WAFER POSITION DETECTION DEVICE

摘要

PURPOSE:To easily detect the orientation flat OF of a wafer without contact by using an optical method. CONSTITUTION:Pulse driving is applied to a board by a command from an information processing device 10. Irradiation light 6 is condensed 8 through a transparent adhesive sheet 4 and the image of the end finge 5a of a wafer is imaged on a photoelectric conversion element 7. A detection signal is processed 10 by binary code 9. The input signal to the device 10 is synchronized with the output signal (driving command). Now, the information from the element 7 is read to obtain a light and shade inversion bit position and observation is continued until a pulse motor run by one turn and the position of the end fringe 5b of the wafer is obtained. Next, the maximum value a and the minimum value b of average slope of each bit position are calculated and the maximum point c of the bit position is decided as OF5a and detected at the middle of the maximum and minimum values and the number of pulses of the motor 1 at the maximum point c is computed to know the position of the OF5a of the wafer.