Diode avalanche shaping device with composite terminal structure and secondary avalanche resistance

Abstract

The invention discloses a diode avalanche shaping device with a composite terminal structure and secondary avalanche resistance. The diode avalanche shaping device comprises a negative electrode, a SiC substrate, a P-type control region, a SiC epitaxial layer, a corrugated P + region, a JTE region, a passivation layer and a positive electrode, a first protrusion of the corrugated P + region is embedded in the SiC epitaxial layer, and the orthographic projection of the first protrusion on the SiC substrate coincides with the orthographic projection of a control block of the P-type control region on the SiC substrate. And the widths of the spacer regions formed in the JTE region are sequentially increased along the direction far away from the corrugated P + region. According to the diode avalanche shaping device provided by the invention, the corrugated P + region, the JTE region with the interval regions of different widths and the control block arranged on the SiC substrate are arranged, so that the reliability of the device during the first avalanche can be improved, and the second avalanche of the device can be avoided at the same time.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, specifically relating to a diode avalanche shaping device with a composite termination structure and resistance to secondary avalanche. Background Technology

[0002] A diode avalanche shaper (DAS) is a semiconductor power device that operates based on the delayed avalanche effect. Its working principle is as follows: when a rapidly rising reverse pulse voltage is applied, the device's dynamic breakdown voltage can exceed its static value; when the voltage reaches its peak value, the region within the device exceeding the critical electric field undergoes violent collisional ionization, instantaneously generating a large number of electron-hole pairs (i.e., plasma). Once the plasma fills the entire device, the device quickly switches to the conducting state.

[0003] Traditional pulsed power switching devices (such as thyristors, IGBTs, and MOSFETs) struggle to balance high voltage withstand capability with fast turn-on. Delayed avalanche (DAS) cleverly utilizes the rapid plasma accumulation characteristic during delayed avalanche, effectively resolving this contradiction and thus demonstrating significant application potential in pulsed power systems. SiC, with its high critical electric field, high electron saturation velocity, and high thermal conductivity, is an ideal material for fabricating DAS devices. Existing SiC DAS devices are divided into P... + PN + (p-DAS) and P + NN + The two structures, n-DAS and n-DAS, exhibit superior dynamic performance due to the fact that the electron diffusion coefficient and saturation drift velocity of SiC materials are both higher than those of holes.

[0004] Due to their unique delayed avalanche operating mechanism, SiC DAS devices can achieve dynamic breakdown voltages that are 1-2 times higher than their static values, placing more stringent demands on termination design. While traditional termination structures can effectively improve the static breakdown voltage, they cannot meet the specific requirements of DAS devices under dynamic operating conditions. Simultaneously, a large number of electrons generated by the avalanche rush towards the cathode at high speed; when these high-energy electrons reach the NN... + When the junction (i.e., the interface between the base region and the cathode) is formed, due to N + A sudden change in doping concentration in the region can create an extremely strong local electric field near the interface. This enhanced electric field may trigger a second avalanche breakdown point, located at the NN junction. + Near the junction. This process causes a sudden and dramatic increase in current and generates enormous heat, which can easily lead to permanent damage to the device due to localized overheating.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides an avalanche shaping device. The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches, comprising: negative electrode; A SiC substrate is located on one side of the negative electrode; The P-type control region includes multiple control blocks, which are embedded in the SiC substrate on the side away from the negative electrode. A SiC epitaxial layer is located on the side of the SiC substrate away from the negative electrode, and the SiC epitaxial layer covers the SiC substrate and the P-type control region; A corrugated P+ region is located in the middle of the side of the SiC epitaxial layer away from the SiC substrate, and the corrugated P+ region is correspondingly disposed with respect to the P-type control region; the corrugated P+ region includes a plurality of first protrusions facing the SiC epitaxial layer, and the first protrusions are embedded in the SiC epitaxial layer; the orthographic projection of the first protrusions on the SiC substrate coincides with the orthographic projection of the control block on the SiC substrate. The JTE region is located on both sides of the corrugated P+ region. The JTE region includes a plurality of second protrusions facing the SiC epitaxial layer. The second protrusions and the corrugated P+ region form a first spacing region. Along the direction away from the corrugated P+ region, adjacent second protrusions sequentially form a second spacing region, a third spacing region, ..., an Nth spacing region. The width of the first interval is W1, the width of the second interval is W2, ..., and the width of the Nth interval is W... N And satisfying W1 < W2 < ... < W N ; The positive electrode is located on the side of the corrugated P+ region away from the SiC substrate; A passivation layer is located on both sides of the positive electrode, and the passivation layer covers the JTE region.

[0007] In one embodiment of the present invention, the width W1 of the first interval region is in the range of 0.8 μm to 1 μm, and the width W of the Nth interval region is... N Within the range of 3.8μm to 4.2μm.

[0008] In one embodiment of the present invention, when 1≤n≤10, W is satisfied. n =W n-1 +0.1μm; when 11≤n≤N, W n =W n-1 +0.2μm; where W nW is the width of the nth interval. n-1 It represents the width of the (n-1)th interval.

[0009] In one embodiment of the present invention, the thickness of the first interval region, the second interval region, ..., the Nth interval region is L1; The thickness of the groove formed between any two adjacent first protrusions is L2, which satisfies L1 > L2.

[0010] In one embodiment of the present invention, L1 is 0.8 to 2.1 μm and L2 is 0.3 to 1.5 μm.

[0011] In one embodiment of the present invention, the ion doping concentration of the JTE region is less than the ion doping concentration of the corrugated P+ region; Along the side of the corrugated P+ region away from the SiC substrate, and towards the side of the corrugated P+ region closer to the SiC substrate, the ion doping concentration of the corrugated P+ region is a Gaussian doping distribution.

[0012] In one embodiment of the present invention, the ion doping concentration of the corrugated P+ region is 1×10⁻⁶. 19 cm -3 ~1×10 21 cm -3 The ion doping concentration of the JTE region is 5 × 10⁻⁶. 18 cm -3 ~5×10 20 cm -3 ; The doped ions are boron ions or aluminum ions.

[0013] In one embodiment of the present invention, the ion doping concentration of each control block in the P-type control region is 1×10⁻⁶. 17 cm -3 ~1×10 20 cm -3 ; The doped ions are boron ions or aluminum ions.

[0014] In one embodiment of the present invention, the SiC substrate is N-type ion doped, and the doping concentration of the SiC substrate is 1×10⁻⁶. 18 cm -3 ~1×10 20 cm -3 ; The SiC epitaxial layer is N-type ion doped, and the doping concentration of the SiC epitaxial layer is 1×10⁻⁶. 15 cm -3 ~1×10 17 cm -3 .

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The diode avalanche shaping device provided by the present invention provides a corrugated P+ region with a periodic first protrusion below the positive electrode. By using multiple controllable curvature points to disperse the peak value of the surface electric field, the trigger point of dynamic avalanche is guided from an unreliable single point on the surface to multiple preset positions within the corrugated P+ region, thereby achieving more uniform plasma triggering and improving the consistency and reliability of device conduction.

[0016] 2. The diode avalanche shaping device provided by the present invention also gradually increases the spacing of the second protrusions of the JTE region by setting a JTE region that is linked to the shape of the main junction region (corrugated P+ region), so that each second protrusion structure can bear the voltage in sequence and smoothly, and the depletion region can gradually and uniformly extend to both sides of the corrugated P+ region, thereby flattening the surface electric field distribution of the entire terminal and alleviating the electric field concentration at the surface of the PN junction.

[0017] 3. The diode avalanche shaping device provided by this invention has a P-type control region on the upper surface of the SiC substrate. The control block of the P-type control region can inject holes into the SiC epitaxial layer (N-base region) and recombine with the incoming electrons, which can directly weaken the N-base formation formed between the SiC substrate and the SiC epitaxial layer. + The electric field near the junction fundamentally suppresses secondary avalanches.

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a diode avalanche shaping device with a composite terminal structure and resistance to secondary avalanches, provided in an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1-SiC substrate; 2-P-type control region; 21-Control block; 3-SiC epitaxial layer; 4-Wave-shaped P+ region; 41-First protrusion; 5-JTE region; 51-Second protrusion; 6-Passivation layer; 7-Positive electrode; 8-Negative electrode. Detailed Implementation

[0021] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following describes in detail, with reference to the accompanying drawings and specific embodiments, a diode avalanche shaping device with a composite terminal structure and resistant to secondary avalanche, according to the present invention.

[0022] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0023] It should be noted that, in this document, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more unless otherwise expressly specified, and the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed.

[0024] In the description of this invention, it should be understood that the terms "width," "thickness," "upper," "lower," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In this invention, "width" refers to the dimension of the JTE region in the direction away from the corrugated P+ region; "thickness" refers to the dimension in the direction perpendicular to the upper surface of the SiC substrate, where the upper surface of the SiC substrate is the surface of the SiC substrate away from the negative electrode.

[0025] This invention provides a diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches. See [link to relevant documentation]. Figure 1 The system includes a negative electrode 8, a SiC substrate 1, a P-type control region 2, a SiC epitaxial layer, a corrugated P+ region 4, a JTE region 5, a passivation layer 6, and a positive electrode 7. The SiC substrate 1 is located on one side of the negative electrode 8. The P-type control region 2 includes multiple control blocks 21, which are embedded in the SiC substrate 1 on the side away from the negative electrode 8. The SiC epitaxial layer 3 is located on the side of the SiC substrate 1 away from the negative electrode 8, and covers the SiC substrate 1 and the P-type control region 2.

[0026] The corrugated P+ region 4 is located in the middle of the side of the SiC epitaxial layer 3 away from the SiC substrate 1, and the corrugated P+ region 4 is correspondingly disposed with respect to the P-type control region 2. That is, the orthographic projection of the corrugated P+ region 4 on the SiC substrate 1 coincides with the orthographic projection of the P-type control region 2 on the SiC substrate 1. The corrugated P+ region 4 includes a plurality of first protrusions 41 facing the SiC epitaxial layer 3, and the first protrusions 41 are embedded in the SiC epitaxial layer 3; the orthographic projection of the first protrusions 41 on the SiC substrate 1 coincides with the orthographic projection of the control block 21 on the SiC substrate 1.

[0027] JTE regions 5 are located on both sides of the corrugated P+ region 4. JTE regions 5 include multiple second protrusions 51 facing the SiC epitaxial layer 3. Along the direction away from the corrugated P+ region 4, the second protrusions 51 and the corrugated P+ region 4 form a first spacing region. Adjacent second protrusions 51 sequentially form a second spacing region, a third spacing region, ..., an Nth spacing region. The width of the first spacing region is W1, the width of the second spacing region is W2, ..., and the width of the Nth spacing region is W... N And satisfying W1 < W2 < ... < W N .

[0028] The positive electrode 7 is located on the side of the corrugated P+ region 4 away from the SiC substrate 1. The passivation layer 6 is located on both sides of the positive electrode 7, and the passivation layer 6 covers the JTE region 5.

[0029] The diode avalanche shaping device with a composite terminal structure and resistance to secondary avalanches provided in this embodiment of the invention, on the one hand, replaces the regularly shaped P+ region located below the positive electrode 7 with a corrugated P+ region 4 with periodic protrusions. Multiple controllable curvature points disperse the peak surface electric field, guiding the trigger point of dynamic avalanches from an unreliable single surface point to multiple preset positions within the corrugated P+ region 4, thereby achieving more uniform plasma triggering and improving the consistency and reliability of device conduction. Simultaneously, at the interface between the SiC substrate 1 and the SiC epitaxial layer 3, a P-type control region 2 embedded in the SiC substrate 1 is provided. The control block 21 of the P-type control region 2 can inject holes into the N-base region, recombine with the incoming electrons, and directly weaken the N-base region formed by the SiC substrate 1 and the SiC epitaxial layer 3. + The electric field near the junction fundamentally suppresses secondary avalanche. On the other hand, by setting a JTE region 5 that is linked to the shape of the main junction region (corrugated P+ region 4), the spacing of the second protrusions 51 of the JTE region 5 is gradually increased, allowing each first protrusion 41 structure to bear the voltage sequentially and smoothly, so that the depletion region gradually and uniformly extends to both sides of the corrugated P+ region 4, thereby flattening the surface electric field distribution of the entire terminal and alleviating the electric field concentration at the PN junction surface.

[0030] For example, the negative electrode 8 and the SiC substrate 1 are in an ohmic contact; the positive electrode 7 and the corrugated P+ region 4 are also in an ohmic contact. For example, the material of the positive electrode 7 can be Ti, Ni, or Al; the material of the negative electrode 8 can be Ni.

[0031] For example, the material of passivation layer 6 can be silicon dioxide.

[0032] In some embodiments, the width W1 of the first interval region is in the range of 0.8 μm to 1 μm, and the width W of the Nth interval region is... N Within the range of 3.8μm to 4.2μm.

[0033] In some examples, when 1 ≤ n ≤ 10, W is satisfied. n =W n-1 +0.1μm; when 11≤n≤N, W n =W n-1 +0.2μm; where W n W is the width of the nth interval. n-1 Let W be the width of the (n-1)th interval. For example, if N=4, then the widths W1 of the first interval, W2 of the second interval, W3 of the third interval, and W4 of the fourth interval are 1μm, 1.1μm, 1.2μm, and 1.3μm, respectively. When N≥11, the widths of the first interval to the tenth interval satisfy W... n =W n-1 +0.1μm; the width of the eleventh interval to the width of the Nth interval satisfies W n =W n-1 +0.2μm.

[0034] In one embodiment of the present invention, the thickness of the first spacing region, the second spacing region, ..., the Nth spacing region is L1. The thickness of the groove region formed between any two adjacent first protrusions 41 is L2, satisfying L1 > L2. That is, provided that the side of the first protrusion 41 near the SiC substrate 1 is flush with the side of the second protrusion 51 near the SiC substrate 1, the thickness of the groove region formed by two adjacent first protrusions 41 is less than the thickness of the spacing region formed by two adjacent second protrusions 51. In other words, in the corrugated P+ region 4, the thickness of the planarization layer on the first protrusion 41 is greater than the thickness of the planarization layer on the second protrusion 51 in the JTE region 5.

[0035] For example, L1 is 0.8–2.1 μm and L2 is 0.3–1.5 μm.

[0036] In one example, the ion doping concentration of JTE region 5 is less than that of corrugated P+ region 4; along the side of corrugated P+ region 4 away from SiC substrate 1 and towards the side of corrugated P+ region 4 closer to SiC substrate 1, the ion doping concentration of corrugated P+ region 4 is a Gaussian doping distribution.

[0037] In one example, the ion doping concentration of the corrugated P+ region 4 is 1 × 10⁻⁶. 19 cm -3 ~1×10 21 cm -3 The ion doping concentration in region 5 of JTE is 5 × 10⁻⁶. 18 cm -3 ~5×10 20 cm -3 The doped ions are boron ions or aluminum ions.

[0038] In one example, the ion doping concentration of each control block 21 in the P-type control region 2 is 1 × 10⁻⁶. 17 cm -3 ~1×10 20 cm -3 The doped ions are boron ions or aluminum ions.

[0039] In one example, SiC substrate 1 is N-type ion doped, and the doping concentration of SiC substrate 1 is 1 × 10⁻⁶. 18 cm -3 ~1×10 20 cm -3 The SiC epitaxial layer 3 is N-type ion doped, and the doping concentration of the SiC epitaxial layer 3 is 1×10⁻⁶. 15 cm -3 ~1×10 17 cm -3 .

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0041] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches, characterized in that, include: negative electrode (8); A SiC substrate (1) is located on one side of the negative electrode (8); The P-type control region (2) includes a plurality of control blocks (21), which are embedded in the SiC substrate (1) on the side away from the negative electrode (8); The SiC epitaxial layer (3) is located on the side of the SiC substrate (1) away from the negative electrode (8), and the SiC epitaxial layer (3) covers the SiC substrate (1) and the P-type control region (2); A corrugated P+ region (4) is located in the middle of the SiC epitaxial layer (3) on the side away from the SiC substrate (1). The corrugated P+ region (4) is correspondingly disposed with the P-type control region (2). The corrugated P+ region (4) includes a plurality of first protrusions (41) facing the SiC epitaxial layer (3). The first protrusions (41) are embedded in the SiC epitaxial layer (3). The orthographic projection of the first protrusion (41) on the SiC substrate (1) coincides with the orthographic projection of the control block (21) on the SiC substrate (1). JTE region (5) is located on both sides of the corrugated P+ region (4). The JTE region (5) includes a plurality of second protrusions (51) facing the SiC epitaxial layer (3). The second protrusions (51) and the corrugated P+ region (4) form a first spacing region. Along the direction away from the corrugated P+ region (4), adjacent second protrusions (51) sequentially form a second spacing region, a third spacing region, ..., an Nth spacing region. The width of the first interval is W1, the width of the second interval is W2, ..., and the width of the Nth interval is W... N And satisfying W1 < W2 < ... < W N ; The positive electrode (7) is located on the side of the corrugated P+ region (4) away from the SiC substrate (1); A passivation layer (6) is located on both sides of the positive electrode (7), and the passivation layer (6) covers the JTE region (5).

2. The diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches according to claim 1, characterized in that, The width W1 of the first interval region is in the range of 0.8 μm to 1 μm, and the width W of the Nth interval region is... N Within the range of 3.8μm to 4.2μm.

3. The diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches according to claim 2, characterized in that, When 1 ≤ n ≤ 10, W is satisfied. n =W n-1 +0.1μm; when 11≤n≤N, W n =W n-1 +0.2μm; where W n W is the width of the nth interval. n-1 It represents the width of the (n-1)th interval.

4. The diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches according to any one of claims 1-3, characterized in that, The thickness of the first interval region, the second interval region, ..., the Nth interval region is L1; The thickness of the groove formed between any two adjacent first protrusions (41) is L2, which satisfies L1 > L2.

5. The diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches according to claim 4, characterized in that, The L1 ranges from 0.8 to 2.1 μm, and the L2 ranges from 0.3 to 1.5 μm.

6. The diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches according to claim 1, characterized in that, The ion doping concentration of the JTE region (5) is less than that of the corrugated P+ region (4); Along the side of the corrugated P+ region (4) away from the SiC substrate (1), and towards the side of the corrugated P+ region (4) closer to the SiC substrate (1), the ion doping concentration of the corrugated P+ region (4) is a Gaussian doping distribution.

7. The diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches according to claim 6, characterized in that, The ion doping concentration of the corrugated P+ region (4) is 1×10⁻⁶. 19 cm -3 ~1×10 21 cm -3 The ion doping concentration of the JTE region (5) is 5 × 10⁻⁶. 18 cm -3 ~5×10 20 cm -3 ; The doped ions are boron ions or aluminum ions.

8. The diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches according to claim 1, characterized in that, The ion doping concentration of each control block (21) in the P-type control region (2) is 1×10⁻⁶. 17 cm -3 ~1×10 20 cm -3 ; The doped ions are boron ions or aluminum ions.

9. The diode avalanche shaping device with a composite termination structure and resistance to secondary avalanches according to claim 1, characterized in that, The SiC substrate (1) is N-type ion doped, and the doping concentration of the SiC substrate (1) is 1×10⁻⁶. 18 cm -3 ~1×10 20 cm -3 ; The SiC epitaxial layer (3) is N-type ion doped, and the doping concentration of the SiC epitaxial layer (3) is 1×10⁻⁶. 15 cm -3 ~1×10 17 cm -3 .

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