# US 2014/0152336 A1 · Semiconductor Device and Method for Evaluating Semiconductor Device

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- Number: US 2014/0152336 A1
- Document ID: US20140152336A1
- Status: Published application
- Kind: A1
- Application number: 14/091,907
- Filed: 2013-11-27
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Applicants: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Toshinari Sasaki; Hiroshi Kanemura; Yasuharu Hosaka; Shuhei Yokoyama; Toshimitsu Obonai
- Web page: https://patentgrep.com/patent/US20140152336A1

## CPC

- H10D 30/6755: {Oxide semiconductors, e.g. zinc oxide, copper aluminium oxide or cadmium stannate}
- H10D 62/86: being Group II-VI materials, e.g. ZnO
- H10F 39/016: {of thin-film-based image sensors}
- H10F 39/198: {Contact-type image sensors [CIS]}
- G01R 31/2656: {using non-ionising electromagnetic radiation, e.g. optical radiation}
- G09G 3/006: {Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309)}
- G09G 3/3225: using an active matrix
- G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

A semiconductor layer with a low density of trap states is provided. A transistor with stable electrical characteristics is provided. A transistor having high field-effect mobility is provided. A semiconductor device including the transistor is provided. A method for evaluating a semiconductor layer is provided. A method for evaluating a transistor is provided. A method for evaluating a semiconductor device is provided. Provided is, for example, a semiconductor layer with a low defect density which can be used for a channel formation region of a transistor, a transistor including a semiconductor layer with a low defect density in a channel formation region, or a semiconductor device including the transistor.

## Claims

### Claim 1

An evaluation method for a semiconductor device comprising the steps of:
starting to apply a voltage between a first electrode and a second electrode at a time T0 so that a current flows in an oxide semiconductor layer electrically connected to the first electrode and the second electrode;
irradiating the oxide semiconductor layer with light having an energy higher than an energy gap of the oxide semiconductor layer, wherein the irradiating step starts at a time T1 and stops at a time T2;
comparing a value of a current flowing between the first electrode and the second electrode at a time T3 with a maximum value of a current flowing between the first electrode and the second electrode between the time T1 and the time T2; and
comparing a value of a current flowing between the first electrode and the second electrode at a time T4 with the maximum value of the current flowing between the first electrode and the second electrode between the time T1 and the time T2; and
stopping to apply the voltage between the first electrode and the second at time T5,
wherein the time T1 is after the time T0,
wherein the time T3 is after a period of greater than or equal to 1 second and less than or equal to 15 seconds from the time T1 and before the time T2,
wherein the time T4 is after a period of greater than or equal to 1 second and less than or equal to 15 seconds from the time T2, and
wherein the time T5 is after the time T4.

### Claim 2 (depends on 1)

The evaluation method for a semiconductor device according to claim 1,
wherein the time T3 is five seconds after the time T1, and
wherein the time T4 is five seconds after the time T2.

### Claim 3 (depends on 1)

The evaluation method for a semiconductor device according to claim 1,
wherein the time T2 is after a period of greater than or equal to 100 seconds and less than or equal to 300 seconds from the time T1.

### Claim 4 (depends on 1)

The evaluation method for a semiconductor device according to claim 1,
wherein a temperature around the semiconductor device is kept within a range of 20° C. to 25° C. from the time T0 until the time T5.

### Claim 5 (depends on 1)

The evaluation method for a semiconductor device according to claim 1, further comprising the step of judging whether the value of the current flowing between the first electrode and the second electrode at the time T3 is greater than or equal to 70% and less than 100% of the maximum value of the current flowing between the first electrode and the second electrode between the time T1 and the time T2.

### Claim 6 (depends on 1)

The evaluation method for a semiconductor device according to claim 1, further comprising the step of judging whether the value of the current flowing between the first electrode and the second electrode at the time T4 is greater than or equal to 5% and less than 100% of the maximum value of the current flowing between the first electrode and the second electrode between the time T1 and the time T2.

### Claim 7 (depends on 1)

The evaluation method for a semiconductor device according to claim 1, further comprising the steps of:
judging whether the value of the current flowing between the first electrode and the second electrode at the time T3 is greater than or equal to 70% and less than 100% of the maximum value of the current flowing between the first electrode and the second electrode between the time T1 and the time T2; and
judging whether the value of the current flowing between the first electrode and the second electrode at the time T4 is greater than or equal to 5% and less than 100% of the maximum value of the current flowing between the first electrode and the second electrode between the time T1 and the time T2.

### Claim 8 (depends on 1)

The evaluation method for a semiconductor device according to claim 1,
wherein the light has a peak intensity in a wavelength range of 340 nm to 360 nm.

### Claim 9 (depends on 1)

The evaluation method for a semiconductor device according to claim 1,
wherein the light has an intensity of 3 mW/cm2.

### Claim 10 (depends on 1)

The evaluation method for a semiconductor device according to claim 1,
wherein the oxide semiconductor layer includes a first oxide semiconductor layer and a second oxide semiconductor layer over the first oxide semiconductor layer.

### Claim 11

A semiconductor device comprising:
a transistor including an oxide semiconductor layer in a channel formation region, the oxide semiconductor layer being electrically connected to a first electrode and a second electrode,
wherein, while a voltage is applied between the first electrode and the second electrode, the oxide semiconductor layer begins to be irradiated with light having a peak intensity in a wavelength range of 340 nm to 360 nm and an intensity of 3 mW/cm2 at a temperature of 25° C. at a time T0 and irradiation is stopped at a time T1,
wherein a value of a current flowing between the first electrode and the second electrode at a time T2 is greater than or equal to 70% and less than 100% of a maximum value of a current flowing between the first electrode and the second electrode between the time T0 and the time T1,
wherein a value of a current flowing between the first electrode and the second electrode at a time T3 is greater than or equal to 5% and less than 100% of the maximum value of the current flowing between the first electrode and the second electrode between the time T0 and the time T1,
wherein the time T2 is after a period of greater than or equal to 1 second and less than or equal to 15 seconds from the time T0 and before the time T1, and
wherein the time T3 is after a period of greater than or equal to 1 second and less than or equal to 15 seconds from the time T1.

### Claim 12 (depends on 11)

The semiconductor device according to claim 11,
wherein the time T2 is five seconds after the time T0, and
wherein the time T3 is five seconds after the time T1.

### Claim 13 (depends on 11)

The semiconductor device according to claim 11,
wherein the time T1 is after a period of greater than or equal to 100 seconds and less than or equal to 300 seconds from the time T0.

### Claim 14 (depends on 11)

The semiconductor device according to claim 11,
wherein the oxide semiconductor layer includes a first oxide semiconductor layer and a second oxide semiconductor layer over the first oxide semiconductor layer, and
wherein the second oxide semiconductor layer has a lower electron affinity than an electron affinity of the first oxide semiconductor layer.

### Claim 15 (depends on 11)

The semiconductor device according to claim 11, further comprising an insulating film in contact with the oxide semiconductor layer and a third electrode overlapping with the oxide semiconductor layer with the insulating film interposed therebetween.

### Claim 16 (depends on 11)

The semiconductor device according to claim 11,
wherein the oxide semiconductor layer comprises at least indium.

### Claim 17

An evaluation method for a semiconductor device comprising the steps of:
starting to apply a voltage between a first electrode and a second electrode at a time T0 so that a current flows in an oxide semiconductor layer electrically connected to the first electrode and the second electrode;
irradiating the oxide semiconductor layer with light having an energy higher than an energy gap of the oxide semiconductor layer, wherein the irradiating step starts at a time T1 and stops at a time T2;
comparing a value of a current flowing between the first electrode and the second electrode at a time T3 with a maximum value of a current flowing between the first electrode and the second electrode between the time T1 and the time T2; and
comparing a value of a current flowing between the first electrode and the second electrode at a time T4 with the maximum value of the current flowing between the first electrode and the second electrode between the time T1 and the time T2; and
stopping to apply the voltage between the first electrode and the second at time T5,
wherein the time T1 is after the time T0,
wherein the time T3 is between the time T1 and the time T2,
wherein the time T4 is after a period of greater than or equal to 1 second and less than or equal to 15 seconds from the time T2, and
wherein the time T5 is after the time T4.