Semiconductor device with semiconductor element and electrodes on different surfaces

The semiconductor device includes a semiconductor element, a first lead, and a second lead. The semiconductor element has an element obverse surface and an element reverse surface spaced apart from each other in a thickness direction. The semiconductor element includes an electron transit layer disposed between the element obverse surface and the element reverse surface and formed of a nitride semiconductor, a first electrode disposed on the element obverse surface, and a second electrode disposed on the element reverse surface and electrically connected to the first electrode. The semiconductor element is mounted on the first lead, and the second electrode is joined to the first lead. The second lead is electrically connected to the first electrode. The semiconductor element is a transistor. The second lead is spaced apart from the first lead and is configured such that a main current to be subjected to switching flows therethrough.

FIELD

The present disclosure relates to a semiconductor device.

BACKGROUND

Heretofore, semiconductor elements using a group III-V nitride semiconductor (“nitride semiconductor”) such as gallium nitride (GaN) have been developed. JP-A-2012-38885 discloses an example of such a semiconductor element. The semiconductor element disclosed in JP-A-2012-38885 includes a substrate, a nitride semiconductor layer formed on the obverse surface of the substrate, and a plurality of electrodes. The electrodes include a source electrode, a drain electrode, a gate electrode, and a back electrode. The source electrode, the drain electrode, and the gate electrode are disposed on the nitride semiconductor layer. The back electrode is disposed on the reverse surface of the substrate and is electrically connected to the source electrode via a conductive portion that passes through both the substrate and the nitride semiconductor layer.

The above-described semiconductor element constitutes a semiconductor device together with a plurality of leads and a sealing resin, for example. The plurality of leads include a source lead, a drain lead, and a gate lead. The source lead is a component on which the semiconductor element is mounted, and is electrically connected to the back electrode (thus also electrically connected to the source electrode). The drain lead is electrically connected to the drain electrode, and the gate lead is electrically connected to the gate electrode. The sealing resin covers the semiconductor element and the respective leads. The respective leads are partially exposed from the sealing resin, and the exposed portions are used as external connection terminals. In this semiconductor device, the source lead is electrically connected to the back electrode and the source electrode, whereby a current circulation path is formed by the source lead, the source electrode, the conductive portion, and the back electrode. Part of this circulation path extends along the lamination direction of the nitride semiconductor layer. Accordingly, when a current flows through this circulation path, electrons may be trapped in crystal defects in the nitride semiconductor layer. This may change the properties of the nitride semiconductor layer, resulting in reduced reliability of the semiconductor element.

SUMMARY

In light of the foregoing, it is an object of the present disclosure to provide a semiconductor device that can suppress the flow of a current in the lamination direction of a nitride semiconductor layer.

One aspect of the present disclosure provides a semiconductor device including: a semiconductor element having an element obverse surface and an element reverse surface that are spaced apart from each other in a thickness direction, the semiconductor element including an electron transit layer that is disposed between the element obverse surface and the element reverse surface and is formed of a nitride semiconductor, a first electrode that is disposed on the element obverse surface, and a second electrode that is disposed on the element reverse surface and is electrically connected to the first electrode; a first lead on which the semiconductor element is mounted, the first lead being joined to the second electrode; and a second lead that is electrically connected to the first electrode. The semiconductor element is a transistor, and the second lead is spaced apart from the first lead and is configured such that a main current to be subjected to switching flows through the second lead.

According to the above-described configuration, the first lead to which the second electrode is joined and the second lead electrically connected to the first electrode are spaced apart from each other. Accordingly, a current circulation path including the first lead, the second electrode, the first electrode, and the second lead is not formed. As a result, a current is kept from flowing along the lamination direction of a nitride semiconductor layer.

Other characteristics and advantages of the present disclosure will become more apparent by the following detailed description with reference to the accompanying drawings.

EMBODIMENTS

The present disclosure will be described in detail by way of various examples with reference to the accompanying drawings.

A semiconductor device A1according to Example 1 will be described with reference toFIGS. 1 to 7. The semiconductor device A1includes a plurality of leads, a semiconductor element6, bonding wires71to74, and a sealing resin8. In the example illustrated in these drawings, the plurality of leads include first to fifth leads1to5. InFIG. 2, the sealing resin8is not shown and the outer shape thereof is indicated with an imaginary line (double-dot-dash line).

The semiconductor device A1is surface-mountable on circuit boards of various apparatuses. The semiconductor device A1has a rectangular shape as viewed in the thickness direction (z direction). Two directions that are orthogonal to the z direction and also are orthogonal to each other are defined as the x direction and the y direction. For example, as shown inFIG. 2, one side of the semiconductor device A1extends along the x direction, and another side of the semiconductor device A1extends along the y direction. The size of the semiconductor device A1is not particularly limited, and may be such that, for example, the dimension in the x direction is about 1 to 10 mm, the dimension in the y direction is about 1 to 10 mm, and the dimension in the z direction is about 0.3 to 3 mm.

As described in the following, the leads1to5support the semiconductor element6and/or are electrically connected to the semiconductor element6. The leads1to5are made of metal, and are preferably made of either Cu or Ni, or an alloy of Cu and Ni, a42alloy, or the like. The leads1to5can be formed through punching, bending, or the like of a metal plate. The leads1to5each have a thickness of 0.08 to 0.5 mm, for example. In the example illustrated in the drawings, the leads1to5are each made of Cu and each have a thickness of about 0.5 mm.

As shown inFIG. 2, the semiconductor device A1has two sides that are spaced apart from each other in the y direction (each side extends along the x direction). The first lead1is disposed closer to one of these two sides (closer to the lower side inFIG. 2). In other words, the first lead1is disposed closer to the lower side than to the upper side of the semiconductor device A1. The first lead1extends over the entire width of the semiconductor device A1in the x direction.

The second lead2and the third lead3are provided on sides opposite to each other in the y direction with respect to the first lead1. The second lead2and the third lead3are each spaced apart from the first lead1. As shown inFIG. 2, the second lead2is adjacent to the lower side and the left side (extending along the y direction) of the semiconductor device A1. The third lead3is adjacent to the upper side of the semiconductor device A1and extends from the left side to the right side (extending along the y direction) of the semiconductor device A1. That is, the third lead3extends over the entire width of the semiconductor device A1in the x direction.

The fourth lead4and the fifth lead5are provided on the same side as the second lead2in the y direction with respect to the first lead1. InFIG. 2, the fourth lead4and the fifth lead5are each provided adjacent to the lower side of the semiconductor device A1. The fourth lead4and the fifth lead5are spaced apart from each other, and they are each spaced apart from the first lead1. The fifth lead5is disposed between the second lead2and the fourth lead4in the x direction. That is, the second lead2, the fifth lead5, and the fourth lead4are spaced apart from each other and disposed in this order in the x direction.

The dimension of the first lead1as viewed in the z direction is larger than those of the remaining leads2to5. The dimensions of the leads2to5in the x direction are as follows: the dimension of the third lead3is the largest, and the dimensions of the remaining leads decrease in the order of the second lead2, the fourth lead4, and the fifth lead5. In the y direction, the distance between the third lead3and the first lead1is greater than the distance between the second lead2(or the fifth lead5, the fourth lead4) and the first lead1.

The first lead1includes a mounting portion110and a plurality of coupling portions120. In the example illustrated in the drawings, four coupling portions120are provided. However, the present disclosure is not limited thereto.

The mounting portion110, which is a major portion of the first lead1, has a rectangular shape as viewed in the z direction. The mounting portion110has an obverse surface111(FIG. 2) and a reverse surface112(FIG. 4). The obverse surface111and the reverse surface112face away from each other in the z direction. The obverse surface111is a surface that faces upward inFIG. 3and on which the semiconductor element6is mounted. The reverse surface112is a surface that faces downward inFIG. 3and is exposed from the sealing resin8to serve as a back terminal. The mounting portion110has at least one recess113. In the example illustrated inFIG. 4, two recesses113(each recess is elongated in the x direction) are formed spaced apart from each other in the y direction. InFIG. 4, the dimension of the upper recess113(adjacent to the second lead2) in the y direction is smaller than that of the lower recess113(adjacent to the third lead). On the other hand, the upper recess113and the lower recess113have the same dimension in the x direction. Accordingly, the area of the upper recess113as viewed in the z direction is smaller than that of the lower recess113. The respective recesses113are portions of the mounting portion110recessed from the reverse surface112in the z direction. The thickness (the dimension in the z direction) of each of the portions of the mounting portion110provided with the recesses113is about one-half of the thickness of the portion of the mounting portion110provided with the reverse surface112(the distance between the obverse surface111and the reverse surface112). Each recess113is formed by, for example, subjecting the mounting portion110(the first lead1) to half etching.

As shown inFIG. 2, each coupling portion120is connected to the mounting portion110and has a rectangular shape as viewed in the z direction. In the example illustrated in the drawings, the mounting portion110has two end surfaces that are spaced apart from each other in the x direction and parallel to each other, and two coupling portions120are disposed on each end surface. Each coupling portion120has an obverse surface121(FIG. 2), a reverse surface122(FIG. 4), and an end surface123(FIGS. 2 and 4). The obverse surface121and the reverse surface122face away from each other in the z direction. The obverse surface121of each coupling portion faces upward inFIG. 3and is flush with the obverse surface111of the mounting portion. The reverse surface122of each coupling portion faces downward inFIG. 3. The thickness (the dimension in the z direction) of each coupling portion120is about the same as the thickness of each of the portions of the mounting portion110provided with the recesses113. Each coupling portion120is formed by, for example, subjecting the first lead1to half etching. In each coupling portion, the end surface123is a surface connecting the obverse surface121and the reverse surface122, faces outward in the x direction, and is exposed from the sealing resin8(seeFIG. 1).

The second lead2is disposed at a corner (the lower left corner inFIG. 2) of the semiconductor device A1as viewed in the z direction, and includes a wire bonding portion210, two terminal portions220, and a coupling portion230.

The wire bonding portion210has a rectangular shape elongated in the x direction as viewed in the z direction. The wire bonding portion210has an obverse surface211, a reverse surface212, and a recess213. The obverse surface211and the reverse surface212face away from each other in the z direction. The obverse surface211is a surface that faces upward inFIG. 3and to which the bonding wires71are bonded. The reverse surface212is a surface that faces downward inFIG. 3and is exposed from the sealing resin8to serve as a back terminal (seeFIG. 4). The recess213is a portion of the wire bonding portion210recessed from the reverse surface212in the z direction. The thickness (the dimension in the z direction) of a portion of the wire bonding portion210provided with the recess213is about one-half of the thickness of a portion of the wire bonding portion210provided with the reverse surface212. The recess213is formed by, for example, subjecting the second lead2to half etching.

Each terminal portion220is connected to the wire bonding portion210and has a rectangular shape as viewed in the z direction. In the example illustrated in the drawings, two terminal portions220are disposed on one end surface (end surface that faces away from the semiconductor device A1) of the wire bonding portion210so as to be spaced apart from each other in the x direction. Each terminal portion220has an obverse surface221, a reverse surface222, and an end surface223. The obverse surface221and the reverse surface222face away from each other in the z direction. The obverse surface221faces upward inFIG. 3. The obverse surface221of the terminal portion is flush with the obverse surface211of the wire bonding portion. The reverse surface222faces downward inFIG. 3. The reverse surface222of the terminal portion is flush with the reverse surface212of the wire bonding portion. The end surface223is a surface connecting the obverse surface221and the reverse surface222and faces outward in the y direction. The reverse surface212of the wire bonding portion, the reverse surfaces222of the terminal portions, and the end surfaces223of the terminal portions are exposed from the sealing resin8and connected to each other to function as an external connection terminal.

The coupling portion230is connected to the outer side of the wire bonding portion210in the x direction (the left side inFIG. 2). The thickness (the dimension in the z direction) of the coupling portion230is about the same as the thickness of a portion of the wire bonding portion210provided with the recess213. The coupling portion230is formed by, for example, subjecting the second lead2to half etching. The coupling portion230has an obverse surface231, a reverse surface232, and an end surface233. The obverse surface231and the reverse surface232face away from each other in the z direction. The obverse surface231faces upward inFIG. 3. The obverse surface231of the coupling portion is flush with the obverse surface211of the wire bonding portion. Accordingly, the obverse surface211of the wire bonding portion, the obverse surfaces221of the terminal portions, and the obverse surface of the coupling portion231together form a flat surface (seeFIG. 2). The reverse surface232faces downward inFIG. 3. Of surfaces connecting the obverse surface231and the reverse surface232, the end surface233is a surface facing in the x direction and is exposed from the sealing resin8.

InFIG. 2, the third lead3is disposed adjacent to the upper side of the semiconductor device A1and extends over the entire width of the semiconductor device A1in the x direction. The third lead3includes a wire bonding portion310, a plurality of terminal portions320, and a plurality of coupling portions330.

The wire bonding portion310has a rectangular shape elongated in the x direction as viewed in the z direction. The wire bonding portion310has an obverse surface311, a reverse surface312, and a recess313. The obverse surface311and the reverse surface312face away from each other in the z direction. The obverse surface311faces upward inFIG. 3. The obverse surface311is a surface to which the bonding wires72are bonded. The reverse surface312faces downward inFIG. 3. The reverse surface312is exposed from the sealing resin8to serve as a back terminal. The recess313is a portion of the wire bonding portion310recessed from the reverse surface312in the z direction. The thickness (the dimension in the z direction) of a portion of the wire bonding portion310provided with the recess313is about one-half of the thickness of a portion of the wire bonding portion310provided with the reverse surface312. The recess313is formed by, for example, subjecting the third lead3to half etching.

Each terminal portion320is connected to the wire bonding portion310and has a rectangular shape as viewed in the z direction. In the example illustrated inFIG. 2, four terminal portions320are disposed on one end surface (end surface that faces away from the semiconductor device A1) of the wire bonding portion310so as to be spaced apart from each other in the x direction. Each terminal portion320has an obverse surface321, a reverse surface322, and an end surface323. The obverse surface321and the reverse surface322face away from each other in the z direction. The obverse surface321faces upward inFIG. 3. The obverse surface321of each terminal portion is flush with the obverse surface311of the wire bonding portion. The reverse surface322faces downward inFIG. 3. The reverse surface322of each terminal portion is flush with the reverse surface312of the wire bonding portion. The end surface323is a surface connecting the obverse surface321and the reverse surface322and faces outward in the y direction. The reverse surface312of the wire bonding portion, the reverse surfaces322of the terminal portions, and the end surfaces323of the terminal portions are exposed from the sealing resin8and connected to each other to function as an external connection terminal.

In the example illustrated inFIG. 2, two coupling portions330are connected to both ends of the wire bonding portion310in the x direction, respectively. The thickness (the dimension in the z direction) of each coupling portion330is about the same as the thickness of a portion of the wire bonding portion310provided with the recess313. The coupling portions330are formed by, for example, subjecting the third lead3to half etching. Each coupling portion330has an obverse surface331, a reverse surface332, and an end surface333. The obverse surface331and the reverse surface332face away from each other in the z direction. The obverse surface331faces upward inFIG. 3. The obverse surface331of each coupling portion is flush with the obverse surface311of the wire bonding portion. Accordingly, the obverse surface311of the wire bonding portion, the obverse surfaces321of the terminal portions, and the obverse surfaces of the coupling portions331together form a flat surface (seeFIG. 2). The reverse surface332faces downward inFIG. 3. Of surfaces connecting the obverse surface331and the reverse surface332, the end surface333is a surface facing in the x direction and is exposed from the sealing resin8.

InFIG. 2, the fourth lead4is disposed at the lower right corner of the semiconductor device A1, and includes a wire bonding portion410, a terminal portion420, and a coupling portion430.

The wire bonding portion410has a rectangular shape elongated in the x direction as viewed in the z direction. The wire bonding portion410has an obverse surface411, a reverse surface412, and a recess413. The obverse surface411and the reverse surface412face away from each other in the z direction. The obverse surface411faces upward inFIG. 3. The obverse surface411is a surface to which the bonding wire73is bonded. The reverse surface412faces downward inFIG. 3. The reverse surface412is exposed from the sealing resin8to serve as a back terminal. The recess413is a portion of the wire bonding portion410recessed from the reverse surface412in the z direction. The thickness (the dimension in the z direction) of a portion of the wire bonding portion410provided with the recess413is about one-half of the thickness of a portion of the wire bonding portion410provided with the reverse surface412. The recess413is formed by, for example, subjecting the fourth lead4to half etching.

The terminal portion420is connected to the wire bonding portion410and has a rectangular shape as viewed in the z direction. The terminal portion420is disposed on one end surface (end surface that faces away from the semiconductor device A1) of the wire bonding portion410. The terminal portion420has an obverse surface421, a reverse surface422, and an end surface423. The obverse surface421and the reverse surface422face away from each other in the z direction. The obverse surface421faces upward inFIG. 3. The obverse surface421of the terminal portion is flush with the obverse surface411of the wire bonding portion. The reverse surface422faces downward inFIG. 3. The reverse surface422of the terminal portion is flush with the reverse surface412of the wire bonding portion. The end surface423is a surface connecting the obverse surface421and the reverse surface422and faces outward in the y direction. The reverse surface412of the wire bonding portion, the reverse surface422of the terminal portion, and the end surface423of the terminal portion are exposed from the sealing resin8and connected to each other to function as an external connection terminal.

InFIG. 2, the coupling portion430is connected to the right side of the wire bonding portion410in the x direction. The thickness (the dimension in the z direction) of the coupling portion430is about the same as the thickness of a portion of the wire bonding portion410provided with the recess413. The coupling portion430is formed by, for example, subjecting the fourth lead4to half etching. The coupling portion430has an obverse surface431, a reverse surface432, and an end surface433. The obverse surface431and the reverse surface432face away from each other in the z direction. The obverse surface431faces upward inFIG. 3. The obverse surface431of the coupling portion is flush with the obverse surface411of the wire bonding portion. Accordingly, the obverse surface411of the wire bonding portion, the obverse surface421of the terminal portion, and the obverse surface431of the coupling portion together form a flat surface (seeFIG. 2). The reverse surface432faces downward inFIG. 3. Of surfaces connecting the obverse surface431and the reverse surface432, the end surface433is a surface facing in the x direction and is exposed from the sealing resin8.

InFIG. 2, as viewed in the z direction, the fifth lead5is adjacent to the lower side of the semiconductor device A1and is disposed between the second lead2and the fourth lead4. The fifth lead5includes a wire bonding portion510and a terminal portion520.

The wire bonding portion510has a rectangular shape elongated in the x direction as viewed in the z direction. The wire bonding portion510has an obverse surface511, a reverse surface512, and a recess513. The obverse surface511and the reverse surface512face away from each other in the z direction. The obverse surface511faces upward inFIG. 3. The obverse surface511is a surface to which the bonding wires74are bonded. The reverse surface512faces downward inFIG. 3. The reverse surface512is exposed from the sealing resin8to serve as a back terminal. The recess513is a portion of the wire bonding portion510recessed from the reverse surface512in the z direction. The thickness (the dimension in the z direction) of a portion of the wire bonding portion510provided with the recess513is about one-half of the thickness of a portion of the wire bonding portion510provided with the reverse surface512. The recess513is formed by, for example, subjecting the fifth lead5to half etching.

The terminal portion520is connected to the wire bonding portion510and has a rectangular shape as viewed in the z direction. InFIG. 2, the terminal portion520is disposed on one end surface (end surface that faces away from the semiconductor device A1) of the wire bonding portion510. The terminal portion520has an obverse surface521, a reverse surface522, and an end surface523. The obverse surface521and the reverse surface522face away from each other in the z direction. The obverse surface521faces upward inFIG. 3. The obverse surface521of the terminal portion is flush with the obverse surface511of the wire bonding portion. The reverse surface522faces downward inFIG. 3. The reverse surface522of the terminal portion is flush with the reverse surface512of the wire bonding portion. The end surface523is a surface connecting the obverse surface521and the reverse surface522, and faces outward in the y direction. The reverse surface512of the wire bonding portion, the reverse surface522of the terminal portion, and the end surface523of the terminal portion are exposed from the sealing resin8and connected to each other to function as an external connection terminal.

The semiconductor element6is a component that performs electrical functions of the semiconductor device A1. The semiconductor element6is a semiconductor element using a nitride semiconductor. In the present example, the semiconductor element6is a high electron mobility transistor (HEMT) using gallium nitride (GaN). The semiconductor element6includes an element body60, first electrodes61, a second electrode62, third electrodes63, and fourth electrodes64.

The element body60has an obverse surface6aand a reverse surface6b. As shown inFIG. 3etc., the obverse surface6aand the reverse surface6bface away from each other in the z direction. The obverse surface6afaces upward inFIG. 3, and the reverse surface6bfaces downward inFIG. 3. As shown inFIG. 7, the element body60includes a substrate601, a buffer layer602, a first nitride semiconductor layer603, a second nitride semiconductor layer604, a third nitride semiconductor layer605, a protective layer606, and a conductive portion607.

The substrate601is, for example, an Si substrate and has a predetermined low resistance value. The thickness (the dimension in the z direction) of the substrate601is about 400 to 600 μm. The buffer layer602is formed on the substrate601and has a multilayer structure composed of a plurality of nitride semiconductor layers. In the example illustrated in the drawings, the buffer layer602is composed of a first buffer layer (which is an AlN film) in contact with the substrate601and a second buffer layer (which is an AlGaN film) laminated on the first buffer layer. The first nitride semiconductor layer603is a GaN layer formed on the buffer layer602through epitaxial growth and serves as an electron transit layer. The second nitride semiconductor layer604is an AlGaN layer formed on the first nitride semiconductor layer603through epitaxial growth and serves as an electron supply layer. The total thickness (the dimension in the z direction) of the buffer layer602, the first nitride semiconductor layer603, and the second nitride semiconductor layer604is about 2 μm, which is smaller than the thickness of the substrate601. Two-dimensional electron gas (2DEG) generated in the vicinity of the interface between the first nitride semiconductor layer603and the second nitride semiconductor layer604is used as a current flow path.

The third nitride semiconductor layer605is a p-type GaN layer laminated on the second nitride semiconductor layer604through epitaxial growth. The fourth electrodes64are formed on the third nitride semiconductor layer605and functions as gate electrodes. The protective film606is, for example, an SiN film, and covers the second nitride semiconductor layer604, the third nitride semiconductor layer605, and the fourth electrodes64. A portion of each of the fourth electrodes64is exposed from the protective film606(seeFIGS. 2 and 6). The first electrodes61and the third electrodes63are formed on the protective film606, and portions of the respective first electrodes61and third electrodes63pass through the protective film606to be in contact with the second nitride semiconductor layer604. The first electrodes61and the third electrodes63are spaced apart from each other (seeFIGS. 2 and 6). The first electrodes61are formed so as to cover the third nitride semiconductor layer605and the fourth electrodes64, respectively. The first electrodes61function as source electrodes. The third electrodes63function as drain electrodes. As shown inFIGS. 2 and 6, the first electrodes61, the third electrodes63, and the fourth electrodes64are disposed on the obverse surface6aof the element.

In response to a voltage signal applied to the fourth electrodes (gate electrodes)64, a current (“main current”) flows from the third electrodes (drain electrodes)63to the first electrodes61(source electrodes). The semiconductor element6switches between a state where the main current flows and a state where the main current does not flow. That is, the switching element6performs switching of the main current.

The second electrode62is formed on the reverse surface (the surface that faces away from the surface on which the buffer layer602is formed) of the substrate601, and is disposed on the reverse surface6bof the element.

Each conductive portion607is, for example, a via hole, and passes through the second nitride semiconductor layer604, the first nitride semiconductor layer603, and the buffer layer602to reach the substrate601. The conductive portion607is in contact with the portion of the first electrode61that passes through the protective film606to be electrically connected to the first electrode61, and is also electrically connected to the second electrode62via the substrate601. Accordingly, the first electrodes61and the second electrode62are at the same potential. The conductive portion607may pass through the substrate601to reach the second electrode62. The configuration of the semiconductor element6described above is merely an illustrative example, and the present disclosure is not limited thereto.

As shown inFIG. 2, the semiconductor element6is mounted in a central portion both in the x direction and the y direction on the obverse surface111. As shown inFIG. 5, the semiconductor element6is mounted on the obverse surface111of the first lead1in a state where the reverse surface6bthereof faces the obverse surface111with a conductive bonding material interposed between the reverse surface6band the obverse surface111. With this configuration, the second electrode62of the semiconductor element6is electrically connected to the first lead1via a conductive bonding material. Accordingly, the second electrode62is at the same potential as the first lead1. Also, the first electrodes61are electrically connected to the second electrode62via the conductive portions607, and thus are at the same potential as the first lead1.

The plurality of bonding wires71are connected to first electrodes61of the semiconductor element6and to the wire bonding portion obverse surface211of the second lead2. With this configuration, the second lead2is electrically connected to the first electrode61(source electrode) of the semiconductor element6to serve as a source terminal. A main current to be subjected to switching flows through the source terminal. The plurality of bonding wires72are connected to the third electrodes63of the semiconductor element6and the wire bonding portion obverse surface311of the third lead3. With this configuration, the third lead3is electrically connected to the third electrode63(drain electrodes) of the semiconductor element6to serve as a drain terminal. The bonding wire73is connected to a fourth electrode64of the semiconductor element6and the wire bonding portion obverse surface411of the fourth lead4. With this configuration, the fourth lead4is electrically connected to a fourth electrode64(gate electrode) of the semiconductor element6to serve as a gate terminal. The plurality of bonding wires74are connected to a first electrode61of the semiconductor element6and the wire bonding portion obverse surface511of the fifth lead5. With this configuration, the fifth lead5is electrically connected to the first electrode61(source electrode) of the semiconductor element6to serve as a source sense terminal. The source sense terminal is a terminal for detecting the potential of the first electrode61(source electrode), and a main current to be subjected to switching does not flow therethrough. Accordingly, the number of bonding wires74is smaller than the number of bonding wires71through which a main current to be subjected to switching flows. The numbers of the bonding wires71to74are not limited to the examples illustrated in the drawings. Instead of the bonding wires71to74, metal plates made of Cu or the like may be used, for example.

The sealing resin8covers portions of the respective leads1to5, the semiconductor element6, and the bonding wires71to74. The sealing resin8is a black epoxy resin, for example.

The sealing resin8has an obverse surface81, a reverse surface82, and side surfaces83. The obverse surface81and the reverse surface82face away from each other in the z direction. The obverse surface81faces upward inFIG. 3, and the reverse surface82faces downward inFIG. 3. The side surfaces83are surfaces connecting the obverse surface81and the reverse surface82and face in either the x direction or the y direction. In the example illustrated in the drawings, the side surfaces83are four flat surfaces each having a rectangular shape. However, the present disclosure is not limited thereto.

As shown inFIGS. 1 and 2, the coupling portion end surfaces123of the first lead1, the terminal portion end surfaces223and the coupling portion end surface233of the second lead2, the terminal portion end surfaces323and the coupling portion end surfaces333of the third lead3, the terminal portion end surface423and the coupling portion end surface433of the fourth lead4, and the terminal portion end surface523of the fifth lead5are flush with the side surfaces83of the sealing resin8. Also, the reverse surface112of the first lead1, the wire bonding portion reverse surface212and the terminal portion reverse surfaces222of the second lead2, the wire bonding portion reverse surface312and the terminal portion reverse surfaces322of the third lead3, the wire bonding portion reverse surface412and the terminal portion reverse surface422of the fourth lead4, and the wire bonding portion reverse surface512and the terminal portion reverse surface522of the fifth lead5are flush with the reverse surface82of the sealing resin8.

An example of a method for producing the semiconductor device A1will be described with reference toFIGS. 8 and 9.

As shown inFIG. 8, a lead frame10is prepared. The lead frame10is a plate-shaped material that is to be processed into leads1to5. An obverse surface1010of the lead frame10is a surface that is processed into the obverse surface111and the coupling portion obverse surfaces121of the first lead1, the wire bonding portion obverse surface211, the terminal portion obverse surfaces221, and the coupling portion obverse surface231of the second lead2, the wire bonding portion obverse surface311, the terminal portion obverse surfaces321, and the coupling portion obverse surfaces331of the third lead3, the wire bonding portion obverse surface411, the terminal portion obverse surface421, and the coupling portion obverse surface431of the fourth lead4, and the wire bonding portion obverse surface511and the terminal portion obverse surface521of the fifth lead5. The respective portions of the obverse surface1010of the lead frame10are flush with each other. InFIG. 8, two types of hatching patterns with different line densities are applied to the lead frame10. Regions with a relatively dense hatching pattern are regions with a greater thickness (the dimension in the z direction). On the other hand, regions with a relatively sparse hatching pattern are regions with a smaller thickness (the dimension in the z direction). These regions are formed by, for example, subjecting the lead frame10to half etching. The base material of the lead frame10is Cu, for example. However, the present disclosure is not limited thereto.

Next, as shown inFIG. 9, the semiconductor element6is bonded to a mounting portion110of the lead frame10using a conductive bonding material. Thereafter, the bonding wires71to74are bonded to the respective electrodes of the semiconductor element6and the lead frame10. Subsequently, a resin material is hardened to form a sealing resin (not shown) that covers portions of the lead frame10, the semiconductor element6, and the bonding wires71to74. This sealing resin is formed over the entire region shown inFIG. 9, for example. Then, the lead frame10and the sealing resin are cut along a cutting line1020. As a result, the above-described semiconductor device A1is obtained.

Next, functions and effects of the semiconductor device A1will be described.

As described above, in the semiconductor device A1, the second electrode62of the semiconductor element6is connected to the first lead1, and the first electrodes61are connected to the second lead2via the bonding wires71. That is, the semiconductor element6is connected to both the first lead1and the second lead2. On the other hand, the first lead1and the second lead2are spaced apart from each other. With this configuration, a current circulation path including the first lead1, the second electrode62, the conductive portions607, the first electrodes61, the bonding wires71, and the second lead2is not formed. Accordingly, a current is kept from flowing along the lamination direction (z direction) of the second nitride semiconductor layer604and the first nitride semiconductor layer603. As a result, undesirable changes in properties of the second nitride semiconductor layer604and the first nitride semiconductor layer603are suppressed, which contributes to improvement in the long-term reliability of the semiconductor element6.

In the semiconductor device A1, the separation distance between the third lead3and the first lead1is greater than the separation distance between the second lead2(or the fifth lead5and the fourth lead4) and the first lead1. Such a configuration helps to increase the dielectric strength between the first lead1and the third lead3, to which a relatively high voltage is applied.

In the semiconductor device A1, the reverse surface112of the first lead1is exposed from the reverse surface82of the sealing resin8. With this configuration, the first lead1functions as a back terminal when the semiconductor device A1is mounted on a circuit board or the like, and also functions as a heat dissipator for dissipating heat generated by the semiconductor element6.

The semiconductor device A1includes the fifth lead5in addition to the second lead2. With this configuration, the semiconductor device A1can have, in addition to a source terminal (the second lead2) through which a main current to be subjected to switching flows, a source sense terminal (the fifth lead5through which a main current does not flow) for detecting the electric potential of the source electrodes (the first electrodes61). Also, by setting the number of bonding wires71connected to the second lead2to be larger than the number of bonding wires74connected to the fifth lead5, the resistance to a current that flows via the second lead2can be set low. Also, the number of terminal portions220of the second lead2is larger than the number of terminal portions520of the fifth lead5, and the second lead2has a larger dimension in the x direction than the fifth lead5does. With such a configuration, the cross-sectional area of the current path can be relatively increased, whereby the resistance to a current that flows through the second lead2can be reduced.

Although an example where the semiconductor element6is a HEMT has been described above, the present disclosure is not limited thereto. The configuration of the semiconductor element6is not limited as long as the first electrodes61disposed on the obverse surface6aand the second electrode62disposed on the reverse surface6bare electrically connected to each other via the conductive portions607. The conductive portion607is not limited to a via hole as long as it allows electrical communication between the first electrode61and the second electrode62. For example, as shown inFIG. 10, the conductive portion607may be formed on a side surface of the element body60.

In the above-described example, the coupling portion end surfaces123of the first lead1, the terminal portion end surfaces223and the coupling portion end surface233of the second lead2, the terminal portion end surfaces323and the coupling portion end surfaces333of the third lead3, the terminal portion end surface423and the coupling portion end surface433of the fourth lead4, and the terminal portion end surface523of the fifth lead5are flush with the side surfaces83of the sealing resin8. However, the present disclosure is not limited thereto. These end surfaces may protrude from the side surfaces83or may be recessed inward from the side surfaces83. Each of the end surfaces may be flat, curved, or have recesses and protrusions.

A semiconductor device A2according to Example 2 will be described with reference toFIGS. 11 and 12. In these drawings, components that are identical or similar to those of the above-described semiconductor device A1are given the same reference signs, and redundant explanations thereof are omitted as appropriate.

In the semiconductor device A2, the shape of a first lead1is different from that in the semiconductor device A1. In the semiconductor device A2, a surface of the first lead1that faces away from an obverse surface111does not have a portion corresponding to the reverse surface112in Example 1, and the entire surface forms a recess113(or it can be said that the surface is not provided with a recess and is entirely flat). Accordingly, a mounting portion110is not exposed from a reverse surface82of a sealing resin8. Further, the first lead1includes terminal portions130instead of the coupling portions120. Each terminal portion130has an obverse surface131, a reverse surface132, and an end surface133. The obverse surface131and the reverse surface132face away from each other in the z direction. The obverse surface131faces upward inFIG. 11. The obverse surface131of the terminal portion and the obverse surface111are flush with each other. The reverse surface132of each terminal portion faces downward inFIG. 11. The thickness (the dimension in the z direction) of each terminal portion130is about twice as great as that of the mounting portion110, and the reverse surface132of each terminal portion is exposed from the reverse surface82of the sealing resin8. The end surface133of the terminal portion is a surface connecting the obverse surface131and the reverse surface132, and faces outward in the x direction. The reverse surface132and the end surface133are exposed from the sealing resin8and connected to each other to function as a terminal.

Also, in the semiconductor device A2, the first lead1and the second lead2are spaced apart from each other. Accordingly, a current circulation path, which has conventionally been a problem, is not formed, whereby a current is kept from flowing along the lamination direction (z direction) of nitride semiconductor layers603and604. This improves the long-term reliability of the semiconductor element6.

In the semiconductor device A2, the first lead1includes, as terminals, the terminal portions130exposed from the sealing resin8. Each terminal portion130is a terminal configured such that it has the end surface133exposed from a side surface83of the sealing resin and the reverse surface132exposed from the reverse surface82of the sealing resin and the end surface133and the reverse surface132are connected to each other. When the semiconductor device A2is mounted on a circuit board, these terminals are joined to circuit wiring formed on the circuit board through soldering. Since solder fillets are formed on the end faces133of the terminal portions, whether the terminal portions130are joined to the circuit wiring can be visually confirmed.

A semiconductor device A3according to Example 3 will be described with reference toFIGS. 13 and 14. In these drawings, components that are identical or similar to those of the above-described semiconductor device A1are given the same reference signs, and redundant explanations thereof are omitted as appropriate.

In the semiconductor device A3, the shape of a first lead1is different from that in the semiconductor device A1. The first lead1of the semiconductor device A3includes terminal portions130that are similar to those in the semiconductor device A2. The configuration of the terminal portions130is similar to that of the terminal portions130in Example 2. In the semiconductor device A3, reverse surfaces132of the terminal portions are flush with a reverse surface112. The reverse surface112, the reverse surfaces132of the terminal portions, and end surfaces133of the terminal portions are exposed from a sealing resin8and connected to each other to function as terminals.

Also, in the semiconductor device A3, the first lead1and a second lead2are spaced apart from each other, and a current circulation path is thus not formed. Accordingly, a current is kept from flowing along the lamination direction (z direction) of nitride semiconductor layers603and604, which improves the long-term reliability of a semiconductor element6.

In the semiconductor device A3, the first lead1has the terminal portions130exposed from the sealing resin8and the reverse surface112is exposed from a reverse surface82of the sealing resin8. Accordingly, the joined state of the first lead1can be checked based on the appearance thereof after mounting the semiconductor device A3on a circuit board, and further, the first lead1can also function as a heat dissipator for dissipating heat generated by the semiconductor element6.

A semiconductor device A4according to Example 4 will be described with reference toFIG. 15. InFIG. 15, components that are identical or similar to those of the above-described semiconductor device A1are given the same reference signs, and redundant explanations thereof are omitted. InFIG. 15, for the sake of convenience in understanding, a sealing resin8is not shown and the outer shape thereof is indicated with an imaginary line (double-dot-dash line).

The semiconductor device A4is different from the semiconductor device A1in that it does not include a source sense terminal (fifth lead5). A second lead2of the semiconductor device A4extends to a position near a fourth lead4in the x direction, and includes three terminal portions220. The semiconductor device A4may also be configured such that the second lead2is the same as the second lead2in the semiconductor device A1and does not include the fifth lead5in the semiconductor device A1.

Also, in the semiconductor device A4, a first lead1and the second lead2are spaced apart from each other, and a current circulation path is thus not formed. Accordingly, a current is kept from flowing along the lamination direction (z direction) of nitride semiconductor layers603and604, which improves the long-term reliability of a semiconductor element6.

A semiconductor device A5according to Example 5 will be described with reference toFIG. 16. InFIG. 16, components that are identical or similar to those of the above-described semiconductor device A1are given the same reference signs, and redundant explanations thereof are omitted as appropriate.

The semiconductor device A5is different from the semiconductor device A1in that a semiconductor element6is configured such that conductive portions607are in contact with third electrodes63instead of with first electrodes61and electrically connected to the third electrodes63. In the semiconductor device A5, the conductive portions607are electrically connected to the third electrodes63and also electrically connected to a second electrode62via a substrate601. Accordingly, the third electrodes63and the second electrode62are at the same potential. The second electrode62of the semiconductor element6is electrically connected to a first lead1using a conductive bonding material. Accordingly, the second electrode62of the semiconductor element6is at the same potential as the first lead1. The third electrodes63are electrically connected to the second electrode62via the conductive portions607and thus are at the same potential as the first lead1.

In the semiconductor device A5, the first lead1and the third lead3are spaced apart from each other. Accordingly, even if the second electrode62of the semiconductor element6is connected to the first lead1and if the third electrodes63and the third lead3are connected by bonding wires72, a current circulation path including the first lead1, the second electrode62, the conductive portions607, the third electrodes63, the bonding wires72, and the third lead3is not formed. Accordingly, a current is kept from flowing along the lamination direction (z direction) of a second nitride semiconductor layer604, a first nitride semiconductor layer603, and a buffer layer602, which improves the long-term reliability of the semiconductor element6.

A semiconductor device A6according to Example 6 will be described with reference toFIG. 17. InFIG. 17, components that are identical or similar to those of the above-described semiconductor device A1are given the same reference signs, and redundant explanations thereof are omitted as appropriate.

In the semiconductor device A6, a semiconductor element6does not include a conductive portion607, and first electrodes61and a first lead1are connected to each other by bonding wires75. The bonding wires75are connected to the first electrodes61of the semiconductor element6and an obverse surface111of the first lead1. With this configuration, the first lead1is at the same potential as the first electrodes61of the semiconductor element6. A second electrode62is connected to the first lead1using a conductive bonding material, and is at the same potential as the first lead1. Accordingly, the first electrodes61and the second electrode62are electrically connected to each other and are at the same potential.

Also, in the semiconductor device A6, the first lead1and a second lead2are spaced apart from each other, and a current circulation path, which has conventionally been a problem, is not formed. Accordingly, the semiconductor device A6can exhibit effects similar to those in Example 1.

The semiconductor device according to the present disclosure is not limited to the above-described examples. Various modifications in design may be made freely in the specific structure of each part of the semiconductor device according to the present disclosure.