Method and apparatus for reduction of voltage potential spike during dechucking
AssigneeLam Research Corporation
InventorsBrian McMillin, Jose V. Tong, Yen-Kun Victor Wang
Life of this patent
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Abstract
Provided is a substrate dechucking system of a plasma processing chamber adapted to remove a substrate from an ESC with reduction in voltage potential spike during dechucking of the substrate.
Claims20
A method of dechucking a substrate from an electrostatic chuck in a plasma processing chamber, the method comprising:
- supplying process gas into the chamber;
- energizing the process gas into a plasma state;
- maintaining the plasma chamber at a vacuum pressure and low RF power to produce a plasma sheath above the substrate of 2 mm or greater thickness;
- lifting the substrate above a support surface of the electrostatic chuck to a mid-lift position within the plasma sheath which does not induce plasma instability and maintaining the substrate at the mid-lift position;
- extinguishing the plasma;
- and
- lifting the substrate above the mid-lift position to an upper position at which the substrate can be removed from the plasma chamber.
The method of claim 5, wherein He gas is supplied to the underside of the substrate while plasma etching the openings in the dielectric material, the method further comprising terminating supply of the He gas before the substrate is raised to the mid-lift position.
A pneumatic lift mechanism for a plasma reactor wherein lift pins raise and lower a substrate in at least three positions with respect to an upper surface of an electrostatic chuck, the lift mechanism comprising:
- a housing having an upper chamber and a lower chamber;
- an upper piston slidably mounted to move up and down in the upper chamber;
- a lower piston slidably mounted to move up and down in the lower chamber, the lower chamber comprising a hard stop defining an upper limit of travel of the lower piston;
- the three positions comprising (1) a lower position at which the upper piston positions the lift pins below the upper surface of the electrostatic chuck, (2) a mid-lift position at which the lower piston is in contact with the hard stop and a shaft of the lower piston raises the upper piston, and (3) an up position at which the substrate can be removed from the plasma chamber;
- and
- wherein the upper piston and the lower piston are independently pneumatically operated.
Dependencies are inferred from the claim text.