SiC power device with inner step structure

Abstract

The invention relates to the technical field of semiconductor devices, in particular to a SiC power device with an inner step structure, which comprises an ohmic contact electrode, an N + SiC substrate, an N-SiC epitaxy and a Schottky contact electrode, and is characterized in that a first bowl-shaped groove is formed in the upper surface of the N-SiC epitaxy, and a first P-type junction terminal is fixedly arranged at the bottom of the side wall of the first bowl-shaped groove; a second bowl-shaped groove is arranged above the first bowl-shaped groove, a second P-type junction terminal is fixedly arranged below the Schottky contact electrode, a circular truncated cone is fixedly arranged at the center of the bottom of the first bowl-shaped groove, and a third P-type junction terminal is fixedly arranged between the circular truncated cone and the second P-type junction terminal. And the upper surface of the circular truncated cone is connected with the lower surface of the Schottky contact electrode. According to the invention, the first P-type junction terminal, the second P-type junction terminal and the third P-type junction terminal are in bowl-shaped distribution, and the bowl-shaped distribution design enables the fringe electric field distribution of the device to be smoother, thereby reducing the electric field concentration.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a SiC power device with an inner step structure. Background Art

[0002] The edge termination structure is an indispensable technology in high breakdown voltage power devices. It is used to prevent local electric field spikes, thereby avoiding early impact ionization and destructive breakdown. The most common way to achieve edge termination is through junction termination extension. In traditional silicon carbide (SiC) power devices, p- or n-type doped junction terminations can be selectively created by ion implantation or diffusion.

[0003] A Chinese patent with publication number CN108281491B discloses a silicon carbide power device with a step structure and a preparation method thereof. In the silicon carbide power device, the P-type junction terminal is distributed on the high and low step surfaces of the annular step of the N-SiC epitaxial layer. On the one hand, the electric field intensity in the terminal area is reduced in a jump-like manner, resulting in uneven distribution of the electric field at the P-type junction terminal. On the other hand, it causes local heat accumulation in the terminal area, reducing the stability of the device under high temperature conditions. Summary of the invention

[0004] The object of the present invention is to provide a SiC power device with an inner step structure to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a SiC power device with an inner step structure, comprising an ohmic contact electrode, an N + SiC substrate, N - SiC epitaxial and Schottky contact electrodes, the N - The upper surface of the SiC epitaxial layer is provided with a first bowl-shaped groove. - A first P-type junction terminal is fixedly disposed on the SiC epitaxial portion and at the bottom of the side wall of the first bowl-shaped groove. - A second bowl-shaped groove is provided on the SiC epitaxy and above the first bowl-shaped groove, and a second P-type junction terminal is fixedly provided at the bottom of the sidewall of the second bowl-shaped groove and below the Schottky contact electrode. - A truncated cone is fixedly disposed on the SiC epitaxy and at the bottom center of the first bowl-shaped groove. - A third P-type junction terminal is fixedly provided on the SiC epitaxy and located between the truncated cone body and the second P-type junction terminal. The upper surface of the truncated cone body is connected to the lower surface of the Schottky contact electrode.

[0006] Optionally, the N + A ceramic package is fixedly disposed on the upper surface of the SiC substrate, and the inner wall of the ceramic package is connected to the N- The outer wall of the SiC epitaxial part is threadedly connected, and the upper surface of the Schottky contact electrode is fixedly passed through the center of the upper surface of the ceramic package.

[0007] Optionally, the first P-type junction terminal, the second P-type junction terminal and the third P-type junction terminal are all closed ring structures with uniform thickness and have the same P-type doping concentration, and the P-type doping concentration of the first P-type junction terminal is 1×10 19 cm -3 .

[0008] Optionally, the thickness of the first P-type junction terminal, the thickness of the second P-type junction terminal and the thickness of the third P-type junction terminal are equal, and the thickness of the first P-type junction terminal is 10 nm.

[0009] Optionally, the ring width of the first P-type junction terminal, the ring width of the second P-type junction terminal and the ring width of the third P-type junction terminal are equal, and the ring width of the first P-type junction terminal is 5 μm.

[0010] Optionally, the included angle between the side generatrix of the first bowl-shaped groove and its bottom surface is 120°, and the included angle between the side generatrix of the second bowl-shaped groove and its bottom surface is 120°.

[0011] Compared with the prior art, the present invention has the following beneficial effects: in the present invention, the first P-type junction terminal, the second P-type junction terminal and the third P-type junction terminal are distributed in a bowl shape. The bowl-shaped distribution design makes the edge electric field distribution of the device smoother and reduces the electric field concentration. On the one hand, it helps to alleviate the electric field strength of the device under high voltage conditions, thereby improving the voltage resistance of the device. On the other hand, it can effectively reduce the edge electric field concentration phenomenon, thereby reducing the sharp changes in electric field strength and improving the energy efficiency and static performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a top view of the present invention without installing the ceramic package.

[0013] In the figure: 100, ohmic contact electrode; 200, N + SiC substrate; 300, N - SiC epitaxy; 301, first bowl-shaped groove; 302, second bowl-shaped groove; 303, truncated cone; 400, Schottky contact electrode; 500, first P-type junction terminal; 600, second P-type junction terminal; 700, third P-type junction terminal; 800, ceramic package. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] Example: See Figure 1 The present invention provides a SiC power device with an inner step structure, comprising an ohmic contact electrode 100, N + SiC substrate 200, N - SiC epitaxy 300 and Schottky contact electrode 400, N - A first bowl-shaped groove 301 is formed on the upper surface of the SiC epitaxy 300, and the angle between the side generatrix of the first bowl-shaped groove 301 and its bottom surface is 120°. - A first P-type junction terminal 500 is fixedly disposed on the SiC epitaxy 300 and at the bottom of the side wall of the first bowl-shaped groove 301. - A second bowl-shaped groove 302 is provided on the SiC epitaxy 300 and above the first bowl-shaped groove 301. The angle between the side busbar of the second bowl-shaped groove 302 and its bottom surface is 120°. A second P-type junction terminal 600 is fixedly provided at the bottom of the side wall of the second bowl-shaped groove 302 and below the Schottky contact electrode 400. - A truncated cone 303 is fixedly disposed on the SiC epitaxy 300 and at the bottom center of the first bowl-shaped groove 301. - A third P-type junction terminal 700 is fixedly provided on the SiC epitaxy 300 and between the truncated cone 303 and the second P-type junction terminal 600 . The upper surface of the truncated cone 303 is connected to the lower surface of the Schottky contact electrode 400 .

[0016] The first P-type junction terminal 500, the second P-type junction terminal 600 and the third P-type junction terminal 700 are distributed in a bowl shape. The bowl-shaped distribution design makes the edge electric field distribution of the device smoother and reduces the electric field concentration. On the one hand, it helps to alleviate the electric field strength of the device under high voltage conditions, thereby improving the voltage resistance of the device. On the other hand, it can effectively reduce the edge electric field concentration phenomenon, thereby reducing the sharp change of the electric field strength and improving the energy efficiency and static performance of the device. In addition, the bowl-shaped distribution design can increase the P-type junction terminal and N - The contact surface area of ​​the SiC epitaxy 300 is increased, thereby reducing thermal resistance and improving heat dissipation efficiency.

[0017] Based on the above embodiments, in this embodiment, N + A ceramic package 800 is fixed on the upper surface of the SiC substrate 200. The inner wall of the ceramic package 800 is connected to the N -The outer wall of the SiC epitaxial 300 is threadedly connected, and the upper surface of the Schottky contact electrode 400 is fixedly passed through the center of the upper surface of the ceramic package 800 .

[0018] See also Figure 2 On the basis of the above embodiment, in this embodiment, the first P-type junction terminal 500, the second P-type junction terminal 600 and the third P-type junction terminal 700 are all closed ring structures with uniform thickness and have the same P-type doping concentration. The P-type doping concentration of the first P-type junction terminal 500 is 1×10 19 cm -3 The thickness of the first P-type junction terminal 500, the thickness of the second P-type junction terminal 600 and the thickness of the third P-type junction terminal 700 are equal, and the thickness of the first P-type junction terminal 500 is 10 nm. The ring width of the first P-type junction terminal 500, the ring width of the second P-type junction terminal 600 and the ring width of the third P-type junction terminal 700 are equal, and the ring width of the first P-type junction terminal 500 is 5 μm.

[0019] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A SiC power device with an inner step structure, comprising an ohmic contact electrode (100), an N + SiC substrate (200), N - SiC epitaxy (300) and Schottky contact electrode (400), characterized in that: The N - The upper surface of the SiC epitaxial (300) is provided with a first bowl-shaped groove (301), wherein the N - A first P-type junction terminal (500) is fixedly provided on the SiC epitaxy (300) and at the bottom of the side wall of the first bowl-shaped groove (301), and the N - A second bowl-shaped groove (302) is provided on the SiC epitaxy (300) and is located above the first bowl-shaped groove (301); a second P-type junction terminal (600) is fixedly provided at the bottom of the side wall of the second bowl-shaped groove (302) and is located below the Schottky contact electrode (400); - A truncated cone (303) is fixedly provided on the SiC epitaxy (300) and at the bottom center of the first bowl-shaped groove (301), wherein the N - A third P-type junction terminal (700) is fixedly provided on the SiC epitaxy (300) and located between the truncated cone (303) and the second P-type junction terminal (600), and the upper surface of the truncated cone (303) is connected to the lower surface of the Schottky contact electrode (400).

2. The SiC power device with an inner step structure according to claim 1, characterized in that: The N + A ceramic package (800) is fixedly disposed on the upper surface of the SiC substrate (200), and the inner wall of the ceramic package (800) is in contact with the N - The outer wall of the SiC epitaxial (300) is threadedly connected, and the upper surface of the Schottky contact electrode (400) is fixedly passed through the center of the upper surface of the ceramic package (800).

3. The SiC power device with an inner step structure according to claim 1, characterized in that: The first P-type junction terminal (500), the second P-type junction terminal (600) and the third P-type junction terminal (700) are all closed ring structures with uniform thickness and have the same P-type doping concentration. The P-type doping concentration of the first P-type junction terminal (500) is 1×10 19 cm -3 .

4. The SiC power device with an inner step structure according to claim 3, characterized in that: The thickness of the first P-type junction terminal (500), the thickness of the second P-type junction terminal (600) and the thickness of the third P-type junction terminal (700) are equal, and the thickness of the first P-type junction terminal (500) is 10 nm.

5. The SiC power device with an inner step structure according to claim 3, characterized in that: The ring widths of the first P-type junction terminal (500), the second P-type junction terminal (600) and the third P-type junction terminal (700) are equal, and the ring width of the first P-type junction terminal (500) is 5 μm.

6. The SiC power device with an inner step structure according to claim 1, characterized in that: The included angle between the side generatrix of the first bowl-shaped groove (301) and its bottom surface is 120°, and the included angle between the side generatrix of the second bowl-shaped groove (302) and its bottom surface is 120°.

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