8 June 1998 High-resolution profilometry for improved overlay measurements of CMP-processed layers
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Abstract
Chemical-mechanical polishing (CMP) processes are widely used in the semiconductor industry to enable multilevel device processing and smaller device features with smaller stepper lens depth of focus. However, CMP planarization of the wafers can lead to failure modes in stepper alignment and overlay measurements that rely on some topography for contrast. It is also been speculated that the CMP process, with its rotating pads that are wetted with polishing slurry, has a spreading or smearing effect on the overlay targets. Both these effects can lead to inaccurate and imprecise overlay measurements. In this paper, we present the results of measuring the depth and asymmetry of overlay targets post-CMP using a High Resolution Profiler. We find clear evidence of smearing in post-CMP overlay targets and discuss its impact on stepper registration error.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Anna Mathai, Jason Schneir, "High-resolution profilometry for improved overlay measurements of CMP-processed layers", Proc. SPIE 3332, Metrology, Inspection, and Process Control for Microlithography XII, (8 June 1998); doi: 10.1117/12.308725; https://doi.org/10.1117/12.308725
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