US5835225A
Expired / Lapsed
US
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Surface properties detection by reflectance metrology
Assignee: Micron Technology Inc
•
Filing: 1997-07-14
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Granted: 1998-11-10
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Expires: 2017-07-14
Abstract
Abstract Method and apparatus are used to determine surface properties. A reflectometer directs an electromagnetic radiation (EMR) source having a plurality of selected wavelengths to a surface of a semiconductor substrate having a known selected surface property. The quantity and variation of reflectance of EMR at each selected wavelength is measured, and a target wavelength therefrom is identified that has the highest variation of reflected EMR. EMR reflectance measurements are then made at the target wavelength on surfaces having unknown surface properties for comparison to that of the original surface. The magnitude of variation in the comparison, based upon a predetermined understanding of such variations, provide an analytical tool by which the surface is analyzed for the selected surface property. With the disclosed technique, reflectance can be used to determine characteristics of each of multiple layers that are deposited in-situ. The disclosed technique is also useful to identify both a pattern and a film on a surface, as a process end point detection tool, and in multiple points analysis on a surface using master and slave reflectometers.
Inventors
- 👤 Randhir P. S. Thakur
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:08
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/27; G01; G01K; G01K11/00; G01K11/12; G01K11/14; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70605; G03F7/70616; G05D23/1919; G05D23/20; G05D23/26; H; H10; H10P; H10P74/00; H10P74/20; H10P74/203
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
234 words
A method of measuring a selected surface property of a surface of a semiconductor substrate, the method comprising: directing electromagnetic radiation having a plurality of selected wavelengths to a surface of a test semiconductor substrate, where a selected surface property of the surface of the test semiconductor substrate is known; measuring the quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths that is reflected off the surface of the test semiconductor substrate; determining a target wavelength from among the plurality of selected wavelengths that has substantially the highest the change in the ratio of reflected electromagnetic radiation off the surface of the test semiconductor substrate divided by incident electromagnetic radiation to the surface of the test semiconductor substrate; directing electromagnetic radiation at the target wavelength to a surface of a production semiconductor substrate for which the selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is reflected off the surface of the production semiconductor substrate; and determining the selected surface property for the surface of the production semiconductor substrate when the numerical difference between the measured quantity of electromagnetic radiation at the target wavelength that is reflected off the surface of the test semiconductor substrate and the measured quantity of electromagnetic radiation at the target wavelength that is reflected off the surface of the production semiconductor substrate is within a selected numerical range.
Claim 2
Independent Claim
234 words
A method of measuring a selected surface property of a surface of a semiconductor substrate, the method comprising: directing electromagnetic radiation having a plurality of selected wavelengths to a surface of a test semiconductor substrate, where a selected surface property of the surface of the test semiconductor substrate is known; measuring the quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths that is reflected off the surface of the test semiconductor substrate; determining a target wavelength from among the plurality of selected wavelengths that has substantially the highest the change in the ratio of reflected electromagnetic radiation off the surface of the test semiconductor substrate divided by incident electromagnetic radiation to the surface of the test semiconductor substrate; directing electromagnetic radiation at the target wavelength to a surface of a production semiconductor substrate for which the selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is reflected off the surface of the production semiconductor substrate; and determining the selected surface property for the surface of the production semiconductor substrate when the numerical difference between the measured quantity of electromagnetic radiation at the target wavelength that is reflected off the surface of the test semiconductor substrate and the measured quantity of electromagnetic radiation at the target wavelength that is reflected off the surface of the production semiconductor substrate is within a selected numerical range.
Claim 3
Dependent Claim
34 words
The method as defined in claim 1, wherein the selected surface property for the surface of the production semiconductor substrate is the thickness of a film beneath the surface of the production semiconductor substrate.
Claim 4
Dependent Claim
35 words
The method as defined in claim 1, wherein the selected surface property for the surface of the production semiconductor substrate is the material of which the surface of the production semiconductor substrate is substantially composed.
Claim 5
Dependent Claim
39 words
The method as defined in claim 1, wherein the selected surface property for the surface of the production semiconductor substrate is a grain size of the material of which the surface of the production semiconductor substrate is substantially composed.
Claim 6
Dependent Claim
55 words
The method as defined in claim 1, where the electromagnetic radiation directed at the target wavelength to the surface of the production semiconductor substrate is an electromagnetic radiation beam that irradiates an area on the surface of the production semiconductor substrate that has a diameter within range from about 0.005 microns to about 0.018 microns.
Claim 7
Independent Claim
376 words
A method of measuring a selected surface property of a surface of a semiconductor substrate, the method comprising: directing electromagnetic radiation having a plurality of selected wavelengths from each of a plurality of slave reflectometers to a respect slave area on a surface of a test semiconductor substrate, where a selected surface property of the surface of the test semiconductor substrate is known; measuring the quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths that is reflected off the respective slave areas of the surface of the test semiconductor substrate from each of the plurality of slave reflectometers, each said slave reflectometers communicating the respective measured quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths to as signal data to a master data channel; receiving said signal data from the master data channel communicated by said plurality of slave reflectometers, and for each of said slave areas: determining a target wavelength from among the plurality of selected wavelengths that has substantially the highest the change in the ratio of reflected electromagnetic radiation off the slave area of surface of the test semiconductor substrate divided by incident electromagnetic radiation to the slave area of the surface of the test semiconductor substrate; directing electromagnetic radiation at the target wavelength for each respective slave reflectometer to a respective slave area of a surface of a production semiconductor substrate for which the selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is reflected off the respective slave area of the surface of the production semiconductor substrate from the respective slave reflectometer of the plurality of slave reflectometers, each said slave reflectometers communicating the respective measured quantity of reflected electromagnetic radiation at the target wavelength for each respective slave area as signal data to a master data channel; receiving said signal data from the master data channel communicated by said plurality of slave reflectometers, and determining with the selected surface property for each said slave areas of the surface of the production semiconductor substrate when the numerical difference between a selected target amount and the signal data from the master data channel communicated by said plurality of slave reflectometers is within a selected master numerical range.
Claim 8
Independent Claim
376 words
A method of measuring a selected surface property of a surface of a semiconductor substrate, the method comprising: directing electromagnetic radiation having a plurality of selected wavelengths from each of a plurality of slave reflectometers to a respect slave area on a surface of a test semiconductor substrate, where a selected surface property of the surface of the test semiconductor substrate is known; measuring the quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths that is reflected off the respective slave areas of the surface of the test semiconductor substrate from each of the plurality of slave reflectometers, each said slave reflectometers communicating the respective measured quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths to as signal data to a master data channel; receiving said signal data from the master data channel communicated by said plurality of slave reflectometers, and for each of said slave areas: determining a target wavelength from among the plurality of selected wavelengths that has substantially the highest the change in the ratio of reflected electromagnetic radiation off the slave area of surface of the test semiconductor substrate divided by incident electromagnetic radiation to the slave area of the surface of the test semiconductor substrate; directing electromagnetic radiation at the target wavelength for each respective slave reflectometer to a respective slave area of a surface of a production semiconductor substrate for which the selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is reflected off the respective slave area of the surface of the production semiconductor substrate from the respective slave reflectometer of the plurality of slave reflectometers, each said slave reflectometers communicating the respective measured quantity of reflected electromagnetic radiation at the target wavelength for each respective slave area as signal data to a master data channel; receiving said signal data from the master data channel communicated by said plurality of slave reflectometers, and determining with the selected surface property for each said slave areas of the surface of the production semiconductor substrate when the numerical difference between a selected target amount and the signal data from the master data channel communicated by said plurality of slave reflectometers is within a selected master numerical range.
Claim 9
Dependent Claim
41 words
The method as defined in claim 6, wherein the selected surface property for the surface of both the test and production semiconductor substrates is the thickness of a film, respectively, beneath the surface of both the test and production semiconductor substrates.
Claim 10
Dependent Claim
42 words
The method as defined in claim 6, wherein the selected surface property for the surface of both the test and production semiconductor substrates is the material of which, respectively, the surface of both the test and production semiconductor substrates is substantially composed.
Claim 11
Dependent Claim
40 words
The method as defined in claim 6, wherein at least one of said plurality of slave reflectometers produces an electromagnetic radiation beam that irradiates an area having a diameter within a range from about 0.005 microns to about 0.018 microns.
Claim 12
Independent Claim
159 words
An apparatus for determining a selected surface property of a surface on a semiconductor substrate, said apparatus comprising: a plurality of slave reflectometers for each performing a slave reflectometer process comprising: directing electromagnetic radiation at a target wavelength to a slave area on the surface of the semiconductor substrate for which a selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is reflected off the slave area on the surface of the semiconductor substrate, and communicating same as signal data to a master data channel; and determining the selected surface property for each of the slave areas on the surface of the semiconductor substrate from said signal data from the master data channel communicated by said plurality of slave reflectometers when the numerical difference between a selected target amount and the signal data from the master data channel communicated by said plurality of slave reflectometers is within a selected master numerical range.
Claim 13
Independent Claim
159 words
An apparatus for determining a selected surface property of a surface on a semiconductor substrate, said apparatus comprising: a plurality of slave reflectometers for each performing a slave reflectometer process comprising: directing electromagnetic radiation at a target wavelength to a slave area on the surface of the semiconductor substrate for which a selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is reflected off the slave area on the surface of the semiconductor substrate, and communicating same as signal data to a master data channel; and determining the selected surface property for each of the slave areas on the surface of the semiconductor substrate from said signal data from the master data channel communicated by said plurality of slave reflectometers when the numerical difference between a selected target amount and the signal data from the master data channel communicated by said plurality of slave reflectometers is within a selected master numerical range.
Claim 14
Dependent Claim
32 words
The apparatus as defined in claim 10, wherein the selected surface property for the surface of the semiconductor substrate is the thickness of a film beneath the surface of the semiconductor substrate.
Claim 15
Dependent Claim
33 words
The apparatus as defined in claim 10, wherein the selected surface property for the surface of the semiconductor substrate is the material of which the surface of the semiconductor substrate is substantially composed.
Claim 16
Dependent Claim
47 words
The apparatus as defined in claim 10, wherein at least one of said plurality of slave reflectometers produces an electromagnetic radiation beam that irradiates an area on the surface of the semiconductor substrate that has a diameter within range from about 0.005 microns to about 0.018 microns.
Claim 17
Independent Claim
230 words
A method of forming a contact plug comprising: forming an electrically conductive material on a semiconductor substrate, said electrically conductive material being formed in between and adjacent to a pair of raised structures on the semiconductor substrate; directing electromagnetic radiation at a target first wavelength towards an area adjacent to the electrically active area where a top surface of each of the raised structures is desired to be situated; measuring the quantity and variation thereof of electromagnetic radiation at the target first wavelength that is reflected, determining the selected first surface property for a surface from which the electromagnetic radiation at the target first wavelength was reflected when the numerical difference between a target first amount and the quantity of electromagnetic radiation at the target first wavelength that was reflected is within a selected first numerical range; directing electromagnetic radiation at a target second wavelength towards the electrically active area where a top surface of the electrically conductive material is desired to be situated; measuring the quantity of electromagnetic radiation at the second target wavelength that is reflected; and determining the selected second surface property for a surface from which the electromagnetic radiation at the second target wavelength was reflected when the numerical difference between a target second amount and the quantity of electromagnetic radiation at the target second wavelength that was reflected is within a selected second numerical range.
Claim 18
Independent Claim
230 words
A method of forming a contact plug comprising: forming an electrically conductive material on a semiconductor substrate, said electrically conductive material being formed in between and adjacent to a pair of raised structures on the semiconductor substrate; directing electromagnetic radiation at a target first wavelength towards an area adjacent to the electrically active area where a top surface of each of the raised structures is desired to be situated; measuring the quantity and variation thereof of electromagnetic radiation at the target first wavelength that is reflected, determining the selected first surface property for a surface from which the electromagnetic radiation at the target first wavelength was reflected when the numerical difference between a target first amount and the quantity of electromagnetic radiation at the target first wavelength that was reflected is within a selected first numerical range; directing electromagnetic radiation at a target second wavelength towards the electrically active area where a top surface of the electrically conductive material is desired to be situated; measuring the quantity of electromagnetic radiation at the second target wavelength that is reflected; and determining the selected second surface property for a surface from which the electromagnetic radiation at the second target wavelength was reflected when the numerical difference between a target second amount and the quantity of electromagnetic radiation at the target second wavelength that was reflected is within a selected second numerical range.
Claim 19
Dependent Claim
47 words
The method as defined in claim 14, wherein the selected first and second surface properties are, respectively, the material of which the top surface of the raised structures are substantially composed, and the material of which the top surface of the electrically conductive material is substantially composed.
Claim 20
Dependent Claim
66 words
The method as defined in claim 15, wherein the material of which the top surface of the raised structures are substantially composed is selected from a group consisting of silicon dioxide and silicon nitride, and wherein the material of which the top surface of the electrically conductive material is substantially composed is selected from a group consisting of polysilicon, hemispherical grain polysilicon, and spherical grain polysilicon.
Claim 21
Dependent Claim
31 words
The method as defined in claim 14, wherein the selected second surface property for the top surface of the electrically conductive material is a grain size of the electrically conductive material.
Claim 22
Dependent Claim
26 words
The method as defined in claim 14, wherein each said raised structures is an electrode and the electrically conductive material is formed upon said raised structures.
Claim 23
Dependent Claim
47 words
The method as defined in claim 15, wherein each said raised structures is adjacent to an electrically active area and is an insulated transistor gate stack, and the electrically conductive material is a contact plug that is situated on the electrically active area within the semiconductor substrate.
Claim 24
Dependent Claim
21 words
The method as defined in claim 14, wherein the selected second surface properties is the thickness of the electrically conductive material.
Claim 25
Dependent Claim
46 words
The method as defined in claim 14, where the electromagnetic radiation directed at at least one of the first and second target wavelengths is an electromagnetic radiation beam that irradiates an area that has a diameter within range from about 0.005 microns to about 0.018 microns.
Claim 26
Independent Claim
234 words
A method of measuring a selected surface property of a surface of a semiconductor substrate, the method comprising: directing electromagnetic radiation having a plurality of selected wavelengths to a surface of a test semiconductor substrate, where a selected surface property of the surface of the test semiconductor substrate is known; measuring the quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths that is refracted from the surface of the test semiconductor substrate; determining a target wavelength from among the plurality of selected wavelengths that has substantially the highest the change in the ratio of refracted electromagnetic radiation off the surface of the test semiconductor substrate divided by incident electromagnetic radiation to the surface of the test semiconductor substrate; directing electromagnetic radiation at the target wavelength to a surface of a production semiconductor substrate for which the selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is refracted from the surface of the production semiconductor substrate; and determining the selected surface property for the surface of the production semiconductor substrate when the numerical difference between the measured quantity of electromagnetic radiation at the target wavelength that is refracted from the surface of the test semiconductor substrate and the measured quantity of electromagnetic radiation at the target wavelength that is refracted from the surface of the production semiconductor substrate is within a selected numerical range.
Claim 27
Independent Claim
234 words
A method of measuring a selected surface property of a surface of a semiconductor substrate, the method comprising: directing electromagnetic radiation having a plurality of selected wavelengths to a surface of a test semiconductor substrate, where a selected surface property of the surface of the test semiconductor substrate is known; measuring the quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths that is refracted from the surface of the test semiconductor substrate; determining a target wavelength from among the plurality of selected wavelengths that has substantially the highest the change in the ratio of refracted electromagnetic radiation off the surface of the test semiconductor substrate divided by incident electromagnetic radiation to the surface of the test semiconductor substrate; directing electromagnetic radiation at the target wavelength to a surface of a production semiconductor substrate for which the selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is refracted from the surface of the production semiconductor substrate; and determining the selected surface property for the surface of the production semiconductor substrate when the numerical difference between the measured quantity of electromagnetic radiation at the target wavelength that is refracted from the surface of the test semiconductor substrate and the measured quantity of electromagnetic radiation at the target wavelength that is refracted from the surface of the production semiconductor substrate is within a selected numerical range.
Claim 28
Independent Claim
243 words
A method of measuring a selected surface property of a surface of a semiconductor substrate, the method comprising: directing electromagnetic radiation having a plurality of selected wavelengths to a surface of a test semiconductor substrate, where a selected surface property of the surface of the test semiconductor substrate is known; measuring the quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths that is reflected or refracted from the surface of the test semiconductor substrate; determining a target wavelength from among the plurality of selected wavelengths that has substantially the highest the change in the ratio of reflected or refracted electromagnetic radiation off the surface of the test semiconductor substrate divided by incident electromagnetic radiation to the surface of the test semiconductor substrate; directing electromagnetic radiation at the target wavelength to a surface of a production semiconductor substrate for which the selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is reflected or refracted from the surface of the production semiconductor substrate; and determining the selected surface property for the surface of the production semiconductor substrate when the numerical difference between the measured quantity of electromagnetic radiation at the target wavelength that is reflected or refracted from the surface of the test semiconductor substrate and the measured quantity of electromagnetic radiation at the target wavelength that is reflected or refracted from the surface of the semiconductor substrate is within a selected numerical range.
Claim 29
Independent Claim
243 words
A method of measuring a selected surface property of a surface of a semiconductor substrate, the method comprising: directing electromagnetic radiation having a plurality of selected wavelengths to a surface of a test semiconductor substrate, where a selected surface property of the surface of the test semiconductor substrate is known; measuring the quantity and variation thereof of electromagnetic radiation at each of the selected wavelengths that is reflected or refracted from the surface of the test semiconductor substrate; determining a target wavelength from among the plurality of selected wavelengths that has substantially the highest the change in the ratio of reflected or refracted electromagnetic radiation off the surface of the test semiconductor substrate divided by incident electromagnetic radiation to the surface of the test semiconductor substrate; directing electromagnetic radiation at the target wavelength to a surface of a production semiconductor substrate for which the selected surface property is unknown; measuring the quantity of electromagnetic radiation at the target wavelength that is reflected or refracted from the surface of the production semiconductor substrate; and determining the selected surface property for the surface of the production semiconductor substrate when the numerical difference between the measured quantity of electromagnetic radiation at the target wavelength that is reflected or refracted from the surface of the test semiconductor substrate and the measured quantity of electromagnetic radiation at the target wavelength that is reflected or refracted from the surface of the semiconductor substrate is within a selected numerical range.
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