阅读说明：本技术 一种SiC JBS二极管器件及其制备方法 (SiC JBS diode device and preparation method thereof ) 是由 袁昊 刘延聪 胡彦飞 何艳静 汤晓燕 宋庆文 张玉明 于 2020-07-27 设计创作，主要内容包括：本发明公开了一种SiC JBS二极管器件及其制备方法,属于微电子技术领域,包括自下而上依次设置的阴极、N+衬底、N-外延层、P+注入区和阳极,两个所述P+注入区之间设置有沟槽结构；本发明在两个P+注入区之间的肖特基接触面下方设置有沟槽结构,沟槽的引入可以增大肖特基接触面积,同时减小寄生电阻,降低了导通电阻,使器件更容易开启,解决了传统SiC JBS二极管由于缺乏载流子的调制导致导通电阻过大的问题。(The invention discloses a SiC JBS diode device and a preparation method thereof, belonging to the technical field of microelectronics, and comprising a cathode, an N + substrate, an N-epitaxial layer, a P + injection region and an anode which are sequentially arranged from bottom to top, wherein a groove structure is arranged between the two P + injection regions; according to the invention, the groove structure is arranged below the Schottky contact surface between the two P + injection regions, the introduction of the groove can increase the Schottky contact area, reduce the parasitic resistance, reduce the on-resistance, enable the device to be easier to open, and solve the problem of overlarge on-resistance caused by lack of carrier modulation of the traditional SiC JBS diode.)

1. The utility model provides a SiC JBS diode device, includes negative pole (5), N + substrate (4), N-epitaxial layer (3), P + injection zone (2) and positive pole (1) that set gradually from bottom to top, its characterized in that, two be provided with trench structure (6) between P + injection zone (2), trench structure (6) are located the Schottky contact interface below between two P + injection zones (2), the degree of depth of trench structure (6) is less than the degree of depth of P + injection zone (2).

2. The SiC JBS diode device of claim 1, wherein the trench structure (6) has a depth of 0.5 to 1 μm and a width of 1 to 3 μm.

3. The SiC JBS diode device of claim 2, wherein the difference between the depth of the trench structure (6) and the depth of the P + implant region (2) is 0.1-3 μm.

4. The SiC JBS diode device of claim 1, wherein the edge of the trench structure (6) is equally spaced from the two P + implant regions (2), each 0.2-0.8 μm.

5. The SiC JBS diode device of claim 1, wherein the metal in contact with the schottky contact interface is Ti or Ni.

6. The method of manufacturing a SiC JBS diode device of claim 1, comprising the steps of:

s1, forming an N-epitaxial layer (3) on the N + substrate (4) through epitaxial growth;

s2 preparation of SiO on N-epitaxial layer (3)₂A mask layer, a mask pattern is formed by using a photoetching process, and a groove structure (6) is formed by using an ICP (inductively coupled plasma) etching method;

s3, cleaning the injection mask layer, forming a new mask layer on the surface, forming a mask pattern by using a photoetching process, and forming a P + injection region (2) by using an Al ion injection means;

s4, performing carbon film protection on the surface of the N-epitaxial layer (3), activating implanted ions through high-temperature annealing, and removing the carbon film through an oxidation method;

s5 deposition of SiO₂Forming an isolation medium, photoetching and etching to form a P + injection region (2) Schottky contact region, depositing Schottky contact metal on the front surface and the back surface of the epitaxial wafer, etching at the front surface groove structure (6) to form a Schottky contact window, depositing the Schottky contact metal, forming an electrode pattern through a photoetching process, and forming Schottky contact in the groove structure region through a low-temperature rapid thermal annealing process;

and S6, forming thick electrodes on the front surface and the back surface of the epitaxial wafer through a metal deposition process.

Technical Field

The invention belongs to the technical field of microelectronics, and particularly relates to a SiC JBS diode device and a preparation method thereof.

Background

In recent years, with the continuous development of power electronic systems, higher requirements are put on power devices in the systems. Si-based power electronics have not been able to meet the requirements of system applications due to the limitations of the materials themselves. Silicon carbide (SiC) materials, as representative of third generation semiconductor materials, are far better than Si materials in many properties.

In SiC power systems, a good rectifier requires a small turn-on voltage, a large conduction current, a low leakage current, a high breakdown voltage and a high switching speed, while having these characteristics is the most desirable goal we pursue. JBS (J-shaped Barrier Schottky) is a device combining the advantages of Pin and SBD, the forward characteristic of the structure is similar to that of SBD, and the structure has small starting voltage, large conduction current and fast switching speed; the reverse characteristic is more like a PiN diode, and has low leakage current and high breakdown voltage. The use of the JBS structure allows us to flexibly select metals with low barrier as schottky contacts without worrying about increased reverse leakage current. In addition, the excellent performance of the SiC material can exert greater advantages by combining with the advantages of the JBS structure, and the SiC material also becomes the development trend of the current power rectifying device.

As shown in fig. 1, the conventional SiC JBS diode structure includes a cathode, an N + substrate, an N-epitaxial layer, a P + injection region, and an anode sequentially arranged from bottom to top, and when the conventional SiC JBS diode is turned on in the forward direction, the current density is slightly lower due to the P-type region, and the on-resistance is too large, which increases the difficulty in turning on the device.

Disclosure of Invention

In order to solve the problems, the invention provides a SiC JBS diode device and a preparation method thereof, wherein the introduction of a groove can increase the Schottky contact area, reduce the parasitic resistance and reduce the on-resistance, thereby reducing the forward starting voltage and enabling the device to be easier to start.

The invention provides a SiC JBS diode device, which comprises a cathode, an N + substrate, an N-epitaxial layer, P + injection regions and an anode which are arranged from bottom to top in sequence, wherein a groove structure is arranged between the two P + injection regions and is positioned below a Schottky contact interface between the two P + injection regions, and the depth of the groove structure is smaller than that of the P + injection regions.

Preferably, the depth of the groove structure is 0.5-1 μm, and the width is 1-3 μm.

Preferably, the difference between the depth of the groove structure and the depth of the P + injection region is 0.1-3 μm.

Preferably, the distance between the edge of the groove structure and the two P + injection regions is equal and is 0.2-0.8 μm.

Preferably, the metal in contact with the schottky contact interface is Ti or Ni.

The second object of the present invention is to provide a method for manufacturing the SiC JBS diode device, comprising the following steps:

s1, forming an N-epitaxial layer on the N + substrate through epitaxial growth; generally, the overall structure after the N-epitaxial layer is formed is called an epitaxial wafer;

s2 preparation of SiO on N-epitaxial layer₂A mask layer, forming a mask pattern by using a photoetching process, and forming a groove structure by using an ICP (inductively coupled plasma) etching method;

s3, cleaning the injection mask layer, forming a new mask layer on the surface, forming a mask pattern by using a photoetching process, and forming a P + injection region by using an Al ion injection means;

s4, performing carbon film protection on the surface of the N-epitaxial layer, activating implanted ions through high-temperature annealing, and removing the carbon film through an oxidation method;

s5 deposition of SiO₂Forming an isolation medium, photoetching and etching to form a P + injection region Schottky contact region, depositing Schottky contact metal on the front surface and the back surface of the epitaxial wafer, etching to form a Schottky contact window at the front surface groove structure, depositing Schottky metal, and etching to form a Schottky contact window at the front surface groove structureForming an electrode pattern by a photoetching process, and forming Schottky contact in the groove structure region by a low-temperature rapid thermal annealing process;

and S6, forming thick electrodes on the front surface and the back surface of the epitaxial wafer through a metal deposition process.

Compared with the prior art, the invention has the following beneficial effects:

compared with the traditional SiC JBS diode device, the Schottky contact area between the two P + injection regions is increased by the groove structure arranged below the Schottky contact surface, the parasitic resistance is reduced, and the on-resistance is reduced, so that the forward starting voltage is reduced, the device is easier to start, and the problem of overlarge on-resistance caused by lack of carrier modulation of the traditional SiC JBS diode is solved.

Drawings

FIG. 1 is a schematic cross-sectional view of a conventional SiC JBS diode device;

FIG. 2 is a schematic cross-sectional view of a SiC JBS diode device structure provided by the present invention;

FIG. 3 is an SEM scanning electron microscope image of a SiC JBS diode device prepared in example 1 of the present invention;

fig. 4 is a forward characteristic curve of a SiC JBS diode device made in example 1 of the present invention;

fig. 5 is a reverse characteristic curve of the SiC JBS diode device manufactured in example 1 of the present invention.

Description of reference numerals:

wherein, 1, anode; 2. a P + implantation region; 3. an N-epitaxial layer; 4. an N + substrate; 5. a cathode; 6. and (5) a groove structure.

Detailed Description

In order to make the technical solutions of the present invention better understood and implemented by those skilled in the art, the present invention is further described below with reference to the following specific embodiments and the accompanying drawings, but the embodiments are not meant to limit the present invention. The following detection methods, unless otherwise specified, are all conventional methods; the materials are commercially available unless otherwise specified.

The invention provides a SiC JBS diode device, which comprises a cathode 5, an N + substrate 4, an N-epitaxial layer 3, P + injection regions 2 and an anode 1, wherein the cathode, the N + substrate, the N-epitaxial layer, the P + injection regions 2 and the anode 1 are sequentially arranged from bottom to top, a groove structure 6 is arranged between the two P + injection regions 2, the groove structure 6 is positioned below a Schottky contact interface between the two P + injection regions 2, and the depth of the groove structure 6 is smaller than that of the P + injection regions 2.

According to the invention, the groove structure is arranged below the Schottky contact surface between the two P + injection regions, the introduction of the groove can increase the Schottky contact area, reduce the parasitic resistance, reduce the on-resistance, enable the device to be easier to open, and solve the problem of overlarge on-resistance caused by lack of carrier modulation of the traditional SiC JBS diode.

The preparation method of the SiC JBS diode device specifically comprises the following steps:

(1) forming an N-epitaxial layer 3 on an N + substrate 4 through epitaxial growth; generally, the overall structure after the N-epitaxial layer is formed is called an epitaxial wafer;

(2) preparation of SiO on N-epitaxial layer 3₂A mask layer, wherein a mask pattern is formed by using a photoetching process, and a groove structure 6 is formed by using an ICP (inductively coupled plasma) etching method;

(3) cleaning the mask layer, forming a new mask layer on the surface through a deposition process, forming a mask pattern through a photoetching process, and forming a P + injection region 2 through an Al ion injection means;

(4) performing carbon film protection on the surface of the N-epitaxial layer 3, activating implanted ions through high-temperature annealing, and removing the carbon film through an oxidation method;

(5) deposition of SiO₂Forming an isolation medium, photoetching and etching to form a P + injection region 2 Schottky contact surface, depositing Schottky contact metal on the front surface and the back surface of the N-epitaxial layer 3, etching at the front surface groove structure to form a Schottky contact window, depositing the Schottky contact metal, forming an electrode pattern through a photoetching process, and forming Schottky contact in a Schottky region through a low-temperature rapid thermal annealing process;

(6) and forming thick electrodes on the front surface and the back surface by a metal deposition process.

The above SiC JBS diode device and the method of making the same are specifically illustrated by the following examples.