| 摘要 |
An in-situ measurement of thickness profiles of polishing pads ( 1 ) used in chemical mechanical polishing (CMP) is enabled by arranging sensors ( 7 ) for measuring distances together with a conditioner ( 6 ). The sensors ( 7 ) are provided as e.g. laser sensors ( 7 a-c) performing an indirect measurement from a calibrated height level above the pad ( 1 ) surface or as e.g. laser ( 7 a-c) or ultrasonic sensors ( 7 e) performing a direct thickness measurement from the pad surface to the pad-platen contact surface. A thickness profile ( 10 ) is obtained by co-moving the sensor (7a , 7 b) with the conditioner ( 6 ) during conditioning or by leading a sensor ( 7 c) along a guide-rail ( 14 ) above the pad surface ( 1 ) with e.g. a constant distance. A reference distance measurement to the polishing platen ( 2 ) can be achieved by a second sensor ( 7 d) mounted at a position, where there is no pad on the platen ( 2 ), e.g. a hole or the edge. Using the arrangement a disadvantageous thickness profile ( 10 ) with a steep slope resulting in polishing inhomogeneities affecting semiconductor device ( 4 ) surfaces can be detected and a warning signal be issued. A destructing micrometer measurement is not necessary, thus prolonging the pad ( 1 ) lifetime and increasing the device yield.
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