Development of a freezing pin chuck for polishing to fabricate a nonwarped substrate: Fixing characteristics to polish a quartz glass wafer

摘要

Precision polishing of thin, large substrates is essential in order to realize the manufacturing of green devices. However, most substrates warp and so cannot be fixed during polishing without deformation occurring. As such, fabricating a nonwarped substrate is difficult. In order to solve this problem, a freezing pin chuck for polishing has been developed. The present paper describes the fixing characteristics for polishing a quartz glass wafer using the development chuck. The experimental results showed that the chuck surface is cooled to less than 5°C, at which point the freezing liquid fixes the wafer firmly and the wafer profile is changed no more than 1 μm. The polishing experiment revealed that the wafer did not peel from the chuck for 60 minutes, and the fixing strength of the freezing pin chuck was determined to be sufficient for polishing. In addition, the coolant filling the space between the pins was revealed to greatly improve the fixing strength of the wafer.