VERTICAL POWER SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD

Abstract

Vertical power semiconductor device (100), comprising: a semiconductor body (102) having a first principal surface (104) and a second principal surface (106) opposite along a vertical direction (y) of the first principal surface (104); a gate-trench structure (108) on the first main surface (104), wherein at least part of the gate-trench structure (108) extends along a first lateral direction (x1); a body area (110) of a first conductivity type, directly adjacent to the gate trench structure (108); a source area (111) of a second conductivity type, directly adjacent to the gate trench structure (108), a drift region (120) of the second conductivity type, which is located between the body region (110) and the second main surface (106); a body contact structure (112) comprising a first body contact sub-region (1121) and a second body contact sub-region (1122) spaced at a first lateral distance (W) along the first lateral direction (x1), wherein each of the first body contact sub-region (1121) and the second body contact sub-region (1122) is directly adjacent to the gate trench structure (108) and has a higher doping concentration than the body region (110), wherein a part of the source region (111) is located between a part of the body contact structure (112) and the first main surface (104), and wherein in a channel area (114) between the first body contact sub-area (1121) and the second body contact sub-area (1122) the body contact structure (112) has a second lateral distance (L) to the gate trench structure (108) along a second lateral direction (x2) perpendicular to the first lateral direction (x1), wherein the first lateral distance (W) is equal to twice the second lateral distance (L) or less.

Description

TECHNICAL AREA

[0001] The present disclosure relates to semiconductor devices, in particular vertical power semiconductor devices, which include a body contact structure. BACKGROUND

[0002] In semiconductor switching devices such as IGBTs (insulated-gate bipolar transistors) or diodes, mobile charge carriers flood a lightly doped drift region and form a charge carrier plasma, which provides a low on-resistance. Such semiconductor devices are known, for example, from US 2008 / 0012040A1 and US 2017 / 0005186A1. One goal of semiconductor device technology is the design of semiconductor switching devices with specified reliability and operational safety. The operational safety of semiconductor switching devices is affected when the devices are operated under extreme conditions, such as when high overcurrents are switched off. Consequently, the development of semiconductor device technology faces the challenge of meeting target requirements for the operational safety of devices with regard to extreme operating conditions.

[0003] There is a need to improve the operational reliability of devices in vertical power semiconductor devices. SUMMARY

[0004] The invention is defined in the independent patent claims. Further developments are the subject of the dependent patent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The accompanying drawings are enclosed to provide a further understanding of the embodiments and are incorporated into and form part of this description. The drawings illustrate embodiments of a vertical power semiconductor device and a method for fabricating a vertical power semiconductor device and, together with the description, serve to explain the principles of the embodiments. Further embodiments are described in detail in the following description and the claims. Fig. Figures 1A to 1C are schematic top and cross-sectional views to illustrate an example of a vertical power IGBT incorporating a continuous body contact structure and a recess contact. Fig. Figures 2A to 2D are schematic top and cross-sectional views to illustrate another example of a vertical power IGBT, which includes a body contact structure with body contact sub-regions and a recess contact and separate source sub-regions. Fig. Figures 3A to 3D are schematic top and cross-sectional views to illustrate another example of a vertical power IGBT incorporating a planar contact. Fig. Figures 4A to 4C are schematic top and cross-sectional views to illustrate examples of body contact structure designs. Fig. Figures 5A to 5F are schematic top views to illustrate examples of square and polygonal IGBT cell designs. Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11 to Fig. Figure 12 are schematic cross-sectional views to illustrate examples of IGBT transistor areas containing gate trench structures and auxiliary trench structures. DETAILED DESCRIPTION

[0006] The terms "have," "contain," "comprise," "exhibit," and the like are open-ended terms, indicating the presence of the identified structures, elements, or features, but not excluding the presence of additional elements or features. Indefinite and definite articles should encompass both the plural and the singular unless the context clearly indicates otherwise.

[0007] The term "electrically connected" describes a permanent, low-resistance connection between electrically connected elements, for example, a direct contact between the elements in question or a low-resistance connection via a metal and / or a highly doped semiconductor material. The term "electrically coupled" implies that one or more intermediate elements suitable for signal and / or power transmission may be connected between the electrically coupled elements, for example, elements that temporarily provide a low-resistance connection in a first state and a high-resistance electrical decoupling in a second state. A resistive contact is a non-rectifying electrical junction with a linear or nearly linear current-voltage characteristic.

[0008] The figures and description illustrate relative doping concentrations by indicating "-" or "+" next to the doping type "n" or "p". For example, "n" means - “a doping concentration that is lower than the doping concentration of an “n” doping area, while an “n + A doping region with a relative concentration of n-type doping has a higher doping concentration than an n-type doping region. Doping regions with the same relative concentration doping doping do not necessarily have the same absolute concentration. For example, two different n-type doping regions can have the same or different absolute concentrations of doping.

[0009] For physical dimensions, specified ranges include the boundary values. For example, a range for a parameter y from a to b is read as a ≤ y ≤ b. A parameter y with a value of at least c is read as c ≤ y, and a parameter with a value of at most d is read as y ≤ d.

[0010] The term "on" should not be interpreted as meaning 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) can be positioned between the two elements (e.g., another layer can be positioned between a layer and a substrate if the layer is "on" the substrate).

[0011] An example of a vertical power semiconductor device can have a semiconductor body having a first main surface and a second main surface opposite to the first main surface along a vertical direction. The vertical power semiconductor device can further have a gate-trench structure on the first main surface. At least part of the gate-trench structure can extend along a first lateral direction. The vertical power semiconductor device can also include a body region of a first conductivity type directly adjacent to the gate-trench structure. The vertical power semiconductor device can further include a source region of a second conductivity type directly adjacent to the gate-trench structure.The vertical power semiconductor device can further include a second-type conductivity drift region located between the body region and the second main surface. The vertical power semiconductor device can also include a body contact structure comprising a first body contact subregion and a second body contact subregion spaced at a first lateral distance along the first lateral direction. Each of the first and second body contact subregions can be directly adjacent to the gate trench structure and can have a higher doping concentration than the body region. In a channel region between the first and second body contact subregions, the body contact structure can have a second lateral distance from the gate trench structure along a second lateral direction perpendicular to the first lateral direction.The first lateral distance can be equal to twice the second lateral distance or less.

[0012] The vertical power semiconductor device can be a power semiconductor IGBT (insulated gate bipolar transistor), a reverse conducting (RC) power semiconductor IGBT, or a power semiconductor transistor such as a power semiconductor IGFET (insulated gate field-effect transistor, e.g., a metal oxide semiconductor field-effect transistor). The vertical power semiconductor device can be configured to conduct currents greater than 1 A, 10 A, or even 30 A, and can furthermore be configured to block voltages between load terminals, e.g., between the emitter and collector of an IGBT or between the drain and source of a MOSFET, in a 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 can, for example, correspond to a voltage class specified in a datasheet for the power semiconductor device.

[0013] The semiconductor body may contain or consist of a semiconductor material from the elemental semiconductors of Group IV, a IV-IV composite semiconductor material, a III-V composite semiconductor material, or a II-VI composite semiconductor material. Examples of semiconductor materials from elemental semiconductors of Group IV include silicon (Si) and germanium (Ge). Examples of IV-IV composite semiconductor materials include silicon carbide (SiC) and silicon germanium (SiGe). Examples of III-V composite semiconductor materials include 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 composite semiconductor materials include cadmium telluride (CdTe), mercury cadmium telluride (CdHgTe), and cadmium magnesium telluride (CdMgTe).For example, the semiconductor body can be a magnetic Czochralski, MCZ, or floating zone (FZ) or an epitaxially deposited silicon semiconductor body.

[0014] The gate-trough structure can, for example, contain an electrode, e.g., a gate electrode as at least part of the electrode, and a dielectric, e.g., a gate dielectric as at least part of the dielectric, within a gate-trough. The dielectric can comprise a layer or a combination of layers, e.g., a stack of dielectric layers, for example, oxide layers such as thermal oxide layers or deposited oxide layers, e.g., undoped silicate glass (USG), phosphosilicate glass (PSG), borosilicate glass (BSG), boron phosphosilicate glass (BPSG), nitride layers, dielectric layers with a high dielectric constant, or dielectric layers with a low dielectric constant. The electrode can comprise 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, metal, or metal compounds. The gate-trench structure can contain one or multiple parts extending along different lateral directions. For example, the gate-trench structure can be strip-shaped and extend along the first lateral direction. The first lateral direction can be perpendicular to the vertical direction, e.g., a direction extending parallel to the first main surface. If the gate-trench structure contains multiple parts extending along different lateral directions, the lateral direction of each part can, for example, define a longitudinal direction of that part of the gate-trench structure.

[0015] The source area can, for example, border on one opposite side wall of a gate trench or on both sides of the gate trench structure.

[0016] The concentration of impurities or foreign substances in the drift region can, for example, increase or decrease gradually or in steps with increasing distance from the first main surface, at least in parts of its vertical extent. According to other examples, the impurity concentration in the drift region can be approximately uniform. For silicon-based IGBTs, the average impurity concentration in the drift region can be between 5 × 10 12 cm -3 and 1 × 10 15 cm -3 , for example in an area of ​​1 × 10 13 cm -3 up to 2 × 10 14 cm -3 , lie. In the case of a SiC-based semiconductor device, the average defect concentration in the drift region can be between 5 × 10 14 cm -3 and 1 × 10 17 cm -3 , for example in an area of ​​1 × 10 15 cm -3 up to 2 × 10 16 cm -3The vertical extent of the drift region may depend on voltage blocking requirements, such as a specified voltage class, of the vertical power semiconductor device. When the vertical power semiconductor device is operated in a voltage blocking mode, a space charge region may extend partially or completely vertically through the drift region, depending on the blocking voltage applied to the vertical power semiconductor device. If the vertical power semiconductor device is operated at or near the specified maximum blocking voltage, the space charge region may reach or penetrate a field stop region. The field stop region is configured to prevent the space charge region from extending further toward the cathode or collector on the second primary surface of the semiconductor body.In this way, the drift or base region can be formed using desired low doping levels and with a desired thickness, while achieving smooth switching for the semiconductor device thus formed.

[0017] The body contact structure can, for example, comprise a contact, such as a metal contact like a connector, directly adjacent to the first major surface of the semiconductor body, and a variety of doped body contact subregions. Some or all of the body contact subregions in a mesa region can be laterally separated from one another. The mesa region is laterally bounded by opposing trench structures. Additionally, or alternatively, some or all of the body contact separating regions in a mesa region can be fused or connected to form a continuous body contact structure, or they can form a continuous portion of the body contact structure. For example, some or all of the body contact subregions can be stripe-shaped along the second lateral direction.

[0018] For example, the maximum doping concentration of some or all of the body contact sub-areas may be higher than the maximum doping concentration of the body region. Similarly, the vertical doping concentration profile of the body contact sub-areas may differ from the vertical doping concentration of the body region.

[0019] The second lateral distance between the body contact structure and the gate trench structure along the second lateral direction can, for example, be a distance between a gate dielectric of the gate trench structure and a body contact subregion. Alternatively, the second lateral distance between the body contact structure and the gate trench structure along the second lateral direction can also be a distance between a gate dielectric of the gate trench structure and a contact, e.g., a planar contact of the body contact structure.

[0020] When high currents, such as overcurrents, are switched off, carriers originating from below the gate trench midway between the first and second body contact subregions must reach the contact. By setting the first lateral distance equal to twice the second lateral distance in a channel region between the first and second body contact subregions, or less, the voltage drop caused by carriers flowing from the midway between the first and second body contact subregions to the contact can be reduced with respect to two current paths along the first lateral direction: one current path from the midway to the first body contact subregion and another current path from the midway to the second body contact subregion.The reduction in voltage drop is achieved by splitting the current path into two current paths, compared to a single current path along the second lateral direction, in cases where the current paths along the first lateral direction are not attractive to the carriers with respect to path resistance. A reduction in voltage drop enables an increase in latch-up robustness, and thus the operational reliability of a device in vertical power semiconductor devices can be improved.

[0021] For example, the source region can have a multitude of source subregions spaced apart along the first lateral direction. One of these source subregions can be located between the first and second body contact subregions. The multitude of source subregions can, for example, extend as strip-like segments parallel to each other along the second lateral direction. Since the body contact subregions, e.g., the first and second body contact subregions, are not electrically compensated or counter-doped by the source region, a higher number of activated dopants in the body contact subregions can, for example, help to dissipate carriers during overcurrent shutdown. This can, for example, lead to a further improvement in latch-up robustness.

[0022] For example, part of the body area can be located along the first lateral direction between the first body-contact sub-area and one of the multiple source sub-areas. This makes the effective channel width independent of any potential misalignment between one of the multiple source sub-areas and the first body-contact sub-area.

[0023] The first body contact subregion can, for example, extend deeper into the semiconductor body along the vertical direction from the first main surface than the source region. This can enable increased conductivity when carriers are diverted during overcurrent shutdown, for example, below regions where the source region is located.

[0024] For example, part of the source region may be located between a portion of the body contact structure and the first main surface. In this case, the contact to the source region and the body contact structure may have a greater distance to the gate trench structure than the second lateral distance.

[0025] The body contact structure can, for example, further include a third body contact structure that connects the first and second body contact sub-regions. A lateral distance between the gate trench structure and the third body contact sub-region along the second lateral direction can be equal to the second lateral distance. For example, the third body contact sub-region can be directly adjacent to a planar contact on the first main surface or directly adjacent to a contact depression. The third body contact sub-region can enable improved carrier dissipation during high-current shutdowns, for example, by optimizing current paths with respect to latch-up robustness.

[0026] The body contact structure can, for example, include a contact within a contact depression. The third body contact sub-region can directly border a lateral surface portion of the contact. The contact depression can extend from the first main surface into the semiconductor body. The third body contact sub-region can also, for example, border a bottom side of the contact depression. The contact depression can, for example, improve the area of ​​a contact surface facing both the body contact region and the source region. Thus, an electrical contact resistance can, for example, be reduced.

[0027] The source area can, for example, border directly on a lateral surface of the contact in the contact depression.

[0028] The base of the contact can, for example, border an electrode in a trench structure, such as an auxiliary trench structure. The electrode in the trench structure can be separated from the body region by a dielectric in the same or a similar manner as the gate electrode. The electrode in the trench structure can also be different from the gate electrode. For example, the electrode in the trench structure can be electrically connected to the source region, e.g., via a source contact surface. The electrode can also be electrically connected to a reference voltage output. This allows for a compact electrical connection of various structural elements, such as the body region, the source region, and the electrode.

[0029] The vertical power semiconductor device may, for example, further include a first- or second-type barrier region located between the body region and the drift region. The barrier region may, for example, be a first-type barrier region located in a mesa region between the body region and the bottom of the trench-gate structure, or partially below the trench-gate structure. The first-type barrier region and the body region may be vertically spaced apart. The barrier may, for example, improve the robustness of the device. Alternatively, the barrier region may also be a second-type barrier region located in a mesa region between the body region and the bottom of the trench-gate structure.The barrier region of the second conductivity type and the body region can, for example, be vertically spaced apart or directly adjacent to each other. The barrier can, for example, allow an increase in the carrier concentration during an on-state of the device.

[0030] The body contact structure can, for example, also have a contact. The contact can be a planar contact with a lateral distance to the gate trench structure along the second lateral direction, which is equal to the second lateral distance.

[0031] The vertical power semiconductor device can, for example, further comprise a plurality of channel regions spaced apart along the first lateral direction. All or some of the plurality of channel regions can be arranged between body-contact subregions of the body-contact structure along the first lateral direction. Thus, along a longitudinal direction of a straight region of the gate-trench structure, all or some of the plurality of channel regions can, for example, be arranged between adjacent pairs of body-contact subregions. The channel regions can be parts of the body region that directly adjoin the gate-trench structure, and the channel regions can, for example, further adjoin a bottom face of the source region.

[0032] The vertical power semiconductor device can, for example, further contain a plurality of transistor cells. The plurality of transistor cells can have one or more strip-shaped, square, or polygonal cell designs. The plurality of transistor cells can share a common first load electrode, such as a source electrode or emitter electrode. Thus, the plurality of transistor cells is electrically connected in parallel.

[0033] At least part of the gate trench structure extends, for example, along the second lateral direction. The body contact structure can directly adjoin a portion of the gate trench structure extending along the first lateral direction and a portion of the gate trench structure extending along the second lateral direction. Thus, effective carrier dissipation during the shutdown of large currents can be achieved in differently oriented segments of vertical power semiconductor transistors with a square cell design or a polygonal cell design.

[0034] The multitude of transistor cells can include, for example, cells of insulated-gate bipolar transistors, IGBT cells, or cells of reverse-conducting insulated-gate bipolar transistors, RC-IGBT cells.

[0035] The source area can, for example, border directly on the gate-trench structure on only one of its opposite side walls. Thus, a channel area can only form on one of the opposite side walls of the gate-trench structure. For example, the body contact structure can border directly on a side wall of another trench structure that is opposite the gate-trench structure.

[0036] A method for fabricating a vertical power semiconductor device may, for example, include providing a semiconductor body having a first main surface and a second main surface oriented along a vertical direction opposite the first main surface. The method may further include forming a gate-trench structure on the first main surface. At least a portion of the gate-trench structure may extend along a first lateral direction. The method may also include forming a body region of a first conductivity type directly adjacent to the gate-trench structure. Furthermore, the method may include forming a source region of a second conductivity type directly adjacent to the gate-trench structure. Finally, the method may include forming a drift region of the second conductivity type located between the body region and the second main surface.The process can further include the formation of a body-contact structure comprising a first body-contact sub-region and a second body-contact sub-region spaced at a first lateral distance along the first lateral direction. Each of the first and second body-contact sub-regions can be directly adjacent to the gate-trench structure and can have a higher doping level than the body region. In a channel region between the first and second body-contact sub-regions, the body-contact structure can have a second lateral distance to the gate-trench structure along a second lateral direction perpendicular to the first lateral direction. The first lateral distance can be equal to twice the second lateral distance or less.

[0037] The examples and features described above and below can be combined.

[0038] Further examples of vertical power semiconductor devices and manufacturing processes are explained below in conjunction with the accompanying drawings. Functional and structural details described in relation to the examples above apply equally to the exemplary embodiments illustrated in the figures and further described below.

[0039] Fig. Figure 1A is a schematic top view illustrating an embodiment of an insulated gate bipolar transistor, IGBT 101, as an example of a vertical power semiconductor device 100. Fig. 1B is a schematic cross-sectional view along a section line AA of Fig. 1A. Fig. 1C is a schematic cross-sectional view along a section line BB of Fig. 1A.

[0040] Referring to the schematic views of the Fig. 1A to 1C the IGBT 101 contains a semiconductor body 102 which has a first main surface 104 and a second main surface 106 opposite along a vertical direction y of the first main surface 104.

[0041] A gate-trench structure 108 is formed on the first main surface 104. At least part of the gate-trench structure 108 extends along a first lateral direction x1. The first lateral direction x1 can be a longitudinal direction of a segment of the gate-trench structure 108. The gate-trench structure contains a gate dielectric 1081 and a gate electrode 1082.

[0042] A p-doped body region 110 borders directly on the gate-trench structure 108. An n + -doped source area 111 borders directly on the gate trench structure (for simplicity's sake in Fig. 1A not shown). An n -A -doped drift region 120 is located between the p-doped body region 110 and the second main surface 106. An n-doped field stop region 122 is located between the n-doped drift region 120 and the second main surface 106. A p + -doped region 124, e.g. a semiconductor substrate and / or a back-side emitter region of the IGBT 101, is arranged between the field-stop region 122 and the second main surface 106.

[0043] A p + -doped body contact structure 112 comprises a first p + -doped body contact sub-area 1121 and a second p + doped body contact sub-area 1122, which are spaced along the first lateral direction x1 at a first lateral distance W. Both the first p + -doped body contact sub-area 1121 as well as the second p +-doped body contact subregion 1122 borders directly on the gate trench structure 108 and has a higher doping concentration than the p + endowed body area 110.

[0044] In a canal area 114 of body area 110 between the first p + -doped body contact sub-area 1121 and the second p + -doped body contact subarea 1122 shows the p +The p-doped body contact structure 112 extends a second lateral distance L to the gate trench structure 108 along a second lateral direction x2 perpendicular to the first lateral direction x1. The first lateral distance W is equal to twice the second lateral distance L, or less, or less than 1.5 times the second lateral distance L, or even equal to or less than the second lateral distance L. The channel region 114 is a part of the p-doped body region 110 that directly borders the gate trench structure 108. The conductivity in the channel region can be controlled, for example, by a gate voltage applied to the gate electrode.

[0045] The p + -doped body contact structure 112 further contains a third p + -doped body contact subarea 1123, which is the first p + -doped body contact subarea 1121 and the second p +The endowed body contact sub-area 1122 connects with each other. A lateral distance between the gate trench structure 108 and the third p + -doped body contact sub-area 1123 along the second lateral direction x2 is equal to the second lateral distance L.

[0046] The first p + The -doped body contact subregion 1121 extends along the vertical direction y from the first main surface 104 deeper into the semiconductor body 102 than the source region 111. Part of the source region 111 is located between a part of the body contact structure 112 and the first main surface 104.

[0047] The p + The -doped body contact structure 112 further contains a contact 1129 in a contact depression 118. The third p + The doped body contact sub-area 1123 borders directly on a part of the lateral surface of the contact 1129.

[0048] The contact 1129 transitions into a first load electrode 126, e.g., an emitter electrode or source electrode. An intermediate layer dielectric 128 is arranged between the first load electrode 126 and the first main surface 104.

[0049] A second load electrode 130, e.g. a collector electrode, is directly adjacent to the p + -doped area 124 on the second main surface 106 and connects it electrically.

[0050] Fig. Figure 2A is a schematic top view illustrating another embodiment of an insulated gate bipolar transistor, IGBT 101, as an example of a vertical power semiconductor device 100. Fig. 2B is a schematic cross-sectional view along a section line AA of Fig. 2A. Fig. 2C is a schematic cross-sectional view along a section line BB of Fig. 2A. Fig. 2D is a schematic cross-sectional view along a section line CC of Fig. 2A.

[0051] The in Fig. 2A to 2D illustrated IGBT 101 has with the in Fig. Figures 1A to 1C illustrate IGBT 101's structural and functional elements together. To avoid repeating the description of such common structural and functional elements, the above explanations apply to the embodiment of the Fig. 1A to 1C equally for those in Fig. 2A to 2D illustrate embodiment.

[0052] Referring to the schematic views of the Fig. In sections 2A to 2D, the IGBT 101 has a plurality of source subregions 1110 spaced apart from each other along the first lateral direction x1. One of the plurality of source subregions 1110 is located between the first body contact subregion 1121 and the second body contact subregion 1122.

[0053] In the Fig. The embodiment illustrated in 2A to 2D represents the body contact sub-areas, e.g. the first p + -doped body contact subarea 1121 and the second p + -doped body contact subregion 1122, spaced apart from each other along the first lateral direction x1. For example, the body contact subregions can be separated, for instance, by means of the third body contact subregion 1123, as in Fig. 1A illustrates that they are interconnected.

[0054] Part of body area 110 is arranged along the first lateral direction x1 between the first body contact sub-area 1121 and one of the multiple source sub-areas.

[0055] Fig. Figure 3A is a schematic top view illustrating another embodiment of an insulated gate bipolar transistor, IGBT 101, as an example of a vertical power semiconductor device 100. Fig. 3B is a schematic cross-sectional view along a section line AA of Fig. 3A. Fig. 3C is a schematic cross-sectional view along a section line BB of Fig. 3A. Fig. 3D is a schematic cross-sectional view along a section line CC of Fig. 3A.

[0056] The in Fig. 3A to 3D illustrated IGBT 101 has with the in Fig. Figures 1A to 1C illustrate the structural and functional elements of IGBT 101 together. To avoid repeating the description of such common structural and functional elements, the above explanations apply to the embodiment of the Fig. 1A to 1C equally for those in the Fig. 3A to 3D illustrate embodiment.

[0057] Referring to the schematic views of the Fig. 3A to 3D, the contact 1129 of the body contact structure 112 is a planar contact with a lateral distance to the gate trench structure 108 along the second lateral direction x2, which is equal to the second lateral distance L.

[0058] Fig. 4A and Fig. Figure 4B shows schematic top views illustrating other embodiments of an insulated gate bipolar transistor, IGBT 101, as an example of a vertical power semiconductor device 100. Fig. 4C is a schematic cross-sectional view along a section line AA of Fig. 4B.

[0059] Referring to the schematic view of Fig. 4A can extend the body contact structure 112 between opposing gate-trough structures 108 into a first part between a first gate-trough structure 108, e.g. the gate-trough structure on the left side of Fig. 4A, Fig. 4B, and contact 1129 and a second part between a second gate trench structure 108, e.g. the gate trench structure on the right side of Fig. 4A, Fig. 4B, and the contact 1129 will be shared. In the Fig. In the embodiment illustrated in 4A, the first and second parts are arranged symmetrically with respect to contact 1129. In the embodiment shown in Fig. 4B, Fig. In the embodiment illustrated in 4C, the first and second parts are compared to the one in Fig. 4A illustrates the arrangement along the first lateral direction x1, additionally offset.

[0060] Fig. Figures 5A to 5F are schematic top views illustrating embodiments of closed cell geometries of insulated gate bipolar transistors 101.

[0061] In the Fig. The embodiments illustrated in 5A to 5D feature a rectangular cell design ( Fig. 5A, Fig. 5C) and a square cell design with rounded corners ( Fig. 5B, Fig. 5D). Contact 1129 can be a contact in a contact depression or a planar contact. An illustration of source area 111 is shown in Fig. 5A, Fig. 5B omitted and in Fig. 5C, Fig. 5D added. In the Fig. In the embodiments illustrated in Figures 5A to 5D, a first part of the gate-trench structure 108 extends along the first lateral direction x1, and a second part of the gate-trench structure 108 extends along the second lateral direction x2. The body-contact structure 112 is directly adjacent to the first and second parts of the gate-trench structure 108, respectively.

[0062] In the Fig. In the embodiments illustrated in Figures 5E to 5F, a polygonal cell design, e.g., an octagonal cell design, is used. The contact 1129 can be a contact in a contact recess or a planar contact.

[0063] In the Fig. In the embodiments illustrated in Figures 5A to 5F, the number and widths of the source regions 111 and / or channel regions may differ. For example, the number of channel regions in one part of the gate-trench structure 108 extending along the first lateral direction x1 may differ from the number of channel regions in another part of the gate-trench structure 108 extending along the second lateral direction x2.

[0064] The transistor cells described with reference to the embodiments above can be integrated into a transistor region. Examples of transistor regions are described with reference to the following figures.

[0065] Referring to the schematic cross-sectional view of Fig. In addition to the gate trench structures 108 and transistor cell designs described above, the IGBT 101 contains auxiliary trench structures 109 integrated into the transistor area. These auxiliary trench structures 109 can contain electrodes electrically connected to a potential different from that of the gate electrode. The electrodes in the auxiliary trench structures 109 can be connected to one or more of a source potential, a reference voltage output, or a resistive or capacitive voltage divider. In a mesa region between these additional auxiliary trench structures 109, one or more of the channel regions, source regions, or body contact regions can be omitted.

[0066] The IGBT 101 also contains an n-doped barrier region 133, which is located between the body region 110 and the drift region 120.

[0067] Referring to the schematic cross-sectional view of Fig. In section 7, the auxiliary trench structures 109 are recessed, and the width of the contact 1129 of the body contact structure 112 is increased. As a result, the contact 1129 is electrically connected not only to the body contact structure 112 and the source region 111, but also to the electrode of the auxiliary trench structure 109. This can, for example, enable an improved, more compact design of transistor regions.

[0068] The schematic views of the Fig. 8, Fig. 9, Fig. 10 to Fig. Figure 11 are exemplary cross-sectional views of rectangular or polygonal IGBT cell designs, as presented in Fig. Figures 5A to 5F illustrate, or strip-shaped cell designs. The IGBT cells can be surrounded by a p-doped structure 134, which can be electrically floating or connected to an emitter potential, e.g., to the first load electrode 126. The p-doped structure 134 can, for example, be formed at least partially simultaneously with the body region 110. The p-doped structure 134 can also, for example, contain a deep p-well 135.

[0069] In the schematic cross-sectional view of Fig. Figure 12 illustrates a reverse-conducting RC-IGBT 101. In the RC-IGBT 101 of Fig. 12 are one or more n + -endowed areas 136 between p +The p-doped regions 124 are arranged on the second main surface 106. Furthermore, the contact 1129 is configured as a deep recess contact that extends at least as deep into the semiconductor body 102 as the body contact structure 112. This allows, for example, the emitter efficiency of p-doped regions on the first main surface 104 to be reduced. The RC-IGBT 101 can include RC-IGBT cells 137 mixed with diode cells 138. Channel regions are omitted in the diode cells, and these cells are configured to act as diodes connected in parallel with the RC-IGBT cells 137.

[0070] The aspects and features mentioned and described in conjunction with one or more of the previously described examples and figures can likewise be combined with one or more of the other examples to replace an identical feature of the other example or to additionally introduce the feature into the other example. For example, the previous examples described with reference to IGBTs can be used for RC-IGBTs by, for instance, extending the RC functionality into the IGBT as shown on the second main surface 106 of Fig. 12 is illustrated and included.

[0071] The conductivity type of the doped regions illustrated in the examples above can also be reversed, i.e., for example, a region illustrated as n-doped can be p-doped and a region illustrated as p-doped can be n-doped.

Claims

[1] Vertical power semiconductor device (100) comprising: a semiconductor body (102) having a first principal surface (104) and a second principal surface (106) opposite along a vertical direction (y) of the first principal surface (104); a gate-trench structure (108) on the first main surface (104), wherein at least part of the gate-trench structure (108) extends along a first lateral direction (x1); a body area (110) of a first conductivity type, directly adjacent to the gate trench structure (108); a source area (111) of a second conductivity type, directly adjacent to the gate trench structure (108), a drift region (120) of the second conductivity type, which is located between the body region (110) and the second main surface (106); a body contact structure (112) comprising a first body contact sub-region (1121) and a second body contact sub-region (1122) spaced at a first lateral distance (W) along the first lateral direction (x1), wherein each of the first body contact sub-region (1121) and the second body contact sub-region (1122) is directly adjacent to the gate trench structure (108) and has a higher doping concentration than the body region (110), wherein a part of the source region (111) is located between a part of the body contact structure (112) and the first main surface (104), and wherein in a channel area (114) between the first body contact sub-area (1121) and the second body contact sub-area (1122) the body contact structure (112) has a second lateral distance (L) to the gate trench structure (108) along a second lateral direction (x2) perpendicular to the first lateral direction (x1), wherein the first lateral distance (W) is equal to twice the second lateral distance (L) or less. [2] Vertical power semiconductor device (100) according to the preceding claim, wherein the source region (111) comprises a plurality of source subregions spaced apart from one another along the first lateral direction (x1) and wherein one of the plurality of source subregions is arranged between the first body contact subregion (1121) and the second body contact subregion (1122). [3] Vertical power semiconductor device (100) according to the preceding claim, wherein a part of the body region (110) is arranged along the first lateral direction (x1) between the first body contact subregion (1121) and one of the plurality of source subregions. [4] Vertical power semiconductor device (100) according to one of the preceding claims, wherein the first body contact sub-region (1121) extends along the vertical direction (y) from the first main surface (104) deeper into the semiconductor body (102) than the source region (111). [5] Vertical power semiconductor device (100) according to one of the preceding claims, wherein the body contact structure (112) further comprises a third body contact sub-area (1123) connecting the first body contact sub-area (1121) and the second body contact sub-area (1122), wherein a lateral distance between the gate trench structure (108) and the third body contact sub-area (1123) along the second lateral direction (x2) is equal to the second lateral distance (L). [6] Vertical power semiconductor device (100) according to the preceding claim, wherein the body contact structure (112) further comprises a contact (1129) in a contact recess (118) and wherein the third body contact sub-area (1123) directly borders a part of a lateral surface of the contact (1129). [7] Vertical power semiconductor device (100) according to the preceding claim, wherein the source region (111) is directly adjacent to a lateral surface of the contact (1129) in the contact recess (118). [8] Vertical power semiconductor device (100) according to one of the two preceding claims, wherein a base of the contact (1129) borders an electrode in a trench structure. [9] Vertical power semiconductor device (100) according to any one of the preceding claims, further comprising: a barrier area of ​​the first or second conductivity type, located between the body area (110) and the drift area (120). [10] Vertical power semiconductor device (100) according to any one of claims 1 to 4, wherein the body contact structure (112) further includes a contact (1129) and wherein the contact (1129) is a planar contact having a lateral distance to the gate trench structure (108) along the second lateral direction (x2) which is equal to the second lateral distance (L). [11] Vertical power semiconductor device (100) according to one of the preceding claims, further comprising a plurality of channel regions (114) spaced apart from each other along the first lateral direction (x1), wherein all or some of the plurality of channel regions (114) are arranged along the first lateral direction (x1) between body contact subregions of the body contact structure (112). [12] Vertical power semiconductor device (100) according to any one of the preceding claims, wherein the vertical power semiconductor device (100) comprises a plurality of transistor cells and wherein the plurality of transistor cells has one or more of a strip-shaped cell design, a square cell design or a polygonal cell design. [13] Vertical power semiconductor device (100) according to the preceding claim, wherein at least a part of the gate trench structure (108) extends along the second lateral direction (x2) and wherein the body contact structure (112) is directly adjacent to a part of the gate trench structure (108) extending along the first lateral direction (x1) and to a part of the gate trench structure (108) extending along the second lateral direction (x2). [14] Vertical power semiconductor device (100) according to one of the two preceding claims, wherein the plurality of transistor cells are cells of insulated gate bipolar transistors, IGBT cells or cells of insulated gate bipolar transistors, RC-IGBT cells. [15] Vertical power semiconductor device (100) according to one of the preceding claims, wherein the source region (111) is directly adjacent to the gate trench structure (108) on one of opposite side walls. [16] Vertical power semiconductor device (100) according to one of the preceding claims, wherein the Body contact structure (112) extends along the second lateral direction (x2) from a side wall of the gate trench structure (108) to a side wall of an adjacent gate trench structure (108). [17] Method for manufacturing a vertical power semiconductor device (100), comprising: Providing a semiconductor body (102) having a first principal surface (104) and a second principal surface (106) opposite along a vertical direction (y) of the first principal surface (104); Forming a gate-trench structure (108) on the first main surface (104), wherein at least part of the gate-trench structure (108) extends along a first lateral direction (x1); Formation of a body area (110) of a first conductivity type directly adjacent to the gate trench structure (108); Forming a source area (111) of a second conductivity type directly adjacent to the gate trench structure (108); Forming a drift region (120) of the second conductivity type, which is arranged between the body region (110) and the second main surface (106); Forming a body contact structure (112) comprising a first body contact sub-region (1121) and a second body contact sub-region (1122) spaced along the first lateral direction (x1) at a first lateral distance (W), wherein each of the first body contact sub-region (1121) and the second body contact sub-region (1122) is directly adjacent to the gate trench structure (108) and has a higher doping concentration than the body region (110), wherein a part of the source region (111) is located between a part of the body contact structure (112) and the first main surface (104), and wherein in a channel area (114) between the first body contact sub-area (1121) and the second body contact sub-area (1122) the body contact structure (112) has a second lateral distance (L) to the gate trench structure (108) along a second lateral direction (x2) perpendicular to the first lateral direction (x1), wherein the first lateral distance (W) is equal to twice the second lateral distance (L) or less.

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