Novel reverse conducting IGBT (Insulated Gate Bipolar Translator) device and preparation method thereof

Abstract

The invention relates to a novel reverse conducting IGBT device and a preparation method in the technical field of semiconductors. The novel reverse conducting IGBT device comprises a first anode structure; the second anode structure and the first anode structure are located on the same surface, and the second anode structure and the first anode structure are connected through the N-type drift layer; the drift region structure is arranged on the first anode structure and the second anode structure, the drift region structure and the second anode structure form a first PN junction barrier, and the drift region structure and the first anode structure form a second PN junction barrier; the gate structure is arranged on the surface, deviating from the first anode structure, of the drift region structure; and the cathode structure is arranged on the gate structure, so that the problem of wrong current division caused by a rebound phenomenon when the device is transited from a single-pole working mode to a double-pole working mode is solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a novel reverse-conducting IGBT device and a preparation method thereof. Background Art

[0002] IGBT is the abbreviation of insulated gate bipolar transistor, which is a voltage-controlled power semiconductor device used in high-frequency and high-voltage applications. It can be used in DC-DC conversion, AC-DC conversion, motor control, inverters, electric vehicles and other fields.

[0003] When a traditional IGBT device is subjected to reverse voltage, the collector is reverse biased and cannot be turned on. Therefore, when driving a resistive and inductive load, a diode needs to be connected in anti-parallel to conduct the reverse current and prevent the device from being broken down. Therefore, in the actual market, a single-tube IGBT chip is usually connected in anti-parallel with a fast recovery diode FRD chip and packaged together, but this method is expensive and has large parasitic parameters. The reverse-conducting IGBT device integrates a diode structure in the IGBT chip by introducing an N+ region in the anode area of ​​the IGBT, so there is no need for an additional anti-parallel diode chip. The structure of the reverse-conducting IGBT saves chip area and testing costs, thereby reducing chip costs. In addition, compared with traditional IGBTs, reverse-conducting IGBTs have smaller parasitic parameters and better temperature uniformity, as well as good soft shutdown characteristics and power cycling capabilities.

[0004] However, due to the introduction of the anode N+ region, the PN junction of the anode P+ / N- buffer layer of the reverse-conducting IGBT cannot be turned on in the low current mode, so the conductivity modulation effect cannot be introduced, and the device works in the unipolar mode. As the current increases, the voltage drop at the anode P+ / N- buffer junction increases, prompting the anode P+ / N- buffer junction to turn on, injecting holes into the N- drift region, reducing the device resistance, and entering the bipolar conduction mode; however, when the device transitions from the unipolar working mode to the bipolar mode, there will be a negative resistance region, which is the rebound phenomenon, and the rebound phenomenon may cause the current misdivision of the device when working in parallel, resulting in uneven current distribution of each parallel device causing device damage, so how to eliminate the rebound problem under short cells needs to be solved urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a novel reverse-conducting IGBT device and a preparation method thereof, which solves the current misdivision problem caused by the rebound phenomenon that occurs when the device transitions from a unipolar working mode to a bipolar working mode.

[0006] In order to solve the above technical problems, the present invention is solved by the following technical solutions:

[0007] A novel reverse conducting IGBT device, comprising:

[0008] a first anode structure;

[0009] A second anode structure, wherein the second anode structure and the first anode structure are located on the same surface, and the second anode structure and the first anode structure are connected via an N-type drift layer;

[0010] A drift region structure, wherein the drift region structure is disposed on the first anode structure and the second anode structure, the drift region structure and the second anode structure form a first PN junction barrier, and the drift region structure and the first anode structure form a second PN junction barrier;

[0011] A gate structure, wherein the gate structure is disposed on a surface of the drift region structure away from the first anode structure;

[0012] A cathode structure is disposed on the gate structure.

[0013] Optionally, when in the initial forward conduction stage, the first PN junction barrier blocks the flow path of electrons, and the device is in a unipolar working mode;

[0014] When in the low-voltage forward conduction stage, the first PN junction potential barrier decreases, and the unipolar working mode of the device is weakened;

[0015] When in the high-voltage forward conduction stage, the second PN junction barrier is turned on, and the device enters a bipolar operation mode.

[0016] Optionally, the second anode structure is located on one side of the first anode structure;

[0017] Alternatively, the second anode structure is located on both sides of the first anode structure, and the second anode structure on one side or both sides is located on the same surface as the first anode structure and is connected via an N-type drift layer.

[0018] Optionally, the second anode structure includes a first P-type anode region and a Schottky anode, and the Schottky anode is arranged on a surface of the first P-type anode region away from the drift region structure.

[0019] Optionally, the doping concentration of the first P-type anode region is 4×10 15 cm -3 ~6×10 15 cm -3 , the metal work function of the Schottky anode is 3.0 eV~4.2 eV.

[0020] Optionally, the first anode structure includes a second P-type anode region and an anode electrode, the anode electrode is arranged on a surface of the second P-type anode region away from the drift region structure, and the doping concentration of the second P-type anode region is 1×10 18 cm -3 ~1×1020 cm -3 .

[0021] Optionally, the drift region structure includes an N-type drift layer and an N-type buffer layer, wherein the N-type drift layer is disposed on a surface of the N-type buffer layer away from the first anode structure and the second anode structure, and the doping concentration of the N-type drift layer is 7.7×10 13 cm -3 ~1×10 15 cm -3 The doping concentration of the N-type buffer layer is 5×10 15 cm -3 ~1×10 17 cm -3 .

[0022] Optionally, the gate structure includes a gate electrode, a gate oxide layer, a polysilicon gate and a P-type base region, the polysilicon gate is arranged through the P-type base region, the gate oxide layer is formed on the side wall of the polysilicon gate, the gate electrode is arranged on the surface of the polysilicon gate away from the drift region structure, and the doping concentration of the P-type base region is 8×10 15 cm -3 ~1×10 17 cm -3 The doping concentration of the polysilicon gate is 1×10 20 cm -3 ~5×10 21 cm -3 , the thickness of the gate oxide layer is 0.1 μm~0.5 μm.

[0023] Optionally, the cathode structure includes a cathode electrode, a P-type cathode region and an N-type cathode region, the sidewall of the P-type cathode region is in contact with the sidewall of the N-type cathode region, and the P-type cathode region and the N-type cathode region are located on the same surface, the sidewall of the N-type cathode region is also in contact with the sidewall of the gate oxide layer, the cathode electrode is in contact with both the P-type cathode region and the N-type cathode region, and the doping concentration of the P-type cathode region is 1×10 18 cm -3 ~1×10 20 cm -3 The doping concentration of the N-type cathode region is 1×10 19 cm -3 ~1×10 20 cm -3 .

[0024] A method for preparing a novel reverse-conducting IGBT device, wherein the method is used to prepare the novel reverse-conducting IGBT device described in any one of the above.

[0025] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0026] By introducing the second anode structure into the first anode structure and utilizing the first PN junction barrier formed by the second anode structure and the drift region structure, the rebound phenomenon of the traditional structure under short cells is eliminated during the forward conduction stage of the device. In the reverse conduction stage, a large amount of electron conduction introduced by the work function difference between the first P-type anode region and the Schottky anode in the second anode structure is utilized to ensure the reverse conduction capability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 paying creative labor.

[0028] Figure 1 This is one of the schematic diagrams of the cell structure of the novel reverse-conducting IGBT device proposed in the first embodiment;

[0029] Figure 2 This is the second schematic diagram of the cell structure of the novel reverse-conducting IGBT device proposed in the first embodiment;

[0030] Figure 3 A schematic diagram of the cell structure of a conventional reverse-conducting IGBT device proposed in the first embodiment;

[0031] Figure 4 This is a schematic diagram of the working principle of the novel reverse-conducting IGBT device proposed in the first embodiment under three forward conduction voltages;

[0032] Figure 5 A line graph showing the change of the conduction band energy of the first P-type anode region with the forward voltage when the first embodiment is forwardly conducting;

[0033] Figure 6 This is an energy band diagram of the first P-type anode region during reverse initial conduction when the Schottky anode has a different metal work function as proposed in the first embodiment;

[0034] Figure 7 A comparison diagram of forward conduction characteristics between the novel reverse conducting IGBT device proposed in the first embodiment and the conventional reverse conducting IGBT device;

[0035] Figure 8 A comparison diagram of reverse conduction characteristics between the novel reverse conducting IGBT device proposed in the first embodiment and the conventional reverse conducting IGBT device;

[0036] Fig. 9 This is a diagram of the conduction performance of the novel reverse-conducting IGBT device proposed in the first embodiment at different doping concentrations in the first P-type anode region;

[0037] Fig.10 This is a reverse conduction voltage drop diagram of the novel reverse conducting IGBT device proposed in the first embodiment under different metal work functions;

[0038] Fig.11 This is a schematic diagram of the cell structure of the novel reverse-conducting IGBT device proposed in the second embodiment.

[0039] Figure numerals: 1. first P-type anode region; 2. Schottky anode; 3. second P-type anode region; 4. anode electrode; 5. N-type drift layer; 6. N-type buffer layer; 7. gate electrode; 8. gate oxide layer; 9. polysilicon gate; 10. P-type base region; 11. cathode electrode; 12. P-type cathode region; 13. N-type cathode region; 14. first anode structure; 15. second anode structure; 16. drift region structure; 17. gate structure; 18. cathode structure; 19. N-type anode region. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below in conjunction with embodiments. The following embodiments are for explanation of the present invention but the present invention is not limited to the following embodiments.

[0041] Embodiment 1

[0042] like Figure 1 As shown, a novel reverse conducting IGBT device includes a first anode structure 14, a second anode structure 15, a drift region structure 16, a gate structure 17 and a cathode structure 18, wherein the second anode structure 15 and the first anode structure 14 are located on the same surface, and the second anode structure 15 and the first anode structure 14 are connected through an N-type drift layer 5, the drift region structure 16 is arranged on the first anode structure 14 and the second anode structure 15, the drift region structure 16 and the second anode structure 15 form a first PN junction barrier, the drift region structure 16 and the first anode structure 14 form a second PN junction barrier, the gate structure 17 is arranged on the surface of the drift region structure 16 away from the first anode structure 14, and the cathode structure 18 is arranged on the gate structure 17.

[0043] The second anode structure 15 is located on one side of the first anode structure 14, and the second anode structure 15 and the first anode structure 14 are located on the same surface and are connected through the low-doped N-type drift layer 5. Specifically, Figure 2 As shown, the second anode structure 15 includes a lightly doped first P-type anode region 1 and a Schottky anode 2. The Schottky anode 2 is arranged on the surface of the first P-type anode region 1 away from the drift region structure 16. The doping concentration of the first P-type anode region 1 is 4×10 15cm -3 ~6×10 15 cm -3 , the metal work function of the Schottky anode 2 is 3.0 eV~4.2 eV.

[0044] The first anode structure 14 includes a heavily doped second P-type anode region 3 and an anode electrode 4. The anode electrode 4 is disposed on the surface of the second P-type anode region 3 away from the drift region structure 16. In order to obtain a good ohmic contact, the doping concentration of the second P-type anode region 3 is set to 1×10 18 cm -3 ~1×10 20 cm -3 The first P-type anode region 1 and the second P-type anode region 3 are connected through a low-doped N-type drift layer 5, and the first P-type anode region 1, the second P-type anode region 3, and the N-type drift layer 5 are located on the same surface, and the Schottky anode 2 and the anode electrode 4 are not arranged in contact.

[0045] like Figure 3 As shown, it is a structural diagram of a conventional reverse conducting IGBT device, including an anode structure, a drift region structure 16, a gate structure 17 and a cathode structure 18. Since the anode structure of the conventional reverse conducting IGBT device includes a heavily doped N-type anode region 19, a heavily doped second P-type anode region 3 and an anode electrode 4, when the length LA of the second P-type anode region 3 of the conventional reverse conducting IGBT device is short, the device will have a large snap-back voltage, which will have an adverse effect on the parallel operation of the device. For this reason, the length LA of the second P-type anode region 3 needs to be designed to be long enough. However, if the length of the second P-type anode region 3 is too long to generate a snap-back voltage, the temperature and dynamic carrier uniformity of the device will become poor, thereby affecting the robustness of the device. Therefore, compared with the conventional reverse conducting IGBT device, the present embodiment provides a second anode structure 15 composed of a first P-type anode region 1 and a Schottky anode 2, and is connected to the first anode structure 14 through an N-type drift layer 5, thereby eliminating the snap-back phenomenon.

[0046] Furthermore, if Figure 1 and Figure 2 As shown, the gate structure 17 includes a gate electrode 7, a gate oxide layer 8, a polysilicon gate 9 and a low-doped P-type base region 10. The polysilicon gate 9 is arranged through the P-type base region 10, and multiple groups of polysilicon gates 9 are arranged. The multiple groups of polysilicon gates 9 are arranged at intervals. The gate oxide layer 8 is formed on the side wall of the polysilicon gate 9. The thickness of the gate oxide layer 8 is 0.1μm~0.5μm. The gate electrode 7 is arranged on the surface of the polysilicon gate 9 away from the drift region structure 16. In order to improve the conductivity, the doping concentration of the polysilicon gate 9 in this embodiment is set to 1×10 20 cm -3 ~5×10 21 cm-3 , the preferred setting is 1×10 20 cm -3 In order to set the device threshold voltage to a reasonable range, the doping concentration of the P-type base region 10 is set to 8×10 15 cm -3 ~1×10 17 cm -3 , the preferred setting is 1×10 16 cm -3 .

[0047] The cathode structure 18 includes a cathode electrode 11, a heavily doped P-type cathode region 12, and a heavily doped N-type cathode region 13. The sidewall of the P-type cathode region 12 is in contact with the sidewall of the N-type cathode region 13, and the P-type cathode region 12 and the N-type cathode region 13 are located on the same surface. The sidewall of the N-type cathode region 13 is also in contact with the sidewall of the gate oxide layer 8. The surfaces of the P-type cathode region 12 and the N-type cathode region 13 near the drift region structure 16 are also in contact with the P-type base region 10. The cathode electrode 11 is in contact with both the P-type cathode region 12 and the N-type cathode region 13. In order to form a good ohmic contact electrode, the doping concentration of the P-type cathode region 12 is set to 1×10 18 cm -3 ~1×10 20 cm -3 , preferably set to 1×10 20 cm -3 , the doping concentration of the N-type cathode region 13 is set to 1×10 19 cm -3 ~1×10 20 cm -3 , preferably set to 1×10 20 cm -3 .

[0048] The drift region structure 16 includes a low-doped N-type drift layer 5 and a low-doped N-type buffer layer 6. The N-type drift layer 5 is disposed on the surface of the N-type buffer layer 6 away from the first anode structure 14 and the second anode structure 15, and the surface of the N-type drift layer 5 away from the N-type buffer layer 6 is in contact with the P-type base region 10 and the gate oxide layer 8. In order to maintain the withstand voltage of the device, the doping concentration of the N-type drift layer 5 is set to 7.7×10 13 cm -3 ~1×10 15 cm -3 , the preferred setting is 1×10 14 cm -3 , the doping concentration of the N-type buffer layer 6 is 5×10 15 cm -3 ~1×10 17 cm -3, preferably set to 1×10 16 cm -3 .

[0049] Specifically, in the present embodiment, in order to eliminate the rebound phenomenon and maintain the reverse conduction capability of the device, a second anode structure 15 is introduced into the first anode structure 14, that is, a Schottky anode 2 and a first P-type anode region 1 are introduced, and through the Schottky anode 2 and the first P-type anode region 1, a first PN junction barrier formed by the first P-type anode region 1 and the N-type buffer layer 6 is utilized to eliminate the rebound phenomenon of the traditional structure under short cells during the forward conduction stage of the device, and a large amount of electron conduction introduced by the work function difference between the first P-type anode region 1 and the Schottky anode 2 during reverse conduction is utilized to ensure the reverse conduction capability of the device.

[0050] More specifically, if Figure 4 As shown in FIG. 1 , when the new reverse-conducting IGBT device is in operation, it is divided into three stages: an initial forward conduction stage, a low-voltage forward conduction stage, and a high-voltage forward conduction stage. When in the initial forward conduction stage, as shown in FIG. Figure 4 As shown in (a), due to the effect of the first PN junction barrier formed by the first P-type anode region 1 and the N-type buffer layer 6, the flow path of electrons is blocked. At this time, the current is small, the flow path resistance is large, and the device is in a unipolar working mode; as the forward voltage increases, when it is in the low-voltage forward conduction stage, as shown in FIG. Figure 4 As shown in (b), the first PN junction barrier gradually decreases, the current increases, and the resistance decreases, but the resistance value is still large, and the unipolar working mode of the device is weakened; as the forward voltage increases further, when it is in the high-voltage forward conduction stage, as shown in Figure 4 As shown in (c), the second PN junction barrier formed by the second P-type anode region 3 and the N-type buffer layer 6 is turned on, and a large number of holes begin to be injected into the N-type drift layer 5. Due to the conductivity modulation effect, the resistance of the drift region decreases, and the device enters the bipolar working mode.

[0051] Although the forward voltage causes the first P-type anode region 1 to be punched through at this time, and some electrons flow through the first P-type anode region 1, and the electron blocking ability of the first P-type anode region 1 is weakened, due to the bipolar working mode, the first P-type anode region 1 always maintains a relatively large resistance, so that the forward voltage is simultaneously applied to the PN junction formed by the second P-type anode region 3 and the N-type buffer layer 6, causing the PN junction to be turned on, eliminating the rebound phenomenon, thereby solving the current misdivision problem caused by the rebound phenomenon, and at the same time reducing the turn-off time of the IGBT part of the device and the reverse recovery time of the diode part, and reducing the overall power switching loss of the device.

[0052] On the other hand, during reverse conduction, due to the influence of the low work function of the Schottky anode 2, an inversion layer appears on the lower surface of the first P-type anode region 1. As the reverse voltage increases, the potential barrier of the first P-type anode region 1 is penetrated, and the device begins to conduct electricity. Moreover, due to the small energy difference between the conduction bands of the metal and the semiconductor, under the action of the reverse voltage, electrons can enter the semiconductor from the metal to maintain conduction, thereby ensuring the reverse conduction capability of the device.

[0053] In order to further verify the working performance of the novel reverse conducting IGBT device of this embodiment, this embodiment takes a 1200V novel reverse conducting IGBT as an example and compares it with a traditional reverse conducting IGBT through simulation to illustrate the working performance.

[0054] like Figure 5 As shown in the figure, it is a line graph showing the change of the conduction band energy of the first P-type anode region 1 with the forward voltage when the novel reverse conducting IGBT device of this embodiment is forward-conducting. As can be seen from the figure, at V CE When it is 0V, the potential barrier of the first P-type anode region 1 is relatively large, and the electrons flowing from the N-type buffer layer 6 to the Schottky anode 2 need to pass through the high barrier region (i.e., the first PN junction barrier) formed by the first P-type anode region 1. At this time, due to the blocking effect of the barrier region, the number of electrons that can cross the barrier is relatively small, so the electronic current is relatively small and the resistance is relatively large.

[0055] With V CE Increased to 0.7V, the potential barrier of the first P-type anode region 1 is reduced, but still large, reflecting a large resistance value, which weakens the unipolar working mode of the device, allowing the forward voltage to be simultaneously applied to the PN junction formed by the second P-type anode region 3 and the N-type buffer layer 6, promoting the device to enter the bipolar working mode.

[0056] When VCE is 1.7V, the device enters the bipolar working mode. At this time, the potential barrier of the first P-type anode region 1 is almost completely weakened, and its blocking ability for electrons is relatively small. However, since the first P-type anode region 1 always maintains a large resistance in the device unipolar working mode, the rebound phenomenon of the device is eliminated.

[0057] During reverse conduction, affected by the metal work function of the Schottky anode 2, the conduction band of the first P-type anode region 1 close to the upper surface of the Schottky anode 2 will be close to the Fermi level. At this time, the electrons in the metal will enter the semiconductor and participate in the conduction in large quantities, thereby ensuring the reverse conduction capability of the device.

[0058] Specifically, Figure 6As shown, when the novel reverse-conducting IGBT device of this embodiment is initially turned on, the energy band variation diagram of the first P-type anode region 1 when the Schottky anode 2 has different metal work functions, when the metal work function is 4.4 eV, at a longitudinal length of 120 μm, the conduction band is far away from the Fermi level, and the lower surface of the first P-type anode region 1 presents a weak inversion zone. Since the surface electron concentration is low at this time and it is difficult for electrons to enter the semiconductor from the metal, the device cannot be turned on.

[0059] When the metal work function is 4.2eV, although the conduction band is close to the Fermi level, electrons still cannot enter the semiconductor under low reverse voltage, and the device cannot conduct in the reverse direction.

[0060] When the metal work function is 4.0eV, the conduction band is below the Fermi level, the lower surface of the first P-type anode region 1 enters a strong inversion state, and electrons can enter the semiconductor at a very low voltage. At this time, the device can maintain good reverse conduction performance, thus verifying the above statement.

[0061] like Figure 7 As shown, it is a comparison diagram of the forward conduction characteristics of the new reverse conducting IGBT device of this embodiment and the traditional reverse conducting IGBT device. The new reverse conducting IGBT device of this embodiment successfully eliminates the rebound phenomenon of the short-cell reverse conducting IGBT device, while the traditional type still cannot completely eliminate the rebound phenomenon under the condition of LA of 100μm.

[0062] At 150A / cm 2 At an on-current density of , the on-voltage drop of the novel reverse conducting IGBT device of this embodiment is 1.41V, which is slightly higher than 1.37V of the conventional reverse conducting IGBT device, but eliminates the harmful rebound phenomenon in parallel operation.

[0063] like Figure 8 As shown, it is a comparison diagram of the reverse conduction characteristics of the new reverse conducting IGBT device of this embodiment and the traditional reverse conducting IGBT device. It can be seen from the figure that at a reverse conduction current density of 150A / cm2, the reverse conduction voltage drop of the new reverse conducting IGBT device of this embodiment is 1.25V, which is only slightly higher than the traditional 1.21V. This is caused by the combined effect of the first P-type anode region 1 and the Schottky anode 2 potential barrier.

[0064] like Fig. 9 As shown, the conduction performance diagram of the novel reverse conducting IGBT device of this embodiment under different doping concentrations in the first P-type anode region 1 is shown. Since the novel reverse conducting IGBT device of this embodiment requires forward conduction without rebound and reverse conduction, Fig. 9 It can be seen that the doping concentration of the first P-type anode region 1 needs to be controlled at 4×10 15 cm-3 ~6×10 15 cm -3 within the range.

[0065] like Fig.10 As shown, this is a reverse conduction voltage drop diagram of the new reverse conducting IGBT device of this embodiment under different metal work functions. It can be seen from the figure that in order to obtain a smaller reverse conduction voltage drop and consider the obtainability of the metal work function, it is necessary to control the metal work function between 3.0eV and 4.2eV.

[0066] Embodiment 2

[0067] like Fig.11 As shown, the difference between this embodiment and the first embodiment is that the second anode structure 15 is arranged on both sides of the first anode structure 14 of this embodiment, and the second anode structures 15 on both sides are located on the same surface as the first anode structure 14 and are connected through the N-type drift layer 5. By introducing the Schottky anode 2 and the first P-type anode region 1, and utilizing the first PN junction barrier formed by the first P-type anode region 1 and the N-type buffer layer 6, the rebound phenomenon of the traditional structure under the short cell is eliminated in the forward conduction stage of the device, and during reverse conduction, a large amount of electrons introduced by the work function difference between the first P-type anode region 1 and the Schottky anode 2 are utilized to conduct electricity, thereby ensuring the reverse conduction capability of the device. At the same time, the arrangement of the second anode structures 15 on both sides makes the carrier distribution more uniform.

[0068] Embodiment 3

[0069] A method for preparing a novel reverse-conducting IGBT device, the method for preparing the novel reverse-conducting IGBT device of any one of Embodiment 1 or Embodiment 2.

[0070] The steps for preparing the novel reverse conducting IGBT device shown in the first embodiment are as follows:

[0071] S1, select the doping concentration as 7.7×10 13 cm -3 ~1×10 15 cm -3 The N-type silicon wafer is used as the substrate silicon wafer to obtain a lightly doped N-type drift layer 5 with a thickness of 100 μm to 150 μm;

[0072] S2, etching the silicon substrate to form a groove of 4 μm to 8 μm;

[0073] S3, O2 annealing to form a 0.1μm~0.5μm thick SiO2 layer to form a gate oxide layer 8;

[0074] S4, deposit polysilicon on the surface of the SiO2 trench to form a polysilicon gate 9, with a concentration of 1×10 20 cm-3 ~5×10 21 cm -3 ;

[0075] S5, the P-type cathode region 12 heavily doped with boron ions is implanted into the substrate surface with a dose of 1×10 18 cm -3 ~1×10 20 cm -3 ;

[0076] S6, boron ions are implanted into the substrate surface to form a lightly doped P-type base region 10, with a dose of 8×10 15 cm -3 ~1×10 17 cm -3 ;

[0077] S7, phosphorus ions are implanted into the substrate surface to form a heavily doped N-type cathode region 13, with a dose of 1×10 19 cm -3 ~1×10 20 cm -3 ;

[0078] S8, phosphorus ions are implanted into the back of the substrate to form a lightly doped N-type buffer layer 6, with a dose of 5×10 15 cm -3 ~1×10 17 cm -3 ;

[0079] S9, implant boron ions into the back of the substrate to form a heavily doped second P-type anode region 3 on one side of the back of the substrate. The dose is 1×10 18 cm -3 ~1×10 20 cm -3 ;

[0080] S10, boron ions are implanted on the back of the substrate to form a lightly doped first P-type anode region 1 on the other side of the back of the substrate. The dose is 4×10 15 cm -3 ~6×10 15 cm -3 ;

[0081] S11, double-sided aluminum vaporization forms an ohmic contact electrode, forming a cathode electrode 11, a gate electrode 7 and an anode electrode 4;

[0082] S12, selecting a metal with a metal work function of 3.0 eV to 4.2 eV to form a P-type Schottky anode 2.

[0083] The steps for preparing the novel reverse conducting IGBT device shown in Example 2 are as follows:

[0084] S1, select the doping concentration as 7.7×10 13 cm -3 ~1×10 15 cm -3 The N-type silicon wafer is used as the substrate silicon wafer to obtain a lightly doped N-type drift layer 5 with a thickness of 100 μm to 150 μm;

[0085] S2, etching the silicon substrate to form a groove of 4 μm to 8 μm;

[0086] S3, O2 annealing to form a 0.1μm~0.5μm thick SiO2 layer to form a gate oxide layer 8;

[0087] S4, deposit polysilicon on the surface of the SiO2 trench to form a polysilicon gate 9, with a concentration of 1×10 20 cm -3 ~5×10 21 cm -3 ;

[0088] S5, the P-type cathode region 12 heavily doped with boron ions is implanted into the substrate surface with a dose of 1×10 18 cm -3 ~1×10 20 cm -3 ;

[0089] S6, boron ions are implanted into the substrate surface to form a lightly doped P-type base region 10, with a dose of 8×10 15 cm -3 ~1×10 17 cm -3 ;

[0090] S7, phosphorus ions are implanted into the substrate surface to form a heavily doped N-type cathode region 13, with a dose of 1×10 19 cm -3 ~1×10 20 cm -3 ;

[0091] S8, phosphorus ions are implanted into the back of the substrate to form a lightly doped N-type buffer layer 6, with a dose of 5×10 15 cm -3 ~1×10 17 cm -3 ;

[0092] S9, implant boron ions into the back of the substrate to form a heavily doped second P-type anode region 3 on both sides of the back of the substrate. The dose is 1×10 18 cm -3 ~1×10 20 cm -3 ;

[0093] S10, boron ions are implanted into the back of the substrate to form a lightly doped first P-type anode region 1 between the two groups of second P-type anode regions 3 on the back of the substrate. The dosage is 4×10 15 cm -3 ~6×10 15 cm -3 ;

[0094] S11, double-sided aluminum vaporization forms an ohmic contact electrode, forming a cathode electrode 11, a gate electrode 7 and an anode electrode 4;

[0095] S12, selecting a metal with a metal work function of 3.0 eV to 4.2 eV to form a P-type Schottky anode 2.

[0096] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A novel reverse conducting IGBT device, characterized in that: include: a first anode structure; A second anode structure, wherein the second anode structure and the first anode structure are located on the same surface, and the second anode structure and the first anode structure are connected via an N-type drift layer; A drift region structure, wherein the drift region structure is disposed on the first anode structure and the second anode structure, the drift region structure and the second anode structure form a first PN junction barrier, and the drift region structure and the first anode structure form a second PN junction barrier; A gate structure, wherein the gate structure is disposed on a surface of the drift region structure away from the first anode structure; A cathode structure is disposed on the gate structure.

2. A novel reverse conducting IGBT device according to claim 1, characterized in that: When in the initial forward conduction stage, the first PN junction potential barrier blocks the flow path of electrons, and the device is in a unipolar working mode; When in the low-voltage forward conduction stage, the first PN junction potential barrier decreases, and the unipolar working mode of the device is weakened; When in the high-voltage forward conduction stage, the second PN junction barrier is turned on, and the device enters a bipolar operation mode.

3. A novel reverse conducting IGBT device according to claim 1, characterized in that: The second anode structure is located on one side of the first anode structure; Alternatively, the second anode structure is located on both sides of the first anode structure, and the second anode structure on one side or both sides is located on the same surface as the first anode structure and is connected via an N-type drift layer.

4. A novel reverse conducting IGBT device according to any one of claims 1 to 3, characterized in that: The second anode structure includes a first P-type anode region and a Schottky anode. The Schottky anode is arranged on a surface of the first P-type anode region away from the drift region structure.

5. A novel reverse conducting IGBT device according to claim 4, characterized in that: The doping concentration of the first P-type anode region is 4×10 15 cm -3 ~6×10 15 cm -3 , the metal work function of the Schottky anode is 3.0 eV~4.2 eV.

6. A novel reverse conducting IGBT device according to claim 1, characterized in that: The first anode structure includes a second P-type anode region and an anode electrode, wherein the anode electrode is disposed on a surface of the second P-type anode region away from the drift region structure, and the doping concentration of the second P-type anode region is 1×10 18 cm -3 ~1×10 20 cm -3 .

7. The novel reverse conducting IGBT device according to claim 1, characterized in that: The drift region structure includes an N-type drift layer and an N-type buffer layer. The N-type drift layer is arranged on a surface of the N-type buffer layer away from the first anode structure and the second anode structure. The doping concentration of the N-type drift layer is 7.7×10 13 cm -3 ~1×10 15 cm -3 The doping concentration of the N-type buffer layer is 5×10 15 cm -3 ~1×10 17 cm -3 .

8. The novel reverse conducting IGBT device according to claim 1, characterized in that: The gate structure includes a gate electrode, a gate oxide layer, a polysilicon gate and a P-type base region. The polysilicon gate is arranged through the P-type base region. The gate oxide layer is formed on the side wall of the polysilicon gate. The gate electrode is arranged on the surface of the polysilicon gate away from the drift region structure. The doping concentration of the P-type base region is 8×10 15 cm -3 ~1×10 17 cm -3 The doping concentration of the polysilicon gate is 1×10 20 cm -3 ~5×10 21 cm -3 , the thickness of the gate oxide layer is 0.1 μm~0.5 μm.

9. A novel reverse conducting IGBT device according to claim 8, characterized in that: The cathode structure includes a cathode electrode, a P-type cathode region and an N-type cathode region, wherein the sidewall of the P-type cathode region is in contact with the sidewall of the N-type cathode region, and the P-type cathode region and the N-type cathode region are located on the same surface, and the sidewall of the N-type cathode region is also in contact with the sidewall of the gate oxide layer, and the cathode electrode is in contact with both the P-type cathode region and the N-type cathode region, and the doping concentration of the P-type cathode region is 1×10 18 cm -3 ~1×10 20 cm -3 The doping concentration of the N-type cathode region is 1×10 19 cm -3 ~1×10 20 cm -3 .

10. A method for preparing a novel reverse-conducting IGBT device, characterized in that: The preparation method is used to prepare the novel reverse conducting IGBT device according to any one of claims 1 to 9.

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