Patent ID: 7248456
Filing Date: 2007-07-24
Classification: H01L,Y10T

Abstract:
1. An electrostatic chuck comprising: a circular ceramic plate having an electrostatic attractive electrode; a mounting surface for supporting a wafer formed on one of the main surfaces of the circular ceramic plate; an annular gas groove formed on the periphery of the mounting surface in the form of concentric circles and a first gas inlet which communicates with the annular gas groove; and a circular gas recess formed inside the circular ceramic plate, and a second gas inlet which communicates with the circular gas recess, wherein the annular gas groove and the circular gas recess are independently separated from each other by a first annular rib protrusion, wherein a plurality of dotted protrusions are disposed within both the annular gas groove and the circular gas recess, wherein the circular gas recess has a diameter which is set to 70 to 95% of the outer diameter of the mounting surface, wherein the first annular rib protrusion surrounded by the outer circumference of the circular gas recess and the inner circumference of the annular gas groove has a width in a range of 0.5 to 5 mm, and a second annular rib protrusion surrounded by the outer circumference of the mounting surface and the outer circumference of the annular gas groove has a width in a range of 1 to 5 mm, wherein the ratio S the ratio S