Bidirectional thyristor device with asymmetric characteristics

Abstract

A bidirectional thyristor device is specified, comprising: a semiconductor body (2) extending between a first main surface (21) and a second main surface (22) in a vertical direction, the second main surface being opposite to the first main surface (21); a first main electrode (31) arranged on the first main surface (21) and a second main electrode (32) arranged on the second main surface (22), wherein the semiconductor body (2) comprises a first base layer (51) of a first conductivity type, a second base layer (52) of the first conductivity type, and a third base layer (53) of a second conductivity type different from the first conductivity type arranged between the first base layer (51) and the second base layer (52). The first main electrode (31) serves as a cathode of a first thyristor functional element (11) and an anode of a second thyristor functional element (12) of the bidirectional thyristor device (1). The bidirectional thyristor further comprises first and second emitter regions (61, 62) of a second conductivity type therein, and an emitter short circuit region (71, 72) of a first conductivity type. A bidirectional thyristor device (1) is asymmetrically configured with respect to a first thyristor functional element (11) and a second thyristor functional element (12) by different arrangements of a first emitter short-circuit region (71) and a second emitter short-circuit region (72) at first and second main sides.

Description

Technical Field

[0001] A bidirectional thyristor device with asymmetrical characteristics is specified. Background Art

[0002] Cost-effective anti-parallel connected thyristors are needed for various applications, such as the classic Flexible AC Transmission Systems (FACTS). They are also beneficial for the next generation of valve concepts based on Voltage Source Converters (VSC) for High Voltage Direct Current (HVDC) transmission, often referred to as Hybrid Multi-Modular Converters (MMC).

[0003] Bidirectional controlled thyristors (BCTs) can be obtained by integrating two monolithically anti-parallel thyristor functions, which are formed from two separate, individually triggered areas on one wafer. However, the process flow is quite complex and relies on the electrical parameters of the device area being halved. For example, the surge current is half that of a full wafer device, and the thermal resistance of the thyristor is twice that of a single thyristor on a wafer of the same size.

[0004] Document WO 2019 / 158594 A1 describes the so-called BiPCT concept, in which the device has a common pnp region for two anti-parallel pnpn sections. This concept allows short commutation turn-off times to be obtained.

[0005] However, many applications require devices with different functions that currently require the use of separate devices. Summary of the invention

[0006] It is therefore an object of the invention to specify a device concept which allows providing different functionalities.

[0007] This object is achieved in particular by a bidirectional thyristor arrangement according to claim 1. Developments and expediencies are subject matter of further claims.

[0008] According to at least one embodiment, a bidirectional thyristor device includes a semiconductor body extending between a first main surface and a second main surface in a vertical direction, the second main surface being opposite to the first main surface. A first main electrode is arranged on the first main surface, and a second main electrode is arranged on the second main surface. The semiconductor body includes a first base layer of a first conductivity type, a second base layer of the first conductivity type, and a third base layer of a second conductivity type different from the first conductivity type arranged between the first base layer and the second base layer. The first main electrode serves as a cathode of a first thyristor functional element and an anode of a second thyristor functional element of the bidirectional thyristor device, and the bidirectional thyristor device is configured asymmetrically with respect to the first thyristor functional element and the second thyristor functional element.

[0009] For example, the first main electrode is adjacent to at least one first emitter region of the second conductivity type and a plurality of first emitter short-circuit regions of the first conductivity type, the second main electrode is adjacent to at least one second emitter region of the second conductivity type and a plurality of second emitter short-circuit regions of the first conductivity type, and when viewed along the vertical direction, the arrangement of the plurality of first emitter short-circuit regions at the first main surface is at least in regions different from the arrangement of the plurality of second emitter short-circuit regions at the second main surface, so that the bidirectional thyristor device is asymmetrically configured with respect to the first thyristor functional element and the second thyristor functional element. For example, the bidirectional thyristor device may provide two anti-parallel connected thyristor structures (the first thyristor functional element and the second thyristor functional element) in the same device, wherein the anode region and the cathode region are staggered to avoid the need for a separation region between the two anti-parallel thyristors.

[0010] Using an asymmetric configuration, at least one characteristic property of the bidirectional thyristor device is different for different polarities of the voltage between the first main electrode and the second main electrode. For example, the first thyristor functional element and the second thyristor functional element differ from each other with respect to at least one of the on-state voltage drop, the surge current, the turn-off time and the technical curve Qrr-VT. For example, at least one of these parameters differs by at least 10% between the first thyristor functional element and the second thyristor functional element. Alternatively or additionally, the first thyristor functional element and the second thyristor functional element may be configured to implement different functions.

[0011] In other words, the bidirectional thyristor device is intentionally configured such that it behaves asymmetrically with respect to a change in polarity of the voltage between the first main electrode and the second main electrode.

[0012] According to at least one embodiment of the bidirectional thyristor device, the local charge carrier recombination lifetime at the pn junction between the first base layer and the third base layer is different from the local charge carrier recombination lifetime at the pn junction between the second base layer and the third base layer. Therefore, the first thyristor functional element and the second thyristor functional element differ from each other with respect to the local value of the charge carrier recombination lifetime close to the pn junction between the base layers, which pn junction is closer to the main electrode serving as the cathode of the corresponding thyristor functional element. For example, the semiconductor body is configured with respect to the charge carrier recombination lifetime so that the turn-off times of the first thyristor functional element and the second thyristor functional element are different from each other. It has been found that by irradiating with electrons, protons or other ions near the pn junction, the lifetime of excess charge carriers in the n-type and p-type base layers can be intentionally shortened so as to ensure that the thyristor can be turned off in response to voltage commutation performed by an external circuit. For example, a region at a pn junction between the first base layer and the third base layer is subjected to a greater radiation dose than a region at a pn junction between the second base layer and the third base layer, or vice versa.

[0013] For example, the first thyristor functional element and the second thyristor functional element have different threshold values ​​(di / dt) during voltage commutation. 临界值 . Above this critical value, there is no switch-off during voltage commutation. In this case, the concentration of the electron-hole plasma close to the blocking pn junction may be so high during the crossing of the zero current level that the formation of a space charge region (SCR) is prevented. Therefore, if the polarity of the voltage between the first main electrode and the second main electrode changes, the bidirectional thyristor device may remain in the on-state. Therefore, switch-off may only occur if the bidirectional thyristor device is brought below its holding current.

[0014] According to at least one embodiment of the bidirectional thyristor device, the first main electrode is adjacent to at least one first emitter region of the second conductivity type and multiple first emitter short-circuit regions of the first conductivity type, and the second main electrode is adjacent to at least one second emitter region of the second conductivity type and multiple second emitter short-circuit regions of the first conductivity type. For example, the first main electrode acts as the cathode of the first thyristor functional element via the first emitter region and acts as the anode of the second thyristor functional element via the first emitter short-circuit region. Similarly, the second main electrode acts as the cathode of the second thyristor functional element via the second emitter region and acts as the anode of the first thyristor functional element via the second emitter short-circuit region. In other words, the cathode short-circuit region of one thyristor functional element simultaneously acts as the anode region of the anti-parallel thyristor functional element.

[0015] According to at least one embodiment of the bidirectional thyristor device, the arrangement of the plurality of first emitter short-circuit regions at the first main surface is different from the arrangement of the plurality of second emitter short-circuit regions at the second main surface at least in area. For example, the proportion of the first main surface in which the arrangement of the first emitter short-circuit regions is different from the arrangement of the second short-circuit regions on the second main surface amounts to between 5% and 100% of the area of ​​the first main surface.

[0016] According to at least one embodiment of the bidirectional thyristor device, when viewed in a vertical direction, at least one first emitter region overlaps with a second emitter short-circuit region. With this arrangement, a minimum length of a current path between a first emitter region and a closest second emitter short-circuit region in the semiconductor body can be reduced compared to a completely symmetrical arrangement of emitter short-circuit regions on the first main surface and the second main surface. This can help to minimize the on-state voltage drop of the bidirectional thyristor device.

[0017] According to at least one embodiment of the bidirectional thyristor device, the first emitter short circuit region and the second emitter short circuit region are arranged in an alternating manner at least in the regions along at least one direction in a top view. For example, the first emitter short circuit region and the second emitter short circuit region are arranged in an alternating manner at least in the regions along two directions in a top view. For example, the angle between the two directions is between 45° and 90° and includes end values, such as 60° or 90°.

[0018] According to at least one embodiment of the bidirectional thyristor device, when viewed along the vertical direction, the centers of at least some of the first emitter short-circuit regions are arranged next to the plurality of second emitter short-circuit regions. Alternatively or additionally, when viewed along the vertical direction, the centers of at least some of the second emitter short-circuit regions are arranged next to the first emitter short-circuit regions. For example, when viewed along the vertical direction, at least 2% and at most 100% of the first emitter short-circuit regions do not overlap with the closest second emitter short-circuit regions.

[0019] According to at least one embodiment of the bidirectional thyristor device, when viewed in the vertical direction, for one of the plurality of first emitter short-circuit regions and an associated closest one of the plurality of second emitter short-circuit regions, at least one of the following criteria (i) and (ii) applies:

[0020] (i) the maximum lateral extent of the first emitter shorting region is different from the maximum lateral extent of an associated closest second emitter shorting region; and

[0021] (ii) the center-to-center distance between the first emitter short-circuit region of the plurality of first emitter short-circuit regions and its closest first emitter short-circuit region is different from the center-to-center distance between the associated closest second emitter short-circuit region of the plurality of second emitter short-circuit regions and its closest second emitter short-circuit region. At least one of the above criteria may also apply to a plurality of or even all first emitter short-circuit regions and their associated closest second emitter short-circuit regions when viewed in the vertical direction. In other words, the arrangement of the first emitter short-circuit regions and the arrangement of the second emitter short-circuit regions may differ from each other at least in the region with respect to at least one of the center-to-center distance at the associated main surface and the maximum lateral extent. If the short-circuit region has a circular shape, the maximum lateral extent is the diameter. For example, one or more of the first emitter short-circuit region and the associated second emitter short-circuit region differ from each other by at least 10% in at least one of the above parameters. For different values ​​of these parameters, an asymmetric behavior with respect to the on-state voltage VT or the technology curve Qrr-VT may be obtained, where Qrr is the recovery charge.

[0022] According to at least one embodiment of the bidirectional thyristor device, the proportion of the area of ​​the first main surface formed by the first emitter short-circuit region is different from the proportion of the area of ​​the second main surface formed by the second emitter short-circuit region. For example, the proportion at the first main surface is at least 1.5 or 2 or 5 times the proportion at the second main surface, or vice versa. Alternatively, these proportions may differ by at least 5 percentage points or at least 10 percentage points or at least 20 percentage points and / or at most 50 percentage points.

[0023] According to at least one embodiment of the bidirectional thyristor device, the first thyristor functional element and the second thyristor functional element are configured to have different electrical ratings. For example, the first thyristor functional element and the second thyristor functional element differ from each other in terms of the rating of at least one of the following: on-state voltage drop, surge current, and turn-off time. Therefore, two thyristor functional elements with different electrical ratings can be integrated in a common device with a single semiconductor body. This can help reduce costs and / or obtain a smaller footprint. For example, one of the first thyristor functional element and the second thyristor functional element may fail at a low surge current to act as a crowbar, while the other acts as a bypass capable of withstanding high surge currents.

[0024] According to at least one embodiment, the bidirectional thyristor device includes at least one gate electrode. For example, the bidirectional thyristor device includes at least one of a first gate electrode on the first main surface and a second gate electrode on the second main surface.

[0025] According to at least one embodiment, a bidirectional thyristor device comprises a first gate electrode on a first main surface, wherein the first main electrode comprises a plurality of first segments spaced apart from one another, wherein at least some of the first segments are completely surrounded by the first gate electrode when viewed along a vertical direction. For example, each of the first segments of the first main electrode adjoins at least one first emitter region of the second conductivity type and at least one first emitter short-circuit region of the first conductivity type.

[0026] The first gate electrode surrounding the segment of the first main electrode allows to obtain a thyristor functional element that switches on very quickly. For example, the first gate electrode can be distributed over the entire first main surface. As a result, the length of the gate-cathode boundary can be increased, resulting in an enhanced di / dt capability for fast switching. At the same time, the dV / dt capability can remain unchanged.

[0027] According to at least one embodiment of the bidirectional thyristor device, the second main electrode comprises a plurality of second segments spaced apart from one another, wherein at least some of these second segments are completely surrounded by the second gate electrode when viewed in the vertical direction. The second gate electrode surrounding a plurality of segments of the first main electrode allows obtaining a bidirectional thyristor device that conducts very quickly in both current directions. For example, the second gate electrode may be distributed over the entire second main surface.

[0028] Thus, in addition to the staggered arrangement of the anodes and cathodes of the two anti-parallel connected thyristor structures (the first thyristor functional element and the second thyristor functional element), a staggered arrangement of the gate regions can also be obtained for at least one of the first thyristor functional element and the second thyristor functional element. Thus, staggered gate regions can be provided on at least one of the first main surface and the second main surface.

[0029] According to at least one embodiment of the bidirectional thyristor device, a gate electrode in the form of a first gate electrode or a second gate electrode is arranged on only one of the first and second main surfaces. Thus, one of the thyristor functional elements cannot be triggered directly via a current pulse applied to the associated gate.

[0030] Alternatively, both a first gate electrode and a second gate electrode may be provided. In this case, the bidirectional thyristor device may be electrically triggered in both current directions via the first gate electrode and the second gate electrode.

[0031] According to at least one embodiment of the bidirectional thyristor device, one of the first thyristor functional element and the second functional element is configured as a protection device to prevent cosmic ray failure or external faults causing overload during operation. Therefore, the bidirectional thyristor device provides an integrated protection device function via one of the thyristor functional elements. For example, one of the thyristor functional elements is configured to conduct very quickly via the gate electrode like a standard phase-controlled thyristor, while the anti-parallel connected thyristor functional element is only used to provide the conduction capability in the forward blocking state. For example, the conduction can be triggered by a single event caused by cosmic rays. It has been found that cosmic rays can trigger the thyristor in the forward blocking state to enter the conducting state without damage. This is also called protective firing. Since the first thyristor functional element and the second thyristor functional element are electrically connected in anti-parallel, one of them is in the forward blocking state regardless of the polarity of the applied voltage. Therefore, the risk of single-particle burnout that may occur in reverse blocking in conventional devices can be eliminated or at least significantly reduced. An additional external protection device connected in anti-parallel can be omitted.As the requirements on the thyristor functional element acting as a protection device decrease (eg with respect to the VT-Qrr technology curve), the structural parameters of the bidirectional thyristor device can be optimized for the other of the thyristor functional elements.

[0032] According to at least one embodiment of the bidirectional thyristor device, both the first thyristor functional element and the second thyristor functional element use the entire area of ​​the pn junction formed between the first base layer and the third base layer. For example, the first thyristor functional element and the second thyristor functional element taken separately each use the entire area of ​​the pn junction formed between the second base layer and the third base layer. If, for example, the first conductivity type is p-type and the second conductivity type is n-type, the first thyristor functional element and the second thyristor functional element can use a common pnp base layer sequence. The separation area between the two anti-parallel thyristors can be omitted. The first base layer, the second base layer and the third base layer can be completely unstructured in the lateral direction (i.e., in the direction extending parallel to the first main surface). In addition, it is not necessary to provide two separate electrodes on the same side of the bidirectional thyristor device, wherein one of the two electrodes serves as the anode of one thyristor and the other serves as the cathode of the other thyristor.

[0033] According to at least one embodiment of the bidirectional thyristor device, the first gate electrode forms an ohmic contact with the first base layer. This means, for example, that there is no pn junction between the first gate electrode and the first base layer. Alternatively or additionally, the second gate electrode may form an ohmic contact with the second base layer.

[0034] According to at least one embodiment of the bidirectional thyristor device, the first gate electrode includes a first grid structure having a plurality of first cells. In a view onto the first main surface, these first cells may have a polygonal shape. For example, these first cells may have a hexagonal, octagonal or quadrilateral shape. For example, the bidirectional thyristor device includes between 20 and 2000 first cells including end values. Depending on the specific requirements for the bidirectional thyristor device, the number of cells may vary over a wide range. For example, the first grid structure forms a honeycomb pattern at least in the region. For example, the honeycomb pattern is formed by regular hexagons.

[0035] According to at least one embodiment of the bidirectional thyristor device, a plurality of first emitter short-circuit regions are arranged in one of the first cells. For example, the number of first emitter short-circuit regions in one of the first cells amounts to between 2 and 100 and includes end values. However, only one first emitter short-circuit region may also be sufficient.

[0036] The second gate electrode may include a second grid structure having a plurality of second unit cells.The features described in conjunction with the first gate electrode may also be applicable to the second gate electrode.

[0037] According to at least one embodiment of the bidirectional thyristor device, an amplifying gate structure is integrated into at least one of the first gate electrode and the second gate electrode. The amplifying gate structure helps to obtain a short on-time by quickly distributing the trigger current laterally over a large wafer area. By using the amplifying gate structure for both the first gate electrode and the second electrode, a short on-time can be obtained in both current directions.

[0038] According to at least one embodiment of the bidirectional thyristor device, the first gate electrode and the second gate electrode have the same basic shape. In other words, the second gate electrode represents a copy or at least a similar copy of the first gate electrode. Alternatively, the structures of the first gate electrode and the second gate electrode may also be different from each other.

[0039] In the exemplary embodiments and the accompanying drawings, similar or similarly acting components are provided with the same reference numerals. Generally, only the differences with respect to the various embodiments are described. Unless otherwise specified, the description of a part or aspect in one embodiment also applies to the corresponding part or aspect in another embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In the attached picture:

[0041] Figures 1A to 1C The cross-sectional view ( Figure 1A ), to the view on the first primary surface ( Figure 1B ) and the view onto the second primary surface ( Figure 1C ) shows an exemplary embodiment of a bidirectional thyristor device;

[0042] Figure 2 An exemplary embodiment of a bidirectional thyristor device is shown in cross-section;

[0043] Figure 3 An exemplary embodiment of a bidirectional thyristor device is shown in top view;

[0044] Figure 4A and Figure 4B shows the measurement results of the turn-off time tq at a current of 2 kA as a function of the on-state voltage VT at a current of 1.5 kA for samples having different proportions of the main surface covered by the emitter short-circuit area and different irradiation doses;

[0045] Figure 4C and Figure 4D The (di / dt) at 2 kA current is shown as a function of the on-state voltage VT at 1.5 kA current for samples having different proportions of the main surface covered by the emitter short-circuit area and different irradiation doses. 最大值 The measurement results;

[0046] Figure 4E shows the anode current as a function of the on-state voltage VT for two samples having different sizes of emitter short regions;

[0047] Figure 4F and Figure 4G It is shown that for samples with large distance between emitter short regions ( Figure 4F ) and for samples with a small distance between emitter short regions ( Figure 4G ) as a function of time for the current I and voltage V;

[0048] Figure 5A Details of an exemplary embodiment of a bidirectional thyristor device are shown in top view;

[0049] Figure 5B Shows Figure 5A A cross-sectional view of a bidirectional thyristor device;

[0050] Figure 6 Shown are the measured results of charge recovery Qrr as a function of di / dt for samples treated with different irradiation doses.

[0051] The elements shown in the drawings and their size relationships are not necessarily correct to scale. On the contrary, for better representation and / or for better understanding, the individual elements or layer thicknesses may be shown with exaggerated size. DETAILED DESCRIPTION

[0052] Figure 1A , Figure 1B and Figure 1C An exemplary embodiment of a bidirectional thyristor device 1 is illustrated. The bidirectional thyristor device 1 comprises a semiconductor body 2 extending between a first main surface 21 and a second main surface 22 .

[0053] The semiconductor body 2 includes a first base layer 51 of a first conductivity type, a second base layer 52 of the first conductivity type, and a third base layer 53 of a second conductivity type different from the first conductivity type arranged in a vertical direction between the first base layer 51 and the second base layer 52. The first main electrode 31 is arranged on the first main surface 21, and the second main electrode 32 is arranged on the second main surface 22. For example, the first conductivity type is p-type, and the second conductivity type is n-type, or vice versa.

[0054] The first main electrode 31 serves as a cathode of the first thyristor functional element 11 and an anode of the second thyristor functional element 12. For the second thyristor functional element 12, the first main electrode 31 serves as an anode via the first emitter short-circuit region 71. Figure 1A 1 and 12 are illustrated using four thyristor symbols for each thyristor functional element, wherein the thyristor symbols belonging to one functional thyristor element are electrically connected in parallel. The first thyristor functional element 11 and the second thyristor functional element 12 represent two thyristor structures connected in anti-parallel and arranged in the same semiconductor body 2.

[0055] The bidirectional thyristor device 1 is configured asymmetrically with respect to the first thyristor functional element 11 and the second thyristor functional element 12 .

[0056] The first main electrode 31 adjoins at least one first emitter region 61 of the second conductivity type and a plurality of first emitter short-circuit regions 71 of the first conductivity type.

[0057] The second main electrode 32 adjoins at least one second emitter region 62 of the second conductivity type and a plurality of second emitter short-circuit regions 72 of the first conductivity type. In this embodiment, the first thyristor functional element 11 is formed by the second emitter short-circuit region 72 acting as an anode, the second base layer 52, the third base layer 53, the first base layer 51, and the first emitter region 61.

[0058] Therefore, the second thyristor functional element 12 is formed by the first emitter short-circuit region 71 acting as an anode, the first base layer 51, the third base layer 53, the second base layer 52 and the second emitter region 62. Therefore, the emitter short-circuit regions 71, 72 also realize the anode function of the associated anti-parallel thyristor functional element.

[0059] Between the first base layer 51 and the third base layer 53 and between the third base layer 53 and the second base layer 52, pn junctions are formed which extend over the entire area of ​​the semiconductor body 2. Therefore, the entire area of ​​these pn junctions can be used by both the first thyristor functional element 11 and the second thyristor functional element 12. In this way, a high surge current capability close to that of a single thyristor of the same size can be obtained.

[0060] For example, the semiconductor body 2 comprises silicon. However, other semiconductor materials may also be used, such as SiC (Silicon Carbide).

[0061] The bidirectional thyristor device 1 further includes a first gate electrode 41 on the first main surface 21 and a second gate electrode 42 on the second main surface 22. The bidirectional thyristor device 1 having two gate electrodes can conduct current in two directions.

[0062] However, one of the first gate electrode 41 and the second gate electrode 42 may be omitted.

[0063] The first gate electrode 41 forms an ohmic contact with the first base layer 51 via a first gate contact region 91 of the semiconductor body 2 adjacent to the first main surface 21. The second gate electrode 42 forms an ohmic contact with the second base layer 52 via a second gate contact region 92 of the semiconductor body 2 adjacent to the second main surface 22. The first gate contact region 91 and the second gate contact region 92 are of the same conductivity type as the first base layer 51.

[0064] In the exemplary embodiment shown, the amplification gate structure 8 is integrated into the first gate electrode 41 and the second gate electrode 42. The amplification gate structure 8 comprises a segment 80 of the first gate electrode 41. For example, the segment 80 is formed as a ring extending around the first gate electrode pad 410. The first gate electrode pad 410 is configured as an external contact for applying an external trigger current to the first gate electrode 41. The segment 80 overlaps with a first partial region 81 of the first conductivity type and a second partial region 82 of the second conductivity type. This results in an amplification of the current pulse applied to the first gate electrode 41 via the first gate electrode pad 410. In principle, this is a Darlington configuration of two bipolar transistors integrated in a thyristor body.

[0065] Likewise, the second gate electrode 42 has an amplifying gate structure 8 having a section 80 extending around the second gate electrode pad 420 .

[0066] In the exemplary embodiment shown, the bidirectional thyristor device 1 is formed asymmetrically by means of different configurations of the first emitter short-circuit region 71 and the second emitter short-circuit region 72. Exemplarily, the second emitter short-circuit region 72 is larger than the first emitter short-circuit region 71. The first emitter short-circuit region 71 and the second emitter short-circuit region 72 may be different from each other over the entire area of ​​the bidirectional thyristor device 1 or only in one or more partial areas (for example, near the first gate electrode 41 and the second gate electrode 42).

[0067] For example, the maximum lateral extent E2 of the second emitter short-circuit region 72 is at least 10% or at least 20% or at least 50% or at least 2 times greater than the maximum lateral extent E1 of the first emitter short-circuit region.

[0068] Thus, the proportion of the area of ​​the first main surface 21 covered by the first emitter short-circuit region 71 is smaller than the proportion of the area of ​​the second main surface 22 covered by the second emitter short-circuit region 72. For example, the proportion on one of the main surfaces is at least 1.5 or at least 2 or at least 5 times the proportion on the other. Alternatively or in addition, these proportions may differ by at least 5 percentage points or at least 10 percentage points or at least 20 percentage points and / or at most 50 percentage points.

[0069] Figure 4A and Figure 4B 9 shows the effect of the ratio of the first emitter short circuit region 71 and the second emitter short circuit region 72 on the turn-off time. For curve 931, the coverage at the cathode side amounts to 5%, and the coverage at the anode side amounts to 30%. For curve 932, the coverage on the cathode side amounts to 30%, and the coverage on the anode side amounts to 5%. For comparison, curve 939 shows the case where the coverage on both the cathode side and the anode side is 30%.

[0070] The measurement points on the corresponding curves represent samples with different proton irradiation doses. Figure 4A As shown in , if the difference between the coverage of the short-circuit area on the cathode side and the anode side is relatively large, a very short turn-off time tq can be obtained regardless of the proton irradiation dose.

[0071] Figure 4B Illustration: This is not the case if the difference between coverage and coverage is smaller. Curve 941 represents a coverage of 5% at the cathode side and a coverage of 17% at the anode side, while curve 942 belongs to a sample with a coverage of 17% at the cathode side and a coverage of 5% at the anode side. For comparison, curve 949 corresponds to a coverage of 17% on both the cathode side and the anode side.

[0072] Therefore, different turn-off times can be obtained for the first thyristor functional element 11 and the second thyristor functional element 12 using an asymmetric arrangement of the first emitter short-circuit region 71 on the first main surface and the second emitter short-circuit region 72 on the second main surface.

[0073] For the combination Figure 4A and Figure 4B For the sample described, Figure 4C and Figure 4D The (di / dt) at 2kA current is shown in the figure. 最大值 The measurement results.

[0074] Figure 4C The curves 951, 952 and 959 refer to the same samples as the curves 931, 932 and 939, respectively. As illustrated by the curves 951 and 952, a high (di / dt) during the commutation turn-off period is obtained. 最大值 ability.

[0075] Figure 4D Curves 961, 962, and 969 refer to the same samples as curves 941, 942, and 949, respectively.

[0076] Figure 4D The curves in FIG. 9 show that for smaller coverage and smaller differences, even better (di / dt) can be obtained for the sample of curve 962 compared to sample 969 having the same coverage of 17% for both cathode and anode sides. 最大值 Capability. For curve 961 with 5% coverage at the cathode side and 17% coverage at the anode side, the capability to turn off at high di / dt is reduced compared to sample 962 with the opposite coverage.

[0077] Therefore, the dynamic behavior of the bidirectional thyristor device 1 may be different for the first thyristor functional element and the second thyristor functional element.

[0078] Figure 4E It is further illustrated that the size of the emitter short circuit region also has an effect on the anode current. The size of the emitter short circuit region of curve 971 is larger than the size of the emitter short circuit region of curve 972. For a larger emitter short circuit region, the same anode current is obtained at a significantly lower on-state voltage VT.

[0079] Additionally or alternatively, an asymmetric behavior may also be obtained by different distances between the first emitter short-circuit region 71 and the second emitter short-circuit region 72 .

[0080] Figure 4F and 4G The emitter short circuit region with a relatively large distance ( Figure 4F) and closely spaced emitter short regions ( Figure 4G ) is the turn-off characteristic of the current I and voltage V as a function of time. Figure 4F In this case, voltage commutation does not cause the device to shut down. Only the current direction changes.

[0081] In contrast, for Figure 4G For the sample shown in , the device is off and there is no significant current flow in the negative direction.

[0082] Therefore, the bidirectional thyristor device 1 may be configured such that the first thyristor functional element 11 and the second thyristor functional element 12 are different from each other with respect to turn-off capability.

[0083] exist Figure 1A In the exemplary embodiment shown in , the semiconductor body 2 is a complete wafer with bevel junction termination. However, the semiconductor body 2 can also be part of a wafer, so that the bidirectional thyristor device 1 is a chip obtained by singulating the processed wafer into individual devices. In this case, the bidirectional thyristor device 1 can include a planar pn junction termination, for example using a guard ring or lateral variable doping (VLD). At the same time, a deep p-type well (sink) can be provided for reverse blocking capability. This also applies to the subsequent exemplary embodiments.

[0084] exist Figure 2 and Figure 3 In the exemplary embodiment shown in FIG. 1 , the first emitter short circuit region 71 and the second emitter short circuit region 72 differ from each other with respect to their relative positions when viewed in the vertical direction.

[0085] like Figure 2 As shown in FIG, the first emitter short region 71 overlaps the second emitter region 62. Therefore, the length of the direct current path between the first emitter short region 71 and the closest second emitter region 62 is reduced compared to an arrangement in which the first emitter short region 71 and the second emitter short region 72 have the same lateral position.

[0086] like Figure 3 As shown in , the center 710 of the first emitter short circuit region 71 can be arranged laterally next to the second emitter short circuit region 72. Similarly, the center 720 of the second emitter short circuit region 72 can be arranged laterally next to the first emitter short circuit region 71. The first emitter short circuit region 71 and the second emitter short circuit region 72 can be arranged so that there is no overlap between them when viewed in the vertical direction. The first emitter short circuit region 71 and the second emitter short circuit region 72 are arranged in an alternating manner along two directions. In the figure, the angle between the two directions is 90°. However, the angle may also be different from 90°. For example, the angle between the two directions is between 45° and 90° and includes end values.

[0087] Figure 5A and Figure 5B The exemplary embodiment of the bidirectional thyristor device 1 shown in FIG. 1 corresponds substantially to the embodiment of the bidirectional thyristor device 1 in combination with Figures 1A to 1C Exemplary embodiments are described.

[0088] In contrast, the first main electrode 31 includes a plurality of first segments 310 spaced apart from one another. In a view onto the first main surface 21 , at least some (eg, at least 50%, or at least 90%, or all) of the first segments 310 are completely surrounded by the first gate electrode 41 .

[0089] The first gate electrode 41 includes a first gate electrode pad 410 (see Figure 1A )'s first grid structure 411.

[0090] Each of the first segments 310 of the first main electrode 31 adjoins at least one first emitter region 61 of the second conductivity type and at least one first emitter short-circuit region 71 of the first conductivity type.

[0091] exist Figure 5A In the exemplary embodiment shown in , the first grid structure 411 includes a plurality of first cells 4110 in a hexagonal shape, thereby forming a honeycomb structure. However, other polygonal first cells may also be applicable to the first grid structure 411, such as a quadrangular or octagonal shape.

[0092] like Figure 5B As illustrated in the cross-sectional view of FIG. 2 , the second main electrode 32 and the second gate electrode 42 are arranged on the second main surface 22 of the semiconductor body. Like the first main electrode 31, the second main electrode 32 is divided into a plurality of second segments 320. In the view onto the second main surface 22, at least some (e.g., at least 50%, or at least 90%, or all of the second segments 320) of the second segments 320 are completely surrounded by the second gate electrode 42.

[0093] Each of the second segments 320 of the second main electrode 32 adjoins at least one second emitter region 62 of the second conductivity type and at least one second emitter short-circuit region 72 of the first conductivity type.

[0094] During operation of the bidirectional thyristor device 1, the first section 310 of the first main electrode 31 can be electrically contacted to the same potential, for example by pressing a conductive plate or a conductive wafer against the first main electrode 31. Figure 5B As shown in , the thickness of the first gate electrode 41 within the first grid structure 411 is less than the thickness of the first main electrode 31. Therefore, the first grid structure 411 does not form an electrical contact to the board or wafer. This also applies to the second main electrode 32.

[0095] The number of first unit cells 4110 may vary within wide limits, for example between 10 and 5000, depending on the intended application of the bidirectional thyristor device 1 . For example, a device with a diameter of 100 mm may include several hundred first unit cells formed by the first grid structure 411 .

[0096] The view onto the first main surface 21 may correspond to the view onto the second main surface 22. Therefore, the views onto the second main surface 22 are not explicitly shown in the figures. The features and parameters described in conjunction with the configuration on the first main surface 21 (e.g., in conjunction with the first main electrode 31, the first gate electrode 41, the first grid structure 411, the first unit cell 4110, the first emitter region 61, and the first emitter short-circuit region 71) may also be applied to the corresponding elements on the second main surface 22, such as the second main electrode 32, the second gate electrode 42, the second grid structure 421, the second unit cell 4210, the second emitter region 62, and the second emitter short-circuit region 72, respectively. However, these parameters may also differ between the first main surface 21 and the second main surface 22, so that the bidirectional thyristor device is asymmetric.

[0097] For example, the length L1 of one side portion 4111 of the first unit cell 4110 is between 500 μm and 5000 μm, or between 900 μm and 3000 μm. The greater the length L1, the greater the connected area of ​​the first segment 310 of the first main electrode 31.

[0098] The width W1 of a side of at least one of the first cells 4110 is between 100 μm and 2000 μm and includes end values, for example, between 100 μm and 500 μm. The width of the side together with their thickness defines the cross-section of the first grid structure 411. For example, the thickness of the first grid structure 411 is between 3 μm and 30 μm and includes end values, or between 5 μm and 12 μm and includes end values. For example, using these parameters, the cross-section of the first grid structure 411 is large enough to avoid a significant voltage drop along the gate path from the first gate electrode pad to the outermost area of ​​the first grid structure 411.

[0099] The terms "length" and "width" refer to the extension in the lateral direction. Thickness refers to the extent in the vertical direction (ie, perpendicular to the first major surface).

[0100] For example, the maximum lateral extent E1 of the first emitter short-circuit region 71 is between 50 μm and 1000 μm, inclusive, or between 100 μm and 500 μm, inclusive.

[0101] For example, the edge-to-edge distance D1 between two emitter short regions 71 within the same first unit cell is between 200 μm and 1000 μm, or between 300 μm and 500 μm. The distance between emitter short regions may be appropriately selected to provide sufficiently high dV / dt.

[0102] For example, an edge-to-edge distance D2 between the first grid structure 411 and a first emitter short-circuit region arranged closest thereto is between 50 μm and 400 μm inclusive, or between 100 μm and 200 μm inclusive.

[0103] The above parameters can take into account design rules that are not applicable to existing device concepts. This is, for example, because the emitter short-circuit region on the cathode side of one thyristor functional element simultaneously serves as the anode region of the anti-parallel thyristor functional element.

[0104] Different from Figure 5A For example, the first emitter short circuit region 71 arranged in one first unit cell may also have different values ​​for the maximum lateral extent. For example, the emitter short circuit region arranged closer to the edge of the first segment may have a smaller maximum lateral extent than the first emitter short circuit region arranged closer to the center of the corresponding first segment.

[0105] Alternatively or additionally, the central first emitter short-circuit region 71 may be replaced by several smaller first emitter short-circuit regions 71 .

[0106] For example, the diameter of the first emitter short region 71 arranged near the first cell edge may be between 100 μm and 250 μm, inclusive, wherein the diameter of the first emitter short region 71 arranged closer to the cell center may be between 150 μm and 500 μm, inclusive.

[0107] exist Figure 5B In the example shown in , each first segment 310 overlaps with a plurality of first emitter short-circuit regions 71, wherein one first emitter short-circuit region 71 is arranged in the center of the first segment 310 and the other first emitter short-circuit regions 71 are arranged along the circumference of the first segment 310. However, a single emitter short-circuit region 71 may also be sufficient.

[0108] The described device structure provides a high di / dt capability due to the large increase in the interface area between the gate electrode and the main electrode on the first and second main surfaces. In comparison with conventional devices, a short on-time after application of a gate current pulse can be obtained.

[0109] In conventional devices, the distance of the short-circuit region from the edge of the main electrode is kept low, since it is inversely proportional to the dV / dt capability. This reduces the di / dt capability. In contrast, for the described bidirectional thyristor device 1, high values ​​of dV / dt and di / dt can be obtained simultaneously, for example due to the large increase in the gate-cathode area.

[0110] exist Figure 5B In the exemplary embodiment shown in , the sizes and positions of the first emitter short-circuit region 71 and the second emitter short-circuit region 72 are the same for the first main surface 21 and the second main surface 22 .

[0111] By configuring the semiconductor body 2 such that the turn-off times of the first thyristor functional element and the second thyristor functional element differ from each other, an asymmetric behavior of the bidirectional thyristor device 1 with respect to the first thyristor functional element 11 and the second thyristor functional element 12 may be obtained.

[0112] This can be achieved by subjecting the region of the semiconductor body 2 at the pn junction between the first base layer 51 and the third base layer 53 to a different irradiation dose than the region at the pn junction between the second base layer 52 and the third base layer 53 .

[0113] Figure 6 The effect of the irradiation dose is illustrated in FIG. 98, which shows curves 981, 982 and 983 belonging to three samples treated with different irradiation doses. For each curve, the (di / dt) representing the critical values ​​of these samples is illustrated. 临界值 value.

[0114] Above this critical value, there is no switch-off during voltage commutation. Above this critical value, the device operates without physical damage, and when di / dt returns to the critical value (di / dt) in some of the following AC voltage waves 临界值 Below this value, the shutdown capability is restored, provided that the device does not overheat. Figure 6 Figure 1 shows that (di / dt) can be adjusted by irradiation dose during device fabrication. 临界值 Therefore, different values ​​can be obtained for the first thyristor functional element 11 and the second thyristor functional element 12.

[0115] Devices irradiated with a lower irradiation dose further show a lower voltage drop in the on-state which is reflected in lower electrical losses. If, for example, one of the thyristor functional elements is operated in a circuit with a lower commutation di / dt due to a higher series inductance, the thyristor functional element may require a lower irradiation dose and the losses in the on-state may be smaller. The on-state voltage VT drop is also reflected in the surge current I TSMThe lower the VT value, the higher the I TSM The higher the value.

[0116] Thus, one of the thyristor functional elements may operate as a crowbar that fails at relatively low surge currents, while the other thyristor functional element acts as a bypass that can withstand high surge currents.

[0117] Different irradiation doses may also be applicable to the apparatus described in connection with the previous exemplary embodiments.

[0118] As an alternative or in addition to different charge carrier recombination lifetimes, the arrangement of the first emitter short-circuit region 71 and the second emitter short-circuit region 72 as described in the previous exemplary embodiment may be configured asymmetrically. Figure 5A and Figure 5B The bidirectional thyristor device of the exemplary embodiment shown in FIG.

[0119] Furthermore, as in the previous exemplary embodiment, one of the first gate electrode 41 and the second gate electrode 42 may be omitted.

[0120] Various combinations of the above ways of obtaining an asymmetric behavior of a bidirectional thyristor device can be used to obtain different thyristor functional elements integrated in one semiconductor body.

[0121] The invention described herein is not limited to the description given with reference to the exemplary embodiments. On the contrary, the invention covers any novel feature and any combination of features, in particular including any combination of features in the claims, even if this feature or this combination itself is not explicitly indicated in the claims or the exemplary embodiments.

[0122] Reference numerals list

[0123] 1 Thyristor device

[0124] 11. First thyristor functional element

[0125] 12 Second thyristor functional element

[0126] 2 Semiconductor body

[0127] 21 first main surface

[0128] 22 Second main surface

[0129] 31. First main electrode

[0130] 310 First paragraph

[0131] 32. Second main electrode

[0132] 320 Second paragraph

[0133] 41 first gate electrode

[0134] 410 first gate electrode pad

[0135] 411 First Grid Structure

[0136] 4110 First cell

[0137] 4111 Side

[0138] 42 second gate electrode

[0139] 420 second gate electrode pad

[0140] 421 Second Grid Structure

[0141] 4210 Second cell

[0142] 51 First base layer

[0143] 52 Second base layer

[0144] 53 Third base layer

[0145] 61 First emitter region

[0146] 62 Second emitter region

[0147] 71 First emitter short circuit area

[0148] 710 Center of the first emitter short circuit area

[0149] 72 Second emitter short circuit area

[0150] 720 Center of the second emitter short circuit area

[0151] 8 Amplification gate structure

[0152] 80 Segment

[0153] 81 First partial region (first conductivity type)

[0154] 82 Second partial region (second conductivity type)

[0155] 91 first gate contact region

[0156] 92 Second gate contact region

[0157] 931, 932, 939 curves

[0158] 941, 942, 949 curves

[0159] 951, 952, 959 curves

[0160] 961, 962, 969 curves

[0161] 971, 972 curves

[0162] 981, 982, 983 curves

[0163] L1 Side length

[0164] W1 Width of the side (covered by the first / second gate electrode)

[0165] E1 Maximum lateral extent of the first emitter short-circuit region

[0166] E2 Maximum lateral extent of the second emitter short-circuit region

[0167] D1 edge to edge distance

[0168] D2 edge to edge distance

Claims

1. A bidirectional thyristor device (1), comprising: - a semiconductor body (2), the semiconductor body extending in a vertical direction between a first main surface (21) and a second main surface (22), the second main surface being opposite to the first main surface (21), a first main electrode (31) arranged on the first main surface (21) and a second main electrode (32) arranged on the second main surface (22), in, - the semiconductor body (2) comprises a first base layer (51) of a first conductivity type, a second base layer (52) of the first conductivity type, and a third base layer (53) of a second conductivity type different from the first conductivity type arranged between the first base layer (51) and the second base layer (52), - the first main electrode (31) serves as a cathode of a first thyristor functional element (11) of the bidirectional thyristor device (1) and an anode of a second anti-parallel thyristor functional element (12) of the bidirectional thyristor device (1), - the first main electrode (31) adjoins at least one first emitter region (61) of the second conductivity type and a plurality of first emitter short-circuit regions (71) of the first conductivity type, - the second main electrode (32) adjoins at least one second emitter region (62) of the second conductivity type and a plurality of second emitter short-circuit regions (72) of the first conductivity type, It is characterized in that - when viewed along the vertical direction, the arrangement of the plurality of first emitter short-circuit regions (71) at the first main surface (21) is different from the arrangement of the plurality of second emitter short-circuit regions (72) at the second main surface (22), so that the bidirectional thyristor device (1) is configured asymmetrically with respect to the first thyristor functional element (11) and the second thyristor functional element (12), and The bidirectional thyristor device (1) comprises at least one of the following: (i) a first gate electrode (41) on the first main surface (21), wherein the first main electrode (31) comprises a plurality of first segments (310) spaced apart from each other, wherein, when viewed along the vertical direction, at least some of the first segments (310) are completely surrounded by the first gate electrode (41); and (ii) a second gate electrode (42) on the second main surface (22), wherein the second main electrode (32) comprises a plurality of second segments (320) spaced apart from each other, wherein, when viewed along the vertical direction, at least some of the second segments (320) are completely surrounded by the second gate electrode (42), Wherein, when viewed along the vertical direction, at least one first emitter region (61) overlaps with a second emitter short-circuit region (72).

2. The bidirectional thyristor device (1) according to claim 1, wherein: A local charge carrier recombination lifetime at a pn junction between the first base layer (51) and the third base layer (53) is different from a local charge carrier recombination lifetime at a pn junction between the second base layer (52) and the third base layer (53).

3. The bidirectional thyristor device (1) according to claim 1 or 2, in, When viewed along the vertical direction, centers (710) of at least some of the first emitter short-circuit regions (71) are arranged next to the plurality of second emitter short-circuit regions (72).

4. The bidirectional thyristor device (1) according to claim 1 or 2, in, When viewed along the vertical direction, for one of the plurality of first emitter short-circuit regions (71) and an associated closest one of the plurality of second emitter short-circuit regions (72), at least one of the following criteria applies: (i) the maximum lateral extent (E1) of the first emitter shorting region (71) is different from the maximum lateral extent (E2) of the associated closest second emitter shorting region (72); and (ii) a center-to-center distance between a first emitter short-circuit region (71) and its closest first emitter short-circuit region among the plurality of first emitter short-circuit regions (71) is different from a center-to-center distance between an associated closest second emitter short-circuit region (72) and its closest second emitter short-circuit region among the plurality of second emitter short-circuit regions (72).

5. The bidirectional thyristor device (1) according to claim 1 or 2, in, An area ratio of the first main surface (21) formed by the first emitter short-circuit region (71) is different from an area ratio of the second main surface (22) formed by the second emitter short-circuit region (72).

6. The bidirectional thyristor device (1) according to claim 1 or 2, in, The first thyristor functional element (11) and the second functional element (12) are configured to have different electrical ratings.

7. The bidirectional thyristor device (1) according to claim 1 or 2, in, A gate electrode in the form of the first gate electrode (41) or the second gate electrode (42) is provided on only one of the first main surface (21) and the second main surface (22).

8. The bidirectional thyristor device (1) according to claim 7, in, One of the first thyristor functional element (11) and the second functional element (12) is configured as a protection device against external faults or cosmic ray failures causing overload during operation.

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