JP3041318B2 - Semiconductor device 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 bonding apparatus for pressing a protruding electrode and a lead of a semiconductor chip under heating.

[0002]

2. Description of the Related Art A TA for bonding a projecting electrode formed on an upper surface of a semiconductor chip to a lead of a mounting tape.
An example of implementation using the B (Tape Automated Bonding) method will be described with reference to the drawings. FIG. 7 is a perspective view showing a conventional semiconductor chip mounted by the TAB method. In the figure,
1 is a semiconductor chip, 2 is a protruding electrode formed on the upper surface of the semiconductor chip 1, and 3 is a lead of a mounting tape (not shown), which is electrically and mechanically connected to the protruding electrode 2.
By bonding the protruding electrodes 2 and the leads 3 in this manner, the active functions of the semiconductor chip 1 can be taken out to the leads 3. Therefore, for example, by connecting the leads 3 to the substrate having pads electrically connected to the external terminals by soldering or the like, the semiconductor chip 1 can send out its active function from the external terminals. As a function to shine.

[0003] A bonding method in the TAB technique will be described with reference to the drawings. FIG. 8 is a schematic diagram illustrating an example of a bonding method in the TAB technique, which is a gang bonding method in which all protruding electrodes and all leads are thermocompressed together. is there. In the figure, reference numeral 4 denotes a bonding stage on which the semiconductor chip 1 of about 15 mm × 15 mm is mounted, 5 denotes a bonding tool, and 6 denotes a fixture for the stage 4. FIG. 8 (a)
, The semiconductor chip 1 is placed on the stage 4 and the projecting electrodes 2 and the leads 3 are aligned. Next, FIG.
, The tool 5 heated to about 500 ° C. is pressed against all the protruding electrodes 2 (made of, for example, Au) and all the leads 3 (made of, for example, Sn, Au, etc.). The projecting electrode 2 and the lead 3 are thermocompression bonded by this heat and pressing force.

[0004]

However, in the conventional bonding method, as shown in FIG.
The heat reaches the stage 1 via the chip, a temperature distribution occurs in the stage 1, and the stage is warped in a convex shape. As a result of this phenomenon, as shown in FIG. 8D, a difference Hc in height between the lead and the bump chip corner near the center of each side of the chip after bonding occurred. That is, the electrode lead of the chip near the center was too much crushed as compared with that near the corner. The over-crushing causes a contact with an adjacent bump and a breakdown of a bump underlayer, which causes a problem that a semiconductor device becomes defective.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to reduce the variation of Hc in a chip. It is an object of the present invention to provide a bonding method and a device that are less likely to occur.

[0006]

SUMMARY OF THE INVENTION A bonding apparatus according to the present invention is provided.
The semiconductor chip having the protruding electrodes is mounted on a bonding stage, and the leads and the protruding electrodes superimposed by a bonding tool heated to a predetermined temperature in a state where the leads are arranged so as to overlap the protruding electrodes. To press the lead and the protruding electrode by applying pressure
Device. The above bonding stage has a diameter of 30
mm and a column shape with a thickness of 10 mm or more , F
αρC / λ [unit: cal / (° C.mm ⁴ )] is that of SKS-3
It is characterized by being formed of a smaller material.
Where α is the linear expansion coefficient 1 / ° C., ρ is the density gr / mm ³ , C
Is the specific heat cal / (gr · ° C), λ is the thermal conductivity cal / (mm · s · ° C)
It is. F is the heat flux [cal / (mm ² ·
s)]. Semi-conductive on 25 ° C bonding stage
Body chip and place the leads on the mounting tape
500 ° C bonding tool
When pressed against the bonding stage with a
Unit that flows into the bonding stage via the chip
Heat flux [cal / cal / per unit area [ s] per area [mm ² ]
(mm ² · s)].

[0007]

The bonding stage has a diameter of 30 mm.
mm and a column shape with a thickness of 10 mm or more. This
Shape compared to conventional bonding stages
It becomes a mold and improves rigidity to restrain the stage warpage. Ma
Also, when the bonding stage is large,
If heat is transferred to the outside, the stage surface
Rising swelling is reduced. In addition, this bondings
As the material of the cottage, FαρC / λ is that of SKS-3
By using smaller materials, as shown in FIG.
The height of the combined protruding electrode and lead after crimping
And the one pressed at the center of the stage
The difference Hc from the crimped one should be less than 1.83
it can.

[0008]

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a schematic diagram showing a state before bonding and shows a case where the entire stage temperature is set to 285 ° C. Note that the stage temperature of 285 ° C. at this time was determined due to restrictions on the configuration of the bonding apparatus in this embodiment. Although not shown, the stage 4 is precisely fixed to a bonding apparatus base (not shown) by a fixture similarly to the conventional example. And the bonding time is 3
Have been done in seconds. Next, as a result of numerical analysis, FIG.
Immediately after the bonding shown in (b) is completed, the stage upper surface temperature becomes 360.4 ° C. At this time, the temperature of the lower surface of the stage is maintained at 285 ° C. As a result of this analysis, the temperature difference ΔT between the upper surface and the lower surface of the stage is 75.4 ° C. Numerical analysis was performed with the stage having such a temperature difference (temperature distribution) fixed to the lower surface, and it was found that the warpage was 1.61 μm. Since the bonding of the chip is performed on the stage having the amount of warpage, the difference Hc in the height of the electrode leads is equal to the amount of warpage compared to the case where the amount of warpage is zero, that is, the variation of 1.61 μm. It is considered that it has. The stage shape of this embodiment is shown in FIG. 4, and the material is SKS-3 (alloy tool steel). Although the stage heating method is not particularly described, it is based on ordinary heater heating or the like.

In the above embodiment, the stage temperature is 285.degree. C. due to the restriction of the apparatus. No warpage,
It goes without saying that bonding without variation in Hc is performed.

FIG. 2 shows an embodiment of the present invention.
In the conventional method shown in (1), the stage temperature is 25 ° C.
In this case, it was found by numerical analysis that the stage surface temperature would be 131.4 ° C. when the bonding was completed. As a result, the temperature difference ΔT becomes 106.4 ° C., and the amount of warpage at this time is 2.27 μm. (Numerical analysis value)
Therefore, it is considered that the variation of Hc is 2.27 μm. The material in this case is also SKS-3, and the shape is as shown in FIG.

As described above, according to the present invention, the variation in the height difference Hc of the lead electrodes caused by the conventional bonding apparatus was 2.27 μm, but the variation of the present invention can be reduced to 1.61 μm. it can.

Embodiment 2 FIG. A second embodiment of the present invention will be described with reference to FIG. Fig. 3 shows 30mmφ, 10mmt
(Large stage) is shown. The amount of stage warpage in this case was determined to be 1.83 μm by numerical analysis. The material was SKS-3 and the temperature was 25 ° C. On the other hand, FIG. 4 shows a conventional stage shape (small stage).
In the case of, the stage warpage amount is 2.27 μm as described above.
It is. This is considered to be because the stage of the present invention (FIG. 3) is larger than the conventional stage, so that the rigidity is improved and the stage warpage is restrained. Further, it is considered that one of the reasons is that when the stage is made large, heat is transmitted to the outside, and expansion of the surface layer of the stage in the surface direction is reduced. FIGS. 5A and 5B show the temperature distribution and deformation at the time of completion of the bonding operation of the large and small stages (after 3 seconds).
Thus, according to the second embodiment, it is possible to reduce the variation in Hc from 2.27 μm to 1.83 μm. If the stage shape is 30 mmφ or more and 10 mmt or more, it is considered that Hc is further reduced.

Embodiment 3 A third embodiment of the present invention will be described with reference to FIG . FIG. 6 shows the relationship between FαρC / λ and Hc for the stage material. Here, F is the heat flux, α is the linear expansion coefficient, ρ
Is density, C is specific heat, and λ is thermal conductivity. This FαρC
It was found by numerical analysis that Hc was small when a material having a small / λ was selected. In the figure, it can be seen that silicon nitride has the smallest Hc of 0.59 μm. The shape in this case is as shown in FIG. 3, and the temperature is 25 ° C.
An example of another material is shown in FIG. 6 , and the conventional material SKS-3 is 1.83 μm, and forsterite is 3.59 μm. Thus, according to the present invention, F
If a material having a small αρC / λ is selected , Hc becomes small. For example, when silicon nitride is used, Hc becomes 0.59 μm.
m.

Embodiment 4 FIG. In the first to third embodiments, the stage material is made of the same material and has the shape shown in FIG. 3, but the same effect can be obtained by adopting a structure in which the stage is provided with a heat sink to reduce the amount of warpage.

[0015]

As described above, according to the present invention, variation in Hc can be reduced, and defects such as contact between adjacent bumps and breakage of the under bump are less likely to occur.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a temperature distribution before and after bonding when a stage temperature is raised, which is one of embodiments of the present invention.

FIG. 2 is a schematic diagram of a conventional temperature distribution before and after bonding when the stage temperature is not raised.

FIG. 3 is a schematic external view of a stage when one of the embodiments of the present invention has a stage shape of 30 mmφ and 10 mmt.

FIG. 4 is a schematic view of a conventional stage appearance.

FIG. 5 is a diagram showing a temperature distribution and deformation immediately after bonding in FIGS. 3 (a) and 3 (b).

FIG. 6 is a diagram showing a relationship between FαρC / λ and Hc.

FIG. 7 is a perspective view showing a semiconductor chip mounted by a TAB method.

FIG. 8 is a schematic diagram showing the reason why variation in Hc occurs.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor chip 2 Protruding electrode 3 Lead 4 Bonding stage 5 Bonding tool

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masatoshi Yasunaga 4-1-1 Mizuhara, Itami City Mitsubishi Electric Corporation In-LSE Research Institute (56) References JP-A-4-171739 (JP, A) Hei 3-206635 (JP, A) Japanese Utility Model 63-112339 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/60

Claims (1)

(57) [Claims] 1. A placing a semiconductor chip having a protruding electrode on the bonding stage, while arranged so as to overlap the lead on the projecting electrodes, the lead superimposed by a bonding tool which is heated to a predetermined temperature The bonding stage has a columnar shape with a diameter of 30 mm or more and a thickness of 10 mm or more, and a FαρC / λ [unit].
Order: cal / (° C.mm ⁴ )] is smaller than that of SKS-3
A bonding device for a semiconductor device , wherein the bonding device is formed of a material . Here, α is a coefficient of linear expansion [1 /
° C], ρ is density [gr / mm ³ ], C is specific heat [cal / (gr ·
° C)] and λ is the thermal conductivity [cal / (mm · s · ° C)]. Ma
F is the heat flux [cal / (mm ² · s)] in the following case.
Place semiconductor chip on bonding stage at 25 ℃
Press the leads of the mounting tape onto the semiconductor chip.
Bonding with 500 ° C bonding tool
When pressed against the moving stage side,
Unit area [mm ² ] flowing into the bonding stage
Heat flux per unit time [s] [cal / (mm ² · s)]
It is.