Patent US5596411A successfully refreshed from Google Patents.
US5596411A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Integrated spectroscopic ellipsometer
Assignee: Therma Wave Inc
•
Filing: 1996-03-18
•
Granted: 1997-01-21
•
Expires: 2016-03-18
Abstract
Abstract An optical inspection apparatus is disclosed for generating an ellipsometric output signal at a plurality of wavelengths, each signal being representative of an integration of measurements at a plurality of angles of incidence. A polarized, broad band light beam is focused through a lens onto a sample in a manner to create a spread of angles of incidence. The reflected beam is passed through a quarter-wave plate and a polarizer which creates interference effects between the two polarizations states in the beam. The beam is then passed through a filter which transmits two opposed radial quadrants of the beam and blocks light striking the remaining two quadrants. The beam is then focused and angularly dispersed as function of wavelength. Each element of a one dimensional photodetector array generates an output signal associated with a specific wavelength and represents an integration of the phase-sensitive ellipsometric parameter (δ) at a plurality of angles of incidence. A second, independent measurement is taken in order to isolate the signal of interest. In one embodiment, the azimuthal angle of the filter is rotated by ninety degrees. The output signals from the second measurement are subtracted from the corresponding output signals from the first measurement to obtain the phase-sensitive ellipsometric information at a plurality of wavelengths. The ellipsometric information is used to analyze the sample.
Inventors
- 👤 Jeffrey T. Fanton
- 👤 Jon Opsal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 23:07
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/21; G01N21/211
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
215 words
An apparatus for evaluating a sample comprising: a source for generating a beam of polychromatic light; means for polarizing the light beam; lens means for focusing the light beam onto the surface of the sample in a manner so that various rays within the beam create a spread of angles of incidence; means for retarding the phase of one polarization state of the light beam; means for creating interference effects between the two polarization states of the beam after it has interacted with the sample; filter means located in an image plane of the lens means for filtering the light beam, said filter means for transmitting at least a portion of the light passing through a first radial quadrant and blocking light from the two radial quadrants disposed orthogonally thereto; optical means for focusing the transmitted light and angularly dispersing the focused light as a function of wavelength; means for measuring the intensity of the focused light as a function of position; means for obtaining a second independent intensity measurement of light having the characteristics of the light which was blocked by said filter means during the first intensity measurement; and processor means for evaluating the sample based on the independent measurements, wherein said measurements represent an integration of rays at various angles of incidence.
Claim 2
Independent Claim
215 words
An apparatus for evaluating a sample comprising: a source for generating a beam of polychromatic light; means for polarizing the light beam; lens means for focusing the light beam onto the surface of the sample in a manner so that various rays within the beam create a spread of angles of incidence; means for retarding the phase of one polarization state of the light beam; means for creating interference effects between the two polarization states of the beam after it has interacted with the sample; filter means located in an image plane of the lens means for filtering the light beam, said filter means for transmitting at least a portion of the light passing through a first radial quadrant and blocking light from the two radial quadrants disposed orthogonally thereto; optical means for focusing the transmitted light and angularly dispersing the focused light as a function of wavelength; means for measuring the intensity of the focused light as a function of position; means for obtaining a second independent intensity measurement of light having the characteristics of the light which was blocked by said filter means during the first intensity measurement; and processor means for evaluating the sample based on the independent measurements, wherein said measurements represent an integration of rays at various angles of incidence.
Claim 3
Dependent Claim
41 words
An apparatus as recited in claim 1 wherein said means for obtaining the second independent measurement includes a means for rotating the azimuthal angle of one of the polarizing means, retarding means, interference creating means and filter means by ninety degrees.
Claim 4
Dependent Claim
38 words
An apparatus as recited in claim 1 further including a means for rotating the azimuthal angle of one of the polarizing means, retarding means, interference creating means and filter means and for taking measurements at multiple azimuthal angles.
Claim 5
Dependent Claim
61 words
An apparatus as recited in claim 1 wherein said means for obtaining the second measurement includes splitting the light beam after it has interacted with the sample and providing a second filter means and optical means and measuring means oriented to measure light having the characteristic of the light that was blocked by the filter means during the first intensity measurement.
Claim 6
Dependent Claim
24 words
An apparatus as recited in claim 1 wherein said means for creating interference effects consists of a polarizer formed integrally with the filter means.
Claim 7
Dependent Claim
59 words
An apparatus as recited in claim 5 wherein the first quadrant of said filter as well as the quadrant disposed opposite thereto include a linear polarizer for polarizing light along a first axis and wherein said two orthogonally disposed quadrants of said filter include a linear polarizer for polarizing light along a second axis orthogonal to the first axis.
Claim 8
Dependent Claim
19 words
An apparatus as recited in claim 1 wherein said means for polarizing the light beam is a linear polarizer.
Claim 9
Dependent Claim
18 words
An apparatus as recited in claim 1 wherein said means for retarding the beam is a quarter-wave plate.
Claim 10
Dependent Claim
18 words
An apparatus as recited in claim 1 wherein said means for creating interference effects is a linear polarizer.
Claim 11
Dependent Claim
46 words
An apparatus as recited in claim 1 wherein said means for creating interference is defined by a polarizing beam splitter for dividing the beam into two halves with different polarization states and further including a second optical means and detector means for obtaining the second measurement.
Claim 12
Dependent Claim
15 words
An apparatus as recited in claim 1 wherein said optical means includes a curved grating.
Claim 13
Dependent Claim
15 words
An apparatus as recited in claim 1 wherein measuring means includes a one-dimensional photodetector array.
Claim 14
Dependent Claim
30 words
An apparatus as recited in claim 1 wherein said filter means is formed from a liquid crystal device configured such that the transmission of radial quadrants can be selectively controlled.
Claim 15
Independent Claim
228 words
An apparatus for evaluating a sample comprising: a source for generating a beam of polychromatic light; means for polarizing the light beam; lens means for focusing the light beam onto the surface of the sample in a manner so that various rays within the beam create a spread of angles of incidence; means for retarding the phase of one polarization state of the light beam; means for creating interference effects between the two polarization states of the beam after it has interacted with the sample; filter means located in an image plane of the lens means for filtering the light beam, said filter means for transmitting a portion of the light passing through a pair of opposed radial quadrants and blocking light from the remaining pair of radial quadrants disposed orthogonally thereto; optical means for focusing the transmitted light and angularly dispersing the focused light as a function of wavelength; means for measuring the intensity of the focused light as a function of position; means for rotating the azimuthal angle of one of the polarizing means, retarding means, interference creating means and filter means by ninety degrees allowing said measuring means to perform an independent measurement of the intensity of the focused light; and processor means for evaluating the sample based on the independent measurements, wherein said measurements represent an integration of rays at various angles of incidence.
Claim 16
Independent Claim
228 words
An apparatus for evaluating a sample comprising: a source for generating a beam of polychromatic light; means for polarizing the light beam; lens means for focusing the light beam onto the surface of the sample in a manner so that various rays within the beam create a spread of angles of incidence; means for retarding the phase of one polarization state of the light beam; means for creating interference effects between the two polarization states of the beam after it has interacted with the sample; filter means located in an image plane of the lens means for filtering the light beam, said filter means for transmitting a portion of the light passing through a pair of opposed radial quadrants and blocking light from the remaining pair of radial quadrants disposed orthogonally thereto; optical means for focusing the transmitted light and angularly dispersing the focused light as a function of wavelength; means for measuring the intensity of the focused light as a function of position; means for rotating the azimuthal angle of one of the polarizing means, retarding means, interference creating means and filter means by ninety degrees allowing said measuring means to perform an independent measurement of the intensity of the focused light; and processor means for evaluating the sample based on the independent measurements, wherein said measurements represent an integration of rays at various angles of incidence.
Claim 17
Dependent Claim
19 words
An apparatus as recited in claim 14 wherein said means for polarizing the light beam is a linear polarizer.
Claim 18
Dependent Claim
18 words
An apparatus as recited in claim 14 wherein said means for retarding the beam is a quarter-wave plate.
Claim 19
Dependent Claim
18 words
An apparatus as recited in claim 14 wherein said means for creating interference effects is a linear polarizer.
Claim 20
Dependent Claim
15 words
An apparatus as recited in claim 14 wherein said optical means includes a curved grating.
Claim 21
Dependent Claim
15 words
An apparatus as recited in claim 14 wherein measuring means includes a one-dimensional photodetector array.
Claim 22
Dependent Claim
30 words
An apparatus as recited in claim 14 wherein said filter means is formed from a liquid crystal device configured such that the transmission of radial quadrants can be selectively controlled.
Claim 23
Independent Claim
234 words
An apparatus for evaluating a sample comprising: a source for generating a beam of polychromatic light; means for initially polarizing the light beam; lens means for focusing the light beam onto the surface of the sample in a manner so that various rays within the beam create a spread of angles of incidence; means for retarding the phase of one polarization state of the light beam; filter means located in an image plane of the lens means for filtering the light beam, said filter means including a first linear polarizer formed in a pair of opposed radial quadrants and a second linear polarizer formed in the remaining pair of quadrants disposed orthogonally thereto, and wherein the axis of polarization of the first linear polarizer is disposed orthogonally with respect to the axis of polarization of the second linear polarizer; optical means for focusing the transmitted light and angularly dispersing the focused light as a function of wavelength; means for measuring the intensity of the focused light as a function of position; means for rotating the azimuthal angle of one of the polarizing means, retarding means, interference creating means and filter means by ninety degrees allowing said measuring means to perform an independent measurement of the intensity of the focused light; and processor means for evaluating the sample based on the measurements, wherein said measurements represent an integration of rays at various angles of incidence.
Claim 24
Independent Claim
234 words
An apparatus for evaluating a sample comprising: a source for generating a beam of polychromatic light; means for initially polarizing the light beam; lens means for focusing the light beam onto the surface of the sample in a manner so that various rays within the beam create a spread of angles of incidence; means for retarding the phase of one polarization state of the light beam; filter means located in an image plane of the lens means for filtering the light beam, said filter means including a first linear polarizer formed in a pair of opposed radial quadrants and a second linear polarizer formed in the remaining pair of quadrants disposed orthogonally thereto, and wherein the axis of polarization of the first linear polarizer is disposed orthogonally with respect to the axis of polarization of the second linear polarizer; optical means for focusing the transmitted light and angularly dispersing the focused light as a function of wavelength; means for measuring the intensity of the focused light as a function of position; means for rotating the azimuthal angle of one of the polarizing means, retarding means, interference creating means and filter means by ninety degrees allowing said measuring means to perform an independent measurement of the intensity of the focused light; and processor means for evaluating the sample based on the measurements, wherein said measurements represent an integration of rays at various angles of incidence.
Claim 25
Independent Claim
196 words
A method for evaluating a sample comprising: generating a beam of polychromatic light; polarizing the light beam; focusing the light beam through a lens onto the surface of the sample in a manner so that various rays within the beam create a spread of angles of incidence; retarding the phase of one polarization state of the light beam; creating interference effects between the two polarization states of the beam after it has interacted with the sample; filtering the light beam in a manner to transmit a the portion thereof passing through a pair of opposed radial quadrants and blocking light from the remaining pair of radial quadrants disposed orthogonally thereto, said filtering step being performed in an image plane of the lens; focusing the transmitted light and angularly dispersing the focused light as a function of wavelength; measuring the intensity of the focused light as a function of position; obtaining a second independent intensity measurement of light having the characteristics of the light which was blocked during the first intensity measurement; and processor means for evaluating the sample based on the independent measurements, wherein said measurements represent an integration of rays at various angles of incidence.
Claim 26
Independent Claim
196 words
A method for evaluating a sample comprising: generating a beam of polychromatic light; polarizing the light beam; focusing the light beam through a lens onto the surface of the sample in a manner so that various rays within the beam create a spread of angles of incidence; retarding the phase of one polarization state of the light beam; creating interference effects between the two polarization states of the beam after it has interacted with the sample; filtering the light beam in a manner to transmit a the portion thereof passing through a pair of opposed radial quadrants and blocking light from the remaining pair of radial quadrants disposed orthogonally thereto, said filtering step being performed in an image plane of the lens; focusing the transmitted light and angularly dispersing the focused light as a function of wavelength; measuring the intensity of the focused light as a function of position; obtaining a second independent intensity measurement of light having the characteristics of the light which was blocked during the first intensity measurement; and processor means for evaluating the sample based on the independent measurements, wherein said measurements represent an integration of rays at various angles of incidence.
References Cited (Backward Citations)
US3316799A
Cited
US3397608A
Cited
US4210401A
Cited
FR2602338A1
Cited
US4999014A
Cited
US5042951A
Cited
US5166752A
Cited
US5159412A
Cited
US5181080A
Cited
US5412473A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-01-21 | 2000-07-22 | 2001-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-01-21 | 2004-07-22 | 2005-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-01-21 | 2008-07-22 | 2009-01-21 | $7700.00 | Window Closed / Lapsed |