Fast recovery diode matched with IGBT (Insulated Gate Bipolar Translator) and preparation method thereof

Abstract

The embodiment of the invention provides a fast recovery diode matched with an IGBT for use and a preparation method, and relates to the technical field of semiconductors. The fast recovery diode comprises an anode region, a drift layer of a first conduction type and a cathode region which are sequentially distributed from top to bottom, a defect recombination region is arranged in a terminal region on the edge of the top of the drift layer, is a hydrogen ion injection region, and is used for capturing and compositing holes. According to the embodiment of the invention, the dynamic reliability of the FRD device is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a fast recovery diode used in combination with IGBT and a preparation method thereof. BACKGROUND

[0002] As a kind of switching device, fast recovery diode (FRD) is usually used in parallel with insulated gate bipolar transistor (IGBT) and plays a role of reverse current to protect IGBT from being damaged.

[0003] When IGBT is converted from off state to on state, FRD needs to be converted from on state to off state. But FRD cannot be turned off immediately because there are a large number of carriers in the body region when FRD is on, and the disappearance of carriers has a time effect, so FRD has a reverse recovery process.

[0004] During the reverse recovery process of FRD, the holes in the body region move under the action of the space electric field. The holes in the terminal region move along the radial direction to the active region boundary and finally gather at the active region boundary, which can cause the concentration of current and electric field at the active region boundary and easily cause dynamic avalanche, leading to the damage of FRD and further leading to the damage of IGBT. Moreover, the faster the IGBT turns on, the greater the impact of FRD turn-off, and the more likely it is to be damaged. SUMMARY

[0005] Embodiments of the present application provide a fast recovery diode used in combination with IGBT and a preparation method thereof to improve the dynamic reliability of FRD device.

[0006] In a first aspect, embodiments of the present application provide a fast recovery diode used in combination with IGBT, comprising:

[0007] An anode region, a drift layer of a first conductivity type and a cathode region are sequentially distributed from top to bottom.

[0008] A terminal region at the top edge of the drift layer is provided with a defect recombination region.

[0009] The defect recombination region is a hydrogen ion implantation region, and the defect recombination region is used to capture and recombine holes.

[0010] In a possible implementation, the defect recombination region is arranged in parallel with the upper surface of the drift layer.

[0011] In a possible implementation, the anode region includes a first conductive region of a second conductivity type and a second conductive region of the second conductivity type; the doping concentration of the second conductive region is higher than that of the first conductive region.

[0012] The defect recombination region is adjacent to the boundary of the first conductive region and is located below the second conductive region.

[0013] In a possible implementation, the first conductive type is N type and the second conductive type is P type.

[0014] In a second aspect, the embodiments of the present application provide a preparation method of a fast recovery diode, which is used for preparing the fast recovery diode used in combination with the IGBT in any one of the first aspect, and the preparation method comprises the following steps:

[0015] providing a substrate of a first conductive type;

[0016] forming an anode region, a drift layer of the first conductive type and a cathode region on the substrate to obtain the fast recovery diode;

[0017] forming a defect recombination region in a termination region of a top edge of the drift layer by a hydrogen ion implantation process when the drift layer is formed.

[0018] In a possible implementation, the forming of the defect recombination region in the termination region of the top edge of the drift layer by the hydrogen ion implantation process comprises the following steps:

[0019] In the termination region of the top edge of the drift layer, the defect recombination region is formed by multiple times of hydrogen ion implantation and low-temperature annealing through a mask blocking technology.

[0020] In a possible implementation, the number of times of hydrogen ion implantation is 3-6, the implantation energy is 500 Kev-1.5 Mev, the implantation energy is sequentially increased, and the implantation dose is 5E13 cm −2 -5E14 cm −2 .

[0021] In a possible implementation, the anode region comprises a first conductive region of a second conductive type, a second conductive region of the second conductive type and an anode metal, and the cathode region comprises the substrate of the first conductive type and a cathode metal.

[0022] The forming of the anode region, the drift layer of the first conductive type and the cathode region on the substrate comprises the following steps:

[0023] forming the drift layer of the first conductive type on an upper surface of the substrate;

[0024] forming the second conductive region and the first conductive region on the drift layer in sequence by ion implantation and high-temperature annealing;

[0025] forming the defect recombination region by hydrogen ion implantation and low-temperature annealing in a terminal region of a top edge of the drift layer;

[0026] forming the anode metal on a top surface of the drift layer;

[0027] reducing the thickness of the substrate to a preset thickness by back thinning;

[0028] forming the cathode metal on a bottom surface of the substrate.

[0029] In a possible implementation, the cathode region further comprises a buffer layer of the first conductive type;

[0030] the forming of the drift layer of the first conductive type on the top surface of the substrate comprises:

[0031] forming the buffer layer of the first conductive type and the drift layer of the first conductive type on the top surface of the substrate in sequence.

[0032] In a possible implementation, the fast recovery diode further comprises a stop ring of the first conductive type and a dielectric layer;

[0033] the forming of the second conductive region and the first conductive region on the drift layer by ion implantation and high-temperature annealing in sequence comprises:

[0034] the forming of the second conductive region, the first conductive region and the stop ring of the first conductive type on the drift layer by ion implantation and high-temperature annealing in sequence;

[0035] after the forming of the second conductive region and the first conductive region on the drift layer by ion implantation and high-temperature annealing in sequence, the method further comprises:

[0036] forming the dielectric layer on a top surface of the drift layer;

[0037] the forming of the anode metal on the top surface of the drift layer comprises:

[0038] the forming of the anode metal on the dielectric layer by metal sputtering or evaporation.

[0039] The fast recovery diode for IGBT and the preparation method provided by the embodiments of the present application form a defect recombination region in a terminal region of a top edge of a drift layer of the FRD by hydrogen ion implantation, in the reverse recovery stage of the FRD, holes will first pass through the defect recombination region before reaching the boundary of the anode region, and the holes will be trapped by defects and recombined when passing through the defect recombination region, thereby reducing the concentration of current and electric field at the boundary of the anode region and improving the dynamic reliability of the FRD device. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0041] Figure 1 A schematic diagram showing a current variation curve of an FRD;

[0042] Figure 2 A schematic structural diagram of a fast recovery diode is shown;

[0043] Figure 3 shows a structural schematic diagram of another fast recovery diode;

[0044] Figure 4 A schematic structural diagram of another fast recovery diode is shown;

[0045] Figure 5 A schematic flow chart of a method for preparing a fast recovery diode is shown;

[0046] Figure 6 A schematic diagram showing a process for preparing a fast recovery diode is shown;

[0047] Figure 7 A schematic diagram showing hole movement in a fast recovery diode during reverse recovery is shown.

[0048] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0049] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present application, as detailed in the appended claims.

[0050] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0051] Insulated Gate Bipolar Transistor (IGBT): is a composite full-controlled voltage-driven power semiconductor device composed of bipolar transistor and insulated gate field effect transistor, which has the advantages of high input impedance of insulated gate field effect transistor and low on-state voltage drop of power transistor.

[0052] FRD as a switching device, IGBT is used in parallel, play a reverse current to protect IGBT from being damaged.

[0053] Figure 1 A schematic diagram showing the current change curve of FRD is shown. In which, the horizontal axis of the current change curve is time (t), and the vertical axis is the forward current (I F ).

[0054] Referring to Figure 1 , the large current platform of the initial part of the curve corresponds to the forward conduction stage. Under the condition of forward bias, FRD is in the on state, and the forward current is maintained at a relatively stable high value.

[0055] Referring to Figure 1 , in the initial stage of reverse bias, when the applied voltage suddenly changes from forward bias to reverse bias, due to the existence of a large number of injected carriers in the body region of FRD, FRD cannot be immediately cut off, but will continue to conduct for a period of time. At this time, the reverse voltage is applied to the FRD, and the carriers in the body region are extracted under the action of the reverse electric field, forming a reverse recovery current. The direction of the reverse recovery current is opposite to that of the forward current, and its size rapidly rises, which is manifested in Figure 1 as the current rapidly decreases from the forward current platform to zero.

[0056] Referring to Figure 1 , in the peak stage of reverse recovery current, with the continuous action of the reverse voltage, more carriers are extracted, and the reverse recovery current gradually increases and reaches a peak. In Figure 1 , the current drops to the lowest point, which is the peak stage of the reverse recovery current.

[0057] Referring to Figure 1 , in the reverse recovery stage, after the reverse recovery current reaches the peak, the carrier concentration in the body region gradually decreases, and the reverse recovery current begins to decrease. In this process, the reverse voltage across the FRD still exists, and the remaining carriers continue to be extracted. The falling speed of the reverse recovery current is represented by dI F / dt, from Figure 1 , it can be seen that the reverse recovery current gradually approaches zero from the peak, and the absolute value of dI F / dt reflects the speed of current drop.

[0058] With reference to the foregoing Figure 1 In the reverse blocking phase, when the carriers in the body region are substantially extracted, the reverse recovery current decreases to a very small value, and the FRD enters the reverse blocking state. At this time, the FRD can withstand a reverse voltage, and only a very small reverse leakage current flows through it. In the reverse recovery process Figure 1 , the current finally approaches zero, indicating that the reverse recovery process is substantially complete, and the FRD returns to the reverse blocking state.

[0059] In the scenario where the FRD is used in combination with the IGBT, when the IGBT is switched from the off state to the on state, the FRD needs to be switched from the on state to the off state. However, according to the foregoing Figure 1 and related descriptions, the FRD cannot be immediately turned off, but there is a reverse recovery process.

[0060] During the reverse recovery process of the FRD, the holes in the body region move under the action of the space electric field. The holes in the terminal region move along the radial direction to the active region boundary and finally gather at the active region boundary. This situation can cause the concentration of the current and the electric field at the active region boundary, and is prone to cause dynamic avalanche, thereby causing damage to the FRD and further causing damage to the IGBT. Moreover, the faster the IGBT is turned on, the greater the impact of the FRD on the off state, and the more prone to damage.

[0061] Based on this, the embodiment of the present application provides a fast recovery diode used in combination with an IGBT and a preparation method, to solve the foregoing technical problems.

[0062] The fast recovery diode used in combination with an IGBT and the preparation method provided by the embodiment of the present application form a defect recombination region in the terminal region at the top edge of the drift layer of the first conduction type by means of hydrogen ion implantation. During the reverse recovery phase of the FRD, the holes will first pass through the defect recombination region before reaching the active region boundary, and the holes will be trapped and recombined when passing through the defect recombination region, thereby reducing the concentration of the current and the electric field at the active region boundary, improving the dynamic reliability of the FRD device, and especially in the scenario of high-frequency application.

[0063] The FRD provided by the embodiment of the present application can be used in combination with the IGBT, or can also be used in combination with other semiconductor devices, which are not limited by the embodiment of the present application. For example, it can also be used in combination with Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), Gate Turn-Off Thyristor (GTO), power module, inverter, motor driver and other devices.

[0064] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described again in some embodiments. The embodiments of the present application will be described below with reference to the drawings.

[0065] Figure 2 A structure diagram of a fast recovery diode is shown. Referring to Figure 2 , the FRD includes, from top to bottom, an anode region 10, a drift layer 20 of a first conductivity type, and a cathode region 30;

[0066] A termination region at the top edge of the drift layer 20 is provided with a defect recombination region 40.

[0067] The defect recombination region 40 is a hydrogen ion implantation region, and the defect recombination region 40 is used to trap and recombine holes.

[0068] From the vertical direction, from top to bottom, are the anode region 10, the drift layer 20 of the first conductivity type, and the cathode region 30. This structure allows electrons to be injected from the cathode region 30 to the drift layer 20 of the first conductivity type when the FRD is turned on, and then move to the anode region 10; holes are injected from the anode region 10 to the drift layer 20 of the first conductivity type, and then move to the cathode region 30, forming current conduction.

[0069] The FRD provided by the embodiments of the present application is provided with the defect recombination region 40 at the termination region at the top edge of the drift layer 20 of the first conductivity type. During the reverse recovery phase of the FRD, holes will pass through the defect recombination region 40 before reaching the junction boundary, and the holes will be trapped and recombined by defects when passing through the defect recombination region 40, thereby reducing the concentration of current and electric field at the junction boundary and improving the dynamic reliability of the FRD.

[0070] The anode region 10 is located at the top of the FRD. In some embodiments, the anode region 10 includes a first conductive region 101 of a second conductivity type, a second conductive region 102 of the second conductivity type, and an anode metal 103. The doping concentration of the second conductive region 102 is higher than that of the first conductive region 101, that is, the first conductive region 101 is a lightly doped region, and the second conductive region 102 is a heavily doped region. The anode metal 103 is used to connect with an external circuit.

[0071] Optionally, the defect recombination region 40 is adjacent to the boundary of the first conductive region 101 and is located below the second conductive region 102. By setting the defect recombination region 40 adjacent to the boundary of the first conductive region 101, holes moving to the boundary of the first conductive region 101 can be trapped and recombined by the defect recombination region 40 during the reverse recovery phase of the FRD.

[0072] Optionally, the defect recombination zone 40 may slightly overlap with the boundary of the first conductive region 101 .

[0073] The drift layer 20 is located between the anode region 10 and the cathode region 30. When the FRD is in the reverse blocking state, the drift layer 20 bears the majority of the voltage. The thickness and doping concentration of the drift layer 20 affect the FRD's voltage resistance and can be set based on actual needs. This is not limited in the present embodiment. Optionally, the doping concentration of the drift layer 20 can be set higher, that is, the drift layer 20 is a heavily doped region.

[0074] Optionally, the defect recombination region 40 is arranged parallel to the upper surface of the drift layer 20. This arrangement allows holes in the reverse recovery phase to be more evenly distributed and close to the defect recombination region 40, thereby increasing the chance of interaction with defects and improving recombination efficiency.

[0075] Optionally, the defect recombination region 40 is formed by multiple hydrogen ion implantations followed by low-temperature annealing. This combined process of multiple implantations and annealing can better balance the recombination capability of the defect recombination region 40 and its impact on other FRD properties. Each implantation creates a layer of defects, resulting in multiple layers of defects.

[0076] For ease of understanding, Figure 3 Figure 2 shows a schematic diagram of another fast recovery diode. Figure 3 The three hydrogen ion implantations form three layers of defects, which together constitute a defect recombination region 40. By controlling the implantation energy and dose, the position of the defects can be adjusted so that the multiple layers of defects merge together to form a complete defect recombination region 40.

[0077] Figure 2 The shape of the defect recombination zone 40 is represented by a rectangle. It can be understood that Figure 2 This is only an exemplary description, and the present application does not limit the shape of the defect recombination zone 40 .

[0078] The cathode region 30 is located at the bottom of the FRD. In some embodiments, the cathode region 30 includes a substrate 301 of the first conductivity type, a buffer layer 302 of the first conductivity type, and a cathode metal 303. Substrate 301 is a heavily doped region that provides an outflow channel for electrons. Cathode metal 303 is used to connect to an external circuit.

[0079] Optionally, the first conductivity type is N-type, and the second conductivity type is P-type. The N-type dopant ions may be phosphorus or nitrogen ions, and the P-type dopant ions may be aluminum ions or boron ions. Accordingly, the first conductive region 101 is a P- region, the second conductive region 102 is a P+ region, and the drift layer 20 is an N+ drift layer.

[0080] In some embodiments, the FRD further includes a first conductivity type cutoff ring 50. The cutoff ring 50 is used to prevent premature breakdown at the FRD edge and acts as an electric field cutoff. The cutoff ring 50 is a heavily doped region. Exemplarily, the cutoff ring 50 is an N+ cutoff ring.

[0081] In some embodiments, the FRD further includes a dielectric layer 60. The dielectric layer 60 is used for insulation and isolation.

[0082] Based on the above embodiments, Figure 4 FIG1 shows a schematic diagram of the structure of another fast recovery diode. Figure 4 The FRD includes a first conductive region 101 of the second conductivity type, a second conductive region 102 of the second conductivity type, an anode metal 103, a dielectric layer 60, a stop ring 50, a drift layer 20 of the first conductivity type, a buffer layer 302 of the first conductivity type, a substrate 301 of the first conductivity type, a cathode metal 303, and a defect recombination zone 40. The defect recombination zone 40 is located below the right boundary of the first conductive region 101 and below the second conductive region 102 and the stop ring 50.

[0083] Based on the above embodiment, the present invention further provides a method for preparing a fast recovery diode, which comprises:

[0084] Providing a substrate 301 of a first conductivity type;

[0085] An anode region 10, a drift layer 20 of a first conductivity type, and a cathode region 30 are formed on a substrate to manufacture a fast recovery diode 10;

[0086] When forming the drift layer 20 , a defect recombination region 40 is formed in a terminal region at the top edge of the drift layer 20 by a hydrogen ion implantation process.

[0087] In some embodiments, multiple hydrogen ion implantations and low-temperature annealing are performed in the termination region at the top edge of the drift layer 20 using a mask blocking technique to form a defect recombination region 40 .

[0088] When hydrogen ions are implanted into the drift layer 20 , the high-energy hydrogen ions collide with atoms in the lattice of the drift layer 20 , destroying the integrity of the lattice and thereby generating a large number of lattice defects in the implanted region.

[0089] On the one hand, low-temperature annealing can partially repair the lattice structure damaged by hydrogen ion implantation, reducing unnecessary deep-level defects. On the other hand, the annealing process causes hydrogen atoms to diffuse and redistribute within the drift layer 20. Hydrogen atoms can combine with some defects to form more stable composite defect structures. These composite defects can serve as effective carrier recombination centers.

[0090] The mask blocking technique can precisely control the region of hydrogen ion implantation. In practical application, a suitable mask pattern can be designed to implant hydrogen ions only in the termination region of the top edge of the drift layer 20, and avoid introducing defects in other unwanted regions. In this way, the defect recombination region 40 can be accurately formed at a specific location.

[0091] Multiple hydrogen ion implantation can more accurately control the concentration and distribution of defects. The dose, energy and other parameters of each implantation can be adjusted as needed to form different types and densities of defect structures in the defect recombination region 40.

[0092] Optionally, the number of hydrogen ion implantations is 3-6. The implantation energy of each time is 500Kev-1.5Mev, and the implantation energy of each time is increased in turn. The implantation dose of each time is 5E13cm −2 -5E14cm −2 .

[0093] Low-temperature annealing is performed after each implantation, which can gradually optimize the state of defects, so that the finally formed defect recombination region 40 has better carrier recombination performance.

[0094] Optionally, the specific preparation process of forming the anode region 10, the drift layer 20 of the first conductivity type and the cathode region 30 on the substrate 301 includes:

[0095] Forming the drift layer 20 of the first conductivity type on the upper surface of the substrate 301;

[0096] Forming the second conductive region 102 and the first conductive region 101 on the drift layer 20 by ion implantation and high-temperature annealing;

[0097] Forming the defect recombination region 40 in the termination region of the top edge of the drift layer 20 by hydrogen ion implantation and low-temperature annealing;

[0098] Forming the anode metal 103 on the upper surface of the drift layer 20;

[0099] Reducing the thickness of the substrate 301 to a predetermined thickness by back thinning;

[0100] Forming the cathode metal 303 on the lower surface of the substrate 301.

[0101] Among them, when the second conductive region 102 and the first conductive region 101 are formed in turn, the implanted ions can be boron ions.

[0102] Optionally, the cathode region 30 also includes a first conductive type buffer layer 302; accordingly, the preparation operation of forming the first conductive type drift layer 20 on the upper surface of the substrate 301 is specifically implemented as follows: forming the first conductive type buffer layer 302 and the first conductive type drift layer 20 in sequence on the upper surface of the substrate 301.

[0103] Optionally, the FRD also includes a cutoff ring 50 of the first conductive type; accordingly, the preparation operation of sequentially forming the second conductive region 102 and the first conductive region 101 in the drift layer 20 by ion implantation and high-temperature annealing is specifically implemented as follows: sequentially forming the second conductive region 102, the first conductive region 101 and the cutoff ring 50 of the first conductive type in the drift layer 20 by ion implantation and high-temperature annealing.

[0104] Optionally, the FRD further includes a dielectric layer 60. After the drift layer 20 is fabricated by sequentially forming the second conductive region 102 and the first conductive region 101 through ion implantation and high-temperature annealing, the process further includes forming the dielectric layer 60 on the upper surface of the drift layer 20. Accordingly, the process of forming the anode metal 103 on the upper surface of the drift layer 20 is specifically implemented by forming the anode metal 103 on the dielectric layer 60 through metal sputtering or evaporation.

[0105] The following combination Figure 5 and Figure 6 The method for preparing the fast recovery diode provided in the embodiment of the present application is exemplified. Figure 5 A schematic flow chart of a method for preparing a fast recovery diode is shown. Figure 6 A schematic diagram showing the preparation process of a fast recovery diode is shown in FIG. Figure 5 , the preparation method comprises the following steps:

[0106] S501 , providing a substrate 301 of a first conductivity type.

[0107] S502 , sequentially forming a first conductivity type buffer layer 302 and a first conductivity type drift layer 20 on the upper surface of the substrate 301 .

[0108] See also Figure 6 After steps S501 and S502, structure 1 is obtained.

[0109] S503 , forming the second conductive region 102 , the first conductive region 101 and the first conductive type stop ring 50 in sequence in the drift layer 20 by ion implantation and high temperature annealing.

[0110] See also Figure 6 Based on structure one, structure two is obtained through step S503.

[0111] S504, forming a dielectric layer 60 on the upper surface of the drift layer 20.

[0112] Referring to Figure 6 On the basis of structure two, structure three is prepared through step S504.

[0113] S505, forming a defect recombination region 40 on the terminal area of the top edge of the drift layer 20 by hydrogen ion implantation and low-temperature annealing.

[0114] Referring to Figure 6 On the basis of structure three, structure four is prepared through step S505.

[0115] It should be noted that Figure 6 The defect recombination region 40 shown is exemplified by three layers of defects.

[0116] S506, forming an anode metal 103 on the dielectric layer 60 by metal sputtering or evaporation.

[0117] Referring to Figure 6 On the basis of structure four, structure five is prepared through step S506.

[0118] S507, reducing the thickness of the substrate 301 to a predetermined thickness by back thinning.

[0119] S508, forming a cathode metal 303 on the lower surface of the substrate 301.

[0120] Referring to Figure 7 On the basis of structure five, structure six is prepared through steps S507-S508, and structure six is the final prepared FRD.

[0121] On the basis of the above embodiment, Figure 7 A schematic diagram of hole movement in a fast recovery diode during reverse recovery is shown. Referring to ​ During reverse recovery of the FRD, the holes in the body region move to the front surface under the action of the space electric field and are extracted, and the holes in the active region range move substantially perpendicular to the surface of the FRD body, and the hole current and electric field distribution are relatively uniform. However, the holes on the two sides of the terminal region move along the radial direction to the active region boundary due to the curvature effect of the space electric field at the active region boundary. By introducing the defect recombination region 40 in the FRD, the holes will first pass through the defect recombination region 40 before reaching the active region boundary, and the holes will be trapped and recombined when passing through the defect recombination region 40, thereby reducing the concentration of current and electric field at the active region boundary and improving the dynamic reliability of the FRD.

[0122] It should be understood that many of the materials and devices exemplified in this disclosure are articles of manufacture (i.e., articles of manufacture) according to this disclosure. The articles of manufacture can be manufactured as such or can be manufactured by combining the materials and devices exemplified in this disclosure. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It should be understood that, in some embodiments, equivalents to the specific electrode structures and / or methods described herein can be employed without departing from the scope of the application. Accordingly, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," "characterized by," "characterized into," and variations thereof herein, is meant to encompass the items listed thereafter, and equivalents thereof as well as additional items. Although the foregoing application has been described in some detail by way of illustration and example, it is not to be limited thereby, but rather, only by the scope of the appended claims.

Claims

1. A fast recovery diode used with an IGBT, characterized in that: include: An anode region, a drift layer of the first conductivity type, and a cathode region are sequentially distributed from top to bottom; A defect recombination zone is provided in the terminal area at the top edge of the drift layer; The defect recombination region is a hydrogen ion implantation region, and the defect recombination region is used to capture and recombine holes.

2. The fast recovery diode according to claim 1, characterized in that: The defect recombination region is arranged parallel to the upper surface of the drift layer.

3. The fast recovery diode according to claim 1, characterized in that: The anode region includes a first conductive region of a second conductive type and a second conductive region of the second conductive type; the doping concentration of the second conductive region is higher than that of the first conductive region; The defect recombination region is adjacent to a boundary of the first conductive region and is located below the second conductive region.

4. The fast recovery diode according to claim 3, characterized in that: The first conductivity type is N-type, and the second conductivity type is P-type.

5. A method for preparing a fast recovery diode, characterized in that: A method for preparing a fast recovery diode for use with an IGBT according to any one of claims 1 to 4, comprising: providing a substrate of a first conductivity type; forming an anode region, a drift layer of a first conductivity type, and a cathode region on the substrate to produce the fast recovery diode; When forming the drift layer, a defect recombination zone is formed in a terminal region at the top edge of the drift layer by a hydrogen ion implantation process.

6. The preparation method according to claim 5, characterized in that The forming of a defect recombination zone in the terminal region at the top edge of the drift layer by a hydrogen ion implantation process comprises: In the terminal area at the top edge of the drift layer, multiple hydrogen ion implantations and low-temperature annealing are performed through mask blocking technology to form the defect recombination area.

7. The preparation method according to claim 5, characterized in that The number of hydrogen ion implantations is 3 to 6 times, the implantation energy is 500Kev~1.5Mev, the implantation energy increases successively, and the implantation dose is 5E13cm −2 ~5E14cm −2 .

8. The preparation method according to claim 5, characterized in that The anode region includes a first conductive region of the second conductive type, a second conductive region of the second conductive type, and an anode metal, and the cathode region includes a substrate of the first conductive type and a cathode metal; The step of forming an anode region, a drift layer of a first conductivity type, and a cathode region on the substrate comprises: forming a drift layer of the first conductivity type on the upper surface of the substrate; sequentially forming the second conductive region and the first conductive region in the drift layer by ion implantation and high temperature annealing; forming the defect recombination region in the terminal region at the top edge of the drift layer by hydrogen ion implantation and low temperature annealing; forming the anode metal on the upper surface of the drift layer; Reducing the thickness of the substrate to a predetermined thickness by backside thinning; The cathode metal is formed on the lower surface of the substrate.

9. The preparation method according to claim 8, characterized in that The cathode region further includes a buffer layer of the first conductivity type; The step of forming a drift layer of the first conductive type on the upper surface of the substrate includes: A buffer layer of the first conductivity type and a drift layer of the first conductivity type are sequentially formed on the upper surface of the substrate.

10. The preparation method according to claim 8, characterized in that The fast recovery diode further includes a cutoff ring and a dielectric layer of the first conductivity type; The step of sequentially forming the second conductive region and the first conductive region in the drift layer by ion implantation and high-temperature annealing comprises: forming the second conductive region, the first conductive region and a cutoff ring of the first conductivity type in sequence in the drift layer by ion implantation and high temperature annealing; After the second conductive region and the first conductive region are sequentially formed in the drift layer by ion implantation and high-temperature annealing, the method further includes: forming the dielectric layer on the upper surface of the drift layer; The forming of the anode metal on the upper surface of the drift layer includes: The anode metal is formed on the dielectric layer by metal sputtering or evaporation.

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