Study of the Warp Removal Process for a Thin Substrate: Development of a Correction Processing System Using a Freezing Pin Chuck

Abstract

High precision is required for thin substrates used in the manufacturing processes for semiconductor devices and flat panel displays, and the required precision for substrate warp becomes more stringent every year. However, it is difficult to remove the warp efficiently utilizing the current grinding and polishing methods. One of the causes is deformation of the substrate during clamping. For this reason, a freezing pin chuck has been developed as a clamping technology that does not deform the substrate. A freezing pin chuck that uses the adhesion of frozen liquid can be designed with a substrate clamping force that can withstand the processing force. In this study, we developed a correction processing system that utilizes a freezing pin chuck to remove the warp of the thin substrate. The developed correction processing system can perform the grinding and polishing processes while clamping the substrate without deformation using a freezing pin chuck, and has a non-deformation clamping capacity that suppresses substrate deformation to 1/10 or less for a substrate with an initial warp of 100 μm. In addition, the newly devised additional application method has made it possible to increase the clampable warp by approximately twice that of the ordinal application method, and improves the clamping force. The results of the grinding and polishing experiments revealed that the correction processing system can obtain the same planarized profile as that when a vacuum pin chuck is utilized, while cooling the substrate surface during processing to 5°C or less, and also demonstrated that it can be applied to correction processing.