Recycling SiC Focus Rings for Reactive Ion Etching Equipment by Insertless Diffusion Bonding using Hot Isostatic Pressing

Abstract

SiC focus rings are mount on the stage at the surround of wafer in the reactive ion etching chamber, in order to make the etching rate uniform. SiC is used for the material of focus ring because it has higher plasma resistance than Si. We investigated a new method to recycle SiC without using the chemical vapor deposition (CVD) method. The recycling process consists of grinding, dry cleaning, hot isostatic pressing (HIP), atmospheric burning, and aqueous solution cleaning. As a result, diffusion bonding with a tensile strength of 100 kg cm−2 or more was realized by reducing the surface roughness at the diffusion bonding surface to 0.1 μm or less. It was confirmed that the SiC surface was oxidized with thickness 135 nm by atmospheric burning in air ambience. It was also confirmed that the oxide layer at the SiC surface was completely removed by the aqueous solution cleaning. We have reduced the cost to 50% for SiC focus ring replacement by using the recycle method.