Method of repairing deep subsurface defects in a silicon substrate that includes diffusing negatively charged ions into the substrate from a sacrificial oxide layer
View Patent ↗Performance of field effect transistors and other channel dependent devices formed on a monocrystalline substrate is improved by carrying out a high temperature anneal in a nitrogen releasing atmosphere while the substrate is coated by a sacrificial oxide coating containing easily diffusible atoms that can form negatively charged ions and can diffuse deep into the substrate. In one embodiment, the easily diffusible atoms comprise at least 5% by atomic concentration of chlorine atoms in the sacrificial oxide coating and the nitrogen releasing atmosphere includes NO. The high temperature anneal is carried out for less than 10 hours at a temperature less than 1100° C.
1. A defect repair process for repairing deep subsurface defects in a to-be cured silicon substrate to depths substantially greater than 0.1 μm, the method comprising:
(a) coating a to-be-cured substrate with a sacrificial first oxide layer that is doped with diffusible atoms that can diffuse into the substrate as negatively charged ions;
(b) subjecting the first oxide coated substrate to a first anneal atmosphere that can produce positively charged nitrogen ions (N+);
(c) heating the first oxide coated substrate in the first anneal atmosphere to a temperature of at least 800° C.; and
(d) maintaining said heating of the first oxide coated substrate in the first anneal atmosphere for at least 1 minute.
2. The defect repair process of claim 1 wherein:
said diffusible atoms include at least 1% by atomic percentage of chlorine atoms.
3. The defect repair process of claim 2 wherein:
said diffusible atoms include at least 5% by atomic percentage of chlorine atoms.
4. The defect repair process of claim 2 wherein:
said diffusible atoms include at least 10% by atomic percentage of chlorine atoms.
5. The defect repair process of claim 1 wherein:
said diffusible atoms are selected from the group consisting of Cl, Br, S, F and P said diffusible atoms constitute at least 1% by atomic percentage of atoms in the sacrificial first oxide layer.
6. The defect repair process of claim 5 wherein:
said diffusible atoms constitute at least 5% by atomic percentage of atoms in the sacrificial first oxide layer.
7. The defect repair process of claim 5 wherein:
said diffusible atoms constitute at least 10% by atomic percentage of atoms in the sacrificial first oxide layer.
8. The defect repair process of claim 1 wherein:
said first anneal atmosphere includes NO.
9. The defect repair process of claim 1 wherein:
said first anneal atmosphere includes NH3.
10. The defect repair process of claim 1 wherein:
said heating of the first oxide coated substrate in the first anneal atmosphere to a temperature of at least 800° C. does not include heating to or above 1100° C. for more than about 1 minute.
11. The defect repair process of claim 1 wherein:
said maintaining of the heating of the first oxide coated substrate in the first anneal atmosphere is for at least 1 hour.
12. The defect repair process of claim 11 wherein:
said maintaining of the heating of the first oxide coated substrate in the first anneal atmosphere is for at least 3 hours.
13. The defect repair process of claim 1 wherein:
said maintaining of the heating of the first oxide coated substrate in the first anneal atmosphere is for less than 10 hours.
14. The defect repair process of claim 1 and further comprising:
(e) selectively removing the sacrificial first oxide layer from the substrate after said step of maintaining said heating of the first oxide coated substrate in the first anneal atmosphere for at least 1 minute.
15. The defect repair process of claim 14 and further comprising:
(f) after removing the sacrificial first oxide layer, applying a wet etch to selectively remove a silicon oxinitride (SiON) layer that may have formed under the sacrificial first oxide layer.
16. The defect repair process of claim 15 and further comprising:
(g) after applying the selective wet etch, performing a shallow surface nitridation on the exposed substrate.
17. The defect repair process of claim 14 and further comprising:
(f)after removing the sacrificial first oxide layer, performing a shallow surface nitridation on the exposed substrate.
18. The defect repair process of claim 17 and further comprising:
(g) after performing said shallow nitridation, using a radical oxidation process to grow a tunnel oxide layer or a gate oxide layer on said shallow surface nitrided substrate.
19. The defect repair process of claim 14 and further comprising:
(f) after removing the sacrificial first oxide layer, thermally growing a tunnel oxide layer or a gate oxide layer on the surface of the substrate.