Wide band gap semiconductor device

Abstract

A wide bandgap semiconductor device (100) is presented. A wide bandgap semiconductor device (100) includes a wide bandgap semiconductor body (102) having a first surface (104) and a second surface (106) opposite the first surface (104) along a vertical direction (y). A gate electrode structure (108) is arranged in the active transistor region (105). The gate electrode structure (108) includes a gate electrode (1081) and a gate dielectric (1082) disposed between the gate electrode (1081) and the wide bandgap semiconductor body (102). A gate interconnect structure (110) is arranged outside the active transistor region (105). The gate interconnect structure (110) includes an interconnect electrode (1101) and an interconnect dielectric (1102) disposed between the interconnect electrode (1101) and the wide bandgap semiconductor body (102). The dielectric constants of the main dielectric components of at least two of i) a portion of the gate interconnect dielectric, ii) a first portion of the gate dielectric, or iii) a second portion of the gate dielectric are different from each other.

Description

Technical Field

[0001] The present disclosure relates to a wide bandgap semiconductor device, and in particular to a wide bandgap semiconductor device including a gate electrode structure and a gate interconnection structure. Background Art

[0002] Technology development for new generations of wide bandgap semiconductor devices (e.g., insulated gate field effect transistors (IGFETs), such as metal oxide semiconductor field effect transistors (MOSFETs) or insulated gate bipolar transistors (IGBTs)) aims to improve electrical device characteristics and reduce costs by shrinking device geometries. Although costs can be reduced by shrinking device geometries, various tradeoffs and challenges must be met when increasing device functionality per unit area. For example, reducing the area ratio on-state resistance R on xA may affect other electrical device characteristics such as, for example, the gate-to-drain capacitance CGD.

[0003] There is a need to improve the electrical characteristics of wide bandgap semiconductor devices. Summary of the invention

[0004] Examples of the present disclosure relate to a wide bandgap semiconductor device, the wide bandgap semiconductor device comprising: a wide bandgap semiconductor body having a first surface and a second surface opposite to the first surface along a vertical direction. The wide bandgap semiconductor device also includes a gate electrode structure arranged in an active transistor region. The gate electrode structure includes a gate electrode and a gate dielectric arranged between the gate electrode and the wide bandgap semiconductor body. The wide bandgap semiconductor device also includes a gate interconnect structure arranged outside the active transistor region. The gate interconnect structure includes an interconnect electrode and an interconnect dielectric arranged between the interconnect electrode and the wide bandgap semiconductor body. The dielectric constants of the main dielectric components of at least two of i) a portion of the interconnect dielectric or ii) a first portion of the gate dielectric or iii) a second portion of the gate dielectric are different from each other.

[0005] Another example of the present disclosure relates to a method for manufacturing a wide bandgap semiconductor device. The method includes: providing a wide bandgap semiconductor body, the wide bandgap semiconductor body having a first surface and a second surface opposite to the first surface along a vertical direction. The method also includes: forming a gate electrode structure in an active transistor region. The gate electrode structure includes a gate electrode and a gate dielectric arranged between the gate electrode and the wide bandgap semiconductor body. The method also includes: forming a gate interconnect structure outside the active transistor region. The gate interconnect structure includes an interconnect electrode and an interconnect dielectric arranged between the interconnect electrode and the wide bandgap semiconductor body. The dielectric constants of the main dielectric components of at least two of i) a portion of the interconnect dielectric or ii) a first portion of the gate dielectric or iii) a second portion of the gate dielectric are different from each other.

[0006] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description, and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings are included to provide a further understanding of the embodiments and are included in and constitute a part of this specification. The accompanying drawings illustrate embodiments of wide bandgap semiconductor devices and together with the description serve to explain the principles of the embodiments. Additional embodiments are described in the following detailed description and claims.

[0008] Figure 1A A partial cross-sectional view schematically and exemplarily showing a configuration example of a wide bandgap semiconductor device.

[0009] Figure 1B A top view schematically and exemplarily shows a configuration example of a wide bandgap semiconductor device.

[0010] Figure 1C and 1D It is along Figure 1B An exemplary cross-sectional view of the intersection lines AA' and BB'.

[0011] Figure 2 A partial cross-sectional view schematically and exemplarily showing another configuration example of a wide bandgap semiconductor device.

[0012] Figures 3A to 3C A top view and a perspective view schematically and exemplarily show another configuration example of a wide bandgap semiconductor device.

[0013] Figure 4 A partial cross-sectional view schematically and exemplarily showing a configuration example of a wide bandgap semiconductor device including a trench gate interconnect structure. DETAILED DESCRIPTION

[0014] In the following detailed description, reference is made to the accompanying drawings, which form a part of the detailed description and in which specific examples of processable semiconductor substrates are illustrated as diagrams. It should be understood that other examples may be used and structural or logical changes may be implemented without departing from the scope of the present disclosure. For example, features illustrated or described for one example can be used on other examples or used in conjunction with other examples to produce another example. It is intended that the present disclosure includes such modifications and variations. Examples are described using specific language, which should not be interpreted as limiting the scope of the appended claims. The accompanying drawings are not drawn to scale and are for illustration purposes only. If not otherwise indicated, corresponding elements are designated by the same reference numerals in different drawings.

[0015] The terms "having", "containing", "including", "comprising" and the like are open ended and indicate the presence of stated structures, elements or features but do not exclude the presence of additional elements or features. The articles "a", "an" and "the" are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

[0016] The term "electrically connected" describes a permanent low resistance connection between electrically connected elements, such as direct contact between the elements involved or a low resistance connection via metal and / or heavily doped semiconductor materials. The term "electrically coupled" includes that one or more intermediate elements adapted for signal and / or power transmission may be connected between the electrically coupled elements, such as elements that may be controlled to temporarily provide a low resistance connection in a first state and a high resistance electrical decoupling in a second state.

[0017] If two elements A and B are combined using "or", if not explicitly or implicitly defined otherwise, this should be understood to disclose all possible combinations, i.e. only A, only B and A and B. Alternative wordings for the same combination are "at least one of A and B" or "A and / or B". The same applies to combinations of more than two elements, if appropriately modified.

[0018] Ranges given for physical dimensions include the boundary values. For example, the range of parameter y from a to b is read as a≤y≤b. The same applies to ranges with a boundary value (e.g., "at most" and "at least").

[0019] The main components of a layer or structure of a chemical compound or alloy are such elements whose atoms form said chemical compound or alloy.For example, silicon (Si) and carbon (C) are the main components of a silicon carbide (SiC) layer.

[0020] The term “on” should not be interpreted as meaning only “directly on.” On the contrary, if an element is disposed “on another element” (for example, a layer is “on another layer” or “on a substrate”), another component (for example, another layer) may be disposed between the two elements (for example, if a layer is “on a substrate,” another layer may be disposed between the layer and the substrate).

[0021] An exemplary wide bandgap semiconductor device includes a wide bandgap semiconductor body having a first surface and a second surface opposite to the first surface along a vertical direction. The wide bandgap semiconductor device includes a gate electrode structure arranged in an active transistor region. The gate electrode structure includes a gate electrode and a gate dielectric arranged between the gate electrode and the wide bandgap semiconductor body. The gate interconnect structure may be arranged outside the active transistor region. The gate interconnect structure includes an interconnect electrode and an interconnect dielectric arranged between the interconnect electrode and the wide bandgap semiconductor body. The dielectric constants of the main dielectric components of at least two of i) a portion of the gate interconnect dielectric or ii) a first portion of the gate dielectric or iii) a second portion of the gate dielectric may be different from each other.

[0022] For example, the wide bandgap semiconductor device may be part of an integrated circuit, or may be a discrete semiconductor device or a semiconductor module. For example, the wide bandgap semiconductor device may be or may include an insulated gate field effect transistor (IGFET), such as a metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT). The wide bandgap semiconductor device may be: a vertical semiconductor device having a load current flowing between a first surface and a second surface opposite to the first surface. The vertical power semiconductor device may be configured to conduct a current exceeding 1A or exceeding 10A or exceeding 30A or exceeding 50A or exceeding 75A or even exceeding 100A, and may also be configured to block a voltage between load electrodes (e.g., between the collector and emitter on an IGBT, or between the drain and source of a MOSFET) in a range of hundreds or up to several thousand volts, such as 400V, 650V, 1.2kV, 1.7kV, 3.3kV, 4.5kV, 5.5kV, 6kV, 6.5kV, 10kV. For example, the blocking voltage may correspond to a voltage level specified in a data sheet of the power semiconductor device.

[0023] A wide bandgap semiconductor device may be based on a semiconductor body from a crystalline wide bandgap semiconductor material having a bandgap that is larger than the bandgap of silicon (i.e., larger than 1.12 eV). As an example, the wide bandgap semiconductor material may have a hexagonal crystal lattice and may be silicon carbide (SiC) or gallium nitride (GaN). For example, the semiconductor material may be 2H-SiC (SiC in 2H polymorph), 6H-SIC, or 15R-SiC. According to an example, the semiconductor material is silicon carbide in 4H polymorph (4H-SiC). The semiconductor body may include or consist of a semiconductor substrate having no semiconductor layer (e.g., a layer grown epitaxially), one or more than one semiconductor layer thereon.

[0024] For example, the first surface may be a front surface or top surface of the semiconductor body, and the second surface may be a back surface or rear surface of the semiconductor body. For example, the semiconductor body may be attached to a lead frame via the second surface. On top of the first surface of the semiconductor body, for example, a bonding pad may be arranged, and a bonding wire may be bonded on the bonding pad.

[0025] For example, the gate electrode structure may be stripe-shaped, and the second lateral direction may be, for example, the longitudinal direction of the stripe-shaped gate electrode structure. The gate electrode structure may also have another layout or geometric shape in a plan view, such as a hexagon, a square, a circle, an ellipse. The gate electrode structure may include one or more conductive materials, such as: a metal, a metal alloy, such as Cu, Au, AlCu, Ag or an alloy thereof; a metal compound, such as TiN; a highly doped semiconductor material, such as highly doped polysilicon. For example, the one or more conductive materials may form a layer stack. For example, the gate electrode structure may be electrically connected to a gate pad via a gate interconnect structure. The gate pad and, for example, a first load electrode pad (e.g., a source pad of a MOSFET or an emitter pad of an IGBT) may be part of a wiring area on a wide bandgap semiconductor body. The wiring area may include one or more than one (e.g., two, three, four or even more) wiring levels. Each wiring level may be formed by a single conductive layer or a stack of conductive layers, such as (one or more) metal layers. For example, the wiring level may be patterned in a lithographic manner. Between the stacked wiring levels, an interlayer dielectric structure may be arranged.(One or more) contact plugs or(one or more) contact lines may be formed in the openings of the interlayer dielectric structure to electrically connect portions (e.g., metal lines or contact areas) of different wiring levels to each other.

[0026] To achieve a desired current-carrying capacity, a wide-bandgap semiconductor device can be designed by a plurality of wide-bandgap semiconductor device elements connected in parallel. The wide-bandgap semiconductor device elements connected in parallel can be, for example, wide-bandgap semiconductor device elements formed in the shape of bars or bar segments. Of course, the wide-bandgap semiconductor device elements can also have any other shape, such as circular, oval, polygonal (such as hexagon or octahedron). The wide-bandgap semiconductor device elements can be arranged in the active transistor region of the semiconductor body. The active transistor region can be a region in which the emitter region (or source region of a MOSFET) of the IGBT and the collector region (or drain region of a MOSFET) of the IGBT are arranged opposite to each other along the vertical direction. In the active transistor region, for example, through a contact plug on the first surface of the wide-bandgap semiconductor body, the load current can enter or leave the semiconductor body of the wide-bandgap semiconductor device. The wide-bandgap semiconductor device can also include an edge termination region, and the edge termination region can include a termination structure. In the blocking mode or in the reverse bias mode of the wide-bandgap semiconductor device, the blocking voltage between the active transistor region and the field-free region drops laterally along the termination structure. Compared with the active region, the termination structure can have a higher or slightly lower voltage blocking ability. For example, the termination structure can include a junction termination extension (JTE) with or without a lateral doping variation (VLD), one or more laterally separated guard rings, or any combination thereof.

[0027] The gate interconnect structure outside the active transistor element region can be arranged laterally between the active transistor element region and the edge termination region. The interconnect electrodes can include one or more conductive materials, such as: metals, metal alloys, such as Cu, Au, AlCu, Ag or their alloys; metal compounds, such as TiN; highly doped semiconductor materials, such as highly doped polysilicon. For example, the one or more conductive materials can form a layer stack. At least a part of the interconnect electrodes can be a so-called gate runner, and the gate runner is merged with the gate pad.

[0028] The main dielectric component of a dielectric structure or a part of a dielectric structure is the dielectric material having the largest volume fraction for the dielectric structure or the part of the dielectric structure. For example, for a dielectric structure having three stacked layers with thicknesses d1, d2, d3 and corresponding dielectric materials m1, m2, m3 (where d1 < d2 < d3), the main dielectric component of the dielectric structure is given by the dielectric material m3.

[0029] When the dielectric constants of the main dielectric components of at least two of i) a part of the gate interconnect dielectric, ii) a first part of the gate dielectric, or iii) a second part of the gate dielectric are different from each other, the following combinations may occur:

[0030] - the dielectric constant of the main dielectric component of a portion of the interconnect dielectric is different from (e.g., smaller than or larger than) the dielectric constant of the first portion of the gate dielectric - for this case, the dielectric constant of the main dielectric component of the second portion of the gate dielectric may have any value, such as equal to the dielectric constant of the main dielectric component of the first portion or equal to the dielectric constant of the main dielectric component of the interconnect dielectric;

[0031] - the dielectric constant of the main dielectric component of a portion of the interconnect dielectric is different from (e.g., smaller than or larger than) the dielectric constant of the main dielectric component of the second portion of the gate dielectric - for this case, the dielectric constant of the main dielectric component of the first portion of the gate dielectric may have any value, such as being equal to the dielectric constant of the main dielectric component of the second portion or being equal to the dielectric constant of the main dielectric component of the interconnect dielectric;

[0032] - the dielectric constant of the main dielectric component of the first portion of the gate dielectric is different from (e.g., smaller than or larger than) the dielectric constant of the main dielectric component of the second portion of the gate dielectric - for this case, the dielectric constant of the main dielectric component of a portion of the interconnect dielectric may have any value, such as equal to the dielectric constant of the main dielectric component of the first portion of the gate dielectric or equal to the dielectric constant of the main dielectric component of the second portion of the gate dielectric;

[0033] -The dielectric constant of the main dielectric component of a portion of the interconnect dielectric is different from (e.g., less than or greater than) the dielectric constant of the main dielectric component of the first portion of the gate dielectric, and is further different from (e.g., less than or greater than) the dielectric constant of the main dielectric component of the second portion of the gate dielectric, and the dielectric constant of the main dielectric component of the first portion of the gate dielectric is different from (e.g., less than or greater than) the dielectric constant of the main dielectric component of the second portion of the gate dielectric.

[0034] When different dielectric constants are used in the main dielectric components of different parts of the dielectric structure of the gate electrode structure / gate interconnect structure, the gate-to-source capacitance CGS can be increased, for example to reduce parasitic turn-on, without adversely affecting the trade-off between Rds and CGD. In addition, the contribution to the gate-to-source capacitance CGS originating from outside the active transistor area (e.g., the gate interconnect area) can also be tuned, for example, via ALD deposition and patterning of a high-k dielectric layer. This allows, for example, to reduce electrical losses in the gate driver circuit.

[0035] For example, the gate electrode structure may be a trench gate electrode structure. The first portion of the gate dielectric may be adjacent to the channel region. The second portion of the gate dielectric may be adjacent to the non-channel region. For example, the sidewalls of the trench gate electrode structure may be non-tapered or slightly tapered. In the case of slightly tapered sidewalls of the trench gate electrode structure, the channel length may be slightly greater than the vertical width of the channel region. The taper angle of the trench gate structure may be caused by process technology (e.g., the aspect ratio of the trench etching process), and may also be used to maximize the charge carrier mobility in the channel region depending on the direction of the channel current flow. Another example of a tapered trench gate structure is a V-shaped trench gate structure. The channel region may be defined as a portion of the main region adjacent to the gate dielectric structure at the sidewall of the trench gate electrode structure. For example, the conductivity of the channel region may be controlled by a potential applied to the gate electrode structure, for example, by a field effect. For example, a positive voltage applied to a trench gate electrode structure in an n-channel MOSFET may, for example, induce an n inversion channel in a portion of a p-doped main region adjacent to the gate dielectric. The body region may be electrically connected via the first surface, for example, by a contact plug and / or a recessed contact on the top surface of the body region, which recessed contact may extend into the wide bandgap semiconductor body and may be electrically connected to the body region via the sidewalls of the recessed contact. For example, a portion of the channel region of the body region may include partial compensation by a dopant of the second conductivity type (e.g., an n-type dopant in the case of a p-doped body region) for adjusting the threshold voltage. For example, partial compensation may be achieved by oblique ion implantation through the sidewalls of the trench.

[0036] For example, the main dielectric component of the first portion of the gate dielectric may be an oxide of silicon.The main dielectric component of the second portion of the gate dielectric may be a high-k dielectric material.

[0037] For example, the first portion of the gate dielectric may include a high-k dielectric material, or the second portion of the gate dielectric may include an oxide of silicon. For example, the high-k material of the first portion of the gate dielectric may be a material residue caused by process technology. For example, the thickness of the layer of the main dielectric component (e.g., SiO2) of the first portion of the gate dielectric may be greater, such as 2 times or greater, or 5 times or greater (e.g., 10 to 100 times) than the thickness of the layer of the high-k dielectric material of the first portion of the gate dielectric. For example, the thickness of the residue layer of the high-k material may be in the range of 1 nm to 10 nm. Similarly, for example, the oxide of silicon of the second portion of the gate dielectric may be a material residue caused by process technology. For example, the thickness of the layer of the main dielectric component (e.g., high-k dielectric material) of the second portion of the gate dielectric may be greater, such as 2 times or greater, or 5 times or greater (e.g., 10 to 100 times) than the thickness of the layer of the oxide of silicon of the second portion of the gate dielectric.

[0038] For example, the main dielectric component of the first portion of the gate dielectric can be a high-k dielectric material. The main dielectric component of the second portion of the gate dielectric can be an oxide of silicon. This can allow for reducing losses caused by channel conductivity. This can also allow for limiting gate charge in the case of non-critical CGD / CGS.

[0039] For example, a first portion of the gate dielectric may be disposed at a first sidewall of the trench gate electrode structure. A second portion of the gate dielectric may be disposed at a second sidewall of the trench gate electrode structure. Along the first lateral direction, the second sidewall is opposite to the first sidewall.

[0040] For example, the first portion of the gate dielectric may be adjacent to a p-doped body region including the channel region. The first portion of the gate dielectric may also be adjacent to an n-doped body region disposed between the p-doped body region and the first surface of the wide bandgap semiconductor body. + The first portion of the gate dielectric may be adjacent to an n-doped current expansion region, which is arranged below the p-doped region, for example, between the p-doped region and the second surface of the wide bandgap semiconductor body. The n-doped current expansion region may have a greater n-type doping concentration than an n-doped drift region arranged below the current expansion region. The n-doped drift region may be arranged between the n-doped current expansion region and the second surface. The second portion of the gate dielectric may be adjacent to a p-doped diode region, which is at least a portion of the non-channel region. For example, the bottom side of the p-doped diode region may have a large vertical distance relative to the first surface compared to the bottom side of the trench gate electrode structure. For example, the p-doped diode region may include: a plurality of p-doped sub-regions, for example, two, three, four, five or more, having a p-type doping concentration distribution overlapping in a vertical direction.

[0041] For example, the p-doped diode region may adjoin a first portion of the bottom side of the trench gate structure.

[0042] For example, a first portion of the gate dielectric may merge into a second portion of the gate dielectric at the bottom side of the trench gate structure.

[0043] For example, the p-doped diode region may adjoin a first portion of the gate dielectric and adjoin a second portion of the gate dielectric at a bottom side of the trench gate structure.

[0044] For example, the wide bandgap semiconductor device may further include a third portion of a gate dielectric. The third portion of the gate dielectric and the second portion of the gate dielectric may have the same material composition, for example, may include a high-k dielectric material as a main dielectric component. The third portion of the gate dielectric may be arranged on the first sidewall of the trench gate electrode structure.

[0045] For example, the third portion of the gate dielectric may be merged into the first portion of the gate dielectric along the second lateral direction. The second lateral direction may be the longitudinal direction of the trench gate electrode structure. In other words, for example, the channel region may be formed by channel sub-regions that are laterally separated from each other along the longitudinal direction of the trench gate structure. For example, between adjacent channel sub-regions, a non-channel region (e.g., a diode region) adjacent to the third portion of the gate dielectric may be arranged.

[0046] For example, the gate interconnect structure may include a trench gate interconnect structure. The trench gate interconnect structure may be incorporated into the gate electrode structure. For example, in some regions of the wide bandgap semiconductor device, the longitudinal directions of the trench gate interconnect structure and the gate electrode structure may be different from each other, for example, perpendicular to each other.

[0047] For example, in a cross-sectional view, the trench gate interconnect structure may only abut the non-channel portion of the wide bandgap semiconductor body. In other words, the trench gate interconnect structure may not be used as a transistor primitive by controlling the conductivity in the channel region via a field effect. For example, the trench interconnect structure may include a portion or segment surrounded by a diode region. In other words, the diode region may abut not only one sidewall, but also the bottom side and the opposite sidewall.

[0048] For example, the primary dielectric component of the first portion of the gate dielectric may be an oxide of silicon, and the primary dielectric component of the portion of the interconnect dielectric may be a high-k dielectric material. This may allow for a further increase in CGS without adversely affecting R on A compromise between xA and CGD.

[0049] For example, high-k dielectric materials may include Al2O3, ZrO2, HfO2, AlN, aluminosilicate AlSiO x , silicon-doped HfO2, lanthanum-doped HfO2, TiO2, Y2O3 or Si3N4, ONO (oxide-nitride-oxide) or at least one of any stacked combination thereof.

[0050] For example, the main dielectric component of the first portion of the gate dielectric may be an oxide of silicon. The main dielectric component of the portion of the interconnect dielectric may be a low-k dielectric material. For example, this may allow for improved resonant switching behavior of wide bandgap semiconductor devices. The low-k dielectric material may include at least one of SiO2, phosphorus or carbon doped SiO2, or porous SiO2.

[0051] For example, the gate electrode structure may be a planar gate electrode structure.

[0052] Details of the structure or function or technical benefits of the features described above for wide bandgap semiconductor devices (such as FETs or IGBTs) are equally applicable to the exemplary methods described herein. Processing a semiconductor body may include one or more optional additional features corresponding to one or more aspects mentioned in conjunction with the proposed concept or one or more examples described above or below.

[0053] The description and drawings illustrate only the principles of the present disclosure. In addition, all examples described herein are primarily intended to be used for illustration purposes only to help readers understand the principles and concepts of the present disclosure contributed by (one or more) inventors to promote the art. All statements describing the principles, aspects and examples of the present disclosure and specific examples of the present disclosure in this article are intended to include their equivalents.

[0054] It should be understood that the disclosure of multiple actions, processes, operations, steps or functions disclosed in the specification or claims cannot be interpreted as falling within the specific order, unless, for example, due to technical reasons, such as by expressions such as "afterwards" explicitly or implicitly otherwise indicated. Therefore, the disclosure of multiple actions or functions will not limit these to a specific order unless such actions or functions are not interchangeable due to technical reasons. In addition, in some examples, a single action, function, process, operation or step may include multiple sub-actions, sub-functions, sub-processes, sub-operations or sub-steps, respectively, or may be decomposed into multiple sub-actions, sub-functions, sub-processes, sub-operations or sub-steps. Unless explicitly excluded, such sub-actions may be included and are part of the disclosure of this single action.

[0055] Examples of the present disclosure relate to a method for manufacturing a wide bandgap semiconductor device. The method includes providing a wide bandgap semiconductor body having a first surface and a second surface opposite to the first surface along a vertical direction. The method also includes forming a gate electrode structure in an active transistor region. The gate electrode structure includes a gate electrode and a gate dielectric arranged between the gate electrode and the wide bandgap semiconductor body. The method also includes forming a gate interconnect structure outside the active transistor region. The gate interconnect structure includes an interconnect electrode and an interconnect dielectric arranged between the interconnect electrode and the wide bandgap semiconductor body. The dielectric constants of the main dielectric components of at least two of i) a portion of the interconnect dielectric or ii) a first portion of the gate dielectric or iii) a second portion of the gate dielectric may be different from each other.

[0056] The examples and features described above and below may be combined.

[0057] Some of the above and following examples are described in conjunction with a silicon carbide substrate. Alternatively, a wide bandgap semiconductor substrate (e.g., a wide bandgap wafer) may be processed, for example, including a wide bandgap semiconductor material other than silicon carbide. The wide bandgap semiconductor wafer may have a bandgap larger than the bandgap of silicon (1.12 eV). For example, the wide bandgap semiconductor wafer may be a silicon carbide (SiC) wafer or a gallium arsenide (GaAs) wafer or a gallium nitride (GaN) wafer.

[0058] Further details and aspects are mentioned in connection with the examples described above or below.Processing 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.

[0059] The description and drawings illustrate only the principles of the present disclosure. In addition, all examples described herein are primarily intended to be used for illustration purposes only to help readers understand the principles and concepts of the present disclosure contributed by (one or more) inventors to promote the art. All statements describing the principles, aspects and examples of the present disclosure and specific examples of the present disclosure in this article are intended to include their equivalents.

[0060] In the following, further examples of field effect transistors FET are explained in conjunction with the accompanying drawings. The functional and structural details described for the above examples will be equally applicable to the exemplary embodiments illustrated in the accompanying drawings and further described below. In the illustrated examples, n-channel FETs are illustrated. However, the examples described in this article can also be applied to p-channel devices, such as p-channel MOSFETs or p-channel devices IGBTs.

[0061] Details of the structure or functions or technical benefits of the features described above are equally applicable to the following examples, and vice versa.

[0062] Figure 1A A partial cross-sectional view schematically and exemplarily showing a configuration example of a wide bandgap semiconductor device 100, and Figure 1B Diagram Figure 1A An exemplary top view of a wide bandgap semiconductor device is shown in FIG.

[0063] Reference Figure 1A , 1B, the wide bandgap semiconductor device 100 includes a wide bandgap semiconductor body 102, such as a SiC semiconductor body. The wide bandgap semiconductor body 102 has a first surface 104 and a second surface 106 opposite to the first surface 104 along a vertical direction y. A stripe-shaped gate electrode structure 108 extends along a second lateral direction x2 and is arranged in the active transistor region 105. A stripe-shaped gate interconnect structure 110 is arranged outside the active transistor region 105 and extends along the first lateral direction x1. The gate electrode structure 108 is merged with the gate interconnect structure 110. The gate interconnect structure 110 can electrically couple the gate electrode of the gate electrode structure 108 to a gate pad (not shown in the figure). Figure 1A , 1B middle).

[0064] Figure 1C , 1D Schematically and exemplarily shown Figure 1B A partial cross-sectional view of a wide bandgap semiconductor device along the intersection lines AA' and BB' shown in the figure.

[0065] Reference Figure 1C , the gate electrode structure 108 includes a gate electrode 1081 and a gate dielectric 1082 arranged between the gate electrode 1081 and the wide bandgap semiconductor body 102. Figure 1D , the gate interconnect structure 110 includes an interconnect electrode 1101 and an interconnect dielectric 1102 disposed between the interconnect electrode 1101 and the wide bandgap semiconductor body 102. The dielectric constants of the main dielectric components of the gate interconnect dielectric 1102 and the gate dielectric are different from each other.

[0066] Figure 2 A partial cross-sectional view schematically and exemplarily shows a configuration example of a wide bandgap semiconductor device 100 in an active transistor region 105. The wide bandgap semiconductor device 100 may be a vertical power semiconductor device, which further includes an edge termination region that at least partially surrounds the active transistor region 105 and a gate interconnect structure 110 (not shown in the figure). Figure 1A middle).

[0067] The gate electrode structure 108 is a trench gate electrode structure and includes a gate electrode 1081 and a gate dielectric 1082 arranged between the gate electrode 1081 and the wide bandgap semiconductor body 102. A first portion 10821 of the gate dielectric 1082 adjoins a channel region 112. The channel region 112 is defined by a portion of a p-doped body region 114 adjoining the gate dielectric 1081 at a first sidewall 1241 of the gate electrode structure 108. For example, the conductivity of the channel region 112 may be controlled by a potential applied to the gate electrode 1082, for example, by a field effect. For example, a positive voltage applied to the gate electrode 1081 may, for example, induce an n-type inversion channel in the channel region 112 adjoining the gate dielectric 1082. The p-doped body region 114 may be electrically connected to the first load electrode L1 via the first surface 104, for example, by a contact plug and / or a recess contact on the top surface of the body region 114, wherein the recess contact may extend into the wide bandgap semiconductor body 102 and may be electrically connected to the body region 114 via the sidewall of the recess contact (not shown). Figure 2 For example, the channel region 112 as part of the body region 114 may include partial compensation by n-type dopants for adjusting the threshold voltage. For example, partial compensation may be achieved by oblique ion implantation through the sidewalls of the trench. The first portion 10821 of the gate dielectric 1082 is also connected to the n-type dopant. + The doped source region 116 is adjacent to the n + The doped source region 116 is arranged between the p-doped body region 114 and the first surface 104. The first portion 10821 of the gate dielectric 1082 further adjoins an n-doped current extension region 118, which is arranged between the p-doped body region 114 and the n-doped drift region 120. The n-doped drift region 120 has a smaller doping concentration than the current extension region 118. Via the second surface 106 of the wide bandgap semiconductor body 102, the n-doped drift region is electrically coupled to the second load electrode L2.

[0068] The second portion 10822 of the gate dielectric 1081 is adjacent to the p-doped diode region 122. The p-doped diode region 122 is a non-channel region, similar to the source region 116 and the current spreading region 118. For example, the main dielectric component of the first portion 10821 of the gate dielectric 1082 can be an oxide of silicon, and the main dielectric component of the second portion 10822 of the gate dielectric 1082 can be a high-k dielectric material. Depending on the process technology, the first portion 10821 of the gate dielectric 1082 can include a high-k dielectric material (e.g., as a process residue), and / or the second portion 10822 of the gate dielectric 1082 can include an oxide of silicon (e.g., as a process residue).

[0069] The first portion 10821 of the gate dielectric 1082 is disposed at the first sidewall 1241 of the trench gate electrode structure 108. The second portion 10822 of the gate dielectric 1082 is disposed at the second sidewall 1242 of the trench gate electrode structure 108. The second sidewall 1242 is opposite to the first sidewall 1241 along the first lateral direction x1.

[0070] The p-doped diode region 122 includes a first sub-region 1221 and a second sub-region 1222. The doping concentration profiles of the first sub-region 1221 and the second sub-region 1222 overlap each other along the vertical direction y. The number of sub-regions may also be different from the example of two sub-regions shown in the figure, for example, it may be three or four or five or even more. The p-doped diode region 122 is also adjacent to the first portion 10821 and the second portion 10822 of the gate dielectric 1082 at the bottom side of the trench gate structure 108. The first portion 10821 of the gate dielectric 1082 merges into the second portion 10822 of the gate dielectric 1082 at the bottom side of the trench gate structure 108. The gate electrode 1081 of the trench gate structure 108 may be electrically isolated from the first load electrode L1 by the intermediate dielectric 126. In some examples, the p-doped diode region 122 is a single region and, therefore, is not defined by a plurality of sub-regions.

[0071] Figure 3A A top view regarding a wide bandgap semiconductor device 100 according to another configuration example is schematically and exemplarily shown. Figure 3B , 3C The perspective diagram shown in the figure is about Figure 3A Different perspective views of a wide bandgap semiconductor device 100 .

[0072] Reference Figure 3A , the source regions 116 (and similarly, the channel regions arranged below the source regions 116) are separated from each other along the second lateral direction x2. The diode region 122 is arranged between adjacent source regions 116 and is adjacent to the third portion 10823 of the gate dielectric 1082. For example, the main dielectric component of the first portion 10821 of the gate dielectric 1082 can be an oxide of silicon, and the main dielectric component of the third portion 10823 of the gate dielectric 1082 can be a high-k dielectric material, similar to the second portion 10822 of the gate dielectric 1082. Depending on the process technology, the third portion 10822 of the gate dielectric 1082 may include an oxide of silicon. In some other examples, the main dielectric component of the first portion 10821 of the gate dielectric 1082 can be equal to the main dielectric component of the second portion 10822 of the gate dielectric 1082, for example, an oxide of silicon, and the main dielectric component of the third portion 10823 of the gate dielectric 1082 can be a high-k dielectric material.

[0073] like Figure 3B , 3C As shown in the schematic perspective view of , the third portion 10823 of the gate dielectric 1082 merges into the first portion 10821 of the gate dielectric 1082 along the second lateral direction x2.

[0074] Figure 4 The schematic cross-sectional view of FIG. 1 illustrates another configuration example of a wide bandgap semiconductor device 100 including a trench gate interconnect structure 110. In the illustrated cross-sectional view, the interconnect dielectric 1102 of the trench gate interconnect structure 110 is adjacent to the diode region 122 which is a non-channel portion of the wide bandgap semiconductor body. For example, the diode region 122 may completely cover the interconnect dielectric 1102 below the first surface 104.

[0075] The aspects and features mentioned and described in conjunction with one or more of the previously described examples and figures may also be combined with one or more of the other examples in order to replace similar features of the other examples, or to otherwise introduce the features into the other examples.

[0076] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that various alternatives and / or equivalent implementations may replace the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptation or variation of the specific embodiments discussed herein. Therefore, it is intended that the present invention be limited only by the claims and their equivalents.

Claims

1. A wide bandgap semiconductor device (100), comprising: A wide bandgap semiconductor body (102) having a first surface (104) and a second surface (106) opposite to the first surface (104) along a vertical direction (y); A gate electrode structure (108) arranged in the active transistor region (105), the gate electrode structure (108) comprising a gate electrode (1081) and a gate dielectric (1082) arranged between the gate electrode (1081) and the wide bandgap semiconductor body (102); a gate interconnect structure (110) arranged outside the active transistor region (105), the gate interconnect structure (110) comprising an interconnect electrode (1101) and an interconnect dielectric (1102) arranged between the interconnect electrode (1101) and the wide bandgap semiconductor body (102); and wherein The dielectric constants of the main dielectric components of at least two of i) a portion of the interconnect dielectric (1102) or ii) a first portion (10821) of the gate dielectric (1082) or iii) a second portion (10822) of the gate dielectric (1082) are different from each other.

2. The wide bandgap semiconductor device (100) of the preceding claim, wherein the gate electrode structure (1081) is a trench gate electrode structure, the first portion (10821) of the gate dielectric (1082) is adjacent to a channel region (112), and the second portion (10822) of the gate dielectric (1082) is adjacent to a non-channel region.

3. The wide bandgap semiconductor device (100) of the preceding claim, wherein a main dielectric component of the first portion (10821) of the gate dielectric (1082) is an oxide of silicon and a main dielectric component of the second portion (10822) of the gate dielectric (1082) is a high-k dielectric material.

4. The wide bandgap semiconductor device (100) of the preceding claim, wherein the first portion (10821) of the gate dielectric (1082) comprises a high-k dielectric material or the second portion (10822) of the gate dielectric (1082) comprises an oxide of silicon.

5. The wide bandgap semiconductor device (100) of claim 2, wherein a major dielectric component of the first portion (10821) of the gate dielectric (1082) is a high-k dielectric material, and a major dielectric component of the second portion (10822) of the gate dielectric (1082) is an oxide of silicon.

6. A wide bandgap semiconductor device (100) as described in any of the three preceding claims, wherein the first portion (10821) of the gate dielectric (1082) is arranged on a first sidewall (1241) of the trench gate electrode structure, and the second portion (10822) of the gate dielectric (1082) is arranged on a second sidewall (1242) of the trench gate electrode structure, the second sidewall (1242) being opposite to the first sidewall (1241) along a first lateral direction (x1).

7. The wide bandgap semiconductor device (100) of the preceding claim, wherein the first portion (10821) of the gate dielectric (1082) is adjacent to a p-doped body region (114) comprising the channel region (112), and the second portion (10822) of the gate dielectric (1082) is adjacent to a p-doped diode region (122), the p-doped diode region (122) being at least a portion of the non-channel region.

8. The wide bandgap semiconductor device (100) of the preceding claim, wherein the p-doped diode region (122) adjoins a first portion of a bottom side of the trench gate electrode structure.

9. The wide bandgap semiconductor device (100) of any one of the two preceding claims, wherein the first portion (10821) of the gate dielectric (1082) merges into the second portion (10822) of the gate dielectric (1082) at the bottom side of the trench gate electrode structure.

10. The wide bandgap semiconductor device (100) of the preceding claim, wherein the p-doped diode region (114) adjoins the first portion (10821) of the gate dielectric (1082) and adjoins the second portion (10822) of the gate dielectric (1082) at the bottom side of the trench gate structure.

11. The wide bandgap semiconductor device (100) according to any one of claims 2 to 9, further comprising: A third portion (10823) of the gate dielectric (1082), wherein the third portion (10823) of the gate dielectric (1082) and the second portion (10822) of the gate dielectric (1082) have the same material composition, and the third portion (10823) of the gate dielectric (1082) is arranged on the first sidewall (1241) of the trench gate electrode structure.

12. The wide bandgap semiconductor device (100) of the preceding claim, wherein the third portion (10823) of the gate dielectric (1082) merges into the first portion (10821) of the gate dielectric (1082) along a second lateral direction (x2).

13. The wide bandgap semiconductor device (100) of any one of the preceding claims, wherein the gate interconnect structure (110) comprises a trench gate interconnect structure.

14. The wide bandgap semiconductor device (100) according to the preceding claim, wherein the trench gate interconnect structure is incorporated into the gate electrode structure (108).

15. The wide bandgap semiconductor device (100) of any one of the two preceding claims, wherein in a cross-sectional view, a trench gate interconnect structure adjoins only a non-channel portion of the wide bandgap semiconductor body (102).

16. The wide bandgap semiconductor device (100) of any one of the preceding claims, wherein a major dielectric component of the first portion of the gate dielectric (1082) is an oxide of silicon and a major dielectric component of the portion of the interconnect dielectric (1102) is a high-k dielectric material.

17. The wide bandgap semiconductor device (100) of any one of claims 3 or 16, wherein the high-k dielectric material comprises Al2O3, ZrO2, HfO2, AlN, aluminosilicate AlSiO x , silicon-doped HfO2, lanthanum-doped HfO2, TiO2, Y2O3 or Si3N4, ONO (oxide-nitride-oxide) or at least one of any stacked combination thereof.

18. The wide bandgap semiconductor device (100) of any one of claims 1 to 14, wherein a major dielectric component of the first portion (10821) of the gate dielectric (1082) is silicon oxide, and a major dielectric component of the portion of the interconnect dielectric (1102) is a low-k dielectric material.

19. The wide bandgap semiconductor device (100) of the preceding claim, wherein the low-k dielectric material comprises at least one of SiO2, phosphorus or carbon doped SiO2 or porous SiO2.

20. The wide bandgap semiconductor device (100) of claim 1, wherein the gate electrode structure (1081) is a planar gate electrode structure.

21. A method of manufacturing a wide bandgap semiconductor device (100), the method comprising: Providing a wide bandgap semiconductor body (102) having a first surface (104) and a second surface (106) opposite to the first surface (104) along a vertical direction (y); forming a gate electrode structure (108) in the active transistor region (105), the gate electrode structure (108) comprising a gate electrode (1081) and a gate dielectric (1082) arranged between the gate electrode (1081) and the wide bandgap semiconductor body (102); A gate interconnect structure (110) is formed outside the active transistor region (105), the gate interconnect structure (110) comprising an interconnect electrode (1101) and an interconnect dielectric (1102) arranged between the interconnect electrode (1101) and the wide bandgap semiconductor body (102); and wherein Dielectric constants of main dielectric components of at least two of i) a portion of the interconnect dielectric or ii) a first portion of the gate dielectric or iii) a second portion of the gate dielectric are different from each other.

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