Nitride semiconductor device and method for manufacturing same
View Patent ↗An nitride semiconductor device according to the present invention is a nitride semiconductor device including: an n-GaN substrate 10 ; a semiconductor multilayer structure 100 formed on a principal face of the n-GaN substrate 10 , the semiconductor multilayer structure 100 including a p-type region and an n-type region; a p-side electrode 32 which is in contact with a portion of the p-type region included in the semiconductor multilayer structure 100 ; and an n-side electrode 34 provided on the rear face of the n-GaN substrate 10 . The rear face of the n-GaN substrate includes a nitrogen surface, such that a carbon concentration at an interface between the rear face and the n-side electrode 34 is adjusted to 5 atom % or less.
1. A nitride semiconductor device comprising: a nitride-type semiconductor substrate having a shorter side surface and a longer side surface, and containing an n-type impurity; a semiconductor multilayer structure formed on a principal face of the semiconductor substrate, the semiconductor multilayer structure including a p-type region and an n-type region; a p-side electrode which is in contact with a portion of the p-type region included in the semiconductor multilayer structure; and an n-side electrode provided on a rear face of the semiconductor substrate, wherein the rear face of the semiconductor substrate slopes at an angle from the shorter side surface to the longer side surface, with a carbon concentration of 5 atom % or less at an interface between the rear face of the semiconductor substrate and the n-side electrode.
2. The nitride semiconductor device of claim 1 , wherein the n-side electrode includes a layer composed of at least one kind of metal or alloy selected from the group consisting of Ti, Al, Pt, Au, Mo, Sn, In, Ni, Cr, Nb, Ba, Ag, Rh, Ir, Ru, and Hf.
3. The nitride semiconductor device of claim 1 , wherein the n-side electrode has a contact resistivity of 5×10 −4 Ω·cm 2 or less.
4. The nitride semiconductor device of claim 1 , wherein the nitrogen surface accounts for an area ratio of 10% or more in the rear face of the semiconductor substrate.
5. The nitride semiconductor device of claim 1 , wherein the carbon concentration at the interface is 2 atom % or less.
6. The nitride semiconductor device of claim 1 , wherein the rear face of the semiconductor substrate is composed of a polished surface.
7. The nitride semiconductor device of claim 1 , wherein an insulating layer containing oxygen is provided on a portion of the rear face of the semiconductor substrate.
8. A production method for a nitride semiconductor device, comprising: a step of providing a nitride-type semiconductor substrate having a shorter side surface and a longer side surface, and containing an n-type impurity; a step of forming a semiconductor multilayer structure on a principal face of the semiconductor substrate, the semiconductor multilayer structure including a p-type region and an n-type region; a step of forming a p-side electrode on the p-type region included in the semiconductor multilayer structure; and a step of forming an n-side electrode on a rear face of the semiconductor substrate, the rear face being sloped at an angle from the shorter side surface to the longer side surface, wherein, before forming the n-side electrode on the rear face of the semiconductor substrate, a step of reducing a carbon concentration in the rear face is performed.
9. The production method for a nitride semiconductor device of claim 8 , wherein the step of reducing the carbon concentration comprises:
a step of forming an insulative film on the rear face of the semiconductor substrate; and
a step of removing the insulative film.
10. The production method for a nitride semiconductor device of claim 8 , wherein the step of reducing the carbon concentration comprises:
a step of depositing a silicon oxide film on the rear face of the semiconductor substrate; and
a step of removing the silicon oxide film.
11. The production method for a nitride semiconductor device of claim 8 , wherein the step of reducing the carbon concentration comprises a step of exposing the rear face of the semiconductor substrate to a plasma.
12. A production method for a nitride semiconductor device, comprising: a step of depositing an insulative film on a rear face of a nitride-type semiconductor substrate, wherein the semiconductor substrate has a shorter side surface and a longer side surface, and the rear face slopes at an angle from the shorter side surface to the longer side surface; a step of removing the insulative film; and a step of forming an electrode on the rear face of the semiconductor substrate.
13. The production method for a nitride semiconductor device of claim 12 , wherein the insulative film is composed of silicon oxide.