Polishing apparatus

Abstract

A polishing apparatus is used to polish a workpiece such as a semiconductor wafer. The polishing apparatus includes a polishing table having a polishing surface, a dresser for dressing the polishing surface, a substrate holder for holding and pressing a substrate against the polishing surface to polish the substrate with relative movement between the polishing surface and the substrate. The dresser includes a first dressing member and a second dressing member. The first dressing member has a circular shape having a diameter larger than a diameter of the substrate. The second dressing member is shaped so as to surround the first dressing member. The first dressing member and the second dressing member are operable to come into contact with the polishing surface independently of each other.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a polishing apparatus for polishing a workpiece, such as a semiconductor wafer (e.g., silicon wafer), and more particularly to a polishing apparatus having a dresser for dressing a polishing surface of a polishing table. [0003] 2. Description of the Related Art [0004] With a recent progress in semiconductor devices toward finer structure and higher integration, a distance between interconnects is becoming smaller and smaller. Especially, when forming a circuit pattern by optical lithography with a line width of not more than 0.5 μm, surfaces, on which pattern images are to be focused by a stepper, are required to be flat because depth of focus is small. Thus, in order to achieve flat surfaces, a polishing apparatus has been widely used to polish the surfaces. [0005] This type of polishing apparatus includes a polishing table having a polishing pad attached to an upper surface thereof...

AI Technical Summary

Benefits of technology

[0010] The present invention has been made in view of the above drawbacks. It is therefore an object of the present invention to provide a polishing apparatus which can maintain a polishing surface of a polishing table in suitable conditions during polishing, can hold a shape of the polishing surface unchanged even after the polishing surface is scraped off, and can polish a substrate at a high removal rate while suppressing an increase in temperature of the polishing surface.

[0011] Further, another object of the present invention is to provide a polishing apparatus which can shorten downtime of the apparatus required for bringing a new polishing pad closer to a ready condition for practical use after placement of a polishing pad.

Problems solved by technology

This means that it is difficult to achieve both of these effects with a single dresser.

However, dummy polishing requires cleaning of the dummy wafers and, as a result, downtime of the apparatus would be increased.

In addition, a temperature of the polishing surface during polishing also affects the removal rate.

Further, an increase in temperature of the polishing surface results in a decrease in hardness of the resin polishing pad forming the polishing surface, thus adversely affecting flattening capability.

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