1 August 2003 Silicon wafer thickness variation measurements using the National Institute of Standards and Technology infrared interferometer
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Abstract
Decreasing depths of focus, coupled with increasing silicon wafer diameters, place greater restrictions on chucked wafer flatness in photolithography processes. A measurement device is described that measures thickness variation of double-sided polished wafers using an IR source and vidicon detector. Various possible instrument configurations are described with the focus on a setup that uses a collimated wavefront to produce interference fringes between the front and back surfaces of the plane parallel wafer. Experimental results are presented. These tests include (1) a drift test; (2) comparisons between measurements performed using different collimators and, subsequently, wavefronts; (3) an exploration of the impact of phase change on reflection due to the wafer clamping method; and (4) an intercomparison with thickness measurements recorded by a capacitance gage-based instrument and surface measurements obtained using a separate visible wavelength interferometer.
© (2003) Society of Photo-Optical Instrumentation Engineers (SPIE)
Tony L. Schmitz, Tony L. Schmitz, Angela D. Davies, Angela D. Davies, Chris Evans, Chris Evans, Robert E. Parks, Robert E. Parks, } "Silicon wafer thickness variation measurements using the National Institute of Standards and Technology infrared interferometer," Optical Engineering 42(8), (1 August 2003). https://doi.org/10.1117/1.1589757 . Submission:
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