JP3151324B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC, an LSI, and a VLS.
Highly integrated semiconductor integrated circuits (semiconductor chips)
The present invention relates to a semiconductor device in which is mounted on a lead frame.

[0002]

2. Description of the Related Art In general, lead frames are often used for mounting semiconductor chips such as ICs, LSIs, and VLSIs. This lead frame usually includes an island formed at the center and inner leads formed around the island, and the semiconductor chip is die-bonded on the island.

Under these circumstances, recently, there is no portion corresponding to an island, and a semiconductor chip is provided below or above the surface of a lead frame.
A semiconductor device provided with a lead frame having an ad on chip (COL) or a COL (chip on lead) structure has been developed. Advantages of using this LOC or COL structure include product development in various packages, high-speed operation and noise suppression at the time of simultaneous output of multi-bit versions, support for large semiconductor chips, and reduction of lead frame design time. Etc.,
A great effect can be expected in solving many problems in producing a state-of-the-art semiconductor chip.

FIG. 4 is a configuration diagram of a semiconductor device having a lead frame having this kind of LOC structure. A semiconductor chip 2 is mounted on the lead frame 1. The lead frame 1 is formed of a conductive material (42 alloy or a copper material sandwiched between 42 alloys on both sides thereof).

The tip of each inner lead 3 of the lead frame 1 is positioned (aligned) with respect to each electrode (aluminum electrode or the like, hereinafter referred to as a pad) 4 of the semiconductor chip 2, and furthermore, each inner lead 3 is formed. And the respective pads 4 of the semiconductor chip 2 are wire-bonded by bonding wires (Au wire, Al wire, etc.) 5 and connected to each other.

Here, in order to position the tip of each inner lead 3 and each pad 4 of the semiconductor chip 2, the semiconductor chip 2 and the inner lead 3 are temporarily fixed with a double-sided adhesive tape 6 before performing wire bonding. It is done by doing.

In connection by such wire bonding, the shortest distance between adjacent bonding wires 5 is restricted by the outer shape of a bonding capillary (needle) to be used.
It is difficult to reduce the distance to about 100 μm or less.

Further, in order to connect the Au wire or the Al wire to the pad 4 on the semiconductor chip 2 with a metal, it is necessary to apply a physical load such as heating, pressurizing, ultrasonic vibration, etc. May damage the semiconductor chip 2 itself.

Therefore, in order to solve the above-mentioned problems, recently, for example, one disclosed in Japanese Patent Application Laid-Open No. 4-37149 has been proposed. That is, the connection between the inner lead of the lead frame and the electrode of the semiconductor chip is performed by metal plating or by using a conductive adhesive and metal plating in combination.

However, the semiconductor device having such a connection has the following problems.

That is, since the semiconductor chip 2 and the lead frame 1 are bonded and fixed by the double-sided adhesive tape 6, the gap between them cannot be filled by plating. Further, even if the gap can be filled, the plating film grows isotropically (100 μm downward).
m, and grows about 100 μm on both sides).
If plating is performed only to grow and connect in the direction, the inner leads 3 come into contact with each other and short-circuit. Therefore, a non-contact portion occurs between the pad 4 of the semiconductor chip 2 and the inner lead 3 of the lead frame 1, and the connection between the semiconductor chip 2 and the lead frame 1 is not reliably performed. There is a problem in responding to the change.

If the pads 4 of the semiconductor chip 2 and the inner leads 3 of the lead frame 1 are not in contact with each other and sufficient connection strength between the semiconductor chip 1 and the lead frame 2 cannot be obtained, peeling occurs during molding and other processing. Will occur.

As described above, when manufacturing the semiconductor device, when the semiconductor chip 2 is temporarily fixed to the inner lead 3 of the lead frame 1 by thermocompression bonding, the tip of the inner lead 3 is attached to the semiconductor chip 2. There is a problem that the pad 4 of the semiconductor chip 2 is damaged when it comes into contact with the pad 4.

When the pad 4 of the semiconductor chip 2 is damaged as described above, the plating solution or the like intrudes from the damaged portion, thereby causing corrosion of the electrodes 4 and wirings, thereby lowering the reliability of the semiconductor chip 2. I will.

When the tip of the inner lead 3 comes into contact with the pad 4 during the temporary fixing, the pad 4 may be damaged. Therefore, there is a possibility that the electrode, the aluminum (Al) wiring, and the like are corroded from the damaged portion of the pad 4.

[0016]

As described above, when mounting the semiconductor chip 2 on the lead frame 1, the connection between the tip of the inner lead 3 and the pad 4 on the semiconductor chip 2 is not sufficient, and Contact areas may occur.
Further, when the tip of the inner lead 3 comes into contact with the pad 4 during the temporary fixing, the pad 4 may be damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device which can securely connect a tip of an inner lead to a pad and can prevent damage to the pad.

[0018]

SUMMARY OF THE INVENTION According to the present invention, a double-sided adhesive tape is interposed between a semiconductor chip having an electrode and an inner lead of a lead frame, and temporarily fixed by thermocompression bonding. At least two types of metal materials having different coefficients of thermal expansion are laminated, and a metal material having a small coefficient of thermal expansion is arranged on the electrode side. Thus, a semiconductor device that achieves the above object.

The present invention also relates to the above semiconductor device,
The inner lead is sandwiched between a first metal material, for example, a second metal material having a thermal expansion coefficient smaller than that of a copper alloy, for example, an iron-nickel alloy, and the second metal material is sandwiched. This is a semiconductor device that achieves the above object by removing a tip portion of a second metal material disposed on the side opposite to the electrode side.

[0020]

With the provision of such means, at least the inner lead portion of the lead frame is provided with a metal material having a low coefficient of thermal expansion on the electrode side. When the inner lead is temporarily fixed by heating through a double-sided tape, the metal material having a large coefficient of thermal expansion increases in the inner lead, and the inner lead is bent toward the side having a small coefficient of thermal expansion. Due to this bending, the tip of the inner lead is bent toward the electrode side of the semiconductor chip and comes into contact with this electrode.

In this case, if the metal materials having different coefficients of thermal expansion are an iron-nickel alloy and a copper alloy, the coefficient of thermal expansion of the copper alloy is larger and the inner lead is bent toward the iron-nickel alloy.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram of a semiconductor device. A plurality of inner leads 11 are formed on a lead frame 10 formed of a conductive material. As shown in FIG. 2, the inner leads 11 are formed of a clad material in which two layers of an iron (Fe) -nickel (Ni) alloy, that is, a 42 alloy 12 and a copper (Cu) alloy 13 are laminated.

These 42 alloy 12 and Cu alloy 13
The coefficients of thermal expansion are different from each other, and the coefficient of thermal expansion of the Cu alloy 13 is larger than the coefficient of thermal expansion of the alloy 42.

The 42 alloy 12 and the Cu alloy 13
In the first embodiment, the 42 alloy 12 is arranged on the pad 4 side of the semiconductor chip 2, and the Cu alloy 13 is arranged outside thereof. The thickness of each of the 42 alloy 12 and the Cu alloy 13 is 75 μm.

With this configuration, when the semiconductor chip 2 is temporarily fixed to the lead frame 10, the double-sided tape 6 is interposed between the semiconductor chip 2 and the inner lead 11. The double-sided tape 6 is a double-sided tape using an acrylic adhesive. Then, in this state, the positioning of each pad 4 on the semiconductor chip 2 and the tip of each inner lead 11 is performed. At the time of this positioning, the tip of each inner lead 11 and each pad 4 are in an approaching state.

Thereafter, the semiconductor chip 2 of the double-sided tape 6 and each inner lead 11 are temporarily fixed by thermocompression bonding. The heating temperature in this thermocompression bonding is approximately 200 ° C.

The heat at the time of thermocompression bonding is based on 42 alloy 12 and Cu
To the alloy 13 and the 42 alloy 12 and the Cu alloy 1
3 thermally expands. At this time, since the thermal expansion coefficient of the Cu alloy 13 is higher than the thermal expansion coefficient of the 42 alloy 12, the entire inner lead 11 gradually bends in the direction of the arrow (a), that is, toward the pad 4. The inner lead 11 is bent by this bending.
Contact the pad 4. The contact between the tip of the inner lead 11 and the pad 4 is
Since it is performed by the entire bending, there is no damage to the pad 4 and the pad 4 is securely contacted.

After the temporary fixing, the tip of each inner lead 11 and each pad 4 are connected by, for example, electroplating.

As described above, in the first embodiment,
Since the inner lead 11 is formed by laminating metal materials of the 42 alloy 12 and the Cu alloy 13 having different coefficients of thermal expansion from each other, and the 42 alloy 12 having a small coefficient of thermal expansion is arranged on the pad 4 side, the coefficient of thermal expansion of the Cu alloy 13 is reduced. The inner lead 11 is larger than the coefficient of thermal expansion of the 42 alloy 12, and the inner lead 11 can be bent and brought into contact with the pad 4 without being damaged by the thermocompression bonding at the time of temporary fixing, and the contact is ensured. can do.

Therefore, the temporary fixing can be reliably performed, and the subsequent connection processing by electroplating can be reliably performed, and the non-contact portion can be eliminated.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a configuration diagram of an inner lead portion of a lead frame in a semiconductor device. The inner lead 20 is formed by coating both surfaces of the Cu alloy 21 with each of the 42 alloys 22 and 23.
It is sandwiched between. In this case, Cu alloy 2
The thickness of the Cu alloy 21 and the thickness of each of the 42 alloys 22 and 23 are 70 μm, and the thickness of each of the 42 alloys 22 and 23 is 40 μm.

Of the 42 alloys 22 and 23, the tip of the 42 alloy 22 opposite to the pad 4 when viewed from the Cu alloy 21 is removed by half etching.
This half-etched portion is the inner lead 20
Is closer to the pad 4 than the position of the double-sided tape 6. Therefore, the double-sided tape 6 in the inner lead 20
The pad 4 side is formed by two layers of Cu alloy 21 and 42 alloy 23.

With this configuration, when the semiconductor chips 2 are temporarily fixed to the lead frame, the double-sided tape 6 is interposed between the semiconductor chips 2 and the inner leads 20, and in this state, the semiconductor chip 2 Each pad 4 and the tip of each inner lead 20 are positioned. At the time of this positioning, the tip of each inner lead 20 and each pad 4 are in an approaching state.

Thereafter, the semiconductor chip 2 of the double-sided tape 6 and the inner leads 20 are temporarily fixed by thermocompression bonding. The heating temperature in this thermocompression bonding is approximately 200 ° C. as described above.

The heat during the thermocompression bonding is applied to the Cu alloys 21 and 42.
To the alloys 22 and 23 and the Cu alloys 21 and 42
The alloys 22, 23 thermally expand.

At this time, at the tip of the inner lead 20 formed of two layers of the Cu alloy 21 and the 42 alloy 23,
Since the coefficient of thermal expansion of the Cu alloy 13 is larger than the coefficient of thermal expansion of the 42 alloy 12, it gradually bends in the direction of the arrow (a), that is, toward the pad 4. Due to this bending, the tip of the inner lead 20 comes into contact with the pad 4 as described above. Since the contact between the tip of the inner lead 20 and the pad 4 is performed by bending the entire inner lead 20, the pad 4 is securely contacted without being damaged.

On the other hand, in the portion formed by the three layers of the Cu alloy 21 and the 42 alloys 22 and 23 of the inner lead 20, the thermal expansion coefficients on both sides of the Cu alloy 21 are the same.
No bending occurs.

After the temporary fixing, the tip of each inner lead 20 and each pad 4 are connected by, for example, electroplating.

As described above, in the second embodiment,
The inner lead 20 is formed by forming 42 alloys 22 and 23 on both surfaces of the Cu alloy 21 respectively.
Since the alloy 22 was removed by half-etching to form a two-layer structure, the thermal expansion coefficient of the Cu alloy 21 was larger than that of the 42 alloy 23 in the two-layer portion, as in the first embodiment. In addition, the inner leads 20 are bent by thermocompression bonding at the time of temporary fixing and can be brought into contact with the pad 4 without damaging the pad 4, and the contact can be ensured.

Accordingly, only the necessary portion of the inner lead 20 is bent to secure the temporary fixing, and the subsequent connection processing by electroplating can be reliably performed, and the non-contact portion can be eliminated.

Further, in the portion formed by the three layers of the lead frame (outer lead portion), it does not bend during thermocompression bonding, can have high mechanical strength, and does not deform the entire lead frame. .

The present invention is not limited to the above embodiments, but may be changed without departing from the scope of the invention. For example, the present invention is not limited to the two-layer structure of the Cu alloy and the 42 alloy, and instead of the 42 alloy, iron (F
e) A nickel (Ni) -cobalt (Co) alloy may be used.

The lead frame is not limited to the two-layer structure of the Cu alloy and the 42 alloy, but may be formed by arranging a plurality of metal materials having a higher thermal expansion coefficient as viewed from the pads on the semiconductor chip.

Although the lead frame 20 is formed in two layers by half etching, it may be removed by cutting or the like.

[0047]

As described above in detail, according to the present invention, it is possible to provide a semiconductor device capable of ensuring the connection between the tip of the inner lead and the pad and preventing damage to the pad.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of a semiconductor device according to the present invention.

FIG. 2 is a configuration diagram of an inner lead in the apparatus.

FIG. 3 is a configuration diagram of an inner lead showing a second embodiment of the semiconductor device according to the present invention.

FIG. 4 is a configuration diagram of a conventional device.

[Explanation of symbols]

2: semiconductor chip, 4: pad, 6: double-sided tape, 10
... Lead frame, 11,20 ... Inner lead, 12,
22, 23 ... 42 alloy, 13, 21 ... Cu alloy.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yoshimasa Kudo 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Tamagawa Plant (72) Inventor Shinya Shimizu Komukai-Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa No. 1 Toshiba Tamagawa Plant Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 23/50 H01L 21/60 321

Claims (3)

(57) [Claims] 1. A two-sided adhesive tape is interposed between a semiconductor chip having an electrode and an inner lead of a lead frame, temporarily fixed by thermocompression bonding, and an electrode of the semiconductor chip and a tip of the inner lead are connected by plating. In the semiconductor device, at least the inner lead portion of the lead frame is formed by laminating at least two types of metal materials having different coefficients of thermal expansion from each other, and the metal material having a smaller coefficient of thermal expansion is arranged on the electrode side. A semiconductor device characterized by being formed by: 2. A two-sided adhesive tape is interposed between a semiconductor chip having an electrode and an inner lead of a lead frame, temporarily fixed by thermocompression bonding, and the electrode of the semiconductor chip and the tip of the inner lead are connected by plating. In the semiconductor device, at least the inner lead portion of the lead frame is sandwiched between the first metal material by a second metal material having a smaller thermal expansion coefficient than a thermal expansion coefficient of the first metal material, and A semiconductor device, wherein a tip portion of a second metal material disposed on a side opposite to the electrode side of the second metal material is removed. 3. The method according to claim 2, wherein the first metal material is formed of a copper alloy, and the second metal material is formed of an iron-nickel alloy.
13. The semiconductor device according to claim 1.