Focus ring and plasma processing apparatus

Abstract

A focus ring to be detachably attached to a top surface of an outer peripheral portion of a mounting table in a processing chamber, includes: an annular main body having a back surface to be attached to the top surface of the outer peripheral portion of the mounting table. And a thermally conductive sheet fixed to the annular main body, the thermally conductive sheet being interposed between the annular main body and the top surface of the outer peripheral portion of the mounting. The thermally conductive sheet is fixed as one unit to the annular main body by coating an unvulcanized rubber on one surface of the thermally conductive sheet, bringing said one surface into contact with the annular main body, and heating the thermally conductive sheet and the annular main body to vulcanize and to adhere the thermally conductive sheet to the annular main body.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to Japanese Patent Application No. 2013-222563 filed on Oct. 25, 2013, the entire contents of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]Various aspect and embodiments of the present invention relate to a focus ring and a plasma processing apparatus.BACKGROUND OF THE INVENTION[0003]In a plasma processing apparatus used in a semiconductor device manufacturing process, a substrate to be processed such as a semiconductor wafer or the like is mounted on a substrate mounting table provided in a processing chamber, and a high frequency voltage is applied to the processing chamber under a vacuum environment. Accordingly, a plasma is generated in the processing chamber, and, e.g., etching of the substrate is carried out. In such a plasma processing apparatus, a focus ring is provided at an outer peripheral portion of the substrate mounted on the mounting table to improve in-plane unifor...

AI Technical Summary

Benefits of technology

The present invention provides a focus ring that can be detachably attached to a mounting table for processing substrates. The focus ring includes an annular main body and a thermally conductive sheet fixed to the back surface of the main body using an unvulcanized rubber adhesive. The thermally conductive sheet is interposed between the main body and the table surface in case of attachment and ensures sufficient heat transfer without bubbling. The technical effect of this invention is effective heat transfer through a reliable attachment of the thermally conductive sheet to the focus ring.

Problems solved by technology

In the above configuration, it is general that a vacuum insulating layer is formed between the focus ring and a top surface of the outer peripheral portion of the mounting table in the depressurized processing chamber and, thus, thermal conductivity between the focus ring and the top surface of the outer peripheral portion of the mounting table becomes considerably poor.

When the vacuum insulating layer is formed, it is difficult to cool the focus ring, so that the temperature of the focus ring is increased.

As a result, an etching rate and a hole forming property (in which a hole can be reliably formed to a predetermined depth by etching) of the outer peripheral portion of the semiconductor wafer which is close to the focus ring become poorer, and an etching aspect ratio become smaller.

In other words, the etching characteristics of the outer peripheral portion of the semiconductor wafer become poorer.

Accordingly, it is difficult to perform uniform etching on a plurality of semiconductor wafers in a same lot.

In the case of attaching the thermally conductive sheet, existence of even an extremely small amount of air between the focus ring and the thermally conductive sheet or between the thermally conductive sheet and the portion above the outer peripheral portion of the mounting table leads to insufficient thermal conductivity and insufficient cooling of the focus ring.

As the focus ring is consumed, the in-plane uniformity in the processing of the semiconductor wafer becomes poorer.

However, when the consumed focus ring is detached for exchange from the top surface of the outer peripheral portion of the mounting table, the thermally conductive sheet firmly adhered by the mechanical pressing unit may be broken.

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