SOI wafer and method for forming the same
An SOI wafer and a method for forming the same, where the method for forming an SOI wafer includes: preparing a monocrystalline silicon wafer on which a mask layer is formed; etching the mask layer and the monocrystalline silicon wafer to form several trenches; forming a first insulating layer on the sidewalls and the bottoms of the trenches; etching and removing the first insulating layer on the bottoms of the trenches; etching along the trenches the monocrystalline silicon wafer beneath the trenches to form cavities; processing the inner walls of the cavities to form a second insulating layer; and filling up the trenches and the cavities with an insulating material layer. The process of the invention is easy to be implemented at a low manufacturing cost and an SOI wafer being formed is of high quality while being capable of being compatible with a standard process of manufacturing a bulk silicon CMOS.
1. A method for forming an SOI wafer, comprising:
preparing a monocrystalline silicon wafer on which a mask layer is formed;
etching the mask layer and the monocrystalline silicon wafer to form several trenches;
forming a first insulating layer on the sidewalls and the bottoms of the trenches;
etching and removing the first insulating layer on the bottoms of the trenches;
etching along the trenches the monocrystalline silicon wafer beneath the trenches to form cavities;
processing the inner walls of the cavities to form a second insulating layer, the second insulating layers in adjacent cavities connecting with each other to split the monocrystalline silicon wafer into an upper sector of a top layer silicon and a lower sector of a silicon substrate; and
filling up the trenches and the cavities with an insulating material layer.
2. The method for forming an SOI wafer according to claim 1 , wherein the mask layer comprises a first film layer and a second film layer on the first film layer.
3. The method for forming an SOI wafer according to claim 2 , wherein the first film layer is made of silicon oxide, and the second film layer is made of silicon nitride.
4. The method for forming an SOI wafer according to claim 1 , wherein the first insulating layer is formed through thermal oxidization, thermal nitrification or chemical vapor deposition.
5. The method for forming an SOI wafer according to claim 4 , wherein the first insulating layer is made of silicon oxide or silicon nitride with a thickness of 1 nm to 10 μm.
6. The method for forming an SOI wafer according to claim 1 , wherein the first insulating layer on the bottoms is etched and removed through plasma etching or ion beam etching using Gas of Argon.
7. The method for forming an SOI wafer according to claim 1 , wherein the monocrystalline silicon wafer is etched through dry etching using gas of XeF2 or mixed gas of HNO3 and HF.
8. The method for forming an SOI wafer according to claim 1 , wherein the second insulating layer is formed through thermal oxidation or thermal nitrification.
9. The method for forming an SOI wafer according to claim 8 , wherein the second insulating layer is made of silicon oxide or silicon nitride.
10. The method for forming an SOI wafer according to claim 1 , wherein the insulating material layer is filled through low-pressure chemical vapor disposition or spin coating.
11. The method for forming an SOI wafer according to claim 10 , wherein the insulating material layer is made of silicon oxide or silicon oxide containing phosphor, boron, carbon, nitrogen or hydrogen.
12. The method for forming an SOI wafer according to claim 1 , wherein the number of the trenches is dependent upon whether the cavities to be formed subsequently beneath the trenches can be interconnected to separate the monocrystalline silicon wafer into a silicon substrate and a top layer of silicon.
13. The method for forming an SOI wafer according to claim 1 , wherein the cavities are spaced at an interval of approximately 10 nm to 1000 nm, and the monocrystalline silicon at the interval is processed to form a part of the second insulating layer in the following processing step.
14. The method for forming an SOI wafer according to claim 1 , wherein the adjacent cavities are interconnected with each other completely.
15. The method for forming an SOI wafer according to claim 1 , wherein the cavities having a depth of 50 nm to 50 um arranged in the monocrystialline silicon wafer.