EP0091545A2
Expired / Lapsed
EP
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Ellipsometers
Assignee: International Business Machines Corp
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Filing: 1983-02-18
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Granted: —
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Expires: 2003-02-18
Abstract
Abstract An ellipsometer includes a quarter wavelength plate 16 located between a laser source 14 and an electro-optic polarization modulator 18 driven in time quarature by two 90 degree out-of-phase A C electrical signals at a single frequency. The modulator consists of an array of uniaxial electro-optic crystal plates 18A, B, C, D, E in series and is located between the laser source 14 and the sample 12. The polarization modulator 18 is operative to rotate the planes of polarization of the light transmitted therethrough. A 45° analyzer 20 is located between the sample 12 and the detector 22. A stored program computer 24 is connected to the output of the detector 21 to acquire data at specific times and to analyze the signal.
Inventors
- 👤 Jean-Claude Andre Chastang
- 👤 Walter William Hildenbrand
- 👤 Menachem Levanoni
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:03
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/21; G01N21/211
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
140 words
An ellipsometer for use with a sample, comprising a source (14) of monochromatic light to provide a beam of light directed at the sample (12), a quarter wave (?/4) plate (16) positioned in the beam path between the source (14) and the specimen (12), and a detector (22) positioned to receive light from the specimen, said ellipsometer being characterised by the combination of an electro-optial polarization modulator (18) positioned in the beam between the quarter wave plate (16) and the sample (12) and a polarization analyser located in the beam between the sample and the detector (22), said polarization modular (18) being driven by two separate electrical signals having the same frequency but in time quadrature so that the plane of polarization of the light emerging from the modulator (18) is effectively rotated at the frequency of the applies signals.
Claim 2
Dependent Claim
140 words
An ellipsometer for use with a sample, comprising a source (14) of monochromatic light to provide a beam of light directed at the sample (12), a quarter wave (?/4) plate (16) positioned in the beam path between the source (14) and the specimen (12), and a detector (22) positioned to receive light from the specimen, said ellipsometer being characterised by the combination of an electro-optial polarization modulator (18) positioned in the beam between the quarter wave plate (16) and the sample (12) and a polarization analyser located in the beam between the sample and the detector (22), said polarization modular (18) being driven by two separate electrical signals having the same frequency but in time quadrature so that the plane of polarization of the light emerging from the modulator (18) is effectively rotated at the frequency of the applies signals.
Claim 3
Dependent Claim
41 words
An ellipsometer as claimed in claim 1, further characterised in that the polarization modulator (18) comprises at least one pair of uni-axial electro-optic crystal plates (18A, 18B) in series to which the electric signals are applied parallel to the optic axis.
Claim 4
Dependent Claim
25 words
An ellipsometer as claimed in claim 2, further characterised in that the or each pair of plates have their dielectric axes inclined at 45 degrees.
Claim 5
Dependent Claim
44 words
An ellipsometer as claimed in claim 1, 2 or 3, further characterised in that the optical path of the beam is arranged so that the light is incident on the surface of the sample at an angle of about 70 degrees to the normal.
Claim 6
Dependent Claim
26 words
An ellipsometer as claimed in claim 1, 2, 3 or 4, further characterised in that the analyzer has a fixed azimuth angle (A) of 45 degrees.
Claim 7
Dependent Claim
30 words
An ellipsometer as claimed in any one of claims 1 to 5 in combination with a stored program data processing apparatus programmed to analyse the signals received from the detector.
References Cited (Backward Citations)
No citation records indexed.
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