Silicon-on-insulator structures and methods
View Patent ↗Silicon-on-insulator (SOI) structures are provided by forming a single-crystal insulator over a substrate, followed by heteroepitaxy of a semiconductor layer thereover. Atomic layer deposition (ALD) is preferably used to form an amorphous insulator, followed by solid phase epitaxy to convert the layer into a single-crystal structure. Advantageously, the crystalline insulator has a lattice structure and lattice constant closely matching that of the semiconductor formed over it, and a ternary insulating material facilitates matching properties of the layers. Strained silicon can be formed without need for a buffer layer. An amorphous SiO 2 layer can optionally be grown underneath the insulator. In addition, a buffer layer can be grown, either between the substrate and the insulator or between the insulator and the semiconductor layer, to produce desired strain in the active semiconductor layer.
1. A method for forming a semiconductor-on-insulator structure, comprising:
forming an epitaxial insulator over a substrate; and
forming an epitaxial semiconductor over the epitaxial insulator, wherein forming the epitaxial insulator comprises:
depositing an amorphous insulating layer, wherein depositing the amorphous insulating layer comprises an atomic layer deposition process; and
converting the amorphous insulating layer to a single-crystal material by solid phase epitaxy.
2. The method of claim 1 , wherein the amorphous insulating layer comprises a ternary oxide.
3. The method of claim 1 , wherein the atomic layer deposition process comprises pulsing source chemicals in a plurality of cycles.
4. The method of claim 3 , wherein the frequency of pulses in different cycles is varied to tailor the composition of the amorphous insulating layer.
5. The process of claim 1 , wherein the atomic layer deposition process is modified to achieve the desired composition of the insulating layer.
6. The process of claim 1 , wherein the semiconductor comprises strained silicon.
7. A method for forming a semiconductor-on-insulator structure, comprising:
forming an epitaxial insulator over a substrate; and
forming an epitaxial semiconductor over the epitaxial insulator, wherein forming the epitaxial insulator comprises:
depositing an amorphous insulating layer;
converting the amorphous insulating layer to a single-crystal material by solid phase epitaxy, and oxidizing the substrate during the solid phase epitaxy.
8. A method for forming a semiconductor-on-insulator structure, comprising:
forming an epitaxial insulator over a substrate, wherein the epitaxial insulator comprises greater than two elements; and
forming an epitaxial semiconductor over the epitaxial insulator, wherein forming the epitaxial insulator comprises:
depositing an amorphous insulating layer; and
converting the amorphous insulating layer to a single-crystal material by solid phase epitaxy.
9. The method of claim 8 , wherein the epitaxial insulator comprises lanthanum aluminum oxide.
10. A process for forming an integrated circuit, comprising:
depositing an amorphous insulating layer over a semiconductor substrate, wherein depositing the amorphous insulator comprises forming a compound having greater than or equal to three elements;
converting the amorphous insulating layer into a highly crystalline material; and
heteroepitaxially depositing a semiconductor structure over the amorphous insulating layer after converting.
11. A method for forming a semiconductor-on-insulator structure, comprising:
forming an epitaxial insulator over a substrate; and
forming an epitaxial semiconductor over the epitaxial insulator, wherein forming the epitaxial insulator comprises:
depositing an amorphous insulating layer, wherein depositing the amorphous insulator comprises depositing a ternary oxide by an atomic layer deposition process; and
converting the amorphous insulating layer to a single-crystal material by solid phase epitaxy.
12. A process for forming an integrated circuit, comprising:
depositing an amorphous insulating layer over a semiconductor substrate, wherein depositing the amorphous insulator comprises maintaining the semiconductor substrate substantially free of a native oxide;
converting the amorphous insulating layer into a highly crystalline material; and
heteroepitaxially depositing a semiconductor structure over the amorphous insulating layer after converting.