研磨用冷凍ピンチャックの開発 (第2報)

—試作冷凍ピンチャックの冷却特性と研磨への適用—

抄録

It is difficult to fabricate a nonwarped substrate, because a thin wafer cannot be fixed without deformation occuring. To resolve this matter, a silicon-carbide-ceramics freezing pin chuck has been developed. This paper describes the structure and cooling characteritics of a prototype freezing pin chuck, the uniform application method of fleezing requid on pin tops, applicability of polishing and low-temperature polishing. The prototype freezing pin chuck has double spiral flow channels built inside. These structure enable to cool down a quartz glass surface less than 5°C where frozen liquid does not melt till the polishing temperature of 30°C. The newly devised application method can form uniform droplets with the height of about 160μm on the whole chuck by blowing mist in the upper and oblique direction. When the quartz glass surface is cooled less than 5°C and the coolant fills spaces between pins, it becomes possible to polish a quartz glass for 60 min with cerium slurry under the pressure of 4.8kPa and the revolution speed of 50 min^-1. In addition, it was shown that the low-temperature polishing less than 10°C with the cerium slurry has the performance of the same removal rate as that at the ordinary temperature. Accordingly, the matter of peeling of a wafer due to polishing heat was resolved without reducing the removal rate.