Search

CN-113644118-B - Composite substrate and method for producing the same

CN113644118BCN 113644118 BCN113644118 BCN 113644118BCN-113644118-B

Abstract

The invention provides a composite substrate and a preparation method thereof, wherein the composite substrate comprises a III-V group substrate, a first substrate and a second substrate, wherein the III-V group substrate is provided with a III group polar surface and a V group polar surface; and the ohmic contact layer is positioned on the V-group polar surface of the III-V substrate. The preparation method comprises the steps of providing a III-V substrate, wherein the III-V substrate is provided with a III polar surface and a V polar surface, and forming an ohmic contact layer on the V polar surface of the III-V substrate. The preparation method comprises the steps of providing a supporting substrate, forming an ohmic contact layer on the surface of the supporting substrate, forming a III-V group substrate on the surface of the ohmic contact layer, wherein the III-V group substrate is provided with a III group polar surface and a V group polar surface, the V group polar surface is in direct contact with the ohmic contact layer, and removing the supporting substrate. According to the invention, by arranging the ohmic contact layer, the carrier concentration of the composite substrate is improved, the contact resistance is reduced, and the heat stability of ohmic contact and the performance of a device are improved.

Inventors

  • XU LIN
  • JIN CHAO
  • ZHAO MAOMAO

Assignees

  • 苏州纳维科技有限公司

Dates

Publication Date
20260505
Application Date
20210728

Claims (15)

  1. 1. A composite substrate, comprising: A III-V substrate, wherein the III-V substrate is provided with a III polar surface and a V polar surface, the III-V substrate adopts undoped GaN material or semi-insulating GaN material, the thickness is 1-1000 mu m, and the carrier concentration is lower than 1 multiplied by 10 17 cm -3 ; The ohmic contact layer is positioned on the V-group polar surface of the III-V group substrate, the ohmic contact layer is made of a GaN material with high carrier concentration, the thickness of the ohmic contact layer is 10nm-1000 mu m, the GaN material with high carrier concentration is doped with shallow energy level donor impurities, the carrier concentration is higher than 1X 10 19 cm -3 , and the shallow energy level donor impurities are Si, ge or O.
  2. 2. The composite substrate according to claim 1, wherein the ohmic contact layer is made of a high-conductivity GaN single crystal material, and has a thickness of 1 μm to 1000 μm.
  3. 3. The composite substrate according to claim 1, wherein the group III-V substrate adopts a low impurity concentration epitaxial layer with a thickness of 1 μm-1000 μm and a carrier concentration of less than 1 x 10 17 cm -3 .
  4. 4. The composite substrate according to claim 1, wherein the materials of the III-V substrate and the ohmic contact layer are respectively binary III-V semiconductor materials, ternary, quaternary and multi-element III-V semiconductor materials formed by a plurality of III-elements and a plurality of V-elements, or binary, ternary and multi-element III-V semiconductor materials formed by III-elements and V-elements with different forbidden band widths.
  5. 5. A method of preparing a composite substrate, comprising: providing a III-V substrate, wherein the III-V substrate is provided with a III polar surface and a V polar surface, the III-V substrate adopts an undoped GaN material or a semi-insulating GaN material, the thickness is 1-1000 mu m, and the carrier concentration is lower than 1X 10 17 cm -3 ; and forming an ohmic contact layer on the V-group polar surface of the III-V substrate, wherein the ohmic contact layer is made of a high-carrier concentration GaN material, the thickness of the ohmic contact layer is 10nm-1000 mu m, the high-carrier concentration GaN material is doped with shallow-level donor impurities, the carrier concentration of the high-carrier concentration GaN material is higher than 1X 10 19 cm -3 , and the shallow-level donor impurities are Si, ge or O.
  6. 6. The method of claim 5, wherein the group III-V substrate and the ohmic contact layer are respectively formed of a binary group III-V semiconductor material, a ternary, quaternary and multi-element group III-V semiconductor material formed of a plurality of group III elements and a plurality of group V elements, or a binary, ternary and multi-element group III-V semiconductor material formed of a group III element and a group V element with different forbidden band widths.
  7. 7. The method of claim 5, wherein the method of forming the ohmic contact layer is selected from one or more of hydride vapor phase epitaxy, metal organic chemical vapor deposition, molecular beam epitaxy, ammonothermal method, and Na flux method.
  8. 8. A method of preparing a composite substrate, comprising: Providing a supporting substrate; Forming an ohmic contact layer on the surface of the supporting substrate, wherein the ohmic contact layer is made of a high-carrier-concentration GaN material, the thickness of the ohmic contact layer is 10nm-1000 mu m, the high-carrier-concentration GaN material is doped with shallow-level donor impurities, the carrier concentration of the high-carrier-concentration GaN material is higher than 1X 10 19 cm -3 , and the shallow-level donor impurities are Si, ge or O; Forming a III-V substrate on the surface of the ohmic contact layer, wherein the III-V substrate is provided with a III polar surface and a V polar surface, the V polar surface is in direct contact with the ohmic contact layer, the III-V substrate is made of undoped GaN material or semi-insulating GaN material, the thickness is 1-1000 mu m, and the carrier concentration is lower than 1X 10 17 cm -3 ; And removing the supporting substrate.
  9. 9. The method of claim 8, wherein the III-V substrate and the ohmic contact layer are formed of a binary III-V semiconductor material, a ternary, quaternary and multi-element III-V semiconductor material formed of a plurality of III-elements and a plurality of V-elements, or a binary, ternary and multi-element III-V semiconductor material formed of a III-element and a V-element, respectively, having different forbidden band widths.
  10. 10. The method of claim 8, wherein the methods of forming the ohmic contact layer and the group III-V substrate are each selected from one or more of hydride vapor phase epitaxy, metal organic chemical vapor deposition, molecular beam epitaxy, ammonothermal method, na flux method.
  11. 11. The method of claim 8, wherein the support substrate comprises a GaN single crystal substrate, a sapphire substrate, a Si substrate, or a SiC substrate.
  12. 12. The method of claim 8, wherein removing the support substrate is by laser lift-off or grinding.
  13. 13. A method of preparing a composite substrate, comprising: Providing an ohmic contact layer, wherein the ohmic contact layer is made of III-V group materials and has III-group polar surfaces and V-group polar surfaces, the ohmic contact layer is made of high-carrier-concentration GaN materials, the thickness of the ohmic contact layer is 10nm-1000 mu m, the high-carrier-concentration GaN materials are doped with shallow-level donor impurities, the carrier concentration of the high-carrier-concentration GaN materials is higher than 1X 10 19 cm -3 , and the shallow-level donor impurities are Si, ge or O; And forming a III-V substrate on the III-group polar surface of the ohmic contact layer, wherein the III-V substrate adopts an epitaxial layer with low impurity concentration, the thickness is 1-1000 mu m, and the carrier concentration is lower than 1 multiplied by 10 17 cm -3 .
  14. 14. The method of claim 13, wherein the ohmic contact layer is made of a high-conductivity GaN single crystal material and has a thickness of 1 μm to 1000 μm.
  15. 15. The method of claim 13, wherein the method of forming the group III-V substrate is selected from one or a combination of several methods selected from the group consisting of hydride vapor phase epitaxy, metal organic chemical vapor deposition, molecular beam epitaxy, ammonothermal method, na flux method.

Description

Composite substrate and method for producing the same Technical Field The invention relates to the field of semiconductors, in particular to a composite substrate and a preparation method thereof. Background Gallium nitride (GaN) is a direct band gap semiconductor material, has the advantages of large forbidden band width, high breakdown field strength, good chemical stability and the like, and is an ideal substrate material for preparing GaN-based photoelectron 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, effectively inhibit the interface from forming two-dimensional hole gas and improve the reliability of the device, and provides a composite substrate and a preparation method thereof. In order to solve the problems, the invention provides a composite substrate, which comprises a III-V substrate and an ohmic contact layer, wherein the III-V substrate is provided with a III-polar surface and a V-polar surface, and the ohmic contact layer is positioned on the V-polar surface of the III-V 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 substrate, wherein the III-V substrate is provided with a III polar surface and a V polar surface, and forming an ohmic contact layer on the V polar surface of the III-V substrate. The invention provides another preparation method of a composite substrate, which comprises the steps of providing a supporting substrate, forming an ohmic contact layer on the surface of the supporting substrate, forming a III-V group substrate on the surface of the ohmic contact layer, wherein the III-V group substrate is provided with a III group polar surface and a V group polar surface, the V group polar surface is in direct contact with the ohmic contact layer, and removing the supporting substrate. The invention also provides a preparation method of the composite substrate, which comprises the steps of providing an ohmic contact layer, wherein the ohmic contact layer is made of III-V group materials and is provided with a III-group polar surface and a V-group polar surface, an