JP3476643B2 - Manufacturing method of semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device in which a semiconductor chip and an electrode pad of a lead frame are bonded by a thermocompression wire bonding method. FIG. 7 shows a side view of a wire bonding portion of a wire in a conventional semiconductor device. FIG. 8 shows a state immediately before wire bonding for forming as shown in FIG.
A cross-sectional view after wire bonding is shown in FIG. In the figure, 1 is a semiconductor chip, 2 is an electrode pad made of aluminum or aluminum alloy, 3 is a wire, 4 is a crimping portion at the end of the wire 3, and the wire 3 before crimping is caused by discharge or the like as shown in FIG. The end is melted to form a substantially spherical press-bonded ball 3a. Reference numeral 5 denotes an adhesive portion where the crimping portion 4 at the end of the wire 3 and the electrode pad 2 are coupled, and reference numeral 6 denotes a capillary tool provided with an insertion hole 6a through which the wire 3 is inserted at the center. The corner of the lower insertion hole 6a is provided with a mounting space for a press-bonded ball by chamfering or the like. The connection between the semiconductor chip of the semiconductor device and the lead frame is a wire 3 mainly composed of gold, gold alloy or the like.
A substantially spherical pressure-bonded ball 3a is formed at the end of the wire by inserting a wire 3 into the insertion hole 6a of the capillary tool 6 while applying energy such as ultrasonic vibration.
a is pressed against the electrode pad 2 of the semiconductor chip 1, and the press-bonded ball 3 a is plastically flowed in the outer peripheral direction and deformed as shown in FIG. 9 to protrude between the electrode pad 2 and the lower end of the capillary tool 6. In this portion, the wire end and the electrode pad 2 are integrally coupled to form the adhesion portion 5. As described above, in the conventional wire bonding method, the pressing force is weak when the center portion is deformed, and it does not adhere, but only the outer periphery adheres, and the area of the adhesion portion is secured. However, it was necessary to increase the outer diameter to some extent, and there was a limit to reducing the wire interval. Japanese Patent Laid-Open No. 5-267382 discloses a means for securing the adhesion area and reducing the wire interval. In this method, the shape of the pressing part at the tip of the capillary tool is formed in an elliptical shape so that the outer shape of the adhesive part becomes elliptical, and the adhesive part at the end of the wire is aligned in the minor axis direction and spaced. Is designed not to become large. In this method, the processing of the tip of the capillary tool is complicated, and it is necessary to accurately control the direction during wire bonding, which complicates the operation. Japanese Patent Laid-Open No. 4-28241 “Method for Manufacturing Semiconductor Device” uses a method in which a press-bonded ball has an elliptical shape that is long in a direction parallel to the ultrasonic vibration direction of a capillary tool. It is shown. FIG. 10 is a plan view of a wire bonding portion of Japanese Patent Laid-Open No. 2-28241, and FIG. 11 is a plan view of a semiconductor device. In the figure, 12 is an electrode pad of a semiconductor device, 13 is a wire,
4 is a crimping part of the wire end. In this method, a method is adopted in which the ultrasonic vibration direction of the capillary tool is changed and pressed for each side of the semiconductor device. As shown in FIG. 10, the crimping portion 14 is elliptical,
The adhesion area of the electrode pad 12 is increased by increasing the area of the adhesion portion.
Can be arranged with a narrow interval. However, FIG.
As described above, in the semiconductor chip in which the crimping portions 14 are arranged on the four sides, the distance between the electrodes of the electrode pad 13 arranged on the vertical side and the electrode pad 13 arranged on the horizontal side is reduced. In order to cope with this, the arrangement pitch of the crimping part arranged on the vertical side and the crimping part arranged on the horizontal side are different, and in order to cope with this, is it possible to use two bonders with different vertical and horizontal orientations? Alternatively, wire bonding is performed by changing the direction for each of the vertical and horizontal directions, and there is an advantage that the wire interval can be reduced. However, for chips having pads on four sides, the vibration direction of the capillary tool during bonding is Complicated control that changes the direction every time is necessary, and the cost of the bonding apparatus increases. Japanese Patent Application Laid-Open No. 1-273325 discloses a method for manufacturing a semiconductor device using a capillary and a capillary by reducing the radius of the outer peripheral portion on the outer peripheral side from the diameter required for crimping the capillary tip. The method which suppressed that the external shape of this becomes large is shown. In order to reduce the size of the semiconductor device, it is important to reduce the size of the wire bonding portion. However, in the above-described conventional thermocompression bonding wire bonding of the semiconductor device, Since the adhesion part is formed in a ring shape at the part pressed against the lower end surface of the capillary tool, the outer shape is secured by securing the necessary area so that deformation and fracture do not occur against external forces such as vibration and tensile load. This has become a bottleneck in the miniaturization of semiconductor devices. In the method for forming the adhesion portion elliptical, processing of capillary tool, a complicated control during pressing, gutter a difficulty in productivity
There was a problem . The present invention secures the adhesion area of the crimping portion between the electrode pad and the wire of the semiconductor device, and the outer shape of the crimping portion is small, the lateral width with respect to the wire drawing direction is reduced, and the distance between the electrode pads is reduced. Manufactures semiconductor devices that can be narrowed and have sufficient strength against the load applied to the wire
An object of the present invention is to provide a method for manufacturing a semiconductor device . According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device , wherein a capillary tool for crimping a crimping ball is provided with an insertion hole through which the wire is inserted. A mounting space for mounting the press-bonded ball is formed at the lower end of the insertion hole, the volume of the mounting space is 40 to 60% of the volume of the press-bonded ball, and the press-bonded ball is formed at the tip of the inserted wire. Is brought into contact with the electrode pad, ultrasonic vibration is applied to the capillary tool from the initial stage of crimping, and a crimping ball is attached to the electrode pad.
The capillary tool is shifted to the outer edge of the semiconductor device
A method for manufacturing a semiconductor device to be worn. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 of the Invention The configuration of FIG. 1, FIG. 2, FIG.
Shown in FIG. 1 is a side sectional view of a wire bonding portion of a semiconductor device, FIG. 2 is a side sectional view of the wire bonding portion at the initial stage of crimping, and FIG. 3 shows an adhesion state of the adhesion portion after crimping of the wire bonding portion. It is a side view. In the figure, 21 is a semiconductor chip, 22 is an electrode pad of aluminum or aluminum alloy, 23 is a wire, 23a is a wire 23
A crimping ball formed at the end of the wire, 24 is a crimping portion after the wire 3 is crimped, and 24a is a protruding portion protruding between the lower end surface of the capillary tool of the crimping portion and the electrode pad. 2
6 is a capillary tool provided with a wire insertion hole 26a in the center, and 26b is a mounting space provided at the end of the capillary tool. In actual wire bonding, the wire 2
3 is made of gold or a gold alloy having a diameter of about 30 μm, and a pressure-bonding ball 23 a of about 50 μm is formed at the tip of the wire 23 by, for example, electric discharge. The insertion hole 26a of the wire of the capillary tool 26 is processed to about 40 μm, and the inner corner of the insertion hole 26a is chamfered at the lower end to form the crimp ball 23.
A mounting space 26b in which a is mounted is provided. In the crimping operation, the wire 3 on which the crimping ball 23a is formed is inserted into the insertion hole 26a of the capillary tool 26, the crimping ball 23a is mounted in the mounting space 26b, and the capillary tool 26 is placed at a predetermined position on the electrode pad 22. The pressure ball 23 a is pressed against the electrode pad 22. Bonding load at this time, the contact area deformation occurs of the ball, and about 10gf so as not to exceed the diameter of the initial squashed ball 23a. The deformation state at this time is shown in FIG. As shown in the drawing, the press-bonded ball 23 a is pressed against the electrode pad 22 by applying a load of about 10 gf to the press-bonded ball 23 a with the capillary tool 26. And press ball 2
Ultrasonic vibration with a steep rise so that the oscillation amplitude becomes 1/2 or more of the set value within 1 ms from the start of pressing against the electrode pad 3a is applied from the capillary tool 26 to the ball 23a to be in the state of FIG. Crimp so that. As described above, by pressing with a pressing force that is not so strong as compared with the prior art and applying ultrasonic vibration from the initial stage of pressing, an adhesive portion is generated from the center of the contact surface as shown in FIG. By further pressing, the press-bonded ball 2 is caused by plastic flow as shown in FIG.
Adhesive portions are formed on the entire bonding surface between 3a and the electrode pad 22, and strong adhesion strength can be obtained with a small bonding surface. If the rising characteristic of the ultrasonic vibration is slow, the adhesion starts after the deformation of the press-bonded ball progresses,
Since an adhesive part is not generated in the central part, it is desirable that the ultrasonic vibration rises quickly. In this embodiment, the amplitude that gives rise to the rise of ultrasonic vibration within 1 ms was applied at least 1/2 of the set value. However, it is possible to give more sharp rise of ultrasonic vibration from the central portion of the adhesion force. Strong adhesion can be formed. The present invention reduces the volume of the flat plate portion that protrudes between the end surface of the capillary tool 26 and the electrode pad when the pressure-bonding ball 23a mounted on the capillary tool 26 is pressed against the electrode pad 22 to be deformed. Is important, and the mounting space 2 with respect to the volume of the press-bonded ball 23a.
FIG. 4 shows the result of obtaining the bonding strength of the electrode pad of the press-bonded ball 23a while changing the volume ratio of 6b. From this result, the shear strength of the crimping portion is strong when the volume of the mounting space 26b is in the range of 20 to 60 percent of the crimping ball volume. The thickness of the wire 23 is intended for a fine unit of about 30 μm, and it is difficult to accurately process the mounting space of the capillary tool 26. Considering this point, the volume of the mounting space relative to the volume of the press-bonded ball is considered. 40-60 percent is a reasonable value. Further, stress concentration occurs at the end portion of the bonding interface of the flat portion that protrudes between the end face of the capillary tool 26 after the crimping and the electrode pad 22. In order to know the degree of stress concentration, samples with different thicknesses and lengths of the protruding portions are manufactured, and the results of calculating the edge stress of the flat portion by applying a load to the wire are shown in FIG. From this result, the thinner the flat portion, the less the stress concentration, and the longer the length, the smaller the stress concentration. The stress is saturated at the point where the thickness and length are almost equal. From the above, in order to reduce the wire bonding dimension of the semiconductor device, the mounting space 26a provided at the end of the capillary tool is provided with the crimp ball 2
3a volume relative to 40 to 60% of, by compression ball 23a is crimped applying ultrasonic vibrations within 1ms in contact with the electrode pads, the entire surface of the crimping portion is an adhesion portion, it tends to FIG 5 By pressing the crimping part so that the length of the flat part protruding from the capillary tool of the crimping part is around the flat part thickness, a crimping part with a small size can be formed. In addition, the first embodiment. In this case, the bonding load is set to 10 gf. However, if the contact of the pressure-bonded ball with the electrode pad can be detected within a range that is not affected by the wire feeding resistance on the apparatus, a smaller bonding load can be used. Therefore, an adhesive part with strong adhesion can be formed. Although the case where gold is used has been described above, since the deformation of the ball can be suppressed by using a material having a higher elastic limit, an adhesion portion having a stronger adhesion can be formed. Thus, the press-bonded ball 23 of the wire 23 is obtained.
By applying ultrasonic vibration from the initial stage of pressing a, by setting the pressing force to a low value and pressing, the formed adhesive part has a desired adhesion strength in a small area,
In addition, since the electrode pad can be made smaller, the semiconductor device can be made smaller. Embodiment 2 FIG. FIG. 6 shows the shape of the wire bonding portion of the second embodiment. In the second embodiment, the amount of protrusion in the lateral width direction of the bonding portion is reduced, and the amount of protrusion necessary for the stress concentrated portion is ensured. In the figure, 43 is a wire,
Reference numeral 44 denotes a crimping portion, and 44a denotes a flat portion. This configuration is a manufacturing method in which the final stop position of the capillary tool at the time of bonding is moved to a predetermined amount to the outer edge side of the semiconductor device
This can be achieved. A semiconductor device is manufactured by such a manufacturing method.
When it is manufactured, the wire 43 is extended from the bonding portion in the direction of the connection portion of the outer peripheral portion of the semiconductor device.
Only the flat portion 44a is secured to, the protruding width lateral width direction is reduced, the width of the electrode pads is small, becomes the bonding portion where the stress concentration due to the wire is avoided, dimensions
A reduced semiconductor device is obtained . According to the first aspect of the present invention, there is provided a semiconductor device .
The manufacturing method is such that a capillary tool for crimping a crimping ball has an insertion hole through which the wire is inserted at the center, and a mounting space for mounting the crimping ball is formed at the lower end of the insertion hole. The volume is 40 to 60% of the volume of the press-bonded ball, the press-bonded ball is formed at the tip of the inserted wire, the press-bonded ball is brought into contact with the electrode pad,
Ultrasonic vibration is applied to the capillary tool from the initial stage of crimping, and the final stop position of the capillary tool is located outside the semiconductor device.
A manufacturing method in which a predetermined amount is moved to the edge side,
A flat part is secured only on the back side in the extending direction in which the wire is extended from the bonding part in the direction of the connection part of the outer peripheral part of the semiconductor device, the stress concentration is reduced, and the bonding part with a small protruding width in the lateral width direction semiconductor instrumentation that has been reduced I Do
Can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of the present invention; It is a sectional side view of the crimping | compression-bonding part of this semiconductor device. FIG. 2 shows the first embodiment of FIG. It is a side view just after the press of the crimping | compression-bonding part of this semiconductor device. FIG. 3 shows a first embodiment of the present invention. It is sectional drawing which shows the shape of the crimping | compression-bonding state, and the adhesion condition of a junction part. FIG. 4 shows a first embodiment of the present invention. It is a graph which shows the relationship between the ratio of the volume of the crimping | compression-bonding ball | bowl of a crimping | compression-bonding part, and the volume of an installation space, and the elastic shear strength of an adhesion part. FIG. 5 is a graph showing the relationship between the width of the crimped portion and the thickness of the outer peripheral flat portion and the tensile stress at the joint interface end of the electrode pad. FIG. 6 shows a second embodiment of the present invention. It is a perspective view of the crimping | compression-bonding part. FIG. 7 is a side view of a crimp portion of a conventional semiconductor device. FIG. 8 is a side view showing a state immediately before crimping of a conventional semiconductor device crimping portion. FIG. 9 is a cross-sectional view showing a bonding state of a crimping portion of a conventional semiconductor device. FIG. 10 is a plan view of a crimp portion of another conventional semiconductor device. 11 is a plan view showing a state in which the conventional crimping portion of FIG. 10 is mounted on a semiconductor device. [Description of Symbols] 21 Semiconductor chip, 22 Electrode pad, 23 Wire, 23a Crimp space, 24 Crimp part, 24a Flat part, 25 Adhering part, 26 Capillary tool, 26a
Insertion hole, 26b mounting space, 43 wire, 44 crimping part, 44a flat part.

──────────────────────────────────────────────────── ----- Continuation of the front page (56) References JP-A-6-45392 (JP, A) JP-A-2-43747 (JP, A) JP-A-5-218147 (JP, A) JP-A-4- 48742 (JP, A) JP-A-8-8308 (JP, A) JP-A-10-4097 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/60 H01L 21 / 607

Claims (1)

(57) Claims 1. A method of manufacturing a semiconductor device in which a substantially spherical pressure-bonded ball is formed at the tip of a wire made of a fine metal wire, and the pressure-bonded ball is thermally bonded to an electrode pad of a semiconductor chip. The capillary tool for crimping the crimping ball is provided with an insertion hole through which the wire is inserted at the center, and a mounting space for mounting the crimping ball is formed at the lower end of the insertion hole. The volume of the mounting space is 40 to 60% of the volume of the press-bonded ball, and a press-bonded ball is formed at the tip of the wire inserted through the insertion hole of the capillary tool, and the press-bonded ball is brought into contact with the electrode pad. applying ultrasonic vibration to the capillary tool from step, the electrode pads
A capillary tool with a crimp ball attached to the semiconductor
A method of manufacturing a semiconductor device , wherein the semiconductor device is shifted to the outer edge side of the device and crimped .