阅读说明：本技术 一种SiC MPS二极管器件及其制备方法 (SiC MPS diode device and preparation method thereof ) 是由 何艳静 刘延聪 胡彦飞 袁昊 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 MPS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,其特征在于,两个所述P+注入区之间设置有沟槽结构,在沟槽结构两侧与P+注入区之间分别设有N+注入区,且所述N+注入区将P+注入区包围在内,形成阱结构；本发明SiC MPS二极管器件设有沟槽结构,集成了沟槽结构的SiC MPS二极管器件可以促使PiN结构与肖特基结构体内电势在器件正向导通时更加均匀,接近PiN体内电势分布情况,有效抑制器件出现压降急速返回的现象,在沟槽型SiC MPS二极管的基础上,在原有的PiN二极管上多进行一次N+注入,目的是提高PiN晶体管注入效率,提高器件的浪涌能力。(The invention discloses a SiC MPS 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, the N + injection region is respectively arranged between the two sides of the groove structure and the P + injection region, and the P + injection region is surrounded by the N + injection region to form a well structure; the SiC MPS diode device is provided with the groove structure, the SiC MPS diode device integrated with the groove structure can make the internal potentials of the Pin structure and the Schottky structure more uniform when the device is conducted in the forward direction and approach the potential distribution situation in the Pin structure, the phenomenon of rapid return of voltage drop of the device is effectively inhibited, and on the basis of the groove type SiC MPS diode, N + injection is carried out on the original Pin diode for one time, so that the injection efficiency of the Pin transistor is improved, and the surge capacity of the device is improved.)

1. The utility model provides a SiC MPS diode device, includes negative pole (6), N + substrate (5), N-epitaxial layer (4), P + injection zone (2) and positive pole (1) that set gradually from bottom to top, its characterized in that:

a trench structure (7) is arranged between the two P + injection regions (2), Schottky metal is deposited on the trench structure (7), the depth of the trench structure (7) is smaller than that of the P + injection regions (2), and the surface of the P + injection regions (2) is an ohmic contact interface;

an N + injection region (3) is arranged between the groove structure (7) and the P + injection region (2), the N + injection region (3) surrounds the P + injection region (2) at the corresponding position to form a well structure, and the edge of the N + injection region (3) is located on the groove structure (7) but is not covered by Schottky metal.

2. The SiC MPS diode device according to claim 1, characterized in that the trench structure (7) has a width of 1-2 μm and a depth of 0.5-0.8 μm.

3. The SiC MPS diode device according to claim 2, characterized in that the depth of the P + implant region (2) is 0.8-2 μm and the edge of the trench structure (7) is 0.2-0.8 μm apart from the P + implant region (2).

4. The SiC MPS diode device of claim 1, wherein said N + implanted region (3) has an implantation concentration higher than the concentration of said N-epitaxial layer (4).

5. The SiC MPS diode device of claim 1, wherein the N + implant region (3) is 3-4 μm deep.

6. The SiC MPS diode device of claim 1, wherein said schottky metal is Ti or Ni.

7. The method of fabricating the SiC MPS diode device of claim 1, comprising the steps of:

s1, forming an N-epitaxial layer (4) on the N + substrate (5) through epitaxial growth;

s2 preparation of SiO on N-epitaxial layer (4)₂A mask layer, wherein a mask pattern is formed by using a photoetching process, and an N + injection region (3) is formed by using an N ion injection means;

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, 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 groove structure (7) by using an ICP (inductively coupled plasma) etching method;

s5, performing carbon film protection on the surface of the N-epitaxial layer (4), activating implanted ions through high-temperature annealing, and removing the carbon film through an oxidation method;

s6 deposition of SiO₂Forming an isolation medium, photoetching and etching to form a P + injection region (2) ohmic contact region, depositing ohmic contact metal on the front surface and the back surface of the epitaxial wafer, and performing a rapid thermal annealing process under the Ar atmosphere to form ohmic contact;

s7, protecting the back of the epitaxial wafer, etching the front groove structure (7) to form a Schottky contact window, depositing Schottky 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;

and S8, 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 MPS 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, and having these characteristics at the same time is the most desirable goal we pursue. MPS (large PiN/Schottky) is a device combining the advantages of PiN and SBD, and the forward characteristics of the structure are similar to SBD, with small turn-on voltage, large conduction current, fast switching speed; the reverse characteristic is more like a PiN diode, and has low leakage current and high breakdown voltage. The use of MPS structure allows us to flexibly select metals with low barrier as schottky contacts without fear of increased reverse leakage current. In addition, the combination of the excellent performance of SiC materials and the advantages of MPS structure can exert greater advantages, and is also the trend of the development of current power rectifier devices.

Problems with SiC MPS diode devices: the current SiC MPS diode has a forward current bounce phenomenon called snapback when turned on, and the bipolar degradation causes the degradation of the forward function of the device.

Disclosure of Invention

In order to solve the above problems, the present invention provides a SiC MPS diode device and a method for manufacturing the same, in which a trench type SiC MPS diode device that performs N + injection can effectively suppress the occurrence of a forward current bounce phenomenon and increase the injection efficiency of the device.

The first purpose of the invention is to provide a SiC MPS diode device, which comprises a cathode, an N + substrate, an N-epitaxial layer, a P + injection region and an anode which are arranged from bottom to top in sequence, wherein a groove structure is arranged between the two P + injection regions, Schottky metal is deposited on the groove structure, the depth of the groove structure is less than that of the P + injection regions, and the surface of the P + injection region is an ohmic contact interface;

and N + injection regions are respectively arranged between the trench structure and the P + injection regions, the N + injection regions surround the P + injection regions at corresponding positions to form a well structure, and the edges of the N + injection regions are positioned on the trench structure but are not covered by Schottky metal.

Preferably, the width of the groove structure is 1-2 μm, and the depth is 0.5-0.8 μm.

Preferably, the depth of the P + injection region is 0.8-2 μm, and the distance between the edge of the trench structure and the P + injection region is 0.2-0.8 μm.

Preferably, the implantation concentration of the N + implantation region is higher than that of the N-epitaxial layer.

Preferably, the depth of the N + injection region is 3-4 μm.

Preferably, the schottky metal is Ti or Ni.

A second object of the present invention is to provide a method for manufacturing the above SiC MPS diode device, comprising the steps of:

s1, forming an N-epitaxial layer on the N + substrate through epitaxial growth, wherein the whole structure for forming the N-epitaxial layer is generally 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 an N + injection region by using an N ion injection means;

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, 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 groove structure by using an ICP (inductively coupled plasma) etching method;

s5, 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;

s6 deposition of SiO₂Forming an isolation medium, photoetching and etching to form a P + injection region ohmic contact region, depositing ohmic contact metal on the front surface and the back surface of the epitaxial wafer, and performing a rapid thermal annealing process under the atmosphere of Ar to form ohmic contact;

s7, protecting the back of the epitaxial wafer, etching the front groove structure to form a Schottky contact window, depositing Schottky 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;

and S8, 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 MPS diode device, the SiC MPS diode device provided by the invention is provided with the groove structure, the SiC MPS diode device integrated with the groove structure can enable the internal potential of the Pin structure and the Schottky structure to be more uniform when the device is conducted in the forward direction and approach the internal potential distribution condition of the Pin structure, the phenomenon of rapid return of voltage drop of the device is effectively inhibited, and on the basis of the groove type SiC MPS diode, N + injection is carried out on the original Pin diode for one time, so that the injection efficiency of the Pin transistor is improved, and the surge capacity of the device is improved.

Drawings

FIG. 1 is a schematic cross-sectional view of the structure of a SiC MPS diode device fabricated in example 1;

FIG. 2 is a schematic cross-sectional view of the structure of a SiC MPS diode device fabricated in example 2;

FIG. 3 is a forward characteristic curve of the SiC MPS diode device fabricated in example 1;

description of reference numerals:

wherein, 1, anode; 2. a P + implantation region; 3. an N + injection region; 4. an N-epitaxial layer; 5. an N + substrate; 6. a cathode; 7. 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 conventional materials and commercially available, unless otherwise specified.

The invention provides a SiC MPS diode device, which comprises a cathode 6, an N + substrate 5, an N-epitaxial layer 4, a P + injection region 2 and an anode 1 which are sequentially arranged from bottom to top, wherein a groove structure 7 is arranged between the two P + injection regions 2, Schottky metal is deposited on the groove structure 7, the depth of the groove structure 7 is smaller than that of the P + injection region 2, and the surface of the P + injection region 2 is an ohmic contact interface; an N + injection region 3 is respectively arranged between the trench structure 7 and the P + injection region 2, the N + injection region 3 surrounds the P + injection region 2 at a corresponding position to form a well structure, and the edge of the N + injection region 3 is located on the trench structure 7 but is not covered by schottky metal.

The SiC MPS diode device is provided with the groove structure, the SiC MPS diode device integrated with the groove structure can make the internal potentials of the Pin structure and the Schottky structure more uniform when the device is conducted in the forward direction and approach the potential distribution situation in the Pin structure, the phenomenon of rapid return of voltage drop of the device is effectively inhibited, and on the basis of the groove type SiC MPS diode, N + injection is carried out on the original Pin diode for one time, so that the injection efficiency of the Pin transistor is improved, and the surge capacity of the device is improved.

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

s1: forming an N-epitaxial layer 4 on an N + substrate 5 through epitaxial growth; the overall structure forming the N-epitaxial layer is generally referred to as an epitaxial wafer;

s2: preparation of SiO on N-epitaxial layer 4₂A mask layer, a mask pattern is formed by using a photoetching process, and an N + injection region 3 is formed by an N ion injection means;

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: 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 groove structure 7 by using an ICP (inductively coupled plasma) etching method;

s5: performing carbon film protection on the surface of the epitaxial layer, activating implanted ions through high-temperature annealing, and removing the carbon film through an oxidation method;

s6: deposition of SiO₂Forming an isolation medium, photoetching and etching to form a P + injection region 2 ohmic contact region, depositing ohmic contact metal on the front surface and the back surface of the epitaxial wafer, and performing a rapid thermal annealing process under the atmosphere of Ar to form ohmic contact;

s7: protecting the back, etching the front groove structure 7 to form a Schottky contact window, depositing Schottky 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;

s8: and forming thick electrodes on the front surface and the back surface by a metal deposition process.

The SiC MPS diode device and the method of manufacturing the same according to the present invention will be specifically explained by the following examples.