JP2005311099A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device which is resin-sealed, by bonding a chip to a lead frame by a bump to reduce the stress generated, due to the difference of the thermal expansion coefficients of the lead frame and a semiconductor chip in the chip at a packaging time, and to provide a method of manufacturing the same. <P>SOLUTION: The semiconductor device includes the semiconductor chip 3; the lead frame 1 of Cu, etc.; a bump electrode 2 electrically connecting the semiconductor chip to the lead of the lead frame; and a resin sealer 4 for sealing at least the part of the lead, the semiconductor chip, and the bump. A notch 5 is formed at the lead. The notch is sealed by the resin sealer, and formed at the outside from the bump disposed on the semiconductor chip to the semiconductor chip. When the semiconductor device is mounted on the packaging substrate of an electronic apparatus, even if the stress is generated due to the difference of the linear expansion coefficients of the semiconductor chip and the lead frame is generated in the semiconductor device, the notched part is deformed, to reduce the stress applied to the semiconductor chip. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor device and a method for manufacturing the same, and particularly to a semiconductor package in which a flip chip type semiconductor chip is mounted on a lead frame.

  A semiconductor package in which a conventional flip chip type semiconductor chip is mounted on a lead frame, that is, a semiconductor device is shown in FIG. In the figure, a lead frame 101 is composed of a plurality of leads supported by a peripheral frame portion (not shown). The lead frame 101 is made of a metal material such as copper (Cu) or an Fe-42Ni alloy. On the other hand, a semiconductor chip 103 on which a semiconductor element such as a transistor is formed is made of silicon or the like, and has a surface electrode (not shown) made of aluminum or the like electrically connected to the semiconductor element. A bump electrode such as Au) or solder or a bump 102 is joined. In addition, the semiconductor chip 103 is electrically connected to the lead frame 101 via bumps 102. Part of the leads of the lead frame 101, the bumps 102, and the semiconductor chip 103 have a structure sealed with a resin sealing body 104 made of a mold resin made of epoxy resin or the like.

The lead frame 101 uses a metal material such as Cu or Fe-42Ni. For example, the linear expansion coefficient of Cu constituting the lead frame is 17 × 10 ⁻⁶ , whereas the lead frame 101 constitutes a semiconductor chip. The linear expansion coefficient of silicon is 2.8 × 10 ^−6, and there is a large difference between the two. Therefore, when a semiconductor product in which a semiconductor chip is bonded to a lead frame with a bump and resin-sealed is mounted on a mounting substrate, mechanical stress is generated in the semiconductor chip, and in some cases, chip cracking occurs.

  For example, Patent Document 1 is known as a conventional technique for preventing the occurrence of chip cracks occurring in a semiconductor chip. This semiconductor device has a frame member provided with a chip mounting portion for supporting a semiconductor chip. The semiconductor chip and the chip mounting portion are joined by silver plating. A large number of voids are provided in the silver plating. The semiconductor chip and its periphery, the wire for electrically connecting the semiconductor chip and the lead, and the silver plating are resin-sealed by the sealing body. This void portion relieves stress applied to the semiconductor chip and prevents chip cracks. Further, for example, Patent Document 2 describes a resin-sealed package of a resin-sealed semiconductor device that is thinned without reducing the strength of a lead and without reducing the mechanical strength of a semiconductor chip.

  The thickness of the outer lead constituting the lead frame is not particularly reduced, and the lead frame is partially thinned. A semiconductor chip is mounted and electrically connected to the thinned portion. And the part in which this semiconductor chip is mounted is resin-sealed. In this case, the thickness of the semiconductor chip is made thinner than before so as to be within the depth of the recess of the lead frame. Since the semiconductor chip is completely accommodated in the thinly processed part of the lead frame, the thickness of the resin-encapsulated package depends only on the thickness of the lead frame and the resin, and the thickness of the package can be reduced. In addition, by making the element fixing pad a part of the structure of the lead frame, it is possible to hold the element and to dissipate heat from the pad. By providing a thinly processed portion on a part of the outer lead, thermal stress acting on the junction between the semiconductor device and the circuit board is alleviated. Moreover, the cutting | disconnection is made easy by forming the part processed thinly in the dam bar. Further, the inner leads cover almost the entire surface of the semiconductor element in the recess for housing the semiconductor element, whereby the semiconductor element can be held and heat dissipation is improved.

For example, Patent Document 3 describes a semiconductor device including a die pad that has good adhesion to a sealing resin, high strength, and is difficult to warp. A plurality of hemispherical upper surface side dimples are formed in a semiconductor chip mounting area on a semiconductor chip mounting surface on which a semiconductor chip is mounted, and the semiconductor chip on the lower surface of the die pad on which no semiconductor chip is mounted A plurality of hemispherical lower surface side dimples are formed in the mounting area in a state of being alternately arranged with the upper surface side dimples. The upper surface side dimples are densely arranged within a range that does not overlap with each other, and are arranged in a line in a direction intersecting with the sides of the die pad at a predetermined angle. A lower surface side dimple having the same shape and the same size as the upper surface side dimple is also arranged in the same manner. A semiconductor chip is mounted on the upper surface of the die pad, and is sealed with resin through a wiring process.
Japanese Patent Laid-Open No. 10-284516 (FIG. 2) Japanese Patent Laid-Open No. 8-11016 (FIG. 13) Japanese Unexamined Patent Publication No. 2000-269401 (FIG. 1)

  The present invention has been made under such circumstances. When a semiconductor device in which a semiconductor chip is bonded to a lead frame by bumps such as Au or solder and sealed with resin is mounted on a mounting substrate, the lead frame is mounted on the semiconductor chip. It is an object of the present invention to provide a semiconductor device configured to reduce stress generated due to a difference in coefficient of linear expansion between the semiconductor chip and the semiconductor chip, and a manufacturing method thereof.

In order to achieve the above object, one aspect of a semiconductor device of the present invention includes a semiconductor chip, a lead frame made of a metal material, a bump electrode that electrically connects the semiconductor chip and leads of the lead frame, And a resin sealing body that seals at least a part of the lead, the semiconductor chip, and the bump electrode, the lead has a notch, and the notch is sealed by the resin sealing body, and The semiconductor chip is characterized in that it is formed at a portion outside the bump electrode arranged on the semiconductor chip.
According to another aspect of the method for manufacturing a semiconductor device of the present invention, a step of electrically connecting a semiconductor chip and a lead of a lead frame made of a metal material via a bump electrode, at least a part of the lead, and the semiconductor And a step of resin-sealing the chip and the bump electrode, the lead has a notch, the notch is sealed with a resin sealing body in the resin sealing step, and the semiconductor chip The semiconductor device is characterized in that it is formed in a portion outside the bump electrodes arranged on the semiconductor chip.

  In the present invention, when the manufactured semiconductor device is mounted on a mounting board of an electric device, for example, even if stress is generated due to a difference in linear expansion coefficient between the semiconductor chip and the lead frame, the lead Such a stress applied to the semiconductor chip can be reduced by deforming the notch portion provided in the frame, and as a result, the reliability of the semiconductor device can be greatly improved.

The present invention relates to a flip chip type semiconductor device having a bump for electrically connecting a lead frame, which is a metal material, and a semiconductor chip, and a resin sealing body for sealing the lead frame, the semiconductor chip, the bump electrode, and the like. 1 is characterized in that a notch is formed in a portion outside the bump electrode disposed on the semiconductor chip of the lead constituting the lead frame.
Hereinafter, the best mode for carrying out the invention will be described with reference to examples.

First, Embodiment 1 will be described with reference to FIGS.
FIG. 1 is a schematic cross-sectional view of the semiconductor device of this embodiment, and FIG. 2 is a partially transparent plan view of the semiconductor device of FIG. As shown in FIG. 1, the lead frame 1 is composed of a peripheral frame portion (not shown) and a lead portion including a plurality of leads 1a supported by the frame portion. The lead frame 1 is made of a metal material such as copper (Cu), a copper alloy, or a Fe-42Ni alloy. In this embodiment, Cu is used as the lead frame material. The semiconductor chip 3 on which semiconductor elements such as transistors are formed is made of silicon or the like. The semiconductor chip 3 has a pad or surface electrode (not shown) made of aluminum or the like, and the surface electrode is electrically connected to the semiconductor element.

  Bump electrodes (hereinafter referred to as bumps) 2 such as gold (Au) or solder are joined to the surface electrodes. In this embodiment, solder is used as the bump material. A semiconductor chip 3 is bonded to the lead frame 1 by bumps 2. One end of the lead 1 a constituting the lead frame 1 is supported by the frame portion of the lead frame 1, and the other end extends in the center direction of the semiconductor chip 3. In the vicinity of the other end, the lead 1 a is bonded to the bump 2 on the chip 3.

The lead 1a has a thin tip at the other end, and the semiconductor chip 3 is bonded to the thin portion via bumps 2. The lead frame generally has a thickness of about 80 to 400 μm. The leading end portion of the lead is thinned to about ½. In this embodiment, the thickness of the lead frame 1 is about 200 μm, and the thin portion at the tip of the lead 1a is about 100 μm.
A part of the lead 1a of the lead frame 1, the bump 2 and the semiconductor chip 3 are all sealed with a resin sealing body 4 made of a mold resin made of epoxy resin or the like.

  In the lead 1 a constituting the lead portion of the lead frame 1, a notch 5 that is a weak portion is formed in the vicinity of the portion where the semiconductor chip 3 is fixed by the bump 2. The notch 5 is formed by thinning the lead 1a by a known method. The thickness is suitably about ½ of the thin portion at the tip of the lead. In this embodiment, the thickness of the notch 5 is about 50 μm. The notch 5 is also sealed with the resin sealing body 4. Further, the notch 5 is formed in a portion outside the bump 2 with respect to the semiconductor chip 3. That is, the position of the notch 5 is outside the portion between the other end of the lead 1a and the portion where the bump 2 is joined. The notch 5 may be provided above the semiconductor chip 3 or may be separated from the top of the semiconductor chip 3.

In the lead frame 1, for example, the linear expansion coefficient of Cu constituting the lead frame is 17 × 10 ⁻⁶ , whereas the linear expansion coefficient of silicon constituting the semiconductor chip is 2.8 × 10 ^−6. Therefore, when a semiconductor product in which a semiconductor chip is fixed to a lead frame with a bump and resin-sealed is mounted on a mounting board of a set, mechanical stress is generated on the semiconductor chip, and in some cases chip cracks occur. It will occur. However, the stress applied to the semiconductor chip due to the difference between the linear expansion coefficients of the lead frame and the semiconductor chip can be reduced by the deformation of the notch.

Next, a method for manufacturing the semiconductor device of this embodiment will be described.
First, a surface electrode such as aluminum is formed on a semiconductor chip 3 made of silicon or the like on which a semiconductor element such as a transistor is formed, and bumps such as solder are attached to the surface electrode. Next, the lead 1a constituting the lead portion of the lead frame 1 is disposed so that the tip of the lead 1a faces the central portion of the semiconductor chip 3, and the semiconductor chip 3 and the lead 1a of the lead frame 1 are joined via the bumps 2, Are electrically connected. Next, the lead frame 1 is placed on a resin mold together with the semiconductor chip 3, and at least a part of the lead 1a, the semiconductor chip 3 and the bump 2 are sealed by a transfer molding method or the like, and a resin seal made of epoxy resin or the like is sealed. A stop 4 is formed. Thereafter, the lead frame 1 is molded to remove unnecessary portions to complete a product. According to this embodiment, it is possible to easily form a semiconductor device with less chip cracks during mounting.

Next, Embodiment 2 will be described with reference to FIGS.
FIG. 3 is a schematic sectional view of the semiconductor device of this embodiment, and FIG. 4 is a perspective plan view of the semiconductor device of FIG. 3 as viewed from above. As shown in the drawing, the lead frame 21 includes a peripheral frame portion (not shown) and a lead portion including a plurality of leads 21a supported by the frame portion. The lead frame 21 is made of a metal material such as Cu, its alloy, or Fe-42Ni alloy. In this embodiment, Cu is used as the lead frame material. A semiconductor chip 23 on which a semiconductor element such as a transistor is formed is made of silicon or the like. The semiconductor chip 23 has a surface electrode (pad) (not shown) made of aluminum or the like, and this electrode is electrically connected to the semiconductor element. Bumps 22 such as Au and solder are joined to the surface electrode.

In this embodiment, solder is used as the bump material. A semiconductor chip 23 is bonded to the lead frame 21 by bumps 22. One end of the lead 21 a is supported by the frame portion of the lead frame 21, and the other end extends in the center direction of the semiconductor chip 23. The tip portion on the other end side of the lead 21a is thin (about 100 μm), which is about ½ of the other portions.
A part of the lead 21a of the lead frame 21, the bump 22 and the semiconductor chip 23 are all sealed with a resin sealing body 24 made of a mold resin such as an epoxy resin.

  A notch 25, which is a weak portion, is formed in the vicinity of the portion where the semiconductor chip 23 is fixed by the bump 22 in the thin portion at the tip of the lead 21 a of the lead frame 21. In the previous embodiment, the notch is formed on the side opposite to the side where the semiconductor chip of the lead is mounted. In this embodiment, the notch 25 is provided on the side of the lead 21a where the semiconductor chip 23 is mounted. Is formed. The thickness of the notch 21a is about 50 μm and is about ½ of the thin pressure portion at the tip of the lead 21a. The notch 25 is sealed with the resin sealing body 24. Further, the semiconductor chip 23 is formed at a portion outside the bump 22. That is, the position of the notch 25 is outside the portion between the other end opposite to the one end supported by the frame portion of the lead 21a and the portion where the bump 22 is joined. The notch 25 may be above the semiconductor chip 23 or may be separated from the semiconductor chip 23.

  As described in the previous example, the lead frame has a large difference in linear expansion coefficient between the lead frame and the semiconductor chip. Therefore, a semiconductor product in which the semiconductor chip is fixed to the lead frame with bumps and resin-sealed is mounted on the set. When the semiconductor chip is mounted on the substrate, mechanical stress is generated in the semiconductor chip, and in some cases, chip cracking occurs. However, the stress applied to the semiconductor chip due to the difference between the linear expansion coefficients of the lead frame and the semiconductor chip can be reduced by the deformation of the notch. This effect does not change greatly whether the notch is on the semiconductor chip side or the opposite side.

1 is a schematic cross-sectional view of a semiconductor device according to Embodiment 1 of the present invention. FIG. 2 is a partial perspective plan view of the semiconductor device of FIG. 1 viewed from above. FIG. 6 is a schematic cross-sectional view of a semiconductor device according to Example 2 of the present invention. FIG. 4 is a partial perspective plan view of the semiconductor device of FIG. 3 viewed from above. Sectional drawing of the semiconductor package which mounted the conventional flip chip type semiconductor chip in the lead frame.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 21 ... Lead frame 1a, 21a ... Lead 2, 22 ... Bump 3, 23 ... Semiconductor chip 4, 24 ... Resin sealing body 5, 25 ... Notch

Claims (5)

A semiconductor chip;
A lead frame made of a metal material;
A bump electrode for electrically connecting the lead of the semiconductor chip and the lead frame;
Comprising at least a part of the lead, a resin sealing body for sealing the semiconductor chip and the bump electrode;
The lead has a notch, and the notch is sealed with the resin sealing body, and is formed on a portion outside the bump electrode disposed on the semiconductor chip with respect to the semiconductor chip. A semiconductor device characterized by the above. The semiconductor device according to claim 1, wherein a stress generated by a difference in linear expansion coefficient between the lead frame and the semiconductor chip and reduced on the semiconductor chip is reduced by deformation of the notch. The semiconductor device according to claim 2, wherein the lead frame is made of copper, and the semiconductor chip is made of silicon. Electrically connecting a semiconductor chip and a lead of a lead frame made of a metal material via a bump electrode;
A step of resin-sealing at least part of the leads, the semiconductor chip, and the bump electrodes;
The lead has a notch, and the notch is sealed with a resin sealing body in the resin sealing step, and at a portion outside the bump electrode disposed on the semiconductor chip with respect to the semiconductor chip. A method for manufacturing a semiconductor device, wherein the semiconductor device is formed. 5. The method of manufacturing a semiconductor device according to claim 4, further comprising a step of electrically connecting the lead and the bump electrode after attaching the bump electrode to the surface electrode of the semiconductor chip.

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