AIXTRON CRIUS II - Molybdenum Parts; Sic-Coated Graphite Parts

AIXTRON - Dokumentation CONFIDENTIAL 147
6
crius_II_en_00, Edition 06/2010
System Manual Maintenance
CRIUS II Cleaning procedures
6.6.2 SiC-coated graphite parts
High-temperature baking
AIXTRON recommends to use high-temperature baking. The baking condi-
tions must be adapted to the SiC coating.
Etching
Etching in aqua regia is also possible except for susceptors. See
Chapter 6.6.1 Fused quartz glass parts,  146.
6.6.3 Molybdenum parts
Solution
AIXTRON recommends using a solution of 90% KOH and 10% H
2
O
2
.
KOH is prepared from KOH pellets (30% in weight) in DI water.
However, the etchant also partly attacks the molybdenum and the coating is
lifted off rather than dissolved.
Etching time
Account few hours
Rinsing and Drying
See Chapter 6.6.1 Fused quartz glass parts,  146.
NOTE:
Do not use etching for susceptors!
The SiC coating prevents diffusion of the etching solution in the graphite
bulk.
But any fracture or chip in the SiC will cause issues as the etching solu-
tion will locally diffuse into the graphite bulk where it would be difficult
to rinse away and/or dry off.