Optical metrology system with combined interferometer and ellipsometer

A metrology tool with an interferometer and an ellipsometer, said metrology tool comprising:

• means for producing a light beam for an interferometer;
• means for producing a light beam for an ellipsometer;
• interferometer optics for directing said light beam for an interferometer onto a sample, wherein the interferometer optics comprise a beam splitter that splits said light beam for the interferometer into two light beams both of which are reflected off the sample;
• ellipsometer optics for directing said light beam for an ellipsometer onto a sample;
• and
• a means for receiving and detecting both the reflected light beam for an interferometer and the reflected light beam for an ellipsometer.

A method of measuring the step height of a sample, said method comprising:

• producing a light beam
• directing said light beam into an interferometer path;
• directing said light beam into an ellipsometer path;
• splitting the light beam in the interferometer path into two light beams;
• reflecting the two light beams in the interferometer path off said sample;
• combining the two reflected light beams into one reflected light beam:
• reflecting the light beam for an ellipsometer off said sample;
• and
• receiving the reflected light beam for an interferometer and the reflected light beam for an ellipsometer at the same detector element.

An apparatus for measuring a step height of a sample, said apparatus comprising:

• a light source;
• a polarizer to polarize a light beam emitted from said light source;
• said light beam providing a light beam for an interferometer and a light beam for an ellipsometer,
• interferometer optics disposed to receive said light beam for an interferometer, wherein the interferometer optics comprise a beam splitter that splits said light beam for the interferometer into two light beams and directs said two light beams for an interferometer to reflect off said sample and combines the two reflected light beams into one reflected light beam;
• ellipsometer optics disposed to receive said light beam for an ellipsometer and direct said light beam for an ellipsometer to reflect off said sample;
• an analyzer disposed downstream of said interferometer optics and ellipsometer optics to analyze said one reflected light beam and said light beam for an ellipsometer after being reflected off said sample;
• and
• a detector element for receiving the light beam for an interferometer and the light beam for an ellipsometer after passing through the analyzer.