JP2752890B2 - Wire bonding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding apparatus for connecting a thin metal wire to a semiconductor chip, and more particularly to a wire bonding apparatus having a function of checking whether a bonding load is normal.

[0002]

2. Description of the Related Art Conventionally, when a bonding pad of a semiconductor chip and a lead of a case are connected by a wire bonding apparatus, a semiconductor chip mounted on a case is previously positioned and fixed on a stage of the wire bonding apparatus. The wire bonding tool is given a predetermined load, speed and ultrasonic vibration and is lowered to connect the bonding wire, which is a thin metal wire, by applying an impact force and ultrasonic energy to the bonding pad of the semiconductor chip.

FIG. 4 is a diagram showing a state where a bonding wire is connected to a semiconductor chip. However, when this bonding wire is connected to the semiconductor chip, FIG.
As shown in (1), although there is no problem with the connection on the case 16 side, the semiconductor chip 10 often has a problem that a crack 11 is formed. Moreover, the problem of the crack has occurred even after the dynamic conditions given to the bonding tool 2 are appropriately set. For this reason, even after the dynamic conditions are set, it is necessary to periodically inspect the load and speed applied to the bonding tool and the quality of the ultrasonic energy.

FIG. 5 is a diagram showing a configuration of an example of a conventional wire bonding apparatus. Therefore, in the conventional wire bonding apparatus, as shown in FIG. 5, an impact sensor 5 for measuring the impact force of the bonding tool 2 of the arm 1 extending from the main body is mounted on the stage 4, and this impact sensor 5
Was provided and an oscilloscope 7 was provided with an impact force measuring device 6 for drawing a shock wave.

[0005] The dynamic conditions of the bonding tool 2 are set by setting the load and the lowering speed applied to the bonding tool 2 and the ultrasonic energy by the ultrasonic oscillation control section 9, and the impact force measuring device 6 periodically performs bonding. The shock wave obtained by the impact force of the tool 2 is observed, and crack prevention management of the semiconductor chip is performed based on whether or not the conditions are appropriate.

[0006]

However, in the above-described conventional wire bonding apparatus, although the impact force is periodically checked, a crack occurs in the semiconductor chip during the periodic check and a large number of defective products are generated. May occur in large quantities. Further, even if the cause is determined, it takes a long time and wastes a lot of man-hours. Furthermore, since the apparatus is stopped during the repair adjustment, there is a problem that the operation rate of the apparatus is reduced.

Accordingly, an object of the present invention is to provide a wire bonding apparatus which detects the cause in advance, prevents the occurrence of cracks, eliminates unnecessary adjustment man-hours, and has a high operation rate.

[0008]

SUMMARY OF THE INVENTION The present invention is characterized in that a shock sensor arranged on a stage, a shock wave output section for detecting a shock generated when the shock sensor is hit with a bonding tool and outputting a shock wave, and a reference shock wave. A comparison detection unit that compares the shock wave output from the shock wave output unit with the reference shock wave and outputs a difference in waveform,
Load setting unit and ultrasonic
Before performing a predetermined number of bonding with the oscillation controller
By hitting the impact sensor of the bonding tool
There is a difference between the obtained shock wave and the reference shock wave
And there is no deviation in the set values of the load and ultrasonic conditions
If the load and ultrasonic conditions are set within the allowable range,
The shock wave obtained by hitting the shock sensor again and the reference
Judgment method that generates an alarm when there is a difference compared with the shock wave
And a wire bonding apparatus including a step.

[0009]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the wire bonding apparatus of the present invention. As shown in FIG. 1, the wire bonding apparatus receives a shock signal from a shock sensor 5 disposed on a stage 4a and outputs a shock wave. The shock wave output unit 12 stores a reference shock wave in advance and outputs a shock wave. A comparison detection unit 13 that compares the shock wave output from the unit 12 to determine a difference in the waveform, outputs a signal for operating the alarm unit 15, and instructs a change in the load of the bonding tool and the ultrasonic application condition; 13 is provided with a load / ultrasonic setting unit 14 for inputting the instruction of 13 and controlling the ultrasonic oscillation control unit 9 and the load applying unit.

FIG. 2 is a flowchart for explaining the operation of the wire bonding apparatus of FIG. 1, and FIGS. 3A and 3B are a waveform diagram and a graph for explaining the waveform of a shock wave. Next, the operation of the wire bonding apparatus will be described with reference to FIGS. First, the impact detection peak value (for example, 30 gf or less) and the shock decay time (for example, 45 msec or less) of the reference waveform under the best condition shown in FIG.
To memorize. Next, the load / ultrasonic application condition of the bonding arm 2 corresponding to the reference waveform is set, and the bonding operation is started in step A of FIG.

Next, when the predetermined number of operations has been reached, the stage 4 moves in step B, and the impact sensor 5 is positioned immediately below the bonding arm 2. Next, step C
The bonding arm 2 descends and strikes the impact sensor 5,
Thereby, the shock sensor 5 generates a signal and outputs the shock wave output unit 1.
Enter 2 Next, the shock wave output unit 12 outputs a shock wave and inputs the shock wave to the comparison detection unit 13. Next, in step D, the comparison detection unit 13 compares the previously stored reference waveform with the input shock wave. If there is no difference between the waveforms, the process returns to step A to continue the bonding operation.

If there is a difference in step D, in step E, the set values of the load and the ultrasonic condition of the load setting unit and the ultrasonic oscillation control unit 9 are detected, and it is determined whether there is any deviation from the predetermined condition. Detects and automatically resets any deviation. If there is no deviation, the load condition and the ultrasonic condition are automatically reset within the range of the correlation condition shown in FIG. Next, in step F, the impact sensor 5 is hit with the bonding arm 2, and the waveform output in step G is compared with the reference waveform to determine whether there is a difference.

Here, if there is no difference, the process returns to step A to perform the bonding operation. If there is a difference, an alarm is issued by the alarm unit 15 and the apparatus is stopped in step H.

Here, a description will be given of the assistance in this operation. Conventionally, the occurrence of cracks in a semiconductor chip is based on the fact that the peak value and attenuation value of a shock wave detected are the peak values of the reference waveform shown in FIG. Occurs when the attenuation value is large and long.
However, mechanical loosening or abrasion of the connection part such as a bonding tool causes the transmission of the impact force to become unstable, and the impact force varies from bonding to bonding, and in some cases, a large impact force is applied to cause cracking. Was thought. In consideration of this, first, the impact energy value with the best connection performance is determined, and the impact waveform generated at this time is used as the reference waveform, and when there is no mechanical loosening or wear, how much from the reference waveform If there is a difference within the range,
I experimented to see if it could be connected without cracking. As a result, it was found that the setting only needs to be kept within the correlation condition range of the load and the ultrasonic condition which determine the impact force shown in FIG. Based on such experimental results and knowledge, even during the bonding operation, by checking the waveform of the shock wave generated by the impact force of the bonding tool, the initially set bonding conditions are:
This is to determine whether the condition can be set to an appropriate condition simply by correcting the condition or cannot be repaired without repair.

It is to be noted that the condition setting does not need to be corrected,
If only the mechanical looseness of the bonding arm or the wear of the bonding tool is simply checked, the impact sensor can be hit a plurality of times, and it can be determined by seeing whether or not there is a variation in the waveforms.

[0017]

As described above, according to the present invention, a shock wave output section for detecting a shock generated when a shock sensor is hit with a bonding tool and outputting a shock wave, and a shock wave output section for storing and storing a reference shock wave in advance. The shock wave to be output is compared with the reference shock wave, a difference in waveform is output, and a warning is issued based on the difference, or a comparison detection unit that corrects bonding load and ultrasonic conditions is provided. When there is a difference between the waveform of the shock wave output by the unit and the waveform of the reference waveform, when there is a difference between the shock wave obtained by the next impact on the impact sensor by changing the impact energy of the bonding tool and the reference waveform By issuing an alarm to the user, changes in bonding conditions due to mechanical loosening and wear of the bonding arm and bonding tool, etc. Or simply can determine whether variations due to the deviation of the condition setting in a very short time.

Therefore, there is an effect that it is possible to detect the cause of the condition change in advance and prevent the occurrence of cracks in the semiconductor chip. In addition, since there is no need to spend man-hours for setting conditions, there is an effect that the operation rate of the apparatus can be further increased.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a wire bonding apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the wire bonding apparatus of FIG. 1;

FIG. 3 is a waveform diagram and a graph for explaining a waveform of a shock wave.

FIG. 4 is a diagram showing a state where a bonding wire is connected to a semiconductor chip.

FIG. 5 is a diagram showing a configuration of an example of a conventional wire bonding apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 bonding arm 2 bonding tool 4, 4 a stage 5 impact sensor 6 impact force measuring device 7 oscilloscope 9 ultrasonic oscillation control unit 12 shock wave output unit 13 comparison detection unit 14 load / ultrasonic setting unit

Continuation of the front page (56) References JP-A-58-164233 (JP, A) JP-A-1-112436 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21 / 607 H01L 21/60 301

Claims (1)

(57) [Claims] An impact sensor arranged on a stage, a shock wave output unit for detecting an impact generated when the impact sensor is hit with a bonding tool and outputting a shock wave, and a shock wave output unit for storing and storing a reference shock wave in advance. The ratio of comparing the shock wave output from the above with the reference shock wave and outputting a difference in waveform
Ultrasonic load for setting the load and ultrasonic conditions
Weight setting unit and ultrasonic oscillation control unit
After bonding, the impact of the bonding tool
Shock wave obtained by tapping the sensor and the reference shock
There is a difference compared to the wave and of the load and ultrasonic conditions
If there is no deviation in the set value, the load and ultrasonic conditions
Set again within the allowable range and hit the impact sensor again.
Warning when there is a difference between the shock wave
A wire bonding apparatus comprising: a determination unit that generates a report .