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CN-224234069-U - Schottky P-GaN grid structure

CN224234069UCN 224234069 UCN224234069 UCN 224234069UCN-224234069-U

Abstract

The utility model provides a Schottky P-GaN gate structure, which belongs to the technical field of semiconductors and comprises a substrate, a buffer layer, a trench gate structure, a Schottky metal layer and a P-GaN layer, wherein the buffer layer is sequentially arranged on the substrate, the trench gate structure is formed on the buffer layer, the trench gate structure comprises a plurality of trenches which are mutually parallel, the bottom and the side wall of each trench are sequentially provided with the Schottky metal layer and the P-GaN layer, the Schottky metal layer is tightly attached to the bottom and the side wall of each trench, the P-GaN layer is filled above the Schottky metal layer, the top of the P-GaN layer is level with the top surface of the buffer layer, and the thickness of the Schottky metal layer is larger than that of the side wall at the bottom of each trench.

Inventors

  • WANG PILONG
  • WANG XINQIANG
  • TAN WENTAO
  • YANG YUZHEN
  • MA LINA

Assignees

  • 青岛佳恩半导体有限公司

Dates

Publication Date
20260512
Application Date
20250326

Claims (9)

  1. 1. A Schottky P-GaN gate structure is characterized by comprising a substrate, a buffer layer, a trench gate structure, a Schottky metal layer and a P-GaN layer, wherein the buffer layer is sequentially arranged on the substrate, the trench gate structure is formed on the buffer layer, the trench gate structure comprises a plurality of trenches which are mutually parallel, the Schottky metal layer and the P-GaN layer are sequentially arranged on the bottom and the side wall of each trench, the Schottky metal layer is tightly attached to the bottom and the side wall of each trench, the P-GaN layer is filled above the Schottky metal layer, the top of the P-GaN layer is level with the top surface of the buffer layer, the thickness of the Schottky metal layer is larger than that of the side wall at the bottom of each trench, the thickness of the P-GaN layer is larger than that of the edge region at the central region of each trench, and the distance between two adjacent trenches in the trench gate structure is 1.5-3 times of the width of each trench.
  2. 2. The schottky P-GaN gate structure of claim 1, wherein the trench has a trapezoidal cross-sectional structure with a bottom width smaller than a top width, an included angle between the bottom and the sidewall of the trench is 120 ° -160 °, a depth of the trench is 0.5 μm-3 μm, a top width of the trench is 1 μm-5 μm, and a bottom width of the trench is 0.3 μm-3 μm.
  3. 3. The Schottky P-GaN gate structure of claim 1, wherein the thickness of the Schottky metal layer is 50-150 nm at the bottom of the trench, the thickness of the Schottky metal layer is 20-80 nm at the side wall of the trench, and a nanoscale roughened structure is arranged at the contact interface of the Schottky metal layer and the trench and used for enhancing the contact area of the Schottky metal layer and the trench.
  4. 4. The Schottky P-GaN gate structure of claim 3, wherein the substrate is a silicon carbide substrate or a sapphire substrate, the thickness of the substrate is 200-500 μm, the surface of the substrate is polished to have a surface roughness of less than 0.1nm, and the diameter of the substrate is 2-6 in.
  5. 5. The Schottky P-GaN gate structure of claim 4, wherein the buffer layer comprises a bottom buffer sub-layer and a top buffer sub-layer, the bottom buffer sub-layer is directly arranged on the surface of the substrate, the top buffer sub-layer is arranged on the upper surface of the bottom buffer sub-layer, the thickness of the bottom buffer sub-layer is 10 nm-50 nm, the thickness of the top buffer sub-layer is 1-3 μm, and the bottom buffer sub-layer and the top buffer sub-layer are integrally formed in an in-situ epitaxial mode.
  6. 6. The schottky P-GaN gate structure according to claim 5, wherein the side walls of the trenches are inclined, the upward inclination angle from the bottoms of the trenches is 5-15 degrees, arc transition structures are adopted at four corners of the bottoms of the trenches, and the radius of the arc is 50-100 nm.
  7. 7. The schottky P-GaN gate structure according to claim 6, wherein the schottky metal layer forms a protrusion structure in a central area of the bottom of the trench, the protrusion height is 10 nm-30 nm, the protrusion structure is semi-ellipsoidal, and the long axis direction is parallel to the length direction of the trench.
  8. 8. The schottky P-GaN gate structure of claim 7, wherein the top surface of the P-GaN layer is formed with an arc-shaped protrusion having an arc height of 10nm to 50nm.
  9. 9. The schottky P-GaN gate structure of claim 8, wherein the number of trenches is 3-10, the plurality of trenches are uniformly spaced on the top surface of the buffer layer, and the distance between adjacent trenches is 2-8 μm.

Description

Schottky P-GaN grid structure Technical Field The utility model belongs to the technical field of semiconductors, and particularly relates to a Schottky P-GaN grid structure. Background With the rapid development of power electronics technology, gaN-based power devices have great potential in the fields of high frequency, high power and high temperature application due to the excellent characteristics of wide forbidden band, high breakdown field strength, high electron mobility and the like. In the prior art, the grid structure of the GaN-based power device mainly comprises a metal grid and a P-GaN grid. The metal grid (such as Schottky grid) has lower on-resistance and quick switching speed, but has the problems of large grid leakage current, poor high-temperature stability and the like, and the P-GaN grid has higher breakdown voltage and good high-temperature stability, but has higher on-resistance. To address the limitations of single material gate structures, researchers have tried a variety of composite gate structures such as metal/insulator/semiconductor structures, field plate assist gate structures, and the like. However, these structures are complex in manufacturing process, difficult in interface quality control, and limited in electric field distribution optimization effect. Particularly, under the application scenes of high voltage, high frequency and high temperature, the prior art is difficult to meet the requirements of low on-resistance, high breakdown voltage and high temperature stability at the same time, and the application range and the performance improvement of the GaN-based power device are limited. Disclosure of utility model In view of the above, the present utility model provides a schottky P-GaN gate structure, which can solve the problem that the existing composite gate structure is difficult to satisfy the low on-resistance, high breakdown voltage and high temperature stability at the same time. The utility model is realized in the following way: The utility model provides a Schottky P-GaN gate structure, which comprises a substrate, a buffer layer, a trench gate structure, a Schottky metal layer and a P-GaN layer, wherein the buffer layer is sequentially arranged on the substrate, the trench gate structure is formed on the buffer layer, the trench gate structure comprises a plurality of trenches which are mutually parallel, the Schottky metal layer and the P-GaN layer are sequentially arranged on the bottom and the side wall of each trench, the Schottky metal layer is tightly attached to the bottom and the side wall of each trench, the P-GaN layer is filled above the Schottky metal layer, the top of the P-GaN layer is level with the top surface of the buffer layer, the thickness of the Schottky metal layer is larger than that of the side wall at the bottom of each trench, the thickness of the P-GaN layer is larger than that of the edge region at the central region of each trench, and the distance between two adjacent trenches in the trench gate structure is 1.5-3 times of the width of each trench. The Schottky P-GaN gate structure has the technical effects that the Schottky metal layer and the P-GaN layer are combined in the groove structure to form the composite gate structure, so that the advantages of low on-resistance of the Schottky metal gate and high breakdown voltage of the P-GaN gate are achieved, meanwhile, the control capacity of the gate to a channel region is enhanced due to the thickening design of the Schottky metal layer at the bottom of the groove, the electric field distribution is optimized due to the fact that the central thickness of the P-GaN layer is larger than that of the edge region, the phenomenon of concentration of electric fields at the edge of the gate is restrained, and the current density and the power density of the device are improved due to the distance design between adjacent grooves. Based on the technical scheme, the Schottky P-GaN gate structure can be improved as follows: The groove is of a trapezoid cross-section structure, the width of the bottom is smaller than the width of the top, an included angle between the bottom of the groove and the side wall is 120-160 degrees, the depth of the groove is 0.5-3 microns, the width of the top of the groove is 1-5 microns, and the width of the bottom of the groove is 0.3-3 microns. The improved scheme has the advantages that the electric field distribution of the grid is optimized through the groove structure with the trapezoid cross section, the electric field crowding effect of the edge of the grid is reduced, the breakdown voltage of the device is improved, the cavity formation in the metal filling process of the grid is reduced through the included angle design, the process reliability is improved, the switching speed and the on-resistance of the device are optimized while the control capability of the grid is guaranteed through the groove depth and the groove width design, and the comprehe