Layer transfer of low defect SiGe using an etch-back process
View Patent ↗A method for forming strained Si or SiGe on relaxed SiGe on insulator (SGOI) or a SiGe on Si heterostructure is described incorporating growing epitaxial Si 1−y Ge y layers on a semiconductor substrate, smoothing surfaces by Chemo-Mechanical Polishing, bonding two substrates together via thermal treatments and transferring the SiGe layer from one substrate to the other via highly selective etching using SiGe itself as the etch-stop. The transferred SiGe layer may have its upper surface smoothed by CMP for epitaxial deposition of relaxed Si 1−y Ge y , and strained Si 1−y Ge y depending upon composition, strained Si, strained SiC, strained Ge, strained GeC, and strained Si 1−y Ge y C or a heavily doped layer to make electrical contacts for the SiGe/Si heterojunction diodes.
1. A multi layer substrate for use in forming integrated circuits comprising:
a silicon containing substrate;
an epitaxial graded Si 1−x Ge x layer disposed on said silicon containing substrate, wherein the value of x ranges from zero to 0.5;
a relaxed Si 1−y Ge y layer disposed on said epitaxial graded Si 1−x Ge x layer;
an encapsulation layer disposed on said relaxed Si 1−y Ge y layer and comprising a material selected from the group consisting of Poly Si, Si 3 N 4 , low-k dielectric materials having a dielectric constant less than SiO 2 , Diamond Like Carbon (DLC), Fluorinated Diamond Like Carbon (FDLC), a polymer of Si, C, O, and H and a combination of any two or more of the foregoing materials; and
a second substrate bonded to said encapsulation layer, wherein said relaxed Si 1−y Ge y layer is free of hydrogen implant.
2. The multi layer substrate of claim 1 , wherein the value of said y is in the range of about 0.2 to about 0.5.
3. The multi layer substrate of claim 1 , wherein the thickness of said epitaxial graded SiGe layer is in the range from about 300 nm to 1,000 nm.
4. The multi layer substrate of claim 1 , wherein the thickness of said relaxed Si 1−y Ge y layer is in the range from 200 nm to 1,000 nm.
5. The multi layer substrate of claim 1 , wherein said encapsulation layer is an isolation layer.
6. The multi layer substrate of claim 1 , wherein said second substrate comprises a material selected from the group consisting of Si, SiGe, SiGeC, SiC, sapphire, glass, ceramic, and metal.