Liquid crystal panel manufacturing method

Abstract

The present invention provides a liquid crystal panel manufacturing method that enables the stable and high-yield production of thin liquid crystal panels. [Solution] A liquid crystal panel manufacturing method comprising the steps of: forming a mother board 1 by bonding a first substrate 2 and a second substrate 3 in wafer state via peripheral seals 4 corresponding to a plurality of image display areas; forming a protective film 6 on the surface of the first substrate 2 on the mother board 1, having openings that expose the street portion (area to be cut) of the first substrate 2; and cutting the first substrate 2 by performing dry etching on the protective film 6 to remove the street portion of the first substrate 2 exposed through the openings.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for manufacturing a liquid crystal panel.

BACKGROUND ART

[0002] The liquid crystal panel includes, for example, two substrates facing each other, a peripheral seal for bonding the two substrates together, liquid crystal injected into a region between the two substrates and surrounded by the peripheral seal, and electrodes and alignment films provided on the opposing surface sides of each of the two substrates.

[0003] FIG. 3 is (a) a top view and (b) an A-A' cross-sectional view showing the liquid crystal panel. As a conventional manufacturing method of the liquid crystal panel shown in FIG. 3, pixel electrodes are formed on one of two substrates in a wafer state (for example, glass and Si) so that a plurality of image display regions are formed, an alignment film is formed over the pixel electrodes, a common electrode corresponding to each image display region is formed on the other substrate, an alignment film is formed over the common electrode, then a peripheral seal 4 is provided so as to surround each image display region, the two substrates are aligned and bonded to each other, thereafter the two substrates are divided for each individual image display region to produce a plurality of hollow liquid crystal panels (empty cells), subsequently liquid crystal is injected from a liquid crystal injection port provided in a part of the peripheral seal 4 of each individual liquid crystal panel, and then the liquid crystal injection port is sealed with a sealing material similar to the peripheral seal 4, whereby the liquid crystal panel 10 with liquid crystal sealed inside is produced, and such a manufacturing method is known (see, for example, Patent Document 1).

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0004]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] In conventional liquid crystal panel manufacturing methods, when the substrate constituting the liquid crystal panel is very thin (for example, when the total thickness of the bonded glass and Si is about 0.1 mm), there is a risk that the substrate itself will crack during flow when using 8-inch or 12-inch wafers, making it difficult to flow up to the bonding process. Even if flow is successful, stress is applied during the subsequent dicing process when the dicing blade cuts the material, causing distortion or damage to the liquid crystal panel (empty cell) before liquid crystal is injected, potentially leading to a significant decrease in yield. In addition, handling is difficult when injecting liquid crystal into the empty cell, raising concerns about a significant decrease in yield during the liquid crystal injection to sealing process. The present invention aims to provide a liquid crystal panel manufacturing method that enables the stable and high-yield production of thin liquid crystal panels. [Means for solving the problem]

[0006] A process for forming a motherboard by bonding a first substrate and a second substrate in wafer form via peripheral seals corresponding to multiple image display areas, A step of forming a protective film on the surface of the first substrate of the motherboard, having an opening that exposes the street portion of the first substrate, The process involves dry etching the protective film to remove the street portion of the first substrate exposed from the opening, and cutting the first substrate. A method for manufacturing a liquid crystal panel, characterized by having the following:

[0007] The method for manufacturing a liquid crystal panel according to claim 1, characterized in that the protective film is removed by dry etching, and then the surface of the first substrate exposed by removing the protective film is scraped to thin the first substrate.

[0008] The method for manufacturing a liquid crystal panel according to claim 1, characterized in that, after forming the protective film, the street portion of the second substrate on the mother substrate is cut by dicing.

[0009] The method for manufacturing a liquid crystal panel according to claim 3, characterized in that liquid crystal is injected through an injection port into the region surrounded by the peripheral seal through a cut in the second substrate formed by cutting the street of the second substrate, and the injection port is sealed.

[0010] The method for manufacturing a liquid crystal panel according to claim 4, characterized in that, after sealing the opening, the surface of the second substrate is polished to thin the second substrate.

[0011] The method for manufacturing a liquid crystal panel according to claim 1, characterized in that a protective film is applied to the surface of the second substrate before performing the dry etching. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for manufacturing liquid crystal panels that enables the stable production of thin liquid crystal panels with a high yield. [Brief explanation of the drawing]

[0013] [Figure 1] This is a flowchart illustrating the manufacturing method of a liquid crystal panel according to the present invention. [Figure 2-1] This is a vertical cross-sectional view showing the manufacturing method of a liquid crystal panel according to the present invention, and includes (a) a lamination process diagram, (b) a polishing process diagram, (c) a film formation process diagram, (d) a patterning process diagram, and (e) a dicing process diagram. [Figure 2-2] This is a vertical cross-sectional view showing the manufacturing method of a liquid crystal panel according to the present invention, and includes (f) a diagram of the liquid crystal injection and sealing process, (g) a diagram of the glass polishing process, (h) a diagram of the dry etching process, and (i) a diagram of the completed liquid crystal panel. [Figure 3] (a) is a top view and (b) is a cross-sectional view along A-A' showing the liquid crystal panel. [Modes for carrying out the invention]

[0014] An example of the method for manufacturing a liquid crystal panel according to the present invention is shown below.

[0015] Figure 1 is a flowchart showing the manufacturing method of a liquid crystal panel according to the present invention. Figure 2 (Figures 2-1 and 2-2) is a side view showing the manufacturing method of a liquid crystal panel according to the present invention, and includes (a) a lamination process diagram, (b) a polishing process diagram, (c) a protective film process diagram, (d) a patterning process diagram, (e) a dicing process diagram, (f) an injection process diagram, (g) a polishing process diagram, (h) a dry etching process diagram, and (i) a completed liquid crystal panel diagram.

[0016] First, as shown in Figure 2(a), a mother substrate 1 (a composite substrate after bonding) is fabricated by bonding and fixing a first substrate 2 (e.g., Si) and a second substrate 3 (e.g., glass) in wafer form with their electrode surfaces facing each other using a peripheral seal 4 containing spacers. The spacers create a gap between the substrates, and the size of this gap depends on the size of the spacers. At this time, the thickness of the first substrate 2 and the second substrate 3 (each thickness) is, for example, about 0.7 mm. The peripheral seal 4 is positioned to surround the effective pixel area and is cured by heat or UV irradiation.

[0017] Next, as shown in Figure 2(b), the surfaces of the first substrate 2 and the second substrate 3 of the motherboard 1 shown in Figure 2(a) are polished using a polishing device. The thickness of the first substrate 2 and the second substrate 3 after polishing is, for example, about 0.3 mm. However, if substrates with a thickness of 0.3 mm can be prepared in advance, this step can be omitted. Wet polishing is performed by applying water or water-soluble polishing oil. This allows for cooling of the heat generated by grinding resistance, and the use of water improves work efficiency and shortens the construction period. Dry polishing is a method of polishing without applying water, and post-processing is also easy. Either of these polishing methods can be selected and performed.

[0018] Next, as shown in Figure 2(c), a protective film 6 is formed on the surface of the first substrate 2 of the motherboard 1. The protective film 6 is composed of, for example, a photoresist or a patternable PI. If the viscosity is low, it is desirable to use a spinner device or the like to apply the protective film 6 uniformly. The protective film 6 is mainly of the thermosetting or UV curing type.

[0019] Next, as shown in FIG. 2(d), patterning is performed on the protective film 6 formed in the step of FIG. 2(c). The patterning can be performed using a well-known photolithography technique. By this patterning, an opening is formed in the protective film 6, through which the street portion (region to be cut) of the second substrate 3 is exposed.

[0020] Next, as shown in FIG. 2(e), the second substrate 3 of the mother substrate 1 is cut by dicing at a predetermined position. The wafer is cut while rotating the dicing saw 8 at high speed, so that the second substrate 3 is divided into individual pieces. As the cutting method, one of two dicing methods, half cut and full cut, is appropriately selected. The half cut is a method of cutting the wafer to an intermediate depth in the thickness, and after the cutting, a step of breaking the uncut remaining thickness is performed. Note that the dicing is performed at a position facing the opening of the protective film 6 formed by the patterning in FIG. 2(d).

[0021] Next, as shown in FIG. 2(f), liquid crystal 5 is injected into the gap between the first substrate 2 and the second substrate 3. The peripheral seal 4 that bonds the first substrate 2 and the second substrate 3 is provided with injection ports for injecting the liquid crystal 5. The liquid crystal 5 in a high-viscosity state is collectively applied in the vicinity of each injection port through the cuts of the second substrate 3 formed by the dicing in FIG. 2(e), and the viscosity of the liquid crystal 5 is reduced by heating, so that the liquid crystal 5 is injected through the injection ports. For the injection of the liquid crystal 5, vacuum injection, capillary action or the like can be appropriately utilized. After the injection, the injection ports are sealed using a sealing material 7 made of a UV-curable resin or the like so that the liquid crystal 5 does not flow out. In conventional liquid crystal panel manufacturing methods, the injection and sealing of the liquid crystal 5 are performed after the mother substrate is divided into individual pieces, but in the step of FIG. 2(f), these operations can be performed collectively in the state of the mother substrate. Further, unnecessary liquid crystal adhering to the surface of the mother substrate 1 can be collectively removed by ashing, IPA cleaning, dry etching, or the like.

[0022] Next, as shown in Figure 2(g), the surface of the second substrate 3 is polished to reduce its thickness to a predetermined thickness. At this point, since the injection of the liquid crystal 5 and the sealing of the injection port have already been completed, distortion of the substrate due to polishing is less likely to occur than when polishing in an empty cell state. Furthermore, if the substrate warps during the polishing of the second substrate 3, a protective film 6 formed on the first substrate 2 in the process shown in Figure 2(c) may be selected that has properties that mitigate warping caused by polishing.

[0023] Next, as shown in Figure 2(h), dry etching is performed on the surface (back side) of the first substrate 2 of the motherboard 1. Dry etching is an etching method that uses ions, high-speed neutral particles, and radicals generated by plasma-forming gases such as etching gases. Dry etching removes the street portion of the first substrate 2 exposed through the openings in the protective film 6, and at the same time, the protective film 6 formed on the surface of the first substrate 2 is also gradually removed. As dry etching progresses, the protective film 6 is completely removed first, and then by continuing dry etching, the entire surface (back side) of the second substrate 3 is gradually removed, making the first substrate 2 thinner.

[0024] Then, as shown in Figure 2(i), dry etching is performed until the street portion of the first substrate 2 is completely removed. This separates the mother substrate 1 into individual pieces, resulting in a finished liquid crystal panel.

[0025] Furthermore, if a protective film is applied to the surface of the second substrate 3 before performing the dry etching shown in Figures 2(h) to (i), chipping of the liquid crystal panel after individualization can be prevented.

[0026] Furthermore, as a modified version of the liquid crystal panel manufacturing method shown in Figure 2, for example, after the process in Figure 2(d), a protective film can be applied to the surface of the second substrate 3, and the dicing of the second substrate 3 in Figure 2(e) can be omitted. In this case, the mother substrate 1 can be separated into individual pieces by dry etching in Figure 2(i), which removes not only the street portions of the first substrate 2 but also the street portions of the second substrate 3. However, in this case, liquid crystal injection and sealing will be performed after the mother substrate 1 has been separated into individual pieces.

[0027] The manufacturing method of the present invention reduces the risk of the substrate cracking during production, enabling the stable and high-yield mass production of thin liquid crystal panels.

[0028] Furthermore, the materials of the first substrate 2 and the second substrate 3 are not limited to Si (silicon) and glass, but may be other materials.

[0029] The present invention is not limited to the embodiments described above, and various other embodiments are possible. [Explanation of Symbols]

[0030] 1 Motherboard 2 First board 3 Second board 4. Peripheral seal 5 LCD 6 Protective film 7 Sealing material 8 Dicing Saws 10 LCD panels 11 Terminal section

Claims

1. A process for forming a motherboard by bonding a first substrate and a second substrate in wafer form via peripheral seals corresponding to multiple image display areas, A step of forming a protective film on the surface of the first substrate of the motherboard, having an opening that exposes the street portion of the first substrate, The process involves dry etching the protective film to remove the street portion of the first substrate exposed from the opening, and cutting the first substrate. A method for manufacturing a liquid crystal panel, characterized by having the following:

2. The method for manufacturing a liquid crystal panel according to claim 1, characterized in that the protective film is removed by dry etching, and then the surface of the first substrate exposed by removing the protective film is scraped to thin the first substrate.

3. The method for manufacturing a liquid crystal panel according to claim 1, characterized in that, after forming the protective film, the street portion of the second substrate on the mother substrate is cut by dicing.

4. The method for manufacturing a liquid crystal panel according to claim 3, characterized in that liquid crystal is injected through an injection port into the region surrounded by the peripheral seal through a cut in the second substrate formed by cutting the street of the second substrate, and the injection port is sealed.

5. The method for manufacturing a liquid crystal panel according to claim 4, characterized in that, after sealing the opening, the surface of the second substrate is polished to thin the second substrate.

6. The method for manufacturing a liquid crystal panel according to claim 1, characterized in that a protective film is applied to the surface of the second substrate before performing the dry etching.

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