JP2914337B2 - 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 and, more particularly, to an ultrasonic bonding wire bonding apparatus for electrically connecting a semiconductor device to a lead frame or a ceramic package using metal wires.

[0002]

2. Description of the Related Art As shown in FIGS. 4A and 4B, the structure of a conventional wire bonding apparatus is such that a metal wire 1 is provided on a side surface of a wire drawing hole 2 provided so as to communicate from the side surface to the bottom surface. It is inserted from the side and pulled out from the bottom. A bond flat (hatched portion in FIG. 4B), which is a portion for crushing the metal wire 1 having a lateral width W (W ≧ 60 μm), is formed on an extension of the wire drawing hole outlet side opening 3 of the wire drawing hole 2. ing. Also,
As shown in FIGS. 6A and 6B, the shape of the wire drawing hole outlet side opening 3 has a curve with a radius of curvature γ _{0 at} the tip of the bond flat 4 and the tip opposite to the bond flat 4 side. The part is flat. Actually, wire bonding is achieved by crushing the metal wire 1 with the bond flat 4 and applying an ultrasonic output to the bond flat 4 from an ultrasonic oscillator.

There is a known example of the structure of a wire bonding apparatus shown in FIGS. 5A and 5B (Japanese Utility Model Laid-Open No. 2-113335).

In this known example, a metal wire (gold wire) 1 communicating from a side surface to a bottom surface is provided, and a drawing hole (circular shape) 3 is provided, and a bond flat 4 is provided on the outer periphery of a bottom side opening 3 of the drawing hole. It has a structure. However, with the development of ICs that are becoming more and more highly integrated year by year, the pitch of wire bonding pads has become narrower, and it has become necessary to reduce the size of the bonding apparatus (wire bonding action portion). But,
Increasing the size of the bonding apparatus also reduced the surface area of the wire draw-out hole 2, which made it easier for the metal wire 1 to be rooted and hindered wire feeding during bonding. Therefore, in the prior art, as shown in FIGS.
Since the shape of the opening 3 on the exit side of the wire drawing hole is bullet-shaped, the wire feed is likely to be displaced in the lateral direction (perpendicular to the bonding direction) when bonding the metal wire 1. For this reason, wire sagging (curl) occurs in the appearance after wire bonding, and this causes wire shorting in narrow pitch bonding.

[0005]

The first problem is that in the wire bonding by the bonding apparatus of the related art, in which the opening of the wire drawing hole is a logical product gate type (bullet shape), the wire is laid horizontally at the time of bonding. Direction (direction perpendicular to the bonding direction), which tends to cause wire bowing (curl) on the appearance of bonding. Further, in a narrow pitch bonding product, a wire short occurs. The reason is that, at the wire outlet hole outlet side opening, the shape of the hole opening on the side opposite to the bond flat 4 side is flat, so that the degree of freedom of the wire at the time of bonding is large, and the lateral displacement easily occurs. is there.

[0006] The second problem is that the wedge tool having a circular opening on the exit side of the wire drawing hole in the known example tends to be rooted in narrow pitch bonding. Therefore, wire feeding at the time of bonding is not performed properly. The reason is that, in the narrow pitch bonding, the lateral width of the bonding apparatus becomes narrow, so that the surface area of the opening on the exit side of the wire drawing hole becomes small, and the clearance from the diameter of the metal wire becomes small.

[0007] The present invention enables stable wire feed without causing rooting or the like during wire bonding even when a bonding apparatus having a reduced width is used for narrow pitch bonding, and the bonded wire has a reduced appearance. Narrow P without curl or short
An object is to enable production of an AD pitch semiconductor device.

[0008]

SUMMARY OF THE INVENTION The feature of the present invention is that a metal
Pull out the wire from the wire drawing hole and bond flat
Bonder with Wedge Tool for Ultrasonic Pressure Bonding
A wire drawing hole exit portion
Wherein both the bond flat side of the curvature radius of gamma ₁ of
The bond flat side opposite to the curvature radius of the shape in the gamma ₂ in
Wire bonding apparatus that is formed and γ ₁ ≧ γ ₂
You . Also, the radius of curvature γ on the side opposite to the bond flat side
₂ is at least 1.2 times the diameter of the metal wire
It is desirable.

According to the present invention, as shown in FIGS. 4A and 4B, when the metal wire 1 is bonded to the semiconductor chip-side electrode PAD of the semiconductor device, the metal wire 1 is fed through the wire drawing hole of the wire bonding apparatus. The fixed metal wire 1 is fixed on the side γ ₁ of the opening 3 on the outlet side of the outlet 3 opposite to the bond flat 4. Therefore, the lateral displacement of the metal wire 1 at the time of bonding is prevented, and the metal wire 1 does not have a sink, a curl, or a short-circuit defect in the appearance after the completion of the wire bonding.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIGS. 1A and 1B are a side view and a bottom view, respectively, for explaining the configuration of a wire bonding apparatus according to a first embodiment of the present invention. The configuration of the wire bonding apparatus according to the first embodiment of the present invention is shown in FIGS.
As shown in FIG. 1, a wire pull-out hole 2 for inserting the metal wire 1 is provided, and a surface bond flat 4 for ultrasonically bonding the metal wire 1 is provided at an exit side of the draw-out hole 2. In addition, the shape of the opening 3 on the outlet side of the wire drawing hole of the drawing hole 2 has a curve with a radius of curvature γ _{1 on} the bond flat 4 side and a curve with a radius of curvature γ ₂ on the side opposite to the bond flat 4 side. It has a structure having. The radii of curvature γ ₁ , γ ₂ of the opening 3 on the exit side of the wire drawing hole are in a relationship of γ ₁ ≧ γ ₂ and have a size of γ ₂ ≧ (diameter of the metal wire 1 × 1.2). . Further, γ ₁ and γ ₂ are set in a range having a thickness sufficient to secure the strength of the wire bonding apparatus itself with respect to the width W of the wire bonding apparatus. For gamma _1, the position of the radius of curvature center of the gamma ₁ is present a length F of the bond Flat 4 so as to be F ≧ 40 [mu] m. curvature center of the gamma ₂ is located at a position where the intensity of the bonding apparatus itself can be sufficiently secured. Tungsten carbide or titanium carbide is desirable as the material of the wire bonding apparatus.

Next, the operation of the first embodiment of the present invention will be described with reference to the drawings.

FIGS. 2A to 2D are a side view and a bottom view showing the operation of the first embodiment of the present invention in the order of steps for explaining the operation. The operation of the first embodiment of the present invention is as follows. First, as shown in FIG. 2A, the metal wire 1 inserted from the side entrance to the bottom exit of the wire draw-out hole 2 is firstly moved by the wire bonding apparatus. The wire bonding is performed by being sent onto the semiconductor chip side electrode PAD5 which is a bonding point, crushed by the bond flat 4, and applying ultrasonic output. At this time, as shown in FIG.
The metal wire 1 inside the bonding apparatus has a radius of curvature γ ₂ (γ ₂ = 38 μm) of the opening 3 on the exit side of the wire drawing hole.
The lateral displacement is suppressed at the portion, so that the metal wire 1 crushed by the bond flat 4 is parallel to the bonding direction. Next, as shown in FIG. 2C, the semiconductor chip side electrode PA which is the first bonding point
After the wire bonding to D5 is completed, the wire bonding apparatus is moved to the external terminal side electrode PAD6, which is the second bonding point, with the metal wire 1 inserted in the wire bonding apparatus. The wire bonding to the second bonding point is performed in the same manner as the wire bonding to the first bonding point. At this time, the effect of suppressing the lateral displacement of the metal wire 1 also shows the same effect. Next, FIG.
As shown in (d), when the wire bonding to the second bonding point is completed, the metal wire 1 is cut at the radius of curvature γ _{1 of} the wire drawing hole exit side opening 3,
The bonding operation for one wire is completed. Hereinafter, similarly, the second and subsequent wire bondings are performed.

Next, an example of the first embodiment of the present invention will be described with reference to FIGS. 1 (a) and 1 (b).

As shown in FIGS. 1 (a) and 1 (b), the embodiment of the first embodiment of the present invention has a wire drawing hole 2 for communicating a metal wire 1, and this wire drawing hole 2 Is provided with a surface bond flat 4 for ultrasonically bonding the metal wire 1 to the exit side. Also has a radius of curvature gamma ₁ of semicircular wire lead-out hole outlet opening 3 wire drawer hole 2 is the bond flat side, the radius of curvature gamma ₂ semicircles on the side opposite the bond Flat 4 side It has a structure having. Here, the metal wire 1 is made of Al-
It is made of a Si alloy and has a diameter of 30 μm. The radii of curvature γ ₁ , γ ₂ formed in the wire drawing hole exit opening 3 are γ ₁ = 48 μm, γ ₂ = 38 μm, and the distance between the centers of γ ₁ , γ ₂ is about 60 μm. ing. The width W of the wire bonding apparatus is 64 μm, and the width of the bond flat 4 has the same width.
The vertical width T of the wire bonding apparatus is about 200 μm, and its material is tungsten carbide.

Next, the operation of the example of the first embodiment of the present invention will be described in detail with reference to FIGS.

The metal wire 1 (Al-Si alloy, 30 μm in diameter) inserted from the side entrance to the bottom exit of the wire drawing hole 2 is first subjected to a first bonding by a wire bonding apparatus as shown in FIG. The wire bonding is performed by being sent to the semiconductor chip side electrode PAD5 which is a point, crushed by the bond flat 4, and applying an ultrasonic output. At this time, as shown in FIG. 2 (b), the metal wire 1 inside the bonding apparatus is restrained from swaying at the radius of curvature γ ₂ (γ ₂ = 38 μm) of the opening 3 on the exit side of the wire drawing hole. Therefore, the metal wire 1 crushed by the bond flat 4 is parallel to the bonding direction. Next, as shown in FIG. 2C, the semiconductor chip side electrode PA which is the first bonding point
After the wire bonding to D5 is completed, the wire bonding apparatus is moved to the external terminal side electrode PAD6, which is the second bonding point, with the metal wire 1 inserted in the wire bonding apparatus. External terminal side electrode PAD6
Wire bonding to semiconductor chip side electrode PAD5
It is performed in the same manner as wire bonding on the upper side. At this time, the effect of suppressing the lateral displacement of the metal wire 1 also shows the same effect. Next, as shown in FIG. 2 (d), After wire bonding to the external terminal side electrodes PAD6 is complete, the metal wire 1 is cut at a radius of curvature gamma ₁ portion of the wire lead-out hole outlet opening 3, the wire 1 The main bonding operation is completed. Hereinafter, the second and subsequent wire bondings are performed in the same manner as the first wire bonding.

FIGS. 3A and 3B are a side view and a bottom view, respectively, for explaining the configuration of a wire bonding apparatus according to a second embodiment of the present invention. FIGS. 4A and 4B show the configuration of a wire bonding apparatus according to a second embodiment of the present invention.
Is the same as that of the first embodiment, except that the radii of curvature γ ₁ and γ ₂ formed in the extraction hole opening 3 are γ ₁ = γ ₂ (= 38 μm) as shown in FIG. Therefore, the operation of the second embodiment and the effects of the invention are the same as those of the first embodiment. Further, the effect of the present invention is not limited to the Al-Si alloy as long as the diameter of the metal wire 1 is 35 μm or less, and can be applied to the Au wire. further,
The wire bonding apparatus according to the present embodiment has a narrow pad pitch bonding (single row 100 μm or less, staggered 80 μm).
m or less) as well as bonding with a wide pad pitch (bonding pitch). That is, the width of the wire bonding apparatus according to the present embodiment is 30 to 1
The diameter of the metal wire 1 is 20 μm and the vertical width is in the range of 100 to 400 μm. The radius of curvature of the wire drawing hole exit opening 3 can be arbitrarily set depending on the diameter of the metal wire 1 to be applied.
Here, γ ₂ is γ ₂ ≧ (wire diameter × 1.2), and γ 2
The relationship of ₁ ≧ γ ₂ is satisfied. The material of the wire bonding apparatus itself of the present invention can be titanium carbide in addition to tungsten carbide. The feed angle of the wire withdrawal hole for inserting metal wire is 3
There are three types: 0 °, 45 °, and 60 °.

[0019]

The first effect is that it is possible to suppress the lateral displacement of the wire during wire bonding. As a result, good bonding can be achieved without wire sagging, curling, and short-circuiting in appearance after wire bonding. The reason for this is that the radius of curvature γ ₁ ,
The gamma ₂ is provided, the curve radius of curvature gamma ₂ with a radius of curvature gamma ₁ and opposite side of the bonding flat side gamma ₂ ≧ (wire diameter ×
This is because of the relationship of 1.2).

The second effect is that the width of the wire bonding apparatus is reduced in order to cope with the narrow pad pitch bonding, and even if the width of the wire drawing hole is reduced along with the bonding, it is unlikely to take root during the wire bonding. is there. This means that a stable wire feed can be maintained. The reason is that the radius of curvature γ ₁ ,
opening shape because of the γ ₁ ≧ γ ₂ relation in gamma ₂ is because the surface area than that of the circle becomes wider.

A third effect is that the strength of the wire bonding apparatus (mainly, the wire feed portion) is increased. As a result, the durability of the wire bonding apparatus is increased and the wire bonding apparatus can be applied to mass production of multi-pin bonding products. The reason is that the radii of curvature γ ₁ and γ ₂ provided at the opening on the outlet side of the wire drawing hole satisfy the relations of γ ₁ ≧ γ ₂ and γ ₂ ≧ (wire diameter × 1.2), This is because the thickness with respect to the opening of the wire bonding apparatus can be sufficiently ensured compared to the case of γ ₁ <γ ₂ or a circle.

[Brief description of the drawings]

FIGS. 1A and 1B are a side view and a bottom view illustrating a configuration of a wire bonding apparatus according to a first embodiment of the present invention.

FIGS. 2A to 2D are a side view and a bottom view showing an operation of the first embodiment of the present invention in a process order.

FIGS. 3A and 3B are a side view and a bottom view illustrating a configuration of a wire bonding apparatus according to a second embodiment of the present invention.

FIGS. 4A and 4B are bottom views illustrating the effect of the present invention.

5A and 5B are a side view and a bottom view illustrating an example of a configuration of a conventional wire bonding apparatus.

FIGS. 6A and 6B are a side view and a bottom view illustrating another side of the conventional wire bonding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal wire 2 Wire drawing hole 3 Wire drawing hole exit side opening 4 Bond flat 5 Semiconductor chip side electrode PAD 6 External terminal side electrode PAD

Claims (2)

(57) [Claims] 1. A wedge tool for drawing a metal wire from a wire drawing hole and ultrasonically compressing it at a bond flat portion.
In the wire bonding apparatus having the above, a half of the curvature of the exit portion of the wire drawing hole on the bond flat side is provided.
Opposite side of the bond flat side with diameter of gamma ₁
Wire bonding apparatus, wherein the radius of curvature is by cutlet γ ₁ ≧ γ ₂ formed on the gamma ₂ of. 2. A half-curvature on the side opposite to the bond flat side.
Diameter gamma ₂ is small with 1.2 times the diameter of the metal wire
Wire bonding apparatus according to claim 1, wherein there.