JP2003007749A - Integrated circuit and display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a manufacturing cost by replacing gold used for bumps for connecting a display and a driving IC chip, with another metal. SOLUTION: Each bump is formed in a two-layer structure constituted of thick insulation films 20 and 25 and conductive films 21 and 26. The insulation films 20 and 25 is formed with many through holes 22. The conductive films 21 and 26 are formed of metal less expensive than gold, such as aluminum, molybdenum, and chrome, and the film thickness is smaller than the diameter of conductive particles 51. The height of the bump is secured by the insulation films 20 and 25. About the through holes 22, many through holes 22 having a small diameter are disposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection terminal for an integrated circuit, and more particularly to a connection terminal mounted on an external device by crimping with an ACF.

[0002]

2. Description of the Related Art FIG. 1 is a perspective view showing a liquid crystal display device (LCD) 1 as an example of a display device. The LCD 1 encloses liquid crystal between a first body substrate 2 and a second body substrate 3 made of glass to form a display area. On the first main body substrate 2 in the display area, a plurality of pixel electrodes 4 and switching elements 5 each including a thin film transistor (TFT) are arranged in a matrix. Then, the common electrode 6 is arranged on the second substrate over the entire display area. The LCD 1 is a display device that applies a voltage between the pixel electrode 4 and the common electrode 6 to drive the liquid crystal and perform display. A plurality of gate line driving ICs 7 are provided around the display area.
And a plurality of data line driving ICs 8 are arranged. A plurality of gate lines 9 extend from the gate line driving IC 7,
The gate line driving IC 7 sequentially selects the gate lines 9 and applies a gate signal to turn on the TFTs 5 connected thereto. A plurality of data lines 10 extend from the data line driving IC 8, and the data line driving IC 8 supplies a video signal to the pixel electrode 4 via the turned-on TFT 5. The gate line driving IC 7 and the driving IC 8 are IC chips mounted on the main body substrate.

Generally, an IC chip is a semiconductor I
A plurality of circuit elements in which a semiconductor film, a conductive film, an insulating film, and the like are laminated are formed on a C substrate. In this specification, LCD
The substrate that constitutes 1 is distinguished from the main substrate, and the substrate that constitutes the IC chip is distinguished from the IC substrate.

FIG. 2 is a perspective view showing how a glass substrate IC chip is mounted. Various elements,
The wiring is formed, and the board-side terminal 41 for mounting the IC chip is also formed. The IC chip mounted on the board-side terminal 41 includes various elements on the IC board 42,
The wiring is formed, and the chip-side terminal 43 is formed at a position corresponding to the board-side terminal 41. Bumps, which are protrusions made of gold, are formed on the board-side terminals 43, and a resin adhesive containing fine conductive particles and an anisotropic conductive film (AC
The terminals are crimped and fixed by F).

FIG. 7 is a sectional view showing the structure of the bump. Substrate side terminals 41 are provided on the main body substrate 2, and chip side terminals 43 are provided on the IC substrate 42. Terminal 4
On the layers 1 and 43, insulating films 44 and 45 having contact surfaces of the terminals 41 and 43 opened are provided. Gold bumps 46 are provided on the chip-side terminals 43. The gold bump 46 is
It is a projecting structure having a height of about 5 μm. ACF is attached on the board-side terminals 41 of the main board 2,
42 is crimped and fixed. The ACF is made of conductive particles 51 dispersed in the adhesive 50, and the gold bumps 46 and the substrate-side terminals 41 are electrically connected via the conductive particles 51 by sandwiching the ACF and pressing them.

[0006]

The gold bumps 46 described above are to be solved.
Uses high-purity gold as a material. This is because the diameter of the conductive particles 51 is about 3 μm, and it is necessary to form the gold bump 46 higher than this, for example, about 5 μm.
This is because gold is the most suitable material as a material that has a low electric resistance and a high bump height.

However, gold is a noble metal and is very expensive, which has been an obstacle to reducing the manufacturing cost of IC chips.

Therefore, an object of the present invention is to form bumps without using gold and to supply IC chips having a low manufacturing cost.

[0009]

The present invention has been made to solve the above-mentioned problems, and is an integrated circuit and a display device in which a plurality of elements are arranged on a substrate, and which is electrically conductive to an external device. It has bumps for mounting by pressure bonding through an anisotropic conductive film formed by dispersing particles in an adhesive.
A terminal portion formed on the substrate, an insulating film formed so as to cover the terminal portion and provided with a plurality of openings on the terminal portion, and an insulating film formed so as to cover the insulating film, and formed at the terminal portion through the plurality of openings. An integrated circuit and a display device each including a conductive film to be connected.

Further, the thickness of the insulating film is larger than the diameter of the conductive particles.

Furthermore, the spacing between the openings is at least 10 times larger than the diameter of the openings.

Further, the diameter of the opening is larger than the diameter of the conductive particles and smaller than the diameter of the conductive particles plus twice the thickness of the conductive film.

Further, the diameter of the opening is almost equal to the film thickness of the insulating film.

Further, the display device is an active matrix type having a plurality of switching elements on the substrate, and at least a part of elements constituting the bump is
It is formed at the same time as the switching element.

Further, the switching element has a flattening film for flattening the unevenness of the lower layer, and the insulating film of the bump is formed simultaneously with the flattening film.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described. This embodiment is also an IC chip to be mounted on a device as shown in FIG. 1, and is similar to the conventional one in that the device side terminal 41 and the chip side terminal 43 are crimped by using an ACF as shown in FIG. . The present embodiment is characterized by the bump structure. FIG. 3 is a cross-sectional view showing the bump structure of the present invention.
The board-side terminal 41 is provided on the main body board 2, and the IC board 4
The chip-side terminal 43 is provided on the upper part 2. Terminal 41,
On the 43, insulating films 44 and 45 are provided, the contact surfaces of the terminals 41 and 43 being opened. The above structure is the same as the conventional one. The bump of the first embodiment is formed of an insulating film 20 having a plurality of through holes and a conductive film 21 provided on the insulating film 20.

As described above, since the diameter of the conductive particles 51 contained in the ACF is about 3 μm, the height of the bump is at least higher than that, for example, about 5 μm is required. However, it is inefficient because it is necessary to continue sputtering for a long time, for example, in order to obtain a single layer of metal other than gold with a film thickness of 5 μm. Therefore, the bump of this embodiment has a two-layer structure of the insulating film 20 and the conductive film 21, and the thickness of the insulating film 20 is 5 μm. The conductive film formed on the insulating film is made of a metal that is cheaper than gold, such as aluminum, molybdenum, or chromium, and has a film thickness of about 1 μm. Since such a two-layer structure is provided, the insulating film 20 has a sufficient height, and the conductive film 21 need only be thinly formed. Therefore, it can be easily formed by a normal sputtering method or the like, which is inefficient. It is not necessary to adopt a different manufacturing method.

FIG. 4 is a perspective view showing only the insulating film 20. The bump size is length Lp = 1000 μm, width W
p = 500 μm. A plurality of through holes 22 are formed in the insulating film 20. The distance between the through holes 22 is Wh = 100 μm in the width direction and Lh = 100 in the length direction.
μm, and there are 36 through holes 22 in 4 rows and 9 columns. A conductive film 21 (not shown) is formed on this, and is connected to the chip side terminal 43 in the lower layer through the through hole 22. By thus forming a large number of through holes, the electric resistance can be reduced.

If only reducing the electric resistance is considered, it is better to increase the diameter of the through hole 22 because the electric resistance can be further reduced. However, when the size of the through hole 22 is increased, the conductive film 21 is dented at the position of the through hole 22, and when the conductive particle 51 is located there, the bump, the conductive particle 51,
The board-side terminals 41 may not be sufficiently crimped, resulting in poor contact. Therefore, in this embodiment, the diameter of the through hole is set to 5 μm. If the diameter is 5 μm, the insulating film 20
And the through hole 22 has an aspect ratio of 1
Therefore, no deep depression is formed on the conductive film 21.
Further, since the conductive film 21 having a thickness of 1 μm is formed so as to cover the through hole 22, the diameter of the recess is 3 μm or less at the maximum. Therefore, even if a depression is formed in the conductive film 21,
Since the diameter is equal to or smaller than the diameter of the conductive particles 51, the contact between the conductive film 21 and the conductive particles 51 is prevented from being deteriorated. As described above, the diameter of the through hole 22 is approximately equal to the thickness of the insulating film 20, or a value obtained by subtracting twice the thickness of the conductive film 21 from the diameter of the through hole is equal to or larger than the diameter of the conductive particles 51 of the ACF. The following is a good idea.

The through holes 22 are separated from each other by 100 μm. Through hole 22 diameter 5 μm
By forming the through holes 22 with a sufficiently large interval as compared with the above, the surface of the conductive film 21 can be formed almost flat. Therefore, the conductive particles 51 are surely pressure-bonded to the conductive film 21 and the substrate-side terminal 41, so that the conductive particles 51 can be surely conducted. Thus, the through hole 2
The distance between the two is sufficiently wide, for example, it is preferable to open the diameter of the through hole by 10 times or more, preferably about 20 times.

A method of manufacturing the bump of this embodiment will be described below. First, the insulating film 20 is formed. The insulating film 20 is formed by, for example, applying an acrylic resin used for a photolithography mask, exposing it, and developing it so that it remains on the chip-side terminals 43. At the same time, a plurality of through holes 22 are formed for one chip side terminal 43.
Next, a conductive film 21 made of metal is formed on the insulating film 20 and in the through holes 22.

Next, a second embodiment of the present invention will be described. FIG. 5: is sectional drawing which shows the 2nd Embodiment of this invention. Generally, the bump is provided on the IC chip side.
However, the present embodiment is different from the conventional and first embodiments in that the bump is provided on the display device side. That is, the thick insulating film 25 having a plurality of through holes is provided on the terminal 43 on the main body substrate 2 forming the display device, and the conductive film 26 is arranged thereon. Whether the bumps are provided on the IC chip side or the device side on which the IC chip is mounted, the functions are the same in that they are connected via the ACF made of the adhesive 52 containing the conductive particles 51. In this embodiment,
The point is that the device on which the IC chip is mounted is an active matrix display device. A plurality of switching elements 5 are arranged in the active matrix display device. By providing the bumps on the side of the display device, the bumps can be formed at the same time as the switching element 5, so that an increase in manufacturing cost can be suppressed.

FIG. 6 shows the switching element 5 of the display device 1.
FIG. A buffer layer 31 for preventing impurity diffusion from the main body substrate 2 is formed on the main body substrate 2 made of alkali-free glass that does not contain an alkali element such as sodium. A polycrystalline silicon film 32 is arranged as an active layer on the buffer layer 31, and a gate insulating film 33 is formed so as to cover the polycrystalline silicon film 32. A gate electrode 34 is formed on the gate insulating film 33 so as to overlap a part of the polycrystalline silicon film 32 and branched from the gate line 9, and an interlayer insulating film 35 is formed to cover the gate electrode 34. A data line 10 connected to the polycrystalline silicon film 32 via a contact hole is arranged on the interlayer insulating film 35, and a flattening film 36 is formed so as to cover the data line 10. On the flattening film 36, the interlayer insulating film 35 and the pixel electrode 4 connected to the polycrystalline silicon film 32 via a contact hole provided in the flattening film 36 are formed.

Here, the flattening film 36 is formed on the gate electrode 34.
It is formed by applying an acrylic resin and then solidifying the acrylic resin in order to flatten the irregularities caused by the polycrystalline silicon film 32 and the like, and has a flat surface. The pixel electrode 4 is
Since it is disposed on the flattening film 36, it is flat in the region other than the contact holes. In this way, the pixel electrode 4 is made flat and the display quality is improved. This flattening film has a thickness several times as large as that of other insulating films in order to absorb the unevenness of the lower layer. Optimal. Therefore, in the present embodiment, the bumps are arranged on the main body substrate side, and the flattening film 36 is formed, and at the same time, the insulating film 25 of the bumps is formed, thereby suppressing an increase in the number of steps.

Of course, also in the first embodiment, I
If the insulating film having the same thickness as the insulating film 20 is formed in a single layer or a plurality of layers in the circuit of the C chip, the film can be used as the insulating film 20 to form bumps on the IC chip side. At the same time, it is possible to reduce the number of manufacturing steps.

[0026]

As described in detail above, according to the present invention, an insulating film in which bumps to be pressed by an anisotropic conductive film are formed so as to cover the terminal portion and a plurality of openings are provided on the terminal portion. Since the film and the conductive film formed to cover the insulating film and connected to the terminal portion through the plurality of openings are formed, the material cost can be reduced as compared with the gold bump.

Further, since the thickness of the insulating film forming the bump is larger than the diameter of the conductive particles, the bump height can be sufficiently secured even if the conductive film forming the bump is formed thin. Good connection can be achieved through the anisotropic conductive film.

Furthermore, since the distance between the openings is at least 10 times larger than the diameter of the openings, the upper surface of the bump is
It becomes flat in almost all areas, and the height of the bump does not vary depending on the position of the conductive particles, so that the connection can be further improved.

Further, since the diameter of the opening is larger than the diameter of the conductive particles and smaller than the diameter of the conductive particles plus twice the film thickness of the conductive film, the bumps caused by the openings can be formed. Since the dent on the upper surface is smaller than the diameter of the conductive particle, it is possible to prevent the conductive particle from entering the dent and causing conduction failure.

Further, since the diameter of the opening is almost equal to the film thickness of the insulating film, the aspect ratio of the opening becomes approximately 1,
It is possible to prevent the formation of a deep depression on the upper surface of the opening and make the surface substantially flat. Therefore, it is possible to prevent conductive particles from entering the recesses and prevent poor conduction.

Further, particularly when the device on which the integrated circuit is mounted is an active matrix type display device, a plurality of switching elements are arranged on this main body substrate, and at least a part of the bumps is used as this switching element. By forming them at the same time, it is possible to minimize the increase in the manufacturing process and prevent the manufacturing cost from increasing.

Further, as the bump insulating film, the flattening film of the switching element is optimal in terms of material and film thickness.

[Brief description of drawings]

FIG. 1 is a perspective view showing a display device of the present invention.

FIG. 2 is a perspective view showing a display device and an integrated circuit of the present invention.

FIG. 3 is a sectional view showing a bump according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing an insulating film 20 forming a bump of the present invention.

FIG. 5 is a sectional view showing a bump according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing a switching element according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a conventional gold bump.

[Explanation of symbols]

1: Display device 2: Main substrate 3: Counter substrate 4: Pixel electrode 5: TFT (Switching element) 6: Common electrode 7, 8: Driving IC chip 9: Gate line 10: Data line 41, 43: Terminal portion 20, 25: bump insulating film 21, 26: bump conductive film 32: polycrystalline silicon film 34: gate electrode 35: interlayer insulating film 36: flattening film 50: ACF adhesive 51: ACF conductive particles

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/30 330 G09F 9/30 348A 348 H05K 3/32 B H05K 3/32 H01L 21/92 602C 603C 602K (72) Yasushi Miyajima, 2-5-5 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd. (72) Koji Hirosawa, 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. In-house F-term (reference) 2H092 GA48 GA55 JA24 JB21 JB56 KA04 KB13 MA05 NA15 NA27 NA29 5C094 AA43 AA44 AA45 BA03 BA43 CA19 DA15 DB01 EA02 FB12 5E319 AA03 AB05 BB16 KK20 KK20 KK16QQ02AQ4QQ02 AQ4QQ02AQ4

Claims (12)

[Claims] 1. An integrated circuit in which a plurality of elements are arranged on a substrate, wherein the integrated circuit is pressure-bonded to an external device via an anisotropic conductive film formed by dispersing conductive particles in an adhesive. A bump for mounting on the substrate, the bump having a terminal portion formed on the substrate, and an insulating film formed to cover the terminal portion and having a plurality of openings formed on the terminal portion. And a conductive film formed to cover the insulating film and connected to the terminal portion through the plurality of openings. 2. The integrated circuit according to claim 1, wherein the thickness of the insulating film is larger than the diameter of the conductive particles. 3. The integrated circuit according to claim 1, wherein the distance between the openings is at least 10 times larger than the diameter of the openings. 4. The diameter of the opening is larger than the diameter of the conductive particles, and smaller than the diameter of the conductive particles plus twice the film thickness of the conductive film. The integrated circuit according to claim 1. 5. The integrated circuit according to claim 1, wherein a diameter of the opening is substantially equal to a film thickness of the insulating film. 6. A display device having a bump for mounting an integrated circuit by pressure bonding on a substrate surface via an anisotropic conductive film formed by dispersing conductive particles in an adhesive, the bump comprising:
A terminal formed on the substrate; an insulating film formed on the terminal and having a plurality of openings; and a conductive film formed on the insulating film and electrically connected to the terminal through the openings. Characteristic display device. 7. The display device according to claim 6, wherein a film thickness of the insulating film is larger than a diameter of the conductive particles. 8. The display device according to claim 6, wherein the distance between the openings is at least 10 times larger than the diameter of the openings. 9. The diameter of the opening is larger than the diameter of the conductive particles and smaller than the diameter of the conductive particles plus twice the film thickness of the conductive film. The display device according to claim 6. 10. The display device according to claim 6, wherein the diameter of the opening is substantially equal to the film thickness of the insulating film. 11. The display device is an active matrix type having a plurality of switching elements on a substrate,
7. The display device according to claim 6, wherein at least a part of elements forming the bump is formed at the same time as the switching element. 12. The switching element has a flattening film for flattening unevenness of a lower layer, and the insulating film of the bump is formed simultaneously with the flattening film. Display device described.