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30 April 1981 End-Point Detection With Laser Interferometry
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A laser interferometric method was developed to detect end-of-etching of materials such as doped and undoped polysilicon, Si3N4, Si02 and metals used during different stages of IC and thin film device processing. For metal etching, a detector trace of constant magnitude is obtained until the underlying layers are exposed. At this point, a step change in re-flectivity occurs, signaling the end-point. For the other above mentioned films, a sinu-soidal waveform is obtained which changes its frequency once the film of interest is etched and the underlying layers become exposed. The method is applicable to all of the dry etch-ing processes and will be illustrated in some detail for polysilicon and silicon nitride etching applications using a barrel-type plasma reactor.
© (1981) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Heinz H. Busta "End-Point Detection With Laser Interferometry", Proc. SPIE 0276, Optical Characterization Techniques for Semiconductor Technology, (30 April 1981);

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