Semiconductor device and method for manufacturing the same

• US 9,276,121 B2
• Filed: 04/09/2013
• Issued: 03/01/2016
• Est. Priority Date: 04/12/2012
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei
• Primary Examiner(s): Lee, Cheung
• Assistant Examiner(s): Hargrove, Frederick B
• Application Number:
  US13/859,163
• Publication Number:
  US 20130270563A1
• Time in Patent Office: 1,057 Days
• Field of Search: 257/43, 257/57, 438/158
• US Class Current: 1/1
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/285 from a gas or vapour, e.g. condensation
• CPC Class Codes: H01L 21/30604 Chemical etching
• CPC Class Codes: H01L 21/30625 With simultaneous mechanical treatment, e.g. mechanico-chemical polishing
• CPC Class Codes: H01L 29/4908 for thin film semiconductor, e.g. gate of TFT
• CPC Class Codes: H01L 29/66742 Thin film unipolar transistors
• CPC Class Codes: H01L 29/78609 for preventing leakage current H01L29/78618 takes precedence
• 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 semiconductor device including a transistor in which an oxide semiconductor is used for a channel formation region and which has a positive threshold voltage to serve as a normally-off switching element, and the like are provided. Stable electrical characteristics are given to the semiconductor device including the transistor in which an oxide semiconductor film is used for the channel formation region, and thus the semiconductor device has high reliability. In a semiconductor device including a transistor in which an oxide semiconductor film including a channel formation region, source and drain electrode layers, a gate insulating film, and a gate electrode layer are stacked in this order over an oxide insulating film, a conductive layer overlapping with the gate electrode layer with the channel formation region provided therebetween and controlling the electrical characteristics of the transistor is provided in the oxide insulating film including an oxygen excess region.

Claims

1. A semiconductor device comprising:

a first insulating film containing aluminum oxide;

a conductive layer over the first insulating film;

a first oxide insulating film over the conductive layer, wherein the first oxide insulating film, and wherein an upper surface of the first oxide insulating film is planarized;

an oxide semiconductor layer comprising a channel formation region over the planarized surface of the first oxide insulating film, wherein the channel formation region overlaps with the conductive layer;

a source electrode layer and a drain electrode layer electrically connected to the oxide semiconductor layer;

a gate insulating film over the oxide semiconductor layer;

a gate electrode layer over the channel formation region with the gate insulating film interposed therebetween; and

a second insulating film containing aluminum oxide over the oxide semiconductor layer, the source electrode layer, the drain electrode layer, and the gate electrode layer,

wherein the first oxide insulating film comprises a first region which overlaps with the conductive layer, and a second region which does not overlap with the conductive layer,

wherein a first thickness of the first oxide insulating film in the first region is smaller than a second thickness of the first oxide insulating film in the second region,

wherein the first insulating film is in direct contact with the second insulating film, and

wherein the conductive layer, the first oxide insulating film, the oxide semiconductor layer, the source electrode layer, the drain electrode layer, the gate insulating film, and the gate electrode layer are between the first insulating film and the second insulating film.

2. The semiconductor device according to claim 1, wherein the gate insulating film is a second oxide insulating film.

3. The semiconductor device according to claim 1, further comprising a third insulating film containing aluminum oxide between the conductive layer and the first oxide insulating film.

4. The semiconductor device according to claim 1,

wherein the conductive layer comprises a first conductive film and a second conductive film over the first conductive film, and

wherein the second conductive film comprises a metal oxide containing nitrogen.

5. The semiconductor device according to claim 1,

wherein the gate electrode layer comprises a first conductive film and a second conductive film over the first conductive film, and

wherein the first conductive film comprises a metal oxide containing nitrogen.

6. The semiconductor device according to claim 1, wherein the gate electrode layer overlaps with the source electrode layer and the drain electrode layer.

7. The semiconductor device according to claim 1, wherein the oxide semiconductor layer comprises a first oxide semiconductor film and a second oxide semiconductor film over the first oxide semiconductor film.

8. A semiconductor device comprising:

a first insulating film containing aluminum oxide;

a conductive layer over the first insulating film;

a first oxide insulating film over the conductive layer and the first insulating film, wherein the first oxide insulating film comprises an oxygen excess region, and wherein an upper surface of the first oxide insulating film is planarized;

an oxide semiconductor layer comprising a channel formation region over the planarized surface of the first oxide insulating film, wherein the channel formation region overlaps with the conductive layer;

a source electrode layer and a drain electrode layer electrically connected to the oxide semiconductor layer;

a gate insulating film over the oxide semiconductor layer;

a gate electrode layer over the channel formation region with the gate insulating film interposed therebetween; and

a second insulating film containing aluminum oxide over the oxide semiconductor layer, the source electrode layer, the drain electrode layer, and the gate electrode layer,

wherein the first oxide insulating film comprises a first region which overlaps with the conductive layer, and a second region which does not overlap with the conductive layer,

wherein a first thickness of the first oxide insulating film in the first region is smaller than a second thickness of the first oxide insulating film in the second region,

wherein a first distance between the oxygen excess region in the first region and the channel formation region is shorter than a second distance between the oxygen excess region in the second region and each of the source electrode layer and the drain electrode layer,

wherein the first insulating film is in direct contact with the second insulating film, and

wherein the conductive layer, the first oxide insulating film, the oxide semiconductor layer, the source electrode layer, the drain electrode layer, the gate insulating film, and the gate electrode layer are between the first insulating film and the second insulating film.

9. The semiconductor device according to claim 8, wherein the gate insulating film is a second oxide insulating film.

10. The semiconductor device according to claim 8, further comprising a third insulating film containing aluminum oxide between the conductive layer and the first oxide insulating film.

11. The semiconductor device according to claim 8,

wherein the conductive layer comprises a first conductive film and a second conductive film over the first conductive film, and

wherein the second conductive film comprises a metal oxide containing nitrogen.

12. The semiconductor device according to claim 8,

wherein the gate electrode layer comprises a first conductive film and a second conductive film over the first conductive film, and

wherein the first conductive film comprises a metal oxide containing nitrogen.

13. The semiconductor device according to claim 8, wherein the gate electrode layer overlaps with the source electrode layer and the drain electrode layer.

14. The semiconductor device according to claim 8, wherein the oxide semiconductor layer comprises a first oxide semiconductor film and a second oxide semiconductor film over the first oxide semiconductor film.