JP2017098359A - Reverse conducting igbt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique that reduces on-voltage of a reverse IGBT by effectively utilizing the vicinity of a boundary between an IGBT area and a diode area as a current path.SOLUTION: When a semiconductor layer 10 from the center of an IGBT area 2a to the boundary between the IGBT area 2a and a diode area 2b is divided by a third of a distance from the center to the boundary, a first area S1 that is the total of side surfaces where a trench gate 26 included in a division area 51 on the boundary side projects in a drift area 14 is larger than a second area S2 that is the total of side surfaces where the trench gate 26 included in a division area 52 on the center side projects in the drift area 14. A third area S3 that is the total of side surfaces whether a trench gate 26 included in a division area 53 between the division area 51 on the boundary side and the division area 52 on the center side projects in the drift area 14 is equal to or larger than the second area S2 but equal to or smaller than the first area S1.SELECTED DRAWING: Figure 4

Description

  The technology disclosed in this specification relates to a reverse conducting IGBT (Reverse Conducting Insulated Gate Bipolar Transistor).

  As disclosed in Patent Literature 1, a reverse conducting IGBT in which an IGBT region and a diode region are integrated in a semiconductor layer has been developed. In such a reverse conducting IGBT, a first main electrode is provided on the back surface of the semiconductor layer, a second main electrode is provided on the surface of the semiconductor layer, and a trench gate is provided on the surface side of the semiconductor layer. The first main electrode functions as a collector electrode in the IGBT region and functions as a cathode electrode in the diode region. The second main electrode functions as an emitter electrode in the IGBT region and functions as an anode electrode in the diode region. In the reverse conducting IGBT, the amount of current flowing between the first main electrode and the second main electrode is controlled according to the potential applied to the trench gate. In the reverse conducting IGBT, the diode structure formed in the diode region operates as a free wheel diode.

JP 2011-134950 A

  When the carrier distribution in the semiconductor layer when the IGBT structure of the IGBT region is on is examined in detail, the carrier amount in the vicinity of the boundary between the IGBT region and the diode region is significantly lower than the carrier amount at the center of the IGBT region. I understand that. From this examination result, it has been found that the conventional reverse conducting IGBT cannot effectively use the vicinity of the boundary between the IGBT region and the diode region as a current path. The present specification provides a technique for reducing the on-voltage of the reverse conducting IGBT by effectively utilizing the vicinity of the boundary between the IGBT region and the diode region as a current path.

  One embodiment of the reverse conducting IGBT disclosed in this specification includes a semiconductor layer having an element region partitioned into an IGBT region and a diode region, a first main electrode provided on a first main surface of the semiconductor layer, and a semiconductor A second main electrode provided on the second main surface of the layer; and a trench gate provided on the second main surface side of the IGBT region of the semiconductor layer. The semiconductor layer has a first conductivity type drift region and a second conductivity type region. The drift region is provided continuously in both the IGBT region and the diode region. The second conductivity type region is provided on the drift region, is provided continuously in both the IGBT region and the diode region, and is exposed on the second main surface of the semiconductor layer. The trench gate protrudes into the drift region through the second conductivity type region. Side surface where the trench gate included in the dividing region on the boundary side protrudes into the drift region when the semiconductor layer from the center of the IGBT region to the boundary between the IGBT region and the diode region is divided into three equal parts of the distance from the center to the boundary The first area, which is the sum of the two, is larger than the second area which is the sum of the side surfaces of the trench gate included in the center-side divided region and protrudes into the drift region, and is between the boundary-side divided region and the center-side divided region. The third area, which is the sum of the side surfaces from which the trench gates included in the divided regions protrude into the drift region, is not less than the second area and not more than the first area.

  One feature of the reverse conducting IGBT of the above embodiment is that the area of the side surface from which the trench gate protrudes into the drift region is configured to be large on the boundary side between the IGBT region and the diode region. As a result, the electrical resistance value between the first main electrode and the second main electrode is lowered on the boundary side between the IGBT region and the diode region. For this reason, when the IGBT structure of the IGBT region is on, the amount of carriers in the semiconductor layer near the boundary between the IGBT region and the diode region increases. In the reverse conducting IGBT of the above embodiment, the vicinity of the boundary between the IGBT region and the diode region is effectively utilized as a current path, and the on-voltage is reduced.

The top view showing the outline | summary of reverse conducting IGBT is shown typically. It is sectional drawing corresponding to the II-II line of FIG.1 and FIG.3, and shows an example of the principal part longitudinal cross-sectional view of reverse conduction IGBT typically. FIG. 3 is a cross-sectional view corresponding to line III-III in FIG. 2, schematically showing a cross-sectional view of the main part of the reverse conducting IGBT. It is sectional drawing corresponding to the II-II line | wire of FIG.1 and FIG.3, and the figure for demonstrating the comparison between each divided area of the area of the side surface where a trench gate protrudes in a drift region is shown. The other example of the principal part longitudinal cross-sectional view of reverse conduction IGBT is shown typically. The principal part cross-sectional view of the reverse conduction IGBT of a modification is shown typically.

  As shown in FIG. 1, the reverse conducting IGBT 1 includes a silicon single crystal semiconductor layer 10. The semiconductor layer 10 has an element region 2 partitioned into an IGBT region 2a and a diode region 2b. The range of the element region 2 substantially coincides with a range where a second main electrode described later is coated. In this example, the IGBT region 2a and the diode region 2b in the element region 2 are partitioned so as to repeat alternately along one direction.

  As shown in FIG. 2, the reverse conducting IGBT 1 covers the first main electrode 22 that covers the back surface (an example of the first main surface) of the semiconductor layer 10 and the surface of the semiconductor layer 10 (an example of the second main surface). A second main electrode 24, a trench gate 26 provided on the surface side of the IGBT region 2 a of the semiconductor layer 10, and a dummy trench 28 provided on the surface side of the diode region 2 b of the semiconductor layer 10.

  The first main electrode 22 functions as a collector electrode in the IGBT region 2a and functions as a cathode electrode in the diode region 2b. The second main electrode 24 functions as an emitter electrode in the IGBT region 2a and functions as an anode electrode in the diode region 2b. In one example, aluminum is used as the material of the first main electrode 22 and the second main electrode 24. As shown in FIG. 3, both the trench gate 26 and the dummy trench 28 have a striped layout when observed from a direction orthogonal to the surface of the semiconductor layer 10.

2 and 3, the semiconductor layer 10 includes a p ⁺ type collector region 11, an n ⁺ type cathode region 12, an n ⁺ type buffer region 13, an n type drift region 14, and a p type region. 15, an n ⁺ -type emitter region 16, an n-type barrier region 17 and a p ⁺ -type contact region 18.

  As shown in FIG. 2, the collector region 11 is provided in a part on the back side of the semiconductor layer 10. The collector region 11 is provided in a part below the drift region 14 and is selectively disposed in the IGBT region 2a. In the semiconductor layer 10, a range where the collector region 11 exists is referred to as an IGBT region 2a. The collector region 11 has a high impurity concentration and is in ohmic contact with the first main electrode 22. The collector region 11 is formed, for example, by introducing boron from the back surface of the semiconductor layer 10 using an ion implantation technique.

  As shown in FIG. 2, the cathode region 12 is provided on a part of the back side of the semiconductor layer 10. The cathode region 12 is provided in a part below the drift region 14 and is selectively disposed in the diode region 2b. In the semiconductor layer 10, a range where the cathode region 12 exists is referred to as a diode region 2b. The cathode region 12 has a high impurity concentration and is in ohmic contact with the first main electrode 22. The cathode region 12 is formed, for example, by introducing phosphorus from the back surface of the semiconductor layer 10 using an ion implantation technique.

  As shown in FIG. 2, the buffer region 13 is provided between the collector region 11 and the drift region 14, and between the cathode region 12 and the drift region 14, and is continuous between the IGBT region 2a and the diode region 2b. Are placed on both sides. The buffer region 13 is formed, for example, by introducing phosphorus from the back surface of the semiconductor layer 10 using an ion implantation technique.

  As shown in FIG. 2, the drift region 14 is provided between the buffer region 13 and the p-type region 15, and the IGBT region 2 a and the diode region 2 b are continuously arranged on both sides. The drift region 14 is a remaining part in which another region is formed in the semiconductor layer 10, and the impurity concentration is constant in the thickness direction. In the upper layer portion of the drift region 14, a lifetime control region 14 a in which crystal defects are adjusted to a high density by He irradiation is formed.

  As shown in FIG. 2, the p-type region 15 is provided above the drift region 14, is in contact with the drift region 14, and the IGBT region 2a and the diode region 2b are continuously arranged on both sides. Exposed on the surface of the semiconductor layer 10. The p-type region 15 functions as a body region in the IGBT region 2a, and functions as an anode region in the diode region 2b. The p-type region 15 is formed, for example, by introducing boron from the surface of the semiconductor layer 10 using an ion implantation technique. The p-type region 15 is an example of a second conductivity type region described in the claims.

  As shown in FIG. 2, the emitter region 16 is provided above the p-type region 15, is in contact with the p-type region 15, is selectively disposed in the IGBT region 2 a, and includes the trench gate 26. It is in contact with the side surface and exposed on the surface of the semiconductor layer 10. As shown in FIG. 3, the emitter region 16 has a form extending in a direction perpendicular to the longitudinal direction of the trench gate 26. The emitter regions 16 are arranged in a distributed manner along the longitudinal direction of the trench gate 26. The emitter region 16 has a high impurity concentration and is in ohmic contact with the second main electrode 24. The emitter region 16 is formed, for example, by introducing phosphorus from the surface of the semiconductor layer 10 using an ion implantation technique.

  As shown in FIG. 2, the barrier region 17 is provided in the p-type region 15, separated from the drift region 14 by the p-type region 15, and also separated from the emitter region 16 by the p-type region 15. It is selectively disposed in the IGBT region 2 a and contacts the side surface of the trench gate 26. The potential of the barrier region 17 is floating. The barrier region 17 is formed, for example, by introducing phosphorus from the surface of the semiconductor layer 10 using an ion implantation technique. Barrier region 17 may be provided so as to be interposed between drift region 14 and p-type region 15. In this case, the impurity concentration of the barrier region 17 is adjusted to be higher than the impurity concentration of the drift region 14.

  As shown in FIG. 3, the contact region 18 is provided above the p-type region 15, is in contact with the p-type region 15, is selectively disposed in the IGBT region 2 a, and Exposed on the surface. Contact regions 18 are distributed along the longitudinal direction of trench gate 26. The contact region 18 has an impurity concentration higher than that of the p-type region 15 and is in ohmic contact with the second main electrode 24. The contact region 18 is formed, for example, by introducing boron from the surface of the semiconductor layer 10 using an ion implantation technique.

  As shown in FIG. 2, each of the trench gate 26 and the dummy trench 28 has an electrode portion made of polysilicon and an insulating film made of silicon oxide, and the electrode portion is interposed through the insulating film. Opposite the semiconductor layer 10. The electrode portion of the trench gate 26 is separated from the second main electrode 24 by an interlayer insulating film, and is configured to be able to apply a gate potential. The electrode portion of the dummy trench is in contact with the second main electrode 24 and is configured to have the same potential as the second main electrode 24.

  As shown in FIG. 2, the trench gate 26 extends from the surface of the semiconductor layer 10 toward the deep portion, and is configured to penetrate the p-type region 15 and protrude into the drift region 14. The emitter region 16 and the barrier region 17 are in contact with the side surface of the trench gate 26. The dummy trench 28 also extends from the surface of the semiconductor layer 10 toward the deep portion, and is configured to penetrate the p-type region 15 and protrude into the drift region 14.

  As shown in FIG. 2, the trench gate 26 is configured to have different lengths protruding into the drift region 14 along the thickness direction of the semiconductor layer 10. The trench gate 26 is configured such that the length protruding from the drift region 14 increases as the distance from the boundary between the IGBT region 2a and the diode region 2b becomes shorter. In other words, it can be explained as follows. As shown in FIG. 4, the semiconductor layer 10 from the center of the IGBT region 2a to the boundary between the IGBT region 2a and the diode region 2b is divided into three equal parts of the distance from the center to the boundary. A side divided area 52 and an intermediate divided area 53 between the boundary side divided area 51 and the center side divided area 52 are defined. The first area S1, which is the sum of the side surfaces where the trench gates 26 included in the boundary-side divided region 51 protrude into the drift region 14, is the total of the side surfaces where the trench gate 26 included in the center-side divided region 52 protrudes into the drift region 14. It is larger than a certain second area S2. Furthermore, the third area S3, which is the total of the side surfaces of the trench gate 26 included in the intermediate divided region 53 that protrudes into the drift region 14, is equal to or greater than the second area S2 and equal to or less than the first area S1. In this example, the third area S3 is larger than the second area S2 and smaller than the first area S1.

  In this example, the length that the trench gate 26 protrudes into the drift region 14 is set so as to gradually increase from the center of the IGBT region 2a toward the boundary between the IGBT region 2a and the diode region 2b. However, as long as the relationship between the protruding length of the trench gate 26 closest to the diode region 2b is longer than the protruding length of the trench gate 26 at the center, the protruding length of the trench gate 26 between them is obtained. All may be set to be constant, or a part may be set to increase stepwise with a constant length. That is, the protruding length of the trench gate 26 closest to the diode region 2b is longer than the protruding length of the trench gate 26 at the center, and the protruding length of the trench gate 26 between them is the trench gate at the center. 26, which is equal to or longer than the protruding length of the trench gate 26 closest to the diode region 2b, and when the protruding lengths of adjacent trench gates 26 are compared, the trenches on the diode region 2b side are compared. The protruding length of the gate 26 is equal to or longer than the protruding length of the trench gate 26 on the center side.

  In the reverse conducting IGBT 1, the first main electrode 22, the collector region 11, the buffer region 13, the drift region 14, the p-type region 15, the emitter region 16, the barrier region 17, the contact region 18, the second main electrode 24, and the trench gate 26 are provided. An IGBT structure is configured. In the reverse conducting IGBT 1, the first main electrode 22, the cathode region 12, the buffer region 13, the drift region 14, the p-type region 15 and the second main electrode 24 form a diode structure.

  In the reverse conducting IGBT 1, when a voltage that is more positive than the second main electrode 24 is applied to the first main electrode 22 and a voltage that is more positive than the second main electrode 24 is applied to the electrode portion of the trench gate 26, The IGBT structure in the IGBT region 2a is turned on. As described above, the reverse conducting IGBT 1 is configured such that the length that the trench gate 26 protrudes into the drift region 14 increases as the distance from the boundary between the IGBT region 2a and the diode region 2b decreases. With one feature. Thereby, many holes flow in along the side surface of the trench gate 26 in the vicinity of the boundary between the IGBT region 2a and the diode region 2b. The electrical resistance value between the first main electrode 22 and the second main electrode 24 becomes lower as the distance from the boundary between the IGBT region 2a and the diode region 2b is closer. For this reason, when the IGBT structure of the IGBT region 2a is on, a larger amount of current flows near the boundary between the IGBT region 2a and the diode region 2b than at the center of the IGBT region 2a, and near the boundary between the IGBT region 2a and the diode region 2b. The amount of carriers in the semiconductor layer 10 increases. In the reverse conducting IGBT 1, the vicinity of the boundary between the IGBT region 2a and the diode region 2b is effectively utilized as a current path, and the on-voltage is reduced.

  In the reverse conducting IGBT 1, since the current flowing near the boundary between the IGBT region 2a and the diode region 2b increases, the amount of heat generated in this portion increases. In the conventional reverse conducting IGBT (the length and pitch of the trench gate are constant), since the current near the boundary between the IGBT region and the diode region is small, the heat distribution of the semiconductor layer has a peak at the center of the IGBT region. It drops sharply toward the center and becomes uneven. Such non-uniform heat distribution makes the electrical characteristics of the reverse conducting IGBT non-uniform and reduces the reliability of the reverse conducting IGBT. On the other hand, in the reverse conducting IGBT 1, since the current flowing near the boundary between the IGBT region 2a and the diode region 2b increases, the heat generated in this portion is efficiently dissipated to the diode region 2b. The heat distribution is made uniform. In the reverse conducting IGBT 1, the heat distribution of the semiconductor layer 10 is made uniform, the electrical specification is stabilized, and the reliability is improved.

  Further, the reverse conducting IGBT 1 is characterized by having a barrier region 17. The barrier region 17 suppresses the discharge of holes to the second main electrode 24 when the IGBT structure of the IGBT region 2a is turned on, accumulates holes in the semiconductor layer 10, and increases the on-voltage. Reduce. In the reverse conducting IGBT 1, many holes flow in the vicinity of the boundary between the IGBT region 2 a and the diode region 2 b due to the shape effect of the trench gate 26 described above. These holes are effectively accumulated by the barrier region 17. In other words, the shape effect of the trench gate 26 described above can improve the hole accumulation effect of the barrier region 17. As a result, in the reverse conducting IGBT 1, the vicinity of the boundary between the IGBT region 2a and the diode region 2b is used very effectively as a current path, and the on-voltage is significantly reduced.

  FIG. 5 shows a modified reverse conducting IGBT 1A. The reverse conducting IGBT 1A is characterized in that the pitch width between adjacent trench gates 26 is configured to be shorter as the distance from the boundary between the IGBT region 2a and the diode region 2b is closer. Although not shown, even in the reverse conducting IGBT 1A, the semiconductor layer 10 from the center of the IGBT region 2a to the boundary between the IGBT region 2a and the diode region 2b is divided into three equal parts of the distance from the center to the boundary, and the boundary side divided region Trench gate in which the first area, which is the sum of the side surfaces of the trench gate 26 included in the boundary side divided region protruding into the drift region 14 when the central side divided region and the intermediate divided region are defined, is included in the central side divided region Is larger than the second area that is the sum of the side surfaces protruding into the drift region 14, and the third area that is the sum of the side surfaces that the trench gate 26 included in the intermediate divided region projects into the drift region 14 is the second area. Above and below the first area. In addition, the pitch width between the trench gates 26 adjacent on the most diode region 2b side is shorter than the pitch width between the trench gates 26 adjacent on the most center side, and is centered on the trench gate 26 closest to the diode region 2b side. The pitch width between the trench gates 26 between certain trench gates 26 is equal to or greater than the pitch width of the trench gates 26 adjacent on the diode region 2b side and equal to or smaller than the pitch width of the trench gates 26 adjacent on the most central side. Further, when comparing the pitch widths between the respective trench gates 26, it can be said that the pitch width between the trench gates 26 on the diode region 2b side is equal to or larger than the pitch width between the trench gates 26 on the center side. In the reverse conducting IGBT 1A, the trench gate 26 may be configured such that the length protruding from the drift region 14 increases as the distance from the boundary between the IGBT region 2a and the diode region 2b decreases.

  As described above, the reverse conducting IGBT 1A is configured such that the pitch width between adjacent trench gates 26 becomes shorter as the distance from the boundary between the IGBT region 2a and the diode region 2b becomes shorter. Thereby, many holes flow in along the side surface of the trench gate 26 in the vicinity of the boundary between the IGBT region 2a and the diode region 2b. The electrical resistance value between the first main electrode 22 and the second main electrode 24 becomes lower as the distance from the boundary between the IGBT region 2a and the diode region 2b is closer. For this reason, when the IGBT structure of the IGBT region 2a is on, a larger amount of current flows near the boundary between the IGBT region 2a and the diode region 2b than at the center of the IGBT region 2a, and near the boundary between the IGBT region 2a and the diode region 2b. The amount of carriers in the semiconductor layer 10 increases. In the reverse conducting IGBT 1, the vicinity of the boundary between the IGBT region 2a and the diode region 2b is effectively utilized as a current path, and the on-voltage is reduced.

  Further, the reverse conducting IGBT 1A also has a barrier region 17 as one feature. In the reverse conducting IGBT 1A, the pitch width of the trench gate 26 is narrow in the vicinity of the boundary between the IGBT region 2a and the diode region 2b. Therefore, the electrical resistance value with respect to holes discharged from this portion is high. Furthermore, since the barrier region 17 is provided, the electric resistance value for holes discharged from this portion is further increased. Thus, in the reverse conducting IGBT 1A, the hole accumulation effect in the vicinity of the boundary between the IGBT region 2a and the diode region 2b is remarkably improved by the synergistic effect of the trench gate 26 and the barrier region 17. As a result, in the reverse conducting IGBT 1, the boundary between the IGBT region 2a and the diode region 2b is extremely effectively utilized as a current path, and the on-voltage is significantly reduced.

  FIG. 6 shows a reverse conducting IGBT 1B according to a modification. The reverse conducting IGBT 1B is configured such that the area of the emitter region 16 exposed on the surface of the semiconductor layer 10 increases as the distance from the boundary between the IGBT region 2a and the diode region 2b decreases. Although illustration is omitted, even in the reverse conducting IGBT 1B of the modified example, the semiconductor layer 10 from the center of the IGBT region 2a to the boundary between the IGBT region 2a and the diode region 2b is divided into three equal parts of the distance from the center to the boundary, The first area, which is the total of the emitter regions 16 exposed on the surface of the semiconductor layer 10 in the boundary side divided region when the side divided region, the central side divided region, and the intermediate divided region are defined, is the semiconductor layer 10 in the central side divided region. The third area which is larger than the second area which is the sum of the emitter regions 16 exposed on the surface of the semiconductor layer 10 and which is the sum of the emitter regions 16 exposed on the surface of the semiconductor layer 10 in the intermediate divided region is equal to or larger than the second area. There is a first area or less. Instead of this modification, the impurity concentration of the emitter region 16 may be configured to increase as the distance from the boundary between the IGBT region 2a and the diode region 2b decreases. Although illustration is omitted, even in this case, the semiconductor layer 10 from the center of the IGBT region 2a to the boundary between the IGBT region 2a and the diode region 2b is divided into three equal parts of the distance from the center to the boundary, When the center-side divided region and the intermediate divided region are defined, the first concentration of the impurity concentration of the emitter region 16 of the boundary-side divided region is higher than the second concentration of the impurity concentration of the emitter region 16 of the center-side divided region, The third concentration of the impurity concentration of the emitter region 16 in the intermediate divided region is not less than the second concentration and not more than the first concentration. Alternatively, the emitter region 16 may be configured to combine these features. When the emitter region 16 is configured in this way, the first main electrode 22 and the first main electrode 22 are connected to the first main electrode 22 due to a decrease in contact resistance between the emitter region 16 and the second main electrode 24 and / or an increase in the amount of electrons injected from the emitter region 16. The electrical resistance value between the two main electrodes 24 becomes lower as the distance from the boundary between the IGBT region 2a and the diode region 2b is closer. For this reason, when the IGBT structure of the IGBT region 2a is on, a larger amount of current flows near the boundary between the IGBT region 2a and the diode region 2b than at the center of the IGBT region 2a, and near the boundary between the IGBT region 2a and the diode region 2b. The amount of carriers in the semiconductor layer 10 increases. In the reverse conducting IGBT 1A, the boundary between the IGBT region 2a and the diode region 2b is more effectively utilized as a current path, and the on-voltage is further reduced.

  Further, the impurity concentration of the collector region 11 provided in the IGBT region 2a may be configured to increase as the distance from the boundary between the IGBT region 2a and the diode region 2b decreases. Although illustration is omitted, even in this case, the semiconductor layer 10 from the center of the IGBT region 2a to the boundary between the IGBT region 2a and the diode region 2b is divided into three equal parts of the distance from the center to the boundary, When the center side divided region and the intermediate divided region are defined, the first concentration of the impurity concentration of the collector region 11 of the boundary side divided region is higher than the second concentration of the impurity concentration of the collector region 11 of the center side divided region, The third concentration of the impurity concentration in the collector region 11 of the intermediate divided region is not less than the second concentration and not more than the first concentration. When the collector region 11 is configured in this way, the electrical resistance value between the first main electrode 22 and the second main electrode 24 is the same as that of the IGBT region 2a due to an increase in the amount of holes injected from the collector region 11. The closer the distance from the boundary of the diode region 2b, the lower the value. For this reason, when the IGBT structure of the IGBT region 2a is on, a larger amount of current flows near the boundary between the IGBT region 2a and the diode region 2b than at the center of the IGBT region 2a, and near the boundary between the IGBT region 2a and the diode region 2b. The amount of carriers in the semiconductor layer 10 increases. In the reverse conducting IGBTs 1 and 1A, the boundary between the IGBT region 2a and the diode region 2b is more effectively utilized as a current path, and the on-voltage is further reduced.

  In the above example, as shown in FIG. 1, the case where the IGBT region 2a and the diode region 2b in the element region 2 are partitioned so as to repeat alternately along one direction is illustrated. The layout of the IGBT region 2a and the diode region 2b is not limited to this example, and various layouts can be employed. For example, one or a plurality of diode regions 2b may be distributed so as to be surrounded by the IGBT region 2a, and the surrounded diode regions 2b have a rectangular shape, a polygonal shape, a circular shape, or an elliptical shape. You may do it.

  In the above example, the case where seven trench gates 26 are provided in the IGBT region 2a is illustrated. The number of trench gates 26 provided in the IGBT region 2a is not limited to this example. However, in order to cause a difference in form of the trench gate 26 between the center of the IGBT region 2a and the boundary between the IGBT region 2a and the diode region 2b, the number of the trench gates 26 provided in the IGBT region 2a is at least three. It is desirable that

  In the above example, the case where the trench gate 26 provided in the IGBT region 2a is configured to be line-symmetric with respect to the center of the IGBT region 2a in the cross section shown in FIG. Instead, the trench gate 26 provided in the IGBT region 2a may be configured to be asymmetric with respect to the center of the IGBT region 2a in the cross section shown in FIG. For example, the protruding length of the trench gate 26 on one side with respect to the center of the IGBT region 2a may be configured to be longer than the protruding length of the trench gate 26 on the other side.

  In the above example, in the entire range of the IGBT region 2a, the area per unit volume of the side surface where the trench gate 26 protrudes into the drift region 14 is increased as the distance from the boundary between the IGBT region 2a and the diode region 2b is closer. The case where it was comprised was illustrated. In this case, since the entire IGBT region 2a is effectively utilized as a current path, the on-voltage reduction effect is great. However, the technique disclosed in this specification is useful even when the trench gate 26 to which such a configuration is applied is provided in at least a part of the IGBT region 2a. Even in this case, in at least a part of the IGBT region 2a, the boundary between the IGBT region and the diode region is effectively utilized as a current path, and the on-voltage is reduced.

  The technical features disclosed in this specification will be summarized below. The items described below have technical usefulness independently.

  One embodiment of the reverse conducting IGBT disclosed in this specification includes a semiconductor layer having an element region partitioned into an IGBT region and a diode region, a first main electrode provided on a first main surface of the semiconductor layer, A second main electrode provided on the second main surface of the semiconductor layer and a trench gate provided on the second main surface side of the IGBT region of the semiconductor layer may be provided. The semiconductor layer has a first conductivity type drift region and a second conductivity type region. The drift region is provided continuously in both the IGBT region and the diode region. The second conductivity type region is provided on the drift region, is provided continuously in both the IGBT region and the diode region, and is exposed on the second main surface of the semiconductor layer. The trench gate protrudes into the drift region through the second conductivity type region. Side surface where the trench gate included in the dividing region on the boundary side protrudes into the drift region when the semiconductor layer from the center of the IGBT region to the boundary between the IGBT region and the diode region is divided into three equal parts of the distance from the center to the boundary The first area, which is the sum of the two, is larger than the second area which is the sum of the side surfaces of the trench gate included in the center-side divided region and protrudes into the drift region, and is between the boundary-side divided region and the center-side divided region. The third area, which is the sum of the side surfaces from which the trench gates included in the divided regions protrude into the drift region, is not less than the second area and not more than the first area. More desirably, the third area is larger than the second area and smaller than the first area.

  The trench gate provided in at least a part of the IGBT region has a protruding length at which the trench gate closest to the diode region protrudes into the drift region, and the trench gate at the center of the IGBT region protrudes into the drift region. You may be comprised longer than protrusion length. Furthermore, the protrusion length of the trench gate between the trench gate closest to the diode region and the trench gate in the center protruding into the drift region is equal to or longer than the protrusion length of the trench gate in the center and closest to the diode region. You may be comprised so that it may become below the protrusion length of a certain trench gate. Furthermore, when the protruding lengths of adjacent trench gates are compared, the protruding length of the trench gate on the diode region side may be greater than or equal to the protruding length of the trench gate on the center side. More desirably, the protruding length of the trench gate may be configured to increase as the distance from the boundary between the IGBT region and the diode region decreases. In addition, the trench gate provided in at least a part of the IGBT region is configured such that the pitch width between the trench gates adjacent on the most diode region side is shorter than the pitch width between the trench gates adjacent on the most central side. It may be. Furthermore, the pitch width between the trench gates located between the trench gate closest to the diode region and the trench gate located at the center is equal to or greater than the pitch width of the trench gate adjacent to the diode region, and is adjacent to the center. You may be comprised so that it may become below the pitch width of a trench gate. Furthermore, when the pitch width between the respective trench gates is compared, the pitch width between the trench gates on the diode region side may be configured to be greater than or equal to the pitch width between the trench gates on the center side. More desirably, the pitch width between adjacent trench gates may be configured to increase as the distance from the boundary between the IGBT region and the diode region becomes shorter. Alternatively, the trench gate may be configured to combine these features. According to the reverse conducting IGBT of these aspects, the electrical resistance value between the first main electrode and the second main electrode becomes lower as the distance from the boundary between the IGBT region and the diode region is closer. For this reason, when the IGBT structure of the IGBT region is on, the amount of carriers in the semiconductor layer near the distance from the boundary between the IGBT region and the diode region increases. In the reverse conducting IGBT of the above aspect, the boundary between the IGBT region and the diode region is effectively utilized as a current path, and the on-voltage decreases.

  In the reverse conducting IGBT of the above aspect, the semiconductor layer may further include a first conductivity type emitter region. The emitter region is provided on the drift region, is provided in the IGBT region, is in contact with the side surface of the trench gate, and is exposed on the second main surface of the semiconductor layer. In this case, the area of the emitter region exposed on the second main surface of the semiconductor layer may be configured to increase as the distance from the boundary between the IGBT region and the diode region decreases. Further, the impurity concentration of the emitter region may be configured to increase as the distance from the boundary between the IGBT region and the diode region becomes shorter. Alternatively, the emitter region may be configured to combine these features. According to the reverse conducting IGBT of these aspects, the electrical resistance value between the first main electrode and the second main electrode becomes lower as the distance from the boundary between the IGBT region and the diode region is closer. For this reason, when the IGBT structure of the IGBT region is on, the amount of carriers in the semiconductor layer near the distance from the boundary between the IGBT region and the diode region increases. In the reverse conducting IGBT of the above aspect, the boundary between the IIGBT region and the diode region is effectively utilized as a current path, and the on-voltage decreases.

  In the reverse conducting IGBT of the above aspect, the semiconductor layer may have a second conductivity type collector region. The collector region is provided in the IGBT region and is exposed on the first main surface of the semiconductor layer. In this case, the collector region may be configured such that the impurity concentration in the collector region increases as the distance from the boundary between the IGBT region and the diode region decreases. According to the reverse conducting IGBT of this aspect, the electrical resistance value between the first main electrode and the second main electrode becomes lower as the distance from the boundary between the IGBT region and the diode region is closer. For this reason, when the IGBT structure of the IGBT region is on, the amount of carriers in the semiconductor layer near the distance from the boundary between the IGBT region and the diode region increases. In the reverse conducting IGBT of the above aspect, the boundary between the IGBT region and the diode region is effectively utilized as a current path, and the on-voltage decreases.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

1: Reverse conducting IGBT
2a: IGBT region 2b: Diode region 10: Semiconductor layer 11: Collector region 12: Cathode region 13: Buffer region 14: Drift region 15: P-type region 16: Emitter region 17: Barrier region 18: Contact region 19: Pillar region 22 : First main electrode 24: second main electrode 28: dummy trench

Claims (1)

A reverse conducting IGBT,
A semiconductor layer having an element region partitioned into an IGBT region and a diode region;
A first main electrode provided on a first main surface of the semiconductor layer;
A second main electrode provided on the second main surface of the semiconductor layer;
A trench gate provided on the second main surface side of the IGBT region of the semiconductor layer,
The semiconductor layer is
A drift region of a first conductivity type provided continuously in both the IGBT region and the diode region;
A second conductivity type region provided on the drift region, continuously provided in both the IGBT region and the diode region, and exposed to the second main surface of the semiconductor layer; And
The trench gate protrudes into the drift region through the second conductivity type region,
When the semiconductor layer from the center of the IGBT region to the boundary between the IGBT region and the diode region is divided into three equal parts of the distance from the center to the boundary, the trench included in the division region on the boundary side The first area, which is the sum of the side surfaces where the gate protrudes into the drift region, is larger than the second area, which is the sum of the side surfaces where the trench gate included in the central divided region protrudes into the drift region, and the boundary A third area that is the sum of the side surfaces of the trench gates included in the divided region between the divided region on the side and the divided region on the central side that protrudes into the drift region is equal to or greater than the second area, and Reverse conducting IGBT that is smaller than the area.

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