Semiconductor device and method for manufacturing the same

Abstract

To provide a semiconductor device with low on-resistance.SOLUTION: A semiconductor device comprises: a semiconductor element 10 including a surface electrode layer 20 having a first principal surface 20a and a second principal surface 20b, the first principal surface 20a being exposed as a surface; a first wire 30 electrically connected to the first principal surface 20a by a plurality of first connection parts 31 and arranged on the first principal surface 20a so as to extend in a first prescribed direction; and a second wire 33 electrically connected to the first principal surface 20a by a second connection part 34 and arranged on the first principal surface 20a so as to extend in a second prescribed direction. A second circle equivalent diameter, which is a diameter of a circle having the same cross section as a cross section of the second wire 33, is greater than a first circle equivalent diameter, which is a diameter of a circle having the same cross section as a cross section of the first wire 30.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device. [Background technology]

[0002] Conventionally, a technique for reducing the resistance value of the path of current flowing through the front electrode layer of a semiconductor element mounted on a semiconductor device has been proposed (for example, see Patent Document 1). The smaller the resistance value of the path of current flowing through the front electrode layer of the semiconductor element, the more the power loss during operation of the semiconductor device can be reduced.

[0003] The semiconductor device includes a semiconductor element, a surface electrode layer disposed on the surface of the semiconductor element, and a bonding wire connected to the surface electrode layer and electrically connecting the semiconductor element to the outside. The elements that constitute the on-resistance of the semiconductor device include the resistance of the semiconductor element, the resistance of the surface electrode layer, and the resistance of the bonding wire.

[0004] In order to reduce the resistance of semiconductor elements, miniaturized structures, trench gate structures, superjunction structures, etc. have been proposed. By using these, the resistance of semiconductor elements can be reduced to 1 / 2 or less.

[0005] As the resistance of the semiconductor element decreases, the resistance of the surface electrode layer and the resistance of the bonding wire become relatively large.

[0006] One technique for reducing the resistance of the surface electrode layer is to increase the thickness of the surface electrode layer, but since the thickness of the surface electrode layer is restricted by the specifications of the semiconductor device and the process capacity of the manufacturing process, it is difficult to increase only the thickness of the surface electrode layer.

[0007] In addition, techniques for reducing the resistance of the bonding wire include increasing the number of bonding wires or increasing the diameter of the bonding wires. However, increasing the number of bonding wires or increasing the diameter of the bonding wires requires changing the wiring pattern of the circuit board to which the bonding wires are connected or the structure of the external terminals such as the lead frame. Furthermore, increasing the number of bonding wires or increasing the diameter of the bonding wires also requires changing the area of ​​the semiconductor element. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2011-18841 A Summary of the Invention [Problem to be solved by the invention]

[0009] Fig. 1 is a diagram showing a conventional semiconductor device including bonding wires, and Fig. 2 is a cross-sectional view taken along line ZZ in Fig. 1.

[0010] The semiconductor device 100 includes a semiconductor element 110, a bonding wire 133, a bonding wire 136, a circuit board or a lead frame (not shown) on which the back electrode layer of the semiconductor element 110 is mounted via a solder layer or a conductive adhesive such as silver paste, and an external terminal (not shown) such as a wiring pattern of the circuit board or a lead frame. The semiconductor element 110 has a drain electrode layer 119 (rear electrode layer) on its lower surface, and a source electrode layer 120 and a gate electrode layer 121 on its upper surface. The semiconductor element 110 has a drain layer 111, a drift layer 112, and a plurality of trenches 150 whose depth direction is from the upper surface of the drift layer 112 toward the drain layer 111. A gate insulating film 115 and a gate electrode 114 embedded inside the trench 150 via the gate insulating film 115 are provided in the trench 150. A p-base region 113 shallower than the bottom surface of the trench 150 is provided between adjacent trenches 150. A source region 116 is provided in a surface layer of the p-base region 113 so as to contact the gate electrode 114 via the gate insulating film 115. In addition, a p-base region 113 is provided between adjacent source regions 116. ++ A contact region 117 is provided. A connection portion 134 indicates a portion where the bonding wire 133 is joined (in contact) with the source electrode layer 120. A connection portion 137 indicates a portion where the bonding wire 136 is joined (in contact) with the gate electrode layer 121. The source electrode layer 120 corresponds to a surface electrode layer. One end of the bonding wire 133 is electrically connected to the source electrode layer 120 at a connection portion 134. The other end of the bonding wire 133 is joined to an external terminal (not shown) such as a wiring pattern or a lead frame of a circuit board on which the semiconductor element 110 is mounted, and the external terminal such as the wiring pattern or the lead frame is electrically connected to the source electrode layer 120. The gate electrode layer 121 is electrically connected to the gate electrode 114 via a wiring layer (not shown). The upper portions of the gate electrode 114 and the gate insulating film 115 are covered with an interlayer insulating film 118. One end of the bonding wire 136 is electrically connected to the gate electrode layer 121 at a connection portion 137. The other end of the bonding wire 136 is joined to another external terminal (not shown) such as another wiring pattern or a lead frame of a circuit board on which the semiconductor element 110 is mounted, and the other wiring pattern or the other external terminal of the circuit board such as a lead frame is electrically connected to the gate electrode layer 121.

[0011] The semiconductor element 110 has a plurality of cells. C1, C2, C3, and C4 shown in FIG. 2 indicate some cells of the semiconductor element 110. The cell refers to the center between the width direction of adjacent trenches 150. For example, the cell between the center in the width direction of trench 150a and the center in the width direction of trench 150b adjacent to trench 150a is defined as cell C1, and the cell between the center in the width direction of trench 150b and the center in the width direction of trench 150c adjacent to trench 150b is defined as cell C2. 2 have the same structure, but the position of cell C4 is farther away than the position of cell C1 with respect to bonding wire 133. In the example shown in Fig. 2, the distance between end 134a of connection portion 134 of bonding wire 133 and cell C4 is four times the distance between end 134a of connection portion 134 of bonding wire 133 and cell C1.

[0012] When the semiconductor device 100 is in operation, in each of the cells C1, C2, C3, and C4, a voltage equal to or greater than the threshold is applied to the gate electrode 114 via the bonding wire 136 and the gate electrode layer 121, causing a current to flow from the drain electrode layer 119 to the source region 116, and from the source region 116 to the bonding wire 133 via the source electrode layer 120.

[0013] Here, the cell C1 and the cell C4 are taken as examples for explanation. In the cell C1 and the cell C4, the resistance r0 in the path through which the current flows from the drain electrode layer 119 to the source region 116 is the same.

[0014] On the other hand, the path length within the source electrode layer 120 through which current flows from the source region 116 of cell C4 to the end 134a of the connection portion 134 of the bonding wire 133 is four times the path length through which current flows from the source region 116 of cell C1 to the end 134a of the connection portion 134 of the bonding wire 133.

[0015] Therefore, the resistance of the path along which current flows from the source region 116 of cell C4, via the source electrode layer 120, to the end 134a of the connection portion 134 of the bonding wire 133 is four times (4 × rs) the resistance rs of the path along which current flows from the source region 116 of cell C1, via the source electrode layer 120, to the end 134a of the connection portion 134 of the bonding wire 133.

[0016] In this manner, the resistance between each of the cells C1, C2, C3, and C4 and the bonding wire 133 varies depending on the distance between each of the cells C1, C2, C3, and C4 and the end 134a of the connection portion 134 of the bonding wire 133.

[0017] Since the thickness of the source electrode layer 120 is about several μm, the sheet resistance of the source electrode layer 120 is not small. The sheet resistance of the source electrode layer 120 increases according to the distance of the source electrode layer 120 between each of the cells C1, C2, C3, and C4 and the end 134a of the connection portion 134 of the bonding wire 133. Therefore, the increase in the sheet resistance of the source electrode layer 120 increases the resistance of the front electrode layer of the semiconductor element 110, which is a cause of preventing the reduction of the on-resistance of the semiconductor device 100.

[0018] By the way, it has been proposed to use copper clips instead of bonding wires. Figure 3 shows a conventional semiconductor device using copper clips.

[0019] The semiconductor device 100 includes a semiconductor element 110, a solder layer 152, a copper clip 160, and a circuit board or lead frame (not shown). The semiconductor element 110 has a drain electrode layer 119 on its lower surface, and a source electrode layer 120 and a gate electrode layer 121 on its upper surface. Furthermore, a plating layer 151 is provided on the upper surface of the source electrode layer 120. Another plating layer, another solder layer, and another copper clip (not shown) are also provided on the upper surface of the gate electrode layer 121. The semiconductor element 110 has a drain layer 111, a drift layer 112, and a plurality of trenches 150 whose depth direction is from the upper surface of the drift layer 112 toward the drain layer 111. A gate insulating film 115 and a gate electrode 114 embedded in the trench 150 via the gate insulating film 115 are provided in the trench 150. A p-base region 113 shallower than the bottom surface of the trench 150 is provided between adjacent trenches 150. A source region 116 is provided in a surface layer of the p-base region 113 so as to contact the gate electrode 114 via the gate insulating film 115. The gate electrode 114 and the upper portion of the gate insulating film 115 are covered with an interlayer insulating film 118. In addition, between adjacent source regions 116, ++ A contact region 117 is provided. Here, the surface electrode layer of the semiconductor element 110 refers to the source electrode layer 120 and the plated electrode layer 151. The copper clip 160 electrically connects, via a solder layer 152, the surface electrode layers, that is, the source electrode layer 120 and the plated electrode layer 151, to an external terminal (not shown) such as a wiring pattern or a lead frame of a circuit board on which the semiconductor element 110 is mounted.

[0020] The semiconductor element 110 has a plurality of cells. C1, C2, C3, and C4 shown in FIG. 3 indicate some cells of the semiconductor element 110. The cell refers to the center between the width direction of adjacent trenches 150. For example, the cell between the center in the width direction of trench 150a and the center in the width direction of trench 150b adjacent to trench 150a is defined as cell C1, and the cell between the center in the width direction of trench 150b and the center in the width direction of trench 150c adjacent to trench 150b is defined as cell C2. When the semiconductor device 100 is in operation, in each of the cells C1, C2, C3, and C4, a voltage equal to or greater than the threshold is applied to the gate electrode 114, causing a current to flow from the drain electrode layer 119 to the source region 116, and from the source region 116 to the copper clip 160 via the source electrode layer 120, the plated electrode layer 151, and the solder layer 152.

[0021] The copper clip 160 is electrically connected to the surface of the source electrode layer 120 via the solder layer 152. Therefore, the path length of the current flowing from the source region 116 of the cell C4 through the source electrode layer 120, which is the surface electrode layer, to the copper clip 160 via the solder layer 152 is the same as the path length of the cell C1.

[0022] That is, the resistance of the path along which current flows from the source regions 116 of cells C1 and C4 to the copper clip 160 is the sum of the resistance component r1 of the source electrode layer 120, the resistance component r2 of the plated electrode layer 151, and the resistance component r3 of the solder layer 152.

[0023] However, since the resistance of the plated electrode layer 151 and the solder layer 152 is high, the resistance of the path through which the current flows through the source electrode layer 120, the plated electrode layer 151, and the solder layer 152 is about two orders of magnitude higher than when the surface electrode layer shown in Fig. 2 is only the source electrode layer 120. Therefore, the on-resistance of the semiconductor device 100 having the copper clip 160 is higher than when a bonding wire is used.

[0024] In this way, it is difficult to reduce the resistance of the source electrode layer 120 and plated electrode layer 151, which correspond to the surface electrodes of the semiconductor element 110, and the solder layer 152 by using copper clips instead of bonding wires, thereby reducing the on-resistance of the semiconductor device.

[0025] The objective of this specification is to propose a semiconductor device having a low on-resistance by reducing the resistance of the path through which current flows in the surface electrode layer of a semiconductor element, and a method for manufacturing a semiconductor device having a low on-resistance by reducing the resistance of the path through which current flows in the surface electrode layer of a semiconductor element. [Means for solving the problem]

[0026] According to the semiconductor device disclosed in this specification, there is provided a semiconductor element having a surface electrode layer having a first main surface and a second main surface, the semiconductor element having the first main surface exposed as its surface, a first wire electrically connected to the first main surface at a plurality of first connection portions and arranged in a first direction on the first main surface, and a second wire electrically connected to the first main surface at a second connection portion and arranged in a second direction on the first main surface, wherein a second circular equivalent diameter, which is the diameter of a circle having the same cross-sectional area as the cross-sectional area of ​​the second wire, is larger than a first circular equivalent diameter, which is the diameter of a circle having the same cross-sectional area as the cross-sectional area of ​​the first wire.

[0027] In this semiconductor device, the first circular equivalent diameter may be greater than or equal to 4 times and less than or equal to 50 times the thickness of the front electrode layer.

[0028] In the semiconductor device, the first direction and the second direction may intersect.

[0029] In the semiconductor device, the first direction and the second direction may be parallel to each other.

[0030] In this semiconductor device, the first wire and the second wire may be in contact with each other.

[0031] Furthermore, in this semiconductor device, the semiconductor element has an on-resistance Rc, the first connection portion of the first wire and the second connection portion of the second wire are separated by a distance S, and the sheet resistance Rs of a portion of the surface electrode layer in an area surrounding the first connection portion where the first wire is electrically connected to the first main surface by the distance S and the on-resistance Rc may satisfy the relationship 0≦Rs / Rc≦0.2.

[0032] Furthermore, according to a method for manufacturing a semiconductor device disclosed in this specification, there is provided a method for manufacturing a semiconductor device including a surface electrode layer having a first main surface and a second main surface, and including a semiconductor element having the first main surface exposed as its surface, the method including a first step of arranging a first wire having conductivity on the first main surface so as to extend in a first direction and to be electrically connected to the first main surface at a plurality of first connection portions, and a second step of arranging a second wire having conductivity and thicker than the first wire on the first main surface so as to extend in a second direction and to be electrically connected to the first main surface at a second connection portion.

[0033] In this method for manufacturing a semiconductor device, a second step may be carried out after the first step.

[0034] In the method for manufacturing a semiconductor device, the second step may include arranging the second wire on the first main surface so that the second direction intersects with the first direction.

[0035] In the method for manufacturing a semiconductor device, the second step may include arranging the second wire on the first main surface so that the second direction is parallel to the first direction.

[0036] Furthermore, in this method for manufacturing a semiconductor device, the second step may include arranging a second wire on the first main surface so as to be in contact with the first wire. Effect of the Invention

[0037] According to the semiconductor device disclosed in the present specification, the resistance of the path of the current flowing in the front electrode layer of the semiconductor element is reduced, thereby reducing the on-resistance of the semiconductor device.

[0038] Furthermore, according to the method for manufacturing a semiconductor device disclosed in the present specification, the resistance of the path of the current flowing in the front electrode layer of the semiconductor element can be reduced, thereby obtaining a semiconductor device having a low on-resistance. [Brief description of the drawings]

[0039] [Figure 1]FIG. 1 is a plan view showing a conventional semiconductor device; [Diagram 2] 2 is a cross-sectional view taken along line ZZ in FIG. 1. [Diagram 3] FIG. 11 is a cross-sectional view showing another semiconductor device according to the prior art. [Figure 4] 1 is a plan view showing a semiconductor device according to a first embodiment of the present invention. [Diagram 5] 5 is a cross-sectional view taken along line XX in FIG. 4. [Figure 6] 5 is a cross-sectional view taken along line YY in FIG. 4. [Figure 7] 1(A) to (D) are diagrams showing experimental examples. [Figure 8] FIG. 13 is a diagram showing the relationship between on-resistance Ron and the number of source wires. [Figure 9] FIG. 13 is a diagram showing the relationship between the on-resistance Ron and the spacing between source wires. [Figure 10] 4A to 4C are diagrams illustrating a modified example of the semiconductor device according to the first embodiment of the present invention. [Figure 11] FIG. 4 is a plan view showing a semiconductor device according to a second embodiment of the present invention. [Figure 12] 1 is a diagram (part 1) for explaining the relationship between the ratio Rs / Rc of the resistance Rs of the source electrode layer to the on-resistance Rc of the device body and the distance X. FIG. [Figure 13] FIG. 2 is a diagram (part 2) for explaining the relationship between the ratio Rs / Rc of the resistance Rs of the source electrode layer to the on-resistance Rc of the device body and the distance X. [Figure 14] 13A and 13B are diagrams (part 3) illustrating the relationship between the distance X and the ratio Rs / Rc of the resistance Rs of the source electrode layer to the on-resistance Rc of the device body. [Figure 15] FIG. 11 is a diagram showing a modified example of the semiconductor device according to the second embodiment of the present invention. [Figure 16] FIG. 11 is a plan view showing a semiconductor device according to a third embodiment of the present invention. [Figure 17] FIG. 11 is a diagram showing a modified example of the semiconductor device according to the third embodiment of the present invention. [Figure 18] FIG. 2 is a diagram for explaining a process (part 1) of one embodiment of the method for manufacturing a semiconductor device according to the present invention. [Figure 19] 4 is a diagram illustrating a process (part 2) of the embodiment of the method for manufacturing a semiconductor device according to the present invention. FIG. [Figure 20] 4 is a diagram illustrating a third step of the embodiment of the method for manufacturing a semiconductor device according to the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, an embodiment of the semiconductor device disclosed in this specification will be described with reference to the drawings. However, the technical scope of the present invention is not limited to the embodiment, but covers the inventions described in the claims and their equivalents.

[0041] In this specification, in a layer or region marked with n, electrons are the majority carriers, and in a layer or region marked with p, holes are the majority carriers. In addition, + attached to n or p means that the impurity concentration is higher than that of a layer or region not marked with that symbol, and - attached to n or p means that the impurity concentration is lower than that of a layer or region not marked with that symbol.

[0042] Fig. 4 is a plan view showing the first embodiment, Fig. 5 is a cross-sectional view taken along line XX in Fig. 4, and Fig. 6 is a cross-sectional view taken along line YY in Fig. 4.

[0043] The semiconductor device 1 includes a semiconductor element 10, a first wire 30, a second wire 33, a third wire 36, and a circuit board or a lead frame (not shown) on which a back electrode layer (drain electrode layer 19) of the semiconductor element 10 is mounted via a solder layer or a conductive adhesive such as silver paste. As shown in Fig. 4, the semiconductor element 10 has a rectangular shape in a plan view. As shown in Fig. 5, the semiconductor element 10 has a plurality of cells. C1 and C2 shown in Fig. 5 indicate some cells of the semiconductor element 10. The cell refers to the distance between the centers of adjacent trenches 50 in the width direction. For example, the distance between the center of trench 50a in the width direction and the center of trench 50b adjacent to trench 50a in the width direction is defined as cell C1, and the distance between the center of trench 50b in the width direction and the center of trench 50c adjacent to trench 50b in the width direction is defined as cell C2.

[0044] The semiconductor element 10 of this embodiment has a drain electrode layer 19 (rear electrode layer) on its lower surface, and a source electrode layer 20 and a gate electrode layer 21 on its upper surface. The semiconductor element 10 is provided with a breakdown voltage structure region 22 on its outer periphery.

[0045] The drain electrode layer 19 is disposed so as to cover the entire back surface side of the semiconductor element 10. + The drain layer 11 is disposed on the drain electrode layer 19. - The drift layer 12 is + It is disposed on the drain layer 11 .

[0046] The semiconductor element 10 is - From the top surface of the drift layer 12 + The semiconductor device has a plurality of trenches 50 provided at predetermined intervals with the depth direction being the direction toward the drain layer 11. The trenches 50 are provided with a gate insulating film 15 and a gate electrode 14 embedded inside the trenches 50 with the gate insulating film 15 interposed therebetween. Between adjacent trenches 50 - A p-base region 13 is provided in the surface layer of the drift layer 12 and is shallower than the bottom surface of the trench 50 in the depth direction. The surface layer of the p-base region 13 is + The source region 16 is provided so as to be in contact with the gate electrode 14 via the gate insulating film 15. + The source regions 16 are disposed on either side of a trench including the gate electrode 14 and the gate insulating film 15 . Also, adjacent n + Between the source regions 16, p ++ It may have a contact region 17 .

[0047] The gate electrode 14 is electrically connected to the gate electrode layer 21 via a wiring layer (not shown). The interlayer insulating film 18 is disposed between the gate electrode 14 and the source electrode layer 20, and covers the upper part of the gate electrode 14 and the gate insulating film 15.

[0048] n + Drain layer 11 and n - A drift layer 12, a p-base region 13, and an n + A source region 16 and p ++ The contact region 17 is formed by stacking a layer doped with an impurity that imparts p-type polarity (e.g., boron or aluminum) and an impurity that imparts n-type polarity (e.g., phosphorus, arsenic, or antimony) on a silicon substrate, or by injecting the respective impurities into the silicon substrate, or by stacking a semiconductor layer doped with the respective impurities on the silicon substrate.

[0049] The source electrode layer 20 is an example of a surface electrode layer, and is disposed on the surface of the semiconductor element 10. As an example, the source electrode layer 20 has a recess that is recessed inward in a plan view, and the gate electrode layer 21 is disposed in this recess. The source electrode layer 20 and the gate electrode layer 21 may be formed of aluminum, an aluminum alloy, copper, a copper alloy, or other conductive metal, or may be formed by laminating these materials. A breakdown voltage structure region 22 is disposed on the outer periphery of the semiconductor element 10.

[0050] The semiconductor element 10 has a plurality of cells. Cells C1 and C2 shown in FIG. 5 are some of the cells of the semiconductor element 10. The cell refers to the distance between the centers of adjacent trenches 50 in the width direction. The width direction of the trench 50 refers to the distance between the centers of adjacent trenches 50 in the width direction. - From the top surface of the drift layer 12 + This indicates a direction perpendicular to the depth direction of the trench 50 toward the drain layer 11. For example, a cell C1 is defined between the center of the trench 50a in the width direction and the center of the trench 50b in the width direction adjacent to the trench 50a, and a cell C2 is defined between the center of the trench 50b in the width direction and the center of the trench 50c in the width direction adjacent to the trench 50b.

[0051] Among the elements constituting the semiconductor device 1, the first wire 30, the second wire 33, the third wire 36, the circuit board or lead frame (not shown) on which the semiconductor element 10 is mounted, external terminals (not shown) such as the wiring pattern of the circuit board or the lead frame, and a conductive adhesive (not shown) such as a solder layer or silver paste used to mount the drain electrode layer 19 (rear electrode layer) of the semiconductor element 10 on the circuit board or lead frame are not included in the semiconductor element 10.

[0052] The source electrode layer 20 has a first main surface 20a and a second main surface 20b. The second main surface 20b is electrically connected to each of the cells C1 and C2. In the source electrode layer 20, the first main surface 20a is exposed to the outside as the upper surface of the semiconductor element 10. The first main surface 20a is exposed to the outside as the surface of the semiconductor element 10.

[0053] The first wire 30 is conductive and electrically connected to the first main surface 20a of the source electrode layer 20 at a plurality of connection portions 31. The first wire 30 is disposed in a predetermined direction on the first main surface 20a. A plurality of first wires 30 are disposed on the first main surface 20a. The first wire 30 is electrically connected only to the first main surface 20a of the source electrode layer 20, and is not connected to an external terminal (not shown) such as a wiring pattern of a circuit board or a lead frame.

[0054] The connection portion 31 indicates a portion where the first wire 30 and the first main surface 20a of the source electrode layer 20 are joined. One first wire 30 has multiple connection portions 31, and is electrically connected at multiple points on the first main surface 20a of the source electrode layer 20. The multiple connection portions 31 are formed by joining multiple points of the first wire 30 and the first main surface 20a of the source electrode layer 20 using ultrasonic waves, such as wire bonding. A portion of the first wire 30 between two adjacent connection portions 31 does not contact the first main surface 20a. Adjacent connection parts 31 are connected by a first wire 30. When adjacent connection parts 31 are not connected by a first wire 30, the sheet resistance of the source electrode layer 20 at the connection part 31 where the first wire 30 is connected to the first main surface 20a of the source electrode layer 20 is reduced, but the sheet resistance of the source electrode layer 20 at the part between adjacent connection parts 31 is higher than the sheet resistance of the source electrode layer 20 at the connection part 31. Therefore, in the connection part 31 away from the second wire 33 described later, the resistance of the source electrode layer 20 between this connection part 31 and the first wire 33 is high, and the on-resistance of the semiconductor device 1 is high. Therefore, by connecting the adjacent connection portions 31 with the first wire 30, the resistance of the source electrode layer 20 between the connection portion 31 distant from the second wire 33 and the second wire 33 can be reduced. This makes it possible to obtain the same effect as that obtained by increasing the thickness of the source electrode layer 20 to reduce the resistance of the path of the current flowing through the source electrode layer 20. Furthermore, the narrower the interval between adjacent connection parts 31, the smaller the resistance of the path of the current flowing through the source electrode layer 20 can be. The first wire 30 may be in contact with the first main surface 20a of the source electrode layer 20 between the two connection portions 31. The larger the area of ​​the connection portion 31 where the first wire 30 and the first main surface 20a of the source electrode layer 20 are joined (the joining area between the first main surface 20a of the source electrode layer 20 and the first wire 30), the smaller the resistance of the path of the current flowing in the source electrode layer 20. For this reason, the area of ​​one connection portion 31 is increased, or a bonding area between the first wire 30 and the first main surface 20a is increased by providing multiple connection portions 31. This reduces the resistance of the path of the current flowing through the source electrode layer 20, and the on-resistance of the semiconductor device 1 can be reduced.

[0055] The first wire 30 has a connection periphery 32 around the connection portion 31. The connection periphery 32 is provided in the direction in which the multiple connection portions 31 provided on one first wire 30 are arranged (the direction in which the first wire 30 extends). The connection periphery 32 indicates the boundary between the crushed and non-crushed areas of the first wire 30 when the connection 31 is formed, for example, when the connection 31 is formed using ultrasound, such as by wire bonding. It is not necessary to provide the connection periphery 32 in a direction perpendicular to the direction in which the multiple connection parts 31 are arranged. For example, when the connection parts 31 are formed using ultrasonic waves as in wire bonding, the upper part of the connection part 31 of the first wire 30 may be entirely crushed by ultrasonic waves in the direction perpendicular to the direction in which the multiple connection parts 31 are arranged. 4, the end 30a of the first wire 30 may be in contact with a side surface 33b of a second wire 33 described later. When the end 30a of the first wire 30 is in contact with the side surface 33b of the second wire 33, the first wire 30 and the second wire 33 are electrically connected to each other. This can further reduce the resistance of the current path flowing in the source electrode layer 20, and can reduce the on-resistance of the semiconductor device 1. The side surface 33b of the second wire 33 indicates the side surface of the connection portion .

[0056] A plurality of first wires 30 are connected onto the first main surface 20a of the source electrode layer 20 of the semiconductor element 10. The plurality of first wires 30 each have a plurality of connection portions 31 and are electrically connected to the first main surface 20a of the source electrode layer 20. The resistance of the first wire 30 itself is preferably small. Also, the larger the diameter of the first wire 30, the lower the resistance of the first wire 30. The cross-sectional shape of the wire that is the material for forming the first wire 30 is usually circular, and the cross-sectional area is approximately constant in the longitudinal direction. As the material for forming the first wire 30, a conductive wire that has a constant diameter and a circular cross-sectional shape is used. When a ribbon-type wire is used as the material for forming the first wire 30, the cross-sectional shape of the wire will be a shape other than circular. Even if a wire with a circular cross section is used as the material, the connection portion 31 of the first wire 30 is formed using ultrasonic waves, for example, as in wire bonding, so that the cross-sectional shape of the connection portion 31 in the direction perpendicular to the direction in which the multiple connection portions 31 of the first wire 30 are arranged will not be circular. Therefore, when defining the relationship between the thickness of the first wire 30 and the thickness of the source electrode layer 20, a circular equivalent diameter is used. The circular equivalent diameter of the first wire 30 is the thickness of the cross section of the first wire converted into the diameter of a wire having a circular cross section that has the same cross section area as the cross section area of ​​the first wire 30. For example, the circular equivalent diameter may be the diameter of a circular wire having the same cross section area as the cross section area of ​​the connection portion 31 of the first wire 30. The circle equivalent diameter of the first wire 30 may be four times or more the thickness of the source electrode layer 20, and may be eight times or more. The thickness of the source electrode layer 20 is n + The thickness from the upper surface of the source region 16 to the upper surface (first major surface 20a) of the source electrode layer 20 is shown. By making the circular equivalent diameter of the cross section of the first wire 30 four or more times the thickness of the source electrode layer 20, the resistance of the first wire 30 electrically connected to the source electrode layer 20 at the connection portion 31 can be made sufficiently low. Furthermore, since one first wire 30 has multiple connection parts 31, the area (joining area) where the first wire 30 and the first main surface 20a of the source electrode layer 20 are joined together is increased. The larger the area (joining area) where the first wire 30 and the first main surface 20a of the source electrode layer 20 are joined together, the lower the resistance between the first wire 30 and the source electrode layer 20 can be. Furthermore, since the semiconductor element 10 includes multiple first wires 30 each having multiple connection parts 31, the resistance between the first wires 30 and the source electrode layer 20 can be further reduced. The upper limit of the equivalent circle diameter of the cross section of the first wire 30 may be 30 times or less, or 50 times or less, the thickness of the source electrode layer 20 . In FIG. 5 and cross-sectional views described later, the source electrode layer 20 is shown to be thicker than it actually is in order to make the structure of the semiconductor element 10 easier to understand. The cross-sectional shape of the first wire 30 depends on the cross-sectional shape of the wire material. The connection portion 31 has a cross-sectional shape in which the wire is crushed in a direction perpendicular to the direction in which the multiple connection portions 31 are arranged, because the first wire 30 and the first main surface 20a of the source electrode layer 20 are joined by ultrasonic waves, for example, like wire bonding, regardless of the cross-sectional shape of the first wire 30, such as circular or rectangular.

[0057] The number of connection parts 31 of the first wire 30 is large, so that the area where the first wire 30 and the first main surface 20a of the source electrode layer 20 are joined is large. The larger the area where the first wire 30 and the first main surface 20a of the source electrode layer 20 are electrically connected over a large area. This can reduce the resistance between the first wire 30 and the first main surface 20a of the source electrode layer 20. For example, the first wire 30 having two connection parts 31 electrically connects two parts of the first main surface 20a of the source electrode layer 20. Furthermore, the first wire 30 having three connection parts 31 electrically connects three parts of the first main surface 20a of the source electrode layer 20. Furthermore, the first wire 30 having four or more connection parts 31 electrically connects four or more parts of the first main surface 20a of the source electrode layer 20. Providing a plurality of connection portions 31 for one first wire 30 increases the area in which the first wire 30 and the first main surface 20a of the source electrode layer 20 are electrically connected.

[0058] In addition, since the area of ​​each connection portion 31 is large, it is possible to reduce the resistance between the first wire 30 and the source electrode layer 20. The relationship between the area of ​​the connection portion 31 and the circular equivalent diameter of the first wire 30 is expressed as follows: (area of ​​connection portion 31)>π×((circular equivalent diameter of first wire 30) / 2)×1.2 2The relationship between the area of ​​the connection portion 31 and the thickness of the source electrode layer 20 may be (area of ​​the connection portion 31)>((3600 / (thickness of the source electrode layer 20)). The shape of the connection portion 31 is such that it is wide in a direction perpendicular to the direction in which the multiple connection portions 31 are arranged on one first wire 30, thereby making it possible to further reduce the resistance between the first wire 30 and the source electrode layer 20.

[0059] The first wire 30 may be made of, for example, aluminum, an aluminum alloy, copper, or a copper alloy. The equivalent circle diameter of the cross section of the first wire 30 may be 10 μm or more and 200 μm or less, or may be 10 μm or more and 80 μm or less. When the equivalent circle diameter is 10 μm or more, the resistance of the first wire 30 can be reduced. Furthermore, when the equivalent circle diameter is 200 μm or less, the process of disposing the second wire 33, which will be described later, on the first main surface 20a of the source electrode layer 20 becomes easier. The larger the area (joint area) of the connection portion 31 where the first wire 30 and the first main surface 20a of the source electrode layer 20 are joined, the smaller the resistance of the path of the current flowing through the source electrode layer 20. Therefore, the area of ​​one connection portion 31 is increased, or a plurality of connection portions 31 is provided to increase the total area of ​​the connection portions 31. This reduces the resistance of the path of the current flowing through the source electrode layer 20, thereby reducing the on-resistance of the semiconductor device 1. Furthermore, by increasing the equivalent circular diameter of the first wire 30 (the diameter if the first wire 30 is circular), the resistance of the path of the current flowing to the source electrode layer 20 can be reduced, and the on-resistance of the semiconductor device 1 can be reduced.

[0060] The second wire 33 is conductive. The second wire 33 may be arranged in a direction intersecting a direction in which the multiple connection portions 31 of the first wire 30 are arranged on the first main surface 20a of the source electrode layer 20 (a direction in which the first wire 30 extends). In the plan view shown in FIG. 4, the second wire 33 is disposed on the first main surface 20a of the source electrode layer 20 so as to extend in a direction perpendicular to the direction in which the first wire 30 extends. The equivalent circle diameter of the second wire 33 is larger than the equivalent circle diameter of the first wire 30 . Therefore, the equivalent circle diameter of the cross section of connection portion 34 of second wire 33 is larger than the equivalent circle diameter of the cross section of connection portion 31 of first wire 30. Here, the cross section of connection portion 31 of first wire 30 indicates a cross section in a direction perpendicular to the extension direction of first wire 30. The cross section of connection portion 34 of second wire 33 indicates a cross section in a direction perpendicular to the extension direction of second wire 33. A plurality of second wires 33 may be disposed on the first main surface 20a of the source electrode layer 20. The second wires 33 may have a plurality of connection portions 34 electrically connected to the first main surface 20a of the source electrode layer 20. The connection portions 34 indicate portions where the second wires 33 and the source electrode layer 20 are joined. One end of the second wire 33 is electrically connected to the source electrode layer 20, and the other end is a bonding wire that is electrically connected to an external terminal (not shown) such as a wiring pattern of a circuit board or a lead frame. The second wires 33 may be connected to the first main surface 20a of the source electrode layer 20 in fewer numbers than the first wires 30. In addition, the number of connection portions 34 of the second wires 33 may be fewer than the connection portions 31 of the first wires 30. The circle equivalent diameter of the first wire 30 is smaller than the circle equivalent diameter of the second wire 33. When the first wire 30 and the second wire 33 are circular, the circle equivalent diameter corresponds to the diameter of the circular wire. In this way, the first wire 30 is connected (joined) to the first main surface 20a of the source electrode layer 20 to form the connection portion 31. Furthermore, the fact that the circle equivalent diameter of the first wire 30 is smaller than the circle equivalent diameter of the second wire 33 makes it possible to reduce damage to the semiconductor element 10 when the first wire 30 is cut after the connection portion 31 is formed.

[0061] The multiple connection parts 34 are formed by disposing the second wire 33 on the first main surface 20a of the source electrode layer 20 and electrically connecting multiple points of the second wire 33 to the first main surface 20a of the source electrode layer 20 using ultrasonic waves, such as wire bonding. The number of connection parts 34 that the second wire 33 has may be one or more. In one second wire 33, a portion of the second wire 33 between two adjacent connection parts 34 does not contact the first main surface 20a of the source electrode layer 20.

[0062] Similar to the first wire 30, the second wire 33 also has a connection periphery 35 around the connection portion 34. As shown in Fig. 6, the connection periphery 35 is provided in the direction in which the multiple connection portions 34 provided on one second wire 33 are arranged (the direction in which the second wire 30 extends). The connection peripheral portion 35 indicates the boundary between the crushed and non-crushed areas of the second wire 33 at the upper portion of the connection portion 34 of the second wire 33 when the connection portion 34 is formed using ultrasound, for example, by wire bonding. It is not necessary to provide the connection periphery 35 in a direction perpendicular to the direction in which the multiple connection parts 34 are arranged. For example, when the connection parts 34 are formed using ultrasonic waves as in wire bonding, the upper part of the connection part 34 of the second wire 33 may be completely crushed by the ultrasonic waves in the direction perpendicular to the direction in which the multiple connection parts 34 are arranged.

[0063] The first wire 30 shown in FIG. 4 has end portions 30a at both ends in the direction in which the first wire 30 extends. The first wire 30 has a pair of opposing side surfaces 30b along the direction in which the first wire 30 extends. The second wire 33 shown in FIG. 4 has one end portion 33a in the direction in which the second wire 33 extends. The second wire 33 has a pair of opposing side surfaces 33b along the direction in which the second wire 33 extends. As shown in FIG. 4, the end portion 33a of the second wire 33 may be in contact with the side surfaces 30b of the first wire 30. The end 33a of the second wire 33 comes into contact with the side surface 30b of the first wire 30, thereby electrically connecting the first wire 30 and the second wire 33. This makes it possible to further reduce the resistance of the current path flowing through the source electrode layer 20, and thus reduce the on-resistance of the semiconductor device 1.

[0064] The second wire 33 may be made of, for example, aluminum, an aluminum alloy, copper, or a copper alloy. The cross section of the second wire 33 may have a circular equivalent diameter of 150 μm or more and 500 μm or less, or may have a circular equivalent diameter of 200 μm or more and 500 μm or less. By having a circular equivalent diameter of 150 μm or more, sufficient power can be supplied from an external terminal to the source electrode layer 20. Furthermore, by having a circular equivalent diameter of 500 μm or less, the second wire 33 becomes easy to handle. Therefore, the process of placing the second wire 33 on the first main surface 20a of the source electrode layer 20 becomes easy. Furthermore, if the circular equivalent diameter is 500 μm or more, damage caused during wire bonding becomes large, and it is necessary to increase the thickness of the source electrode layer 20. In addition, it is necessary to increase the size of the wiring pattern of the circuit board or the portion to which the wire of the external terminal of the lead frame or the like is connected.

[0065] The third wire 36 is electrically conductive and is disposed on the gate electrode layer 21 so as to extend parallel to the direction in which the second wire 33 extends. The third wire 36 has a connection portion 37 that electrically connects to the gate electrode layer 21. The connection portion 37 indicates the portion where the third wire 36 and the gate electrode layer 21 are joined. One end of the third wire 36 is electrically connected to the gate electrode layer 21, and the other end of the third wire 36 is a bonding wire that is electrically connected to an external terminal (not shown) such as a wiring pattern of a circuit board or a lead frame. The third wire 36 may be made of, for example, aluminum, an aluminum alloy, copper, a copper alloy, or gold.

[0066] The semiconductor element 10 of FIG. 5 includes a plurality of cells having the same structure. Here, the following description focuses on two cells C1 and C2 that are different in distance from the end 34a of the connection portion 34 of the second wire 33. Although the cells C1 and C2 have the same structure, the position of the cell C2 is farther from the end 34a of the connection portion 34 of the second wire 33 than the position of the cell C1. Note that the plurality of cells of the semiconductor element 10 do not all have to have the same structure. The end 34a of the connection portion 34 of the second wire 33 indicates the end of the portion where the source electrode layer 20 and the second wire 33 are joined in the cross-sectional view in the direction perpendicular to the direction in which the second wire 33 extends shown in FIG. 5.

[0067] During operation of the semiconductor device 1, in the cells C1 and C2, a voltage equal to or higher than the threshold voltage is applied to the gate electrode 14 via the third wire 36 and the gate electrode layer 21, so that n + A current flows through the source region 16 . In cell C2, the current flows through the following path: + A first path L1 that flows from the source region 16 through the source electrode layer 20 to the end 34a of the connection portion 34 of the second wire 33; + It has a second path L2 that flows from the source region 16 to the source electrode layer 20, from the connection portion 31 to the first wire 30, and from the connection portion 31 of the first wire 30 via the source electrode 20 to the end portion 34a of the connection portion 34 of the second wire 33. When the end 30a of the first wire 30 and the side surface 33b of the second wire 33 are electrically connected, n + It further has a third path L3 that flows from the source region 16 to the source electrode layer 20, from the connection portion 31 to the first wire 30, from the end portion 30a of the first wire 30, via the side portion 33b of the second wire 33, to the end portion 34a of the connection portion 34 of the second wire 33. Since the connection portion 31 of the first wire 30 is electrically connected to the first main surface 20a of the source electrode layer, the resistance of the first wire 30 in the second path L2 and the third path L3 is smaller than the sheet resistance of the first path L1 in which the current flows from the cell C2 to the end 34a of the connection portion 34 of the second wire 33 through the source electrode layer 20. Therefore, in the cell C2, when the end 30a of the first wire 30 and the side surface 33b of the second wire 33 are not electrically connected, the current mainly flows through the second path L2 to n + The current flowing from the source region 16 to the second wire 33 becomes large. When the end 30a of the first wire 30 and the side surface 33b of the second wire 33 are electrically connected, the current mainly passes through the third path, + The current flowing from the source region 16 to the second wire 33 becomes large.

[0068] In the cells C1 and C2, the drain electrode layer 19 to n + The resistance r0 of the path through which a current flows to the source region 16 and the resistance r1 in the thickness direction of the source electrode layer 20 are the same. The resistance of the first wire 30 in the second path L2 and the third path L3 can be lowered as the area of ​​the connection portion 31 connecting the first wire 30 and the first main surface 20a of the source electrode layer 20 is larger. Thus, by providing the semiconductor element 10 with a plurality of first wires 30 having a plurality of connection portions 31 on the first main surface 20a of the source electrode layer 20, it is possible to obtain an effect similar to that obtained when the thickness of the source electrode layer 20 is increased to reduce the resistance of the source electrode layer 20.

[0069] Furthermore, by arranging the first wire 30 having a plurality of connection portions 31 in a direction perpendicular to the extending direction of the second wire 33, it is possible to arrange more connection portions 31 at which the first wire 30 and the first main surface 20a of the source electrode layer 20 are connected. This makes it possible to increase the bonding area between the first wire 30 and the first main surface 20a of the source electrode layer 20. Furthermore, by arranging the first wire 30 having multiple connection portions 31 in a direction perpendicular to the direction in which the second wire 33 extends, the ends 30a of the multiple first wires 30 and the sides 33b of the second wire 33 can be electrically connected to provide multiple third paths L3. Therefore, by arranging the first wire 30 having the multiple connection parts 31 in a direction perpendicular to the direction in which the second wire 33 extends, the resistance between the first wire 30 and the source electrode layer 20 can be further reduced, and the same effect as when the thickness of the source electrode layer 20 is substantially increased can be easily obtained. This makes it possible to reduce the on-resistance of the semiconductor device 1 without changing the structure or manufacturing process of the semiconductor device 1.

[0070] Next, it will be shown that the on-resistance of the semiconductor element 10 decreases according to the number of the first wires 30 and second wires 33 and the number of connecting parts. Fig. 7 shows an experimental example of source wires 40 corresponding to second wires 33 connected onto source electrode layer 20. Fig. 8 shows the relationship between on-resistance Ron of semiconductor element 10 and the number of source wires 40. Fig. 9 shows the relationship between on-resistance Ron and the spacing between source wires.

[0071] 7(A), one side of a source wire 40a is connected onto the source electrode layer 20 of the semiconductor element 10, and one side of a gate wire 41 is connected onto the gate electrode layer 21. The other side of the source wire 40a is connected to a source probe terminal (not shown), and the other side of the gate wire 41 is connected to a gate probe terminal (not shown). Then, the drain electrode layer 19 of the semiconductor element 10 is mounted so as to be electrically connected to a die pad (not shown) for measurement, and the semiconductor element 10 is operated to measure the on-resistance.

[0072] 7(B), one of the source wire 40a and the source wire 40b is connected with a gap therebetween onto the source electrode layer 20 of the semiconductor element 10. The other of the source wire 40a and the source wire 40b is connected to a source probe terminal (not shown), and the source wire 40a and the source wire 40b are at the same potential. One end of a gate wire 41 is connected onto the gate electrode layer 21. The other end of the gate wire 41 is connected to a gate probe terminal (not shown). The drain electrode layer 19 of the semiconductor element 10 is mounted so as to be electrically connected to a die pad for measurement (not shown), and the semiconductor element 10 is operated to measure the on-resistance.

[0073] 7(C), one of source wire 40a, source wire 40b, and source wire 40c is connected at equal intervals onto source electrode layer 20 of semiconductor element 10. The other of source wire 40a, source wire 40b, and source wire 40c is connected to a source probe terminal (not shown), and source wire 40a, source wire 40b, and source wire 40c are at the same potential. One end of a gate wire 41 is connected onto the gate electrode layer 21. The other end of the gate wire 41 is connected to a gate probe terminal (not shown). The drain electrode layer 19 of the semiconductor element 10 is mounted so as to be electrically connected to a die pad for measurement (not shown), and the semiconductor element 10 is operated to measure the on-resistance.

[0074] 7(D), one of source wire 40a, source wire 40b, source wire 40c, and source wire 40d is connected at equal intervals onto source electrode layer 20 of semiconductor element 10. The other of source wire 40a, source wire 40b, source wire 40c, and source wire 40d is connected to a source probe terminal (not shown), and source wire 40a, source wire 40b, source wire 40c, and source wire 40d are at the same potential. One end of a gate wire 41 is connected onto the gate electrode layer 21. The other end of the gate wire 41 is connected to a gate probe terminal (not shown). The drain electrode layer 19 of the semiconductor element 10 is mounted so as to be electrically connected to a die pad for measurement (not shown), and the semiconductor element 10 is operated to measure the on-resistance.

[0075] FIG. 8 shows the relationship between the on-resistance Ron and the number of source wires 40. The on-resistance Ron on the vertical axis indicates the value obtained by subtracting the resistance of the source wires 40 and the resistance of the measurement die pad on which the semiconductor element 10 is mounted from the on-resistance measured in FIG. 7 to obtain only the on-resistance of the semiconductor element 10. As shown in FIG. 8, it was confirmed that the on-resistance Ron decreases as the number of source wires connected to the first main surface 20a of the source electrode layer 20 increases. Since each source wire is at the same potential, an increase in the number of source wires corresponds to an increase in the number of connection parts 34 of the second wires 33. An increase in the number of source wires 40 corresponds to an increase in the area where the source electrode layer 20 and the second wires 33 are electrically connected. This result can be substituted for the first wire 30. Therefore, by increasing the area where the source electrode layer 20 and the first wire 30 are electrically connected, the on-resistance of the semiconductor element 10 can be reduced. Furthermore, the area where the source electrode layer 20 and the first wire 30 are electrically connected increases, and at the same time, the distance between the first wire 30 and the second wire 33 decreases. This shortens the path of the current flowing through the source electrode layer 20, which has a high resistance, and the on-resistance of the semiconductor element 10 can be reduced.

[0076] 9 shows the relationship between the on-resistance Ron and the spacing between the source wires 40. When there is one source wire 40 (see FIG. 7(A)), the distance between the source wire 40a and the end of the source electrode layer 20 is taken as the spacing between the source wires 40a. The on-resistance Ron on the vertical axis indicates the value obtained by subtracting the resistance of the source wire 40 and the resistance of the measurement die pad on which the semiconductor element 10 is mounted from the on-resistance measured in FIG. 7 to find only the on-resistance of the semiconductor element 10. As shown in FIG. 9, it was confirmed that the on-resistance Ron of the semiconductor element 10 decreases as the spacing between the source wires 40 decreases (becomes narrower). This result can be substituted for the first wire 30. Therefore, the smaller the interval between the connection parts 31 of the first wire 30 electrically connected to the source electrode layer 20 (the narrower the interval), the more the on-resistance of the semiconductor element 10 can be reduced. Also, the smaller the interval between the multiple first wires 30 electrically connected to the source electrode layer 20 (the narrower the interval), the more the on-resistance of the semiconductor element 10 can be reduced.

[0077] According to the semiconductor device of the present embodiment described above, an effect of having a low on-resistance is achieved.

[0078] 10 is a diagram showing a modified example of the semiconductor device of the first embodiment. In the semiconductor device 1 of this modified example, the direction in which the first wire 30 extends is parallel to the direction in which the second wire 33 extends. The side surface 30b of the connection portion 31 of the first wire 30 contacts and is electrically connected to the side surface 33b of the connection portion 34 of the second wire 33. The first wire 30 having the multiple connection portions 31 is electrically connected to the second wire 33 in the direction in which the first wire 30 extends. Therefore, the multiple connection portions 31 of the first wire 30 and the second wire 33 are electrically connected on the first main surface 20a of the source electrode layer 20.

[0079] Next, other embodiments of the above-mentioned semiconductor device will be described with reference to Figures 11 to 17. For points not specifically described in the other embodiments, the detailed description of the above-mentioned first embodiment is applied as appropriate. In addition, the same components are given the same reference numerals.

[0080] FIG. 11 is a plan view showing a semiconductor device according to the second embodiment of the present invention.

[0081] The semiconductor device 1 of this embodiment is different from the first embodiment in that the first wire 30 is not in physical contact (connected) with the second wire 33. The first wire 30 shown in FIG. 11 has ends 30a, 30a at both ends in the direction in which the first wire 30 extends. The connection portion 31 closest to the end 30a in the first wire 30 has two ends 31a, 31c that face each other in the direction in which the first wire 30 extends. The end 31a is located outside (toward the end 30a) of the first wire 30, and the end 31c is located inside. In addition, among the multiple connection portions 31 of the first wire 30, the connection portion 31 that is located inside the connection portion 31 closest to the end 30a has a pair of ends 31c, 31c that face each other in the direction in which the first wire 30 extends. The connection portion 31 of the first wire 30 has two ends 31b, 31b that face each other in a direction perpendicular to the direction in which the first wire 30 extends. The first wire 30 has a pair of side surfaces 30b that face each other along the direction in which the first wire 30 extends. The second wire 33 shown in FIG. 11 has one end 33a in the direction in which the second wire 33 extends. The connection portion 34 closest to the end 33a of the second wire 33 has two ends 34b, 34c that face each other in the direction in which the second wire 33 extends. The end 34b is located outside the second wire 33, and the end 34c is located inside. In addition, among the multiple connection portions 34 of the second wire 33, the connection portion 34 that is located inside the connection portion 34 closest to the end 33a has a pair of ends 34c, 34c that face each other in the direction in which the second wire 33 extends. The second wire 33 has a pair of side surfaces 33b that face each other along the direction in which the second wire 33 extends. The connection portion 34 of the second wire 33 has a pair of ends 34a, 34a that face each other in a direction perpendicular to the direction in which the second wire 33 extends. A side surface 30b of the connection portion 31 of the first wire 30 and an end portion 33a of the second wire 33 are spaced apart from each other. The end 30a of the first wire 30 and the side surface 33b of the connection portion 34 of the second wire 33 are spaced apart by a distance S1. Further, the end 31a of the connection portion 31 provided at a position closest to the end 30a of the first wire 30 and the end 34a of the connection portion 34 of the second wire 33 are spaced apart by a distance S3. The shorter the distance S1 and the distance S3 are, the smaller the resistance of the portion of the source electrode layer 20 between the second wire 33 and the first wire 30 can be.

[0082] The on-resistance of the semiconductor element 10 and the resistance (sheet resistance) of the source electrode layer 20 will be described using the example shown in FIG. In FIG. 11, all of the connection portions 34 of the second wires 33 are electrically connected to the first main surface 20a of the source electrode layer 20, and all of the connection portions 31 of the first wires 30 are electrically connected to the first main surface 20a of the source electrode layer 20. Here, the on-resistance of the semiconductor element 10 is defined as Rc. The resistance (sheet resistance) of a region 20c defined by a distance S3 between a connection portion 31 at which the first wire 30 is electrically connected to the first main surface 20a of the source electrode layer 20 and an end portion 31a of the connection portion 31 and an end portion 34a of a connection portion 34 of a second wire 33 opposed to the end portion 31a is defined as Rs. The on-resistance Rc of the semiconductor element 10 and the resistance Rs of the region 20c surrounding the connection portion 31 of the first wire 30 need only satisfy the relationship 0≦Rs / Rc≦0.2.

[0083] The above-mentioned relationship will be described below with reference to Figures 12 to 14. Note that Figures 12 to 14 show a case in which the first wire 30, like the second wire 33, is connected to a source terminal (not shown). 12 and 13 each show a different shape of the connection portion 31 at which the first wire 30 is electrically connected to the first main surface 20a of the source electrode layer 20. Figures 14(A) and 14(B) show the relationship between the distance X and the ratio Rs / Rc of the resistance Rs of the source electrode layer 20 to the on-resistance Rc of the semiconductor element 10 for each of the shapes of the connection portion 31 shown in Figures 12 and 13.

[0084] 12, a plurality of first wires 30 are arranged to straddle opposing ends of the source electrode layer 20. The first wires 30 and the first main surface 20a of the source electrode layer 20 are electrically connected to each other at connection portions 31 of the first wires 30. 12, for ease of understanding, the first wire 30 has one connection portion 31, and the illustration of the connection periphery 32 is omitted. Also, the illustration of the second wire 33 provided between adjacent first wires 30 is omitted, and the adjacent first wires 30 are spaced equally apart. The equivalent circular diameter of the first wire 30 is defined as a. This equivalent circular diameter may be the diameter of the wire when the cross-sectional shape of the first wire 30 is circular, or may be the width of the surface connected to the first main surface 20a of the source electrode layer 20 when the cross-sectional shape is rectangular, such as a ribbon wire. The length of the connection portion 31 between the opposing ends of the source electrode layer 20 is defined as L. In adjacent first wires 30, the distance X is defined as half the distance between the ends 31b of the connection portion 31 in a direction perpendicular to the extension direction of the first wires 30. The on-resistance RonA per unit area of ​​the semiconductor element 10 is denoted by α. The on-resistance Rc of the region including the region 20c and the connection portion 31 (the on-resistance Rc of the semiconductor element 10 up to a distance X that is ½ the distance between the ends 31b of the connection portion 31) is expressed by the following formula (1).

[0085] Rc = α / ((k1 × a + 2X) × L) (1)

[0086] Here, k1 is a parameter that is determined based on the conditions for forming the connection portion 31 of the first wire 30. (k1×a) indicates the width of the area of ​​connection portion 31, which depends on the circle equivalent diameter a of first wire 20. Therefore, on-resistance Rc is the on-resistance of the region consisting of region 20c indicated by the dashed line in FIG.

[0087] Moreover, the cross-sectional area of ​​the source electrode layer 20 in the region 20c surrounding the connection portion 31 in the direction perpendicular to the longitudinal direction of the first wire 30 is denoted by s′, and the resistivity of the source electrode layer 20 is denoted by ρ. The thickness t of the source electrode layer 20 is n + This is the thickness from the upper surface of the source region 16 to the upper surface (first major surface 20a) of the source electrode layer 20. The resistance Rs of the region 20c of the source electrode layer 20 that is a distance X away from the end 31b of the connection portion 31 of the first wire 30 is expressed by the following formula (2). The resistance Rs is the resistance of the portion excluding the connection portion 31 from the region 20c indicated by the dotted line in FIG.

[0088] Rs=ρ×X / s'=ρ×X / (2×L×t) (2)

[0089] Therefore, the resistance Rs is the resistance of the region 20c in a direction perpendicular to the longitudinal direction of the first wire 30 (the horizontal direction in FIG. 12). 14(A) is a diagram showing the relationship between the distance X and the ratio Rs / Rc of the resistance Rs of the source electrode layer 20 to the on-resistance Rc of the semiconductor element 10 when the interval between the connection portion 31 of the first wire 30 and the connection portion 34 of the second wire 33 is narrow, for example, 200 μm or less, and the areas of the connection portions 31 and 34 (the junction areas where the source electrode layer 20 is junctioned with the first wire 30 and the second wire 33) are large. The ratio Rs / Rc increases with an increase in the distance X. The ratio Rs / Rc being zero (0=Rs / Rc) indicates a state in which the second wire 33 is connected between adjacent first wires 30, and the first wire 30 and the second wire 33 are in contact with each other and electrically connected.

[0090] 13, a plurality of first wires 30 are disposed on the first main surface 20a of the source electrode layer 20. The first wires 30 and the first main surface 20a of the source electrode layer 20 are electrically connected to each other at connection portions 31 of the first wires 30. 13, for ease of understanding, the first wire 30 has one connection portion 31, and the illustration of the connection periphery 32 is omitted. Also, the illustration of the second wire 33 provided between adjacent first wires 30 is omitted, and the adjacent first wires 30 are spaced equally apart. In the first wire 30 shown in FIG. 13, the area where the connection portion 31 is connected to the first main surface 20a of the source electrode layer 20 is smaller than that of the first wire 30 shown in FIG. The equivalent circular diameter of the first wire 30 is defined as a. This equivalent circular diameter may be, for example, the diameter of the wire when the cross-sectional shape of the first wire 30 is circular, or the width of the surface connected to the first main surface 20a of the source electrode layer 20 when the cross-sectional shape is rectangular, such as a ribbon wire. In adjacent first wires 30, distance X is defined as half the distance between ends 31b of connection portions 31 in a direction perpendicular to the direction in which the first wires 30 extend. If the on-resistance RonA per unit area of ​​the semiconductor element 10 is α, the on-resistance Rc of the region 20c and the connection portion 31 (the on-resistance Rc of the semiconductor element 10 up to a distance X that is 1 / 2 the distance between the ends 31b of the connection portion 31) is expressed by the following equation (3).

[0091] Rc=α / ((k1×a+2X)(L+2X))=α / (k2×a 2 +k3×a×X+4X 2 ) (3)

[0092] Here, k2 and k3 are parameters that are determined based on the conditions for forming the connection portion 31 of the first wire 30. The length L of the connection portion 31 is ky×a (Ky is a constant according to the forming conditions of the connection portion 31), and ky is k2 and k3. The on-resistance Rc is the on-resistance of the region consisting of the connection portion 31 and the region 20c indicated by the dashed line in FIG.

[0093] Moreover, the cross-sectional area of ​​the source electrode layer 20 in the region 20c surrounding the connection portion 31 in the direction perpendicular to the longitudinal direction of the first wire 30 is denoted by s′, and the resistivity of the source electrode layer 20 is denoted by ρ. The thickness t of the source electrode layer 20 is n + This is the thickness from the upper surface of the source region 16 to the upper surface (first major surface 20a) of the source electrode layer 20. The resistance Rs of the region 20c that is a distance X outward from the end 31b of the connection portion 31 of the first wire 30 is expressed by the following formula (4). The resistance Rs is the resistance of the portion of the region 20c indicated by the dotted line in FIG. 13 excluding the connection portion 31.

[0094] Rs=ρ×X / s'=ρ×X / (2((k1×a+2X)+(L+2X))×t)=ρ×X / (2(k4×a+X)×t) (4)

[0095] Here, k4 is a parameter determined based on the conditions for forming the connection portion 31 of the first wire 30. Therefore, the resistance Rs is the resistance in the direction perpendicular to the longitudinal direction of the first wire 30 in the region 20c surrounding the connection portion 31.

[0096] FIG. 14(B) is a diagram showing the relationship between the distance X and the ratio Rs / Rc of the resistance Rs of the source electrode layer 20 to the on-resistance Rc of the semiconductor element 10 when the spacing between the connection portion 31 of the first wire 30 and the connection portion 34 of the second wire 33 is, for example, greater than 200 μm and the areas of the connection portions 31 and 34 (the junction areas where the source electrode layer 20 is joined to the first wire 30 and the second wire 33) are small.

[0097] 14(A) and 14(B), when the ratio Rs / Rc is 0.2 (corresponding to 20%) or less, particularly 0.1 (corresponding to 10%) or less, the second wire 33 is electrically connected with low resistance to a wide area of ​​the first main surface 20a of the source electrode layer 20 via the multiple connection portions 31 of the first wire 30. The ratio Rs / Rc becomes 0.2 or less when the distance X is about 140 μm or less in the example shown in FIG. 14(A), and when the distance X is about 250 μm or less in the example shown in FIG. 14(B). 14(A) and 14(B), the value of distance X at which the ratio Rs / Rc is the same is larger in FIG 14(B). This is because in FIG 14(B), the areas of connection parts 31 and 34 (the junction areas where source electrode layer 20 is junctioned with first wire 30 and second wire 33) are smaller, and the value of Rc is larger. Therefore, the on-resistance of semiconductor element 10 is higher in the case of FIG 14(B).

[0098] The interval between the ends 31b of the connections 31 of the adjacent first wires 33 shown in FIG. 12 corresponds to twice the distance X, and it is preferable that the interval between the ends 31b of the adjacent connections 31 be 280 μm or less.

[0099] In addition, in one first wire 30 having a plurality of connection portions 31 as shown in FIG. 11, the spacing S2 between the ends 31c of two adjacent connection portions 31 need only satisfy 0≦Rs / Rc≦0.2 and be equal to or less than twice the distance X determined so that the ratio Rs / Rc is equal to or less than 0.2. The narrower the interval 2S, the smaller the resistance of the path of the current flowing through the source electrode layer 20. For example, the interval S2 is preferably 200 μm or less (the distance X is 100 μm or less). The portion between two adjacent connection portions 31 of the first wire 30 is not connected to the first main surface 20a of the source electrode layer 20, but a good electrical connection is obtained with the second wire 33 via the first wire 30. This makes it possible to reduce the resistance between the first wire 30 and the source electrode layer 20. 12 and 13, the second wire 33 is omitted, but the above description of the first wire 30 and the connection portion 31 also applies to the second wire 33 and the connection portion 34 as appropriate. The above is the description of the relationship 0≦Rs / Rc≦0.2. Next, the relationship between this relationship and the semiconductor device 1 shown in FIG. 11 will be described below. The distance between the end 31b of the connection portion 31 of the first wire 30 and the end 34b of the connection portion 34 of the second wire 33 opposite to the end 31b is set to be equal to or less than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is equal to or less than 0.2. The distance between the end 31a of the connection portion 31 of the first wire 30 and the end 34a of the connection portion 34 of the second wire 33 opposite to the end 31a is set to be equal to or less than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is equal to or less than 0.2. In addition, in one second wire 34 having a plurality of connection portions 34, the distance between two opposing ends 34c of adjacent connection portions 34 is preferably set to be equal to or less than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is equal to or less than 0.2. This makes it possible to reduce the resistance between the first wire 30 and the second wire 33 and the source electrode layer 20.

[0100] According to the semiconductor device of the present embodiment described above, by mounting a semiconductor element capable of reducing the resistance between the first wire 33 and the source electrode layer 20 on the semiconductor device, it is possible to provide a low on-resistance.

[0101] 15 is a diagram showing a modified example of the semiconductor device of the second embodiment. In the semiconductor element 10 of the semiconductor device 1 of this modified example, the direction in which the first wire 30 extends is parallel to the direction in which the second wire 33 extends. The first wire 30 and the second wire 33 are spaced apart. The distance between the end 31b of the connection portion 31 of the first wire 30 and the end 34a of the connection portion 34 of the second wire 33 facing the end 31b should be no more than twice the distance X that satisfies 0≦Rs / Rc≦0.2 and is determined so that the ratio Rs / Rc is 0.2 or less. In addition, the distance between two opposing ends 31c of adjacent connection portions 31 of the first wire 30 should be equal to or less than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is equal to or less than 0.2.

[0102] 16 is a plan view showing a third embodiment of a semiconductor device disclosed in this specification. In the semiconductor element 10 of the semiconductor device 1 of this embodiment, the direction in which the first wires 30 extend is perpendicular to the direction in which the second wires 33 extend. Furthermore, the semiconductor element 10 of the semiconductor device 1 of this embodiment has the first wires 30 that are in physical contact with the second wires 33 and the first wires 30 that are not in physical contact with the second wires 33. A side surface 30b of the connection portion 31 of the first wire 30 is physically connected to an end portion 33a of the second wire 33. In addition, the end portion 30a of the first wire 30 is physically connected to a side surface 33b of the connection portion 34 of the second wire 33. In addition, in Figure 16, each of the two ends 30a of the first wire 30 between the connection portions 34 of adjacent second wires 33 is physically connected to the side surface 33b of the connection portion 34 of the second wire 33, but either one of the two ends 30a of the first wire 30 may be physically connected to the side surface 33b of the connection portion 34 of the second wire 33. At the point where the first wire 30 and the second wire 33 are physically connected, the distance between the end 31b of the connection portion 31 of the first wire 30 and the end 34b of the connection portion 33 of the second wire 33 should be no more than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is no more than 0.2. At the point where the second wire 33 and the first wire 30 are physically connected, the distance between the end 31a of the connection portion 31 of the first wire 30 and the end 34a of the second wire 33 should similarly be no more than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is no more than 0.2. Furthermore, regardless of whether the second wire 33 and the first wire 30 are physically connected or not, the distance between the ends 31b of the connection portions 31 of adjacent first wires 30 should be no more than twice the distance X that satisfies 0≦Rs / Rc≦0.2 and is determined so that the ratio Rs / Rc is 0.2 or less. Furthermore, the distance between the opposing ends 31c of adjacent connection portions 31 of one first wire 30 should be equal to or less than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is equal to or less than 0.2.

[0103] 17 is a diagram showing a variation of the semiconductor device of the third embodiment. In the semiconductor device 1 of this variation, the direction in which the first wires 30 extend is parallel to the direction in which the second wires 33 extend. The semiconductor device 1 of this variation also has the first wires 30 that are in physical contact with the second wires 33 and the first wires 30 that are not in physical contact with the second wires 33. A side surface 30b of the connection portion 31 of the first wire 30 and a side surface 33b of the connection portion 34 of the second wire 33 are in physical contact with each other and are electrically connected to each other. At the point where the first wire 30 and the second wire 33 are physically connected, the distance between the end 31b of the connection portion 31 of the first wire 30 and the end 34a of the connection portion 33 of the second wire 33 should be no more than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is no more than 0.2. In addition, the distance between the ends 31b of the connection portions 31 of adjacent first wires 30 should be equal to or less than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is equal to or less than 0.2. Furthermore, the distance between the opposing ends 31c of adjacent connection portions 31 of one first wire 30 should be equal to or less than twice the distance X determined so that 0≦Rs / Rc≦0.2 is satisfied and the ratio Rs / Rc is equal to or less than 0.2.

[0104] Next, one embodiment of a method for manufacturing a semiconductor device disclosed in this specification will be described below with reference to FIGS.

[0105] First, as shown in FIG. 18, a conductive first wire 30 is disposed on a first main surface 20a of a source electrode layer 20 of a semiconductor element 10 so as to be electrically connected to the first main surface 20a of the source electrode layer 20 at a plurality of connection portions 31 and extend in a predetermined direction. Specifically, an end of a long wire is placed on the first main surface 20a of the source electrode layer 20, and the connection portion 31 is formed by joining the end of the long wire to the first main surface 20a of the source electrode layer 20 using ultrasound, for example, by wire bonding. The wire is moved in a predetermined direction to repeatedly bond the source electrode layer 20 to the first main surface 20a, thereby forming a plurality of connection portions 31. When the wire connected to the source electrode layer 20 and the first main surface 20a reaches a predetermined length, the long wire is cut near the connection portion 31, and the first wire 30 is formed. Further, a conductive third wire 36 is disposed on the gate electrode layer 21 so as to be electrically connected to the gate electrode layer 21 at a connection portion 37. The other end of the third wire 36 is electrically connected to an external terminal (not shown) such as a wiring pattern or a lead frame of a circuit board on which the semiconductor element 10 is mounted.

[0106] Next, as shown in FIG. 19, a second wire 33 that is conductive and has a larger circular equivalent diameter than the first wire 30 is placed on the first main surface 20a of the source electrode layer 20 in a direction intersecting the extension direction of the first wire 30. 19, the second wire 33 is disposed in a direction perpendicular to the extending direction of the first wire 30. Note that the dotted line portion of the second wire 33 indicates the extending direction (the direction in which the second wire 33 is moved).

[0107] Next, as shown in FIG. 20, the second wire 33 is joined to the first main surface 20a of the source electrode layer 20 by, for example, wire bonding using ultrasonic waves, thereby forming the connection portion . Furthermore, the second wire 33 is moved in the direction in which the second wire 33 extends, and is disposed on the first main surface 20a of the source electrode layer 20. The second wire 33 and the first main surface 20a of the source electrode layer 20 are joined to form a connection 34. The second wire 33 is moved in a predetermined direction to repeatedly join the source electrode layer 20 and the first main surface 20a, thereby forming a plurality of connection parts 34. The other end of the second wire 33 is electrically connected to an external terminal (not shown) such as a wiring pattern or a lead frame of a circuit board on which the semiconductor element 10 is mounted. As a result, the end 30a of the first wire 30 and the side surface 33b of the connection portion 34 of the second wire 33 are physically in contact with each other and are also electrically connected. After the first wire 30 is connected to the first main surface 20a of the source electrode layer 20, the second wire 33 having a larger circle equivalent diameter than the first wire 30 is connected to the first main surface 20a of the source electrode layer 20, thereby obtaining the semiconductor device 1 shown in FIGS. 4 to 6.

[0108] In the present invention, the semiconductor device and the method for manufacturing the semiconductor device according to the above-mentioned embodiments can be modified as appropriate without departing from the spirit of the present invention.

[0109] For example, in the above-described embodiment, when the first wire and the second wire are in contact, the end of the first wire is in contact with the side of the connection portion of the second wire, the side of the connection portion of the first wire is in contact with the end of the second wire, or the side of the connection portion of the first wire is in contact with the side of the connection portion of the second wire, but the first wire and the second wire may be in contact at a location other than the end of each wire and the side of each connection portion. For example, the second wire may be disposed so as to straddle the first wire and be in contact with the first wire and the second wire.

[0110] In addition, in the above-described embodiment, the first wire and the second wire are arranged so as to intersect at a perpendicular angle, but the first wire and the second wire may be arranged so as to intersect at an angle different from the perpendicular angle. In the above-described embodiment, the direction in which the first wire, the second wire, and the third wire extend and the positions of the gate electrode layer and the source electrode layer of the semiconductor element are specified, but the direction in which the first wire, the second wire, and the third wire are connected and the positions of the gate electrode layer and the source electrode layer of the semiconductor element may differ depending on the wiring pattern of the circuit board of the semiconductor device on which the semiconductor element is mounted or an external terminal such as a lead frame.

[0111] In the above-described embodiment, the semiconductor element is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), but the semiconductor element is not limited to this and may be an Insulated Gate Bipolar Transistor (IGBT) or a Reverse Conducting Insulated Gate Bipolar Transistor (RC-IGBT). [Explanation of symbols]

[0112] 1 Semiconductor device 10 Semiconductor elements 11 n + Drain Layer 12 n - Drift Layer 13p base region 14 Gate electrode 15 Gate insulating film 16n + Source Region 17 p ++ Contact Area 18 Interlayer insulating film 19 Drain electrode layer 20 Source electrode layer (surface electrode layer) 20a First main surface 20b 2nd principal surface 21 Gate electrode layer 22 Pressure-resistant structure area 30 First Wire 30a end 30b side 31 Connection 31a End 31b End 31c end 32 Connection Periphery 33 Second Wire 33a end 33b side 34 Connection 34a end 34b end 34c end 35 Connection Periphery 36 3rd Wire 37 Connection 40, 40a~40d Source wire 41 Gate Wire 50, 50a~50c Trench

Claims

1. A semiconductor element including a plurality of trenches arranged along a first direction, each of which includes a gate electrode and a gate oxide film, and a surface electrode layer having a first main surface and a second main surface, the first main surface being exposed as a surface of the semiconductor element; a first wire electrically connected to the first main surface at a plurality of first connection portions and disposed on the first main surface in a first direction; a second wire electrically connected to the first main surface at a second connection portion and disposed on the first main surface in a second direction intersecting the first direction; A semiconductor device in which a second equivalent circular diameter, which is the diameter of a circle having the same cross-sectional area as the cross-sectional area of ​​the second wire, is larger than a first equivalent circular diameter, which is the diameter of a circle having the same cross-sectional area as the cross-sectional area of ​​the first wire.

2. The semiconductor device according to claim 1 , wherein the first equivalent circular diameter is 4 to 50 times the thickness of the surface electrode layer.

3. The semiconductor device according to claim 1 , wherein the first wire and the second wire are in contact with each other.

4. The semiconductor element has an on-resistance Rc, the first connection portion of the first wire and the second connection portion of the second wire are spaced apart by a distance S; The semiconductor device according to any one of claims 1 to 3, wherein the sheet resistance Rs and on-resistance Rc of the portion of the surface electrode layer in the region surrounding the first connection portion where the first wire is electrically connected to the first main surface by a distance S satisfy the relationship 0≦Rs / Rc≦0.

2.

5. a plurality of the first wires electrically connected to only the first main surface at the plurality of first connection portions; The semiconductor device according to any one of claims 1 to 4, comprising a plurality of second wires, one of which is electrically connected to the first main surface via a plurality of the second connection portions, and the other of which is electrically connected to an external terminal.

6. 6. The semiconductor device according to claim 1, wherein the first wire has a sheet resistance lower than a sheet resistance of the front electrode layer.

7. A method for manufacturing a semiconductor device including a semiconductor element including a plurality of trenches arranged along a first direction, each of the trenches including a gate electrode and a gate oxide film, and a front surface electrode layer having a first main surface and a second main surface, the first main surface being exposed as a front surface, the method comprising: a first step of disposing a conductive first wire on the first main surface so as to extend in a first direction and to be electrically connected to the first main surface at a plurality of first connection portions; a second step of disposing a second wire, which is conductive and thicker than the first wire, on the first main surface so as to be electrically connected to the first main surface at a second connection portion and extend in a second direction intersecting the first direction; A method for manufacturing a semiconductor device comprising the steps of:

8. The method for manufacturing a semiconductor device according to claim 7 , wherein the second step is performed after the first step.

9. 9. The method for manufacturing a semiconductor device according to claim 7, wherein the second step includes arranging the second wire on the first main surface so as to be in contact with the first wire.

10. The first step includes forming a plurality of the first wires electrically connected only to the first main surface at the plurality of first connection portions; 9. The method for manufacturing a semiconductor device according to claim 7 or 8, wherein the second step forms a plurality of second wires, one of which is electrically connected to the first main surface via a plurality of the second connection portions and the other of which is electrically connected to an external terminal.

11. 11. The method for manufacturing a semiconductor device according to claim 7, wherein the first wire has a sheet resistance lower than a sheet resistance of the front electrode layer.

Images