PhotoLitho, Aberration compensation and surface charging PPS 1912P11

Electrostatic clamps are used in EUV lithography machines for high-precision wafer handling in a vacuum environment where conventional vacuum clamps have become obsolete. An electrostatic clamp can hold the wafer with a distributed force, preventing damage to the wafer with nanometer accurate reproducibility in wafer clamping functionality during its lifetime. Electrostatic clamps consist of electrode planes encapsulated in dielectric insulators biased with high voltage to establish an electrostatic holding force, thereby “chucking” the wafer. There are various unwanted effects which can affect the correct functioning of the clamp. One such effect is the charging of the surface of the clamp due to various sources. This project will deliver means to characterize the exact influence of surface charge sources in order to define possible prevention methods.