JP2012049258A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device whose ability to tolerate surges can be increased.SOLUTION: The semiconductor device adopts a configuration composed of parallel parts 30 having plural pieces of field plates 17b to 17e disposed from a cell part toward the outer periphery side of an outer periphery pressure part, with the parallel direction alongside the contour of the cell part being a longer direction, and coupling parts 33 extended in an oblique direction from the respective parallel parts 30, wherein the parallel parts 30 and the coupling parts 33 are alternately connected to be formed step-wise in one direction. The parallel parts 30 include a group of Zener diodes 18a to 18e made up of plural stages of a pair of Zener diodes which are connected in series in the opposite direction, in which formation the number of stages of a pair of Zener diodes provided in each of the disposed plural pieces of parallel parts 30 can be increased from a side close to the cell part toward the outer periphery of the cell part.

Description

  The present invention relates to a semiconductor device including a semiconductor element such as a MOSFET or an insulated gate field effect bipolar transistor (hereinafter referred to as IGBT).

  A semiconductor switching element such as an IGBT used for an igniter or the like receives an input signal and generates a high voltage on the secondary side. Since such a semiconductor switching element is used at a high voltage, a high voltage rebound may occur instantaneously in a short time such as an L load surge in the element itself, and the structure should be able to withstand it. Is required. There are various modes of surge, and a voltage of several kV is applied to the semiconductor switching element in several μsec to several nsec.

  Therefore, in order to obtain a surge withstand capability, a structure has been proposed in which a surge is not concentrated on a part of a main cell in which an on / off operation is normally performed. For example, a structure has been proposed in which a surge is removed by clamping a voltage between an IGBT gate and collector or a gate and an emitter with a Zener diode to soft-on a main cell, and particularly withstand high-speed and high-voltage surges. Patent Document 1 proposes a structure in which a surge is removed from the main cell at the outer peripheral pressure resistant portion.

  Specifically, Patent Document 1 proposes a semiconductor device provided with a field plate incorporating a Zener diode group. In this semiconductor device, a field plate is provided so as to surround a cell portion in which a semiconductor switching element such as a MOSFET or an IGBT is formed, and the operating resistance of the Zener diode group is reduced when a surge is applied, and at the time of breakdown. The current density of the outer peripheral withstand voltage portion at the corner portion is reduced.

  The field plate includes a parallel portion having a longitudinal direction (hereinafter, simply referred to as a longitudinal direction) parallel to the direction along the outline of the cell portion in the outer peripheral pressure-resistant portion surrounding the cell portion, and is long with respect to the parallel portion. A plurality of Zener diodes are formed along the direction. A plurality of parallel portions are arranged in parallel in the direction from the cell portion toward the outer periphery, that is, in a multiple manner, and each parallel portion is adjacent to each other in the outer peripheral direction via a connecting portion extending obliquely from each parallel portion. It is connected with respect to the parallel part which adjoins in the longitudinal direction of the parallel part which exists. For this reason, from the parallel part (parallel part on the most cell part side) electrically connected to the gate electrode of the semiconductor element formed in the cell part to the parallel part (parallel part on the most outer peripheral side) connected to the semiconductor substrate. Up to this point, each parallel part is arranged in a staircase pattern. Thus, for example, the gate-collector of the IGBT is clamped to the breakdown voltage of the Zener diode group, and a voltage exceeding the breakdown voltage is not applied between the gate-collector of the IGBT.

  In the semiconductor device having such a structure, the field plate plays a role of defining the gate-collector clamp voltage by the sum of breakdown voltages of the Zener diode groups included in the parallel portions connected in a staircase pattern, and in the outer circumferential direction. A plurality of parallel portions arranged in parallel has a role of determining the breakdown voltage of the bulk, that is, the entire silicon portion in the semiconductor device. The semiconductor device disclosed in Patent Document 1 has a structure in which the same number of Zener diodes are arranged for each of a plurality of parallel portions arranged in parallel in the outer peripheral direction.

JP 2003-174165 A

  However, the demand for semiconductor switching elements has increased due to the high efficiency of igniters and the like, and the required surge withstand tends to increase. For this reason, in the surge resistant design in the semiconductor device as shown in the above-mentioned Patent Document 1, there is a possibility that the deviation of the electric field strength partially occurs and the tolerance specification cannot be satisfied.

  An object of this invention is to provide the semiconductor device which can enlarge surge tolerance further in view of the said point.

  In order to achieve the above object, according to the first aspect of the present invention, the outer peripheral withstand voltage portion includes the outermost peripheral plate (17g) electrically connected to the semiconductor substrate and the gate electrode formed in the cell portion. (7) and a plurality of conductive field plates (17) including the innermost peripheral plate (17a) electrically connected are formed, and the plurality of field plates are formed on the outline of the cell portion. A plurality of parallel portions (30) arranged side by side from the cell portion toward the outer peripheral side of the outer peripheral pressure-resistant portion with the parallel direction along the longitudinal direction, and a connecting portion (33) extending obliquely from each of the parallel portions ), And the parallel portion and the connecting portion are alternately connected to form a stepped shape in one direction. In the parallel portion, the Zener diode is connected in series in the reverse direction. Multiple diode pairs The formed Zener diode groups (18a to 18e) are provided, and the number of stages of Zener diode pairs provided in each of the parallel parts arranged in a plurality is arranged from the side closer to the cell part toward the outer periphery of the cell part. It is characterized by being increased.

  Thus, if the number of stages of the Zener diode pair in the parallel part is increased from the cell part side toward the outer periphery, the surge resistance can be increased.

  The semiconductor device having such a structure can be applied to, for example, driving an igniter to which a high voltage is applied as described in claims 2 to 5.

  In that case, as described in claim 2, the number of stages of Zener diode pairs provided in the two parallel portions (30a, 30b) located closest to the cell portion among the plurality of parallel portions arranged side by side The stage ratio divided by the total number of Zener diode pairs formed with respect to the parallel part arranged in a plurality of stages, which is the difference between the stages, is 9% or less when used in a 500V igniter, When used in a 600V igniter, 7.5% or less is preferable, and when used in a 700V igniter, 6% or less is preferable.

  Thus, the stage ratio is set according to the applied voltage of the igniter. The stage ratio is 9% or less for the 500V system, the stage ratio is 7.5% or less for the 600V system, and the stage ratio for the 700V system. By making the value 6% or less, a large surge resistance can be obtained.

  Further, as described in claim 3 or 4, the plurality of Zener diode pairs provided in the two parallel portions (30a, 30b) positioned closest to the cell portion among the parallel portions arranged in a line. The difference in the number of stages, which is the difference in the number of stages, is 9 stages or less when used in a 500V igniter, 8 stages or less when used in a 600V igniter, and when used in a 700V igniter. It is preferable that the number of steps is 5 or less.

  In this way, the difference in the number of stages of the Zener diode pair is set according to the applied voltage of the igniter. The absolute value of the difference in the number of stages is 9 steps or less for the 500V system, and the absolute value of the difference in the number of stages is 8 or less for the 600V system. In the case of the 700V system, it is possible to obtain a large surge resistance by setting the absolute value of the difference in the number of stages to 5 stages or less.

  Furthermore, as described in claim 5, the number of parallel portions arranged in a plurality of rows is four or more when used in a 500V igniter, and is used in a 600V or 700V igniter. In this case, the number is preferably 5 or more.

  In this way, the number of parallel portions where the Zener diode pair is formed is set according to the applied voltage of the igniter, and the number is 4 or more in the case of the 500V system, and the number is 5 in the case of the 600V system or 700V system. By using more than this, a large surge resistance can be obtained.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a plan view of a semiconductor device according to a first embodiment of the present invention. It is sectional drawing of the principal part of FIG. It is a partial enlarged view of the outer periphery pressure | voltage resistant part in FIG. (A) is a partial enlarged view of the straight line part B1 of the outer periphery pressure | voltage resistant part B in FIG. 1, (b) is a schematic diagram of a field plate. It is the elements on larger scale which showed the detailed structure of the linear part B1 of the outer periphery pressure | voltage resistant part B in FIG. It is the figure which showed the relationship of the surge immunity (voltage) with respect to the stage number ratio of a Zener diode pair at the time of applying a semiconductor device with respect to a 600V type igniter. It is the figure which showed the relationship of the surge immunity (voltage) with respect to the stage number ratio of a Zener diode pair at the time of applying a semiconductor device with respect to 500V type | system | group, 600V type | system | group igniter. It is the figure which showed the relationship of surge tolerance with respect to the absolute number of the stage number difference of the Zener diode pair with which each of the parallel part 30a and the parallel part 30b when a semiconductor device is applied to a 500V type | system | group, 600V type | system | group igniter. It is the figure which showed the relationship of surge immunity at the time of changing the number of the parallel parts 30 with which the Zener diode pair with which a semiconductor device is applied to a 500V type | system | group, 600V type | system | group igniter, and 700V type | system | group igniter. (A), (b) is a layout figure when the number of the parallel parts 30 is four, and a layout figure when the number of the parallel parts 30 is five.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
FIG. 1 is a plan view of a semiconductor device to which an embodiment of the present invention is applied. 2 is a cross-sectional view taken along the line II ′ of FIG. 1, and FIG. 3 is an enlarged schematic view of the region R of FIG.

  In FIG. 1, a central portion is a cell portion A in which a semiconductor element constituting an IGBT is formed, and an outer peripheral pressure resistant portion B is formed around the cell portion A in a shape along the outer periphery of the cell portion A. In the cross-sectional view of FIG. 2, the right portion of the drawing is the cell portion A, and the left side of the cell portion A is the outer peripheral pressure resistant portion B.

In the semiconductor substrate 1 of FIG. 2, an n ⁻ type layer 1B is formed on a p ⁺ type layer 1A. In this semiconductor substrate 1, the surface on the p ⁺ type layer 1A side is the back surface 1a, the surface on the n ⁻ type layer 1B side is the main surface 1b, and the collector electrode 2 is formed on the back surface 1a.

In the cell portion A, the p-type well 3 is formed in the surface layer portion of the n ⁻ -type layer 1B. The junction depth is shallower than the p-type well 3, and the p-type base region 4 overlaps with the p-type well 3. Is formed. Further, an n ⁺ type source region 5 is formed inside the p type base region 4. A gate electrode 7 made of polysilicon or the like is provided on the upper surface of the n ⁻ type layer 1B with a gate insulating film 6 interposed therebetween. The p-type base region 4 sandwiched between the n ⁺ -type source region 5 and the n ⁻ -type layer 1B located under the gate electrode 7 is a channel region 8.

Further, of the surface portion of the p-type base region 4, on opposite sides of the channel region 8 for the n ⁺ -type source region 5 overlaps the n ⁺ -type source region 5 p ⁺ -type region 9 is formed. An emitter electrode 11 made of an Al alloy or the like is provided on an interlayer insulating film 10 made of BPSG or PSG formed on the surface of the n ⁻ type layer 1B. The emitter electrode 11 is electrically connected to the n ⁺ type source region 5 and the p ⁺ type region 9 through a contact hole 12 formed in the interlayer insulating film 10.

Thus, and a p-type base region 4 and the n ⁺ -type source region 5 and p ⁺ -type region 9, an emitter electrode 11 on the p ⁺ -type region 9, a gate electrode on the p-type base region 4 The cell portion A has a structure in which a plurality of these are installed.

On the other hand, in the outer peripheral breakdown voltage portion B, an outer peripheral p-type well 13 having the same junction depth as the p-type well 3 is formed around the outermost peripheral cell in the surface layer portion of the n ⁻ -type layer 1B. An n ⁺ type contact region 15 is formed on the outermost peripheral side of the surface layer portion of the n ⁻ type layer 1B.

A field oxide film 16 as an insulating film is formed on the n ⁻ -type layer 1B, and an end of the n ⁺ -type contact region 15 on the cell portion side from the outer p-type well 13 on the field oxide film 16. Field plates 17a to 17g and Zener diode groups 18a to 18e made of, for example, polysilicon are formed between the portions. Further, interlayer insulating film 10 is formed on field oxide film 16 including on field plates 17a-17g. A gate wiring 19 connected to the gate electrode 7 is provided on the interlayer insulating film 10, and the gate wiring 19 is electrically connected to the field plate 17 a through a contact hole 20 formed in the interlayer insulating film 10. . An equipotential plate 21 is provided on the outermost peripheral side on the interlayer insulating film 10. The equipotential plate 21 is electrically connected to the field plate 17 g and the n ⁺ -type contact region 15.

4A is a partially enlarged view of the straight line portion B1 of the outer peripheral pressure resistant portion B in FIG. 1, and FIG. 4B is a view schematically showing the structure of the field plate 17. As shown in FIG. The field plate 17 a is arranged on the cell part A side on the lower side of the drawing, is formed so as to surround the cell part A along the outline of the cell part A, and is electrically connected to the gate wiring 19. Further, the field plate 17g is formed so as to surround the cell portion A along the outer contour of the outer peripheral pressure resistant portion B at the outermost periphery, and is electrically connected to the n ⁻ type layer 1B via the equipotential plate 21. It is connected. Therefore, the field plate 17g is electrically connected to the collector electrode 2 through the equipotential plate 21 and the n ⁻ type layer 1B through the p + type layer 1A.

  A plurality of field plates 17b to 17f are arranged between the field plate 17a and the field plate 17g, and these are parallel to the direction along the outline of the cell portion (each side inside the outer peripheral pressure resistant portion). Parallel portions 30 (30a to 30e) and connecting portions 33 (33a to 33f) extending from each parallel portion in an oblique direction (upper right direction in the drawing in the case of FIG. 4A). 30a-30g and the connection parts 33a-33f are connected alternately, and are formed in a step shape toward one direction. The field plates 17b to 17f are electrically insulated from each other.

  A plurality of Zener diode groups 18a to 18e are formed in a strip shape in the parallel portions 30b to 30f disposed between the field plate 17a disposed on the most cell portion A side and the field plate 17g disposed on the outermost periphery side. ing. Specifically, the plurality of band-shaped Zener diode groups 18a to 18e includes, for example, a plurality of n-type regions 31 into which P (phosphorus) is implanted and p-type regions 32 into which B (boron) is implanted, for example. It is formed by arranging. With such a configuration, a reverse connection of a pn junction constituted by a portion formed in the order of the n-type region 31 and the p-type region 32 and a portion formed in the order of the p-type region 32 and the n-type region 31 are configured. The pn junction forward direction connection constitutes a Zener diode pair in which Zener diodes are connected in series in the reverse direction (in FIG. 4A, the Zener diode pair is schematically shown. Are arranged more than the number shown). Therefore, the Zener diode groups 18a to 18e have a configuration in which a plurality of such Zener diode pairs are continuously formed and directly connected.

  For example, the parallel parts 30a to 30e and the connecting parts 33a to 33f arranged in order from the cell part A toward the outer peripheral direction of the semiconductor substrate 1 are defined as one block Z, and the outer peripheral pressure resistant part B includes a plurality of blocks Z. It has a configuration. Note that Z1, Z2, Z3,... In FIG.

  The parallel part 30a including the Zener diode group 18a in the block Z1 is connected to the parallel part 30b including the Zener diode group 18b in the block Z2 adjacent to the right side of the drawing via the connecting part 33b. The parallel portion 30b including the Zener diode group 18b is further connected to the parallel portion 30c including the Zener diode group 18c in the block Z3 (see FIG. 4B) on the right side via a connecting portion 33c. In this way, the parallel portion 30e including the Zener diode group 18e is connected via the connecting portions 33d and 33e.

  Therefore, as shown in FIG. 4B, from the field plate 17a connected to the gate wiring 19 toward the field plate 17g connected to the equipotential plate 21, the Zener diode group 18a in the block Z1 and the block in the block Z2 The zener diode group 18b, the zener diode group 18c in the block Z3, the zener diode group 18d in the block Z4, and the zener diode group 18e in the block Z5 are sequentially inclined in a direction from the cell part A toward the outer periphery. It is configured to be connected in steps.

  Thus, the Zener diode groups 18a to 18e are not connected in one block Z, but are connected in a stepwise manner between the plurality of blocks Z in a direction oblique to the direction along the outer periphery. Thus, the width of the Zener diode groups 18a to 18e in the direction perpendicular to the linear side of the outer peripheral withstand voltage portion can be increased without increasing the area of the outer peripheral withstand voltage portion. And the width of the connection parts 33b-33e connected to the parallel parts 30a-30e containing these Zener diode groups 18a-18e can also be enlarged. Thereby, as shown in FIG. 4B, the resistance value of the electrically connected region from the field plate 17a connected to the gate wiring 19 to the field plate 17g connected to the equipotential plate 21 is reduced. Even when a high-frequency surge is applied, a large current can be instantaneously passed through the Zener diode groups 18a to 18e. For this reason, the gate electrode 7 can be charged and a surge can be absorbed in the ON state of the element.

  Further, the polysilicon layers of the field plates 17a to 17g having the parallel portions 30a to 30e including the Zener diode groups 18a to 18e and the connecting portions 33b to 33e are directed from the cell portion A toward the outer periphery in the entire outer peripheral withstand voltage portion B. Since the electrodes are arranged at regular intervals in the direction, the electric field concentration in the outer peripheral withstand voltage portion B can be reduced when a surge is applied.

  As described above, by applying the structure as described above, it is basically possible to improve the resistance to high frequency surge of the semiconductor device. However, as described above, the demand for semiconductor switching elements increases due to the high efficiency of the igniter and the like, and the required surge withstand tends to increase. May not be able to meet the specifications for withstand load. For this reason, in the present embodiment, the number of stages of the Zener diode groups 18a to 18e formed in the parallel portions 30a to 30e is configured as follows in order to make the semiconductor device capable of further increasing the surge resistance. Yes. This will be described based on the results of trial production by the present inventors.

  As described above, the field plate 17 has a role of defining the gate-collector clamp voltage by the sum of breakdown voltages of the Zener diode groups 18a to 18e included in the parallel portions 30a to 30e connected in a stepwise manner, The plurality of parallel portions 30a to 30e arranged in parallel in the outer peripheral direction has a role of determining the breakdown voltage of the bulk, that is, the entire silicon portion in the semiconductor device. The total number of Zener diode pairs is determined by the breakdown voltage required for the Zener diode groups 18a to 18e as a clamp voltage between the gate and the collector. Further, among the parallel portions 30a to 30e in which the Zener diode groups 18a to 18e are formed, the number of stages of the Zener diode pair provided in the parallel portion 30a closest to the cell portion A is limited by the breakdown voltage of the bulk outer periphery. , Can not be many numbers.

  For this reason, it is assumed that the surge resistance can be increased by increasing the number of Zener diode pairs of the parallel portions 30a to 30e from the cell portion A side toward the outer periphery. Based on such knowledge, the relationship between the number of stages of the Zener diode pairs included in each of the Zener diode groups 18a to 18e provided in the parallel portions 30a to 30e and the surge withstand capability was examined. As a result, the number of stages is changed, the number of stages on the cell part A side is reduced, and the number of stages from the cell part A side toward the outer periphery is reduced as compared with the case where the number of stages of the Zener diode pairs of the parallel parts 30a to 30e is constant. It was confirmed that the surge resistance can be increased by increasing the surge resistance. This will be described with reference to FIGS.

  FIG. 5 is a partially enlarged view showing a detailed structure of the straight line portion B1 of the outer peripheral pressure resistant portion B in FIG. As shown in this figure, each parallel portion 30a-30e is provided with a plurality of Zener diode pairs by alternately arranging a plurality of n-type regions 31 and p-type regions 32. Further, the number of Zener diode pairs of the parallel parts 30a to 30e is increased from the cell part A side toward the outer periphery. In the following description, as shown in FIG. 5, the two parallel portions 30 a and 30 b positioned closest to the cell portion A among the parallel portions 30 a to 30 e where the Zener diode groups 18 a to 18 e are formed are provided. The difference in the number of stages of the Zener diode pair is referred to as the difference in the number of stages of the Zener diode pair. Further, the total number of Zener diode pairs for clamping to obtain resistance against an L load surge arranged between the gate and the collector, that is, the total number of Zener diode pairs provided in the Zener diode groups 18a to 18e is the total number of Zener diode pairs. That's it. The total number of Zener diode pairs is equal to the total number of Zener diode pairs included in one block Z.

  FIG. 6 is a diagram showing the relationship of surge withstand voltage (voltage) to the ratio of the number of Zener diode pairs when the semiconductor device having the above configuration is applied to a 600 V igniter. The stage number ratio of the Zener diode pair serving as the X axis in this figure indicates the ratio between the total number of Zener diode pairs and the difference in the number of Zener diode pairs. Further, on the Y axis in this figure, the maximum surge withstand voltage (voltage) is 40 kV. Since the measurement limit value is 40 kV, no further numerical value is shown, but it actually means that it is 40 kV or more. In the case of a 600V igniter, for example, the total number of Zener diode pairs is about 100.

  As shown in this figure, when the semiconductor device having the above configuration is applied to a 600V igniter, a desired surge withstand is obtained when the stage ratio is 7.5% or less. If it exceeds, it can be seen that the surge resistance decreases. That is, if the difference in the number of Zener diode pairs provided in each of the parallel part 30a and the parallel part 30b becomes too large, the surge resistance cannot be obtained.

  FIG. 7 is a diagram showing the relationship of the surge withstand voltage (voltage) with respect to the stage number ratio of the Zener diode pair when the semiconductor device having the above configuration is applied to a 500 V, 600 V, or 700 V igniter. In the figure, (1) is the 700V system, (2) is the 600V system, and (3) is the 500V system. In the case of a 700V igniter, for example, the total number of Zener diode pairs is about 120, and in the case of a 500V igniter, for example, the total number of Zener diode pairs is about 80.

  As shown in this figure, the relationship of the surge withstand voltage (voltage) to the stage ratio changes according to the applied voltage of the igniter. The stage ratio is 9% or less for the 500V system, and the stage ratio is 7.% for the 600V system. If the ratio of the number of stages is 5% or less and 700V, the desired surge resistance can be obtained. For this reason, the number of stages of the zener diode pair is such that the stage number ratio is 9% or less for the 500V system, the stage ratio is 7.5% or less for the 600V system, and the stage ratio is 6% or less for the 700V system. It is preferable to set the ratio.

  FIG. 8 shows the relationship between the surge resistance and the absolute number of the difference in the number of stages of the zener diode pairs provided in each of the parallel part 30a and the parallel part 30b when the semiconductor device having the above configuration is applied to a 500V, 600V, or 700V igniter. The results of the investigation are shown. As shown in this figure, it can be seen that the surge resistance decreases as the absolute number of the difference in the number of stages of the Zener diode pair increases. Specifically, the absolute value of the step number difference is 9 steps or less for the 500V system, the absolute value of the step number difference is 8 steps or less for the 600V system, and the absolute value of the step number difference is 5 steps or less for the 700V system. If there is, a desired surge resistance can be obtained, and if it exceeds that, the surge resistance is reduced. For this reason, it is preferable to set the absolute value of the difference in the number of stages of the Zener diode pair so that it is 9 stages or less for the 500V system, 8 stages or less for the 600V system, and 5 stages or less for the 700V system.

  FIG. 9 shows the results of investigating the relationship of surge resistance when the number of parallel portions 30 is changed when the semiconductor device having the above configuration is applied to a 500 V, 600 V, or 700 V igniter. FIGS. 10A and 10B are layout diagrams when the number of parallel portions 30 is four, and layout diagrams when the number of parallel portions 30 is five similarly to the above.

  As shown in FIGS. 10 (a) and 10 (b), the number of parallel portions 30 can be changed. In this case, as shown in FIG. 9, the surge resistance varies depending on the number. This is because the number of the Zener diode pairs included in the Zener diode groups 18a to 18e included in the adjacent ones of the parallel parts 30 is increased by increasing the number of the parallel parts 30. This is because it becomes possible to reduce. Specifically, when the semiconductor device having the above configuration is applied to a 500V igniter, the surge resistance can be obtained even if the number of the parallel portions 30 is four, but the above configuration is applied to the 600V and 700V igniters. When the semiconductor device is applied, the surge resistance may not be obtained unless the number of the parallel portions 30 is five. For this reason, it is preferable that the number of the parallel parts 30 is 4 or more in the case of the 500V system, and that the number of the parallel parts 30 is 5 or more in the case of the 600V system or 700V system.

  As described above, if the number of stages of the Zener diode pairs of the parallel portions 30a to 30e is increased from the cell portion A side toward the outer periphery, the surge withstand capability can be increased.

  In particular, the stage ratio is set according to the applied voltage of the igniter. The stage ratio is 9% or less for the 500V system, the stage ratio is 7.5% or less for the 600V system, and the stage ratio is 6 for the 700V system. By making the ratio less than or equal to%, it is possible to obtain a large surge resistance.

  Also, the difference in the number of stages of the Zener diode pair is set in accordance with the applied voltage of the igniter. If the system is 500V, the absolute value of the number of stages is 9 or less, and if the system is 600V, the absolute value of the number of stages is 8 or less, 700V In the case of a system, it is possible to obtain a large surge resistance by setting the absolute value of the difference in the number of stages to 5 stages or less.

  Furthermore, the number of parallel parts 30 in which a Zener diode pair is formed is set according to the applied voltage of the igniter. In the case of 500V system, the number of parallel parts 30 is four or more, and in the case of 600V system or 700V system By setting the number of parallel portions 30 to 5 or more, a large surge resistance can be obtained.

(Other embodiments)
In the above embodiment, as shown in FIGS. 4A and 4B, the field plate 17a electrically connected to the gate wiring 19 moves from the field plate 17g electrically connected to the n ⁻ -type layer 1B. The connecting portions 33 are inclined in the upper right direction on the paper and connected in a staircase pattern, but can be connected in an inclined manner in the upper left direction.

  Further, the number of Zener diode pairs included in each Zener diode group 18a to 18e, the width of the n-type region 31, and the width of the p-type region 32 can be arbitrarily set, and the Zener diode pairs in one block The total number of stages and the total number of blocks can be set arbitrarily.

  Further, in the present embodiment, the semiconductor device in which the cell portion has a substantially pentagonal shape as shown in FIG. 1 has been described as an example, but the present invention is applied to a semiconductor device in which the cell portion has a substantially rectangular shape or other shapes. The invention can be applied.

A cell part B outer peripheral pressure resistant part 1 semiconductor substrate 1A p ⁺ type substrate 1B n ⁻ type layer 2 collector electrode 3 p type well 7 gate electrode 13 outer peripheral p type well 15 n ⁺ type contact region 16 field oxide film 17 field plate 18 zener Diode 21 Equipotential plate 30 Parallel portion 31 N-type region 32 P-type region 33 Connecting portion

Claims (5)

In a semiconductor device comprising a semiconductor substrate (1) having a cell part (A) in which a semiconductor element is formed and an outer peripheral pressure-resistant part (B) disposed on the outer periphery of the cell part.
The outer peripheral pressure-resistant portion includes an outermost plate (17g) electrically connected to the semiconductor substrate and an innermost electrode electrically connected to the gate electrode (7) formed in the cell portion. A plurality of conductive field plates (17) including a peripheral plate (17a) are formed;
The plurality of field plates include a parallel portion (30) arranged in a plurality from the cell portion toward the outer peripheral side of the outer peripheral pressure resistant portion with the parallel direction along the outline of the cell portion as a longitudinal direction, It has a connecting portion (33) extending in an oblique direction from each parallel portion, and is formed in a staircase shape in one direction by alternately connecting the parallel portion and the connecting portion. ,
The parallel portion is provided with a Zener diode group (18a to 18e) in which a plurality of Zener diode pairs in which Zener diodes are connected in series in the opposite direction are formed, and each of the parallel portions arranged in a line is provided. The number of stages of the formed Zener diode pair is increased from the side closer to the cell part toward the outer periphery of the cell part. The semiconductor device according to claim 1 is applied to driving of an igniter to which a high voltage is applied,
Of the plurality of the parallel parts arranged side by side, the difference in the number of stages, which is the difference in the number of stages of the zener diode pair provided in the two parallel parts (30a, 30b) located closest to the cell part side, is obtained. The ratio of the number of stages divided by the total number of Zener diode pairs formed for the parallel portions arranged side by side is 9% or less when used for a 500 V igniter, and is used for a 600 V igniter. The semiconductor device for driving an igniter is characterized in that it is 7.5% or less when used, and 6% or less when used in a 700V igniter.   The difference in the number of stages, which is the difference in the number of stages of the Zener diode pair provided in the two parallel parts (30a, 30b) located closest to the cell part among the parallel parts arranged in a row, is 500V. 9 stages or less when used for a system igniter, 8 stages or less when used for a 600 V igniter, and 5 stages or less when used for a 700 V igniter. A semiconductor device for driving an igniter according to claim 2. The semiconductor device according to claim 1 is applied to driving of an igniter to which a high voltage is applied,
The difference in the number of stages, which is the difference in the number of stages of the Zener diode pair provided in the two parallel parts (30a, 30b) located closest to the cell part among the parallel parts arranged in a row, is 500V. 9 stages or less when used for a system igniter, 8 stages or less when used for a 600 V igniter, and 5 stages or less when used for a 700 V igniter. 4. A semiconductor device for driving an igniter according to claim 2 or 3.   The number of the parallel parts arranged side by side is 4 or more when used in a 500V igniter, and 5 or more when used in a 600V or 700V igniter. 5. The semiconductor device for driving an igniter according to claim 2, wherein the igniter driving semiconductor device is provided.

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