METHOD AND DEVICE FOR PRODUCING AN EDGE STRUCTURE OF A SEMICONDUCTOR ELEMENT

Description

[0001] The present invention relates to a method for producing an edge structure of a semiconductor component according to the preamble of claim 1. Furthermore, the invention relates to an apparatus for producing an edge structure of a semiconductor component according to the preamble of claim 13.

[0002] Edge structures of semiconductor components, in particular power semiconductor components, serve in a known manner to increase the blocking capability of high-blocking semiconductor components, e.g., diodes, thyristors, IGBTs, and the like, by reducing the maximum electric field strengths that usually occur in the near-surface edge region of the component in order to achieve the most homogeneous distribution of the electric field in the component and thus the highest possible dielectric strength of the power semiconductor component.

[0003] Such edge terminations are often produced by removing a portion of the semiconductor body in its edge region, for example, in the region of a radially outer circumferential surface of the semiconductor body, in order to advantageously influence the course of the electric field in the edge region. In particular, a specific angle is set in the edge region of the semiconductor body by means of an edge bevel, at which, for example, a pn junction intersects the semiconductor surface of the edge bevel, thereby relieving the edge of high electric field strengths.

[0004] To achieve the highest possible dielectric strength of the component, it is crucial to adhere to a specified shape as precisely as possible during the production of such an edge termination. The process steps involved are complex, and exact reproducibility of the specified shape is often difficult. In conventional processes, such edge terminations are manufactured through a multitude of work steps. The semiconductor body can typically be manufactured mechanically in a first step, for example, by grinding at a negative angle with high precision and good reproducibility.

[0005] EP 1 005 064 B1 discloses a device for wet etching the edge of a semiconductor wafer. The device comprises a carrier with a support surface for rotatingly supporting the semiconductor wafer and a nozzle arranged above the semiconductor wafer, the nozzle's orifice section being designed and oriented such that an etching fluid jet emerging from the orifice section impinges on a defined surface section of the edge of the semiconductor wafer to be treated at an angle of > 0 and < 90 degrees to the plane of the semiconductor wafer.

[0006] GB 1 031 043 A discloses that in semiconductor devices, at a junction between a layer of one conductivity type and a more highly doped layer of a different conductivity type, the surface of the lower conductivity layer is shaped so that this layer decreases in cross-sectional area in a direction away from the intersection. This is intended to reduce the tangential electric field at the body surface. The surface of the higher conductivity layer can also be shaped. The document describes various shapes that the surface of the layers can take. Reference is made to devices in which a layer of one conductivity type is sandwiched between two more highly conductive layers of the opposite or different conductivity type. The low conductivity layer is shaped so that its cross-sectional area initially decreases in the direction away from both junctions.

[0007] Against this background, the object of the present invention is to provide a method and a device for producing an edge structure of a semiconductor component, which enable cost-effective and efficient production of a predetermined edge structure, i.e. contour of an edge region or edge surface, of the semiconductor component with high accuracy and reproducibility in order to ensure, among other things, a high yield in the volume production of semiconductor components with regard to desired electrical, mechanical or geometric properties. Furthermore, the electrical properties of the components achievable by means of the edge structure produced according to the method should be as stable as possible with regard to inherently unavoidable fluctuations in the manufacturing process. Furthermore, the required work steps should be both efficient to carry out and their number overall reduced.

[0008] This object is achieved by a method having the features of claim 1 and by a device having the features of claim 13. Further advantageous embodiments of the invention are disclosed in the respective subclaims.

[0009] It should be noted that the features listed individually in the claims can be combined with one another in any technically reasonable manner (even across category boundaries, for example, between methods and devices) and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures.

[0010] It should also be noted that a conjunction "and / or" used herein between two features and linking them together is always to be interpreted in such a way that in a first embodiment of the subject matter according to the invention only the first feature can be present, in a second embodiment only the second feature can be present and can be manufactured at a negative angle with high accuracy and good reproducibility.

[0011] Against this background, the object of the present invention is to provide a method and a device for producing an edge structure of a semiconductor component, which enable cost-effective and efficient production of a predetermined edge structure, i.e. contour of an edge region or edge surface, of the semiconductor component with high accuracy and reproducibility in order to ensure, among other things, a high yield in the volume production of semiconductor components with regard to desired electrical, mechanical or geometric properties. Furthermore, the electrical properties of the components achievable by means of the edge structure produced according to the method should be as stable as possible with regard to inherently unavoidable fluctuations in the manufacturing process. Furthermore, the required work steps should be both efficient to carry out and their number overall reduced.

[0012] This object is achieved by a method having the features of claim 1 and by a device having the features of claim 13. Further advantageous embodiments of the invention are disclosed in the respective subclaims.

[0013] It should be noted that the features listed individually in the claims can be combined with one another in any technically reasonable manner (even across category boundaries, for example, between methods and devices) and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures.

[0014] It should also be noted that a conjunction "and / or" used herein between two features and linking them together is always to be interpreted in such a way that in a first embodiment of the subject matter according to the invention only the first feature can be present, in a second embodiment only the second feature can be present and in a third embodiment both the first and the second feature can be present.

[0015] Furthermore, the term "approximately" used herein is intended to indicate a tolerance range that a person skilled in the art considers usual. In particular, the term "approximately" is understood to mean a tolerance range of the referenced size of up to a maximum of + / -20%, preferably up to a maximum of + / -10%.

[0016] Furthermore, within the meaning of the invention, relative terms used herein with regard to a feature, for example "larger," "smaller," "higher," "lower," "faster," "slower," and the like, are always to be interpreted in such a way that manufacturing and / or implementation-related size deviations of the feature in question, which lie within the manufacturing / implementation tolerances defined for the manufacture or implementation of the respective feature, are not covered by the respective relative term.In other words, a size of a feature is only to be considered as "larger," "smaller," "higher," "lower," "faster," "slower," and the like, within the meaning of the invention, than a size of a comparison feature if the two comparison sizes differ so significantly in their value that this difference in size certainly does not fall within the manufacturing / implementation-related tolerance range of the feature in question, but is the result of purposeful action.

[0017] According to the invention, a method for producing an edge structure of a semiconductor component, such as diodes, thyristors and the like, comprises the steps: Providing a semiconductor body of the semiconductor component, which has at least two main surfaces spaced apart from one another, each with an edge, between which edges an edge surface extends, and etching a predetermined edge contour by applying a chemical etchant specifically to the edge surface by means of an etchant jet while simultaneously rotating the semiconductor body about a rotation axis.

[0018] Furthermore, according to the invention, the etchant jet is guided tangentially to the edge surface with a predetermined jet cross-section such that the etchant jet impinges on the edge surface with only a portion of its jet cross-section. The diameter of the etchant jet is smaller than the distance between the edges of the respective main surfaces that delimit the edge surface.

[0019] In the sense of the invention, an edge contour is understood to be a definable outline of the semiconductor body in its edge region in a cross-section of the semiconductor body. The edge contour defines the profile of the edge surface in the edge region of the semiconductor body. In particular, this is understood to mean the profile essentially perpendicular to the tangential direction determined by the rotation of the semiconductor body (herein also referred to as the circumferential direction of the semiconductor body or the edge surface).

[0020] In the ideal (mathematical) case, a tangent is a straight line that touches a given curve (in particular a curve of the edge surface) at a specific point. However, since the etchant jet does not strictly speaking describe a straight line in the mathematical sense and also has a two-dimensional diameter (i.e. jet cross-section), for the purposes of the invention, the etchant jet directed tangentially to the edge surface is to be understood as a geometric relationship between the edge surface and the etchant jet such that a part of the etchant jet (i.e. a part of the jet cross-section) touches a point or a flat area of ​​the edge surface (also referred to herein as the point of impact). The part of the etchant jet that does not touch the point of impact on the edge surface passes the edge surface without essentially being involved in a direct chemical etching effect on the edge surface.The etchant jet therefore does not hit the edge surface with its full jet cross-section, but only with a part of it.

[0021] The above-described tangential alignment of the etchant jet to the edge surface enables targeted control and management, e.g., reduction, of a conventionally essentially uncontrollable spreading of the etchant jet after impacting the edge surface due to the etchant splashing away from the impact site. The impact site of the etchant on the edge surface, which essentially corresponds to a wetting region in which the etchant directly exerts its etching effect on the semiconductor body, can be locally and very precisely delimited according to the invention. Furthermore, it is effectively prevented that the etchant impacting the edge surface inadvertently and uncontrolled reaches the main surfaces of the semiconductor body and thereby damages them. This makes it possible to apply a mask to areas not to be etched, e.g.Main surfaces, top and / or bottom of the semiconductor body, are eliminated, which reduces the number of required process steps and makes the process easier to carry out overall.

[0022] The tangential guidance of the etchant jet to the edge region of the semiconductor body to be etched, as disclosed herein, can be automated using appropriate control and, if necessary, sensor means, ensuring highly accurate reproduction of the edge structure, which imparts the predetermined electrical, mechanical, and geometric properties to the manufactured component. The edge chamfer can thus be created entirely through the etching process, without, for example, the need for mechanical pre- and / or post-processing of the edge surface. The high degree of automation increases the efficiency of component manufacturing due to short processing cycles, which is particularly advantageous in large-scale production. Component manufacturing costs can be significantly reduced.

[0023] The semiconductor body can be geometrically designed to be substantially rotationally symmetrical with respect to the rotation axis, for example, (circular) cylindrical or disk-shaped. In the case of a cylindrical or disk-shaped body, its two base surfaces, i.e., its top and bottom, can each form one of the main surfaces within the meaning of the invention, and the lateral surface of the cylindrical or disk-shaped body, or a part of the lateral surface, can form the edge surface within the meaning of the invention. However, the invention is not necessarily limited to such a configuration and arrangement of the respective surfaces.

[0024] The semiconductor component can preferably be a symmetrically blocking, bipolar component (ie having at least two pn junctions), such as a thyristor, or an asymmetrically blocking, in particular bipolar component (ie having only one pn junction), such as a diode and the like, and can be designed for blocking voltages of, for example, approximately 3.6 kV and more, but without necessarily being limited thereto.

[0025] The main surfaces of the semiconductor body can be formed, for example, as cathode and anode surfaces, e.g., of a thyristor, a diode, and the like, although the invention is not necessarily limited thereto. The edge surface of the semiconductor body can extend as an outer peripheral surface between the cathode and anode surfaces.

[0026] The process can be used particularly advantageously for the volume production of semiconductor components with a quantity of, for example, approximately 25,000 per year and more.

[0027] According to an advantageous development of the subject matter of the invention, an edge bevel is etched as the edge contour using the etchant jet, the contour of which, macroscopically speaking, differs from the original contour of the edge surface existing before etching. In other words, the material removal caused by the etching effect of the etchant is not uniform throughout the edge region of the semiconductor body. Rather, the material removal is greater / lesser in one section of the edge region than in another section of the edge region.

[0028] In contrast, an essentially constant material removal over the entire edge surface does not, from a macroscopic perspective, change its original edge contour that existed before the etching process.

[0029] The material removal in the edge region of the semiconductor body caused by etching can be constant in some sections and non-constant in other sections, whereby the etched edge contour differs in its course from the original edge contour. Constant material removal enables the formation of a straight edge contour in the non-circumferential / non-tangential direction of the semiconductor body (correspondingly in the radial and / or axial direction). The material removal in the edge region caused by etching can also be non-constant across the entire edge region in the non-circumferential / non-tangential direction, so that a curved, arcuate course of the edge contour in the non-circumferential / non-tangential direction of the semiconductor body can also be achieved.

[0030] If the amount of material to be removed in the edge region in the radial direction of the semiconductor body exceeds the maximum cross-section of the etchant jet, the etchant jet can be tracked in the radial direction while maintaining its tangential orientation to the edge surface. For this purpose, the etchant jet can be spatially displaced, for example, translationally and / or rotationally in the radial direction toward the edge surface. The tracking speed of the etchant jet can be selected so that it follows the contour in the edge region created by the etching effect.

[0031] In addition or alternatively to the above-described radial displacement of the etchant jet, a desired material removal in the edge region in the axial direction of the semiconductor body can be carried out by displacing the etchant jet translationally and / or rotationally in the axial direction of the semiconductor body in order to change the point of impact of the etchant jet on the edge region in the axial direction of the semiconductor body (i.e., substantially parallel to the axis of rotation).

[0032] In a further advantageous embodiment of the invention, the etched edge bevel is a so-called double-positive edge bevel. The double-positive edge bevel is characterized in that it recedes into the interior of the semiconductor body with respect to the main surfaces that delimit the edge surface, e.g., in the manner of a groove, notch, fillet, or similar. With the double-positive edge bevel, the main surfaces of the semiconductor body can advantageously be essentially (completely) retained in terms of area. The formation of the double-positive edge bevel requires a significantly smaller silicon region of the semiconductor body than, for example, a so-called negative or positive-negative edge bevel, the formation of which is always accompanied by a significant reduction in the size of the main surfaces.

[0033] Furthermore, the electrical properties of the semiconductor component achievable with the double-positive edge chamfer can be adjusted with significantly greater stability, even in the face of process fluctuations (i.e., process tolerances), so that the process can be further simplified without adversely affecting the quality of the manufactured semiconductor components. A high yield can still be guaranteed.

[0034] The double-positive edge bevel can be arranged and formed substantially symmetrically and centrally between the main surfaces with respect to a thickness of the semiconductor body (i.e., a distance between the main surfaces). However, the invention is not necessarily limited to this. The edge bevel can also be arranged and / or formed off-center between the main surfaces and / or asymmetrically.

[0035] Accordingly, an alternative embodiment of the invention provides that the etched edge bevel is an asymmetric edge bevel.

[0036] Another advantageous development of the subject matter of the invention provides that the edge contour is etched in at least two different etching steps, e.g. a first etching step and a second etching step, wherein between the etching steps at least one parameter from the group comprising a diameter of the beam cross-section, a volume flow of the etchant beam, ie the volume of etchant that is transported through a defined cross-section per time period, and a rotation speed of the semiconductor body is changed.

[0037] For example, the diameter of the beam cross-section during the first etching step can be deliberately chosen to be smaller than the diameter of the beam cross-section during the second etching step. The smaller beam cross-section makes it possible to significantly limit the spread of the etchant beam after it hits the edge surface, allowing the etching effect to be specifically limited to a very narrow area of ​​the edge surface. Furthermore, the smaller beam cross-section increases the degree of freedom in producing a specific shape for the edge contour. The desired shape of the edge contour can be accurately and precisely incorporated into the edge surface.

[0038] In the second etching step, the spread of the incident etchant jet can be deliberately increased by increasing the jet cross-section. In this way, any traces of etchant runoff and / or inhomogeneities in / on the edge surface that may have occurred during the first etching step can be effectively eliminated. The wider jet cross-section can, but is not necessarily limited to, preferably be selected in the second etching step such that the etchant jet wets essentially the entire surface of the etched edge contour and, as a result of the etching effect now uniformly exerted on the entire edge surface, achieves homogenization (e.g., smoothing) of the etched edge surface.

[0039] In any case, the larger beam cross-section leads to a more homogeneous etching effect and can thus be advantageously used for polishing and etching the edge surface, i.e., for the chemical removal of roughness peaks on the surface of the edge surface. Polishing and etching with a large beam cross-section of the etchant beam can particularly preferably be carried out as a final, final etching step after one or more previous etching steps. Additional or alternative options for deliberately increasing the spread are provided by the rotation speed and the volume flow (described below). These can therefore also be used for polishing and etching the edge surface.

[0040] Particularly preferably, the edge surface can be at least partially smoothed in a first etching step. For this purpose, the spread of the incident etchant jet can advantageously be increased, for example, by using a larger jet cross-section than, for example, when etching the edge bevel itself. Additional or alternative possibilities for deliberately increasing the spread are provided by the rotation speed and the volume flow (described below). These can therefore also be used to smooth the edge surface.

[0041] In the preferred design of the double-positive edge bevel, the groove-like or groove-like depression can first be introduced into the edge surface with the smaller jet cross-section, whereby the etchant jet with a larger diameter is additionally limited by the lateral flanks of the groove-like or groove-like double-positive edge bevel in the second etching step and is guided in a correspondingly controlled manner.

[0042] Alternatively, or in addition to changing the beam cross-section, the rotational speed at which the semiconductor body is rotated during the etching process, e.g., during the first etching step, can be selected to be greater than the rotational speed, e.g., during the second etching step (or vice versa). The higher rotational speed of the semiconductor body also significantly limits the spreading of the etchant beam after it impacts the edge surface. In the second etching step, a greater spreading of the etchant beam is deliberately permitted by reducing the rotational speed in order to achieve the effect described above (i.e., homogenization, smoothing).

[0043] Alternatively or in addition to changing the beam cross-section and / or changing the rotation speed of the semiconductor body, the volume flow of the etchant beam, for example, during the first etching step, can be selected to be smaller than the volume flow, for example, during the second etching step (or vice versa). By applying a smaller amount of etchant in the first etching step, the spreading of the etchant beam after it hits the edge surface is greatly limited. In the second etching step, a larger spreading of the etchant beam can be deliberately permitted by the larger amount of etchant per unit time in order to achieve the advantageous effect of homogenizing or smoothing the edge contour.

[0044] A further advantageous embodiment of the invention provides that the maximum beam cross-section of the ejected etchant beam is limited to a diameter of at most approximately 50%, preferably between approximately 10% and approximately 30%, of a distance between the edges of the respective main surfaces that delimit the edge surface. The distance corresponds to a thickness of the semiconductor body where the main surfaces of the semiconductor body are arranged spaced apart from one another and substantially parallel. This limitation of the beam cross-section can, in combination with the division of the entire etching process into the first and second etching steps described herein, be particularly advantageous for the first etching step, in which the beam cross-section is selected to be smaller than in the second etching step. Although an etchant beam with such a limited beam cross-section, with which the profile of the edge contour can be formed precisely, initially traces (i.e.Inhomogeneities) may occur on the semiconductor surface. However, these can be effectively eliminated in the second etching step with a larger beam cross-section of the etchant beam, as already described elsewhere.

[0045] According to an advantageous development of the subject matter of the invention, at least a portion of the edge surface is merely smoothed as the edge contour by means of the etchant jet, wherein an original contour of the smoothed portion of the edge surface, present prior to etching, remains unchanged from a macroscopic perspective. In other words, during pure smoothing, only a small area of ​​the edge surface is chemically removed in order to smooth the edge surface. For example, a rough edge surface (also referred to as "damage") may have arisen from cutting (e.g., laser cutting) of the semiconductor component in a preliminary process, i.e., before the actual etching process. This "damage" can advantageously also be removed using the method disclosed herein. To remove the "damage,"Depending on the surface roughness of the edge, the beam cross-section can preferably have a larger diameter than, for example, when etching a beveled edge. The larger beam cross-section results in a more homogeneous etching effect than a beam cross-section with a smaller diameter.

[0046] If the entire edge surface is smoothed exclusively, the edge contour remains essentially unchanged macroscopically as a result of etching, since only the damage is removed evenly across the entire edge surface. However, if only a portion of the edge surface is smoothed and an additional edge bevel, such as a double-positive edge bevel, is introduced into the edge surface, the edge contour in the area of ​​the introduced edge bevel changes due to etching compared to the original edge contour in this area.

[0047] Advantageously, a rotation direction of the semiconductor body at a point of impact of the etchant jet on the edge surface is substantially identical to a jet direction of the etchant jet. In other words, the tangential directions of the rotational movement and of the etchant jet essentially coincide at the point of impact, whereby the spread of the etchant jet impinging on the edge surface at the point of impact can be controlled very precisely in the manner disclosed herein.

[0048] Additionally or alternatively, an additive can be added to the etchant to reduce its surface tension, whereby the wetting properties of the etchant jet upon impact with the edge surface can be specifically influenced, e.g. the area of ​​the edge surface that can be wetted by the etchant during the contact period, ie after impact and before subsequent centrifugation, the spreading of the etchant jet after impact with the edge surface and the like.

[0049] According to a preferred embodiment, the rotation axis is aligned substantially vertically in space. An alternative embodiment provides for the rotation axis to be aligned substantially horizontally in space. In both embodiments, the effect of gravity can be additionally utilized to enhance the properties and effects according to the invention, depending on the arrangement of the edge surface to be etched. For example, gravity can be utilized to additionally specifically influence the running off or centrifugation of the etchant applied to the edge surface and / or the residence time (i.e., exposure time) of the etchant on the edge surface.Due to the effect of gravity, it may also be necessary to rotate the semiconductor body at a higher speed when the rotation axis is arranged vertically than when the rotation axis is arranged horizontally. This is necessary, for example, to ensure that the etchant is spun off sufficiently quickly after being applied to the edge surface, thereby reducing or preventing unwanted sagging of the etchant on the edge surface due to gravity. On the other hand, a lower rotation speed can be advantageously used to rotate semiconductor bodies with a larger diameter in order to reduce the centrifugal forces acting on the semiconductor body.

[0050] According to a further aspect of the invention, an apparatus for producing an edge structure of a semiconductor component comprises a rotatable carrier for holding a semiconductor body of the semiconductor component, at least one controllable nozzle for dispensing an etchant jet with a predetermined jet cross-section, and a control unit. The control unit is configured to control the carrier and / or the at least one nozzle using a method according to one of the disclosed embodiments, that is, in particular, to guide the etchant jet tangentially to the edge surface such that the etchant jet impinges on the edge surface with only a portion of its jet cross-section.

[0051] It should be noted that with regard to device-related definitions of terms as well as the effects and advantages of device-related features, reference can be made in full to the disclosure of analogous definitions, effects, and advantages of the inventive manufacturing method disclosed herein. This means that disclosures herein relating to the inventive manufacturing method can also be used analogously to define the device according to the invention, and vice versa, unless expressly excluded. In this respect, repetition of explanations of analogous features, their effects, and advantages can be omitted in favor of a more concise description, without such omissions being interpreted as a limitation.

[0052] The nozzle can be configured to controllably change its position and / or angular orientation in space. Alternatively or additionally, the nozzle can be configured to controllably change the properties of the etchant jet, e.g., the jet cross-section, a volume flow, pressure, and / or temperature of the etchant.

[0053] An advantageous embodiment of the invention provides for a plurality of nozzles to be distributed circumferentially around the carrier, in particular equidistantly distributed. For example, two to four nozzles can preferably be distributed circumferentially around the carrier. Particularly preferably, three nozzles can be arranged equidistantly around the carrier. The provision of a plurality of nozzles increases the etching effect, i.e., the material removal, that can be achieved per unit of time on the edge surface, thereby significantly reducing the time required to fully form the desired edge contour for each semiconductor component.

[0054] Further features and advantages of the invention will become apparent from the following description of non-limiting embodiments of the invention, which are explained in more detail below with reference to the drawings. In this drawing, schematically show: Fig. 1 a side view of one half of an exemplary semiconductor body of a semiconductor component before etching an edge structure, Fig. 2 an intermediate step in a side view of the semiconductor body 1 from Fig. 1 after a partial embodiment of an exemplary method for producing an edge structure according to the invention, Fig. 3 a side view of the semiconductor body from Fig. 2 with the according to the embodiment of the method according to the invention Fig. 2 completely manufactured edge structure, Fig. 4 a side view of an exemplary semiconductor body of a semiconductor component with an alternative edge structure completely manufactured according to an embodiment of the method according to the invention, Fig. 5 a side view (A) of an embodiment of a device for producing an edge structure according to the invention and a plan view (B) of the device from view (A) and Fig. 6 a plan view of a further embodiment of a device for producing an edge structure according to the invention.

[0055] In the different figures, parts that are equivalent in terms of their function are always provided with the same reference symbols, so that they are usually only described once.

[0056] Fig. 1 shows a side view of one half of an exemplary semiconductor body 1 of a semiconductor component prior to etching an edge structure. The semiconductor component can be, for example, a symmetrically blocking, in particular bipolar component (i.e., having at least two pn junctions, for example), e.g., a thyristor, or an asymmetrically blocking, in particular bipolar component with only one pn junction, such as a diode and the like, and can be designed for blocking voltages of, for example, approximately 3.6 kV and more. However, the invention is not necessarily limited to semiconductor components having the aforementioned features.

[0057] In the present case, the semiconductor body 1 shown is essentially cylindrical. Due to its essentially rotationally symmetrical shape, the semiconductor body 1 is Fig. 1 shown only on one side of its central axis 2 or axis of symmetry. The central axis 2 is simultaneously a rotation axis around which the semiconductor body 1 can be rotated, as will be described in more detail below.

[0058] The Fig. 1 The exemplary cylindrical semiconductor body 1 shown has a first disk-shaped main surface 3 and a second disk-shaped main surface 4. The first main surface 3 can, for example, form a cathode structure 8 of the semiconductor component (e.g., diode, thyristor, etc.), which is only indicated schematically, and the second main surface 4 can, for example, form an anode structure 9 of the semiconductor component, which is also only indicated schematically. For this purpose, the semiconductor regions 8 and 9 can each be provided with dopants in a manner well known per se in order to provide desired conduction properties (e.g., p- / n-conduction) and / or semiconductor junctions between different conduction types (e.g., pn- / pnp junction, etc.).

[0059] In Fig. 1 The two main surfaces 3 and 4 are clearly arranged at a distance from one another; in the present case, they also run parallel, although this is not necessarily limited to this. The first main surface 3 has a radially outer edge 5 that borders it, while the second main surface 4 has a radially outer edge 6 that borders it. An edge surface 7 of the semiconductor body 1 extends between the edges 5 and 6 of the two main surfaces 3 and 4, respectively.

[0060] The distance between the two main surfaces 3 and 4 corresponds in this case to a thickness D of the semiconductor body 1. The distance of the edge surface 7 to the central axis 2 essentially corresponds to a radius R of the semiconductor body 1.

[0061] In the semiconductor body 1 of the illustrated embodiment, two pn junctions 17 and 18 can be seen by way of example, as they can be provided in this or a similar manner in a symmetrically blocking component such as a thyristor. The invention is not necessarily limited to the presence of two pn junctions. Fewer or more than two pn junctions can be provided in the semiconductor body 1. It should be noted that the distance between the pn junctions 17 and 18 and the respective main surfaces 3 and 4, respectively, is not shown to scale.

[0062] In Fig. 1 A surface roughness of the edge surface 7 is indicated by the jagged dashed lines, although not to scale. The rough edge surface, which is also referred to as "damage," can, for example, have been created by cutting the semiconductor body 1 in a preliminary process, i.e., before the actual etching process described below to form an edge contour. The roughness of the edge surface 7 essentially has an extension in a radial direction of the semiconductor body 1, which is designated by the reference numeral 10 in Fig. 1 is specified.

[0063] In Fig. 1 Furthermore, an etchant jet 11 can be seen, the jet direction of which points into the plane of the drawing. The etchant jet 11 is thus aligned tangentially to the edge surface 7. The etchant jet 11 has a (in this case essentially circular) jet cross-section 12 with a diameter d1A chemical etchant forming the etchant jet 11 may have an additive added to reduce its surface tension, but is not necessarily limited to this.

[0064] In order to etch a predetermined edge contour, ie, a predetermined profile of the edge surface 7, by removing material from the edge surface 7, the chemical etchant is applied in a targeted manner to the edge surface 7 by means of the etchant jet 11, while the semiconductor body 1 is simultaneously rotated about the rotation axis 2. In the present case, the direction of rotation of the semiconductor body 1 and the jet direction of the etchant jet 11 essentially coincide at the point of impact of the etchant jet 11 on the edge surface 7.

[0065] Further in Fig. 1 It is shown that the etchant jet 11 is guided tangentially to the edge surface 7 during the etching process for forming the edge contour, such that the etchant jet 11 impinges on the edge surface 7 with only a portion of its jet cross-section 12. The tangential orientation of the etchant jet 11 to the edge surface 7 according to the invention makes it possible to very precisely control any spreading of the etchant jet 11 after impinging on the edge surface 7, which spreading is caused by the etchant spraying away from the edge surface 7. As a result, the etching effect of the etchant on the edge surface 7 can be very precisely limited locally. Furthermore, this prevents the etchant impinging on the edge surface 7 from inadvertently and uncontrollably reaching the main surfaces 3, 4 of the semiconductor body 1 and thereby damaging them.

[0066] In the Fig. 1 In the example shown, the rough surface of the entire edge surface 7 or only a part of the edge surface 7* (as shown for example in Fig. 2 and 3 shown) are smoothed, wherein the contour of the edge surface 7 after smoothing essentially corresponds (ie viewed macroscopically) to the contour of the edge surface 7 before smoothing, ie both the original, rough and the smoothed edge contour in the present case essentially run parallel to the central axis 2.

[0067] In order to use the etchant jet 11, whose diameter d1 is smaller than the thickness D of the semiconductor body 1 - preferably a maximum of 50% of the thickness D of the semiconductor body 1 or more preferably a maximum of 10% to 30% of the thickness D- to smooth the entire edge surface 7, the etchant jet 11 in the embodiment shown here can be directed in an axial displacement direction a of the semiconductor body 1. For example, a Fig. 1 The nozzle (not shown) for dispensing the etchant jet 11 can be displaced translationally and / or rotationally in space in order to change the point of impact of the etchant jet 11 on the edge region 7 in the axial direction of the semiconductor body 1 (ie essentially parallel to the central or rotational axis 2).

[0068] In order to achieve material removal at the edge surface 7 in the entire semiconductor region 10 of the semiconductor body 1, the etchant jet 11 can also be displaced in a radial displacement direction r in space. For this purpose, the Fig. 1 The nozzle (not shown) for dispensing the etchant jet 11 can be moved translationally and / or rotationally in space. The tracking speed of the etchant jet 11 in the radial direction r is preferably selected such that it always follows the contour of the edge surface 7 resulting from the etching effect while maintaining its tangential orientation to the edge surface 7 as described herein.

[0069] In the presently shown embodiment, the rotation axis 2 is aligned vertically in space, but is not necessarily limited to this. For example, the rotation axis 2 can also be 90° to the direction of the Fig. 1 shown rotation axis 2, i.e. aligned horizontally in space.

[0070] Fig. 2 shows a side view of the semiconductor body 1 Fig. 1 an intermediate step after a partial implementation of an exemplary method for producing an edge structure according to the invention. It can be seen that a part 7* of the edge surface 7 as above for Fig. 1 explained was first smoothed. Furthermore, a portion of an edge bevel 13 was etched using the etchant jet 11, the shape of which, macroscopically viewed, differs from the original contour of the edge surface 7 as it existed before etching. Fig. 2 The edge bevel 13 shown is an example of a double-positive edge bevel. It is set back in the radial direction relative to the main surfaces 3 and 4 and is thus designed in the form of a groove, notch, chamfer, or the like, directed towards the interior of the semiconductor body 1. In the Fig. 2 In the intermediate step shown, a first section of the edge bevel 13 was treated with the etchant jet 11 and a jet diameter d2etched. For this purpose, the etchant jet 11 was directed both in the axial direction a and in the radial direction r each shifted relative to the semiconductor body 1, as already described in connection with Fig. 1 In the example shown here, the beam diameter d2 larger than the beam diameter used solely for smoothing d1 in Fig. 1 . The larger beam diameter d2 allows for rapid material removal when forming the double-positive edge bevel 13 opening towards the edges 5 and 6 of the respective main surfaces 3 and 4, while simultaneously achieving a homogeneous etching effect on a relatively wide area of ​​the edge surface 7. The beam diameter d2can be determined, for example, by a correspondingly controllable diameter of a nozzle opening (not shown) or by selecting a separate nozzle (also not shown) with a corresponding nozzle diameter. The volume flow of the etchant jet 11 can also be adjusted accordingly. As shown in Fig. 2 As shown, the edge bevel 13 in the intermediate state has a maximum height 14 and a temporary depth 15 which is determined from the edges 5, 6 of the respective edge surfaces 3 and 4, respectively.

[0071] It should be noted that the part 7* of the edge surface 7 is not mandatory. In extreme cases, it is also possible to set the maximum height 14 of the edge bevel 13 equal to the thickness D of the semiconductor body 1 so that the part 7* of the edge surface 7 is not present.

[0072] In Fig. 2 It can be seen that in this case, both pn junctions 17, 18 each intersect the curved edge contour of the edge bevel 13, which is why the edge bevel 13 can be referred to as a double-positive edge bevel and has the advantages explained herein. However, the invention is not necessarily limited to the double-positive edge bevel 13. In principle, other edge bevels can also be produced with the invention, such as those used for asymmetrically blocking components such as diodes, which may have only one pn junction 17 or 18 (cf. Fig. 4 ).

[0073] Fig. 3 shows a side view of the semiconductor body 1 Fig. 2 with the according to the embodiment of the method according to the invention Fig. 2 fully finished edge structure. It can be seen that the edge bevel 13 has reached a final depth 16 which is greater than the temporary depth 15 in Fig. 2 For a better comparison, Fig. 3 as a dashed line additionally the course of the edge bevel 13' from Fig. 2 The maximum width 14 in the final state of the edge bevel 13 can be increased compared to the intermediate state Fig. 2 be essentially unchanged. Even if this is a preferred variant, the invention is not necessarily limited to this, ie the width 14 can vary between the Fig. 2 and Fig. 3 shown condition, especially in Fig. 3 be larger than in Fig. 2 .

[0074] To achieve the greater depth 16 in conjunction with a contour of the edge bevel 13, which has a smallest radius at the deepest, ie radially innermost, point, starting from the state in Fig. 2 a beam diameter d3 of the etchant jet 11, which is smaller than the jet diameter d2 in Fig. 2 . This also allows you to set a desired (optimal) bevel angle α at the transition of part 7* of the edge surface 7 to the beginning of the edge bevel 13. The angle α is preferably selected between approximately 35 ° and 45 °. If the maximum width 14 of the edge bevel 13 is substantially equal to the thickness D of the semiconductor body 1, the angle α on the transition from edge 5 or 6 to edge bevel 13.

[0075] As shown above based on the Fig. 1 bis 3 As explained above, the method for producing the edge structure can be divided into several individual etching steps, in particular at least two, which differ from one another in that at least one method parameter is changed between the individual etching steps, which in the above exemplary embodiment concerned the beam cross-section or beam diameter d1, d2, d3 of the etchant beam 11. However, it should be understood that other method parameters, such as the volume flow of the etchant beam 11 and / or the rotational speed of the semiconductor body 1, can also be changed in addition to or alternatively to the beam cross-section, as has already been explained in the general part of this description.

[0076] Deviating from the above description of the Fig. 1 bis 3 In the embodiment shown, the diameter of the beam cross-section 12 of the etchant beam 11 during a first etching step can also be selected to be smaller than the diameter of the beam cross-section 12 during a second etching step.

[0077] Alternatively or additionally, the rotation speed of the semiconductor body 1 during a first etching step can be selected to be greater than the rotation speed during a second etching step.

[0078] Alternatively or additionally, the volume flow of the etchant jet 11 during a first etching step can be selected to be smaller than the volume flow during a second etching step.

[0079] These and other combinations of etching steps with different process parameters and a different execution sequence are conceivable and are also encompassed by the present disclosure.

[0080] Fig. 4 shows a side view of an exemplary semiconductor body 19 of a semiconductor component with an alternative edge structure 13 completely manufactured according to an embodiment of the method according to the invention. Fig. 4 It can be seen that the etched edge bevel 13 in this case is an asymmetrical edge bevel and, without any mandatory limitation, in particular an edge bevel with a positive angle. It is to be understood that the Fig. 4 The final state of the etched edge bevel 13 shown in FIG. 1 by means of the etching method according to the invention disclosed herein from a semiconductor body 1, as shown for example in Fig. 1 shown can be generated.

[0081] The Fig. 4 The asymmetric edge bevel 13 shown can advantageously be used in semiconductor components that have only one pn junction, for example a single pn junction 17 (here assigned to the second main surface 4), for example a diode (ie asymmetrically blocking component). In a symmetrically blocking component with at least two pn junctions, such as a thyristor, the Fig. 3 shown symmetrical edge bevel 13 is provided in the semiconductor body 1.

[0082] Fig. 5 shows a side view A of an embodiment of a device 20 for producing an edge structure of a semiconductor component according to the invention as well as a plan view B of the device 20 from view A. It can be seen that the exemplary device 20 comprises a rotatable carrier 21 for holding a semiconductor body, e.g. semiconductor body 1, of the semiconductor component, at least one controllable nozzle 22 for dispensing an etchant jet, e.g. etchant jet 11, with a predetermined jet diameter 12, as shown for example in the Fig. 1 bis 3 shown, and a control unit 23. The control unit 23, which comprises, for example, an electronic computing and storage unit, is designed to control the carrier 21 and / or the at least one nozzle 22 for carrying out a method according to the invention disclosed herein. In particular, the nozzle 22 can be designed to controllably change its position and / or angular orientation in space and / or to controllably change properties of the etchant jet 11, such as jet cross-section, volume flow, pressure, and / or temperature of the dispensed etchant.

[0083] The rotation axis 2 of the Fig. 5 The device 20 shown is oriented vertically in space. As shown in Fig. 5 As shown, an alignment of the nozzle 22 in space both at a horizontal angle ϕ (View A) as well as at an elevation angle θ (View B) controllable (rotational displacement). A translational displacement of the nozzle 22 can be provided, but this is not mandatory.

[0084] In an alternative embodiment not shown, only a translational displacement of the at least one nozzle for dispensing the etchant jet 11 can be provided and a rotational displacement can be dispensed with.

[0085] Furthermore, Fig. 5 a clear spreading 24 of the etchant jet 11 after impinging on the edge surface 7 of the semiconductor body 1 can be seen. The spreading 24 can be specifically controlled and regulated using the method and device according to the invention in the manner disclosed herein. After the spreading of the etchant jet 11 on the edge surface 7, it is thrown off the edge surface 7 again as a result of the rotation of the semiconductor body 1. The thrown-off etchant is in Fig. 5 marked with the reference number 25.

[0086] Fig. 6 shows a plan view of a further embodiment of a device 30 for producing an edge structure according to the invention. The essential difference between the device 30 and the device 20 from Fig. 5 is that the device 30 has a plurality of nozzles 22, in this case three, arranged circumferentially distributed around the carrier 21. The nozzles 22 can advantageously be arranged circumferentially equidistant. The nozzles 22 can be made of Fig. 5 be designed to be controllable, in particular be controllable in position (translational) and / or angular orientation (rotational) in space and / or be controllable in the properties of the etchant jet 11 such as jet cross-section, volume flow, pressure and / or temperature of the etchant.

[0087] The above-described inventive method for producing an edge structure of a semiconductor component and the inventive device for producing such an edge structure are not limited to the embodiments shown herein, but also encompass other similarly effective embodiments resulting from technically expedient further combinations of the features of the respective subject matter described herein. In particular, the features and feature combinations mentioned above in the general description and the description of the figures and / or shown alone in the figures can be used not only in the combinations explicitly specified herein, but also in other combinations or on their own, and are likewise encompassed by the present invention.

[0088] In a particularly preferred embodiment, the method and the device for producing an edge structure of a semiconductor component are used to form a double-positive edge bevel on an edge surface of a semiconductor body of the semiconductor component, wherein the edge surface can advantageously be an outer peripheral surface of the semiconductor body. The semiconductor component can preferably be a symmetrically blocking, in particular bipolar component (i.e., having at least two pn junctions), e.g., a thyristor, or an asymmetrically blocking, in particular bipolar component (i.e., having only one pn junction), such as, e.g., a diode and the like, and can be designed for blocking voltages of, for example, approximately 3.6 kV and more. The method and the device according to the invention can be particularly advantageously used for the production of semiconductor components in a quantity of, for example, approximately 25.000 per year and more.

Claims

1. Method for producing an edge structure of a semiconductor component, comprising the steps: - providing a semiconductor body (1) of the semiconductor component, which semiconductor body comprises at least two mutually spaced-apart main faces (3, 4) respectively having an edge (5, 6), between which edges (5, 6) an edge face (7) extends, and - etching a predetermined edge contour by purposely applying a chemical etchant onto the edge face (7) by means of an etchant jet (11) with simultaneous rotation of the semiconductor body (1) about a rotation axis (2), wherein the etchant jet (11) is guided with a predetermined jet cross section (12), while being directed tangentially with respect to the edge face (7), in such a way that the etchant jet (11) impinges on the edge face (7) only with a part of its jet cross section (12), and a diameter (d1) of the etchant jet (11) is smaller than a spacing (D) of the edges (5, 6) of the respective main faces (3, 4) delimiting the edge face (7), wherein the spacing (D) corresponds to a thickness (D) of the semiconductor body.

2. Method according to Claim 1, wherein as the edge contour, an edge chamfer (13) whose profile is different from an original contour profile of the edge face (7) existing before the etching, considered macroscopically, is etched by means of the etchant jet (11).

3. Method according to the preceding claim, wherein the etched edge chamfer (13) is a double-positive edge chamfer.

4. Method according to Claim 2, wherein the etched edge chamfer (13) is an asymmetrical edge chamfer.

5. Method according to one of the preceding claims, wherein the edge contour is etched in at least two different etching steps, at least one parameter from the group comprising a diameter (d1, d2, d3) of the jet cross section, a volume flow rate of the etchant jet and a rotational speed of the semiconductor body being varied between the etching steps.

6. Method according to the preceding claim, wherein the edge face (7) is at least partially smoothed in a first etching step.

7. Method according to one of the two preceding claims, wherein running traces of the etchant and / or inhomogeneities on the edge face (7) are eliminated in a last etching step.

8. Method according to one of the preceding claims, wherein the maximum jet cross section (12) is limited to a diameter (d1, d2, d3) of at most 50%, or between 10% and 30%, of the spacing (D) of the edges (5, 6) of the respective main faces (3, 4) delimiting the edge face (7).

9. Method according to one of the preceding claims, wherein as the edge contour, at least a part (7*) of the edge face (7) is only smoothed by means of the etchant jet (11), wherein an original contour profile of the smoothed part (7*) of the edge face (7), existing before the etching, is maintained unchanged, considered macroscopically.

10. Method according to one of the preceding claims, wherein a rotation direction of the semiconductor body (1) at an impingement point of the etchant jet (11) on the edge face (7) is substantially the same as a jet direction of the etchant jet (11).

11. Method according to one of the preceding claims, wherein an additive is added to the etchant in order to reduce its surface tension.

12. Method according to one of the preceding claims, wherein the rotation axis (2) is aligned vertically or horizontally in space.

13. Device for producing an edge structure of a semiconductor component, comprising a carrier (21), which can be rotated about a rotation axis (2), for holding a semiconductor body (1) of the semiconductor component, at least one controllable nozzle (22) for delivering an etchant jet (11) having a predetermined jet cross section (12), and a control unit (23), wherein the control unit (23) is configured to control the carrier (21) and / or the at least one nozzle (22) by means of a method according to one of the preceding claims.

14. Device according to the preceding claim, wherein the nozzle (22) is configured to controllably vary its position and / or angular alignment (θ, ϕ) in space and / or to controllably vary properties of the etchant jet (11), such as jet cross section, volume flow rate, pressure and / or temperature.

15. Device according to one of the two preceding claims, wherein a plurality of nozzles (22) are arranged distributed, in particular equidistantly distributed, circumferentially around the carrier (21).