Infineon Technologies Ag

Benno Utess

Walter Glashauser

Andreas Purath

Peter Faustmann

A method and a configuration for conditioning a polishing pad surface are described. The method includes measuring a rotation table current or voltage as an input for a motor driving the rotation of the polishing pad versus a rotating conditioning head. The electrical power input is used as a measure of an actual abrasion effective in regenerating the polishing pad. Since the polishing pad commonly deteriorates by repeated usage, i.e. debris settles down onto its surface, the abrasion efficiency decreases. The method issues a warning signal, in response to the electrical power input exceeding a limit, to take actions for maintaining the uniformity of the conditioning process. The polishing pad rotation can be accelerated or the conditioning head pressure force or rotation can be increased in response to the warning signal. Therefore, the polishing pad can be conditioned.

Method and configuration for conditioning a polishing pad surface

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

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Dresden, Germany

Benno Utess