System and method of improving electromagnetic radiation beam characteristics in ellipsometer and the like systems
AssigneeJ.A. Woollam Co., Inc.
InventorsJames D. Welch, Blaine D. Johs, Martin M. Liphardt, Ping He
Life of this patent
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Abstract
Disclosed are systems for, and methods of controlling radial energy density profiles in, and/or cross-section dimensioning of electromagnetic beams in polarimeters, ellipsometers, reflectometers and spectrophotometers.
Claims22
A reflectometer, spectrophotometer, polarimeter or ellipsometer system for application in non-destructive investigation of sample systems, comprising:
- source of electromagnetic radiation;
- means for effecting cross-sectional, essentially radially uniform energy density in electromagnetic beams, said means for effecting cross-sectional, essentially radially uniform energy density in electromagnetic beams comprising a sequential combination of:
- beam expander;
- first beam collimator;
- at least one multi-faceted optical element;
- beam condenser;
- and
- second beam collimator;
- stage for supporting a sample system;
- and
- detector;
- such that in use electromagnetic radiation of arbitrary cross-sectional radial energy density is provided by said source of electromagnetic radiation and is caused to pass through said means for effecting cross-sectional, essentially radially uniform energy density in electromagnetic beams such that a beam of substantially radially uniform energy density is output therefrom, is caused to interact with a sample system placed on said stage for supporting a sample system, and then enter said detector.
A method of non-destructively analyzing a sample system in a reflectometer, spectrophotometer, polarimeter or ellipsometer system which comprises:
- source of electromagnetic radiation,
- stage for supporting a sample system, and
- detector;
- such that in use a beam of electromagnetic radiation is provided by said source of electromagnetic radiation, is caused to interact with a sample system placed on said stage for supporting a sample system, and enter said detector,
- said method comprising the steps of:
- a. providing a reflectometer, spectrophotometer, polarimeter or ellipsometer system comprising:
- source of electromagnetic radiation,
- stage for supporting a sample system, and
- detector;
- b. positioning, between said source of electromagnetic radiation and said stage for supporting a sample system, a means for effecting cross-sectional, essentially radially uniform energy density in electromagnetic beams, said means for effecting cross-sectional, essentially radially uniform energy density in electromagnetic beams comprising a sequential combination of:
- beam expander;
- first beam collimator;
- at least one multi-faceted optical element;
- beam condenser;
- and
- second beam collimator;
- c. placing a sample system on said stage for supporting a sample system;
- d. causing said source of electromagnetic radiation to provide a beam of electromagnetic radiation of arbitrary cross-sectional radial energy density and causing it to pass through said means for effecting cross-sectional, essentially radially uniform energy density in electromagnetic beams such that a beam of substantially radially uniform energy density is output therefrom, is caused to impinge at an oblique angle upon, and interact with a sample system placed on said stage for supporting a sample system, and then enter said detector.
A reflectometer, spectrophotometer, polarimeter or ellipsometer system for application in non-destructive investigation of sample systems, sequentially comprising a source of electromagnetic radiation, an optical element which demonstrates non-radial symetry, a stage for supporting a sample system, and a detector, such that a beam of electromagnetic radiation provided by said source of electromagnetic radiation is caused to interact with said optical element which demonstrates non-radial symetry and then impinge on a surface of a sample system placed on said stage for supporting a sample system, thereat forming an essentially circular spot, said beam of electromagnetic radiation then being caused to enter said detector.
A method of causing an electromagnetic beam to form an essentially circular spot shape at a surface of a sample system, in a reflectometer, spectrophotometer, polarimeter or ellipsometer system;
- where said electromagnetic beam impinges onto said sample system surface from a source located so as to cause said beam of electromagnetic radiation to approach said sample system along a locus other than coincident with a normal to said sample system surface, comprising the steps of causing a beam of electromagnetic radiation to progress toward a sample system, and placing an optical element in the pathway of said electromagnetic beam which presents with non-radial symmetry.
A reflectometer, spectrophotometer, polarimeter or ellipsometer system comprising a source of electromagnetic radiation, a stage for supporting a sample system, and an optical element, said optical element causing a beam of electromagnetic radiation provided by said source of electromagnetic radiation to, prior to the location of said stage for supporting a sample system, present with a cross-sectional shape which is essentially elliptical.
A method of causing an electromagnetic beam in a reflectometer, spectrophotometer, polarimeter or ellipsometer system, to form an essentially circular spot shape at a surface of a sample system, where said electromagnetic beam impinges onto said sample system surface from a source located so as to cause said beam of electromagnetic radiation to approach said sample system along a locus other than coincident with a normal to said sample system surface, comprising the step of placing an aperture in the pathway of said electromagnetic beam which presents with a larger “width-wise” than “length-wise” dimension, such that the elongation of the electromagnetic beam in the “length-wise” direction at the sample system surface whereat the beam impinges as a result of its impinging along a direction removed from perpendicular thereto, is appropriate to cause the resulting beam spot shape to be essentially circular at said surface of a sample system where said electromagnetic beam impinges onto said sample system surface.
A method of causing an electromagnetic beam in a reflectometer, spectrophotometer, polarimeter or ellipsometer system, to form an essentially circular spot shape at a surface of a sample system, where said electromagnetic beam impinges onto said sample system surface from a source located so as to cause said beam of electromagnetic radiation to approach said sample system along a locus other than coincident with a normal to said sample system surface, comprising the step of placing an aperture in the pathway of said electromagnetic beam which presents with a larger “width-wise” than “length-wise” dimension, such that the elongation of the electromagnetic beam at the point on the sample system surface whereat the beam impinges thereupon as a result of its impinging along a direction removed from perpendicular thereto causes the spot shape thereat to be more circular than it would otherwise be;
- said method further comprising the step of placing a second optical element in the pathway of said electromagnetic beam which presents with non-radial symmetry;
- the combined result of said aperture which presents with a larger “width-wise” than “length-wise” dimension, and second optical element which presents with non-radial symmetry, being an essentially circular spot shape at said surface of a sample system where said electromagnetic beam impinges thereonto.
Dependencies are inferred from the claim text.