JP2002368040A - Method of manufacturing semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor, in which inner leads are bonded collectively so as to shorten the time required for bonding per package and in which the excessive deformation of the inner leads can be reduced. SOLUTION: In an ILB process, a chip which is equipped with an external connecting terminal and a TAB tape are aligned on a bonder, a plurality of inner leads at the TAB tape are pressed down by a bonding tool, and the inner leads and pads are bonded collectively by a thermocompression bonding method jointly using ultrasonic waves. When leads are insufficient with reference to the number of prescribed collectively bonded inner leads, a collectively bonded pair is formed of the bonded inner leads and unbonded inner leads, and bonding is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device in which an inner lead is bonded to an electrode pad of a semiconductor element, and more particularly to a method of manufacturing a semiconductor device in which a plurality of inner leads are simultaneously pressed by a bonding tool. .

[0002]

2. Description of the Related Art In recent years, the importance of mounting technology on semiconductor devices has increased with the increasing functionality and integration of devices. Its importance is growing. TAB (Ta
(pe Automated Bonding) technology
It has been applied as a technology that can connect inner leads to input / output terminals of a semiconductor device at a narrow pitch by an ILB (Inner Lead Bonding) process.

In the current general TAB technology, it is common to form a gold bump on an electrode pad of a semiconductor chip or on an inner lead, and to obtain a bond between the two via this. However, the formation of the gold bump has disadvantages such as an increase in assembly cost and a long construction period. As a technique for solving this problem, a bumpless ILB method in which a bump forming step is omitted has been proposed.

FIGS. 9a and 9b show a bumpless ILB.
1 schematically shows a form of bonding by a method. Insert the inner lead 1 of the TAB tape into the semiconductor chip 2
A single point bonder capable of ultrasonic bonding is used as the ILB tool 4, and ultrasonic waves are applied to the ILB tool while pressing the leads one by one. Are directly joined by an ultrasonic combined thermocompression bonding method. Although bump formation is not required, the number of inner leads increases with an increase in the number of input / output terminals of the device, and there has been a problem that the bonding time per package increases and productivity decreases.

In the semi-gang system in which a plurality of inner leads 1 are pressed together and bonded to an aluminum pad 3, the bonding is performed under the same bonding conditions regardless of the number of pressing leads at the time of bonding. Lead 1
The bonding conditions are set for each of the numbers. Alternatively, when forming a pair of inner leads 1 that are to be joined together, a tape is designed so that the inner leads 1 do not run short.

However, when bonding is performed under the same conditions irrespective of the number of inner leads 1 to be pressed, if the number of inner leads 1 to be pressed collectively is different, the load per inner lead 1 is different. Excessive deformation occurred, and there was a possibility that a short between leads and a decrease in lead neck strength occurred. In addition, deciding the load and the ultrasonic setting for each number of batches to be pressed collectively complicates the operation. Further, when a dummy lead is used to form a pair of inner leads 1 that are pressed together, there is a problem that the degree of freedom in designing a TAB tape is limited.

On the other hand, an inner lead 1 and an aluminum pad 3
As another means for bonding, there is a method in which all the inner leads 1 are collectively bonded by gang bonding. However, high precision flatness is required for a bonding tool, and adjustment thereof is difficult.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention is intended to reduce the time required for bonding per package by bonding inner leads at once and to excessively deform the inner leads. It is an object of the present invention to provide a semiconductor manufacturing method capable of reducing the number of semiconductor devices.

[0008]

According to a method of manufacturing a semiconductor device of the present invention, a plurality of inner leads are collectively pressed by a bonding tool onto a semiconductor element having a plurality of connection electrode pads. In the method of manufacturing a semiconductor device, the method includes a step of simultaneously and simultaneously pressing the bonded inner lead and the unbonded inner lead by the bonding tool.

By pressing the joined inner leads together with the unjoined inner leads again, the load applied to the bonding tool at the time of pressing can be changed without any change.
It is possible to equalize the load per inner lead, so even if the number of unjoined inner leads is less than the set number of presses at one time, it suppresses excessive deformation of the inner lead due to variation in load It is possible to Therefore, a short circuit of the inner lead caused by excessive deformation of the inner lead can be prevented, and the pitch of the electrode pads can be reduced, so that the size of the semiconductor package can be reduced.

In the semiconductor manufacturing method according to the present invention for solving the above-mentioned problem, the number of the inner leads simultaneously pressed by the bonding tool in a single pressing step is always the same. .

Since the number of inner leads to be pressed is always the same, the load applied to each inner lead can be kept constant without changing the load applied to the bonding tool. Even when the number of inner leads is less than the set number of presses at one time,
It is possible to suppress excessive deformation of the inner lead due to variation in load. Therefore, a short circuit of the inner lead caused by excessive deformation of the inner lead can be prevented, and the pitch of the electrode pads can be reduced, so that the size of the semiconductor package can be reduced.

Further, a method of manufacturing a semiconductor device according to the present invention for solving the above problem is characterized in that the inner leads are supplied to the connection electrode pads by a TAB tape including a plurality of the inner leads. I do.

By supplying the inner leads with a TAB tape, it is possible to easily supply the inner leads according to the semiconductor element, and it is possible to flexibly cope with the diversification of products.

Further, in the method of manufacturing a semiconductor device according to the present invention for solving the above-mentioned problems, a bottom surface of the bonding tool for pressing the inner lead is rectangular.

By pressing with a bonding tool having a rectangular bottom shape, the number of inner leads that can be pressed and joined at once is increased, and the time required for bonding can be shortened. . This makes it possible to reduce the time of the entire manufacturing process, thereby reducing the manufacturing cost.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, wherein the bonding tool is rotated in accordance with the arrangement of the connection electrode pads.

By rotating the bonding tool in accordance with the arrangement direction of the electrode pads, the direction in which ultrasonic waves or heat is applied to the bonding tool and the direction of the inner leads can be made to coincide with each other. It is possible to perform joining without affecting the anisotropy that occurs on the inner leads. Therefore, the inner leads can be uniformly joined to all the electrode pads without rotating the semiconductor element.

Further, according to the present invention, there is provided a method of manufacturing a semiconductor device, comprising: bonding an inner lead to the connection electrode pad by the bonding tool; Crimping method,
It is characterized in that any one of the eutectic bonding methods is used.

In the method of manufacturing a semiconductor device according to any one of the first to fifth aspects, since the excessive deformation can be reduced without depending on the bonding method used for bonding the electrode pad and the inner lead, a desired semiconductor device is desired. By selecting a bonding method that is optimal for the shape and characteristics of the semiconductor device, a manufacturing method suitable for manufacturing cost, manufacturing time, and bonding reliability can be obtained.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

FIG. 1A shows the principle of the semi-gang ILB method using a single point bonder. By using a bonding tool having a square bottom surface, the same bonding area can be obtained on each side of the chip. In this case, the number of leads that can be joined together is limited by the pad size. In order to avoid this restriction, as shown in FIG. 1B, by providing the bottom surface with a rectangular shape and providing a rotation mechanism in the bond head, the ILB tool 4 can be bonded to the shape of the bonding area to perform bonding. This makes it possible to increase the number of collective bonding leads and to design a tool corresponding to a reduction in the pad opening length.

The rotation of the bond head increases the degree of freedom in tool design, and also affects the bondability. In the non-rotating head shown in FIG. 1 a, the direction of the ultrasonic wave applied to obtain the joint was constant regardless of the direction of the inner lead 1. Therefore, when the amplitude direction of the ILB tool 4 caused by the ultrasonic wave becomes perpendicular to the inner lead 1, the width of the rolled inner lead 1 tends to increase at the joint. On the other hand, in the rotating head shown in FIG.
Since ultrasonic waves can always be applied in parallel with the inner lead 1, it is possible to suppress excessive deformation of the joint.

FIG. 2 shows the bonding strength and the SEM (Scanning) obtained by measuring the inner lead width of the bonding portion and the tensile strength of the inner lead in each direction in which ultrasonic waves are applied.
Electron Microscopy photograph is shown. When ultrasonic waves are applied perpendicularly to the inner lead, the inner lead 1 is excessively deformed and the width is 16.6 μm.
m to 19.8 μm, and the joint strength with the aluminum pad 3 is reduced from 5.6 gf to 4.6 gf accordingly.

Pad opening length 40 μm × 60 μm (50 μm
m pad pitch) 10
The bonding property was evaluated when the inner leads were bonded together. The bonding time per lead at this time was 20 msec. FIG. 3 shows the measured values of the lead width, the lead height, and the bonding strength. There is no significant difference in the joint lead shape and joint strength, and the joint strength is on average 5.
It was confirmed that about 5 gf was obtained. Here, the ultrasonic bonding thermocompression bonding method has been exemplified as a method for bonding the inner lead 1 and the aluminum pad. However, only ultrasonic bonding, only the thermocompression bonding method, or a eutectic bonding method may be used.

As shown in FIG. 4, when there is an empty pad having no lead, the number of leads connected simultaneously is less than the target number, and the load applied per lead increases. It is conceivable that short defects may occur due to excessive deformation of the leads. As shown in FIG. 5, there was no significant difference in lead deformation state and bonding strength for up to two empty pads with respect to batch bonding of six leads, but the lead width tended to increase with an increase in empty pads. Observed.

As a means for compensating for the insufficient lead at the time of collective joining and preventing the lead from being excessively deformed, a double press shown in FIG. The lead pressed only by the first press is a normal bonding lead, and the lead pressed by the first and second presses is
The twice-pressed lead and the lead pressed only by the second press are referred to as the twice-pressed adjacent lead.

FIG. 7 shows the results of evaluation of the normal bonding, the double press, and the double press adjacent lead. All leads have a lead width of about 17.0 μm and a lead thickness of 14.6 μm
And the bonding strength was about 6.0 gf, and there was no significant difference in the lead shape and bonding strength between the normal bonding and the twice pressed part and the adjacent part pressed twice, and it was confirmed that uniform bonding was obtained. Was.

Since the bonding time can be reduced by increasing the number of leads that can be joined together, productivity is expected to be improved. FIG. 8 shows a comparison of the bonding time per package in a package having a pad pitch of 50 μm and a number of inner leads of 580. The bonding time per package at the time of 10-lead batch bonding was 11.8 sec, and it was confirmed that the bonding time could be significantly reduced by using multi-lead ILB.

From these results, it was confirmed that uniform joining could be obtained without adding leads for batch joining lead number matching.
It can be seen that the LB method has high versatility. In addition, it can be seen that this connection technology enables high-speed bonding of 20 msec per lead.

[0030]

According to the present invention, when the number of leads is insufficient for forming a collective bonding pair, a collective bonding pair is formed by a bonded lead and an unbonded lead, so that an applicable load per lead can be obtained without using a dummy lead for forming a pair. Can be joined under uniform conditions. In addition, since the number of collectively joined leads is uniform due to the bonded leads, the load per lead is constant, and it is not necessary to set conditions for each bonding point. In addition, the bonding tool used in the present invention has a smaller pressing portion area as compared with a tool used for gang bonding in which all leads are joined together, so that tool parallel adjustment becomes easier.

By pressing the joined inner leads again with the unjoined inner leads, the load applied to the bonding tool at the time of pressing can be changed.
It is possible to equalize the load per inner lead, so even if the number of unjoined inner leads is less than the set number of presses at one time, it suppresses excessive deformation of the inner lead due to variation in load It is possible to Therefore, it is possible to prevent the inner leads from being short-circuited due to the excessive deformation of the inner leads, and to reduce the pitch of the electrode pads, thereby making it possible to reduce the size of the semiconductor package.

By supplying the inner leads with a TAB tape, the inner leads can be supplied easily according to the semiconductor element, and it is possible to flexibly cope with the diversification of products. In addition, by pressing with a bonding tool having a rectangular bottom shape, the number of inner leads that can be pressed and joined at once is increased, and the time required for bonding can be reduced. This makes it possible to reduce the time of the entire manufacturing process, thereby reducing the manufacturing cost.

By rotating the bonding tool in accordance with the arrangement direction of the electrode pads, the direction in which ultrasonic waves or heat are applied to the bonding tool and the direction of the inner leads can be made to coincide with each other. It is possible to perform joining without affecting the anisotropy that occurs on the inner leads. Therefore, the inner leads can be uniformly joined to all the electrode pads without rotating the semiconductor element.

In the semiconductor manufacturing method according to the first to fifth aspects, since the excessive deformation can be reduced without depending on the bonding method used for bonding the electrode pad and the inner lead, a desired semiconductor device can be obtained. By selecting a bonding method that is optimal for the shape and characteristics of the semiconductor device, a manufacturing method suitable for manufacturing cost, manufacturing time, and bonding reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram of a semi-gang ILB method using a single point bonder.

FIG. 2 Inner lead width, bonding strength, SEM of a bonding portion
Photo

FIG. 3 Measured values of lead width, lead height, and bonding strength

FIG. 4 is a diagram showing the occurrence of excessive deformation when an empty pad exists.

FIG. 5 shows measured values of bonding strength and lead width when an empty pad exists.

FIG. 6 is a diagram schematically showing a double press.

FIG. 7 shows evaluation results of normal bonding, double pressing and double pressing adjacent leads.

FIG. 8 is a graph showing a comparison of bonding time per package.

FIG. 9 is a diagram schematically showing conventional bumpless ILB bonding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner lead 2 ... Semiconductor chip 3 ... Aluminum pad 4 ... ILB (bonding) tool

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshio Kasuga 5-7-1 Shiba, Minato-ku, Tokyo F-term in NEC Corporation 5F044 NN01

Claims (6)

[Claims] 1. A method for manufacturing a semiconductor device, comprising: bonding a plurality of inner leads to a semiconductor element having a plurality of connection electrode pads by pressing a plurality of inner leads collectively with a bonding tool. Simultaneously and collectively pressing with the bonding tool. 2. The semiconductor manufacturing method according to claim 1, wherein the number of the inner leads pressed simultaneously by the bonding tool in one pressing step is always the same. 3. The semiconductor device according to claim 1, wherein the inner leads are supplied to the connection electrode pads by a TAB tape including a plurality of the inner leads. Method. 4. The method according to claim 1, wherein a bottom surface of the bonding tool for pressing the inner lead is rectangular. 5. The method according to claim 4, wherein the bonding tool is rotated in accordance with the arrangement of the connection electrode pads. 6. An ultrasonic method, a thermocompression bonding method, a thermocompression bonding method using ultrasonic waves, or a eutectic bonding method is used for bonding the inner leads to the connection electrode pads by the bonding tool. The method of manufacturing a semiconductor device according to claim 1, wherein: