JP2004062133A - Manufacturing method of substrate for chip on glass, and mounting method of chip on glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a substrate for a COG by which damage of a COG pad can be prevented at the time of reworking. <P>SOLUTION: A manufacturing process of the substrate for the COD comprises a step for providing the substrate provided with a COG region, a step for forming the COG pad in the COG region on the substrate, a step for forming a slow down layer on the COG pad and the substrate, a step for forming a thick organic layer on the slow down layer, a step for forming a first hole positioned above the COG pad and exposing the slow down layer and a second hole comprising the first hole and having a thin organic layer left at a bottom part at the thick organic layer by a lithography process, a step for removing a part of the slow down layer using the organic layer as an etching mask to expose a part of the COG pad, a step for removing the thin organic layer and a step for forming a conductive layer on the COG pad. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a chip on glass (COG) manufacturing process for a liquid crystal display (LCD), and more particularly, to a method for manufacturing a COG substrate capable of avoiding damage to a COG pad during rework.
[0002]
[Prior art]
In recent years, liquid crystal display panels (LCD panels) have been widely replaced by cathode ray tubes (CRTs) in display device applications. In the assembly manufacturing process of the liquid crystal display panel, first, an LCD substrate and a transparent substrate are combined. The LCD substrate includes many switches, for example, TFTs (Thin Film Transistors) and the like, thereby controlling many pixels. After combining the LCD panel, the panel must be bonded to a printed circuit board (PCB). At present, COG technology for mounting a chip on a glass substrate is attracting attention and used.
[0003]
By the way, in this COG technique, when a chip bonding failure or the like occurs, an operation of removing the chip from the substrate (rework operation) may be performed. During the operation of removing the chip from the substrate, damage such as separation of the COG pad and other elements such as an organic layer, a blunt layer, and a conductive wire may frequently occur.
[0004]
In the following, with reference to FIG. 1, a problem that occurs when a known COG structure is reworked will be described. FIG. 1 shows a cross-sectional view of a known COG structure. The substrate 100, the COG pad 110, the blunt layer 120, the organic layer 130, the ITO (Indium Tin Oxide) layer 140, the ACF (Anisotropic Conductive Film) layer 150, and the gold bumps and the chip 170. However, when the reworking operation is necessary, the space 180 above the pad 110 is quite narrow, and thus the organic layer 130, the blunting layer 120, and the pad 110 are often damaged in the step of removing the chip 170 (reworking step).
[0005]
As a technique for solving the problem of damage caused at the time of rework described above, a method for manufacturing a COG substrate shown in FIGS. 2 to 5 is known (see, for example, Patent Documents 1 to 5).
[0006]
[Patent Document 1] US Pat. No. 6,337,723 [Patent Document 2] US Pat. No. 6,424,401 [Patent Document 3] US Pat. No. 5,946,065 [Patent Document 4] US Pat. No. 5,706,064 [Patent Document 3] Document 5: US Pat. No. 5,748,179
Initially, a substrate 200 comprising a metal layer (not shown) is provided. Next, a COG pad 210 is formed from the metal layer by performing a lithography process using the first mask. Thereafter, the blunt layer 220 and the photosensitive organic layer 230 are sequentially stacked on the substrate 200.
[0008]
Then, as shown in FIG. 3, a lithography process is performed on the organic layer 230 using a second mask to form a first hole 240 having an appropriate rework space, and a part of the blunt layer 220 is exposed.
[0009]
Next, as shown in FIG. 4, a lithography process is performed using a third mask, and the blunt layer 220 located above the COG pad 210 is removed by etching, and the second hole exposing the COG pad 210 surface. 250 is formed.
[0010]
Subsequently, as shown in FIG. 5, an ITO layer (not shown) is laminated on the blunt layer 220 and the organic layer 230, and the ITO layer 260 is formed on the COG pad 210 using a fourth mask. To do.
[0011]
[Problems to be solved by the invention]
Thus, in the above-described method for manufacturing a COG substrate, in order to provide an appropriate rework space for preventing damage to the COG pad during rework, a total of four masks are required in the manufacturing process. The increase in cost and manufacturing time cannot be suppressed.
[0012]
SUMMARY OF THE INVENTION An object of the present invention is to provide a manufacturing process of a COG substrate that can prevent chip-on-glass (hereinafter referred to as COG) pad damage during rework. Another object of the present invention is to provide a mounting method for preventing damage to the COG pad during rework.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a method for manufacturing a substrate for COG that can prevent damage to a chip-on-glass (hereinafter referred to as COG) pad during rework, and a step of providing a substrate having a COG region; A step of forming a COG pad in the COG region, a step of forming a blunt layer on the COG pad and the substrate, a step of forming a thick organic layer on the blunt layer, and a portion of the thick organic layer. By removing the first hole located above the COG pad and exposing the surface of the blunt layer and the first hole, a thin organic layer is left at the bottom, and the opening area is larger than the COG region A step of forming a second hole, a part of the blunt layer is removed using the thick organic layer and the thin organic layer as an etching mask, and a part of the COG pad Exposing a was intended to comprise the step of removing the thin organic layer of the second hole bottom portion, and forming a conductive layer on the COG pad, a.
[0014]
The method of removing a portion of the thick organic layer and leaving the thin organic layer at the bottom of the second hole includes a step of performing a lithography process on the thick organic layer using a photomask, The mask has a first pattern in which the installation position corresponds to the first hole and can transmit light, and a second pattern in which the installation position corresponds to the second hole and can reduce light transmission intensity, It is preferable to consist of.
[0015]
The second pattern of the photomask is preferably a halftone pattern, and the second pattern of the photomask preferably includes a plurality of micropatterns.
[0016]
The substrate is preferably made of glass, and the COG pad is preferably formed of a stack of titanium (Ti) / aluminum (Al) / titanium (Ti). The blunt layer is preferably silicon nitride. Further, the thick organic layer is preferably made of a photosensitive organic material, and the conductive layer is preferably ITO.
[0017]
When the COG substrate is manufactured by the above-described method for manufacturing a COG substrate according to the present invention, a COG mounted product is obtained by mounting by performing a step of electrically connecting a chip to the conductive layer of the COG substrate. Even if a bonding failure occurs, the rework operation can be performed without causing damage to the COG pad or the like.
[0018]
The COG substrate obtained by the method for manufacturing a COG substrate of the present invention is further subjected to a reworking step for removing the chip from the COG mounted product in which the chip is electrically connected to the conductive layer of the COG substrate. It is also possible to perform a step of electrically connecting the chip to the substrate. According to the COG mounted product using the COG substrate obtained by the manufacturing method of the present invention, the COG pad or the like is not damaged by the reworking operation. Connection can be made, and the manufacturing yield of the COG mounted product can be improved.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
In order to further clarify the above-described objects, features, and advantages of the present invention, preferred embodiments of the present invention will be given below and described in detail with reference to the drawings.
[0020]
The manufacturing process of the substrate for COG according to the present invention will be described with reference to FIGS. FIG. 12 is a plan view of the photomask used to form the COG pad in FIG. FIG. 13 is a plan view of the photomask used to form the holes in FIG.
[0021]
First, as shown in FIG. 6, a substrate 300 made of glass is provided. The substrate 300 includes at least one COG region 310. A metal layer (not shown) is stacked on the substrate 300. Subsequently, the first photomask 910 shown in FIG. 12 is used to form a patterned COG pad 320 by performing a lithography process on the metal layer. At this time, the COG pad 320 is electrically connected to a data line (not shown) and a scan line (not shown) transistor element (not shown) on the substrate 300. The COG pad 320 is composed of, for example, a stacked metal layer structure of titanium (Ti) / aluminum (Al) / titanium (Ti).
[0022]
The photomask shown in FIG. 12 includes an opaque region 920 and a transparent region 930. The opaque region 920 corresponds to the position of the COG pad 320 in FIG.
[0023]
Next, as shown in FIG. 6, a blunt layer 330 that is, for example, a silicon nitride (SiN) layer is laminated on the COG pad 320 and the surface of the substrate 300. Subsequently, a thick organic layer 340 that is a photosensitive material, i.e., having photoresist characteristics, is formed on the blunt layer 330.
[0024]
Next, as shown in FIG. 7, for example, a lithography process is performed using the second mask 1010 shown in FIG. 13, and the thick organic layer 340 is removed by etching, so that the first hole 410 and the second hole 420. Is formed. In the lithography process in this case, the first hole 410 and the second hole 420 of the thick organic layer 340 are simultaneously formed by using the pattern profile on the second mask. In addition, the blunt layer 330 formed above the COG pad 320 and exposed above the COG pad 320 is exposed, and the thin organic layer 430 remains at the bottom of the second hole 420, and the opening area of the second hole 420 is It becomes larger than the COG region 310.
[0025]
The photomask 1010 in FIG. 13 includes a first pattern 1020, a second pattern 1030, and a third pattern 1040. The first pattern 1020 (transparent region) is used for light transmission and corresponds to the first hole 410. The second pattern 1030 (semi-transparent region) is used to reduce the light transmission intensity and corresponds to the second hole 420. The third pattern 1040 (opaque region) is used for light shielding and corresponds to a region where the thick organic layer 340 is not etched.
[0026]
Here, the pattern profile of the second pattern 1030 will be described as an example, but the present invention is not limited thereto. Since the second pattern 1030 is required to have an effect of reducing the light transmission intensity, the second pattern 1030 is a halftone pattern. Thus, the second pattern 1030 includes a plurality of micropatterns 1060 separated by appropriate slits 1050. The micro pattern 1060 may be a translucent pattern or a non-translucent pattern, but when the micro pattern 1060 is formed, the slit 1050 of each micro pattern 1060 must be non-translucent. On the other hand, when the micro pattern 1060 is a non-light-transmitting pattern, the slit 1050 must be light-transmitting. By controlling the size of the micropattern 1060 or the slit 1050, the light beam is partially blocked and not completely transmitted, and the light intensity is reduced during the lithography process, so that the thick organic layer 340 is completely exposed. Do not. That is, after the lithography is completed, an organic layer having a certain thickness (thin organic layer 430) remains. The shape design of the micro pattern 1060 is not particularly limited, and may be any shape such as a rectangle, a circle, a square, a rhombus, and a triangle. For example, when the micropattern 1060 is a non-transparent square pattern, the side length is 2 to 5 μm and the interval 1050 is about 1 to 5 μm. Furthermore, the residual thickness of the thin organic layer 430 is preferably 1.5 to 4.0 μm. This is because the etching process described later can be performed satisfactorily.
[0027]
Next, as shown in FIG. 8, the thick organic layer 340 and the thin organic layer 430 serve as an etching mask, and the blunt layer 330 in the first hole 410 is removed by etching to expose a part of the COG pad 320. Subsequently, the thin organic layer 430 is removed by etching to expose the blunt layer 330 in the second hole 420. It should be noted that the thin organic layer 430 may also be removed at the same time in the course of etching away the blunt layer 330 in the first hole 410.
[0028]
Then, as shown in FIG. 9, the conductive layer 610 is laminated on the thick organic layer 340, the blunt layer 330, and the COG pad 320.
[0029]
Subsequently, as shown in FIG. 10, a patterned photoconductive layer 610 ′ is formed on the COG pad 320 by performing a lithography process using a third photomask (similar to the photomask of FIG. 12, not shown). Form. The conductive layer 610 ′ is, for example, an ITO layer.
[0030]
Further, as shown in FIG. 11, a mounting step of electrically connecting the chip 810 to the conductive layer 610 ′ is performed. In FIG. 11, a chip 810 is, for example, a driving IC chip, 820 is a gold bump, and 830 is an ACF (anisotropic conductive film).
[0031]
Thereafter, in the rework work for removing the chip 810 with respect to the COG mounted product obtained as described above, the opening area of the second hole 420 is larger than the COG region 310, so that a sufficient rework space ( That is, there is a second hole 420), and elements such as the thick organic layer 340 and the COG pad 320 are hardly damaged.
[0032]
Although preferred embodiments of the present invention have been disclosed in the present invention as described above, these are not intended to limit the present invention in any way, and any person who is familiar with the technology can make various modifications within the scope of the spirit and scope of the present invention. Variations and moist colors can be added, so the protection scope of the present invention is based on what is specified in the claims.
[0033]
【The invention's effect】
According to the present invention, since the opening area of the second hole is larger than the COG pad, there is sufficient work space during rework, avoiding the problem of damaging the organic layer and the COG pad, and improving the reliability of the product. I can do it. And in the manufacturing process of the substrate for COG of this invention, compared with a well-known method, since only three photomasks are sufficient and there is one mask, cost can also be suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a known COG structure.
FIG. 2 is a cross-sectional view showing a manufacturing process of a known COG substrate.
FIG. 3 is a cross-sectional view showing a known manufacturing process of a COG substrate.
FIG. 4 is a cross-sectional view showing a manufacturing process of a known COG substrate.
FIG. 5 is a cross-sectional view showing a manufacturing process of a known COG substrate.
FIG. 6 is a cross-sectional view showing a manufacturing process of the COG substrate of the present invention.
FIG. 7 is a cross-sectional view showing a manufacturing process of the COG substrate of the present invention.
FIG. 8 is a cross-sectional view showing a manufacturing process of the COG substrate of the present invention.
FIG. 9 is a cross-sectional view showing a manufacturing process of the COG substrate of the present invention.
FIG. 10 is a cross-sectional view showing a manufacturing process of the COG substrate of the present invention.
FIG. 11 is a cross-sectional view showing a manufacturing process of a COG substrate of the present invention.
12 is a plan view of a photomask used for forming the COG substrate defined in FIG. 6. FIG.
FIG. 13 is a plan view of a photomask used to form the holes defined in FIG.
[Explanation of symbols]
100, 200 Substrate 110, 210 COG pad 120, 220 Blunt layer 120, 230 Organic layer 140, 260 ITO layer 150 ACF layer 160 Gold bump 170 Chip 180 Space 240, 250 Hole 300 Substrate 330 Blunt layer 340 Thick organic layer 410 First Hole 420 Second hole 430 Thin organic layer 610, 610 'Conductive layer (ITO layer)
810 Chip 820 Gold bump 830 ACF
910 First photomask 920 Non-transparent region 930 Translucent region 1010 Second photomask 1020 First pattern 1030 Second pattern 1040 Third pattern 1050 Slit 1060 Micro pattern

Claims (11)

A method for manufacturing a substrate for COG capable of preventing damage to a chip-on-glass (hereinafter referred to as COG) pad during rework,
Providing a substrate comprising a COG region;
Forming a COG pad in the COG region;
Forming a blunt layer on the COG pad and the substrate;
Forming a thick organic layer on the blunt layer;
By removing a part of the thick organic layer, a first hole located above the COG pad and exposing the surface of the blunt layer, and the first hole including the thin organic layer remaining at the bottom Forming a second hole having an area larger than the COG region;
Using the thick organic layer and the thin organic layer as an etching mask, removing a portion of the blunt layer and exposing a portion of the COG pad;
Removing a thin organic layer at the bottom of the second hole;
Forming a conductive layer on the COG pad;
A method for manufacturing a substrate for COG, comprising: The method of removing a portion of the thick organic layer and leaving the thin organic layer at the bottom of the second hole includes:
The photomask comprises a step of performing a lithography process on the thick organic layer,
The photomask has a first pattern in which the installation position corresponds to the first hole and can transmit light, and a second pattern in which the installation position corresponds to the second hole and can reduce light transmission intensity. When,
The manufacturing method of the board | substrate for COG of Claim 1 which consists of these. The substrate for COG according to claim 2, wherein the second pattern of the photomask is a halftone pattern. 4. The COG substrate according to claim 2, wherein the second pattern of the photomask includes a plurality of micro patterns. The said board | substrate is glass, The manufacturing method of the board | substrate for COG in any one of Claims 1-4. 6. The method for manufacturing a substrate for COG according to claim 1, wherein the COG pad is a stack of titanium (Ti) / aluminum (Al) / titanium (Ti). The method for manufacturing a substrate for COG according to any one of claims 1 to 6, wherein the blunt layer is silicon nitride. The said thick organic layer consists of photosensitive organic materials, The manufacturing method of the board | substrate for COG in any one of Claims 1-7. The said conductive layer is ITO, The manufacturing method of the board | substrate for COG in any one of Claims 1-8. A COG mounting method, wherein a COG mounting product is obtained by performing a step of electrically connecting a chip to a conductive layer of a COG substrate obtained by the manufacturing method according to claim 1. . The COG mounting method according to claim 10, further comprising a rework step of removing the chip from the COG mounted product, and a step of electrically connecting the chip to the COG substrate.

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