Ion beam implantation method and semiconductor device

Abstract

Ion beam implantation methods and semiconductor devices. In one example, a substrate is oriented to a target axis, wherein a residual angular misalignment between the target axis and a preselected crystal channel direction in the substrate is within an angular tolerance interval. Dopant ions are implanted into the substrate using an ion beam propagating along the ion beam axis. The dopant ions are implanted at an implantation angle between the ion beam axis and the target axis. The implantation angle is within an implantation angle range. A channel acceptance width is effective for the preselected crystal channel direction. The implantation angle range is greater than 80% of the sum of the channel acceptance width and twice the angular tolerance interval. The implantation angle range is less than 500% of the sum of the channel acceptance width and twice the angular tolerance interval.

Description

[0001] Related applications

[0002] This application claims priority from German Patent Application No. 102019135490.0, filed on December 20, 2019, entitled “ION BEAM IMPLANTATION METHOD AND SEMICONDUCTOR DEVICE,” which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure relates to an ion beam implantation method, a method of manufacturing a semiconductor device, and a semiconductor device including a doped region. Background Art

[0004] If the direction of the dopant ions incident on the surface of a single crystal substrate is sufficiently tilted relative to the main crystal direction in the substrate, the dopant ions primarily experience large-angle scattering, which determines the final average penetration depth of the dopant ions. If the direction of the dopant ions is approximately parallel to the main crystal direction, the dopant ions are highly subject to only small-angle scattering as they pass through the crystal lattice. The dopant ions remain in the same crystal channel ("channeling") and can penetrate deeper into the crystal substrate than in the case of large-angle scattering. Therefore, ion beam implantation using channeling has the potential to form doped regions having end-of-range peaks that are deeper below the main surface of the crystal substrate than the end-of-range peaks of doped regions formed without channeling and by using the same acceleration energy for the dopant ions. In order for the dopant ions to have channeling, the distance between the end-of-range peak and the main surface can strongly depend on the slight deviation between the crystal channel direction and the implantation beam axis.

[0005] There is a need for an improved ion implantation method. Summary of the Invention

[0006] Embodiments of the present disclosure relate to an ion beam implantation method. A substrate is oriented to a target axis, wherein the residual angular misalignment between the target axis and a preselected crystal channel direction in the substrate is within an angular tolerance interval. Dopant ions are implanted into the substrate using an ion beam propagating along the ion beam axis. The dopant ions can be implanted into the substrate through a first substrate main surface of the substrate. The dopant ions are implanted at an implantation angle between the ion beam axis and the target axis. The ion beam can impact the same sub-region of the first substrate main surface for the implantation angle at which the dopant ions are implanted. The implantation angle is within an implantation angle range. The channel acceptance width is valid for the preselected crystal channel direction. The implantation angle range is greater than 80% of the sum of the channel acceptance width and twofold the angular tolerance interval. The implantation angle range is less than 500% of the sum of the channel acceptance width and twofold the angular tolerance interval.

[0007] Embodiments of the present disclosure relate to a method for manufacturing a semiconductor device. A substrate of the semiconductor device is oriented with respect to a target axis, wherein a residual angular misalignment between the target axis and a preselected crystal channel direction in the substrate is within an angular tolerance interval. Dopant ions are implanted into the substrate using an ion beam propagating along an ion beam axis. The dopant ions are implanted at an implantation angle between the ion beam axis and the target axis. The implantation angle is within an implantation angle range. The channel acceptance width is valid for the preselected crystal channel direction. The implantation angle range is greater than 80% of the sum of the channel acceptance width and twice the angular tolerance interval. The implantation angle range is less than 500% of the sum of the channel acceptance width and twice the angular tolerance interval. A doped region includes a first local dopant concentration maximum at a first distance from a first surface of the substrate, a second local dopant concentration maximum at a second distance from the first surface, and a local dopant concentration minimum at a third distance from the first surface, wherein the third distance is between the first and second distances. The first distance is greater than the second distance. The difference between the first and second distances is within a range from 200 nanometers (nm) to 1500 nm. A ratio between the first local dopant concentration maximum and the second local dopant concentration maximum is in a range from 0.5 to 2. A ratio between the sum of the first local dopant concentration maximum and the second local dopant concentration maximum and the local dopant concentration minimum is in a range from 2 to 10.

[0008] Embodiments of the present disclosure relate to a semiconductor device. A semiconductor body includes a first surface and a doped region. The semiconductor body includes silicon carbide. The doped region includes a first local dopant concentration maximum at a first distance from the first surface, a second local dopant concentration maximum at a second distance from the first surface, and a local dopant concentration minimum at a third distance from the first surface, wherein the third distance is between the first and second distances. Starting from the first distance from the first surface, the dopant concentration in the doped region decreases by 90% of the first local dopant concentration maximum within a maximum of 2 micrometers (μm) as the distance from the first surface increases. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate embodiments of ion beam implantation methods and 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.

[0010] Figures 1A-1F Schematic side views and plan views of a substrate are included to illustrate an ion beam implantation method according to an embodiment, including substrate alignment and ion beam implantation at different implantation angles.

[0011] Figures 2A-2B is a schematic diagram illustrating a vertical dopant distribution in a semiconductor device according to an embodiment and illustrating the effect of an ion beam implantation method according to an embodiment.

[0012] Figures 2C-2D is a schematic diagram for illustrating the effect of the ion beam implantation method according to the embodiment.

[0013] Figure 3 A schematic vertical cross-sectional view of a portion of a semiconductor device having one or more doped regions including a vertical dopant concentration profile with a channeling peak according to an embodiment is shown.

[0014] Figures 4A-4C is shown along Figure 3 Schematic diagram of the vertical doping profile along line IV-IV' of the semiconductor device shown in FIG.

[0015] Figure 5 is shown along Figure 3 Schematic diagram of the vertical doping profile along line VV′ of the semiconductor device shown in FIG.

[0016] Figure 6 is a schematic diagram illustrating a vertical dopant profile according to an embodiment including multiple ion implantation processes.

[0017] Figure 7FIG. 1 is a diagram showing an embodiment having multiple ion implantation processes. Figure 3 Schematic diagram of another vertical dopant distribution along line VI-VI in the semiconductor device. DETAILED DESCRIPTION

[0018] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof and in which specific embodiments in which the ion beam implantation method and the semiconductor device can be implemented are shown by way of illustration. It should be understood that other embodiments can be utilized and structural or logical changes can be made without departing from the scope of the present disclosure. For example, features shown or described for one embodiment can be used on other embodiments or used in combination with other embodiments to produce further embodiments. The present disclosure is intended to include such modifications and variations. Examples are described using specific language, which should not be interpreted as limiting the scope of the appended claims. The drawings are not to scale and are for illustrative purposes only. Unless otherwise specified, corresponding elements are represented by the same reference numerals in different drawings.

[0019] The terms "having," "containing," "including," "comprising," and the like are open ended, and the terms indicate the presence of stated structures, elements, or features, but do not preclude 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.

[0020] The term "electrically connected" describes a permanent, low-resistance connection between electrically connected elements, such as direct contact between the associated elements or a low-resistance connection via metal and / or heavily doped semiconductor materials. The term "electrically coupled" includes that one or more intermediate elements suitable for signal and / or power transmission may be connected between electrically coupled elements, for example, elements controllable to temporarily provide a low-resistance connection in a first state and temporarily provide a high-resistance, electrolytic coupling in a second state. An ohmic contact is a non-rectifying electrical junction with a linear or nearly linear current-voltage characteristic.

[0021] The accompanying drawings illustrate relative doping concentrations by indicating "-" or "+" next to the doping type "n" or "p". For example, "n-" means a lower doping concentration than the doping concentration of an "n"-doped region, while an "n+"-doped region has a higher doping concentration than an "n"-doped region. Doping regions with the same relative doping concentration do not necessarily have the same absolute doping concentration. For example, two different "n"-doped regions can have the same or different absolute doping concentrations.

[0022] The range given for a physical dimension is inclusive. For example, the range of parameter y from a to b is expressed as This also applies to ranges with a bounding value like "at most" and "at least".

[0023] The main constituents of a layer or structure from a chemical compound or alloy are the elements whose atoms form the chemical compound or alloy. For example, nickel and silicon are the main constituents of a nickel silicide layer, and copper and aluminum are the main constituents of a copper-aluminum alloy.

[0024] The term “on” is not to be interpreted as meaning “directly on.” Rather, if one element is “on” another element (for example, a layer is “on” another layer or “on a substrate”), additional components (for example, additional layers) may be located between the two elements (for example, if a layer is “on” a substrate, the additional layers may be located between the layer and the substrate).

[0025] With respect to structures and doped regions formed in a substrate, a second region is "below" a first region if the minimum distance between the second region and the first substrate main surface at the substrate front side is greater than the maximum distance between the first region and the first substrate main surface. A second region is "directly below" a first region when the vertical projections of the first and second regions into the first substrate main surface overlap. A vertical projection is a projection normal to the first substrate main surface.

[0026] Regions and / or structures can be laterally separated from one another in the same horizontal layer. Laterally separated regions and / or structures can also be vertically separated (i.e., located in different horizontal layers). In the latter case, the orthogonal projections of the separated regions and / or structures onto the horizontal projection plane are laterally separated. Regions and / or structures in different horizontal layers can laterally overlap, wherein the orthogonal projections of the related regions and / or structures onto the horizontal projection plane laterally overlap.

[0027] The term “power semiconductor device” refers to a semiconductor device having a high voltage blocking capability of at least 30 V, such as 100 volts (V), 600 V, 3.3 kilovolts (kV) or more, and having a nominal on-state current or forward current of at least 1 ampere (A), such as 10 A or more.

[0028] Power semiconductor switches include IGBTs (insulated gate bipolar transistors), JFETs (junction field effect transistors), and IGFETs (insulated gate field effect transistors). IGFETs are voltage-controlled devices that include MOSFETs (metal oxide semiconductor FETs) and other FETs with gate electrodes based on doped semiconductor materials and / or with gate dielectrics that are not, or not exclusively, oxide-based.

[0029] The term "semiconductor body" as used herein may refer to a substrate, a portion of a substrate, or other semiconductor structure.

[0030] According to an embodiment, an ion beam implantation method may include orienting a substrate to a target axis, wherein a residual angular misalignment between the target axis and a preselected crystal channel direction in the substrate may be within an angular tolerance interval.

[0031] The substrate may be a wafer-sized slice (e.g., a wafer) comprising a single crystal material, or may comprise a layer of single crystal material formed on an amorphous base substrate. The slice or layer of single crystal material may comprise exclusively single crystal material, or may comprise structures of other materials, such as conductive structures and / or insulating structures, in addition to single crystal material.

[0032] The single crystal material may be a ceramic, such as α-Al2O3 (sapphire), or a semiconductor material. For example, the semiconductor material may be any Group IV element semiconductor, such as silicon (Si) or germanium (Ge), any Group IV compound semiconductor, such as silicon carbide (SiC) or silicon germanium (SiGe), or any Group III / V compound semiconductor, such as gallium arsenide (GaAs) or gallium nitride (GaN).

[0033] For example, the single crystal material may be 15R-SiC (silicon carbide of the 15R polytype), or silicon carbide having a hexagonal polytype, such as 2H-SiC, 4H-SiC, or 6H-SiC. In addition to the main components of silicon and carbon, the single crystal material may include dopant atoms such as nitrogen (N), phosphorus (P), beryllium (Be), boron (B), aluminum (Al), and / or gallium (Ga). The single crystal material may also include additional impurities caused by process imperfections and / or precursor impurities, such as hydrogen, fluorine, and / or oxygen.

[0034] The substrate may have two substantially parallel main surfaces of identical shape and size, and a lateral outer surface connecting the edges of the two substrate main surfaces. The substrate may extend laterally in a plane spanned by the lateral direction. Thus, the substrate may have a surface extending along two lateral directions (hereinafter also referred to as horizontal directions). The substrate may have a thickness along a vertical direction perpendicular to the lateral directions. The first substrate main surface at the front side and the second substrate main surface at the back side may have a polygonal shape (e.g., rectangular or hexagonal) with or without rounded edges, a circular shape, a notch, or a circular shape with a flat surface along the circumference.

[0035] Any crystal direction along which the channeling effect outweighs the effect of large angle scattering may be denoted as a crystal channel direction. For example, for a hexagonal crystal lattice, the crystal channel direction may be a principal crystal direction, such as, for example, <0001> lattice direction ("c-axis"), an <11-20> lattice direction ("a-axis"), a <1-100> lattice direction ("m-axis"), or an <11-23> lattice direction. For a cubic lattice, the crystal channel direction may be a principal crystal direction, such as, for example, <001> Lattice direction, <001> Lattice direction, <111> Lattice direction, <112> lattice direction, the direction parallel to the (111) plane, and the direction parallel to the (022) plane.

[0036] The user may preselect one of the available crystal channel directions as the crystal channel direction that defines the position of the end-of-range peak of the channeling dopant ions under predetermined process conditions.

[0037] The target axis may be the same as the idle ion beam axis. The idle ion beam axis may be a default ion beam axis along which the ion beam propagates in the idle mode. In the idle mode, the ion beam implanter uses a constant implantation angle.

[0038] Residual angular misalignment (total angle of incidence variation) between the target axis and the preselected crystal channel direction may result from process imperfections in the process of orienting the substrate to the target axis.

[0039] Process imperfections may arise from mechanical limitations of the ion beam implantation apparatus. For example, the ion beam implantation apparatus may include a substrate tilt mechanism. The substrate tilt mechanism can rotate the substrate about a horizontal rotation axis parallel to the first substrate major surface. Alternatively, the substrate tilt mechanism can rotate the substrate sequentially about two differently oriented orthogonal horizontal rotation axes, for example, parallel to the first substrate major surface. The substrate tilt mechanism can align the preselected crystal channel direction to the target axis with only limited accuracy.

[0040] Alternatively or in addition, the ion beam implantation apparatus may include an ion beam projection apparatus having a steerable ion beam axis. The ion beam projection apparatus may deflect the ion beam axis in an incident beam plane that is tilted toward the first substrate main surface. Alternatively, the ion beam projection apparatus may be adapted to deflect the ion beam axis in two differently oriented, e.g., orthogonal, incident beam planes. The ion beam projection apparatus may align the ion beam axis with the preselected channel direction with only limited accuracy.

[0041] Alternatively or in addition, the ion beam implantation apparatus may include a substrate rotation mechanism. The substrate rotation mechanism can rotate the substrate about a vertical axis passing through the transverse center of the first substrate major surface. The substrate rotation mechanism can align the preselected crystal channel direction with an incident plane spanned by the surface normal and the ion beam axis with only limited accuracy.

[0042] Typically, the total device angular tolerance window including tolerances for the substrate tilt mechanism and for the ion beam projection device may be in the range of from -0.5 degrees to +0.5 degrees, for example from -0.2 degrees to +0.2 degrees or from -0.1 degrees to +0.1 degrees. Alternatively and / or in addition, the tolerances for the substrate tilt mechanism and / or the ion beam projection device may be outside the range of from -0.5 degrees to +0.5 degrees.

[0043] Additionally or alternatively, the process imperfection may involve an off-axis cut that defines the orientation of the first substrate main surface relative to a main crystal direction including a preselected crystal channel direction. Typically, the angular tolerance window for the off-axis cut may be in the range of -0.5 degrees to +0.5 degrees, for example, in the range of -0.2 degrees to +0.2 degrees for silicon carbide (SiC) and silicon (Si), or in the range of -0.1 degrees to +0.1 degrees for silicon (Si). Alternatively and / or additionally, the angular tolerance window for the off-axis cut may be outside the range of -0.5 degrees to +0.5 degrees.

[0044] Additionally or alternatively, process imperfections may involve an angular deviation between an orientation indicator of a primary lattice plane and the actual orientation of the same primary lattice plane. For example, the orientation of a notch or a flat surface at the outer circumference of the substrate may indicate the orientation of a predefined primary lattice plane. Process imperfections may result in an angular deviation between the actual orientation of a predefined primary lattice plane and the flat surface, or between the actual orientation of a predefined primary lattice plane and the direction indicated by the notch.

[0045] The total angular tolerance interval can be the sum of the total device angular tolerance window and the angular tolerance windows for off-axis cutting and orientation indicators. For example, the angular tolerance interval can be in the range of from -1 degree to +1 degree, such as from -0.4 degrees to +0.4 degrees or from -0.2 degrees to +0.2 degrees.

[0046] The residual angular misalignment can be described by a first angular component and a second angular component, wherein the first angular component and the second angular component are defined in orthogonal directions. For example, the first angular component describes the angular deviation of a preselected crystal channel direction from a target axis in a vertical plane orthogonal to the horizontal rotation axis of the substrate tilt mechanism. The second angular component can describe the angular deviation of a vertical projection of the preselected crystal channel direction onto the first substrate main surface from a vertical projection of the target axis onto the first substrate main surface.

[0047] Dopant ions can be implanted into a substrate using a directed ion beam. The ion beam propagates along the beam axis. In a collimated ion beam, the dopant ions move parallel to the beam axis. In a diverging ion beam, the beam axis is the axis of symmetry of the ion beam. The dopant ions can be implanted into the substrate through the first major surface of the substrate.

[0048] The dopant ions can be implanted at different implantation angles. The corresponding implantation angle is the angle between the ion beam axis and the target axis.

[0049] For example, the substrate tilt mechanism can tilt the substrate at different tilt angles about a horizontal rotation axis parallel to the first major surface of the substrate. Alternatively, the ion beam projection device can deflect the ion beam axis at different deflection angles in the incident plane. Alternatively, the substrate rotation mechanism can rotate the substrate at different twist angles.

[0050] During the ion implantation process, the implantation angle can be changed continuously. Alternatively, the implantation angle can be changed in discrete motions.

[0051] The injection angle may be within a range of injection angles. The range of injection angles may be symmetrical about the target axis. Alternatively, the range of injection angles may be slightly asymmetrical about the target axis. For example, a first sub-range of injection angles on a first side of the target axis may cover 40% to 50% of the full range of injection angles.

[0052] Each crystal channel direction can have a specific channel acceptance width. The channel acceptance width (or channel effect probability distribution) is a measure of the angular dependence of the channel effect efficiency. The angularly dependent channel effect efficiency can be symmetric with respect to the crystal channel direction and can have a global maximum at the corresponding crystal channel direction. The channel acceptance width can be defined by a FWHM (full width half maximum) value. Typically, the angularly dependent channel effect efficiency can be approximated by a Gaussian angular distribution. Alternatively and / or in addition, the angularly dependent channel effect efficiency can be determined and / or approximated by using one or more other techniques. For example, the channel acceptance width can be a function of ion type, ion energy and ion dose.

[0053] The implantation angle range may be greater than 80% of the sum of the channel acceptance width in the preselected crystal channel direction and twice the angular tolerance interval, for example, greater than 90% or greater than 100%. In addition, the implantation angle range may be less than 500% of the sum of the channel acceptance width in the preselected crystal channel direction and twice the angular tolerance interval, for example, less than 400% or less than 250%. The implantation angle range may be less than five times the sum of the channel acceptance width in the preselected crystal channel direction and twice the angular tolerance interval, for example, less than four times or less than 2.5 times. When these prerequisites are met, the channeling effect may be effective for the same amount of ion dopant or for at least approximately the same amount of ion dopant, regardless of the actual angular misalignment between the target axis and the preselected crystal channel direction. For example, for a given channeling effect acceptance width, the implantation angle range may be selected to be as small as possible to achieve a high channeling effect portion (for example, a channeling effect portion that meets a threshold channeling effect efficiency with a process stability that meets a threshold process stability) with sufficient process stability.

[0054] The implant sweep may include a full pass of the implant angle range. For example, the implant sweep may include tilting the substrate about a horizontal rotation axis parallel to the first substrate main surface through the implant angle range. According to another example, the implant sweep may include twisting the substrate about a vertical rotation axis through the rotation angle range. The rotation angle range may be derived from the implant angle range and may depend on the characteristics of the preselected crystal channel direction.

[0055] The act of implanting the dopant ions into the substrate can include one or more implantation sweeps along a single rotational axis. For example, implanting the dopant ions can include one or more implantation sweeps orthogonal to a first horizontal rotational axis of the substrate tilt mechanism. Alternatively, implanting the dopant ions can include one or more rotational sweeps ("twists") or rotations about a vertical axis.

[0056] Alternatively, implanting the dopant ions may include continuous implantation sweeps along two or more rotational axes. For example, implanting the dopant ions may include at least one implantation sweep orthogonal to a first horizontal rotational axis of the substrate tilt mechanism and at least one implantation sweep orthogonal to a second horizontal rotational axis of the substrate tilt mechanism, wherein the second horizontal axis may be perpendicular to the first horizontal axis. Alternatively, implanting the dopant ions may include at least one implantation sweep orthogonal to the horizontal rotational axis of the substrate tilt mechanism and at least one rotational sweep about a vertical rotational axis.

[0057] In this way, the amount of "channeling" dopant ions can be decoupled (and / or decoupled to a large extent) from the exact value of the angular misalignment between the crystal channel direction and the target axis. Thus, regardless of the actual angular misalignment between the target axis and the preselected crystal channel direction, the distance between the peak at the end of the range of the channeling dopant ions ("channeling peak") and the first substrate major surface is the same or nearly the same. Furthermore, the maximum dopant concentration at the channeling peak can be independent of (and / or to a large extent independent of) the actual angular misalignment between the target axis and the preselected crystal channel direction.

[0058] The method may facilitate practical and productive use of channeling dopant ions for various applications using substrates with typical angular deviations from off-axis cuts and / or using ion beam implantation apparatus with substrate tilt mechanisms having typical orientation accuracy.

[0059] Channeling dopant ions can promote the formation of a dopant region having a local dopant maximum at a comparatively large vertical distance from the main surface of the substrate and / or can contribute to reducing the maximum implantation energy. For example, the vertical distance to the main surface of the substrate can be greater (e.g., as a result of the channeling dopant ions) than the vertical distance between the main surface of the substrate and the dopant region (having a local dopant maximum) formed in the absence of the channeling dopant ions. Ion implantation at lower implantation energy can reduce negative side effects, such as damage to existing structures, damage to the semiconductor lattice, and / or can facilitate the use of thinner implantation masks.

[0060] Furthermore, the non-channeling dopant ions are distributed in the substrate between the first substrate major surface and the channeling peak. The distribution of the non-channeling dopant ions can be tuned by process parameters, such as the implantation angle range, the distribution of implantation angles within the implantation angle range, the implantation energy, the implantation temperature, and / or the implantation dose for each sub-implantation. For example, the process parameters can be selected such that the distribution of the non-channeling dopant ions includes an additional end-of-range peak ("main peak") between the first substrate major surface and the channeling peak.

[0061] The main peak and the channeling peak can be defined so that the vertical dopant concentration profile of the implanted dopant ions approximates a desired profile, such as a broad plateau-like dopant profile with a less pronounced minimum or a dopant profile with two distinct peaks. Thus, the method can facilitate the formation of a variety of vertical dopant profiles using a single implantation process. In particular, the ratio between the dopant concentration at the channeling peak and the main peak can be adjusted by selecting an appropriate angular magnitude for the implantation angle range and / or by selecting an appropriate implantation angle, i.e., an appropriate distribution of implantation angles within the implantation angle range.

[0062] According to an embodiment, during the implantation of dopant ions, the implantation angle (and / or ion beam) may be continuously swept through the implantation angle range at least once. In this context, "continuously" may mean that two consecutive angles (e.g., two directly consecutive angles) may differ by at most 1° (or at most 0.1°) and / or at most 10% (or at most 1%) of at least one of the consecutive angles. For example, during a single implantation process about a rotation axis, the implantation beam (e.g., ion beam) may be swept across the entire implantation angle range once, twice, or even more frequently. During each angular sweep, the implantation beam may impinge on the same or nearly the same sub-region of the first substrate main surface. For example, the first substrate main surface may be completely within the implantation beam cone. The implantation beam cone may consist of a wide single beam or of a fast 2D scanning spot beam. For example, the fast 2D scan may be an electrostatic or magnetic scan in the X and Y directions with a frequency in the range from a few Hz to a few kHz.

[0063] During each sweep, the average dopant ion current in the ion beam can be constant or nearly constant. The ratio between the dopant concentration at the peak channeling effect and the main peak can be adjusted by the angular velocity of the angular sweep. Changing the angular velocity as a function of the implantation angle can further promote the variation of the vertical dopant profile without changing the dopant ion current in the ion beam.

[0064] Continuous scanning can be achieved by continuous rotation around the horizontal rotation axis of the substrate tilt mechanism, by continuously reducing or increasing the deflection of the ion beam axis in the beam plane of an ion beam projection device with a steerable ion beam axis, or by continuous rotation around the vertical rotation axis of the substrate rotation mechanism.

[0065] According to an embodiment, implanting dopant ions may comprise nmax implantation sub-processes at nmax different implantation angles between the ion beam axis and the target axis. nmax may be at least 2, for example at least 7, at least 15 or at least 16. Each implantation sub-process may be effective for a constant implantation angle. The method may be performed at an ion beam implantation apparatus that provides the functionality of changing the implantation angle between consecutive ion implantation sub-processes ("shots"). The ion implantation sub-processes may follow one another directly without an intermediate calibration and / or tuning process. Alternatively, a retuning and / or recalibration process may be performed between at least two consecutive ion implantation sub-processes, between some of the ion implantation sub-processes or between each pair of consecutive ion implantation sub-processes.

[0066] Different implantation angles can be achieved by gradually changing the tilt angle about the horizontal rotation axis of the substrate tilt mechanism, by gradually decreasing or increasing the deflection angle of the ion beam axis in an ion beam projection device having a steerable ion beam axis, or by gradually rotating the substrate rotation mechanism about the vertical rotation axis. For a rotational sweep, the range of the rotational sweep about the vertical rotation axis can be a function of the implantation angle range and can depend on a preselected crystal channel orientation and / or substrate material.

[0067] For each implantation sub-process, the total dopant ion current in the ion beam can be constant or approximately constant. In other words, each implantation sub-process can approximately implant the same amount of dopant ions, i.e., the same dopant ion dose. If the ion beam implantation apparatus allows nmax implantation sub-processes within the same recipe and there is no further tuning and / or calibration of the ion beam, it is possible that the division of the implantation process into nmax implantation sub-processes has no effect or only a negligible effect on the total process time (for example, the division of the implantation process into nmax implantation sub-processes may not cause the total process time to change or may cause the total process time to change by an amount less than a threshold amount of time).

[0068] Alternatively, at least one implantation sub-process may implant an amount of dopant ions that is different from an amount of dopant ions implanted by at least one other implantation sub-process.

[0069] The acceleration voltage used to accelerate the dopant ions may be the same or nearly the same for each implantation sub-process. Alternatively, at least one implantation sub-process may use an acceleration voltage that is different from the acceleration voltage used in at least one other implantation sub-process.

[0070] According to an embodiment, the nmax injection angles of a multi-act injection process including a plurality of injection sub-processes may be equally spaced. In other words, each injection angle may have the same angular distance to its adjacent injection angle. In this way, it is possible that the position of the channeling peak and the dopant concentration at the channeling peak are highly independent of the actual residual misalignment angle between the target axis and the preselected crystal channel direction. According to other embodiments, the angular distance between adjacent injection angles may be a function of the distance to the corresponding injection angle of the angular center of the injection angle range. For example, the angular distance between adjacent injection angles may decrease or increase monotonically or strictly monotonically. Other distributions of injection angles may also be possible. For example, the nmax injection angles may be derived from the equiangular distances (twist angles) between adjacent injection positions of the substrate rotation mechanism.

[0071] According to an embodiment, the nmax implantation sub-processes may include implantation sub-process pairs, wherein the implantation angle of each implantation sub-process pair is symmetrical with respect to the angular center of the implantation angle range. In this way, it may be possible to make the resulting doping profile independent (and / or highly independent) of the angular direction of the angular deviation of the off-axis cut and / or independent of the angular direction of the tilt error angle of the substrate tilt mechanism.

[0072] According to an embodiment, at least one of the implantation angles may be 0 degrees or deviate from 0 degrees by at most 0.3 degrees. In other words, one implantation sub-process may be performed with the ion beam axis parallel to the target axis, i.e., along the idle ion beam axis. The target axis may be as close as possible to the selected channel direction.

[0073] For example, in the case of a silicon carbide substrate with a 4 degree off-axis cut, at an implantation angle of 0 degrees between the target axis and the ion beam axis, the ion beam axis can have a tilt angle of about 4 degrees relative to the surface normal, as long as <0001> The lattice direction is the selected channel direction. In the case where the <11-23> lattice direction is the selected channel direction, for an implantation angle of 0 degrees, the ion beam axis may have a tilt angle of 21 degrees or 13 degrees relative to the surface normal.

[0074] In the case of a single-crystal silicon substrate having a (001) lattice plane parallel to the main surface, at an implantation angle of 0 degrees between the target axis and the ion beam axis, <001> In the case where the lattice direction is the selected channel direction, the ion beam axis is almost perpendicular to the first surface.

[0075] According to an embodiment, adjacent implantation angles may differ by at most 0.5 degrees, for example, at most 0.2 degrees or at most 0.1 degrees. For example, starting from a first boundary angle of the implantation angle range, the implantation angles of the implantation sub-processes may be changed in regular angular steps of 0.5 degrees until a second boundary angle of the implantation angle range is reached. According to another example, the angular step size may be 0.2 degrees or 0.1 degrees.

[0076] For a rotational sweep about a vertical rotation axis, the angular distance between adjacent implant locations can depend on the total rotational sweep range, which in turn can depend on the preselected crystal channel direction. For example, the average angular distance between adjacent implant locations can be in the range of 3% to 10% of the rotational sweep range. According to another example, the angular distance between adjacent implant locations can be in the range of 0.1 degrees to 1 degree, such as 0.1 degrees to 0.5 degrees.

[0077] For example, by combining fifteen implant sub-processes, it is possible that the location of the channeling peak and the dopant concentration at the channeling peak can be highly decoupled from the actual angular misalignment between the target axis and the preselected crystal channel direction for a channel acceptance width of about 0.6 degrees or less. For example, a channel acceptance width of about 0.6 degrees can be a reasonable approximation for the c-axis of the hexagonal silicon carbide lattice.

[0078] According to an embodiment, the implantation angle range is at most 6 degrees, for example at most 5 degrees or at most 4 degrees. According to other examples, the implantation angle range can be at most 3 degrees, 2 degrees, 1 degree, or 0.2 degrees. For example, the implantation angle range can be a channel acceptance width that increases by 0.8 degrees. 0.8 degrees can represent a typical upper limit for the sum of the angular tolerance window for the substrate tilt mechanism and the off-axis cut. A relatively small, but sufficiently large, implantation angle range (e.g., an implantation angle range that is less than the first threshold implantation angle range and greater than the second threshold implantation angle range) can be sufficient to define the dopant concentration around the channeling peak with little additional effort.

[0079] According to an embodiment, before implantation, an angular deviation between a lateral main crystal direction in the substrate and a lateral target direction may be determined. Alternatively and / or additionally, the angular deviation may be determined during or after implantation.

[0080] The ion beam axis and the target axis span the implantation angle plane. The lateral target direction can have an arbitrary but predefined orientation relative to the implantation angle plane. For example, the implantation angle plane can run perpendicular to or parallel to the lateral target direction. For substrates having a hexagonal lattice and off-axis cuts, the principal lateral crystallographic direction can depend on the direction of the off-axis cut. For example, the principal lateral crystallographic direction can be an <11-20> lattice direction or a <1-700> lattice direction.

[0081] The angular deviation can be determined by a measurement unit, for example, by optically detecting the orientation of ribs on the main surface of the first substrate. For example, the ribs may result from off-axis cutting and may extend perpendicular to or parallel to the transverse main crystal direction. Alternatively, data indicating the angular deviation relative to the notch or relative to the flatness at the outer circumference of the substrate can be received and analyzed.

[0082] Then, further prior to implanting the dopant ions, the transverse major crystal axis can be aligned with the transverse target direction. Alternatively and / or additionally, the transverse major crystal axis can be aligned with the transverse target direction during or after implanting the dopant ions. The alignment process can include rotational movement ("twisting") of the substrate. The residual rotational misalignment between the transverse target direction and the transverse major crystal axis can be at most 0.5 degrees, e.g., at most 0.2 degrees or at most 0.1 degrees.

[0083] Thus, for a complete implantation process, the implantation angle plane can have a predefined orientation relative to the crystal lattice. Implantation conditions for different substrates of the same type can be more closely aligned with each other. An additional alignment process can improve the reproducibility of implantation results across multiple substrates of the same type. Rotational alignment can be performed after or before beam tilt alignment using a substrate tilt mechanism and / or an ion beam projection device having a steerable ion beam axis as described above.

[0084] Rotational alignment can replace rotational sweeping. Alternatively, rotational alignment can be combined with rotational sweeping. For example, the angular position achieved by rotational alignment can be used as the angular center of at least one rotational sweep. The sweep range can be symmetrical or asymmetrical about the angular center.

[0085] For example, with an angular center at 0 degrees, for a rotational sweep about a vertical rotation axis, the total rotational sweep range of the injection position can be, for example, in the range from -14 degrees to +14 degrees, from -4.9 degrees to +4.9 degrees, from -2.1 degrees to +2.1 degrees, from -1.4 degrees to +1.4 degrees, or from -0.7 degrees to +0.7 degrees.

[0086] According to an embodiment, a semiconductor device may include a semiconductor body having a first surface and having a doped region.

[0087] The semiconductor device may be a power semiconductor device, such as a power semiconductor switch or a power semiconductor diode. The semiconductor body may include a semiconductor material. The semiconductor material may include silicon carbide, such as silicon carbide having a hexagonal lattice. The second surface of the semiconductor body may be parallel to, or at least nearly parallel to, the first surface. The first and second surfaces may extend in a lateral direction and may have the same shape and size.

[0088] The doped region may include a first local dopant concentration maximum at a first distance from the first surface, a second local dopant concentration maximum at a second distance from the first surface, and a local dopant concentration minimum between the first distance and the second distance. For example, the doped region may include a local dopant concentration minimum at a third distance from the first surface. The third distance may be between the first distance and the second distance. The first distance may be greater than the second distance.

[0089] One of the first and second local dopant concentration maxima may be a global local dopant concentration maximum. Alternatively, neither of the first and second local dopant concentration maxima is a global local dopant concentration maximum.

[0090] The difference between the first distance and the second distance may be in the range of 200 nanometers (nm) to 1500 nm, for example in the range of 300 nm to 1000 nm. According to an embodiment, the difference between the first distance and the second distance may be in the range of 400 nm to 550 nm. The ratio between the first local dopant concentration maximum and the second local dopant concentration maximum may be in the range of 0.5 to 2, according to an embodiment, the ratio between the first local dopant concentration maximum and the second local dopant concentration maximum may be in the range of 0.9 to 1.1. The ratio between the sum of the first local dopant concentration maximum and the second local dopant concentration maximum on the one hand and the local dopant concentration minimum on the other hand may be in the range of 2 to 10. According to an embodiment, the ratio between the sum of the first local dopant concentration maximum and the second local dopant concentration maximum on the one hand and the local dopant concentration minimum on the other hand may be in the range of 5 to 7.

[0091] The vertical dopant concentration profile reflects the dopant concentration along a vertical direction perpendicular to the first surface. A vertical dopant concentration profile having the aforementioned characteristics can approximate a box-shaped vertical dopant profile to a sufficient degree for some applications and can be formed with relatively low effort (e.g., a vertical dopant concentration profile having the aforementioned characteristics can be formed with less effort than other vertical dopant concentration profiles having other characteristics). To further smooth the resulting doping profile, the implantation energy and / or implantation dose can be varied for implants at different angles.

[0092] According to an embodiment, the vertical dopant concentration profile of the doped region may include a first trailing slope and a second trailing slope. The first trailing slope may be between the second local dopant concentration maximum and the local dopant concentration minimum. The second trailing slope may be between the first local dopant concentration maximum and the second surface of the semiconductor body. The second trailing slope may be steeper than the first trailing slope.

[0093] The second surface may be opposite the first surface. By using channeling dopant ions, a vertical dopant concentration profile having twin peaks and a steeper tail slope at the deeper end of the range peak can be formed in an efficient manner. The channeling dopant ions can promote a doped region having a bottom edge that is a considerable distance from the first surface. For example, the distance from the bottom edge to the first surface can be greater (e.g., due to the channeling dopant ions) than the distance between the dopant region surface and the bottom edge formed in the absence of the channeling dopant ions.

[0094] According to an embodiment, forming the doped region may include implanting dopant ions into the semiconductor body using an ion beam implantation method as described above. The doped region can be formed in an efficient manner using a relatively low number of implantation operations. For example, by implementing one or more of the techniques provided herein (e.g., one or more techniques for ion beam implantation as described above), the doped region can be formed by performing a lower number of implantation operations than when forming the doped region without implementing one or more of the techniques provided herein.

[0095] According to embodiments, a semiconductor device may include a gate structure. The gate structure may extend from a first surface into the semiconductor body. The gate structure may contact a doped region. The doped region may form at least a portion of a source region, a body region, or a current diffusion region of a transistor cell of a power semiconductor switch or an MCD (MOS controlled diode). Source regions, body regions, and / or current diffusion regions that include the aforementioned characteristics of the doped regions may improve device characteristics of the semiconductor device with relatively low additional effort and / or may help simplify the manufacturing process, for example, by reducing the number of implantation steps and / or by reducing the maximum acceleration energy. For example, implementing source regions, body regions, and / or current diffusion regions that include at least some of the aforementioned characteristics of the doped regions may provide improved device characteristics of the semiconductor device compared to a semiconductor device that does not include at least some of the aforementioned characteristics. Alternatively and / or additionally, a semiconductor device that includes source regions, body regions, and / or current diffusion regions that include at least some of the aforementioned characteristics of the doped regions may be implemented with less effort than implementing a semiconductor device that includes source regions, body regions, and / or current diffusion regions that do not include at least some of the aforementioned characteristics.

[0096] According to an embodiment, a semiconductor device may include a body region in contact with a doped region and in contact with a gate structure. The doped region and the body region may form a pn junction. The doped region may be formed between the first surface and the body region. For example, the doped region may form a source region of a vertical transistor cell having a vertical load current flowing through the body region.

[0097] In the source region of the vertical transistor cell, the vertical dopant concentration profile comprising at least two peaks as described above may allow for adjusting the total bulk resistance of the source region with only low adverse side effects on the ohmic contact resistance between the source metallization and the source region and on the properties of the pn junction between the source region and the body region.

[0098] The bulk resistance can be adjusted to provide a voltage drop during a short-circuit condition. The voltage drop enables current filament cancellation and can reduce the effective gate overvoltage. When adjusting the bulk resistance of the source region, for example, a tradeoff can also be considered between i) increasing the bulk resistance of the source region to cancel current filament and / or reducing the effective gate overvoltage during short-circuit current loads and ii) reducing the on-state resistance of the device by reducing the bulk resistance of the source region.

[0099] According to an embodiment, the semiconductor device may include a source region in contact with the doped region and in contact with the gate structure. The doped region and the source region may form a pn junction. The source region may be formed between the first surface and the doped region. For example, the doped region may form a body region of a vertical transistor unit.

[0100] For example, the semiconductor material may include silicon carbide, and the dopant ions may include aluminum ions. Due to the channeling effect, the acceleration energy for a given vertical extension of the body region can be quite low. For example, as a result of the channeling effect (e.g., the channeling effect along the crystal channel direction, e.g., for channeling dopant ions to form the doped region), the acceleration energy for a given vertical extension of the body region can be lower than the acceleration energy for a given vertical extension of the body region of a doped region formed without the channeling effect. The lower acceleration energy can reduce the defect density in the body region after ion beam implantation and / or reduce the waviness of the vertical dopant concentration profile. The channeling portion of the vertical dopant concentration profile can increase the conductivity at the drain side of the body region without affecting the threshold voltage. In SiC-IGBTs, the higher transverse conductivity at the drain-side end of the body region can improve latch-up ruggedness. Furthermore, the deleterious effects of drain-induced barrier lowering can be reduced by such a doping profile. According to another example, the semiconductor material may include single crystal silicon and the dopant ions may include boron ions.

[0101] According to an embodiment, a semiconductor device may include a body region in contact with a doped region and in contact with a gate structure. The doped region and the body region may form a pn junction. The body region may be formed between a first surface and the doped region. For example, the doped region may form a current diffusion region of a vertical transistor cell. Due to a channeling effect used to define a first dopant concentration maximum, the current diffusion region may extend considerably deeper into the semiconductor body. For example, the current diffusion region may extend deeper into the semiconductor body (as a result of using a channeling effect to define the first dopant concentration maximum) than a current diffusion region formed without using a channeling effect to define the dopant concentration maximum.

[0102] Due to the current diffusion region having a channeling peak having a maximum distance from the first surface and having a local dopant concentration maximum toward a steep trailing edge of the lightly doped drift region, a high lateral conductivity of the highly conductive thin layer portion (e.g., a lateral conductivity exceeding a threshold conductivity) can be combined with a low vertical extension (e.g., a vertical extension less than a threshold vertical extension). In other words, the current diffusion region can effectively diffuse the on-state current laterally with a relatively low adverse effect on the blocking capability and / or on-state resistance. For example, the current diffusion region can diffuse the on-state current laterally with a lower effect (e.g., adverse effect) on the blocking capability and / or on-state resistance compared to other current diffusion regions that do not have at least some of the characteristics provided herein.

[0103] According to an embodiment, the vertical dopant concentration profile of the doped region may include at least one additional local dopant concentration maximum between the first surface and the second distance. For example, the vertical dopant concentration profile of the doped region may include at least one additional local dopant concentration maximum between the first surface and the second local dopant concentration maximum. The additional local dopant concentration maximum may originate from an additional ion beam implantation process. The additional ion beam implantation process may exclusively include ion beam implantation without channeling dopant ions. Alternatively, the additional ion beam implantation process may include at least one additional ion beam implantation process using a varying implantation angle around the target axis and using channeling dopant ions as described above.

[0104] The additional local dopant concentration maximum may contribute to improving the flatness of the vertical dopant concentration profile of the doped region. For example, the additional local dopant concentration maximum may improve the flatness of the vertical dopant concentration profile of the body region and / or the current spreading region.

[0105] According to embodiments, a semiconductor device may include a semiconductor body having a first surface and a doped region. The doped region may include a first local dopant concentration maximum at a first distance from the first surface, a second local dopant concentration maximum at a second distance from the first surface, and a local dopant concentration minimum between the first and second distances. For example, the doped region may include a local dopant concentration minimum at a third distance from the first surface. The third distance may be between the first and second distances. The semiconductor body may include silicon carbide. Starting from the first distance, the dopant concentration in the doped region may decrease by 10% (or 90%) of the first local dopant concentration maximum with increasing distance from the first surface within a range of up to 2 micrometers (μm), for example, up to 1.8 μm. For example, starting from the first distance from the first surface, the dopant concentration in the doped region may decrease by at least 10% (or at least 90%) of the first local dopant concentration maximum with increasing distance from the first surface within a range of up to 2 micrometers (μm), for example, up to 1.8 μm.

[0106] According to an embodiment, a semiconductor device may include a gate structure, wherein the gate structure may extend from a first surface into a semiconductor body. A doped region may be in contact with the gate structure. A body region may be in contact with the doped region and the gate structure. A source region may be in contact with the body region and the gate structure. The body region may separate the source region and the doped region. A vertical dopant concentration profile of the doped region may include at least one additional local dopant concentration maximum between the first surface and the second distance and at least one additional local dopant concentration maximum between the second distance and the first distance. For example, the vertical dopant concentration profile of the doped region may include at least one additional local dopant concentration maximum between the second local dopant concentration maximum and the first local dopant concentration maximum.

[0107] The embodiments of the ion beam implantation method described herein can be used in methods for manufacturing embodiments of semiconductor devices described herein. In at least some embodiments of the semiconductor device manufacturing method and / or semiconductor device, the following features (if applicable) apply individually or in combination:

[0108] (i) A doped region may form a shielding region for a gate structure of a vertical transistor cell, wherein the shielding region has the conductivity type of the body region, wherein a portion of the shielding region may be formed between the gate structure and a second surface of the semiconductor body, wherein a channeling peak may be located between a bottom of the gate structure and the second surface, wherein the shielding region and a source metallization may form a low-resistance ohmic contact, and wherein the semiconductor device may be a power semiconductor switch. The channeling dopant ions may promote a greater vertical extension of the shielding region and / or better shielding efficiency with low additional effort.

[0109] (ii) The doped region may form at least a portion of a junction termination region, wherein the junction termination region may be p-doped, wherein the junction termination region may be formed in an edge region of the semiconductor body, wherein the edge region may laterally surround a central region comprising a main pn junction of a power semiconductor diode or a functional transistor cell, wherein the junction termination region may surround the central region, and wherein the semiconductor device may be a power semiconductor diode or a power semiconductor switch. The channeling dopant ions may promote a greater vertical extension of the junction termination region and / or a higher efficiency with low additional effort.

[0110] (iii) The doped region may form a field ring, wherein the field ring may be p-doped, wherein the field ring may be formed in an edge region of the semiconductor body, wherein the edge region may laterally surround a central region including a main pn junction of a power semiconductor diode or a functional transistor cell, wherein the field ring may surround the central region, and wherein the semiconductor device may be a power semiconductor diode or a power semiconductor switch. The channeling dopant ions may promote a greater vertical extension of the field ring and / or higher efficiency with low additional effort.

[0111] (iv) The doped region may form a channel stopper zone, wherein the channel stopper zone may be n-doped, wherein the channel stopper zone may be formed in an edge region of the semiconductor body, wherein the edge region may laterally surround a central region comprising a main pn junction of a power semiconductor diode or a functional transistor cell, wherein the channel stopper zone may surround the central region, wherein the channel stopper zone may be in contact with a lateral outer surface of the semiconductor body, and wherein the semiconductor device may be a power semiconductor diode or a power semiconductor switch. The channeling dopant ions may promote a greater vertical extension of the channel stopper zone and / or a higher efficiency with low additional effort.

[0112] (v) An ion beam implantation method can form a field stop or buffer zone, wherein the field stop or buffer zone can have the same conductivity type as the source region of the transistor cell, wherein the field stop or buffer zone can be formed between a voltage sustaining layer and a heavily doped contact layer, wherein the voltage sustaining layer can include a compensation structure such as a superjunction structure and / or a lightly doped drift zone of the same conductivity type as the source region, wherein the contact layer and backside metallization form a low-resistance ohmic contact, wherein the backside metallization can contact a second surface of the semiconductor body, wherein the dopant concentration in the field stop or buffer zone can steadily decrease with increasing distance from the second surface, and wherein the semiconductor device can be a power semiconductor diode or a power semiconductor switch. Dopant ions can be implanted through the second surface. The dopant ions can include protons. In the case where the semiconductor material includes SiC, the dopant ions can include phosphorus ions and / or nitrogen ions. Channeling dopant ions can promote greater vertical extension of the field stop or buffer zone with low additional effort.

[0113] In order to realize the drift zone and the buffer / field stop zone by epitaxial technology, the epitaxial process can be interrupted (for example, after reaching a well-defined thickness) to realize the buffer layer by the above process, thereby realizing the injection into the surface defined by the epitaxial deposition; the epitaxial deposition of the drift zone can be performed (for example, the epitaxial deposition can be performed after reaching a well-defined thickness, after realizing the buffer layer and / or after realizing the injection into the surface).

[0114] (vi) An ion beam implantation method can form an emitter layer in a semiconductor body, wherein the emitter layer can have the same conductivity type as the body region, wherein the emitter layer forms a low-resistance ohmic contact with a backside metallization, wherein the backside metallization can be in contact with a second surface of the semiconductor body, wherein the emitter layer is formed between the backside metallization and a field stop zone, and wherein the semiconductor device can be an IGBT, such as a reverse blocking IGBT. Dopant ions can be implanted through the second surface. The dopant ions can include protons for implementing the field stop zone. In the case where the semiconductor material comprises SiC, the dopant ions can include phosphorus ions and / or nitrogen ions for implementing a buffer layer / field stop zone. Channeling dopant ions can promote a relatively small distance between a dopant concentration maximum, such as a proton density maximum, in the field stop zone and the emitter layer with low additional effort. For example, the distance between the dopant concentration maximum in the field stop zone and the emitter layer can be smaller (e.g., as a result of the channeling dopant ions) than the distance between the dopant concentration maximum and the emitter layer in a field stop zone formed without the channeling dopant ions. Reducing the distance between the dopant concentration maximum in the field stop zone and the emitter layer may help to improve short circuit strength and / or reduce leakage current.

[0115] (vii) An ion beam implantation method can form a doped column or portion of a doped column of a superjunction structure, wherein the superjunction structure can be formed in a voltage sustaining layer of a semiconductor body, and wherein the semiconductor device can be a power semiconductor switch or a power semiconductor diode. Channel effect dopant ions can help increase the vertical extension of the superjunction structure with relatively low additional effort. For example, the vertical extension of the superjunction structure can be increased (and / or the superjunction structure can be formed) with less effort (e.g., as a result of the channel effect dopant ions) than increasing the vertical extension of the superjunction structure (and / or forming the superjunction structure) without the channel effect dopant ions. The use of channel effect dopant ions can help reduce the total number of epitaxial sublayers in a multi-epi / multi-implantation process.

[0116] (viii) A method for manufacturing a semiconductor device may include forming a stray layer on a first substrate main surface of a semiconductor substrate, patterning the stray layer, and implanting dopant ions through the patterned stray layer using an ion beam implantation method having an implantation angle that varies about a target axis as described above and using channeling dopant ions. The patterned stray layer may include a main portion having a first thickness and at least one additional portion in which the stray layer is absent or in which the stray layer has a thickness that significantly deviates from the first thickness (e.g., the difference between the first thickness and the thickness of the stray layer exceeds a threshold difference). The patterned stray layer may facilitate formation of a laterally varying dopant profile with low additional effort.

[0117] Figures 1A-1F It involves alignment of substrate 700 and implantation of dopant ions at different implantation angles into substrate 700. Substrate 700 may comprise hexagonal polytype of silicon carbide. The preselected crystal channel direction 707 for the channeling dopant ions may be the c-axis.

[0118] Figure 1A A substrate 700 is shown having a first substrate main surface 701 at the front side, a second substrate main surface 702 at the back side, and a lateral outer surface 703 connecting the edges of the two substrate main surfaces 701 and 702. In the illustrated embodiment, a preselected crystal channel direction 707 for channeling is the c-axis, which is tilted at an off-axis cut angle α relative to the normal 704 toward the first substrate main surface 701. As an example, the off-axis cut angle α can be in the range of 3 to 5 degrees, for example, approximately 4 degrees. According to another embodiment (not shown), the preselected crystal channel direction can be an <11-23> lattice direction.

[0119] The substrate 700 is placed on a substrate holder of an ion beam implantation apparatus. The ion beam implantation apparatus is adapted to implant ions at different implantation angles, wherein the ion beam changes the implantation angle in an implantation angle plane extending orthogonally to the first substrate main surface 701. The ion beam has a default direction (idle ion beam axis). For ion beam implantation at a changed implantation angle, a deflection unit of the ion beam implantation apparatus deflects the ion beam relative to the default orientation. The deflection is effective in the implantation angle plane. In other words, for each implantation angle, the ion beam axis and the target axis span the same plane.

[0120] Prior to ion implantation, substrate 700 may be aligned with the implantation angle plane and the idle ion beam axis. Alternatively and / or in addition, during or after ion implantation, substrate 700 may be aligned with the implantation angle plane and the idle ion beam axis. Alignment with the implantation angle plane may include rotational motion ("twist"). Alignment with the idle ion beam axis may include tilting substrate 700. Ion beam tilt alignment may occur before or after rotational alignment.

[0121] Figure 1B A plan view of substrate 700 is shown. Substrate 700 has an almost circular horizontal cross-section with a flat 903 forming part of an outer lateral surface 703. Flat 903 generally indicates the orientation of a major crystal plane parallel to the c-axis, such as a (1-100) crystal plane or a (11-20) crystal plane. Alternatively, substrate 700 may include a notch in the outer lateral surface, wherein the notch generally indicates a major crystal orientation. For example, the angular deviation between flat 903 and the indicated major crystal plane is It can be in the range from -3 degrees to +3 degrees.

[0122] The rotational alignment brings the indicated major crystal plane into closer alignment with the implantation angle plane. In other words, the rotational alignment brings the lateral major crystal direction 708 in the associated major crystal plane into closer alignment with the lateral target direction 709 in the implantation angle plane.

[0123] For example, the rotational alignment may use an image recognition system that analyzes the orientation of the ribs 905 resulting from off-axis cutting at the first substrate main surface 701. Alternatively or in addition, the rotational alignment may use data that may individually indicate the angular deviation between the orientation of the indicated main crystal plane and the flatness 903 of each individual substrate 700.

[0124] Imperfections in the rotational alignment may result in a residual rotational misalignment ψ between the lateral principal crystal direction 708 and the lateral target direction 709. The residual rotational misalignment ψ may be in the range from -0.2 degrees to +0.2 degrees.

[0125] Figures 1C-1FInvolving beam tilt alignment. In an ion beam implantation apparatus, substrate 700 is oriented such that a preselected crystal channel direction 707 is aligned as best as possible with a target axis 706. Target axis 706 can be a default ion beam axis along which dopant ions propagate in idle mode, providing ion implantation at a constant implantation angle. Dopant ions are implanted (e.g., the dopant ions may be implanted after rotational alignment and beam tilt alignment).

[0126] Figure 1C The diagram shows the situation where the preselected crystal channel direction 707 is fully aligned to the target axis 706, with the minimum value 8011 and the maximum value 801 nmax The residual angular misalignment between the sweep of the ion beam axis 801 and is 0 degrees, and the preselected crystal channel direction 707 is in the angular center of the implantation angle range Rw.

[0127] For example, the implantation can be started from an implantation angle that is closest to the channeling direction and can be continued to implantation angles with a larger angular distance to the channeling direction. In this way, it may be possible to avoid or keep low a possible adverse effect of the previous implantation on the channel acceptance width. According to an embodiment with a symmetrical implantation angle range and with nmax being an odd number, the implantation can be started from an implantation angle corresponding to The injection angle of the idle beam axis starts and proceeds alternately to two boundary values: .

[0128] Due to technical imperfections regarding the off-axis cut angle and regarding the mechanism for orienting the substrate 700 to the target axis 706 , the preselected crystal channel direction 707 may typically not be perfectly aligned to the target axis 706 at the end of the beam tilt alignment.

[0129] Figure 1D The substrate 700 is shown at the end of the beam tilt alignment with a residual angular misalignment Δθ of approximately 2 degrees between the target axis 706 and the preselected crystal channel direction 707 .

[0130] like Figure 1E As shown in FIG, even with a residual angular misalignment Δθ of about 2 degrees, the preselected crystal channel direction 707 can still be within the implantation angle range Rw. Assuming that the half-channel acceptance width is less than the angular distance between the preselected crystal channel direction 707 and the closer of the boundary angles of the implantation angle range Rw, then Figure 1C In the case shown in , the same (or nearly the same) amount of ion dopant is implanted through the channel.

[0131] Figure 1FA substrate 100 is schematically shown positioned in an ion beam implantation apparatus. The substrate 100 can be secured to a substrate holder 750, for example, by electrostatic forces and / or by negative pressure. The substrate holder 750 can be adapted to perform rotational motion about a first horizontal rotation axis 610. The substrate holder 750 may or may not be configured to perform rotational motion about a second horizontal rotation axis 620. The second horizontal rotation axis 620 and the first horizontal rotation axis 610 can be perpendicular to each other. The first and second horizontal axes 610, 620 can lie in the same horizontal plane or can be spaced vertically apart. Additionally or alternatively, the substrate holder 750 can be adapted to perform rotational motion (twist) about a vertical rotation axis 630. The vertical rotation axis 630 can extend through the lateral center point of the substrate 100.

[0132] The ion beam implantation apparatus may include an ion beam projection apparatus 740 adapted to variably deflect the ion beam axis 801 at different angles in a first incident beam plane parallel to the first horizontal rotation axis 610. The ion beam projection apparatus 740 may or may not be adapted to variably deflect the ion beam axis 801 at different angles in a second incident beam plane parallel to the second horizontal rotation axis 620.

[0133] Figures 2A-2B shows a vertical dopant concentration profile (hereinafter: vertical dopant profile), which can be obtained by using the reference Figures 1A-1F The ion beam implantation method is achieved in a silicon carbide substrate having a hexagonal lattice. The vertical dopant profile may correspond to a portion of a vertical dopant profile of a doped region in a semiconductor body of a semiconductor device.

[0134] Figure 2A Figure 401 shows a vertical dopant profile for a dopant ion such as nitrogen ions, an ion beam implanted at an acceleration energy of 2.5 MeV, and an implantation angle swept symmetrically from -7 degrees to +7 degrees in 1 degree steps about a default ion beam direction. The preselected crystal channel direction is the c-axis of the 4H-SiC substrate. Line 401 represents the vertical dopant profile for an implant with the c-axis perfectly aligned to the target axis. Line 402 shows the dopant profile obtained when the residual angular misalignment Δθ between the target axis and the c-axis is equal to 0.5 degrees. Line 403 shows the dopant profile obtained when the residual angular misalignment Δθ between the target axis and the c-axis is equal to 1 degree. Reference numeral 404 denotes the end-of-range peak (main peak) for the randomly implanted dopant ions. Reference numeral 405 indicates the end-of-range peak (channeling peak) for the channeling dopant ions.

[0135] The position of the channeling peak 405 and the maximum dopant concentration Nch show little or no dependence on the residual angular misalignment Δθ. Furthermore, the angular misalignment Δθ has only a low impact on the remaining dopant ion distribution. Thus, the method can facilitate a highly predictable and reproducible vertical dopant profile for channeling dopant ions, while accounting for alignment imperfections and typical off-axis cut tolerances within a typical range for ion beam implantation equipment.

[0136] To predict the vertical dopant profile, it is sufficient to know that the residual angular misalignment between the target axis and the preselected crystal channel direction is within a certain range. Knowledge of the exact residual angular misalignment between the target axis and the selected crystal channel direction is not necessary to predict the vertical dopant profile with sufficient reliability (e.g., reliability exceeding a threshold reliability).

[0137] At a channeling peak 405, the vertical dopant profile has a first local dopant concentration maximum Nch at a first distance dch from the first surface at the front side of the semiconductor body or from the first substrate main surface at the front side of the semiconductor substrate. At a main peak 404, the vertical dopant profile has a second local dopant concentration maximum Npr at a second distance dpr. Between the first distance dch and the second distance dpr, the vertical dopant profile has a local dopant concentration minimum Nmin. The first distance dch is greater than the second distance dpr.

[0138] The difference between the first distance dch and the second distance dpr can be in the range of 400 nm to 550 nm. The ratio between the first local dopant concentration maximum Nch and the second local dopant concentration maximum Npr can be in the range of 0.9 to 1.1. The ratio between the sum of the first local dopant concentration maximum Nch and the second local dopant concentration maximum Npr on the one hand and the local dopant concentration minimum Nmin on the other hand can be in the range of 5 to 7.

[0139] exist Figure 2B In the example, the implant angle sweep is varied from -0.7 to +0.7 degrees in steps of 0.1 degrees. The effect of the angular misalignment on the position of the channeling peak 405 and the maximum dopant concentration is still small. The main peak 404 is significantly lower than Figure 2A The main peak in the example (e.g., Figure 2B The main peak 404 may be lower than Figure 2A The main peak 404, and / or Figure 2B The main peak 404 and Figure 2A The difference between the main peak 404 and the target axis may exceed a threshold difference). However, both the channeling peak 405 and the main peak 404 are independent of (and / or highly independent of) the residual angular misalignment between the target axis and the preselected crystal channeling direction.

[0140] Knowing the angular alignment accuracy of the ion implantation apparatus, the tolerance windows of the channel acceptance width and the substrate off-axis cut angle α, the number of implants and the implantation angle range can be selected to obtain the desired dopant distribution between the two range end peaks 404, 405.

[0141] Figure 2A and 2B The vertical dopant distribution benefits from the channeling effect. Therefore, the implantation method allows the formation of doped regions with considerable vertical extension at relatively low energy. For example, by implementing one or more of the techniques provided herein (e.g., one or more implantation techniques), doped regions with greater vertical extension can be formed compared to forming doped regions without implementing one or more of the techniques provided herein. Alternatively and / or in addition, by implementing one or more of the techniques provided herein (e.g., one or more implantation techniques), doped regions with vertical extension can be formed using lower energy compared to forming doped regions with vertical extension without implementing one or more of the techniques provided herein. By combining the end-of-range peaks of the randomly implanted dopant ions, the method promotes the approximation of a plateau-like vertical dopant distribution, wherein, in the plateau-like dopant distribution, the dopant concentration changes by a relatively low amount across a relatively large vertical range (e.g., the dopant concentration in the plateau-like dopant distribution can change less than a threshold amount across a vertical range greater than a threshold).

[0142] Figures 2C to 2D The diagram shows the Figure 2A Further details of the vertical dopant profiles 401, 402, and 403 are provided. For simplicity, the ion beam divergence is assumed to be Gaussian and time-invariant. Similarly, the channel acceptance function 421 used to channel a particular dopant ion is approximated as a time-invariant Gaussian distribution. For example, the channel acceptance function 421 can be obtained through simulation or by Rutherford Backscattering Spectrometry (RBS).

[0143] exist Figure 2C In the example, the c-axis is precisely at 4 degrees, and the first substrate major surface is tilted exactly 4 degrees relative to the default ion beam axis. The channeling direction (e.g., c-axis) is perfectly aligned with the idle beam axis. The tilted implantation includes 15 individual shots, one of which is implanted at an angle parallel to the channeling direction and the others are symmetrical about the channeling direction and at equal angular distances. The dashed line 422 depicts the summed profile, which has 1.5×10 13 centimeters (cm) -2Each single shot has an integrated dose of 1.0×10 12 cm -2 The integrated dose is . The total distribution is constant from about -2 degrees to about +2 degrees. The total distribution is multiplied by the channel acceptance function 421 in angular space and results in the function shown by the dashed line 423. The resulting shaded area 424 below the dashed line 423 corresponds to the integrated dose during the peak channeling effect.

[0144] exist Figure 2D In Figure 4, the incident default ion beam axis is misaligned by 1 degree with the channeling direction. In other words, the incident multi-shot center is still at 0 degrees, but the c-axis is at 1 degree. The total distribution (dashed line 422) multiplied by the channeling acceptance function 421 in angular space and the resulting shaded area 424 corresponding to the integrated dose at the channeling peak is about Figure 2C are approximately the same.

[0145] Figure 3 The semiconductor device 500 shown in FIG. 5 may be an IGBT (Insulated Gate Bipolar Transistor), an MCD (MOS Controlled Diode), or an IGFET (Insulated Gate Field Effect Transistor), such as a MOSFET (Metal Oxide Semiconductor FET).

[0146] The semiconductor device 500 includes a semiconductor body 100, which may include silicon carbide crystals having main components of silicon and carbon. The silicon carbide crystals may include impurities and / or dopant atoms such as hydrogen and oxygen.

[0147] The first surface 101 at the front side of the semiconductor body 100 can be planar or ripped. A surface normal 104, which is perpendicular to the planar first surface 101 or the mean plane of the ripped first surface 101, defines a vertical direction. Directions perpendicular to the surface normal 104 are horizontal and lateral directions. A second surface 102 at the back side of the semiconductor body can extend parallel to the first surface 101.

[0148] The semiconductor device 500 may include a transistor cell TC having a gate structure 150 extending from a first surface 101 into a semiconductor body 100. The gate structure 150 includes a gate dielectric 159 and a conductive gate electrode 155. The gate electrode 155 is electrically separated from the semiconductor body 100. For example, the gate dielectric 159 may completely separate the gate electrode 155 from the semiconductor body 100.

[0149] The transistor cell TC further includes a source region 110, a body region 120, and a shielding region 140. The source region 110 and the body region 120 adjoin (eg, directly adjoin) a first sidewall of the gate structure 150. The source region 110 is between the body region 120 and the first surface 101. The body region 120 separates the source region 110 from the drift structure 130.

[0150] The drift structure 130 is formed between the body region 120 and the second surface 102. The body region 120 and the drift structure 130 form a first pn junction pn1. The body region 120 and the source region 110 form a second pn junction pn2.

[0151] The shielding region 140 may extend along the second sidewall of the gate structure 150. The dopant concentration in the shielding region 140 along the second sidewall may be higher than the dopant concentration in the body region 120 along the first sidewall, for example, at least ten times higher than the dopant concentration in the body region 120 along the first sidewall. The vertical extension of the shielding region 140 may be greater than the vertical extension of the gate structure 150. For example, the local dopant concentration maximum in the shielding region 140 may have a greater distance from the first surface 101 than the bottom of the gate structure 150.

[0152] The drift structure 130 includes a voltage sustaining layer. For example, the voltage sustaining layer may include a drift zone 131. The vertical extension and dopant concentration in the drift zone 131 are selected so that the semiconductor device 500 reaches its nominal blocking voltage capability. The drift zone 131 may be formed in a layer grown by epitaxial growth. The average net dopant concentration in the drift zone 131 may be in the range of 1.0×10 15 cm -3 to 5.0×10 16 cm -3 The vertical extension of the drift zone 131 is related to the nominal blocking capability of the semiconductor device 500. The vertical extension of the drift zone 131 may be in the range of approximately 1 μm to several tens of μm.

[0153] The drift structure 130 further includes a heavily doped contact layer 139 adjacent to (e.g., directly adjacent to) the second surface 102. The heavily doped contact layer 139 contacts the backside metallization 320 adjacent to (e.g., directly adjacent to) the second surface 102. Along the second surface 102, the dopant concentration in the contact layer 139 is sufficiently high (e.g., above a threshold dopant concentration) such that the contact layer 139 and the backside metallization 320 form a low-resistance ohmic contact. If the semiconductor device 500 is or includes an MCD or an IGFET, the contact layer 139 has the same conductivity type as the drift zone 131. If the semiconductor device 500 is an IGBT, the contact layer 139 has a complementary conductivity type to the drift zone 131 or includes zones of both conductivity types.

[0154] The drift zone 131 may adjoin (e.g., directly adjoin) the contact layer 139, or a field stop or buffer zone 135 may be formed between the drift zone 131 and the contact layer 139. The field stop or buffer zone 135 forms a unipolar junction with the drift zone 131. The vertical extension of the field stop of the buffer zone 135 may be approximately in the range from 1 μm to 10 μm. For example, the average dopant concentration in the field stop or buffer zone 135 may be in the range from 1.0×10 17 cm -3 to 1.0×10 18 cm -3 The field stop of the buffer zone 135 may relax mechanical stresses in the semiconductor body 100 and / or may help to shape the electric field in the drift structure 130 .

[0155] The drift structure 130 may include further doped regions, such as current spreading regions 137 or counter-doped regions of the conductivity type of the barrier zone and / or drift zone 131. Each current spreading region 137 may abut (e.g., directly abut) the body region 120 and may extend between adjacent shielding regions 140. The average net dopant concentration in the current spreading regions 137 is higher than in the drift zone 131.

[0156] The front electrode 310 is electrically connected to the source region 110, the body region 120, and the shield region 140. The interlayer dielectric 210 electrically separates the front electrode 310 and the gate electrode 155.

[0157] According to an embodiment, transistor cell TC is an n-channel FET cell having a p-doped body region 120 , an n-doped source region 110 and an n-doped drift zone 131 . According to another embodiment, transistor cell TC is a p-channel FET cell having an n-doped body region 120 , a p-doped source region 110 and a p-doped drift zone 131 .

[0158] The source region 110, the body region 120, the current spreading region 140, the shielding region 140, the contact layer 139 and / or the field stop or buffer zone 135 may be formed using, for example, a reference Figures 1A to 1F The ion beam implantation method of the channel effect dopant ions and the varying implantation angle as described above is formed. For example, the semiconductor device 500 may include the semiconductor device 500 as described in reference Figures 4A-4C 、 Figure 5 、 Figure 6 and Figure 7 The method also applies to further layouts and designs of transistor cells TC, for example to transistor cells with a double-sided channel.

[0159] Figure 4A Shown Figure 3 1 . A possible vertical source doping profile 430 of the source region 110 of FIG. 1 is shown. The vertical source doping profile 430 shows the dopant concentration ND as a function of the distance d from the first surface 101. The vertical source doping profile may include a main peak 434 in the first source sub-region 111, a local doping concentration minimum 436 or valley in the second source sub-region 112, and a channeling peak 435 in the third source sub-region 113. For example, the doping concentration value at the local doping concentration minimum 436 may be adjusted relative to a desired overall bulk resistance of the source region 110.

[0160] Figure 4B This relates to a second source subregion 112 having more than one local doping concentration minimum 436. Figure 4B In the example shown in FIG, the second source sub-region 112 comprises two local doping concentration minima 436 and one local doping concentration maximum 437. The number of doping minima and doping maxima may also be greater than Figure 4B As shown in .

[0161] exist Figure 4C In the embodiment, the doping in the source region 110 includes an n-type component and a p-type component. The n-type component may have a similar Figure 4A 4. The vertical source dopant profile 440 of the vertical source dopant profile is shown in FIG. The p-type component may further include a channeling peak and a main peak. The p-type main peak may be formed between the n-type main peak and the n-type channeling peak and may be used to tune the effective ohmic resistance of the source region between the first surface 110 and the body region 120. The p-type channeling peak may form a portion of the body region 120 and may define a pn junction between the third source sub-region 113 and the body region 120.

[0162] Figure 5 Shown Figure 3 A possible vertical body doping profile 440 of the body region 120 of FIG. The vertical body doping profile 440 shows the vertical body doping profile 440 as a function of the distance d to the first surface 101. Figure 3 The dopant concentration ND in the body region 120 may be 0. The vertical body doping profile 440 may include a main peak 444 in the first body sub-region 121 , a local doping concentration minimum 446 or valley in the second body sub-region 122 , and a channeling peak 445 in the third body sub-region 123 .

[0163] exist Figure 6 In FIG. 4 , the vertical current spreading doping profile 460 is shown as a function of the distance d from the first surface 101. Figure 3The dopant concentration ND in the current diffusion region 137 is denoted by ΔN. The vertical current diffusion doping profile 460 may include a first pair of a main peak 4641 and a channeling peak 4651 produced by ion beam implantation with an acceleration energy of 2.5 MeV. The vertical current diffusion doping profile 460 may include a second pair of a main peak 4642 and a channeling peak 4652 produced by ion beam implantation with an acceleration energy of 2.1 MeV. Each pair of channeling peaks and main peaks has a specific distance from each other. The vertical current diffusion doping profile 460 may include additional peaks 467 produced by additional implantation that may or may not use channeling.

[0164] exist Figure 7 In FIG. 4 , another vertical doping profile 470 shows the dopant concentration ND in the doping region as a function of the distance d to one of the main surfaces of the semiconductor body. The vertical doping profile 470 may be Figure 3 , where d indicates the distance to the first surface 101 at the front side. Alternatively, the vertical doping profile 470 may be a vertical doping profile in a P-doped column or in an N-doped column of a superjunction structure.

[0165] The doped region includes a first local dopant concentration maximum at a first distance dch1 (d=0) from the first surface, a second local dopant concentration maximum at a second distance dpr1 from the first surface, and at least one local dopant concentration minimum between the first distance dch1 and the second distance dpr1. Starting from the first distance dch1, the dopant concentration in the doped region decreases with increasing distance from the first surface by 90% of the first local dopant concentration maximum within the first distance d1. For example, the semiconductor body includes or consists of 4H-SiC, and the first distance d1 is at most 2 μm.

[0166] Figure 7 Also shown is a vertical reference doping profile 450 formed without the use of a channeling effect. A vertical body doping profile 470 shows a steeper tail slope at the side opposite the first surface than the vertical reference doping profile 450. Using the possibility of defining two peaks using one ion implantation process using varying implantation angles, the vertical doping profile 470 can be formed by a lower number of ion beam implants than the vertical reference doping profile 450.

[0167] The doping profile 470 may include at least two main peaks 4741, 4742 and two channeling peaks 4751, 4752. A first peak pair having one main peak 4741 and one channeling peak 4751 is produced by an ion beam implantation with a first accelerating voltage. A second peak pair having another main peak 4742 and another channeling peak 4752 is produced by an ion beam implantation with a second, lower accelerating voltage. The channeling peak 4752 of the second peak pair may be between the main peak 4741 and the channeling peak 4751 of the first peak pair. The channeling peak and the main peak of each peak pair have a specific distance to each other. The vertical body doping profile may include an additional peak 477 produced by an additional implantation that may or may not use channeling.

[0168] Another ion beam implantation method may include orienting a substrate to a lateral target direction of an ion beam implantation apparatus, wherein a residual angular misalignment between the lateral target direction and a lateral principal crystal direction is within a lateral angular tolerance interval. The method may also include implanting dopant ions into the substrate using an ion beam propagating in an incident beam plane parallel to the ion beam axis, e.g., spanned by the ion beam axis and the substrate normal, wherein the dopant ions are implanted at different twist angles between the incident beam plane and the lateral target direction, as described above. The different twist angles are within a twist angle range (total rotational sweep range). The twist angle range may be greater than the lateral angular tolerance interval, e.g., at least two times or at least three times the angular tolerance interval. The twist angle range may be less than ten times the lateral angular tolerance interval, e.g., at most five times or at most three times the angular tolerance interval. The lateral principal crystal direction may be a horizontal principal crystal direction, or may be an orthogonal projection of any principal crystal direction into the horizontal plane. The lateral target direction may be an orthogonal projection of the target direction described above into the horizontal plane.

[0169] The ion beam propagates along the ion beam axis as described above. As described above, the ion beam axis and the vertical direction can span the plane of the incident beam. For example, with a transverse target direction at 0 degrees, the total rotational sweep range of the implant position can be, for example, in the range of -14 degrees to +14 degrees, from -4.9 degrees to +4.9 degrees, from -2.1 degrees to +2.1 degrees, from -1.4 degrees to +1.4 degrees, or from -0.7 degrees to +0.7 degrees.

[0170] The lateral angle tolerance interval between the lateral target direction and the lateral main crystal axis can be at most 3 degrees, such as at most 1.6 degrees, at most 1 degree, at most 0.5 degrees, at most 0.2 degrees or at most 0.1 degrees. The total rotational sweep range of the implant position can be at most 10 times, such as at most 5 times, the lateral angle tolerance interval.

Claims

1. An ion beam implantation method, comprising: orienting the substrate to a target axis, wherein a residual angular misalignment between the target axis and a preselected crystal channel direction in the substrate is within an angular tolerance interval; as well as implanting dopant ions into the substrate through the first substrate major surface of the substrate using an ion beam propagating along an ion beam axis, wherein: Dopant ions are implanted at an implantation angle between the ion beam axis and the target axis; With respect to the implantation angle for implanting the dopant ions, the ion beam impinges on the same sub-region of the main surface of the first substrate; The injection angle is within the injection angle range; The channel acceptance width is effective for preselecting the crystal channel orientation; The implant angle range is greater than 80% of the sum of the channel acceptance width and twice the angular tolerance interval; and The implant angle range is less than 500% of the sum of the channel acceptance width and twice the angle tolerance interval.

2. The method according to claim 1, wherein: The ion beam is continuously scanned across the implantation angle range at least once to implant dopant ions into the substrate.

3. The method according to claim 1, wherein: Implanting the dopant ions includes performing nmax implantation sub-processes at nmax different implantation angles; The injection angle includes nmax different injection angles; and nmax is at least 2.

4. The method according to claim 3, wherein: The nmax different injection angles are equally spaced.

5. The method according to claim 3, wherein: nmax injection sub-processes include one or more injection sub-process pairs; and The injection angles of the one or more injection sub-process pairs are symmetrical with respect to the target axis.

6. The method according to claim 3, wherein: At least one of the nmax different implantation angles deviates from 0 degrees by at most 0.3 degrees.

7. The method according to claim 3, wherein: Adjacent implantation angles among the nmax different implantation angles differ from each other by at most 0.5 degrees.

8. The method according to claim 1, wherein: The injection angle range is up to 6 degrees.

9. The method according to claim 1, comprising: determining an angular deviation between a lateral principal crystal direction in the substrate and a lateral target direction; as well as Prior to implanting the dopant ions, the lateral main crystal direction is aligned with a lateral target direction based on the angular deviation.

10. A method for manufacturing a semiconductor device, comprising: orienting a substrate of the semiconductor device to a target axis, wherein a residual angular misalignment between the target axis and a preselected crystal channel direction in the substrate is within an angular tolerance interval; and implanting dopant ions into the substrate using an ion beam propagating along an ion beam axis to form a doped region in the substrate, wherein: the dopant ions are implanted at an implantation angle between the ion beam axis and a target axis; The injection angle is within the injection angle range; The channel acceptance width is effective for preselecting the crystal channel orientation; The implant angle range is greater than 80% of the sum of the channel acceptance width and twice the angle tolerance interval; The implant angle range is less than 500% of the sum of the channel acceptance width and twice the angle tolerance interval; the doped region comprising a first local dopant concentration maximum at a first distance from the first surface of the substrate, a second local dopant concentration maximum at a second distance from the first surface, and a local dopant concentration minimum at a third distance from the first surface; The third distance is between the first distance and the second distance; The first distance is greater than the second distance; A difference between the first distance and the second distance is in a range from 200 nanometers to 1500 nanometers; a ratio between the first local dopant concentration maximum and the second local dopant concentration maximum in a range from 0.5 to 2; and A ratio between the sum of the first local dopant concentration maximum and the second local dopant concentration maximum and the local dopant concentration minimum is in a range from 2 to 10.

11. The method according to claim 10, wherein: The vertical dopant concentration profile of the doped region includes a first tail slope between the second local dopant concentration maximum and the local dopant concentration minimum and a second tail slope between the first local dopant concentration maximum and the second surface of the substrate; as well as The second tail slope is steeper than the first tail slope.

12. The method according to claim 10, wherein: The semiconductor device includes a gate structure extending from a first surface into a substrate.

13. The method according to claim 12, wherein: The semiconductor device includes a body region in contact with the doped region and the gate structure; The doped region and the body region form a pn junction; and The doped region is formed between the first surface and the body region.

14. The method according to claim 12, comprising: A source region is formed between the first surface and the doped region, wherein: The doped region and the source region form a pn junction; and The source region contacts the doped region and the gate structure.

15. The method according to claim 12, comprising: A body region is formed between the first surface and the doped region, wherein: The doped region and the body region form a pn junction; and The body region contacts the doped region and the gate structure.

16. The method of claim 11, wherein: The vertical dopant concentration profile of the doped region comprises at least one further local dopant concentration maximum between the first surface and the second local dopant concentration maximum.

17. The method of claim 10, wherein: The injection angle range is up to 6 degrees.

18. A semiconductor device manufactured by using the method according to any one of claims 1 to 9, comprising: A semiconductor body comprising a first surface and a doped region, wherein: The semiconductor body includes silicon carbide; the doped region comprising a first local dopant concentration maximum at a first distance from the first surface, a second local dopant concentration maximum at a second distance from the first surface, and a local dopant concentration minimum at a third distance from the first surface; The third distance is between the first distance and the second distance; and Starting from a first distance from the first surface, the dopant concentration in the doped region decreases with increasing distance from the first surface by 90% of a first local dopant concentration maximum within a period of at most 2 micrometers.

19. The semiconductor device according to claim 18, comprising: a gate structure extending from the first surface into the semiconductor body, wherein the doped region contacts the gate structure; a body region contacting the doped region and the gate structure; and a source region in contact with the body region and the gate structure, wherein: The body region is between the source region and the doped region; and The vertical dopant concentration profile of the doped region comprises at least one further local dopant concentration maximum between the first surface and the second local dopant concentration maximum, and at least one further local dopant concentration maximum between the second local dopant concentration maximum and the first local dopant concentration maximum.

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