Study of a mechanically clamped cryo-chuck device in a high density plasmafor deep anisotropic etching of silicon

This article presents a study concerning a cryo-chuck device used in an ind uctively coupled plasma reactor for deep anisotropic etching of narrow tren ches (2 mum wide) in silicon wafers of 5 in, in diameter. Thermal mechanism s in a mechanically clamped cryo-chuck system have been studied. First, waf er deformations have been measured in the chuck device. Deformations occur because of the helium backside pressure allowing thermal transfer to cool t he wafer. In a second step, these deformations have been used in calculatio ns considering the heat transfers in the substrate. In a last step, in situ temperature measurements have been made on wafers during a process using a LUXTRON (R) probe. This study shows the influence of the backside helium g ap variation and the clamping ring temperature on the uniformity of substra te cooling. (C) 2001 American Vacuum Society.