JP2780498B2 - Single point bonding tool - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single point bonding tool, and more particularly to a bonding tool of a manufacturing apparatus for performing a single point bonding of a semiconductor device having a projection type electrode (bump).

[0002]

2. Description of the Related Art Conventionally, this kind of bonding tool has
As shown in the external view of FIG. 5A, the crimping surface 8d of the tool 1b is in contact with the surface of the tip of the lead of the film carrier tape, that is, the portion where the thermocompression bonding is performed with the semiconductor element. Is flat or the tip of the tool 1c has a cross-shaped protrusion or an X-shaped protrusion (Nikkei Microdevice, February 1990, P.
106- and electronic materials, July 1989, P50-5
4).

That is, in the case of a tool having a flat tool tip crimping surface 8d shown in FIG. 5 (a), thermocompression is performed by upsetting with a so-called parallel tool. Mechanically, it was as if a kind of uniform forced displacement was applied to the thermocompression bonding part, leaving a flat shape according to the shape of the crimping surface. Also, the cross shape shown in FIG.
In a tool having a crimped surface shape of a letter-shaped convex portion, this convex portion is provided in consideration of the transmission efficiency of ultrasonic vibration. Was transcribed, and was mechanically deformed by indentation with a wedge having a certain apex angle.

[0004]

In the conventional bonding tool described above, first, as shown in FIG. 5A, when the crimping surface of the tool tip is flat, as shown in FIG.
The elementary analysis can be applied to the thermocompression bonding of the lead 3 and the bump 4 as shown in FIG. 6 (a) is a perspective view showing the thermocompression bonding conditions, FIG. (B), as seen from (c) perspective A (x ₁ direction) in the figure, respectively (a), and viewpoint B (x ₂ direction) It is a figure showing balance of power of a two-dimensional section. In FIG. 6, σ _n is the rolling force or deformation resistance when the tool 1 is lowered, μ is the friction coefficient of the joint, a and h are the lead width and thickness, and b is the length of the thermocompression bonding portion in the longitudinal direction of the lead. ,.

As a result, a distribution of deformation resistance generated in a portion of the lead end of the film carrier tape to which the thermocompression bonding is performed is obtained, and an uneven distribution as shown in FIGS. 7 and 8 is obtained. FIG. 7 is a diagram showing the rolling force distribution viewed from the viewpoint A,
FIG. 3A shows the deformation resistance distribution and the rolling force distribution, FIG. 3B shows the shearing force generated on the semiconductor element substrate, and FIG. 3C shows the deformation resistance distribution by numerical values. Indicates the shear yield stress. 8A and 8B are diagrams showing the rolling force distribution viewed from the viewpoint B. FIG. 8A shows the deformation resistance distribution and the rolling force distribution, and FIG. 8B shows the relationship between the stress generated at the joint. FIG. 3C is a diagram showing the deformation resistance distribution by numerical values.

Therefore, when a uniform required amount of deformation, that is, a forced displacement is applied to the lead while the flat end face is formed, a rolling force corresponding to the above-described deformation resistance acts on the semiconductor element substrate. In the case of FIG. 7, a shear flow is generated by a moment load M = P · l as shown in FIG. Here, P is a force obtained by replacing the rolling force distribution with an equivalent concentrated load, and 1 is a moment arm. In the case of FIG. 8, the profile of the rolling force acts to push the wedge as shown in FIG. 8A, and as a result, as shown in FIG. However, there is a drawback that a strong tensile force acts on the surface of the semiconductor element substrate, and the tensile force induces cracks, growth, and progress in the semiconductor element substrate that promotes defects such as bump peeling.

When the crimping surface of the tool tip has a cross-shaped or X-shaped convex as shown in FIG. 5B, the deformation resistance distribution in the flat shape described above is strong. The portion exhibiting the resistance is pushed back more strongly, and a stronger tensile force acts on the semiconductor element substrate, which further promotes crack generation and growth, and induces defects such as bump peeling.

In general, in the manufacture of a semiconductor device which performs bonding by a thermocompression bonding process, it is necessary to form a new surface (slip surface) due to strong tensile stress at the bonding interface between the bump and the lead, that is, to promote plastic flow. For this purpose, it is necessary to apply a strong rolling force to the whole or a local portion of the bonding portion, but the rolling force for promoting the good bonding is simultaneously applied to the semiconductor element substrate. The problem is that there is always the contradiction of creating a strong tensile stress field.

[0009]

According to the present invention, there is provided a single point bonding tool comprising a projection type electrode provided on one of a leading end of a film carrier tape and an external lead electrode pad provided on a semiconductor element. In a single-point bonding tool of a semiconductor manufacturing apparatus that performs single-point bonding in a semiconductor device having a thermocompression bonding process, a lead is provided on a crimping surface at a tip portion of the bonding tool which is in contact with a portion of the surface of the lead where thermocompression is performed. And has a groove of an arbitrary depth and width located at the center of the crimping surface. Alternatively, the bonding tool has at least one step-like step in the longitudinal direction from the portion in contact with the free end surface of the tip of the lead on the tip pressing surface of the bonding tool.

[0010]

Next, the present invention will be described with reference to the drawings. FIG. 1 shows a first embodiment of the present invention. FIG. 1 (a) shows a semiconductor device 5 in which a bump 4 formed on a semiconductor element 5 is aligned with a lead 3 formed on a film carrier tape, and is fixed to an arm 2. FIG. 2B is a schematic view showing a state in which thermocompression bonding is performed by the bonding tool 1 shown in FIG.
FIG. 4 is an enlarged external view showing that a groove 7 having a width W is formed in parallel with the arm 2 and at a position substantially at the center of the crimping surface 8.

The distribution of the rolling force by the parallel tool in the cross section viewed from the viewpoint B in FIG. 6A is analyzed from FIG.
The semiconductor element substrate 5 as shown in FIGS.
As shown in FIG. 3B, a distribution is formed in which the wedge is pushed in, and a tensile stress field which promotes generation of a new surface is formed at the bonding interface between the bump 4 and the lead 3, thereby contributing to the bonding property. However, at the same time, the semiconductor element substrate 5 is subjected to a tensile stress which causes crack generation and propagation, which causes a problem. Therefore, a groove 7 as shown in FIG. 1 is formed and thermocompression bonding is performed. 3A and 3B are cross-sectional views of a joint for explaining a rolling force distribution in an embodiment of the present invention. FIG. 3A shows the case of the first embodiment, and FIG. 3B shows the case of the second embodiment. 4A and 4B are diagrams showing the rolling force distribution in the embodiment of the present invention, wherein FIG. 4A shows the case of the first embodiment, and FIG. 4B shows the case of the second embodiment.

As shown in FIG. 3 (a), the particles of the material constituting the leads 3 and the bumps 4 try to flow along the grooves 7 as the pressure is reduced. This tends to improve the wedge-shaped profile of the rolling force distribution. In particular, the wedge shape is corrected as the groove depth d satisfies d ₁ <d ₂ <d ₃ . That is, the groove 7 of the bonding tool 1 causes a plastic flow contributing to the bonding on the bonding interface between the bump 4 and the lead 3, and at the same time, the rolling force on the semiconductor element substrate 5 becomes almost uniform and the rolling is reduced. This has the advantage that the force distribution can also be improved. At this time, the groove 7 is pressed down so as to be parallel to the longitudinal direction of the arm 2 or the lead 3.

FIG. 2 shows a second embodiment of the present invention. FIG. 2 (a) is an external view of a bonding tool, and FIG. 2 (b) is a partially enlarged view thereof. This embodiment is similar to the first embodiment.
The bonding tool 1a has the same groove 7a as shown in FIG. 5, and has an arbitrary number of steps in the longitudinal direction of the lead 3 or the arm 2 in a stepped manner. Further, as shown in FIG. 3B, the pressure is reduced so that the deep portion of the groove 7 a is always located at the tip end side of the lead 3. This improves the rolling force distribution that causes a shear fracture surface as shown in FIG. 7B. That is, in the process of pressing down, the crimping surface 8a on the deep side of the groove 7a
, And then the crimping surfaces 8b and 8c perform the reduction. During this process, the material of the lead 3 is conventionally
Since the tip of the lead 3 is a free end, what caused plastic flow to this tip will behave like a kind of upsetting angle, and the above-mentioned flow will flow in the depth direction of the lead 3. Press. This means that the grooves 7a
Does not cause unnecessary or excessive deformation constraint of the material by undertaking the volume change of the material due to the plastic flow caused by the local strong rolling force by the 8a surface in the early stage of the reduction, that is, non-uniformity. Means that no significant deformation stress is generated. FIG. 4 (b), by selecting a step of tool tip optimally, the pressure distribution is compared with the prior art shows a state approaching to the ideal deformation resistance P _m.

[0014]

As described above, the present invention relates to a bonding tool for a semiconductor manufacturing apparatus for performing a single point bonding in a thermocompression bonding process, wherein a lead surface,
In other words, the shape of the crimping surface at the tip end of the bonding tool that comes into contact with the part to be subjected to thermocompression bonding is parallel to the longitudinal direction of the lead, and has a groove of an arbitrary depth and width located at the center of the crimping surface. And that the shape of the crimping surface at the distal end of the bonding tool has at least one or more steps in the longitudinal direction of the lead from a portion in contact with the surface of the free end, which is the distal end of the lead. This has the effect of improving the plastic flow at the bonding interface with the substrate, improving the uneven rolling force distribution on the semiconductor element substrate, suppressing the occurrence of peeling of bumps and the like, and improving the bonding strength.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing a first embodiment of the present invention. FIG. 1A is a schematic diagram showing a bonding state, and FIG. 1B is an enlarged external view of a bonding tool.

FIGS. 2A and 2B are views showing a second embodiment of the present invention, wherein FIG. 2A is an external view of a bonding tool, and FIG. 2B is a partially enlarged view thereof.

3A and 3B are cross-sectional views of a joint for explaining a rolling force distribution in an embodiment of the present invention. FIG. 3A shows the case of the first embodiment, and FIG. 3B shows the case of the second embodiment. .

4A and 4B are distribution diagrams of a rolling force in an embodiment of the present invention. FIG. 4A shows the case of the first embodiment, and FIG. 4B shows the case of the second embodiment.

5A and 5B are views showing a conventional bonding tool, wherein FIG. 5A is an external view and FIG. 5B is a perspective view.

6A and 6B are elementary analysis diagrams of stress at a joint portion for explaining a conventional technique, wherein FIG. 6A is a perspective view showing a thermocompression bonding state, and FIGS. 6B and 6C are perspective views A and P, respectively. FIG. 9 is a diagram showing the balance of forces in a two-dimensional cross section viewed from B.

7A and 7B are diagrams showing a rolling force distribution viewed from a viewpoint A in FIG. 6A, wherein FIG. 7A shows a deformation resistance distribution and a rolling force distribution, and FIG. FIG. 3C is a diagram in which the deformation resistance distribution is represented by numerical values.

8A and 8B are diagrams showing a rolling force distribution viewed from a viewpoint B in FIG. 6A, wherein FIG. 8A shows a deformation resistance distribution and a rolling force distribution, and FIG. FIG. 3C is a diagram showing the deformation resistance distribution by numerical values.

[Explanation of symbols]

1, 1a, 1b, 1c Bonding tool 2 Tool support arm 3 Film carrier tape lead 4 Protruding electrode (bump) 5 Semiconductor element substrate 6 Bonding stage 7, 7a Groove on tool tip crimping surface 8, 8a, 8b, 8c , 8d tool tip crimping surface 9 electrode pads d, d _1, d ₂ the groove depth a lead width b leads longitudinal length W groove width h lead thickness l moment arm M moment load P rolling force of the thermocompression bonding sites Force in which distribution is replaced by equivalent concentrated load σ _n Rolling force distribution and deformation resistance distribution k Shear yield stress μ Joint friction coefficient P _m Ideal deformation resistance

Claims (2)

(57) [Claims] 1. Single point bonding to a semiconductor device having a protruding electrode at one of a lead end of a film carrier tape and an external lead electrode pad provided on a semiconductor element by a thermocompression bonding process. In the single point bonding tool of the semiconductor manufacturing apparatus, the tip of the bonding tool is in contact with a portion of the surface of the lead to be subjected to thermocompression, and is parallel to the longitudinal direction of the lead, and A single point bonding tool having a groove of an arbitrary depth and width located at the center of the surface. 2. A crimping surface at a tip portion of a bonding tool,
2. The single point bonding tool according to claim 1, wherein the single point bonding tool has at least one or more steps in the longitudinal direction of the lead from a portion in contact with the free end surface of the lead of the film carrier tape.