Segmented power diode with improved reverse recovery

Abstract

The power diode comprises a plurality of diode cells (10). Each diode cell (10) comprises a first anode layer (40) of a first conductivity type, a second anode layer (45) of the first conductivity type having a lower doping concentration than the first anode layer (40) and separated from the anode electrode layer (20) by the first anode layer (40), a drift layer (50) of a second conductivity type forming a pn junction with the second anode layer (45), a cathode layer (60) of the second conductivity type in direct contact with the cathode electrode layer (60), and a cathode-side segmentation layer (67) in direct contact with the cathode electrode layer (30). The material of the cathode-side segmentation layer (67) is a semiconductor of the first conductivity type, and the integrated doping content on the cathode side integrated along a direction perpendicular to the second main surface (102) is 2·10 13 cm -2 or the material of the cathode-side segmentation layer (67) is an insulating material. A horizontal cross section through each diode cell (10) along a horizontal plane (K1) includes a first region where the horizontal plane (K1) intersects with the second anode layer (45) and a second region where the plane (K1) intersects with the drift layer (50).

Description

[Technical field]

[0001] FIELD OF THEINVENTION The invention relates to a power diode according to the preamble of claim 1 and to a reverse conducting (RC) integrated gate commutated thyristor (IGCT) comprising such a power diode. [Background technology]

[0002] 2. Background of the Invention Fast power diode snap recovery has been investigated for many years in view of the need for faster power semiconductor devices with lower switching losses during transients. Fast recovery diodes are typically used in combination with integrated gate commutated thyristors (IGCTs), insulated gate bipolar transistors (IGBTs) and gate turn-off thyristors (GTOs) as freewheeling, snubber and clamp diodes.

[0003] The depletion of residual stored charge during the recovery period of a power diode leads to a current discontinuity (chop-off) that appears in the current gradient dI / dt. dI / dt acts on the inductance of the circuit, resulting in a voltage overshoot (V L =-L dI / dt). Figure 1 shows the time dependence of the forward current IF and the voltage across the power diode during the recovery period. From Figure 1 it can be seen that at the end of the reverse recovery period the diode exhibits a snappy turn-off behavior (snap recovery). This is mainly due to insufficient thickness of the device. Snap recovery is mainly more pronounced at lower temperatures (25°C) and lower currents (less than 10% of nominal current). Snap recovery can be reduced by increasing the thickness of the device. However, this increases the conduction and switching losses.

[0004] Integrated gate commutated thyristors (IGCTs) have become established as the device of choice for high power applications such as medium voltage drives, pumped storage, railway inter-tie and power quality applications. Today, IGCTs are optimized for voltage source inverter (VSI), current source inverter (CSI) and event switching (solid-state circuit breaker) applications and are available as asymmetric, symmetric (reverse blocking) and reverse conducting (RC) devices. For VSI topologies, asymmetric IGCTs have the highest power levels for a given wafer size, while reverse conducting (RC) IGCTs offer compactness (reduced size and weight) and increased reliability (reduced component count) due to monolithic integration of power diodes on the same wafer as the gate commutated thyristors (GCTs).

[0005] In the RC-IGCT, the choice of silicon as the starting material is limited to one thickness, since both the IGCT and the diode are on the same wafer and use the same electrical pressure contacts (one on the top side of the wafer and another on the bottom side). The thickness is dictated by the device voltage and cosmic ray elasticity ratings, as well as the dynamic behavior of both the GCT and the diode components. The dynamic behavior of the diode components includes the previously mentioned diode snap-off behavior. Increasing the thickness improves all three mentioned aspects, but also increases losses in both operating modes. In a typical optimization of the RC-IGCT, the snap-off behavior dictates the minimum wafer thickness, which is why in the case of the RC-IGCT, the motivation to improve this aspect of the diode reverse recovery is twofold, i.e., both the GCT and the diode components benefit from reduced operating losses due to reduced thickness.

[0006] From EP 3029737 A1 a backside hole injection diode is known. By more effectively ensuring the effect of hole injection from the backside of the semiconductor substrate, the performance of the semiconductor device is improved. An anode P-type layer formed on the main surface of the semiconductor substrate and a backside N-type layer formed on the backside of the semiconductor substrate are formed. +In a diode having a PN junction shape including a back surface P + The mold layer is formed on the back surface and the front surface P + The mold layer is the back P + This is formed on the peripheral surface directly above the mold layer, which promotes the effect of hole injection from the backside.

[0007] JP 06-29558A describes a static induction diode, which has a planar structure suitable for obtaining a high breakdown voltage by setting a planar structure in one or both of the anode and cathode regions using the static induction effect, and also by setting a lifetime distribution in the high resistance layer. The lifetime in the vicinity of the anode side and the cathode side is set long, and the lifetime distribution is set to gradually shorten as the distance from these regions increases. The lifetime at positions deep from the anode side and the cathode side is set relatively short so that the reduction of residual carriers is accelerated. Therefore, in addition to the effect of static induction short circuit, it is possible to realize a high-voltage diode with almost no reverse recovery charge and a short reverse recovery time.

[0008] DE 36 31 136 A1 describes a method for implementing the concept of field charge extraction (FCE), i.e., a diode cathode short circuit or P + By introducing a region, a diode with a relatively thin silicon layer and no snap-off is known. These P + The region injects holes and supports current during the tail (end) phase of the reverse recovery period, thus enhancing the softness of the device in the diode mode of operation without significantly affecting the device performance in the GCT mode of operation. However, the safe operating area (SOA) or maximum controllable turn-off current (MCC) capability of the device in the GCT mode may be less in the RC-IGCT with integrated power diode with FCE design as n-buffer peak doping concentration, which is usually due to the absence of diode cathode short circuit or the presence of p-type junctions on the diode cathode side in the FCE design. +Less area than conventional diode designs (<1·10 16 cm -3 ) Also, these structures with FCE design may have higher leakage current due to the gain of the parasitic PNP transistor increasing at low buffer doping. In addition, FCE design is more sensitive to temperature variations in the device. The FCE effect is more pronounced, i.e., P + Carrier injection from the region is higher at higher temperatures, resulting in increased reverse recovery losses. The strong temperature dependence of the FCE design leads to large differences in the technology curves at Tjmax and room temperature as a result of the long tail currents of the FCE components.

[0009] Tsukuda et al., "Dynamic Punch-Through Design of High-Voltage Diode for Suppression of Waveform Oscillation and Switching Loss," Proceedings of the 21st International Symposium on Power Semiconductor Devices & IC's, pp. 128-131, 2009, discloses a power diode design in which a silicon oxide region is embedded in an n-type cathode layer to cover a portion of the cathode electrode. It is described that such a power diode design can suppress current and voltage fluctuations during reverse recovery.

[0010] Pfaffenlehner et al., “Optimization of Diodes using SPEED concept and CIBH,” Proceedings of the 23rd rd The International Symposium on Power Semiconductor Devices & IC's, pp108-111, 2011, describes a freewheeling diode with improved surge current robustness. In this freewheeling diode according to the SPEED concept, the anode is a highly doped p-type diode positioned inside a lightly doped, p-type emitter region.+ At low current densities, hole injection occurs primarily from both p-doped regions, but mainly from the p + However, this diode using the SPEED concept can exhibit snappy reverse recovery when the device thickness is small. Summary of the Invention [Problem to be solved by the invention]

[0011] Summary of the Invention In view of the above-mentioned deficiencies in the prior art, it is an object of the present invention to provide a power diode that exhibits fast and soft recovery (i.e., non-snappy recovery) while reducing conduction and switching losses over a wide temperature range. [Means for solving the problem]

[0012] This object is achieved by a power diode according to claim 1. The power diode according to claim 1 comprises an anode electrode layer, a cathode electrode layer, and a number of diode cells arranged between the anode electrode layer and the cathode electrode layer. The direction from the anode electrode layer to the cathode electrode layer defines a vertical direction (the vertical direction is the direction of the shortest line connecting the anode electrode layer and the cathode electrode layer). Each diode cell comprises a first conductivity type anode layer in direct contact with the anode electrode layer, a second anode layer of the first conductivity type having a lower doping concentration than the first anode layer and separated from the anode electrode layer by the first anode layer, a drift layer of the second conductivity type forming a p-n junction with the second anode layer, a cathode layer of the second conductivity type in direct contact with the cathode electrode layer, and a cathode-side segmentation layer in direct contact with the cathode electrode layer, the second conductivity type being different from the first conductivity type. Here, the cathode layer has a higher doping concentration than the drift layer. The material of the cathode-side segmentation layer is a semiconductor or insulating material of the first conductivity type. When the cathode-side segmentation layer is a semiconductor of the first conductivity type, the integrated doping content integrated along a direction perpendicular to the second main surface is 2·10 13 cm -2 The first anode layer extends vertically from the anode electrode layer to a first depth, and the second anode layer extends vertically from the first anode layer to a second depth greater than the first depth. A horizontal cross section of each diode cell along a horizontal plane perpendicular to the vertical direction at the third depth includes a first region where the horizontal plane intersects with the second anode layer and a second region where the horizontal plane intersects with the drift layer in each diode cell, the first depth being smaller than the third depth, and the third depth being smaller than the second depth. The drift layer may have a constant doping concentration, for example. Here, the constant doping concentration means that the doping concentration is approximately uniform throughout the drift layer, but does not exclude the possibility that the doping concentration may vary by about 1 to 5 times within the drift layer for manufacturing reasons.

[0013] This design of the power diode of the present invention has a segmented structure on the anode side and the cathode side. Specifically, the design has a segmented second anode layer on the anode side and a cathode layer that is segmented by a segmentation layer on the cathode side. The segmented structure of the power diode of the present invention improves the reverse recovery of the power diode for a minimum thickness of the power diode (throughout this specification, the thickness of the power diode refers to the shortest distance between the anode electrode layer and the cathode electrode layer). Compared to FCE diodes, which rely on hole injection during the tail (end) phase of the reverse recovery period, the characteristics of the power diode of the present invention are less temperature dependent. The soft reverse recovery behavior (i.e., a significantly reduced voltage peak during reverse recovery, as will be explained in more detail later with reference to FIG. 6) is due to the fact that, contrary to FCE diodes, the P + This is not the result of carrier injection from the regions, but rather the result of accumulated charge remaining in the unsegmented regions.

[0014] In a first exemplary embodiment, in at least one vertical cross section perpendicular to a horizontal plane, the second anode layers of each pair of adjacent diode cells are laterally separated from one another by the drift layers of the respective pairs of adjacent diode cells. Throughout this specification, when a first region (or layer) is separated from a second region (or layer) by a third region (or layer), this is intended to mean that there is no direct contact between the first region and the second region, but that there is a continuous path from the first region to the second region via the third region without passing through another region.

[0015] In this first exemplary embodiment, in at least one vertical cross section, the cathode-side segmentation layers of each pair of adjacent diode cells may be laterally separated from each other by the cathode layers of the second conductivity type of the respective pairs of adjacent diode cells, which can further improve reverse recovery of the power diode.

[0016] In the first exemplary embodiment, in at least one vertical cross section, the shortest lateral distance L between the second anode layers of each pair of adjacent diode cells d1 is 0.3 L p1 ~L p1 and L p1 is the minimum lateral width of the cathode-side segmentation layer in each of a pair of adjacent diode cells.

[0017] In the first exemplary embodiment, in at least one vertical cross section, the shortest lateral distance L between the cathode side segmentation layers of each pair of adjacent diode cells is n1 is 0.3 W n ~W n and W n is the vertical thickness of the diode cell.

[0018] In the first exemplary embodiment, in at least one vertical cross section, the lateral width L of the cathode-side segmentation layer p1 is 0.3 W n ~W n and W n is the vertical thickness of the diode cell.

[0019] In a second exemplary embodiment, in at least one vertical cross section perpendicular to the horizontal plane, a portion of the drift layer separates the second anode layer in each diode cell into two distinct regions extending laterally from the portion of the drift layer to an edge of the diode cell.

[0020] In this second exemplary embodiment, in at least one vertical cross section, the cathode layers of each pair of adjacent diode cells may be laterally separated from one another by the cathode-side segmentation layers of the respective pairs of adjacent diode cells.

[0021] In the second exemplary embodiment, in at least one vertical cross section, the shortest lateral distance L between two distinct regions of the second anode layer in each diode cell of each pair of adjacent diode cells is d2 is 0.3 L p2 ~L p2 and L p2 is the shortest lateral distance between the cathode layers of pairs of adjacent diode cells in at least one vertical cross section.

[0022] In the second exemplary embodiment, the lateral width L of the cathode layer of each diode cell in at least one vertical cross section is n2 is 0.3 W n ~W n and W n is the vertical thickness of the diode cell.

[0023] In the second exemplary embodiment, in at least one vertical cross section, the shortest lateral distance L between the two cathode-side segmentation layers of each pair of adjacent diode cells is p2 is 0.3 W n ~W n and W n is the vertical thickness of the diode cell.

[0024] In an exemplary embodiment, the multiple diode cells all have the same design or structure. The symmetry in the power diode of such an exemplary embodiment allows for mostly uniform device characteristics.

[0025] In an exemplary embodiment, the power diode has a honeycomb structure, and each diode cell has a hexagonal shape in horizontal cross section. Alternatively, each diode cell may have a stripe shape in horizontal cross section.

[0026] In an exemplary embodiment, the power diode comprises a second conductivity type buffer layer. The buffer layer has a doping concentration higher than that of the drift layer and lower than that of the cathode layer. The buffer layer is separated from the cathode electrode layer by the cathode layer and by the cathode-side segmentation layer. The buffer layer is separated from the first anode layer and from the second anode layer by the drift layer. In an exemplary embodiment, the buffer layer has a peak doping concentration of 1·10 16 cm -3 Higher or 2·10 16 cm -3 Higher or 4·10 16 cm -3 Contrary to the FCE design, the concept of the present invention is independent of the buffer design, i.e. the peak doping of the buffer is not limited to values ​​below a certain limit as in the case of the FCE design. The higher the peak doping of the buffer layer, the less sensitive the power diode of the present invention is to temperature fluctuations.

[0027] The power diode of the present invention may be integrated with a gate commutated thyristor (GCT) in a reverse conducting integrated gate commutated thyristor (RC-IGCT) device. The soft reverse recovery behavior of the device in diode mode is achieved with a minimum device thickness. Thus, the efficiency of the device can be improved while ensuring the soft recovery behavior in both diode and GCT operating modes.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, detailed embodiments of the present invention will be described with reference to the accompanying drawings. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 illustrates the time dependence of current and voltage during snap recovery of a conventional power diode. [Diagram 2] 1 is a top view showing power diodes according to the first, third and fourth embodiments. FIG. [Diagram 3]6 is a horizontal cross-section of nine diode cells included in the power diode according to the first embodiment taken along line II' in FIG. 5. [Figure 4] 6 is a horizontal cross-section of nine diode cells included in the power diode according to the first embodiment, taken along line II-II' in FIG. 5. [Diagram 5] 5 is a vertical cross-sectional view showing the power diode of the first embodiment taken along any one of lines AA', BB', and CC' in FIGS. 3 and 4, respectively. FIG. [Figure 6] FIG. 2 shows the time dependence of current and voltage during reverse recovery of a power diode according to the first embodiment and of a conventional (non-segmented) power diode. [Figure 7] 10 is a horizontal cross-sectional view showing a power diode according to a second embodiment taken along line II' in FIG. 9. [Figure 8] 10 is a horizontal cross-sectional view showing the power diode according to the second embodiment taken along line II' in FIG. 9. [Figure 9] 9A and 9B are vertical cross-sectional views showing a power diode according to a second embodiment taken along line EE' in each of FIGS. 7 and 8. [Figure 10] 5 is a cross-sectional view showing a power diode according to a third embodiment taken along any one of lines AA', BB', and CC' in FIGS. 3 and 4, respectively. FIG. [Figure 11] 14 is a horizontal cross-sectional view showing nine diode cells included in a power diode according to a fourth embodiment, taken along line II' in FIG. 13. [Figure 12] 14 is a horizontal cross-sectional view showing nine diode cells included in the power diode according to the fourth embodiment, taken along line II-II' in FIG. 13. [Figure 13] 13 is a vertical cross-sectional view showing a power diode according to a fourth embodiment taken along any one of lines AA', BB', and CC' in FIGS. 11 and 12, respectively. FIG. [Figure 14] FIG. 2 is a top view showing an RC-IGCT including a power diode according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The reference signs used in the drawings and their meanings are summarized in the reference sign list. Generally, similar elements have the same reference signs throughout this specification. The described embodiments are intended as examples and not to limit the scope of the invention. Similar reference signs with the same reference number but different numbers of dashes (e.g., reference signs 100, 100', 100'', 100''') refer to similar elements / entities in different embodiments. The description of a feature with respect to one of these similar reference signs shall apply to all elements / entities referenced by these reference signs unless otherwise stated.

[0031] Detailed Description of the Embodiments Hereinafter, a power diode 91 according to a first embodiment of the present invention will be described with reference to Fig. 2 to Fig. 6 (reference numbers in parentheses relate to other embodiments discussed in more detail later). Fig. 2 shows a top view of the power diode 91, Fig. 3 shows a horizontal cross-sectional view of nine diode cells 10 included in the power diode 91 along line I-I' in Fig. 5, Fig. 4 shows a horizontal cross-sectional view of nine diode cells 10 included in the power diode 91 along line II-II' in Fig. 5, and Fig. 5 shows a cross-sectional view of the power diode 91 along any one of lines A-A', B-B', and C-C' in Fig. 3 and Fig. 4 (in the power semiconductor device 91, the cross-section along line A-A' is the same as the cross-section along line B-B' and also the cross-section along line C-C').

[0032] The power diode 91 comprises a semiconductor wafer 100 having a first major surface 101 and a second major surface 102, as shown in FIG. 5. As can be seen from FIG. 2, the semiconductor wafer 100 comprises an active area laterally bounded by an edge termination region 5. Within this active area, the power diode 91 comprises a plurality of diode cells 10. All the diode cells 10 may have the same structure, illustratively a six-sided structure, except for the incomplete cell 110 immediately adjacent to the edge termination region 5. The six-sided structure is characterized by a hexagonal outline in top view (i.e., in a view in a direction perpendicular to the first major surface 101, which is the vertical direction). The diode cells 10 having the six-sided structure form a honeycomb pattern in top view, as shown in FIG. 2. The incomplete cell 110 immediately adjacent to the edge termination region 5 may have a different structure, including only a portion of the six-sided structure of the diode cell 10, as compared to the diode cells 10 not immediately adjacent to the edge termination region 5. The horizontal cross-sectional views of Figures 3 and 4 each show nine adjacent diode cells 10 having the same six-sided structure. In Figures 2 to 4, solid lines represent boundaries between adjacent diode cells 10, while thin dashed lines in Figure 3 indicate boundaries (i.e., outer or peripheral edges) of the p-type second anode layer 45 in the first horizontal plane K1 along line I-I' in Figure 5, and thin dashed lines in Figure 4 indicate boundaries of the cathode-side segmentation layer 67 in the second horizontal plane K2 along line II-II' in Figure 5. As shown in Figures 3 and 4, the boundaries of the p-type second anode layer 45 and the cathode-side segmentation layer 67 may be hexagonal, similar to the outline of the diode cell 10 in top view.

[0033] FIG. 5 is a cross-sectional view showing three adjacent (i.e., directly adjacent) diode cells 10 along any one of lines A-A', B-B', and C-C' in FIG. 3 and FIG. 4, respectively. As shown in FIG. 5, the power diode 91 includes an anode electrode layer 20 formed on a first main surface 101 of a semiconductor wafer 100 and a cathode electrode layer 30 formed on a second main surface 102 of the semiconductor wafer 100. The anode electrode layer 20 and the cathode electrode layer 30 cover at least a portion of each diode cell 10. Illustratively, the anode electrode layer 20 and the cathode electrode layer 30 may be formed as continuous metallization layers on the first main surface 101 and the second main surface 102, respectively. Thus, the diode cells 10 in the semiconductor wafer 100 are disposed between the anode electrode layer 20 and the cathode electrode layer 30. Each diode cell 10 includes a p-type first anode layer 40 in direct contact with the anode electrode layer 20, a second anode layer 45 separated from the anode electrode layer 20 by the first anode layer 40 (along any vertical straight line from the anode electrode layer 20 to the cathode electrode layer 30, where the vertical direction is the direction from the anode electrode 20 to the cathode electrode layer 30 along the shortest line connecting the anode electrode 20 and the cathode electrode layer 30), an n-type drift layer 50 forming a p-n junction with the second anode layer 45, an n-type buffer layer 65, an n-type cathode layer 60 in direct contact with the cathode electrode layer 30, and cathode side segmentation layers 67 alternating with the cathode side segmentation layers 67 in direct contact with the cathode electrode layer 30. The buffer layer 65 is separated from the first anode layer 40 and from the second anode layer 45 by the drift layer 50, and the buffer layer 65 is separated from the cathode electrode layer 30 by the cathode layer 60 and a cathode-side segmentation layer 67. The second anode layer 45 may be a well region in the drift layer 50.

[0034] The power diode 91 according to the first embodiment may be a silicon-based power diode, i.e., the semiconductor wafer 100 including the first anode layer 40, the second anode layer 45, the n-type drift layer 50, the n-type buffer layer 65, and the n-type cathode layer 60 may be made of silicon.

[0035] The first anode layer 40 in the power diode 91 according to the first embodiment is a continuous layer shared by the plurality of diode cells 10. In all of the plurality of diode cells 10, the first anode layer 40 may have a constant thickness d1 in a direction perpendicular to the first main surface 101, i.e., the first anode layer 40 extends vertically from the surface 101 of the semiconductor wafer 100 to a first depth d1. The second anode layer 45 extends vertically from the first anode layer 40 to a second depth d2.

[0036] The second anode layers 45 of each pair of adjacent diode cells 10 are laterally separated from each other by a portion of the n-type drift layer 50 of each pair of adjacent diode cells 10. More specifically, the second anode layer 45 of each diode cell 10 is laterally surrounded by a portion of the drift layer 50 and separated from the periphery of the diode cell 10, as shown in FIG. 3 and FIG. 5. Throughout this specification, the lateral direction refers to a direction parallel to the first principal surface 101 or the second principal surface 102. Thus, the second anode layer 45 of each diode cell 10 is laterally surrounded by a portion of the drift layer 50 in an orthogonal projection onto a plane parallel to the first principal surface 101 (or parallel to the second principal surface 102) and separated from the periphery of the diode cell 10. Thus, a horizontal cross-section through each diode cell 10 along a first horizontal plane K1 perpendicular to the vertical direction at a third depth d3 includes, in each diode cell 10, a first region where the first horizontal plane K1 intersects with the second anode layer 45 and a second region where the first horizontal plane K1 intersects with the drift layer 50, and the third depth d3 is a depth between the depth d1 to which the first anode layer 40 extends and the second depth d2 to which the second anode layer 45 extends.

[0037] In the vertical cross section shown in FIG. 5, the shortest lateral distance between the two second anode layers 45 of each pair of adjacent diode cells 10 is L d1 Due to the same structure or design of the diode cell 10 in the power diode 91, the distance between the anode layer 45 of the diode cell 10 and the periphery of the diode cell 10 is L d1 / 2, and the distance L between two adjacent second anode layers 45 in the cross section shown in FIG. d1 is the same for all pairs of immediately adjacent diode cells 10.

[0038] Therefore, the p-type region including the first anode layer 40 and the second anode layer 45 has a first depth d1 at the periphery of the diode cell 10 and a second depth d2 at the lateral center of the diode cell 10, the second depth d2 being greater than the first depth d1. Exemplarily, the thickness of the first anode layer 40 in a direction perpendicular to the first main surface 101 is within a range of 2 μm to 80 μm, i.e., the first depth d1 is within a range of 2 μm to 80 μm. Exemplarily, the thickness of the second anode layer 45 in a direction perpendicular to the first main surface 101 is within a range of 50 μm to 200 μm, i.e., the difference d2-d1 between the second depth d2 and the first depth d1 is within a range of 50 μm to 200 μm. The first anode layer 40 includes a first doping concentration of a first p-type dopant and the second anode layer 45 includes a second doping concentration of a second p-type dopant having a lower surface concentration than the first p-type dopant. Illustratively, the first p-type dopant is different from the second p-type dopant, e.g., the first p-type dopant may be boron (B) and the second p-type dopant may be aluminum (Al).

[0039] The peak doping concentration of the first anode layer 40 is higher than the peak doping concentration of the second anode layer 45. Illustratively, the peak doping concentration of the first anode layer 40 is 5·10 17 cm -3The peak doping concentration of the second anode layer 45 is 5·10 17 cm -3 Lower.

[0040] The drift layer 50 is shared by all the diode cells 10 and extends in the entire area of ​​each diode cell 10 in an orthogonal projection onto a plane parallel to the first main surface 101, i.e., the drift layer 50 extends laterally through each diode cell 10. The drift layer 50 forms a pn junction with the first anode layer 40 in an area where the first anode layer 40 does not overlap with the second anode layer 45 in an orthogonal projection onto a plane parallel to the first main surface 101. The drift layer 50 forms a pn junction with the second anode layer 45 in an area where the first anode layer 40 overlaps with the second anode layer 45 in an orthogonal projection onto a plane parallel to the first main surface 101. The thickness of the drift layer 50 depends on the voltage class of the power diode. The doping concentration of the drift layer 50 is relatively low (illustratively lower than the doping concentration of other layers such as the buffer layer 65), illustratively between 5 and 10 V depending on the voltage class of the power diode 91. 13 cm -3 The drift layer 50 may have a constant doping concentration. Here, a constant doping concentration means that the doping concentration is approximately uniform throughout the drift layer 50, but does not exclude the possibility that the doping concentration in the drift layer 50 may vary by about 1 to 5 times due to manufacturing reasons. The doping concentration of the buffer layer 65 is higher than that of the drift layer 50. Illustratively, the buffer layer 65 may have a doping concentration that increases toward the second main surface 102. The peak doping concentration of the buffer layer 65 is illustratively 1·10 16 cm -3 Higher, for example 2·10 16 cm -3 Higher, or more illustratively 4·10 16 cm -34, the cathode-side segmentation layer 67 is surrounded by the n-type cathode layer 60 and positioned in the laterally center of the diode cell 10. Thus, in top view (orthogonal projection onto the horizontal plane), the second anode layer 45 completely overlaps the cathode-side segmentation layer 67.

[0041] The material of the cathode-side segmentation layer 67 is either a p-type semiconductor or an electrically insulating material such as silicon oxide or oxynitride. The material of the cathode-side segmentation layer 67 can be any material that can inhibit electron emission from the buffer layer 65 to the drift region during diode conduction in the region adjacent to or above the cathode-side segmentation layer 67. The thickness of the cathode-side segmentation layer 67 is less than the thickness of the highly n-type doped cathode layer 60. The doping concentration of the cathode layer 60 is much higher than that of the buffer layer, e.g., 10 18 cm -3 It may be higher.

[0042] Contrary to known FCE diodes that require large hole injection to mitigate the current collapse as the electric field sweeps away the last charge close to the buffer (i.e., FCE diodes require a strong p-emitter), the segmented power diode 91 of the present invention does not require hole injection from the cathode side. Quite the contrary, the FCE effect, i.e., large hole injection, is undesirable because it is temperature dependent and gives the strongest effect at high temperatures where it is least needed. If the segmentation layer 67 is made of an insulating material, there is no hole injection. On the other hand, if the cathode side segmentation layer 67 is made of a p-type semiconductor material, it is desirable that the emitter efficiency is relatively low. The emitter efficiency of the p-type cathode side segmentation layer 67 depends essentially on the doping concentration of the cathode side segmentation layer 67 and its depth (i.e., the thickness in the direction perpendicular to the second major surface 102). The dose or accumulated doping content of the cathode-side segmentation layer 67 (accumulated along a direction perpendicular to the second major surface 102) is 2·10 13 cm -2 Less than, or for example, 1·10 13 cm -2 Less than, or more illustratively, 5·10 12 cm -2 The doping content is less than 1000 nm. Here, the doping content refers to the active dopant. The lower the p-type dosage, the lower the emitter efficiency of the p-type cathode side segmentation layer 67 for hole injection. The use of p-type material as the cathode segmentation layer 67 may facilitate the fabrication of the power diode compared to when an insulating material is used for the cathode segmentation layer 67.

[0043] Similar to the second anode layer 45, the cathode-side segmentation layer 67 is also segmented. The cathode-side segmentation layers 67 of each pair of adjacent diode cells 10 are laterally separated from one another by the n-type cathode layers 60 of the respective pairs of adjacent diode cells 10. More specifically, as can be seen from the vertical cross section shown in FIG. 5 and the horizontal cross section shown in FIG. 4, the cathode-side segmentation layer 67 of each diode cell 10 is surrounded laterally (i.e., in an orthogonal projection onto a plane parallel to the first principal surface 101 or the second principal surface 102) by a portion of the n-type cathode layer 60 and separated from the periphery of the diode cell 10. The shortest lateral distance between the two cathode-side segmentation layers 67 of each pair of adjacent diode cells 10 is defined as L in the vertical cross section shown in FIG. n1 Due to the sameness of the structure or design of the diode cell 10, the distance from the cathode side segmentation layer 67 of the diode cell 10 to the periphery of the diode cell 10 is referred to as L n1 The width of the cathode side segmentation layer 67 of the diode cell 10 is L / 2 in the vertical cross section shown in FIG. p1 It is called.

[0044] The width L of the cathode side segmentation layer 67 of each diode cell p1 and the shortest lateral distance L between the two cathode-side segmentation layers 67 of each pair of adjacent diode cells 10 n1 and the shortest lateral distance L between the second p-type layers 45 of each pair of adjacent diode cells 10. d1 and the thickness W of each diode cell 10 n1 The relationship (design rule) between may be as follows:

[0045] (i) 0.3 L p1 ≦L d1 ≦L p1 (ii) 0.3 W n1 ≦L n1 ≦W n1 (iii) 0.3 W n1 ≦L p1 ≦W n1 In Fig. 6, the time dependence of current and voltage during reverse recovery of the power diode 91 according to the first embodiment and, for comparison, of a conventional non-segmented power diode (conventional PiN diode) is shown. The solid lines in the graph of Fig. 6 correspond to the current and voltage of the power diode 91 according to the first embodiment, and the dashed lines correspond to the current and voltage of the conventional non-segmented power diode. As can be clearly seen from Fig. 6, the power diode 91 of the present invention exhibits a soft recovery behavior, whereas the conventional power diode exhibits a snappy reverse recovery behavior with a noticeable swing in voltage.

[0046] Hereinafter, the power diode 91' according to the second embodiment will be described with reference to FIG. 5 and FIG. 7 to FIG. 9. Due to many similarities between the power diode 91 according to the first embodiment and the power diode 91' according to the second embodiment, the features that are the same in the two power diodes 91 and 91' according to the first and second embodiments will not be repeated below. The description of the power diode 91' according to the second embodiment will focus on the differences between the first and second embodiments, whereas for all other features, please refer to the previous description of the first embodiment. In particular, the same reference symbols in the drawings refer to similar elements having the same properties or characteristics.

[0047] The power diode 91' according to the second embodiment differs from the power diode 91 according to the first embodiment in that the horizontal section of each diode cell 10' of the power diode 91' is striped. This can be seen from FIG. 7, which shows the three diode cells 10' of the power diode 91' in a first horizontal section along the line I-I' in FIGS. 5 and 9, respectively, and from FIG. 8, which shows these three diode cells 10' in a second horizontal section along the line II-II' in FIGS. 5 and 9, respectively. FIG. 5 shows a first vertical section of these three diode cells 10' along the line D-D' in FIGS. 7 and 8, respectively. Thus, the section of the diode cell 10' along the line D-D' in FIGS. 7 and 8 looks the same as the section of the diode cell 10 along any one of the lines A-A', B-B' and C-C' in FIGS. 3 and 4, respectively. In FIG. 5, the reference signs exclusively related to the second embodiment are shown in parentheses. Specifically, the cross section of the stripe-shaped p-type second anode layer 45' along line D-D' and the cross section of the stripe-shaped cathode-side segmentation layer 67' are the same as the cross sections of the second anode layer 45 and the cathode-side segmentation layer 67 along lines A-A', B-B' and C-C' in Figures 3 and 4, respectively.

[0048] In a second embodiment, a semiconductor wafer 100', the partial vertical cross section of which is shown in FIG. 5, has a first major surface 101'' and a second major surface 102'' and is similar to the semiconductor wafer 100 described above. It differs from the semiconductor wafer 100 described above only in the different shapes of the second anode layer 45', drift layer 50', buffer layer 65', cathode layer 60' and cathode segmentation layer 67' due to the previously described stripe shape of the diode cells 10'. Similar to the power diode 91, the power diode 91' may have four or more diode cells 10'. In addition, the power diode 91' may have an edge termination region 5 and an incomplete diode cell 110 adjacent to the edge termination region, as previously described with respect to the first embodiment. In the horizontal cross sections of Figures 7 and 8, the solid lines represent the boundaries between adjacent diode cells 10', while the thin dashed lines in Figure 7 indicate the boundaries of the second anode layer 45' in a first horizontal plane K1' along line I-I' in Figures 5 and 9, and the thin dashed lines in Figure 8 indicate the boundaries of the cathode-side segmentation layer 67' in a second horizontal plane K2' along line II-II' in Figures 5 and 9. In top view, i.e. in orthogonal projection onto a plane perpendicular to the vertical direction, as well as in the first and second horizontal cross sections shown in Figures 7 and 8, each of the second anode layer 45' and the cathode-side segmentation layer 67' has a stripe shape. The longitudinal axes of the striped second anode layer 45' and the striped cathode side segmentation layer 67' extend across the diode cell 10' along line E-E' in Figures 7 and 8, i.e., left to right in Figure 9. In the horizontal cross section of Figure 7, the striped regions of the drift layer 50' alternate with striped regions of the second anode layer 45'. Similarly, in the horizontal cross section shown in Figure 8, the striped regions of the cathode layer 60' alternate with striped regions of the cathode segmentation layer 67''.

[0049] As in the first embodiment described above, in the vertical cross section shown in FIG. 5, the shortest lateral distance L between the two second anode layers 45′ of each pair of adjacent diode cells 10′ (each adjacent in a direction parallel to the line D-D′ in FIGS. 7 and 8) is d1 , the shortest lateral distance L between the two cathode-side segmentation layers 67′ of each pair of adjacent diode cells 10′ n1 , the lateral width L of each cathode-side segmentation layer 67′ in a direction parallel to the line D-D′ in FIG. 7 and FIG. 8, p1 , and the thickness W of each diode cell 10′ n may, for example, satisfy the design rules (i) to (iii) shown above.

[0050] A power diode 91'' according to a third embodiment will be described below with reference to Figs. 2 to 4 and 10. Here, Fig. 3 shows a horizontal section of the diode cells 10'' of the power diode 91'' along the line I-I' in Fig. 10 (along the plane K1'' in Fig. 10), and Fig. 4 shows another horizontal section of these diode cells 10'' along the line II-II' in Fig. 10 (i.e. along the plane K2'' in Fig. 10). Due to the many similarities between the power diode 91'' according to the first embodiment and the power diode 91'' according to the third embodiment, the features that are the same in the two power diodes 91 and 91'' will not be repeated below in their entirety. The description of the power diode 91'' according to the third embodiment focuses on the differences between the first and third embodiments, whereas for all other features, reference should be made to the previous description of the first embodiment. In particular, the same reference symbols in the drawings refer to similar elements having the same properties or characteristics.

[0051] The only difference between the power diode 91'' of the third embodiment and the power diode 91 of the first embodiment described above with reference to Figs. 2 to 5 is the shape of the p-type first anode layer 40'' and the p-type second anode layer 45''. In the third embodiment, the first anode layer 40'' is configured as a well region in the second anode layer 45''. The top view of the power diode 91'' of the third embodiment is the same as the top view of the power diode 91 of the first embodiment shown in Fig. 2. In Figs. 2, 3 and 4, the reference numerals exclusively related to the third embodiment are shown in parentheses. Fig. 10 shows a cross section of the power diode 91'' along any one of the lines A-A', B-B' and C-C' in Figs. 3 and 4. Due to the deformed shapes of the first anode layer 40″ and the second anode layer 45″, the drift layer 50″ differs from the drift layer 50 in the first embodiment in that it is not in direct contact with the first anode layer 40″ but is separated from the first anode layer 40″ by the second anode layer 45″. In the third embodiment, a semiconductor wafer 100″ having a first main surface 101″ and a second main surface 102″ shown in FIG. 10 is similar to the semiconductor wafer 100 described above. The only difference between it and the semiconductor wafer 100 described above is in the structure of the first anode layer 40″, the second anode layer 45″ and the drift layer 50″. Contrary to the drift layer 50 in the first embodiment, in the third embodiment, the drift layer 50″ extends to the first main surface 101″ of the semiconductor wafer 100″. Similarly, the second anode layer 45'' extends to the first major surface 101''. An insulating layer 80 provided on the first major surface 101'' and covering the drift layer 50'' prevents the anode electrode 20 from directly contacting the drift layer 50'' and the second anode layer 45''.

[0052] Hereinafter, the power diode 91''' according to the fourth embodiment will be described with reference to FIG. 2 and FIG. 11 to FIG. 13. Due to many similarities between the power diode 91 according to the first embodiment and the power diode 91''' according to the fourth embodiment, the features that are the same in the two power diodes 91 and 91''' according to the first and fourth embodiments will not be repeated in full below. The description of the power diode 91''' will focus on the differences between the first and fourth embodiments, whereas for all other features, reference should be made to the previous description of the first embodiment. In particular, identical or similar reference symbols in the drawings refer to similar elements having the same properties or characteristics.

[0053] 2 shows the power diode 91''' in a top view. This means that the top view of the power diode 91''' is the same as the top view of the power diode 91 according to the first embodiment. FIG. 11 is a first horizontal cross-sectional view of nine diode cells 10''' included in a power diode 91''' along line I-I' in FIG. 13 (i.e., along horizontal plane K1''' in FIG. 13), FIG. 12 is a second horizontal cross-sectional view of nine diode cells 10''' included in a power diode 91''' along line II-II' in FIG. 13 (i.e., along horizontal plane K2''' in FIG. 13), and FIG. 13 shows a cross-sectional view of a power diode 91 along any one of lines A-A', B-B' and C-C' in FIG. 11 and FIG. 12, respectively (in the power semiconductor device 91''', the cross-section along line A-A' in FIG. 11 and FIG. 12 is the same as the cross-section along line B-B' and also the cross-section along line C-C').

[0054] Power diode 91''' differs from power diode 91 in that second anode layer 45''' is not located in the lateral center of each diode cell 10''', as in the first embodiment, but is located along the outer boundary of each diode cell 10''' in an orthogonal projection onto a horizontal plane perpendicular to the vertical direction. Thus, in a vertical cross section perpendicular to first horizontal plane K1'', as shown in FIG. 13, a portion of drift layer 50''' separates second anode layer 45''' in each diode cell 10''' laterally into two distinct regions each extending laterally from the portion of drift layer 50''' to an edge of diode cell 10'''. In the first horizontal cross section shown in FIG. 11, the portion of the drift layer 50''' described above in each diode cell 10''' is an island-like region surrounded by the region where the first horizontal plane K1''' intersects with the second anode layer 45''' (where the first horizontal plane K1''' intersects with that portion of the drift layer 50''').

[0055] The power diode 91''' also differs from the power diode 91 in that the cathode layer 60''' is not located in the lateral center of each diode cell 10'''' as in the first embodiment, but is located along the outer boundary of each diode cell 10''' in the horizontal cross section shown in FIG. 12 and in the orthogonal projection onto a horizontal plane perpendicular to the vertical direction. In the horizontal cross section shown in FIG. 12, the cathode segmentation layer 67''' in each diode cell 10''' is an island-like region surrounded by the region where the second horizontal plane K2'''' intersects with the cathode layer 60'''' (where the second horizontal plane K2'''' intersects with the segmentation layer 67'''). In the vertical cross section perpendicular to the first horizontal plane K1'''', the cathode layers 60''' of each pair of adjacent diode cells 10''' are laterally separated from each other by the cathode-side segmentation layers 67''' of the respective pairs of adjacent diode cells 10'''.

[0056] In a vertical cross section as shown in FIG. 13, the shortest lateral distance L between two separate regions of the second anode layer 45′″ in each diode cell 10′″ of each pair of adjacent diode cells 10′″ is d2 is 0.3 L p2 ~L p2 Within the range of L p2 is the shortest lateral distance between a pair of cathode layers 60''' of adjacent diode cells 10'''. This characteristic corresponds to the above-mentioned design rule (i) in the first embodiment.

[0057] In addition, in the vertical cross section shown in FIG. 13, the width L n2 is 0.3 W n ~W n Within the range of W n is the vertical thickness of the diode cell 10'''. This characteristic corresponds to design rule (ii) above.

[0058] Finally, in a vertical cross section as shown in FIG. 13, the shortest lateral distance L between the two cathode layers 60''' of each pair of adjacent diode cells 10''' is p2 is 0.3 W n ~W n Within the range of W n is the vertical thickness of the diode cell 10'''. This characteristic corresponds to design rule (iii) above.

[0059] In this fourth embodiment, semiconductor wafer 100''', the partial vertical cross section of which is shown in FIG. 13, has a first major surface 101''' and a second major surface 102''' and is similar to the previously described semiconductor wafer 100. It differs from the previously described semiconductor wafer 100 only in the different shapes and arrangements of second anode layer 45''', drift layer 50''', buffer layer 65''', cathode layer 60''' and cathode segmentation layer 67''', which result from the previously described structure of diode cell 10'''.

[0060] FIG. 14 shows a top view of a reverse conducting integrated gate commutated thyristor (RC-IGCT) 90 according to an embodiment of the present invention. The RC-IGCT 90 comprises a gate commutated thyristor (GCT) 93 and a power diode 910 (functioning as a free-wheeling diode) monolithically integrated on a single wafer. Within the wafer, the GCT 93 is separated from the power diode 910 by an isolation region 92. As shown in FIG. 9, the GCT 93 comprises a number of GCT fingers arranged in two rings and surrounding the power diode 91'''. Along the periphery of the wafer, the RC-IGCT has a gate contact 94 for controlling the GCT 93, as shown in FIG. 9. Such a design of the RC-IGCT is well known to those skilled in the art. Therefore, a detailed description of the structure of the GCT 93 and the isolation region 92 will be omitted. The only difference between the RC-IGCT 90 according to an embodiment of the present invention and such known RC-IGCTs is that the power diode 910 is a power diode according to the present invention without the edge termination region 5, e.g., configured as previously described for any one of the power diodes 91, 91', 91'' or 91'''' described above. It is noted that the novel diode design in the RC-IGCT 90 can be manufactured without the need for additional masks, as compared to known manufacturing methods for RC-IGCTs having a conventional PiN power diode as a freewheeling diode.

[0061] It will be apparent to those skilled in the art that modifications can be made to the above-described embodiments without departing from the scope of the invention, which is defined by the appended claims.

[0062] In the above-described first to third embodiments of the power diode, the shape of the diode cells 10, 10'', and 10''' is described as being hexagonal in top view, and the shape of the diode cell 10' is described as being striped. However, the diode cells 10, 10', 10'', 10''' may have any other shape, such as a square or a triangle, in top view, i.e., in horizontal projection onto a plane parallel to the first main surface 101, 101', 101'', 101''''. Similarly, the outline of the second anode layer 45, 45', 45'', 45''' in the power diode 91, 91', 91'', 91'''' may have another shape other than a hexagon or a stripe, such as a square, a triangle, any other polygon or a circle in top view. In addition, in the first to third embodiments, the outer shape of the diode cells 10, 10', 10'', 10''' is described as being the same as the outer shape of the second anode layer 45, 45', 45'', 45''' in the top view (either hexagonal or striped shape), but the outer shape of the diode cells 10, 10', 10'', 10''' in the power diodes 91, 91', 91'', 91'''' of the present invention is not necessarily the same as the outer shape of the second anode layer 45, 45', 45'', 45'''' in the top view.

[0063] In the above-described embodiment, the diode cells 10, 10', 10'', 10''' in one power diode 91, 91', 91'', 91''' all had the same design, except for the incomplete diode cell 110 that is immediately adjacent to the edge termination region 5 in the RC-IGCT 90 or adjacent to the isolation region 92. However, the power diode of the present invention may use diode cells having two or more different designs, for example diode cells of different sizes, among the multiple diode cells.

[0064] In the RC-IGCT, the gate contact 94 is described as being positioned at the periphery of the device surrounding the GCT 93. However, the gate contact 94 may be positioned in another location, such as between two rings of thyristor fingers. The GCT 93 may also have any other arrangement of GCT fingers, and in particular any other number of rings in which the thyristor fingers are arranged.

[0065] In the above embodiments, the power diode of the present invention is described as being either a discrete device as in the first to third embodiments or incorporated in an RC-IGCT. However, the power diode of the present invention may be used or integrated in any other power device, such as, for example, in combination with an Insulated Gate Bipolar Transistor (IGBT) and a Gate Turn-Off Thyristor (GTO) as a free-wheeling diode, a snubber diode and a clamp diode.

[0066] In the above-mentioned embodiment, the power diode of the present invention is described as including a buffer layer, i.e., having a punch-through (PT) structure. However, the above-mentioned embodiment can be modified to have no buffer layer, i.e., to have a non-punch-through (NPT) structure.

[0067] The embodiments are described with particular conductivity types. In each of the above embodiments, the conductivity types of the semiconductor layers may be swapped such that all layers described as p-type layers become n-type layers, and all layers described as n-type layers become p-type layers.

[0068] It should be noted that the term "comprising" does not exclude other elements or steps, and that the indefinite articles "a" or "an" meaning "single" do not exclude a plurality. Also, elements described in association with different embodiments may be combined. [Explanation of symbols]

[0069] Explanation of symbols 5. Edge Termination 10,10',10'',10'' Diode Cell 20 Anode electrode layer 30 Cathode electrode layer 40,40'' First anode layer 45,45',45'',45'''' Second anode layer 50,50',50'',50'' drift layer 60,60',60''' Cathode layer 67,67',67'' Cathode side segmentation layer 80 Insulating layer 90 RC-IGCT 91,91′,91'',91'''',910 Power diode 92 Separation area 93 Gate commutated thyristor (GCT) 94 Gate Contact 100,100',100'',100'''' Semiconductor wafers 101,101',101'',101'''' First main surface 102,102',102'',102'''' Second main surface 110 Incomplete Cell K1,K1',K1'',K1'' First horizontal plane K2,K2',K2'',K2'' Second horizontal plane L d1 The shortest lateral distance (between the second anode layers of two adjacent diode cells) L n1 The shortest lateral distance (between the cathode-side segmentation layers of two adjacent diode cells) L p1 Width (of cathode side segmentation layer) L d2 The shortest lateral distance (between two distinct regions of the second anode layer) L n2 Width (of cathode side segmentation layer) L p2The shortest lateral distance (between the cathode layers of two adjacent diode cells) W n The vertical thickness of the diode cell.

Claims

1. A power diode comprising an anode electrode layer (20) formed on a first main surface (101) of a semiconductor wafer (100), a cathode electrode layer (30) formed on a second main surface (102) of the semiconductor wafer (100), and a plurality of diode cells (10; 10'; 10"; 10"') disposed between the anode electrode layer (20) and the cathode electrode layer (30), wherein a direction from the anode electrode layer (20) to the cathode electrode layer (30) defines a vertical direction, and each diode cell (10; 10'; 10"; 10"') has: a first anode layer (40; 40'') of a first conductivity type in direct contact with the anode electrode layer (20), extending along all parts of the anode electrode layer (20) in a horizontal direction perpendicular to the vertical direction, and extending vertically from the anode electrode layer to a first depth (d1); a second anode layer (45; 45'; 45"; 45"') of a first conductivity type having a lower doping concentration than said first anode layer (40; 40") and separated from all of said portions of said anode electrode layer (20) by said first anode layer (40; 40"), said second anode layer extending vertically from said first anode layer to a second depth (d2) greater than said first depth (d1); a drift layer (50; 50'; 50"; 50'") of a second conductivity type forming a pn junction with the second anode layer (45; 45'; 45"; 45"'), the second conductivity type being different from the first conductivity type; and a cathode layer (60; 60'; 60''') of a second conductivity type in direct contact with the cathode electrode layer (30), the cathode layer (60; 60'; 60''') having a higher doping concentration than the drift layer (50; 50'; 50''; 50'''); a cathode-side segmentation layer (67; 67'; 67''') in direct contact with said cathode electrode layer (30), a horizontal cross section through each diode cell (10; 10'; 10"; 10'") along a horizontal plane perpendicular to the vertical direction at a third depth (d3) includes, in each diode cell (10; 10'; 10"; 10"'), a first region where the horizontal plane (K1; K1'; K1"; K1"') intersects with the second anode layer (45; 45'; 45"; 45"') and a second region where the horizontal plane (K1; K1'; K1"; K1"') intersects with the drift layer (50; 50'; 50"; 50"'), wherein the first depth (d1) is smaller than the third depth (d3) and the third depth (d3) is smaller than the second depth (d2); The material of the cathode-side segmentation layer (67; 67'; 67''') is a semiconductor of a first conductivity type and has an integrated doping content, integrated along a direction perpendicular to the second main surface (102), of 2.10 １３ cm －２ or the material of said cathode side segmentation layer (67; 67'; 67''') is an insulating material.

2. 2. The power diode of claim 1, wherein in at least one vertical cross section perpendicular to the horizontal plane (K1;K1';K1";K1"'), the second anode layers (45;45';45") of each pair of adjacent diode cells (10;10';10") are laterally separated from one another by the drift layers (50;50") of respective pairs of adjacent diode cells (10;10';10").

3. 3. The power diode of claim 2, wherein in the at least one vertical cross section, the cathode-side segmentation layers (67; 67') of each pair of adjacent diode cells (10; 10'; 10'') are laterally separated from one another by the cathode layers (60) of the respective pairs of adjacent diode cells (10; 10'; 10'').

4. In said at least one vertical cross section, the shortest lateral distance L between the second anode layers (45; 45'; 45'') of each pair of adjacent diode cells (10; 10'; 10'') ｄ１ is 0.3 L ｐ１ ~L ｐ１ In the range of L ｐ１ 4. The power diode according to claim 2 or 3, wherein x is the lateral width of each cathode-side segmentation layer (67; 67') of the pair of adjacent diode cells (10; 10'; 10'') in the at least one vertical cross-section.

5. In said at least one vertical cross section, the shortest lateral distance L between each pair of cathode-side segmentation layers (67; 67') of adjacent diode cells (10; 10'; 10'') ｎ１ is 0.3 W ｎ ~W ｎ Within the range of W ｎ A power diode according to any one of claims 2 to 4, wherein x is the vertical thickness of the diode cell (10; 10'; 10'').

6. In the at least one vertical cross section, the lateral width L of the cathode-side segmentation layer (67; 67') ｐ１ is 0.3 W ｎ ~W ｎ Within the range of W ｎ A power diode according to any one of claims 2 to 5, wherein x is the vertical thickness of the diode cell (10; 10'; 10'').

7. 2. The power diode of claim 1, wherein in at least one vertical cross section perpendicular to the horizontal plane (K1; K1'; K1"; K1"'), the portion of the drift layer separates the second anode layer (45'") in each diode cell (10'") into two distinct regions extending laterally from the portion of the drift layer to an edge of the diode cell (10'").

8. 8. The power diode of claim 7, wherein in the at least one vertical cross section, the cathode layers (60''') of each pair of adjacent diode cells (10''') are laterally separated from one another by a cathode-side segmentation layer (67''') of each pair of adjacent diode cells (10''').

9. In the at least one vertical cross section, the shortest lateral distance L between two separate regions of the second anode layer (45''') in each diode cell (10''') of each pair of adjacent diode cells (10'''). ｄ２ is 0.3 L ｐ２ ~L ｐ２ In the range of L ｐ２ 9. The power diode of claim 7 or 8, wherein: ##EQU1## is the shortest lateral distance between the cathode layers (60''') of a pair of adjacent diode cells (10''') in the at least one vertical cross section.

10. In the at least one vertical cross section, the lateral width L of the cathode layer (60''') of each diode cell (10''') ｎ２ is 0.3 W ｎ ~W ｎ Within the range of W ｎ A power diode according to any one of claims 7 to 9, wherein x is the vertical thickness of the diode cell (10''').

11. In the at least one vertical cross section, the shortest lateral distance L between the two cathode layers (60'') of each pair of adjacent diode cells (10'') ｐ２ is 0.3 W ｎ ~W ｎ Within the range of W ｎ A power diode according to any one of claims 7 to 10, wherein x is the vertical thickness of the diode cell (10''').

12. 12. A power diode according to any one of claims 1 to 11, wherein all diode cells (10; 10'; 10"; 10'") of the plurality of diode cells (10; 10'; 10"; 10"') have an identical structure.

13. 13. A power diode according to any one of claims 1 to 12, wherein each diode cell (10; 10'; 10''; 10''') has a hexagonal shape or each diode cell (10') has a stripe shape in horizontal cross section.

14. a buffer layer (65) of a second conductivity type; the buffer layer (65) has a higher doping concentration than the drift layer (50; 50'; 50"; 50"'); the cathode layer (60) has a doping concentration higher than that of the buffer layer (65); the buffer layer (65) is separated from the cathode electrode layer (30) by the cathode layer (60; 60'; 60''') and by the cathode-side segmentation layer (67; 67'; 67'''); and 14. A power diode according to any one of claims 1 to 13, wherein the buffer layer (65) is separated from the first anode layer (40; 40'') and from the second anode layer (45; 45'; 45''; 45''') by the drift layer (50; 50'; 50''; 50''').

15. A reverse conducting integrated gate commutated thyristor device comprising a gate commutated thyristor (93) and a power diode (91; 91'; 91''; 91''') according to any one of claims 1 to 14.

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