Surface modification of stainless steel by Si coating was attempted to redu
ce water desorption in an evacuation process. Outgassing properties of stai
nless steel plates with and without Si coating including dependence on depo
sition condition were compared by temperature programmed desorption and thr
oughput method. The outgassing rate of a Si coated sample at optimized cond
ition was reduced to about 1/10 of the electrolytically polished 304L-type
stainless steel plate at room temperature. The most reduced outgassing spec
ies was water. H-2 and CO2 were also reduced at the same time. The Si film
was amorphous and the surface was covered with about an 8 nm thick oxide la
yer. (C) 1999 Elsevier Science Ltd. All rights reserved.