Substrate centering apparatus and method

An apparatus for supporting and centering a substrate, comprising:

• a substrate chuck having:
• a plurality of pins, each pin having a top surface and a longitudinal axis of rotation, the top surfaces of the pins defining a plane in which the substrate is supported, each pin having a tab mounted eccentrically with respect to the pin's longitudinal axis of rotation at the top surface of the pin and extending upwardly relative to the top surface of the pin;
• a pin rotation mechanism adapted to rotate each pin about a longitudinal axis of the respective pin, the pin rotation mechanism rotating the pins between a first position in which the tabs define an envelope that is larger than a circumference of the substrate and a second position in which the tabs define a centered position for the substrate;
• a pin lift/lower mechanism adapted to move the pins along the longitudinal axes of the pins;
• and
• a controller operatively coupled to the pin rotation mechanism and the pin lift/lower mechanism and adapted to control the pin rotation mechanism and the pin lift/lower mechanism such that the pin rotation mechanism rotates the pins from the first position to the second position while the pin lift/lower mechanism is lowering the pins.

A method of centering a substrate, comprising:

• supporting the substrate on a plurality of pins;
• rotating each pin in a first direction about a longitudinal axis of the pin to bring a tab on each pin into contact with the substrate;
• and
• rotating each pin in a second direction that is opposite to the first direction to move the tabs out of contact with the substrate, leaving the substrate in a centered position.