Method and system for diffusion and implantation in gallium nitride based devices
View Patent ↗A method of forming a doped region in a III-nitride substrate includes providing the III-nitride substrate and forming a masking layer having a predetermined pattern and coupled to a portion of the III-nitride substrate. The III-nitride substrate is characterized by a first conductivity type and the predetermined pattern defines exposed regions of the III-nitride substrate. The method also includes heating the III-nitride substrate to a predetermined temperature and placing a dual-precursor gas adjacent the exposed regions of the III-nitride substrate. The dual-precursor gas includes a nitrogen source and a dopant source. The method further includes maintaining the predetermined temperature for a predetermined time period, forming p-type III-nitride regions adjacent the exposed regions of the III-nitride substrate, and removing the masking layer.
1. A method of forming a doped region in a III-nitride substrate, the method comprising:
providing the III-nitride substrate, wherein the III-nitride substrate is characterized by a first conductivity type;
forming a masking layer having a predetermined pattern, wherein the predetermined pattern defines exposed regions of the III-nitride substrate;
placing the exposed regions of the III-nitride substrate in a dual-precursor gas comprising both a chemically reactive nitrogen source and a dopant source;
while the exposed regions of the III-nitride substrate are exposed to the chemically reactive nitrogen source and the dopant source of the dual-precursor gas, implanting the dopant from the dopant source of the dual-precursor gas into the exposed regions of the III-nitride substrate, wherein, while the dopant is implanted into the exposed regions, the chemically reactive nitrogen source counteracts the effects of nitrogen escaping from the III-nitride substrate; and
removing the masking layer.
2. The method of claim 1 , wherein the III-nitride substrate comprises an n-type GaN substrate.
3. The method of claim 1 , wherein the masking layer comprises a refractory material.
4. The method of claim 1 , wherein a temperature of the dual-precursor gas is between about 800° C. to about 1800° C.
5. The method of claim 1 , wherein the dual-precursor gas includes ammonia and an acceptor species.
6. The method of claim 1 , wherein placing the exposed regions of the III-nitride substrate in the dual-precursor gas comprises:
positioning the III-nitride substrate in a chamber; and
flowing the dual-precursor gas including both the nitrogen source and the dopant source through the chamber.
7. The method of claim 5 , wherein the chamber comprises an MOCVD chamber.
8. The method of claim 1 , wherein implanting the dopant into the III-nitride substrate comprises diffusing the dopant into the III-nitride substrate.
9. A method of forming a doped region in a III-nitride substrate, the method comprising:
providing the III-nitride substrate, wherein the III-nitride substrate is characterized by a first conductivity type;
forming a masking layer having a predetermined pattern, wherein the predetermined pattern defines predetermined portions of the III-nitride substrate;
placing the III-nitride substrate in a chamber;
forming an environment in the chamber, wherein the environment comprises a dual-precursor gas including both a chemically reactive nitrogen source and a dopant source, wherein the dopant is characterized by a second conductivity type;
exposing the predetermined portions of the III-nitride substrate to the chemically reactive nitrogen source and the dopant source of the dual-precursor gas;
while the predetermined portions of the III-nitride substrate are exposed to the chemically reactive nitrogen source and the dopant source of the dual-precursor gas, implanting the dopant into the predetermined portions of the III-nitride substrate;
while the predetermined portions of the III-nitride substrate are exposed to the chemically reactive nitrogen source, with the chemically reactive nitrogen source, counteracting the effects of nitrogen escaping from the III-nitride substrate; and
removing the masking layer.
10. The method of claim 9 , wherein the chamber comprises an MOCVD reactor.
11. The method of claim 9 , wherein the chamber comprises an annealing furnace.
12. The method of claim 9 , wherein the III-nitride substrate comprises an n-type GaN substrate.
13. The method of claim 9 , wherein the masking layer comprises a refractory material.
14. The method of claim 9 , wherein removing the masking layer is performed prior to placing the III-nitride substrate in the chamber.
15. The method of claim 9 , wherein a temperature of the environment is between about 800° C. to about 1800° C.
16. The method of claim 9 , wherein the dopant comprises an acceptor species.
17. The method of claim 9 , further comprising forming a sacrificial layer coupled to the III-nitride substrate prior to implanting the dopant.
18. The method of claim 17 , further comprising removing the sacrificial layer is performed after implanting the dopant.
19. The method of claim 9 , wherein implanting the dopant into the III-nitride substrate comprises performing an ion implantation process.
20. The method of claim 9 , wherein implanting the dopant into the III-nitride substrate comprises diffusing the dopant into the III-nitride substrate.