Composite semiconductor devices and nitride-based semiconductor devices

Abstract

To provide a composite semiconductor device capable of reducing parasitic inductance. [Solution] A composite semiconductor device 100 comprises a first switching element 200 and a second switching element 300 with lower breakdown voltage, wherein the source electrode of the first switching element and the drain electrode of the second switching element are electrically connected. The first switching element includes a drain electrode 10, a source electrode 8, and a gate electrode 7 connected to the upper surface of a wide bandgap semiconductor and arranged extending in the D1 direction in a plan view. Each electrode has multiple active portions 201 arranged side by side in the D2 direction intersecting the D1 direction, an insulating film 203 arranged on the upper surface of the wide bandgap semiconductor outside the active portions so as to sandwich the active portions in the D1 direction in a plan view, a drain pad electrode 210 connected to the drain electrode, and a source wiring 208 which also serves as a source pad electrode connecting adjacent source electrodes. The second switching element is installed on top of the first switching element.

Description

Technical Field

[0001] The present disclosure relates to a compound semiconductor device and a nitride semiconductor device.

Background Art

[0002] Devices with increased breakdown voltage using wide-bandgap semiconductors such as GaN and SiC have attracted attention. However, these normally-off devices have not yet fully solved problems such as a low gate voltage threshold, a large gate leakage current, and the occurrence of current collapse phenomena. Therefore, a structure that provides a high-breakdown-voltage pseudo-normally-off device using a cascode circuit combining a normally-on high-breakdown-voltage FET formed of a wide-bandgap semiconductor and a low-breakdown-voltage MOSFET formed of silicon is disclosed in Patent Document 1 and the like.

[0003] Currently, the mainstream of high-breakdown-voltage FETs is a lateral device in which source, gate, and drain electrodes are arranged on the upper surface of a wide-bandgap semiconductor. On the other hand, the mainstream of low-breakdown-voltage MOSFETs is a vertical device in which a drain electrode is arranged on the back side of a silicon substrate and source and gate electrodes are arranged on the front side.

[0004] Therefore, in Patent Document 1, in order to electrically connect the drain electrode of the low-breakdown-voltage MOSFET and the source electrode of the high-breakdown-voltage FET, the source electrode is electrically connected to the conductive electrode on the back surface through a through VIA in a high-breakdown-voltage FET (such as a GaN chip) with the back surface facing up, and a Si-MOSFET is stacked and connected on the conductive electrode.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Figure 8 of Patent Document 1 shows a cascode connection circuit. In Patent Document 1, the source electrode is connected to the conductive electrode on the back surface via a via, and Si-MOSFETs are stacked on the conductive electrode. However, providing through holes such as vias reduces the crystallinity of the wide-bandgap semiconductor. Furthermore, if vias cannot be provided near the active region where many semiconductor elements are located, parasitic inductance occurs. Figure 9 is a diagram of the cascode connection circuit described in Figure 8 of Patent Document 1 with the above-mentioned parasitic inductance added.

[0007] When the high-voltage FET 200A is turned on and current flows between the drain electrode 10 and the source electrode 8, the back electromotive force of the parasitic inductance causes the voltage between the gate electrode 7 and the source electrode 8 of the high-voltage FET 200A to drop, increasing the on-resistance of the high-voltage FET 200A.

[0008] Furthermore, turning off the high-voltage FET 200A causes the drain voltage of the Si-MOSFET 300A to rise due to the back electromotive force of the parasitic inductance, which can lead to problems such as avalanche breakdown of the Si-MOSFET 300A or even the destruction of the Si-MOSFET 300A.

[0009] Alternatively, one method involves stacking Si-MOSFETs by placing the source pad electrode of the high-voltage FET above the upper surface of the active portion of the high-voltage FET. However, in this case, it is necessary to ensure sufficient distance, taking into account the voltage breakdown between the drain electrode of the high-voltage FET and the drain electrode of the Si-MOSFET. As a result, there is a problem in that the parasitic inductance between the source electrode of the high-voltage FET and the drain electrode of the Si-MOSFET becomes large.

[0010] This disclosure was made to solve the above problems and aims to provide a composite semiconductor device capable of reducing parasitic inductance and a nitride-based semiconductor device that can be used in the composite semiconductor device. [Means for solving the problem]

[0011] This disclosure has been made to achieve the above objective, and provides a composite semiconductor device comprising a first switching element and a second switching element having a lower breakdown voltage than the first switching element, wherein the source electrode of the first switching element and the drain electrode of the second switching element are electrically connected, the first switching element includes a drain electrode, a source electrode, and a gate electrode provided between the drain electrode and the source electrode, which are connected to the upper surface of a wide bandgap semiconductor and arranged to extend in a first direction in a plan view of the first switching element, and each of the drain electrode, the gate electrode and the source electrode has multiple active portions arranged side by side in a second direction intersecting the first direction, and source wiring which also serves as a drain pad electrode connected to the drain electrode and a source pad electrode connecting adjacent source electrodes, which are arranged on the upper surface of the wide bandgap semiconductor outside the active portions via an insulating film so as to sandwich the active portions in the first direction in a plan view of the first switching element, and the second switching element is installed on the source pad electrode via a conductive adhesive.

[0012] Such a composite semiconductor device makes it possible to reduce parasitic inductance.

[0013] In this case, the wide-bandgap semiconductor can be a composite semiconductor device in which a first and second nitride-based semiconductor layer is stacked, a two-dimensional electron gas layer is formed in the first nitride-based semiconductor layer of the active portion, and a groove reaching the first nitride-based semiconductor layer is provided between the active portion and the source pad electrode, or the first nitride-based semiconductor layer below the source pad electrode has a region in which the two-dimensional electron gas layer is not formed.

[0014] This reduces the influence of leakage current from around the pad electrodes, and also reduces the influence of parasitic capacitance between the two-dimensional electron gas layer and the two-dimensional hole gas layer.

[0015] In this case, a composite semiconductor device can be provided that does not have the second nitride-based semiconductor layer below the source pad electrode.

[0016] This reduces the influence of leakage current from around the pad electrodes, and also reduces the influence of parasitic capacitance between the two-dimensional electron gas layer and the two-dimensional hole gas layer.

[0017] In this case, a composite semiconductor device can be formed comprising a third nitride-based semiconductor layer disposed on the active portion of the second nitride-based semiconductor, and a p-type semiconductor layer connected to the gate electrode and disposed on the third nitride-based semiconductor layer, wherein the third nitride-based semiconductor layer is extended toward the drain electrode side than the p-type semiconductor layer.

[0018] This allows for a reduction in on-resistance.

[0019] In this case, a composite semiconductor device can be provided, comprising a protective film having a first opening and a second opening that covers the source wiring, the second switching element being installed on the first source pad region of the first opening, and a detection terminal for adjusting the drive voltage of the gate electrode electrically connected to the second source pad region of the second opening.

[0020] This makes it possible to create a composite semiconductor device with stable, low on-resistance.

[0021] The present disclosure also relates to a nitride semiconductor device including a first nitride semiconductor layer, a second nitride semiconductor layer provided on the first nitride semiconductor layer and composed of a nitride semiconductor having a larger bandgap energy than the first nitride semiconductor layer, and a third nitride semiconductor layer provided on the first nitride semiconductor layer and composed of a nitride semiconductor having a smaller bandgap energy than the second nitride semiconductor layer. The device further includes a drain electrode, a source electrode, and a gate electrode disposed between the drain electrode and the source electrode and extending in a first direction in plan view. Each of the drain electrode, the gate electrode, and the source electrode has a plurality of juxtaposed active portions in a second direction intersecting the first direction. A source wiring that also serves as a drain pad electrode connected to the drain electrode and a source pad electrode connecting adjacent source electrodes is disposed on the upper surface of the first nitride semiconductor layer outside the active portion via an insulating film so as to sandwich the active portion in the first direction in plan view.

[0022] The nitride semiconductor device of the present disclosure can be applied to the above composite semiconductor device.

Advantages of the Invention

[0023] As described above, according to the composite semiconductor device of the present disclosure, it is possible to reduce parasitic inductance. Also, according to the nitride semiconductor device of the present disclosure, it can be applied to the above composite semiconductor device.

Brief Description of the Drawings

[0024] [Figure 1] A drawing showing an example (plan view) of a composite semiconductor device according to the present disclosure. [Figure 2] An enlarged cross-sectional view showing an active portion (active region) of a first switching element according to the present disclosure. [Figure 3] An enlarged cross-sectional view of a source pad electrode portion of a first switching element in which a second switching element is disposed in the composite semiconductor device according to the present disclosure. [Figure 4] This figure shows the cascode connection circuit and its peripheral circuit of the composite semiconductor device relating to this disclosure. [Figure 5] This is a drawing (plan view) showing the first switching element (nitride-based semiconductor device) related to this disclosure. [Figure 6] This is a drawing (plan view) showing the first switching element (nitride-based semiconductor device) related to this disclosure, and shows an enlarged cross-sectional view of the source pad electrode portion before the second switching element is placed. [Figure 7] This is a drawing showing an example (cross-sectional view) of the second switching element related to this disclosure. [Figure 8] This drawing shows an example (plan view) of a conventional composite semiconductor device. [Figure 9] This is a diagram showing a cascode connection circuit as described in Figure 8 of Patent Document 1, with parasitic inductance added. [Modes for carrying out the invention]

[0025] The disclosure is described in detail below, but is not limited to this.

[0026] As described above, there was a need for a composite semiconductor device capable of reducing parasitic inductance, and a nitride-based semiconductor device that could be used in said composite semiconductor device.

[0027] As a result of diligent study on the above problems, the present inventors have provided a composite semiconductor device comprising a first switching element and a second switching element having a lower breakdown voltage than the first switching element, wherein the source electrode of the first switching element and the drain electrode of the second switching element are electrically connected, and the first switching element includes a drain electrode, a source electrode, and a gate electrode provided between the drain electrode and the source electrode, which are connected to the upper surface side of a wide bandgap semiconductor and arranged to extend in a first direction in a plan view of the first switching element, and the drain electrode, the gate electrode and the source electrode We have discovered that a composite semiconductor device can reduce parasitic inductance, comprising: each electrode having multiple active portions arranged side-by-side in a second direction intersecting the first direction; and source wiring that serves as both a drain pad electrode connected to the drain electrode and a source pad electrode connecting adjacent source electrodes, arranged via an insulating film on the upper surface of the wide bandgap semiconductor outside the active portions, sandwiching the active portions in the first direction in a plan view of the first switching element, with the second switching element mounted on the source pad electrodes via a conductive adhesive.

[0028] The inventors also provide a first nitride-based semiconductor layer, a second nitride-based semiconductor layer provided on the first nitride-based semiconductor layer and composed of a nitride-based semiconductor having a larger bandgap energy than the first nitride-based semiconductor layer, a third nitride-based semiconductor layer provided on the first nitride-based semiconductor layer and composed of a nitride-based semiconductor having a smaller bandgap energy than the second nitride-based semiconductor layer, and a drain electrode, a source electrode, and a gate electrode provided between the drain electrode and the source electrode, arranged in a plan view stretched in a first direction. We have found that a nitride-based semiconductor device can be applied to the above-mentioned composite semiconductor device, and have completed this disclosure, which includes a plurality of active portions in which the drain electrode, gate electrode, and source electrode are each arranged side by side in a second direction intersecting the first direction, and in a plan view, the active portions are sandwiched in the first direction, and the source wiring, which also serves as a drain pad electrode connected to the drain electrode and a source pad electrode connecting adjacent source electrodes, is arranged on the upper surface of the first nitride-based semiconductor layer outside the active portions via an insulating film, and the active portions include a drain pad electrode connected to the drain electrode and a source pad electrode connecting adjacent source electrodes.

[0029] The following explanation will be given with reference to the drawings.

[0030] [Composite semiconductor device] Figure 1 shows an example (plan view) of the composite semiconductor device 100 according to this disclosure. Figure 2 is a cross-sectional view of the active portion (active region) 201 of the first switching element according to this disclosure, taken in the direction of D2 and viewed in the direction of D1. Figure 3 is an enlarged cross-sectional view of the source pad electrode portion of the first switching element on which the second switching element is arranged in the composite semiconductor device 100 according to this disclosure. Note that in Figure 1, the protective films 224A, 224B and conductive adhesives 110A, 110B, etc., shown in Figure 3 are omitted in order to clarify the positional relationship of each component.

[0031] The composite semiconductor device 100 of this disclosure comprises a first switching element 200 and a second switching element 300 having a lower voltage rating than the first switching element 200. As shown in Figure 3, the source electrode 8 of the first switching element 200 and the drain electrode 356 of the second switching element 300 are electrically connected via a source wiring 208. In a plan view of the composite semiconductor device 100, the second switching element 300 is mounted on a first source pad region 225 located outside the active portion 201 of the first switching element 200, but the second switching element 300 is not mounted on the active portion 201 of the first switching element 200.

[0032] The first switching element 200 may be fixed to the metal plate 120 via a conductive adhesive 110A such as Ag paste. The drain electrode 356 of the second switching element 300 is fixed and installed on the first source pad region 225 of the first switching element 200 via a conductive adhesive 110B. Other pad electrodes of the first switching element 200 and the second switching element 300 are connected to their respective external lead terminals (gate input terminal 130A, drain terminal 130B, source terminal 130C, gate terminal (nitride semiconductor) 130D) via wires 140 or metal plates. The first switching element 200, the second switching element 300, and some of their respective external lead terminals are covered with a molded resin (not shown).

[0033] Furthermore, as shown in Figures 1, 3, and 5, protective films 224A and 224B, having a first opening 221 and a second opening 222, are provided to cover the source wiring 208, with the first source pad region 225 corresponding to the portion of the source wiring 208 in the first opening 221, and the second source pad region 226 corresponding to the portion of the source wiring 208 in the second opening 222. A second switching element is installed on the first source pad region 225 of the first opening 221. And, as shown in Figure 1, it is also preferable to have a detection terminal 250 (a terminal connected to the second source pad region 226; also called a VM terminal) that is electrically connected to the second source pad region 226 in the second opening 222 of the source wiring 208, and monitors the potential of the gate electrode to increase or decrease the potential of the gate electrode in accordance with the potential fluctuation of the gate electrode. For example, if the gate-source voltage of the first switching element 200 decreases due to parasitic inductance when the first switching element 200 is turned on, the gate input voltage of the first switching element 200 can be increased by that amount, and the gate-source voltage of the first switching element 200 can be adjusted to achieve a low on-resistance. Figure 4 shows a cascode connection circuit and its peripheral circuit for such a composite semiconductor device according to the present disclosure.

[0034] Figure 8 shows an example (plan view) of a conventional composite semiconductor device. In Figure 8, a vertical Si-MOSFET 300A and a general high-voltage FET 400 made of nitride semiconductor material are arranged side by side, and the source pad on the top surface of the Si-MOSFET 300A and the source pad of the high-voltage FET 400 are connected by a wire 140. In this case, parasitic inductance due to the wiring occurs at the connection point enclosed by the dotted line of the wire 140. On the other hand, since the composite semiconductor device according to this disclosure does not use connections by wires or vias, it is possible to reduce parasitic inductance.

[0035] (First switching element) The first switching element 200 is not particularly limited, but for example, a normally-on type high-voltage FET formed from a wide-bandgap semiconductor can be used. Here, a more specific form of the first switching element will be described using a normally-on type HEMT, which is a nitride-based semiconductor device formed from GaN, as an example of a normally-on type high-voltage FET formed from a wide-bandgap semiconductor. A normally-on type lateral JFET formed from SiC may also be used.

[0036] Figure 5 is a top view (plan view) of the first switching element 200 according to this disclosure. Figure 6 is an enlarged view of the cross-section including the first source pad region 225, when the cross-section is cut in the direction of -D1 from the left end of the source electrode 8 of the active portion 201 of Figure 5 and viewed in the direction of D2. The right side of the active portion 201 in Figure 6 is a view of the cross-section taken in the direction of D1 from the left end of the source electrode 8, continuously cut in the direction of D2. The second switching element 300 is placed on the source pad region 225 of the first switching element 200 shown in Figures 5 and 6, and wires 140 etc. are provided to form the composite semiconductor device shown in Figure 1.

[0037] Here, a first switching element 200 is described based on a nitride-based semiconductor device equipped with a nitride-based semiconductor, which is a preferred example of a wide-bandgap semiconductor. As shown in Figures 1, 5, and 6, the first switching element 200 includes an active section 201. The active section 201 includes a drain electrode 10, a source electrode 8, and a gate electrode 7 provided between the drain electrode 10 and the source electrode 8, which are connected to the upper surface of the wide-bandgap semiconductor (nitride-based semiconductor layer) 202 and arranged to extend in a first direction D1 in a plan view of the first switching element 200. Multiple drain electrodes 10, gate electrodes 7, and source electrodes 8 are arranged side by side in a second direction D2 that intersects the first direction D1. The arrangement of the drain electrode 10, gate electrodes 7, and source electrodes 8 can be as shown in Figures 1 and 5, such as <-source electrode 8-gate electrode 7-drain electrode 10-gate electrode 7-source electrode 8-gate electrode 7-drain electrode 10->. The adjacent source electrode 8, gate electrode 7, and drain electrode 10 are connected to their respective bus lines (metal wiring), forming a comb-like shape overall.

[0038] As shown in Figures 1, 5, and 6, one side of the gate bus line 217, which is provided on the insulating film 203 on the wide bandgap semiconductor 202 (nitride semiconductor layer) and is positioned in the -D1 direction when viewed from the active part 201, is connected to each gate electrode 7, and the other side of the gate bus line 217 is connected to the gate pad electrode 207. Each drain electrode 10 is connected to the drain pad electrode 210, which also serves as the drain bus line. Each source electrode 8 is connected to the source wiring (bus line) 208, which also serves as the first source pad region 225. Furthermore, the source wiring 208 is a wide solid plane so that a second source pad electrode 226 can also be provided. The exposed portions by opening the protective films 224A and 224B on the wide solid plane become the first source pad region 225 and the second source pad region 226, and the second switching element 300 is installed on the first source pad region 225. In this way, the parasitic inductance caused by the connection between the first switching element 200 and the second switching element 300 can be reduced as much as possible.

[0039] Furthermore, as shown in Figures 1 and 5, in a plan view of the first switching element 200, a drain pad electrode 210 connected to the drain electrode 10 and a source wiring 208 connected to the source electrode 8 are arranged on the upper surface of the wide bandgap semiconductor 202 (nitride-based semiconductor layer) outside the active part 201 via an insulating film 203, sandwiching the active part 201 in the first direction D1. The gate pad electrode 207 is also arranged outside the active part 201. The source wiring 208 and gate pad electrode 207 are arranged in the -D1 direction (left side of the paper) when viewed from the active part 201, and the drain pad electrode 210 is arranged in the +D1 direction (right side of the paper) when viewed from the active part 201. Thus, the source wiring 208, gate pad electrode 207, and drain pad electrode 210 are located outside the active part and outside the groove 220. Therefore, the nitride semiconductor layer beneath the source wiring 208, gate pad electrode 207, and drain pad electrode 210 is either not conductive with the two-dimensional electron gas layer of the active section, or has relatively high resistance. A second switching element 300 (such as a Si-MOSFET), described later, is mounted on the source wiring 208 via a conductive adhesive 110B. On the other hand, the second switching element 300 is not mounted on the active section 201.

[0040] As shown in Figure 2, the wide bandgap semiconductor 202 can be made up of stacked first and second nitride-based semiconductor layers 2 and 3, with a two-dimensional electron gas layer 20 formed in the first nitride-based semiconductor layer 2 of the active portion 201. Alternatively, the wide bandgap semiconductor (nitride-based semiconductor layer) 202 may also comprise, as shown in Figure 2, a first nitride-based semiconductor layer 2, a second nitride-based semiconductor layer 3 which has a larger bandgap energy than the first nitride-based semiconductor layer 2 and is made of, for example, AlGaN and functions as an electron supply layer, and a third nitride-based semiconductor layer 4 which has a smaller bandgap energy than the second nitride-based semiconductor layer 3 and is made of, for example, GaN and functions as a PSJ structure (polarized superjunction) 5.

[0041] Furthermore, as shown in Figure 1, a groove 220 reaching the first nitride-based semiconductor layer 2 can be provided between the active part 201 and the source wiring 208. Alternatively, as shown in Figures 3 and 6, it is also preferable to remove the second nitride-based semiconductor layer 3 and the third nitride-based semiconductor layer 4 below and around the source wiring 208, gate pad electrode 207, and drain pad electrode 210, so that the second nitride-based semiconductor layer 3 and the third nitride-based semiconductor layer 4 are not provided below the source wiring 208, gate pad electrode 207, and drain pad electrode 210. Alternatively, it is also preferable to lower the crystallinity of the second nitride-based semiconductor layer 3 below and around the gate pad electrode 207 and drain pad electrode 210 compared to the crystallinity of these layers in the active part 201. In such structures, it is preferable that the first nitride-based semiconductor layer 2 below the source wiring 208, gate pad electrode 207, and drain pad electrode 210 includes regions where a two-dimensional electron gas layer 20 and a two-dimensional hole gas layer are not formed. With this design, the effects of leakage current generated around the pad electrodes can be reduced, and the effects of parasitic capacitance between the two-dimensional electron gas layer and the two-dimensional hole gas layer can also be reduced.

[0042] Furthermore, as shown in Figure 2, the second nitride semiconductor 3 may have a third nitride semiconductor layer 4 connected to the gate electrode 7 via a p-type semiconductor layer 6 on the active portion 201, and extending further toward the drain electrode 10 than the gate electrode 7. Such a configuration can effectively reduce on-resistance.

[0043] In the example shown in Figure 2, a source electrode 8 is provided on one side of the second nitride-based semiconductor layer 3, which is separated from the third nitride-based semiconductor layer 4, and a drain electrode 10 is provided on the other side. It is desirable that the drain electrode 10 and the source electrode 8 are electrically connected to the two-dimensional electron gas layer by being provided on the side walls of an electrode groove 11 that reaches the first nitride-based semiconductor layer 2, which is deeper than the two-dimensional electron gas (2DEG) layer 20, or by providing a high-density contact region beneath the electrodes.

[0044] The gate electrode 7 is electrically connected to the source electrode 8 side of the third nitride semiconductor layer 4 via a p-type semiconductor 6 made of p-type GaN or NiO. The portion of the third nitride semiconductor layer 4 that extends from the p-type semiconductor 6 toward the drain electrode 10 functions as a PSJ structure (polarization superjunction) 5. The third nitride semiconductor layer 4 is provided so as to be separated from the drain electrode 10 and the source electrode 8.

[0045] (Second switching element) The second switching element 300 is not particularly limited, as long as it has a lower voltage rating than the first switching element 200 described above. As the second switching element 300, known components such as a normally-off Si-MOS transistor as described in Patent Document 1 can be used. Here, a normally-off type MOSFET formed from Si will be used as an example.

[0046] A Si-MOSFET suitable for use as a second switching element 300 according to this disclosure, as shown in Figure 7, comprises a P-type base region 362 on an N-type drift region 360. An N-type source region 364 is located on the P-type base region 362, and a groove 350 is formed that penetrates the P-type base region 362 and reaches the N-type drift region 360. A field plate electrode 354 is provided on the lower inner side of the groove 350 via a first insulating film 352 on the groove wall surface, and a gate electrode 370 is provided on the upper inner side of the groove 350 via the first insulating film 352 on the groove wall surface. A P-type contact region 366 is provided in the area between the grooves 350 where the N-type source region 364 is not provided. A source electrode 374 is formed on the gate electrode 370 via an interlayer insulating film 372, and the source electrode 374 is connected to the P-type contact region 366 and the N-type source region 364. The field plate electrode 354 is also connected to the N-type source region 364 at a location not shown. An N-type drain region 358 with a higher N-type impurity concentration than the N-type drift region 360 is formed on the back surface of the N-type drift region 360, and a drain electrode 356 is connected to the N-type drain region 358. When a higher potential is applied to the drain electrode 356 than to the source electrode 374, the device is turned off by a depletion layer extending from the interface between the N-type drift region 360 and the P-type base region 362. When a voltage above a threshold is applied to the gate electrode 370, a channel is created in the P-type base region 362 facing the groove 350, and the second switching element 300 is turned on.

[0047] [nitride-based semiconductor devices] A nitride-based semiconductor device suitably usable in the composite semiconductor device according to this disclosure will be described below with reference to the drawings. As shown in Figure 2, the nitride-based semiconductor device according to this disclosure includes an active section 201. In the active section 201, a first nitride-based semiconductor layer 2 made of a nitride semiconductor such as GaN and functioning as an electron transport layer is stacked on a substrate 1 such as silicon, SiC, or sapphire via an arbitrary buffer layer, a second nitride-based semiconductor layer 3 made of, for example, AlGaN and having a larger bandgap energy than the first nitride-based semiconductor layer 2 and functioning as an electron supply layer, and a third nitride-based semiconductor layer 4 made of, for example, GaN and having a smaller bandgap energy than the second nitride-based semiconductor layer 3 and functioning as a PSJ structure (polarized superjunction) 5. A two-dimensional electron gas layer (2DEG layer) 20 is formed within the first nitride semiconductor layer 2 near the interface between the first nitride semiconductor layer 2 and the second nitride semiconductor layer 3, and a two-dimensional hole gas layer is formed within the third nitride semiconductor layer 3 near the interface between the second nitride semiconductor layer and the third nitride semiconductor layer. Furthermore, as shown in Figure 5, the active portion 201 includes a drain electrode 10, a source electrode 8, and a gate electrode 7 provided between the drain electrode 10 and the source electrode 8, which are arranged in a plan view extending in a first direction D1. Multiple drain electrodes 10, gate electrode 7, and source electrode 8 are arranged side by side in a second direction D2 that intersects the first direction D1. Furthermore, in a plan view, the active portion 201 is sandwiched in a first direction D1, and the device includes a drain pad electrode 210 connected to the drain electrode 10 and a source wiring 208 connected to the source electrode 8, which are arranged on the upper surface of the first nitride-based semiconductor layer 2 outside the active portion 201 via an insulating film 203. The nitride-based semiconductor device according to this disclosure can be a normally-on type HEMT.

[0048] Furthermore, the matters described above regarding the first switching element in this disclosure are applicable to the nitride-based semiconductor device in this disclosure, and therefore will not be explained here. The nitride-based semiconductor device in this disclosure described above is applicable to the composite semiconductor device described above.

[0049] This specification includes the following embodiments: [1]: A composite semiconductor device comprising a first switching element and a second switching element having a lower breakdown voltage than the first switching element, wherein the source electrode of the first switching element and the drain electrode of the second switching element are electrically connected, the first switching element includes a drain electrode, a source electrode, and a gate electrode provided between the drain electrode and the source electrode, which are connected to the upper surface of a wide bandgap semiconductor and arranged to extend in a first direction in a plan view of the first switching element, and each of the drain electrode, the gate electrode and the source electrode each comprises a plurality of active portions arranged side by side in a second direction intersecting the first direction, and source wiring which also serves as a drain pad electrode connected to the drain electrode and a source pad electrode connecting adjacent source electrodes, which are arranged on the upper surface of the wide bandgap semiconductor outside the active portions via an insulating film so as to sandwich the active portions in the first direction in a plan view of the first switching element, and the second switching element is installed on the source pad electrode via a conductive adhesive. [2]: The composite semiconductor device according to [1], wherein the wide bandgap semiconductor is made up of stacked first and second nitride-based semiconductor layers, a two-dimensional electron gas layer is formed in the first nitride-based semiconductor layer of the active portion, and a groove reaching the first nitride-based semiconductor layer is provided between the active portion and the source pad electrode, or the first nitride-based semiconductor layer below the source pad electrode has a region where the two-dimensional electron gas layer is not formed. [3]: The composite semiconductor device according to [2], wherein the second nitride-based semiconductor layer is not provided below the source pad electrode. [4]: The composite semiconductor device according to [2] or [3] above, comprising a third nitride semiconductor layer disposed on the active portion of the second nitride semiconductor, and a p-type semiconductor layer connected to the gate electrode and disposed on the third nitride semiconductor layer, wherein the third nitride semiconductor layer is extended toward the drain electrode side than the p-type semiconductor layer. [5]: A protective film having a first opening and a second opening that covers the source wiring, The second switching element is installed on the first source pad region of the first opening. A composite semiconductor device according to [1], [2], [3], or [4], comprising a detection terminal for adjusting the drive voltage of the gate electrode which is electrically connected to the second source pad region of the second aperture. [6]: A nitride semiconductor device comprising: a first nitride semiconductor layer; a second nitride semiconductor layer provided on the first nitride semiconductor layer and composed of a nitride semiconductor having a larger bandgap energy than the first nitride semiconductor layer; a third nitride semiconductor layer provided on the first nitride semiconductor layer and composed of a nitride semiconductor having a smaller bandgap energy than the second nitride semiconductor layer; an active portion comprising a drain electrode, a source electrode, and a gate electrode provided between the drain electrode and the source electrode, each of which is arranged in a plan view stretched in a first direction, wherein the drain electrode, the gate electrode, and the source electrode are each arranged in a plurality of parallel active portions in a second direction intersecting the first direction; and a source wiring that serves as both a drain pad electrode connected to the drain electrode and a source pad electrode connecting adjacent source electrodes, arranged on the upper surface of the first nitride semiconductor layer outside the active portions via an insulating film, so as to sandwich the active portions in the first direction in a plan view.

[0050] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and produces similar effects is included within the technical scope of this disclosure. [Explanation of symbols]

[0051] 1...Substrate, 2...First nitride-based semiconductor layer, 3...Second nitride-based semiconductor layer 4…Third nitride-based semiconductor layer, 5…PSJ structure (polarized superjunction), 6...p-type semiconductor layer, 7...gate electrode, 8...source electrode, 10...drain electrode 11…Electrode groove, 12…Fourth nitride semiconductor layer (first spacer layer), 13…5th nitride semiconductor layer (2nd spacer layer), 14, 15…diffusion layer, 20...Two-dimensional electron gas (2DEG) layer, 100...Composite semiconductor device, 110A, B...Conductive adhesive, 120...metal plate, 130A...gate input terminal, 130B...drain terminal, 130C...Source terminal, 130D...Gate terminal (nitride semiconductor) 140... wire, 200...First switching element, 200A...High voltage FET, 201... Active part, 202... Wide bandgap semiconductor, 203... Insulating film 208...Source wiring, 207...Gate pad electrode, 210...Drain pad electrode, 217...Gate bus line, 220...Groove 224A, 224B...protective film, 221...first opening, 222...second opening, 225...First source pad area, 226...Second source pad area, 250...Detection terminal, 300...Second switching element, 300A...Si-MOSFET, 350...Groove, 352...First insulating film, 354...Field plate electrode, 356...Drain electrode, 358...N-type drain region, 360...N-type drift region, 362...P-type base region, 364...N-type source region, 370...Gate terminal, 366...P-type contact region, 372...Interlayer insulating film, 374...Source electrode, 400... A typical high-voltage FET. D1...first direction, D2...second direction.

Claims

1. A composite semiconductor device comprising a first switching element and a second switching element having a lower voltage rating than the first switching element, wherein the source electrode of the first switching element and the drain electrode of the second switching element are electrically connected, The first switching element is, Connected to the upper surface of a wide-bandgap semiconductor, and arranged to extend in a first direction in a plan view of the first switching element, the first switching element includes a drain electrode, a source electrode, and a gate electrode provided between the drain electrode and the source electrode, wherein each of the drain electrode, the gate electrode, and the source electrode has multiple active portions arranged side by side in a second direction intersecting the first direction, In a plan view of the first switching element, the first switching element comprises a drain pad electrode connected to the drain electrode and a source wiring that also serves as a source pad electrode connecting adjacent source electrodes, which are arranged on the upper surface of the wide bandgap semiconductor outside the active portion via an insulating film, so as to sandwich the active portion in the first direction, A composite semiconductor device characterized in that the second switching element is installed on the source pad electrode via a conductive adhesive.

2. The wide-bandgap semiconductor is formed by stacking first and second nitride-based semiconductor layers. A two-dimensional electron gas layer is formed in the first nitride-based semiconductor layer of the active portion. The composite semiconductor device according to claim 1, characterized in that a groove reaching the first nitride-based semiconductor layer is provided between the active portion and the source pad electrode, or the first nitride-based semiconductor layer below the source pad electrode has a region in which the two-dimensional electron gas layer is not formed.

3. The composite semiconductor device according to claim 2, characterized in that it does not have the second nitride-based semiconductor layer below the source pad electrode.

4. A third nitride-based semiconductor layer disposed on the active portion of the second nitride-based semiconductor, The gate electrode is connected to a p-type semiconductor layer disposed on the third nitride-based semiconductor layer, The composite semiconductor device according to claim 2, characterized in that the third nitride-based semiconductor layer is extended toward the drain electrode side than the p-type semiconductor layer.

5. A protective film having a first opening and a second opening is provided to cover the source wiring, The second switching element is installed on the first source pad region of the first opening. The composite semiconductor device according to any one of claims 1 to 4, characterized in that it is provided with a detection terminal for adjusting the drive voltage of the gate electrode which is electrically connected to the second source pad region of the second aperture.

6. A first nitride-based semiconductor layer, A second nitride-based semiconductor layer is provided on the first nitride-based semiconductor layer and is composed of a nitride-based semiconductor having a larger bandgap energy than the first nitride-based semiconductor layer, A third nitride-based semiconductor layer is provided on the first nitride-based semiconductor layer and is composed of a nitride-based semiconductor having a smaller bandgap energy than the second nitride-based semiconductor layer, In a plan view, the device includes a drain electrode, a source electrode, and a gate electrode provided between the drain electrode and the source electrode, each of which has multiple active portions arranged side-by-side in a second direction intersecting the first direction. A nitride-based semiconductor device characterized in that, in a plan view, it comprises a drain pad electrode connected to the drain electrode and a source wiring that also serves as a source pad electrode connecting adjacent source electrodes, which are arranged on the upper surface of the first nitride-based semiconductor layer outside the active portion via an insulating film, so as to sandwich the active portion in the first direction.

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