Nitride-based semiconductor device and method of fabricating the same
A method of fabricating a nitride-based semiconductor device capable of reducing contact resistance between a nitrogen face of a nitride-based semiconductor substrate or the like and an electrode is provided. This method of fabricating a nitride-based semiconductor device comprises steps of etching the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or a nitride-based semiconductor substrate having a wurtzite structure and thereafter forming an n-side electrode on the etched back surface of the first semiconductor layer.
1. A method of fabricating a nitride-based semiconductor device, comprising the steps of:
polishing the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or an n-type nitride-based semiconductor substrate having a wurtzite structure;
removing dislocation defects at the back surface generated by the polishing until dislocation density at the back surface is not more than 1×10 9 cm −2 ;
forming an n-side electrode on said back surface having the dislocation density of no more than 1×10 9 cm −2 with a contact resistance between the electrode and the back surface of no more than 0.05 ohms cm 2 ; and
mounting said nitride-based semiconductor device in a junction-down system.
2. The method of fabricating a nitride-based semiconductor device according to claim 1 ,
further comprising a step of performing heat treatment after said step of forming said n-side electrode.
3. The method of fabricating a nitride-based semiconductor device according to claim 1 ,
further comprising a step of cleaving said first semiconductor layer.
4. A method of fabricating an n-type nitride-based semiconductor device, comprising the steps of:
polishing the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or an n-type nitride-based semiconductor substrate having a wurtzite structure;
removing dislocation defects at the back surface generated by the polishing until dislocation density at the back surface is not more than 1×10 9 cm −2 ;
forming an n-side electrode on said back surface having the dislocation density of no more than 1×10 9 cm −2 with a contact resistance between the electrode and the back surface of no more than 0.05 ohms cm 2 ; and
adhering between said n-side electrode and a radiator base.
5. The method of fabricating a nitride-based semiconductor device according to claim 4 ,
further comprising a step of performing heat treatment after said step of forming said n-side electrode.
6. The method of fabricating a nitride-based semiconductor device according to claim 4 ,
further comprising a step of cleaving said first semiconductor layer.
7. The method of fabricating a nitride-based semiconductor device according to claim 1 ,
wherein the removing dislocation defects comprises etching with a combination of Cl 2 gas and BCI 3 gas followed by hydrochloric acid treatment.
8. The method of fabricating a nitride-based semiconductor device according to claim 4 ,
wherein the removing dislocation defects comprises etching with a combination of Cl 2 gas and BCI 3 gas followed by hydrochloric acid treatment.
9. The method of fabricating a nitride-based semiconductor device according to claim 1 ,
wherein the removing dislocation defects comprises wet etching.
10. The method of fabricating a nitride-based semiconductor device according to claim 4 ,
wherein the removing dislocation defects comprises wet etching.
11. A method of fabricating a nitride-based semiconductor device, comprising:
mechanically polishing the back surface of a first semiconductor layer consisting of either an n-type nitride-based semiconductor layer or an n-type nitride-based semiconductor substrate having a wurtzite structure with an abrasive particle roughness of about 0.2 μm to about 1 μm;
etching the polished surface to remove a thickness of about 1 μm until a dislocation density at the back surface is not more than 1×10 9 cm −2 ; and
forming an n-side electrode on the polished and etched back surface having the dislocation density of no more than 1 33 10 9 cm 2 with a contact resistance between the electrode and the back surface of no more than 0.05 ohms cm 2 .
12. The method of fabricating a nitride-based semiconductor device according to claim 11 ,
further comprising performing heat treatment after said forming said n-side electrode.
13. The method of fabricating a nitride- based semiconductor device according to claim 11 ,
further comprising cleaving said first semiconductor layer.
14. The method of fabricating a nitride-based semiconductor device according to claim 11 ,
wherein the etching of the polished surface comprises wet etching.
15. The method of fabricating a nitride-based semiconductor device according to claim 1 , further comprising cleaving said first semiconductor layer.
16. The method of fabricating a nitride-based semiconductor device according to claim 15 ,
further comprising etching the polished back surface prior to cleaving the first semiconductor layer.