Memc Electronic Materials, Inc.

Paride Corbellini

Ezio Bovio

Giovanni Negri

Peter D Albrecht

Luca Moiraghi

Marco Morganti

A wafer polishing apparatus for polishing a semiconductor wafer. The polisher comprises a base (), a turntable (), a polishing pad () and a drive mechanism () for driven rotation of a polishing head (). The polishing head is adapted to hold at least one wafer () for engaging a front surface of the wafer with a work surface of the polishing pad. A spherical bearing assembly () mounts the polishing head () on the drive mechanism for pivoting of the polishing head about a gimbal point (p) lying no higher than the work surface when the polishing head holds the wafer in engagement with the polishing pad. This pivoting allowing the plane of the front surface of the wafer to continuously align itself to equalize polishing pressure over the front surface of the wafer, while rotation of the polishing head is driven by the driving mechanism. This maintains the front surface and work surface in a continuously parallel relationship for more uniform polishing of a semiconductor wafer, particularly near the lateral edge of the wafer. A cassette of wafers and method of polishing are also disclosed.

Semiconductor wafer, polishing apparatus and method

The method comprises the steps of mounting a first wafer () on the mounting member () and securing the mounting member to the hub () by drawing a vacuum at a first vacuum pressure through the hub; rotating the hub about the hub axis (AH), rotating a polishing pad () mounted on the turntable () about the turntable axis (at), and bringing a surface of the wafer () and the polishing pad into contact with each other. The wafer () is demounted, and the shape of the polished wafer is determined. A second vacuum pressure is selected using the information obtained. A successive wafer is polished according to the same method as the first wafer except that the second vacuum pressure is substituted for the first vacuum pressure. The second vacuum pressure is sufficient to deform the mounting member () thereby deform the wafer to improve the flatness and parallelism of the surfaces of the successive wafer.

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Trecate, Italy

Paride Corbellini