| 摘要 |
A table positioning apparatus suitable for use in an electron beam exposure system. A movable table holds a wafer or other work piece. The table is driven by a motor in response to a motor drive signal to position the table at different locations. An optical position measuring transducer is located in fixed relation to the table to establish a reference position for the table in a local region. The transducer provides a position signal as a function of the table position in the local region. An amplifier is provided which is responsive to the position signal to produce a servo signal. A motor drive circuit provides the motor drive signal for driving the motor in response to the servo signal so that the table is driven to the reference position. At the reference position, a reset signal is provided to reset interferometers in both X and Y axes. |
