Reverse conducting insulated gate bipolar transistor and method for manufacturing reverse conducting insulated gate bipolar transistor

Abstract

According to an embodiment, an RC-IGBT (100) includes a semiconductor body (10) having an emitter side (11) and a collector side (19). The semiconductor body comprises at least one mixing region (18) at the collector side. The hybrid region comprises a plurality of first type regions (15) having a first conductivity type and being laterally spaced apart from each other by a semiconductor material of a second conductivity type. In a top view on the collector side, the first type regions of the mixing region are each formed in an elongated manner and each extend radially away from a reference point of the mixing region. The number of the first type regions of the mixing region is gradually increased in the direction away from the reference point.

Description

Technical Field

[0001] The present disclosure relates to a reverse conducting insulated gate bipolar transistor and a method for manufacturing the reverse conducting insulated gate bipolar transistor. Background Art

[0002] There is a need for an improved reverse conducting insulated gate bipolar transistor, for example for a transistor having improved reverse conducting characteristics and / or improved secondary snap-back events. Furthermore, there is a need for a method for manufacturing such a reverse conducting insulated gate bipolar transistor. Summary of the Invention

[0003] Embodiments of the present disclosure relate to a reverse conducting insulated gate bipolar transistor and a method for manufacturing the reverse conducting insulated gate bipolar transistor.

[0004] First, a reverse conducting insulated gate bipolar transistor will be described in detail. Hereinafter, the abbreviation RC-IGBT for "reverse conducting insulated gate bipolar transistor" will be used.

[0005] According to an embodiment, an RC-IGBT includes a semiconductor body having an emitter side and a collector side. The semiconductor body includes at least one hybrid region on the collector side. The hybrid region includes a plurality of first-type regions having a first conductivity type and laterally separated from one another by semiconductor material of a second conductivity type. In a top view from the collector side, the first-type regions of the hybrid region are each elongated and extend radially away from a reference point of the hybrid region. The number of first-type regions of the hybrid region increases progressively in a direction away from the reference point.

[0006] In case the first type regions are arranged in a radial and step-wise manner, a desired diode area can be obtained and, at the same time, a snap-free device can be realized.

[0007] The RC-IGBT described herein is particularly a power device. It can be configured to carry a current of at least 10 A and / or handle a voltage of at least 600 V and / or at most 6500 V. For example, the RC-IGBT is a low-voltage device for operation between 1000 V and 2000 V.

[0008] The semiconductor body can be based on silicon or silicon carbide. The thickness of the semiconductor body, measured in the vertical direction from the collector side to the emitter side, is, for example, at least 60 μm and / or at most 700 μm. For example, the thickness of the semiconductor body is at most 150 μm. The emitter side and the collector side are two sides of the semiconductor body and delimit the semiconductor body in the vertical direction.

[0009] A first main electrode (the so-called "emitter electrode") can be arranged on the emitter side and electrically contact the semiconductor body. A second main electrode (the so-called "collector electrode") is arranged on the collector side and electrically contact the semiconductor body, in particular the mixing region.

[0010] The mixed region is a collector-side region, i.e., the mixed region adjoins the collector side or respectively forms part of the collector side. The mixed region comprises a plurality of first-type regions, for example, at least 20 or at least 50 first-type regions. The first-type regions also adjoin the collector side, i.e., each forms part of the collector side.

[0011] The RC-IGBT may comprise a plurality of hybrid regions. All features disclosed herein in connection with one hybrid region are also disclosed for the other hybrid regions.

[0012] The first type region has a first conductivity type, which may be an n-type. Thus, the first type region may be n-doped. Alternatively, however, the first conductivity type may also be a p-type.

[0013] The first-type regions are laterally spaced apart from one another in a lateral direction, wherein the lateral direction is a direction perpendicular to the vertical direction. The lateral direction is, in particular, a direction parallel to the collector side and / or parallel to the main extension plane of the semiconductor body. For example, in a plan view from the collector side, each first-type region is formed continuously and without interruption.

[0014] The first type regions are separated from each other by semiconductor material of a second conductivity type. The second conductivity type is opposite to the first conductivity type. Thus, if the first conductivity type is n-type, the second conductivity type is p-type. Each first type region can be completely surrounded laterally by semiconductor material of the second conductivity type. The semiconductor material of the second conductivity type disposed between the first type regions also abuts the collector side, i.e., forms part of the collector side.

[0015] When viewed in a top view on the collector side, the first type regions are elongated. For example, the first type regions are all formed as strips. In addition, when viewed in a top view on the collector side, the first type regions extend away from the reference point of the mixing region like rays. That is, some or all of the first type regions are oriented primarily or entirely in the radial direction. The radial direction is a lateral direction pointing away from the reference point from the reference point. In particular, some or all of the main extension directions of the elongated first type regions are parallel or almost parallel to the radial direction.

[0016] For example, when viewed in a top view on the collector side, the main extension direction of some or all elongated first type regions extends perpendicularly to the outline of a circle or ellipse, wherein the reference point is located in the center of the circle or ellipse.

[0017] The number of first-type zones in a hybrid zone increases in a direction away from the reference point. This means that, when considering a certain azimuth sector (polar sector) covered by the hybrid zone, the number of first-type zones that are completely located in this azimuth sector is greater in zones farther from the reference point than in zones closer to the reference point. The azimuth sector can be 360° or can be a smaller azimuth sector of, for example, up to 20° and / or at least 5°. The azimuth angle or azimuth sector is defined relative to the reference point.

[0018] "Stepwise" means that the number of first type areas does not increase continuously, but increases in steps. In the top view on the collector side, each ladder is assigned a specific area of the mixing zone. These ladders are arranged one after another in the direction away from the reference point. For example, the ladder closest to the reference point has the least number of first type areas, and the ladder farthest from the reference point has the greatest number of first type areas. When comparing the number of first type areas in different ladders, only the first type areas within the (same) azimuth sector are counted.

[0019] For example, in each ladder or at least in the ladder closest to the reference point, all first type regions have the same length, wherein the length is measured along the main extension direction of the corresponding first type region.The first type regions of different ladders may have different lengths.

[0020] For example, the hybrid region comprises two or more ladders, in particular three or more ladders, wherein the greater the number of first type regions, the farther the ladders are from the reference point. For example, the hybrid region comprises at most ten such ladders, which are arranged one after another in a direction away from the reference point.

[0021] According to another embodiment, the semiconductor body includes a pilot region on the collector side. The pilot region adjoins the mixed region. The pilot region has the second conductivity type. Accordingly, the RC-IGBT can be a so-called "bi-mode insulated gate transistor," or BIGT for short. The terms "pilot region" and "BIGT" are well known to those skilled in the art. The pilot region forms part of the collector side.

[0022] The pilot region is a region of the device that is a pure IGBT, and the hybrid region is a region that actually forms an RC-IGBT. In particular, the pilot region is a continuous region at the emitter side, eg, a region without interruptions.

[0023] When viewed in a top view on the collector side, the area of the pilot region is particularly larger than the area of each first type region, for example at least 5 times or 10 times the area of each first type region. For example, the pilot region adjoins the collector electrode. The size of the pilot region is selected so that it reduces rebound. On the other hand, in order to keep the area of the RC-IGBT large, it may be advantageous to select a pilot region that is as small as possible. For example, when viewed in a top view on the top side, the area of the pilot region is at least d·d and / or at most 100·d·d and / or at most 90% of the active area, where d is the thickness of the semiconductor body measured in the vertical direction. This range has been shown to meet the above conditions.

[0024] According to another embodiment, in a plan view on the collector side, the reference point is located in the pilot region, for example, the reference point coincides with the center of gravity of the pilot region.

[0025] When the reference point is located in the pilot region, the first type region extends away from the pilot region like a ray. With the arrangement of the first type region, a homogeneous plasma distribution along the extension of the RC-IGBT can also be obtained for low-voltage applications, i.e., where the thickness of the semiconductor body is relatively small and the thermal performance is good.

[0026] According to another embodiment, in a top view on the collector side, the mixing zone completely surrounds the leading zone. In other words, the leading zone is completely surrounded laterally by the mixing zone. This means that the mixing zone covers an azimuthal sector of 360°.

[0027] According to another embodiment, in a top view on the collector side, a second type zone of the second conductivity type extends continuously from the pilot zone to the edge of the mixing zone. The edge of the mixing zone is the part of the mixing zone farthest from the reference point. The second type zone is, for example, a continuous zone interrupted by several first type zones. The second type zone can extend over the entire azimuth sector covered by the mixing zone. For example, the second type zone extends over a 360° azimuth sector, i.e., completely surrounds the reference point and / or the pilot zone. In particular, the second type zone is formed by a semiconductor material of the second conductivity type arranged between the first type zones.

[0028] This continuously formed second type region further contributes to a uniform distribution of the plasma generated during operation.

[0029] According to another embodiment, in a top view on the collector side, the first type regions are uniformly distributed around the reference point.For example, for each pair of adjacent first type regions within one ladder, the minimum distance between adjacent first type regions is the same.

[0030] Additionally or alternatively, the mixed region may have an n-fold rotational symmetry relative to a reference point in top view on the collector side. The integer n is, for example, at least 10 or at least 30 or at least 50 or at least 100.

[0031] According to a further embodiment, each step-wise increase is assigned a certain area of the collector side in a plan view onto the collector side.

[0032] According to another embodiment, the area assigned to at least one ladder is annular, for example shaped as an elliptical ring or a circular ring. For example, the area assigned to two or more ladders is annular. These rings are concentric relative to each other.

[0033] For example, each of the first-type regions has a first longitudinal end closest to the reference point and a second longitudinal end furthest from the reference point. In a top view from the collector side, the first longitudinal ends of the first-type regions can lie on the contours of different ellipses or circles around the reference point. These contours define the boundaries of the annular region of the ladder.

[0034] For example, in a top view, a first such contour encompassing a minimum area intersects a first number of first longitudinal ends. The first number is, for example, at least 10. A second such contour encompasses a larger area and intersects a second number of first longitudinal ends, where the second number is greater than the first number, for example, at least twice the first number. Furthermore, there may be a third such contour encompassing an even larger area and intersecting a third number of first longitudinal ends, where the third number may be greater than the second number. The contours may be concentric relative to a reference point.

[0035] According to another embodiment, the number of regions of the first type varies by a multiple of at least 2 or at least 3 or at least 5 from one ladder to an adjacent ladder.

[0036] According to another embodiment, within a ladder, i.e., within an area assigned to this ladder, the distance between two adjacent first-type areas (in particular, the distance within each pair of adjacent first-type areas) has a first value in the area closest to the reference point and a second value in the area farthest from the reference point. The second value is greater than the first value. In other words, the distance between two adjacent first-type areas (in particular, the distance within each pair of adjacent first-type areas) increases as one moves away from the reference point. For example, the distance increases gradually or continuously.

[0037] When talking about adjacent first type regions within a ladder, this means that the first type regions are adjacent in the azimuthal direction. In the radial direction, two adjacent first type regions may be located at the same height or at the same position, respectively.

[0038] According to another embodiment, the second value is at most 4 times the first value. In particular, the mixed region is formed so that when moving away from the reference point and before the ratio of the second value to the first value exceeds 4, the next step begins in which the number of first type regions increases. For example, in a region arranged azimuthally between two adjacent first type regions, when changing from one step to the next, a new first type region with an increased number of first type regions is formed.

[0039] For example, some first type regions start in one ladder and extend from this ladder over one or more further ladders that are further from the reference point than the ladder where the first type regions start.

[0040] For example, at least some or all of the first-type regions extend over only one ladder. That is, these first-type regions can be explicitly assigned to one ladder. However, some or all of these first-type regions in at least one ladder can be assigned to paired first-type regions in a next ladder that is further from the reference point, wherein the first-type region and the assigned paired first-type region are oriented in the same direction and / or have the same azimuthal position, i.e., have the same position in the azimuthal direction.

[0041] According to another embodiment, the maximum distance between two adjacent first type regions in one ladder is greater than the minimum distance between two adjacent first type regions in a next ladder located downstream from the one ladder in a direction away from the reference point.

[0042] According to a further embodiment, the width of the first type areas (measured perpendicularly to the respective main extension direction of these first type areas) is at most half the first value or at most ¼ the first value or at most ⅙ the first value.

[0043] According to another embodiment, the RC-IGBT further includes a plurality of transistor half-cells arranged one after another in a first lateral direction. Each transistor half-cell includes, for example, an injection region (also referred to as a source region) of the first conductivity type. The injection region is in electrical contact with an emitter electrode arranged on the top side. For example, the injection region is adjacent to the emitter electrode. For example, the injection region extends as far as the emitter side. The injection region can be a continuous region, for example without interruption. Each transistor half-cell can be assigned exactly one injection region on a one-to-one basis.

[0044] In addition to the injection region, the semiconductor body also includes at least one base region and a drift region. The drift region has a first conductivity type. The drift region is arranged vertically between the emitter side and the mixing region and / or the pilot region. The drift region may be adjacent to the mixing region and / or the pilot region. At least one base region is arranged vertically between the emitter side and the drift region. At least one base region has a second conductivity type. Each injection region is separated from the drift region by at least one base region, for example, in the lateral direction and / or vertical direction. For example, a separate base region can be assigned to each injection region and, accordingly, each transistor half cell. All transistor half cells can be formed identically within the limits of manufacturing tolerances.

[0045] RC-IGBTs can have a planar architecture or a trench architecture. A trench architecture means that there are several trenches extending from the emitter side into the semiconductor body (for example, two trenches per half-cell). The gate electrode of the RC-IGBT extends into at least some of these trenches. In a planar architecture, the gate electrode is arranged on the emitter side of the semiconductor body.

[0046] According to another embodiment, the extension of the transistor half-cell measured in the first lateral direction is less than the width of the first type region. For example, the ratio between the width of the first type region and the extension of the transistor half-cell is at least 1.2 and / or at most 5. The extension of the transistor half-cell is, for example, defined as the pitch between two adjacent transistor half-cells in the first lateral direction. Each two adjacent half-cells may be adjacent to each other and may be formed in a mirror-symmetrical manner with respect to each other.

[0047] According to another embodiment, the pilot region has a circular shape when viewed in a top view on the collector side. For example, the pilot region has a circular or elliptical shape. In particular, the pilot region can be formed by following the relationship x 2 / a 2 +y 2 / b 2 = 1, where x and y are coordinates on the collector side, the center of the pilot zone has coordinates x = 0 and y = 0, and a and b are fixed numbers. The center of the pilot zone can be its centroid. The center of the pilot zone can coincide with the reference point. For example, the main extension direction of the first type region is perpendicular to this contour.

[0048] According to another embodiment, the collector side has a rectangular shape, wherein the edges of the rectangle have a length L and a width W. Thus, L ≥ W. For example, L and W are at least 1 mm and / or at most 30 mm or at most 20 mm.

[0049] According to another embodiment, the area and shape of the pilot region are selected according to the area and shape of the collector side according to the following rules:

[0050] - if L<2·W, the collector side comprises only one pilot region surrounded by a mixed region, wherein the contour delimiting the pilot region satisfies 0.1≤(2·a) / L≤0.5, 0.1≤(2·b) / W≤0.5 and (2·a) / L=(2·b) / W, and

[0051] If L ≥ 2·W, the collector side includes several pilot regions, each of which is surrounded by a mixed region, and each pilot region is defined by a contour satisfying 0.1 ≤ (2·a) / L' ≤ 0.5, 0.1 ≤ (2·b) / W ≤ 0.5, and (2·a) / L' = (2·b) / W, where L'·c = L, c is an integer and is the number of pilot regions. In particular, L' ≥ W.

[0052] In other words, if the length L is less than twice the width W, the RC-IGBT includes only one pilot region and one mixing region on the collector side. If the length L is at least twice the width W but less than three times the width W, the RC-IGBT includes exactly two mixing regions and exactly two assigned pilot regions, and so on. Furthermore, if the collector side is square, the pilot region has a circular form. In the case of several pilot regions, the pilot regions are spaced apart from each other in the lateral direction.

[0053] With these design rules for the size of the pilot region, a good compromise between bounce-back reduction and homogeneous plasma contribution is achieved.

[0054] According to another embodiment, L ≥ 2·W and the collector side includes several pilot regions, each of which is surrounded by a mixing region and each of which is defined by a contour that satisfies 0.1 ≤ (2·a) / L' ≤ 0.5, 0.1 ≤ (2·b) / W ≤ 0.5, and (2·a) / L' = (2·b) / W, where L'·c = L, c is an integer and is the number of pilot regions. In particular, L' ≥ W.

[0055] According to another embodiment, the semiconductor body comprises an edge region at the collector side. The edge region may extend to a collector side edge delimiting the collector side in a lateral direction. For example, the edge region forms an edge of the collector side.

[0056] According to another embodiment, the edge region has a first conductivity type. Alternatively, the edge region has a second conductivity type. In particular, the edge region is a continuous region consisting of only one conductivity type.

[0057] According to another embodiment, the edge region laterally surrounds the mixing region and / or the pilot region. For example, the edge region laterally completely surrounds the mixing region and / or the pilot region. That is, in a top view from the collector side, the edge region can completely surround the mixing region and / or the edge region. For example, in this top view, the edge region forms a frame around the mixing region and / or the pilot region.

[0058] In a top view on the collector side, the edge region may overlap with the termination region of the RC-IGBT. For example, the edge region completely or partially overlaps with the termination region of the RC-IGBT.

[0059] When viewed in a top view on the collector side, the area of the edge region may be greater than the area of each first type region, for example at least 10 times the area of each first type region.The edge region may have a constant width along its extension around the mixing region and / or the pilot region.

[0060] According to another embodiment, the edge region has a second conductivity type. For example, the edge region has a lower doping concentration than the semiconductor material of the second conductivity type in the mixed region that is laterally arranged between the first type regions. For example, the doping concentration is at least one order of magnitude or at least two orders of magnitude lower than the doping concentration of the semiconductor material of the second conductivity type in the mixed region. In this way, leakage can be reduced while further improving SCSOA (thermal) capabilities.

[0061] According to another embodiment, the edge region has a first conductivity type. The doping concentration can be the same as or different from the doping concentration in the first conductivity type region. In the case of such an edge region, since the emitter connection portion of the p-type termination region serves as an additional anode region for the BIGT internal diode, on-state losses in diode operation mode can be reduced.

[0062] Next, a method for manufacturing an RC-IGBT will be described in detail. This method can be used to manufacture an RC-IGBT as specified herein. Therefore, all features disclosed in conjunction with the RC-IGBT are also disclosed for this method, and vice versa.

[0063] According to an embodiment, the method includes a step of providing information representing the length L and width W that the collector side of the RC-IGBT to be manufactured will have, wherein L≥W. Then, a semiconductor body having an emitter side and a collector side is manufactured according to the provided information. The semiconductor body is manufactured so that the semiconductor body includes at least one mixed region at the collector side. The mixed region includes a plurality of first-type regions, which have a first conductivity type and are laterally spaced apart from each other by semiconductor material of a second conductivity type. In a top view on the collector side, the first-type regions of the mixed region are each formed in an elongated manner and each extend radially away from a reference point of the mixed region. The number of first-type regions of the mixed region increases stepwise in a direction away from the reference point. If L≥2·W, the semiconductor body is manufactured from two or more such mixed regions, and if L<2·W, the semiconductor body is manufactured from only one such mixed region. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In the following, the RC-IGBT and the method for manufacturing the RC-IGBT will be explained in more detail with reference to the accompanying drawings based on exemplary embodiments. The accompanying drawings are included to provide further understanding. In the accompanying drawings, elements with the same structure and / or function may be represented by the same reference numerals. It should be understood that the embodiments shown in the accompanying drawings are illustrative representations and are not necessarily drawn to scale. As long as elements or components in different figures correspond to each other in terms of their function, their description will not be repeated for each subsequent figure. For the sake of clarity, elements may not appear with corresponding reference numerals in all figures.

[0065] Figures 1 to 3 A first exemplary embodiment of an RC-IGBT 100 is shown in a cross-sectional view. Figure 2 Shown in more detail Figure 1 The area indicated by the dotted rectangle. Figure 3 Shown in more detail Figure 2 part of. DETAILED DESCRIPTION

[0066] The RC-IGBT comprises a semiconductor body 10 having an emitter side 11 and a collector side 19 which are opposite to each other in a vertical direction. For example, the semiconductor body 10 is based on Si or SiC.

[0067] At the collector side 19, the semiconductor body 10 comprises alternatingly arranged first type regions 15 and second type regions 16. These first type regions and second type regions form a mixed region 18. The regions 15 and 16 are in electrical contact with a collector electrode 3 arranged on the bottom side 19. The collector electrode 3 is formed, for example, of metal.

[0068] The first type region 15 has a first conductivity type, which is hereinafter referred to as n-type, and the second type region 16 has a second conductivity type, which is hereinafter referred to as p-type.

[0069] Furthermore, the semiconductor body 10 comprises an edge region 18 ″ which forms a part of the collector side 19 and forms an edge of the collector side 19 . The edge region 18 ″ here has the second conductivity type, but alternatively it may have the first conductivity type.

[0070] The drift region 14 is arranged between the emitter side 11 and the collector side 19 . The drift region 14 has a first conductivity type, ie an n-type. The drift region 14 adjoins a first type region 15 and a second type region 16 .

[0071] A plurality of trenches 51, 52 extend from the emitter side 11 into the semiconductor body 10 and into the drift region 14. Trenches 51 are first type trenches, also referred to herein as active trenches, and trenches 52 are second type trenches, also referred to herein as inactive trenches or dummy trenches.

[0072] The first-type trenches 51 are filled with a conductive material that is electrically isolated from the semiconductor body 10 by an electrically insulating layer 40 (referred to herein as a "gate insulating layer"). Therefore, there is no direct electrical contact between the semiconductor body 10 and the conductive material in the first-type trenches 51. The gate insulating layer 40 is formed, for example, of an oxide (e.g., SiO2). The conductive material in the first-type trenches 51 may be highly doped polysilicon. The conductive material in the first-type trenches 51 is part of the gate electrode 4 of the semiconductor device 100.

[0073] The second-type trenches 52 are also filled with a conductive material, such as highly doped polysilicon, which is also electrically separated from the semiconductor body 10 by the same electrical insulating layer as the gate insulating layer 40. The conductive material in the second-type trenches 52 is part of the emitter electrode 2 arranged on the emitter side 11. The first base region 13a adjoins the emitter electrode 2 in a first contact region 6a (also referred to as "Rb base region") and is in electrical contact with the emitter electrode.

[0074] The semiconductor body 10 includes several base regions 13a, 13b, 13c, which are arranged vertically between the drift region 14 and the emitter side 11. The base regions 13a, 13b, 13c all have the second conductivity type, i.e., p-type, and all adjoin the drift region 14 and the emitter side 11. The first and second base regions 13a, 13b are shallower (have a smaller vertical extension) than the trenches 51, 52. The third base region 13c is deeper than the trenches 51, 52, i.e., it extends further into the semiconductor body 10.

[0075] As in Figure 1 As can be seen in FIG. 1 , the semiconductor device 100 is subdivided into a plurality of so-called “transistor half-cells”. Figure 3 One such transistor half-unit HF is shown in more detail in FIG. Figure 3 The structure between the vertical dashed lines. Figure 1 and Figure 2 In FIG. 1 , several such transistor half cells HF are arranged one after another in a first lateral direction extending from left to right. Two adjacent half cells HF are arranged in a plane extending perpendicular to the first lateral direction and passing through the third base region 13 c (see FIG. 1 ). Figure 3 The half units are mirrored relative to each other at the right vertical dashed line in FIG. The half units each have a lateral extension W4 in the first lateral direction.

[0076] As in Figure 3As can be seen in FIG, the half cell HF includes a portion (half) of the first base region 13c, the first type trench 51, the second base region 13b, the second type trench 52, and a portion (half) of the third base region 13c, which are arranged one after another in this order along the first lateral direction. The half cell HF further includes an implantation region 12 (source region 12) of the first conductivity type (i.e., n-type) vertically arranged between the first base region 13c and the top side 11. The implantation region 12 is adjacent to the first base region 13c and the first type trench 51. The implantation region 12 is further adjacent to the emitter electrode 2 and is in electrical contact with the emitter electrode.

[0077] Figure 4 The top view on the collector side 19 shows Figures 1 to 3 RC-IGBT 100. As can be seen here, semiconductor body 10 includes a pilot region 18' in addition to the mixed region 18. Pilot region 18' also has the second conductivity type, namely p-type. Furthermore, it can be seen that mixed region 18 completely surrounds pilot region 18' laterally. Edge region 18" completely surrounds mixed region 18 and pilot region 18' laterally.

[0078] The pilot zone 18' has a circular shape, ie a circle. The first type of zones 15 of the mixing zone 18 are all elongated, strip-shaped and extend radially relative to a reference point Z coinciding with the centre of the pilot zone 18'.

[0079] As in Figure 4 As can be further seen in FIG, the number of first type regions 15 in the mixing region 18 increases in a direction away from the reference point Z. In practice, the mixing region 18 can be subdivided into three steps. Each step is assigned an area that completely surrounds the leading region 18'. The area assigned to the innermost step is annular. The area assigned to the next radially further outward step is also annular. The area of the outermost step is defined by a square outline.

[0080] The number of first type regions 15 increases from the innermost ladder (innermost ring) to the middle ladder (middle ring) and increases again from the middle ladder to the outermost ladder. With this stepwise increase in the number of first type regions 15, the desired diode area can be maintained.

[0081] In particular, as in Figure 4 As can be seen in FIG, the density of the first type regions 16 decreases monotonically within each step when moving in the direction away from the reference point Z. At the transition to the next step, the density suddenly increases and then decreases monotonically again within this next step.

[0082] exist Figure 4It can also be seen in FIG. 1 that the second type region 16 of the second conductivity type extends continuously from the leading region 18 ′ to the edge region 18 ″. This enables the electron-hole plasma generated during operation to be uniformly distributed over the entire extension of the RC-IGBT 100 .

[0083] In this design, snapback is minimized because the pilot region is larger due to the circular design. This is particularly important for ultra-thin LV devices, where first snapback elimination and design rules for pilot IGBT design depend on device thickness. Accordingly, the hybrid region is designed to surround the pilot region with alternating p-type and n-type regions to minimize secondary snapback and increase the SOA limit. In practice, if the hybrid region is not properly designed and distributed around the pilot region, carrier injection can become non-uniform after the first snapback event. During IGBT turn-on, the plasma density reaches its highest point in the middle of the active region and directly above the pilot protruding from the active region. Consequently, the temperature at the center of the RC-IGBT is significantly higher compared to conventional standalone diode and IGBT approaches. This is even further exacerbated in ultra-thin LV devices, where plasma distribution can already be problematic. Furthermore, during IGBT turn-off, dynamic avalanche, which primarily increases turn-off losses at low temperatures and low currents, initiates very early in the cells directly above the pilot region, compromising BiGT device reliability. Here, the design of the hybrid region is selected to ensure smooth electrical characteristics and SOA performance.

[0084] Figure 5 Another exemplary embodiment of an RC-IGBT 100 is shown, again in a top view onto the collector side 19. Here, the collector side 19 is rectangular in shape, with different lengths L and widths W. Accordingly, the pilot region 18' is not circular, but rather elliptical. The first type regions 15 of the mixing region 18 also extend predominantly radially, but now run perpendicular to the elliptical contour that defines and delimits the pilot region 18'.

[0085] exist Figure 4 and Figure 5 In the embodiment, the length L is less than 2 times the width W. The contour defining or delimiting the pilot zone 18' is selected to follow the relationship x 2 / a 2 +y 2 / b 2 = 1, where x and y are coordinates on the collector side 19, where the center of the pilot region 18' has coordinates x = 0 and y = 0, and where a and b are fixed numbers. Figure 4 and Figure 5In both cases, the following conditions are satisfied: 0.1≤(2·a) / L≤0.5, 0.1≤(2·b) / W≤0.5, and (2·a) / L=(2·b) / W. Figure 4 In this case, W=L and a=b.

[0086] Figure 6 Another exemplary embodiment of an RC-IGBT 100 is shown in a top view onto the collector side 19. In this case, L ≥ 2·W. Therefore, the collector side 19 includes two mixed regions 18, each surrounding a uniquely assigned pilot region 18'. Each pilot region 18' satisfies 0.1 ≤ (2·a) / L' ≤ 0.5, 0.1 ≤ (2·b) / W ≤ 0.5, and (2·a) / L' = (2·b) / W, where L'·c = L, c being an integer and the number of pilot regions 18'. In this case, L' = L / 2.

[0087] Figure 7 Shown in more detail Figure 4 As can be seen here, the distance between two adjacent first-type regions 15 within a ladder (wherein this distance is measured in a direction perpendicular to the radial direction, i.e., in the azimuthal direction) continuously increases as one moves radially outward (i.e., from a first value W1 to a second value W2). Thus, the following constraints are satisfied: W2>W1 and W2≤4·W1. Upon transition to the next ladder, the number of first-type regions 15 increases, so that in the next ladder, the value W1 is again less than the value W2 of the previous ladder.

[0088] Moreover, the width W3 of each first type region 15 is smaller than the first value W1. Figure 3 As indicated in , the extension W4 of the transistor half-cell HF is smaller than the width W3 .

[0089] Figure 8 A flow chart of an exemplary embodiment of a method for manufacturing an RC-IGBT is shown. In step S1 , information I representing the length L and width W of the collector side 19 of the RC-IGBT to be manufactured is provided, where L≥W.

[0090] In a step S2 , a semiconductor body 10 having an emitter side 11 and a collector side 19 is produced according to the provided information I, such that the semiconductor body 10 comprises at least one mixed region 18 at the collector side 19 .

[0091] Mixing region 18 includes a plurality of first-type regions 15 having a first conductivity type and laterally separated from one another by semiconductor material of a second conductivity type. In a top view onto collector side 19, each of first-type regions 15 of mixing region 18 is elongated and extends radially away from a reference point Z of mixing region 18. The number of first-type regions 15 in mixing region 18 increases in a direction away from reference point Z. If L ≥ 2·W, the semiconductor body is formed from two or more such mixing regions 18, and if L < 2·W, the semiconductor body is formed from only one such mixing region.

[0092] As stated Figures 1 to 8 The embodiments shown in the accompanying drawings represent exemplary embodiments of the improved RC-IGBT and the improved method for manufacturing the RC-IGBT; therefore, these exemplary embodiments do not constitute a complete list of all embodiments according to the improved RC-IGBT and method. Actual RC-IGBTs and methods may differ from the illustrated embodiments, for example, in terms of arrangement, devices, and method steps.

[0093] Reference numerals

[0094] 2 Emitter electrode

[0095] 3 Collector electrode

[0096] 4 Gate electrode

[0097] 10 Semiconductor body

[0098] 11 Emitter side

[0099] 12 Injection area

[0100] 13 base region

[0101] 13a First base region

[0102] 13b Second base region

[0103] 13c third base region

[0104] 14 Drift Zone

[0105] 15 Type 1 area

[0106] 16 Type II Area

[0107] 18 Mixed Zone

[0108] 18' pilot area

[0109] 18” edge area

[0110] 19 collector side

[0111] 40 electrical insulation layer / gate insulation layer

[0112] 51 Type 1 groove

[0113] 52 Second type groove

[0114] 100RC-IGBT

[0115] W Width

[0116] L length

[0117] W1 first value

[0118] W2 second value

[0119] W3 width

[0120] W4 extension

[0121] I Information

[0122] S1 and S2 method steps.

Claims

1. A reverse conducting insulated gate bipolar transistor (100), comprising: - a semiconductor body (10) having an emitter side (11) and a collector side (19), wherein - the semiconductor body (10) comprises at least one mixing region (18) at the collector side (19), - the mixed region (18) comprises a plurality of first type regions (15) having a first conductivity type and being laterally spaced apart from one another by semiconductor material of a second conductivity type, - in a top view on the collector side (19), - the first type of zones (15) of the mixing zone (18) are each formed in an elongated manner and each extend radially away from a reference point (Z) of the mixing zone (18), - the number of first type areas (15) of the mixing area (18) increases progressively in a direction away from the reference point (Z), the semiconductor body (10) comprises at least one pilot region (18') at the collector side (19), and the at least one pilot region adjoins the mixing region (18), - said pilot region (18') has a second conductivity type, - in a top view on the collector side (19), the reference point (Z) is located in the pilot zone (18'), The area of the pilot region (18') is at least d·d and at most 100·d·d, wherein d is the thickness of the semiconductor body (10).

2. The reverse conducting insulated gate bipolar transistor (100) according to claim 1, wherein In a top view on the collector side (19), the mixing zone (18) completely surrounds the pilot zone (18').

3. The reverse conducting insulated gate bipolar transistor (100) according to claim 1 or 2, wherein: In a top view on the collector side (19), the second type region (16) of the second conductivity type extends continuously from the leading region (18') to the edge of the mixed region (18).

4. A reverse conducting insulated gate bipolar transistor (100) according to any one of the preceding claims, wherein - in a top view on the collector side (19), the first type of regions (15) are uniformly distributed around the reference point (Z).

5. A reverse conducting insulated gate bipolar transistor (100) according to any one of the preceding claims, wherein - in a top view onto the collector side (19), each step of increasing size is assigned a certain area of the collector side (19), and At least one region assigned to a ladder is annular.

6. A reverse conducting insulated gate bipolar transistor (100) according to any one of the preceding claims, wherein - the number of first type regions (15) varies from one step to an adjacent step by a factor of at least 2.

7. A reverse conducting insulated gate bipolar transistor (100) according to any one of the preceding claims, wherein - within the ladder, the distance between each adjacent first type area (15) has a first value (W1) in the area closest to said reference point (Z) and a second value (W2) in the area farthest from said reference point (Z), - said second value (W2) is greater than said first value (W1) but is at most 4 times greater than said first value (W1).

8. The reverse conducting insulated gate bipolar transistor (100) according to claim 7, wherein: - a width (W3) of the first type of areas (15) measured perpendicularly to the respective main extension direction of the first type of areas is at most half of the first value (W1).

9. The reverse conducting insulated gate bipolar transistor (100) according to any one of the preceding claims, further comprising: a plurality of transistor half-cells (HC), said plurality of transistor half-cells being arranged one after another in a first lateral direction, - the extension (W4) of the transistor half-cell (HC) measured in the first lateral direction is smaller than the width (W3) of the first type region (15).

10. A reverse conducting insulated gate bipolar transistor (100) according to any one of the preceding claims, wherein - In a top view on the collector side (19), the pilot region (18') has a circular shape and is formed by the relation x 2 / a 2 +y 2 / b 2 = 1, wherein x and y are coordinates on the collector side (19), wherein the center of the pilot region (18') has coordinates x=0 and y=0, and wherein a and b are fixed numbers, - the collector side (19) has a rectangular shape, wherein the edges of the rectangle have a length L and a width W, and wherein L ≥ W, - The area and shape of the pilot region (18') are selected according to the area and shape of the collector side (19) according to the following rules: - if L<2·W, the collector side (19) comprises only one pilot region (18') surrounded by a mixing region (18), wherein the contour delimiting the pilot region (18') satisfies 0.1≤(2·a) / L≤0.5, 0.1≤(2·b) / W≤0.5 and (2·a) / L=(2·b) / W, and - If L ≥ 2·W, the collector side (19) includes several pilot regions (18'), each of which is surrounded by a mixing region (18) and each pilot region (18') is defined by a contour that satisfies 0.1 ≤ (2·a) / L' ≤ 0.5, 0.1 ≤ (2·b) / W ≤ 0.5 and (2·a) / L' = (2·b) / W, where L'·c = L, c is an integer and is the number of pilot regions (18').

11. The reverse conducting insulated gate bipolar transistor (100) according to claim 10, wherein: -L≥2·W, - the collector side (19) comprises several pilot regions (18'), each of which is surrounded by a mixing region (18) and each of which is defined by a contour satisfying 0.1≤(2·a) / L'≤0.5, 0.1≤(2·b) / W≤0.5 and (2·a) / L'=(2·b) / W, where L'·c=L, c is an integer and is the number of pilot regions (18').

12. A reverse conducting insulated gate bipolar transistor (100) according to any one of the preceding claims, wherein - the semiconductor body (10) comprises an edge region (18") at the collector side (19), The edge region (18") has the first conductivity type or the second conductivity type and laterally surrounds the mixed region (18).

13. The reverse conducting insulated gate bipolar transistor (100) according to claim 12, wherein: The edge regions (18") are of the second conductivity type and have a lower doping concentration than the semiconductor material of the second conductivity type arranged laterally between the regions (15) of the first type.

14. The reverse conducting insulated gate bipolar transistor (100) according to claim 12, wherein - the edge region (18") has a first conductivity type.

15. A method for manufacturing a reverse conducting insulated gate bipolar transistor (100), the method comprising: - providing information (I) representing the length L and width W that the collector side (19) of the reverse conducting insulated gate bipolar transistor (100) to be manufactured will have, where L≥W, - producing a semiconductor body (10) having an emitter side (11) and a collector side (19) according to the information (I) provided, so that, - the semiconductor body (10) comprises at least one mixing region (18) at the collector side (19), - the mixed region (18) comprises a plurality of first type regions (15) having a first conductivity type and being laterally spaced apart from one another by semiconductor material of a second conductivity type, - in a top view on the collector side (19), - the first type of zones (15) of the mixing zone (18) are each formed in an elongated manner and each extend radially away from a reference point (Z) of the mixing zone (18), - the number of first type areas (15) of the mixing area (18) increases progressively in a direction away from the reference point (Z), If L≧2·W, the semiconductor body (10) is produced from two or more such mixed regions (18), and if L<2·W, the semiconductor body (10) is produced from only one such mixed region (18).

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