METHOD AND SYSTEM FOR MEASURING PATTERNED SUBSTRATES

摘要

A system and method of measuring feature depth using a common path auto-correlation low coherence interferometer including a light source having an output directed toward a first beam splitter, the first beam splitter directing at least a portion of a light beam from the light source toward a sample having two reflective interfaces including a top surface reflective interface and a feature bottom reflective interface. The first beam splitter can also pass toward a second beam splitter each of a reference light beam reflected from the top surface interface and a measurement light beam reflected from the feature bottom reflective interface. The second beam splitter directs the reference light beam to a first mirror and the measurement light beam to a second mirror and combines a reflected measurement light beam from the second mirror and a reflected reference light beam from the first mirror to form an interference pattern.

主权项

1. A common path auto-correlation low coherence interferometer system comprising:
a light source having an output directed toward a first beam splitter; the first beam splitter configured to direct at least a portion of a light beam output by the light source toward a sample having two reflective interfaces including a top surface reflective interface and a feature bottom reflective interface; the first beam splitter further configured to pass toward a second beam splitter each of a reference light beam reflected from the top surface interface and a measurement light beam reflected from the feature bottom reflective interface; the second beam splitter configured to direct the reference light beam to a first mirror and the measurement light beam to a second mirror, wherein the first mirror is a first distance from the second beam splitter and the second mirror is a second distance from the second beam splitter; the second beam splitter further configured to combine a reflected measurement light beam reflected from the second mirror and a reflected reference light beam reflected from the first mirror and direct a resulting interference pattern toward a detector, wherein the first mirror is a scanning mirror such that a difference distance between the first distance and the second distance is equal to an optical separation between the feature bottom reflective interface and the top surface reflective interface.