Ellipsometer

• US 3,874,797 A
• Filed: 04/05/1974
• Issued: 04/01/1975
• Est. Priority Date: 04/13/1973
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Toshiyuki Kasai
• Inventors: Kasai, Toshiyuki
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Goodwin, Paul K.
• Application Number:
  US05/458,426
• Time in Patent Office: 361 Days
• Field of Search: 356/114,115,116,118,161 350/147,152 250/285
• US Class Current: 356/369
• CPC Class Codes: G01B 11/0641 with measurement of polarization
• CPC Class Codes: G01N 21/211 Ellipsometry optical thickness measurement G01B11/06

Abstract

An ellipsometer includes a polarizing optical system, a first and a second optical path changing total reflecting prism, and an analyzer. Light from a light source passes through the polarizing optical system to leave it in the form of elliptical polarized light, which in turn passes through the first total reflection prism in which the elliptical polarized light is given a phase skip difference and deflected so as to impinge on the surface of a sample obliquely with respect thereto. The light so reflected by the first total reflection prism further passes through the second total reflection prism in which the light is given a phase skip difference and deflected in a direction substantially parallel to the optical axis of the polarizing optical system. The light passed through the second total reflection prism is finally extinguished by the analyzer.

Claims

1. An ellipsometer for measuring the thickness, optical constant or the like of a sample from the polarization with which light impinging on the surface of the sample is reflected therefrom, said ellipsometer comprising:

a polarizing optical system disposed on an optical axis substantially perpendicular to the surface of the sample to be measured and for providing an emergence of elliptical polarized light;

a first optical path changing total reflection prism for imparting a phase skip difference to the elliptical polarized light emergent from said polarizing optical system and for totally reflecting said polarized light to deflect the path thereof to cause it to impinge obliquely on said sample surface;

a second optical path changing total reflection prism for imparting a phase skip difference to said light reflected by said surface of the sample and for totally reflecting said reflected light to deflect the path thereof to cause it to be substantially parallel to the optical axis of said polarizing optical system; and

an analyzer for extinguishing the light passed through said second total reflection prism.

2. An ellipsometer according to claim 1, wherein said polarizing optical system comprises:

a light source;

a monochrome filter for passing therethrough the light from said source;

a polarizer for converting the monochromatic light from said monochrome filter into rectilinear polarized light; and

a 1/4 wavelength plate for converting said rectilinear polarized light from said polarizer into elliptical polarized light of an azimuth angle 45* with respect to thE incidence surface of the sample.

3. An ellipsometer according to claim 1, wherein the sum of the phase skip differences imparted by said first and second optical path changing total reflection prisms is 180*.

4. An ellipsometer according to claim 3, wherein the phase skip difference imparted by said first optical path changing total reflection prism is 135* and the phase skip difference imparted by said second optical path changing total reflection prism is 45* .