Patent ID: 6707545
Filing Date: 2004-03-16
Classification: G01N,H01L

Abstract:
A method for inspecting a plurality of substrates, comprising:providing a plurality of fiber optic cables adapted to transmit a plurality of optical signals received from a surface of the substrates positioned at different locations; multiplexing, at a signal switching unit, between the plurality of optical signals transmitted by the plurality of fiber optic cables in order to allow transmission of a multiplexed portion of the optical signals; detecting, at a detector unit, the multiplexed portion of the optical signals received from the signal switching unit; and determining, at a signal processing unit, a topographical condition of the substrate according to optical information contained in the multiplexed portion of optical signals via comparison of the optical information to references optical information, wherein the optical information contained in the multiplexed portion of optical signals and the reference optical information are indicative of a plasma uniformity on a surface of the substrate.