JP3075680B2 - Semiconductor device and method of manufacturing 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 a semiconductor device for reducing damage to inner leads after inner lead bonding in a tape carrier package assembly process, and a method of manufacturing the semiconductor device.

[0002]

2. Description of the Related Art Conventionally, in the inner lead bonding process of a tape carrier package, a semiconductor chip and a tape carrier are joined as follows. That is, a bump is formed on a pad of a semiconductor chip with Au or Pb / Sn, and Sn,
An inner lead plated with Pb / Sn or Au or the like is brought into contact. Then, an alloy is precipitated by applying heat and a load, and the bump and the inner lead are joined.

As a method of applying heat and load to the contacted bumps and inner leads, there is a method of collective inner bonding (gang) in which all bumps and all inner leads are collectively bonded using a constant heat tool or a pulse heat tool. Bonding) or single point bonding for bonding a pair of bumps and inner leads.

FIG. 5 shows a batch inner lead bonding method using a constant heat tool. In FIG. 5, 1 is a bonding tool and 2 is a tape carrier.
Inner lead (hereinafter simply referred to as inner lead), 3
Is a bump formed on a pad (not shown) of the semiconductor chip 4, 6 is a tape carrier substrate, 7 is a tape guide, 8
Is a bend plate and 9 is a bonding stage.

After aligning the inner leads 2 with the bumps 3 of the semiconductor chip 4 set on the bonding stage 9, the heated bonding tool 1 is lowered to apply a temperature and a load to the contact point between the inner leads 2 and the bumps 3. Then, the bump 3 and the inner lead 2 are joined. At this time, the inner lead 2 is bent at an angle corresponding to the offset amount r between the inner lead 2 and the bump 3.

FIG. 2 shows a tool edge 1 of a bonding tool 1 by a conventional batch inner lead bonding method.
The outline of a is shown. The conventional bonding tool edge contour 10 is designed to coincide with a rectangular line circumscribing the bump 33 (corresponding to the bump 3 in FIG. 5), or to be positioned outside the above-mentioned line.

[0007] Japanese Patent Application Laid-Open No. 4-372144 and Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 82596 describes that a difference occurs in a portion of a thermocompression-bonded inner lead pressed by a bonding tool, and the difference reduces the strength of the inner lead. Therefore, Japanese Patent Laid-Open No. 5-8
In Japanese Patent No. 2596, the tip of the inner lead is folded back to make it thicker.

[0008]

However, in the above-described conventional inner lead bonding method, there is no problem when the eutectic alloy is not deposited, for example, when bonding Au plated inner leads to Au bumps. However, when the eutectic alloy is deposited, there are the following problems. First, when the above-mentioned batch inner lead bonding is performed using the bonding tool 1 designed to exhibit the bonding tool edge contour 10 in FIG. 2, there are the following problems.

FIG. 3 (b) shows a state after bonding when the package inner lead bonding is performed using the above-mentioned conventional bonding tool 1. If the tool edge 1a of the bonding tool 1 is on a rectangular line circumscribing the bump 3, a portion of the inner lead 2 which is relatively far from the bump 3 will also be heated. As a result, the deposited eutectic alloy 5 creeps upward along the lower surface of the inner lead 2 from the bump 3 side, and flows downward from above along the side surface of the bump 3 as shown in FIG. Such a mini scath is formed. On the other hand, an external force is applied to the inner lead 2 until the potting step after the inner lead bonding, and the inner lead 2
Can be somewhat displaced. At that time, the inner lead 2 is normally displaced from the outer edge of the bump (the inner lead neck portion) 11.

When bonding is performed by the conventional batch inner lead bonding method, a brittle eutectic alloy 5 exists at the displaced portion 11 and cracks are easily generated. Then, once the cracks 12 occur in the eutectic alloy 5, the cracks 12 grow large due to the notch effect, and in the worst case, there is a problem that the inner leads are disconnected.

[0011] Further, in the above-mentioned JP-A-4-372144 and JP-A-5-82596, there is no description of a plating layer and no description of precipitation of a eutectic alloy. However, if the inner leads are plated, as shown in FIG. 6, heat is also applied to the periphery of the pressing portion of the bonding tool during thermocompression bonding, so that the eutectic alloy 25 precipitates. However, the inner leads 22 are thermocompression-bonded horizontally to the semiconductor chip 24, and the bumps 2
Since the inner lead 22 is not bent on the top 3, the eutectic alloy 25 is applied to the inner lead 22 from the side surface of the bump 23.
Will be deposited over the lower surface of the substrate. Then, similarly to the above, there is a problem that cracks easily occur in the eutectic alloy 25 when an external force is applied to the inner leads 22.

Accordingly, an object of the present invention is to provide a semiconductor device capable of preventing the generation of an initial crack which causes disconnection of an inner lead by allowing a brittle eutectic alloy deposited at the time of inner lead bonding to exist only on the upper surface of a bump. An object of the present invention is to provide a method for manufacturing a semiconductor device.

[0013]

In order to achieve the above object, the invention according to claim 1 is to provide an inner lead made of a metal pattern formed on a film substrate on a bump formed on a semiconductor chip. A semiconductor device formed by thermocompression bonding, wherein a portion of the inner lead bonded on the bump is metal-plated and a predetermined distance inward from an outer end of the bump on the bump. And the predetermined distance is
The space between the eutectic alloy between the inner lead and the bump material and bump deposited upon thermocompression bonding the inner lead material, the inner lead and the bump upper surface formed on the bump by bending of the inner leads it is characterized in that is set to so that distances are <br/> held fall within the limits.

According to a second aspect of the present invention, in the semiconductor device according to the first aspect, the metal plating applied to the inner lead is one of Sn and Pb / Sn. Features.

[0015] The invention according to claim 3 is that, after the inner leads made of the metal pattern formed on the film substrate are aligned with the bumps formed on the semiconductor chip by a predetermined offset amount, In a method for manufacturing a semiconductor device for thermocompression bonding inner leads and bumps,
At the time of thermocompression bonding between the inner leads and the bumps, the bonding of the inner leads to the bumps is performed by using a bonding tool in which a tool edge is located at a position on the semiconductor chip that enters a predetermined distance inward from the outer end of the bumps. Was bent at a position where the predetermined distance was inserted inward from the outer end of the bump on the bump, and a eutectic alloy deposited during the thermocompression bonding was formed on the bump by bending the inner lead. So that it is held in the space between the inner lead and the top of the bump.
The predetermined distance at that time is
The joint held in the space between the
The distance is set so that the crystal alloy can be accommodated in the space .

[0016]

According to the first and second aspects of the present invention, the inner leads thermocompression-bonded on the bumps of the semiconductor chip are:
It is bent at a position on the bump that enters a predetermined distance inward from the outer end of the bump. The eutectic alloy of the bump material and the inner lead material precipitated during the thermocompression bonding is held in the space between the inner lead formed on the bump and the upper surface of the bump by bending the inner lead. ing. At that time, the predetermined distance
The above-mentioned eutectic alloy is
Distance within the space between the
Eutectic alloy deposited on the bump
Do not hang down to the side. Therefore, after the thermocompression bonding, it takes an external force to the inner lead upon displacement from the time outside the bumps, the inner lead, the van
As a result, the eutectic alloy is displaced from the outside of the eutectic alloy held and held in the upper surface of the metal alloy, so that no stress is applied to the brittle eutectic alloy and no crack occurs.

In the invention according to claim 3, the inner lead made of the metal pattern formed on the film base is aligned with the bump formed on the semiconductor chip by a predetermined offset amount. After that, a thermocompression bonding between the bumps and the inner leads is performed by using a bonding tool having a tool edge located at a position on the semiconductor chip that enters a predetermined distance inward from the outer end of the bumps. As a result, the inner lead bonded to the bump bends at a position on the bump at a predetermined distance from the outer end of the bump to the inside. The eutectic alloy deposited during the thermocompression bonding is held in the space between the inner lead formed on the bump and the upper surface of the bump by bending the inner lead. At that time, the predetermined distance is:
The eutectic alloy is on the bent inner leads and bumps
The distance must be such that it fits within the space between
Eutectic alloy deposited on the bump side
It does not hang down to the surface. Thus, a semiconductor device is formed in which the inner lead is displaced from the outside of the eutectic alloy when the inner lead is displaced from the outside of the bump due to an external force applied after the thermocompression bonding.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a partially enlarged view of the semiconductor device of the present embodiment, and shows a state in which inner lead bonding is performed by a bonding tool having an optimized bonding tool edge contour. In FIG. 1, 3
Reference numeral 1 denotes a bonding tool, 32 denotes a tape carrier inner lead (hereinafter, simply referred to as an inner lead), and 33 denotes a bump formed on a semiconductor chip 34.

A pad (not shown) is arranged around the periphery of the semiconductor chip 34 by about 100 μm from the outer peripheral end of the semiconductor chip 34, and a bump 33 having a size of 100 μm × 50 μm is formed of Au on the pad. ing. And
An inner lead 32 formed of a Cu foil having a thickness of about 15 μm and a width of about 35 μm on a film base 36 made of polyimide is offset from the bump 33 by an offset amount r = 50 μm.
The alignment is between m and 100 μm. At this time, the distance l between the end of the semiconductor chip 34 and the film substrate 36 is set to 100
It is about μm. The inner lead 32 has a thickness of 0.2.
Sn plating with a thickness of μm to 0.4 μm is applied.

As shown in FIG. 2, the bonding tool 31 used in the present embodiment has a tool edge 31a.
Is designed such that the outline 37 of each of them is 20 μm inside each side of a rectangular line circumscribing the bump 33. Then, by the bonding tool 31 having the above configuration, 1
The pressure per bump 33 is 20 gf to 40 gf, and the bonding is performed at a temperature of about 500 ° C.

As described above, the offset of the inner lead 32 with respect to the bump 33 is performed by using the bonding tool 31 designed such that the bonding tool edge contour 37 is located inside the rectangular line circumscribing the bump 33 by 20 μm on each side. The amount r is 50 μm to 100 μm
In the case where the above-described batch inner bonding is performed, as shown in FIG. 3A, the inner lead 32 is located at a position where the bonding tool edge contour 37 is located (a position 20 μm inward from the outer end of the bump 33). It bends toward the anti-semiconductor chip side at 39, and a space between the inner lead 32 and the bent portion 39 on the bump 33 is formed outside.

For this reason, the eutectic alloy 35 deposited during the above-described collective inner lead bonding is substantially contained in the space above the bump 33. In addition, eutectic alloy 3
The amount of precipitate 5 varies depending on the temperature, pressure, load time and the like during the inner bonding. Therefore, the amount of the eutectic alloy 35 deposited is controlled in the space by controlling the amount of displacement of the bonding tool edge contour 37 from the outer end of the bump 33 and the plating thickness according to the bonding conditions.

As described above, in the semiconductor device manufactured in this embodiment, the brittle eutectic alloy 35 that precipitates when the inner leads 32 are bonded to the Au bumps 33 of the semiconductor chip 34 by the inner bonding is formed only on the upper surfaces of the bumps 33. Exists. Therefore, as shown in FIG. 3A, when an external force is applied to the inner lead 32 and the outer lead 32 is displaced from the outer edge of the bump (the inner lead neck portion) 38 until the potting step after the inner lead bonding, Will be displaced from the outside of the crystal alloy 35. Therefore, no stress is applied to the brittle eutectic alloy 35, and no crack is generated in the eutectic alloy 35.

In this embodiment, the bump 3
The bump size of the bump 33 is increased by 20 μm inward from the conventional bump size so that the bonding area (bonding area) between the inner lead 3 and the inner lead 32 becomes equal to that of the conventional batch inner bonding. That is, assuming that a bonding area of 80 μm × 35 μm is conventionally required in terms of characteristics, the size of the bump 33 in this embodiment is changed from 80 μm × 50 μm to 100 μm ×
Change to 50 μm.

FIG. 4 shows the bonding tool edge contour position and the inner lead tensile strength after inner lead bonding (the inner lead bonding conditions are the same as those in the above embodiment, and only the bonding tool edge contour position is changed in three ways. ).
From FIG. 4, it was confirmed that the inner lead tensile strength was improved by shifting the bonding tool edge contour position inward with respect to the bump 33 and securing the deposition location of the eutectic alloy 35 on the upper surface of the bump 33. . When this embodiment was applied to an actual model, an improvement in inner lead tensile strength of about 1 gf / lead was observed.

In the above-described inner lead tensile strength test, the inner lead neck (displaced portion outside the bump) 11, which is most susceptible to damage due to a step formed by pressing the bonding tool 1, usually has a large number of breaks. However, when this embodiment was applied, most of the breakage occurred at the center of the inner lead 32. This indicates that by applying the present embodiment, the inner lead neck portion 39 where the step is generated is reinforced by the adhesion with the eutectic alloy 35, and the damage is reduced.

As described above, in the present embodiment, the position of the tool edge 31a at the time of the batch inner bonding is set so that the position of the tool edge 31a is on the inner side of the rectangular line circumscribing the bump 33 by 20 μm on each side. Offset amount r of 50 μm to 10
It is 0 μm. Therefore, the inner lead 32 is bent toward the anti-semiconductor chip side at a position of 20 μm inward from the outer end on the bump 33 by the inner lead bonding.
3 A space is created on the upper surface. Then, the eutectic alloy 35 deposited by inner lead bonding becomes bump 33
Fits in the space on the upper surface of. Therefore, even if an external force is applied to the inner lead 32 after the inner lead bonding, the inner lead 32 is displaced from the outside of the eutectic alloy 35, and no stress is applied to the brittle eutectic alloy 35, so that cracks occur in the eutectic alloy 35. do not do.

At this time, the bump size of the bump 33 is set to 20 μm inside the conventional bump size so that the bonding area (bonding area) between the bump 33 and the inner lead 32 becomes equal to the conventional one. It is expanding.
Therefore, a sufficient bonding area can be secured and the inner lead tensile strength can be improved.

In the above embodiment, the description has been given of the case of the batch inner bonding. However, even in the case of the single point bonding, the outline of the bonding tool edge and the outer end of the bump as shown in FIG. The same effect can be obtained by controlling the pressing position of the bonding tool so that the positional relationship is obtained. Further, it goes without saying that the materials and dimensions of the inner leads 32, the bumps 33, the film base material 36, and the like in the present invention are not limited to the above-described embodiment.

[0030]

As is apparent from the above description, in the semiconductor device according to the first and second aspects of the present invention, the inner leads thermocompression-bonded on the bumps of the semiconductor chip are formed from the outer ends of the bumps on the bumps. is bent by intruding position a predetermined distance inward, the predetermined distance is eutectic alloy deposited during the thermocompression bonding is, the inner lead and the bump upper surface formed on the bump by bending of the inner leads so that distances are maintained falls within the space between the
Because it is set in, it precipitated the eutectic alloy bump
Do not hang down to the side. Therefore, the above thermocompression bonding
After, when displaced from the time the outside bump applied external force to the inner lead, inner lead, on the bump
Displaced from the outside of the eutectic alloy held and held in the plane . That is, according to the present invention, no stress is applied to the brittle eutectic alloy, and it is possible to prevent the generation of micro cracks in the eutectic alloy, thereby preventing the micro cracks from growing and leading to disconnection of the inner lead.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: using a bonding tool having a tool edge positioned at a predetermined distance inward from an outer end of a bump on a semiconductor chip; Since the thermocompression bonding is performed on the bumps and the inner leads that have been aligned with the offset amount, the inner leads bonded to the bumps enter the inside of the outer ends of the bumps by a predetermined distance on the bumps. The eutectic alloy that bends at an elliptical position and precipitates during the thermocompression bonding is held in the space between the inner lead formed on the bump and the upper surface of the bump by the bending of the inner lead. So
At the time, the predetermined distance, the eutectic alloy is bent
Fit in the space between the inner lead and the top of the bump
Because the distance is set to be maintained,
The eutectic alloy does not hang down to the side of the bump. Therefore, the semiconductor device manufactured by the present invention is:
Even if external force is applied to the inner lead after thermocompression bonding and the outer lead is displaced from the outside of the bump, the inner lead is displaced from the outside of the eutectic alloy because the brittle eutectic alloy is precipitated only on the upper surface of the bump. Become. As a result, no stress is applied to the eutectic alloy, and no microcracks are generated, and the microcracks can be prevented from growing and leading to disconnection.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view of a semiconductor device of the present invention,
FIG. 4 is a diagram showing an example of a positional relationship between a tool edge of a bonding tool and a bump at the time of inner lead bonding in the method of manufacturing a semiconductor device according to the present invention.

FIG. 2 is a comparison diagram of a bonding tool edge profile in FIG. 1 and a conventional bonding tool edge profile.

FIG. 3 is a diagram showing a relationship between a positional relationship between a tool edge and a bump, a state of generation of a eutectic alloy by inner lead bonding, and a state of a eutectic alloy when the inner lead is displaced.

FIG. 4 is a diagram showing a relationship between a bonding tool edge contour position and an inner lead tensile strength after collective inner lead bonding.

FIG. 5 is a side view of a bonding tool and a semiconductor chip in a conventional batch inner lead bonding.

FIG. 6 is an enlarged view of an inner lead and a bump joined by a conventional inner lead bonding method different from that of FIG. 5;

[Explanation of symbols]

31 bonding tool, 32 inner lead, 33 bump, 34 semiconductor chip, 35 eutectic alloy, 36
Film substrate, 37: bonding tool edge contour.

Claims (3)

(57) [Claims] 1. A bump formed on a semiconductor chip,
A semiconductor device formed by thermocompression bonding of an inner lead made of a metal pattern formed on a film substrate, wherein the portion of the inner lead joined on the bump is metal-plated. The bump is bent at a position inside the outer end of the bump by a predetermined distance on the bump, and the predetermined distance is a distance between the bump material and the inner lead material deposited when the inner lead and the bump are thermocompressed. eutectic alloy, Ru space <br/> is set to so that distances are maintained falls within between the inner lead and the bump upper surface formed on the bump by bending of the inner leads with A semiconductor device characterized by the above-mentioned. 2. The semiconductor device according to claim 1, wherein the metal plating applied to the inner lead is one of Sn and Pb / Sn. 3. After positioning an inner lead made of a metal pattern formed on a film base material with a predetermined offset amount with respect to a bump formed on a semiconductor chip, the inner lead and the bump are thermocompression-bonded. In the method of manufacturing a semiconductor device, the thermocompression bonding between the inner leads and the bumps is performed by using a bonding tool in which a tool edge is positioned at a predetermined distance from the outer end of the bump to the inside on the semiconductor chip. The inner lead bonded to the bump is bent at a position on the bump from the outer end of the bump to the inside from the outer end of the bump by the predetermined distance, and the eutectic alloy deposited during the thermocompression bonding is bent at the inner lead. by and held in the space between the inner lead and the bump upper surface formed on the bump Yo
In that case, the predetermined distance at that time, the inner lead and the
The eutectic alloy held in the space between the bump
A method of manufacturing a semiconductor device, wherein the distance is set so as to fit in a space .