CN-113643978-B - Preparation method of composite substrate and composite substrate

CN113643978BCN 113643978 BCN113643978 BCN 113643978BCN-113643978-B

Abstract

The invention provides a preparation method of a composite substrate and the composite substrate, wherein the preparation method comprises the steps of providing a III-V group single crystal substrate, wherein the III-V group single crystal substrate is provided with a III group polar surface and a V group polar surface; and forming a nanowire layer on the V-group polar surface of the III-V single crystal substrate. The composite substrate comprises a III-V group single crystal substrate and a nanowire layer, wherein the III-V group single crystal substrate is provided with a III group polar surface and a V group polar surface, and the nanowire layer is arranged on the V group polar surface of the III-V group single crystal substrate. According to the invention, the nanowire layer is arranged on the V-group polar surface of the III-V single crystal substrate, so that the problem of poor ohmic contact of the N-polar surface of the GaN substrate is effectively solved, the contact resistance is reduced, the thermal stability of ohmic contact of the N-polar surface is improved, and the reliability of a device is improved.

Inventors

CHEN JIHU
Nie Hengliang
SU KEYONG

Assignees

苏州纳维科技有限公司

Dates

Publication Date: 20260508
Application Date: 20210727

Claims (6)

1. A method of preparing a composite substrate, comprising: Providing a III-V group single crystal substrate, wherein the III-V group single crystal substrate is provided with a III group polar surface and a V group polar surface, the III-V group single crystal substrate adopts undoped GaN material, and the thickness of the III-V group single crystal substrate is 10 mu m-500 mu m; And directly forming a nanowire layer on the V-group polar surface of the III-V group monocrystalline substrate, wherein the nanowire layer is made of GaN material, and the nanowire layer is used for converting ohmic contact on the V-group polar surface into ohmic contact on a nonpolar surface, so that the contact resistance of the V-group polar surface is reduced, and a metal electrode is evaporated on the surface of the nanowire layer.
2. The method of claim 1, wherein the nanowire layer has a thickness of 10 μιη to 100 μιη.
3. The method of claim 1, wherein the nanowire layer is formed by one or more methods selected from the group consisting of hydride vapor phase epitaxy, metal organic chemical vapor deposition, molecular beam epitaxy, ammonothermal method, and Na flux method.
4. The method of claim 1, wherein the nanowire layer is formed by electrochemical etching.
5. A composite substrate, comprising: A III-V group single crystal substrate, wherein the III-V group single crystal substrate is provided with a III group polar surface and a V group polar surface, the III-V group single crystal substrate adopts undoped GaN material, and the thickness of the III-V group single crystal substrate is 10-500 mu m; the nanowire layer is directly arranged on the V-group polar surface of the III-V group monocrystalline substrate, the nanowire layer is made of GaN material and is used for converting ohmic contact on the V-group polar surface into ohmic contact on a nonpolar surface, so that the contact resistance of the V-group polar surface is reduced, and a metal electrode is evaporated on the surface of the nanowire layer.
6. The composite substrate of claim 5, wherein the nanowire layer has a thickness of 10 μιη -100 μιη.

Description

Preparation method of composite substrate and composite substrate Technical Field The invention relates to the field of semiconductors, in particular to a preparation method of a composite substrate and the composite substrate. Background Gallium nitride (GaN) is an ideal substrate material for the fabrication of GaN-based optoelectronic and microelectronic devices. Currently, ga-polarity GaN-based devices have been rapidly developed and are widely used in the fields of semiconductor lighting, laser display, power electronics, and microwave radio frequency. The ohmic contact of the N polar surface is an important problem of GaN-based devices, mainly because (1) in recent years, gaN-based vertical structure devices have received extensive attention, because the vertical structure devices can avoid the problems of fringe electric field concentration and the like faced by conventional planar devices, and weakening the influence of surface states on the performance of the devices is an important direction of the development of GaN-based devices. One electrode of the vertical structure device must be prepared on the N-polar plane of the gallium nitride single crystal substrate. (2) N-polar GaN has different polarity, surface dangling bonds and surface reconstruction modes compared with Ga-polar GaN, so that a plurality of novel device structures can be realized, and performances which are not possessed by Ga-polar devices can be obtained. The N-polarity High Electron Mobility Transistor (HEMT) device can weaken short channel effect and improve high-frequency characteristics of the device. In, al and other impurities are doped more efficiently In the growth process of the N polar material, and components of the GaN-based ternary and quaternary compounds are easier to regulate and control. In the solar cell, the polarized electric field in the N-polarity device can promote the separation of photo-generated electrons and holes, and the efficiency of the solar cell is improved. One electrode of the N-polarity device must also be fabricated on the N-polarity side of the gallium nitride single crystal substrate. However, the ohmic contact on the N-polar surface has the problems of high contact resistance, poor thermal stability and the like, and generally the ohmic contact on the N-polar surface is annealed at a high temperature of 300 ℃ or more, and then is deteriorated or even fails. This is mainly because Al in the electrode material easily diffuses into GaN to form AlN at the interface, and two-dimensional hole gas is formed near the interface due to piezoelectric polarization effect, resulting in deterioration of ohmic characteristics. The device often uses high temperature technology, such as annealing, wire bonding and other technologies, in the preparation process, so that the problem of performance degradation of the device caused by high temperature can be avoided only by improving the thermal stability of the ohmic contact of the N polar surface. Disclosure of Invention The invention aims to solve the technical problem of poor ohmic contact of an N-polar surface of a GaN-based device, improve the thermal stability of the ohmic contact of the N-polar surface, reduce the contact resistance and improve the reliability of the device, and provides a preparation method of a composite substrate and the composite substrate. In order to solve the problems, the invention provides a preparation method of a composite substrate, which comprises the steps of providing a III-V group single crystal substrate, wherein the III-V group single crystal substrate is provided with a III group polar surface and a V group polar surface, and forming a nanowire layer on the V group polar surface of the III-V group single crystal substrate. In order to solve the problems, the invention provides a composite substrate, which comprises a III-V group single crystal substrate and a nanowire layer, wherein the III-V group single crystal substrate is provided with a III group polar surface and a V group polar surface, and the nanowire layer is arranged on the V group polar surface of the III-V group single crystal substrate. According to the invention, the nanowire layer is arranged on the V-group polar surface of the III-V single crystal substrate, so that the problem of poor ohmic contact of the N-polar surface of the GaN substrate is effectively solved, the contact resistance is reduced, the thermal stability of ohmic contact of the N-polar surface is improved, and the reliability of a device is improved. Drawings Figure 1 is a schematic diagram of one embodiment of the present invention. FIGS. 2A-2B are schematic diagrams illustrating a process according to an embodiment of the present invention. Figures 3A-3B are schematic diagrams illustrating a process according to one embodiment of the present invention. Detailed Description The following describes in detail a preparation method of a composite substrate and a specific embodiment of t