Fast sample height, AOI and POI alignment in mapping ellipsometer or the like

• US 8,436,994 B2
• Filed: 01/15/2011
• Issued: 05/07/2013
• Est. Priority Date: 03/21/2000
• Status: Expired due to Term

• Current Assignee: J.A. Woollam Co., Inc.
• Original Assignee: J.A. Woollam Co., Inc.
• Inventors: Liphardt, Martin M., Hale, Jeffrey S., He, Ping, Pfeiffer, Galen L.
• Primary Examiner(s): LAUCHMAN, LAYLA G
• Application Number:
  US12/930,762
• Publication Number:
  US 20110109906A1
• Time in Patent Office: 843 Days
• Field of Search: 356/364, 356/399
• US Class Current: 356/364
• CPC Class Codes: G01N 2021/151 Gas blown
• CPC Class Codes: G01N 2021/212 Arrangement with total internal reflection
• CPC Class Codes: G01N 2021/213 Spectrometric ellipsometry
• CPC Class Codes: G01N 2021/214 Variangle incidence arrangement
• CPC Class Codes: G01N 21/01 Arrangements or apparatus for facilitating the optical investigation
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G01N 21/211 Ellipsometry optical thickness measurement G01B11/06
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 2201/021 Special mounting in general
• CPC Class Codes: G01N 2201/0693 Battery powered circuitry

Abstract

A sample investigation system (ES) in functional combination with an alignment system (AS), and methodology of enabling calibration and very fast, (eg. seconds), sample height, angle-of-incidence and plane-of-incidence adjustments, with application in mapping ellipsometer or the like systems.

Claims

1. A sample alignment system (AS) in functional combination within a sample investigation system (ES) selected from the group consisting of:

ellipsometer;

polarimeter;

reflectometer;

spectrophotometer; and

Mueller Matrix measuring system;

said sample investigation system (ES) comprising;

a source (ELS) of a sample (SAM) investigation beam of electromagnetic radiation;

a stage (STG) for supporting a sample (SAM);

a data detector (DDET); and

means for adjusting the relative “

height”

positioning between said stage (STG) for supporting a sample (SAM) and, as a unit, said source (ELS) of a sample investigation beam of electromagnetic radiation and data detector (DDET);

as well as means for translating relative positioning of said sample (SAM) with respect to said source (ELS) of a sample investigation beam of electromagnetic radiation and said data detector (DDET), along two orthogonal axes, and means for adjusting the relative orientation of the sample investigation system (ES) with respect to said sample (SAM) to set the angle and plane of incidence of said sample (SAM) investigation beam of electromagnetic radiation with respect to a surface of said sample (SAM);

said sample investigation system (ES) optionally comprising at least one polarizer (P), analyzer (A), compensator (RC) and/or focusing means (CL1) (CL2) (CL3) (CL4) between said source (ELS) of a sample (SAM) investigation beam of electromagnetic radiation and said data detector (DDET);

such that in use a sample investigation beam of electromagnetic radiation from said source (ELS) thereof approaches said sample (SAM) at an oblique angle-of-incidence and reflects therefrom into said data detector (DDET); and

wherein said alignment system (AS) comprises;

an alignment source (ALS) of an alignment beam of electromagnetic radiation;

a first alignment beam focusing means (CLA1) for focusing an alignment beam of electromagnetic radiation provided from said source (ALS) thereof onto a sample (SAM) on said sample investigation system (ES) stage (STG) for supporting a sample (SAM);

a second alignment focusing means (CLA2) for focusing alignment beam electromagnetic radiation which reflects from said sample onto a two dimensional detector array (SCRN1); and

said two dimensional detector array (SCRN1);

said sample alignment system (AS) further comprising;

between said second alignment focusing means (CLA2) and said two dimensional detector array (SCRN1), a beam splitter (BS) which diverts a portion of the alignment beam electromagnetic radiation which reflects from said sample (SAM) to a secondary two dimensional detector array (SCRN2), and said secondary two dimensional detector array (SCRN2);

such that in use an alignment beam of electromagnetic radiation from said source (ALS) thereof is focused onto said sample (SAM) at an oblique angle-of-incidence and reflects therefrom and is focused onto said two dimensional detector array (SCRN1) with a portion thereof being directed to secondary two dimensional detector array (SCRN2) via beam splitter (BS);

said sample (SAM) investigation system (ES) and alignment system (AS) being mounted with respect to one another such that the sample investigation beam of electromagnetic radiation and said alignment beam of electromagnetic radiation impinge on said sample (SAM) at substantially the same location;

such that in use, while monitoring two dimensional detector array (SCRN1), causing an alignment beam of electromagnetic radiation from said source (ALS) thereof to be focused onto said sample (SAM) at an oblique angle-of-incidence, reflect therefrom and become focused onto said two dimensional detector array (SCRN1), adjusting the means for adjusting the relative “

height”

positioning between said stage (STG) for supporting a sample until the location at which the alignment beam arrives thereat is at an aligned position thereupon;

and

such that in use the means for adjusting the relative orientation of the sample investigation system (ES) with respect to said sample (SAM), to set the angle and plane of incidence of said beam with respect to a surface of said sample (SAM) until said alignment beam reflected from said sample (SAM) surface appears on the two dimensional detector array (SCRN2) an aligned position thereupon.

2. A sample alignment system as in claim 1, which further comprises at least one known standard sample (SSMP) positioned away from said stage (STG) for supporting a sample (SAM), such that in use the sample investigation system (ES) and sample alignment system (AS) are positioned so that electromagnetic beams from each are directed to intereact with said at least one known standard sample (SSMP) while data is acquired from at least the sample investigation system (ES), followed by using said data to calibrate said sample investigation system (ES).

3. A sample alignment system as in claim 1, which further comprises a door (D) which is applied to cover said at least one known standard sample (SSMP) when it is not in use, to prevent contamination thereof.

4. A method of investigating a plurality of locations on a sample comprising the steps of:

a) providing a sample alignment system (AS) in functional combination within a sample investigation system (ES) selected from the group consisting of;

ellipsometer;

polarimeter;

reflectometer;

spectrophotometer; and

Mueller Matrix measuring system;

said sample investigation system (ES) comprising;

a source (ELS) of a sample (SAM) investigation beam of electromagnetic radiation;

a stage (STG) for supporting a sample (SAM);

a data detector (DDET); and

means for adjusting the relative “

height”

positioning between said stage (STG) for supporting a sample (SAM) and, as a unit, said source (ELS) of a sample investigation beam of electromagnetic radiation and data detector (DDET);

as well as means for translating relative positioning of said sample (SAM) with respect to said source (ELS) of a sample investigation beam of electromagnetic radiation and said data detector (DDET), along two orthogonal axes, and means for adjusting the relative orientation of the sample investigation system (ES) with respect to said sample (SAM) to set the angle and plane of incidence of said sample (SAM) investigation beam of electromagnetic radiation with respect to a surface of said sample (SAM);

said sample investigation system (ES) optionally comprising at least one polarizer (P), analyzer (A), compensator (RC) and/or focusing means (CL1) (CL2) (CL3) (CL4) between said source (ELS) of a sample (SAM) investigation beam of electromagnetic radiation and said data detector (DDET);

such that in use a sample investigation beam of electromagnetic radiation from said source (ELS) thereof approaches said sample (SAM) at an oblique angle-of-incidence and reflects therefrom into said data detector (DDET); and

wherein said alignment system (AS) comprises;

an alignment source (ALS) of an alignment beam of electromagnetic radiation;

a first alignment beam focusing means (CLA1) for focusing an alignment beam of electromagnetic radiation provided from said source (ALS) thereof onto a sample (SAM) on said sample investigation system (ES) stage (STG) for supporting a sample (SAM);

a second alignment focusing means (CLA2) for focusing alignment beam electromagnetic radiation which reflects from said sample onto a two dimensional detector array (SCRN1); and

said two dimensional detector array (SCRN1);

said sample alignment system (AS) further comprising;

between said second alignment focusing means (CLA2) and said two dimensional detector array (SCRN1), a beam splitter (BS) which diverts a portion of the alignment beam electromagnetic radiation which reflects from said sample (SAM) to a secondary two dimensional detector array (SCRN2), and said secondary two dimensional detector array (SCRN2);

such that in use an alignment beam of electromagnetic radiation from said source (ALS) thereof is focused onto said sample (SAM) at an oblique angle-of-incidence and reflects therefrom and is focused onto said two dimensional detector array (SCRN1) with a portion thereof being directed to secondary two dimensional detector array (SCRN2) via beam splitter (BS);

said alignment system (AS) further comprising at least one known standard sample (SSMP) positioned away from said stage (STG) for supporting a sample (SAM);

said sample (SAM) investigation system (ES) and alignment system (AS) being mounted with respect to one another such that the sample investigation beam of electromagnetic radiation and said alignment beam of electromagnetic radiation impinge on said sample (SAM) at substantially the same location;

such that in use, while monitoring two dimensional detector array (SCRN1), causing an alignment beam of electromagnetic radiation from said source (ALS) thereof to be focused onto said sample (SAM) at an oblique angle-of-incidence, reflect therefrom and become focused onto said two dimensional detector array (SCRN1), adjusting the means for adjusting the relative “

height”

positioning between said stage (STG) for supporting a sample until the location at which the alignment beam arrives thereat is at an aligned position thereupon;

and

such that in use the means for adjusting the relative orientation of the sample investigation system (ES) with respect to said sample (SAM), to set the angle and plane of incidence of said beam with respect to a surface of said sample (SAM) until said alignment beam reflected from said sample (SAM) surface appears on the two dimensional detector array (SCRN2) an aligned position thereupon;

b) causing the sample investigation system (ES) and sample alignment system (AS) to be positioned such that electromagnetic beams from each are directed to intereact with said at least one known standard sample (SSMP) while data is acquired from at least the sample investigation system (ES), followed by using said data to calibrate said sample investigation system (ES);

c) causing the sample investigation system (ES) and sample alignment system (AS) to be positioned such that electromagnetic beams from each are directed to intereact with a location on said sample (SAM) such that alignment beam of electromagnetic radiation from said source (ALS) of the sample alignment system is focused onto said sample (SAM) location at an oblique angle-of-incidence, reflects therefrom and is focused onto said two dimensional detector array (SCRN1) with a portion thereof being directed to secondary two dimensional detector array (SCRN2) via beam splitter (BS), followed by using information derived from screens (SCRN1) and (SCRN2), to adjust the distance between the sample (SAM) and said source (ELS) of a sample investigation beam of electromagnetic radiation and said data detector (DDET) as a unit, and to adjust the angle and plane of incidence of said sample (SAM) investigation beam of electromagnetic radiation with respect to a surface of said sample (SAM);

d) acquiring data from said data detector (DDET) and therefrom deriving sample (SAM) characterizing information therefrom; and

e) repeating steps c and d a plurality of times to provide (SAM) characterizing information at a plurality of locations thereupon.

5. A method of aligning a sample in an ellipsometer system, which ellipsometer system comprises:

a source of a beam of electromagnetic radiation;

a polarizer;

a stage for supporting a sample;

an analyzer;

a data detector;

means for adjusting the relative “

height”

positioning between said stage for supporting a sample and, as a unit, said source of a beam of electromagnetic radiation and data detector;

as well as means for translating relative positioning of said sample with respect to said source of an ellipsometer beam of electromagnetic radiation and said data detector, along two orthogonal axes, and optionally means for adjusting the relative orientation of the ellipsometer systems with respect to said sample to set the angle and plane of incidence of said ellipsometer beam with respect to a surface of said sample;

said ellipsometer system optionally comprising at least one compensator and/or focusing means between said source of a beam of electromagnetic radiation and said data detector;

such that in use a beam of electromagnetic radiation from said source thereof approaches said sample at an oblique angle-of-incidence and reflects therefrom into said data detector;

said method comprising the steps of;

a) functionally mounting a sample alignment system to said ellipsometer system, which sample alignment system comprises;

an alignment source of an alignment beam of electromagnetic radiation;

a first alignment beam focusing means for focusing an alignment beam of electromagnetic radiation provided from said source thereof onto a sample on said ellipsometer system stage for supporting a sample;

a second alignment focusing means for focusing alignment beam electromagnetic radiation which reflects from said sample onto a two dimensional detector array; and

said two dimensional detector array;

such that in use an alignment beam of electromagnetic radiation from said source thereof is focused onto said sample at an oblique angle-of-incidence and reflects therefrom and is focused onto said two dimensional detector array;

said sample alignment system optionally further comprising;

between said second alignment focusing means and said two dimensional detector array a beam splitter which diverts a portion of the alignment beam electromagnetic radiation which reflects from said sample to a secondary two dimensional detector array, and said secondary two dimensional detector array;

said ellipsometer and alignment system being mounted with respect to one another such that the ellipsometer beam of electromagnetic radiation and said alignment beam of electromagnetic radiation impinge on said sample at substantially the same location;

said method further comprising;

prior to step e, performing steps b and c at least once, in which steps b and c are;

b) while monitoring output intensity from said data detector causing a beam of electromagnetic radiation from said source thereof to approach said sample at an oblique angle-of-incidence and reflect therefrom into said data detector, adjusting the means for adjusting the relative “

height”

positioning between said stage for supporting a sample, and, as a unit, said source of a beam of electromagnetic radiation and data detector, until output from said data detector is of a desirable intensity; and

c) causing the source of an alignment beam of electromagnetic radiation from said source thereof to approach said sample at an oblique angle-of-incidence and reflect therefrom onto said two dimensional detector array and identifying the location on said two dimensional detector array as an aligned position;

said method further comprising performing steps d, e and f a plurality of times, wherein steps d, e and f are;

d) using said means for translating relative positioning of said sample with respect to, as a unit, said source of an ellipsometer beam of electromagnetic radiation and said data detector, along two orthogonal axes, causing relative translation of said sample along at least one of said orthogonal axes so that a new spot on said sample is investigated by said ellipsometer beam, and such that the location at which the alignment beam reflected from said sample surface in step c appears on the two dimensional detector array, possibly at a different location than said aligned position;

e) if necessary, adjusting the means for adjusting the relative “

height”

positioning between said stage for supporting a sample and, as a unit, said source of a beam of electromagnetic radiation and data detector, until said alignment beam reflected from said sample surface in step c appears on the two dimensional detector array at said aligned position;

f) with the above adjustment set, acquiring ellipsometric data from said data detector.

6. A method as in claim 5, in which the which the ellipsometer system further comprises at least one known standard sample (SSMP) positioned away from said stage (STG) for supporting a sample (SAM), such that in use the sample investigation system (ES) and sample alignment system (AS) are positioned so that electromagnetic beams from each are directed to intereact with said at least one known standard sample (SSMP) while data is acquired from at least the sample investigation system (ES), followed by using said data to calibrate said sample investigation system (ES).

7. A method as in claim 6, which further comprises a door (D) which is applied to cover said at least one known standard sample (SSMP) when it is not in use, to prevent contamination thereof.