TECHNICAL FIELD

Embodiments of the present invention relate, in general, to a substrate support assembly such as an electrostatic chuck that has a plasma resistant protective layer with deposited surface features.

BACKGROUND

In the semiconductor industry, devices are fabricated by a number of manufacturing processes producing structures of an ever-decreasing size. Some manufacturing processes such as plasma etch and plasma clean processes expose a substrate support such as an electrostatic chuck (ESC) (e.g., an edge of ESC during wafer processing and the full ESC during chamber cleaning) to a high-speed stream of plasma to etch or clean the substrate. The plasma may be highly corrosive, and may corrode processing chambers and other surfaces that are exposed to the plasma.

An ESC typically has surface features that are created by placing a positive mask on a surface of the ESC and then bead blasting exposed portions of the ESC through the positive mask. The positive mask is a mask that contains an exact copy of the pattern which is to remain on the wafer. The bead blasting process causes sharp edges and cracking in the ESC surface. Additionally, the spaces between formed surface features (referred to as valleys) have a high roughness that provides traps that trap particles and peaks that can break during thermal expansion. The trapped particles and broken peaks can cause particle contamination on the backsides of wafers that are held during processing.

SUMMARY

In one embodiment, an electrostatic chuck includes a thermally conductive base and a ceramic body bonded to the thermally conductive base, the ceramic body having an embedded electrode. A protective ceramic coating covers a surface of the ceramic body. Multiple deposited elliptical mesas are distributed over the surface of the ceramic body. The elliptical mesas each have rounded edges.

In one embodiment, a method of manufacturing an electrostatic chuck includes polishing a surface of a ceramic body of the electrostatic chuck to produce a polished surface. The method further includes depositing a protective ceramic coating onto the polished surface of the ceramic body to produce a coated ceramic body. The method further includes disposing a mask over the coated ceramic body, the mask comprising a plurality of elliptical holes (e.g., circular holes). The method further includes depositing a ceramic material through the plurality of elliptical holes of the mask to form a plurality of elliptical mesas on the coated ceramic body, wherein the plurality of elliptical mesas (e.g., circular mesas) have rounded edges. The mask is then removed, and the plurality of elliptical mesas are polished.

In one embodiment, a circular mask for the deposition of elliptical mesas onto a surface of an electrostatic chuck includes a body having a first diameter that is less than a second diameter of the electrostatic chuck onto which the mask is to be placed. The circular mask further includes multiple elliptical through holes in the body, the elliptical through holes having an aspect ratio of approximately 1:2 to approximately 2:1. At least one of the elliptical holes has a flared top end and a flared bottom end, wherein the flared top end is to funnel particles through the elliptical hole onto the electrostatic chuck to form an elliptical mesa on the electrostatic chuck, and wherein the flared bottom end prevents the elliptical mesa from contacting the mask.

