Patent ID: 6367329
Filing Date: 2002-04-09
Classification: G01N,H01J

Abstract:
A method for determining an endpoint of a plasma etch process in a semiconductor manufacturing process, comprising the steps of:introducing reactant gases into a reaction chamber of a plasma generator and generating a plasma; subjecting a substrate with at least a first material layer formed thereon to the plasma, whereby the first material layer is etched by the plasma; introducing at least a portion of a gas stream from the reaction chamber into an acoustic cell during the plasma etch process; regulating pressure of the gas stream in the acoustic cell to a preselected value higher than a pressure in the reaction chamber; transmitting an acoustic signal through the gas stream in the acoustic cell; monitoring the acoustic signal transmitted through the gas stream during the plasma etch process; and determining the endpoint of the plasma etch process in response to an observed change in the monitored acoustic signal.