Silicon on insulator structure having an epitaxial layer and intrinsic gettering
View Patent ↗The present invention is directed to a process for producing a silicon on insulator (SOI) structure having intrinsic gettering, wherein a silicon substrate is subjected to an ideal precipitating wafer heat treatment which enables the substrate, during the heat treatment cycles of essentially any arbitrary electronic device manufacturing process to form an ideal, non-uniform depth distribution of oxygen precipitates, and wherein a dielectric layer is formed beneath the surface of the wafer by implanting oxygen or nitrogen ions, or molecular oxygen, beneath the surface and annealing the wafer. Additionally, the silicon wafer may initially include an epitaxial layer, or an epitaxial layer may be deposited on the substrate during the process of the present invention.
1. A silicon on insulator structure comprising a device layer, a supporting layer and a dielectric layer therebetween, wherein the device layer comprises an epitaxial layer and the supporting layer comprises
(i) a first region and a second region, the first region extending from the dielectric layer to the second region and having a thickness, T, as measured from the dielectric layer to the second region, and
(ii) a non-uniform concentration of crystal lattice vacancies, the concentration of the vacancies in the second region being greater than the concentration of vacancies in the first region.
2. The silicon on insulator structure of claim 1 wherein the supporting layer, upon being subjected to an oxygen precipitation heat treatment consisting essentially of annealing the silicon on insulator structure at 800° C. for four hours and then at 1000° C. for sixteen hours, contains oxygen precipitates having a concentration profile in which a peak density of the precipitates is in the second region at or near a central plane with the concentration of the precipitates in the second region generally decreasing in the direction of the first region.
3. The silicon on insulator structure of claim 1 wherein the first region has a thickness of at least about 5 microns.
4. The silicon on insulator structure of claim 1 wherein the first region has a thickness of at least about 10 microns.
5. The silicon on insulator structure of claim 1 wherein the first region has a thickness of at least about 20 microns.
6. The silicon on insulator structure of claim 1 wherein the first region has a thickness of at least about 50 microns.
7. The silicon on insulator structure of claim 1 wherein the epitaxial layer has a thickness within the range of at least about 0.1 μm to less than about 2 μm.
8. The silicon on insulator structure of claim 1 wherein the epitaxial layer has a thickness within the range of about 0.25 to about 1 μm.
9. The silicon on insulator structure of claim 1 wherein the supporting layer has a carbon concentration which is less than about 1×10 16 atoms/cm 3 .
10. A silicon on insulator structure comprising a device layer, a supporting layer and a dielectric layer therebetween, wherein the device layer comprises an epitaxial layer and the supporting layer comprises
(i) a first region and a second region, the first region extending from the dielectric layer to the second region and having a thickness, T, as measured from the dielectric layer to the second region, and
(ii) a non-uniform depth distribution of stabilized oxygen precipitates, the concentration of the precipitates in the second region being greater than the concentration of precipitate in the first region.
11. The silicon on insulator structure of claim 10 wherein the supporting layer has a stabilized oxygen precipitate concentration profile in which a peak density of the precipitates is in the second region at or near a central plane with the concentration of the precipitates in the second region generally decreasing in the direction of the first region.
12. The silicon on insulator structure of claim 10 wherein the first region has a thickness of at least about 5 microns.
13. The silicon on insulator structure of claim 10 wherein the first region has a thickness of at least about 10 microns.
14. The silicon on insulator structure of claim 10 wherein the first region has a thickness of at least about 20 microns.
15. The silicon on insulator structure of claim 10 wherein the first region has a thickness of at least about 50 microns.
16. The silicon on insulator structure of claim 10 wherein the first region has a thickness ranging from about 5 microns to less than about 100 microns.
17. The silicon on insulator structure of claim 10 wherein the epitaxial layer has a thickness within the range of at least about 0.1 μm to less than about 2 μm.
18. The silicon on insulator structure of claim 10 wherein the epitaxial layer has a thickness within the range of about 0.25 to about 1 μm.
19. The silicon on insulator structure of claim 10 wherein the supporting layer has a carbon concentration which is less than about 1×10 16 atoms/cm 3 .
20. The silicon on insulator structure of claim 10 wherein the oxygen precipitates have an average cross-sectional area of at least about 40 nm.
21. The silicon on insulator structure of claim 10 wherein the oxygen precipitates have an average cross-sectional area of at least about 50 nm.
22. The silicon on insulator structure of claim 10 wherein the oxygen precipitates have an average cross-sectional area of at least about 60 nm.
23. The silicon on insulator structure of claim 10 wherein the oxygen concentration of the supporting layer is at least about 6×10 17 atoms/cm 3 .
24. A silicon on insulator structure comprising a device layer, a supporting layer and a dielectric layer therebetween, wherein the device layer comprises an epitaxial layer and the supporting layer comprises
(i) a first region and a second region, the first region extending from the dielectric layer to the second region and having a thickness, T, as measured from the dielectric layer to the second region, and
(ii) a non-uniform depth distribution of secondary defects capable of acting as intrinsic gettering sites, the concentration of defects in the second region being greater than the concentration of defects in the first region.
25. The silicon on insulator structure of claim 24 wherein the supporting layer has a secondary defect concentration profile in which a peak density of the defects is in the second region at or near a central plane with the concentration of the defects in the second region generally decreasing in the direction of the first region.
26. The silicon on insulator structure of claim 24 wherein the first region has a thickness of at least about 5 microns.
27. The silicon on insulator structure of claim 24 wherein the first region has a thickness of at least about 10 microns.
28. The silicon on insulator structure of claim 24 wherein the first region has a thickness of at least about 20 microns.
29. The silicon on insulator structure of claim 24 wherein the first region has a thickness ranging from about 5 microns to less than about 100 microns.
30. The silicon on insulator structure of claim 24 wherein the epitaxial layer has a thickness within the range of at least about 0.1 μm to less than about 2 μm.
31. The silicon on insulator structure of claim 24 wherein the epitaxial layer has a thickness within the range of about 0.25 to about 1 μm.
32. The silicon on insulator structure of claim 24 wherein the supporting layer has a carbon concentration which is less than about 1×10 16 atoms/cm 3 .
33. The silicon on insulator structure of claim 24 wherein the oxygen concentration of the supporting layer is at least about 6×10 17 atoms/cm 3 .
34. The silicon on insulator structure of claim 24 wherein the secondary defects are prismatic dislocation loops or tangles, or stacking faults.