Patterned strained semiconductor substrate and device
View Patent ↗A method that includes forming a pattern of strained material and relaxed material on a substrate; forming a strained device in the strained material; and forming a non-strained device in the relaxed material is disclosed. In one embodiment, the strained material is silicon (Si) in either a tensile or compressive state, and the relaxed material is Si in a normal state. A buffer layer of silicon germanium (SiGe), silicon carbon (SiC), or similar material is formed on the substrate and has a lattice constant/structure mis-match with the substrate. A relaxed layer of SiGe, SiC, or similar material is formed on the buffer layer and places the strained material in the tensile or compressive state. In another embodiment, carbon-doped silicon or germanium-doped silicon is used to form the strained material. The structure includes a multi-layered substrate having strained and non-strained materials patterned thereon.
1. A method, comprising:
forming a pattern of strained material and relaxed material on a substrate;
forming a strained device in the strained material; and
forming a non-strained device in the relaxed material,
wherein the step of forming a pattern of strained material and relaxed material on a substrate further comprises:
forming a recess in the substrate, the recess having sidewalls;
forming a buffer layer in the recess which has a lattice constant/structure mismatch with the substrate;
forming a relaxed layer on the buffer layer;
forming the strained material on the relaxed layer and the relaxed material on the substrate, wherein the relaxed layer has a lattice constant/structure mismatch with the strained material.
2. The method of claim 1 , further comprising forming an insulating layer on the sidewalls before forming the buffer layer.
3. The method of claim 1 wherein the relaxed layer and the buffer layer are each selected from the group consisting of silicon carbon (SiC), silicon germanium (SiGe), Al X1 Ga X2 In X3 As Y1 P Y2 N Y3 Sb Y4 , where X1, X2, X3, Y1, Y2, Y3, and Y4 represent relative proportions, each greater than or equal to zero and X1+X2+X3+Y1+Y2+Y3+Y4=1 (1 being the total relative mole quantity), and Zn A1 Cd A2 Se B1 Te B2 , where A1, A2, B1, and B2 are relative proportions each greater than or equal to zero and A1+A2+B1+B2=1 (1 being a total mole quantity).
4. The method of claim 1 , wherein the strained material and the relaxed material are each selected from one of the group consisting of silicon (Si), silicon carbon (SiC), silicon germanium (SiGe), Al X1 Ga X2 In X3 As Y1 P Y2 N Y3 Sb Y4 , where X1, X2, X3, Y1, Y2, Y3, and Y4 represent relative proportions, each greater than or equal to zero and X1+X2+X3+Y1Y2Y3Y4=1, and Zn A1 Cd A2 Se B1 Te B2 , where A1, A 2, B1, and B2 are relative proportions each greater than or equal to zero and A1+A2+B1+B2=1.
5. The method of claim 1 , wherein the step of forming the buffer layer further comprises:
epitaxially growing multiple layers of a material forming the buffer layer such that the material forming the buffer layer has a base concentration proximate the substrate and an increased benchmark concentration proximate the relaxed layer.
6. The method of claim 5 , wherein the step of forming the relaxed layer further comprises:
epitaxially growing multiple layers of a material forming the relaxed layer such that the material forming the relaxed layer has a second base concentration proximate the buffer layer that approximately equals the bench-mark concentration of the buffer layer material.