# US 10,502,687 B2 · Methods for inspecting semiconductor wafers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,687 B2 - Document ID: US10502687B2 - Status: Granted - Kind: B2 - Application number: 16/268,550 - Filed: 2019-02-06 - Published: 2019-06-13 - Granted: 2019-12-10 - Earliest claimed: 2012-07-06 - Assignees: Bt Imaging Pty Ltd - Applicants: Bt Imaging Pty Ltd - Inventors: Thorsten Trupke; Juergen Weber - Web page: https://patentgrep.com/patent/US10502687B2 ## CPC - G01N 21/6489: {Photoluminescence of semiconductors} - G01N 21/6456: {Spatial resolved fluorescence measurements; Imaging} - G01N 21/9501: {Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} - G01R 31/2656: {using non-ionising electromagnetic radiation, e.g. optical radiation} - G01N 2021/646: {Detecting fluorescent inhomogeneities at a position, e.g. for detecting defects} - G01N 2201/062: LED's - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract Methods and systems are presented for analysing semiconductor materials as they progress along a production line, using photoluminescence images acquired using line-scanning techniques. The photoluminescence images can be analysed to obtain spatially resolved information on one or more properties of said material, such as lateral charge carrier transport, defects and the presence of cracks. In one preferred embodiment the methods and systems are used to obtain series resistance images of silicon photovoltaic cells without making electrical contact with the sample cell. ## Claims ### Claim 1 A method for obtaining series resistance or carrier transport information across a semiconductor material selected from the group consisting of: a photovoltaic cell; a partially metallised photovoltaic cell precursor; a photovoltaic cell precursor having an emitter layer on a base; and a photovoltaic cell precursor having a selective emitter layer on a base, said method comprising the steps of: illuminating a first portion of said material with a first illumination from a light source suitable for generating a photoluminescence response from said material; detecting photoluminescence emitted from a second portion of said material with an image capture device; scanning said first and second portions across a substantial area of said material, said substantial area corresponding to an entire surface of said semiconductor material; and interrogating said image capture device while said first and second portions are being scanned across said substantial area to acquire an image of photoluminescence emitted from said substantial area, wherein an intensity of said first illumination is selected such that there is a significant lateral flow of photo-generated charge carriers out of said first portion, and wherein said method further comprises the step of interpreting said image to identify defects that impede carrier transport in said substantial area. ### Claim 2 (depends on 1) A method according to claim 1, wherein said first and second portions are scanned in a scanning direction across the substantial area of said material and wherein said second portion is wider than said first portion in the scanning direction. ### Claim 3 (depends on 1) A method according to claim 1, wherein the intensity of said first illumination is selected such that the lateral flow rate of photo-generated charge carriers out of said first portion is at least 10% of the photo-generation rate. ### Claim 4 (depends on 3) A method according to claim 3, wherein the intensity of said first illumination is selected such that the lateral flow rate of photo-generated charge carriers out of said first portion is at least 50% of the photo-generation rate. ### Claim 5 (depends on 4) A method according to claim 4, wherein the intensity of said first illumination is selected such that the lateral flow rate of photo-generated charge carriers out of said first portion is at least 80% of the photo-generation rate. ### Claim 6 (depends on 1) A method according to claim 1, wherein the scanning step comprises moving said material relative to said light source and said image capture device. ### Claim 7 (depends on 1) A method according to claim 1, wherein said method is applied in-line in a photovoltaic cell manufacturing process for quality control or process control purposes. ### Claim 8 (depends on 1) An article of manufacture comprising a non-transitory computer usable medium having a computer readable program code configured to implement the method according to claim 1. ### Claim 9 A system for obtaining series resistance or carrier transport information across a semiconductor material selected from the group consisting of: a photovoltaic cell; a partially metallised photovoltaic cell precursor; a photovoltaic cell precursor having an emitter layer on a base; and a photovoltaic cell precursor having a selective emitter layer on a base, said system comprising: a light source adapted to illuminate a first portion of said material with a first illumination suitable for generating a photoluminescence response from said material; an image capture device adapted to detect photoluminescence emitted from a second portion of said material; a mechanism for scanning said first and second portions across a substantial area of said material, said substantial area corresponding to an entire surface of said semiconductor material; and a computer programmed to interrogate said image capture device while said first and second portions are being scanned across said substantial area to acquire an image of photoluminescence emitted from said substantial area, wherein an intensity of said first illumination is selected such that there is a significant lateral flow of photo-generated charge carriers out of said first portion, and wherein said computer is programmed to interpret said image to identify defects that impede carrier transport in said substantial area. ### Claim 10 (depends on 9) A system according to claim 9, wherein said mechanism is configured to scan said first and second portions in a scanning direction across the substantial area of said material and wherein said second portion is wider than said first portion in the scanning direction. ### Claim 11 (depends on 9) A system according to claim 9, wherein the intensity of said first illumination is selected such that the lateral flow rate of photo-generated charge carriers out of said first portion is at least 10% of the photo-generation rate. ### Claim 12 (depends on 11) A system according to claim 11, wherein the intensity of said first illumination is selected such that the lateral flow rate of photo-generated charge carriers out of said first portion is at least 50% of the photo-generation rate. ### Claim 13 (depends on 12) A system according to claim 12, wherein the intensity of said first illumination is selected such that the lateral flow rate of photo-generated charge carriers out of said first portion is at least 80% of the photo-generation rate. ### Claim 14 (depends on 9) A system according to claim 9, wherein the scanning mechanism comprises a mechanism for moving said semiconductor material relative to said light source and said image capture device. ### Claim 15 (depends on 9) A system according to claim 9, wherein said image capture device comprises a line camera or a time delay integration camera. ### Claim 16 (depends on 9) A system according to claim 9, wherein the pixels within said image capture device comprise silicon, InGaAs or InGaAsP. ### Claim 17 (depends on 9) A system according to claim 9, wherein said image capture device comprises a silicon sensor in combination with an InGaAs or InGaAsP photocathode. ### Claim 18 (depends on 9) A system according to claim 9, when used in-line in a photovoltaic cell manufacturing process for quality control or process control purposes. ### Claim 19 (depends on 9) An article of manufacture comprising a non-transitory computer usable medium having a computer readable program code configured to operate the system according to claim 9.