Smoothing method for cleaved films made using thermal treatment

The present invention relates to the manufacture of objects. More particularly, the present invention provides a technique for improving surface texture or surface characteristics of a film of material, e.g., silicon, silicon germanium, or others. The present invention can be applied to treating or smoothing a cleaved film from a layer transfer process for the manufacture of integrated circuits, for example. But it will be recognized that the invention has a wider range of applicability; it can also be applied to smoothing a film for other substrates such as multi-layered integrated circuit devices, three-dimensional packaging of integrated semiconductor devices, photonic devices, piezoelectronic devices, microelectromechanical systems ("MEMS"), sensors, actuators, solar cells, flat panel displays (e.g., LCD, AMLCD), doping semiconductor devices, biological and biomedical devices, and the like. In a specific embodiment, the present invention provides a novel process for smoothing a surface of a separated film. The present process is for the preparation of thin semiconductor material films. The process includes a step of implanting by ion bombardment of the face of the wafer by means of ions creating in the volume of the wafer at a depth close to the average penetration depth of the ions, where a layer of gaseous microbubbles defines the volume of the wafer a lower region constituting a majority of the substrate and an upper region constituting the thin film. A temperature of the wafer during implantation is kept below the temperature at which the gas produced by the implanted ions can escape from the semiconductor by diffusion. The process also includes contacting the planar face of the wafer with a stiffener constituted by at least one rigid material layer. The process includes treating the assembly of the wafer and the stiffener at a temperature above that at which the ion bombardment takes place and adequate to create by a crystalline rearrangement effect in the wafer and a pressure effect in the microbubbles to create separation between the thin film and the majority of the substrate. The stiffener and the planar face of the wafer are kept in intimate contact during the stage to free the thin film from the majority of the substrate. The method also includes applying a combination of thermal treatment and an etchant to the thin film to reduce a surface roughness of the thin film to a predetermined value.