Quality evaluation method for laminate having protective layer on surface of oxide semiconductor thin film and quality control method for oxide semiconductor thin film

Patent metadata

Field	Value
Publication number	US-10203367-B2
Application number	US-201515316801-A
Country	US
Kind code	B2
Filing date	Jun 22, 2015
Priority date	Jul 1, 2014
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

Provided is a method for simply evaluating defects caused in interface states in oxide semiconductor thin films and protective films in TFTs having protective films formed on the surface of oxide semiconductor thin films without actually measuring the characteristics of the same. This evaluation method evaluates defects caused in the interface states by measuring electron states in the oxide semiconductor thin film by a contact method or noncontact method. The defects caused in the interface states are any of the following: (1) threshold value voltage (V th ) when a positive bias is applied to the thin-film transistor, (2) difference in threshold value voltage (ΔV th ) before and after applying the positive bias to the thin-film transistor, and (3) threshold value during the first measurement when a plurality of measurements is made of the threshold value voltage when a positive bias is applied to the thin-film transistor.

First claim

The invention claimed is:

1. A quality evaluation method of a laminate including a protective film on a surface of an oxide semiconductor thin film,
wherein a defect caused by an interface state between the oxide semiconductor thin film and the protective film is evaluated by measuring a sheet resistance or a specific resistance of the oxide semiconductor thin film by a contact method or a noncontact method,
wherein the defect caused by the interface state is one of the following (1) to (3)
(1) threshold voltage V th of a thin film transistor,
(2) a difference in threshold voltage ΔV th between before and after application of a positive bias when the positive bias is applied to the thin film transistor, and
(3) a difference between a threshold voltage at first measurement and a threshold voltage after multiple times of measurement when the threshold voltage of the thin film transistor is measured multiple times.

2. The evaluation method according to claim 1 , wherein the oxide semiconductor thin film contains at least one element selected from the group consisting of In, Ga, Zn, and Sn.

3. The evaluation method according to claim 1 , wherein the oxide semiconductor thin film is provided on a surface of an insulating film formed on a substrate.

4. The evaluation method according to claim 1 , wherein a defect caused by the interface state is evaluated using a laminate having a first electrode and a second electrode in contact with two respective sides of the protective film.

5. The evaluation method according to claim 1 , wherein when the defect caused by the interface state is measured by the contact method, electrodes are provided on the surface of the oxide semiconductor thin film, and the defect is evaluated based on one of a measured current value and a measured voltage.

6. A quality evaluation method of a laminate for evaluating a thin film transistor, wherein when a defect caused by an interface state between the oxide semiconductor thin film and the protective film is measured by a noncontact method based on an electronic state of the oxide semiconductor thin film of the laminate comprising a protective film thereon, the measurement includes;
(i) irradiating the laminate with excitation light and a microwave, measuring maximum of a reflected wave of the microwave from the oxide semiconductor thin film, the maximum being varied by irradiation of the excitation light, and then stopping irradiation of the excitation light, and measuring temporal change in reflectance of the reflected wave of the microwave from the oxide semiconductor thin film after stopping irradiation of the excitation light, and
(ii) calculating a parameter corresponding to slow decay, the slow decay being, observed after stopping irradiation of the excitation light, from the temporal change in reflectance to evaluate the electronic state of the oxide semiconductor thin film.

7. The evaluation method according to claim 6 , wherein in (ii), a parameter corresponding to slow decay observed at 0.1 to 10 μs after stopping irradiation of the excitation light is calculated from the temporal change in reflectance to evaluate the electronic state of the oxide semiconductor thin film.

8. A quality control method of an oxide semiconductor thin film, wherein the evaluation method according to claim 6 is applied to at least one step of a semiconductor manufacturing process.

9. The evaluation method according to claim 6 , wherein the electronic state of the oxide semiconductor thin film is measured based on electrical resistivity of the oxide semiconductor thin film.

10. The evaluation method according to claim 6 , wherein the electrical resistivity is one of sheet resistance and specific resistance.

11. The evaluation method according to claim 6 , wherein the defect caused by the interface state is one of the following (1) to (3)
(1) a threshold voltage V th of a thin film transistor,
(2) a difference in threshold voltage ΔV th , between before and after application of a positive bias when the positive bias is applied to the thin film transistor, and
(3) a difference between a threshold voltage at first measurement and a threshold voltage after multiple times of measurement when the threshold voltage of the thin film transistor is measured multiple times.

12. The evaluation method according to claim 6 , wherein the oxide semiconductor thin film contains at least one element selected from the group consisting of In, Ga, Zn, and Sn.

13. The evaluation method according to claim 6 , wherein the oxide semiconductor thin film is provided on a surface of an insulating film formed on a substrate.

Assignees

• Kobe Steel Ltd

Inventors

• Hayashi Kazushi
• Miki Aya
• Kawakami Nobuyuki

Classifications

• H10P74/207

  Electrical properties, e.g. testing or measuring of resistance, deep levels or capacitance-voltage characteristics · CPC title

• H10P74/203 Primary

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10D64/011

  of electrodes ohmically coupled to a semiconductor · CPC title

• G01R1/06

  Measuring leads; Measuring probes (G01R19/145, G01R19/165 take precedence) · CPC title

• G01R31/2623

  for measuring break-down voltage therefor · CPC title