Semiconductor device and manufacturing method thereof

• US 9,812,544 B2
• Filed: 11/09/2015
• Issued: 11/07/2017
• Est. Priority Date: 12/17/2010
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Endo, Yuta, Sasaki, Toshinari, Noda, Kosei, Sato, Hitomi, Sato, Yuhei
• Primary Examiner(s): Everhart, Caridad
• Assistant Examiner(s): SINGAL, ANKUSH K
• Application Number:
  US14/935,553
• Publication Number:
  US 20160064505A1
• Time in Patent Office: 729 Days
• CPC Class Codes: H01L 21/28088 the final conductor layer next to the insulator being a composite, e.g. TiN
• CPC Class Codes: H01L 21/288 from a liquid, e.g. electrolytic deposition
• 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 29/42384 for thin film field effect transistors, e.g. characterised by the thickness or the shape of the insulator or the dimensions, the shape or the lay-out of the conductor
• 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 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate

Abstract

To manufacture a transistor whose threshold voltage is controlled without using a backgate electrode, a circuit for controlling the threshold voltage, and an impurity introduction method. To manufacture a semiconductor device having favorable electrical characteristics, high reliability, and low power consumption using the transistor. A gate electrode including a tungsten oxide film whose composition is controlled is used. The composition or the like is adjusted by a film formation method of the tungsten oxide film, whereby the work function can be controlled. By using the tungsten oxide film whose work function is controlled as part of the gate electrode, the threshold of the transistor can be controlled. Using the transistor whose threshold voltage is controlled, a semiconductor device having favorable electrical characteristics, high reliability, and low power consumption can be manufactured.

Claims

1. A method for manufacturing a semiconductor device comprising:

forming an oxide semiconductor film over a substrate;

forming a gate insulating film over the oxide semiconductor film; and

forming a gate electrode including a tungsten oxide film by a sputtering method over the gate insulating film,

wherein a work function of the gate electrode is higher than or equal to 4.9 eV and lower than or equal to 5.6 eV,

wherein a thickness of the gate electrode is greater than or equal to 10 nm.

2. The method according to claim 1 further comprising:

forming a pair of electrodes between the gate electrode and the oxide semiconductor film before forming the oxide semiconductor film.

3. The method according to claim 1 further comprising:

forming a pair of electrodes over the oxide semiconductor film.

4. The method according to claim 1, wherein one or more gases selected from a rare gas, oxygen, and nitrogen is used as a film formation gas in the sputtering method.

5. The method according to claim 1 further comprising:

performing heat treatment after forming the gate electrode.

6. The method according to claim 1, wherein the oxide semiconductor film includes two or more elements selected from In, Ga, Zn, Sn, and Al.

7. The method according to claim 1, wherein the sputtering method is a bias sputtering method.

8. The method according to claim 1, wherein the sputtering method uses two or more targets selected from tungsten target, tungsten dioxide target, tungsten trioxide target, and target of tungsten oxide with another valence.

9. The method according to claim 1, wherein the gate electrode includes nitrogen at greater than or equal to 0.1 at % and lower than or equal to 20 at%.

10. A method for manufacturing a semiconductor device comprising:

forming an oxide semiconductor film over a substrate;

forming a gate insulating film over the oxide semiconductor film; and

forming a gate electrode including a film including tungsten and oxygen by a sputtering method over the gate insulating film,

wherein a work function of the gate electrode is higher than or equal to 4.9 eV and lower than or equal to 5.6 eV,

wherein a thickness of the gate electrode is greater than or equal to 10 nm.

11. The method according to claim 10 further comprising:

forming a pair of electrodes between the gate electrode and the oxide semiconductor film before forming the oxide semiconductor film.

12. The method according to claim 10 further comprising:

forming a pair of electrodes over the oxide semiconductor film.

13. The method according to claim 10, wherein one or more gases selected from a rare gas, oxygen, and nitrogen is used as a film formation gas in the sputtering method.

14. The method according to claim 10 further comprising:

performing heat treatment after forming the gate electrode.

15. The method according to claim 10, wherein the oxide semiconductor film includes two or more elements selected from In, Ga, Zn, Sn, and Al.

16. The method according to claim 10, wherein the sputtering method is a bias sputtering method.

17. The method according to claim 10, wherein the sputtering method uses two or more targets selected from tungsten target, tungsten dioxide target, tungsten trioxide target, and target of tungsten oxide with another valence.

18. The method according to claim 10, wherein the gate electrode includes nitrogen at greater than or equal to 0.1 at % and lower than or equal to 20 at%.