# US 10,871,515 B2 · Method of measuring Fe concentration in p-type silicon wafer

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,871,515 B2
- Document ID: US10871515B2
- Status: Granted
- Kind: B2
- Application number: 15/765,792
- Filed: 2016-09-05
- Published: 2018-10-04
- Granted: 2020-12-22
- Earliest claimed: 2015-10-07
- Assignees: Sumco Corporation
- Applicants: Sumco Corporation
- Inventors: Shinya Fukushima; Masahiko Mizuta
- Web page: https://patentgrep.com/patent/US10871515B2

## CPC

- G01R 31/2648: {Characterising semiconductor materials (testing of materials or semi-finished products G01R31/2831; testing during manufacture H10P74/00)}
- G01R 31/2656: {using non-ionising electromagnetic radiation, e.g. optical radiation}
- H10P 74/207: {Electrical properties, e.g. testing or measuring of resistance, deep levels or capacitance-voltage characteristics}
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Provided is a method of measuring the Fe concentration in a p-type silicon wafer by the SPV method, by which the detection limit for the Fe concentration can be lowered, and the measurement can be performed in a short time. The measurement by the SPV method is performed in a measurement mode in which irradiation with a plurality of lights having mutually different wavelengths is performed during the same period under conditions where (i) Time Between Readings is 35 ms or more and 120 ms or less and Time Constant is 20 ms or more, or Time Between Readings is 10 ms or more and less than 35 ms and Time Constant is 100 ms or more, and (ii) Number of Readings is 12 times or less.

## Claims

### Claim 1

A method of measuring an iron concentration in a p-type silicon wafer, based on a measurement that uses a surface photovoltage method (SPV), the method of measuring comprising:
performing the measurement in a measurement mode in which the p-type silicon wafer is irradiated during a same period with a plurality of lights having mutually different wavelengths,
wherein the measurement is performed under the following conditions:
(i) a Time Between Readings is 35 ms or more and 120 ms or less and a Time Constant is 20 ms or more, or the Time Between Readings is 10 ms or more and less than 35 ms and the Time Constant is 100 ms or more, and
(ii) a Number of Readings is 12 times or less,
the Number of Readings being defined by a number of SPV signals acquired during one SPV measurement,
the Time Constant being defined by a time period in which each of the number of SPV signals is acquired, and
the Time Between Readings being defined by a time interval between points in time at which successive signals among the number of SPV signals are acquired.