Semiconductor diode and manufacturing process

Abstract

Semiconductor diode (100), comprising: a wide bandgap semiconductor body (104) having a first surface (106) and a second surface (107) opposite the first surface (106), wherein the wide bandgap semiconductor body (104) has a first pn junction diode (102) having a first p-doped region (1021) adjacent to the first surface (106) and a first n-doped region (1022) adjacent to the first surface (106) and the second surface (107); a semiconductor element, wherein the semiconductor element has a second pn junction diode (112) having a second p-doped region (1121) and a second n-doped region (1122); a dielectric structure (110) between the wide band gap semiconductor body (104) and the semiconductor element and electrically insulating the wide band gap semiconductor body (104) from the semiconductor element; a cathode contact (C); an anode contact (A) above the first surface (106), wherein the anode contact is electrically connected to the second p-doped region (1121) and the first p-doped region (1021) is electrically coupled to the anode contact (A); where the band gap energy of the semiconductor element is lower than the band gap energy of the wide band gap semiconductor body (104); wherein the cathode contact (C) is electrically connected to the first n-doped region (1022) on the second surface (107); and wherein the second n-doped region (1122) of the second pn junction diode (112) is electrically coupled to the first n-doped region (1022) of the first pn junction diode.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a semiconductor diode and a manufacturing process, in particular to a semiconductor diode with a wide bandgap semiconductor body. BACKGROUND

[0002] The technological development of new generations of wide-bandgap semiconductor devices, such as SiC power semiconductor devices, aims to improve electrical device characteristics and reduce costs by shrinking device geometries. For examples related to wide-bandgap semiconductor devices, reference is made to the disclosures in US 2019 / 0 081 039 A1 and US 2004 / 0 119 076 A1. Although costs can be reduced by shrinking device geometries, a variety of trade-offs, conflicting objectives, and challenges must be addressed when increasing device functionality per unit area. For example, wide-bandgap semiconductor diodes that offer low forward voltages combined with surge current and avalanche resistance present a challenge.

[0003] Therefore, there is a need for an improved semiconductor diode. SUMMARY

[0004] The invention is defined in the independent patent claims. Further developments are the subject of the dependent patent claims.

[0005] The expert will recognize additional features and advantages upon reading the following detailed description and upon examining the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] 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 examples of semiconductor diodes and, together with the description, serve to explain the principles of the examples. Further examples are described in the following detailed description and the claims. Fig. 1 and Fig. Figure 2 shows partial cross-sectional views to illustrate examples of a semiconductor diode containing a wide bandgap semiconductor body. Fig. Figure 3 is an exemplary equivalent circuit diagram of the semiconductor diodes of the Fig. 1 and Fig. 2. Fig. 4 is a partial cross-sectional view to show exemplary details of the in Fig. 1 illustrated semiconductor diode. Fig. 5 and Fig. Figure 6 shows schematic top views to illustrate examples of semiconductor diodes containing strip-shaped first and second pn junction diode cells. DETAILED DESCRIPTION

[0007] The following detailed description refers to the accompanying drawings, which form part thereof and illustrate specific examples of wide-bandgap semiconductor diodes. It is understood that other examples may be used and structural or logical modifications made without departing from the scope of this disclosure. For example, features illustrated or described for one example may be used in conjunction with other examples to arrive at yet another example. It is intended that this disclosure includes such modifications and variations. The drawings are not to scale and are for illustrative purposes only. Corresponding elements are designated by the same reference numerals in the various drawings unless otherwise stated.

[0008] 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.

[0009] 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 are controllable to 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.

[0010] 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. The same applies to ranges with a boundary value such as "at most" and "at least".

[0011] The terms "on" and "over" should not be interpreted as meaning only "directly on" and "directly over". Rather, if an element is positioned "on" or "over" another element (e.g., a layer is "on" or "over" another layer or "on" or "over" 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" or "over" the substrate).

[0012] An example of a semiconductor diode can include a wide-bandgap semiconductor body having a first surface and a second surface opposite the first. The wide-bandgap semiconductor body can contain a first pn-junction diode with a first p-doped region adjacent to the first surface and a first n-doped region adjacent to both the first and second surfaces. The semiconductor diode can further include a semiconductor element. The semiconductor element can contain a second pn-junction diode with a second p-doped region and a second n-doped region. Furthermore, the semiconductor diode can include a dielectric structure between the wide-bandgap semiconductor body and the semiconductor element. The dielectric structure can electrically isolate the wide-bandgap semiconductor body from the semiconductor element.The semiconductor diode may also include a cathode contact. The bandgap energy of the semiconductor element may be lower than the bandgap energy of the wide-bandgap semiconductor body. The cathode contact may be electrically connected to the first n-doped region on the second surface. The second n-doped region of the second pn-junction diode may be electrically coupled to the first n-doped region of the first pn-junction diode.

[0013] The semiconductor diode can be, for example, part of an integrated circuit or it can be a discrete semiconductor device or module. The semiconductor diode can be a vertical semiconductor device with a load current flowing between the first surface and the second surface opposite the first. The vertical power semiconductor diode can be configured to conduct currents greater than 1 A, 10 A, 30 A, 50 A, 75 A, or even 100 A, and can furthermore be configured to block voltages between load electrodes, e.g., between the cathode and anode of the diode, 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, 10 kV. The reverse voltage can, for example, correspond to a voltage class specified in a datasheet for the semiconductor diode.

[0014] The semiconductor diode can be based on a semiconductor body made of a crystalline, wide-bandgap semiconductor material with a bandgap larger than that of silicon, i.e., greater than 1.12 eV. The wide-bandgap semiconductor material can, for example, have a hexagonal crystal lattice and can be silicon carbide (SiC) or gallium nitride (GaN). For example, the semiconductor material could be 2H-SiC (SiC of the 2H polytype), 6H-SiC, or 15R-SiC. In one example, the semiconductor material could be silicon carbide of the 4H polytype (4H-SiC). The semiconductor body can contain, or consist of, a semiconductor substrate with no, one, or more semiconductor layers (e.g., epitaxially grown layers).

[0015] For example, the first surface can be a front surface or top surface of the wide-bandgap semiconductor body, and the second surface can be a rear surface or back surface of the wide-bandgap semiconductor body. The wide-bandgap semiconductor body can, for example, be mounted on a conductor frame via the second surface. Bond pads can be arranged over the first surface of the wide-bandgap semiconductor body, and bond wires can be bonded to the bond pads.

[0016] The first p-doped region can form a pn junction with the first n-doped region of the first pn junction diode. For example, the first p-doped region can be formed by one or a multitude of p-doped subregions. If, for instance, the first p-doped region is formed by a multitude of p-doped subregions, each of these subregions can have doping profiles that overlap along a vertical direction, e.g., by forming the multitude of p-doped subregions using a multitude of ion implantation processes with different ion implantation energies to achieve different penetration depths of the implanted ions relative to the first surface.

[0017] The first n-doped region can also be formed from a multitude of n-doped subregions. For example, the first n-doped region can be a first n-doped subregion, e.g., an n + -doped cathode contact region, contained, which borders the cathode contact on the second surface. The n +The p-doped cathode contact region can have a doping concentration large enough to form an ohmic contact with the cathode contact on the second surface. The first n-doped region can contain an n-doped drift region as a second n-doped subregion. The first n-doped subregion can be located between the second n-doped subregion and the second surface. The drift region can, for example, border a bottom surface of the first p-doped region. The doping concentration of the drift region can increase or decrease gradually or in steps with increasing distance from the first surface, at least in sections or regions of its vertical extent. According to other examples, the impurity concentration in the drift region can be approximately uniform. For wide-bandgap SiC-based semiconductor diodes, the average impurity concentration in the drift region can be between 5 × 10⁻⁶ 14 cm -3and 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 can depend on voltage blocking requirements, such as a specified voltage class, of the semiconductor diode. When the wide-bandgap semiconductor device is operated in a voltage blocking mode, a space charge region can extend vertically, partially or completely, through the drift region, depending on the blocking voltage applied to the semiconductor diode. The first n-doped region can contain an n-doped channel region as a third n-doped subregion. The second n-doped subregion can be located between the third n-doped subregion and the first n-doped subregion. The n-doped channel region can be laterally bounded by adjacent first p-doped regions. The channel region can be a channel region of a junction or junction field-effect transistor, with the first p-doped region acting as the gate of the JFET.Similar to the first p-doped region, an n-doped channel region can be formed by one or a multitude of n-doped subregions. For example, if the channel region is formed by a multitude of n-doped subregions, these subregions can exhibit doping profiles that overlap along a vertical direction, e.g., by forming the subregions using a multitude of ion implantation processes with different ion implantation energies to achieve different penetration depths of the implanted ions relative to the first surface. The first n-doped region can further be an n. + The -doped channel contact area is included as the fourth n-doped subarea. The n +The n-doped channel contact region can be located between the first surface and the n-doped channel region and can border a contact on the first surface. A doping concentration of n + The -doped channel contact area can be large enough to form an ohmic contact with the contact, e.g., a contact plug, on the first surface, for example to electrically connect the channel area with the second n-doped area of ​​the second pn junction diode.

[0018] The semiconductor diode can have an anode contact above the first surface. The anode contact can, for example, be electrically connected to the first p-doped region of the first pn-junction diode and to the second p-doped region of the second pn-junction diode.

[0019] The anode contact, the dielectric structure, and the contact on the channel region can be elements of a wiring region above the wide-bandgap semiconductor body. The wiring region can comprise one or more than one, e.g., two, three, four, or even more, wiring levels. Each wiring level can be formed by a single or a stack of conductive layers, e.g., metal layer(s) and / or highly doped semiconductor layer(s). The wiring levels can be, for example, lithographically structured. An interlayer dielectric structure can be arranged between stacked wiring levels. A contact plug (contact stop) or contact conductor(s) can be formed in openings of the interlayer dielectric structure to electrically connect parts, e.g., metal conductors or contact regions, of different wiring levels.

[0020] To achieve a desired current-carrying capacity, the wide-bandgap semiconductor diode can be designed using a multitude of parallel-connected wide-bandgap semiconductor diode cells. These parallel-connected wide-bandgap semiconductor diode cells can, for example, be arranged in the form of a strip or a strip segment. Of course, the wide-bandgap semiconductor diode cells can also have any other shape, such as circular, elliptical, polygonal, or octahedral. The wide-bandgap semiconductor diode cells can be arranged in an active region of the wide-bandgap semiconductor body. This active region can be an area where the first p-doped region is located on the first surface and the n +The doped cathode contact area on the second surface is arranged in opposite directions along the vertical direction. In the active region, a load current can enter or exit the wide-bandgap semiconductor body. The semiconductor diode may also include an edge termination region, which may contain a termination structure. In a blocking mode or in a blocking-biased mode of the semiconductor diode, the blocking voltage drops laterally between the active region and a field-free region across the termination structure. The termination structure may have a higher or slightly lower voltage blocking capability than the active region. The termination structure may, for example, include a junction termination extension (JTE) with or without variation of lateral doping (VLD), one or more laterally separated guard rings, or any combination thereof.

[0021] By combining the first and second pn junctions in the semiconductor diode as described above and below, advantages of semiconductor materials with different bandgap energies can be realized. For example, the forward voltage of the semiconductor diode can be determined by the forward voltage of the second pn junction, which has a lower bandgap energy than the first pn junction. The reverse blocking capability of the semiconductor diode can be determined by the voltage blocking capability, e.g., the breakdown voltage, of the first pn junction, which has a higher bandgap energy than the second pn junction. This allows for a low forward voltage while utilizing the voltage blocking capability of the semiconductor material with the larger bandgap.Thus, a semiconductor diode with a low forward voltage can be provided in combination with surge current resistance and avalanche resistance.

[0022] The semiconductor body can be, for example, a SiC semiconductor body, and the semiconductor element can be made of or consist of polycrystalline silicon. The polycrystalline silicon can form part of a wiring region above the first surface of the wide-bandgap semiconductor body.

[0023] The semiconductor diode also contains an anode contact above the first surface. The anode contact is electrically connected to the second p-doped region. The first p-doped region is electrically coupled to the anode contact. Contact plugs and / or through-holes or vias in the wiring area can, for example, facilitate electrical connection.

[0024] The first n-doped region may, for example, contain a channel region bordering the first surface and the first p-doped region. Furthermore, the first n-doped region may contain a drift region bordering the channel region and the first p-doped region. The n-type doping concentration can increase by at least a factor of 5 at a transition from the drift region to the channel region.

[0025] The n-type doping concentration is constant in the channel region, for example. Depending on the manufacturing process of the channel region, it can also contain a multitude of overlapping profiles with doping peaks, where the profiles with doping peaks overlap along a vertical direction. For example, performing a multitude of ion implantation processes with different ion implantation energies can make it possible to adjust the penetration depth of the implanted ions to different depths relative to the first surface.

[0026] The transition from the drift region to the channel region, for example, has a first vertical distance to the first surface. A lower surface of the first p-doped region exhibits a second vertical distance to the first surface. The first vertical distance can, for example, lie in a range of 60% to 90% of the second vertical distance.

[0027] The dielectric structure can, for example, be arranged above the first surface. This dielectric structure could, for instance, be the bottom insulating layer of a wiring area above the first surface. Additionally, or alternatively, the dielectric structure could also, for example, line the sidewalls and bottom of a trench extending from the first surface into the wide-bandgap semiconductor body.

[0028] Furthermore, the semiconductor diode can, for example, include a first contact extending through the dielectric structure. This first contact can be configured to electrically couple the second n-doped region of the second pn-junction diode to the first n-doped region of the first pn-junction diode. The first contact could, for example, be a contact plug of a wiring region above the first surface of the wide-bandgap semiconductor body.

[0029] The semiconductor diode can, for example, have a lower surface coverage of the dielectric structure by the first pn-junction diode and an upper surface coverage of the dielectric structure by the second pn-junction diode. The lower surface coverage of the dielectric structure by the first n-doped region can be smaller than the upper surface coverage of the dielectric structure by the second n-doped region. The lower surface coverage of the dielectric structure can, for example, be determined by the portion of the first n-doped region that defines the channel region of the JFET.

[0030] For example, at least one diode cell can have an upper surface coverage of the dielectric structure by the second p-doped region that can be larger than an upper surface coverage of the dielectric structure by the second n-doped region.

[0031] For example, at least one diode cell can have a lower surface coverage of the dielectric structure by the first p-doped region that is greater than a lower surface coverage of the dielectric structure by the first n-doped region.

[0032] The multitude of diode cells can, for example, comprise a multitude of strip-shaped first pn-junction diodes in the wide-bandgap semiconductor body, extending parallel to each other along a first lateral direction, and a multitude of second strip-shaped pn-junction diodes in the semiconductor element, also extending parallel to each other along the first lateral direction. A multitude of contact openings can be provided in the dielectric structure between the first and second pn-junction diodes to electrically connect the second p-doped region of the second pn-junction diode.

[0033] The multitude of diode cells can, for example, comprise a multitude of strip-shaped first pn-junction diodes in the wide-bandgap semiconductor body, extending parallel to each other along a first lateral direction, and a multitude of strip-shaped second pn-junction diodes in the semiconductor element, extending parallel to each other along a second lateral direction. The second direction can differ from the first.

[0034] For example, a semiconductor diode can be a discrete semiconductor device within a semiconductor body with a wide band gap.

[0035] The examples and features described above and below can be combined.

[0036] The functional and structural details described in the examples above (e.g., materials, dimensions) should apply equally to the examples illustrated in the figures and described below with reference to the manufacturing processes.

[0037] An example of a method for fabricating a semiconductor diode may include forming a first pn-junction diode in a wide-bandgap semiconductor body. The wide-bandgap semiconductor body has a first surface and a second surface opposite the first surface. The first pn-junction diode may contain a first p-doped region adjacent to the first surface and a first n-doped region adjacent to both the first and second surfaces. Furthermore, the method may include forming a semiconductor device. The semiconductor device may contain a second pn-junction diode having a second p-doped region and a second n-doped region. Finally, the method may include forming a dielectric structure between the wide-bandgap semiconductor body and the semiconductor device.The dielectric structure can electrically isolate the wide-bandgap semiconductor body from the semiconductor element. The method can further include the formation of a cathode contact. The bandgap energy of the semiconductor element can be lower than the bandgap energy of the wide-bandgap semiconductor body. The cathode contact can be electrically connected to the first n-doped region on the second surface. The second n-doped region of the second pn-junction diode can be electrically coupled to the first n-doped region of the first pn-junction diode.

[0038] For example, forming the second pn junction diode can involve forming the semiconductor element over the dielectric structure, where the semiconductor element is a polycrystalline silicon layer. Forming the second pn junction diode can further involve introducing n- or p-type dopants into the semiconductor element by at least one unmasked or masked ion implantation process or by in-situ doping during a deposition process. Forming the second pn junction diode can also involve introducing p- or n-type dopants into the semiconductor element by at least one masked ion implantation process.

[0039] For example, forming the first pn junction diode can involve introducing n-type dopants into the semiconductor element using a variety of ion implantation processes with different ion implantation energies.

[0040] For example, the multitude of ion implantation processes with different ion implantation energies can be unmasked or masked ion implantation processes.

[0041] Forming the first pn junction diode can, for example, involve introducing p-type dopants into the semiconductor element using a variety of ion implantation processes with different ion implantation energies.

[0042] Some of the examples mentioned above and below are described in connection with a silicon carbide substrate. Alternatively, a wide-bandgap semiconductor substrate, such as a wide-bandgap wafer, can be processed, which may, for example, have a wide-bandgap semiconductor material other than silicon carbide. The wide-bandgap semiconductor wafer can have a larger bandgap than that of silicon (1.12 eV). For example, the wide-bandgap semiconductor wafer could be a silicon carbide (SiC) wafer, a gallium arsenide (GaAs) wafer, or a gallium nitride (GaN) wafer.

[0043] More details and aspects are provided in connection with the examples described above or below. The processing of a wide-bandgap semiconductor wafer may include one or more optional additional features corresponding to one or more aspects mentioned in connection with the proposed concept or one or more examples described above or below.

[0044] The description and drawings merely illustrate the principles of revelation. Furthermore, all examples cited herein are expressly intended for illustrative purposes only, to aid the reader in understanding the principles of revelation and the concepts contributed by the inventor(s) to further develop the technology. All statements herein that cite principles, aspects, and examples of revelation, as well as specific examples thereof, are intended to include their equivalents.

[0045] It is understood that the disclosure of multiple actions, processes, operations, steps, or functions in the description or claims should not be interpreted as requiring them to occur in a specific sequence, unless explicitly or implicitly otherwise, for example, for technical reasons, such as by the use of terms like "afterwards." For instance, the dielectric structure may be formed before the formation of the second pn junction diode. Therefore, the disclosure of multiple actions or functions does not restrict them to a particular order unless such actions or functions are not interchangeable for technical reasons.Furthermore, in some examples, a single action, function, process, operation, or step may comprise or be subdivided into multiple sub-actions, sub-functions, sub-processes, sub-operations, or sub-steps. Such sub-actions may be contained in or form part of the disclosure of that single action, unless expressly excluded.

[0046] Fig. Figure 1 shows a schematic and exemplary partial cross-sectional view of a semiconductor diode 100.

[0047] The semiconductor diode 100 comprises a wide-bandgap semiconductor body 104, e.g., a SiC semiconductor body, having a first surface 106 and a second surface 107 opposite the first surface 106. A first pn-junction diode 102 is formed within the wide-bandgap semiconductor body 104. The first pn-junction diode 102 comprises a first p-doped region 1021 adjacent to the first surface 106 and a first n-doped region 1022 adjacent to both the first surface 106 and the second surface 107. Furthermore, the semiconductor diode 100 comprises a semiconductor element, the semiconductor element having a second pn-junction diode 112, which has a second p-doped region 1121 and a second n-doped region 1122. The semiconductor diode 100 further contains a dielectric structure 110 between the wide bandgap semiconductor body 104 and the semiconductor element.The dielectric structure 110 electrically isolates the wide-bandgap semiconductor body 104 from the semiconductor element. In the in . Fig. In the illustrated example 1, the semiconductor element is arranged above the wide-bandgap semiconductor body 104. In other examples, the semiconductor element may also be arranged, for example, in a trench extending into the wide-bandgap semiconductor body 104. The semiconductor diode 100 further includes a cathode contact C, e.g., a metal layer or a stack of metal layers, on the second surface 107, e.g., a back side, of the wide-bandgap semiconductor body 104. The bandgap energy of the semiconductor element, which is made of or has polycrystalline silicon, e.g., is lower than the bandgap energy of the wide-bandgap semiconductor body 104, which is made of or has SiC, e.g., SiC. The cathode contact C is electrically connected to the first n-doped region 1022 on the second surface 107. The second n-doped region 1122 of the second pn-junction diode 112 is connected via a contact 114, e.g., a metal layer or a stack of metal layers. B.a contact plug extending through an opening in the dielectric structure 110 electrically coupled to the first n-doped region 1022 of the first pn junction diode 102.

[0048] Fig. Figure 2 shows a schematic and exemplary partial cross-sectional view of a semiconductor diode 100, which is based on Fig. 1 is based on, and further illustrates more exemplary details.

[0049] The semiconductor diode 100 can be formed from a multitude of diode cells. For example, the diode cells can be formed as parallel strips, e.g., strip-shaped first p-doped regions 1021, extending along a direction perpendicular to the plane of the drawing. Fig. 2 extend parallel.

[0050] The first n-doped region 1022 contains a multitude of n-doped subregions that may differ from one another in function and / or doping. For example, the first n-doped region 1022 may contain an n + The -doped cathode contact region 1023 is included as the first n-doped subregion. The n + The n-doped cathode contact region 1023 borders the cathode contact C on the second surface 107 and is sufficiently doped to allow an ohmic contact with the cathode contact C. The first n-doped region 1022 can also be an n -The first n-doped region 1022 contains a doped drift region 1024 as a second n-doped subregion. The vertical extent and doping profile of the drift region 1024 can be adapted to voltage blocking requirements, e.g., a specific voltage class, of the semiconductor diode 100. The drift region 1024 can border a bottom surface of the first p-doped region 1021. The first n-doped region 1022 can further contain an n-doped channel region 1025 as a third n-doped subregion. The n-doped channel region 1025 is laterally bounded by adjacent first p-doped regions 1021. The first n-doped region 1022 can further contain an n + -doped channel contact area 1026 is included as the fourth n-doped subarea. The n + -doped channel contact area 1026 is highly doped to allow an ohmic contact to contact 114.

[0051] An exemplary equivalent circuit diagram of the semiconductor diodes 100 of the Fig. 1 and Fig. 2 is in Fig. Figure 3 shows that, for illustrative purposes, nodes in the equivalent circuit diagram are represented by elements of the cross-sectional view of Fig. 2 linked by the reference symbols of the elements in Fig. 2 can be used.

[0052] The first pn-junction diode 102 is part of a JFET 118. A gate G of the JFET corresponds to the first p-doped region 1021 of the first pn-junction diode 102. A source S of the JFET 118 corresponds to a first end of the channel region 1025, where the n-doped channel region 1025 is connected by the n + The -doped channel contact region 1026 is electrically connected to the contact 114. A drain D of the JFET 118 corresponds to a second end of the channel region 1025, where the n-doped channel region 1025 is connected to the n -The -doped drift region 1024 merges with or transitions into it. The flow of electric charge through the JFET 118 is controlled by constricting the current-carrying n-doped channel region 1025. The current also depends on the electric field between the source S and the drain D. The constriction of the conducting channel is achieved by utilizing the field effect. When the depletion layer spans more than the width of the conducting channel, a pinch-off occurs, stopping the drain-source conduction.

[0053] A cathode of the second pn junction diode 112, i.e. the second n-doped region 1122, is connected via the n + -doped channel contact area 1026 and the contact 114 are electrically connected to the n-doped channel area 1025 of the JFET 118.

[0054] In a forward bias mode of semiconductor diode 100, the forward voltage of semiconductor diode 100 corresponds to the forward voltage of the second pn-junction diode 112, which has a lower bandgap energy than the first pn-junction diode 102. The channel region 1025 of the JFET 118 is switched on in the forward bias mode of semiconductor diode 100.

[0055] In a reverse bias mode, e.g. a reverse bias mode, the semiconductor diode 100 has its first pn junction diode 102 reverse biased and the breakdown voltage between the n - -doped drift region 1024 and the first p-doped region 1021 of the first pn junction diode 102 of the breakdown voltage of the semiconductor diode 100. The channel region 1025 of the JFET 118 is switched off in reverse bias mode of the semiconductor diode 100 at reverse voltages that are close to or lower than the electrical breakdown of the semiconductor diode 100.

[0056] The schematic partial cross-sectional view of Fig. Figure 4 illustrates an exemplary transition from the drift region 1024 to the channel region 1025. A vertical plane of the transition is schematically indicated by a dashed line T. A bottom surface of the channel region 1025 has a first vertical distance d1 to the first surface 106, and a bottom surface 116 of the first p-doped region 1021 has a second vertical distance d2 to the first surface 106. The first vertical distance d1 can, for example, lie in a range of 60% to 90% of the second vertical distance d2.

[0057] As illustrated by the schematic graphic representation depicting a doping concentration c through the channel region along the vertical direction y of a line AA', an n-type doping concentration c increases by at least a factor of 5 at the transition T from the drift subregion 1024, e.g., from a doping concentration c1, to a channel subregion 1025, e.g., to a doping concentration c2 (c2 > 5 × c1). In some other examples, a lower surface of the channel region 1025 may also lie below the lower surface 116 of the first p-doped region 1021.

[0058] The schematic top views of the Fig. 5 and Fig. Figure 6 illustrates exemplary designs of strip-shaped diode cells of the semiconductor diode 100.

[0059] Referring to the schematic top view of Fig. Figure 5 shows that the semiconductor diode 100 contains a plurality of stripe-shaped first pn-junction diodes in the wide-bandgap semiconductor body, extending parallel to each other along a first lateral direction x1. Stripe-shaped channel subregions 1025 and stripe-shaped first p-doped regions 1021 are illustrated for the stripe-shaped first pn-junction diodes. In the simplified top view of Fig. Figure 5 illustrates superimposed strip-shaped second pn-junction diodes, although the strip-shaped second pn-junction diodes are arranged above the first pn-junction diodes. For the multitude of strip-shaped second pn-junction diodes in the semiconductor element, strip-shaped second p-doped regions 1121 and strip-shaped second n-doped regions 1122 are illustrated running parallel to each other along the first lateral direction x1. The first contacts 114 electrically connect the second n-doped region 1122 to the channel subregion 1025. Second contacts 115 electrically connect the p-doped region 1121 to the p-doped first region 1021.

[0060] The expansion directions of the strip-shaped first and second pn junction diodes can also differ from each other. In the schematic top view of Fig. Figure 6 illustrates an example. In the example of Fig.6 Strip-shaped second pn junction diodes, containing the strip-shaped second p-doped regions 1121 and the strip-shaped n-doped regions 1122, extend along a second lateral direction x2, which is perpendicular to the first lateral direction x1, parallel to each other.

[0061] The description and drawings merely illustrate the principles of revelation. Furthermore, all examples cited herein are expressly intended for illustrative purposes only, to aid the reader in understanding the principles of revelation and the concepts contributed by the inventor(s) to further develop the technology. All statements herein that cite principles, aspects, and examples of revelation, as well as specific examples thereof, are intended to include their equivalents.

[0062] The aspects and features mentioned and described along with one or more of the previously detailed examples and figures can also 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.

Claims

[1] Semiconductor diode (100), comprising: a wide bandgap semiconductor body (104) having a first surface (106) and a second surface (107) opposite the first surface (106), wherein the wide bandgap semiconductor body (104) has a first pn junction diode (102) having a first p-doped region (1021) adjacent to the first surface (106) and a first n-doped region (1022) adjacent to the first surface (106) and the second surface (107); a semiconductor element, wherein the semiconductor element has a second pn junction diode (112) having a second p-doped region (1121) and a second n-doped region (1122); a dielectric structure (110) between the wide band gap semiconductor body (104) and the semiconductor element and electrically insulating the wide band gap semiconductor body (104) from the semiconductor element; a cathode contact (C); an anode contact (A) above the first surface (106), wherein the anode contact is electrically connected to the second p-doped region (1121) and the first p-doped region (1021) is electrically coupled to the anode contact (A); where the band gap energy of the semiconductor element is lower than the band gap energy of the wide band gap semiconductor body (104); wherein the cathode contact (C) is electrically connected to the first n-doped region (1022) on the second surface (107); and wherein the second n-doped region (1122) of the second pn junction diode (112) is electrically coupled to the first n-doped region (1022) of the first pn junction diode. [2] Semiconductor diode (100) according to the preceding claim, wherein the semiconductor body (104) is a SiC semiconductor body and the semiconductor element comprises polycrystalline silicon. [3] Semiconductor diode (100) according to one of the preceding claims, wherein the first n-doped region (1022) comprises a channel region (1025) bordering the first surface (106) and the first p-doped region (1021), and a drift region (1024) bordering the channel region and the first p-doped region (1021), wherein an n-type doping concentration increases at a transition from the drift region to the channel region by at least a factor of 5. [4] Semiconductor diode (100) according to the preceding claim, wherein the n-type doping concentration is constant in the drift region (1024). [5] Semiconductor diode (100) according to one of the two preceding claims, wherein the transition from the drift region to the channel region has a first vertical distance (d1) to the first surface (106) and a bottom surface (116) of the first p-doped region (1021) has a second vertical distance (d2) to the first surface (106) and the first vertical distance (d1) is in a range of 60% to 90% of the second vertical distance (d2). [6] Semiconductor diode (100) according to one of the preceding claims, wherein the dielectric structure (110) is arranged over the first surface (106). [7] Semiconductor diode (100) according to the preceding claim, further comprising a first contact (114) extending through the dielectric structure (110), wherein the first contact (114) is configured to electrically couple the second n-doped region (1122) of the second pn-junction diode (112) with the first n-doped region (1022) of the first pn-junction diode (102). [8] Semiconductor diode (100) according to one of the two preceding claims, wherein the semiconductor diode (100) comprises a plurality of diode cells, wherein at least one diode cell of the plurality of diode cells has a lower surface covering of the dielectric structure (110) by the first pn-junction diode (102) and an upper surface covering of the dielectric structure (110) by the second pn-junction diode (112), wherein the lower surface covering of the dielectric structure (110) by the first n-doped region (1022) is less than the upper surface covering of the dielectric structure (110) by the second n-doped region (1122). [9] Semiconductor diode (100) according to the preceding claim, wherein the at least one diode cell has an upper surface coverage of the dielectric structure (110) by the second p-doped region (1121) that is greater than an upper surface coverage of the dielectric structure (110) by the second n-doped region (1122). [10] Semiconductor diode (100) according to one of the two preceding claims, wherein the at least one diode cell has a lower surface coverage of the dielectric structure (110) by the first p-doped region (1021) which is greater than a lower surface coverage of the dielectric structure (110) by the first n-doped region (1022). [11] Semiconductor diode (100) according to one of the three preceding claims, wherein the plurality of diode cells comprises a plurality of strip-shaped first pn junction diodes in the wide bandgap semiconductor body extending parallel to each other along a first lateral direction (x1), and a plurality of strip-shaped second pn junction diodes in the semiconductor element extending parallel to each other along the first lateral direction (x1). [12] Semiconductor diode (100) according to one of claims 8 to 10, wherein the plurality of diode cells comprises a plurality of strip-shaped first pn junction diodes in the wide bandgap semiconductor body extending parallel to each other along a first lateral direction (x1), and a plurality of strip-shaped second pn junction diodes in the semiconductor element extending parallel to each other along a second lateral direction (x2), wherein the second lateral direction (x2) differs from the first lateral direction (x1). [13] Semiconductor diode (100) according to one of the preceding claims, wherein the semiconductor diode (100) is a discrete semiconductor device in the semiconductor body (104) with a wide band gap. [14] Method for manufacturing a semiconductor diode (100), comprising: a formation of a first pn-junction diode (102) in a wide bandgap semiconductor body (104), wherein the wide bandgap semiconductor body (104) has a first surface (106) and a second surface (107) opposite the first surface (106), wherein the first pn-junction diode (102) includes a first p-doped region (1021) adjacent to the first surface (106) and a first n-doped region (1022) adjacent to the first surface (106) and the second surface (107); a forming of a semiconductor element wherein the semiconductor element has a second pn junction diode (112) having a second p-doped region (1121) and a second n-doped region (1122); a formation of a dielectric structure (110) between the wide band gap semiconductor body (104) and the semiconductor element, wherein the dielectric structure (110) electrically insulates the wide band gap semiconductor body (104) from the semiconductor element; a formation of a cathode contact (C); a formation of an anode contact (A) over the first surface (106), wherein the anode contact is electrically connected to the second p-doped region (1121) and the first p-doped region (1021) is electrically coupled to the anode contact (A), wherein the band gap energy of the semiconductor element is lower than the band gap energy of the wide band gap semiconductor body (104), the cathode contact (C) is electrically connected to the first n-doped region (1022) on the second surface (107), and the second n-doped region (1122) of the second pn-junction diode (112) is electrically coupled to the first n-doped region (1022) of the first pn-junction diode (102). [15] Method according to the preceding claim, wherein forming the second pn junction diode (112) comprises: a formation of the semiconductor element over the dielectric structure (110), wherein the semiconductor element is a polycrystalline silicon layer; the introduction of n- or p-type dopants into the semiconductor element by means of at least one unmasked or masked ion implantation process or by means of in-situ doping during a deposition process; and an introduction of p- or n-type dopants into the semiconductor element by means of at least one masked ion implantation process. [16] Method according to the preceding claim, wherein forming the first pn junction diode (102) comprises: an introduction of n-type dopants into the semiconductor element by means of a variety of ion implantation processes with different ion implantation energies. [17] Method according to the preceding claim, wherein the plurality of ion implantation processes with different ion implantation energies are unmasked ion implantation processes. [18] Method according to any one of the four preceding claims, comprising forming the first pn junction diode (102): a process of introducing p-type dopants into the semiconductor element using a variety of ion implantation processes with different ion implantation energies.

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