High-voltage silicon carbide diode anti-radiation reinforcing structure and method

Abstract

The invention discloses a high-voltage silicon carbide diode anti-radiation reinforcing structure and method, and the structure comprises a silicon carbide Schottky diode main body, an electrode part, a Schottky contact part, a P-type injection window, a floating P island, a deep groove part, an N-type epitaxial layer, and an N-type silicon carbide substrate. A Schottky contact part is arranged below the anode electrode, a deep groove part is arranged in the middle of the lower portion of the Schottky contact part, P-type injection windows are arranged on the two sides of the deep groove part, an N-type silicon carbide substrate is arranged above the cathode electrode, an N-type epitaxial layer is arranged between the N-type silicon carbide substrate and the Schottky contact part, and the N-type epitaxial layer is arranged between the N-type silicon carbide substrate and the Schottky contact part. And a floating P island is arranged on the N-type epitaxial layer. According to the anti-radiation reinforcing structure and method for the high-voltage silicon carbide diode, the single-particle radiation resistance of the silicon carbide diode can be effectively improved under the combined action of the surface structure and the back structure of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon carbide diodes, and in particular to a high-voltage silicon carbide diode radiation resistance reinforcement structure and method. Background Art

[0002] Silicon carbide high-voltage power devices have better electrothermal properties than traditional silicon devices and can work normally in more demanding environments. Therefore, they have broad application prospects in photovoltaic power generation, electric vehicles, aerospace, etc. For the aerospace field, power devices must not only meet the requirements of high voltage, high power, high frequency and low loss, but also have good radiation resistance.

[0003] For high-voltage SiC power devices, radiation hardening is a major difficulty. Current SiC power devices often experience single-particle burnout when the blocking voltage is less than 1 / 3 and the LET is no higher than 10MeV.cm2 / mg, which is far lower than theoretical expectations. Single-particle radiation usually involves very complex electrothermal coupling responses inside the device. When heavy ions bombard the power device, a large number of electron-hole pairs are generated along the motion trajectory. These electron-hole pairs drift under the action of the electric field, forming a large instantaneous current inside the device. Some electrons and holes will also accumulate at both ends of the device, thereby reconstructing the electric field inside the device, resulting in strong electric field breakdown in the local part of the device, such as single-particle gate breakdown. In addition, this large amount of electron-hole movement and strong electric field coupling generate huge instantaneous heat inside the device, which may cause single-particle burnout in the local part of the device.

[0004] In order to solve the deficiencies of the prior art, the present invention proposes a high-voltage silicon carbide diode radiation-resistant reinforcement structure, which introduces deep trenches on the surface of the device, and injects P-type impurities into the sidewalls and bottom of the deep trenches to form a P-type doped region, fills the grooves with high-concentration P-type and N-type polysilicon, and the N-type polysilicon is surrounded by P-type polysilicon, and introduces a floating P island facing the Schottky contact on the back of the device. The deep trench structure introduces a strong electric field into the body, and at the same time, uses a larger P-type doped area and P-type polysilicon to greatly enhance the hole extraction efficiency in the body at the moment of heavy ion bombardment. In addition, the N-type polysilicon short-circuited with the anode will accelerate the recombination of the extracted holes with the electrons in the N-type polysilicon, further improving the excess carrier extraction speed; the floating P island on the back provides protection for the N- / N+ junction by forming a wider depletion region during reverse blocking, and inhibits the N- / N+ junction from avalanche breakdown during heavy ion bombardment. The combined effect of the device surface and back structures can effectively improve the single-particle radiation resistance of the silicon carbide diode. Summary of the invention

[0005] The purpose of the present invention is to provide a high-voltage silicon carbide diode anti-radiation reinforcement structure and method to further improve the excess carrier extraction speed; the floating P island on the back side provides protection for the N- / N+ junction by forming a wider depletion region during reverse blocking, thereby suppressing the avalanche breakdown of the N- / N+ junction during heavy ion bombardment. The combined effect of the device surface and back structure can effectively improve the single-particle radiation resistance of the silicon carbide diode.

[0006] The present invention provides a high-voltage silicon carbide diode radiation resistance reinforcement structure and method, comprising a silicon carbide Schottky diode body, an electrode part, a Schottky contact part, a P-type injection window, a floating P island, a deep groove part, an N-type epitaxial layer, and an N-type silicon carbide substrate, wherein the electrode part comprises an anode electrode and a cathode electrode, a Schottky contact part is provided below the anode electrode, a deep groove part is provided in the middle below the Schottky contact part, P-type injection windows are provided on both sides of the deep groove part, an N-type silicon carbide substrate is provided above the cathode electrode, an N-type epitaxial layer is provided between the N-type silicon carbide substrate and the Schottky contact part, and a floating P island is provided on the N-type epitaxial layer.

[0007] Preferably, the deep trench includes a P-type doped region and a P-type injected region, the P-type doped region is located outside the P-type injected region, P-type impurities are provided inside the P-type doped region, the P-type doped region is located on the sidewall and bottom of the deep trench, the P-type injected region in the deep trench includes N-type polysilicon and P-type polysilicon, and the N-type polysilicon filling is surrounded by the P-type polysilicon filling.

[0008] Preferably, the P-type doped region, the P-type injection region, and the whole composed of N-type polysilicon and P-type polysilicon in the P-type injection region in the deep trench are arranged between the P-type injection windows, and 2-30 P-type injection windows are arranged between the P-type doped region, the P-type injection region, and the whole composed of N-type polysilicon and P-type polysilicon in the P-type injection region in the deep trench.

[0009] Preferably, the specific ratio of the deep trench and the P-type implantation window is adjusted according to the depth of the deep trench.

[0010] Preferably, the anode electrode is located at the top of the silicon carbide Schottky diode body, and the cathode electrode is located at the bottom of the silicon carbide Schottky diode body.

[0011] Preferably, the method comprises the following steps:

[0012] S1. Introducing a deep trench portion on the surface of the silicon carbide Schottky diode body, injecting P-type impurities into the sidewalls and bottom of the deep trench portion to form a P-type doped region, filling the deep trench portion with high concentrations of P-type polysilicon and N-type polysilicon to form a P-type implanted region, wherein the N-type polysilicon in the P-type implanted region is surrounded by P-type polysilicon, and the ratio of the deep trench portion to the P-type implanted window is adjusted according to the depth of the deep trench portion;

[0013] S2. A floating P island is introduced on the back of the main body of the silicon carbide Schottky diode, which is directly opposite to the Schottky contact part. The deep trench part introduces a strong electric field into the deep trench, and at the same time uses the P-type doped area and P-type polysilicon to enhance the efficiency of hole extraction in the body at the moment of heavy ion bombardment.

[0014] S3, short-circuiting the N-type polysilicon and the anode electrode accelerates the recombination of the extracted holes with the electrons in the N-type polysilicon, increases the speed of excess carrier extraction, and removes the electron-hole pairs generated by heavy ion bombardment;

[0015] S4. The P-type injection window on the back side of the silicon carbide Schottky diode body forms a wide depletion region during reverse blocking.

[0016] Therefore, the present invention adopts the above-mentioned high-voltage silicon carbide diode anti-radiation reinforcement structure and method to further improve the excess carrier extraction speed; the floating P island on the back side provides protection for the N- / N+ junction by forming a wider depletion region during reverse blocking, thereby suppressing the avalanche breakdown of the N- / N+ junction during heavy ion bombardment. The combined effect of the device surface and back structure can effectively improve the silicon carbide diode's ability to resist single-particle radiation.

[0017] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is an overall structural diagram of a high-voltage silicon carbide diode radiation-resistant reinforcement structure and method of the present invention;

[0019] Figure 2 A schematic diagram of a deep trench structure of a high-voltage silicon carbide diode radiation-resistant reinforcement structure and method of the present invention;

[0020] Figure 3 The present invention is a schematic diagram of a process flow of a high-voltage silicon carbide diode radiation resistance reinforcement structure and method.

[0021] Reference numerals

[0022] 1. Electrode part; 2. Schottky contact part; 3. P-type injection window; 4. Floating P island; 5. Deep trench part; 6. N-type epitaxial layer; 7. N-type silicon carbide substrate; 8. Anode electrode; 9. Cathode electrode; 10. P-type doping region; 11. P-type injection region. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0024] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0025] The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprises" and similar terms mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and similar terms are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0026] Embodiment 1

[0027] like Figure 1-Figure 3 As shown, the present invention provides a high-voltage silicon carbide diode radiation resistance reinforcement structure and method, including a silicon carbide Schottky diode body, an electrode part 1, a Schottky contact part 2, a P-type injection window 3, a floating P island 4, a deep trench part 5, an N-type epitaxial layer 6, and an N-type silicon carbide substrate 7. The electrode part 1 includes an anode electrode 8 and a cathode electrode 9. A Schottky contact part 2 is provided below the anode electrode 8, a deep trench part 5 is provided in the middle below the Schottky contact part 2, P-type injection windows 3 are provided on both sides of the deep trench part 5, an N-type silicon carbide substrate 7 is provided above the cathode electrode 9, an N-type epitaxial layer 6 is provided between the N-type silicon carbide substrate 7 and the Schottky contact part 2, and a floating P island 4 is provided on the N-type epitaxial layer 6.

[0028] The deep trench portion 5 includes a P-type doped region 10 and a P-type injected region 11. The P-type doped region 10 is located outside the P-type injected region 11. P-type impurities are arranged inside the P-type doped region 10. The P-type doped region 10 is located on the sidewall and bottom of the deep trench half portion 5. The P-type injected region 11 in the deep trench portion 5 includes N-type polysilicon and P-type polysilicon. The filling of the N-type polysilicon is surrounded by the filling of the P-type polysilicon.

[0029] The P-type doped region 10 in the deep trench portion 5, the P-type injection region 11, and the N-type polysilicon and P-type polysilicon in the P-type injection region 11 as a whole are arranged between the P-type injection windows 3, and 2-30 P-type injection windows 3 are arranged between the P-type doped region 10 in the deep trench portion 5, the P-type injection region 11, and the N-type polysilicon and P-type polysilicon in the P-type injection region 11 as a whole.

[0030] The specific ratio of the deep trench portion 5 and the P-type implantation window 3 is adjusted according to the depth of the deep trench portion 5 .

[0031] The anode electrode 8 is located on the top of the silicon carbide Schottky diode body, and the cathode electrode 9 is located on the bottom of the silicon carbide Schottky diode body.

[0032] The P-type implantation window 3 is located below the Schottky contact portion 2 , and the floating P island 4 is located above the N-type silicon carbide substrate 7 .

[0033] The method comprises the following steps: S1, introducing a deep trench portion on the surface of the main body of the silicon carbide Schottky diode, injecting P-type impurities into the sidewalls and the bottom of the deep trench portion to form a P-type doped region, filling the deep trench portion with high concentrations of P-type polysilicon and N-type polysilicon to form a P-type implanted region, wherein the N-type polysilicon in the P-type implanted region is surrounded by the P-type polysilicon, and the ratio of the deep trench portion to the P-type implanted window is adjusted according to the depth of the deep trench portion;

[0034] S2. A floating P island is introduced on the back of the main body of the silicon carbide Schottky diode, which is directly opposite to the Schottky contact part. The deep trench part introduces a strong electric field into the deep trench, and at the same time uses the P-type doped area and P-type polysilicon to enhance the efficiency of hole extraction in the body at the moment of heavy ion bombardment.

[0035] S3, short-circuiting the N-type polysilicon and the anode electrode accelerates the recombination of the extracted holes with the electrons in the N-type polysilicon, increases the speed of excess carrier extraction, and removes the electron-hole pairs generated by heavy ion bombardment;

[0036] S4. The P-type injection window on the back side of the silicon carbide Schottky diode body forms a wide depletion region during reverse blocking.

[0037] Therefore, the present invention adopts the above-mentioned high-voltage silicon carbide diode anti-radiation reinforcement structure and method to further improve the excess carrier extraction speed; the floating P island on the back side provides protection for the N- / N+ junction by forming a wider depletion region during reverse blocking, thereby suppressing the avalanche breakdown of the N- / N+ junction during heavy ion bombardment. The combined effect of the device surface and back structure can effectively improve the silicon carbide diode's ability to resist single-particle radiation.

[0038] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A high voltage silicon carbide diode radiation hardening structure, characterized in that: The invention comprises a silicon carbide Schottky diode body, an electrode part, a Schottky contact part, a P-type injection window, a floating P island, a deep trench part, an N-type epitaxial layer, and an N-type silicon carbide substrate. The electrode part comprises an anode electrode and a cathode electrode. A Schottky contact part is provided below the anode electrode. A deep trench part is provided in the middle below the Schottky contact part. P-type injection windows are provided on both sides of the deep trench part. An N-type silicon carbide substrate is provided above the cathode electrode. An N-type epitaxial layer is provided between the N-type silicon carbide substrate and the Schottky contact part. A floating P island is provided on the N-type epitaxial layer.

2. A method for strengthening the radiation resistance of a high voltage silicon carbide diode according to claim 1, characterized in that: The deep trench includes a P-type doped region and a P-type injected region, wherein the P-type doped region is located outside the P-type injected region, and P-type impurities are arranged inside the P-type doped region. The P-type doped region is located on the sidewall and bottom of the deep trench, and the P-type injected region in the deep trench includes N-type polysilicon and P-type polysilicon, and the filling of the N-type polysilicon is surrounded by the filling of the P-type polysilicon.

3. The method for strengthening the high voltage silicon carbide diode against radiation according to claim 1, characterized in that: The P-type doped region, the P-type injection region, and the N-type polysilicon and P-type polysilicon in the P-type injection region are arranged between the P-type injection windows, and 2-30 P-type injection windows are arranged between the P-type doped region, the P-type injection region, and the N-type polysilicon and P-type polysilicon in the P-type injection region.

4. The specific ratio of the deep trench and the P-type implantation window is adjusted according to the depth of the deep trench.

5. The high voltage silicon carbide diode radiation hardening structure according to claim 1, characterized in that: The anode electrode is located on the top of the silicon carbide Schottky diode body, and the cathode electrode is located on the bottom of the silicon carbide Schottky diode body.

6. The high voltage silicon carbide diode radiation hardening structure according to claim 1, characterized in that: The P-type implantation window is located below the Schottky contact portion, and the floating P island is located above the N-type silicon carbide substrate.

7. A method for a high voltage silicon carbide diode radiation hardening structure as claimed in claims 1 to 6, comprising the following steps: S1. Introducing a deep trench portion on the surface of the silicon carbide Schottky diode body, injecting P-type impurities into the sidewalls and bottom of the deep trench portion to form a P-type doped region, filling the deep trench portion with high concentrations of P-type polysilicon and N-type polysilicon to form a P-type implanted region, wherein the N-type polysilicon in the P-type implanted region is surrounded by P-type polysilicon, and the ratio of the deep trench portion to the P-type implanted window is adjusted according to the depth of the deep trench portion; S2. A floating P island is introduced on the back of the main body of the silicon carbide Schottky diode, which is directly opposite to the Schottky contact part. The deep trench part introduces a strong electric field into the deep trench, and at the same time uses the P-type doped area and P-type polysilicon to enhance the efficiency of hole extraction in the body at the moment of heavy ion bombardment. S3, short-circuiting the N-type polysilicon and the anode electrode accelerates the recombination of the extracted holes with the electrons in the N-type polysilicon, increases the speed of excess carrier extraction, and removes the electron-hole pairs generated by heavy ion bombardment; S4. The P-type injection window on the back side of the silicon carbide Schottky diode body forms a wide depletion region during reverse blocking.

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