Method for preparing a recrystallised silicon substrate with large crystallites

A process for preparing a silicon substrate having an average crystallite size larger than or equal to 20 μm, comprising at least the steps consisting in:

• (i) providing a polycrystalline silicon substrate the average grain size of which is lower or equal to 10 μm;
• (ii) subjecting said substrate to an overall and uniform plastic deformation at a temperature of at least 1000° C.;
• (iii) subjecting said substrate to a plastic deformation localized in a plurality of substrate zones referred to as zones of external stress, the spacing between two consecutive zones being at least 20 μm, the local deformation of the substrate being strictly greater than the overall deformation carried out in step (ii),
• step (iii) possibly being carried out consecutively to or at the same time as step (ii);
• and
• (iv) subjecting the substrate obtained at the end of step (iii) to a solid-phase recrystallization heat treatment, at a temperature strictly higher than the temperature implemented in step (ii), in order to obtain said expected substrate.