Automated ellipsometer and the like systems

• US 7,505,134 B1
• Filed: 04/21/2006
• Issued: 03/17/2009
• Est. Priority Date: 01/16/2001
• Status: Expired due to Term

• Current Assignee: J.A. Woollam Co., Inc.
• Original Assignee: J.A. Woollam Co., Inc.
• Inventors: Liphardt, Martin M., He, Ping, Johs, Blaine D., Welch, James D., Woollam, John A., Goeden, Christopher A.
• Primary Examiner(s): Pham; Hoa Q
• Application Number:
  US11/408,679
• Time in Patent Office: 1,061 Days
• Field of Search: 356364-369, 250/225
• US Class Current: 356/369
• CPC Class Codes: G01N 2021/151 Gas blown
• CPC Class Codes: G01N 2021/212 Arrangement with total internal reflection
• CPC Class Codes: G01N 2021/214 Variangle incidence arrangement
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• 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

Systems and methodology for orienting the tip/tilt and vertical height of samples, preferably automated, as applied in ellipsometer and the like systems.

Claims

1. A method of aligning an ellipsometer system which comprises:

an ellipsometer source of a beam of electromagnetic radiation;

a stage for supporting a sample and having means for effecting tip/tilt and translation thereof;

a data detector of electromagnetic radiation;

said method comprising;

a) placing an alignment sample on said stage;

b) generally orienting said ellipsometer source of a beam of electromagnetic radiation so that it directs a beam of electromagnetic radiation onto a first location of said alignment sample at an oblique angle, which beam then reflects from said alignment sample and enters said data detector so that it provides an output signal;

performing steps;

c1) while monitoring the output signal from said data detector causing said stage to effect translation of said alignment sample so that said beam is directed to a second location thereon at said oblique angle, reflects therefrom and enters said data detector, followed by adjusting the tip/tilt of said stage;

c2) while monitoring the output signal from said data detector causing said stage to effect translation of said alignment sample so that said beam is directed to a third location thereon at said oblique angle, reflects therefrom and enters said data detector, followed by adjusting the tip/tilt of said stage, said third location being other than co-linear with said first and second locations;

c3) while monitoring the output signal from said data detector causing said stage to effect translation of said alignment sample so that said beam is directed to a said first location thereon at said oblique angle, reflects therefrom and enters said data detector, followed by adjusting the tip/tilt of said stage;

itteratively, in any functional order, until the output of the data detector is substantially the same in all said steps c1, c2 and c3;

with the result being that the stage is oriented in tip/tilt so that no matter from what location on said alignment sample said beam is caused to reflect, the output from said data detector remains substantially the same;

said method then optionally further comprising;

d) while monitoring the data detector output signal moving the location and orientation thereof until said output signal therefrom is substantially maximized.

2. A method as in claim 1 which further comprises itteratively repeating a step c4 along with steps c1, c2 and c3, said step c4 being selected from the group consisting of c4a and c4b:

c4a) while monitoring the output signals from the detector elements of said oblique beam monitoring multi-element alignment detector, causing said stage to effect translation of said sample so that said beam is directed to a forth, arbitrary, location thereon at said oblique angle, reflects therefrom and enters said multi-element alignment detector, followed by adjusting the tip/tilt of said stage;

c4b) while monitoring the output signals from the detector elements of said oblique beam monitoring multi-element alignment detector, causing said stage to effect translation of said sample so that said beam is directed to a forth, location thereon at said oblique angle, reflects therefrom and enters said multi-element alignment detector, followed by adjusting the tip/tilt of said stage, said forth location being oriented so as to form a square shape with the first three locations.

3. A method as in claim 2 wherein said ellipsometer system further comprises a focusing lens between said ellipsometer source of a beam of electromagnetic radiation and said stage.

4. A method as in claim 2 which further comprises:

e) providing and positioning a source of a beam of electromagnetic radiation derived from a selection from the group consisting of;

said ellipsometer source of a beam of electromagnetic radiation; and

an alternative source of a beam of electromagnetic radiation;

such that it provides an alignment beam of electromagnetic radiation which proceeds substantially along an incident locus which is normal to said alignment sample, which then reflects from said alignment sample and returns substantially back along the incident locus; and

providing a normal beam monitoring multi-detector element alignment detector so that it monitors said reflected alignment beam of electromagnetic radiation, and positioning it such that a selection from the group consisting of;

each detector element of said normal beam monitoring multi-detector element alignment detector provides no output signal; and

each detector element of said normal beam monitoring multi-detector element alignment detector provides reference output signals;

results when said reflected alignment beam of electromagnetic radiation normally interacts therewith, said normal beam monitoring multi-element alignment detector being selected from the group consisting of;

it comprises a plurality of detector elements surrounding a central hole through which said alignment beam passes, said detector elements being positioned to monitor said alignment beam after it reflects from said sample; and

it comprises a plurality of detector elements in combination with a beam spliter, said beam spliter being positioned to intercept said beam which reflects from said sample and direct a portion thereof toward said alignment beam monitoring detector elements;

f) removing said alignment sample from said stage and placing a second sample thereupon;

g) adjusting at least one selection from the group consisting of;

the locations of said ellipsometer source of a beam of electromagnetic radiation and data detector and alignment detector; and

the tip/tilt of said stage;

so that the normal beam monitoring multi-detector element alignment detector provides a selection from the group consisting of;

no output signals; and

each detector element of said normal beam monitoring multi-detector element alignment detector provides said reference output signals; and

h) optionally simultaneous with adjusting the tip/tilt of said stage effecting translation thereof to maintain unchanged the location on said second sample at which said oblique beam reflects therefrom.

5. A method as in claim 4 wherein said oblique angle beam of electromagnetic radiation provided by said ellipsometer source of a beam of electromagnetic radiation and said normal angle alignment beam derived from a selection from the group consisting of:

said ellipsometer source of a beam of electromagnetic radiation;

an alternative source of a beam of electromagnetic radiation;

are caused to impinge on at least one selection from the group consisting of;

said alignment; and

said second sample at the same location.

6. A method as in claim 4 wherein actuators are provided which receive signals from the data and alignment detector elements and produce stage position and orientation controlling motions, and in which said steps g and h are automated.

7. A method as in claim 1 wherein said ellipsometer system further comprises a focusing lens between said ellipsometer source of a beam of electromagnetic radiation and said stage.

8. A method as in claim 1 which further comprises:

e) providing and positioning a source of a beam of electromagnetic radiation derived from a selection from the group consisting of;

said ellipsometer source of a beam of electromagnetic radiation; and

an alternative source of a beam of electromagnetic radiation;

such that it provides an alignment beam of electromagnetic radiation which proceeds substantially along an incident locus which is normal to said alignment sample, which then reflects from said alignment sample and returns substantially back along the incident locus; and

providing a normal beam monitoring multi-detector element alignment detector so that it monitors said reflected alignment beam of electromagnetic radiation, and positioning it such that each detector element of said normal beam monitoring multi-detector element alignment detector provides a selection from the group consisting of;

no output signal; and

each detector element of said normal beam monitoring multi-detector element alignment detector provides reference output signals;

when said reflected alignment beam of electromagnetic radiation normally interacts therewith, said normal beam monitoring multi-element alignment detector being selected from the group consisting of;

it comprises a plurality of detector elements surrounding a central hole through which said alignment beam passes, said detector elements being positioned to monitor said alignment beam after it reflects from said sample; and

it comprises a plurality of detector elements in combination with a beam spliter, said beam spliter being positioned to intercept said beam which reflects from said sample and direct a portion thereof toward said alignment beam monitoring detector elements;

f) removing said alignment sample from said stage and placing a second sample thereupon;

g) adjusting at least one selection from the group consisting of;

the locations of said ellipsometer source of a beam of electromagnetic radiation and data detector and alignment detector and

the tip/tilt of said stage;

so that the normal beam monitoring multi-detector element alignment detector provides a selection from the group consisting of;

no output signals; and

each detector element of said normal beam monitoring multi-detector element alignment detector provides said reference output signals; and

h) optionally simultaneous with adjusting the tip/tilt of said stage effecting translation thereof to maintain unchanged the location on said second sample at which said oblique beam reflects therefrom.

9. A method as in claim 8 wherein said oblique angle beam of electromagnetic radiation provided by said ellipsometer source of a beam of electromagnetic radiation and said normal angle alignment beam derived from a selection from the group consisting of:

said ellipsometer source of a beam of electromagnetic radiation; and

an alternative source of a beam of electromagnetic radiation;

are caused to impinge on at least one selection from the group consisting of;

said alignment; and

said second sample;

at the same location.

10. A method as in claim 8 wherein actuators are provided which receive signals from the data and alignment detector elements and produce stage position and orientation controlling motions, and in which said steps g and h are automated.

11. A method of aligning an ellipsometer system which comprises:

an ellipsometer source of a beam of electromagnetic radiation;

a stage for supporting a sample and having means for effecting tip/tilt and translation thereof;

an oblique beam monitoring multi-element data detector of electromagnetic radiation;

said method comprising;

a) placing a sample on said stage;

b) generally orienting said ellipsometer source of a beam of electromagnetic radiation so that it directs a beam of electromagnetic radiation onto a first location of said sample at an oblique angle, which beam then reflects from said alignment sample and enters said data detector so that it provides an output signal;

performing steps;

c1) while monitoring the output signal from said data detector causing said stage to effect translation of said alignment sample so that said beam is directed to a second location thereon at said oblique angle, reflects therefrom and enters said data detector, followed by adjusting the tip/tilt of said stage;

c2) while monitoring the output signal from said data detector causing said stage to effect translation of said alignment sample so that said beam is directed to a third location thereon at said oblique angle, reflects therefrom and enters said data detector, followed by adjusting the tip/tilt of said stage, said third location being other than co-linear with said first and second locations;

c3) while monitoring the output signal from said data detector causing said stage to effect translation of said alignment sample so that said beam is directed to a said first location thereon at said oblique angle, reflects therefrom and enters said data detector, followed by adjusting the tip/tilt of said stage;

itteratively, in any functional order, until the output of the data detector is substantially the same in all said steps c1, c2 and c3;

with the result being that the stage is oriented in tip/tilt so that no matter from what location on said alignment sample said beam is caused to reflect, the output from said data detector remains substantially the same;

d) optionally while monitoring the outputs from said detector elements of said oblique beam monitoring multi-element alignment detector, moving the location and orientation thereof until said output signals therefrom are substantially optimized.

12. A method as in claim 11 which further comprises itteratively repeating a step c4 along with steps c1, c2 and c3, said step c4 being selected from the group consisting of c4a and c4b:

c4a) while monitoring the output signals from the detector elements of said oblique beam monitoring multi-element alignment detector, causing said stage to effect translation of said sample so that said beam is directed to a forth, arbitrary, location thereon at said oblique angle, reflects therefrom and enters said multi-element alignment detector, followed by adjusting the tip/tilt of said stage;

c4b) while monitoring the output signals from the detector elements of said oblique beam monitoring multi-element alignment detector, causing said stage to effect translation of said sample so that said beam is directed to a forth, location thereon at said oblique angle, reflects therefrom and enters said multi-element alignment detector, followed by adjusting the tip/tilt of said stage, said forth location being oriented so as to form a square shape with the first three locations.

13. A method as in claim 12 wherein said ellipsometer system further comprises a focusing lens between said ellipsometer source of a beam of spectroscopic electromagnetic radiation and said stage.

14. A method as in claim 12 wherein said oblique beam monitoring multi-element alignment detector is selected from the group consisting of:

it comprises a plurality of detector elements surrounding a central hole toward which said beam is directed after it reflects from said sample; and

it comprises a plurality of detector elements in combination with a beam spliter, said beam spliter being positioned to intercept said beam which reflects from said sample and direct a portion thereof toward said oblique beam monitoring multi-element alignment detector.

15. A method as in claim 12 which further comprises:

e) providing and positioning a source of a beam of electromagnetic radiation derived from a selection from the group consisting of;

said ellipsometer source of a beam of electromagnetic radiation; and

an alternative source of a beam of electromagnetic radiation;

such that it provides an alignment beam of electromagnetic radiation which proceeds substantially along an incident locus which is normal to said alignment sample, which then reflects from said alignment sample and returns substantially back along the incident locus; and

providing a normal beam monitoring multi-detector element alignment detector so that it monitors said reflected alignment beam of electromagnetic radiation, and positioning it such that each detector element of said normal beam monitoring multi-detector element alignment detector provides a selection from the group consisting of;

no output signal; and

each detector element of said normal beam monitoring multi-detector element alignment detector provides reference output signals;

when said reflected alignment beam of electromagnetic radiation normally interacts therewith, said normal beam monitoring multi-element alignment detector being selected from the group consisting of;

it comprises a plurality of detector elements surrounding a central hole through which said alignment beam passes, said detector elements being positioned to monitor said alignment beam after it reflects from said sample; and

it comprises a plurality of detector elements in combination with a beam spliter, said beam spliter being positioned to intercept said beam which reflects from said sample and direct a portion thereof toward said alignment beam monitoring detector elements;

f) removing said alignment sample from said stage and placing a second sample thereupon;

g) adjusting the locations of at least one selection from the group consisting of;

said ellipsometer source of a beam of electromagnetic radiation and data detector and alignment detector; and

the tip/tilt of said stage;

so that the normal beam monitoring multi-detector element alignment detector provides a selection from the group consisting of;

no output signals; and

each detector element of said normal beam monitoring multi-detector element alignment detector provides said reference output signals; and

h) optionally simultaneous with adjusting the tip/tilt of said stage effecting translation thereof to maintain unchanged the location on said second sample at which said oblique beam reflects therefrom.

16. A method as in claim 15 wherein said oblique angle beam of electromagnetic radiation provided by said ellipsometer source of a beam of electromagnetic radiation and said normal angle alignment beam derived from a selection from the group consisting of:

said ellipsometer source of a beam of electromagnetic radiation; and

an alternative source of a beam of electromagnetic radiation;

are caused to impinge on at least one selection from the group consisting of;

said alignment; and

said second sample;

at the same location.

17. A method as in claim 15 wherein actuators are provided which receive signals from oblique and normal beam monitoring multi-element alignment detector elements and produce stage position and orientation controlling motions, and in which said steps g and h are automated.

18. A method as in claim 11 wherein said ellipsometer system further comprises a focusing lens between said ellipsometer source of a beam of spectroscopic electromagnetic radiation and said stage.

19. A method as in claim 11 wherein said oblique beam monitoring multi-element alignment detector is selected from the group consisting of:

it comprises a plurality of detector elements surrounding a central hole toward which said beam is directed after it reflects from said sample; and

it comprises a plurality of detector elements in combination with a beam spliter, said beam spliter being positioned to intercept said beam which reflects from said sample and direct a portion thereof toward said oblique beam monitoring multi-element alignment detector.

20. A method as in claim 11 which further comprises:

e) providing and positioning a source of a beam of electromagnetic radiation derived from a selection from the group consisting of;

said ellipsometer source of a beam of electromagnetic radiation; and

an alternative source of a beam of electromagnetic radiation;

such that it provides an alignment beam of electromagnetic radiation which proceeds substantially along an incident locus which is normal to said alignment sample, which then reflects from said alignment sample and returns substantially back along the incident locus; and

providing a normal beam monitoring multi-detector element alignment detector so that it monitors said reflected alignment beam of electromagnetic radiation, and positioning it such that each detector element of said normal beam monitoring multi-detector element alignment detector provides a selection from the group consisting of;

no output signal; and

each detector element of said normal beam monitoring multi-detector element alignment detector provides reference output signals;

when said reflected alignment beam of electromagnetic radiation normally interacts therewith, said normal beam monitoring multi-element alignment detector being selected from the group consisting of;

it comprises a plurality of detector elements surrounding a central hole through which said alignment beam passes, said detector elements being positioned to monitor said alignment beam after it reflects from said sample; and

it comprises a plurality of detector elements in combination with a beam spliter, said beam spliter being positioned to intercept said beam which reflects from said sample and direct a portion thereof toward said alignment beam monitoring detector elements;

f) removing said alignment sample from said stage and placing a second sample thereupon;

g) adjusting the locations of at least one selection from the group consisting of;

said ellipsometer source of a beam of electromagnetic radiation and data detector and alignment detector;

the tip/tilt of said stage;

so that the normal beam monitoring multi-detector element alignment detector provides a selection from the group consisting of;

no output signals;

each detector element of said normal beam monitoring multi-detector element alignment detector provides said reference output signals; and

h) optionally simultaneous with adjusting the tip/tilt of said stage effecting translation thereof to maintain unchanged the location on said second sample at which said oblique beam reflects therefrom.

21. A method as in claim 20 wherein said oblique angle beam of electromagnetic radiation provided by said ellipsometer source of a beam of electromagnetic radiation and said normal angle alignment beam derived from a selection from the group consisting of:

said ellipsometer source of a beam of electromagnetic radiation;

an alternative source of a beam of electromagnetic radiation;

are caused to impinge on at least one selection from the group consisting of;

said alignment; and

said second sample;

at the same location.

22. A method as in claim 20 wherein actuators are provided which receive signals from oblique and normal beam monitoring multi-element alignment detector elements and produce stage position and orientation controlling motions, and in which said steps g and h are automated.