Twisted dual-substrate orientation (DSO) substrates
View Patent ↗A semiconductor process and apparatus provide a dual or hybrid substrate by forming a second semiconductor layer ( 214 ) that is isolated from, and crystallographically rotated with respect to, an underlying first semiconductor layer ( 212 ) by a buried insulator layer ( 213 ); forming an STI region ( 218 ) in the second semiconductor layer ( 214 ) and buried insulator layer ( 213 ); exposing the first semiconductor layer ( 212 ) in a first area ( 219 ) of a STI region ( 218 ); epitaxially growing a first epitaxial semiconductor layer ( 220 ) from the exposed first semiconductor layer ( 212 ); and selectively etching the first epitaxial semiconductor layer ( 220 ) and the second semiconductor layer ( 214 ) to form CMOS FinFET channel regions (e.g., 223 ) and planar channel regions (e.g., 224 ) from the first epitaxial semiconductor layer ( 220 ) and the second semiconductor layer ( 214 ).
1. A method for fabricating a dual substrate semiconductor structure, comprising:
forming a first semiconductor layer having a first crystal orientation;
forming a second semiconductor layer over at least part of the first semiconductor layer, wherein the second semiconductor layer is electrically isolated from the first semiconductor layer and has a second crystal orientation that is different from the first crystal orientation;
forming a shallow trench isolation region in a first trench opening that exposes the first semiconductor layer in a first area by filling the first trench opening with an insulating material; then
forming a second trench opening in the shallow trench isolation region that exposes the first semiconductor layer in a second area contained within the first area; then
epitaxially growing a first epitaxial semiconductor material on at least an exposed surface of the first semiconductor layer to form a first epitaxial semiconductor layer; and
patterning and etching the first epitaxial semiconductor layer and the second semiconductor layer to form one or more FinFET channel regions.
2. The method of claim 1 , where the first crystal orientation is rotated forty-five degrees with respect to the second crystal orientation.
3. The method of claim 1 , where the first semiconductor layer has a (110) surface orientation, and the second semiconductor layer has a (100) surface orientation.
4. The method of claim 1 , wherein the second semiconductor layer comprises (100) p-type silicon and the first epitaxial semiconductor layer comprises (110) n-type silicon.
5. The method of claim 1 , where the first semiconductor layer comprises a silicon handle wafer.
6. The method of claim 1 , where the first semiconductor layer is formed over a buried insulator layer that is formed on a silicon handle wafer layer.
7. The method of claim 1 , where patterning and etching the first epitaxial semiconductor layer and the second semiconductor layer also form one or more planar MOSFET channel regions.
8. The method of claim 1 , further comprising:
forming a gate layer over the FinFET channel regions, and
selectively etching the gate layer to form one or more gate electrodes over the FinFET channel regions.
9. A method for forming a semiconductor structure having dual substrates on a wafer, comprising:
forming a first semiconductor layer having a first crystal orientation;
forming a second semiconductor layer over at least part of the first semiconductor layer, wherein the second semiconductor layer is electrically isolated from the first semiconductor layer by a buried insulator layer and where the second semiconductor layer has a crystal orientation that is rotated 45 degrees with respect to the first crystal orientation of the first semiconductor layer;
forming a first trench opening that exposes the first semiconductor layer by removing the buried insulator layer and the second semiconductor layer in a first region;
forming a first insulator layer to fill in the first trench opening; then
forming a second trench opening in the first insulator layer by removing at least the first insulator layer in a second region within the first region to expose the first semiconductor layer; then
filling at least part of a second trench opening that exposes the first semiconductor layer by epitaxially growing a first epitaxial semiconductor layer on at least an exposed surface of the first semiconductor layer; and
selectively etching the first epitaxial semiconductor layer and the second semiconductor layer to form FinFET channel regions from the first epitaxial semiconductor layer and the second semiconductor layer.
10. The method of claim 9 , where the first semiconductor layer comprises a bulk semiconductor substrate layer and the second semiconductor layer comprises an SOI semiconductor layer.
11. The method of claim 9 , where the first semiconductor layer comprises an SOI semiconductor layer and the second semiconductor layer comprises an SOI semiconductor layer.
12. The method of claim 9 , further comprising:
forming a second insulator layer over the FinFET channel regions;
forming a conductive gate layer over the second insulator layer; and
selectively etching the conductive gate layer to form FinFET gate electrodes.
13. The method of claim 9 , where the step of selectively etching the first epitaxial semiconductor layer and the second semiconductor layer is also used to form planar channel regions from the first epitaxial semiconductor layer and the second semiconductor layer.
14. The method of claim 13 , further comprising:
forming a second insulator layer over the FinFET channel regions and the planar channel regions;
forming a conductive gate layer over the second insulator layer; and
selectively etching the conductive gate layer to form FinFET gate electrodes over the FinFET channel regions and to form MOSFET gate electrodes over the planar channel regions.
15. The method of claim 9 , where the first semiconductor layer has a (110) surface orientation, and the second semiconductor layer has a (100) surface orientation.
16. A method for fabricating FET devices on a twisted dual substrate, comprising:
providing a second semiconductor layer that is isolated from an underlying first semiconductor layer by at least a buried insulator layer, where the second semiconductor layer is crystallographically rotated with respect to the underlying first semiconductor layer;
forming a shallow trench isolation region in a first trench opening that exposes the first semiconductor layer in a first area by filling the first trench opening with an insulating material; then
exposing the first semiconductor layer by forming a second trench opening in the shallow trench isolation region in a second area contained within the first area; then
epitaxially growing a first epitaxial semiconductor layer from the second area, where the first epitaxial semiconductor layer is isolated from the second semiconductor layer by the shallow trench isolation region;
selectively etching the first epitaxial semiconductor layer to form first CMOS FinFET channel regions and planar channel regions from the first epitaxial semiconductor layer; and
selectively etching the second semiconductor layer to form second CMOS FinFET channel regions and planar channel regions from the second semiconductor layer.
17. The method of claim 16 , further comprising:
forming an insulator layer over the CMOS FinFET channel regions and planar channel regions;
forming a conductive gate layer over the insulator layer; and
selectively etching the conductive gate layer to form FinFET gate electrodes and MOSFET gate electrodes.
18. The method of claim 16 , where the second semiconductor layer is crystallographically rotated forty-five degrees with respect to the underlying first semiconductor layer.
19. The method of claim 16 , wherein the second semiconductor layer comprises (100) p-type silicon and the first epitaxial semiconductor layer comprises (110) n-type silicon.