JP5139383B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to a technique effective when applied to the manufacture of a semiconductor device in which a semiconductor chip having a large amount of heat generation is sealed.

  As one of high-power semiconductor devices, a semiconductor device in which a semiconductor chip on which a power transistor is formed is incorporated in a sealed body is known. Examples of the power transistor include a power MOSFET (Metal Oxide Semiconductor Field-Effect-Transistor), an IGBT (Insulated Gate Bipolar Transistor), and a bipolar power transistor.

  The power MOSFET device has a structure in which a power MOSFET chip is incorporated in a sealed body. As one of power MOSFET devices, there is a structure in which a metal member serving as a drain terminal is exposed on the bottom surface of a sealing body made of an insulating resin, and a source lead terminal and a gate lead terminal are arranged on one side of the sealing body. Are known. The source lead terminal and the gate lead terminal are partially bent, and a part thereof is exposed on the upper surface of the sealing body. The source lead terminal and the gate lead terminal extending into the sealing body are electrically connected to the source electrode and the gate electrode on the upper surface of the semiconductor chip fixed on the metal member, respectively. These leads are ultrasonically bonded to Au bumps arranged uniformly on the source electrode and the gate electrode by a wire ball bonding method. (For example, patent document 1).

  On the other hand, in manufacturing a semiconductor device (LFPAK: Loss Free Package), a technology is known in which a gold bump is formed on the main surface of a semiconductor wafer, and then the semiconductor wafer is diced to form a semiconductor chip having a gold bump (bump electrode). (For example, Patent Document 2).

JP 2000-223634 A JP 2003-86787 A

The present inventor has examined the improvement of heat dissipation and the reduction of mounting cost of a high-power semiconductor device in which the sealing body is formed of an insulating resin.
As disclosed in Patent Document 1, as one of high-power semiconductor devices, lead terminals and dies made of metal are respectively formed on the top and back surfaces of a sealing housing (sealing body) in order to improve heat dissipation. A structure in which a terminal (electrode plate) is exposed is known.

  In this structure, the electrode plate (die terminal) to which the back electrode of the semiconductor chip (electrode provided over substantially the entire area of the chip) is connected is exposed on the lower surface of the sealing body, and the upper surface (main surface) of the semiconductor chip is exposed. An electrode plate (lead terminal) connected to the electrode (bump electrode) is exposed on the lower surface of the sealing body. When the semiconductor device is mounted on the mounting substrate, the electrode plate (die terminal) faces the mounting substrate.

  In order to dissipate heat from the electrode plate exposed on the lower surface of the sealing body to the mounting board, for example, it is necessary to incorporate a copper layer with good thermal conductivity into the mounting board, which increases the cost of the mounting board. This hinders the reduction of mounting cost.

One object of the present invention is to provide a semiconductor device with good heat dissipation and a method for manufacturing the same.
One object of the present invention is to provide a semiconductor device and a method for manufacturing the same that can reduce mounting costs.
One object of the present invention is to provide an electronic device that has good heat dissipation and can reduce the mounting cost.
The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

The following is a brief description of an outline of typical inventions disclosed in the present application.
(1) The semiconductor device of the present invention
A sealing body made of an insulating resin having an upper surface and a lower surface opposite to the upper surface and a side surface connecting the upper surface and the lower surface;
A semiconductor chip located in the sealing body, having a plurality of electrodes on a first main surface, and having a back electrode on a second main surface opposite to the first main surface;
One end side is located in the sealing body, the electrode of the semiconductor chip is connected to the upper surface of the one end side, and the other end side projects and bends to the side of the sealing body for gull wing type surface mounting A plurality of first electrode plates forming terminals;
The upper surface of one end side is exposed on the upper surface of the sealing body, the back surface electrode of the semiconductor chip is connected to the lower surface that is the opposite surface of the upper surface of the one end side, and the other one end side is the And a second electrode plate that protrudes to the side of the sealing body and bends to form a gull-wing surface mounting terminal.

  In addition, a portion of the second electrode plate that protrudes from the sealing body to the side of the sealing body is branched into a plurality of branches, and the plurality of branched branches constitute the surface mounting terminals.

  In addition, a recess is formed in the periphery of a part of the upper surface of the second electrode plate, and the resin plate forming the sealing body is embedded in the recess. In addition, a recess is formed on the upper surface of at least a part of the branch start portion of the branch end and the upper surface of the electrode plate edge extending between the adjacent branch ends, and opposite to the electrode plate corresponding to the recess. The surface side part protrudes. A resin forming the sealing body is embedded in the recess, and the protruding portion bites into the resin forming the sealing body.

  A transistor (field effect transistor) is formed on the semiconductor chip, and a first electrode (source electrode) and a control electrode (gate electrode) made of a protruding electrode are provided on the first main surface of the semiconductor chip. The second main surface is provided with a second electrode (drain electrode) as a back electrode. The source electrode is connected to the first electrode plate, and the gate electrode is connected to the other first electrode plate.

Such a semiconductor device is manufactured by the following manufacturing method.
Providing patterned first and second lead frames;
A semiconductor chip having a plurality of electrodes (source electrode and gate electrode) on a first main surface and having a back electrode (drain electrode) on a second main surface opposite to the first main surface is prepared. A plurality of electrodes (source electrode and gate electrode) on the first main surface of the semiconductor chip, and a plurality of first electrode plates (source electrode plate, gate electrode plate) on the first lead frame. Respectively electrically connecting to
Electrically connecting the back electrode (drain electrode) of the semiconductor chip to a second electrode plate (drain electrode plate) of the second lead frame with a conductive adhesive;
Insulating so as to cover one end side of the semiconductor chip and the first lead frame and to expose a surface side of the second electrode plate (drain electrode plate) of the second lead frame where the semiconductor chip is not fixed. Forming a sealing body with a conductive resin;
Cutting and removing unnecessary portions of the lead frame, and forming a surface mounting terminal by forming an electrode plate portion protruding from the sealing body.

  In addition, the electrode plate portions of the first and second lead frames extending from the inside to the outside of the sealing body have a structure in which slits are provided at predetermined intervals to form branch pieces having a predetermined width. It has become. That is, the portion of the source electrode plate and the drain electrode plate that protrudes from the sealing body has a structure in which slits are provided at predetermined intervals and branch pieces having a predetermined width are provided. The ends (branch ends) of these branch pieces respectively form surface mounting terminals.

  Further, in the second electrode plate portion (drain electrode plate) of the second lead frame covered with the sealing body, a partial peripheral edge of the upper surface of the second electrode plate in contact with the sealing body is: For example, a depression is provided which is formed one step lower by etching or molding by a press machine and is opened on the peripheral side of the electrode plate. For example, a depression is formed in at least a part of the branch start portion of the branch piece and an edge of the electrode plate extending between adjacent branch pieces by extrusion molding with a press machine. At this time, the opposite surface side of the electrode plate corresponding to the depression protrudes. In addition, a recess is formed in the periphery of the drain electrode plate by etching up to a predetermined depth on the upper surface side.

  The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

  According to the means of (1), (a) the semiconductor device has the drain electrode plate whose upper surface is exposed on the upper surface of the sealing body. A semiconductor chip is connected to the drain electrode plate via a back electrode of the semiconductor chip. The back electrode is approximately the same size as the semiconductor chip. As a result, the heat generated in the semiconductor chip can be efficiently transferred to the drain electrode plate. Therefore, by attaching a heat radiator to the drain electrode plate, heat can be efficiently dissipated to the outside, and a semiconductor device and a semiconductor device mounting structure (that is, an electronic device) with good heat dissipation can be provided. . Further, even when a heat radiator is not attached, heat can be dissipated into the atmosphere from the surface of the wide drain electrode plate.

  Since the semiconductor device has a structure that dissipates heat from the upper surface side of the sealing body, it is not necessary to consider heat dissipation to the mounting board as in the past, and it has a special specification with high cost that makes heat transfer good. Does not require a mounting board. As a result, the mounting cost can be reduced.

(B) When manufacturing a semiconductor device using a lead frame, the drain electrode plate portion protruding to the outside from the sealing body is formed into a gull wing shape suitable for surface mounting. Since this molding portion is provided with slits to form a plurality of branch pieces (lead portions), it is easier than molding a single plate. As a result, there is an effect that the semiconductor chip and the lead can be molded with high accuracy without causing damage to the connecting portion (adhesive, gate protruding electrode and source protruding electrode portion). That is, since the drain electrode plate is thicker than the source electrode plate and the gate electrode plate in order to reduce electric resistance, if the drain electrode plate is formed into a gull wing shape, bending with a larger load can be achieved. Become. As a result, a large stress acts on the drain electrode plate connected to the sealing body in such a direction that the drain electrode plate is pulled out from the sealing body, thereby causing damage to the connection portion with the semiconductor chip. Damage to the connection portion is not preferable because it increases the resistance R _{ds (ON)} between the source and the drain. In the present invention, since a plurality of slits are provided in the drain electrode plate to be formed into a gull wing shape to form a plurality of branch pieces (leads), it is not necessary to apply a large load during molding. As a result, no great stress is applied to the drain electrode plate during molding, and damage to the connection parts on the front and back sides of the semiconductor chip can be prevented. The same applies to the source electrode plate. By forming a plurality of slits in the source electrode plate to form a plurality of branch pieces (lead portions), the source electrode plate is molded without causing damage to the connection portion with the semiconductor chip. be able to.

  (C) The drain electrode plate is sealed in the product state by partially forming a recess on the upper surface of the drain electrode plate located in the sealing body and filling the recess with a resin that forms the sealing body. It becomes difficult to drop off. In the manufacturing stage of the semiconductor device, the upper surface of the drain electrode plate located in the sealing body is partially lowered to form a recess, or the back surface corresponding to the recess is protruded to form a protrusion. . As a result, at the stage where the sealing body is formed, the resin forming the sealing body enters the recess, and the projecting portion bites into the resin forming the sealing body. Therefore, the drain electrode plate is fixed (locked) to the sealing body (resin). For this reason, when the drain electrode plate is formed, the drain electrode plate does not move with respect to the sealing body, and can be formed without damaging the connection portion of the semiconductor chip.

It is a top view of the semiconductor device which is Example 1 of this invention. 1 is a perspective view illustrating an appearance of a semiconductor device according to a first embodiment. 1 is a front view of a semiconductor device according to a first embodiment. 1 is a rear view of a semiconductor device of Example 1. FIG. FIG. 3 is a right side view of the semiconductor device according to the first embodiment. FIG. 6 is a bottom view of the semiconductor device according to the first embodiment. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which follows the BB line of FIG. 3 is a plan view of a drain electrode plate in the semiconductor device of Example 1. FIG. It is a front view of the drain electrode plate. It is sectional drawing which follows the CC line of FIG. 4 is an enlarged cross-sectional view showing a part of a semiconductor chip incorporated in the semiconductor device of Example 1. FIG. 3 is a flowchart illustrating a method for manufacturing the semiconductor device according to the first embodiment. 6 is a plan view showing a part of a first lead frame used in the manufacture of the semiconductor device of Example 1. FIG. 7 is a plan view showing a part of a second lead frame used in the manufacture of the semiconductor device of Example 1. FIG. FIG. 6 is a plan view showing a part of the second lead frame. FIG. 6 is a plan view of a drain electrode plate portion of the second lead frame. It is a front view of the said drain electrode plate part. It is sectional drawing which follows the DD line | wire of FIG. 6 is a schematic plan view showing a state in which a semiconductor chip is mounted on a first lead frame in the manufacture of the semiconductor device of Example 1. FIG. 6 is a schematic plan view showing a state in which the drain electrode plate of the second lead frame is overlapped and connected to the semiconductor chip mounted on the first lead frame in the manufacture of the semiconductor device of Example 1. FIG. 6 is a schematic plan view showing a state where a sealing body is formed in the manufacture of the semiconductor device of Example 1. FIG. It is a schematic diagram which shows the state which performs marking with a laser in manufacture of the semiconductor device of the present Example 1. FIG. It is a partial schematic front view which shows the state which mounted the semiconductor device of the present Example 1 in multiple arrangement arrangement | positioning on the mounting board | substrate, and attached the heat radiator. FIG. 3 is a partial schematic plan view showing a state in which a plurality of semiconductor devices of Example 1 are arranged and mounted on a mounting board and a heat dissipating body is attached. It is sectional drawing which follows the EE line | wire of FIG. FIG. 4 is a partial schematic plan view showing a state in which a plurality of semiconductor devices of Example 1 are arranged and mounted on a mounting substrate. FIG. 3 is a partial schematic plan view showing a state in which a plurality of semiconductor devices of Example 1 are mounted in an array on a mounting substrate and covered with an insulating sheet. It is a typical expanded sectional view which shows the state which mounted the semiconductor device of the present Example 1 on the mounting board | substrate, and attached the heat radiator. It is a block diagram which shows the structure of a part of electronic device with which the semiconductor device of the present Example 1 is incorporated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment of the invention, and the repetitive description thereof is omitted.
[Example 1]
1 to 12 are diagrams relating to the structure of the semiconductor device according to the first embodiment. 13 to 23 are diagrams relating to the method of manufacturing the semiconductor device 1 according to the first embodiment. 24 to 30 are diagrams relating to a mounting structure of a semiconductor device which is a part of an electronic device in which the semiconductor device of the first embodiment is incorporated.

  In the first embodiment, an example in which the present invention is applied to a power MOSFET device (semiconductor device) will be described. The power MOSFET device incorporates a semiconductor chip on which a vertical power MOSFET is formed. A source (S) electrode that is a first electrode and a gate (G) electrode that is a control electrode are provided on the first main surface of the semiconductor chip, and a second surface that is opposite to the first main surface. The main surface has a structure in which a drain (D) electrode serving as a second electrode is provided. The second electrode is a back electrode provided over substantially the entire surface of the semiconductor chip.

  As shown in FIGS. 1 to 6, the semiconductor device (power MOSFET device) 1 includes a sealing body (package) 2 made of an insulating resin having a flat rectangular shape in appearance and both sides of the sealing body 2 ( A plurality of leads are projected side by side from the side surface. The leads protruding from both side surfaces are bent in a single step to form a gull-wing surface mounting terminal.

  As shown in FIGS. 2 and 5, four leads protrude from the right side surface of the sealing body 2 and are arranged at a predetermined pitch as shown in FIGS. 2 and 5. These four leads are drain leads 3. Further, four leads protrude from the left side surface of the sealing body 2 and are arranged at a predetermined pitch. One of these four leads is the gate lead 4 and the remaining three are the source leads 5. The leads on both side surfaces of the sealing body 2 are arranged to correspond to each other in a planar state (see FIGS. 1 and 6). Further, as shown in FIG. 6, a direction identification index 6 is provided on the lower surface of the sealing body 2. The index 6 is formed when the sealing body 2 is formed, and is formed by a circular depression provided in the sealing body 2.

  As shown in FIGS. 1, 7, and 8, the four drain leads 3 extend from a wide chip fixing portion 3 c that exposes the upper surface of the upper surface of the sealing body 2. The chip fixing portion 3c and the drain lead 3 are referred to as a drain electrode plate 3a. For convenience of explanation, the chip fixing portion 3c may be simply referred to as a drain electrode plate 3a. The drain electrode plate 3a also serves as a heat sink that dissipates heat. As shown in FIG. 8, the second main surface side of the semiconductor chip 9 is connected to the lower surface of the drain electrode plate 3 a via an adhesive 7. Although not shown in FIG. 8 or the like, a back surface electrode (drain electrode) 10 having the same size as the second main surface of the semiconductor chip is formed on the second main surface of the semiconductor chip 9 (see FIG. 12). ). In order to electrically connect the back electrode (drain electrode) 10 and the drain electrode plate 3a, a conductive adhesive such as an Ag paste is used as the adhesive 7.

  Moreover, as shown in FIG. 1, the mark 11 by the unevenness | corrugation is formed in the upper surface (exposed surface) of the drain electrode plate 3a (refer FIG. 29). This mark 11 is formed by engraving the surface of the drain electrode plate 3a by laser beam irradiation.

  As shown in FIGS. 6 to 8, the gate lead 4 is connected to the gate electrode plate 4 a in the sealing body 2, and the source lead 5 is connected to the wide source electrode plate 5 a in the sealing body 2. The pattern of the gate electrode plate 4a and the source electrode plate 5a is indicated by a one-dot chain line in FIG. 6 (see FIG. 14). As shown in FIGS. 7 and 8, the gate protrusion electrode 15 and the source protrusion electrode 16 are provided on the first main surface of the semiconductor chip 9, respectively. The gate protruding electrode 15 of the semiconductor chip 9 is electrically connected to the upper surface of the gate electrode plate 4a, and the source protruding electrode 16 of the semiconductor chip 9 is electrically connected to the upper surface of the source electrode plate 5a. As shown in FIG. 6, the source electrode plate 5a is provided with slits 5e at predetermined intervals, and is connected to the source protrusion electrode 16 in a wide region between the slits 5e. The gate electrode plate 4a has a thin pattern.

  Here, the structure of the semiconductor chip 9 will be briefly described with reference to FIG. FIG. 12 is an enlarged sectional view showing a part of the semiconductor chip 9 and showing a part of the vertical power MOSFET.

The semiconductor chip 9 is formed based on an n ⁺ type silicon semiconductor substrate 20 having an n ⁻ type epitaxial layer 21 on the main surface. In the vertical MOSFET, a large number of cells (transistors) are aligned in a plan view. In this example, each transistor cell has a trench configuration. A P ⁻ type channel (CH) layer 22 is formed in a predetermined region of the epitaxial layer 21, and a P ⁻ type well layer 23 serving as a guard ring is formed on the outer periphery thereof. A large number of trenches (grooves) 25 are formed in the cell formation region so as to penetrate the channel layer 22. The trench 25 is also provided in the well layer 23. A region between the trench provided in the well layer 23 and the trench constituting the cell located on the innermost outer periphery thereof is an invalid region that is not used as a cell.

A polysilicon gate layer 26 serving as a gate electrode is provided in the trench 25, and a gate insulating film 27 is provided below this layer. A P ⁺ region 28 is formed in the central surface layer portion of the channel layer 22 surrounded by the trench. In the channel layer 22 in the cell portion, an N ⁺ type source region 29 is provided from the outside of the P ⁺ region 28 to the region reaching the trench. The trench portion, that is, the gate insulating film 27 and the polysilicon gate layer 26 are covered with an insulating film 32 that is selectively provided, and a source electrode 33 is formed on the insulating film 32. The source electrode 33 is electrically connected to the P ⁺ region 28 and the source region 29 at an opening where the insulating film 32 is not provided.

  A thick insulating film (LOCOS) 34 is provided continuously to the gate insulating film 27 in the trench 25 portion located outside the invalid region. Although not shown, the thick insulating film 34 extends beyond the outer periphery of the well layer 23. The polysilicon gate layer 26 embedded in the trench 25 located outside the ineffective region extends to a middle portion on the thick insulating film 34 to form a peripheral gate wiring 35. The peripheral gate wiring 35 and the thick insulating film 34 are also covered with the insulating film 32. A gate electrode 36 is provided from the insulating film 32 to the thick insulating film 34. The gate electrode 36 is electrically connected to the polysilicon gate layer 26 through an opening partially provided in the insulating film 32. Both the source electrode 33 and the gate electrode 36 are formed of an aluminum film.

  An insulating film 37 is selectively provided on the first main surface of the semiconductor chip 16. The source electrode 33 and the gate electrode 36 are selectively covered with an insulating film 37. Then, the source protruding electrode 16 and the gate protruding electrode 15 as protruding electrodes are formed on the source electrode 33 and the gate electrode 36 in the openings where the insulating film 37 is not provided. On the second main surface of the semiconductor chip 9, a back surface electrode 10 serving as a drain electrode is formed over the entire surface.

  In this embodiment, the gate protruding electrode 15 and the source protruding electrode 16 are formed by tearing after wire bonding of a gold wire, but may be formed by a gold bump electrode, a solder bump electrode, or the like.

  Stud type protruding electrodes (stud bumps) such as the gate protruding electrode 15 and the source protruding electrode 16 are formed by the following method. For example, a wire (gold wire) is held by a cylindrical capillary, and the tip of the wire protruding from the lower end of the capillary is formed into a sphere (ball) by a spheroidizing process such as discharge. Thereafter, the capillary is lowered to the protruding electrode forming surface of the semiconductor wafer to connect the wire to the electrode while crushing the ball portion. The capillary is then raised and the wire is clamped and pulled upward. As a result, the wire breaks and a nail head-shaped protruding electrode (bump electrode) is formed. Thereafter, the semiconductor wafer is divided vertically and horizontally to form semiconductor chips.

  Although the gate electrode plate 4a and the gate protrusion electrode 15 are directly connected, if necessary, a conductive adhesive may be interposed therebetween to ensure the connection. Similarly, a conductive adhesive may be interposed between the source electrode plate 5a and the source protruding electrode 16 to ensure the connection.

  Here, an example of the dimensions of the semiconductor device 1 of the first embodiment will be given. As shown in FIG. 1 and FIG. 3, the size of the sealing body 2 is 3.95 mm in length a and 4.9 mm in width b. As shown in FIG. 5, the length c of the drain lead 3 protruding from the side surface of the sealing body 2 is 1.2 mm, the length d of the surface mounting terminal is 0.5 mm, and the thickness e of the drain lead 3 is 0. .25 mm. The length f from the tip of the lead to the tip is 6.1 mm. As shown in FIG. 3, the height g of the semiconductor device is 1.1 mm, and the length h from the lower surface of the sealing body 2 to the lower end of the lead protruding downward is 0.07 mm. Note that the thicknesses of the gate lead and the source lead are 0.2 mm.

  In the first embodiment, the gate, source, and drain leads are formed in a gull wing type that can be surface-mounted. In the semiconductor device 1, since the on-resistance is regarded as important, the drain electrode plate is formed thicker than the gate / source electrode plate in order to reduce the electric resistance. For this reason, the molding load at the time of forming the drain electrode plate is larger than the molding load at the time of forming the gate / source electrode plate. There is a possibility that a stress such as pulling out may occur, and a connection portion between the semiconductor chip and the drain electrode plate may be damaged, or a connection portion between the semiconductor chip and the gate electrode plate and the source electrode plate may be damaged.

  Therefore, in the semiconductor device 1 of the first embodiment, in the lead frame to be used, a plurality of slits are provided in the drain electrode plate portion to be formed into a gull wing type to form a plurality of branch pieces (drain leads). Mold the branch piece. Thereby, the molding load is reduced to prevent damage (crack generation, crack generation) of the adhesive 7 connecting the drain electrode plate 3a and the semiconductor chip 9.

  Further, since the molding is performed after the sealing body 2 is formed, the drain electrode plate 3a is devised to increase the adhesion strength between the drain electrode plate 3a and the resin forming the sealing body 2. By preventing the drain electrode plate 3a from coming off from the resin forming the sealing body 2, a large force is not applied to the connection portion connecting the drain electrode plate 3a and the semiconductor chip 9.

  9 to 11 are views showing the drain electrode plate 3 a including the drain lead 3 removed from the sealing body 2. As shown in FIG. 9, four drain leads 3 protrude in parallel from one side of the rectangular chip fixing portion 3c of the drain electrode plate 3a. On the periphery of the three sides of the chip fixing portion 3c where the drain lead 3 of the drain electrode plate 3a is not disposed, as shown in FIGS. 9 to 11, a recess 3d is formed in which the periphery of the electrode plate is opened by etching. . The recess 3d is formed by etching, and is etched to about half the thickness of the drain electrode plate 3a (see FIG. 11). As shown in FIGS. 7 and 8, the recess 3 d is covered with a resin that forms the sealing body 2. Thereby, the adhesion strength (adhesion strength) between the drain electrode plate 3a and the sealing body 2 is increased.

  Further, by extrusion molding with a press machine, at least a part of the branch start portion of the branch end piece (drain lead 3) and an electrode plate edge (chip tip 3c of the chip fixing portion 3c) extending between adjacent branch pieces (drain lead 3). The edge 3 is provided with a recess 3e that is open on the peripheral side of the electrode plate. Since the extrusion molding process is performed by a press machine, the opposite surface portion of the drain electrode plate corresponding to the recess 3e protrudes to form a protrusion 3f. As shown in FIGS. 7 and 8, the recess 3e is filled with a resin for forming the sealing body 2, and the adhesion strength (adhesion strength) between the drain electrode plate 3a and the sealing body 2 is increased. Further, as shown in FIGS. 7 and 8, the protrusion 3f bites into the resin forming the sealing body 2, and the adhesion strength (adhesion strength) between the drain electrode plate 3a and the sealing body 2 is increased.

  Thereby, when the drain electrode plate is formed, a large load that pulls out the drain electrode plate 3a from the sealing body 2 is not applied, and the connection portion between the drain electrode plate 3a and the semiconductor chip 9 is damaged, or the semiconductor chip 9 and the gate. It is possible to prevent damage to the connection portion between the electrode plate 4a and the source electrode plate 5a.

  Next, a method for manufacturing the semiconductor device according to the first embodiment will be described with reference to FIGS. As shown in the flowchart of FIG. 13, the semiconductor device 1 includes lead frame preparation (S101), chip bonding (S102), heat sink connection (S103), sealing body formation (S104), mark formation (S105), lead frame It is manufactured through each step of cutting and molding (S106).

  In manufacturing the semiconductor device 1, a first lead frame 40 as shown in FIG. 14 and a second lead frame 50 as shown in FIG. 15 are prepared. 14 and 15 are plan views showing a part of the lead frame. 14 and 15, frame bodies 43 and 53 are constituted by two outer frames 41 and 51 extending in parallel and two inner frames 42 and 52 connecting the pair of outer frames 41 and 51. Is formed. A total of four lead patterns in two rows and two columns are formed in the frame bodies 43 and 53, and four semiconductor devices 1 can be manufactured by one frame body 43 and 53. The outer frames 41 and 51 are provided with guide holes 44 and 54 used when the lead frame is transported or positioned.

  In the first lead frame 40, two thin dam pieces 45 are disposed between the pair of outer frames 41. A plurality of lead portions (branch pieces) 46 extend in parallel from the pair of inner frames 42, and extend so as to intersect with the dam pieces 45. Here, four slits 46 are arranged by providing three slits parallel to the flat plate. A wide electrode plate 47 is positioned on the extension of the lead portion 46, and the lead portion 46 is connected to the electrode plate 47. One lead portion 46 at the end is a portion for forming the gate lead 4, and the electrode plate 47 connected to the lead portion 46 is a portion for forming the gate electrode plate 4 a. The electrode plate 47 to be the gate electrode plate 4a is provided with a slit 4p extending from one edge to the middle to make it difficult for the gate electrode plate 4a to come off from the sealing body, and a protrusion is formed adjacent to the slit. Yes. The gate protrusion electrode 15 of the semiconductor chip 9 is connected to the electrode plate 47 which becomes the gate electrode plate 4a.

  Further, the three adjacent lead portions 46 are portions serving as source leads, and the electrode plate 47 connected to the three lead portions 46 is a portion serving as the source electrode plate 5a. The electrode plate 47 to be the source electrode plate 5a is supported by a thin support piece 47a extending from the outer frame 41, and a thin support piece extending from the distal end portion of the support lead portion 48 outside the four lead portions 46. 47b. In addition, the electrode plate 47 serving as the source electrode plate 5a is provided with the four slits 5e described above. A portion removed from these four slits 5e is a portion to which the source protruding electrode 16 of the semiconductor chip 9 is connected. The first lead frame 40 is a flat plate.

  The first embodiment is a semiconductor device on which a semiconductor chip incorporating a transistor is mounted. A gate electrode and a source electrode are located on the first main surface of the semiconductor chip. In the first lead frame 40, an electrode plate connected to the gate electrode and the source electrode located on one surface needs to be disposed. Therefore, the first lead frame 40 has a plurality of (two) first electrode plates, one electrode plate is used as the gate electrode plate 4a, and the other electrode plate is used as the source electrode plate 5a. To do. When the semiconductor device is an integrated circuit device or the like, more electrodes are arranged on the first main surface of the semiconductor chip. In this case, a lead pattern that increases the number of first electrode plates in accordance with the number of electrodes may be used. For convenience of explanation, an electrode plate and a lead extending from the electrode plate may be referred to as an electrode plate.

  As shown in FIG. 15, the second lead frame 50 is provided with a support piece 55 that connects between the centers of the pair of outer frames 51. Then, four lead portions (branching pieces) 56 extend from both the upper and lower sides of the support piece 55 in the drawing. That is, four lead portions (branching pieces) 56 are formed by forming three slits in parallel on the flat plate. The lead portion 56 is a portion that becomes the drain lead 3. These lead portions 56 are connected to a rectangular electrode plate 57. This electrode plate 57 becomes the chip fixing portion 3c. The second lead frame 50 is a flat plate.

  FIG. 16 shows a support piece 55, a lead portion 56 (a portion that becomes the drain lead 3) and an electrode plate 57 (a portion that becomes the chip fixing portion 3 c) connected to the support piece 55. FIGS. 17 to 19 show a single electrode plate 57 and a lead portion 56 connected to the electrode plate 57. Four drain leads 3 (lead portions 56) protrude in parallel from one side of the rectangular chip fixing portion 3c (electrode plate 57). As shown in FIG. 17 to FIG. 19, a recess 3 d is formed on the periphery of the three sides of the electrode plate 57 where the lead portion 56 is not disposed. The recess 3d is formed by etching, and is etched to, for example, about half the thickness of the electrode plate 57 (see FIG. 19).

  Further, by extrusion molding using a press machine, at least a part of the branch start portion of the lead portion 56 that is a branch piece and the electrode plate 57 (chip fixing portion 3c) extending between the adjacent branch pieces (lead portion 56). At the edge, a recess 3e is provided with an opening on the periphery of the electrode plate. Since it is an extrusion molding process by a press machine, the opposite surface portion of the electrode plate 57 corresponding to the recess 3e protrudes to form a protrusion 3f. For convenience of explanation, an electrode plate (chip fixing portion) and a lead extending from the electrode plate may be referred to as an electrode plate.

  For example, the first lead frame 40 and the second lead frame 50 are formed by patterning a copper alloy plate having a thickness of 2 mm and a thickness of 2.5 mm by etching or punching by a precision press.

  After the first lead frame 40 and the second lead frame 50 are prepared, the first main frame of the semiconductor chip 9 is formed on each lead pattern portion on the upper surface of the first lead frame 40 as shown in FIG. Chip bonding is performed so that the surface becomes the lower surface (S102). The gate protruding electrode 15 shown in FIG. 12 is connected to the electrode plate 47 (gate electrode plate 4a) shown in FIG. 14, and the source protruding electrode 16 is connected to the electrode plate 47 (source electrode plate 5a) shown in FIG. If necessary, a conductive adhesive is interposed at each connection portion between the semiconductor chip 9 and the electrode plate 47.

  Next, as shown in FIG. 21, the support piece 55 is cut from the second lead frame 50, and the four electrode plates 57 serving as heat sinks are bonded to each semiconductor chip 9 on the first lead frame 40. Are overlapped and connected (S103).

  Next, as shown in FIG. 22, the sealing body 2 made of an insulating resin is formed by a transfer molding apparatus (not shown) (S104). The upper surface of the electrode plate 57 is exposed on the upper surface of the sealing body 2. The semiconductor chip 9 and the electrode plate 47 connected to the gate protruding electrode 15 and the source protruding electrode 16 of the semiconductor chip 9 are buried in the sealing body 2. The lead part 56 protrudes from one side of the sealing body 2, and the lead part 46 protrudes from the other side (see FIG. 23). By this resin sealing, the resin forming the sealing body 2 is filled in the recesses 3d and 3e, and the projecting portion 3f bites into the resin (see FIGS. 7 and 8). Thereby, the adhesive strength (adhesion strength) between the lead portion 56 and the electrode plate 57 and the sealing body 2 is increased.

  Next, as shown in FIG. 23, after the first lead frame 40 having the sealing body 2 in part is placed on the stage 60 of the laser mark device, a mask 61 is disposed on the upper surface of the electrode plate 57. Then, a laser beam 63 is emitted from the laser oscillator 62, and a mark (see FIG. 1) represented by unevenness is formed on the surface of the electrode plate 57 (chip fixing portion 3c: drain electrode plate 3a) (S105).

  Next, although not shown in the drawing, the unnecessary lead frame portions of the first lead frame 40 and the second lead frame 50 are cut and removed by using a cutting / molding machine and protruded from the sealing body 2. The lead part 56 and the lead part 46 to be formed are formed into a gull wing type, and a plurality of semiconductor devices 1 shown in FIG. 2 are manufactured (S106).

  Since the semiconductor device 1 according to the first embodiment has a structure in which the drain electrode plate 3a (chip fixing portion 3c) serving as a heat sink is exposed on the upper surface of the sealing body 2, heat can be dissipated from the exposed surface. Therefore, it is possible to dissipate heat by fixing the radiator to the upper surface of the drain electrode plate 3a via the adhesive.

  24 to 29 show a state in which a plurality of semiconductor devices 1 according to the first embodiment are arranged and mounted on the mounting substrate 70 and a common heat dissipating body 71 is attached to each semiconductor device 1. FIG. 24 is a schematic cross-sectional view showing a mounted state, and FIG. 25 is a schematic plan view. FIG. 26 is an enlarged sectional view showing a mounted state.

  The mounting structure shown in FIG. 24 constitutes a part of the circuit shown in FIG. 30, for example. FIG. 30 is a step-down circuit diagram in an electronic device, in which a 12V power source 90 is (1) stepped down by each DC / DC converter 91 and supplied to each CPU (central control circuit) 92 as a 1.0V power source. (2) A circuit that steps down by the DC / DC converter 93 and feeds power to the DDR (memory) 94 as a 1.5V power supply, and (3) A circuit that steps down by the DC / DC converter 95 and feeds power to the ASIC 96 as a 2.5V power supply. A circuit and a circuit for directly supplying power to the HDD 97 with a 12V power supply.

  The mounting structure in FIG. 24 forms a DC / DC converter 91. In the manufacture of the DC / DC converter 91, as shown in FIG. 27, first, a plurality of semiconductor devices 1 are aligned and mounted on the mounting substrate.

  As shown in FIG. 27, the upper surface of the mounting substrate 70 is not particularly limited, but 20 semiconductor devices 1 are mounted in two columns and 10 rows in total. As shown in FIG. 26, the mounting state of the semiconductor device 1 is such that the leading end portion of each lead (showing the drain lead 3 and the source lead 5 in the figure) protruding in a gull-wing shape from both sides of the sealing body 2 of the semiconductor device 1 is It is electrically connected to a land 72 on the upper surface of the mounting substrate 70 by a bonding material 73 such as solder. FIG. 29 is a schematic cross-sectional view in which the mounting state of the semiconductor device 1 is further enlarged. As can be seen from this figure, the upper surface of the drain electrode plate 3 a (chip fixing portion 3 c) is exposed on the upper surface of the sealing body 2. Further, a concave portion 11a and a mark 11 represented by a convex portion 11b are formed on the upper surface of the exposed drain electrode plate 3a.

  Next, as shown in FIG. 28, the insulating resin insulating sheet 74 is placed on the semiconductor device group so as to cover all the semiconductor devices 1. Thereafter, the radiator 71 is overlaid on the insulating sheet 74. Screw holes are provided at both end portions of the heat radiating body 71, and female screw holes 75 are provided in the mounting board 70 corresponding to the screw holes, so that the screws 76 are passed through the screw holes and the screws 76 are screwed. The mounting structure as shown in FIGS. 24 and 25 is manufactured by tightening.

  In this mounting structure, heat generated in each semiconductor device 1 is transmitted from the drain electrode plate 3a of each semiconductor device 1 to the heat radiating body 71 via the insulating sheet 74, and protrudes in a columnar shape on the upper surface of the heat radiating body 71. It is dissipated into the atmosphere from the surface of the heat radiating core 71a.

  In this mounting structure, by screwing the screws 76, the insulating sheet 74 made of resin is crushed as shown in FIG. Since the mark 11 has the concave portion 11a and the convex portion 11b, the heat radiation area of the drain electrode plate 3a is widened. As a result, since the heat generated in each semiconductor device 1 is more effectively transmitted to the heat radiating body 71, the heat radiation effect of the mounting structure can be improved. For example, when a mark is formed on the surface of a metal plate with ink, since the ink is a resin, the heat dissipation effect (heat transfer effect) may be reduced.

The first embodiment has the following effects.
(1) The semiconductor device (power MOSFET device) 1 has a drain electrode plate 3 a whose upper surface is exposed on the upper surface of the sealing body 2. A semiconductor chip 9 is connected to the drain electrode plate 3 a via a back electrode (drain electrode) 10 of the semiconductor chip 9. The back electrode 10 has substantially the same size as the semiconductor chip 9. As a result, the heat generated in the semiconductor chip 9 can be efficiently transferred to the drain electrode plate 3a. Therefore, by attaching the heat dissipating body 71 to the drain electrode plate 3a, heat can be efficiently dissipated to the outside, and the semiconductor device 1 and the semiconductor device mounting structure (that is, the electronic device) with good heat dissipation are provided. be able to. Moreover, the semiconductor device 1 of the first embodiment can also dissipate heat from the surface of the wide drain electrode plate 3a to the atmosphere even when no heat radiator is attached.

  Since the semiconductor device 1 has a structure in which heat is radiated from the upper surface side of the sealing body 2, it is not necessary to consider heat radiation to the mounting board as in the past, and a special cost-effective special heat transfer is provided. Does not require a specified mounting board. As a result, the mounting cost can be reduced.

(2) When manufacturing the semiconductor device 1 using the lead frame, the drain electrode plate portion protruding to the outside from the sealing body 2 is formed into a gull wing shape suitable for surface mounting. Since this molding portion is provided with slits to form a plurality of branch pieces (lead portions) 56, compared to molding a single plate, that is, a large molding load is not required. As a result, there is an effect that molding can be performed with high accuracy without causing damage to the connecting portion (adhesive 7, gate protruding electrode 15, and source protruding electrode 16) between the semiconductor chip 9 and the lead. That is, since the drain electrode plate 3a is thicker than the source electrode plate 5a and the gate electrode plate 4a in order to reduce electric resistance, if the drain electrode plate 3a is formed into a gull wing shape, a larger load is applied. It becomes bending molding by. As a result, a large stress acts on the drain electrode plate 3a connected to the sealing body 2 in a direction in which the drain electrode plate 3a is pulled out from the sealing body 2, thereby causing damage to a connection portion with the semiconductor chip. Damage to the connection portion is not preferable because it increases the resistance R _{ds (ON)} between the source and the drain. In the present invention, since a plurality of slits are provided in the drain electrode plate 3a formed into a gull wing shape to form a plurality of branch pieces (leads) 56, it is not necessary to apply a large load during molding. As a result, a large stress is not applied to the drain electrode plate 3a at the time of molding, and damage to the connection parts on the front and back of the semiconductor chip 9 can be prevented. This also applies to the source electrode plate 5a. By providing a plurality of slits in the source electrode plate 5a to form a plurality of branch pieces (lead portions) 46, damage to the connection portion with the semiconductor chip 9 occurs. Can be molded without any problems.

  (3) Drains 3d and 3e are partially formed on the upper surface of the drain electrode plate 3a located in the sealing body 2, and a resin that forms the sealing body is filled in the hollow portions, so that the drain is formed in a product state. It becomes difficult for the electrode plate 3a to drop off from the sealing body 2. Further, in the manufacturing stage of the semiconductor device 1, the upper surface of the drain electrode plate 3a located in the sealing body 2 is partially lowered to form the recesses 3d and 3e, or the back surface corresponding to the recess 3e is projected. Thus, the protruding portion 3f is formed. As a result, at the stage of forming the sealing body 2, the resin forming the sealing body 2 enters the recesses 3 d and 3 e, and the protrusion 3 f bites into the resin forming the sealing body 2. Accordingly, the drain electrode plate 3 a is fixed (locked) to the sealing body (resin) 2. For this reason, when the drain electrode plate 3a is formed, the drain electrode plate 3a does not move with respect to the sealing body 2, and the connection portion of the semiconductor chip 9 can be formed without damage.

  In the formation of the drain electrode plate 3 a, a tensile stress acts on the drain electrode plate 3 a in the extending direction of the surface mounting terminal (drain lead 3: branch piece), and the drain electrode plate extends into the sealing body 2. In 3a, a stress acts in the pulling direction. Accordingly, the recesses 3d, the recesses 3e, and the protruding portions 3f extending in the direction intersecting with the drawing direction work to reduce the stress acting in the drawing direction. In particular, the action of the engaging portion of the recess 3d, the recess 3e, and the protrusion 3f extending in the direction orthogonal to the drawing direction reduces the stress acting in the drawing direction. Therefore, it is also effective to form the protrusion 3f on the lower surface of the drain electrode plate 3a so as not to hinder the flow of the resin for forming the sealing body 2. For example, one side portion of the tip of the drain electrode plate 3a extending into the sealing body 2 is extruded from the top surface in the state of a lead frame to form a recess 3d on the top surface of the tip of the drain electrode plate 3a. It is also effective to form a protrusion on the lower surface of the drain electrode plate 3a on the back side of the recess 3d. Further, unevenness is provided on the periphery of the drain electrode plate 3a extending inside the sealing body 2, and the engagement between the uneven portion and the resin causes damage to the connection portion with the semiconductor chip when the drain electrode plate 3a is formed. You may make it prevent.

  (4) In the semiconductor device 1 of the first embodiment, the mark 11 is formed on the surface of the drain electrode plate 3a that is a metal plate exposed on the upper surface of the sealing body 2 by the laser mark device. The mark 11 forms a recess 11a on the metal plate surface by laser light irradiation, and the mark 11 is formed by the recess 11a and the protrusion 11b. Therefore, it is possible to easily form the mark 11 with no risk of dropping, and the mark formation cost can be reduced.

  (5) The semiconductor device 1 according to the first embodiment uses the drain electrode plate 3a exposed on the upper surface of the sealing body 2 as a heat transfer medium, and the heat generated in the semiconductor chip 9 is directly dissipated or overlapped in the atmosphere. It is structured to transmit to the body 71. In the semiconductor device 1 of the first embodiment, the mark 11 is formed by the concave portion 11a and the convex portion 11b on the exposed surface of the drain electrode plate 3a as a heat transfer medium by forming the concave portion 11a by laser light irradiation. For this reason, the surface area of the drain electrode plate 3 a serving as a heat radiating surface is increased, and the heat generated in the semiconductor chip 9 can be radiated directly into the atmosphere or transferred to the heat radiating body 71. As a result, it is possible to provide a semiconductor device mounting structure with good heat dissipation, that is, an electronic device.

  Although the invention made by the present inventor has been specifically described based on the embodiment, the present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the invention. Nor. In the embodiment, an example in which a power MOSFET is incorporated in a semiconductor chip has been shown. However, as an element to be incorporated, a transistor such as a MOSFET, a power bipolar transistor, or an IGBT, or an IC including a transistor may be used.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device (power MOSFET device), 2 ... Sealing body (package), 3 ... Drain lead, 3a ... Drain electrode plate, 3c ... Chip fixing part, 3d, 3e ... Depression, 3f ... Projection part, 4 ... Gate Lead, 4a ... Gate electrode plate, 5 ... Source lead, 5a ... Source electrode plate, 5e ... Slit, 6 ... Index, 7 ... Adhesive, 9 ... Semiconductor chip, 10 ... Back electrode (drain electrode), 11 ... Mark, DESCRIPTION OF SYMBOLS 15 ... Gate protrusion electrode, 16 ... Source protrusion electrode, 20 ... Silicon semiconductor substrate, 21 ... Epitaxial layer, 22 ... Channel (CH) layer, 23 ... Well layer, 25 ... Trench (groove), 26 ... Polysilicon gate layer, 27 ... Gate insulating film, 28 ... P ⁺ region, 29 ... Source region, 32 ... Insulating film, 33 ... Source electrode, 34 ... Thick insulating film (LOCOS), 35 ... Peripheral gate 36 ... Gate electrode 37 ... Insulating film 40 ... First lead frame 41 ... Outer frame 42 ... Inner frame 43 ... Frame body 44 ... Guide hole 45 ... Dam piece 46 ... Lead part , 47 ... Electrode plate, 50 ... Second lead frame, 51 ... Outer frame, 52 ... Inner frame, 53 ... Frame body, 54 ... Guide hole, 55 ... Supporting piece, 56 ... Lead part, 57 ... Electrode plate, 60 ... Stage, 61 ... Mask, 62 ... Laser oscillator, 63 ... Laser light, 70 ... Mounting substrate, 71 ... Heat radiator, 71a ... Heat radiating core, 72 ... Land, 73 ... Joint material, 74 ... Insulating sheet, 75 ... Female screw Hole, 76 ... screw.

Claims (13)

(A) preparing a lead frame comprising a plurality of first leads and a first electrode plate formed in series with each of the plurality of first leads;
(B) A semiconductor chip is prepared which includes a first main surface on which a plurality of protruding electrodes are formed and a second main surface on the opposite side of the first main surface and on which a back electrode is formed. Process,
(C) electrically connecting the plurality of protruding electrodes of the semiconductor chip to the first electrode plate of the lead frame;
(D) preparing a second electrode plate including a plurality of second leads and a chip fixing portion formed continuously with the plurality of second leads and having a depression formed around the upper surface;
(E) electrically connecting the lower surface of the chip fixing portion of the second electrode plate and the second main surface of the semiconductor chip;
(F) sealing the semiconductor chip with a sealing resin, and forming a sealing body so that a part of the chip fixing part and a part of the plurality of lead parts of the second electrode plate are exposed. When,
(G) After the step (f), a step of separating the plurality of first leads from the lead frame;
(H) After the step (g), forming the second leads of the second electrode plate,
In the step (f), (ii) the plurality of the second electrode plates are exposed so that a part of the upper surface of the chip fixing portion of the second electrode plate is exposed from the upper surface of the sealing body. (Iii) the second lead so that an upper surface of each of the second leads is exposed from the upper surface of the sealing body and each of the plurality of second leads protrudes from the first side surface of the sealing body. Forming the sealing body so that the depression of the chip fixing portion of the electrode plate is covered with the sealing body;
A method of manufacturing a semiconductor device , wherein a width of each of the plurality of second leads is narrower than a width of the chip fixing portion in a direction orthogonal to a direction in which the plurality of second leads protrude from the sealing body . The method for manufacturing a semiconductor device according to claim 1, wherein a thickness of the second electrode plate is larger than a thickness of the first electrode plate . The recess is formed at a portion where each of the plurality of second leads starts to branch from the chip fixing portion and an edge of the chip fixing portion extending between each of the plurality of leads. 2. A method for manufacturing a semiconductor device according to 1. 4. The method of manufacturing a semiconductor device according to claim 3 , wherein a protrusion is formed on the lower surface of the chip fixing portion corresponding to the recess , and the protrusion is sealed by the sealing body . 5. 2. The method of manufacturing a semiconductor device according to claim 1 , wherein the step (f) is performed such that each of the plurality of first leads protrudes from a second side surface facing the first side surface of the sealing body . Wherein step (f), a method of manufacturing a semiconductor device according to claim 1, wherein the first electrode plate is carried out so as to be disposed sealing body. The method for manufacturing a semiconductor device according to claim 1, wherein the upper surface of the chip fixing portion is a surface on which a heat radiating body can be mounted . 2. The method of manufacturing a semiconductor device according to claim 1, further comprising a step of forming a mark by irradiating the upper surface of the chip fixing portion with a laser beam after the step (f) and before the step (g). 3. . The semiconductor chip contains a vertical power MOSFET,
A source electrode and a gate electrode are formed on the first main surface of the semiconductor chip, and a drain electrode is formed on the second main surface,
The plurality of first leads include a source lead electrically connected to the source electrode of the semiconductor chip and a part of the plurality of protruding electrodes, and the gate electrode of the semiconductor chip. A gate lead electrically connected through some of the plurality of protruding electrodes, and
The method of manufacturing a semiconductor device according to claim 1, wherein the plurality of second leads are drain leads electrically connected to the drain electrode of the semiconductor chip. The method of manufacturing a semiconductor device according to claim 1, wherein in the step (h), the plurality of second leads are formed to have a gull wing shape. 2. The step (e) of claim 1, wherein the lower surface of the chip fixing portion of the second electrode plate and the second main surface of the semiconductor chip are electrically connected via a conductive adhesive. A method for manufacturing a semiconductor device. The method of manufacturing a semiconductor device according to claim 1, wherein each of the plurality of protruding electrodes of the semiconductor chip is a gold stud type protruding electrode. 2. The method of manufacturing a semiconductor device according to claim 1, wherein a slit is formed in a region other than a region to which the plurality of protruding electrodes of the semiconductor chip of the first electrode plate are connected.

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