JPS6120138B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for assembling microelectronic devices such as semiconductor integrated circuits, in which a plurality of electrodes and external leads on a semiconductor integrated circuit element (hereinafter referred to as a chip) are connected with gold wire or aluminum wire. This paper relates to a bonding method that connects with

In the field of semiconductor integrated circuits, labor costs have been rising sharply recently, and eliminating work that requires human labor has become an important problem that must be solved.
In particular, labor saving in the so-called bonding process that connects chip electrodes and external leads is attracting much attention. Wire bonding equipment (hereinafter referred to as bonder), which is still the mainstream in this bonding process, uses microcomputers and other devices to replace the conventional manual work by simply positioning the first starting point and the rest is automatic. Products that can be bonded are becoming common.

These so-called automatic bonders irradiate the starting electrode of the chip with light from a minute irradiation device (hereinafter referred to as a spot light) for positioning the initial starting point. These spot lights are equipped with bonding tools (hereinafter referred to as tools) in advance.
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 misalignment when bonding to the chip electrode.

At this time, since the tool in a conventional automatic bonder is located directly above the electrode to be bonded, the spotlight has to be installed at several angles with respect to the tool, which is perpendicular to the chip.

Therefore, if the height of the tip varies, even if the operator determines that the spot light has been used to position the tip, the tool and spot light may actually be showing a position that is shifted by the amount of the variation in height. Become.

Generally, when an automatic bonder is used for initial positioning, a sensor attached to the bonder detects the amount of deviation in the mount position of the chip, and based on the detected amount, calculation is performed using a correction calculation formula, and the resulting output value is calculated based on the above-mentioned mount position. Even if there is misalignment, bonding can be performed correctly.

However, as mentioned above, since the amount of deviation from the actual tool is calculated as the detected amount, there is a problem that bonding deviation occurs in the electrodes on the actual chip. In particular, recently, in order to increase the number of chips obtained per wafer, the chip area has been made as small as possible, so the electrodes of the chip have inevitably become smaller, and even a slight bonding deviation often results in a defect.

In addition, ultrasonic (hereinafter referred to as US) automatic bonders are disadvantageous in bonding accuracy compared to thermocompression (hereinafter referred to as NTC) automatic bonders because they include mechanically rotating elements. The applicable devices are usually enclosed in ceramic or glass type packages (cases), and the height of these packages themselves varies widely.
This method has the drawback that there is a large misalignment between the spot light and the actual tool, which is one of the reasons why the automation of US bonders has been delayed.

Therefore, in order to solve these problems, the purpose of the present invention is to accurately recognize the tool position even when there are variations in chip height during bonding, regardless of the type of package, NTC, or US bonding, and to achieve efficient bonding. The purpose is to provide a method for

A feature of the present invention is that in a bonding method for connecting a semiconductor integrated circuit chip and an external lead, light from a micropoint irradiation device is irradiated vertically onto the first electrode of the chip to irradiate the micropoint. forming and thereby positioning, the distance between the first electrode and the second electrode of the chip being equal to the distance between the vertical axis of the light and the tool axis;
and a bonding method in which the tool is located directly above the second electrode while performing the minute point irradiation.

This method eliminates the drawbacks of the prior art described above. Moreover, after positioning by irradiation, the tool is not brought over the first electrode and used as the starting point; instead, the tool is lowered and bonded to the second electrode, and this is used as the starting point. Because you can do the work, you can save time and work more efficiently.

Next, the present invention will be explained in detail using the drawings.

Figure 1 is a schematic diagram showing the bonding part of a conventional automatic bonder.As shown in the figure, the tool 1 is perpendicular to the chip surface 2, so the spotlight 3 is on the near side of the tool when viewed from the microscope 4. direction (Figure 1 is an example of this) and angle 5 (approximately 10 to 20
°) I have no choice but to install it at an angle. Therefore, as shown in FIG. 3, even if the operator positions the spotlight on the electrode of a certain arbitrary chip surface 6, when the next chip surface 7 comes, there will be an error in the height of the chip surfaces 6 and 7 relative to the mounting angle 5. It is clear that an error of 9 is produced, and if another chip surface 8 comes, an error of 10 will be produced as in the above case.

For example, if l is the amount of error, H is the amount of variation in height, and θ is the mounting angle of the spot, then the amount of error l is expressed by the following equation.

l=±H×tanθ Here, the actual values are H=±0.1 (in the case of ceramic package) and θ=about 20°, so l=±0.1×tan20°=±0.1×0.364 =±0.0364 In other words, the height of the package ±40 just for the variation in height
This results in an error of about μ, and the size of the chip electrode is
Since the angle is 100 to 120 μm, there are other mechanical errors and errors due to human visual positioning, and US bonding, which uses ceramic packages, etc., poses a big problem in practice. Therefore, in the apparatus used in the present invention, as shown in Fig. 2, a spot light 3 is installed at a position perpendicular to the chip surface 2, and a tool 1 is installed at a certain distance 11 from the bonding surface. be.

With this configuration, it is clear that the errors 9, 10, etc. due to variations in chip height, which occur in the conventional mounting angle, do not occur, as can be seen in FIG.

Further, FIG. 4 shows an embodiment of the present invention.
advancement of the tool between the first electrode 15 and the second electrode 16;
The retreat movement can be omitted, and after alignment, the tool can be lowered as it is 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 operator selects the positioning electrode 15 on the front side and moves the tool to the electrode 1 on the opposite side.
The distance between the spot and the tool is 1 so that it can be set to 6.
1 may be made to match the distance between the electrodes on two opposing sides of the chip 2.

As described above, the method according to the present patent has the following features.

That is, regardless of the type of package, even if the chip height varies, this does not affect the positioning accuracy, so it is particularly effective for applications that require high-precision positioning, such as US bonding. In addition, since the mounting angle of the microscope and camera can be vertical or close to vertical, problems with depth of focus are reduced, which naturally makes it easier for the operator to position the operator, improving accuracy and reducing fatigue. In addition, it is possible to improve positioning accuracy and work efficiency.

[Brief explanation of the drawing]

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 a spot light installed at an angle where the position of the spot light is shifted due to the difference in chip height. FIG. 4 is a schematic diagram illustrating a method of omitting tool advancement and retraction according to one embodiment of the present invention. 1... Tool, 2... Chip, 3... Spotlight, 4... Microscope, 11... Tool/spotlight installation distance and distance between first and second electrodes, 12, 13... Microscope installation Angle, 15...
Electrode 1, 16...second electrode.

Claims (1)

[Claims] 1. In a bonding method for connecting a semiconductor integrated circuit chip and external leads, light from a micropoint irradiation device is irradiated vertically onto the first electrode of the chip to form a micropoint irradiation there, 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 the micropoint irradiation is performed. A method of bonding, wherein the bonding tool is located directly above the second electrode.