US 7,531,427 B2
Thermal oxidation of a SiGe layer and applications thereof
Nicolas Daval, Grenoble (France)
Assigned to S.O.I.Tec Silicon on Insulator Technologies, Bernin (France)
Filed on Jul. 05, 2007, as Appl. No. 11/773,893.
Application 11/773893 is a continuation of application No. PCT/IB2005/000644, filed on Feb. 24, 2005.
Prior Publication US 2007/0254440 A1, Nov. 01, 2007
Int. Cl. H01L 21/46 (2006.01)
U.S. Cl. 438—455  [438/769; 257/E21.207] 24 Claims
OG exemplary drawing
 
1. A method for providing a homogeneous distribution of germanium in an SiGe layer when oxidizing a surface region thereof, which comprises directly oxidizing the surface region of the SiGe layer by:
conducting a first phase of directly oxidizing the SiGe layer to form an oxidized surface region which is sufficiently thick to act as a capping oxide to protect the SiGe layer from pitting during further heating while also forming a Ge-enriched region which is located within the SiGe layer immediately beneath the oxidized surface region and a remaining part of the SiGe layer, wherein the oxidized surface region is sufficiently thin to be below a threshold thickness range that would generate dislocations within the SiGe layer due to a lattice parameter mismatch between the Ge-enriched region and the remaining part of the SiGe layer, and
conducting a second phase of high temperature annealing in an inert atmosphere of the capping oxide, Ge-enriched region and remaining part of the SiGe layer for a time and at a temperature sufficient to allow diffusion of Ge from the Ge-enriched region into the remaining of the SiGe layer to provide the homogeneous distribution of germanium within the remaining SiGe layer.