US Patent 7975997 Supporting pin

A supporting pin which can cancel thermal expansion of a mounting table (hot plate) includes an upper supporting pin and a lower supporting pin, wherein the upper supporting pin and the lower supporting pin are independent of each other, the upper supporting pin is retained by the penetrating hole of the mounting table, and the lower supporting pin is attached to an elevator mechanism. Since the lower end of the upper supporting pin and the upper end of the lower supporting pin are in contact with each other, the operation of the supporting pin can be normally performed even when thermal expansion of the hot plate occurs.