GROUP-III NITRIDE VERTICAL-RODS SUBSTRATE

Abstract

The invention is directed to a group-III nitride vertical-rods substrate. The group-III vertical-rods substrate comprises a substrate, a buffer layer and a vertical rod layer. The buffer layer is located over the substrate. The vertical rod layer is located on the buffer layer and the vertical rod layer is comprised of a plurality of vertical rods standing on the buffer layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a cross-sectional view showing a conventional group-III nitride substrate.

FIG. 2 is a cross-sectional view showing a conventional group-III nitride substrate.

FIG. 3A is a cross-sectional view showing a group-III nitride vertical-rods substrate according to one embodiment of the present invention.

FIG. 3B is a cross-sectional view showing another group-III nitride vertical-rods substrate according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a vertical rod of a group-III nitride vertical-rods substrate according to one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 3A is a cross-sectional view showing a group-III nitride vertical-rods substrate according to one embodiment of the present invention.

As shown in FIG. 3A, a group-III nitride vertical-rods substrate of the present invention comprises a substrate 300, a buffer layer 302, a vertical rod layer 306 and a semiconductor layer 308. The substrate 300 can be, for example, made of silicon, silicon carbide or sapphire. The buffer layer 302 is disposed on the substrate 300 and the buffer layer 302 can be, for example, made of nitride such as silicon nitride or group-III silicon nitride compound which includes indium silicon nitride. The thickness of the buffer layer 302 can be, for example, less than 10 nano-meters.

Moreover, the buffer layer can also be a complex structure. That is, the buffer layer 302 can be a complex structure (shown in FIG. 3B) comprised of a main buffer layer 302a and a sub-buffer layer 304 disposed over the main buffer layer 302a. As shown in FIG. 3B, the main buffer layer 302a can be, for example, made of nitride such as silicon nitride or group-III silicon nitride including indium silicon nitride. The sub-buffer layer 304 can be made of group-III nitride. The group-III element comprises aluminum, gallium, indium and thallium. Preferably, the aforementioned buffer layer 304 can be made of indium nitride. The main buffer layer 302a and the sub-buffer layer 304 can compose of a buffer layer having a complex structure. That is, as shown in FIG. 3B, when the group-III nitride vertical-rods substrate has a complex-structure buffer layer 302, the buffer layer 302 has the complex structure can be, for example, a silicon nitride/group-III nitride complex layer. Moreover, in FIG. 3B, the thickness of the main buffer layer 302a is about 10 nano meters and the thickness of the sub-buffer layer is about 1˜50 nano meters. On the other words, as shown in FIG. 3B, when the buffer layer is a complex layer having the main buffer layer 302a and the sub-buffer layer 304, the thickness of the buffer layer 302, the complex-structure buffer layer, is about 1˜60 nano meters.

Furthermore, the aforementioned vertical rod layer 306 is located over the aforementioned buffer layer and the vertical rod layer 306 is composed of several vertical rods 306a disposed over the substrate 300. Each of the vertical rods 306a can be, for example, made of group-III nitride. Preferably, for example, the vertical rods are made of gallium nitride. Further, the thickness of the vertical rod layer 306 is about 10 nano meters ˜5 micrometers. It should be noticed that the distribution density of the vertical rods 306a of the vertical rod layer 306 over the substrate 300 is about 10⁹/cm²˜10¹²/cm².

FIG. 4 is a cross-sectional view showing a vertical rod of a group-III nitride vertical-rods substrate according to one embodiment of the present invention. As shown in FIG. 4, the diameter d of the cross-section of a single vertical rod 306a is about 60˜150 nano meters. It should be noticed that each vertical rod 306a possesses relatively high monomorphism property and is free from the dislocation phenomenon.

In addition, the group-III nitride vertical-rods substrate of the present invention further comprises a semiconductor layer 308. The thickness of the semiconductor layer 308 is larger than 20 micro meters. The semiconductor layer 308 can be, for example, made of group-III nitride. Preferably, the semiconductor layer 308 is made of gallium nitride. This semiconductor layer 308 is an epitaxial layer serving as a substrate for later formed group-III nitride device.

By using the grain arrangement provided by the surface of the buffer layer or the complex-structure buffer layer, the vertical rods perpendicular to the surface of the substrate are formed on the buffer layer, wherein each of the vertical rods has relatively high monomorphism property and is free from the dislocation phenomenon. While the semiconductor layer is formed over the vertical-rod layer, the dislocations in the semiconductor layer epitaxially formed on the vertical rod layer is uniform distributed since the surface of the vertical rod layer provides a dislocation free epitaxial environment.

Furthermore, since the vertical rod layer is located between the substrate and the semiconductor layer in the group-III nitride vertical-rods substrate of the present invention, the vertical rod layer can be served as a stress releasing point between heterogeneous lattices. Therefore, the thickness of the semiconductor layer formed over the vertical rod layer is relatively large. Additionally, by using the vertical rod layer as a structure attenuate point, it is easy to separate the semiconductor layer from the substrate through the vertical rod layer.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing descriptions, it is intended that the present invention covers modifications and variations of this invention if they fall within the scope of the following claims and their equivalents.

Claims

1. A group-III nitride vertical-rods substrate, comprising: a substrate;a buffer layer located over the substrate; anda vertical rod layer located on the buffer layer, wherein the vertical rod layer is comprised of a plurality of vertical rods standing on the buffer layer.

2. The group-III nitride vertical-rods substrate of claim 1, wherein the material of each of the vertical rod includes group-III nitride.

3. The group-III nitride vertical-rods substrate of claim 1, wherein the material of each of the vertical rod includes gallium nitride.

4. The group-III nitride vertical-rods substrate of claim 1, wherein the buffer layer is a complex layer.

5. The group-III nitride vertical-rods substrate of claim 4, wherein the complex layer includes a silicon nitride/group-III nitride layer.

6. The group-III nitride vertical-rods substrate of claim 4, wherein the thickness of the buffer layer is about 1˜60 nano meters.

7. The group-III nitride vertical-rods substrate of claim 1, wherein the material of the buffer layer includes silicon nitride.

8. The group-III nitride vertical-rods substrate of claim 7, wherein the thickness of the buffer layer is less than 10 nano meters.

9. The group-III nitride vertical-rods substrate of claim 1, wherein a diameter of a cross-section of each of the vertical rods is about 60˜150 nano meters.

10. The group-III nitride vertical-rods substrate of claim 1 further comprising a group-III nitride layer located on the vertical rod layer.

11. The group-III nitride vertical-rods substrate of claim 1, wherein the thickness of the vertical rod layer is about 10 nano meters˜5 micro meters.

12. The group-III nitride vertical-rods substrate of claim 1, wherein the distribution density of the vertical rods of the vertical rod layer over the substrate is about 109/cm2˜1012/cm2.

13. A group-III nitride vertical-rods substrate, comprising: a substrate;a vertical rod layer on the substrate, wherein the vertical rod layer is comprised of a plurality of monomorphism vertical rods; anda group III nitride semiconductor layer on the vertical rod layer.

14. The group-III nitride vertical-rods substrate of claim 13 further comprising a silicon nitride buffer layer located between the substrate and the vertical rod layer.

15. The group-III nitride vertical-rods substrate of claim 14, wherein the thickness of the silicon nitride layer is less than 10 nano meters.

16. The group-III nitride vertical-rods substrate of claim 14, wherein a sub-buffer layer is located between the silicon nitride buffer layer and the vertical rod layer.

17. The group-III nitride vertical-rods substrate of claim 16, wherein the thickness of the sub-buffer layer is about 1˜50 nano meters.

18. The group-III nitride vertical-rods substrate of claim 16, wherein the material of the sub-buffer layer includes group-III nitride.

19. The group-III nitride vertical-rods substrate of claim 13, wherein the material of each of the vertical rod includes group-III nitride.

20. The group-III nitride vertical-rods substrate of claim 13, wherein the material of each of the vertical rods includes gallium nitride.

21. The group-III nitride vertical-rods substrate of claim 13, wherein the thickness of the vertical rod layer is about 10 nano meters˜5 micro meters.

22. The group-III nitride vertical-rods substrate of claim 13, wherein the distribution density of the vertical rods of the vertical rod layer over the substrate is about 109/cm2˜1012/cm2.

23. The group-III nitride vertical-rods substrate of claim 13, wherein a diameter of a cross-section of each of the vertical rods is about 60˜150 nano meters.