JP2998179B2 - Method for manufacturing film carrier type semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention particularly relates to a method for manufacturing a film carrier type semiconductor device for manufacturing a film carrier type semiconductor device by inner lead bonding.

[Prior Art] Conventionally, this kind of film carrier type semiconductor device is usually manufactured by inner lead bonding (ILB) using a TAB (Tape Automated Bonding) method.

FIG. 8 is a front view showing a method for manufacturing a conventional film carrier tape type semiconductor device, and FIG. 9 is an enlarged view of a region surrounded by a dashed line in FIG. 8, showing a thermocompression bonding step. . First, a copper tape is laminated on a polyimide tape provided with sprocket holes, and a lead pattern corresponding to a bonding wire is formed on the polyimide tape by photoetching. Then, gold, tin or solder is plated on the lead pattern to form a TAB tape 30. Get. On the other hand, a semiconductor element substrate 33 in which a projection type electrode (hereinafter, referred to as a bump) 32 is formed on an external lead electrode is prepared. Then, the bump 32
The leads 31 of the TAB tape 30 are overlapped, and the leads 31 are pressed on the bumps 32 at a high temperature by a bonding tool 34 to bond the bumps 32 and the leads 31. Thus, a film carrier type semiconductor device is manufactured.

[Problems to be Solved by the Invention] However, in the conventional bonding method described above, the surface to be bonded to the bump 32 at the tip of the lead 31 of the TAB tape 30 and the vicinity thereof are shown in FIGS. 9 and 10. As shown in FIG.
FIG. 10 (a) is a side view of the lead 31, and FIG. 10 (b) is a view as viewed from an end surface of the lead 31. Therefore, when the lead 31 and the bump 32 are crushed and deformed in accordance with the rolling load, the lead 31 and the bump 32 are deformed when pressed down on the crimping surface of the bonding tool 34 formed of diamond or the like and having extremely high rigidity. In particular,
If the material forming the bumps 32 is a material that is rich in extensibility, hardly work hardened, and has high deformability, such as Au,
In combination with the fact that the bumps 32 have a lower deformation resistance than Cu or the like generally used as a material of the leads 31 of the TAB tape 30, the bumps 32 are crushed during bonding and spread around the bumps. This is a restriction on reducing the arrangement interval of the bumps on the semiconductor element substrate. That is, the crushing of the bump 32 is a factor that prevents the pitch of the bump 32 from being narrowed.

Further, in order to reduce the amount of crushing of the bumps 32, in the conventional bonding step, a measure such as setting a lower rolling load or a lower heating temperature is adopted. However, when the rolling load is reduced, the generation of a favorable new surface at the joint surface between the bump and the lead is also suppressed. In addition, when the heating temperature is lowered, self-diffusion between the lead and the bump is necessary for self-diffusion when the lead and the bump are the same kind of metal (eg, Au-Au), and mutual diffusion when the lead and the bump are different kinds of metal (eg, Au-Sn) The amount of heat activation energy input also decreases, leading to a decrease in solid solution between materials. Therefore, as a result, there is a disadvantage that the reliability of the bonding strength is reduced. Further, when the heating temperature is set low, the input amount of the thermal activation energy is reduced, so that the deformation resistance of the material (bump, lead) increases.
For this reason, the bumps are unlikely to be deformed, so that the formation of a new surface on the bonding surface is suppressed in the same manner as described above.

Thus, setting the optimal bonding conditions that can reduce the amount of crushing of the leads and bumps while ensuring the reliability of the bonding strength between the leads and the bumps is one of the contradictory characteristics. It's like looking for optimal conditions.

Further, in the conventional bonding method, as shown in FIG. 10 (a), the bonding portion (deformation region) of the tip portion 35 of the lead 31 is formed.
The displacement d due to in-plane bending occurs between the neutral shaft 36 and the neutral shaft 37 in the undeformed area of the lead, and the lead warps.
This phenomenon is observed not only in the manufacturing process of semiconductor devices, but also in forging of large structures with punches (Plasticity and Processing, Vol. 30, No. 340, 1989).
Year, pages 651 to 657, "Influence of processing conditions on in-plane bending"). Actually, this lead warpage occurs because the lead length is sufficiently longer than the joint size, so that the lead is displaced by its own restraint, and the in-plane stress corresponding to this displacement becomes residual stress inside the lead after bonding. This leads to deterioration and deterioration in strength, dimensional accuracy, moldability, material, and the like in a lead forming step and the like performed after bonding and in a reliability test and the like.

The present invention has been made in view of such a problem, and a film carrier type semiconductor which can suppress the spread of the projection type electrode, promote the generation of a new surface of the projection type electrode, and increase the bonding strength. An object of the present invention is to provide a method for manufacturing a device.

[Means for Solving the Problems] In a method of manufacturing a film carrier type semiconductor device according to the present invention, a lead end of a film carrier tape is heat-bonded to a projection type electrode formed on an external lead electrode pad of a semiconductor element. In a method for manufacturing a film carrier type semiconductor device in which a lead tip is thermocompression-bonded to a protruding electrode by pressing with a tool, the lead tip of the film carrier tape has a concave portion on a joining surface of the lead, Is characterized in that the distal end of the tip is closed and the entire periphery of the recess is surrounded by a wall.

[Operation] In the present invention, a film carrier tape having a groove or a concave portion at the joining surface of the lead tip is aligned with the joining electrode to the projecting electrode, and the lead tip is attached to the projecting electrode by a heating bonding tool. Press. As a result, the protruding electrode plastically flows, and a part of the protruding electrode enters the groove or recess at the tip of the lead. In this manner, the leading ends of the leads of the film carrier tape are thermocompression-bonded to the protruding electrodes.

In the present invention, since the projection-type electrode plastically flows into the groove or the recess at the tip of the lead by the pressing of the bonding tool, a new surface appears on the projection-type electrode, and the reliability of bonding is improved. Further, when the protruding electrode is pressed by the bonding tool, a part of the material enters the groove or the concave portion, so that the spread of the protruding electrode is reduced accordingly.

Example Next, an example of the present invention will be described with reference to the accompanying drawings.

FIGS. 1 to 4 are schematic views showing a method of the first embodiment of the present invention.

First, a film carrier tape 3 shown in FIG. 2 is prepared. FIG. 2 (a) shows the film carrier tape 3
2 (b) is a side view, and FIG. 2 (c) is a bottom view. This film carrier tape 3 is provided with a groove 2 or a concave portion at a lead end portion 1. The groove 2 is a concave,
For example, it can be formed by photo etching or the like. The size and shape of the groove 2 or the concave portion are not particularly limited, but may be any as long as the groove or the concave portion is arranged on the joint surface with the bump.

Then, as shown in FIG. 3 and FIG. 1, a protruding electrode (hereinafter referred to as a bump) 6 formed by Au plating or the like.
The semiconductor element substrate 7 provided on the electrode pad 10 is positioned at the position where the bonding tool 8 is provided, and the bonding surface including the groove 2 of the lead tip 1 of the film carrier tape 3 is aligned with the bonding surface of the surface of the bump 6. Align and overlap. At this time, one film carrier tape 3
FIG. 1 (a) shows a side cross-sectional view of FIG. First
FIG. 1A is an enlarged view of a region surrounded by a dashed line in FIG. 3, and FIG. 1A is a cross section of the lead end portion 1 of the film carrier tape 3 (a surface orthogonal to the longitudinal direction). Is shown.

Next, as shown in FIG. 1 (b), the heated bonding tool 8 is pressed against the bump 6 by sandwiching the lead tip 1 between the bump 6 and the bump 6, thereby pressing the lead tip 1 against the bump 6. To join the two. Thereby, the bump 6 plastically flows and deforms. In this case, the lead tip 1 is a kind of plastic working mold in which the lead itself 1 is deformed, and the size and shape of the groove 2 can be similar to the molding shape and size of this mold. Therefore, the shape and dimensions of the groove 2 define the deformation state and the plastic flow of the joint surface 9 of the bump 6a as a processing material, similarly to a general mold. Here, the plastic flow refers to a movement accompanying the joining of the internal particles of the material formed on the joining surface of the lead tip 1 and the bump 6.

In the method of this embodiment, the groove 2 of the lead tip 1 is
As shown in FIG. 4B and FIG. 4, a bonding surface 9 is formed. At this time, a part of the bump 6 flows into the groove 2 with plastic flow as schematically shown in FIG. 4, and at the same time, forms a new surface. In particular, when the material forming the bumps 6 (generally Au) has a smaller deformation resistance than the material forming the lead tip 1 (generally Cu), and when rolling down / joining due to high-temperature deformation. This plastic flow is an effective method. That is, if the shape and size of the groove 2 of the lead tip 1 are appropriately selected, the bump 6 is deformed as shown in FIG. At the joint surface 9, shear deformation and the like are promoted, and the bump 6
A clean material is exposed on the joining surface to increase the surface area. As a result, the bonding strength is increased, and the reliability of the bonding is improved.

Also, since the bump 6 flows into the groove 2, the groove 2
There is an advantage that the lateral spread at the time of deformation of the bump 6 is reduced as compared with the conventional one by an amount corresponding to the volume of the bump 6. This is the fourth
It can be understood by comparing the plastic flow state near the joint surface with reference to the figure and FIG. 10 (b) showing the conventional deformation, but it can be easily confirmed by experiments and calculations. Qualitatively, it can be explained as follows.

In bonding using a bonding tool 34 having a flat crimping surface 38 and a film carrier tape having a flat bonding end surface at the lead end portion 35, as shown in FIG. 10 (b), the neutral surface 40 (the bump 35 10 (b), the plastic flow flows so as to expand symmetrically with respect to the center line of FIG. On the other hand, in the present embodiment shown in FIG. 4, there are two flows: a plastic flow flowing toward the neutral shaft 12 inside the groove 2 and a plastic flow developing right and left. Of these, the flow into the groove 2 produces the effect of suppressing the lateral spread of the bump 6. Further, in the case of the present embodiment, if the same bumps, the same processing conditions and the same amount of reduction are used as in the prior art, the volume discharged to the periphery of the bump 6 by the above-described plastic flow during the reduction of the width of the groove 6 is reduced. The same effect as that obtained by reducing the volume flowing into the inside compared to the conventional case can be obtained. Thereby, the lateral spread of the bump can be reduced. When the amount of lateral spread of the bump is estimated, it can be calculated as follows.

Focusing only on the deformation of the bump 6, the following assumption is adopted.
That is, in the conventional case, the bumps shown in FIG.
Considering 32 schematic cross-sections, it is assumed that it is mechanically in a plane strain state. Therefore, the depth in the longitudinal direction of the lead is set to unit length 1. In this case, the volume V of the bump 32 is given by the following equation (1) since the height is h ₀ and the width is W ₀ .

V = h ₀ × W ₀ × 1 (1) Next, a bonding tool having a flat surface shape
Assuming that the pressure is reduced by Δh by 34, the discharge amount ΔV when the bump 32 spreads left and right is given by the following equation (2), where the spread width is ΔW.

ΔV = Δh × ΔW × 1 (2) This discharge amount ΔV corresponds to the hatched portion in FIG. 11 (c). Here, since the volume is constant before and after the deformation [FIG. 11 (a)] and after the deformation [FIG. 11 (b)] before and after the deformation from the continuous condition, the relationship shown in the following equation (3) is obtained. There is.

h ₀ · W ₀ = (h ₀ −Δh) (W ₀ + ΔW) (3) Therefore, once Δh is determined, ΔW is inevitably determined. From the above equation (2), if Δh is the same, ΔV must be reduced.

However, as shown in FIG.
When the plastic flow is caused in the bump 6 so that the bump 6 flows in, the discharge volume ΔV of the bump changes to ΔV ₂ shown in the following equation (4) when the volume of the groove 2 is V _2. .

ΔV ₂ = ΔV−V ₂ (4) The spread ΔW ₂ of the bump in this embodiment is given by the following equation (5).

ΔW ₂ = ΔV ₂ / Δh (5) Since ΔV ₂ <ΔV from the above equation (4), the following (6)
An expression is obtained.

ΔW ₂ <ΔW (6) As described above, according to the present embodiment, the spread ΔW ₂ of the bump can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 6, the film carrier tape 23 has a concave portion 22 on the joint surface at a position slightly in the lead base end side from the edge of the lead end portion 21. The recess 22 has a narrow width at the lead end side.

Further, as shown in FIG. 5 (a), the bonding tool 26 has a pressure bonding surface 27 inclined at a taper angle θ. Then, the tool 26 is pressed down by aligning so that at least a part of the bonding surface of the lead tip 21 is located closer to the lead tip than the center line 28 of the bump 24 on the semiconductor element substrate 25.
At this time, after a part of the bonding surface of the lead tip 21 first comes into contact with the surface of the bump 24, it collapses as the rolling down progresses. At the same time, a plastic flow is generated in the bump 24 along the recess 22 in the longitudinal direction of the lead. This allows the bump 24
広 が り W ₂ can be reduced.

Further, similarly to the first embodiment, the concave portion of the lead tip portion 21 is formed.
When the shape of 22 forms the bonding surface 29 on the surface of the bump 24,
The generation of a new surface is promoted by shearing or the like, and the bonding strength is increased, so that the reliability of the bonding is increased.

Further, in this embodiment, it is possible to eliminate the warpage of the lead due to the in-plane stress or the in-plane bending in the longitudinal section of the lead caused by the conventional bonding method. this is,
Since the crimping surface 27 of the bonding tool 26 is inclined at the taper angle θ, a component of a force in the longitudinal direction of the lead is generated due to the vertical downward pressure, and this force causes in-plane bending. Push the material in the longitudinal direction of the lead so as to oppose the suppression of flow in the longitudinal direction of the lead,
This is because it acts to promote the flow of the material in the longitudinal direction of the lead.

[Effects of the Invention] As described above, the present invention provides a film carrier tape in which grooves or recesses are formed in an arbitrary shape and size on a bonding surface of a lead end portion of a film carrier tape to be subjected to thermocompression bonding by photoetching or the like. And a bonding tool having a crimping surface parallel or inclined at a required taper angle is prepared, and the lead tip and the protrusion are aligned with the groove or recess at the lead tip aligned with the surface of the joint of the projection electrode. The protrusion-type electrode is deformed and plastically flowed so as to be embedded in the groove or recess at the tip of the lead by thermocompression bonding with the mold electrode, so that the volume of the constituent material of the protrusion-type electrode in which the groove or recess is embedded , The amount of deformation of the protrusion-type electrode extending to the periphery is reduced. Thereby, the arrangement of the projection type electrodes can be narrower.

In addition, the shape of the groove or the concave portion becomes a kind of plastic working mold, and the plastic flow generated at the joint surface during the thermocompression bonding process can be promoted to generate a new surface, so that optimal joining can be performed. High joining strength can be obtained.

Furthermore, by providing the bonding surface of the bonding tool with an inclined surface, it is possible to eliminate the warpage of the lead and the in-plane stress due to the in-plane bending generated in the lead of the film carrier tape.

[Brief description of the drawings]

FIG. 1 is a side view showing the method of the first embodiment of the present invention, and FIG.
FIG. 3 is a view showing a film carrier tape used in the method of the first embodiment, FIG. 3 is a reference view showing the bonding method, and FIG. 4 is a view showing the plastic flow of the projection type electrode in the present embodiment. FIG. 5 is a front view, and FIG.
FIG. 6 is a diagram showing a film carrier tape used in the method of the second embodiment.
FIG. 7 is a schematic view showing the plastic flow of the projection type electrode in this embodiment, FIG. 8 is a front view showing the conventional method, FIG. 9 is a front view showing the conventional method, and FIG. FIG. 11 is a schematic diagram illustrating the amount of deformation of a conventional bump. 1,21; Lead tip, 2; Groove, 3,23; Film carrier tape, 6,24; Bump, 7,25,33; Semiconductor element substrate, 8; Bonding tool, 9; Joint surface, 10; Electrode pad , 22; recess, 3
0; TAB tape, 31; lead

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/60 311 H01L 21/603

Claims (2)

(57) [Claims] 1. A film for pressing a leading end of a film carrier tape against a projecting electrode formed on an external lead electrode pad of a semiconductor element by heating bonding roots to thermally press the lead tip to the projecting electrode. In the method for manufacturing a carrier-type semiconductor device, the leading end of the lead of the film carrier tape has a concave portion on a joining surface of the lead, and the concave portion has a closed end at the leading end and the entire periphery of the concave portion has a wall. A method for manufacturing a film carrier type semiconductor device, characterized by being surrounded by: 2. A crimping surface of the bonding tool linearly inclines in one direction in which a lead end portion of the film carrier tape is high and a base end portion is low, and the inclined surface has at least the entire size of the bump. The method for manufacturing a film carrier type semiconductor device according to claim 1, wherein the method has a size to cover.