Tailored profile pedestal for thermo-elastically stable cooling or heating of substrates

Abstract

A shaped pedestal having a substantially convex profile for cooling a substrate or a substantially concave profile for heating a substrate. The tailored pedestal is formed of at least one continuous curvature segment that is generally elliptical, parabolic, or spherical in shape. The pedestal may be formed from more than one piecewise linear segments that are angled adjacent one another or stepped in a substantially convex or concave manner.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention The present invention relates to devices for heating or cooling substrates, such as silicon wafers. Specifically, the present invention relates to a tailored pedestal for heating or cooling a wafer during processing.[0002]2. Description of Related Art[0003]Current practices for heating and cooling wafers using a conductive media, such as gas, utilize a constant gap between the heating or cooling device and the substrate. FIG. 1 depicts a substrate 10 shown over a flat heating or cooling device 12 initially with a constant gap 14 between them. Ideally, the constant gap leads to uniform heat transfer to or from the substrate. However, if a perturbation is added, such as an initial deformed shape of the wafer surface, an unstable thermo-elastic response may occur from the non-uniform heat transfer between the device and the substrate due to the gap variation. Initial distortion in the wafer may arise from film stress or from th...

AI Technical Summary

Benefits of technology

[0008]Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a tailored profile pedestal to eliminate unstable wafer distortion during wafer heating or cooling.

[0009]It is another object of the present invention to provide a tailored profile pedestal to minimize potential wafer breakage initiating from edge defects.

Problems solved by technology

However, if a perturbation is added, such as an initial deformed shape of the wafer surface, an unstable thermo-elastic response may occur from the non-uniform heat transfer between the device and the substrate due to the gap variation.

The increase in perimeter cooling relative to the center leads to increased doming or an unstable doming response.

In both instances, these formations are unstable, runaway conditions that lead to large thermal distortion of the substrate and highly non-uniform heat transfer.

If the substrate has edge defects, such as chips or cracks, the tensile stress condition may promote crack propagation and subsequent substrate breakage.

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