Patent ID: 6110802
Filing Date: 2000-08-29
Classification: H01L

Abstract:
Process for producing an epitaxied structure with a low dislocation density, said structure comprising an oxide layer (6) in a semiconductor material substrate (4), the process comprising the following successive steps:(a) at least one implantation of oxygen ions (2) in the substrate (4) through a surface (3) of the latter in order to form a buried oxide layer whereby oxide precipitates are formed during implantation,(b) at least one first conditioning heat treatment of the substrate at a temperature below the melting point of the semiconductor material wherein dislocations (8) are present on a surface of the substrate,(c) forming an epitaxial layer (14) of a semiconductor material having a thickness equal to or greater than 0.05 .mu.m on the substrate surface by epitaxial growth whereby the dislocations (8) become extended into the epitaxial layer (14) during the epitaxy growth, and(d) following step (c), a second heat treatment at a temperature that is lower than the melting point of the semiconductor material of the substrate and that of the material of the epitaxied layer (14) said second heat treatment being carried out at a temperature and for a duration effective to eliminate most of the dislocations in the epitaxied layer that are in an unstable energy configuration, wherein at least one of the first and second heat treatments is performed at a temperature equal to or above 1200.degree. C. to substantially dissolve all the oxide precipitates formed during implantation, to free the dislocations (8) to form free dislocations and to allow the free dislocations to recombine during the second heat treatment to obtain an epitaxied structure having a dislocation density of below 10.sup.5 dislocations/cm.sup.2.