Massachusetts Institute of Technology

Timothy J Dalton

Emanuel Michael Sachs

Herbert H Sawin

William T Conner

A new technique has been developed to measure etching or deposition rate uniformity in situ using a CCD camera which views the wafer during plasma processing. The technique records the temporal modulation of plasma emission or laser illumination reflected from the wafer; this modulation is caused by interferometry as thin films are etched or deposited. The measured etching rates compare very well with those determined by Helium-Neon laser interference. This technique is capable of measuring etching rates across 100-mm or larger wafers. It can resolve etch rate variations across a wafer or within a die. The invention can also be used to make endpoint determinations in etching operations as well as measuring the absolute thickness of thin films.

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N. Reading, MA, United States of America

Timothy J Dalton