Other

John G Merullo

Gary B Tepolt

In the coating apparatus disclosed herein, a semiconductor wafer is held on a vacuum chuck mounted on the spindle of a bidirectional servo motor. The servo motor is energized by a servo amplifier in response to the amplitude of the control signal provided to the amplifier. Dispensing means are provided for placing coating material on wafer held in the chuck. An oscillator is provided generating a periodic output signal of controllable amplitude and period. A programmable sequencer is operative in a first time period for appying the oscillatory output signal as a control signal to the servo amplifier thereby to angularly oscillate a wafer held in the chuck and for operating the dispensing means to place a predetermined amount of coating material on the wafer. The sequencing means is operative in a later time period for applying a fixed higher amplitude control signal to the servo amplifier thereby to spin the wafer and spread the coating material.

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Andover, MA, United States of America

John G Merullo