JP2001021873A - Production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to remove the flaws, dirt, residual films, etc., produced in a wafer deposition stage for transparent substrates constituting liquid crystal display devices by automatic work. SOLUTION: The surfaces having TFT patterns of the wafers 10 are provided with resist films 12 and protective tapes 14 are stuck thereto. The wafers 10 are fed into a CMP device and the rear surfaces of the wafer 10 are automatically subjected to polishing, washing and drying. The wafers 10 are then taken out of the CMP device and the resist film 12 and the protective tapes 14 are removed. In the CMP device, the wafers 10 are held at a polishing head 40 and are brought into contact with a wafer pad 42 disposed atop a turn table 44. While the turn table 44 is rotatably driven and a polishing liquid is supplied, the rear surfaces of the wafers 10 are polished and the flaws, dirt, residual films, etc., produced in the wafer deposition stage are removed. The rear surfaces of the wafers 10 are then washed and dried and are transferred to the ensuing stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly to a method for processing a transparent substrate wafer constituting a liquid crystal display device, which removes scratches, stains, residual films, etc., generated on the outer surface of the transparent substrate. To a method for removal.

[0002]

2. Description of the Related Art Heretofore, there has been provided a transmission type liquid crystal display device in which a pair of transparent substrates are joined via a spacer and a sealing material, and liquid crystal is sealed between the transparent substrates. A TFT (thin film transistor) as a driving element corresponding to each pixel, an electrode film and an alignment film are provided on the inner surface of one transparent substrate, and a counter electrode film and an alignment film are provided on the inner surface of the other transparent substrate. Is provided. Further, a color filter is provided on the outer surface of the other transparent substrate. In such a liquid crystal display device, a transparent substrate provided with a TFT (TFT substrate)
Light input from the side is emitted from the transparent substrate (CF substrate) side provided with a color filter through the liquid crystal layer to display various color images. In addition, each of the above-described substrates is formed by forming a plurality of substrates in a batch in a wafer state and then dividing the wafer for each substrate.

[0003]

In the above-mentioned liquid crystal display device, during the process of forming a film such as a TFT on the inner surface of the transparent substrate, the outer surface (rear surface of the wafer) of the transparent substrate is damaged. In some cases, particularly in the case of a transmissive liquid crystal display device, scratches and the like appear in the image, resulting in poor quality. Therefore, conventionally, in a state where each transparent substrate is divided from a wafer, only those having defects such as scratches are polished using a normal glass polishing apparatus. However, an ordinary glass polishing apparatus is basically a manual dry-in-wet-out system, which requires a separate cleaning after polishing, and it is difficult to automate the transition to the next step. is there. Therefore, conventionally, as described above, an image of a transparent substrate having a defect is checked and determined and inspected, and the corresponding transparent substrate is subjected to a manual polishing process. However, there is a problem that the manufacturing cost is increased. In addition to such inspection and polishing operations for removing defects, a process of removing a residual film adhered to the back surface of the wafer in a film forming process for a TFT or the like is required.

Accordingly, an object of the present invention is to provide a transparent substrate constituting a liquid crystal display device with scratches, stains, and the like generated in a wafer film forming process.
An object of the present invention is to provide a method of manufacturing a liquid crystal display device capable of removing a residual film or the like by an automatic operation.

[0005]

According to the present invention, in order to achieve the above object, a pair of transparent substrates are joined via a spacer and a sealing material, a liquid crystal is sealed between the transparent substrates, and one of the transparent substrates is formed. In a method of manufacturing a liquid crystal display device that controls the liquid crystal by a pixel driving element provided on a side surface, after forming the transparent substrate on a wafer, the surface of the wafer corresponding to the inner side surface of the transparent substrate is protected and planarized. A step of applying a protective tape on the resist film while applying a resist film for the resist film, and pouring the wafer into a chemical mechanical polishing apparatus, thereby polishing and cleaning the back surface of the wafer. The method is characterized by comprising a step of performing automatically and a step of removing the resist film and the protective tape from the wafer taken out of the chemical mechanical polishing apparatus.

In the method of manufacturing a liquid crystal display device of the present invention, first, a resist film for protection and flattening is applied to a wafer on which a transparent substrate is formed, on a surface of the wafer corresponding to an inner surface of the transparent substrate. By sticking a protective tape on the resist film, each element formed on the surface of the wafer is protected. Next, the polishing operation and the cleaning operation of the back surface of the wafer are automatically performed by feeding the wafer into the chemical mechanical polishing apparatus. In the chemical mechanical polishing apparatus, for example, the following operations are automatically performed without manual operation. First, a wafer is selectively taken out from a wafer cassette and set on a polishing table, and the back surface of the wafer is polished by a pad while supplying a polishing liquid. Then, the polished wafer is taken out from the polishing table, washed, dried, and then
Return to wafer cassette.

Next, the resist film and the protective tape are removed from the wafer taken out of the chemical mechanical polishing apparatus.
The protective tape is removed from the wafer by a peeling operation, and the resist film is removed by a cleaning operation. The peeling operation of the protective tape can be easily performed manually, or an automatic peeling device can be used. Further, the cleaning operation of the resist film can be performed by a developing device used in a normal photoresist process. Thereafter, after the wafer is dried, the process proceeds to a process of dividing each transparent substrate.

As described above, scratches, stains, residual films, and the like generated in the step of forming a wafer on a transparent substrate constituting a liquid crystal display device can be automatically removed, thereby reducing the number of manual operations. In addition, the working efficiency can be improved, and the product yield can be improved. Therefore, it is possible to reduce the cost and improve the quality of the liquid crystal display device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for manufacturing a liquid crystal display device according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an outline of a chemical mechanical polishing apparatus (CMP apparatus) used in a method of manufacturing a liquid crystal display device according to an embodiment of the present invention, and FIG.
FIG. 3 is a partial cross-sectional view illustrating an outline of a polishing process unit of the apparatus. FIG. 3 is a cross-sectional view showing a state in which a resist film and a protective tape are provided on a wafer used in the embodiment of the present invention.

In FIG. 3, a wafer 10 has a plurality of T
It constitutes an FT substrate, and has a pattern surface on which a TFT, an electrode film, and an alignment film are formed by a lithography process, an etching process, or the like. Further, the TF as described above is provided on the back surface of the wafer 10.
In the process of forming T or the like, there are scratches, stains, residual films, and the like. In the present embodiment, these are removed in a polishing process by a CMP process. Also, as described above, the wafer 10
When polishing the back surface of the wafer by the CMP process, the wafer 1
It is necessary to protect the TFT and the like provided on the 0 surface. That is, the CMP process of this example is different from a normal CMP process in that the back surface of the wafer is polished, so that the transfer surface used during transfer and the holding surface held by the polishing head during the polishing operation are: Since the wafer surface is formed with a film forming pattern such as a TFT, it is necessary to provide sufficient protection against pressure and impact so that the film forming pattern on the wafer surface is not damaged. Therefore, in this example, prior to the step of polishing the back surface of the wafer 10 by using a CMP apparatus, the resist film 12 is provided on the front surface of the wafer 10 and the protection tape 14 is attached.

The resist film 12 is obtained by applying a resist material used in a normal photoresist process to the surface of the wafer 10 by a spin coating process or the like and drying it. The resist film 12 is provided with a sufficient film thickness in order to flatten irregularities due to TFTs and the like on the surface of the wafer 10 and to surely protect the highest portion. In this example, as will be described later, a non-exposed and soluble resist material is used in order to remove the entire resist film 12 without exposing after completion of the CMP process. The protective tape 14 is affixed to the upper surface of the resist film 12 to absorb shocks, has sufficient elasticity, and uses a material that does not change its characteristics due to heat generated during polishing. And For example, in a general Si wafer processing step, a protective tape used in a back grinding step for removing an unnecessary thickness of the Si substrate can be used.

Next, based on FIG. 1, the CM used in this embodiment will be described.
The P device will be described. This CMP apparatus has a loader /
It has an unloader mechanism 22, a setting mechanism 24, a polishing mechanism 26, transport mechanisms 28 and 30, and a cleaning mechanism 32. The loader / unloader mechanism 22 selectively removes the wafer 10 from the wafer cassette 20 and conversely stores the processed wafer 10 in the wafer cassette 20. The setting mechanism unit 24 is a robot hand or the like that transports and sets the wafer 10 taken out by the loader / unloader mechanism unit 22 to the polishing table. The polishing mechanism 26 polishes the back surface of the wafer 10 set on the polishing table with a pad while supplying a polishing liquid.

The transport mechanism 28 is a robot hand or the like that takes out the wafer 10 polished by the polishing mechanism 26 from the polishing table and transports the wafer 10 to the cleaning mechanism 32. The cleaning mechanism 32 is for cleaning the wafer 10 transported by the transport mechanism 28 and then drying it. In the cleaning process of the wafer 10, rough cleaning to finish cleaning are performed stepwise, and spin drying is used in the drying process.
The transport mechanism 30 is a robot hand or the like that transports the wafer 10 cleaned and dried by the cleaning mechanism 32 to the loader / unloader mechanism 22, and the wafer 10 transported to the loader / unloader mechanism 22 is the original wafer. It is returned to the cassette 20.

Next, the polishing mechanism 26 used in this embodiment will be described with reference to FIG. The polishing mechanism 26 includes:
Wafer 1 provided with resist film and protective tape described above
0, a polishing table 40 provided with a polishing pad 42, a polishing liquid supply unit (not shown) for supplying a polishing liquid on the polishing surface of the pad 42, and a waste liquid after polishing is collected. And a waste liquid collecting section (not shown). The polishing head 40 holds the front side of the wafer 10 and makes the back side thereof contact the pad 42 on the rotary table 44 at a constant pressure. Further, the polishing head 40 is provided with an annular retainer 46 arranged along the outer periphery of the wafer 10 while holding the wafer 10 and slidingly contacting the pad 42 on the back surface of the wafer 10 in a flush state. ing.
By providing such a retainer 46, excessive polishing at the edge portion of the back surface of the wafer 10 is prevented,
This is to obtain a uniform polishing state over the entire back surface of the wafer 10. Further, the rotary table 44 is driven to rotate by a drive motor (not shown) or the like to bring the pad 42 provided on the upper surface into sliding contact with the back surface of the wafer 10 to perform chemical mechanical polishing with a polishing liquid. A plurality of polishing heads 40 are provided for one turntable 44, and a plurality of wafers 10 are collectively polished.

The basic structure of the above-described CMP apparatus is, for example, a conventional CMP apparatus used for residual film processing.
This is the same as the apparatus, but in this example, the back surface of the wafer 10 is polished to a certain thickness or more to remove scratches and the like.
For example, the polishing amount is required to be ten times or more as compared with a normal CMP apparatus. For this reason, it is designed to perform strong polishing. First, as a polishing liquid, for example, a CeO ₂ slurry for glass polishing is used, and in order to increase a polishing rate, a polishing liquid having a large particle size is used. Then, in order to cope with such a polishing liquid of large-diameter particles, a polishing liquid supply section and a waste liquid collecting section of the CMP apparatus are to take measures against the sedimentation of the abrasive. Specifically, the polishing liquid supply unit and the waste liquid recovery unit are provided with a pressure feed unit such as a pump for flowing the polishing liquid or the waste liquid at a constant pressure, and the polishing liquid or the waste liquid is supplied to the flow path of the polishing liquid or the waste liquid. A stirring unit for stirring the waste liquid shall be provided.

In order to cope with a high load caused by increasing the amount of polishing, for example, the polishing mechanism 26 employs a motor having a large driving force as a driving motor for the rotary table 44. In 46,
A material having high hardness such as SiN ceramics is used. Although the pad 42 is used for normal CMP, it is not necessary to provide a dedicated dressing device because the CeO ₂ slurry as an abrasive has a dressing effect. For cleaning, normal post-CMP cleaning is sufficient, and if there is no problem of cross contamination, acid cleaning included in normal post-CMP cleaning can be omitted.

After the back surface of the wafer 10 is polished, cleaned and dried by the CMP apparatus having the above specifications, the wafer 10 returned to the wafer cassette 20 is taken out, and the resist film 12 and the protective tape 14 are removed. . The protective tape 14 is removed from the wafer 10 by a peeling operation, and the resist film 12 is removed by a cleaning operation using a thinner or the like. The peeling operation of the protective tape 14 can be easily performed manually, or an automatic peeling device can be used. The cleaning operation of the resist film 12 can be performed by a developing device used in a normal photoresist process. Thereafter, after the wafer 10 is dried, the process proceeds to a process of dividing each transparent substrate, and the TFT substrate is completed. In the above description, the example in which the TFT substrate is processed is described. However, the CF substrate can be processed in the same manner.

As described above, in the manufacturing method of the liquid crystal display device according to the present embodiment, the back surface of the wafer on which the transparent substrate is formed is polished and removed by the CMP device in the final wafer process, so that scratches, dirt, residual film and the like on the back surface of the wafer are removed. It can be effectively removed, the defect rate in the final image inspection of the liquid crystal display device can be reduced, the product yield can be improved, and the manufacturing cost can be reduced. Also, the removal of scratches, dirt and residual film on the back of the wafer can be performed at once, simplifying the manufacturing process,
The working time can be shortened, and the manufacturing cost can be reduced from this point as well.

Further, since the polishing operation and the cleaning operation are performed by a CMP apparatus that can automatically perform the polishing operation and the cleaning operation, the dry-in operation is performed.
Dry-out is possible, and automation between the preceding and subsequent steps is possible, so that the manufacturing process can be simplified and the manufacturing cost can be reduced in this regard as well.
In addition, it is possible to eliminate the manual image inspection performed at the stage when the transparent substrate is divided from the wafer, and it is possible to reduce the manufacturing cost from this point as well.

[0020]

As described above, in the method of manufacturing a liquid crystal display device according to the present invention, a transparent substrate of the liquid crystal display device is formed on a wafer, and then a resist film for protection and planarization is applied to the surface of the wafer. After applying a protective tape on the resist film, the wafer is put into a chemical mechanical polishing device, and the back and back of the wafer are automatically polished and cleaned to remove scratches and dirt. After that, the resist film and the protective tape were removed from the wafer. For this reason, in the process of forming a film on a transparent substrate, scratches and stains generated on the back surface of the wafer can be automatically removed, thereby reducing manual work, improving work efficiency, and improving product yield. This has the effect of reducing the cost and improving the quality of the liquid crystal display device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a chemical mechanical polishing apparatus (CMP apparatus) used in a method of manufacturing a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view schematically showing a polishing process part of the CMP apparatus shown in FIG.

FIG. 3 is a cross-sectional view showing a state in which a resist film and a protective tape are provided on a wafer used in the embodiment of the present invention.

[Explanation of symbols]

Reference numeral 10: wafer, 12: resist film, 14: protective tape, 20: wafer cassette, 22: loader /
Unloader mechanism 24, setting mechanism 26, polishing mechanism 28, 30 transport mechanism 32 cleaning mechanism 40 polishing head 42 pad 44
Rotary table, 46 ... Retainer.

Claims (7)

[Claims] 1. A pair of transparent substrates are bonded via a spacer and a sealing material, a liquid crystal is sealed between the transparent substrates, and the liquid crystal is controlled by a pixel driving element provided on an inner surface of one of the transparent substrates. In the method for manufacturing a liquid crystal display device, after the transparent substrate is formed on a wafer, a resist film for protection and planarization is applied to the surface of the wafer corresponding to the inner surface of the transparent substrate, and the resist film is A step of attaching a protective tape to, and a step of automatically performing a polishing operation and a cleaning operation on the back surface of the wafer by putting the wafer into a chemical mechanical polishing apparatus, and removing the wafer from the chemical mechanical polishing apparatus. Removing the resist film and the protective tape from the obtained wafer. A method for manufacturing a liquid crystal display device, comprising: 2. A chemical mechanical polishing apparatus comprising: a loader mechanism for selectively taking out a wafer from a wafer cassette; a setting mechanism for setting a wafer taken out by the loader mechanism on a polishing table; A polishing mechanism for performing polishing by a pad while supplying a polishing liquid to the back surface of the wafer, a take-out / transport mechanism for taking out the wafer polished by the polishing mechanism from a polishing table, and cleaning the wafer carried by the take-out / transport mechanism The method for manufacturing a liquid crystal display device according to claim 1, further comprising: a cleaning mechanism for drying the wafer, and an unloader mechanism for returning the wafer cleaned and dried by the cleaning mechanism to the wafer cassette. 3. The polishing liquid according to claim 1, wherein the polishing liquid is CeO ₂ for polishing glass.
3. The method according to claim 2, wherein a slurry is used. 4. An abrasive material having a large particle diameter is used as the polishing liquid, and a polishing liquid supply system and a waste liquid recovery system after polishing are provided.
3. The apparatus according to claim 2, further comprising a pressure feeding unit and a stirring unit for preventing sedimentation of the abrasive.
The manufacturing method of the liquid crystal display device according to the above. 5. The polishing mechanism according to claim 1, wherein when the wafer is set on a polishing table, the polishing mechanism has a retainer arranged along the outer periphery of the wafer and slidably in contact with the pad on the back surface of the wafer. 3. The method for manufacturing a liquid crystal display device according to claim 2, wherein: 6. The method according to claim 1, wherein a non-exposed and soluble resist material is used for the resist film. 7. The method according to claim 1, wherein a heat-resistant protective tape for back grinding of a Si wafer is used as the protective tape.