A high voltage silicon carbide diode radiation-resistant reinforcement structure and preparation method thereof

Abstract

The present invention relates to the technical field of Schottky diodes, and discloses a high-voltage silicon carbide diode radiation-resistant reinforcement structure, including a cathode contact metal, an anode contact metal and a semiconductor epitaxial layer; the semiconductor epitaxial layer is provided with a deep trench structure between two highly doped P-well regions, and the deep trench structure includes a P-type doped region located in an outer layer and a filling medium located in an inner layer, wherein the filling medium is in contact with the highly doped P-well region and the anode contact metal. The present invention introduces a deep trench structure into a silicon carbide Schottky diode, injects P-type impurities into the sidewalls and bottom of the deep trench to form a P-type doped region, and fills the groove with dielectric materials such as SiO2, and quickly and efficiently removes electron-hole pairs generated by heavy ion bombardment, reduces the current and radiation response time generated by single particle radiation, and can effectively improve the single particle radiation resistance of the silicon carbide diode.

Description

Technical Field

[0001] The invention relates to the technical field of Schottky diodes, and in particular to a high-voltage silicon carbide diode radiation-resistant reinforcement structure and a preparation method thereof. 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] The existing patent discloses a Schottky diode (CN207458951U), comprising: a semiconductor substrate; an N-type epitaxial layer, located on the semiconductor substrate, and a plurality of grooves are etched on the N-type epitaxial layer; a high-concentration doped layer, which is a high-concentration semiconductor doped block, combined on the surface of the groove, so that the surface of the high-concentration doped layer is adjacent to the N-type epitaxial layer; a dielectric layer, combined on the surface of the high-concentration doped layer; a conductor layer, located on the N-type epitaxial layer and combined with the high-concentration doped layer and the end of the dielectric layer. In the technology disclosed in this patent, when heavy ions bombard the Schottky diode structure and enter the power device, a large number of electron-hole pairs will be generated along the movement trajectory. These electron-hole pairs drift under the action of the electric field formed by the reverse blocking voltage, forming a huge instantaneous current inside the device. In particular, the local temperature of the surface Schottky contact area rises rapidly due to the instantaneous current and the strong electric field, causing the Schottky barrier to decrease or even disappear, and the device to produce a large leakage current and degrade or even fail due to overheating. On the other hand, if the energy of the heavy ion bombardment is very high, in addition to the aforementioned carrier movement causing device degradation or failure, the large number of carriers generated will also cause a resistive short circuit between the anode and cathode of the device, and the extremely high voltage applied to the N- / N+ junction will also cause this junction to break down and burn out prematurely. Summary of the invention

[0004] The main technical problem solved by the present invention is to provide a high-voltage silicon carbide diode radiation-resistant reinforcement structure and a preparation method thereof, which solves the problems in the above-mentioned background technology.

[0005] To solve the above technical problems, according to one aspect of the present invention, more specifically, a high voltage silicon carbide diode radiation hardening structure includes a cathode contact metal, an anode contact metal and a semiconductor epitaxial layer;

[0006] The semiconductor epitaxial layer comprises a substrate layer and a diffusion layer, wherein the surface of the diffusion layer is formed with a plurality of highly doped P-well regions with complementary contacts by ion implantation of boron ions, the substrate layer is in ohmic contact with the cathode contact metal, the highly doped P-well region is in ohmic contact with the anode contact metal, and the diffusion layer and the anode contact metal form a Schottky contact;

[0007] The semiconductor epitaxial layer is provided with a deep trench structure between two highly doped P-well regions, wherein the deep trench structure includes a P-type doped region located in an outer layer and a filling medium located in an inner layer, wherein the filling medium is in contact with the highly doped P-well region and the anode contact metal.

[0008] Furthermore, the filling medium also includes a P-type polysilicon layer.

[0009] Furthermore, the filling medium also includes an N-type polysilicon layer.

[0010] Furthermore, the filling medium also includes a mixed material consisting of an N-type polysilicon inner layer and a P-type polysilicon outer layer.

[0011] Furthermore, the P-type polysilicon outer layer is located between the N-type polysilicon inner layer and the P-type doped region, and the N-type polysilicon inner layer forms a Schottky contact with the anode contact metal.

[0012] A method for preparing a high-voltage silicon carbide diode radiation-resistant reinforcement structure comprises the following steps:

[0013] S1, selecting a semiconductor epitaxial layer including a substrate layer, a diffusion layer and a highly doped P-well region after preparation;

[0014] S2, forming a deep trench between the two highly doped P-well regions by etching;

[0015] S3, depositing a P-type doped region on the inner wall of the deep trench, and depositing a filling medium on the inner wall of the P-type doped region;

[0016] S4, inspecting the doping concentration of the filling medium and the P-type doping area, and curing the deep trench structure after the inspection meets the standards;

[0017] S5. Embed a cathode contact metal and an anode contact metal on the surface of the semiconductor epitaxial layer.

[0018] Furthermore, in the step S, by sampling the doping concentration of the highly doped P-well region in the semiconductor epitaxial layer, the concentration of the P-type doping region, and the resistance ratio between the cathode contact metal and the anode contact metal after the contact metal is connected without depositing the filling medium and the resistance ratio of the semiconductor without the deep trench structure, we have:

[0019]

[0020] In the formula, It represents the qualified coefficient of doping of deep trench structure in semiconductor epitaxial layer, It represents the doping concentration of the highly doped P-well region in the semiconductor epitaxial layer. It represents the concentration of P-type doping region in the semiconductor epitaxial layer. It represents the resistance ratio of a silicon carbide Schottky diode with a deep trench structure to a silicon carbide Schottky diode without a deep trench structure;

[0021] when When , it indicates that the doping concentration of the filling medium and the P-type doping area has been tested and met the standard;

[0022] when When , it means that the doping concentration of the filling medium and the P-type doping area is not up to standard.

[0023] Furthermore, the resistance ratio between the cathode contact metal and the anode contact metal after the contact metal is connected without depositing the filling dielectric and the resistance ratio of the semiconductor without the deep trench structure is:

[0024]

[0025] In the formula, It represents the resistance ratio of a silicon carbide Schottky diode with a deep trench structure to a silicon carbide Schottky diode without a deep trench structure. It indicates the resistance between the cathode contact metal and the anode contact metal after the contact metal is connected without depositing the filling medium. Represents the resistance between the cathode contact metal and the anode contact metal without a deep trench structure.

[0026] Beneficial effects:

[0027] 1. The present invention introduces a deep trench structure inside a silicon carbide Schottky diode, injects P-type impurities into the sidewalls and bottom of the deep trench to form a P-type doped region, and fills the trench with dielectric materials such as SiO2. By quickly and efficiently removing electron-hole pairs generated by heavy ion bombardment, the current and radiation response time generated by single-particle radiation are reduced, thereby effectively improving the single-particle radiation resistance of the silicon carbide diode.

[0028] 2. The present invention introduces a deep trench structure inside the silicon carbide Schottky diode, injects P-type impurities into the sidewalls and bottom of the deep trench to form a P-type doped region, and fills the trench with P-type polysilicon. The deep trench structure introduces a strong electric field into the body, and at the same time utilizes a larger P-type doped region area and P-type polysilicon with an anode short circuit to greatly increase the hole extraction path, thereby enhancing the hole extraction efficiency in the body at the moment of heavy ion bombardment, reducing the current generated by single-particle radiation and the radiation response time, and can effectively improve the single-particle radiation resistance of the silicon carbide diode.

[0029] 3. The present invention introduces a deep trench structure inside the silicon carbide Schottky diode, injects P-type impurities into the sidewalls and bottom of the deep trench to form a P-type doped region, and fills the trench with N-type polysilicon. In addition, the N-type polysilicon short-circuited to 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 and effectively improving the single-particle radiation resistance of the silicon carbide diode.

[0030] 4. The present invention introduces a deep trench structure into the silicon carbide Schottky diode, injects P-type impurities into the sidewalls and bottom of the deep trench to form a P-type doped region, fills the trench with high-concentration P-type and N-type polysilicon, and the N-type polysilicon is surrounded by P-type polysilicon. 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 efficiency of hole extraction in the body at the moment of heavy ion bombardment.

[0031] 5. In the process of preparing the radiation-resistant reinforcement structure of the high-voltage silicon carbide diode, the present invention analyzes and verifies whether the radiation-resistant structure in the semiconductor epitaxial layer meets the standards by measuring the doping concentration of the filling medium and the P-type doping area, and the resistance ratio of the silicon carbide Schottky diode with a deep trench structure and the silicon carbide Schottky diode without a deep trench structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of Embodiment 1 of the present invention;

[0033] Figure 2 It is a schematic diagram of the second embodiment of the present invention;

[0034] Figure 3 It is a schematic diagram of Embodiment 3 of the present invention;

[0035] Figure 4 It is a schematic diagram of Embodiment 4 of the present invention.

[0036] In the figure: 1. cathode contact metal; 2. anode contact metal; 3. substrate layer; 4. diffusion layer; 5. highly doped P-well region; 6. P-type doped region; 7. filling medium; 701. P-type polysilicon layer; 702. N-type polysilicon layer; 703. N-type polysilicon inner layer; 704. P-type polysilicon outer layer. DETAILED DESCRIPTION

[0037] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] A method for preparing a high-voltage silicon carbide diode radiation-resistant reinforcement structure comprises the following steps:

[0039] Step 1: Select a semiconductor epitaxial layer including a substrate layer 3, a diffusion layer 4 and a highly doped P-well region 5 after preparation;

[0040] Step 2: forming a deep trench between the two highly doped P-well regions 5 by etching;

[0041] Step 3: a P-type doped region 6 is deposited on the inner wall of the deep trench, and a filling medium 7 is deposited on the inner wall of the P-type doped region 6;

[0042] Step 4: inspect the doping concentration of the filling medium 7 and the P-type doping region 6, and perform a curing process on the deep trench structure after the inspection meets the standards;

[0043] Step 5: embedding cathode contact metal 1 and anode contact metal 2 on the surface of the semiconductor epitaxial layer.

[0044] In step 4, by sampling the doping concentration of the highly doped P-well region 5 in the semiconductor epitaxial layer, the concentration of the P-type doping region 6, and the resistance ratio between the cathode contact metal 1 and the anode contact metal 2 after the contact metal is connected without depositing the filling medium 7 and the resistance ratio of the semiconductor without the deep trench structure, we have:

[0045]

[0046] In the formula, It represents the qualified coefficient of doping of deep trench structure in semiconductor epitaxial layer, represents the doping concentration of the highly doped P-well region 5 in the semiconductor epitaxial layer, represents the concentration of the P-type doping region 6 in the semiconductor epitaxial layer, It represents the resistance ratio of a silicon carbide Schottky diode with a deep trench structure to a silicon carbide Schottky diode without a deep trench structure;

[0047] when When , it indicates that the doping concentration of the filling medium 7 and the P-type doping region 6 is tested to be up to standard;

[0048] when , it indicates that the doping concentrations of the filling medium 7 and the P-type doping region 6 are not up to standard.

[0049] The resistance ratio between the cathode contact metal 1 and the anode contact metal 2 after the contact metal is connected without depositing the filling dielectric 7 and the resistance ratio of the semiconductor without the deep trench structure is:

[0050]

[0051] In the formula, It represents the resistance ratio of a silicon carbide Schottky diode with a deep trench structure to a silicon carbide Schottky diode without a deep trench structure. It represents the resistance between the cathode contact metal 1 and the anode contact metal 2 after the contact metal is connected without depositing the filling medium 7. It represents the resistance between cathode contact metal 1 and anode contact metal 2 without deep trench structure.

[0052] The sampled epitaxial layer material X is filled with dielectric 7 and the doping concentration of the P-type doping region 6 is tested. The forward resistance between the cathode contact metal 1 and the anode contact metal 2 is measured after the contact metal is connected without depositing the filling dielectric 7. (mOhm), the forward resistance between the cathode contact metal 1 and the anode contact metal 2 without deep trench structure is (milliohms), then:

[0053]

[0054] From the above calculation, it can be known that the resistance ratio of the silicon carbide Schottky diode with a deep trench structure to the silicon carbide Schottky diode without a deep trench structure is .

[0055] The doping concentration of the highly doped P-well region 5 in the sampled epitaxial layer material X semiconductor epitaxial layer is ( atoms / cm3), the concentration of the P-type doping region 6 in the semiconductor epitaxial layer is ( atoms / cubic centimeter). Then the qualified coefficient of doping in the deep trench structure in the semiconductor epitaxial layer is:

[0056]

[0057] From the above calculation, it can be known that the doping concentration test of the filling medium 7 and the P-type doping region 6 of the sampled epitaxial layer material X meets the standard.

[0058] Example 1

[0059] like Figure 1As shown, a high-voltage silicon carbide diode radiation-resistant reinforcement structure includes a cathode contact metal 1, an anode contact metal 2, and a semiconductor epitaxial layer; the semiconductor epitaxial layer includes a substrate layer 3 and a diffusion layer 4, wherein the surface of the diffusion layer 4 is formed with a plurality of highly doped P-well regions 5 with complementary contacts by ion implantation of boron ions, the substrate layer 3 and the cathode contact metal 1 form an ohmic contact, and the diffusion layer 4 and the anode contact metal 2 form a Schottky contact. Schottky contact refers to the bending of the semiconductor energy band at the interface when the metal and the semiconductor material are in contact, forming a Schottky barrier. The existence of the barrier leads to a large interface resistance. Corresponding to this is an ohmic contact, where the barrier at the interface is very small or there is no contact barrier.

[0060] A deep trench structure is provided in the semiconductor epitaxial layer and between two highly doped P-well regions 5. The deep trench structure includes a P-type doped region 6 located in the outer layer and a filling medium 7 located in the inner layer, wherein the filling medium 7 is in contact with the highly doped P-well region 5 and the anode contact metal 2. P-type impurities are injected into the sidewalls and bottom of the deep trench to form the P-type doped region 6, and dielectric materials such as SiO2 (filling medium 7) are filled in the trench. The deep trench structure introduces a strong electric field into the body, while enhancing the hole extraction efficiency in the device body at the moment of heavy ion bombardment, and reduces the current and radiation response time generated by single particle radiation by quickly and efficiently removing the electron-hole pairs generated by heavy ion bombardment.

[0061] Example 2

[0062] like Figure 2 As shown, the filling medium 7 also includes a P-type polysilicon layer 701. P-type impurities are injected into the sidewalls and bottom of the deep trench to form a P-type doped region 6, and the P-type polysilicon layer 701 is filled in the groove. The deep trench structure introduces a strong electric field into the body, and at the same time utilizes a larger area of ​​the P-type doped region 6 and the anode short-circuited P-type polysilicon layer 701 to greatly increase the hole extraction path to enhance the hole extraction efficiency in the body at the moment of heavy ion bombardment, and quickly and efficiently removes the electron-hole pairs generated by heavy ion bombardment, thereby reducing the current and radiation response time generated by single particle radiation.

[0063] Example 3

[0064] like Figure 3 As shown, the filling medium 7 also includes an N-type polysilicon layer 702. P-type impurities are injected into the sidewalls and bottom of the deep trench to form a P-type doped region 6, and the groove is filled with N-type polysilicon (N-type polysilicon layer 702). The deep trench structure introduces a strong electric field into the body and uses a larger area of ​​the P-type doped region 6 to greatly enhance the hole extraction efficiency in the body at the moment of heavy ion bombardment. In addition, the N-type polysilicon (N-type polysilicon layer 702) short-circuited with the anode will accelerate the recombination of the extracted holes with the electrons in the N-type polysilicon (N-type polysilicon layer 702).

[0065] Example 4

[0066] like Figure 4 As shown, the filling medium 7 also includes a mixed material composed of an N-type polysilicon inner layer 703 and a P-type polysilicon outer layer 704; the P-type polysilicon outer layer 704 is located between the N-type polysilicon inner layer 703 and the P-type doped region 6, and the N-type polysilicon inner layer 703 forms a Schottky contact with the anode contact metal 2. P-type impurities are injected into the sidewalls and bottom of the deep trench to form a P-type doped region 6, and the trench is filled with high-concentration P-type (P-type polysilicon outer layer 704) and N-type polysilicon (N-type polysilicon inner layer 703), and the N-type polysilicon is surrounded by P-type polysilicon. The deep trench structure introduces a strong electric field into the body, and at the same time uses a larger area of ​​the P-type doped region 6 and P-type polysilicon (P-type polysilicon outer layer 704) to greatly enhance the hole extraction efficiency in the body at the moment of heavy ion bombardment.

[0067] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A high voltage silicon carbide diode radiation hardening structure, characterized in that: It comprises a cathode contact metal (1), an anode contact metal (2) and a semiconductor epitaxial layer; The semiconductor epitaxial layer comprises a substrate layer (3) and a diffusion layer (4), wherein the surface of the diffusion layer (4) is formed with a plurality of highly doped P-well regions (5) with complementary contacts by ion implantation of boron ions, the substrate layer (3) is in ohmic contact with the cathode contact metal (1), the highly doped P-well region (5) is in ohmic contact with the anode contact metal (2), and the diffusion layer (4) and the anode contact metal (2) form a Schottky contact; The semiconductor epitaxial layer is provided with a deep trench structure between two highly doped P-well regions (5), the deep trench structure comprising a P-type doped region (6) located at an outer layer and a filling medium (7) located at an inner layer, wherein the filling medium (7) is in contact with adjacent highly doped P-well regions (5) and an anode contact metal (2); The filling medium (7) is a P-type polysilicon layer (701) or an N-type polysilicon layer (702) or a mixed material, and the mixed material is composed of an N-type polysilicon inner layer (703) and a P-type polysilicon outer layer (704).

2. The high voltage silicon carbide diode radiation hardening structure according to claim 1, characterized in that: The P-type polysilicon outer layer (704) is located between the N-type polysilicon inner layer (703) and the P-type doped region (6), and the N-type polysilicon inner layer (703) forms a Schottky contact with the anode contact metal (2).

3. A method for preparing a high voltage silicon carbide diode radiation hardening structure according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1, selecting a semiconductor epitaxial layer comprising a substrate layer (3), a diffusion layer (4) and a highly doped P-well region (5) after preparation; S2, forming a deep trench between the two highly doped P-well regions (5) by etching; S3, depositing a P-type doped region (6) on the inner wall of the deep trench, and depositing a filling medium (7) on the inner wall of the P-type doped region (6); S4, inspecting the doping concentration of the filling medium (7) and the P-type doping region (6), and performing a curing process on the deep trench structure after the inspection meets the standards; S5. Embedding cathode contact metal (1) and anode contact metal (2) on the surface of the semiconductor epitaxial layer.

4. The method for preparing the high voltage silicon carbide diode radiation hardening structure according to claim 3, characterized in that: In step S4, by sampling the doping concentration of the highly doped P-well region (5) in the semiconductor epitaxial layer, the concentration of the P-type doping region (6), and the resistance ratio between the cathode contact metal (1) and the anode contact metal (2) after the contact metal is connected without depositing the filling medium (7) and the resistance ratio of the semiconductor without the deep trench structure, we have: In the formula, It represents the qualified coefficient of doping of deep trench structure in semiconductor epitaxial layer, represents the doping concentration of the highly doped P-well region (5) in the semiconductor epitaxial layer, represents the concentration of the P-type doped region (6) in the semiconductor epitaxial layer, It represents the resistance ratio of a silicon carbide Schottky diode with a deep trench structure to a silicon carbide Schottky diode without a deep trench structure; when When , it indicates that the doping concentration of the filling medium (7) and the P-type doping region (6) has been tested and has met the standard; when , it indicates that the doping concentration of the filling medium (7) and the P-type doping region (6) is not up to standard.

5. The method for preparing the high voltage silicon carbide diode radiation hardening structure according to claim 4, characterized in that: The ratio of the resistance between the cathode contact metal (1) and the anode contact metal (2) after the contact metal is connected without depositing the filling medium (7) to the resistance of the semiconductor without the deep trench structure is: In the formula, It represents the resistance ratio of a silicon carbide Schottky diode with a deep trench structure to a silicon carbide Schottky diode without a deep trench structure. It represents the resistance between the cathode contact metal (1) and the anode contact metal (2) after the contact metal is connected without depositing the filling medium (7), It represents the resistance between the cathode contact metal (1) and the anode contact metal (2) without the deep trench structure.

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