CN220065710U

CN220065710U - FRD with low thermal resistance and low conduction voltage drop

Info

Publication number: CN220065710U
Application number: CN202321540167.8U
Authority: CN
Inventors: 吴小利; 王海军
Original assignee: Shanghai Qingmao Microelectronics Technology Co ltd
Current assignee: Shanghai Qingmao Microelectronics Technology Co ltd
Priority date: 2023-06-16
Filing date: 2023-06-16
Publication date: 2023-11-21
Anticipated expiration: 2033-06-16

Abstract

The utility model relates to a FRD with low thermal resistance and low conduction voltage drop, which comprises a substrate, an anode positioned on one side of the substrate and a cathode positioned on the other side of the substrate, wherein an anode metal layer is arranged on the surface of the anode, a cathode metal layer is arranged on the surface of the cathode, a plurality of deep grooves are formed on the surface of the anode or the cathode, the anode metal layer or the cathode metal layer extends into the deep grooves, and a high doping area is arranged on the surface of the side wall or the bottom wall of the deep grooves. The FRD with low thermal resistance and low conduction pressure drop increases the heat dissipation area by arranging the deep grooves on the surface, has higher heat dissipation effect, and does not need to independently arrange a special heat dissipation device outside the device so as to reduce the volume of the device and facilitate the integration of the device and the IGBT.

Description

FRD with low thermal resistance and low conduction voltage drop

Technical Field

The utility model relates to a diode, in particular to a FRD with low thermal resistance and low conduction voltage drop.

Background

The FRD fast recovery diode is a semiconductor diode with good switching characteristics and short reverse recovery time, is usually used in anti-parallel with an IGBT, generates a large amount of heat as a control module of a motor under some low-frequency high-current working conditions, such as motor stalling, and greatly limits the performance and safety of a product because the FRD is usually small in area and the temperature rises too fast. The reduction of energy consumption and thermal resistance is an urgent problem to be solved by FRD under these working conditions.

In a common FRD structure, the heat conduction of the anode mainly depends on anode metal and binding wires on the surface, the thickness of the anode metal is usually only 3-5um, a better heat conduction medium is lacking on the metal surface, the heat resistance is far greater than that of the cathode, the heat resistance can be effectively reduced by increasing the thickness of the anode metal, but the heat resistance is limited by the processing time and the cost, and enough optimization space is not available.

Chinese patent publication No. CN112687541a, entitled "FRD device with high heat dissipation and process for manufacturing the same", discloses an FRD device in which heat dissipation of a diode chip is achieved by mounting a heat dissipation device communicating with the inside and outside on a device case. Although the problem of FRD heat dissipation can be solved, a special heat dissipation device is arranged outside the chip, so that the whole size of the device is increased, and the integration of the device and the IGBT is not facilitated.

Disclosure of Invention

In order to solve the technical problems, the utility model aims to provide the FRD with low heat resistance and low conduction voltage drop, wherein the FRD is provided with a heat dissipation speed block and reduced conduction voltage.

The FRD comprises a substrate, an anode positioned on one side of the substrate and a cathode positioned on the other side of the substrate, wherein an anode metal layer is arranged on the surface of the anode, a cathode metal layer is arranged on the surface of the cathode, a plurality of deep grooves are formed in the surface of the anode, the anode metal layer extends into the deep grooves, and a high doping area is formed on the surface of the side wall or the bottom wall of the deep grooves.

The FRD with low thermal resistance and low conduction voltage drop has the advantages that the surface of the anode is provided with a plurality of deep grooves, and the anode metal layer extends into the deep grooves. The deep groove filled with metal improves the contact area between the anode and the metal layer thereof, and provides a good heat dissipation channel for heat near the PN junction, thereby greatly improving the heat dissipation efficiency of the FRD and reducing the thermal resistance of the device.

The arrangement of the deep groove can not change the original metal process. Compared with the existing fast recovery diode, the FRD has the advantages that the deep groove is formed in the surface, the radiating area is increased, the radiating effect is high, a special radiating device is not required to be independently arranged outside the device, the size of the device is reduced, and the device is convenient to integrate with an IGBT.

Meanwhile, the high doped region at the bottom of the deep groove or/and on the surface of the side wall forms an approximate structure of the self-adjusting P emission efficiency diode, when high concentration ions at the bottom of the deep groove or/and on the side wall can be the anode reverse bias between the surface and the groove, the electric field is shielded to avoid electric leakage, so that the ion concentration of the anode region is reduced, and the PN junction voltage drop during low current can be effectively reduced. Under the working condition of high current, the PN junction of the anode high doping region is opened, and more carriers can be injected into the drift region, so that the saturation voltage drop at the moment is reduced.

Furthermore, the FRD with low thermal resistance and low conduction voltage drop is characterized in that a contact hole cell area is arranged on the surface of the anode, a plurality of contact hole cells are arranged in the contact hole cell area, and a deep groove is formed on the surface of the anode of each contact Kong Yuanbao.

The design enables operators to realize ion implantation through the contact hole layout, and then the high doped region is formed. In this embodiment, the heavily doped region is a p+ doped region.

Furthermore, the FRD with low thermal resistance and low conduction voltage drop is characterized in that the density of contact hole cells in the middle of the contact hole cell area is smaller than that of contact hole cells at two sides of the contact hole cell area.

This design optimizes the uniformity of the current distribution of the device.

Furthermore, the FRD with low thermal resistance and low conduction voltage drop is characterized in that the deep groove is a strip-shaped deep groove, and the high doping area is positioned on the bottom wall surface of the deep groove.

The foregoing description is merely an overview of the embodiments of the present utility model, and is intended to provide a more clear understanding of the technical means of the present utility model, as embodied in the present utility model, by way of example only.

Drawings

FIG. 1 is a schematic plan view of a prior art FRD;

FIG. 2 is a partial cross-sectional view of a prior art FRD;

FIG. 3 is a schematic plan view of a FRD with low thermal resistance and low conduction voltage drop;

fig. 4 is a partial cross-sectional view of a low thermal resistance low conduction voltage drop FRD.

In the figure, a substrate 1, an anode 2, an anode metal layer 3, a deep groove 4, a highly doped region 5 and a contact hole cell 6.

Detailed Description

The following describes in further detail the embodiments of the present utility model with reference to the drawings and examples. The following examples are illustrative of the utility model and are not intended to limit the scope of the utility model.

Referring to fig. 3 to 4, the FRD with low thermal resistance and low conduction voltage drop of the present embodiment includes a substrate 1, an anode 2 located at one side of the substrate, and a cathode (not shown in the figure) located at the other side of the substrate, wherein an anode metal layer 3 is disposed on the surface of the anode, a cathode metal layer is disposed on the surface of the cathode, a plurality of deep grooves 4 are disposed on the surface of the anode, the anode metal layer extends into the deep grooves, and a highly doped region 5 is disposed on the surface of the side wall or bottom wall of the deep groove.

The FRD with low thermal resistance and low conduction voltage drop is characterized in that a plurality of deep grooves are formed in the surface of an anode, and an anode metal layer extends into the deep grooves. The deep groove filled with metal improves the contact area between the anode and the metal layer thereof, and provides a good heat dissipation channel for heat near the PN junction, thereby greatly improving the heat dissipation efficiency of the FRD and reducing the thermal resistance of the device.

The arrangement of the deep groove can not change the original metal process. Compared with the existing fast recovery diode shown in fig. 1-2, the FRD has the advantages that the heat dissipation area is increased by arranging the deep grooves on the surface, the heat dissipation effect is better, and a special heat dissipation device is not required to be arranged outside the device independently, so that the size of the device is reduced, and the device is convenient to integrate with an IGBT.

Meanwhile, the high doped region on the bottom wall or/and the side wall of the deep groove forms an approximate structure with the self-adjusting P emission efficiency diode, when high concentration ions at the bottom or/and the side wall of the deep groove can be reversely biased to the anode NP junction between the surface and the groove, the electric field is shielded to avoid electric leakage, so that the ion concentration of the anode region is reduced, and the PN junction voltage drop during low current can be effectively reduced. Under the working condition of high current, the PN junction of the anode high doping region is opened, and more carriers can be injected into the drift region, so that the saturation voltage drop at the moment is reduced.

In this embodiment, the substrate is an N-type substrate, the deep groove is disposed on the surface of the P-type anode, and the anode metal layer extends into the deep groove.

The surface of the anode is provided with a plurality of contact hole cell areas, and a plurality of contact hole cell 6 are arranged in the contact hole cell areas. The anode surface of the contact Kong Yuanbao is provided with a strip-shaped deep groove, and the bottom of the deep groove is formed into a P-type high doped region through ion implantation.

During preparation, an operator injects high-concentration P-type doping into the bottom wall surface of the deep groove through the contact hole pattern, so that a P-type doped region is formed, the ion concentration of the P-type doped region is far higher than that of an anode, and a so-called self-adjusting P-emission efficiency diode is formed.

Under the working condition of high current, the P+ anode at the deep groove, namely the high doping area, provides a main current path, and the current in the central area of the FRD is easy to concentrate, so that the current density in the central area can be reduced by reducing the cell density of the contact hole in the central area, and the uniformity of current distribution is optimized. In practice, the operator can achieve the above objective by increasing the distance between contact cells or the width of the cells themselves in the middle area of the contact cell area.

The above is only a preferred embodiment of the present utility model for assisting a person skilled in the art to implement the corresponding technical solution, and is not intended to limit the scope of the present utility model, which is defined by the appended claims. It should be noted that, on the basis of the technical solution of the present utility model, several improvements and modifications equivalent thereto can be made by those skilled in the art, and these improvements and modifications should also be regarded as the protection scope of the present utility model. Meanwhile, it should be understood that, although the present disclosure describes the above embodiments, not every embodiment contains only one independent technical solution, and the description is merely for clarity, and those skilled in the art should consider the disclosure as a whole, and the technical solutions of the embodiments may be combined appropriately to form other embodiments that can be understood by those skilled in the art.

Claims

1. The utility model provides a FRD of low thermal resistance low conduction pressure drop, includes substrate (1), is located positive pole (2) of substrate one side, is located the negative pole of substrate opposite side, and the positive pole surface is equipped with positive pole metal layer (3), and the negative pole surface is equipped with negative pole metal layer, its characterized in that: the surface of the anode is provided with a plurality of deep grooves (4), the anode metal layer extends into the deep grooves, and the surface of the side wall or the bottom wall of the deep grooves is provided with a high doping area (5).

2. The low thermal resistance low conduction voltage drop FRD of claim 1 characterized by: the surface of the anode is provided with a contact hole cell area, a plurality of contact hole cells are arranged in the contact hole cell area, and the surface of the anode of each contact Kong Yuanbao is provided with a deep groove.

3. The low thermal resistance low conduction voltage drop FRD of claim 2 characterized by: the density of contact hole cells in the middle of the contact hole cell area is smaller than that of contact hole cells on two sides of the contact hole cell area.

4. The low thermal resistance low conduction voltage drop FRD of claim 3 characterized by: the deep groove is a strip-shaped deep groove, and the high doping region is positioned on the surface of the bottom wall of the deep groove.