High voltage silicon carbide diode radiation hardening structure and method

Abstract

The application discloses a high-voltage silicon carbide diode anti-radiation reinforcing structure and method, which 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 groove part, an N-type epitaxial layer and an N-type silicon carbide substrate. The electrode part comprises an anode electrode and a cathode electrode. The Schottky contact part is arranged below the anode electrode. The deep groove part is arranged in the middle below the Schottky contact part. The P-type injection window is arranged on both sides of the deep groove part. The N-type silicon carbide substrate is arranged above the cathode electrode. The N-type epitaxial layer is arranged between the N-type silicon carbide substrate and the Schottky contact part. The floating P island is arranged on the N-type epitaxial layer. The high-voltage silicon carbide diode anti-radiation reinforcing structure and method can effectively improve the single-particle radiation resistance of the silicon carbide diode through the cooperation of the front and back structures 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 (SiC) high-voltage power devices offer superior electrothermal performance compared to traditional silicon devices, enabling them to operate in harsher environments. Consequently, they hold broad application prospects in photovoltaic power generation, electric vehicles, and aerospace. In the aerospace sector, power devices must not only meet the requirements of high voltage, high power, high frequency, and low loss, but also possess excellent radiation resistance.

[0003] For high-voltage SiC power devices, radiation hardening is a major challenge. 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 a very complex electrothermal coupling response within 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 and causing 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] To address the shortcomings of existing technologies, the present invention proposes a radiation-hardened structure for a high-voltage silicon carbide diode. This structure incorporates a deep trench on the device surface, implanting P-type impurities along the sidewalls and bottom of the trench to form a P-type doped region. The trench is then filled with high-concentration P-type and N-type polysilicon, with the N-type polysilicon surrounded by P-type polysilicon. A floating P-island is introduced on the backside of the device, directly opposite the Schottky contact. The deep trench structure introduces a strong electric field into the diode, while utilizing the larger P-doped region and P-type polysilicon to significantly enhance hole extraction efficiency during heavy ion bombardment. Furthermore, the N-type polysilicon shorted to the anode accelerates the recombination of extracted holes with electrons in the N-type polysilicon, further increasing excess carrier extraction. The floating P-island on the backside protects the N- / N+ junction during reverse blocking by forming a wide depletion region, suppressing avalanche breakdown during heavy ion bombardment. The combined effects of the surface and backside structures effectively enhance the single-event 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 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.

[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 portion, a Schottky contact portion, a P-type injection window, a floating P island, a deep trench portion, an N-type epitaxial layer, and an N-type silicon carbide substrate. The electrode portion comprises an anode electrode and a cathode electrode. A Schottky contact portion is provided below the anode electrode, a deep trench portion is provided in the middle below the Schottky contact portion, P-type injection windows are provided on both sides of the deep trench portion, 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 portion, 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 injection region, the P-type doped region is located outside the P-type injection 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 injection 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 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 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 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.

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

[0012] S1. A deep trench is introduced on the surface of the silicon carbide Schottky diode body, and P-type impurities are implanted into the sidewalls and bottom of the deep trench to form a P-type doped region. The deep trench is filled with high-concentration P-type polysilicon and N-type polysilicon to form a P-type implanted region. The N-type polysilicon in the P-type implanted region is surrounded by P-type polysilicon. The ratio of the deep trench to the P-type implanted window is adjusted according to the depth of the deep trench.

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

[0014] S3, N-type polysilicon and the anode electrode are short-circuited to accelerate the recombination of extracted holes with electrons in the N-type polysilicon, increase the extraction speed of excess carriers, and remove 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 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] Fig. 1 This is an overall structural diagram of a high-voltage silicon carbide diode radiation hardening structure and method of the present invention;

[0019] Fig. 2 A schematic diagram of a deep trench structure of a high-voltage silicon carbide diode radiation hardening structure and method according to the present invention;

[0020] Fig. 3 The figure is a flow chart of a high-voltage silicon carbide diode radiation hardening structure and method according to the present invention.

[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 doped region; 11. P-type injection region. DETAILED DESCRIPTION

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

[0024] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art 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 "comprise" mean that the elements or objects preceding 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" 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 position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0026] Example 1

[0027] like Figs. 1-3 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, and 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 injection region 11. The P-type doped region 10 is located outside the P-type injection region 11. P-type impurities are provided 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 injection region 11 in the deep trench portion 5 includes N-type polysilicon and P-type polysilicon. The N-type polysilicon filling is surrounded by the P-type polysilicon filling.

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

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

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

[0032] The P-type implanted 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 a silicon carbide Schottky diode body, implanting P-type impurities on the sidewall and bottom of the deep trench portion to form a P-type doped region, filling the deep trench portion with high-concentration P-type polysilicon and N-type polysilicon to form a P-type implanted region, the N-type polysilicon in the P-type implanted region being surrounded by the P-type polysilicon, and the proportion of the deep trench portion and the P-type implanted window being adjusted according to the depth of the deep trench portion;

[0034] S2, introducing a floating P island opposite to the Schottky contact portion on the back of the silicon carbide Schottky diode body, the deep trench portion introducing a strong electric field into the deep trench, and the P-type doped region area and the P-type polysilicon being used to strengthen the hole extraction efficiency in the body in the moment of heavy ion bombardment;

[0035] S3, the N-type polysilicon and the anode electrode short circuit accelerating the recombination of the extracted holes and the electrons in the N-type polysilicon, improving the excess carrier extraction speed, and removing the electron-hole pairs generated by heavy ion bombardment;

[0036] S4, the back P-type implanted window of the silicon carbide Schottky diode body forming a wide depletion region when reverse blocking.

[0037] Therefore, the high-voltage silicon carbide diode anti-radiation reinforcement structure and method further improve the excess carrier extraction speed; the floating P island on the back forms a wider depletion region when reverse blocking, protects the N- / N+ junction, inhibits the avalanche breakdown of the N- / N+ junction in the process of heavy ion bombardment, and the joint action of the front and back structures can effectively improve the single-particle radiation resistance of the silicon carbide diode.

[0038] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions 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 portion, a Schottky contact portion, a P-type injection window, a floating P island, a deep trench portion, an N-type epitaxial layer, and an N-type silicon carbide substrate. The electrode portion comprises an anode electrode and a cathode electrode. A Schottky contact portion is provided below the anode electrode. A deep trench portion is provided in the middle below the Schottky contact portion. P-type injection windows are provided on both sides of the deep trench portion. 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 portion. A floating P island is provided on the N-type epitaxial layer. The deep trench includes a P-type doped region and a P-type implanted region, the P-type doped region is located outside the P-type implanted region, P-type impurities are provided inside the P-type doped region, the P-type doped region is located on the sidewalls and bottom of the deep trench, the P-type implanted 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; 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 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 N-type polysilicon and P-type polysilicon in the P-type injection region in the deep trench.

2. 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.

3. 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.

4. A method for providing a radiation hardened structure for a high-voltage silicon carbide diode according to any one of claims 1 to 3, comprising the following steps: S1. A deep trench is introduced on the surface of the silicon carbide Schottky diode body. P-type impurities are implanted into the sidewalls and bottom of the deep trench to form a P-type doped region. High-concentration P-type polysilicon and N-type polysilicon are filled into the deep trench to form a P-type implanted region. The N-type polysilicon in the P-type implanted region is surrounded by P-type polysilicon. S2. A floating P island is introduced on the back of the silicon carbide Schottky diode body, facing the Schottky contact part. The deep trench part introduces a strong electric field into the deep trench, while utilizing the P-type doped region area and P-type polysilicon to enhance the hole extraction efficiency in the body at the moment of heavy ion bombardment. S3, N-type polysilicon and the anode electrode are short-circuited to accelerate the recombination of extracted holes with electrons in the N-type polysilicon, increase the extraction speed of excess carriers, and remove 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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