# US 12,183,641 B2 · Method for evaluating semiconductor substrate

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- Number: US 12,183,641 B2
- Document ID: US12183641B2
- Status: Granted
- Kind: B2
- Application number: 17/634,365
- Filed: 2020-06-04
- Published: 2022-09-08
- Granted: 2024-12-31
- Earliest claimed: 2019-09-03
- Assignees: Shin-Etsu Handotai Co., Ltd.
- Applicants: Shin-Etsu Handotai Co., Ltd.
- Inventors: Tsuyoshi Ohtsuki
- Web page: https://patentgrep.com/patent/US12183641B2

## CPC

- H10P 74/207: {Electrical properties, e.g. testing or measuring of resistance, deep levels or capacitance-voltage characteristics}
- H10F 39/011: {Manufacture or treatment of image sensors covered by group H10F39/12}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A method for evaluating electrical characteristics of a semiconductor substrate, the method including the steps of: forming a p-n junction on a surface of the semiconductor substrate; mounting the semiconductor substrate on a wafer chuck provided with an equipment for performing light irradiation on the surface of the semiconductor substrate and an equipment for measuring the quantity of the light for the irradiation; performing light irradiation on the surface of the semiconductor substrate for a predetermined time; and measuring an amount of carriers generated after the light irradiation of the p-n junction at least after turning off the light irradiation. This provides a method for evaluating a semiconductor substrate that allows the same evaluation in a wafer state as when an actual solid-state image sensor has been formed without producing a device by using process equipment when evaluating characteristics corresponding to residual image characteristics of a wafer.

## Claims

### Claim 1

A method for evaluating electrical characteristics of a semiconductor substrate, the method comprising the steps of:
forming a p-n junction on a surface of the semiconductor substrate;
mounting the semiconductor substrate on a wafer chuck provided with an equipment for performing light irradiation on the surface of the semiconductor substrate and an equipment for measuring the quantity of the light for the irradiation;
performing light irradiation on the surface of the semiconductor substrate for a predetermined time; and
measuring an amount of carriers generated after the light irradiation of the p-n junction at least after turning off the light irradiation, wherein
an amount of carriers generated during the light irradiation of the p-n junction is measured in the step of performing light irradiation, and
the amount of carriers generated during the light irradiation and the amount of carriers generated after the light irradiation are measured with a carrier measuring probe that is provided separately from the equipment for performing light irradiation and the equipment for measuring the quantity of the light for the irradiation.

### Claim 2 (depends on 1)

The method for evaluating a semiconductor substrate according to claim 1, wherein the carrier measuring probe is a non-contact Kelvin probe.

### Claim 3 (depends on 2)

The method for evaluating a semiconductor substrate according to claim 2, wherein the semiconductor substrate is subjected to a heat treatment in advance after the step of forming the p-n junction and before the step of mounting the semiconductor substrate.

### Claim 4 (depends on 2)

The method for evaluating a semiconductor substrate according to claim 2, wherein a semiconductor substrate for a solid-state image sensor is used as the semiconductor substrate, and residual image characteristics of the solid-state image sensor are evaluated from a ratio of the amount of carriers generated after the light irradiation to the amount of carriers generated during the light irradiation.

### Claim 5 (depends on 1)

The method for evaluating a semiconductor substrate according to claim 1, wherein the carrier measuring probe is a mercury probe.

### Claim 6 (depends on 5)

The method for evaluating a semiconductor substrate according to claim 5, wherein the semiconductor substrate is subjected to a heat treatment in advance after the step of forming the p-n junction and before the step of mounting the semiconductor substrate.

### Claim 7 (depends on 5)

The method for evaluating a semiconductor substrate according to claim 5, wherein a semiconductor substrate for a solid-state image sensor is used as the semiconductor substrate, and residual image characteristics of the solid-state image sensor are evaluated from a ratio of the amount of carriers generated after the light irradiation to the amount of carriers generated during the light irradiation.

### Claim 8 (depends on 1)

The method for evaluating a semiconductor substrate according to claim 1, wherein the semiconductor substrate is subjected to a heat treatment in advance after the step of forming the p-n junction and before the step of mounting the semiconductor substrate.

### Claim 9 (depends on 1)

The method for evaluating a semiconductor substrate according to claim 1, wherein a semiconductor substrate for a solid-state image sensor is used as the semiconductor substrate, and residual image characteristics of the solid-state image sensor are evaluated from a ratio of the amount of carriers generated after the light irradiation to the amount of carriers generated during the light irradiation.