Semiconductor device, and method of manufacturing the same

Abstract

This semiconductor device is provided with a die pad, a semiconductor element, a first joining layer, a first conductive member, and a second joining layer. The die pad has a main surface facing in the thickness direction. The semiconductor element has a first electrode that is provided facing the main surface, and a second electrode that is provided on the reverse side from the first electrode in the thickness direction. The first electrode is electrically joined to the main surface. The first joining layer electrically joins the first electrode and the main surface. The first conductive member is electrically joined to the second electrode. The second joining layer electrically joins the first conductive member and the second electrode. The first joining layer is configured so as to have a melting point higher than the melting point of the second joining layer.

Description

Semiconductor device and method for manufacturing the same

[0001] The present disclosure relates to a semiconductor device including a semiconductor element such as a MOSFET, and a method for manufacturing the semiconductor device.

[0002] Conventionally, semiconductor devices including semiconductor elements such as MOSFETs have been widely known. Such semiconductor devices are used in electronic devices including power conversion circuits (e.g., DC-DC converters). Patent Document 1 discloses an example of a semiconductor device including a MOSFET. The semiconductor device includes a drain terminal to which a power supply voltage is applied, a gate terminal for inputting an electrical signal to the MOSFET, and a source terminal through which a current corresponding to the power supply voltage is converted based on the electrical signal and then flows. The MOSFET has a drain electrode conducting to the drain terminal and a source electrode conducting to the source terminal. The drain electrode is electrically bonded to a die pad connected to the drain terminal by a first conductive bonding material (solder). The source electrode is bonded to a conductive member (a metal clip in Patent Document 1) by a second conductive bonding material (solder). The conductive member is further bonded to the source terminal. This configuration enables a large current to flow through the semiconductor device.

[0003] In recent years, semiconductor devices including MOSFETs with compound semiconductor substrates have become increasingly popular. Such compound semiconductor substrates are formed, for example, using silicon carbide. Compared to conventional MOSFETs, such MOSFETs can achieve improved current conversion efficiency while reducing the device size. In the semiconductor device disclosed in Patent Document 1, when such a small MOSFET is employed, if the drain electrode is electrically bonded to the die pad using a first conductive bonding material and the conductive member is electrically bonded to the source electrode using a second conductive bonding material in the same process, the MOSFET may be misaligned with respect to the die pad. This is due to the simultaneous melting of the first and second conductive bonding materials by reflow. Even if the MOSFET is only slightly misaligned with respect to the die pad, the relatively small dimensions of the MOSFET may reduce the bonding area of ​​the conductive member with respect to the source electrode, potentially hindering current flow to the source terminal.

[0004] JP 2016-192450 A

[0005] In view of the above circumstances, an object of the present disclosure is to provide a semiconductor device that can handle large currents while suppressing a reduction in the bonding area between a conductive member and an electrode of a semiconductor element, and another object of the present disclosure is to provide a method for manufacturing such a semiconductor device.

[0006] A semiconductor device provided by a first aspect of the present disclosure includes: a die pad having a main surface facing a thickness direction; a semiconductor element having a first electrode facing the main surface and a second electrode provided on the opposite side of the first electrode in the thickness direction, the first electrode being electrically connected to the main surface; a first bonding layer electrically connecting the first electrode to the main surface; a first conductive member electrically connected to the second electrode; and a second bonding layer electrically connecting the first conductive member to the second electrode, wherein the melting point of the first bonding layer is higher than the melting point of the second bonding layer.

[0007] A second aspect of the present disclosure provides a method for manufacturing a semiconductor device, comprising the steps of: disposing a conductive first bonding material on a main surface of a die pad; disposing a semiconductor element having a first electrode and a second electrode opposite each other on the first bonding material such that the first electrode faces the first bonding material; melting and solidifying the first bonding material to electrically bond the first electrode to the main surface; disposing a conductive second bonding material on the second electrode; and disposing a conductive member on the second bonding material and melting and solidifying the second bonding material to electrically bond the conductive member to the second electrode. The melting point of the first bonding material is higher than that of the second bonding material.

[0008] According to the semiconductor device and manufacturing method described above, it is possible to accommodate a larger current while suppressing a reduction in the bonding area between the conductive member and the electrode of the semiconductor element.

[0009] Other features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0010] 1 is a perspective view of a semiconductor device according to a first embodiment of the present disclosure. FIG. 1 is a plan view of the semiconductor device shown in FIG. 1. FIG. 2 is a plan view corresponding to FIG. 2, seen through the sealing resin. FIG. 3 is a bottom view of the semiconductor device shown in FIG. 1. FIG. 1 is a front view of the semiconductor device shown in FIG. 1. FIG. 1 is a right side view of the semiconductor device shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line VII-VII of FIG. 3. FIG. 3 is a cross-sectional view taken along line VIII-VIII of FIG. 3. FIG. 3 is a cross-sectional view taken along line IX-IX of FIG. 3. FIG. 3 is a partial enlarged view of FIG. 3. FIG. 7 is a partial enlarged view of FIG. 7. FIG. 7 is another partial enlarged view of FIG. 7. FIG. 7 is a partial enlarged cross-sectional view of a semiconductor device according to a modified example of the first embodiment. FIG. 1 is a plan view illustrating a manufacturing process of the semiconductor device shown in FIG. 1. FIG. 1 is a plan view illustrating a manufacturing process of the semiconductor device shown in FIG. 1. FIG. 1 is a partial enlarged cross-sectional view illustrating a manufacturing process of the semiconductor device shown in FIG. 1. FIG. 1 is a partial enlarged cross-sectional view illustrating a manufacturing process of the semiconductor device shown in FIG. 1. FIG. 1 is a plan view of a semiconductor device according to a second embodiment of the present disclosure, seen through the sealing resin. 23 is a cross-sectional view taken along line XXIII-XXIII of Fig. 22. Fig. 24 is a partially enlarged view of Fig. 23. Fig. 25 is another partially enlarged view of Fig. 23.

[0011] Embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0012] A semiconductor device A10 according to a first embodiment of the present disclosure will be described with reference to Figures 1 to 13. The semiconductor device A10 is used in electronic devices equipped with a power conversion circuit (e.g., a DC-DC converter). The semiconductor device A10 includes a die pad 10, a first lead 11, a second lead 12, a third lead 13, a semiconductor element 20, a first bonding layer 21, a second bonding layer 22, a third bonding layer 23, a first conductive member 31, a wire 33, and a sealing resin 40. For ease of understanding, Figure 3 shows the sealing resin 40 with an imaginary line (two-dot chain line) that shows it through.

[0013] For convenience of explanation, the thickness direction of the die pad 10 is referred to as the "thickness direction z." The direction perpendicular to the thickness direction z is referred to as the "first direction x." The direction perpendicular to both the thickness direction z and the first direction x is referred to as the "second direction y." In the illustrated example, the semiconductor device A10 is elongated along the first direction x, but the present disclosure is not limited to this.

[0014] As shown in FIGS. 3 , 7 , and 8 , the die pad 10 is a conductive member on which a semiconductor element 20 is mounted. The die pad 10, along with the first lead 11, the second lead 12, and the third lead 13, is formed from the same lead frame. The lead frame is made of copper (Cu) or a copper alloy. Therefore, the die pad 10, the first lead 11, the second lead 12, and the third lead 13 each contain copper (i.e., each component contains copper). As shown in FIG. 8 , the die pad 10 has a main surface 101, a back surface 102, and a through hole 103. The main surface 101 faces the thickness direction z. The semiconductor element 20 is mounted on the main surface 101. The back surface 102 faces the opposite side to the main surface 101 in the thickness direction z. The back surface 102 is plated with, for example, tin (Sn). The through hole 103 penetrates the die pad 10 in the thickness direction z from the main surface 101 to the back surface 102. The through hole 103 has a circular shape when viewed in the thickness direction z. As shown in FIG. 7, the thickness T of the die pad 10 is max is greater than

[0015] As shown in FIGS. 3 , 7 , and 8 , the semiconductor element 20 is mounted on the main surface 101 of the die pad 10. The semiconductor element 20 is, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET). In the description of the semiconductor device A10, the semiconductor element 20 is an n-channel MOSFET with a vertical structure. The semiconductor element 20 includes a compound semiconductor substrate. The compound semiconductor substrate is primarily made of silicon carbide (SiC). Alternatively, the compound semiconductor substrate may be primarily made of gallium nitride (GaN). In the semiconductor device A10, the area of ​​the semiconductor element 20, as viewed along the thickness direction z, is 40% or less of the area of ​​the main surface 101 of the die pad 10. As viewed along the thickness direction z, the area of ​​the semiconductor element 20 may be 20% or less, or even 10% or less, of the area of ​​the main surface 101. This ratio can be changed by appropriately changing the area of ​​the semiconductor element 20 and the area of ​​the main surface 101. As shown in Figures 10 and 11, the semiconductor element 20 has a first electrode 201, a second electrode 202, and a third electrode 203.

[0016] 11 , the first electrode 201 is provided opposite the main surface 101 of the die pad 10. A DC power supply voltage to be converted into power is applied to the first electrode 201. The first electrode 201 corresponds to a drain electrode.

[0017] 10 and 11 , the second electrode 202 is provided on the opposite side of the first electrode 201 in the thickness direction z. A current converted by the semiconductor element 20 flows through the second electrode 202. The second electrode 202 corresponds to a source electrode.

[0018] 10 and 11 , the third electrode 203 is provided on the opposite side of the first electrode 201 in the thickness direction z and is located away from the second electrode 202. A gate voltage for driving the semiconductor element 20 is applied to the third electrode 203. That is, the third electrode 203 corresponds to a gate electrode. Based on the gate voltage, the semiconductor element 20 converts a current corresponding to the power supply voltage applied to the first electrode 201. When viewed along the thickness direction z, the area of ​​the third electrode 203 is smaller than the area of ​​the second electrode 202.

[0019] As shown in FIG. 11 , the first bonding layer 21 includes a portion interposed between the main surface 101 of the die pad 10 and the first electrode 201 of the semiconductor element 20. The first bonding layer 21 is conductive. The first bonding layer 21 electrically bonds the first electrode 201 to the main surface 101. As a result, in the semiconductor device A10, the first electrode 201 is electrically bonded to the main surface 101 and is electrically connected to the die pad 10. The first bonding layer 21 contains tin. The first bonding layer 21 is, for example, lead-free solder. The melting point of the first bonding layer 21 is set to be 290°C or higher and 300°C or lower. The first bonding layer 21 may be lead solder.

[0020] As shown in FIGS. 3 and 7 , the first lead 11 is located away from the die pad 10. The first lead 11 extends along the first direction x. The first lead 11 is electrically connected to the second electrode 202 of the semiconductor element 20. Therefore, the first lead 11 corresponds to the source terminal of the semiconductor device A10. The first lead 11 has a covering portion 111, an exposed portion 112, and a first bonding surface 113. The covering portion 111 is covered with the sealing resin 40. The exposed portion 112 is connected to the covering portion 111 and exposed from the sealing resin 40. The exposed portion 112 extends away from the die pad 10 in the first direction x. The surface of the exposed portion 112 is, for example, tin-plated. The first bonding surface 113 faces the same side as the main surface 101 of the die pad 10 in the thickness direction z. The first bonding surface 113 is included as part of the covering portion 111. In the thickness direction z, the first bonding surface 113 is located closer to the semiconductor element 20 than the main surface 101 .

[0021] As shown in FIG. 3 , the second lead 12 is located away from both the die pad 10 and the first lead 11. The second lead 12 extends along the first direction x. In the semiconductor device A10, the second lead 12 is located on the opposite side of the third lead 13 from the first lead 11 in the second direction y. The second lead 12 is electrically connected to the third electrode 203 of the semiconductor element 20. Therefore, the second lead 12 corresponds to the gate terminal of the semiconductor device A10. The second lead 12 has a covering portion 121, an exposed portion 122, and a second bonding surface 123. The covering portion 121 is covered with the sealing resin 40. The exposed portion 122 is connected to the covering portion 121 and is exposed from the sealing resin 40. The exposed portion 122 extends away from the die pad 10 in the first direction x. The surface of the exposed portion 122 is, for example, tin-plated. The second bonding surface 123 faces the same side as the main surface 101 of the die pad 10 in the thickness direction z. The second bonding surface 123 is included in part of the covering portion 121. In the thickness direction z, the second bonding surface 123 is located closer to the semiconductor element 20 than the main surface 101. As shown in FIG. 9 , in the thickness direction z, the position of the second bonding surface 123 is the same as the position of the first bonding surface 113 of the first lead 11.

[0022] 3 and 8 , the third lead 13 includes a portion extending in the first direction x and is connected to the die pad 10. The material of the third lead 13 is the same as the material of the die pad 10. The third lead 13 has a covering portion 131 and an exposed portion 132. The covering portion 131 is connected to the die pad 10 and is covered with the sealing resin 40. When viewed along the second direction y, the covering portion 131 is bent. The exposed portion 132 is connected to the covering portion 131 and is exposed from the sealing resin 40. The exposed portion 132 extends away from the die pad 10 in the first direction x. The surface of the exposed portion 132 is plated with, for example, tin.

[0023] 5, in the semiconductor device A10, the height h of each of the exposed portion 112 of the first lead 11, the exposed portion 122 of the second lead 12, and the exposed portion 132 of the third lead 13 are all the same. Therefore, when viewed along the second direction y, at least a portion of the third lead 13 (exposed portion 132) overlaps each of the first lead 11 and the second lead 12 (see FIG. 6).

[0024] As shown in FIGS. 3 and 7 , the first conductive member 31 is electrically connected to the second electrode 202 of the semiconductor element 20 and the first bonding surface 113 of the first lead 11. This electrically connects the first lead 11 to the second electrode 202. The first conductive member 31 contains copper. In the semiconductor device A10, the first conductive member 31 is a metal clip. As shown in FIGS. 11 and 12 , the first conductive member 31 has a first bonding portion 311 and a second bonding portion 312. The first bonding portion 311 is located at one end of the first conductive member 31 and electrically connects the first conductive member 31 to the second electrode 202. The second bonding portion 312 is located at the other end of the first conductive member 31 and electrically connects the first conductive member 31 to the first bonding surface 113.

[0025] As shown in FIG. 11 , the second bonding layer 22 includes a portion interposed between the second electrode 202 of the semiconductor element 20 and the first bonding portion 311 of the first conductive member 31. The second bonding layer 22 is conductive. The second bonding layer 22 electrically bonds the first bonding portion 311 and the second electrode 202. As a result, in the semiconductor device A10, the first conductive member 31 is electrically bonded to the second electrode 202 and the first conductive member 31 is electrically connected to the second electrode 202. The second bonding layer 22 contains tin. The second bonding layer 22 is, for example, lead-free solder. The melting point of the second bonding layer 22 is set to be 260° C. or higher and 270° C. or lower. Therefore, the melting point of the first bonding layer 21 is higher than the melting point of the second bonding layer 22. Furthermore, the thickness t1 of the first bonding layer 21 is greater than the thickness t2 of the second bonding layer 22. The second bonding layer 22 may be a lead solder.

[0026] 12 , the third bonding layer 23 includes a portion interposed between the first bonding surface 113 of the first lead 11 and the second bonding portion 312 of the first conductive member 31. The third bonding layer 23 is conductive. The third bonding layer 23 electrically bonds the second bonding portion 312 and the first bonding surface 113. As a result, in the semiconductor device A10, the first conductive member 31 is electrically bonded to the first bonding surface 113, and the first conductive member 31 is electrically connected to the first lead 11. The third bonding layer 23 is made of the same material as the second bonding layer 22.

[0027] 3 and 10 , the wire 33 is electrically joined to the third electrode 203 of the semiconductor element 20 and the second bonding surface 123 of the second lead 12. This allows the second lead 12 to be electrically connected to the third electrode 203. The wire 33 contains gold (Au). Alternatively, the wire 33 may contain copper or aluminum (Al).

[0028] As shown in FIG. 3 and FIGS. 7 to 9 , the sealing resin 40 covers the semiconductor element 20, the first conductive member 31, and the wires 33. The sealing resin 40 also covers a portion of each of the die pad 10, the first lead 11, the second lead 12, and the third lead 13. The sealing resin 40 has electrical insulation properties. The sealing resin 40 is made of a material containing, for example, black epoxy resin. The sealing resin 40 has a top surface 41, a bottom surface 42, a pair of first side surfaces 43, a pair of second side surfaces 44, a pair of openings 45, and a mounting hole 46.

[0029] 7 to 9, the top surface 41 faces the same side as the main surface 101 of the die pad 10 in the thickness direction z. As shown in Fig. 7 to 9, the bottom surface 42 faces the opposite side to the top surface 41 in the thickness direction z. As shown in Fig. 4, the back surface 102 of the die pad 10 is exposed from the bottom surface 42.

[0030] 2, 4, and 6, the pair of first side surfaces 43 are spaced apart from each other in the first direction x. Each of the pair of first side surfaces 43 is connected to the top surface 41 and the bottom surface 42. As shown in FIG. 5, an exposed portion 112 of the first lead 11, an exposed portion 122 of the second lead 12, and an exposed portion 132 of the third lead 13 are exposed from one of the pair of first side surfaces 43.

[0031] As shown in FIGS. 2 , 4 , and 5 , the pair of second side surfaces 44 are spaced apart from each other in the second direction y. Each of the pair of second side surfaces 44 is connected to the top surface 41 and the bottom surface 42. As shown in FIGS. 2 and 6 , the pair of openings 45 are spaced apart from each other in the second direction y. Each of the pair of openings 45 is recessed inward into the sealing resin 40 from both the top surface 41 and one of the pair of second side surfaces 44. A portion of the main surface 101 of the die pad 10 is exposed from each of the pair of openings 45. As shown in FIGS. 2 , 4 , and 8 , the mounting hole 46 penetrates the sealing resin 40 from the top surface 41 to the bottom surface 42 in the thickness direction z. When viewed along the thickness direction z, the mounting hole 46 is contained within the through hole 103 of the die pad 10. The peripheral surface of the die pad 10 that defines the through hole 103 is covered with the sealing resin 40. As a result, the maximum dimension of the mounting hole 46 is smaller than the dimension of the through hole 103 when viewed along the thickness direction z.

[0032] 13 shows a semiconductor device A11, which is a modification of the semiconductor device A10. The semiconductor device A11 differs from the semiconductor device A10 in the configuration of the first bonding layer 21. The semiconductor device A11 also includes a plating layer 19.

[0033] In the semiconductor device A11, the first bonding layer 21 is made of a material containing sintered metal particles. The sintered metal particles contain silver (Ag). Therefore, in the semiconductor device A11, the melting point of the first bonding layer 21 is higher than the melting point of the second bonding layer 22.

[0034] 19 , the plating layer 19 covers the main surface 101 of the die pad 10. The plating layer 19 contains silver. The first bonding layer 21 includes a portion interposed between the plating layer 19 and the first electrode 201 of the semiconductor element 20.

[0035] Next, an example of a manufacturing method of the semiconductor device A10 will be described with reference to Figures 14 to 21. The cross-sectional positions of Figures 17 and 19 are the same as that of Figure 11. The cross-sectional position of Figure 20 is the same as that of Figure 12.

[0036] First, as shown in FIG. 14 , a first bonding material 81 is placed on the main surface 101 of the die pad 10. The first lead 11, the second lead 12, and the third lead 13 are connected to one another by tie bars 80 that form a lead frame. The tie bars 80 extend along the second direction y. The first bonding material 81 is conductive. The first bonding material 81 is wire solder. The melting point of the first bonding material 81 is 290° C. or higher and 300° C. or lower. The first bonding material 81 is temporarily attached to the main surface 101.

[0037] 15 , the semiconductor element 20 is placed on the first bonding material 81. At this time, the first electrode 201 of the semiconductor element 20 faces the first bonding material 81. The first electrode 201 is temporarily attached to the first bonding material 81.

[0038] 16 and 17 , the first bonding material 81 is melted by reflow and then solidified by cooling, thereby electrically bonding the first electrode 201 of the semiconductor element 20 to the main surface 101 of the die pad 10. In this step, the first bonding material 81 solidified by cooling becomes the first bonding layer 21.

[0039] Next, as shown in FIGS. 19 and 20 , a second bonding material 82 is placed on the second electrode 202 of the semiconductor element 20, and a third bonding material 83 is placed on the first bonding surface 113 of the first lead 11. The second bonding material 82 and the third bonding material 83 are each electrically conductive. The second bonding material 82 and the third bonding material 83 are each cream solder. A dispenser or the like is used to place the second bonding material 82 and the third bonding material 83. The melting point of the second bonding material 82 is 260°C or higher and 270°C or lower. Therefore, the melting point of the first bonding material 81 is higher than the melting point of the second bonding material 82. The third bonding material 83 is made of the same material as the second bonding material 82. Thereafter, the first bonding portion 311 of the first conductive member 31 is placed on the second bonding material 82. Additionally, the second bonding portion 312 of the first conductive member 31 is placed on the third bonding material 83. Thereafter, the second bonding material 82 and the third bonding material 83 are melted by reflow and then solidified by cooling, thereby electrically bonding the first bonding portion 311 to the second electrode 202. At the same time, the second bonding portion 312 is electrically bonded to the first bonding surface 113. At this time, the reflow temperature is set to be lower than the melting point of the first bonding material 81. In this process, the second bonding material 82 solidified by cooling becomes the second bonding layer 22. Furthermore, the third bonding material 83 solidified by cooling becomes the third bonding layer 23. As shown in FIG. 18 , a wire 33 is electrically bonded to the third electrode 203 of the semiconductor element 20 and the second bonding surface 123 of the second lead 12 by wire bonding.

[0040] Next, as shown in FIG. 21 , a sealing resin 84 is formed to cover the semiconductor element 20, the first conductive member 31, and the wire 33, and to cover portions of the die pad 10, the first lead 11, the second lead 12, and the third lead 13. The sealing resin 84 is formed by transfer molding. As the sealing resin 84 is formed, a resin burr 841 is formed. The resin burr 841 is blocked by the exposed portion 112 of the first lead 11, the exposed portion 122 of the second lead 12, the exposed portion 132 of the third lead 13, and the tie bar 80. The resin burr 841 is then removed using high-pressure water or the like. Thereafter, tin plating is applied by electrolytic plating using the tie bar 80 as a conductive path, covering the surfaces of the exposed portion 112 of the first lead 11, the exposed portion 122 of the second lead 12, and the exposed portion 132 of the third lead 13, as well as the back surface 102 of the die pad 10. Finally, the tie bars 80 are cut to obtain the semiconductor device A10.

[0041] Next, the effects of the semiconductor device A10 will be described.

[0042] The semiconductor device A10 includes a first bonding layer 21 and a second bonding layer 22. The first bonding layer 21 is conductive and electrically bonds a first electrode 201 of the semiconductor element 20 to the main surface 101 of the die pad 10. The second bonding layer 22 is conductive and electrically bonds a first conductive member 31 to a second electrode 202 of the semiconductor element 20. The melting point of the first bonding layer 21 is higher than the melting point of the second bonding layer 22. Therefore, in the manufacturing process of the semiconductor device A10 shown in FIG. 19 , when the second bonding material 82 that forms the second bonding layer 22 is melted, the first bonding layer 21 is not melted. This prevents misalignment of the semiconductor element 20 with respect to the die pad 10. Therefore, when the first conductive member 31 is electrically bonded to the second electrode 202 by the second bonding layer 22 in the manufacturing process shown in FIG. 19 , a larger bonding area of ​​the first conductive member 31 to the second electrode 202 can be ensured. Therefore, the semiconductor device A10 can accommodate a larger current while suppressing a reduction in the bonding area of ​​the conductive member (first conductive member 31) to the electrode (second electrode 202) of the semiconductor element 20.

[0043] The semiconductor device A10 further includes a third bonding layer 23. The third bonding layer 23 is conductive and electrically bonds the first conductive member 31 and the first bonding surface 113 of the first lead 11. The third bonding layer 23 is made of the same material as the second bonding layer 22. As a result, in the manufacturing process of the semiconductor device A10 shown in FIGS. 19 and 20 , when the second bonding material 82 that becomes the second bonding layer 22 is melted, the third bonding material 83 that becomes the third bonding layer 23 is simultaneously melted. Therefore, in the manufacturing process of the semiconductor device A10, when the first conductive member 31 is electrically bonded to the second electrode 202 of the semiconductor element 20, the first conductive member 31 can be electrically bonded to the first bonding surface 113 at the same time, thereby improving the manufacturing efficiency of the semiconductor device A10.

[0044] The first conductive member 31 contains copper, which allows the electrical resistance of the first conductive member 31 to be reduced compared to wires containing aluminum, which is advantageous for passing a larger current through the semiconductor element 20.

[0045] The thickness t1 of the first bonding layer 21 is greater than the thickness t2 of the second bonding layer 22. This allows the heat generated from the semiconductor element 20 to be conducted more quickly to the die pad 10 when the semiconductor device A10 is in use. In the manufacturing process of the semiconductor device A10, by using wire solder as the first bonding material 81, the first bonding layer 21 can be formed with a uniform thickness.

[0046] In the thickness direction z, the first bonding surface 113 of the first lead 11 is located closer to the semiconductor element 20 than the main surface 101 of the die pad 10. This reduces the length of the first conductive member 31, thereby reducing the inductance of the first conductive member 31.

[0047] The die pad 10 contains copper. Furthermore, the thickness T of the die pad 10 is equal to the maximum thickness t max This makes it possible to improve the efficiency of heat conduction in the direction perpendicular to the thickness direction z while improving the thermal conductivity of the die pad 10. This contributes to improving the heat dissipation performance of the die pad 10.

[0048] A semiconductor device A20 according to a second embodiment of the present disclosure will be described with reference to Figures 22 to 25. In these figures, elements that are the same as or similar to those in the semiconductor device A10 described above are given the same reference numerals, and duplicated explanations will be omitted. For ease of understanding, Figure 22 shows the sealing resin 40 through imaginary lines.

[0049] The semiconductor device A20 differs from the semiconductor device A10 in that it includes a second conductive member 32, a fourth bonding layer 24, and a fifth bonding layer 25 instead of the wires 33.

[0050] As shown in FIGS. 22 and 23 , the second conductive member 32 is electrically connected to the third electrode 203 of the semiconductor element 20 and the second bonding surface 123 of the second lead 12. This electrically connects the second lead 12 to the third electrode 203. The second conductive member 32 contains copper. In the semiconductor device A20, the second conductive member 32 is a metal clip. As shown in FIGS. 24 and 25 , the second conductive member 32 has a third bonding portion 321 and a fourth bonding portion 322. The third bonding portion 321 is located at one end of the second conductive member 32 and electrically connects the second conductive member 32 to the third electrode 203. The fourth bonding portion 322 is located at the other end of the second conductive member 32 and electrically connects the second conductive member 32 to the second bonding surface 123.

[0051] 24 , the fourth bonding layer 24 includes a portion interposed between the third electrode 203 of the semiconductor element 20 and the third bonding portion 321 of the second conductive member 32. The fourth bonding layer 24 is conductive. The fourth bonding layer 24 electrically bonds the third bonding portion 321 and the third electrode 203. As a result, in the semiconductor device A20, the second conductive member 32 is electrically bonded to the third electrode 203, and the second conductive member 32 is electrically connected to the third electrode 203. The fourth bonding layer 24 is made of the same material as the second bonding layer 22.

[0052] 25 , the fifth bonding layer 25 includes a portion interposed between the second bonding surface 123 of the second lead 12 and the fourth bonding portion 322 of the second conductive member 32. The fifth bonding layer 25 is conductive. The fifth bonding layer 25 electrically bonds the fourth bonding portion 322 and the second bonding surface 123. As a result, in the semiconductor device A20, the second conductive member 32 is electrically bonded to the second bonding surface 123, and the second conductive member 32 is electrically connected to the second lead 12. The fifth bonding layer 25 is made of the same material as the second bonding layer 22.

[0053] Next, the effects of the semiconductor device A20 will be described.

[0054] The semiconductor device A20 includes a first bonding layer 21 and a second bonding layer 22. The first bonding layer 21 is conductive and electrically bonds a first electrode 201 of the semiconductor element 20 to the main surface 101 of the die pad 10. The second bonding layer 22 is conductive and electrically bonds a first conductive member 31 to a second electrode 202 of the semiconductor element 20. The melting point of the first bonding layer 21 is higher than the melting point of the second bonding layer 22. Therefore, the semiconductor device A20 can also accommodate a larger current while suppressing a reduction in the bonding area of ​​the conductive member relative to the electrode of the semiconductor element 20.

[0055] The semiconductor device A20 includes a second conductive member 32 bonded to the third electrode 203 of the semiconductor element 20 and the second bonding surface 123 of the second lead 12. The semiconductor device A20 further includes a fourth bonding layer 24 and a fifth bonding layer 25. The fourth bonding layer 24 is conductive and electrically bonds the second conductive member 32 to the third electrode 203. The fifth bonding layer 25 is conductive and electrically bonds the second conductive member 32 to the second bonding surface 123. The fourth bonding layer 24 and the fifth bonding layer 25 are each made of the same material as the second bonding layer 22. This allows the second conductive member 32 to be bonded simultaneously with the first conductive member 31 in the manufacture of the semiconductor device A20. Furthermore, during bonding of the second conductive member 32, misalignment of the semiconductor element 20 with respect to the die pad 10 is prevented, thereby ensuring a sufficient bonding area of ​​the second conductive member 32 to the third electrode 203.

[0056] The second conductive member 32 contains copper. Furthermore, in the thickness direction z, the second bonding surface 123 of the second lead 12 is located closer to the semiconductor element 20 than the main surface 101 of the die pad 10. This makes the electrical resistance of the second conductive member 32 relatively low, and also shortens the length of the second conductive member 32, making it possible to reduce the on-resistance of the third electrode 203 of the semiconductor element 20.

[0057] The present disclosure is not limited to the above-described embodiment and modifications, and the specific configuration of each part of the present disclosure can be freely modified in various ways.

[0058] The semiconductor device and manufacturing method disclosed herein include the configurations described in the following appendices. Appendix 1. A semiconductor device comprising: a die pad having a main surface facing a thickness direction; a semiconductor element having a first electrode facing the main surface and a second electrode provided on the opposite side of the first electrode in the thickness direction, the first electrode being electrically joined to the main surface; a first bonding layer electrically joining the first electrode to the main surface; a first conductive member electrically joined to the second electrode; and a second bonding layer electrically joining the first conductive member to the second electrode, wherein a melting point of the first bonding layer is higher than a melting point of the second bonding layer. Appendix 2. The semiconductor device according to Appendix 1, wherein the die pad and the first conductive member each contain copper. Appendix 3. The semiconductor device according to Appendix 2, wherein the second bonding layer contains tin. Appendix 4. The semiconductor device according to Appendix 3, wherein the first bonding layer contains tin. Appendix 5. The semiconductor device according to Appendix 3 or 4, wherein the thickness of the first bonding layer is greater than the thickness of the second bonding layer. Appendix 6. The semiconductor device according to Appendix 3, wherein the first bonding layer is made of a material containing sintered metal particles. Appendix 7. The semiconductor device according to Appendix 6, wherein the sintered metal particles contain silver. Appendix 8. The semiconductor device according to Appendix 7, further comprising a plating layer covering the main surface, the plating layer containing silver, and the first bonding layer being interposed between the plating layer and the first electrode. Appendix 9. The semiconductor device according to any of Appendix 2 to 8, wherein the area of ​​the semiconductor element, as viewed along the thickness direction, is 40% or less of the area of ​​the main surface. Appendix 10. The semiconductor device according to Appendix 9, wherein the semiconductor element includes a compound semiconductor substrate. Appendix 11. 11. The semiconductor device according to any one of Supplementary Notes 2 to 10, further comprising: a first lead having a first bonding surface facing the same side as the main surface in the thickness direction and positioned away from the die pad; and a third bonding layer electrically bonding the first conductive member and the first bonding surface, wherein the first lead contains copper, and the third bonding layer is made of the same material as the second bonding layer. 12. The semiconductor device according to Supplementary Note 11, wherein the first bonding surface is positioned closer to the semiconductor element than the main surface in the thickness direction.Supplementary Note 13. The semiconductor device according to Supplementary Note 11 or 12, wherein a thickness of the die pad is greater than a maximum thickness of the first lead. Supplementary Note 14. The semiconductor device according to any of Supplementary Notes 11 to 13, further comprising a second lead, a second conductive member, a fourth bonding layer, and a fifth bonding layer, wherein the semiconductor element has a third electrode provided on the opposite side to the first electrode in the thickness direction and positioned away from the second electrode, the second lead has a second bonding surface facing the same side as the main surface in the thickness direction and positioned away from both the die pad and the first lead, the second conductive member is electrically bonded to the third electrode and the second bonding surface, the fourth bonding layer electrically bonds the second conductive member to the third electrode, the fifth bonding layer electrically bonds the second conductive member to the second bonding surface, the second conductive member and the second lead contain copper, and the fourth bonding layer and the fifth bonding layer are each made of the same material as the second bonding layer. Appendix 15. The semiconductor device according to Appendix 14, wherein the second bonding surface is located closer to the semiconductor element with respect to the main surface in the thickness direction. Appendix 16. The semiconductor device according to Appendix 14 or 15, further comprising a third lead including a portion extending along a first direction orthogonal to the thickness direction and connected to the die pad, wherein each of the first lead and the second lead extends along the first direction, the material of the third lead is the same as the material of the die pad, and at least a portion of the third lead overlaps each of the first lead and the second lead when viewed along a second direction orthogonal to the thickness direction and the first direction. Appendix 17. The semiconductor device according to any of Appendixes 1 to 16, further comprising a sealing resin that covers the semiconductor element, the first conductive member, and a portion of the die pad. Appendix 18. The semiconductor device according to Appendix 17, wherein the die pad has a back surface facing opposite to the main surface in the thickness direction, and the back surface is exposed from the sealing resin.Appendix 19. A method for manufacturing a semiconductor device comprising the steps of: disposing a conductive first bonding material on a main surface of a die pad; disposing a semiconductor element having a first electrode and a second electrode positioned opposite to each other on the first bonding material such that the first electrode faces the first bonding material; melting and solidifying the first bonding material to electrically bond the first electrode to the main surface; disposing a conductive second bonding material on the second electrode; disposing a conductive member on the second bonding material and melting and solidifying the second bonding material to electrically bond the conductive member to the second electrode, wherein the melting point of the first bonding material is higher than the melting point of the second bonding material. Appendix 20. The method for manufacturing a semiconductor device according to Appendix 19, wherein the first bonding material is wire solder.

[0059] A10, A11, A20: semiconductor device 10: die pad 101: main surface 102: back surface 103: through hole 11: first lead 111: covering portion 112: exposed portion 113: first bonding surface 12: second lead 121: covering portion 122: exposed portion 123: second bonding surface 13: third lead 131: covering portion 132: exposed portion 19: plating layer 20: semiconductor element 201: first electrode 202: second electrode 203: third electrode 21: first bonding layer 22: second bonding layer 23: third bonding layer 24: fourth bonding layer 25: fifth bonding layer 31: first conductive member 311: first bonding portion 312: second bonding portion 32: second conductive member 321: third bonding portion 322: Fourth bonding portion 33: Wire 40: Sealing resin 41: Top surface 42: Bottom surface 43: First side surface 44: Second side surface 45: Opening 46: Mounting hole 80: Tie bar 81: First bonding material 82: Second bonding material 83: Third bonding material z: Thickness direction x: First direction y: Second direction

Claims

1. A semiconductor device comprising: a die pad having a main surface facing in a thickness direction; a first electrode provided opposite the main surface; and a second electrode provided on the opposite side of the first electrode in the thickness direction, with the first electrode electrically bonded to the main surface; a first bonding layer electrically bonding the first electrode to the main surface; a first conductive member electrically bonded to the second electrode; and a second bonding layer electrically bonding the first conductive member to the second electrode, wherein the melting point of the first bonding layer is higher than the melting point of the second bonding layer.

2. The semiconductor device according to claim 1, wherein the die pad and the first conductive member each contain copper.

3. The semiconductor device according to claim 2, wherein the second bonding layer contains tin.

4. The semiconductor device according to claim 3, wherein the first bonding layer contains tin.

5. The semiconductor device according to claim 3 or 4, wherein the thickness of said first bonding layer is greater than the thickness of said second bonding layer.

6. The semiconductor device according to claim 2, wherein the area of ​​said semiconductor element is 40% or less of the area of ​​said main surface when viewed along said thickness direction.

7. A semiconductor device according to any one of claims 2 to 6, further comprising: a first lead having a first bonding surface facing the same side as the main surface in the thickness direction and positioned away from the die pad; and a third bonding layer electrically bonding the first conductive member and the first bonding surface, wherein the first lead contains copper, and the third bonding layer is made of the same material as the second bonding layer.

8. The semiconductor device according to claim 7, wherein the first bonding surface is located closer to the semiconductor element than the main surface in the thickness direction.

9. The semiconductor device according to claim 7 or 8, wherein the thickness of said die pad is greater than the maximum thickness of said first lead.

10. The semiconductor device according to any one of claims 7 to 9, further comprising a second lead, a second conductive member, a fourth bonding layer, and a fifth bonding layer, wherein the semiconductor element has a third electrode provided on the opposite side of the first electrode in the thickness direction and positioned away from the second electrode, the second lead has a second bonding surface facing the same side as the main surface in the thickness direction and positioned away from the die pad and the first lead, the second conductive member is electrically bonded to the third electrode and the second bonding surface, the fourth bonding layer electrically bonds the second conductive member to the third electrode, the fifth bonding layer electrically bonds the second conductive member to the second bonding surface, the second conductive member and the second lead contain copper, and each of the fourth bonding layer and the fifth bonding layer is made of the same material as the second bonding layer.

11. The semiconductor device according to claim 10, wherein the second bonding surface is located closer to the semiconductor element than the main surface in the thickness direction.

12. The semiconductor device according to claim 1, further comprising a sealing resin that covers the semiconductor element, the first conductive member, and a portion of the die pad.

13. The semiconductor device according to claim 12, wherein the die pad has a back surface facing the opposite side to the main surface in the thickness direction, and the back surface is exposed from the sealing resin.

14. A method for manufacturing a semiconductor device, comprising the steps of: placing a conductive first bonding material on a main surface of a die pad; placing a semiconductor element having a first electrode and a second electrode positioned opposite each other on the first bonding material so that the first electrode faces the first bonding material; melting and solidifying the first bonding material to electrically bond the first electrode to the main surface; placing a conductive second bonding material on the second electrode; placing a conductive member on the second bonding material, and melting and solidifying the second bonding material to electrically bond the conductive member to the second electrode; wherein the melting point of the first bonding material is higher than the melting point of the second bonding material.

15. The method for manufacturing a semiconductor device according to claim 14, wherein the first bonding material is wire solder.

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