JP2953448B2 - BINDING METHOD, COMPUTER-READABLE RECORDING MEDIUM CONTAINING PROGRAM FOR EXECUTING BONDING METHOD, AND BONDING APPARATUS - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding method for bonding an electrode of a semiconductor device having a semiconductor element to a substrate, a computer-readable recording medium storing a program for executing the bonding method, and a bonding apparatus.

[0002]

2. Description of the Related Art In recent years, semiconductor devices (hereinafter referred to as IC chips) have been developed.
Is being rapidly promoted in an assembly process of mounting the semiconductor device on a substrate as an external circuit. In particular, labor saving and automation of a wire bonding process for obtaining electrical continuity between each electrode on an IC chip and a lead which is an electrode on the substrate side are becoming more and more active. Further, as the fine processing technology for IC chips has advanced, the size of IC chips has been reduced in circuit configurations of the same scale. Along with this, the size of the electrodes on the IC chip and the distance between the electrodes are also being reduced at the same time. In ball bonding, which is the mainstream of the wire bonding method, the pressure bonding diameter and the pressure bonding thickness of the ball bonded to the electrode of the IC chip Is required to be reduced.

Here, a conventional bonding method will be described with reference to the drawings. FIG. 2 is a flowchart showing a procedure for automatically calculating a bonding condition between an electrode on an IC chip and a thin metal wire in a ball bonding step, which is shown in FIGS. 3 (a), 3 (b) and 3 (c). () Is a diagram showing a ball bonding process.

In FIG. 2, first, a crimping diameter and a crimping thickness representing a crimping ball shape of a thin metal wire to be bonded to an electrode on an IC chip are input to a bonding apparatus (step 3).
8). As shown in FIG. 3C, reference numeral 21 denotes a press-bonded ball, reference numeral 6 denotes a press-bonding diameter, and reference numeral 7 denotes a press-bond thickness. next,
The hole diameter, the chamfer diameter, the chamfer angle, and the diameter of the thin metal wire indicating the shape of the capillary 10 are input to the bonding apparatus (step 39). 3 (a) and 3
As shown in (b), the hole diameter 1 indicates the inner diameter of the capillary 10, the chamfer diameter 2 indicates the opening diameter of the tip of the capillary 10, and the chamfer angle 3 indicates the opening angle of the tip of the capillary 10. Further, the thin metal wire 4 is connected to the capillary 1.
0 through the hollow portion.

Next, a crimping diameter 6, a crimping thickness 7, a hole diameter 1,
From the parameters of the chamfer diameter 2 and the chamfer angle 3, the diameter of the initial ball 5 shown in FIG. 3B is determined based on an empirical formula (step 40). Further, based on the diameter of the initial ball 5 and the diameter of the thin metal wire 4, a discharge time and a discharge voltage required for forming the initial ball 5 are determined by an empirical formula or a conversion table (step 41). Based on the discharge voltage and discharge time determined here, the initial ball 5
To form

In the next stage, the bonding weight, the output of the ultrasonic vibration and the application time of the ultrasonic vibration are determined from the input parameters based on the empirical formula (step 42). On the basis of the conditions determined here, the initial ball 5 formed at the tip of the fine metal wire 4 is pressed against the electrode of the IC chip and the determined bonding load is applied. According to the conditions of the output and the application time of the ultrasonic vibration, the ultrasonic vibration
Initial ball 5 and IC via capillary 10
Apply to the electrodes on the chip.

In this manner, when bonding the pressure-bonded ball 21 to the electrode of the IC chip, the pressure-bonded diameter 6 and the pressure-bonded thickness 7 of the pressure-bonded ball 21 can be set to predetermined dimensions.

In the actual semiconductor device manufacturing process, a so-called mounting process of bonding an IC chip to a substrate or a lead frame via an adhesive is performed before the ball bonding process. FIG.
FIG. 4 is a diagram showing the behavior of the IC chip when performing ball bonding to the IC chip after the mounting step.

In FIG. 4, reference numeral 8 denotes a substrate, and 11 denotes an IC.
The chip 9 is an adhesive for joining the substrate 8 and the IC chip 11. Ultrasonic vibration 1 from capillary 10
2 is applied to the electrodes of the IC chip 11, and the IC chip 11 itself vibrates due to the ultrasonic vibration 12. This IC
When the vibration 13 of the tip 11 increases, the capillary 1
The ultrasonic vibration from zero is canceled out (transmission loss), and the energy required for joining the press-bonded ball 21 and the electrode is reduced, so that a shortage of the joint energy causes poor joining of the press-bonded ball 21. As the size of the IC chip 11 becomes smaller, the holding force (rigidity) by the adhesive 9 is obtained.
Therefore, the vibration 13 of the IC chip 11, that is, the transmission loss of the ultrasonic wave increases. Further, it can be easily estimated that the transmission loss increases even when the thickness of the adhesive 9 increases or the elastic modulus of the adhesive 9 decreases.

FIG. 5 shows the relationship between the position of the capillary 10 on the IC chip 11 and the vibration of the IC chip 11. The magnitude of the vibration of the IC chip 11 caused by the ultrasonic vibration from the capillary 10 depends on the bonding position. As shown in FIG. 5A, when the ultrasonic vibration 17 is applied by the cavities 10 near the side perpendicular to the vibration direction of the ultrasonic vibration 17, the amplitude of the vibration 18 of the IC chip 11 is small. The direction of the vibration 18 is substantially parallel to the ultrasonic vibration 17, but as shown in FIG. 5B, near the side parallel to the vibration direction of the ultrasonic vibration 17,
When the ultrasonic vibration 17 is applied, the vibration 19 of the IC chip 11 includes not only the vibration substantially parallel to the ultrasonic vibration 17 but also the rotational vibration generated from the moment balance. The amplitude of the vibration 19 of the IC chip increases.
Accordingly, the vibrations 18 and 19 of the IC chip 11 cause a transmission loss of the ultrasonic vibration, and an insufficient bonding energy causes a defective bonding of the press-bonded ball 21.

Therefore, in order to prevent the bonding failure of the press-bonded ball 21 at the electrode of the IC chip 11, measures such as increasing the output of the ultrasonic vibration or extending the application time of the ultrasonic vibration have been taken. Was.

[0012]

However, when the above measures are applied to a large IC chip as it is, since the transmission loss of the ultrasonic vibration is small, excessive deformation of the press-bonded ball 21 due to the ultrasonic vibration occurs. As a result, a short circuit occurs between the electrodes.

Further, even in the same IC chip 11,
As described above, since the transmission loss of the ultrasonic wave varies depending on the bonding position, when the ultrasonic wave application condition is the same at any bonding position of the IC chip 11 as in the related art, the same IC chip 11 The bonding state varies for each of the electrodes, and it becomes difficult to obtain good bonding properties for all the electrodes. in this way,
The bonding state of the electrode and the crimping ball 21 is determined by the IC chip 11
And the thickness and elasticity of the torsion agent, the position of bonding, and the like, and short-circuiting between the electrodes due to defective bonding of the press-bonded ball 21 and defective shape of the press-bonded ball 21 is likely to occur.

That is, in the conventional bonding method, the size of the IC chip 11, the elastic modulus and the thickness of the adhesive, and the parameters of the bonding position which affect the bonding property of the press-bonded ball 21 are not considered at all. In such a bonding process, it is necessary to optimize bonding conditions by an operator each time, and the number of working steps involved becomes extremely large, and there is a problem that productivity of the semiconductor device is reduced.

Furthermore, the above-mentioned condition optimization largely depends on the experience of the operator, and if the conditions are not optimized properly, the electrodes may not be connected to each other due to poor bonding of the pressure-bonded ball 21 or an excessively large diameter of the pressure-bonded ball 21. There is a problem that a short circuit occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to prevent bonding failure of a press-bonded ball and short-circuit between electrodes without lowering the productivity of a semiconductor device. It is an object of the present invention to provide a computer-readable recording medium storing a program for executing the method and the bonding method, and a bonding apparatus.

[0017]

In order to achieve the above object, the present invention employs the following constitution. In the bonding method according to the first aspect, a ball formed at the tip of a thin metal wire is pressed against an electrode on a semiconductor element fixed on a substrate via an adhesive by a capillary, and ultrasonic vibration is applied. In a bonding method of deforming the ball into a press-bonded ball and pressing the ball against the electrode, the output amount of the ultrasonic vibration is determined from a press-bonded diameter of the press-bonded ball and a shape parameter of the capillary, and a size of the semiconductor element. The output correction amount of the ultrasonic vibration is determined from the parameters of the elastic modulus of the adhesive, the coating thickness of the adhesive, and the bonding position, and the output amount of the ultrasonic vibration is corrected by the output correction amount of the ultrasonic vibration. Then, the correction output amount of the ultrasonic vibration is determined.

According to a second aspect of the present invention, there is provided a computer readable recording medium storing a program for executing the bonding method according to the second aspect, wherein a ball formed at the tip of a thin metal wire is fixed on a substrate via an adhesive. A computer-readable recording medium that records a program for executing a bonding method of pressing the upper electrode by a capillary and applying ultrasonic vibration while deforming the ball into a press-bonded ball and pressing the electrode against the electrode, Means for inputting the pressure diameter of the pressure-bonded ball, means for inputting the shape parameter of the capillary and the diameter of the fine metal wire, means for determining the diameter of the ball from the pressure diameter and the diameter of the fine metal wire, Semiconductor element size, elastic modulus of the adhesive, coating thickness of the adhesive and bonding position parameters Means for inputting, means for determining the output amount of the ultrasonic vibration from the crimping diameter of the crimping ball and the shape parameter of the capillary, the size of the semiconductor element, the elastic modulus of the adhesive, and the application of the adhesive Means for determining the output correction amount of the ultrasonic vibration from the thickness and the bonding position parameter; and correcting the output amount of the ultrasonic vibration with the output correction amount of the ultrasonic vibration to obtain the corrected output amount of the ultrasonic vibration. And a program for executing a bonding method including means for determining.

According to a third aspect of the present invention, in the bonding apparatus, the ball formed at the tip of the fine metal wire is pressed against the electrode on the semiconductor element fixed on the substrate via an adhesive by a capillary, and the ultrasonic vibration is applied. A bonding device for applying the pressure, deforming the ball into a pressure-bonded ball and pressing the ball to the electrode, inputting a pressure-bonded diameter of the pressure-bonded ball, and inputting a shape parameter of the capillary and a diameter of the fine metal wire. Means, means for determining the diameter of the ball from the pressure bonding diameter and the diameter of the thin metal wire, and inputting the size of the semiconductor element, the elastic modulus of the adhesive, the applied thickness of the adhesive, and bonding position parameters. Means for determining the output amount of the ultrasonic vibration from the crimping diameter and the shape parameters of the capillary; and the size of the semiconductor element. Means for determining the output correction amount of the ultrasonic vibration from the elastic modulus of the adhesive, the coating thickness of the adhesive and the bonding position parameter, and the output amount of the ultrasonic vibration by the output correction amount of the ultrasonic vibration Means for making a correction to determine a correction output amount of the ultrasonic vibration.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 7, the bonding apparatus according to the present invention uses a semiconductor element (hereinafter abbreviated as IC chip 11) in which an initial ball 5 formed at the tip of a fine metal wire 4 is fixed on a substrate via an adhesive 9. A bonding device that presses the upper electrode with the capillary 10 and applies ultrasonic vibration to deform the initial ball 5 into a press-bonded ball 21 and press-bond the same to the electrode. Means 31; means for inputting the shape parameters of the capillary 10 and the diameter of the fine metal wire 4; 32; means 34 for determining the diameter of the initial ball 5 from the crimping diameter 6 and the diameter of the fine metal wire 4;
Means 33 for inputting the size of 1, the elastic modulus of the adhesive 9, the applied thickness of the adhesive 9, and the bonding position parameters;
Means 35 for determining the output amount of the ultrasonic vibration from the crimping diameter 6 and the shape parameter of the capillary 10; and the size of the IC chip 11, the elastic modulus of the adhesive 9, the applied thickness of the adhesive 9, and the bonding position parameters. Means 36 for determining an output correction amount of the ultrasonic vibration, and means 37 for correcting the output amount of the ultrasonic vibration with the output correction amount of the ultrasonic vibration to determine a correction output amount of the ultrasonic vibration. Provided. Further, an ultrasonic generator 38 for applying ultrasonic vibration to the capillary 10 is provided. The ultrasonic generator 38 generates ultrasonic vibration based on the correction output amount determined by the means 37 and applies the ultrasonic vibration to the capillary 10.

The capillary 10 has an initial ball 5
Is pressed against the electrode, and as shown in FIG. 3A, the shape of the capillary 10 is specified by a hole diameter 1, a chamfer diameter 2, and a chamfer angle 3.
The initial ball 5 is a spherical body formed by applying discharge energy from an electric torch (not shown) to the tip of the fine metal wire 4.

Next, by the above-described bonding apparatus,
A method for bonding a thin metal wire to an electrode will be described. In this bonding method, an initial ball 5 formed at the tip of a thin metal wire 4 is pressed against an electrode on an IC chip 11 fixed on a substrate via an adhesive 9 by a capillary 10 and an ultrasonic vibration is applied. In the bonding method in which the initial ball 5 is transformed into the press-bonded ball 21 and press-bonded to the electrode, the output amount of the ultrasonic vibration is determined from the press-bonded diameter 6 of the press-bonded ball 21 and the shape parameter of the capillary 10. The output correction amount of the ultrasonic vibration is determined from the parameters of the size of the adhesive 9, the elastic modulus of the adhesive 9, the thickness of the adhesive 9 applied, and the bonding position, and the output amount of the ultrasonic vibration is corrected for the output of the ultrasonic vibration. The correction amount is used to determine the correction output amount of the ultrasonic vibration.

FIG. 1 is a view for explaining the bonding method of the present invention, and is a flowchart showing a procedure for automatically calculating the bonding condition between the electrode on the IC chip 11 and the press-bonded ball 21 in the ball bonding step. FIG.

In FIG. 1, first, a crimped ball 21 of a thin metal wire 4 to be joined to an electrode on an IC chip 11
Of the crimping diameter 6 and the crimping thickness 7 (step 3
1). Further, the hole diameter 1, the chamfer diameter 2, the chamfer angle 3, and the diameter of the thin metal wire 4 indicating the shape of the capillary 10 are input (step 32). Next, the diameter of the initial ball 5 shown in FIG. 3B is determined by an empirical formula based on the parameters of the compression diameter 6, the compression thickness 7, the hole diameter 1, the chamfer diameter 2, and the chamfer angle 3. (Step 33). Further, the specific discharge time and discharge voltage are determined by an empirical formula or a conversion table based on the diameter of the initial ball 5 and the diameter of the thin metal wire 4 (step 34). Based on the conditions of the discharge voltage and the discharge time determined here, the initial ball 5 is formed by an electric torch.

In the next step, the size of the IC chip 11, the elastic modulus of the adhesive 9 such as Ag paste or adhesive tape, the thickness of the adhesive 9, the bonding position, and the bonding temperature are input to the bonding apparatus ( Step 35).
Based on these parameters, the bonding weight, the bonding weight correction amount, the ultrasonic vibration output amount, the ultrasonic vibration application time, and the ultrasonic vibration output correction amount are calculated and determined by a program input in advance. (Steps 36, 37, 43). Further, the correction output amount of the ultrasonic vibration is determined from the output amount of the ultrasonic vibration and the output correction amount of the ultrasonic vibration (step 44).

Here, the bonding weight correction amount and the ultrasonic vibration output correction amount are the size of the IC chip 11, the thickness and the elasticity of the adhesive 9, the bonding weight for each bonding position, and the output of the ultrasonic vibration. This is a correction amount for performing each correction, and the size of the IC chip 11 is sufficiently large.
When the adhesive 9 is sufficiently thin and the elastic modulus is sufficiently high, the weight and the output amount of ultrasonic vibration are used as a reference value, and are expressed as a magnification with respect to the reference value at each bonding position.

In the present invention, the bonding weight, the bonding weight correction amount, and the ultrasonic application time are fixed for each of the target diameter of the pressure-bonded ball 21 and the bonding temperature, and the ultrasonic vibration output amount and the ultrasonic vibration output correction amount are fixed. Is desirably changed according to the size of the IC chip 11, the thickness of the adhesive 9, and the elastic modulus. The reason is that in most cases, it is sufficient to change only the output amount of the ultrasonic vibration and the output correction amount of the ultrasonic vibration.

Hereinafter, a method for determining each parameter will be described in more detail. The bonding weight, the correction amount of the bonding weight, and the ultrasonic wave application time are determined from the input pressure bonding diameter 6 and the bonding temperature using a conversion table based on the experimental results. The bonding load needs to be increased as the compression diameter 6 increases and as the bonding temperature decreases. Similarly, the ultrasonic wave application time needs to be increased as the pressure bonding diameter 6 increases and the bonding temperature decreases.

The output amount of the ultrasonic vibration must be increased because the transmission loss of the ultrasonic wave increases as the size of the IC chip 11 decreases. As for the arithmetic expression for obtaining the output amount of the ultrasonic vibration, a function obtained by conducting an experiment in advance for each size of each IC chip 11 and performing an approximate calculation may be used. In this case, it is desirable that the function system be such that the output amount decreases as the size of the IC chip 11 increases and gradually approaches a constant value. The output correction amount of ultrasonic vibration is
A correction term for correcting the transmission loss of the ultrasonic wave that varies depending on the size of the IC chip 11, the thickness and the elasticity of the adhesive 9, and a correction term for correcting the transmission loss of the ultrasonic wave that varies depending on the bonding position. And divided into

First, in the correction term based on the size of the IC chip, the thickness of the adhesive 9, and the elastic modulus, the size of the IC chip 11 is large because the smaller the size, the greater the transmission loss of ultrasonic waves. There is a need to. As for the arithmetic expression for calculating the output correction term of the ultrasonic vibration, a function obtained by conducting an experiment in advance for each IC chip size and performing an approximate calculation may be used. In this case, it is desirable that the function system be such that the output amount decreases as the size of the IC chip 11 increases and gradually approaches a constant value. Also,
As for the adhesive 9, when the thickness of the adhesive 9 is large and when the elastic modulus of the adhesive 9 is small, the IC at the time of bonding is
Since the vibration of the tip becomes large and the transmission loss of the ultrasonic wave becomes large, the ultrasonic output is increased. As in the case of the calculation for the size of the IC chip, it is effective to obtain the optimum value by experiment and perform an approximate calculation.

Next, in the correction term based on the bonding position, the correction is made so that the output becomes large when the bonding is performed in the vicinity of a side that is strictly in the vibration direction of the old wave where the transmission loss of the ultrasonic wave becomes large. It is desirable to make correction so that the ultrasonic output becomes smaller when bonding is performed in the vicinity of a side perpendicular to the vibration direction.

The following is an example of ideal calculation formulas (1) and (2) for the output amount of ultrasonic vibration and the output correction amount.

A = f ₀ (ID, BD, BT, HD, CD, CA, T) (1)

B = f ₁ (IX, IY, PE, PT) × f ₂ (X, Y, IX, IY, PE, PT) (2)

Here, A indicates the output amount of the ultrasonic vibration, and B indicates the output correction amount of the ultrasonic vibration. f ₀ () is an ultrasonic output calculation function when vibration of the IC chip 11 does not occur, f ₁
() Is a correction term function based on the size of the IC chip 11, the elastic modulus of the adhesive 9, and the thickness (provided that f ₁ ()> 1 and IX
× IY → ∞, PE → ∞, PT → 0 f ₁ () =
1), f ₂ (), the bonding position by the correction term function (however, f ₂ () shows a> 1 and f ₂ with vibration minimum position of the IC chip 11 () = 1). Also, ID is the diameter of the initial ball 5, BD is the crimping diameter 6, BT is the crimping thickness 7,
HD is hole diameter 1, CD is chamfer diameter 2, CA is chamfer angle 3, T is bonding temperature, IX is IC
The length of one side (X direction) of the chip 11, IY is the length of one side (Y direction) of the IC chip 11, PE is the elastic modulus of the adhesive 9, PT is the thickness of the adhesive 9, X and Y are IC This parameter indicates a bonding position on the chip 11.

F ₀ can be empirically obtained from the result of a bonding experiment conducted by using a sufficiently large IC chip 11 and an adhesive 9 having a sufficiently large elastic modulus and making the thickness of the adhesive 9 sufficiently small. Can be. f ₁ and f ₂ are IC chips 1
This is an element that depends on the size of 1, the applied thickness of the adhesive 9, and the elastic modulus. The size of the IC chip 11 at f _1, perform basic output correction of the ultrasonic vibration in the elastic modulus and the thickness of the adhesive 9, performs correction depending on the bonding position at f _2. That is, the actual output amount of ultrasonic vibration correction is f ₀ × f ₁ × f
It becomes ₂ .

The determination of f ₁ and f ₂ can be determined by performing an experiment for each size of the IC chip 11 and each type of the adhesive 9 and approximating the obtained result by a least square method or the like. The function system for approximation is a function in which the output amount of the ultrasonic vibration decreases with respect to the size of the IC chip 11 within the bonding range, and the ultrasonic vibration increases as the thickness of the adhesive 9 increases. Function that increases the output of the
As long as the function can be approximated by a function in which the output amount of the ultrasonic vibration decreases as the elastic modulus of the adhesive 9 increases, any application is possible. In addition, as long as it is in line with the above-mentioned tendency, experimental data and the like may be interpolated and obtained in the form of a correspondence table obtained by an experiment instead of the form of a function.

Also, means for inputting the crimping diameter of the crimping ball 21 in FIG. 1 (step 31), means for inputting the shape parameter of the capillary and the diameter of the fine metal wire (step 32), Means for determining the diameter of the ball from step (step 33); means for inputting the size of the semiconductor element, the elastic modulus of the adhesive, the thickness of the applied adhesive and the bonding position parameters (step 35);
A means for determining the output amount of ultrasonic vibration from the crimping diameter and the shape parameter of the capillary (step 37), and the ultrasonic vibration from the size of the semiconductor element, the elastic modulus of the adhesive, the applied thickness of the adhesive and the bonding position parameters. Means for determining the output correction amount of the ultrasonic vibration (step 43) and means for correcting the output amount of the ultrasonic vibration with the output correction amount of the ultrasonic vibration to determine the corrected output amount of the ultrasonic vibration (step 44)
The program for executing the bonding method including the above may be recorded on a computer-readable recording medium, and the recording medium may be read and executed by the computer to determine the correction output amount of the ultrasonic vibration.

In the bonding method described above, the initial ball 5 formed at the tip of the fine metal wire 4 is pressed against the electrode of the IC chip 11 fixed on the substrate via the adhesive 9 by the capillary 10 and the ultrasonic vibration is performed. In the bonding method in which the initial ball 5 is deformed into the press-bonded ball 21 and press-bonded to the electrode, the output amount of the ultrasonic vibration is determined from the press-bonded diameter 6 of the press-bonded ball 21 and the shape parameter of the capillary 10, IC chip 1
The output correction amount of the ultrasonic vibration is determined from the parameters of the size 1, the elastic modulus of the adhesive 9, the applied thickness of the adhesive 9, and the bonding position. Since the corrected output amount of the ultrasonic vibration is determined by correcting with the output correction amount, the crimp diameter 6 and the crimp height 7 of the crimp ball 21 can be optimized.

The computer-readable recording medium on which the program for executing the above-mentioned bonding method is recorded is a means for inputting the diameter of the pressure-bonded ball 21 (step 31), and inputting the shape parameter of the capillary and the diameter of the fine metal wire. Means (step 32) and means for determining the diameter of the ball from the pressure bonding diameter and the diameter of the thin metal wire (step 3).
3), means for inputting the size of the semiconductor element, the elastic modulus of the adhesive, the thickness of the applied adhesive and the bonding position parameters (step 35), and the output amount of ultrasonic vibration from the crimping diameter and the shape parameters of the capillary (Step 36); and a means (Step 37) for determining the output correction amount of the ultrasonic vibration from the size of the semiconductor element, the elastic modulus of the adhesive, the applied thickness of the adhesive, and the bonding position parameter. Means for correcting the output amount of the ultrasonic vibration with the output correction amount of the ultrasonic vibration to determine the corrected output amount of the ultrasonic vibration (step 38), so that the determination of the bonding condition is extremely short. The time can be determined, and the productivity of the semiconductor device can be increased.

The bonding apparatus described above uses the press-bonded ball 2
A means 31 for inputting the crimping diameter 6 of 1 and the capillary 10
Means 3 for inputting the shape parameter and the diameter of the thin metal wire 4
2, means 34 for determining the diameter of the initial ball 5 from the pressure bonding diameter 6 and the diameter of the thin metal wire 4, the size of the IC chip 11, the elasticity of the adhesive 9, the applied thickness of the adhesive 9, and the bonding position parameters. 33, a means 35 for determining the output amount of the ultrasonic vibration from the crimping diameter 6 and the shape parameters of the capillary 10, the size of the IC chip 11, the elastic modulus of the adhesive 9, and the application of the adhesive 9. Means 36 for determining an output correction amount of the ultrasonic vibration from a thickness and a bonding position parameter; and a correction output amount of the ultrasonic vibration by correcting the output amount of the ultrasonic vibration with the output correction amount of the ultrasonic vibration. Means 37 for determining the diameter of the pressure-bonded ball 21 and the pressure-bonded thickness 7 of the pressure-bonded ball 21. It is possible to prevent a short circuit between electrodes due to the result, it is possible to improve the productivity of the semiconductor device.

[0042]

The present invention will be further described below with reference to examples. An IC chip having a size of 5 mm × 5 mm and a thickness of 400 μm was fixed to a lead frame processed by etching of a Cu alloy using Ag paste as an adhesive. Next, bonding was performed using a gold wire having a wire diameter of 25 μm, with the target pressure bonding diameter of the pressure bonding ball being 60 μm and the pressure bonding thickness being 12 μm.

First, the diameter of the crimping: 60 μm
m, crimp thickness: 12 μm, hole diameter representing capillary shape: 35 μm, chamfer diameter: 50 μm,
Chamfer angle: 90 °. Further, the diameter of the used gold wire: 25 μm was input. Next, the volume of the required initial ball was calculated from the capillary shape and the target press-bonded ball shape by a program installed in the bonding apparatus, and the initial ball diameter required to obtain the volume was determined to be 49 μm. Further, from the determined initial ball diameter: 49 μm and the already entered fine metal wire diameter: 25 μm, from the correspondence table obtained in the past experiment,
A discharge voltage of 4 kV and a discharge time of 1.2 ms were determined.

Next, the size of the IC chip: 5 mm × 5 m
m, elasticity of adhesive: 1500 MPa, thickness of adhesive:
20 μm was input, and a bonding temperature of 200 ° C. was input to the bonding apparatus. From the parameters of the crimping diameter, linear interpolation is performed according to the correspondence table (Table 1) obtained in the past experiment, the bonding weight is determined to be 25 gf, the ultrasonic wave application time is 10 ms, and the bonding weight correction rate is determined to be 100%. Was. At this point, the above-mentioned f ₀ is 58
It was decided. In Table 1, only the crimping diameter is used as a parameter and the crimping thickness is not touched because the crimping thickness is uniquely determined because the crimping thickness depends only on the initial ball diameter. is there.

Next, a part which depends on the size of the IC chip and the elastic modulus and thickness of the adhesive is obtained. Table 2 shows the size of each IC chip obtained in experiments, the elastic modulus of the adhesive, and f ₁ for each thickness, theta = 90 °, the optimum value of f ₂ of 270 °. Here, the above-mentioned f ₁ is defined as in the following equation (3).

[0046]

(Equation 1)

IX is the length of one side (X direction) of the IC chip, IY is the length of one side (Y direction) of the IC chip, PE is the elastic modulus of the adhesive, PT is the thickness of the adhesive, and α is a constant. It is. Using the numerical values in Table 2, a constant α is obtained for each size of the IC chip, and an average value thereof is calculated, whereby the constant α becomes 300. Here, IX = 5, IY = 5, P
From T = 20 and PE = 1500, f ₁ = 1.036.

In this embodiment, f ₂ is defined as follows. In FIG. 6, the center of the side perpendicular to the direction of the ultrasonic vibration, that is, θ = 0 °, 180 ° is always set to f ₂ (0 °) = f ₂ (180 °) = 1.0 (100%) (4) and then, if f ₂ is assumed to be proportional increase between 0 and 90 °, f ₂ (90 °) = f ₂ (270 °) = 2.0 (200%) (5) and also,, f ₂ (45 °) = f ₂ (135 °) = f ₂ (225 °) = f ₂ (315 °) (6) Here, f ₂ (45 °) = (f ₂ (0 °) + f ₂ (90 °)) ÷ 2 (7).

When the angle is 0 to 90 °, f ₂ is given by the following equation (8): f ₂ (θ) = {(f ₂ (90 °) −f ₂ (0 °))} 90 ° × θ + f ₂ (0 °) (8) Further, when the angle is 90 to 180 °, f ₂ is represented by the following equation (9), and f ₂ (θ) = ｛(f ₂ (90 °) −f ₂ (180)゜)) {90} × (180−θ) + f ₂ (180 °) (9) Further, when 180 to 270 °, f ₂ is given by the following formula (1)
0), and f ₂ (θ) = {(f ₂ (270 °) −f ₂ (180 °))} 90 ° × (θ−180) + f ₂ (180 °) (10) 270 At 360 °, f ₂ is given by the following equation (11). f ₂ (θ) = {(f ₂ (270 °) −f ₂ (360 °))} 90 ° × (360−θ) + f ₂ (360 °) (11)

Here, f = 90 °, f at 270 °
₂ (90 °) and f ₂ (270 °), the following equation (1)
Defined as 2).

F ₂ (90 °) = f ₂ (270 °) = β ÷ (IX × IY) × (PT / PE) +1 (12)

IX is the length of one side (X direction) of the IC chip, IY is the length of one side (Y direction) of the IC chip, PE is the elastic modulus of the adhesive, PT is the thickness of the adhesive, and β is a constant. It is. Using the numerical values in Table 2, a constant β is obtained for each size of the IC chip, and an average value thereof is calculated, whereby the constant α becomes 200. Here, IX = 5, IY = 5, P
From T = 20 and PE = 1500, f ₂ = 1.11. Therefore, the output amount of the ultrasonic vibration applied to the ball and the electrode is represented by the following equation (13): f ₀ × f ₁ × f ₂ = 58 × 1.036 × 1.11 = 66.7 (mW) (13) is determined.

[0053]

[Table 1]

[0054]

[Table 2]

In the present embodiment, the bonding weight, the bonding weight correction amount, and the ultrasonic application time
Not corresponding to chip size, elasticity and thickness of adhesive,
Although the description has been made with these conditions fixed, the present invention is not limited to this, and instead of increasing the ultrasonic output amount, the bonding load or the application time of the ultrasonic vibration may be increased, Instead of using the output correction amount of the sound wave vibration, a bonding weight correction amount may be used. Of course, all conditions can be used together.

Regarding the thickness of the adhesive, instead of directly entering the bonding apparatus, the thickness of the IC chip was input, and the total thickness of the IC chip and the adhesive was input to the bonding apparatus. Thereafter, the thickness may be obtained by subtracting the thickness of the IC chip from the value. The elastic modulus of the adhesive is not the absolute value itself, and a parameter substituted by, for example, a relative ratio of the elastic modulus of each adhesive may be used. Further, the parameter may be replaced with a parameter obtained by simply combining the thickness and the elastic modulus of the adhesive, that is, the parameter such as the vibration of the IC chip.

[0057]

As described above in detail, the bonding method of the present invention determines the output amount of ultrasonic vibration from the compression diameter of the compression ball and the shape parameter of the capillary, and determines the size of the IC chip and the adhesive. The output correction amount of the ultrasonic vibration is determined from the elastic modulus of the adhesive, the thickness of the adhesive applied, and the parameters of the bonding position, and the output amount of the ultrasonic vibration is corrected with the output correction amount of the ultrasonic vibration to obtain the ultrasonic Since the correction output amount of the vibration is determined, the crimping diameter and crimping height of the crimping ball can be optimized.

The computer-readable recording medium on which the program for executing the bonding method of the present invention is recorded includes means for determining the output amount of ultrasonic vibration from the compression diameter of the compression ball and the shape parameter of the capillary; Means for determining the output correction amount of the ultrasonic vibration from the size, the elastic modulus of the adhesive, the coating thickness of the adhesive and the bonding position parameter, and the output amount of the ultrasonic vibration by the output correction amount of the ultrasonic vibration Means for making a correction to determine the correction output amount of the ultrasonic vibration, it is possible to determine bonding conditions in a very short time, and to increase the productivity of the semiconductor device.

The above-mentioned bonding apparatus uses a means for inputting the size of the IC chip, the elastic modulus of the adhesive, the thickness of the applied adhesive, and the bonding position parameter, and the ultrasonic wave from the compression diameter of the compression ball and the shape parameter of the capillary. Means for determining the output amount of vibration; means for determining the output correction amount of the ultrasonic vibration from the size of the IC chip, the elastic modulus of the adhesive, the applied thickness of the adhesive, and the bonding position parameter; Means for correcting the output amount of the ultrasonic vibration with the output correction amount of the ultrasonic vibration to determine a correction output amount of the ultrasonic vibration, it is possible to determine the bonding condition determination in a very short time, Since the crimping diameter and crimping thickness of the crimping ball can be optimized, it is possible to prevent short-circuiting between the electrodes due to poor bonding of the crimping ball and excessive diameter of the crimping ball It becomes possible, thereby improving the productivity of the semiconductor device.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a procedure of a bonding method according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a procedure of a conventional bonding method.

3A and 3B are views for explaining steps of a bonding method according to an embodiment of the present invention, wherein FIG. 3A is a cross-sectional view showing a capillary, and FIG. 3B is formed at the tip of a capillary and a fine metal wire. FIG. 7C is a cross-sectional view showing the initial ball formed, and FIG. 7C is a cross-sectional view showing a press-bonded ball formed by applying ultrasonic waves from a capillary.

FIG. 4 is a cross-sectional view for explaining the behavior of the IC chip during bonding.

5A and 5B are diagrams for explaining the behavior of the IC chip during bonding, and FIG. 5A is a plan view illustrating the vibration of the IC chip when bonding is performed in the vicinity of a side perpendicular to the vibration direction of ultrasonic vibration. (B) is a plan view showing the vibration of the IC chip when bonding is performed in the vicinity of a side parallel to the vibration direction of the ultrasonic vibration.

FIGS. 6A and 6B are diagrams for explaining an ultrasonic output correction factor, in which FIG. 6A is a plan view of an IC chip, and FIG. 6B is a diagram showing a relationship between a bonding position and an ultrasonic vibration output correction amount; It is a graph which shows a relationship.

FIG. 7 is a configuration diagram showing a bonding apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 hole diameter 2 chamfer diameter 3 chamfer angle 4 thin metal wire 5 initial ball 6 crimping diameter 7 crimping thickness 8 substrate 9 adhesive 10 capillary 11 IC chip 12 ultrasonic vibration 13 IC chip vibration 14 bonding load 17 ultrasonic vibration Direction 18 Vibration of IC chip 19 Vibration of IC chip 21 Crimp ball

Claims (3)

(57) [Claims] 1. A ball formed at the tip of a thin metal wire,
In a bonding method of pressing an electrode on a semiconductor element fixed on a substrate via an adhesive with a capillary and applying ultrasonic vibration to deform the ball into a press-bonded ball and press-bond the ball to the electrode, The output amount of the ultrasonic vibration is determined from the compression diameter of the ball and the shape parameter of the capillary, and the size of the semiconductor element, the elastic modulus of the adhesive, the applied thickness of the adhesive, and the bonding position are determined from the parameters. A bonding method comprising: determining an output correction amount of an ultrasonic vibration; and correcting the output amount of the ultrasonic vibration with the output correction amount of the ultrasonic vibration to determine a correction output amount of the ultrasonic vibration. 2. A ball formed at the tip of a thin metal wire,
A program for executing a bonding method in which a ball is pressed against an electrode on a semiconductor element fixed on a substrate via an adhesive and ultrasonic vibration is applied to deform the ball into a press-bonded ball and press-bond the ball to the electrode. A computer-readable recording medium having recorded thereon, a means for inputting a compression diameter of the pressure-bonded ball, a means for inputting a shape parameter of the capillary and a diameter of the thin metal wire, Means for determining the diameter of the ball from the diameter, means for inputting the size of the semiconductor element, the elastic modulus of the adhesive, the applied thickness of the adhesive and bonding position parameters, Means for determining the output amount of the ultrasonic vibration from the shape parameter of the capillary, the size of the semiconductor element, Means for determining the output correction amount of the ultrasonic vibration from the elastic modulus of the adhesive, the coating thickness of the adhesive and the bonding position parameter, and the output amount of the ultrasonic vibration by the output correction amount of the ultrasonic vibration A computer-readable recording medium storing a program for executing a bonding method including means for performing correction and determining a correction output amount of the ultrasonic vibration. 3. A ball formed at the tip of a thin metal wire,
A bonding apparatus for pressing an electrode on a semiconductor element fixed on a substrate via an adhesive with a capillary and applying ultrasonic vibration, deforming the ball into a press-bonded ball and pressing the ball against the electrode, A means for inputting a compression diameter of the pressure-bonded ball; a means for inputting a shape parameter of the capillary and a diameter of the fine metal wire; a means for determining a diameter of the ball from the pressure-bonded diameter and a diameter of the fine metal wire; Means for inputting the size of the semiconductor element, the elastic modulus of the adhesive, the applied thickness of the adhesive, and the bonding position parameter; and determining the output amount of the ultrasonic vibration from the crimping diameter and the shape parameter of the capillary. Means, the size of the semiconductor element, the elastic modulus of the adhesive, the thickness of the adhesive applied, and the bonding position parameters, Means for determining the output correction amount of the ultrasonic vibration, and means for determining the correction output amount of the ultrasonic vibration by correcting the output amount of the ultrasonic vibration with the output correction amount of the ultrasonic vibration. Characteristic bonding equipment.