Trench-edge-defect-free recrystallization by edge-angle-optimized solid phase epitaxy: method and applications to hybrid orientation substrates
View Patent ↗The present invention discloses the use of edge-angle-optimized solid phase epitaxy for forming hybrid orientation substrates comprising changed-orientation Si device regions free of the trench-edge defects typically seen when trench-isolated regions of Si are recrystallized to the orientation of an underlying single-crystal Si template after an amorphization step. For the case of amorphized Si regions recrystallizing to (100) surface orientation, the trench-edge-defect-free recrystallization of edge-angle-optimized solid phase epitaxy may be achieved in rectilinear Si device regions whose edges align with the (100) crystal's in-plane <100> directions.
1. A method for forming a hybrid orientation substrate comprising
forming a direct-silicon-bonded (DSB) bilayer comprising a single-crystal Si layer having a (100) surface orientation directly bonded to a single-crystal Si layer having a (110) surface orientation, said layers oriented in such a manner so as to have one of the (100) layer's in-plane <100> directions aligned with the (110) layer's in-plane <100> direction;
selecting a plurality of first Si bilayer regions and a plurality of second Si bilayer regions, wherein said (110)-oriented Si in said first bilayer regions will retain their original (110) surface orientation and said (110)-oriented Si in said second bilayer regions will undergo an orientation change to a (100) surface orientation in said second bilayer regions;
forming tench isolation around said first and second Si bilayer regions to produce isolation-bordered first and second Si bilayer regions having edges aligned along the (100) layer's in-plane <100> directions;
amorphizing the entirety of said (110)-oriented layer in said second Si bilayer regions to form localized amorphized regions while leaving at least some of said (100)-oriented layer in said second Si bilayer regions crystalline; and
recrystallizing said localized amorphized regions using said crystalline regions of said (100)-oriented layer in said second Si bilayer regions as a template, thereby changing the orientation of said localized amorphized regions from their original (110) surface orientation to a (100) surface orientation.
2. The method of claim 1 wherein said DSB bilayer comprises a single-crystal Si layer having a (110) surface orientation directly bonded to an underlying bulk Si substrate having a (100) surface orientation.
3. The method of claim 1 wherein said DSB bilayer comprises a single-crystal Si layer having a (110) surface orientation directly bonded to an underlying Si-on-insulator substrate layer having a (100) surface orientation.
4. The method of claim 1 wherein said DSB bilayer comprises a single-crystal Si layer having a (100) surface orientation directly bonded to an underlying Si-on-insulator substrate layer having a (110) surface orientation; said localized amorphized regions comprise a buried amorphous layer; and said first and second Si bilayer regions arc uniformly thinned enough to expose said (110) layer in said first Si regions after said step of recrystallizing.
5. The method of claim 1 wherein said Si layers of said DSB bilayer are replaced by semiconductor layers selected from the group consisting of Si, Ge, SiGe alloys, C-containing Si and C-containing SiGe, these materials further including dopants, layered combinations of these materials, these materials in any combination of strained and unstrained semiconductor layers.
6. The method of claim 1 wherein said amorphization is accomplished by an ion implantation.
7. The method of claim 1 wherein said recrystallization is accomplished by annealing.
8. The method of claim 1 wherein said DSB bilayer is bonded so that an in-plane <100> direction of said (100) layer is within 10° of an in-plane <100> direction of said (110) layer.