End-Point Detection With Laser Interferometry

Heinz H. Busta

doi:10.1117/12.931702

30 April 1981 End-Point Detection With Laser Interferometry

Heinz H. Busta

Proceedings Volume 0276, Optical Characterization Techniques for Semiconductor Technology; (1981) https://doi.org/10.1117/12.931702
Event: 1981 Microlithography Conferences, 1981, San Jose, United States

Abstract

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.

Citation Download Citation

Heinz H. Busta "End-Point Detection With Laser Interferometry", Proc. SPIE 0276, Optical Characterization Techniques for Semiconductor Technology, (30 April 1981); https://doi.org/10.1117/12.931702

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