The invention relates to a crucible for the crystallization of silicon and
to the preparation and application of release coatings for crucibles used
in the handling of molten materials that are solidified in the crucible
and then removed as ingots, and more particularly to release coatings for
crucibles used in the solidification of polycrystalline silicon. The
objective of the inventor was to provide a crucible which does not
require the preparation of a very thick coating at the end user
facilities, which is faster and cheaper to produce and which presents a
stronger coating with an improved adherence to the walls. It has now been
found that these problems can be solved with a crucible for the
crystallization of silicon comprising a) a base body comprising a bottom
surface and side walls defining an inner volume; b) an intermediate layer
comprising 50 to 100 wt. % of silica at the surface of the side walls
facing the inner volume; and c) a surface layer comprising 50 to 100 wt.
% of silicon nitride, up to 50 wt. % of silicon dioxide and up to 20 wt %
of silicon on the top of the intermediate layer.