Measuring method for ellipsometric parameter and ellipsometer

An ellipsometer comprising:

• a light source section for radiating a polarized light beam onto a measurement target at a predetermined angle;
• a composite beam splitter for splitting a reflected light beam from the measurement target into four different polarized light components, each of which has a respective light intensity;
• four light-receiving units for detecting the light intensities of the four respective polarized light components produced by said composite beam splitter;
• means for selecting three of said polarized light components having the three highest light intensities out of the four light intensities detected by said four light-receiving units;
• and
• means for calculating ellipsometric parameters of an elliptically polarized light beam of the reflected light beam on the basis of the three selected polarized light components having said three highest light intensities,
• said composite beam splitter comprising:
• a non-polarizing member for splitting the reflected light beam from the measurement target, at an incident surface of said non-polarizing member, into a reflected light beam and a transmitted light beam;
• a first polarizing beam splitter, having one end fixed to said non-polarizing member, for splitting the reflected light beam from said non-polarizing member into light components polarized in directions at +90.degree. and 0.degree. with respect to a reference direction;
• and
• a second polarizing beam splitter, bonded to an exit surface of said non-polarizing member, from which the transmitted light beam emerges, for splitting the transmitted light beam from said non-polarizing member into light components polarized in directions at +45.degree. and -45.degree. with respect to said reference direction.

An ellipsometer comprising:

• a light source section for radiating a polarized light beam onto a measurement target at a predetermined angle;
• a composite beam splitter for splitting a reflected light beam from the measurement target into four different polarized light components, each of which has a respective light intensity;
• four light-receiving units for detecting the light intensities of the four respective polarized light components produced by said composite beam splitter;
• means for selecting three of said polarized light components having the three highest light intensities out of the four light intensities detected by said four light-receiving units;
• and
• means for calculating ellipsometric parameters of an elliptically polarized light beam of the reflected light beam on the basis of the three selected polarized light components having said three highest light intensities,
• said composite beam splitter comprising:
• a non-polarizing member for splitting the reflected light beam from the measurement target, at an incident surface of said non-polarizing member, into a reflected light beam and a transmitted light beam;
• a first polarizing beam splitter, having one end fixed to said non-polarizing member, for splitting the reflected light beam from said non-polarizing member into light components polarized in directions at +45.degree. and -45.degree. with respect to a reference direction;
• and
• a second polarizing beam splitter, bonded to an exit surface of said non-polarizing member, from which the transmitted beam emerges, for splitting the transmitted light beam from said non-polarizing member into light components polarized in directions at +90.degree. and 0.degree. with respect to said reference direction.