Reflection-free ellipsometry measurement apparatus and method for small sample cells
AssigneeSanta Barbara Research Center
InventorsDavid R. Rhiger, Gerald A. Garwood, Jr.
Life of this patent
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Abstract
An ellipsometry cell is provided with a transparent lid that is positioned close to a specimen within the cell, thus allowing for a low volume wet chemical treatment of the specimen, and yet prevents interference with the ellipsometry measurements by partial reflections of a probe beam off the outer and inner lid surfaces. This is accomplished by configuring the lid to direct an ellipsometry beam and reflections thereof at different angles, so that the beam but not its reflections enter an ellipsometer analyzer. The lid preferably has an angled outer surface with beam entry and exit windows symmetrically tapering from a central ridge, and its inner surface substantially flat and parallel to the cell base.
Claims16
In an ellipsometry system having means for holding a sample to be ellipsemetrically analyzed, means for directing an elliptically polarized beam onto said sample, and means for analyzing the beam reflected from the sample, the improvement comprising the provision of said sample holding means as:
- a housing for enclosing said sample, and
- a unitary lid for said housing having entrance and exit windows that are substantially transparent to and partially reflect said beam, said windows being oriented at different respective angles to said beam and being configured to direct said beam and window reflections at different angles so that said beam but not said window reflections enter said analyzing means.
A cell for holding a sample for ellipsometric analysis, comprising:
- a base,
- means for supporting a sample with respect to said base,
- a substantially transparent lid having inner and outer surfaces, wherein the outer lid surface comprises a plurality of sections that are oriented at different respective angles relative to the base, and
- means for holding said lid in sealed relation to said base,
- said lid being configured so that, in response to an ellipsometric analysis beam being transmitted through the lid and reflected off a sample within the cell back out through the lid, primary reflections of the beam from the lid's upper and lower surfaces and directed out of the cell at different angles from the analysis beam.
A method of ellipsometrically analyzing a sample, comprising:
- directing an elliptically polarized beam onto said sample through a substantially transparent entrance window, and reflecting said beam off said sample and through a substantially transparent exit window, wherein said entrance and exit windows are provided with a flat common surface facing said sample, and respective outer surfaces facing away from said sample at different angles,
- directing surface reflections of said beam from said entrance and exit windows at different angles to said reflected beam to segregate them from the reflected beams, and
- positioning an ellipsometric analyzer to detect and analyze said reflected beam but not said surface reflections.
Dependencies are inferred from the claim text.