Semiconductor devices and power converters

Abstract

To provide a semiconductor device and a power conversion device that reduce the areas of a p-body layer of a diode portion of an RC-IGBT to restrain hole injection and improve recovery characteristics.SOLUTION: An RC-IGBT of a semiconductor device 100 includes two body layers 5, a first trench 13 provided between the body layers, a first gate electrode 7 which is formed on a side wall on a first body layer side through a gate insulating film, and a second gate electrode 16 which is formed on a side wall on the second body layer side through a gate insulating film. The first gate electrode and the second gate electrode are spaced from each other with a first insulating film 14a interposed therebetween. A diode has two body layers 5 and a trench 13 provided therebetween. The trench 13 of the diode includes a first electrode 10 which is formed on a side wall on a third body layer side through an insulating film, and a second electrode 17 which is formed on the side wall on the third body layer side through the insulating film. Both the electrodes are spaced from each other through a second insulating film 14a interposed therebetween.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a semiconductor device and a power conversion device.

Background Art

[0002] A reverse-conducting IGBT (hereinafter referred to as "RC-IGBT") incorporating an IGBT (Insulated Gate Bipolar Transistor) and a diode in the same chip has the following advantages: (1) reduction of chip size by sharing the termination regions of the IGBT and the diode, and (2) reduction of thermal resistance because losses generated in the IGBT region or the diode region are dissipated over the entire chip. On the other hand, since the IGBT and the diode are fabricated in the same chip, it is difficult to optimize each chip simultaneously. In particular, it is difficult to control the lifetime of the diode portion, and reducing the low injection of the diode and the recovery loss are issues.

[0003] <0000​​​​​​​​​​​​ Japanese Patent Publication No. 2008-53648 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the above-mentioned Patent Document 1, hole injection is suppressed by reducing the area of ​​the P-base layer 2 (p-body layer) of the diode portion of the RC-IGBT. However, in the method of Patent Document 1, the area of ​​the p-body layer is reduced by making the trench spacing smaller, so there is a limit to how much the area of ​​the p-body layer can be reduced due to the limitations of trench processing.

[0006] In view of the above circumstances, the present invention provides a semiconductor device and a power converter that can reduce the p-body layer area of ​​the diode portion of an RC-IGBT to suppress hole injection and improve recovery characteristics. [Means for solving the problem]

[0007] One aspect of the present invention that solves the above problems is an RC-IGBT having an IGBT section and a diode section in a single chip, Department The diode comprises a first body layer and a second body layer of a first conductivity type, and a first trench provided between the first body layer and the second body layer, wherein the first trench has a first gate electrode formed on the side wall on the first body layer side via a gate insulating film, and a second gate electrode formed on the side wall on the second body layer side via a gate insulating film, and the first gate electrode and the second gate electrode are separated from each other by at least a first insulating film, Department It comprises a third body layer and a fourth body layer of the first conductivity type, and a second trench provided between the third body layer and the fourth body layer, wherein the second trench has a first electrode formed on the side wall on the third body layer side via an insulating film, and 4 It has a second electrode formed on the side wall of the body layer side via an insulating film, and the first electrode and the second electrode are separated from each other via at least a second insulating film. Furthermore, a second conductive layer is provided on the upper surface of the first and second body layers, while a second conductive layer is not provided on the upper surface of the third and fourth body layers. This semiconductor device is characterized by the following features.

[0008] Furthermore, another aspect of the present invention for solving the above problems is a power conversion device having a pair of DC terminals, an AC terminal number equal to the number of phases of the AC output, a switching leg number equal to the number of phases of the AC output, which is connected in series between the pair of DC terminals and consists of two parallel circuits, each consisting of a switching element and a diode connected antiparallel to the switching element, and a gate circuit for controlling the switching element, wherein the diode and Switching element The child The power conversion device is characterized by being a semiconductor device as described above.

[0009] A more specific configuration of the present invention is described in the claims. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a semiconductor device and a power converter that can reduce the p-body layer area of ​​the diode portion of an RC-IGBT, thereby suppressing hole injection and improving recovery characteristics.

[0011] Furthermore, issues, configurations, and effects other than those mentioned above will be clarified by the description of the embodiments below. [Brief explanation of the drawing]

[0012] [Figure 1] A schematic cross-sectional view showing a first example of the semiconductor device of the present invention. [Figure 2] A schematic cross-sectional view showing a second example of the semiconductor device of the present invention. [Figure 3] A schematic cross-sectional view showing a third example of the semiconductor device of the present invention. [Figure 4] Circuit diagram showing the schematic configuration of the power conversion device of the present invention. [Modes for carrying out the invention]

[0013] The present invention will now be described in detail with reference to the drawings.

[0014] [Semiconductor device] Figure 1 is a schematic cross-sectional view showing a first example of the semiconductor device of the present invention. As shown in Figure 1, the semiconductor device (RC-IGBT) 100 of the present invention has an IGBT portion and a diode portion. It has a structure in which a collector electrode layer / cathode electrode layer 1, a collector layer / cathode layer 2, a buffer layer 3, a drift layer 4 and a body layer 5, an insulating layer 14 and an emitter / anode electrode layer 6 are stacked from the back side toward the front side. Note that the conductivity types "p" and "n" in Figure 1 may be reversed.

[0015] The surface structure of both the IGBT and diode sections includes two body layers 5 and a trench 13 sandwiched between the body layers 5. The body layers on the IGBT side are designated as the first body layer and the second body layer, while the body layers on the diode side are designated as the third body layer and the fourth body layer. Furthermore, the trench provided between the first and second body layers is designated as the first trench, and the trench provided between the third and fourth body layers is designated as the second trench.

[0016] In the IGBT trench 13 (first trench), a polysilicon gate electrode (first gate electrode) 7 is formed on the side wall on the first body layer 5 side via a gate insulating film 12. A polysilicon gate electrode (second gate electrode) 16 is formed on the side wall on the second body layer 5 side via a gate insulating film 12. The two gate electrodes 7 and 16 are separated by an insulating film 14a connected to an insulating film 14, and a polysilicon emitter electrode 8 is formed between the two gate electrodes 7 and 16, separated by the insulating film 14a and connected to the emitter / anode electrode layer 6.

[0017] In the trench 13 (second trench) of the Diode section, a polysilicon electrode (first electrode) 10 is formed on the side wall on the side of the third body layer 5 via an insulating film 15, and a polysilicon electrode (second electrode) 17 is formed on the side wall 15 on the side of the fourth body layer 5 via an insulating film. Between the two electrodes 10 and 17, they are separated via an insulating film 14a, and between the two gate electrodes 10 and 17, there is a polysilicon anode electrode 11 that is separated via an insulating film 14a and connected to the emitter / anode electrode layer 6.

[0018] The trench 13 (third trench) at the boundary between the IGBT section and the Diode section has a polysilicon electrode (third electrode) 19 formed on the side wall on the side of the second body layer 5 via an insulating film 15, and a polysilicon electrode (fourth electrode) 20 formed on the side wall 15 on the side of the fourth body layer 5 via an insulating film. Between the two electrodes 19 and 20, they are separated via an insulating film 14a, and between the two gate electrodes 19 and 20, there is a polysilicon emitter / anode electrode 18 that is separated via an insulating film 14a and connected to the emitter / anode electrode layer 6.

[0019] Also, an n+ layer is provided in the first and second body layers of the IGBT section, and an n+ layer is not provided in the third and fourth body layers of the Diode section.

[0020] The feature of the semiconductor device 100 shown in FIG. 1 is that in the Diode section, the width W_DT of the trench 13 is wider than the width W_Dp of the body layer 5. Thereby, the body layer area of the Diode section can be reduced, and hole injection in the Diode section can be suppressed.

[0021] Also, since the opposite side of the body layer side of the IGBT section is covered with a thick insulating film 12, the gate capacitance can be reduced.

[0022] Figure 2 is a schematic cross-sectional view showing a second example of the semiconductor device of the present invention. A feature of the semiconductor device 200 shown in Figure 2 is that the width W_Dt of the trench 13 in the diode section is different from the width W_IT of the trench 13 in the IGBT section. By changing the width W_Dt of the trench 13 in the diode section in this way, the area of ​​the body layer 5 is changed, and hole injection can be controlled. Therefore, the trade-off between forward voltage and recovery loss can be adjusted without lifetime control, and the characteristics of the diode section can be controlled independently of the IGBT section.

[0023] Note that in Figure 2, W_DT > W_IT is assumed, but W_IT > W_DT is also acceptable.

[0024] Figure 3 is a schematic cross-sectional view showing a third example of the semiconductor device of the present invention. A feature of the semiconductor device 300 shown in Figure 3 is that the width W_BT of the trench 13 provided at the boundary between the IGBT portion and the diode portion is wider than the width W_IT of the trench 13 in the IGBT portion.

[0025] In RC-IGBTs, during the recovery of the diode portion, holes may flow into the IGBT portion at the boundary with the diode portion, potentially causing the element to be destroyed at the boundary. Therefore, in the semiconductor device 300 shown in Figure 3, by widening the width W_BT of the trench 13 provided at the boundary between the diode portion and the IGBT portion, the distance between the diode portion and the IGBT portion can be increased, thereby suppressing the flow of holes into the IGBT portion at the boundary with the diode portion as described above, and thus preventing damage to the device.

[0026] [Power converter] Figure 8 is a circuit diagram showing the schematic configuration of the power conversion device of the present invention. Figure 8 shows an example of the circuit configuration of the power conversion device 500 of this embodiment and the relationship between the DC power supply and the three-phase AC motor (AC load).

[0027] In the power conversion device 500 of this embodiment, the semiconductor device of the present invention is used as elements 521 to 526.

[0028] As shown in Figure 8, the power converter 500 of this embodiment includes a pair of DC terminals, P terminal 531 and N terminal 532, and AC terminals, U terminal 533, V terminal 534 and W terminal 535, which are the same number as the number of phases of the AC output.

[0029] Furthermore, it includes a switching leg consisting of a series connection of a pair of power switching elements 501 and 502, with a U terminal 533 connected to the series connection point as its output. It also includes a switching leg consisting of a series connection of power switching elements 503 and 504 having the same configuration, with a V terminal 534 connected to the series connection point as its output. Furthermore, it includes a switching leg consisting of a series connection of power switching elements 505 and 506 having the same configuration, with a W terminal 535 connected to the series connection point as its output.

[0030] The three-phase switching legs, consisting of power switching elements 501 to 506, are connected between the DC terminals P terminal 531 and N terminal 532, and DC power is supplied from a DC power supply (not shown). The three-phase AC terminals U terminal 533, V terminal 534, and W terminal 535 of the power converter 500 are connected as a three-phase AC power supply to a three-phase AC motor (not shown).

[0031] Diodes 521 to 526 are connected in antiparallel to each of the power switching elements 501 to 506. For example, gate circuits 511 to 516 are connected to the input terminals of the gates of each of the power switching elements 501 to 506, which are IGBTs, and the power switching elements 501 to 506 are controlled by the gate circuits 511 to 516. The gate circuits 511 to 516 are controlled collectively by a control circuit (not shown).

[0032] The gate circuits 511-516 comprehensively and appropriately control the power switching elements 501-506 so that the DC power from the DC power supply Vcc is converted into three-phase AC power, which is output from terminals U 533, V 534, and W 535.

[0033] By applying the semiconductor device (RC-IGBT) of the present invention to the power conversion device 500, the power switching elements 501 to 506 and the diodes 521 to 526 can be combined into a single unit, thereby enabling miniaturization of the device. Furthermore, as described above, by using the semiconductor device of the present invention, it is possible to provide a power conversion device with improved recovery characteristics of the diode section.

[0034] In summary, the present invention provides a semiconductor device and a power converter that can reduce the p-body layer area of ​​the diode portion of an RC-IGBT, thereby suppressing hole injection and improving recovery characteristics.

[0035] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are specifically explained in order to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. [Explanation of Symbols]

[0036] 1...Collector electrode layer / cathode electrode layer, 2...Collector layer / cathode layer, 3...Buffer layer, 4...Drift layer, 5...Body layer, 6...Emitter electrode layer / anode electrode layer, 7...Polysilicon electrode (gate), 8...Polysilicon electrode (emitter), 10...Polysilicon electrode (gate / anode), 11...Polysilicon electrode (anode), 12...Insulating layer, 13...Trench, 14,14a,15...Insulating layer, 16...Polysilicon electrode (gate), 17...Polysilicon Polysilicon electrode (gate / anode), 18...Polysilicon electrode (emitter / anode), 19...Polysilicon electrode (gate / anode), 20...Polysilicon electrode (gate / anode), 100, 200, 300...Semiconductor equipment, 500...Power converter, 501~506...Power switching element, 511~516...Gate circuit, 521~526...Diode, 531...P terminal, 532...N terminal, 533...U terminal, 534...V terminal, 535...W terminal.

Claims

1. In an RC-IGBT having an IGBT section and a diode section within a single chip, The IGBT portion includes a first body layer and a second body layer of a first conductivity type, and a first trench provided between the first body layer and the second body layer. The first trench has a first gate electrode formed on the sidewall on the first body layer side via a gate insulating film, and a second gate electrode formed on the sidewall on the second body layer side via a gate insulating film, and the first gate electrode and the second gate electrode are separated from each other by at least a first insulating film. The diode portion comprises a third body layer and a fourth body layer of the first conductivity type, and a second trench provided between the third body layer and the fourth body layer. The second trench has a first electrode formed on the side wall on the third body layer side via an insulating film, and a second electrode formed on the side wall on the fourth body layer side via an insulating film, and the first electrode and the second electrode are spaced apart with at least a second insulating film between them. A semiconductor device characterized in that a second conductivity type layer is provided on the upper surface of the first body layer and the second body layer, and the second conductivity type layer is not provided on the upper surface of the third body layer and the fourth body layer.

2. In the semiconductor device described in claim 1, A semiconductor device characterized in that the width of the second trench is greater than the widths of the third body layer and the fourth body layer.

3. In the semiconductor device described in claim 1, A semiconductor device characterized in that the width of the first trench and the width of the second trench are different.

4. In the semiconductor device according to any one of claims 1 to 3, A semiconductor device having a third trench at the boundary between the IGBT portion and the diode portion, wherein the width of the third trench is greater than the width of the first trench.

5. A pair of DC terminals, The same number of AC terminals as the number of phases of the AC output, Two parallel circuits, each consisting of a switching element and a diode connected in antiparallel to the switching element, are connected in series between the pair of DC terminals, and the number of switching legs is equal to the number of phases of the AC output. A power conversion device having a gate circuit for controlling the switching element, The power conversion device is characterized in that the diode and the switching element are semiconductor devices as described in claim 1.

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