Radiation-resistant reinforced IGBT structure and preparation method thereof
By introducing deeply doped regions and trench gate structures into the IGBT structure, hole injection and electron-hole recombination efficiency are enhanced, solving the problem of insufficient radiation resistance of domestically produced IGBT devices in high-altitude environments and improving the device's withstand voltage and reliability.
Patent Information
- Application Number
- CN202511370947.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-24
- Publication Date
- 2025-12-16
AI Technical Summary
Domestic high-voltage IGBT devices have insufficient radiation resistance in high-altitude environments, resulting in a lower safe operating voltage than foreign products, which cannot meet the needs of high-altitude high-voltage DC power transmission.
Multiple deeply doped regions are introduced into the IGBT structure. These deeply doped regions are embedded in the N-type buffer along the direction perpendicular to the N-type buffer interface and extend into the N-type drift region. The doping concentration is higher than that of the P-type collector region. Combined with the trench gate structure, this enhances the hole injection efficiency and electron-hole recombination efficiency, and reduces the amount of deposited charge.
This improves the radiation resistance of IGBT devices in high-altitude environments, enhances the voltage withstand capability and reliability of the devices, avoids avalanche breakdown, and meets the needs of high-altitude high-voltage direct current transmission.
Smart Images
Figure CN121152228A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of power semiconductor devices, in particular to an anti-radiation reinforced IGBT structure and a preparation method thereof. BACKGROUND
[0002] Insulated Gate Bipolar Transistor (IGBT) has low input impedance, low on-state voltage drop and high switching frequency, and has been rapidly developed in the fields of electric vehicles, train traction, grid-connected power transmission, etc., among which high-voltage and large-capacity IGBT devices play an important role in high-voltage direct current transmission. As a core component of flexible direct current transmission, IGBT devices need to exhibit excellent reliability in many extreme conditions. After several generations of device iteration, the current high-voltage IGBT device has strong robustness in avalanche, short circuit, overcurrent, etc. However, these advantages exhibited by high-voltage IGBT devices are usually only reflected in low-altitude environments, and there is less research on the reliability of IGBT devices in high-altitude environments.
[0003] The atmosphere in high-altitude (such as above 2000 meters) areas is thinner than that in low-altitude areas, and the shielding effect of cosmic rays (mainly high-energy protons and heavy ions) is significantly weakened. When high-energy particles enter the semiconductor layer of IGBT, they will impact the atoms in the lattice through ionization effect, exciting the valence band electrons to the conduction band, and instantaneously generating a large number of electron-hole pairs. These extra carriers will generate a strong electric field in the depletion layer. Under the repulsion-attraction effect of the strong electric field of the depletion layer, the holes drift upward until they are collected by the emitter, and the electrons drift downward until they are collected by the collector. The drift of a large number of carriers will form a large instantaneous current, eventually leading to a decrease in IGBT voltage resistance and causing local avalanche and breakdown. The safe working voltage of domestic IGBT at high altitudes is generally lower than that of IGBT devices produced by foreign mainstream manufacturers. It is urgent to improve the anti-radiation capability of existing IGBT devices to meet the growing demand for high-altitude high-voltage direct current transmission in China. SUMMARY
[0004] The present application provides an anti-radiation reinforced IGBT structure and a preparation method thereof.
[0005] The anti-radiation reinforced IGBT structure provided by the present application comprises:
[0006] a collector electrode;
[0007] a semiconductor layer arranged on the collector electrode; the semiconductor layer comprises a P-type collector region, an N-type buffer region, an N-type drift region, a P-body region and an emitter region arranged in layers, and the emitter region comprises a P+ region and an N+ region;
[0008] A trench gate embedded in the semiconductor layer; the trench gate is embedded in the emitter region and the P-body region along a direction perpendicular to the surface of the emitter region and extends into the interior of the N-type drift region; the inner wall and bottom of the trench gate are provided with an insulating oxide layer, and the inner side of the insulating oxide layer is filled with a gate electrode;
[0009] An isolation medium layer disposed above the trench grid; and,
[0010] An emitter disposed above the emitter region and the isolation dielectric layer;
[0011] The P-type collector region has multiple deeply doped regions. The deeply doped regions are embedded in the N-type buffer along a direction perpendicular to the N-type buffer interface and extend to the interior of the N-type drift region at a preset depth. The doping concentration of the deeply doped regions is higher than that of other regions of the P-type collector region.
[0012] Optionally, the deeply doped region forms a gradually decreasing doping concentration gradient from the collector towards the N-type drift region.
[0013] Optionally, the doping concentration gradient is a linear distribution, a Gaussian distribution, or an error distribution.
[0014] Optionally, the thickness of the deeply doped region is 5 μm.
[0015] Optionally, the P-type doping concentration in the deeply doped region is not less than 1×10⁻⁶. 19 cm -3 .
[0016] Optionally, the multiple deeply doped regions are interconnected in a network structure in the planar direction of the P-type collector region.
[0017] The radiation-hardened IGBT structure provided by this invention can be prepared through the following steps:
[0018] S1, fabricate a semiconductor layer, the semiconductor layer comprising a stacked P-type collector region, an N-type buffer region, an N-type drift region and a P-body region;
[0019] S2, P-type doping is performed in a local area of the P-type collector region by high-temperature diffusion or high-energy ion implantation to obtain multiple deep-doped regions; the deep-doped regions are embedded in the N-type buffer along a direction perpendicular to the N-type buffer interface and extend to the interior of the N-type drift region at a preset depth, and the doping concentration of the deep-doped regions is higher than that of other areas of the P-type collector region.
[0020] Optionally, after step S1 or after step S2, the following step may be further included:
[0021] Trenches are etched along a direction perpendicular to the surface of the P-body region, and an insulating oxide layer and a gate electrode are prepared in the trenches to obtain a trench gate;
[0022] An emitter region is prepared on the surface of the P-body region, the emitter region including a P+ region and an N+ region, the N+ region being disposed on both sides of the trench gate.
[0023] Optionally, after the emitter region and the deeply doped region are prepared, the method further includes the following steps:
[0024] An isolation dielectric layer is deposited above the trench gate, and an emitter is fabricated above the isolation dielectric layer and the emitter; a collector electrode is fabricated on the surface of the P-type collector region.
[0025] Optionally, the P-type dopant element in the deep doped region is at least one of boron, indium, gallium, and aluminum.
[0026] The present invention has the following beneficial effects:
[0027] The technical solution of this invention is based on an IGBT with a trench gate structure. Multiple deeply doped regions are provided in the P-type collector region. These deeply doped regions are embedded in the N-type buffer zone and extend into the interior of the N-type drift region along a direction perpendicular to the N-type buffer zone interface. The doping concentration of the deeply doped regions is higher than that of other regions in the P-type collector region. The presence of these deeply doped regions enhances the hole injection efficiency of the P-type collector region and increases the hole concentration at the bottom of the N-type drift region. When cosmic rays irradiate the IGBT and generate a large number of electron-hole pairs in the semiconductor layer, a large number of electrons migrate towards the collector under the influence of the electric field. The presence of these deeply doped regions enhances the electron-hole recombination efficiency in the bottom region of the N-type drift region, reducing the amount of deposited charge in this region, thereby improving the radiation resistance of the IGBT. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0029] Figure 1 This is a schematic diagram of a radiation-hardened IGBT provided by the present invention.
[0030] Explanation of reference numerals in the attached figures:
[0031] 1. Collector; 2. P-type collector region; 2-1. Deeply doped region; 3. N-type buffer zone; 4. N-type drift region; 5. P-body region; 6. Emitter region; 7. Trench gate; 7-1. Insulating oxide layer; 7-2. Gate electrode; 8. Isolation dielectric layer; 9. Emitter. Detailed Implementation
[0032] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0033] In the description of this invention, it should be understood that the terms "upper," "lower," "vertical," "horizontal," "top," "bottom," "side," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this 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 this invention; in the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0034] In this embodiment of the invention, "+" and "-" are used to indicate the doping concentration of a semiconductor region, which is a simplified expression commonly used in the semiconductor field; for example, the P+ region represents a heavily P-type doped region (P-type doping concentration is typically ≥1×10⁻⁶). 18 cm -3 High hole concentration and strong conductivity; the N+ region represents the heavily doped N-type region (N-type doping concentration is usually ≥1×10⁻⁶). 18 cm -3 High electron concentration and strong conductivity; the P-region represents a lightly doped P-type region (P-type doping concentration is usually ≤1×10⁻⁶). 17 cm -3 (This area) mainly serves as a channel region for carrier transmission.
[0035] See Figure 1 The radiation-hardened IGBT structure proposed in this embodiment of the invention is based on a trench gate IGBT, including a collector 1, a semiconductor layer, a trench gate 7, and an emitter 9.
[0036] A semiconductor layer is disposed on the collector 1; the semiconductor layer includes, from bottom to top, a P-type collector region 2, an N-type buffer region 3, an N-type drift region 4, a P-body region 5 and an emitter region 6 stacked together, and the emitter region 6 includes a P+ region and an N+ region.
[0037] The trench gate 7 is embedded in the semiconductor layer; specifically, the trench gate 7 is embedded in the emitter region 6, the P-body region 5 and extends into the interior of the N-type drift region 4 in a direction perpendicular to the surface of the emitter region 6. The inner wall and bottom of the trench gate 7 are provided with an insulating oxide layer 7-1, and the inner side of the insulating oxide layer 7-1 is filled with gate electrode material to form a gate electrode 7-2; the N+ region is disposed on both sides of the trench gate 7.
[0038] An isolation medium layer 8 is disposed above the trench grid 7; the emitter 9 is disposed above the emitter region 6 and the isolation medium layer 8.
[0039] In this embodiment of the invention, the P-type collector region 2 is provided with a plurality of deep doped regions 2-1. The deep doped regions 2-1 are embedded in the N-type buffer 3 along a direction perpendicular to the interface of the N-type buffer 3 and extend into the interior of the N-type drift region 4 at a preset depth (the specific value of the preset depth can be set according to the functional design requirements of the IGBT device). The doping concentration of the deep doped regions 2-1 is higher than that of other regions of the P-type collector region 2.
[0040] In this embodiment of the invention, the presence of the deeply doped region 2-1 enhances the hole injection efficiency of the P-type collector region 2 and increases the hole concentration at the bottom of the N-type drift region 4. When cosmic rays irradiate the IGBT and generate a large number of electron-hole pairs in the semiconductor layer, a large number of electrons migrate towards the collector 1 under the action of the electric field. The presence of the deeply doped region 2-1 enhances the electron-hole recombination efficiency in the bottom region of the N-type drift region 4 and reduces the amount of deposited charge in this region, thereby improving the radiation resistance of the IGBT.
[0041] If the P-type doping concentration is too high in the region of the deep doped region 2-1 near the N-type drift region 4, resulting in strong conductivity, avalanche breakdown at that location may occur due to charge deposition.
[0042] Therefore, in some embodiments, the deep doped region 2-1 is designed with a gradually decreasing doping concentration gradient from the collector 1 to the N-type drift region 4. The setting of the doping concentration gradient helps to increase the electron barrier height, while reducing the electric field strength of the reconstructed electric field caused by charge deposition during radiation, suppressing avalanche breakdown at the junction interface of the deep doped region 2-1 and the N-type drift region 4, and further improving the radiation resistance of the IGBT device.
[0043] In some embodiments, the doping concentration gradient of the deeply doped region 2-1 is linearly distributed, that is, the doping concentration decreases linearly from the collector 1 to the N-type drift region 4. Since the linearly decreasing concentration gradient is uniform, the hole injection rate from the collector region to the drift region is stable, avoiding excessive concentration or insufficiency of local carriers, which is beneficial to the uniformity of conductance modulation during conduction and reduces local power consumption.
[0044] In some embodiments, the doping concentration gradient of the deeply doped region 2-1 is Gaussian, that is, the concentration decreases rapidly near the collector 1 and the decay slows down as it moves away from the collector 1, exhibiting a Gaussian curve decay. The Gaussian distribution is closer to the natural result of the diffusion process in semiconductor manufacturing (the concentration distribution after impurity diffusion is approximately Gaussian), and no additional complex process control is required, making it suitable for large-scale mass production.
[0045] In other embodiments, the doping concentration gradient of the deep doped region 2-1 can also be an error distribution such as a t-distribution or an exponential distribution; for example, in a t-distribution, after the concentration decays to a certain depth, the tail of the gradient retains a higher residual concentration to maintain the conductivity modulation effect.
[0046] In some preferred embodiments, the doping concentration of the deeply doped region 2-1 is not less than 1×10⁻⁶. 19 cm -3 .
[0047] In practical applications, the typical thickness of the N-type buffer of IGBT power devices is 1~3μm, and the thickness of the deep doped region 2-1 can be selected as 5μm or approximately 5μm. This ensures that the deep doped region 2-1 can effectively penetrate into the N-type drift region 4 to achieve the radiation resistance effect, while avoiding the deep doped region 2-1 penetrating too deeply into the N-type drift region 4 and damaging the overall withstand voltage performance. Moreover, in high-temperature diffusion or ion implantation processes, a depth of about 5μm is within the range of deep doping that can be precisely controlled.
[0048] In some embodiments, in the planar direction of the P-type collector region 1, multiple deeply doped regions 2-1 are interconnected in a network structure. For example, they can be multiple parallel strip-shaped deeply doped regions interwoven laterally to form a network structure, or they can be a latitude and longitude or radial network structure formed by the periodic arrangement of deeply doped regions. The interconnected network structure of multiple deeply doped regions can avoid current concentration caused by excessive local injection and avoid the risk of electric field distortion caused by isolated point-like deep doping. The layout of the deeply doped regions 2-1 does not need to correspond to the front structure of the IGBT device (the side where the trench gate 7 is located).
[0049] Combining the conventional processing steps of power semiconductors, the radiation-hardened IGBT structure proposed in this embodiment of the invention can be prepared through the following steps:
[0050] S1, fabricating a semiconductor layer, the semiconductor layer comprising a stacked P-type collector region, an N-type buffer region, an N-type drift region and a P-body region.
[0051] S2, P-type doping is performed in a local area of the P-type collector region by high-temperature diffusion or high-energy ion implantation to obtain multiple deep-doped regions; the deep-doped regions are embedded in the N-type buffer along the direction perpendicular to the N-type buffer interface and extend into the interior of the N-type drift region at a preset depth, and the doping concentration of the deep-doped regions is higher than that of other areas of the P-type collector region.
[0052] The fabrication of the IGBT front-side structure can be performed after either step S1 or step S2. The fabrication of the IGBT front-side structure includes the following steps:
[0053] Trenches are etched along a direction perpendicular to the surface of the P-body region, and an insulating oxide layer and a gate electrode are prepared in the trenches to obtain a trench gate; an emitter region is prepared on the surface of the P-body region, which includes a P+ region and an N+ region, with the N+ region disposed on both sides of the trench gate.
[0054] In step S2, both high-temperature diffusion and high-energy ion implantation can be used to prepare the deep-doped region. The P-type doping element in the deep-doped region includes, but is not limited to, one or more of boron, indium, gallium, and aluminum.
[0055] The core of high-temperature diffusion is to excite the thermal motion of doped atoms by high temperature (e.g., 800℃~1200℃), so that the doped atoms spontaneously migrate from the high concentration region to the low concentration region. In some specific feasible methods, an extremely thin high-concentration impurity film (e.g., boron film) can be formed in a local area on the surface of a pre-deposition process of a P-type collector region. Then, the boron atoms are diffused towards the N-type drift region by high temperature to form a deep doped region.
[0056] High-energy ion implantation accelerates impurity ions (such as boron ions) through a high-voltage electric field, giving the impurity ions enough kinetic energy to directly bombard and embed them into the crystal lattice, penetrating to the target depth. High-energy ion implantation can precisely control the doping depth and dosage, and has strong directionality, which can reduce the lateral diffusion of impurity ion implantation.
[0057] After the emitter region and the deeply doped region are prepared, the semiconductor layer is completed. The next steps include: depositing an isolation dielectric layer above the trench gate, preparing the emitter above the isolation dielectric layer and the emitter, and preparing the collector on the surface of the P-type collector region; the emitter and collector can be metal electrodes.
[0058] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A radiation-hardened IGBT structure, characterized in that, include: collector; A semiconductor layer is disposed on the collector electrode; the semiconductor layer includes a stacked P-type collector region, an N-type buffer region, an N-type drift region, a P-body region and an emitter region, the emitter region including a P+ region and an N+ region; A trench gate embedded in the semiconductor layer; the trench gate is embedded in the emitter region and the P-body region along a direction perpendicular to the surface of the emitter region and extends into the interior of the N-type drift region; the inner wall and bottom of the trench gate are provided with an insulating oxide layer, and the inner side of the insulating oxide layer is filled with a gate electrode; An isolation medium layer is disposed above the trench grid; as well as, An emitter disposed above the emitter region and the isolation dielectric layer; The P-type collector region has multiple deeply doped regions. The deeply doped regions are embedded in the N-type buffer along a direction perpendicular to the N-type buffer interface and extend to the interior of the N-type drift region at a preset depth. The doping concentration of the deeply doped regions is higher than that of other regions of the P-type collector region.
2. The radiation-hardened IGBT structure according to claim 1, characterized in that, The deeply doped region forms a gradually decreasing doping concentration gradient from the collector towards the N-type drift region.
3. The radiation-hardened IGBT structure according to claim 2, characterized in that, The doping concentration gradient is linear, Gaussian, or error-distributed.
4. The radiation-hardened IGBT structure according to claim 1, characterized in that, The thickness of the deeply doped region is 5 μm.
5. The radiation-hardened IGBT structure according to claim 1, characterized in that, The P-type doping concentration in the deeply doped region is not less than 1×10⁻⁶. 19 cm -3 .
6. The radiation-hardened IGBT structure according to claim 1, characterized in that, The multiple deeply doped regions form an interconnected network structure in the planar direction of the P-type collector region.
7. A method for preparing a radiation-hardened IGBT structure, characterized in that, Including the following steps: S1, fabricate a semiconductor layer, the semiconductor layer comprising a stacked P-type collector region, an N-type buffer region, an N-type drift region and a P-body region; S2, P-type doping is performed in a local area of the P-type collector region by high-temperature diffusion or high-energy ion implantation to obtain multiple deep-doped regions; the deep-doped regions are embedded in the N-type buffer along a direction perpendicular to the N-type buffer interface and extend to the interior of the N-type drift region at a preset depth, and the doping concentration of the deep-doped regions is higher than that of other areas of the P-type collector region.
8. The method for preparing a radiation-hardened IGBT structure according to claim 7, characterized in that, After step S1 or after step S2, the following step is also included: Trenches are etched along a direction perpendicular to the surface of the P-body region, and an insulating oxide layer and a gate electrode are prepared in the trenches to obtain a trench gate; An emitter region is prepared on the surface of the P-body region, the emitter region including a P+ region and an N+ region, the N+ region being disposed on both sides of the trench gate.
9. The method for preparing a radiation-hardened IGBT structure according to claim 8, characterized in that, After the emitter region and the deeply doped region are prepared, the following steps are also included: An isolation dielectric layer is deposited above the trench gate, and an emitter is fabricated above the isolation dielectric layer and the emitter. A collector electrode is fabricated on the surface of the P-type collector region.
10. The method for preparing a radiation-hardened IGBT structure according to claim 7, characterized in that, The P-type doping element in the deep doped region is at least one of boron, indium, gallium, and aluminum.