BACKGROUND

Field

Embodiments of the present disclosure generally relate to the fabrication of integrated circuits and to apparatus for use within a substrate processing chamber to improve film thickness uniformity.

Description of the Related Art

A primary goal of substrate processing is to obtain the largest useful surface area, and as a result the greatest number of chips, possible from each substrate. Some factors to consider include processing variables that effect the uniformity and thickness of the layer deposited on the substrate, and contaminants that can attach to the substrate and render all or a portion of the substrate useless. Controlling these factors maximizes the useful surface area for each substrate processed.

Recent developments in semiconductor processing have caused interest in new treatment applications that require low ion current and high ion energy. This enables deep treatment without growing a film. To satisfy the low ion current and high ion energy requirement, bias power exceeding source power by 10-20 times or more has been used. With such a high bias-to source power ratio, the plasma density and the plasma current to the substrate is affected. The affected plasma current and density result in film thickening toward the substrate edge.

Edge rings have traditionally been used to improve film thickness uniformity by altering the deposition rate near an edge of a substrate. However, typical edge rings still result in poor uniformity and deposition rates near the extreme edges of the substrate. Accordingly, there is a need in the art for edge rings that produce higher uniformity.

SUMMARY

Embodiments of the present disclosure generally relate to an apparatus for improving the film thickness near an edge of a substrate when during low ion current and high ion energy applications.

In one embodiment, an apparatus for substrate processing includes an edge ring and an overhang ring. The edge ring includes a bottom surface, an upper surface, and a groove disposed in the upper surface. The overhang ring is disposed in the groove and includes a first portion extending from the groove and a second portion connected to the first portion and extending radially inward.

In another embodiment, an apparatus for substrate processing includes an edge ring and an overhang ring. The edge ring includes a bottom surface, an upper surface, a central opening, and a groove disposed in the upper surface. The overhang ring is disposed in the groove and includes a first portion extending upwards from the groove and a second portion extending radially inward toward a central axis of the overhang ring.

In yet another embodiment, an apparatus for substrate processing includes an edge ring and an overhang ring. The edge ring further includes a support surface, an upper surface, groove disposed in the upper surface, and a plurality of tabs disposed on the upper surface. The overhang ring is disposed in the groove and further includes a first portion extending from the groove and a second portion connected to the first portion and extending radially inward.

