Process kit for erosion resistance enhancement

Abstract

A process kit is described that resists plasma erosion, preserves the spatial uniformity of plasma properties, reduces particle generation in the chamber, and significantly enhances the lifetime of the process kit. A layer of polymer material covers the top surface of the process kit. The polymer material is fluorocarbon-based and not reactive with the species in the plasma. The polymer material not only protects the process kit from progressive erosion, but also prevents the generation of particles in the chamber. The polymer material has similar permittivity to that of the process kit and therefore maintains the spatial uniformity of plasma properties, e.g., etch rate, near the wafer perimeter. The thickness of the layer is controlled between 0.5 and 1.5 mm such that the difference between its coefficient of thermal expansion and that of the process kit will not cause the layer to peel off the process kit's top surface.

Description

FIELD OF THE INVENTION [0001] The present invention generally relates to a process kit surrounding a semiconductor workpiece in a plasma chamber that can improve the spatial uniformity of plasma energy distribution over the workpiece surface. More specifically, the present invention relates to a film of fluorocarbon-based polymer covering the top surface of the process kit that can resist plasma-related erosion, reduce particulate contamination during etching, and prolong the lifetime of the process kit. BACKGROUND OF THE INVENTION [0002] Semiconductor fabrication includes a series of processes that produce numerous identical integrated circuits in a semiconductor workpiece, e.g., a silicon wafer, in accordance with a circuit design. One important process is plasma etching, which is a process of transferring a pattern in a layer of mask material into another layer under the mask, such as a layer of conductive or dielectric material, by removing the layered material from the wafer su...

AI Technical Summary

Benefits of technology

[0014] In a first aspect of the present invention, a portion of the top surface of the process kit is covered with a layer of fluorocarbon-based polymer. Since the polymer material is fluorocarbon-based, it is less likely to be affected by the fluorocarbon-based plasma. Therefore, this layer effectively insulates the process kit from erosion by the reactive species in the plasma and substantially prolongs the lifetime of the process kit.

[0016] In a third aspect of the invention, the layer of fluorocarbon-based polymer is controlled to be thin, e.g., 1.5 mm, so as to minimize the impact of the Coefficient of the Thermal Expansion (CTE) difference between the polymer material and the process kit. Even though CTE of the polymer material is significantly different from that of the process kit, its limited thickness minimizes the effect of temperature variation on the polymer layer.

Problems solved by technology

Therefore, this layer effectively insulates the process kit from erosion by the reactive species in the plasma and substantially prolongs the lifetime of the process kit.

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