Optimization of a TEOS addition on plasma resistance of YAG ceramics

The influence of tetraethyl orthosilicate (TEOS) on the plasma etching behavior of yttrium aluminum garnet (Y3Al5O12, yttrium aluminum garnet [YAG]) was systematically studied. Dense YAG bulk specimens were hot‐press sintered at a relatively low temperature of 1450°C for 2 h under 20 MPa, using TEOS as a sintering additive. The etching properties of YAG ceramics, doped with different TEOS contents, were evaluated using an inductively coupled plasma etcher with an incident plasma power of 1500 W for up to 2 h. It was observed that the addition of .3 wt.% TEOS optimally reduced the surface roughness of YAG ceramics post‐plasma etching. Transmission electron microscopy and X‐ray fluorescence tests clarified that a densification‐promoting TEOS‐induced residual Si‐rich phase at the triple junction for the over‐doped TEOS (≥.5 wt.%) specimen acts as a pit‐initiation site during plasma etching, which eventually results in increased surface roughness.