A SiC power device that disperses the fringing electric field

Abstract

The present invention relates to the technical field of semiconductor devices, and specifically to a SiC power device for dispersing edge electric fields, which includes an ohmic contact electrode, an N+ SiC substrate, an N− SiC epitaxy, and a Schottky contact electrode. The N− SiC epitaxy includes a disc-shaped member fixedly connected to the N+ SiC substrate, and a frustum-shaped member integrally formed with the disc-shaped member. A plurality of annular grooves are provided at equal intervals on the inclined surface of the frustum-shaped member, and a P-type junction terminal is fixedly provided in the annular groove. The vertex angle of the P-type junction terminal away from the disc-shaped member is located outside the annular groove. A ceramic package is fixedly provided on the upper surface of the disc-shaped member and outside the frustum-shaped member, and a heat sink is fixedly provided on the outer surface of the ceramic package. In the present invention, the P-type junction terminals are concentrically and stepwise distributed on the N− SiC epitaxy, which can gradually reduce the electric field strength in the terminal region, effectively relieve the electric field concentration phenomenon at the edge, thereby improving the breakdown voltage of the device, reducing the breakdown risk, and can also reduce the leakage current, improving the static performance and switching loss of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a SiC power device for dispersing fringe electric fields. Background Art

[0002] In SiC (silicon carbide) power devices, due to the discontinuity of the junction, the electric field lines tend to concentrate at the edge areas of the junction, resulting in high electric fields in these areas. The presence of this high electric field may cause premature breakdown at the junction edge, which severely limits the reverse breakdown voltage of the device. To address this problem, a variety of junction termination technologies are usually used in the design and manufacturing process of SiC power devices to reduce the concentration effect of the edge electric field and thus increase the breakdown voltage of the device. These technologies can effectively optimize the electric field distribution and enhance the performance and reliability of the device.

[0003] The Chinese patent with publication number CN108281491B discloses a silicon carbide power device with a step structure and a preparation method thereof, wherein the P-type junction terminal of the silicon carbide power device is distributed on the N - On the high and low step surfaces of the SiC epitaxial layer's annular step, on the one hand, the electric field strength in the terminal area decreases 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 that disperses the fringe electric field 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 for dispersing the edge electric field, comprising an ohmic contact electrode, an N + SiC substrate, N - SiC epitaxial and Schottky contact electrodes, the N - SiC epitaxy includes the N + A circular cake member fixedly connected to a SiC substrate, and a truncated table member integrally formed with the circular cake member, the inclined surface of the truncated table member is provided with a plurality of annular grooves arranged at equal intervals, and the vertical interval between two adjacent annular grooves is greater than the horizontal interval between two adjacent annular grooves, a P-type junction terminal is fixedly provided in the annular groove, the vertex of the P-type junction terminal away from the circular cake member is located outside the annular groove, a ceramic package is fixedly provided on the upper surface of the circular cake member and outside the truncated table member, and a heat sink is fixedly provided on the outer surface of the ceramic package;

[0006] The ceramic package is a truncated cone structure, the upper surface of the Schottky contact electrode is fixedly passed through the center of the upper surface of the ceramic package, a plurality of through holes are opened on the inclined surface of the ceramic package, the length direction of the through holes points to the top corner of the P-type junction terminal away from the circular cake piece, and a hollow thermal conductive column is integrally formed on the end surface of the heat sink close to the ceramic package, and the hollow thermal conductive column is fixedly passed through the through hole and extends into the ceramic package.

[0007] Optionally, the forward longitudinal section of the annular groove is a right triangle, and the ratio of the vertical spacing between two adjacent annular grooves to the horizontal spacing between two adjacent annular grooves is 1.5 to 2:1.

[0008] Optionally, the P-type junction terminal is a closed ring structure, and several of the P-type junction terminals are distributed in concentric circles outside the Schottky contact electrode, and the lower surface of the lowest P-type junction terminal is fixedly connected to the upper surface of the circular cake member.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1. In the present invention, the P-type junction terminal is at N - The SiC epitaxy is distributed in a concentric stepped pattern, and the P-type junction terminals are evenly distributed, which can gradually reduce the electric field strength in the terminal area and effectively alleviate the electric field concentration phenomenon at the edge, thereby increasing the breakdown voltage of the device, reducing the breakdown risk, and reducing the leakage current, thereby improving the static performance and switching loss of the device;

[0011] 2. In the present invention, the P-type junction terminal is at N - The SiC epitaxy is distributed in a concentric stepped pattern, which can reduce local heat accumulation and improve the stability of the device under high temperature conditions. Heat is dissipated by conduction through hollow thermal conductive columns and heat sinks. Each P-type junction terminal has its corresponding hollow thermal conductive column for heat conduction, which can better absorb the heat from the P-type junction terminal. The ceramic package and heat sink have high structural strength, can withstand certain mechanical pressure, and can adapt to fans of different wind directions, whether blowing from top to bottom or from bottom to top, and can effectively exchange heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the present invention;

[0013] Figure 2 It is a partial cross-sectional view of the present invention;

[0014] Figure 3 for Figure 2 Schematic diagram of the structure with the A part in the middle enlarged.

[0015] In the figure: 100, ohmic contact electrode; 200, N +SiC substrate; 300, N - SiC epitaxy; 301, round cake piece; 302, truncated cone piece; 303, annular groove; 400, Schottky contact electrode; 500, P-type junction terminal; 600, ceramic package; 601, through hole; 700, heat sink; 701, hollow thermal conductive column. DETAILED DESCRIPTION

[0016] 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.

[0017] Example: See Figure 1 and Figure 2 The present invention provides a SiC power device for dispersing the edge electric field, comprising an ohmic contact electrode 100, N + SiC substrate 200, N - SiC epitaxy 300 and Schottky contact electrode 400. - SiC epitaxy 300 includes N + The SiC substrate 200 is fixedly connected to the circular cake member 301, and the truncated cone member 302 is integrally formed with the circular cake member 301. The inclined surface of the truncated cone member 302 is provided with a plurality of annular grooves 303 arranged at equal intervals. The positive longitudinal section of the annular groove 303 is a right triangle. The annular groove 303 is fixedly provided with a P-type junction terminal 500. The P-type junction terminal 500 and the N - The SiC epitaxy 300 forms a PN heterojunction. The top corner of the P-type junction terminal 500 away from the circular cake member 301 is located outside the annular groove 303. A ceramic package 600 is fixedly provided on the upper surface of the circular cake member 301 and outside the truncated cone member 302. The ceramic package 600 is a truncated cone structure. The upper surface of the Schottky contact electrode 400 is fixedly passed through the center of the upper surface of the ceramic package 600, and a heat sink 700 is fixedly provided on the outer surface of the ceramic package 600.

[0018] In the above embodiment, the vertical spacing between two adjacent annular grooves 303 in this embodiment is greater than the horizontal spacing between two adjacent annular grooves 303, and the ratio of the vertical spacing between two adjacent annular grooves 303 to the horizontal spacing between two adjacent annular grooves 303 is 1.5 to 2:1. In this embodiment, the ratio of the vertical spacing between two adjacent annular grooves 303 to the horizontal spacing between two adjacent annular grooves 303 is :1, that is, the angle between the side surface of the circular cake member 301 and its bottom surface is 60°. The P-type junction terminal 500 is a closed ring structure, and a plurality of P-type junction terminals 500 are distributed outside the Schottky contact electrode 400 in a concentric circle manner, and the lower surface of the lowest P-type junction terminal 500 is fixedly connected to the upper surface of the circular cake member 301.

[0019] P-type junction terminal 500 in N - The SiC epitaxy 300 is distributed in a concentric stepped manner, and the P-type junction terminal 500 is evenly distributed, which can gradually reduce the electric field strength in the terminal area and effectively alleviate the electric field concentration phenomenon at the edge, thereby increasing the breakdown voltage of the device, reducing the breakdown risk, and reducing the leakage current, thereby improving the static performance and switching loss of the device.

[0020] See also Figure 3 In addition to the above embodiment, the ceramic package 600 in this embodiment has a plurality of through holes 601 on the inclined surface, the length direction of the through holes 601 points to the top corner of the P-type junction terminal 500 away from the round cake 301, and the end surface of the heat sink 700 close to the ceramic package 600 is integrally formed with a hollow heat-conducting column 701, the heat sink 700 is made of insulating heat-conducting material, and the hollow heat-conducting column 701 is fixed through the through hole 601 and extends into the ceramic package 600. The P-type junction terminal 500 is at N - The SiC epitaxy 300 is distributed in a concentric stepped manner, which can reduce local heat accumulation and improve the stability of the device under high temperature conditions. Heat is dissipated by conduction through the hollow thermal conductive column 701 and the heat sink 700. Each P-type junction terminal 500 has its corresponding hollow thermal conductive column 701 for heat conduction, which can better absorb the heat from the P-type junction terminal 500. The ceramic package 600 and the heat sink 700 have high structural strength, can withstand a certain amount of mechanical pressure, and can adapt to fans of different wind directions, whether blowing from top to bottom or from bottom to top, and can effectively exchange heat.

[0021] 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 for dispersing an edge electric field, 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 SiC epitaxy (300) includes the N + A disk member (301) fixedly connected to a SiC substrate (200), and a truncated cone member (302) integrally formed with the disk member (301), the inclined surface of the truncated cone member (302) being provided with a plurality of annular grooves (303) arranged at equal intervals, and the vertical interval between two adjacent annular grooves (303) being greater than the horizontal interval between two adjacent annular grooves (303), a P-type junction terminal (500) being fixedly provided in the annular groove (303), the vertex of the P-type junction terminal (500) being away from the disk member (301) being located outside the annular groove (303), a ceramic package (600) being fixedly provided on the upper surface of the disk member (301) and outside the truncated cone member (302), and a heat sink (700) being fixedly provided on the outer surface of the ceramic package (600); The ceramic package (600) is a truncated cone structure. The upper surface of the Schottky contact electrode (400) is fixedly passed through the center of the upper surface of the ceramic package (600). The inclined surface of the ceramic package (600) is provided with a plurality of through holes (601). The length direction of the through holes (601) points to the top corner of the P-type junction terminal (500) away from the circular cake (301). The end surface of the heat sink (700) close to the ceramic package (600) is integrally formed with a hollow heat-conducting column (701). The hollow heat-conducting column (701) is fixedly passed through the through hole (601) and extends into the ceramic package (600).

2. The SiC power device for dispersing fringe electric fields according to claim 1, characterized in that: The forward longitudinal section of the annular groove (303) is a right triangle, and the ratio of the vertical spacing between two adjacent annular grooves (303) to the horizontal spacing between two adjacent annular grooves (303) is 1.5 to 2:

1.

3. The SiC power device for dispersing fringe electric fields according to claim 1, characterized in that: The P-type junction terminal (500) is a closed ring structure, and a plurality of the P-type junction terminals (500) are distributed in concentric circles outside the Schottky contact electrode (400), and the lower surface of the lowest P-type junction terminal (500) is fixedly connected to the upper surface of the circular cake member (301).

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