Optics: measuring and testing – Photometers
Reexamination Certificate
2007-05-16
2010-02-16
Stafira, Michael P (Department: 2886)
Optics: measuring and testing
Photometers
C356S392000
Reexamination Certificate
active
07663743
ABSTRACT:
In a first aspect according to the invention there is provided a sensing system100, suitable for sensing the stage of processing of a wafer200, said sensing system100comprising receiving means110in the form of a first photosensitive device110aand a second photosensitive device110b, detector120, a comparator130and a control system in the form of a programmable logic controller (PLC)140. The first photosensitive device110areceives light from the wafer200, while the second photosensitive device110breceives ambient light. The light received by the first photosensitive device110acan be incident ambient light reflected off the surface of the wafer200, refracted light radiating through the wafer200, filtered light radiating through the wafer200or translucent light radiating through the wafer200. It is further envisaged that the received light may be filtered through filters (not shown) before being received by the photosensitive devices110a&b. The detector120then generates a wafer control signal associated with the color(s) of the light received from the wafer200. The wafer control signal produced by the detector120is then compared by a comparator130. Once the comparator130has compared the wafer control signal to the predetermined values, this indirectly indicates the level of processing of the wafer200. The PLC140then controls the further processing of the wafer200according to the result of the comparison.
REFERENCES:
patent: 5072128 (1991-12-01), Hayano et al.
Stafira Michael P
Systems On Silicon Manufacturing Co. Pte. Ltd.
Wells St. John P.S.
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