Smoothing method for cleaved films made using thermal treatment

A process for the preparation of thin semiconductor material films, wherein the process comprises subjecting a semiconductor material wafer having a planar face and whose plane, is substantially parallel to a principal crystallographic plane, the process comprising:

• implanting by ion bombardment of the face of said wafer by means of ions creating in the volume of said wafer at a depth close to the average penetration depth of said ions, a layer of gaseous microbubbles defining in the volume of said wafer a lower region constituting a majority of the substrate and an upper region constituting the thin film, the temperature of the wafer during implantation being kept below the temperature at which the gas produced by the implanted ions can escape from the semiconductor by diffusion;
• contacting the planar face of said wafer with a stiffener constituted by at least one rigid material layer;
• treating the assembly of said wafer and said stiffener at a temperature above that at which the ion bombardment takes place and adequate to created, by a crystalline rearrangement effect in the wafer and a pressure effect in the microbubbles, a separation between the thin film and the majority of the substrate, the stiffener and the planar face of the wafer being kept in intimate contact during said stage to free the thin film from the majority of the substrate;
• and
• applying a combination of thermal treatment and an etchant to said thin film to reduce a surface roughness of said thin film to a predetermined value, wherein said thermal treatment increases a temperature of said thin film to about 1,000 Degrees Celsius and greater, said temperature increasing about 10 Degrees Celsius per second and greater.