An RC-IGBT device integrated with an MPS fast recovery diode

Abstract

The present application relates to a kind of RC-IGBT devices of integrated MPS fast recovery diode, belong to semiconductor technical field.The device includes cathode P+ region, cathode P-well region, cathode N+ region, drift region, anode N-buffer region, anode P+ region, anode N+ region, anode P-well region, cathode MOS oxide layer, cathode MOS polysilicon gate, cathode MPS fast recovery diode and anode MOS oxide layer.Cathode P+ region, cathode P-well region, cathode N+ region, drift region, cathode MOS oxide layer and cathode MOS polysilicon gate constitute cathode MOS region, for controlling the opening and shutdown of the device;Anode N+ region, anode P-well region and anode MOS oxide layer constitute anode MOS region, provide reverse conduction capability for the device.The present application greatly improves the reverse recovery performance of device by integrating MPS fast recovery diode.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology and relates to an RC-IGBT device with integrated MPS fast recovery diode. Background Technology

[0002] IGBT (Insulated Gate Bipolar Transistor) is a semiconductor power device that combines the voltage control mechanism of MOSFET and the bipolar conduction mechanism of BJT. It combines the advantages of both, such as low on-state voltage, low drive power consumption and high operating frequency. It is widely used in communication technology, new energy equipment and various consumer electronics fields, and is a core component of electronic power systems.

[0003] Because IGBTs lack reverse conduction capability, a reverse-current freewheeling diode is typically connected in parallel next to the IGBT for protection in practical applications. Early IGBTs and diodes were packaged separately and used independently, leading to performance mismatch and the introduction of parasitic inductance during soldering, thus increasing the cost and reducing the reliability of IGBT applications. To address this issue, attempts were made to package the IGBT and diode together, reducing parasitic parameters but still failing to achieve true process integration. Simultaneously, to further improve device integration and reduce manufacturing costs, researchers began integrating the protective freewheeling diode inside the IGBT, forming the RC-IGBT (Reverse-Conducting Insulated Gate Bipolar Transistor). The advent of the RC-IGBT significantly simplified the topology of electronic circuits, reduced parasitic parameters, and decreased chip area, but it also has some significant drawbacks.

[0004] In traditional RC-IGBT devices, the N+ and P+ regions of the anode are shorted together by the anode electrode, introducing a parasitic diode within the device, providing reverse conduction capability. During device turn-off, the N+ region of the anode can directly extract electrons from the drift region, improving the switching speed and reducing turn-off losses. However, the introduction of the N+ region reduces hole injection efficiency during conduction, leading to an increased on-state voltage drop and, more seriously, a snapback phenomenon. When the on-state current is small, electrons injected into the NMOS flow directly out of the N+ region, the P+ / N-buffer junction is not conducting, and the device is in unipolar mode with high on-resistance. As the on-state current gradually increases, the voltage drop generated by electrons flowing through the N-buffer region below the P+ region gradually increases. When the voltage drop exceeds the built-in potential of the P+ / N-buffer junction, the P+ region begins to inject holes into the drift region, causing conduction modulation. The device enters bipolar mode, the resistance drops significantly, and the snapback phenomenon occurs. This introduces electromagnetic oscillations into the circuit system, affecting system stability. Secondly, the freewheeling diode also affects the performance of the IGBT. For the freewheeling diode built into the RC-IGBT, its reverse recovery performance is far inferior to that of a discrete diode, and the trade-off between its reverse recovery performance and forward voltage drop is even more difficult to reconcile. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an RC-IGBT device with an integrated MPS fast recovery diode. By integrating an MPS fast recovery diode into a traditional IGBT device, the reverse recovery charge of the device is reduced when the device is reverse-biased, thereby improving the reverse recovery performance of the device. The work function of the Schottky metal is changed to optimize the trade-off between the diode's forward voltage drop and reverse recovery performance.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An RC-IGBT device integrating an MPS fast recovery diode includes a cathode P+ region, a cathode P-well region, a cathode N+ region, a drift region, an anode N-buffer region, an anode P+ region, an anode N+ region, an anode P-well region, a cathode MOS oxide layer, a cathode MOS polysilicon gate, a cathode MPS fast recovery diode, and an anode MOS oxide layer.

[0008] The anode P+ region is formed on the collector surface; the anode MOS oxide layer is formed on the collector surface and symmetrically distributed on both sides of the anode P+ region; the anode N+ region is formed on the collector surface and symmetrically distributed on both sides of the anode P+ region; the anode P-well region is formed on the surface of the anode N+ region; the anode N-buffer region covers the anode P-well region, the anode MOS oxide layer, and the anode P+ region surface; the drift region is formed on the surface of the anode N-buffer region; the cathode P-well region is formed in the drift region; the cathode P+ region is formed on the surface of the cathode P-well region; the cathode N+ region is formed on the surface of the cathode P-well region and distributed on both sides of the cathode P+ region; the cathode MOS polysilicon gate is formed in the drift region and symmetrically distributed on both sides of the cathode P-well region; the cathode MOS oxide layer completely encapsulates the cathode MOS polysilicon gate; and the cathode MPS fast recovery diode is formed in the cathode region. Two cathode MOS polysilicon gates, completely encapsulated by the cathode MOS oxide layer, are distributed on each side of the cathode P-well region, with a gap between the two cathode MOS polysilicon gates.

[0009] Optionally, the cathode MPS fast recovery diode includes a cathode Schottky diode and a cathode general diode; wherein the cathode Schottky diode is distributed on both sides of the cathode P-well region and is located in the gap between the cathode MOS polysilicon gates.

[0010] A cathode Schottky diode consists of a cathode Schottky electrode and a portion of the drift region located in the gap between the gates of the cathode MOS polysilicon.

[0011] Optionally, the work function of the cathode Schottky electrode can be adjusted as needed.

[0012] Optionally, the cathode P+ region, cathode P-well region, cathode N+ region, drift region, cathode MOS oxide layer, and cathode MOS polysilicon gate constitute the cathode MOS region of the RC-IGBT device, which is used to control the turn-on and turn-off of the device.

[0013] Optionally, the anode N+ region, the anode P-well region, and the anode MOS oxide layer constitute the anode MOS region of the RC-IGBT device, providing the device with reverse conduction capability.

[0014] The beneficial effects of this invention are as follows: Based on the traditional RC-IGBT device, this invention introduces a built-in Schottky diode at the cathode and a self-biased MOS at the anode. During forward conduction, the negative resistance effect is eliminated due to the presence of the anode P-well in the anode MOS. During reverse conduction, the anode MOS automatically turns on, providing a reverse conduction path for the device. The Schottky diode and PIN diode form an MPS fast recovery diode, simultaneously achieving low on-state voltage and low charge storage, greatly improving the reverse recovery performance of the device, and enhancing its reliability, ease of use, and low power consumption.

[0015] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0017] Figure 1 This is a schematic diagram of the RC-IGBT device with integrated MPS fast recovery diode provided in Embodiment 1 of the present invention;

[0018] Figure 2 for Figure 1 The equivalent circuit diagram of the device shown;

[0019] Figure 3 This is a diagram showing the positive blocking characteristics of Example 1;

[0020] Figure 4 This is a potential distribution diagram of Example 1 under avalanche breakdown conditions;

[0021] Figure 5 This is a current distribution diagram of Example 1 in the reverse conduction state;

[0022] Figure 6 This is a comparison chart of the reverse conduction characteristics of Example 1 and a conventional RC-IGBT device;

[0023] Figure 7 This is a comparison chart of the reverse recovery characteristics of Example 1 and a conventional RC-IGBT device.

[0024] Figure reference numerals: 1-Cathode P+ region; 2-Cathode P-well region; 3-Cathode N+ region; 4-Cathode Schottky diode; 5-Drift region; 6-Anode N-buffer region; 7-Anode P+ region; 8-Anode N+ region; 9-Anode P-well region; 10-Cathode MOS oxide layer; 11-Cathode MOS polysilicon gate; 12-Anode MOS oxide layer; 13-Cathode Schottky electrode. Detailed Implementation

[0025] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0027] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0028] like Figure 1 As shown, an RC-IGBT device with an integrated MPS fast recovery diode provided in Embodiment 1 of the present invention includes a cathode P+ region 1, a cathode P-well region 2, a cathode N+ region 3, a cathode Schottky diode 4, a drift region 5, an anode N-buffer region 6, an anode P+ region 7, an anode N+ region 8, an anode P-well region 9, a cathode MOS oxide layer 10, a cathode MOS polysilicon gate 11, an anode MOS oxide layer 12, and a cathode Schottky electrode 13.

[0029] The cathode MOS region comprises the P+ region 1, P-well region 2, N+ region 3, drift region 5, MOS oxide layer 10, and polysilicon gate 11. A Schottky diode and a conventional diode form a fast recovery diode (MPS), where the Schottky diode 4 consists of the drift region 5 located between the two MOS oxide layers 10 and the Schottky electrode 13. The anode MOS region comprises the N+ region 8, P-well region 9, N-buffer region 6, and MOS oxide layer 12. The P+ region 7 and N-buffer region 6 form the anode region.

[0030] When the device in Example 1 is in forward conduction, its structure operates identically to a conventional IGBT. The gate voltage of the cathode MOS gradually increases, injecting electrons into the drift region. At this time, the anode MOS is off, and the anode P-well region 9 acts as an electron barrier, preventing electrons from flowing directly through the anode N+ region 8, thus eliminating the negative resistance effect present in traditional RC-IGBTs. In reverse conduction, as the cathode voltage increases, the self-biased anode MOS turns on, providing an electron path for the device. The MPS diode integrated within the device can be considered a parallel combination of a PIN diode and a Schottky diode. In reverse conduction, the Schottky diode provides the main electron current, while the PIN diode provides a small amount of bipolar current. This unique operating mode enables the device to achieve good reverse recovery performance at a relatively low reverse conduction voltage.

[0031] This invention uses SENTAURUS simulation software to perform performance simulation analysis and electrical simulation on the IGBT device of Example 1. During the simulation, all simulation parameters of the Example 1 device are consistent with those of the conventional device, including a carrier lifetime of 10 μs and an ambient temperature of 300 K. The simulation results are as follows: Figures 2-7 As shown.

[0032] like Figure 2 The diagram shown is the equivalent circuit diagram of the RC-IGBT device in Example 1, where the IGBT is equivalent to an NMOS-controlled PNP transistor; the anode self-biased MOS transistor is connected in parallel to the base and collector of the PNP transistor; the cathode P+ and the PIN diode equivalent to the drift region are connected in parallel with the Schottky diode, which together form an MPS fast recovery diode.

[0033] like Figure 3 The image shows a comparison of the blocking characteristics of Example 1 when the drift region length is 110 μm. Example 1 had a drift region concentration of 4.5 × 10⁻⁶ μm. 14 cm -3 The breakdown voltage at that time was 1155V.

[0034] like Figure 5 The image shows Example 1 with a drift region length of 110 μm and a concentration of 4.5 × 10⁻⁶. 15 cm -3 The current distribution diagram under reverse conduction shows that most of the reverse conduction current is provided by the Schottky diode, and only a small portion of the current flows through the PIN diode region. This indicates that the device in Example 1 operates in MPS fast recovery diode mode.

[0035] like Figure 6 The figure shows a comparison of the reverse conduction curves of Example 1 and the conventional RC-IGBT. Since Example 1 operates in MPS mode, the reverse conduction voltage drop of Example 1 is 15% lower than that of the conventional RC-IGBT under the same current density.

[0036] like Figure 7 The figure shows a comparison of the reverse recovery performance of Example 1 and the conventional RC-IGBT. Compared with the conventional RC-IGBT, Example 1 has a 66% reduction in reverse recovery peak current and a 62% reduction in total reverse recovery charge.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An RC-IGBT device integrating an MPS fast recovery diode, comprising a cathode P+ region, a cathode P-well region, a cathode N+ region, a drift region, an anode N-buffer region, an anode P+ region, an anode N+ region, an anode P-well region, a cathode MOS oxide layer, and a cathode MOS polysilicon gate, characterized in that: The device also includes a cathode MPS fast recovery diode and an anode MOS oxide layer; The anode P+ region is formed on the collector surface; the anode MOS oxide layer is formed on the collector surface and symmetrically distributed on both sides of the anode P+ region; the anode N+ region is formed on the collector surface and symmetrically distributed on both sides of the anode P+ region; the anode P-well region is formed on the surface of the anode N+ region; the anode N-buffer region covers the anode P-well region, the anode MOS oxide layer, and the anode P+ region surface; the drift region is formed on the surface of the anode N-buffer region; the cathode P-well region is formed in the drift region; the cathode P+ region is formed on the surface of the cathode P-well region; the cathode N+ region is formed on the surface of the cathode P-well region and distributed on both sides of the cathode P+ region; the cathode MOS polysilicon gate is formed in the drift region and symmetrically distributed on both sides of the cathode P-well region; the cathode MOS oxide layer completely encapsulates the cathode MOS polysilicon gate; the cathode MPS fast recovery diode is formed in the cathode region.

2. The RC-IGBT device according to claim 1, characterized in that: On each side of the cathode P-well region, there are two cathode MOS polysilicon gates that are completely enclosed by the cathode MOS oxide layer, and there is a gap between the two cathode MOS polysilicon gates.

3. The RC-IGBT device according to claim 2, characterized in that: The cathode MPS fast recovery diode includes a cathode Schottky diode and a cathode ordinary diode; the cathode Schottky diode is distributed on both sides of the cathode P-well region and is located in the gap between the cathode MOS polysilicon gates.

4. The RC-IGBT device according to claim 3, characterized in that: The cathode Schottky diode consists of a cathode Schottky electrode and a portion of the drift region located in the gap between the cathode MOS polysilicon gate.

5. The RC-IGBT device according to claim 4, characterized in that: The work function of the cathode Schottky electrode can be adjusted as needed.

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