FRD device proton irradiation processing method based on epitaxial structure

Abstract

The invention relates to an FRD device proton irradiation processing method based on an epitaxial structure, and belongs to the technical field of semiconductor manufacturing, and the method comprises the steps: S100, obtaining an FRD device based on the epitaxial structure; s200, proton irradiation is carried out on the FRD device based on the epitaxial structure to obtain a proton irradiation FRD device, the proton irradiation FRD device comprises proton injection regions, the proton injection regions are located at the contact interface of the lightly doped N-layer and the heavily doped N + layer, the proton injection regions comprise a first proton injection region and a second proton injection region, and the first proton injection region and the second proton injection region are located at the contact interface of the lightly doped N-layer and the heavily doped N + layer; the first proton injection region is partially located in the lightly doped N-layer, and the second proton injection region is partially located in the heavily doped N + layer; and S300, carrying out annealing treatment on the proton irradiation FRD device to obtain the proton irradiation treatment FRD device. According to the invention, the reverse recovery time of the FRD device can be shortened, and the softness factor of the FRD device can be synchronously optimized.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a proton irradiation processing method for an FRD device based on an epitaxial structure. Background Art

[0002] FRD devices (Fast Recovery Diode) are power semiconductor devices specially designed for fast switching applications. They have a faster reverse recovery time than ordinary diodes and are therefore very suitable for use in high-frequency and high-efficiency power converters, inverters, and other power electronic devices.

[0003] Traditional FRD device carrier lifetime control mostly adopts electron irradiation process, platinum diffusion process, helium ion implantation process, proton irradiation process, etc. These carrier control processes have the following defects: 1) The irradiation distribution uniformity of the electron irradiation process is poor, resulting in inaccurate carrier lifetime control and difficulty in synchronous optimization of the reverse recovery time trr and the softness factor S (S = tb / ta); 2) The high temperature of the platinum diffusion process easily introduces lattice stress, and the doping concentration gradient control accuracy is low; 3) The high-energy helium ions of the helium ion implantation process easily cause deep lattice damage, resulting in increased leakage current; 4) The proton irradiation process is mostly designed for PN junctions, and lacks targeted control of the lifetime of the N-N+ junction, resulting in a prominent contradiction between the device's on-state voltage drop VF and switching loss.

[0004] Therefore, the present invention proposes a proton irradiation treatment method for FRD devices based on epitaxial structure, aiming to partially or completely solve the above-mentioned technical problems in the existing wafer high-energy hydrogen ion implantation process monitoring, and simultaneously optimize the reverse recovery time and softness factor of the FRD device, providing a better solution for the preparation of FRD devices based on epitaxial structure. Summary of the Invention

[0005] This invention proposes a proton irradiation treatment method for epitaxially structured FRD devices, aiming to partially or completely address technical issues such as inaccurate carrier lifetime control, difficulty in simultaneously optimizing reverse recovery time and softness factor, easy introduction of lattice stress, deep lattice damage, increased leakage current, and lack of targeted control of N-N+ junction lifetime in existing FRD devices. To achieve the objectives of this invention, the technical solutions provided by this invention are as follows:

[0006] A proton irradiation treatment method for an epitaxial structure-based FRD device comprises:

[0007] Step S100: Obtaining an epitaxial structure-based FRD device, along the thickness direction of the epitaxial structure-based FRD device, the epitaxial structure-based FRD device includes: an anode metal contact layer, a P-type layer, a lightly doped N- layer, a heavily doped N+ layer, an ultra-heavily doped N++ layer, and a cathode metal contact layer, wherein the cathode metal contact layer, the ultra-heavily doped N++ layer, the heavily doped N+ layer, the lightly doped N- layer, the P-type layer, and the anode metal contact layer are stacked and connected in sequence from bottom to top;

[0008] Step S200: Proton irradiating an epitaxial structure-based FRD device to obtain a proton-irradiated FRD device, wherein the proton-irradiated FRD device includes a proton-injected region, the proton-injected region is located at a contact interface between a lightly-doped N-layer and a heavily-doped N+ layer, the proton-injected region includes a first proton-injected region and a second proton-injected region, the first proton-injected region is partially located in the lightly-doped N-layer, and the second proton-injected region is partially located in the heavily-doped N+ layer;

[0009] Step S300: performing annealing treatment on the proton irradiated FRD device to obtain a proton irradiated FRD device.

[0010] Optionally, in step S100, the FRD device voltage is greater than or equal to 1200V; and / or the thickness of the lightly doped N-layer is 60-70 μm, and the doping concentration is 6×10 13 cm -3 -8×10 13 cm -3 ; and / or, the thickness of the heavily doped N+ layer is 20-30 μm, and the doping concentration is 2×10 14 cm -3 -3×10 14 cm -3 and / or, the thickness of the heavily doped N++ layer is 100-120 μm, and the doping concentration is 2×10 19 cm -3 -3×10 19 cm -3 .

[0011] Optionally, in step S200, the energy range of proton irradiation is 3.4-3.9 MeV, the proton Bragg peak is located at the contact interface between the lightly doped N- layer and the heavily doped N+ layer, and the dose range of proton irradiation is 5×10 11 -1×10 12 p / cm 2 .

[0012] Optionally, when the platinum diffusion temperature is 860°C-880°C, the proton irradiation dose is 5×10 11 p / cm 2 Or, when the platinum diffusion temperature is 880℃-900℃, the proton irradiation dose is 8×1011 p / cm 2 Alternatively, when the platinum diffusion temperature is 900℃-920℃, the proton irradiation dose is 1×10 12 p / cm 2 .

[0013] Optionally, when the platinum diffusion temperature increases by 20°C, the corresponding proton irradiation dose increases by 3×10 11 p / cm 2 .

[0014] Optionally, in step S300 , vacuum annealing is used for the annealing process, and the annealing temperature range is 250° C.-350° C.

[0015] Optionally, the proton irradiation dose is 5×10 11 p / cm 2 When the annealing temperature is 250℃; or the proton irradiation dose is 8×10 11 p / cm 2 When the annealing temperature is 300℃; or the proton irradiation dose is 1×10 12 p / cm 2 The annealing temperature is 350℃.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) In the present invention, first, proton irradiation is limited to the N- / N+ interface, and a uniform defect layer is formed in the N-N+ junction region, avoiding uniform distribution of defects in the entire N-drift region. This localized lifetime reduction strategy effectively reduces the reverse recovery charge while having little impact on the forward voltage drop, achieving an optimized balance of performance. Due to the reduction in carrier lifetime, the reverse recovery time is shortened, the proton irradiation softness factor S is simultaneously optimized, and the switching loss is reduced. Experimental data show that the reverse recovery time trr is reduced by more than 30% compared with the traditional process, and the softness factor (S = tb / ta) is improved by 30%-50%, which greatly reduces the device Switching loss is very suitable for high-frequency application scenarios; in addition, the introduction of the proton injection area PD can help control the carrier dynamics during the reverse recovery process, make the recovery curve smoother, reduce electromagnetic interference and device stress, and improve system reliability; in addition, proton irradiation and annealing treatment can be seamlessly integrated into the existing semiconductor manufacturing process, and is compatible with the existing epitaxial growth process. It does not require additional high-temperature steps and has high industrial application feasibility. The vacuum annealing process (250-350℃) effectively repairs shallow lattice damage, reduces leakage current density, improves voltage resistance, avoids lattice stress accumulation, and increases device yield by 15%.

[0018] (2) In the present invention, first, by synergistically controlling the energy (3.4-3.9 MeV) and dose (5×10 11 -1×10 12 p / cm 2 ), the Bragg peak can be positioned at the N- / N+ interface, achieving localized regulation of the carrier lifetime and avoiding the introduction of too many defects in the entire N-layer, thereby shortening the reverse recovery time while reducing the impact on the forward conduction performance; in addition, the selection of the proton irradiation dose is closely matched with the platinum diffusion temperature, and the annealing temperature is matched with the irradiation dose. Through the matching of the three, flexibility in process optimization is provided. Different doses can be selected according to the platinum diffusion temperature, and appropriate temperatures can be selected according to different doses to ensure the performance consistency of the FRD device in long-term operation, and then the carrier lifetime distribution can be optimized under different process conditions. Multiple synergistic effects improve the stability of the FRD device performance and enhance the flexibility of the FRD device manufacturing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 A schematic flow chart of the proton irradiation treatment method for an epitaxial structure-based FRD device according to the present invention;

[0021] Figure 2 A schematic structural diagram of the FRD device applied for in the present invention;

[0022] Figure 3 Schematic diagram of the principle of proton irradiation of the FRD device applied for by the present invention;

[0023] Figure 4 This is a schematic diagram of the reverse recovery curve of the FRD device applied for in the present invention.

[0024] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments; based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] Furthermore, 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 the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means one, two, or more than two, unless otherwise specifically defined.

[0028] In this application, unless otherwise expressly specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed or detachable connections, integral molding, or integration; they may refer to mechanical or electrical connections; they may refer to direct or indirect connections through an intermediate medium; they may refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0030] like Figures 1 to 4 As shown, a proton irradiation treatment method for an epitaxial structure-based FRD device includes:

[0031] Step S100: Obtaining an epitaxial structure-based FRD device. Along the thickness direction of the epitaxial structure-based FRD device, the epitaxial structure-based FRD device includes: an anode metal contact layer 10, a P-type layer 20, a lightly doped N- layer 30, a heavily doped N+ layer 40, an ultra-heavily doped N++ layer 50, and a cathode metal contact layer 60. The cathode metal contact layer 60, the ultra-heavily doped N++ layer 50, the heavily doped N+ layer 40, the lightly doped N- layer 30, the P-type layer 20, and the anode metal contact layer 10 are stacked and connected in sequence from bottom to top.

[0032] In some embodiments, along the thickness direction of the epitaxial FRD device, the cathode metal contact layer 60, the ultra-heavily doped N++ layer 50, the heavily doped N+ layer 40, the lightly doped N- layer 30, the P-type layer 20, and the anode metal contact layer 10 are stacked and connected in sequence from bottom to top. The anode metal contact layer 10 is connected to the P-type layer 20, and the cathode metal contact layer 60 is connected to the ultra-heavily doped N++ layer 50, forming a typical FRD vertical structure. A PN junction is formed between the P-type layer 20 and the lightly doped N- layer 30. The lightly doped N- layer 30 can serve as a drift region, the heavily doped N+ layer 40 serves as a buffer layer, and the ultra-heavily doped N++ layer 50 serves as a substrate layer. The NN structure FRD device, through its multi-layer heterojunction design, can achieve efficient conduction and fast shutdown.

[0033] In some embodiments, the anode metal contact layer 10 (Al) and the cathode metal contact layer 60 (TiNiAg) provide low-resistance contact; the P-type layer 20 and the lightly doped N-layer 30 constitute a core PN junction, which determines the forward voltage drop and reverse voltage characteristics; the heavily doped N+ layer and the ultra-heavily doped N++ layer optimize carrier transport and contact resistance, and are suitable for high-frequency, high-voltage power conversion scenarios (such as switching power supplies and inverters).

[0034] In some embodiments, the anode metal contact layer 10 is made of Al (aluminum). The anode metal contact layer 10 can provide a low-resistance current path, ensuring that current can efficiently flow from the external circuit into the P-type region of the device.

[0035] In some embodiments, the P-type layer 20 is located immediately below the anode metal contact layer 10 and, as part of the PN junction, forms a PN junction with the lightly doped N-layer 30 (forming or including an N-drift region). During forward bias, the P-type layer provides hole carriers, reducing the forward voltage drop and allowing current to flow. During reverse bias, the P-type layer forms a depletion region, blocking current flow. During reverse recovery, the P-type layer helps accelerate minority carrier extraction within the drift region (lightly doped N-layer), further reducing the reverse recovery time trr.

[0036] In some embodiments, the lightly doped N-layer 30 is located below the P-type layer 20. Due to its low doping concentration, it can withstand high reverse voltages and serves as the primary region for reverse voltage. Under forward bias, it serves as the primary current transmission path, but due to its high resistivity, it generates a certain voltage drop. During reverse recovery, minority carrier recombination is a key factor in determining the reverse recovery time, and subsequent proton irradiation can be used to control the carrier lifetime.

[0037] In some embodiments, the heavily doped N+ layer 40 is located below the lightly doped N+ layer 30, which provides a low-resistance path to ensure that current can flow into or out of the cathode quickly and efficiently. When forward biased, the PN junction between the heavily doped N+ layer 40 and the drift region of the lightly doped N- layer 30 forms the main conductive channel; when reverse biased, the heavily doped N+ layer 40 helps to quickly extract the minority carriers accumulated in the drift region, thereby shortening the reverse recovery time.

[0038] In some embodiments, the super heavily doped N++ layer 50 is located below the heavily doped N+ layer 40. Due to the higher doping concentration, the resistance of the cathode contact area can be further reduced, the current transmission efficiency can be improved, and the cathode contact area can still maintain low impedance characteristics under high current conditions to avoid overheating and reliability problems.

[0039] In some embodiments, cathode metal contact layer 60 is located below the heavily doped N++ layer 50. The material of cathode metal contact layer 60 is TiNiAg (titanium nickel silver). TiNiAg alloy has excellent conductivity, corrosion resistance, and welding properties, and can maintain a stable electrical connection in high-temperature environments. Cathode metal contact layer 60 contacts the heavily doped N++ layer 50 and provides a stable ohmic contact, ensuring that current can efficiently flow from the device to the external circuit.

[0040] Step S200: Proton irradiating the epitaxial structure-based FRD device to obtain a proton irradiated FRD device, wherein the proton irradiated FRD device includes a proton implantation region PD, the proton implantation region PD is located at the contact interface between the lightly doped N- layer 30 and the heavily doped N+ layer 40, and the proton implantation region PD includes a first proton implantation region PD1 and a second proton implantation region PD2, wherein the first proton implantation region PD1 is partially located in the lightly doped N- layer 30, and the second proton implantation region PD2 is partially located in the heavily doped N+ layer 40;

[0041] In some embodiments, proton irradiation is positioned at the contact surface between the lightly doped N- layer 30 and the heavily doped N+ layer 40, and the peak position of proton injection can be controlled at the N- / N+ contact interface. Proton irradiation can control the depth and concentration of proton irradiation by adjusting the proton energy and dose, so that the performance parameters can be adjusted and optimized according to the specific requirements of the FRD device.

[0042] In some embodiments, after proton irradiation, a proton implantation region PD is introduced. After the proton implantation region PD includes a first proton implantation region PD1 and a second proton implantation region PD2, the region of the N-drift region close to the N+ buffer layer accumulates minority carriers during forward conduction, accelerating the recombination of these carriers, which can reduce the stored charge during reverse recovery, thereby shortening the reverse recovery time. Placing the proton implantation region PD away from the PN junction (the interface between the P-type layer 20 and the lightly doped layer N-30) can avoid overly affecting the conductance modulation during forward conduction, thereby maintaining a low forward voltage drop while reducing the reverse recovery time. The proton implantation region PD is close to the heavily doped N+ layer, which can help control the carrier removal behavior during the reverse recovery process, making the recovery process smoother, reducing oscillations and electromagnetic interference.

[0043] Step S300: Anneal the proton-irradiated FRD device to obtain a proton-irradiated processed FRD device.

[0044] In some embodiments, as Figure 4 shown, the reverse recovery characteristic curve of the FRD device shows the voltage change during the reverse recovery process of the FRD device. The horizontal axis: time (in nanoseconds, ns), representing the time evolution of the reverse recovery process, and the vertical axis: voltage (V), with the reference voltage Vcc as the reference, showing the voltage dynamics across the diode. Both the unirradiated and irradiated curves start from a high voltage close to Vcc, drop to a minimum point, and then rise back to Vcc, reflecting the dynamic behavior of the diode reverse recovery.

[0045] In some embodiments, as Figure 4 shown, the reverse recovery process of the FRD device includes two key time periods: the ta (delay time) period and the tb (fall time) period. The reverse recovery time trr is: trr = ta + tb, and the softness factor S is: S = tb / ta. Among them, in the ta period, that is, the period from when the voltage starts to drop to reaching the lowest point, in this stage, the charge stored in the diode PN junction starts to be cleared, and the reverse recovery current rises from zero to the peak; in the tb period, that is, the period from the lowest voltage point to when the voltage steadily rises back to Vcc, in this stage, the stored charge continues to be cleared, and the reverse recovery current drops from the peak to nearly zero. The softness factor S is an indicator to measure whether the reverse recovery process is "soft" or "hard": S > 1, tb > ta, the tb recovery time is longer, and the voltage rise curve is relatively gentle, which is called "soft recovery", reducing voltage and current oscillations, reducing electromagnetic interference, and reducing switching losses; S < 1, tb < ta, the tb recovery time is shorter, and the voltage rise curve is steep, which is called "hard recovery", which may generate large voltage spikes and electromagnetic interference, affecting the circuit stability. Obviously, from Figure 4It can be seen from the figure that after electron irradiation, the reverse recovery time trr of the FRD device is shortened. At the same time, the synchronously optimized softness factor S>1 reduces the oscillation of the voltage and current of the FRD device, reduces electromagnetic interference, and reduces switching loss.

[0046] In the present invention application, first, proton irradiation is limited to the N- / N+ interface, and a uniform defect layer is formed in the N-N+ junction region, avoiding uniform distribution of defects in the entire N-drift region. This localized lifetime reduction strategy effectively reduces the reverse recovery charge while having little impact on the forward voltage drop, achieving an optimized balance of performance. Due to the reduction in carrier lifetime, the reverse recovery time is shortened, the proton irradiation softness factor S is synchronously optimized, and the switching loss is reduced. Experimental data show that the reverse recovery time trr is reduced by more than 30% compared with traditional processes, and the softness factor (S=tb / ta) is improved by 30%-50%, which greatly reduces the device switching time. The device reduces the on-off loss and is very suitable for high-frequency applications. In addition, the introduction of the proton-implanted region (PD) can help control the carrier dynamics during the reverse recovery process, making the recovery curve smoother, reducing electromagnetic interference and device stress, and improving system reliability. In addition, the proton irradiation and annealing treatment can be seamlessly integrated into the existing semiconductor manufacturing process and is compatible with the existing epitaxial growth process. It does not require additional high-temperature steps and has high industrial application feasibility. The vacuum annealing process (250-350°C) effectively repairs shallow lattice damage, reduces leakage current density, improves withstand voltage characteristics, avoids lattice stress accumulation, and increases device yield by 15%.

[0047] Optionally, in step S100, the FRD device voltage is greater than or equal to 1200V; and / or the thickness of the lightly doped N-layer is 60-70 μm, and the doping concentration is 6×10 13 cm -3 -8×10 13 cm -3 ; and / or, the thickness of the heavily doped N+ layer is 20-30 μm, and the doping concentration is 2×10 14 cm -3 -3×10 14 cm -3 ; and / or, the thickness of the super heavily doped N++ layer is 100-120 μm, and the doping concentration is 2×10 19 cm -3 -3×10 19 cm -3 .

[0048] In some embodiments, the lightly doped N-layer serves as the drift region, and its thickness directly determines the device's withstand voltage. For a 1200V voltage level, a thickness of 60-70μm ensures that the depletion layer extends to a sufficient depth under reverse bias to withstand high voltages without breakdown. Furthermore, the lower doping concentration widens the depletion layer, reducing the electric field strength and thus increasing the breakdown voltage. The low doping concentration also minimizes the conductivity modulation effect during forward conduction, reducing stored charge and facilitating rapid recovery, meeting the requirements of applications at 1200V and above.

[0049] In some embodiments, the heavily doped N+ layer acts as a buffer layer with a thickness of 20-30 μm, which limits the excessive expansion of the depletion layer under reverse bias, preventing it from penetrating into the highly doped N++ substrate layer and avoiding a drop in breakdown voltage. Compared with the N- layer, the higher doping concentration slows down the electric field gradient and prevents the local electric field from being too high, causing avalanche breakdown. At the same time, when conducting in the forward direction, the N+ layer provides additional carriers to reduce the forward voltage drop.

[0050] In some embodiments, the heavily doped N++ layer serves as a substrate layer, and a thickness of 100-120 μm provides mechanical support to ensure the stability of the device during manufacturing and use, while also facilitating heat conduction. The extremely high doping concentration forms a good ohmic contact with the cathode metal contact layer 60, significantly reducing the contact resistance and thereby reducing the forward voltage drop.

[0051] In the present invention application, the thickness and low doping concentration of the lightly doped N-layer ensure a withstand voltage of 1200V and above, reducing the reverse recovery time. The heavily doped N+ layer and the ultra-heavily doped N++ layer optimize the forward conduction performance and ensure fast switching characteristics. The thickness of the ultra-heavily doped N++ layer provides mechanical support and thermal conductivity, enabling the FRD device to operate efficiently and reliably in a high-frequency, high-voltage (≥1200V) environment.

[0052] Optionally, in step S200, the energy range of proton irradiation is 3.4-3.9 MeV, the proton Bragg peak is located at the contact interface between the lightly doped N- layer 30 and the heavily doped N+ layer 40, and the dose range of proton irradiation is 5×10 11 -1×10 12 p / cm 2 .

[0053] In some embodiments, the selection of the proton irradiation dose is closely related to the platinum diffusion conditions of the FRD device. When the platinum diffusion temperature is 860°C-880°C (i.e., greater than or equal to 860°C and less than 880°C), the corresponding proton irradiation dose is 5×10 11 p / cm 2 When the platinum diffusion temperature is 880℃-900℃ (i.e. greater than or equal to 880℃ and less than 900℃), the corresponding proton irradiation dose is 8×1011 p / cm 2 When the platinum diffusion temperature is 900℃-920℃ (i.e. greater than or equal to 900℃ and less than 920℃), the corresponding proton irradiation dose is 1×10 12 p / cm 2 .

[0054] In other embodiments, the selection of the proton irradiation dose is closely related to the platinum diffusion conditions of the FRD device. When the platinum diffusion temperature is 860°C-880°C (i.e., greater than or equal to 860°C and less than 880°C), the corresponding proton irradiation dose is 5×10 11 p / cm 2 For every 20°C increase in platinum diffusion temperature, the corresponding proton irradiation dose increases by 3×10 11 p / cm 2 .

[0055] In some embodiments, when protons penetrate an FRD device, their energy loss is not uniformly distributed, but instead reaches a peak at a specific depth, known as the proton Bragg peak. This location is where proton energy deposition and defect generation are most concentrated, and where the density of recombination centers is highest. By selecting a proton energy between 3.4 and 3.9 MeV, the Bragg peak can be precisely controlled to locate at the N- / N+ interface, thereby introducing localized recombination centers in this region. This design effectively shortens the reverse recovery time of the FRD device while minimizing the adverse effects on the forward voltage drop.

[0056] In some embodiments, during FRD device fabrication, the platinum diffusion process diffuses platinum atoms into silicon to introduce recombination centers, thereby reducing carrier lifetime and optimizing device switching characteristics. Proton irradiation also creates recombination centers by introducing defects, creating a synergistic effect with the platinum diffusion process. Variations in the platinum diffusion temperature affect the diffusion depth of the platinum atoms and the distribution of the recombination centers: higher temperatures lead to deeper diffusion of the platinum atoms and a wider distribution of the recombination centers. To accommodate this variation, the proton irradiation dose needs to be adjusted based on the platinum diffusion temperature.

[0057] In the present invention, firstly, by synergistically controlling the energy (3.4-3.9 MeV) and dose (5×10 11 -1×10 12 p / cm 2), the Bragg peak can be positioned at the N- / N+ interface, achieving localized regulation of the carrier lifetime and avoiding the introduction of too many defects in the entire N-layer, thereby shortening the reverse recovery time while reducing the impact on the forward conduction performance; in addition, the selection of proton irradiation dose is closely related to the platinum diffusion temperature. By matching the two, the carrier lifetime distribution can be optimized under different process conditions. The synergistic effect not only improves the stability of the FRD device performance, but also enhances the flexibility of the FRD device manufacturing process.

[0058] Optionally, in step S300 , vacuum annealing is used for the annealing process, and the annealing temperature range is 250° C.-350° C.

[0059] In some embodiments, proton irradiation can produce a variety of defects (such as point defects, cluster defects, etc.) in the silicon lattice. These defects partially act as recombination centers, reducing the carrier lifetime and thus shortening the reverse recovery time. Proton irradiation introduces unstable defects, which may cause the performance of the FRD device to degrade. The high temperature of the annealing treatment causes the unstable defects to recombine or anneal out, reducing their negative impact on the performance of the FRD device. At the same time, the recombination centers that are beneficial to the regulation of carrier lifetime are retained and activated, ensuring its stability at the operating temperature. It can also partially repair the lattice damage caused by irradiation, reduce the leakage current density, avoid the accumulation of lattice stress, and optimize the electrical properties.

[0060] In some embodiments, the selection of annealing temperature is closely related to the irradiation dose. The proton irradiation dose is 5×10 11 p / cm 2 When the annealing temperature is 250℃ and the proton irradiation dose is 8×10 11 p / cm 2 When the annealing temperature is 300℃ and the proton irradiation dose is 1×10 12 p / cm 2 The corresponding annealing temperature is 350°C. Obviously, the higher the irradiation dose, the greater the defect density, and a higher annealing temperature is required to eliminate unstable defects and stabilize recombination centers. At lower doses, 250°C is sufficient to stabilize performance; as the dose increases, higher temperatures are required to ensure defect repair and optimization.

[0061] In the present invention application, first, annealing is carried out in a vacuum environment to avoid oxidation and contamination by external impurities, protect the integrity of the surface and internal structure of the FRD device, and significantly improve reliability and service life; in addition, the temperature range of 250°C-350°C has been optimized to eliminate unstable defects while retaining sufficient recombination centers. The matching relationship between annealing temperature and irradiation dose provides flexibility in process optimization. The appropriate temperature can be selected according to different doses to ensure the performance consistency of the FRD device in long-term operation, reduce the risk of performance drift and degradation, regulate the carrier lifetime, shorten the reverse recovery time, thereby improving the switching speed of the device, and increasing the yield of FRD devices by 15%.

[0062] Those skilled in the art can understand that the various operations, methods, steps in the process, measures, and schemes discussed in the present invention application can be interchanged, changed, combined, or deleted; further, the various operations, methods, and other steps, measures, and schemes in the process discussed in the present invention application can also be interchanged, changed, rearranged, decomposed, combined, or deleted; further, the various operations, methods, and steps in the process disclosed in the present invention application in the prior art can also be interchanged, changed, rearranged, decomposed, combined, or deleted. The various technical features of the above embodiments can be arbitrarily combined. To make the description concise, not all possible combinations of the various technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification;

[0063] The embodiments described above only express several implementation methods of the embodiments of the present disclosure, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the embodiments of the present disclosure; it should be pointed out that for ordinary technicians in this field, without departing from the concept of the embodiments of the present disclosure, several variations and improvements can be made, which all fall within the protection scope of the embodiments of the present disclosure; therefore, the protection scope of the embodiments of the present disclosure should be based on the attached claims. As mentioned above, although the present invention application has been expressed and described with reference to specific preferred embodiments, it shall not be interpreted as limiting the present invention application itself. Various changes can be made to it in form and detail without departing from the spirit and scope of the present invention application defined in the attached claims.

[0064] The above description of the present invention and its embodiments is non-limiting. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if a person skilled in the art is inspired by this and, without departing from the inventive purpose of the present invention, designs structures and embodiments similar to the technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A proton irradiation treatment method for an epitaxial FRD device, characterized in that: include: Step S100: Obtaining an epitaxial structure-based FRD device, along the thickness direction of the epitaxial structure-based FRD device, the epitaxial structure-based FRD device includes: an anode metal contact layer, a P-type layer, a lightly doped N- layer, a heavily doped N+ layer, an ultra-heavily doped N++ layer, and a cathode metal contact layer, wherein the cathode metal contact layer, the ultra-heavily doped N++ layer, the heavily doped N+ layer, the lightly doped N- layer, the P-type layer, and the anode metal contact layer are stacked and connected in sequence from bottom to top; Step S200: Proton irradiating an epitaxial structure-based FRD device to obtain a proton-irradiated FRD device, wherein the proton-irradiated FRD device includes a proton-injected region, the proton-injected region is located at a contact interface between a lightly-doped N-layer and a heavily-doped N+ layer, the proton-injected region includes a first proton-injected region and a second proton-injected region, the first proton-injected region is partially located in the lightly-doped N-layer, and the second proton-injected region is partially located in the heavily-doped N+ layer; Step S300: performing annealing treatment on the proton irradiated FRD device to obtain a proton irradiated FRD device.

2. The proton irradiation treatment method for an epitaxial FRD device according to claim 1, characterized in that: In step S100, the FRD device voltage is greater than or equal to 1200V; and / or the thickness of the lightly doped N-layer is 60-70 μm, and the doping concentration is 6×10 13 cm -3 -8×10 13 cm -3 ; and / or, the thickness of the heavily doped N+ layer is 20-30 μm, and the doping concentration is 2×10 14 cm -3 -3×10 14 cm -3 and / or, the thickness of the heavily doped N++ layer is 100-120 μm, and the doping concentration is 2×10 19 cm -3 -3×10 19 cm -3 .

3. The proton irradiation treatment method for an epitaxial FRD device according to claim 2, characterized in that: In step S200, the energy range of proton irradiation is 3.4-3.9 MeV, the proton Bragg peak is located at the contact interface between the lightly doped N- layer and the heavily doped N+ layer, and the dose range of proton irradiation is 5×1011-1×1012 p / cm 2 .

4. The proton irradiation treatment method for an epitaxial FRD device according to claim 3, characterized in that: When the platinum diffusion temperature is 860℃-880℃, the proton irradiation dose is 5×10 11 p / cm 2 ; Alternatively, when the platinum diffusion temperature is 880℃-900℃, the proton irradiation dose is 8×10 11 p / cm 2 ; Alternatively, when the platinum diffusion temperature is 900℃-920℃, the proton irradiation dose is 1×10 12 p / cm 2 .

5. The proton irradiation treatment method for an epitaxial FRD device according to claim 3, characterized in that: For every 20°C increase in platinum diffusion temperature, the corresponding proton irradiation dose increases by 3×1011p / cm 2 .

6. The proton irradiation treatment method for an epitaxial FRD device according to claim 5, characterized in that: In step S300 , vacuum annealing is used for annealing, and the annealing temperature range is 250° C.-350° C.

7. The proton irradiation treatment method for an epitaxial FRD device according to claim 6, characterized in that: The proton irradiation dose was 5×10 11 p / cm 2 When the annealing temperature is 250℃; Alternatively, the proton irradiation dose is 8 × 10 11 p / cm 2 When the annealing temperature is 300℃; Alternatively, the proton irradiation dose is 1×10 12 p / cm 2 The annealing temperature is 350℃.

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