Manufacturing method for strained silicon wafer
View Patent ↗A method for manufacturing a strained silicon wafer, having steps of a first step of preparing a single crystal silicon substrate, a second step of forming a graded SiGe layer on the substrate, the graded SiGe layer having a first Ge composition ratio increased stepwisely from 5 to 60% at atomic ratio, a third step of forming a SiGe constant composition layer on the graded SiGe layer, the SiGe constant composition layer having a Ge composition ratio substantially equal to the Ge composition ratio on a surface of the-graded SiGe layer and a fourth step of forming a strained Si layer on the SiGe constant composition layer. The second through fourth steps are performed under the reduced pressure atmosphere while the single crystal silicon substrate is rotated in a circumferential direction at a rate from 300 rpm to 1500 rpm.
1. A method for manufacturing a strained silicon wafer, comprising:
a first step of preparing a single crystal silicon substrate;
a second step of forming a graded SiGe layer on the single crystal silicon substrate under temperature ranging from 800° C. to 1100° C., the graded SiGe layer comprising a first Ge composition ratio progressively increased stepwisely from 5 to 60% atomic ratio;
a third step of forming a SiGe constant composition layer on the graded SiGe layer, the SiGe constant composition layer comprising a Ge composition ratio substantially equal to Ge composition ratio a surface of the graded SiGe layer which is adjacent to the SiGe constant composition layer; and
a fourth step of forming a strained Si layer comprising a thickness less than 15 nm on the SiGe constant composition layer,
wherein the second through fourth steps are performed under reduced pressure atmosphere while the single crystal silicon substrate is rotated in a circumferential direction at a rate of 300 rpm to 1500 rpm.
2. The method for manufacturing the strained silicon wafer as set forth in claim 1 , wherein the surface of the single crystal silicon substrate is a mirror surface, and has hazes.
3. The method for manufacturing the strained silicon wafer as set forth in claim 2 , wherein the single crystal silicon substrate comprises a surface roughness Rq of at least 0.20 nm and not more than 0.30 nm.
4. The method for manufacturing the strained silicon wafer as set forth in claim 1 , wherein the strained Si layer comprises a threading dislocation density of 1×10 3 cm −2 or less.
5. The method for manufacturing the strained silicon wafer as set forth in claim 1 , wherein the third step comprises epitaxially growing a SiGe constant composition layer on the graded SiGe layer.
6. A method for manufacturing a strained silicon wafer a threading dislocation density of 1×10 3 cm −2 or less, consisting essentially of:
(a) preparing a single crystal silicon substrate;
(b) forming a graded SiGe layer on the single crystal silicon substrate at a temperature ranging from 800° C. to 1100° C., the graded SiGe layer comprising a first Ge composition ratio progressively increased stepwisely from 5 to 60% atomic ratio;
(c) forming a SiGe constant composition layer on the graded SiGe layer, the SiGe constant composition layer comprising a Ge composition ratio substantially equal to a Ge composition ratio at a surface of the graded SiGe layer which is adjacent to the SiGe constant composition layer; and
(d) forming a strained Si layer comprising a thickness less than 15 nm on the SiGe constant composition layer,
wherein (b) through (d) are performed at a temperature ranging from 800° C. to 1100° C. and under a reduced pressure atmosphere while the single crystal silicon substrate is rotated in a circumferential direction at a rate of 300 rpm to 1500 rpm.