JPH04251948A - Manufacture of semiconductor - Google Patents

Abstract

PURPOSE:To provide a wire bonding method which reduces the wiring height and shows no directionality, particularly, a bonding method which facilitates automation by wire bonding out of operations an automatic boards can make. CONSTITUTION:A ball bonder is used to perform bonding with no balls created. A tip of a wire 4 is passed though a capillary tool 6 and a clamper 7 together are lowered to make the wire tip strike one of mounting boards 1, and then the capillary tool 6 is lowered with the wire 4 keeping on moving in a wiring direction, thereby bonding the wire 4 and compression-bonding it to a semiconductor chip 3.

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 by wire bonding a semiconductor chip and a substrate package (hereinafter referred to as a substrate) on which the semiconductor chip is mounted. As semiconductor chips become smaller and more highly integrated, the number of wires increases and the distance between the wires becomes narrower. Furthermore, in order to miniaturize the entire device, it is necessary to reduce the space occupied by the wires.

0002

2. Description of the Related Art Conventionally, there are ball bonding and wedge bonding as wire bonding methods for semiconductor devices.

The former is shown in FIGS. 10 and 11. In the figure, 1 is a substrate, 2 is a brazing material, 3 is a semiconductor chip, 4 is a wire,
5 is a bump attached to the connection portion with the semiconductor chip, 6 is a capillary, and 7 is a clamper.

In the ball bonding method, a wire 4 such as an Au wire is passed through a through hole 6a passing through the center of a capillary tool 6, the tip of the wire is heated and softened to form a ball 8, and the ball 8 is bonded to a semiconductor by the capillary tool 6. Press onto chip 3. The bump 5 formed by pressure bonding has a height of about 90 microns. After crimping the ball, move the capillary tool 6 in the wiring direction to the connection position with the substrate 1, lower the capillary tool 6,
As a result, the wire and the substrate 1 are crimped, and then, while the capillary tool 6 is stopped, the wire 4 is held between the clampers 7 and pulled, thereby cutting the wire 4.

[0005] In the ball bonding method, since the wire 4 extends almost vertically from the bump 5, it has a 360°
Although the wires 4 can be drawn out and wired in any direction, the ball is large and the wiring height is high, so there is a drawback that the semiconductor device cannot be miniaturized.

The latter wedge bonding method is shown in FIG.

The wedge bonding method is shown in FIG.
), the wire 4 is guided along the side of the side tapered part 11a of the wedge tool 11 (see (b)), or it is guided through the through hole of the wedge tool 11, and the wire 4 is connected to the connection part of the substrate 1 or the semiconductor chip 3. Thermocompression bonding or ultrasonic and heat crimping. The wire 4 is crimped while being stretched laterally.

In the wedge bonding method, the wire 4
Since the wire 4 extends almost horizontally, the wire 4 can only be pulled out in the direction in which it extends (in the direction of the solid arrow in Fig. 12).When wiring in the opposite direction, rotate the part to be processed and then pull out the wire 4. need to be brought out. In other words, wedge bonding has a wiring directionality that allows high-speed wiring to be performed in a fixed direction. However, the wedge bonding method has the advantage that the wire height HB can be reduced because the wire 4 is crimped in a horizontal direction.

[0009]

[Problems to be Solved by the Invention] Therefore, as a bonder, ball bonding is applied for general low-cost products, and for products with a small bonding area, bonding speed is sacrificed and the complexity of the bonding equipment is not required. However, wedge bonding is still used.

In other words, it can be said that if a wedge bonding method without directionality can be realized, the wiring height can be reduced and high-speed wiring can be performed. Among these, the reduction in wiring height was achieved by devising the structure of the ball bonder, as shown in Figure 13, by applying a ball forming tool to the wire 4 instead of using a capillary tool 6 through which the wire 4 passes through the center to form a ball. Therefore, if you bend the capillary tool 90 degrees from the tip and crimp the wire and the mating material in this state ((a)
)) is possible. However, the wiring direction can only be realized on the side opposite to the bending direction (see FIG. 13(c)), and if the wiring is placed on the bending direction side (see FIG. 13(b)), the wire 4
Cracks 4a may appear in the substrate 1, or the wires 4 may come off the substrate 1, making wiring difficult.

[0011] In order to avoid such problems, it is necessary to
To avoid bending and wiring as in 3.(a), (b)
When the capillary tool moves upward (x), the planar motion draws an arc as shown in FIG. 13(d), and the wire 4
It was necessary to control the bending direction, such as preventing bending with a small radius of curvature, which could be achieved with manual machines, but was not possible with automatic machines.

The present invention is a wire bonding method that reduces the wiring height and has no directionality, and in particular, a bonding method that can be easily automated by bending the wire in an operation that is possible with an automatic bonding machine. The purpose is to provide a method.

[0013]

According to the present invention, the tip of the wire is passed through a capillary tool, the capillary tool is lowered, the tip of the wire is applied to one of the package substrate or the semiconductor chip, and then the wire is moved in the wiring direction. further lowering the capillary tool while moving the wire, stopping the movement in the wiring direction before the wire is crimped, and lowering the capillary tool,
After completing the crimping of the wire and the package substrate or the semiconductor chip, the capillary tool is moved in the direction of the wiring, rising to a predetermined height and then lowering, and crimping the wire to the other of the package substrate or the semiconductor chip. A semiconductor device is manufactured through the process of crimping using a capillary tool and lifting the capillary tool to cut the wire.

[0014]

According to the present invention, first, the tip of the wire is passed through the capillary tool, the capillary tool is lowered, and the tip of the wire is brought into contact with either the package substrate or the semiconductor chip. At this stage, no ball is formed at the tip of the wire, which would increase the height of the wire. Further, the wire is held by a clamper so that the wire can be bent at a predetermined position when bringing the wire into contact with a substrate or the like.

Next, the capillary tool is further lowered while moving the wire in the wiring direction, and before the wire is crimped, the capillary tool stops moving in the wiring direction and releases the wire from the clamper. At this stage, the wire is not yet crimped. Therefore, since the wire is not metallurgically or mechanically bonded to the substrate etc., the wire is
The wire can be moved in the desired wiring direction by taking advantage of the fact that the direction can be changed by 0 degrees. That is, in the present invention, if the positions of the external wiring of the substrate to be wired and the pads of the semiconductor chip are stored in the automatic bonding machine, the moving direction and moving distance are automatically determined.

In order to determine the starting position of the wiring, the capillary tools are moved in the wiring direction while being lowered. Then, the wire is pulled out in the wiring direction while remaining at the position where the tip first contacted the substrate or the like.

As the capillary tool descends, mechanical or metallurgical bonding between the wire and the substrate progresses. By stopping the movement in the wiring direction before the bond is completed, shear stress is prevented from being applied to the bond, and the bond is completed with pressure only in the vertical direction, making the bond sound. During crimping, it is necessary to release the wire from the clamper and lower the capillary tool to avoid applying unnecessary stress to the wire. The wire and the metallized wiring on the substrate can be crimped two or more times.

Subsequently, the capillary tool and the clamper are moved in the direction of the wiring, raised to a predetermined height and then lowered, the wire is crimped to the other side of the package substrate or the semiconductor chip using the capillary tool, and then the clamper is moved. When closed, the capillary tool rises and cuts the wire to perform wire bonding. This step is the same operation as normal wedge bonding processing, and can achieve a low wiring height.

The above processing operations can be completely automated.

The method according to claim 2 is different from the method according to claim 1 in that the wire is crimped onto the other side of the package substrate or the semiconductor chip using a capillary tool, and then the capillary tool is raised by a predetermined amount. Close the clamper provided above the tool, raise the entire capillary tool and clamper, and cut the wire. In this method, the amount of heat applied from the capillary tool to the semiconductor chip can be adjusted by adjusting the contact time between the capillary tool and the semiconductor chip.

The method according to claim 3 comprises the method according to claim 1, and
The method of claim 1 is the same as the method of claim 1 in that the method of clamping when the tip of the wire comes into contact with the board is different, and a series of processing is performed, such as releasing the clamp immediately before that and then moving the wire in the wiring direction. be. When joining a wire to a substrate, etc., it is not always necessary to hold the wire with a clamp; instead, unnecessary tensile stress is added between the clamper and the wire tip, and if heat from the capillary tool is applied to the wire tip, the wire may break. Since these stresses and heat transfer may cause permanent deformation, it may be preferable not to clamp while metallurgical crimping is proceeding.

[0022] In claim 4, a normal ball bonder is used,
This involves creating a computer program that performs the operations described above. In this case, the amount of wire fed out from the capillary tool should be long enough to be crimped on the side of the tip of the tool, omit heating to make a ball, and use the clamper installed on the top of the capillary tool to hold down the wire just enough to prevent it from returning when wiring. While moving in the desired direction, it is lowered, and even if the tip of the wire touches the substrate, it continues to move and descend. The tip of the wire must be bent and crimped in the opposite direction to the wiring direction. After crimping or just before crimping, release the clamper, raise the capillary tool, move it the required length, and lower it again to crimp and finish the wiring. After finishing, close the clamper, go up, and cut the wire from the crimped part. Only the clamper descends a certain amount and the wire is fed out from the capillary.

[0023]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 9.

When wiring the Au-plated inner leads of the substrate 1 (ceramic package) and the electrodes on the chip 3, the length L1 of the Au wire 4 drawn out is usually 1
It is mm. Since it is easier to bend this length L1 if it is longer, the first bonding (bending) was done on the inner lead side (see FIGS. 1 and 2). The distance between the capillary tool 6 and the clamper 7 does not particularly affect processing operations and is usually 10 m.
It is m.

In order to improve the bonding of the extended portion, it is crimped twice as shown in FIG. 9, and then wired onto the chip. In this case, after the first crimping, the capillary tool 6 is raised by about 100 microns, moved by about several 100 microns in the wiring direction, and lowered again to perform crimping.

As shown in FIG. 3, bonding is performed only by thermocompression bonding (
(approximately 300℃), combined with ultrasound, or only ultrasound
U-wires can be spliced similarly. Moreover, the entire operation beyond wiring one wire is completed in about 0.18 seconds.

In FIG. 4, the capillary tool 6 is moved together with the clamper 7 while lowering the height of the wire 4 to a position very close to the edge of the chip 3. In reality, it is necessary to provide a specified distance (several microns) between the chips to prevent short circuits. However, in the case of ball bonding, the diameter of the ball is 3d relative to the wire diameter (d), so considering that the height is higher than that, the wiring height is extremely low in the present invention.

In FIG. 5, the wire 4 is crimped onto the semiconductor chip 3. In the case of a ball, a crimp width of 3 d or more is required, but in the present invention, a practical level of strength was obtained even with a crimping width of 2 d or less.

The clamper bar 16 is attracted by the electromagnet 17 shown in FIG. 8 to sandwich the wire 4 between the clamper heads 15, and the clamper 7 is pulled up to cut the wire 4 as shown in FIG. 18 in FIG. 8 is a spring.

[0030] Bonding to the semiconductor chip 3 may be performed first, and then bonding to the substrate 1 may be performed.

[0031]

[Effects of the Invention] According to the present invention, a high-speed bonder that does not require a rotating mechanism can be used for products for which conventionally only the wedge method could be used.

[0032] With wedges, wire positioning is important and the bonder mechanism is complicated, but in the present invention, this complexity is avoided by using a capillary tool.

According to the present invention, the wire height can be reduced, making it possible to make the semiconductor device smaller and thinner, and it is also advantageous in terms of high frequency characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating wire feeding in an embodiment of the present invention.

FIG. 2 is a diagram illustrating the downward movement of a wire clamp and a capillary tool in an embodiment of the present invention.

FIG. 3 is a diagram illustrating crimping between a wire and a substrate in an embodiment of the present invention.

FIG. 4 is a diagram illustrating movement of the capillary tool in the wiring direction in the embodiment of the present invention.

FIG. 5 is a diagram illustrating crimping of a wire and a semiconductor chip in an embodiment of the present invention.

FIG. 6 is a diagram illustrating cutting of a wire in an embodiment of the present invention.

FIG. 7 is a diagram illustrating a time chart of operations of a clamper and a capillary tool in an embodiment of the present invention.

FIG. 8 is a diagram illustrating the structure of a clamper.

FIG. 9 is a plan view of a wire that has been crimped twice.

FIG. 10 is an explanatory diagram of a ball bonding method.

FIG. 11 is an explanatory diagram of a capillary tool and wire.

FIG. 12 is an explanatory diagram of a wedge bonding method.

FIG. 13 is an explanatory diagram of a wire bonding method according to a comparative example in which a wire is bent by 90 degrees using a capillary tool.

[Explanation of symbols]

1 Board (package board) 2 Brazing filler metal 3 Semiconductor chip 4 Wire 6 Capillary tool 7 Clamper 11 Wedge tool

Claims (4)

[Claims] Claim 1: Passing the tip of the wire through the capillary tool, lowering the capillary tool, and applying the tip of the wire to one of the package substrate or the semiconductor chip, and then lowering the capillary tool further while moving the wire in the wiring direction. the movement in the wiring direction before the wire is crimped, the capillary tool is lowered to complete the crimping of the wire to the package substrate or the semiconductor chip, and then the capillary tool is moved to the wiring direction. While moving in the direction, the capillary tool rises to a predetermined height and then falls, crimps the wire to the other side of the package substrate or the semiconductor chip using a capillary tool, and the capillary tool rises to cut the wire. A method for manufacturing a semiconductor device. 2. The method according to claim 1, after the wire is crimped to the other of the package substrate or the semiconductor chip using a capillary tool, the capillary tool is raised by a predetermined amount, and then a A method for manufacturing a semiconductor device, which comprises holding a wire with a clamper, raising the entire capillary tool and clamper, and cutting the wire. 3. In the method according to claim 1, the tip of the wire is passed through the capillary tool, and the entire capillary tool and clamper are lowered while holding the wire with a clamper provided above the capillary tool, so that the tip of the wire is A method for manufacturing a semiconductor device in which a clamper is released just before it hits one of a package substrate or a semiconductor chip, the capillary tool is then further lowered while moving the wire in the wiring direction, and the wire is then crimped. 4. A method for manufacturing a semiconductor device, in which the method according to claim 1 is carried out using a common ball bonder.