oxide semiconductor layer, the second oxide semiconductor layer, and the conductive film, wherein a part of the semiconductor layer has a depression; and

forming an oxide insulating film over the semiconductor layer, the source electrode layer, and the drain electrode layer, wherein the oxide insulating film is in contact with the part of the semiconductor layer so that a carrier concentration in the part of the semiconductor layer is reduced.