JPH09134932A - Wire bonding and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent damage to wire loops accompanying the resonance phenomenon of the wire loops. SOLUTION: This bonding device 10 is formed into a structure, wherein a capillary 21 for holding insertedly a wire 5 is driven while being controlled and bonding points on electrodes on a semiconductor pellet and bonding points on leads of a lead frame 3 are connected with each other using the wire. In this case, the device 10 is provided with a resonance frequency calculating part 16 for calculating the resonance frequency of wire loops, which are formed between the bonding points by the wire, an ultrasonic frequency storage part 17 for storing the ultrasonic frequency of ultrasonic vibrations which are given to the capillary 21, a comparison decision part 18, which compares the above resonance frequency with the above ultrasonic frequency and decides the concord between both of the resonance and ultrasonc frequencies or the discord between both of the resonance and ultrasonic frequencies, and a control device 14, which drives the above capillary while controlling the capillary for executing a wire bonding in the case where the above resonance frequency is discordant from the above ultrasonic frequency in the part 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding method and wire bonding apparatus in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In a wire bonding process in a semiconductor manufacturing process, as shown in FIGS. 5 and 6, a plurality of electrodes 2 of a semiconductor pellet 1 connect a wire 5 to each of a plurality of leads 4 of a lead frame 3. Electrically connected to each other, and a wire loop 6 is formed between them. This wire bonding is performed by a wire bonding device.

That is, in the wire bonding apparatus, a discharge is generated between the wire 5 protruding from the tip of the capillary and the torch electrode to form a molten ball at the tip of the wire 5, and this ball is attached to the electrode 2 of the semiconductor pellet 1. After joining at the bonding point, the capillary is moved onto the lead 4 of the lead frame 3 while leading out the wire 5, and the wire 5 is joined at the bonding point of the lead 4 to electrically connect the electrode 2 and the lead 4. That is, wire bonding is performed. The wire 5 and each bonding point of the electrode 2 and the lead 4 are joined by ultrasonically vibrating the capillary.

[0004]

In the wire bonding apparatus described above, the diameter of the wire 5 for bonding the bonding point of the electrode 2 of the semiconductor pellet 1 and the bonding point of the lead 4 of the lead frame 3, the material, or the length of the wire loop 6 is used. In some cases, the resonance frequency of the wire loop 6 matches the ultrasonic frequency of the capillary of the wire bonding apparatus, and the wire loop 6 may resonate.
Then, as a result of the resonance phenomenon of the wire loop 6, the bonding portion 7 between the electrode 2 and the lead 4 in the wire loop 6 may be damaged, resulting in defective bonding.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wire bonding method and a wire bonding apparatus, which have been made in consideration of the above circumstances, and which can prevent defective bonding due to a resonance phenomenon of a wire loop.

[0006]

According to a first aspect of the present invention, the position of the bonding point is determined so that the resonance frequency of the wire loop formed between the bonding points does not match the mechanical frequency of the wire bonding apparatus. Then, the bonding is performed.

According to a second aspect of the present invention, in the first aspect of the invention, the mechanical frequency is a frequency of ultrasonic vibration applied to the capillary during wire bonding.

According to a third aspect of the present invention, in a wire bonding apparatus for driving and controlling a capillary for inserting and holding a wire, and connecting the bonding points by using the wire, the wire is formed between the bonding points. Resonance frequency calculation means for calculating the resonance frequency of the wire loop, storage means for storing the mechanical frequency of the wire bonding device, and the resonance frequency and the mechanical frequency are compared, and it is determined whether they match or not. The comparison determination means and the control means for driving and controlling the capillary based on the result of the comparison determination means are included.

According to a fourth aspect of the present invention, in the third aspect of the invention, the control means performs the wire bonding when the comparison determination means determines that the resonance frequency and the mechanical frequency do not match. In order to do so, the capillaries are driven and controlled.

[0010] The invention described in claim 5 is the invention according to claim 3 or 4.
In the invention described in (1), the control means changes the wire loop length to determine the resonance frequency of the wire loop and the mechanical frequency when the comparison determination means determines that the resonance frequency and the mechanical frequency match. The capillaries are driven and controlled to bring the two into disagreement.

The invention according to claim 6 is the invention according to claim 3 or 4.
In the invention described in (1), the control device stops the driving of the capillary when the comparison determination unit determines that the resonance frequency and the mechanical frequency match.

The invention according to claim 7 is the invention according to any one of claims 3 to 6, wherein the mechanical frequency is a frequency of ultrasonic vibration applied to the capillary during wire bonding. is there.

The first to seventh aspects of the present invention have the following effects. Since the wire bonding is performed so that the resonance frequency of the wire loop formed between the two bonding points and the mechanical frequency of the wire bonding device do not match with each other, defective bonding due to resonance of the wire loop is prevented. it can.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of a wire bonding apparatus according to the present invention.
FIG. 2 is a partial plan view showing a part of the semiconductor pellet and the lead of FIG. FIG. 3 is an enlarged view of part III in FIG. FIG. 4 is a flowchart showing a wire bonding method implemented by the wire bonding apparatus of FIG.
FIG. 5 is a plan view showing a wire-bonded semiconductor pellet and a lead frame. FIG. 6 shows VI of FIG.
FIG. 6 is a cross-sectional view taken along the line VI.

The wire bonding device 10 connects a bonding point on the electrode 2 of the semiconductor pellet 1 and a bonding point on the lead 4 of the lead frame 3 with a wire 5 to form a wire loop 6 therebetween. The guide rail 11, the XY table 12,
Bonding head 13, control device 1 as control means
4, bonding point storage unit 15, resonance frequency calculation unit 16 as resonance frequency calculation unit, ultrasonic frequency storage unit 17 as storage unit, comparison determination unit 1 as comparison determination unit
8 is configured.

The guide rails 11 guide the conveyance of the lead frame 3 on which the semiconductor pellets 1 are mounted in the previous step, and are installed in pairs.

The XY table 12 is installed on the side of the guide rail 11 corresponding to the bonding area, and is movable in the carrying direction of the guide rail 11 and the direction orthogonal thereto. The bonding head 13 is placed on the XY table 12.

The bonding head 13 includes a bonding arm 19 and a torch electrode 20, and a capillary 21 for inserting and holding the wire 5 is attached to the tip of the bonding arm 19. The bonding arm 19 is moved up and down by an arm driving mechanism (not shown). Further, the torch electrode 20 has a tip end movable to a position directly below the capillary 21 to cause an electric discharge between the wire 5 protruding from the capillary 21 and the torch electrode 20, and the molten ball 22 is attached to the tip of the wire 5. To form.

The bonding point storage unit 15 stores the positions of the bonding points on the plurality of electrodes 2 in the semiconductor pellet 1 and the positions of the bonding points on the plurality of leads 4 in the lead frame 3, respectively. There is.

The control device 14 is electrically connected to the XY table 12, the bonding head 13, the bonding point storage unit 15, the resonance frequency calculation unit 16 and the comparison and determination unit 18, and these XY table 12 and the bonding head 1 are connected.
3. Control the resonance frequency calculation unit 16 and the comparison determination unit 18.

That is, the control device 14 operates the bonding arm 19 of the XY table 12 and the bonding head 13 to the bonding point stored in the bonding point storage unit or the bonding point whose position is corrected as described later. Then, the capillaries 21 are sequentially moved to perform wire bonding. In this wire bonding operation, the capillary 21 in which the wire 5 having the molten ball 22 formed at the tip is inserted and held is lowered onto the electrode 2 of the semiconductor pellet 1, and the molten ball 22 at the tip of the wire 5 is
Ultrasonic vibration is applied to the bonding point of the electrode 2 while bonding it under pressure, and then the capillary 21 is moved onto the lead 4 of the lead frame 3 according to a predetermined movement trajectory, and the wire 5 is bonded to the bonding point of the lead 4. Bonding by applying ultrasonic vibration while pressing it to
This is done by raising the capillary 21 by a predetermined amount and cutting the wire 5.

As a result, the electrode 2 and the lead 4 are
The wires 5 are connected by a wire loop 6 formed in a loop shape.

Here, the ultrasonic frequency storage unit 17 stores the frequency of ultrasonic vibration (ultrasonic frequency) as mechanical vibration applied to the capillary 21 via the bonding arm 19 during wire bonding. ing.

Further, the control device 14 includes the resonance frequency calculation unit 1
6, the resonance frequency calculation unit 16 controls the distance between the bonding points of the electrode 2 and the lead 4, the wire loop 6
Based on the conditions such as the loop shape, the wire loop length required for loop formation is calculated, and then based on this wire loop length, the diameter of the wire 5 and the material of the wire 5,
The resonance frequency of the formed wire loop 6 is calculated. The distance between the bonding points of the electrode 2 and the lead 4 is calculated based on the information stored in the bonding point storage unit 15.

Further, the control device 14 controls the comparison / determination unit 18, which compares the resonance frequency calculated by the resonance frequency calculation unit 16 with the ultrasonic frequency stored in the ultrasonic frequency storage unit 17. The sound wave frequency is compared to determine whether or not they match. The determination result of the comparison / determination unit 18 is output to the control device 14. In the present specification, the term “resonance frequency and ultrasonic frequency match” includes not only the case where the two completely match but also the case where the resonance frequency falls within a certain range with respect to the ultrasonic frequency. .

The controller 14 stores the data in the bonding point memory 15 when the resonance frequency of the wire loop 6 and the ultrasonic frequency applied to the capillary 21 do not match in the judgment result of the comparison judgment unit 18. The capillary 21 is moved to each bonding point on the electrode 2 and the lead 4 to perform wire bonding. When the resonance frequency matches the ultrasonic frequency, the controller 14 causes the lead 4
The bonding point on the upper side corresponds to the forming direction of the wire loop 6 (see FIG. 2).
The position is corrected by the shift amount L in A), and the position-corrected bonding point on the lead 4 and the bonding point on the electrode 2 stored in the bonding point storage unit 15 are wire-bonded using the wire 5. . The above shift amount L
Is a value that can be programmed in the control device 14, and in the illustrated example, is a value obtained by ΔX movement in the X direction and ΔY movement in the Y direction in which the XY table 12 moves. The resonance frequency is set to be inconsistent with the ultrasonic frequency applied to the capillary 21.

Next, the operation will be described with reference to FIG. When a start command is input to the control device 14, the control device 1
4 controls the resonance frequency calculation unit 16, and the resonance frequency calculation unit 16 stores the bonding point on the electrode 2 of the semiconductor pellet 1 stored in the bonding point storage unit 15 and the bonding point on the lead 4 of the lead frame 3. The loop wire length of the wire loop 6 is calculated from the information about
(Step), subsequently, the resonance frequency of the wire loop 6 is calculated (Step). Next, the control device 14
Controls the comparison determination unit 18, and the comparison determination unit 18
The resonance frequency of the wire loop 6 calculated by the resonance frequency calculation unit 16 is compared with the ultrasonic frequency stored in the ultrasonic frequency storage unit 17 and applied to the capillary 21 to determine whether they match or not match. Do (step).

When the comparison determination unit 18 determines that the resonance frequency and the ultrasonic frequency do not match, the control device 14 performs wire bonding at the bonding point stored in the bonding point storage unit 15 (step). , The position of the bonding point on the lead 4 is corrected in the forming direction A of the wire loop 6 by an amount L (step), and the bonding point on the electrode 2 stored in the bonding point storage unit 15 Wire bonding is performed with the bonding point on the lead 4 whose position has been corrected (step).

The controller 14 determines whether or not the wire bonding performed this time is at the final bonding point on the electrode 2 and the lead 4 (step), and if not, the same semiconductor pellet 1 The wire bonding described above is repeated, and in the final case, the wire bonding for this semiconductor pellet 1 is completed.

According to the above embodiment, the resonance frequency of the wire loop 6 formed between the bonding points of the electrode 2 of the semiconductor pellet 1 and the lead 4 of the lead frame 3 and the bonding arm 19 are applied to the capillary 21. Since wire bonding is performed using the wire 5 in a state where the frequency of ultrasonic vibration (ultrasonic frequency) does not match, the wire loop 6 resonates during wire bonding, including during bonding of another set. Without doing so, it is possible to prevent a bonding failure such that the joint portion 7 (FIG. 6) of the wire loop 6 with the electrode 2 and the lead 4 is damaged by the resonance phenomenon.

In the above embodiment, particularly in FIG. 4, an example of calculating the next wire loop length after the wire loop is formed between one set of bonding points has been described.
The loop wire lengths and resonance frequencies of all the wire loops formed in each semiconductor pellet may be obtained before bonding.

In the above embodiment, the comparison / determination unit 1
Although the case where the bonding point position on the lead 4 is corrected when it is determined that the resonance frequency and the ultrasonic frequency match in 8 has been described, the bonding point position on the electrode 2 side may be corrected. . Alternatively, the wire bonding may be stopped by stopping the driving of the capillary 21 without correcting the bonding point position.

Further, in the above embodiment, the case where the ultrasonic vibration is applied to the capillary 21 via the bonding arm 19 has been described as the mechanical vibration. There are various vibrations caused by the drive of the wire bonding apparatus 10, such as vibrations caused by the movement of the bonding head 13 caused by 12 and vibrations caused by the conveyance of the lead frame 3 by the guide rails 11. Therefore, the ultrasonic frequency storage unit 17 stores the frequencies of the various mechanical vibrations described above, and the comparison and determination unit 18 compares and determines the frequencies of the respective mechanical vibrations and the resonance frequency of the wire loop 6. You can

Further, in the above embodiment, the wire bonding apparatus 10 wire bonds the bonding points of the electrode 2 of the semiconductor pellet 1 and the bonding points of the leads 4 of the lead frame 3 to each other. It can also be applied to wire bonding between bonding points or bonding points of different leads 4.

[0035]

As described above, according to the wire bonding method and the wire bonding apparatus of the present invention, it is possible to prevent defective bonding due to the resonance phenomenon of the wire loop.

[Brief description of the drawings]

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

FIG. 2 is a partial plan view showing a part of the semiconductor pellet and the lead shown in FIG.

FIG. 3 is an enlarged view of III in FIG. 2.

4 is a flowchart showing a wire bonding method performed by the wire bonding apparatus of FIG.

FIG. 5 is a plan view showing a wire-bonded semiconductor pellet and a lead frame.

FIG. 6 is a sectional view taken along the line VI-VI of FIG. 5;

[Explanation of symbols]

 1 Semiconductor Pellet 2 Electrode 3 Lead Frame 4 Lead 5 Wire 6 Wire Loop 10 Wire Bonding Device 14 Control Device 16 Resonance Frequency Calculation Unit 17 Ultrasonic Frequency Storage Unit 18 Comparison Judgment Unit 19 Bonding Arm 21 Capillary A Wire Loop Forming Direction L Amount of shift

Claims (7)

[Claims] 1. A wire bonding method, wherein the bonding point position is determined so that the resonance frequency of the wire loop formed between the bonding points does not match the mechanical frequency of the wire bonding apparatus. 2. The wire bonding method according to claim 1, wherein the mechanical frequency is a frequency of ultrasonic vibration applied to the capillary during wire bonding. 3. In a wire bonding apparatus for driving and controlling a capillary for inserting and holding a wire and connecting the bonding points by using the wire, a resonance frequency of a wire loop formed by the wire between the bonding points is calculated. Resonance frequency calculation means, storage means for storing the mechanical frequency of the wire bonding apparatus, comparison determination means for comparing the resonance frequency and the mechanical frequency, and determining whether they match or not, the comparison A wire bonding apparatus comprising: a control unit that drives and controls the capillary based on the determination result of the determination unit. 4. The wire bonding apparatus according to claim 3, wherein the control means drives and controls the capillary to perform wire bonding when the comparison determination means determines that the resonance frequency and the mechanical frequency do not match. . 5. The control means changes the wire loop length and determines the resonance frequency of the wire loop and the mechanical frequency when the comparison determining means determines that the resonance frequency and the mechanical frequency match. The wire bonding apparatus according to claim 3 or 4, wherein the capillaries are drive-controlled to bring them into a non-coincident state. 6. The wire bonding apparatus according to claim 3, wherein the control device stops the driving of the capillary when the comparison and determination means determines that the resonance frequency and the mechanical frequency match. 7. The wire bonding apparatus according to claim 3, wherein the mechanical frequency is a frequency of ultrasonic vibration applied to the capillary during wire bonding.