Chemical mechanical planarization pad and method of use thereof

Abstract

A web-style polishing pad includes a guide layer through which individual polishing elements protrude on one side and a flexible under-layer attached to the other side. The polishing elements may be affixed at their base to the compressible under-layer and pass through corresponding holes in the guide layer so as to be maintained and translatable in a substantially orthogonal orientation with respect to a plane defined by the guide layer.

Description

RELATED APPLICATIONS[0001]This application is a Continuation-in-Part of and claims priority to:[0002](1) U.S. patent application Ser. No. 11 / 697,622, filed 6 Apr. 2007, which is U.S. National Stage of and claims priority to: (a) PCT / US05 / 35979, filed 5 Oct. 2005, which claims the priority benefit of and incorporates by reference U.S. Provisional Application 60 / 616,944, filed 6 Oct. 2004, and U.S. Provisional Application 60 / 639,257, filed 27 Dec. 2004; and (b) PCT / US05 / 35732, filed 5 Oct. 2005, which claims the priority benefit of and incorporates by reference U.S. Provisional Application No. 60 / 631,188, filed 29 Nov. 2004, and U.S. Provisional Application No. 60 / 639,257, filed 27 Dec. 2004;[0003](2) U.S. patent application Ser. No. 11 / 576,942, filed 9 Apr. 2007, which is a U.S. National Stage of and claims priority to PCT / US05 / 35660, filed 5 Oct. 2005, which claims the priority benefit of and incorporates by reference U.S. Provisional Patent Application No. 60 / 631,189, filed 29 Nov....

AI Technical Summary

Benefits of technology

The patent describes a polishing pad that can be used on conventional CMP polishing equipment. The pad is made up of a guide layer, a porous slurry distribution layer, and a flexible under-layer. The polishing elements are inter-digitated with each other and affixed to the under-layer with each element protruding above the surface of the guide layer. The pad can be rolled onto a cylindrical support. The guide layer is made of a polymer material with holes for the polishing elements, which can be made of solid or micro-porous polymer with or without metal oxide material. The polishing elements can have a cylindrical body with or without a circular base and may have micro-features on their top surface. The under-layer is made of flexible materials such as polyurethane or PVA. The pad is used in conjunction with a compressible foam to enable full movement of the polishing elements. The technical effect of this patent is the creation of a polishing pad that can be easily installed onto conventional CMP polishing equipment and used to polish materials.

Problems solved by technology

However, this reduces the overall strength of the polishing pad, making it more flexible and thus reducing its planarization characteristic.

Typically, hard (i.e., stiff) pads provide good planarization, but are associated with poor with-in wafer non-uniformity (WIWNU) film removal.

Soft (i.e., flexible) pads, on the other hand, provide polishing with good WIWNU film removal characteristics, but poor planarization characteristics.

Nevertheless, this approach tends to degrade planarization performance when compared to use of a hard pad alone.

The consequence of dishing is an undesirable loss of metal thickness, leading to poor device performance.

Pads may be made stiffer by reducing the number of pores and / or grooves in the pad, however, this can lead to different consequences, for example poor slurry distribution.

In copper processing, however, WIWNU directly impacts over-polishing (i.e., the time between complete removal of copper on any one area versus complete removal from across an entire wafer surface) and, hence, metal loss and, similarly, planarization as expressed by metal loss.

This leads to variability in the metal remaining in the interconnect structures and impacts performance of the integrated circuit.

Frequent changes in pads also lead to reduced productivity of the overall process

Not all polishing pads can be formed into rolls for use with web processing CMP equipment.

For example, stiff pads (such as IC pads supplied by Rohm & Haas) cannot be easily formed into a roll, yet, as discussed above, the inherent stiffness of such pads is required if good planarization characteristics are desired.

CMP pads for planarization offered by other manufacturers, such as the D100 pads offered by Cabot Corp. and the FAST™ polishing pads produced by PPG Industries, have similar limitations.

There are, therefore, significant constraints with respect to implementing web-style CMP equipment architectures.

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