METHOD AND CONTROL SYSTEM FOR PREVENTION OF SCRATCH FLAW ON BACKSIDE OF WAFER BY TAKEOUT ARM OF STEPPER MACHINE

摘要

PROBLEM TO BE SOLVED: To obtain a method and a control system in which a frictional force between the backside of a wafer and a suction head is reduced when the wafer collides with the side part of a cassette holder by a method wherein, before the wafer is inserted into the cassette holder, a negative pressure inside the suction head is released. SOLUTION: A negative-pressure release controller 500 is provided with a timing control circuit 530 which is connected to a first signal delay circuit 510 and to a second signal delay circuit 520 and which generates a first delay signal and a second delay signal. By the timing control circuit 530 and by a light shutoff-type electronic switching circuit 540, a second control signal and a first control signal which is generated by a microcontroller are received, a negative-pressure solenoid, valve is controlled, and the negative-pressure release and negative-pressure holding sequence of a suction head at a takeout arm is controlled. Then, the second control signal releases a negative pressure until a second prescribed time when the takeout arm reaches a second position since the finish of a first prescribed time when the takeout arm starts to be separated from a first position.