Reverse conducting IGBT with uniform reverse current distribution

Abstract

The application discloses a reverse conducting IGBT with uniform reverse current distribution, which comprises a half cell structure, the half cell structure comprising a collector structure, a voltage resistance layer structure, an emitter structure and a gate structure; the collector structure is located at one end of the voltage resistance layer structure, and the emitter structure and the gate structure are located at two sides of the other end of the voltage resistance layer structure; wherein the collector structure comprises a P+ collector region, an N+ collector region, an N-type buffer layer, a P-type conductive material, a collector metal and a floating metal; the collector metal is connected to the P+ collector region and leads out a collector, the floating metal is connected to the N+ collector region, and the collector metal and the floating metal are not in contact; on the basis of a conventional reverse conducting IGBT structure, the voltage foldback phenomenon is eliminated by optimizing and improving the collector structure and utilizing the P-type Schottky diode introduced at the collector side, so that the length ratio of the P+ collector region to the N+ collector region can be smaller, and the current is more uniform when the device is reversely turned on.

Description

Technical Field

[0001] The present invention relates to the field of power semiconductor technology, and more particularly to a reverse-conducting IGBT with uniform reverse current distribution. Background Art

[0002] like Figure 3-4 The conventional reverse-conducting IGBT structure and equivalent circuit diagram shown in the figure, when the conventional reverse-conducting IGBT is forward-conducting, the N+ collector region (12) is turned on first. At this time, the device operates in a unipolar conduction mode and has a large on-resistance. Due to the parasitic resistance of the N-type buffer layer (13), as the anode voltage increases, the anode current will generate a voltage drop on the parasitic resistance. When the potential difference between this voltage drop and the P+ collector region (11) is greater than 0.7V, the P+ collector region (13) / The PN junction of the N-type buffer layer (13) is turned on, and the device enters the bipolar conduction mode with a low on-resistance. The sharp decrease in on-resistance will cause voltage foldback. In order to alleviate this phenomenon, the length of the P+ collector region (11) of a conventional reverse-conducting IGBT is often designed to be very long, but this will cause the length of the N+ collector region (12) to be relatively short. When the reverse-conducting IGBT device is reverse-conducting, the P+ body contact region (33), the P-type well region (31), the N-type drift region (21), the N-type buffer layer (13) and the N+ collector region (12) form a diode conduction current. At this time, if the length of the N+ collector region (12) is short, the reverse conduction current will be unevenly distributed, thereby affecting the device performance and system reliability. Summary of the Invention

[0003] In order to solve the problems raised in the technical background, the present invention provides a reverse-conducting IGBT with uniform reverse current distribution. Due to the introduction of a collector-side Schottky diode, the voltage foldback phenomenon is eliminated in this structure, so that the length ratio of the P+ collector region to the N+ collector region can be smaller, thereby making the current more uniform when the device is reverse-conducting.

[0004] The present invention is achieved through the following technical solutions:

[0005] Provided is a reverse-conducting IGBT with uniform reverse current distribution, comprising a half-cell structure, the half-cell structure comprising a collector structure, a voltage-resistant layer structure, an emitter structure, and a gate structure; the collector structure is located at one end of the voltage-resistant layer structure, and the emitter structure and the gate structure are located on both sides of the other end of the voltage-resistant layer structure;

[0006] The collector structure includes a P+ collector region, an N+ collector region and an N-type buffer layer, a P-type conductive material, a collector metal, and a floating metal;

[0007] One side of the N-type buffer layer is connected to the voltage-resistant layer structure, one side of the P+ collector region and one side of the N+ collector region are respectively connected to the other side of the N-type buffer layer, and a gap is formed between the P+ collector region and the N+ collector region. The collector metal is connected to the other side of the P+ collector region and leads to the collector. The floating metal is connected to the other side of the N+ collector region, and the collector metal and the floating metal are not in contact.

[0008] The P-type conductive material is placed in the gap and is in Schottky contact with the collector metal and ohmic contact with the floating metal respectively. There is a distance between the side of the P-type conductive material and the P+ collector area, N+ collector area and N-type buffer layer.

[0009] Specifically, the emitter structure includes a P-type well region, an N+ emitter region, a P+ body contact region and an emitter metal;

[0010] One side of the P-type well region is connected to the voltage-resistant layer structure, the N+ emitter region and the P+ body contact region are in contact with each other, and one side of the N+ emitter region and the P+ body contact region are both connected to the other side of the P-type well region;

[0011] One side of the emitter metal leads to the emitter, and the other side is connected to the N+ emitter region and the P+ body contact region at the same time.

[0012] Specifically, the gate structure includes a trench gate, which is composed of a second insulating dielectric layer, a conductive material layer and a gate metal. The conductive material layer is arranged in the second insulating dielectric layer, and the gate metal is arranged on the conductive material layer, and a gate is led out.

[0013] Specifically, one side of the second insulating dielectric layer vertically penetrates the P-type well region and contacts the P-type well region and the N+ type emitter region.

[0014] Specifically, the voltage-resistant layer structure includes an N-type drift region; the N-type drift region is in contact with the second insulating dielectric layer and the P-type well region.

[0015] Preferably, an insulating dielectric layer is provided in the gap between the P+ collector region and the N+ collector region, and the P-type conductive material is connected to the insulating dielectric layer.

[0016] Preferably, one side of the insulating dielectric layer is extended and attached to the N-type buffer layer.

[0017] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0018] The present invention optimizes and improves the collector structure on the basis of the conventional reverse-conducting IGBT structure, and uses a P-type Schottky diode introduced on the collector side to eliminate the voltage foldback phenomenon, thereby making the length ratio of the P+ collector region to the N+ collector region smaller, ensuring that the current of the device is more uniform when reverse conducting. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention.

[0020] Figure 1 This is a schematic diagram of the reverse conducting IGBT structure of the present invention;

[0021] Figure 2 Schematic diagram of the equivalent circuit of the reverse-conducting IGBT of the present invention;

[0022] Figure 3 This is a schematic diagram of the structure of a conventional reverse-conducting IGBT;

[0023] Figure 4 This is a schematic diagram of the equivalent circuit of a conventional reverse-conducting IGBT.

[0024] Description of reference numerals:

[0025] 11. P+ collector region, 12. N+ collector region, 13. N-type buffer layer, 14. First insulating dielectric layer, 15. P-type conductive material, 16. Collector metal, 17. Floating metal, 21. N-type drift region, 31. P-type well region, 32. N+ emitter region, 33. P+ body contact region, 34. Emitter metal, 41. Second insulating dielectric layer, 42. Conductive material layer, 43. Gate metal, C, collector, E, emitter, G, gate. DETAILED DESCRIPTION

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0027] Example 1:

[0028] like Figure 1-2 A reverse-conducting IGBT with uniform reverse current distribution is shown, comprising a half-cell structure, which includes a collector structure, a voltage-resistant layer structure, an emitter structure, and a gate structure; the collector structure is located at one end of the voltage-resistant layer structure, and the emitter structure and the gate structure are located on both sides of the other end of the voltage-resistant layer structure. The above content is prior art and will not be described in detail here;

[0029] The collector structure includes a P+ collector region 11, an N+ collector region 12, an N-type buffer layer 13, a P-type conductive material 15, a collector metal 16, and a floating metal 17;

[0030] One side of the N-type buffer layer 13 is connected to the voltage-withstand layer structure. One side of the P+ collector region 11 and the N+ collector region 12 are respectively connected to the other side of the N-type buffer layer 13, with a gap between the P+ collector region 11 and the N+ collector region 12. The collector metal 16 is connected to the other side of the P+ collector region 11 and leads to the collector C. The floating metal 17 is connected to the other side of the N+ collector region 12, and the collector metal 16 and the floating metal 17 are not in contact with each other.

[0031] The P-type conductive material 15 is placed in the gap and is in Schottky contact with the collector metal 16 and in ohmic contact with the floating metal 17. There is a gap between the side of the P-type conductive material 15 and the P+ collector region 11, the N+ collector region 12 and the N-type buffer layer 13.

[0032] Specifically, the emitter structure includes a P-type well region 31, an N+ emitter region 32, a P+ body contact region 33 and an emitter metal 34;

[0033] One side of the P-type well region 31 is connected to the voltage-resistant layer structure, the N+ emitter region 32 and the P+ body contact region 33 are in contact with each other, and one side of the N+ emitter region 32 and the P+ body contact region 33 are both connected to the other side of the P-type well region 31;

[0034] One side of the emitter metal 34 leads to the emitter E, and the other side is connected to both the N+ emitter region 32 and the P+ body contact region 33;

[0035] The gate structure includes a trench gate, which is composed of a second insulating dielectric layer 41, a conductive material layer 42, and a gate metal 43. The conductive material layer 42 is provided in the second insulating dielectric layer 41, and the gate metal 43 is provided on the conductive material layer 42, with a gate G extending therefrom. One side of the second insulating dielectric layer 41 vertically penetrates the P-type well region 31 and contacts the P-type well region 31 and the N+ type emitter region 32.

[0036] The voltage-resistant layer structure includes an N-type drift region 21 ; the N-type drift region 21 is in contact with the first insulating medium 41 and the P-type well region 31 ;

[0037] In the present invention, the collector metal 16, the floating metal 17, and the P-type conductive material 15 form a P-type Schottky diode. When the device is forward-conducting, the P-type Schottky diode is reverse-biased, and when the device is reverse-conducting, the P-type Schottky diode is forward-biased, thereby eliminating the voltage foldback phenomenon and making the current uniform when the device is turned on. The specific working principle is as follows;

[0038] During forward conduction: the gate G is connected to a positive voltage, the collector C is connected to a positive voltage, and the emitter E is grounded. The voltage on the gate G opens the channel, and electrons are injected into the N-type drift region 21. Since there is a reverse-biased P-type Schottky diode between the N+ collector region 12 and the collector C, the N+ collector region 12 does not conduct when the device is forward-conducting, and only the P+ collector region 11 conducts. Therefore, when forward-conducting, the device directly enters the bipolar conduction mode, and there is no voltage foldback phenomenon caused by the sudden change in drift region resistance from unipolar conduction to bipolar conduction.

[0039] When conducting in the reverse direction, the gate G is grounded, the emitter E is grounded, and the collector C is connected to a negative voltage. The diode formed by the P+ body contact region 33, the P-type well region 31, the N-type drift region 21, the N-type buffer layer 13, and the N+ collector region 12 is connected in series with the P-type Schottky diode, and the device can conduct reverse current.

[0040] The reverse conducting IGBT structure disclosed in the invention eliminates the voltage foldback phenomenon in the reverse conducting IGBT by introducing a P-type Schottky diode into the collector structure, so that the length ratio of the P+ collector region 11 to the N+ collector region 22 can be smaller, thereby ensuring that the current of the reverse conducting IGBT is more uniform when it is reversely conducted.

[0041] Example 2:

[0042] On the basis of embodiment 1, further, a first insulating dielectric layer 14 is provided in the gap between the P+ collector region 11 and the N+ collector region 12 , and a P-type conductive material 15 is connected to the first insulating dielectric layer 14 .

[0043] Preferably, one side of the first insulating dielectric layer 14 is extended and attached to the N-type buffer layer 13 .

[0044] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A reverse-conducting IGBT with uniform reverse current distribution, comprising a half-cell structure, wherein the half-cell structure includes a collector structure, a voltage-withstand layer structure, an emitter structure, and a gate structure; the collector structure is located at one end of the voltage-withstand layer structure, and the emitter structure and the gate structure are located on both sides of the other end of the voltage-withstand layer structure, characterized in that: The collector structure includes a P+ collector region (11), an N+ collector region (12), an N-type buffer layer (13), a P-type conductive material (15), a collector metal (16), and a floating metal (17); One side of the N-type buffer layer (13) is connected to the voltage-resistant layer structure, one side of the P+ collector region (11) and one side of the N+ collector region (12) are respectively connected to the other side of the N-type buffer layer (13), and there is a gap between the P+ collector region (11) and the N+ collector region (12), the collector metal (16) is connected to the other side of the P+ collector region (11) and leads to the collector (C), the floating metal (17) is connected to the other side of the N+ collector region (12), and the collector metal (16) and the floating metal (17) are not in contact; The P-type conductive material (15) is placed in the gap and is in Schottky contact with the collector metal (16) and in ohmic contact with the floating metal (17), and there is a gap between the side of the P-type conductive material (15) and the P+ collector region (11), the N+ collector region (12) and the N-type buffer layer (13); The emitter structure includes a P-type well region (31), an N+ emitter region (32), a P+ body contact region (33) and an emitter metal (34); One side of the P-type well region (31) is connected to the voltage-resistant layer structure, the N+ emitter region (32) and the P+ body contact region (33) are in contact with each other, and one side of the N+ emitter region (32) and the P+ body contact region (33) are both connected to the other side of the P-type well region (31); One side of the emitter metal (34) leads to the emitter (E), and the other side is simultaneously connected to the N+ emitter region (32) and the P+ body contact region (33); The gate structure includes a trench gate, which is composed of a second insulating dielectric layer (41), a conductive material layer (42) and a gate metal (43). The conductive material layer (42) is arranged in the second insulating dielectric layer (41), and the gate metal (43) is arranged on the conductive material layer (42) and has a gate (G) extending therefrom.

2. The reverse conducting IGBT with uniform reverse current distribution according to claim 1, characterized in that: A first insulating dielectric layer (14) is provided in the gap between the P+ collector region (11) and the N+ collector region (12), and the P-type conductive material (15) is connected to the first insulating dielectric layer (14).

3. The reverse conducting IGBT with uniform reverse current distribution according to claim 2, characterized in that: One side of the first insulating dielectric layer (14) is extended and attached to the N-type buffer layer (13).

4. The reverse conducting IGBT with uniform reverse current distribution according to claim 3, characterized in that: One side of the second insulating dielectric layer (41) vertically penetrates the P-type well region (31) and contacts the P-type well region (31) and the N+-type emitter region (32).

5. The reverse conducting IGBT with uniform reverse current distribution according to claim 4, characterized in that: The voltage-resistant layer structure comprises an N-type drift region (21); the N-type drift region (21) is in contact with the second insulating dielectric layer (41) and the P-type well region (31).

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