Method of determining a dechucking voltage which nullifies a residual electrostatic force between an electrostatic chuck and a wafer

In a vacuum processing environment, a method of releasing a workpiece from an electrostatic chuck, wherein the chuck includes dielectric elements and at least one electrode energized with a first voltage to electrostatically attract the workpiece to the chuck with a first electrostatic force, and wherein the chuck further includes a gas passageway therethrough, the method comprising the steps of:

• supplying a heat transmission gas via the gas passageway between the workpiece and chuck while the workpiece is held to the chuck by electrostatic attraction;
• while reducing the supply of heat transmission gas to the passageway, energizing the electrode with a second voltage of the same polarity as said first voltage, of a magnitude smaller than the first voltage, and which would result in a second electrostatic attractive force smaller than said first force;
• and thereafter physically removing the workpiece from the chuck.

In a vacuum processing environment, a method of releasing a workpiece from an electrostatic chuck, wherein the chuck includes dielectric elements and at least one electrode energized with a first voltage to electrostatically attract the workpiece to the chuck with a first electrostatic force, and wherein the chuck further includes a gas passageway therethrough, the method comprising the steps of:

• supplying a heat transmission gas via the gas passageway between the workpiece and chuck while the workpiece is held to the chuck by electrostatic attraction;
• while reducing the supply of heat transmission gas to the passageway, energizing the electrode with a second voltage, of a magnitude smaller than said first voltage, and which would result in a reduced electrostatic attraction permitting a leakage rate of the heat transmission gas into the vacuum processing environment exceeding a predetermined level;
• and thereafter physically removing the wafer from the chuck.