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

• US 10,203,367 B2
• Filed: 06/22/2015
• Issued: 02/12/2019
• Est. Priority Date: 07/01/2014
• Status: Active Grant

• Current Assignee: Klaus Schmidt
• Original Assignee: Kobe Steel Limited
• Inventors: Hayashi, Kazushi, Miki, Aya, Kawakami, Nobuyuki
• Primary Examiner(s): Nguyen, Tung X
• Application Number:
  US15/316,801
• Publication Number:
  US 20170184660A1
• Time in Patent Office: 1,331 Days
• CPC Class Codes: G01R 1/06 Measuring leads; Measuring probes G01R19/145, G01R19/165 take precedence
• CPC Class Codes: G01R 31/2623 for measuring break-down voltage therefor
• CPC Class Codes: G01R 31/2656 using non-ionising electromagnetic radiation, e.g. optical radiation
• CPC Class Codes: G01R 31/27 Testing of devices without physical removal from the circuit of which they form part, e.g. compensating for effects surrounding elements testing printed circuit boards G01R31/2801
• CPC Class Codes: H01L 21/28 Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268 etching for patterning the electrodes H01L21/311, H01L21/3213; multistep manufacturing processes for data storage electrodes H01L29/4011
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14
• CPC Class Codes: H01L 22/14 for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
• 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 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00

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.

Claims

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 Δ

V_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 μ

s 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 Δ

V_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.