Diode containing a plurality of trenches

Abstract

Diode (100), comprising: a semiconductor body (102) having a first main surface (104) and a second main surface (106) opposite the first main surface (104); an anode region (108) and a cathode region (109), wherein the anode region (108) is arranged between the first main surface (104) and the cathode region (109); an anode pad region (110) electrically connected to the anode region (108); a plurality of trenches (114) extending from the first main surface (104) into the semiconductor body (102), wherein a first group (1141) of the plurality of trenches (114) includes a first trench electrode (1161) and a second group (1142) of the plurality of trenches (114) includes a second trench electrode (1162) and the first trench electrode (1161) is electrically coupled to the anode pad region (110) via an anode wiring line (112) and the second trench electrode (1162), such that a current path between the first trench electrode (1161) and the anode pad region (110) runs via the anode wiring line (112) and the second trench electrode (1162).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a diode, in particular to semiconductor devices including the diode. BACKGROUND

[0002] Diodes are an important device element in integrated circuits (ICs). Examples of devices containing diodes are known from the documents US 2020 / 0 083 369 A1 and US 2020 / 0 098 747 A1. For example, during turn-off of the half-bridge of a semiconductor switch, a so-called freewheeling diode takes over the current. To enter a low-impedance forward-conducting mode, the freewheeling diode must bring its junction into forward bias and reduce the built-in electric blocking field. During this process, the freewheeling diode is not yet flooded with charge carriers, which causes a large voltage drop when it is forced to conduct a significant current. As the conductance increases while charge carriers are stored in the diode, this voltage drop reduces. This phenomenon is characterized by the so-called forward recovery voltage.In switching applications, the forward recovery voltage is a key parameter because a parallel switching device, such as an insulated-gate bipolar transistor (IGBT), must have sufficient reverse blocking capability to withstand this voltage spike. Furthermore, a gate driver that can drive the gate of the parallel switching device can be damaged if the forward recovery voltage becomes too high. Different types of diodes have different levels of forward recovery voltage.

[0003] This can depend on the thickness, resistivity of the base material, anode efficiency, and other factors. In the case of a diode containing trenches, charging of parasitic trench-related capacitances can cause a prolonged forward recovery phase with a larger forward recovery voltage amplitude.

[0004] There is a need to reduce the forward recovery voltage of trench-containing diodes. SUMMARY

[0005] One example of the present disclosure relates to a diode. The diode includes a semiconductor body having a first main surface and a second main surface opposite the first main surface. The diode further includes an anode region and a cathode region. The anode region is arranged between the first main surface and the cathode region. An anode pad region is electrically connected to the anode region. The diode further includes a plurality of trenches extending from the first main surface into the semiconductor body. A first group of the plurality of trenches includes a first trench electrode. A second group of the plurality of trenches includes a second trench electrode. The first trench electrode is electrically coupled to the anode pad region via an anode wiring line and the second trench electrode.

[0006] Another example of a diode according to the present disclosure includes a semiconductor body having a first main surface and a second main surface opposite the first main surface. The diode further includes an anode region and a cathode region. The anode region is arranged between the first main surface and the cathode region. An anode pad region is electrically connected to the anode region. The diode further includes a plurality of trenches extending from the first main surface into the semiconductor body. A first group of the plurality of trenches includes a first trench electrode. The first trench electrode is divided into at least a first part and a second part.A conductance per unit length of the first part along a longitudinal direction of the first trench electrode is at least a factor of 1000 smaller than a conductance per unit length of the second part along the longitudinal direction of the first trench electrode. The second part is electrically coupled to the anode pad region via the first part.

[0007] Another example of a diode according to the present disclosure includes a semiconductor body having a first main surface and a second main surface opposite the first main surface. The diode further includes an anode region and a cathode region. The anode region is arranged between the first main surface and the cathode region. An anode pad region is electrically coupled to the anode region. The diode further includes a plurality of trenches extending from the first main surface into the semiconductor body. A first group of the plurality of trenches includes a first trench electrode. The first trench electrode is electrically coupled to the anode pad region via an anode wiring line and a resistor.

[0008] Another example of a diode according to the present disclosure includes a semiconductor body having a first main surface and a second main surface opposite the first main surface. The diode includes an anode region and a cathode region. The anode is arranged between the first main surface and the cathode region. An anode pad region is electrically connected to the anode region. Further, the diode includes a plurality of trenches extending from the first main surface into the semiconductor body. A first group of the plurality of trenches includes a first trench electrode. At least one resistive element is coupled in series between the first trench electrode of each trench of the plurality of trenches and the anode pad region.The diode is configured to conduct current in an on-state in a forward direction and to block current in an off-state, wherein the diode is configured to switch from the off-state to the on-state during a switching time, wherein the at least one resistive element is configured such that a potential of each first trench electrode of the plurality of trenches deviates from a potential of the anode region by at least 2 V for at least 30% of the switching time.

[0009] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of semiconductor devices, such as vertical power semiconductor devices, and together with the description serve to explain the principles of the embodiments. Further embodiments are described in the following description and claims. Fig. 1A to 1E are schematic top and cross-sectional views to illustrate an example of a diode having resistive coupling between a trench electrode and an anode pad region. Fig. 2A to 2C, 3 and 4 are schematic top and cross-sectional views to illustrate other examples of a diode having resistive coupling between a trench electrode and an anode pad region. Fig. 5 is a schematic cross-sectional view illustrating a semiconductor device including a diode and a switching device connected in parallel. DETAILED DESCRIPTION

[0011] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown, for illustrative purposes, specific embodiments in which the invention may be practiced. The drawings are not to scale and are for illustrative purposes only. For clarity, like elements in the various drawings are designated by corresponding reference numerals unless otherwise noted.

[0012] The terms "have," "contain," "comprise," "have," and the like are open-ended terms. These terms indicate the presence of the identified structures, elements, or characteristics, but do not preclude the presence of additional elements or characteristics. The indefinite and definite articles are intended to include both the plural and the singular, unless the context clearly indicates otherwise.

[0013] The term "electrically connected" may refer to a permanent electrical connection between the respective elements, for example, a direct current contact between the respective elements or a low-resistance connection via a metal and / or a highly doped semiconductor material. The term "electrically coupled" may include that one or more intermediate control or resistive elements suitable for signal and / or power transmission may be arranged between the electrically coupled elements, for example, elements such as switches that can be controlled to temporarily provide electrical connection in a first state and high-resistance electrical decoupling in a second state, or resistors. Electrically coupled elements may also be electrically connected.An ohmic contact is a non-rectifying electrical junction with a linear or nearly linear current-voltage characteristic.

[0014] Ranges specified for physical dimensions include the boundary values. For example, a range for a parameter y from a to b is written as a ≤ y ≤ b. A parameter y with a value of at least c is written as c ≤ y, and a parameter with a value of at most d is written as y ≤ d.

[0015] The term "on" should not be construed to mean only "directly on." Rather, if an element is positioned "on" another element (e.g., a layer is "on" another layer or "on" a substrate), another component (e.g., another layer) may be positioned between the two elements (e.g., another layer may be positioned between a layer and a substrate if the layer is "on" the substrate).

[0016] An example of a diode may include a semiconductor body having a first main surface and a second main surface opposite the first main surface. The semiconductor body may include an anode region and a cathode region. The anode region may be arranged between the first main surface and the cathode region. An anode pad region may be electrically connected to the anode region. A plurality of trenches may extend from the first main surface into the semiconductor body. A first group of the plurality of trenches may include a first trench electrode. A second group of the plurality of trenches may include a second trench electrode. The first trench electrode may be electrically coupled to the anode pad region via an anode wiring line and the second trench electrode. In plan view, the plurality of trenches may be formed within the diode region.The plurality of trenches can be directly surrounded by semiconductor regions forming the pn diode.

[0017] The diode may be a vertical diode device with a current flow between a first terminal, e.g., an anode terminal, on the first main surface and a second terminal, e.g., a cathode terminal, on a second main surface opposite the first main surface. The diode may be a freewheeling diode. The freewheeling diode may be part of a semiconductor switching device, e.g., a half-bridge. The diode may be configured to conduct currents of 1 A or more than 10 A or even more than 30 A and may further be configured to block voltages between anode and cathode terminals in the range of several hundred to several thousand volts, e.g., 400 V, 650 V, 1.2 kV, 1.7 kV, 3.3 kV, 4.5 kV, 5.5 kV, 6 kV, 6.5 kV. The blocking voltage may, for example, correspond to a voltage class specified in a datasheet of the diode.

[0018] The semiconductor body may contain or consist of a semiconductor material from the elemental semiconductors of Group IV, a IV-IV compound semiconductor material, a III-V compound semiconductor material, or a II-VI compound semiconductor material. Examples of semiconductor materials from the elemental semiconductors of Group IV include, among others, silicon (Si) and germanium (Ge). Examples of IV-IV compound semiconductor materials include, among others, silicon carbide (SiC) and silicon germanium (SiGe). Examples of a III-V compound semiconductor material include, among others, gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), indium phosphide (InP), indium gallium nitride (InGaN), and indium gallium arsenide (InGaAs). Examples of II-VI compound semiconductor materials include cadmium telluride (CdTe), mercury cadmium telluride (CdHgTe), and cadmium magnesium telluride (CdMgTe).The semiconductor body can be, for example, a magnetic Czochralski, MCZ, or float zone (FZ) or zone melt or an epitaxially deposited silicon semiconductor body.

[0019] The first surface may be a plane at an interface between the semiconductor body and a wiring region above the semiconductor body on a first side of the semiconductor body. Likewise, the second main surface may be a plane at an interface between the semiconductor body and a wiring region, e.g., a rear contact, above the semiconductor body on a second side of the semiconductor body.

[0020] The anode region may comprise one or a plurality of fused anode sub-regions. The anode region may have a first conductivity type, e.g., a p-type. The anode sub-regions may differ at least partially with respect to one or more properties of the doping concentration profile, the doping concentration type, the vertical and / or lateral extent. For example, the anode region or sub-regions may be formed by, for example, a diffusion and / or ion implantation process. The anode region may, for example, have a p-type region adjacent to the first main surface. + -doped anode contact region and one or more p-doped anode subregions which extend, for example, along the vertical direction deeper into the semiconductor body than the anode contact region.

[0021] The cathode region may comprise one or a plurality of fused cathode sub-regions. The cathode region may have a second conductivity type, e.g., an n-type. The cathode sub-regions may differ from one another at least partially with respect to one or more properties of the doping concentration profile, the doping concentration type, the vertical and / or lateral extent. For example, the cathode region or the cathode sub-regions may be formed by, for example, a diffusion and / or ion implantation process. The cathode region may, for example, be an n - -doped drift region, an n-doped field stop region and an n +-doped cathode contact region adjacent to the second main surface. An impurity concentration in the drift region may gradually increase or decrease in steps with increasing distance from the first main surface, at least in sections or regions of its vertical extent. According to other examples, the impurity concentration in the drift region may be approximately uniform. For silicon-based diodes, an average impurity concentration in the drift region may be between 5 × 10 12 cm -3 and 1 × 10 15 cm -3 , for example in a range of 1 × 10 13 cm -3 up to 2 × 10 14 cm -3 In the case of SiC-based diodes, an average impurity concentration in the drift region can be between 5 × 10 14 cm -3 and 1 × 10 17 cm -3 , for example in a range of 1 × 10 15 cm -3 up to 2 × 10 16 cm-3 , lie. A vertical extension of the drift region may depend on the voltage blocking requirements of the diode, e.g., a specified voltage class. When the diode is operated in voltage blocking mode, a space charge region may extend vertically partially or completely through the drift region, depending on the reverse voltage applied to the diode. When the diode is operated at or near the specified maximum reverse voltage, the space charge region may reach or penetrate the field stop region. The field stop region is configured to prevent the space charge region from extending further to the cathode terminal at the second main surface of the semiconductor body. In this way, the drift region can be formed using desired low doping levels and with a desired thickness, while achieving soft switching for the so-formed diode.

[0022] A pn junction can be formed between the anode region and the cathode region.

[0023] The anode pad region may be part of a wiring level of a wiring region above the first main surface. The wiring region may have one or more than one wiring level, e.g., two, three, four, or even more wiring levels. Each wiring level may be formed by a single or a stack of conductive layers, e.g., metal layer(s), or doped layers, e.g., highly doped semiconductor layers such as highly doped polycrystalline silicon. The wiring levels may, for example, be lithographically patterned. An intermediate dielectric may be arranged between stacked wiring levels. One or more contact plugs or contact lines may be formed in openings of the intermediate dielectric to electrically connect parts, e.g., metal lines or contact areas or pads, of different wiring levels.In the case of multiple wiring levels, the anode pad region may be located furthest away from the first main surface, e.g., in an outermost wiring level with respect to the first main surface. For example, the anode pad region may be arranged above the anode region. Contacts, e.g., plugs and / or contact lines, may, for example, conduct a diode current along the vertical direction between the anode pad region and the anode region in the semiconductor body.

[0024] For example, all or some parts of each of the plurality of trenches of the first and second groups may be strip-shaped. Strip-shaped parts of the trenches of the first and second groups may extend parallel along a longitudinal direction. For example, the trench electrode in each of the first group and the second group of the plurality of trenches may be electrically insulated from a surrounding part of the semiconductor body, e.g., from the anode region, by a trench dielectric. The trench dielectric may include a layer or a combination of layers, e.g., a stack of dielectric layers, e.g., oxide layers such as thermal oxide layers or deposited oxide layers, e.g., undoped silicate glass (USG), phosphosilicate glass (PSG), borosilicate glass (BSG), borophosphosilicate glass (BPSG), nitride layers, high-dielectric-constant dielectric layers, or low-dielectric-constant dielectric layers.The trench electrode in each of the first group and second group of the plurality of trenches may include an electrode material or a combination of electrode materials, for example, a doped semiconductor material (e.g., a highly doped semiconductor material) such as doped polycrystalline silicon, a metal, or metal compounds. The plurality of trenches of the first group and the second group may be formed at least partially simultaneously, e.g., by means of a common etching process(es). Likewise, the trench electrode and / or the trench dielectric of the first group and the second group may be formed at least partially simultaneously, e.g., by means of a common layer deposition process(es).The electrodes in the plurality of trenches act as field plates configured to protect the anode from high electric field strengths that can limit the robustness of a diode circuit and prevent further degradation of the anode efficiency, for example.

[0025] Unlike in an active region of IGBTs or MOSFETs (metal oxide semiconductor field-effect transistors), in which n-doped and p-doped regions, e.g., source and body, are electrically connected to a load terminal via the first main surface, the anode pad region may be electrically connected to a semiconductor region of one conductivity type alone, e.g., the anode region. The active region may, for example, be a region on the first main surface of the diode where a load current can flow through the first main surface between the semiconductor body and the wiring region. The diode may have regions on the first main surface that differ from the active region, e.g., an edge termination region that partially or completely surrounds the active region. Since pn junctions within the semiconductor body, e.g.,the pn junction between the cathode region and the anode region, can terminate at edge zones of the semiconductor body, this edge effect can limit the breakdown voltage of the device below the ideal value determined by the parallel planar junction.

[0026] The anode wiring line may be arranged at or near an edge of the active region. For example, the anode wiring line may be laterally spaced from the anode pad region. Although the first trench electrode in the first group of trenches may be arranged at least partially directly below the anode pad region, the first trench electrode is electrically coupled to the anode pad region via the anode wiring line and the second trench electrode, rather than being directly electrically connected to the anode pad region via a contact above the first trench electrode. This provides a resistive coupling of the first trench electrode to the anode pad, thus providing a higher ohmic resistance between the first trench electrode and the anode pad compared to a direct connection of the first trench electrode.Consequently, the current from the first trench electrode is forced to flow along a longitudinal extension of the second trench electrode, thereby increasing the resistance. A resistive coupling of the first trench electrode to the anode pad region may allow for an improvement in the trade-off between diode robustness and forward recovery voltage by limiting displacement current flow to the first trench electrodes. This may counteract charging of the parasitic capacitance of the trenches and consequently reduce a prolongation of the forward recovery phase. Apart from a resistive coupling of the first trench electrodes to the anode pad region via a second trench electrode, other measures for resistive coupling may be applied, as will be described below in examples, e.g., a resistive coupling via a resistor.a polycrystalline silicon resistor in the wiring region above the semiconductor body, a resistive coupling via a resistor on a substrate different from the semiconductor body, a resistive coupling via a resistor which is realized, for example, by narrowing a cross-section of the trench electrode in the trenches.

[0027] For example, the anode wiring line and the anode pad region may be separate parts of a structured wiring layer. The anode wiring line and the anode pad region may, for example, correspond to a wiring level of the wiring region above the first main surface.

[0028] A ratio between the number of trenches in the first group and the number of trenches in the second group may, for example, range from 100 to 100,000. The ratio may enable adjustment of a voltage drop of a resistor that, for example, effects the resistive coupling between the first trench electrode and the anode pad region. In some embodiments, a longitudinal extension of the first trench electrode and the second trench electrode may have approximately the same value.

[0029] For example, the anode wiring line may laterally surround at least a quarter or half of a circumference of the anode pad region. For this example, some or all of the trenches of the first group may be electrically connected to the anode wiring line at one end of the trenches. Reducing the degree of enclosure of the anode pad region by the anode wiring line may, for example, enable the realization of an area-efficient resistive coupling between the anode pad region and the first trench electrode.

[0030] The second trench electrodes may, for example, be connected in parallel between the anode wiring line and the anode pad region. A total resistance of the second trench electrodes connected in parallel, multiplied by the total capacitance of the first trench electrodes, is in a range between 100 ohms x nF and 100 ohms x µF. The total capacitance may depend on the permittivity of the oxide material, the thickness of the insulating dielectric material (e.g., oxide material) of the trenches, and the total area of ​​the insulating dielectric material facing the semiconductor material and the trench electrodes.In some embodiments, the total capacitance may be calculated according to the formula for a plate capacitor C = ε A / d, where ε is the permittivity of the material of the insulating dielectric layer, A is the total area of ​​the insulating dielectric material facing the semiconductor material on one side and the trench electrodes on the other side, and d is the thickness of the insulating dielectric layer.

[0031] For example, a conductance per unit length of the second trench electrode along a longitudinal direction of the plurality of trenches may be smaller than a conductance per unit length of the first trench electrode along the longitudinal direction of the plurality of trenches. For example, a material of the second trench electrode may have a greater electrical resistivity than a material of the first trench electrode. Material or material combinations of the first trench electrode and the second trench electrode may, for example, differ. As an alternative to this or in addition, a same semiconductor material may be used for the first trench electrode and the second trench electrode, e.g., polycrystalline silicon, but a doping concentration of the semiconductor material of the first trench electrode may be greater than a doping concentration of the semiconductor material of the second trench electrode.As an alternative or in addition, a cross-sectional area of ​​the second trench electrode perpendicular to the longitudinal direction of the trenches may be at least partially, e.g. in at least some segments of the second trench electrode along the longitudinal direction, smaller than a cross-sectional area of ​​the first trench electrode.

[0032] Another example of a diode may include a semiconductor body having a first main surface and a second main surface opposite the first main surface. The diode may include an anode region and a cathode region. The anode region may be arranged between the first main surface and the cathode electrode. An anode pad region may be electrically connected to the anode region. The diode may include a plurality of trenches extending from the first main surface into the semiconductor body. A first group of the plurality of trenches may include a first trench electrode. The first trench electrode may be divided into at least a first part and a second part.A conductance per unit length of the first portion along a longitudinal direction of the first trench electrode may be smaller by a factor of at least 1000 than a conductance per unit length of the second portion along the longitudinal direction of the first trench electrode. The second portion is electrically coupled (e.g., DC-connected) to the anode pad region via the first portion.

[0033] Similar to the second trench electrode in the trenches of the second group described in the examples above, the second part of the first trench electrode may enable resistive coupling between the first part of the first trench electrode and the anode pad region.

[0034] For example, a material of the first part of the first trench electrode may have a greater electrical resistivity than a material of the second part of the first trench electrode. A material or material combinations of the first part of the first trench electrode and the second part of the first trench electrode may, for example, differ. As an alternative or in addition, a semiconductor material may be used for the first part of the first trench electrode and for the second part of the second trench electrode, e.g., polycrystalline silicon, but a net doping concentration of the semiconductor material of the first part of the first trench electrode may be lower than a net doping concentration of the semiconductor material of the second part of the first trench electrode.Alternatively or additionally, a cross-sectional area of ​​the first part of the first trench electrode perpendicular to the longitudinal direction of the trenches may be at least partially smaller than a cross-sectional area of ​​the second part of the first trench electrode. The smaller cross-sectional area in the first part may be obtained due to a smaller lateral and / or vertical extension (width and / or height) in at least one segment of the first part of the first trench electrode compared to the second part of the first trench electrode.

[0035] For example, a lateral extension of the first part along the longitudinal direction of the first trench electrode may be smaller than a lateral extension of the second part along the longitudinal direction of the first trench electrode.

[0036] Another example of a diode may include a semiconductor body having a first main surface and a second main surface opposite the first main surface. Further, the diode may include an anode region and a cathode region. The anode region may be arranged between the first main surface and the cathode region. An anode pad region may be electrically connected to the anode region. A plurality of trenches may extend from the first main surface into the semiconductor body. A first group of the plurality of trenches may include a first trench electrode. The first trench electrode may be electrically coupled to the anode pad region via an anode wiring line and a resistor.

[0037] For example, the resistor can be arranged on a substrate different from the semiconductor body. The substrate can be, for example, a circuit board or another chip. The diode in the semiconductor body and the resistor on the substrate can be electrically connected using any suitable connection technology, e.g., bond wires, solder balls, plug and socket contacts.

[0038] For example, the anode wiring line may extend into an auxiliary anode pad region above the semiconductor body, and a first bond wire may electrically connect an auxiliary anode pad region and a first end of the resistor on the substrate.

[0039] The resistor can be arranged, for example, in a wiring region above the first main surface. The resistor can be formed, for example, in a first wiring level above the first main surface, e.g., a wiring level closest to the first main surface. The resistor can be formed from polycrystalline silicon.

[0040] A third group of the plurality of trenches may, for example, include a third trench electrode. The third trench electrode may be electrically connected to the anode pad region via a contact arranged in a portion of the first main surface where the third trench electrode and the anode pad region overlap.

[0041] Unlike the first trench electrode of the first group, which is ohmically coupled to the anode pad region, the third trench electrode in the trenches of the third group may be electrically connected to the anode pad region by contacts arranged between the anode pad region and the third trench electrode. This may enable a low-resistance connection of the third trench electrode to the anode pad region such that a lower ohmic connection is provided between the third trench electrode and the anode pad region compared to the higher-resistance connection of the first trench electrode to the anode pad region. The provision of the third trench electrode may, for example, enable protection of the anode from high electric field strengths that may limit the robustness of the diode circuit.

[0042] The plurality of trenches may, for example, extend into the anode region or may extend through the anode region and into the cathode region, e.g., a drift region of the cathode region.

[0043] Another example of a diode may include a semiconductor body having a first main surface and a second main surface opposite the first main surface. The diode may include an anode region and a cathode region. The anode region may be arranged between the first main surface and the cathode region. An anode pad region may be electrically connected to the anode region. A plurality of trenches may extend from the first main surface into the semiconductor body. A first group of the plurality of trenches may include a first trench electrode. At least one resistive element may be electrically coupled in series between the first trench electrode of each trench of the plurality of trenches and the anode pad region. The diode is configured to conduct current in a forward direction in an on-state and to block current in an off-state.Furthermore, the diode is configured to switch from the off-state to the on-state during a switching time, wherein the at least one resistance element is configured such that a potential of each first trench electrode of the plurality of trenches deviates from a potential of the anode pad region by at least 2 V for at least 30% of the switching time. Providing the resistance element for a trench diode as described above enables an effective improvement of a trade-off between the robustness of the diode and the forward recovery voltage by limiting a displacement current flow to the first trench electrodes. This can counteract charging of the parasitic capacitance of the trenches and thus reduce an extension of the forward recovery phase.

[0044] The switching time can be determined by a time interval between the stationary off state and the stationary on state of the diode.

[0045] For example, the at least one resistance element is configured such that the potential of each first trench electrode of the plurality of trenches during the switching time deviates from the potential of the anode pad region by no more than 15 V for at least 30% of the switching time.

[0046] For example, the at least one resistance element may be configured such that the potential of each first trench electrode of the plurality of trenches deviates from the potential of the anode pad region by no more than 200 mV after a time interval of 5 µs from the switching operation.

[0047] For example, a specific resistance of a resistor for ohmic coupling of the trench electrode with the anode pad area can range from 1 ohm to 1 kOhm.

[0048] Another example of the present disclosure relates to a semiconductor device. The semiconductor device includes the diode as described in the examples above and below. The semiconductor device further includes a power transistor, such as a reverse-conducting insulated-gate bipolar transistor (RC-IGBT). The diode and the RC-IGBT may be electrically connected in parallel. For example, the cathode region of the diode and the emitter of the RC-IGBT may be electrically connected. Likewise, the anode region of the diode and the collector of the RC-IGBT may be electrically connected. A transistor cell array of the RC-IGBT may at least partially surround the diode, according to one example.

[0049] The anode pad region of the diode and the source contact region of the RC-IGBT can, for example, fuse together. The anode pad region of the diode and the source contact region can, for example, be formed by a continuous pad region of a wiring level, e.g., an outermost wiring level of a wiring region. One or more bond wires can be formed on the continuous pad region. The continuous pad region can at least partially cover an active region of the diode and an active region of the RC-IGBT.

[0050] The examples and features described above and below can be combined.

[0051] Further examples of semiconductor devices are explained below in conjunction with the accompanying drawings. Functional and structural details described with reference to the above examples are intended to apply equally to the exemplary embodiments illustrated in the figures and described below.

[0052] Fig. 1A is a schematic plan view illustrating an example of a diode 100. Fig. Figure 1B is a schematic cross-sectional view taken along a section line AA of Fig. 1A.

[0053] Fig. Figure 1C is a schematic cross-sectional view along a section line BB of Fig. 1A. Fig. Figure 1D is a schematic cross-sectional view along a section line CC of Fig. 1A.

[0054] Referring to the schematic views of the Fig. 1A to 1D, the diode 100 includes a plurality of trenches 114 extending from a first main surface 104 into a semiconductor body 102. A first group 1141 of the plurality of trenches 114 includes a first trench electrode 1161. A second group 1142 of the plurality of trenches 114 includes a second trench electrode 1162. In a top view, the first group 1141 of the plurality of trenches and the second group 1142 of the plurality of trenches may be located within a region of the diode. Other trenches may be arranged between the first group 1141 of the plurality of trenches and the second group 1142 of the plurality of trenches. Trench dielectrics 1171, 1172 electrically separate the trench electrodes 1161, 1162 from a surrounding portion of the semiconductor body 102.

[0055] The first trench electrode 1161 is electrically coupled to an anode pad region 110, e.g., an anode terminal of a vertical diode such as a freewheeling diode, via an anode wiring line 112 and the second trench electrode 1162. The anode wiring line 112 and the second trench electrode 1162 are electrically connected in series between the anode pad region 110 and the first trench electrode 1161. In the figures, contacts 120 provide electrical contact between regions of the semiconductor body 104 and a first wiring level and / or electrical contact between electrodes in the trenches 114 and the first wiring level. The first wiring level may, for example, include the anode wiring line 112 or the anode pad region 110. An intermediate dielectric 118 is arranged between the first wiring level and the semiconductor body 104.The contacts 120 may correspond to a conductive filling in holes of the intermediate dielectric 118. For example, the contacts 120 may be contact plugs or contact lines.

[0056] Furthermore, the diode 100 includes an anode region 108 and a cathode region 109. Mesa regions 122 are bounded along a lateral direction x by adjacent two of the trenches 114. In the Fig. 1A to 1D, the anode region 108 is formed in the mesa regions 122. In some embodiments, a part of the cathode region 109 may also be formed in the mesa regions 122. According to other examples, the anode region 108 may extend to or below a bottom surface of the mesa regions 122. Apart from the details shown in the schematic views of Fig. 1A to 1D, additional trenches may be arranged, e.g., between the trenches 114 of the first group 1141 and the trenches 114 of the second group 1142. The cathode region 109 is electrically connected to a cathode terminal 124, e.g., a metal layer or a metal layer stack, on a second main surface 106 of the semiconductor body 102.

[0057] As shown in the cross-sectional view of Fig. 1C, the anode region 108 in the mesa region 122 may be electrically connected to the anode pad region 110 via a contact 120.

[0058] As shown in the cross-sectional view of Fig. 1D in combination with the cross-sectional view of Fig. 1B, the first trench electrode 1161 is electrically coupled to the anode pad region 110 via the anode wiring line 112 and the second trench electrode 1162. Contacts 120 formed between the first trench electrodes 1161 and the anode wiring line 112 provide a current from the first trench electrode 1161 to the anode wiring line 112. Furthermore, contacts between the second trench electrodes 1162 and the anode wiring line 112 provide this current from the anode wiring line 112 to the second trench electrodes 1162. Contacts formed between the second trench electrodes 1162 and the anode pad region 110 provide this current to the anode pad region 110. This provides an ohmic orResistive coupling of the first trench electrode 1161 to the anode pad region 110 such that, compared to a direct connection of the first trench electrode 1161, a higher ohmic resistance is provided between the first trench electrode 1161 and the anode pad region 110. Consequently, the current from the first trench electrode 1161 is forced to flow along a longitudinal extension of the second trench electrode 1162, see, for example, the longitudinal extension between the contacts 120 from the anode wiring line 112 to the second trench electrode 1162 in FIG. Fig. 1B and the contacts 120 from the second trench electrode 1162 to the anode pad region 110 in Fig. 1D. Furthermore, a resistance of the electrical connection of the anode pad region 110 via the contacts 120 to the anode region 108 is lower than a resistance of the electrical connection of the anode pad region to the first trench electrodes 1161.

[0059] Referring to the schematic cross-sectional view of Fig. 1E, the diode 100 may further be arranged, for example, between the trenches 114 of the first group 1141 and the trenches 114 of the second group 1142, which are shown in Fig. 1C, a third group 1143 of the plurality of trenches 114. The trenches 114 of the third group 1143 may include a third trench electrode 1163 and a trench dielectric 1173. Unlike the first trench electrodes 1161 of the first group 1141 of trenches 114, which are ohmically coupled to the anode pad region 110 by the second trench electrodes 1162 of the second group 1142 of trenches 114 (see, e.g., Fig. 1A), the third trench electrodes 1163 in the trenches 114 of the third group 1143 are electrically connected to the anode pad region 110 by contacts 120 arranged between the anode pad region 110 and the third trench electrode 1163. This enables a low-resistance connection of the third trench electrode 1163 to the anode pad region 110, thus providing a lower ohmic connection between the third trench electrode 1163 and the anode pad region 110 compared to the higher-resistance connection of the first trench electrode 1161 to the anode pad region 110. The provision of the third trench electrode 1163 can enable protection of the anode from high electric field strengths, which can, for example, limit the robustness of the diode circuit.

[0060] Different layouts of the trenches 114 can be realized in an active region of the diode 110.

[0061] For example, mesa regions 122 may be bounded along the lateral direction x by a trench 114 of the first group 1141 of trenches 114 and any one of the trenches 114 of the second group 1142 or the third group 1143. Likewise, mesa regions 122 may be bounded along the lateral direction x by a trench 114 of the second group 1142 of trenches 114 and any one of the trenches 114 of the first group 1141 or the third group 1143.

[0062] Another example of a diode 100 is shown in the schematic plan views of Fig. 2A, Fig. 2B and the schematic cross-sectional view of Fig. 2C illustrates.

[0063] Similar to the previous examples, the diode 100 includes a plurality of trenches 114 extending from a first main surface 104 into a semiconductor body 102, wherein a first group 1141 of the plurality of trenches 114 includes a first trench electrode 1161.

[0064] The first trench electrode 1161 is divided into at least a first part 1261 and a second part 1262. A conductance per unit length of the first part 1261 along a lateral direction y of the first trench electrode 1161 is lower than a conductance per unit length of the second part 1262 along the longitudinal direction y of the first trench electrode 1161.

[0065] The second part 1262 of the first trench electrode 1161 is electrically coupled to the anode pad region 110 via the first part 1261. In the schematic view of Fig. In Figure 2A, the anode pad region 110 is schematically illustrated by a terminal. The first part 1261 may, for example, be electrically connected to an anode wiring line through a contact or may be directly connected to the anode pad region through a contact.

[0066] Furthermore, the diode 100 includes an anode region 108 in a mesa region 122, which is surrounded by trenches 114 of the first group 1141.

[0067] Referring to the schematic plan view of Fig. 2B, a width w1 of the first trench electrode 1161 at the first main surface 104 in the first part 1261 is smaller than a width w2 in the second part 1262. This enables a reduction of a conductance per unit length of the first trench electrode 1161 in the first part 1261 along the longitudinal direction y compared to the second part 1262.

[0068] In addition or as an alternative to, for example, Fig. Figure 2B is the schematic cross-sectional view of Fig. 2C, taken along the longitudinal direction y of the first trench electrode 1161, shows an example of a diode with a vertical extension h1 of the first trench electrode 1161 in the first part 1261 that is less than a vertical extension h2 in the second part 1262 by forming the trench 114 of the second group 1142 shallower in the first part 1261 than in the second part 1262.

[0069] Another example of a diode 100 is shown in the schematic plan views of Fig. 3 illustrates.

[0070] Similar to the previous examples, the diode 100 includes a first group 1141 of trenches 114 including a first trench electrode 1161.

[0071] The first trench electrode 1161 is electrically coupled to an anode pad region 110 via an anode wiring line 112 and a resistor 130 placed on a substrate 132 different from the semiconductor body 102. The anode wiring line 112 and the resistor 130 are connected in series between the anode pad region 110 and the first trench electrode 1161. Bond wires 1341, 1342 may provide an electrical connection between an auxiliary anode pad region 136 in the wiring region of the semiconductor body 102 and the substrate 132. However, another connection technique, e.g., solder connections or vias with silicon, may be used.

[0072] Another example of a diode 100 is shown in the schematic plan view of Fig. 4 illustrates.

[0073] Instead of placing the resistor 130 on a substrate 132 different from the semiconductor body 102, the resistor 130 of the diode 100 is in Fig. 4 part of the diode 100 and can be arranged, for example, in the wiring area of ​​the diode 100. The resistor 130 can be implemented, for example, as a resistor made of polycrystalline silicon.

[0074] An example of a semiconductor device 200 is shown in the schematic cross-sectional view of Fig. 5 illustrates.

[0075] The semiconductor device 200 includes the diode 100 in a first part 1401 of the semiconductor body 102. Structural elements of the diode 100 may correspond to any of the structural elements or any combination of structural elements described with reference to the diodes 100 in the examples above. The structural elements of the diode 100 in the semiconductor body 102 are shown in the schematic view of Fig. 5 is not illustrated. The semiconductor device 200 further includes a switching device 101, e.g., a reverse conducting insulated gate bipolar transistor, RC-IGBT, in a second part 1402 of the semiconductor body 102. Structural elements of the switching device 101 in the semiconductor body 102 are shown in the schematic view of Fig. 5 is not illustrated.

[0076] The pad region 110 of the diode 100 and a load contact region 111 of the switching device 101 may be connected and form a common pad region 142. The common pad region 142 is electrically connected to active regions of the diode 100 and the switching device 101 through contacts 120. The diode 100 and the RC-IGBT 101 may be electrically connected in parallel between the common pad region 142 on the first main surface 104 and a load terminal 125, e.g., a metal layer or a metal layer stack, on the second main surface 106.

[0077] The aspects and features mentioned and described together with one or more of the previously described examples and figures may also be combined with one or more of the other examples to replace a similar feature of the other example or to additionally introduce the feature into the other example.

Claims

[1] Diode (100), comprising: a semiconductor body (102) having a first main surface (104) and a second main surface (106) opposite the first main surface (104); an anode region (108) and a cathode region (109), wherein the anode region (108) is arranged between the first main surface (104) and the cathode region (109); an anode pad region (110) electrically connected to the anode region (108); a plurality of trenches (114) extending from the first main surface (104) into the semiconductor body (102), wherein a first group (1141) of the plurality of trenches (114) includes a first trench electrode (1161) and a second group (1142) of the plurality of trenches (114) includes a second trench electrode (1162) and the first trench electrode (1161) is electrically coupled to the anode pad region (110) via an anode wiring line (112) and the second trench electrode (1162), such that a current path between the first trench electrode (1161) and the anode pad region (110) runs via the anode wiring line (112) and the second trench electrode (1162). [2] Diode (100) according to the preceding claim, wherein the anode wiring line (112) and the anode pad region (110) are separate parts of a structured wiring layer. [3] Diode (100) according to one of the preceding claims, wherein a ratio between a number of trenches (114) in the first group (1141) and a number of trenches (114) in the second group (1142) ranges from 100 to 100,000. [4] Diode (100) according to one of the preceding claims, wherein the anode wiring line (112) laterally surrounds at least a quarter of a circumference of the anode pad region (110). [5] Diode (100) according to one of the preceding claims, wherein the second trench electrodes (1162) are connected in parallel between the anode wiring line (112) and the anode pad region (110), and wherein a total resistance of the second group of trench electrodes connected in parallel multiplied by the total capacitance of the first group of trench electrodes is in a range between 100 ohms x nF and 100 ohms x µF. [6] The diode (100) of any preceding claim, wherein a conductance per unit length of the second trench electrode (1162) along a longitudinal direction (y) of the plurality of trenches (114) is smaller than a conductance per unit length of the first trench electrode (1161) along the longitudinal direction (y) of the plurality of trenches (114). [7] Diode (100), comprising: a semiconductor body (102) having a first main surface (104) and a second main surface (106) opposite the first main surface (104); an anode region (108) and a cathode region (109), wherein the anode region (108) is arranged between the first main surface (104) and the cathode region (109); an anode pad region (110) electrically connected to the anode region (108); a plurality of trenches (114) extending from the first main surface (104) into the semiconductor body (102), wherein a first group (1141) of the plurality of trenches (114) includes a first trench electrode (1161), the first trench electrode (1161) is divided into at least a first part (1261) and a second part (1262), a conductance per unit length of the first part (1261) along a longitudinal direction (y) of the first trench electrode (1161) is at least a factor of 1000 smaller than a conductance per unit length of the second part (1262) along the longitudinal direction (y) of the first trench electrode (1161) and the second part (1262) is electrically coupled to the anode pad region (110) via the first part (1261), so that a current path between the second part (1262) and the anode pad region (110) runs via the first part (1261). [8] Diode (100), comprising: a semiconductor body (102) having a first main surface (104) and a second main surface (106) opposite the first main surface (104); an anode region (108) and a cathode region (109), wherein the anode region (108) is arranged between the first main surface (104) and the cathode region (109); an anode pad region (110) electrically connected to the anode region (108); a plurality of trenches (114) extending from the first main surface (104) into the semiconductor body (102), wherein a first group (1141) of the plurality of trenches (114) includes a first trench electrode (1161), and the first trench electrode (1161) is electrically coupled to the anode pad region (110) via an anode wiring line (112) and a resistor (130), so that a current path between the first trench electrode (1161) and the anode pad region (110) runs via the anode wiring line (112) and the resistor (130). [9] Diode (100) according to the preceding claim, wherein the resistor (130) is arranged on a substrate (132) different from the semiconductor body (102). [10] Diode (100) according to the preceding claim, wherein the anode wiring line (112) merges into an auxiliary anode pad region (136) above the semiconductor body (102) and a first bonding wire (1341) electrically connects the auxiliary anode pad region (136) and a first end of the resistor (130) on the substrate (132). [11] Diode (100) according to one of the three preceding claims, wherein the resistor (130) is arranged in a wiring region above the first main surface (104). [12] The diode (100) of any preceding claim, wherein a third group (1143) of the plurality of trenches (114) includes a third trench electrode (1163), and wherein the third trench electrode (1163) is electrically connected to the anode pad region (110) via a contact (120) disposed in a portion of the first main surface (104) where the third trench electrode (1163) and the anode pad region (110) overlap each other. [13] Diode (100) according to one of the preceding claims, wherein the plurality of trenches (114) extend into the anode region (108) or extend through the anode region (108) and into the cathode region (109). [14] Diode (100), comprising: a semiconductor body (102) having a first main surface (104) and a second main surface (106) opposite the first main surface (104); an anode region (108) and a cathode region (109), wherein the anode region (108) is arranged between the first main surface (104) and the cathode region (109); an anode pad region (110) electrically connected to the anode region (108); a plurality of trenches (114) extending from the first main surface (104) into the semiconductor body (102), wherein a first group (1141) of the plurality of trenches (114) includes a first trench electrode (1161), wherein at least one resistance element (130) is coupled in series between the first trench electrode (1161) of each trench of the plurality of trenches (114) and the anode pad region (110), and wherein the diode (100) is configured to conduct a current in an on-state in a forward direction and to block a current in an off-state, wherein the diode (100) is configured to switch from the off-state to the on-state during a switching time, wherein the at least one resistance element (130) is configured such that a potential of each first trench electrode (1161) of the plurality of trenches (114) deviates from a potential of the anode pad region (110) by at least 2 V for at least 30% of the switching time. [15] Diode (100) according to the preceding claim, wherein the at least one resistance element (130) is configured such that the potential of each first trench electrode (1161) of the plurality of trenches (114) during the switching operation deviates from the potential of the anode pad region (110) by no more than 15 V for at least 30% of the switching time. [16] Diode (100) according to one of the two preceding claims, wherein the at least one resistance element (130) is configured such that the potential of each first trench electrode (1161) of the plurality of trenches (114) deviates from the potential of the anode pad region (110) by no more than 200 mV after a time interval of 5 µs from the switching operation. [17] A semiconductor device (200) comprising: the diode (100) according to any one of the preceding claims; and a reverse conducting insulated gate bipolar transistor, RC-IGBT, wherein the diode (100) and the RC-IGBT are electrically connected in parallel. [18] Semiconductor device (200) according to the preceding claim, wherein the anode pad region (110) of the diode (100) and a source contact region of the RC-IGBT are fused together.

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