Crucible for solidifying a silicon ingot
AssigneeCommissariat A L'energie Atomique Et Aux Energies Alternatives
InventorsCharles Huguet, Severine Bailly, Virginie Brize
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Abstract
The present invention concerns a crucible for solidifying a silicon ingot from molten silicon, characterized in that it is coated at least partially on the inner surface thereof with an outer layer provided in the form of a stack of laminations, each lamination having a thickness varying from 5 to 150 μm, and being formed from a material obtained by thermal decomposition of polysilazane(s) and/or polysiloxane(s) and wherein inorganic particles are embedded having a size varying from 50 μm to 200 μm. The present invention further concerns a method for preparing such crucibles.
Claims23
A crucible useful for solidifying a silicon ingot from molten silicon, wherein it is coated at least partially on its inner surface with an outer layer that is in the form of a stack of strata, each stratum having a thickness varying from 5 to 150 μm, and being formed from a material obtained by thermal decomposition of polysilazane(s) and/or polysiloxane(s) and in which inorganic particles having a size that varies from 50 nm to 200 μm are incorporated.
A process for forming a high-purity non-stick coating on the inner surface of a crucible useful for solidifying a silicon ingot from molten silicon, wherein said coating is obtained via
- (a) the formation of at least one stratum according to a treatment comprising:
- (1) at least once the sequence of the steps:
- (i) bringing the inner surface of said crucible into contact with a solution comprising at least one polysilazane and/or one polysiloxane, and additionally containing a particulate material, the particles of which have a size varying from 50 nm to 200 μm, in particulate material/polysilazane and/or polysiloxane proportions ranging from 10% to 70% by volume;
- (ii) condensation-crosslinking of said solution by heat treatment;
- and
- (iii) optionally a pre-pyrolysis in air at a temperature ranging from 270° C. to 700° C.;
- (2) a pyrolysis under controlled atmosphere and controlled temperature, at a temperature above 700° C. for at least 1 hour and, optionally;
- (3) an oxidation annealing;
- followed by
- (b) the superposing of one or more consecutive strata on the stratum formed in step (a), each stratum being formed by repeating at least once the sequence of steps (i), (ii) and optionally (iii), followed by step (2) and optionally step (3).
Dependencies are inferred from the claim text.