ELECTROSTATIC CHUCK AND HE CIRCULATION SYSTEM FOR ELECTROSTATIC CHUCK

摘要

PURPOSE: An electrostatic chuck and helium circulation system thereof are provided to make helium gas flow through groove patterns smoothly and prevent leakage of helium gas into a chamber effectively. CONSTITUTION: An electrostatic chuck(132) composes a wafer table(130) installed in a chamber(120), with a block(138). A helium circulation system consists of a helium storage unit(T), a flow control unit(140), the first and second helium flow line(150,151). The first helium flow line is to supply helium gas into the system and the second one is to flow out the gas. When the second valve(152b) is opened after opening the first valve(152a) to supply helium gas, the pressure of the second flow line becomes lower than that of the first one so that the helium flow becomes more fast and the pressure of a bottom side of the wafer is decreased, when the wafer is more closely stick to the electrostatic chuck. As applying a needle valve to the second valve, the pressure and quantity of the flowing gas can be controlled.