JPS611033A - Bonding method - Google Patents

Abstract

PURPOSE:To improve the positioning accuracy and the working efficiency by emitting the light of a spot light from directly above a chip, and equalizing the distance between the two electrodes of the chip and the distance between the vertical axis of the light and the axis of a tool. CONSTITUTION:A spot light 3 is mounted at a vertical position from the surface of a chip 2, and a bonding tool 1 is mounted at the position separated at the prescribed distance from the bonding surface. With this construction, even if the height of the chip 2 is irregular, no error occurs in positioning. Further, the distance between the first electrode 15 and the second electrode 15 of the chip 2 becomes equal to the distance 11. Thus, when the light of the light 3 is emitted to the electrode 15, the tool 1 can be positioned directly above the electrode 16, and the motions of forward and backward movements of the tool between the electrodes 15 and 16 can be omitted, thereby improving the positioning accuracy and the working efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for assembling microelectronic devices such as semiconductor integrated circuits. Contains information on bonding methods for connection.

In the field of semiconductor integrated circuits, labor costs have been rising sharply recently, and eliminating work that requires labor has become an important problem to be solved.

In particular, the labor-saving process of the so-called honding process, which involves mounting chip electrodes and external lead metals, is attracting a great deal of attention.

The bonding equipment for wire bonding (hereinafter referred to as bonder), which is also the mainstream in this bonding process, also uses microcomputers to position only the first starting point instead of the conventional manual work. Things that can be bonded automatically have become commonplace.

These so-called automatic bonders irradiate a starting electrode of a chip with light sound from a minute point irradiation device (hereinafter referred to as a spotlight) for positioning the initial starting point. These spotlights were created using the Bonde Ink tool (
The position of the drop point of the tool and the irradiation position of the spotlight are made to match so that there is no deviation when the tool (hereinafter referred to as the tool) is bonded to the chip electrode.

At this time, in order to place the tool in conventional automatic bonding just above the electrode to be bonded, the spotlight has to be tilted several times with respect to the tool that is perpendicular to the chip. Therefore, even if the operator determines that the height of the 4L tip is uneven and the operator has positioned it using the spotlight, the tool and spotlight are actually shifted by the amount of the height variation. It shows the position.

In general, with an automatic bonder, a sensor attached to the bonder detects the amount of deviation in the mounting position of the chip during initial positioning, and based on that detected amount, a correction formula is used.
The output value obtained by the calculation is such that correct bonding can be performed even at the above-mentioned mount position.

However, as mentioned above, since the detection amount is calculated based on the amount of deviation from the actual tool, there is a problem that bonding errors occur with the electrodes on the actual chip. In order to increase the number of chips, the chip area is made as unsophisticated as possible, and the electrodes of the chips are also inevitably small.9 Even the slightest bonding misalignment often causes defects.

In addition, the ultrasonic (hereinafter referred to as US) automatic bonder uses heat and pressure toleration (hereinafter referred to as US).
(hereinafter referred to as NTC) Compared to an automatic bonder, mechanically rotating elements are introduced, so the bonding f# degree is disadvantageous. In addition, the applicable elements of this US bonding are ceramic and glass type packages (C case). These devices have disadvantages such as large variations in the height of the package itself and a large misalignment between the spotlight and the actual tool mentioned above, which is one of the reasons why the automation of US bonders has been slow. It has also become

Therefore, the purpose of the present invention is to solve these problems by correctly recognizing the tool position even when there is variation in the height of the chip during bonding, regardless of the package type, NTC bonding, or US bonding. By providing a bonding method.

The present invention is characterized by a bonding method for fully connecting a semiconductor integrated circuit chip and external leads.

Light from the micro-point irradiation device is irradiated vertically onto the first electrode of the chip to form a micro-point irradiation therefor positioning, and the first electrode and the second electrode of the chip are the distance between the electrodes is equal to the distance between the vertical axis of the light and the axis of the tool, and the tool is located directly above the second electrode when performing the micropoint irradiation. There is a method of bonding.

This method eliminates the drawbacks of the prior art described above. Moreover, after performing the irradiation and dispensing the position, there is no need to bring the tool onto the first wire and use this as the starting point.
Since the tool can be lowered as it is and bonded to the second electrode, the work can be started from this point, which saves time and makes the work more efficient.

Next, I will explain this IV in detail using drawings.〇Figure 1 is a schematic diagram showing the bonding part with a conventional automatic bonder. 2 and 3 are angles 5 that are tilted towards the tool when viewed from the mirror 4 (Figure 1 is an example of this) and in the z=t+ direction.
If you have to tilt it by about 10 to 20 degrees*, you will not be able to attend the monkey. For this reason, as shown in FIG. It is clear that there will be an error of 9 in the height of , and when another chip surface 8 comes, an error of 10 will appear as above.

- To give an example, if l is the amount of error, H is the amount of variation in height, and θ is the positioning angle of the spot, then the amount of error l is calculated by the following equation.

ノ=±HXtanθ Here, the actual value is H-±01 (for ceramic packages) and θ=about 20°, so! −±0. IX
tan20°-±0. IXo, 364=±0.0364
In other words, there will be an error of about ±40 μ due to the variation in package height, and the size of the chip electrode should be 100 to 12
Because of the 0μ angle, other mechanical errors and errors caused by visual positioning by the input member themselves pose a major problem in practice with US bonding using ceramic packages, etc. Therefore, in the apparatus used in the present invention, as shown in FIG. 2, a spotlight 3 is installed in a vertical position above the surface 2 of the chia 1, and the tool 1 is installed at a certain distance 11 away from the surface of the chia 1. This is what I did.

With this configuration, as can be seen in Fig. 3, the error due to variations in chip height caused by the conventional mounting angle is reduced by 9.
It is clear that 10 etc. do not occur.0 Also, FIG. 4 shows an embodiment of the present invention, in which the first electrode 1
5. The forward and backward movement of the tool between the second electrodes 16 can be omitted, and after alignment, the tool can be lowered to '-1' and bonded to the second electrode 16 as it is. In FIG. 4, the same functions as in other figures are indicated by the same reference numerals.

That is, in the case of a large chip such as an LSI, the distance 11 between the spot and the tool is set on the chip 2 so that the operator can select the positioning electrode 15 on the front side and set the tool on the electrode 16 on the opposite side. opposite of 2
It is a good idea to match the distance between the side electrodes.

As mentioned above, the method according to this special edition has the following characteristics.

, l'l'' Regardless of the type of package, even if the height of the chip varies, it does not affect the positioning accuracy, so it is particularly effective for applications that require high-precision positioning, such as in US bonding. In addition, since the mounting angle of the microscope and camera can be vertical or close to vertical, the problem of depth of focus is reduced, which naturally makes positioning of the operator easier, which improves accuracy and helps reduce the axis of fatigue. In addition, it is possible to improve positioning accuracy and work efficiency.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a conventional automatic bonder, Fig. 2 is a schematic diagram of an apparatus used in an embodiment of the present invention, and Fig. 3 is a schematic diagram of the installation angle of a spotlight, which causes misalignment due to the difference in chip height. . 4! FIG. 4 is a schematic diagram illustrating a method of eliminating tool advancement and retraction according to an embodiment of the present invention. 1...tool, 2...chip, 3...
...Spotlight, 4...Microscope, 11
・Old...tool/spotlight installation distance, and 1st
．． Distance between second electrodes, 12.13...Microscope installation angle, 15...Gun/Electrode 1, 16...
Second electrode. a

Claims (1)

[Claims] In a bonding method for connecting a semiconductor integrated circuit chip and an external lead, light from a micropoint irradiation device is irradiated from a vertical direction onto a first electrode of the chip to form a micropoint irradiation here, thereby positioning the chip. and the distance between the first electrode and the second electrode of the chip is equal to the distance between the vertical axis of the light and the axis of the bonding tool, and when performing the micropoint irradiation. The bonding method is characterized in that the bonding tool is located directly above the second electrode.