9 July 1986 Thin Silicon Films Used As Antireflection Coatings For Metal Coated Substrates
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The controllable patterning of micrometer and submicrometer resist features on metal layers is critical for many VLSI processes, but the exposure of photoresist to near normal incidence illumination will result in spatial, energy variations coupled into the photoresist i.e., standing waves. The dominant factor that determines the amplitude of the standing wave is the substrate reflectivity. The deleterious effects of light reflected from the photoresist/substrate interface are well documented. Thin, sputtered Si films have been found an effective antireflection coating for reducing standing wave effects over metal layers and thus improving resist linewidth control, resolution and sidewall angle. The optical constants of Ar sputtered Si have been measured and this data is used to simulate the resultant reflectivity as a function of Si thickness. In our particular application the optimum Si thickness is determined not just by the minimum in reflected signal but also by the minimum required signal to noise ratio required to accurately align the die.
© (1986) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
K. J. Polasko, B. F. Griffing, "Thin Silicon Films Used As Antireflection Coatings For Metal Coated Substrates", Proc. SPIE 0631, Advances in Resist Technology and Processing III, (9 July 1986); doi: 10.1117/12.963639; https://doi.org/10.1117/12.963639

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