JP2010258286A - Semiconductor device and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: since a conventional semiconductor device uses a gold wire as a metallic thin wire, it is difficult to lower the material cost. <P>SOLUTION: The semiconductor device has a semiconductor element 9 fixed on an island 7 and also has a plurality of through holes 12 formed in the island 7 at a periphery of the fixation region of the semiconductor element 9. Then an electrode pad and a lead 6 of the semiconductor element 9 are electrically connected by a Cu wire 11. With this structure, using the Cu wire 11 lowers the material cost as compared with use of an Au wire. Further, an Au ball 10 is formed on the electrode pad to suppress generation of a splash, and electrode pads are prevented from mutually short-circuiting. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor device wire-bonded using a copper wire and a method for manufacturing the same.

  As an example of a conventional method for manufacturing a semiconductor device, the following manufacturing method is known. 12A and 12B are cross-sectional views for explaining a conventional method for manufacturing a semiconductor device.

  First, as shown in FIG. 12A, after the semiconductor element 72 is fixed on the die pad 71 of the lead frame, the lead frame is set in a wire bonding apparatus. The electrode pad 73 of the semiconductor element 72 is heated to about 200 ° C., and the capillary 74 moves onto the electrode pad 73. Then, the metal ball formed at the tip of the capillary 74 is connected to the electrode pad 73 by a thermocompression bonding technique using ultrasonic vibration. This is generally called ball bonding.

  Next, as shown in FIG. 12B, the capillary 74 moves to the upper end of the inner lead 75 and presses the metal thin wire 76 against the inner lead 75 with a desired load. At this time, the inner lead 75 is heated to about 200 ° C., and the fine metal wire 76 is connected to the inner lead 75 by a thermocompression bonding technique using ultrasonic vibration. Thereafter, the capillary 74 is raised with the wire clamper 77 closed, and the metal thin wire 76 is broken at the connection portion of the inner lead 75. This is generally called stitch bonding.

  Then, by repeating the wire bonding operation described with reference to FIGS. 12A and 12B, all the electrode pads 73 of the semiconductor element 72 and the inner leads 75 are electrically connected by the thin metal wires 76 (for example, , See Patent Document 1).

  As another example of the conventional method for manufacturing a semiconductor device, the following manufacturing method is known. 13A to 13C are cross-sectional views for explaining a conventional method for manufacturing a semiconductor device.

  First, as shown in FIG. 13A, a semiconductor chip 82 is mounted on a wiring board 81. A plurality of electrode pads 83 are arranged on the upper surface of the semiconductor chip 82, and a metal ball 85 formed at the tip of the capillary 84 is connected to the electrode pad 83. Thereafter, the capillary 84 rises with the wire clamper 86 closed, and the fine metal wire 87 is cut from the metal ball 85.

  Next, as shown in FIG. 13B, the capillary 84 moves onto the metal ball 85 in a state where the thin metal wire 87 is led out from the tip of the capillary 84. After the stitch bonding is performed on the metal ball 85, the capillary 84 moves above the wiring layer 88 with the wire clamper 86 opened.

  Next, as shown in FIG. 13C, after stitch bonding is performed on the wiring layer 88, the capillary 84 is raised with the wire clamper 86 closed, and the metal thin wire 87 is connected to the connection portion of the wiring layer 88. (For example, refer to Patent Document 2).

Japanese Patent Laid-Open No. 7-29943 (page 4-5, FIG. 1) Japanese Patent Laying-Open No. 2005-86200 (page 6-7, FIG. 1-6)

  As described above, in the wire bonding process, the fine metal wires 76 are placed under a high temperature condition. At this time, Au wire is used as the fine metal wire, and the inner lead 75 is plated with silver, so that the oxidation problem was not particularly regarded as important.

  However, the use of Cu wires as the thin metal wires 76 has been studied for the purpose of increasing the capacity and reducing the cost of recent devices. In this case, the problem that the Cu wire is oxidized during the operation occurs. In particular, a high-performance semiconductor element has a large number of terminals and tends to be multi-pinned. For this reason, the number of wires to be wire-bonded is increased, and the working time is increased, so that countermeasures against Cu wire oxidation are regarded as important. In addition, the die pad 71, the inner lead 75, and the like are also oxidized by the above-described operation when the plating process or the like is not performed.

  Furthermore, since the Cu wire is harder than the Au wire, for example, when the Cu ball is directly bonded to the electrode pad made of Al, the electrode pad softer than the Cu wire is driven around the Cu ball. Splash occurs around the Cu ball. And the problem that an adjacent electrode pad short-circuits by the splash generate | occur | produces. In addition, there is a problem that damage such as cracks occurs in the insulating layer below the electrode pad due to the impact when the Cu ball is bonded to the ball.

  In particular, when the electrode pad itself is thinned to prevent a short circuit due to splash, damage is further applied to the insulating layer below the electrode pad.

  The above-mentioned splash has the following problems. That is, most of the electrode pads on the bottom surface of the Cu ball move as splash, the connection area between the Cu ball and the electrode pad is reduced, the connection resistance value is increased, or a connection failure occurs.

  On the other hand, considering the cost, the Au wire has a higher material cost than the Cu wire, and there is a problem of raising the cost cost. In addition, since the resistivity of the Au wire is larger than that of the Cu wire, the current capacity is smaller than that of the Au, and there is a problem that the amount of Au wire used increases in a semiconductor element that handles a large current, resulting in an extra material cost. .

  In the conventional technique, wire bonding is performed in a state where the plurality of inner leads 75 are fixed together by a clamper (not shown). However, since the Cu wire is harder than the Au wire, the load during wire bonding is larger than that of the Au wire. Therefore, if there is a gap between the clamper and the lead, the fixed state of the lead is poor, and the load at the time of wire bonding tends to escape due to the repulsion of the hardness, and a problem of poor connection occurs.

  In view of the circumstances described above, the semiconductor device according to the present invention has an island, a plurality of leads arranged around the island, a semiconductor element fixed on the island, and the semiconductor. In a semiconductor device comprising: a thin wire mainly composed of copper that electrically connects an electrode pad of an element and the lead; and a resin package that covers the island, the lead, the copper wire, and the semiconductor element. One end of the fine wire is connected to a metal ball softer than the copper formed on the pad, and the other end of the fine wire is connected to the lead. Therefore, in this invention, material cost is reduced by using a copper wire. By using the metal ball, it is possible to prevent a short circuit due to splash and a crack in the insulating layer below the pad electrode.

  Further, in the method for manufacturing a semiconductor device of the present invention, a lead frame provided with a mounting portion including an island, a plurality of leads arranged around the island, and a suspension lead extending from the island is prepared. Then, after fixing the semiconductor element on the island, electrically connecting the electrode pad of the semiconductor element and the lead with a thin wire mainly made of copper, and forming a resin package covering the mounting portion In the method of manufacturing a semiconductor device in which the lead is bent and the resin package is separated from the lead frame, the lead frame is fixed on a mounting table of a wire bonding apparatus, and from above the connection region of the thin wire, A gas flow is generated toward the connection region to prevent oxidation of the thin wire. Therefore, in this invention, the gas which prevents oxidation is easily filled around the copper wire by which wire bonding was carried out, and oxidation of a copper wire is prevented.

  In this invention, material cost is reduced compared with the case where Au wire is used by performing wire bonding using Cu wire.

  Further, in the present invention, by forming Au balls on the electrode pads, adjacent electrode pads can be prevented from being short-circuited by splash.

  In the present invention, the formation of a buffer material layer in the electrode pad can prevent the occurrence of cracks in the insulating layer on the lower surface of the electrode pad.

  In the present invention, the through hole of the island is buried by a part of the resin package, and the adhesion between the island and the resin package is improved.

  Moreover, in this invention, the inert gas supplied to the wire bonding area | region is attracted | sucked to the island side, An inert gas is filled in the circumference | surroundings of Cu wire, and the oxidation of Cu wire is prevented.

  In the present invention, the wire bonding operation is performed in a state where a plurality of leads are individually fixed by a clamper. And the escape of the load at the time of wire bonding is prevented, and a favorable connection state is realizable.

  Further, in the present invention, by filling the resin up to the through hole of the island and the back side of the suspension lead, it is possible to realize a structure in which the island does not easily come off from the resin package.

1A is a cross-sectional view for explaining a semiconductor device in an embodiment of the present invention, and FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a plan view for explaining a semiconductor device in an embodiment of the present invention, and FIG. 1A and 1B are a cross-sectional view and a cross-sectional view for explaining a semiconductor device in an embodiment of the present invention. 1A and 1B are a cross-sectional view and a cross-sectional view for explaining a semiconductor device in an embodiment of the present invention. 1A and 1B are a cross-sectional view and a cross-sectional view for explaining a semiconductor device in an embodiment of the present invention. 1A is a cross-sectional view for explaining a semiconductor device in an embodiment of the present invention, and FIG. It is (A) top view and (B) top view for demonstrating the manufacturing method of the semiconductor device in embodiment of this invention. It is (A) top view and (B) sectional drawing for demonstrating the manufacturing method of the semiconductor device in embodiment of this invention. 1A is a cross-sectional view for explaining a method of manufacturing a semiconductor device in an embodiment of the present invention, FIG. 2B is a cross-sectional view, and FIG. It is a top view for demonstrating the manufacturing method of the semiconductor device in embodiment of this invention. It is (A) sectional drawing and (B) perspective view for demonstrating the manufacturing method of the semiconductor device in embodiment of this invention. It is (A) sectional drawing for demonstrating the manufacturing method of the semiconductor device in conventional embodiment, (B) It is sectional drawing. It is (A) sectional drawing, (B) sectional drawing, (C) sectional drawing for demonstrating the manufacturing method of the semiconductor device in conventional embodiment.

  First, after explaining the points of the present invention, examples will be described.

  As described above, various measures have been taken to employ copper (hereinafter referred to as Cu) as the fine metal wire. In the embodiment described at the end, all the measures are taken, but at least one of them may be selected depending on a slight difference in conditions.

  (A): Antioxidation of Cu: Cu is easily oxidized, and therefore, it is necessary to fill an inert gas around the connection point. Therefore, the flow is made so that the inert gas flows positively at both ends of the Cu wire, the electrode pads on the semiconductor element side, and the connection points of the inner leads. As an example, a flow is created by sucking an inert gas through the through hole 12.

  (B): Shock absorption of hard Cu ball: The countermeasure on the semiconductor element side is shock absorption. In simple terms, it is a cushion. For example, if there is a glass under the cushion and the ball falls from above, the cushion will be thickened to protect the glass. However, although it is an electrode pad corresponding to a cushion, here, Al, the thicker it is, the more splashed splash 23 occurs as shown in FIG. Considering the slow motion, when a ball consisting of a rough sphere falls from above, it is first a point contact. In other words, as the points to be added concentrate on one point and then sink into the cushion, the volume sinking into the cushion gradually increases. In other words, the area to be excluded becomes larger. This is the biggest problem. In short, at the point contact, first, the destruction of the lower layer starts, and then the action of expelling Al constituting the electrode pad works.

  Therefore, on the electrode pad which is the first cushion, a second cushion which does not sink into the electrode pad but comes into surface contact with the first cushion over the entire back surface is required. Even if the ball falls from above, if the impact is applied to the first cushion on the entire back surface of the second cushion, the removal operation of the first cushion can be suppressed. Moreover, it is sufficient to perform an operation so that no force is applied to the cushions directly from above. In the embodiment, the second cushion is an Au ball, and the operation in which the force is not applied is a stitch bond.

  Embodiments of the present invention will be described below. FIG. 1A is a cross-sectional view of the resin package shown in FIG. FIG. 1B is a plan view from the back side of the resin package. FIG. 2A is a plan view of the lead frame. FIG. 2B is a plan view showing a state where wire bonding is performed on the lead frame shown in FIG. 3-5 is sectional drawing which shows the connection state in an electrode pad.

  As shown in FIG. 1A, the semiconductor device 1 is made of, for example, QFP (Quad Flat Package). The resin package 2 is generally a hexahedron composed of a front surface 3, a back surface 4 and four side surfaces 5. When viewed in cross section, the central portion of the side surface 5 slightly protrudes outward from the releasability of the resin-sealed mold. To do.

  The plurality of leads 6 are exposed from the four side surfaces 5 of the resin package 2 and bent. The mounting surface of the lead 6 is disposed on substantially the same surface as the back surface 4 of the resin package 2. The island 7 is exposed from the back surface 4 of the resin package 2, and the semiconductor element 9 is fixed onto the island 7 by an adhesive 8 such as Ag paste or solder. A plurality of electrode pads 18 (see FIG. 2B) are formed on the upper surface of the semiconductor element 9, and Au balls 10 are formed on the upper surface of the electrode pads 18. The Au ball 10 and the inner lead portion are connected by the Cu wire 11 which is the theme of the present application. As the Cu wire 11, for example, a wire made of Cu having a diameter of 33 to 50 μm and 99.9 to 99.99 wt% is used. As shown in the figure, the Cu wire 11 is ball-bonded on the inner lead and stitch-bonded on the Au ball 10. In addition, the design of the diameter of the Cu wire 11 can be arbitrarily changed according to the intended use.

  As shown in the drawing, the island 7 is larger than the size of the semiconductor element 9, and a plurality of through holes 12 are arranged around the fixed region of the semiconductor element 9. Although details will be described later, the through hole 12 is used as a flow path of an inert gas (forming gas) during die bonding or wire bonding. For example, nitrogen (N 2) gas is employed as the inert gas, and the connection reliability is improved in the wire bonding work of the Cu wire 11. That is, Cu wire 11 itself and the connection area | region of Cu wire 11 are arrange | positioned in the flow of an inert gas, and those oxidation is prevented.

  Further, as a secondary effect, the through hole 12 is embedded with an insulating resin at the time of resin molding, and the through hole 12 produces an anchor effect so that the island 7 is firmly supported in the resin package 2. . In the resin package 2, for example, a low molecular component contained in the resin package 2 or the adhesive 8 is vaporized by driving heat of the semiconductor element 9, and gas is generated. The island 7 receives an external force directed outward from the resin package 2 by this gas. In particular, the island 7 has a thin thickness of 100 to 250 μm, the adhesion between the island 7 and the resin package 2 is weak, and the island 7 is easily pushed out of the resin package 2 by the gas. However, by arranging the through holes 12 in the outer peripheral region of the island 7, the degree of adhesion between the resin package 2 and the island 7 is improved, and the island 7 is difficult to drop off from the resin package 2. And since the through-hole 12 becomes a flow path of an inert gas, the oxidation of the side surface of the through-hole 12 is prevented, and the adhesion degree between the island 7 and the resin package 2 is further improved.

  Further, the gas generated in the resin package 2 and the adhesive 8 in the vicinity of the island 7 is discharged to the outside of the resin package 2 through a short path by using the through hole 12 as a discharge path. And the said gas is efficiently discharged | emitted to the exterior of the resin package 2, and it becomes difficult to push the island 7 out of the resin package 2.

  As shown in FIG. 1B, for example, two through holes 12 are arranged along one side of the island 7. The length of the through hole 12 is about half the length of one side of the island 7. Although details will be described later with reference to FIG. 7B, even if the lead frame is slightly displaced when the lead frame is placed on the mounting table by increasing the opening area of the through hole 12, the lower part of the through hole 12 The gas vent hole 59 is easily disposed on the surface, and the suction force of the inert gas can be properly maintained.

  Further, as shown in the drawing, the suspension leads 13 extend from the four corners of the island 7 and are bent into the inside of the resin package 2. With this structure, most of the suspension leads 13 are arranged in the resin package 2 and an anchor effect is obtained. Further, the island 7 and a part of the suspension lead 13 are exposed from the back surface 4 of the resin package 2, so that heat generated from the semiconductor element 9 is quickly released out of the resin package 2.

  As shown in FIG. 2A, the lead frame 14 is made of, for example, a frame whose main material is Cu having a thickness of about 100 to 250 μm. However, the lead frame 14 may be made of Fe—Ni as a main material or other metal material. A plurality of mounting portions 15 indicated by alternate long and short dash lines are formed on the lead frame 14.

  The mounting portion 15 mainly includes an island 7, a suspension lead 13 that supports the island 7, a lead 6 having one end located near the four sides of the island 7, and a tie bar 16 that supports a plurality of leads 6. Consists of The suspension leads 13 extend from the four corners of the island 7 and are connected to the support region 17 where the tie bars 16 intersect. The support region 17 is integrated with the lead frame 14, and the island 7 is supported by the lead frame 14. A region indicated by a dotted line on the island 7 is a fixing region of the semiconductor element 9, and the through hole 12 which is a point of the present invention is disposed around the fixing region.

  As shown in FIG. 2B, the semiconductor element 9 is fixed on the island 7, and the Au ball 10 is formed on the upper surface of the electrode pad 18. The Cu wire 11 is ball bonded to the upper surface of the inner lead and then stitch bonded to the upper surface of the Au ball 10. And it is necessary to prevent the oxidation of the Cu wire 11 and the connection region of the Cu wire 11 or the like. As will be described later with reference to FIG. 7B, by adopting a structure in which the inert gas is extracted from the through hole 12, the inert gas flows from above to the bonding region, and the arrangement region of the Cu wire 11 is caused by the inert gas. It is easy to satisfy, and oxidation of Cu wire 11 etc. is prevented. As a result, the Cu wire 11 can be used instead of the Au wire, and the cost can be greatly reduced.

  Further, in a semiconductor element that handles a large current, a plurality of Au wires are used for one electrode pad to cope with a large current. However, in the case of a Cu wire, the specific resistance is small and the current capacity is large. It can handle a large current with a smaller number of wires than in the case of wires. As a result, the area of the bonding region can be made smaller than in the case of Au wire, and miniaturization of the semiconductor element is realized.

  In the present embodiment, the shape of the through hole 12 is not limited to the illustrated shape. The shape of the through hole 12 may be, for example, a circle, an ellipse, or a rectangle, and the through hole 12 has a width equal to or larger than the separation width between adjacent leads 6. good. With this structure, the suction force of the inert gas is increased and the effect of preventing the Cu wire 11 from being oxidized can be obtained.

  As shown in FIG. 3A, on the silicon substrate 19, for example, a silicon oxide film, a BPSG (Boron Phospho Silicate Glass) film, a TEOS (Tetra-Ethyl-Orso-Silicate) film, or an SOG (Spin On Glass) film is formed. Etc., at least one material is selected, and the insulating layer 20 is formed. And the electrode pad 18 is formed on the insulating layer 20, and the film thickness of the electrode pad 18 is 0.4-3.0 micrometers, for example. The electrode pad 18 is formed of, for example, an Al layer or an alloy layer mainly composed of Al. The alloy layer is, for example, an Al—Si film, an Al—Si—Cu film, an Al—Cu film, or the like. A shield layer 21 made of, for example, a silicon nitride film is formed on the insulating layer 20, and an opening 22 is formed in the shield layer 21 on the electrode pad 18.

  The Au ball 10 is ball-bonded on the electrode pad 18 exposed from the opening 22. Then, the Au ball 10 slightly bites into the electrode pad 18 due to the load during ball bonding, and a slight splash 23 may occur around the Au ball 10. However, the Au ball 10 is softer than the Cu ball, and the bonding load is smaller than that of the Cu ball. Therefore, the splash 23 is generated only between the inner side surface of the opening 22 and the Au ball 10 and does not occur beyond the region where the electrode pad 18 is formed. With this structure, the splash 23 does not contact and short-circuit between adjacent electrode pads 18. The Au ball 10 may be connected to the electrode pad 18 only by the thermocompression bonding technique without using the ultrasonic vibration technique. In this case, the generation of the splash 23 described above can be suppressed as much as possible. Alternatively, the bonding load can be adjusted by reducing the size of the Au ball 10 to suppress the occurrence of the splash 23 as much as possible. The Au ball may be any material as long as it exhibits the function of the second cushion and is softer than Cu as described above.

  Further, as described above, by reducing the occurrence of the splash 23, the electrode pad 18 between the bottom surface of the Au ball 10 and the insulating layer 20 remains sufficiently. With this structure, the bottom surface of the Au ball 10 is securely connected to the electrode pad 18, and an increase in connection resistance value at the electrode pad 18 can be prevented. In addition, poor connection at the electrode pad 18 can be prevented.

  As shown in FIG. 3B, the Cu wire 11 is stitch-bonded on the Au ball 10. As described above, since the Au ball 10 has a wide connection area with the electrode pad 18, the load during bonding of the Cu wire 11 is dispersed by the Au ball 10. That is, the Au ball 10 is used as a buffer material, and it is possible to prevent the insulating layer 20 below the electrode pad 18 from being damaged such as cracks due to an impact during bonding. Further, the dispersion of the bonding load prevents the splash 23 from significantly increasing, and is slightly larger than the splash 23 generated when the Au ball 10 is connected as shown in FIG. Therefore, the adjacent electrode pads 18 are not short-circuited by the splash 23.

  Further, the Cu wire 11 is stitch-bonded on the Au ball 10 and the height on the semiconductor element 9 is suppressed, so that the resin package 2 can be made thinner.

  The Cu wire 11 may be stitch-bonded to the Au ball 10 and the lead 6, or may be ball-bonded to the Au ball 10 and stitch-bonded to the lead 6. Also in these cases, as described above, short circuit due to the splash 23 is prevented, and damage to the insulating layer 20 is also prevented.

  Next, in FIG. 4 and FIG. 5, the problem of the short circuit caused by the splash and the problem of the crack in the insulating layer are dealt with by the structure of the electrode pad without using the Au ball 10 (see FIG. 3). In the following description, the same components as those of the semiconductor device described with reference to FIG.

  As shown in FIG. 4A, the electrode pad 24 has a structure in which a buffer material layer 26 is disposed between the Al layers 25 and 27. For example, the thickness of the Al layer 25 is about 0.4 μm, the thickness of the buffer material layer 26 is about 0.1 μm, the thickness of the Al layer 27 is about 2.9 μm, and the electrode pad The total film thickness of 24 is about 3.4 μm. The buffer material layer 26 is harder than the Al layers 25 and 27 and is formed of a refractory metal layer such as a titanium nitride (TiN) layer or a titanium tungsten (TiW) layer. As described above, an alloy layer mainly composed of Al may be disposed on the upper and lower surfaces of the buffer material layer 26.

  As shown in FIG. 4B, the Cu ball 28 is ball-bonded on the electrode pad 24 exposed from the opening 22. The Cu ball 28 slightly bites into the electrode pad 24 due to the load during ball bonding, and a splash 29 is generated around the Cu ball 28.

  As described above, the electrode pad 24 has a three-layer structure, so that the total thickness of the electrode pad 24 is the same as before, but the thickness of the Al layer 27 can be reduced. As a result, the amount driven around the Cu ball 28 by the bonding load is reduced, and the splash 29 itself is reduced. With this structure, it is possible to prevent the splash 29 from coming into contact with the adjacent electrode pad 24 to cause a short circuit. On the other hand, the buffer material layer 26 is disposed on the Al layer 25, so that it is difficult to be driven around the Cu ball 28 during bonding. As a result, the Al layer 25 is surely present on the bottom surface of the Cu ball 28, and poor connection at the electrode pad 24 is prevented.

  Further, by arranging the buffer material layer 26 between the Al layers 25 and 27, the bonding load is relaxed by the buffer material layer 26. As a result, the insulating layer 20 below the electrode pad 24 suppresses the occurrence of damage such as cracks. Furthermore, when the buffer material layer 26 is crushed by the bonding load, the Al layers 25 and 27 are directly connected in the crushed region. The current actively flows through the low resistance region, so that the increase in connection resistance value at the electrode pad 24 can be mitigated. As described above, since the buffer material layer 26 is formed of a low specific resistance metal layer, the connection resistance value at the electrode pad 24 is greatly increased even when the buffer material layer 26 is not crushed. Absent.

  As shown in FIG. 5A, the electrode pad 30 may be configured by forming a buffer material layer 31 on the upper surface of the insulating layer 20 and arranging an Al layer 32 so as to cover the buffer material layer 31. The buffer material layer 31 is disposed inside the opening 22 of the shield layer 21 and has a width W2 that is narrower than the width W1 of the opening 22. The shape of the buffer material layer 31 is a shape in which the shape of the opening 22 is similarly reduced. And the film thickness of the buffer material layer 31 is 0.5-1.0 micrometer, for example, and the film thickness of the Al layer 32 is 0.4-3.0 micrometers, for example. With this structure, in the electrode pad 30, the stacked region of the buffer material layer 31 and the Al layer 32 is a region protruding from the other regions. The material of the buffer material layer 31 is the same as that of the buffer material layer 26, and the design of the buffer material layer 31 can be arbitrarily changed as long as it is disposed in the opening 22. Further, it is sufficient that the above-described protruding region is formed on the electrode pad 30, and the buffer material layer 31 may be disposed in the Al layer similarly to the structure of FIG.

  As shown in FIG. 5B, the Cu ball 33 is ball-bonded on the electrode pad 30 exposed from the opening 22. Then, the Cu ball 33 slightly bites into the electrode pad 30 due to the load during ball bonding, and a splash 34 is generated around the Cu ball 33.

  The Cu ball 33 is ball-bonded to the protruding region of the electrode pad 30, so that the Al layer 32 in the protruding region is driven to the side surface side of the opening 22 as indicated by a dotted arrow. At this time, the expelled Al layer 32 first moves to the recessed area 35 (see FIG. 5A) around the protruding area, and embeds the recessed area 35. Then, the Al layer 32 overflowing from the recessed region 35 becomes the splash 34, so that the splash 34 itself becomes smaller. With this structure, it is possible to prevent the splash 34 from coming into contact with the adjacent electrode pad 30 to cause a short circuit.

  Further, the buffer material layer 31 is disposed in the region where the Cu balls 33 are ball bonded, so that the bonding load is relaxed by the buffer material layer 31 and the insulating layer 20 below the electrode pad 30 is damaged such as cracks. Can be prevented. Note that there is no particular problem even if a crack or the like occurs in the buffer material layer 31 due to the bonding load.

  As described above, in the present embodiment, a plurality of through holes 12 are formed in the island 7, and the flow of the inert gas is adjusted through the through holes 12 to prevent oxidation of the Cu wire 11 and its connection region. However, the present invention is not limited to this case. For example, even when the through hole 12 is not disposed in the island 7, the gap between the island 7 and the lead 6 or the gap between the leads 6 may be used to adjust the flow of the inert gas as described above. Further, the flow of the inert gas may be adjusted by using the through hole 12 in combination with the gap described above. In addition, various modifications can be made without departing from the scope of the present invention.

  Next, another embodiment will be described. 6A is a cross-sectional view of the resin package shown in FIG. 6B in the BB line direction. FIG. 6B is a view for explaining the lead frame and the heat sink as viewed from the surface side of the resin package. Note that in the description of this embodiment, the description of the semiconductor device described above with reference to FIGS.

  In the semiconductor device 41 shown in FIG. 6A, a part of the heat sink 43 is exposed from the back surface 44 of the resin package 42. The semiconductor element 46 is fixed on the heat sink 43 by an adhesive material 45 such as Ag paste or solder. An Au ball 48 is formed on the electrode pad of the semiconductor element 46, and the Au ball 48 and the inner lead portion of the lead 47 are electrically connected by a Cu wire 49 which is the theme of the present application. The shape and material of the Cu wire 49 are the same as those of the Cu wire 11 described above.

  In addition, a through hole 50 is formed in the heat sink 43 around the fixed region of the semiconductor element 46 and below the region where the Cu wire 49 is disposed. The inner lead portion of the lead 47 is disposed above the heat sink 43, and the tip of the inner lead portion of the lead 47 terminates before the through hole 50. The through hole 50 is disposed in the heat sink 43 and is used as a flow path for the inert gas (forming gas), thereby preventing the Cu wire 49 and its connection region from being oxidized as described above. Further, the through hole 50 is buried with an insulating resin, and the adhesion area between the heat sink 43 and the insulating resin is increased, so that the adhesion degree between the heat sink 43 and the resin package 42 is also improved.

  Furthermore, the Au ball 48 is disposed on the electrode pad, and the Cu wire 49 is wire-bonded to the Au ball. As described above, there is a problem of short circuit due to splash and a problem of a crack in the insulating layer below the electrode pad. Is resolved. Also, in the semiconductor device 41, by adopting the electrode pad structure shown in FIGS. 4 and 5, the problem of short circuit due to the above-described splash or cracks in the insulating layer can be achieved without using the Au ball 48 due to the structure of the electrode pad. It can also deal with problems.

  Next, as shown in FIG. 6B, the long side of the heat sink 43 is about 2 to 4 times the length of one side of the semiconductor element 46, and the short side of the heat sink 43 is one of the semiconductor elements 46. It is about 1 to 2 times the length of the side. The heat sink 43 is slightly smaller than the back surface 44 of the resin package 42, and conversely, is disposed over almost the entire back surface 44. Since the heat sink 43 is exposed from the back surface 44 side of the resin package 42, heat dissipation is improved.

  Next, a method for manufacturing a semiconductor device of the present invention will be described. 7A and 7B are plan views of the lead frame. FIG. 8A is a plan view of the clamper. FIG. 8B is a cross-sectional view showing the flow of an inert gas during wire bonding. 9A to 9C are cross-sectional views illustrating a wire bonding process. FIG. 10 is a plan view showing a resin molding process. 11A and 11B are a cross-sectional view and a perspective view, respectively, showing a lead processing and cutting process. In the following description, the same reference numerals are given to the same components as those of the semiconductor device described with reference to FIGS. Moreover, in the description of the manufacturing method of the present embodiment, the description will be made with reference to FIGS.

  First, as shown in FIG. 7A, for example, a lead frame 14 mainly made of Cu is prepared. A plurality of mounting portions 15 are formed on the lead frame 14 as indicated by a one-dot chain line. The longitudinal direction (paper surface X-axis direction) of the lead frame 14 is divided at regular intervals by the slits 51. In one section of the lead frame 14 delimited by the slits 51, for example, two mounting portions 15 are arranged in the short direction of the lead frame 14 (the Y axis direction on the paper surface). In the longitudinal direction of the lead frame 14, index holes 52 are provided at regular intervals in the upper and lower end regions, and are used for positioning in each step. The detailed structure constituting the mounting portion 15 is as described with reference to FIG.

  8B, an area indicated by a dotted line in FIG. 7B is an arrangement area of the gas vent hole 59 of the mounting table 53. For example, for one through hole 12, the area shown in FIG. One vent hole 59 is arranged. Further, by increasing the length L of each through hole 12, even when the lead frame 14 is slightly displaced when the lead frame 14 is disposed on the mounting table 53, the length L can be reliably prevented through the through hole 12. The active gas can be sucked. In the present embodiment, the flow of the inert gas is directed toward the mounting table 53, and the Cu wire 11 and the connection region of the Cu wire 11 are arranged in the flow to prevent oxidation thereof. Therefore, the gas vent hole 59 may be larger than the through hole 12. For example, the inert gas may be extracted by using an opening region between the island 7 and the lead 6 or an opening region between the leads 6.

  Next, as shown in FIG. 2B, the semiconductor element 9 is fixed on the island 7 using the adhesive 8 (see FIG. 1A) for each mounting portion 15 of the lead frame 14. At this time, the lead frame 14 is arranged on a mounting table of a die bonding apparatus in which a heating mechanism is incorporated, and the lead frame 14 is fixed on the mounting table by a clamper. Then, the island 7 of the lead frame 14 and the work area thereof are heated to, for example, about 250 to 260 ° C., and the semiconductor elements 9 are continuously fixed on the islands 7 respectively. The details are the same as the flow of the inert gas in the wire bonding step described with reference to FIG. 8B, but the inert gas is supplied into the working area from the clamper that fixes the lead frame 14. Then, the inert gas is pulled out to the mounting table side through the through holes 12 of the island 7, so that the periphery of the lead frame 14 is filled with the inert gas. As a result, the lead frame 14 is placed in a high temperature state for a long time, but its oxidation is prevented.

  Next, the lead frame 14 is disposed on the mounting table 53 of the wire bonding apparatus, and wire bonding is performed for each mounting portion 15 of the lead frame 14.

  First, the clamper 54 shown in FIG. The clamper 54 has a pipe 55 that feeds an inert gas and an opening region 56 that is opened in accordance with the size of the mounting portion 15. Then, the inert gas blown from the pipe 55 of the clamper 54 blows into the opening region 56 from between the lead fixing regions 57. In the case where the diameter of the Cu wire 11 is 45 μm, for example, 1.9 liter / min of nitrogen gas (including some hydrogen gas) is used. The Cu wire 11 is easily oxidized by being placed in a high temperature work area, but the presence of the inert gas prevents the Cu wire 11 from being oxidized.

  Furthermore, a plurality of lead fixing regions 57 are arranged in a comb-tooth shape on the clamper 54 around the opening region 56 in accordance with the shape of the lead 6 of the mounting portion 15. The plurality of leads 6 are individually fixed on the mounting table 53 (see FIG. 8B) by the lead fixing region 57. At this time, the Cu wire 11 is harder than the Au wire, but has a ductility, so that the load at the time of ball bonding (the load applied from the capillary 60 (see FIG. 9A)) becomes larger than that of the Au wire. The plurality of leads 6 are individually fixed by the lead fixing region 57 of the clamper 54 corresponding to each shape, thereby preventing a load from being escaped during bonding. Then, the Cu wire 11 is securely bonded onto the lead 6 and connection failure is prevented.

  Next, the flow of the inert gas illustrated in FIG. 8B will be described. A gas vent hole 59 is formed in the mounting table 53 having the heating mechanism 58. Then, the lead frame 14 is arranged on the mounting table 53 so that the through hole 12 of the island 7 is positioned on the upper surface of the gas vent hole 59. As indicated by the dotted arrows, the inert gas is blown from the space between the lead fixing regions 57 of the clamper 54 to the center side (mounting portion) of the opening region 56. That is, in the opening region 56, the inert gas is blown from the entire periphery to the center side. And the opening area | region 56 is not shielded, but the inside of the opening area | region 56 will be in a high temperature state, and an inert gas will be discharge | released above the opening area | region 56 by an updraft. Therefore, in the present embodiment, the inert gas blown from the top of the lead 6 mainly sucks the island 7 by sucking the inert gas from the gas vent hole 59 of the mounting table 53 through the through hole 12. Flows to the through-hole 12 side. As a result, the main flow of the inert gas is to the lower side (the mounting table 53 side) of the opening region 56, and the arrangement region of the Cu wire 11 is a region that is easily filled with the inert gas.

  The work area in the opening area 56 of the clamper 54 is maintained at, for example, about 250 to 260 ° C. by the heating mechanism 58. The wire wire-bonded Cu wire 11 is placed in the high-temperature work area until the wire bonding is completed for all the electrode pads of the semiconductor element 9. Therefore, by causing the flow of the inert gas described above, the inert gas is easily filled around the Cu wire 11, and the oxidation of the Cu wire 11 is efficiently prevented. In addition, the lead frame 14 such as the lead 6 is also easily oxidized, but the inert gas flows toward the mounting table 53, so that the lead frame 14 is also efficiently prevented from being oxidized.

  The inert gas is not limited to the case where the inert gas is blown from between the lead fixing regions 57 of the clamper 54. For example, the inert gas may be blown into the opening region 56 using a gas nozzle. Further, not all the inert gas blown into the opening region 56 is sucked from the gas vent holes 59 of the mounting table 53, and a part of the inert gas flows upward of the opening region 56. And the opening area | region 56 and its periphery become an area | region filled with the inert gas.

  Next, as shown in FIG. 9A, a Cu wire 61 is inserted into the center hole of the capillary 60, and a wire clamper 62 for holding the Cu wire 61 is disposed above the capillary 60. Then, a Cu wire 61 having a desired length is led out from the tip of the capillary 60 in advance and discharged from the torch 63 located in the vicinity of the capillary 60, and an initial ball (Cu ball) 64 is formed at the tip of the capillary 60. . As shown in the drawing, the inert gas is supplied to the work area where the initial ball 64 is formed. Therefore, the spherical shape of the initial ball 64 is stably formed by the oxidation / reduction action of hydrogen contained in the inert gas.

  Next, as shown in FIG. 9B, the capillary 60 descends onto the lead 6 and presses the initial ball 64 against the upper surface of the lead 6. Then, the initial ball 64 formed at the tip of the capillary 60 is connected to the lead 6 by a thermocompression bonding technique using ultrasonic vibration. During this operation, the wire clamper 62 is open.

  Next, as shown in FIG. 9C, the capillary 60 moves to the upper surface of the electrode pad 18 of the semiconductor element 9 while drawing a certain loop in a state where the wire clamper 62 is opened. Then, after the Cu wire 61 is clamped by the wire clamper 62, the capillary 60 is lowered onto the electrode pad 18 and presses the Cu wire 61 against the upper surface of the Au ball 10 on the electrode pad 18. Then, the Cu wire 61 is connected to the Au ball 10 by a thermocompression bonding technique using ultrasonic vibration. Thereafter, the capillary 60 rises, and a Cu wire 61 having a length to become an initial ball is led out from the tip of the capillary 60, and the Cu wire 61 is cut. Thereafter, the Cu wire 61 led out from the tip of the capillary 60 is processed into an initial ball as described above.

  Thereafter, the wire bonding operation described above with reference to FIGS. 9A to 9C is repeated for the Au balls 10 and the leads 6 on all the electrode pads 18 of the semiconductor element 9. Note that the Au ball 10 is connected to the electrode pad 18 in advance before the wire bonding step, thereby solving the problem of splash and cracking of the insulating layer as described above with reference to FIG.

  Next, as shown in FIG. 10, a heat-resistant sheet (not shown) made of, for example, a PET material is bonded to the back side of the lead frame 14, and the heat-resistant sheet and a resin sealing mold (not shown) are bonded. The lead frame 14 is placed in a resin-sealed mold so that the Then, the resin is filled into the cavities of the individual resin sealing molds, and the resin package 2 is formed. As illustrated, a plurality of resin packages 2 are formed on the lead frame 14 for each mounting portion 15. In addition, by using the heat-resistant sheet, the resin 7 can be prevented from wrapping around the back surface of the island 7 (see FIG. 1A), and the flatness of the back surface of the resin package 2 can be maintained.

  Finally, as shown in FIG. 11A, the lead frame 14 is placed on the pedestals 65 and 66 for lead bending. At this time, the lead 6 in the vicinity of the resin package 2 is fixed by the lead support mechanism 67, and the leading end side (tie bar 16 side) of the lead 6 is installed on the pedestal 66. Then, the lead 6 is bent while the tip end side of the lead 6 is cut by the punch 68. In this step, the tie bar 16 (see FIG. 2A) and the support region 17 (see FIG. 2A) are also punched out, and as shown in FIG. 2 is cut.

  In the present embodiment, the temperature of the inert gas blown into the opening region 56 of the clamper 54 is not particularly limited. However, for example, an inert gas may be blown into the opening region 56 after the inert gas is heated in the same manner as in the opening region 56 by installing a heating mechanism in the clamper 54. In this case, the Cu wire 61 is hardly cooled by the inert gas, and the current efficiency at the time of forming the initial ball can be improved.

  In addition, although the case where the work is performed in a state where the upper portion of the opening region 56 of the clamper 54 is not covered with a lid member such as a plate during wire bonding has been described, the present invention is not limited to this case. For example, the upper portion of the opening area 56 may be covered with a lid member that is opened only in the work area where wire bonding is performed, and the lid member may slide in accordance with the work area. In this case, the upper part of the opening area 56 is generally covered with the lid member, so that the opening area 56 is easily filled with the inert gas. And the supply amount of an inert gas is also reduced and the effect which can suppress manufacturing cost is also acquired.

  Further, the case where the individual leads 6 are individually fixed by the lead fixing region 57 of the clamper 54 during wire bonding has been described, but the present invention is not limited to this case. For example, a plurality of adjacent leads may be divided and fixed by a lead fixing region according to the lead arrangement situation such as the lead shape and lead height. In this case, the number of lead fixing areas is smaller than the total number of leads. In addition, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 Resin package 6 Lead 7 Island 12 Through-hole 54 Clamper 56 Opening area 57 Lead fixing area 59 Gas vent hole

Claims (13)

An island, a plurality of leads arranged around the island, a semiconductor element fixed on the island, and a thin wire mainly composed of copper electrically connecting the electrode pad of the semiconductor element and the lead And a semiconductor device having a resin package that covers the island, the lead, the copper wire, and the semiconductor element,
One end of the fine wire is connected to a metal ball softer than the copper formed on the pad, and the other end of the fine wire is connected to the lead. The semiconductor device according to claim 1, wherein the metal ball is made of gold. The semiconductor device according to claim 2, wherein one end of the thin wire connected to the metal ball is stitch-bonded. An island, a plurality of leads arranged around the island, a semiconductor element fixed on the island, and a thin wire mainly composed of copper electrically connecting the electrode pad of the semiconductor element and the lead And a semiconductor device having a resin package that covers the island, the lead, the copper wire, and the semiconductor element,
A semiconductor device, wherein a buffer material layer is disposed on an inner layer of the electrode pad or a lower surface of the electrode pad, and one end of the fine wire is bonded to the electrode pad. The semiconductor device according to claim 4, wherein the buffer material layer is a metal layer harder than a metal layer constituting the electrode pad, and is crushed in the metal pad. 5. The electrode pad is exposed from an opening of a shield layer that covers the surface of the semiconductor element, and the buffer material layer is smaller than an opening area of the opening and is disposed in the opening. Alternatively, the semiconductor device according to claim 5. 5. The island according to claim 1, wherein a plurality of through holes are formed in the island around a fixed region of the semiconductor element, and the through holes are filled with a resin constituting the resin package. The semiconductor device described. The shape of the through hole is a circle, an ellipse, or a rectangle, and the width of the through hole is equal to or larger than the separation width between the adjacent leads. Semiconductor device. Preparing a lead frame provided with a mounting portion having an island, a plurality of leads arranged around the island, and a suspension lead extending from the island;
After fixing a semiconductor element on the island, electrically connecting the electrode pad of the semiconductor element and the lead with a fine wire mainly made of copper, and forming a resin package covering the mounting portion, In a manufacturing method of a semiconductor device for bending a lead and separating the resin package from the lead frame,
Fixing the lead frame on the mounting table of the wire bonding apparatus;
A method of manufacturing a semiconductor device, characterized in that a gas flow that prevents oxidation of the fine wire is generated from above the fine wire connection region toward the connection region. The method for manufacturing a semiconductor device according to claim 9, wherein the gas is extracted from an opening region provided in the lead frame and / or a gas vent hole of the mounting table. The method of manufacturing a semiconductor device according to claim 10, wherein the gas is extracted through at least the opening region between the island and the lead or the opening region between the leads. 12. The method of manufacturing a semiconductor device according to claim 10, wherein the island is provided with a plurality of through holes, and the gas is extracted through the opening region of the through holes. By fixing the leads individually by a clamper having a lead fixing area corresponding to the leads, the lead frame is fixed on the mounting table,
The method of manufacturing a semiconductor device according to claim 9, wherein the clamper supplies the gas from between the lead fixing regions to the mounting portion.

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