Method for manufacturing semiconductor device

• US 9,275,875 B2
• Filed: 10/31/2014
• Issued: 03/01/2016
• Est. Priority Date: 05/21/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Watanabe, Ryosuke, Hiraishi, Suzunosuke, Sakata, Junichiro
• Primary Examiner(s): Seven, Evren
• Application Number:
  US14/529,525
• Publication Number:
  US 20150050775A1
• Time in Patent Office: 487 Days
• Field of Search: None
• 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 21/477 Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering H01L21/38 - H01L21/449 and H01L21/461 - H01L21/475 take precedence
• 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

Abstract

An object is to provide a semiconductor device including an oxide semiconductor, which has stable electrical characteristics and high reliability. In a manufacturing process of a bottom-gate transistor including an oxide semiconductor layer, heat treatment in an atmosphere containing oxygen and heat treatment in vacuum are sequentially performed for dehydration or dehydrogenation of the oxide semiconductor layer. In addition, irradiation with light having a short wavelength is performed concurrently with the heat treatment, whereby elimination of hydrogen, OH, or the like is promoted. A transistor including an oxide semiconductor layer on which dehydration or dehydrogenation treatment is performed through such heat treatment has improved stability, so that variation in electrical characteristics of the transistor due to light irradiation or a bias-temperature stress (BT) test is suppressed.

Claims

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

forming a gate electrode;

forming a gate insulating layer over the gate electrode;

forming an oxide semiconductor layer over the gate insulating layer so as to overlap with the gate electrode;

increasing a temperature of the oxide semiconductor layer in an inert gas atmosphere, a dry air atmosphere, or an oxygen atmosphere;

performing first heat treatment on the oxide semiconductor layer under reduced pressure after the step of increasing the temperature of the oxide semiconductor layer;

performing second heat treatment on the oxide semiconductor layer in an oxygen atmosphere after the step of performing the first heat treatment;

decreasing a temperature of the oxide semiconductor layer in the oxygen atmosphere after the step of performing the second heat treatment;

forming a source electrode and a drain electrode which are electrically connected to the oxide semiconductor layer after the step of decreasing the temperature of the oxide semiconductor layer; and

forming an insulating layer over the oxide semiconductor layer, the source electrode, and the drain electrode.

2. The method for manufacturing a semiconductor device, according to claim 1, wherein a dew point of an atmosphere gas used in increasing the temperature, performing the first heat treatment, performing the second heat treatment, and decreasing the temperature is −

50°

C. or lower.

3. The method for manufacturing a semiconductor device, according to claim 1, wherein a temperature of the first heat treatment is higher than or equal to 250°

C. and lower than or equal to 650°

C.

4. The method for manufacturing a semiconductor device, according to claim 1, wherein a temperature of the second heat treatment is higher than or equal to 250°

C. and lower than or equal to 650°

C.

5. The method for manufacturing a semiconductor device, according to claim 1, wherein the first heat treatment and the second heat treatment are performed in a state where the oxide semiconductor layer is irradiated with light having a wavelength longer than or equal to 350 nm and shorter than or equal to 450 nm.

6. The method for manufacturing a semiconductor device, according to claim 1, wherein the first heat treatment and the second heat treatment under dry condition are repeated a plurality of times.

7. The method for manufacturing a semiconductor device, according to claim 1, wherein the oxide semiconductor layer is subjected to oxygen doping treatment after the step of decreasing the temperature of the oxide semiconductor layer.

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

forming an oxide semiconductor layer;

increasing a temperature of the oxide semiconductor layer in an inert gas atmosphere, a dry air atmosphere, or an oxygen atmosphere;

performing first heat treatment on the oxide semiconductor layer under reduced pressure after the step of increasing the temperature of the oxide semiconductor layer;

performing second heat treatment on the oxide semiconductor layer in an oxygen atmosphere after the step of performing the first heat treatment; and

decreasing a temperature of the oxide semiconductor layer in the oxygen atmosphere after the step of performing the second heat treatment.

9. The method for manufacturing a semiconductor device, according to claim 8, wherein a dew point of an atmosphere gas used in increasing the temperature, performing the first heat treatment, performing the second heat treatment, and decreasing the temperature is −

50°

C. or lower.

10. The method for manufacturing a semiconductor device, according to claim 8, wherein a temperature of the first heat treatment is higher than or equal to 250°

C. and lower than or equal to 650°

C.

11. The method for manufacturing a semiconductor device, according to claim 8, wherein a temperature of the second heat treatment is higher than or equal to 250°

C. and lower than or equal to 650°

C.

12. The method for manufacturing a semiconductor device, according to claim 8, wherein the first heat treatment and the second heat treatment are performed in a state where the oxide semiconductor layer is irradiated with light having a wavelength longer than or equal to 350 nm and shorter than or equal to 450 nm.

13. The method for manufacturing a semiconductor device, according to claim 8, wherein the first heat treatment and the second heat treatment under dry condition are repeated a plurality of times.

14. The method for manufacturing a semiconductor device, according to claim 8, wherein the oxide semiconductor layer is subjected to oxygen doping treatment after the step of decreasing the temperature of the oxide semiconductor layer.

15. The method for manufacturing a semiconductor device, according to claim 8, wherein an oxygen pressure in the first heat treatment is lower than an oxygen pressure in the second heat treatment.