12 February 1997 Film stress and geometry effects in chrome photomask cleaning damage
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As design rules shrink, photomask blank material characteristics play a more significant role in successful mask fabrication. Chromium-based absorber film stress is a key material attribute in determining mask quality. A photomask is cleaned several times during manufacture by various techniques incorporating part or all of the following processes: strong acids, bases, high pressure sprays, mechanical brushes, sonic agitation. In such aggressive environments, electrostatic discharge damage (ESD) and mechanical damage can occur. Chromium-based film dependence on sputter deposition parameters was studied here. Photoblank flatness, measured by optical interferometry, was used to quantify the stress. Blanks with various chrome film stresses were patterned with features combining different geometry types. The masks were then subjected to multiple cleaning cycles and inspected after each cycle. The results demonstrate how mask damage is related to the film mechanical properties (which are controllable by sputter deposition parameters) and the pattern itself (which is not controllable).
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
H. Ufuk Alpay, H. Ufuk Alpay, James L. Wood, James L. Wood, Franklin D. Kalk, Franklin D. Kalk, } "Film stress and geometry effects in chrome photomask cleaning damage", Proc. SPIE 3236, 17th Annual BACUS Symposium on Photomask Technology and Management, (12 February 1997); doi: 10.1117/12.301230; https://doi.org/10.1117/12.301230

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