Semiconductor device

Abstract

The invention provides a semiconductor device, which can prevent carriers from flowing into an IGBT region from a diode region during recovery of a diode, and prevent the carriers from being concentrated at a boundary portion to cause damage to an element. In a semiconductor device (1) having an IGBT region (21) and a diode region (22) in the same chip, an IGBT in the IGBT region (21) has a drift layer (2) of a first conductivity type, a body layer (3) of a second conductivity type, and a first contact layer (5) of the second conductivity type having a higher impurity concentration than the body layer (3). The diode in the diode region (22) has a first semiconductor layer (11) of a second conductivity type, and a second contact layer (12) of the second conductivity type having a higher impurity concentration than the first semiconductor layer (11). The area of the second contact layer (12) of the diode close to the boundary portion (24) of the boundary portion (23) between the IGBT region (21) and the diode region (22) is smaller than the area of the second contact layer (12) of the diode away from the boundary portion.

Description

Technical Field

[0001] The present invention relates to a semiconductor device. Background Art

[0002] An RC-IGBT (RC: Reverse-Conducting, reverse-conducting IGBT) incorporating an IGBT (Insulated Gate Bipolar Transistor) and a diode within the same chip can share the terminal region of the IGBT's common diode, thus having the advantage of reducing the chip size. Additionally, since the operating timings of the IGBT and the diode are different, heat generated from losses in either the IGBT region or the diode region can be dissipated to the other, enabling heat dissipation across the entire chip, and thus also having the advantage of reducing the thermal resistance.

[0003] On the other hand, in an RC-IGBT, when the IGBT is turned on and the diode switches from conducting to non-conducting, i.e., during the diode's recovery, carriers (holes) tend to flow from the diode region into the IGBT region. As a result, there are problems such as carriers (holes) concentrating at the boundary between the diode region and the IGBT region, leading to component breakdown.

[0004] As a semiconductor device for reducing such component breakdown, for example, the following structure is described in FIG. 9 of Patent Document 1: In the IGBT region closest to the boundary between the IGBT region (10) and the diode region (20), a p+-type contact layer (14) is not provided. The surfaces of the n+-type source layer (13) and the p-type base layer (15) form the first main surface of the semiconductor substrate. The n+-type source layer (13) is connected to the active trench gate (11) but not to the boundary trench gate (51).

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2022-25674 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, if a p+-type contact layer (14) is not provided in the IGBT region at the boundary as in Patent Document 1, there is a possibility of the following problems even during IGBT operation: problems such as difficulty in hole flow in the IGBT at the boundary, resulting in an increase in turn-on voltage, and problems such as the IGBT being prone to latch-up.

[0010] The problem to be solved by the present invention is to provide a semiconductor device which, in a semiconductor device having an IGBT region and a diode region in the same chip, can suppress the inflow of carriers from the diode region into the IGBT region during the recovery of the diode, and prevent the carriers from concentrating at the boundary portion and causing element breakdown.

[0011] Solution to the problem

[0012] To solve the above problem, the semiconductor device of the present invention is characterized in that, for example, in a semiconductor device having an IGBT region and a diode region in the same chip,

[0013] The IGBT in the above IGBT region has a drift layer of a first conductivity type, a body layer of a second conductivity type, a first contact layer of the second conductivity type connected to the above body layer and having a higher impurity concentration than the above body layer, and an emitter electrode connected to the above first contact layer.

[0014] The diode in the above diode region has a first semiconductor layer of the second conductivity type, a second contact layer of the second conductivity type connected to the above first semiconductor layer and having a higher impurity concentration than the above first semiconductor layer, and a first electrode connected to the above second contact layer and the above emitter electrode.

[0015] The area of the above second contact layer of the above diode near the boundary portion close to the boundary between the above IGBT region and the above diode region is smaller than the area of the above second contact layer of the above diode at a position far from the vicinity of the above boundary portion.

[0016] Effects of the invention

[0017] According to the present invention, in a semiconductor device having an IGBT region and a diode region in the same chip, it is possible to suppress the inflow of carriers from the diode region into the IGBT region during the recovery of the diode, and prevent the carriers from concentrating at the boundary portion and causing element breakdown. Description of the drawings

[0018] Figure 1 It is a perspective view showing the schematic structure of the semiconductor device of Embodiment 1.

[0019] Figure 2 It is a top view of the semiconductor device of Embodiment 1.

[0020] Figure 3 It is a top view of the semiconductor device of Embodiment 2.

[0021] Figure 4 It is a top view of the semiconductor device of Embodiment 3. Detailed description of the invention

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each figure and each embodiment, the same or similar components are denoted by the same reference numerals and repeated descriptions are omitted.

[0023] Embodiment 1

[0024] Figure 1 FIG. is a perspective view schematically showing the structure of the semiconductor device of Embodiment 1. Figure 2 FIG. is a top view of the semiconductor device of Embodiment 1.

[0025] As Figure 1 shown, the semiconductor device 1 is an RC-IGBT having an IGBT region 21 and a diode region 22 in the same chip.

[0026] The IGBT in the IGBT region 21 has a drift layer 2 of a first conductivity type (n-type in Figure 1 ), a body layer 3 of a second conductivity type (p-type in Figure 1 ), a first contact layer 5 of the second conductivity type that is connected to the body layer 3 and has a higher impurity concentration than the body layer 3, and an emitter electrode (not shown) that is connected to the first contact layer 5. In addition, as described later, the conductivity type of the semiconductor layer is not limited to Figure 1 the example shown, and the n-type and p-type can be swapped. Also, as described later, the impurity concentrations such as n-, p+ are just examples and can be appropriately changed within the range where the desired operation can be performed.

[0027] In addition, the IGBT region 21 is an IGBT having a trench gate 6, a gate insulating film 7, an emitter layer 4 of the first conductivity type connected to the body layer 3, a collector layer 9 of the second conductivity type provided on the back side of the drift layer 2, and a collector electrode 10 connected to the collector layer 9. The collector electrode 10 is also connected to the second electrode 16 of the diode region 22 described later. And the IGBT in the IGBT region 21 preferably has a buffer layer 8 of the first conductivity type, and the buffer layer 8 of the first conductivity type is provided between the drift layer 2 and the collector layer 9 and has a higher impurity concentration than the drift layer 2.

[0028] The trench gate 6 and the gate insulating film 7 are formed in a trench that penetrates the body layer 3 and reaches the drift layer 2. The trench gate 6 is formed of, for example, polysilicon. A gate potential G is applied to the trench gate 6.

[0029] The first contact layer 5 makes an ohmic contact with the emitter electrode (not shown) through a contact hole formed in an interlayer insulating film (not shown). An emitter potential E is applied to the first contact layer 5. In addition, the emitter layer 4 makes an ohmic contact with the emitter electrode (not shown) through a contact hole formed in an interlayer insulating film (not shown) or is connected to the emitter electrode (not shown) through the first contact layer 5.

[0030] The diode in the diode region 22 has a first semiconductor layer 11 of a second conductivity type, a second contact layer 12 of the second conductivity type that is connected to the first semiconductor layer 11 and has a higher impurity concentration than the first semiconductor layer 11, and a first electrode (not shown) that is connected to the second contact layer 12 and an emitter electrode (not shown).

[0031] In addition, the diode in the diode region 22 has a drift layer 2 provided on the back side of the first semiconductor layer 11, a second semiconductor layer 15 of a first conductivity type provided on the back side of the drift layer 2 and having a higher impurity concentration than the drift layer 2, and a second electrode 16 connected to the second semiconductor layer 15.

[0032] Here, as Figure 1 shown, when the first conductivity type is n-type and the second conductivity type is p-type, the first semiconductor layer 11 is an anode layer, the first electrode (not shown) is an anode electrode, the second semiconductor layer 15 is a cathode layer, and the second electrode 16 is a cathode electrode.

[0033] In the diode region 22, an interlayer insulating film is not formed, the high-concentration second contact layer 12 makes an ohmic contact with the first electrode (not shown), and an anode potential A having the same potential as the emitter potential E is applied to the second contact layer 12. In addition, the low-concentration first semiconductor layer 11 makes a Schottky junction with the first electrode (not shown).

[0034] In addition, when the first conductivity type is p-type and the second conductivity type is n-type, the first semiconductor layer 11 is a cathode layer, the first electrode (not shown) is a cathode electrode, the second semiconductor layer 15 is an anode layer, and the second electrode 16 becomes an anode electrode.

[0035] In addition, a buffer layer 8 is preferably also formed in the diode region 22.

[0036] In the diode region 22, a trench that penetrates the first semiconductor layer 11 and reaches the drift layer 2 is also formed, and a diode region trench electrode 13 and a diode region trench insulating film 14 are preferably formed in the trench. The diode region trench electrode 13 is formed of, for example, polysilicon. An anode potential A having the same potential as the emitter potential E is preferably applied to the diode region trench electrode 13.

[0037] In the semiconductor device 1 of this embodiment, the injection amount of carriers (as Figure 1 shown, holes when the first conductivity type is n-type and the second conductivity type is p-type) during diode conduction can be controlled according to the ratio of the high-concentration second contact layer 12 formed on the surface to the low-concentration first semiconductor layer 11. If the second contact layer 12 is larger, more carriers are injected, and if the first semiconductor layer 11 is larger, the injection of carriers can be suppressed.

[0038] Therefore, in the semiconductor device 1 of this embodiment, the area of the second contact layer 12 of the diode near the boundary portion 24 near the boundary portion 23 between the IGBT region 21 and the diode region 22 is smaller than the area of the second contact layer 12 of the diode at a position far from the boundary portion 24 near the boundary portion. As a result, the amount of carrier injection when the diode near the boundary portion 24 is turned on is smaller than the amount of carrier injection of the diode at a position far from the boundary portion 24 near the boundary portion. Even if the diode recovers and carriers near the boundary portion 24 flow into the IGBT region 21 side, the amount of carrier injection can be suppressed. Therefore, it is possible to suppress the inflow of carriers from the diode region 22 into the IGBT region 21 when the diode recovers and the concentration of carriers at the boundary portion 23, resulting in component breakdown.

[0039] In addition, in Figure 1 , the drift layer 2 is described as a low-concentration n-type, the body layer 3 and the first semiconductor layer 11 are described as low-concentration p-types, the emitter layer 4 and the second semiconductor layer 15 are described as high-concentration n+-types, the first contact layer 5 and the second contact layer 12 are described as high-concentration p+-types, and the others are described as n-type or p-type, but this is not limited thereto, and can be appropriately changed within the range where the desired operation can be performed.

[0040] In addition, when the first conductivity type is p-type and the second conductivity type is n-type, the carriers are electrons instead of holes, so the description of holes related to the carriers can be replaced with electrons.

[0041] Embodiment 2

[0042] Figure 3 is a top view of the semiconductor device of Embodiment 2.

[0043] Embodiment 2 is a modified example of Embodiment 1. The difference between the semiconductor device 1 of this embodiment and that of Embodiment 1 is that the area of the second contact layer 12 near the boundary portion 24 gradually decreases as it approaches the boundary portion 23. As a result, at a portion of the boundary portion 24 far from the boundary portion 23, while injecting carriers to a certain extent to reduce the forward voltage, the concentration of carriers at the boundary portion 23 can be suppressed. Other than this, it is the same as Embodiment 1, so the description is omitted.

[0044] Embodiment 3

[0045] Figure 4 is a top view of the semiconductor device of Embodiment 3.

[0046] Embodiment 3 is a modified example of Embodiment 2. The difference between the semiconductor device 1 of this embodiment and that of Embodiment 2 is that the second contact layer 12 is not provided in the region of the diode region 22 that is in contact with the boundary portion 23. Thus, similar to Embodiment 2, in the portion near the boundary portion 24 that is away from the boundary portion 23, carriers are injected to some extent to reduce the forward voltage, and compared with Embodiment 2, the effect of suppressing the concentration of carriers at the boundary portion 23 can be improved. Other than this, it is the same as Embodiment 2, so the description is omitted.

[0047] In addition, the structure of Embodiment 3 can also be applied to Embodiment 1. In this case, the effect of reducing the forward voltage is weaker than that of Embodiment 2, but the effect of suppressing the concentration of carriers at the boundary portion 23 is higher than that of Embodiment 1.

[0048] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the structures described in the embodiments, and various changes can be made within the scope of the technical idea of the present invention. In addition, a part or all of the structures described in each embodiment can be combined and applied.

[0049] Description of reference numerals

[0050] 1 - Semiconductor device, 2 - Drift layer, 3 - Body layer, 4 - Emitter layer, 5 - First contact layer, 6 - Trench gate, 7 - Gate insulating film, 8 - Buffer layer, 9 - Collector layer, 10 - Collector electrode, 11 - First semiconductor layer, 12 - Second contact layer, 13 - Diode region trench electrode, 14 - Diode region trench insulating film, 15 - Second semiconductor layer, 16 - Second electrode, 21 - IGBT region, 22 - Diode region, 23 - Boundary portion, 24 - Near the boundary portion, G - Gate potential, E - Emitter potential, A - Anode potential.

Claims

1. A semiconductor device having an IGBT region and a diode region within the same chip, characterized in that, the IGBT in the above IGBT region has a drift layer of a first conductivity type, a body layer of a second conductivity type, a first contact layer of the second conductivity type connected to the above body layer and having an impurity concentration higher than that of the above body layer, and an emitter electrode connected to the above first contact layer, the diode in the above diode region has a first semiconductor layer of the second conductivity type, a second contact layer of the second conductivity type connected to the above first semiconductor layer and having an impurity concentration higher than that of the above first semiconductor layer, and a first electrode connected to the above second contact layer and the above emitter electrode, the area of the above second contact layer of the above diode near the boundary portion close to the boundary between the above IGBT region and the above diode region is smaller than the area of the above second contact layer of the above diode at a position far from the vicinity of the above boundary portion.

2. The semiconductor device according to claim 1, characterized in that, the area of the above second contact layer near the above boundary portion gradually decreases as it approaches the above boundary portion.

3. The semiconductor device according to claim 1, characterized in that, the above second contact layer is not provided in the region of the above diode region that abuts on the above boundary portion.

4. The semiconductor device according to claim 1, characterized in that, the above diode has a drift layer provided on the back side of the above first semiconductor layer, a second semiconductor layer of the first conductivity type provided on the back side of the above drift layer and having an impurity concentration higher than that of the above drift layer, and a second electrode connected to the above second semiconductor layer.

5. The semiconductor device according to claim 4, characterized in that, the above IGBT has a trench gate, a gate insulating film, an emitter layer of the first conductivity type connected to the above body layer, a collector layer of the second conductivity type provided on the back side of the above drift layer, and a collector electrode connected to the above collector layer and the above second electrode.

6. The semiconductor device according to claim 5, characterized in that, it has a buffer layer of the first conductivity type, and the buffer layer of the first conductivity type is provided between the above drift layer and the above collector layer and has an impurity concentration higher than that of the above drift layer.

7. The semiconductor device according to claim 1, characterized in that, the above first conductivity type is n-type, the above second conductivity type is p-type, the above first semiconductor layer is an anode layer, and the above first electrode is an anode electrode.

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