Patent ID: 7292426

Claim:
A substrate holding system having a chuck for vacuum attraction and electrostatic attraction of a substrate, said system comprising: a ring-like rim for carrying a substrate thereon; a plurality of first protrusions, disposed inside said rim, for carrying the substrate thereon; a plurality of second protrusions, disposed inside said rim, for carrying the substrate thereon, wherein a substrate carrying surface area of at least one first protrusion is smaller than a substrate carrying surface area of at least one second protrusion and wherein a smallest interval between the first protrusions is smaller than a smallest interval between the second protrusions; an exhaust system for exhausting a clearance between said chuck and the substrate; an electrode for electrostatic attraction and being provided in said chuck; a power supplying system for supplying a power to said electrode; a measuring system for measuring a pressure in the clearance; and a control system for controlling the power supply of said power supplying system on the basis the measurement made by said measuring system.