JP2002082324A - Manufacturing method for optoelectronic device, oriented film forming device, optoelectronic device, and projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optoelectronic device manufacturing method by which the film thickness of an oriented film in a substrate is made fixed and the generation of dispersion in the film thickness of an oriented film even between substrates is prevented, an oriented film forming device and an optoelectronic device to be used for carrying out the manufacturing method and a projection type display device using the optoelectronic device. SOLUTION: In the case of forming oriented films 24, 32 on a TFT array substrate 10 and a counterposed substrate 20, the oriented film forming device 700 forms an oriented film on a testing substrate by a spin coater 300, and then measures the film thickness of the oriented film by a film thickness measuring device 50. The measurement result is fed back to the spin coater 300 by a microcomputer 600.

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 an electro-optical device such as a liquid crystal device, an apparatus for forming an alignment film, an electro-optical device, and an electro-optical device using the electro-optical device as light modulating means. The present invention relates to a projection display device. More specifically, the present invention relates to a technique for forming an alignment film for aligning an electro-optical material between substrates in an electro-optical device.

[0002]

2. Description of the Related Art Among electro-optical devices, for example, in an active matrix type electro-optical device (liquid crystal device) using TFTs as pixel switching elements, as shown in FIG. 13, a TFT array substrate 10 (first substrate) is used. ) And the opposing substrate 20 (second substrate) between the electro-optical material 5 such as a liquid crystal.
0 is sandwiched between the alignment films 2 formed on the surface of each substrate.
The orientations of the electro-optical material 50 are controlled by 4 and 32. In manufacturing such an electro-optical device 100, first, the TFT array substrate 10 and the opposing substrate 20
After forming the alignment films 24 and 32 on each of them (alignment film forming step), a rubbing process is performed on the alignment films 24 and 32. Next, after bonding the TFT array substrate 10 and the opposing substrate 20 with a predetermined gap with the sealing material 52 (adhering step), the sealing material 52 of the gap between the TFT array substrate 10 and the opposing substrate 20 is bonded. Is filled with the electro-optical material 50 in the area defined by the above (filling step).

The electro-optical device 1 manufactured as described above
In FIG. 00, the region where the alignment films 24 and 32 are required is only in the region partitioned by the sealing material 52,
By the flexographic printing, the alignment film 2 is formed only in a necessary region on the substrate, for example, only in a region defined by the sealing material 52.
4 and 32 are applied. According to the flexographic printing, the alignment films 24 and 3 are selectively formed only in predetermined regions.
2 can be applied.

[0004]

However, in the conventional electro-optical device 100, since the alignment films 24 and 32 are applied by flexographic printing, it is necessary to apply the alignment films 24 and 32 with a uniform film thickness. There is a problem that it is difficult.
With such non-uniformity of the film thickness, the electro-optical material 50
Are not uniform and display quality is degraded. In particular,
When this type of electro-optical device 100 is used as a light modulation unit of a projection display device, such non-uniformity of orientation is directly enlarged and projected as display unevenness or spots.
Such a problem becomes more apparent as the brightness of the display increases in the projection display device.

Therefore, a method of applying the orientation films 24 and 32 by spin coating instead of flexographic printing is conceivable. In this spin coating method, a polyimide resin for forming the alignment films 24 and 32 or a chemical solution (alignment agent) obtained by dissolving a polyimide precursor in a solvent such as gamma-butyrolactone or butyl cellosolve is dropped on the center of the rotating substrate and centrifuged. It spreads over the entire surface of the substrate by force. Therefore, according to the spin coating method, the alignment films 24 and 32 can be uniformly applied in the in-plane direction of the substrate.

However, the spin coating method is a method in which a chemical solution is spread on the entire surface of a substrate by centrifugal force, so that the film thickness within the substrate is constant. Since the humidity easily affects the film thickness, there is a problem that the thickness of the alignment films 24 and 32 varies for each substrate. Such alignment films 24, 3
The difference in film thickness of 2 is not preferable because the display quality varies for each electro-optical device.

[0007] In view of the above problems, an object of the present invention is to provide:
A method of manufacturing an electro-optical device in which the thickness of an alignment film is constant within a substrate, and the thickness of the alignment film does not vary between the substrates, an alignment film forming apparatus used for performing the manufacturing method, an electro-optical device, And a projection display device using the electro-optical device.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a bonding step of bonding a first substrate and a second substrate with a sealing material through a predetermined gap,
In the method for manufacturing an electro-optical device having a filling step of filling an electro-optical material into a region defined by the sealing material in a gap between the first substrate and the second substrate, the bonding step is performed. Previously, an alignment film forming step of forming an alignment film on at least one of the first and second substrates by a spin coating method is performed. In the alignment film forming step, the alignment film formed on the substrate surface is formed. Is characterized in that the film thickness of the alignment film is measured, and based on the measurement result, the conditions for applying the alignment film to the substrate thereafter are controlled.

In the present invention, since the alignment film is formed on the substrate by the spin coating method, the alignment film can be formed with a uniform film thickness, so that the electro-optical material such as liquid crystal can be properly aligned. it can. Accordingly, high-quality display without unevenness or spots can be performed. In the spin coating method, a chemical solution (alignment agent) is spread over the entire surface of the substrate by centrifugal force, so that the film thickness within the substrate is constant. Sensitive to temperature and humidity. In the present invention, before the alignment film is continuously formed on the substrate by the spin coating method, the thickness of the alignment film formed on the substrate is measured, and the measurement result is fed back. Therefore, after that, the alignment film is formed on the substrate with the target thickness. Therefore, it is possible to prevent the display quality from varying for each electro-optical device.

In the present invention, the application condition controlled based on the measurement result of the film thickness is, for example, the rotation speed of the substrate in the spin coating method.

In the present invention, the measurement of the film thickness is performed on the alignment film formed on the test substrate.

In the present invention, the measurement of the film thickness may be performed on an alignment film formed in a film thickness measurement region on the substrate.

Here, the substrate on which the alignment film is formed is:
T on which a thin film transistor for pixel switching is formed
In the case of an FT array substrate, the same thin film as any one of the electrode layers constituting the thin film transistor is formed in a film thickness measurement region on the TFT array substrate. It is preferable to measure the thickness of the alignment film formed on the thin film.

In the present invention, when the substrate on which the alignment film is formed is a TFT array substrate on which a thin film transistor for pixel switching is formed, the TFT array substrate is provided at least until the alignment film forming step. T
A configuration may be adopted in which the FT array substrate is formed on a large substrate capable of taking a large number of FT array substrates, and the film thickness measurement region is formed on the large substrate. In this case, the same thin film as any one of the electrode layers constituting the thin film transistor is formed in the thickness measurement region of the large substrate, and in the alignment film forming step, the alignment film formed on the thin film is formed. Is preferably measured.

In the present invention, the measurement of the film thickness is preferably performed by a non-contact optical system. According to such a method, since the alignment film can be measured in a non-contact manner,
The thickness of the alignment film can be measured efficiently without soiling the substrate.

An alignment film forming apparatus used for carrying out such an electro-optical device manufacturing method includes a spin coating apparatus for applying a chemical solution for forming an alignment film to a substrate surface under predetermined conditions, and a spin coating apparatus for forming an alignment film on the substrate surface. A film thickness measuring device for measuring the film thickness of the oriented film, and a film thickness measurement result of the film orientation by the film thickness measuring device and a chemical solution application condition in the spin coater when the film is formed. Thereafter, there is provided control means for deriving optimum conditions for applying a chemical solution with the spin coater.

The apparatus for forming an alignment film according to the present invention comprises a holding table for rotatably mounting a substrate, a nozzle for dropping an alignment film on a surface of the substrate mounted on the holding table, and a rotation of the holding table. A driving unit, a film thickness detecting unit for detecting a film thickness of an alignment film formed on the substrate surface, and the holding table by the driving unit based on a detection value and a reference value detected by the film thickness detecting unit. And a control unit for controlling the number of rotations.

It is preferable that the control section calculates the number of rotations of the holding table every predetermined number of times of applying the alignment film.

Preferably, the apparatus for forming an alignment film further includes a firing furnace, and the film thickness detecting section detects the alignment film of the substrate fired in the firing furnace.

In the electro-optical device manufactured by such a method, since the alignment film is uniformly applied, the electro-optical material such as a liquid crystal is properly oriented. Therefore, high quality display can be performed as compared with the alignment film applied by flexographic printing. Therefore, the electro-optical device to which the present invention is applied includes, for example, a light source, a light guiding optical system that guides light emitted from the light source to the light modulation unit, and enlarges and projects the light modulated by the light modulation unit. In a projection display device having an enlarged projection optical system, it is suitable to be used as the light modulation means.

Further, in the electro-optical device to which the present invention is applied, a light source, color light separating means for separating the light emitted from the light source into a plurality of color lights, and each of the color lights separated by the color light separating means are separated from each other. A color projection display device comprising: a light modulating means for modulating; a color light combining means for combining the color lights modulated by the light modulating means; and an expansion projection optical system for expanding and projecting the light combined by the color light combining means. Is suitable for use as the light modulation means. In such a color projection display device, a plurality of electro-optical devices are used for each color. However, in the electro-optical device to which the present invention is applied, since the thickness of the alignment film does not vary between the substrates, Display characteristics do not vary between devices.
Therefore, a color projection display device with high display quality can be configured.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 (Overall Configuration of Electro-Optical Device) First, the overall configuration of an electro-optical device (liquid crystal device) to which the present invention is applied will be described with reference to FIG. 1 and FIG. Here, an electro-optical device of a TFT active matrix driving system with a built-in driving circuit is taken as an example.

FIG. 1 is a plan view of a TFT array substrate (TFT array substrate) of an electro-optical device to which the present invention is applied, together with components formed thereon, as viewed from a counter substrate side. FIG. 2 is a sectional view taken along the line HH 'in FIG. FIG. 3 shows an end portion (H in FIG. 1) of the electro-optical device to which the invention is applied.
FIG. 6 is an enlarged cross-sectional view schematically showing an end on the H ′ side of −H ′). In FIG. 3, the scale of each layer and each member is different so that each layer and each member have a size recognizable in the drawing. Also, in FIG. 3, the arrangement of the microlenses and the TFTs is different from the actual arrangement to facilitate understanding of the state of light collection.

As shown in FIGS. 1, 2 and 3, in the electro-optical device 100 of the present embodiment, the TFT array substrate 1
0 (first substrate) and the opposing substrate 20 (second substrate)
The pixel electrode 9a and the counter electrode 2 formed on each substrate
1 are arranged to face each other. Here, the pixel electrodes 9 a are formed in a matrix on the TFT array substrate 10, while the counter electrode 21 is formed on the entire surface of the counter substrate 20.

A large number of microlenses 55 are formed on the lower surface of the opposing substrate 20 (adhesion surface with the cover glass), and the opposing substrate 20 is configured as a microlens array plate. An adhesive 210 is provided on the lower surface of the counter substrate 20 on which the microlenses 55 are formed in this manner.
Thereby, the cover glass 200 as the first substrate is adhered. The adhesive 210 is made of an acrylic photocurable adhesive having a refractive index smaller than that of the microlens 55, and the microlens 55 functions as a condenser lens due to a difference in refractive index between the two. Here, each of the microlenses 55 is formed in a matrix so as to converge incident light on each of the pixel electrodes 9a formed on the TFT array substrate 10, and the cover glass 200 has a plurality of microlenses. The light shielding films 23 are formed at positions facing the respective boundaries of the lenses 55. The pixel electrode 9a and the counter electrode 21 are formed of an ITO film (indium tin oxide film).

The sealing material 52 is made of the TFT array substrate 10
And a counter substrate 20 to which a cover glass 200 is entirely adhered to form a panel 5. The panel 5 is made of, for example, an ultraviolet curable resin or a thermosetting resin.
After being coated on the TFT array substrate 10 and the opposing substrate 2
In the state where 0 is superimposed, the composition is cured by ultraviolet irradiation, heating, or the like. If the electro-optical device 100 is of a small size and performs an enlarged display, such as for a projection display device, a glass for setting the distance between the two substrates (gap between the substrates) to a predetermined value is provided in the sealing material 52. A gap material (spacer) such as fiber or glass beads is blended. In addition, if the electro-optical device 100 is a device that is large and displays images at the same magnification as a liquid crystal display or a liquid crystal television, such a gap material may be scattered in the liquid crystal layer 50 in some cases.

In the electro-optical device 100 of the present embodiment, a parting light-shielding film 53 for defining the image display area 10a is formed on the side of the counter substrate 20 along the area inside the formation area of the sealing material 52. Have been. In the sealing material 52,
A liquid crystal injection port 108 is formed by the interruption,
After the injection of the liquid crystal is completed, a sealing material 109 made of the same or different material as the sealing material 52 is used.
It is closed by.

In a peripheral region outside the region where the sealing material 52 is formed, a data line driving circuit 101 and an external circuit connection terminal 102 are formed along one side of the TFT array substrate 10, and the scanning line driving circuit 104 It is provided along two sides adjacent to this one side. Further, a plurality of wirings 105 for connecting between the scanning line driving circuits 104 provided on both sides of the image display area 10a are formed on the remaining one side of the TFT array substrate 10.

In the electro-optical device 100, the upper and lower conductive electrodes 19 are formed on the TFT array substrate 10 at four positions corresponding to the corners of the opposing substrate 20, and
Between the TFT array substrate 10 and the opposing substrate 20, there is a vertical conductive material 106 for establishing electrical continuity between these substrates.
Is provided. Here, the upper and lower conductive material 106 is a material in which conductive particles such as silver powder and gold-plated fiber are mixed with an epoxy resin-based or acrylic resin-based adhesive component.

In FIG. 3, a film is formed by a spin coating method on the surface of the pixel electrode 9a after the pixel switching TFT 30 and the wiring such as the scanning line, the data line and the capacitance line are formed on the TFT array substrate 10. An alignment film 32 made of a polyimide-based material is formed.

On the side of the counter substrate 20, on the cover glass 200, in addition to the counter electrode 21, a light-shielding film 23 generally called a black mask or a black matrix for defining a non-opening area for each pixel is formed. On these surfaces, an alignment film 24 made of a polyimide-based material formed by a spin coating method is formed.

Each of the alignment films 32 and 24 is coated with a polyimide resin material and then baked. Thereafter, the liquid crystal in the liquid crystal layer 50 is aligned in a predetermined direction, and the liquid crystal has a predetermined pretilt angle. An orientation treatment is performed so as to provide. The liquid crystal layer 50 is made of, for example, a liquid crystal in which one or several kinds of nematic liquid crystals are mixed, and has a predetermined alignment state between the alignment films 32 and 24. Light shielding film 23
Has a function of improving the contrast in the displayed image.

The TFT array substrate 10 also has a stripe-shaped light-shielding film 11a along scanning lines and capacitance lines, which will be described later.
Are formed. The light-shielding film 11a covers a region including a TFT channel region from the TFT array substrate 10 side. If the light-shielding film 11a is formed below the TFT 30 in this manner, one optical system can be formed by reflecting the back surface (return light) from the TFT array substrate 10 side or combining a plurality of electro-optical devices 100 via a prism or the like. In the case of configuring, the light or the like penetrating from another electro-optical device 100 through a prism or the like is used as the TFT 3 of the electro-optical device 100.
It can be prevented from being incident on zero.

In the electro-optical device 100 of this embodiment, a color filter is not formed because the color light separated into each color is incident on the projection display device described later.
A color filter may be formed on the surface of the cover glass 200. In this case, the light shielding film 23 also has a function of preventing color mixture of the color materials forming the color filter.

(Area for Forming Alignment Films 24 and 32) In the electro-optical device 100 thus configured, the alignment films 24 and 32
Numeral 32 is applied to each of the opposing substrate 20 and the TFT array substrate 10 by a spin coating method, as described later. According to such a spin coating method, the alignment films 24 and 32 can be applied to a uniform thickness in the in-plane directions of the counter substrate 20 and the TFT array substrate 10 as compared with the flexographic printing method. In the method, the liquid crystal alignment failure due to the thickness variation of the alignment films 24 and 32 does not occur. Therefore, even when the electro-optical device 100 of the present embodiment is used as a light modulation unit of a projection display device described later, high-quality display without unevenness or spots can be performed.

(Configuration of Image Display Area of Electro-Optical Device) A pixel portion of the electro-optical device 100 according to the present embodiment will be described with reference to FIG. FIG. 4 is an equivalent circuit of various elements, wirings, and the like in a plurality of pixels formed in a matrix and constituting the image display area 10a of the electro-optical device 100.

As shown in FIG. 4, in the electro-optical device 100 of the present embodiment, a plurality of pixels formed in a matrix forming an image display area 10a are formed by a TFT 30 for controlling a pixel electrode 9a. And a data line 6a to which a pixel signal is supplied is connected to a TFT.
It is electrically connected to 30 sources. Data line 6a
, Sn to be written may be supplied line-sequentially in this order, or may be supplied to a plurality of adjacent data lines 6a for each group. The scanning line 3a is electrically connected to the gate of the TFT 30, and the scanning line 3a is provided at a predetermined timing.
The scanning signals G1, G2,..., Gm are applied to a in a pulse-wise manner in this order. The pixel electrode 9a is electrically connected to the drain of the TFT 30, and by opening the switch of the TFT 30 as a switching element for a certain period, the image signals S1, S2,... Write at a predetermined timing. The image signals S1, S2,..., Sn of a predetermined level written in the liquid crystal via the pixel signals 9a are held for a certain period between the counter electrodes formed on the counter substrate. The liquid crystal modulates light by changing the orientation and order of the molecular assembly according to the applied voltage level, thereby enabling gray scale display. In the case of the normally white mode, the transmitted light quantity of the incident light of the liquid crystal portion decreases according to the applied voltage, and in the case of the normally black mode, the incident light of the liquid crystal portion depends on the applied voltage. The amount of transmitted light increases, and light having a contrast corresponding to the image signal is emitted from the electro-optical device 100 as a whole. Here, in order to prevent the held image signal from leaking, a storage capacitor 70 is added in parallel with a liquid crystal capacitor formed between the pixel electrode 9a and the counter electrode.

(Method of Manufacturing Electro-Optical Device 100)
Characteristic steps of the method for manufacturing the electro-optical device 100 according to the embodiment will be described.

FIG. 5 shows an alignment film forming step for forming alignment films 24 and 32 on the TFT array substrate 10 and the counter substrate 20 in the manufacturing process of the electro-optical device 100 shown in FIG. FIG. 3 is an explanatory view of an alignment film forming apparatus used in the above. FIG. 6 shows a relationship between the substrate rotation speed and the thickness of the alignment film when the alignment film is formed by using the spin coating method in the alignment film forming step shown in FIG. 5, and a method for obtaining an optimum rotation speed from this relationship. FIG.

In this embodiment, when forming the alignment films 24 and 32 on the TFT array substrate 10 and the opposing substrate 20, an alignment film forming apparatus 700 shown in FIG. 5 is used. The alignment film forming apparatus 700 generally includes a spin coater 300, a baking apparatus 400, a film thickness measuring apparatus 500, and a microcomputer 600 (control means).

The spin coater 300 includes a suction chuck 303 (substrate holding table) connected to an output shaft 302 of a motor 301 as a driving unit, and a substrate (TFT array substrate) that rotates while being held by the suction chuck 303. 10 and the counter substrate 20), a chemical supply pipe 304 for hanging a chemical for forming an alignment film, and a nitrogen gas for jetting nitrogen gas for removing a solvent from the chemical layer applied to the substrate surface toward the substrate surface. And a gas ejection nozzle 305.

In the present embodiment, a baking furnace 400 for baking the alignment films 24 and 32 applied to the substrate surface by spin coating in a nitrogen gas atmosphere is used. The substrates can be delivered by the delivery arms 350 and 450.

A film thickness measuring device 50 for forming the film thickness of the alignment films 24 and 32 applied by the spin coating method.
0, the film thickness measuring device 500 and the firing furnace 400
Means that the substrate can be delivered by the delivery arm 550. In the example described here, an optical system such as an ellipsometer that can measure the film thickness in a non-contact state is used as the film thickness measuring device 500.

Further, in the present embodiment, the rotation speed (number of rotations) of the motor 301 of the spin coater 300 is controlled by the microcomputer 600, and the rotation speed of the motor 301 and the film thickness of the film thickness measuring device 500 are measured. The measurement result is input to the microcomputer 600. The microcomputer 600 operates based on a program stored in advance in a ROM or the like, and adjusts the rotation speed of the motor 301 of the spin coater 300 to the orientation film 2.
The conditions are controlled so that the thicknesses of the layers 4 and 32 are always constant. That is, in the microcomputer 600,
The memory has a spin coater 30 as shown in FIG.
Data indicating a model relationship between the substrate rotation speed at 0 and the film thickness of the alignment films 24 and 32 is stored.

When the spin coater 400 rotates the substrate at a predetermined speed to form the alignment films 24 and 32, the microcomputer 600 controls the thickness of the alignment films 24 and 32 and the thickness of the film thickness measuring device 500. When the relationship with the measurement result deviates from the model-like relationship, a curve (indicated by a dotted line L2 in FIG. 6) obtained by translating the curve indicating the model-like relationship (shown by a solid line L1 in FIG. 6) as it is Then, an appropriate motor rotation speed (optimal coating condition) capable of realizing the target film thickness of the alignment films 24 and 32 is derived, and the spin coater 3 rotates the substrate at this rotation speed.
00 is controlled. Therefore, based on the model-like relationship, when the rotation speed of the substrate is set to 2000 and the target is set to 60 nm, but it is actually 65 nm,
The microcomputer 600 derives 2200 rotations as an appropriate rotation speed for achieving 60 nm from a curve (dotted line L2) obtained by translating the curve (solid line L1) indicating the model-like relationship as it is, and using this rotation speed. The spin coater 300 is controlled so as to rotate the substrate. That is, the correlation data between the reference film thickness and the rotation speed is compared with the detected value of the film thickness, and an appropriate rotation speed is calculated based on the comparison result.

The alignment film forming apparatus 700 thus configured
In this embodiment, before forming an alignment film on the surface of a substrate actually used for assembling a product, first, a test substrate is set on a spin coater 300 to form an alignment film on the surface of the test substrate. Apply chemical solution. At this time, based on the model relationship (solid line L1) shown in FIG.
The rotation is set, and after the substrate is stabilized at this number of rotations, a chemical for forming an alignment film is dripped from the chemical supply pipe 304 onto the surface of the test substrate. As a result, on the surface of the test substrate, the chemical solution is developed to a uniform thickness by the centrifugal force.

After the chemical solution for forming the alignment film is applied to the substrate surface in this manner, the nitrogen gas jet nozzle 305
A solvent is removed from the alignment film by blowing nitrogen gas toward the substrate surface.

Next, the test substrate is placed in a firing furnace 400, and the alignment film formed on the surface of the test substrate is fired in a nitrogen gas atmosphere.

Next, the test substrate is transferred from the firing furnace 400 to the film thickness measuring device 500, and the thickness of the alignment film formed on the surface of the test substrate is measured. This measurement result is output from the film thickness measuring device 500 to the microcomputer 600.

As a result, in the microcomputer 600, the measurement result of the number of rotations (2000 rotations) of the substrate and the film thickness when the alignment film is formed on the test substrate is a curve L1 showing a model relationship shown in FIG. (Reference data).

In this confirmation result, if it is determined that the number of rotations of the substrate at the time of forming the alignment film on the test substrate is 2000 and the film thickness is 60 nm, the microcomputer thereafter actually executes the operation. The number of rotations of the substrate when forming an alignment film on the TFT array substrate and the counter substrate used for product assembly is set to 2,000. Therefore, thereafter, the surface of the TFT array substrate 10 and the counter substrate 20 actually used for product assembly is
nm of the alignment films 24 and 32 can be formed.

On the other hand, when the film thickness is 65 nm, the microcomputer 600 has a model-like structure in spite of the fact that the number of rotations of the substrate when forming the alignment film on the test substrate is 2,000. Curve L1 showing the relationship
2200 rotations are derived from the curve L2 obtained by translating as is as the rotation speed for achieving 60 nm. That is, the reference data indicating the correlation between the film thickness and the rotation speed is compared with the detected value of the film thickness, and an appropriate rotation speed is calculated based on the comparison result. Thereafter, the spin coater 300 is controlled so that the number of rotations of the substrate when forming an alignment film on the TFT array substrate and the counter substrate actually used for product assembly is set to 2200 rotations. Therefore,
Thereafter, the surface of the TFT array substrate 10 and the counter substrate 20 actually used for product assembly is
The alignment films 24 and 32 having a thickness of 0 nm can be formed. After the completion of the alignment film forming step, the alignment films 24 and 32 of the counter substrate 20 and the TFT array substrate 10 are rubbed with a rubbing cloth in a predetermined direction.

It is desirable that the film thickness measurement be performed at the time of starting the apparatus or after forming a predetermined number of alignment films.

Next, as shown in FIGS. 1, 2 and 3, a sealing material 52 and an upper / lower conductive material 106 (not shown) are applied to the surface of the TFT array substrate 10. TFT array substrate 10 and counter substrate 2
Attach to 0. Then, the sealing material 52 and the upper / lower conductive material 106 are cured (bonding step).

Next, the TFT array substrate 10 and the opposing substrate 2
Of the sealing material 52 from the liquid crystal injection port 108.
The liquid crystal or other electro-optical material is injected under reduced pressure into the area defined by
09 (filling step).

As described above, in the present embodiment, the alignment films 24 and 32 are formed on the TFT array substrate 10 and the counter substrate 20 by the spin coating method.
Since 32 can be formed with a uniform film thickness, an electro-optical material such as a liquid crystal can be properly oriented. Accordingly, high-quality display without unevenness or spots can be performed.

In the spin coating method, a chemical solution (alignment agent) is spread on the entire surface of the substrate by centrifugal force. Therefore, the film thickness in the substrate is constant. Sensitive to working environment temperature and humidity. In this embodiment, the electro-optical device 100
The alignment films 24, 3 are applied to the TFT array substrate 10 and the counter substrate 20 which are actually used for assembling by spin coating.
Before forming 2, an alignment film is formed on the test substrate, and the result is fed back. Therefore, thereafter, the TFT array substrate 1 on which the alignment films 24 and 32 are formed
In the substrate 0 and the counter substrate 20, the alignment films 24 and 32 are formed with a film thickness as a predetermined target value. Therefore, it is possible to prevent the display quality from varying for each electro-optical device 100.

[Second Embodiment] In the first embodiment, the alignment film is formed on the test substrate before the actual mass production. For example, as shown in FIG. The film thickness measurement area 190 is provided on the surface of the TFT array substrate
May be set, the film thickness of the alignment film 24 is measured in the film thickness measurement region 190 of the first TFT array substrate 10 to be mass-produced, and the measurement result is fed back to the spin coater 300.

In this case, when the optical system is used as the film thickness measuring device 500, the lower layer of the alignment film is a silicon oxide film, an ITO film, or aluminum, so that a silicide film or the like on which a natural oxide film or the like is hardly formed on the surface is formed. A tantalum film is preferred. Therefore, in the present embodiment, as described below, a thin film of any one of a plurality of electrode layers used for the pixel switching TFT 30 of the TFT array substrate 10 is formed in the film thickness measurement region 190. In addition, the thickness of the alignment film formed on the thin film is measured.

Hereinafter, the structure of the TFT 30 formed on the TFT array substrate 10 will be described, and the structure of the film thickness measuring region 190 will be described while explaining the manufacturing method.

FIG. 7 shows the TFT array substrate 10 shown in FIG.
FIG. 3 is an enlarged cross-sectional view showing the configuration of the TFT 30 formed in FIG.

As shown in FIG. 7, the TFT array substrate 10
Is made of a transparent substrate 10b such as a quartz substrate or a heat-resistant glass plate. A pixel electrode 9a is formed on the TFT array substrate 10, and an alignment film 32 on which a predetermined alignment process such as a rubbing process is performed is formed above the pixel electrode 9a.

In the TFT array substrate 10, each pixel electrode 9
A pixel switching TFT 30 for controlling switching of each pixel electrode 9a is formed at a position adjacent to a. The TFT 30 shown here is an LDD (Lightly Doped
Drain) structure, a scanning line 3a (gate electrode), a channel forming region 1a 'of the semiconductor film 1a in which a channel is formed by an electric field of a scanning signal supplied from the scanning line 3a, the scanning line 3a and the semiconductor. Gate insulating film 2 for insulating layer 1a, data line 6a (source electrode), semiconductor layer 1
a low-concentration source region (source-side LDD region) 1b and low-concentration drain region (drain-side LDD region) 1c;
And a high concentration source region 1d and a high concentration drain region 1e of the semiconductor layer 1a. A corresponding one of the plurality of pixel electrodes 9a is electrically connected to the high-concentration drain region 1e. The source region 1b, 1d and the drain region 1c, 1e form an n-type channel in the semiconductor layer 1a or
It is formed by doping a predetermined concentration of an n-type or p-type dopant depending on whether a type channel is formed. An n-type channel TFT has the advantage of a high operating speed, and is often used as a TFT for pixel switching.

In the present embodiment, the data line 6a (source electrode) is made of, for example, an alloy film of metal silicide or the like. On the scanning line 3a (gate electrode), the gate insulating film 2 and the underlying protective film 12, a contact hole 5 leading to the high-concentration source region 1d and a contact hole 8 leading to the high-concentration drain region 1e are respectively formed. One interlayer insulating film 4 is formed. Via the contact hole 5 to the source region 1d, the data line 6a
The (source electrode) is electrically connected to the high-concentration source region 1d. Further, a second interlayer insulating film 7 is formed on the data line 6a (source electrode) and the first interlayer insulating film 4. Here, the pixel electrode 9a is formed of the second interlayer insulating film 7
Therefore, a contact hole 8 is formed in the gate insulating film 2, the first interlayer insulating film 4, and the second interlayer insulating film 7 so as to communicate with the high-concentration drain region 1e.
Therefore, the pixel electrode 9a is electrically connected to the high-concentration drain region 1e through the contact hole 8 to the high-concentration drain region 1e.

In the present embodiment, the gate insulating film 2 of the TFT 30
Is extended from a position facing the gate electrode 3a to be used as a dielectric film, a semiconductor film 1a is extended to be a first electrode 1f, and a part of the capacitance line 3b opposed to these is formed as a second electrode. By doing so, the storage capacitor 70 is configured.

The TFT array substrate 10 thus configured
In the above, although the data line 6a, the scanning line 3a, and the capacitor line 3b pass through the boundary region between the adjacent pixel electrodes 9a, light passes through these lines or through the gap between these lines and the pixel electrode 9a. If leaked, the quality of the display will be degraded. Therefore, in the present embodiment, the TFT
Between the transparent substrate 10b, which is the base of the array substrate 10, and the underlying protective film 12, opaque refractory metals Ti (titanium), Cr (chromium), W ( Tungsten), Ta (tantalum), Mo
A light shielding film 11a made of (molybdenum) or the like is formed. The light-shielding film 11a is formed, in plan view, in the formation region of the TFT 30 including the channel region of the semiconductor layer 1a,
a, the scanning line 3a and the capacitor line 3b are formed at positions overlapping with each other when viewed from the back surface side of the TFT array substrate 10.

The TFT array substrate 10 thus configured
Will be described with reference to FIGS.
In addition, a process of forming the film thickness measurement region 190 of the TFT array substrate 10 will be described.

8 to 10 are sectional views showing the steps of a method for manufacturing the TFT array substrate 10 according to the present embodiment.

As shown in FIG. 8A, an opaque high melting point metal such as Ti or C is formed on the entire surface of a substrate 10b made of quartz or heat-resistant glass, which is the base of the TFT array substrate 10.
After a metal film made of a single metal such as r, W, Ta, Mo, Pd or the like or a metal film made of an alloy is formed by sputtering or the like, the metal film 11b is patterned to form the light shielding film 11a.

Next, TEOS (tetra-ethyl-tetrafluoroethylene) is formed on the light shielding film 11a by, for example, normal pressure or low pressure CVD.
Orthosilicate gas, TEB (tetra-ethyl
NSG (non-silicate glass), PSG (rinsilicate glass), and so on using a boat rate) gas, a TMOP (tetra-methyl-oxy-foslate) gas, and the like.
Base protective film 1 made of a silicate glass film such as BSG (boron silicate glass) or BPSG (boron phosphorus silicate glass), a silicon nitride film or a silicon oxide film
Form 2

As a result, the light-shielding film 11a and the underlying protective film 12 are also stacked in the thickness measuring region 190.

Next, as shown in FIG. 8B, a semiconductor film made of amorphous silicon is formed on the base protective film 12 by low-pressure CVD using a monosilane gas, a disilane gas, or the like. This is performed in an atmosphere, and then patterned to form an island-shaped semiconductor layer 1a. Further, a first electrode 1f extending from the semiconductor layer 1a is formed in a region where the capacitance line 3b is formed.

Next, the semiconductor layer 1a constituting the TFT 30
At the same time, the gate insulating film 2 is formed by thermally oxidizing the first electrode 1f.

As a result, the light-shielding film 11a, the underlying protective film 12, the semiconductor film 1a, and the gate insulating film 2 are stacked in the film thickness measuring region 190.

Next, as shown in FIG.
After depositing a polysilicon film by the D method or the like, phosphorus (P)
Is thermally diffused to make the polysilicon film conductive, and then the polysilicon film is patterned to form a scanning line 3a (gate electrode).
And a capacitance line 3b.

As a result, the light-shielding film 11a, the underlying protective film 12, the semiconductor film 1a, the gate insulating film 2, and the polysilicon film 3c are stacked in the thickness measuring region 190.

Next, using the scanning line 3a (gate electrode) as a diffusion mask, a low-concentration source region 1b and a low-concentration drain region 1c are formed by doping a V-group element dopant 200 such as P at a low concentration. As a result, the semiconductor layer 1a below the scanning line 3a (gate electrode) is
a '.

Subsequently, as shown in FIG. 8D, a resist mask 20 wider than the scanning line 3a (gate electrode) is formed.
2 is formed on the scanning line 3a (gate electrode), and then a high-concentration source region 1d and a high-concentration drain region
forming e.

Next, as shown in FIG.
0 to cover the scanning line 3a (gate electrode), the capacitance line 3b, and the scanning line 3a, for example, normal pressure or reduced pressure CV.
N method (non-silicate glass), PSG (phosphosilicate glass), BSG using D method or TEOS gas, etc.
(Boron silicate glass), a silicate glass film such as BPSG (boron phosphorus silicate glass), a first interlayer insulating film 4 made of a silicon nitride film, a silicon oxide film or the like, and then a contact hole for the data line 6a (source electrode). 5 is formed by dry etching such as reactive etching, reactive ion beam etching or the like, or wet etching. Thereafter, a metal film 6 such as a metal silicide is formed on the first interlayer insulating layer 4 by a sputtering process or the like. Form.

As a result, the light-shielding film 11a, the underlying protective film 12, the semiconductor film 1a, the gate insulating film 2, the polysilicon film 3c, the first interlayer insulating film 4, and the metal film 6 are stacked in the thickness measuring region 190. Is done.

Next, the metal film 6 is patterned, as shown in FIG.
As shown in (b), a data line 6a is formed.

Next, as shown in FIG. 9C, a normal pressure or low pressure CVD method or a T
NSG, PSG, BSG, BP using EOS gas
A second interlayer insulating film 7 made of a silicate glass film such as SG, a silicon nitride film, a silicon oxide film, or the like is formed.

As a result, the light-shielding film 11a, the underlying protective film 12, the semiconductor film 1a, the gate insulating film 2, the polysilicon film 3c, the first interlayer insulating film 4, the metal film 6, and the second An interlayer insulating film 7 is laminated.

Next, as shown in FIG.
At 0, a contact hole 8 for electrically connecting the pixel electrode 9a and the high-concentration drain region 1e is formed by dry etching such as reactive etching or reactive ion beam etching. At this time, the film thickness measurement area 1
At 90, the second interlayer insulating film 7 is etched to expose the metal film 6.

Next, as shown in FIG. 10A, an ITO film 9 is formed on the second interlayer insulating film 7 by sputtering or the like.
Is deposited.

As a result, the light-shielding film 11a, the underlying protective film 12, the semiconductor film 1a, the gate insulating film 2, the polysilicon film 3c, the first interlayer insulating film 4, the metal film 6, and the ITO film 9 are stacked.

Next, the ITO film 9 is patterned to form a pixel electrode 9a as shown in FIG. At this time, in the film thickness measurement region 190, the ITO film 9 is etched to expose the metal film 6.

Next, as shown in FIG. 10C, a liquid chemical for forming a polyimide-based alignment film is applied on the pixel electrode 9a by spin coating, and then baked to form an alignment film 32. As a result, the alignment film 32 is also provided in the film thickness measurement region 190.
Is formed.

Therefore, in the present embodiment, similarly to the first embodiment, the alignment film 32 is measured by the film thickness measuring device 500,
The measurement result is fed back to the spin coater 300 (see FIG. 5). Therefore, thereafter, the alignment film 32 having a desired film thickness can be formed on the surface of the TFT array substrate 10.

[Third Embodiment] As shown in FIG. 11, a plurality of TFT array substrates 10 are large substrates 1
After the lamination process and the like are completed, the large-sized substrate 1b 'may be cut into a single TFT array substrate 10.

In such a case, as shown in FIG. 11, the film thickness measurement region 1
90 ′ is set, and the alignment film 32 is set in the film thickness measurement region 190 ′ of the large substrate 1b ′ to be flowed first in mass production as in the second embodiment.
A configuration may be adopted in which the measurement result is fed back to the spin coater 300 by measuring the thickness of the film.

Also in this case, when the optical system is used as the film thickness measuring device 500, since the lower layer of the alignment film is a silicon oxide film, an ITO film or aluminum, it is difficult to form a natural oxide film or the like on the surface. A tantalum film is preferred. Therefore, in this embodiment, a detailed description is omitted, but as described in Embodiment 2, the pixel switching TF of the TFT array substrate 10 is used.
A thin film of any one of the plurality of electrode layers used for T30 is formed in the thickness measurement region 190 ', and the thickness of the alignment film formed on the thin film in the thickness measurement region 190' is reduced. It is preferable to measure.

[Other Embodiments] A configuration in which the thickness of an alignment film formed on a substrate which is first flowed in mass production is measured and fed back (the configuration described in the second embodiment), or a first configuration in mass production. The configuration in which the thickness of the alignment film formed on the large substrate flowing through the substrate is measured and fed back (the configuration described in Embodiment 3) may be applied to the case where the alignment film is formed on the counter substrate 20.

The film thickness measuring device 500 is not limited to the optical system, but may measure the film thickness of the alignment film based on a step formed by the alignment film.

[Structure of Projection Display Device] The structure of a projection display device using the electro-optical device 100 to which the present invention is applied will be described with reference to FIG.

In FIG. 12, a projection type display device 1100
Then, the liquid crystal display module including the transmissive electro-optical device 100 includes light valves 100R, 100G and 100 for R (red light), G (green light), and B (blue light), respectively.
B (light modulator).

In the projection display device 1100, the lamp unit 11 of a white light source such as a metal halide lamp is used.
02 (light source) emits this light through the light guide optical system described below.
R, 100G and 100B. That is, the projection light from the lamp unit 1102 is
106 and two dichroic mirrors 1108 (color separation means) separate light components R, G, and B corresponding to the three primary colors of RGB, and the light valve 1 corresponding to each color.
00R, 100G, and 100B. On this occasion,
In particular, the B light is guided through a relay lens system 1121 including an entrance lens 1122, a relay lens 1123, and an exit lens 1124 in order to prevent light loss due to a long optical path.

Then, the light valves 100R, 100G
The light components corresponding to the three primary colors modulated by the first and second components 100B, respectively, are recombined by the dichroic prism 1112 (color combining means) and then enlarged as a color image on the screen 1120 via the projection lens 1114 (enlargement projection optical system). Projected.

As described above, when the electro-optical device 100 to which the present invention is applied is used for the projection display device 1100,
In the enlarged and projected image, display unevenness and spots due to non-uniformity of the alignment films 24 and 32 formed on the electro-optical device 100 do not occur, so that high-quality display can be performed.

The projection display device 110 shown in FIG.
At 0, the present invention was applied to all three light valves 100R, 100G, and 100B for R (red), G (green), and B (blue), but the visibility was particularly low for G (green). The electro-optical device 100 to which the present invention is applied may be used only for the G (green) light valve 100G because it is high and unevenness and spots are easily noticeable.

[0102]

As described above, in the present invention, since an alignment film is formed on a substrate by spin coating,
Since the alignment film can be formed with a uniform thickness, an electro-optical material such as a liquid crystal can be properly aligned.
Accordingly, high-quality display without unevenness or spots can be performed. In the spin coating method, a chemical solution (alignment agent)
Is spread over the entire surface of the substrate by centrifugal force, so the film thickness within the substrate is constant, but it is easily affected by the lot of the used chemical solution or the temperature and humidity of the working environment. In the present invention, before the alignment film is continuously formed on the substrate by spin coating, the thickness of the alignment film formed on the substrate is measured, and the measurement result is fed back. Therefore, after that, the alignment film is formed on the substrate with the target thickness. Therefore, it is possible to prevent the display quality from varying for each electro-optical device.

[Brief description of the drawings]

FIG. 1 is a plan view of a TFT array substrate of an electro-optical device to which the present invention is applied, together with components formed thereon, viewed from a counter substrate side.

FIG. 2 is a sectional view taken along line HH ′ of FIG. 1;

FIG. 3 is a cross-sectional view schematically showing an enlarged end portion of the electro-optical device shown in FIG.

FIG. 4 is an equivalent circuit of various elements, wiring, and the like in a plurality of pixels formed in a matrix in an image display area of the electro-optical device illustrated in FIG.

FIG. 5 is an explanatory view showing an alignment film forming step and a configuration of an alignment film forming apparatus used in this step in the manufacturing steps of the electro-optical device shown in FIG.

6 is a diagram illustrating a relationship between a substrate rotation speed and a film thickness of an alignment film when an alignment film is formed using a spin coating method in a process of forming an alignment film illustrated in FIG. 5, and a method of obtaining an optimum rotation speed from the relationship. FIG.

FIG. 7 is a cross-sectional view showing a configuration of a TFT and a film thickness measurement region formed on a TFT array substrate of the electro-optical device shown in FIG.

8 (a) to 8 (d) are process sectional views for forming the TFT and the film thickness measurement region shown in FIG. 7;

9 (a) to 9 (d) are cross-sectional views showing steps performed after the step shown in FIG. 8 for forming the TFT and the film thickness measurement region shown in FIG. 7;

10 (a) to 10 (c) are cross-sectional views showing the steps performed after the step shown in FIG. 9 for forming the TFT and the film thickness measurement region shown in FIG. 7;

FIG. 11 is an explanatory diagram showing a film thickness measurement region set on a large substrate when the steps shown in FIGS. 8 to 10 are performed in the state of a large substrate.

FIG. 12 is an explanatory diagram showing a configuration of an optical system of a projection display device using an electro-optical device to which the present invention has been applied.

FIG. 13 is an enlarged cross-sectional view schematically illustrating an end of a conventional electro-optical device.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 electro-optical device 5 panel 10 TFT array substrate (first substrate) 10 a image display area 19 vertical conductive electrode 106 vertical conductive material 20 opposed substrate (second substrate) 24, 34 alignment film 50 liquid crystal layer 52 sealing material 53 parting Light shielding film 55 Microlens 100R, 100G, 100B Light valve (light modulator) 200 Cover glass 700 Alignment film forming device 300 Spin coater 400 Baking device 500 Film thickness measuring device 600 Microcomputer (control means) 1100 Projection display apparatus

Claims (15)

[Claims] 1. A bonding step of bonding a first substrate and a second substrate with a sealing material through a predetermined gap, and the sealing material in a gap between the first substrate and the second substrate. A filling step of filling an electro-optical substance in a region defined by the step (a), wherein the first and second steps are performed before performing the bonding step.
Performing an alignment film forming step of forming an alignment film on the surface of at least one of the substrates using a spin coating method, in the alignment film forming step, measuring the thickness of the alignment film formed on the substrate surface, A method for manufacturing an electro-optical device, comprising: controlling a condition for subsequently applying an alignment film to a substrate surface based on the measurement result. 2. The method for manufacturing an electro-optical device according to claim 1, wherein the application condition controlled based on the measurement result of the film thickness is a rotation speed of a substrate in a spin coating method. 3. The method of manufacturing an electro-optical device according to claim 1, wherein the measurement of the film thickness is performed on an alignment film formed on a test substrate. 4. The method of manufacturing an electro-optical device according to claim 1, wherein the measurement of the film thickness is performed on an alignment film formed in a film thickness measurement region on a substrate. 5. The substrate according to claim 4, wherein the substrate on which the alignment film is formed is a TFT array substrate on which a thin film transistor for pixel switching is formed. A thin film made of the same material as any one of the plurality of electrode layers constituting the thin film transistor is formed. In the alignment film forming step, the thickness of the alignment film formed on the thin film is measured. A method for manufacturing an electro-optical device. 6. The substrate according to claim 4, wherein the substrate on which the alignment film is formed is a TFT array substrate on which pixel switching thin film transistors are formed, and the TFT array substrate is provided at least until the alignment film forming step. A method for manufacturing an electro-optical device, comprising: forming a TFT substrate on a large substrate capable of taking a large number of TFT array substrates; and forming the film thickness measurement region on the large substrate. 7. A method according to claim 6, wherein a thin film made of the same material as any one of the plurality of electrode layers forming the thin film transistor is formed in the thickness measurement region of the large substrate. And measuring the thickness of the alignment film formed on the thin film. 8. The method according to claim 1, wherein
The method for manufacturing an electro-optical device, wherein the measurement of the film thickness is performed using a non-contact optical system. 9. An alignment film forming apparatus used in the method of manufacturing an electro-optical device according to claim 1, wherein a chemical solution for forming an alignment film is applied to a substrate surface under predetermined conditions. And a film thickness measuring device for measuring the film thickness of the alignment film formed on the surface of the substrate, and a result of measuring the film thickness of the alignment film by the film thickness measuring device and the spin coating device when the film is formed. Control means for deriving optimum conditions for applying a chemical solution with the spin coater thereafter based on the chemical solution application conditions. 10. A holding table for rotatably mounting a substrate,
A nozzle that drops an alignment film on the surface of the substrate placed on the holding table, a driving unit that rotates the holding table, and a film thickness detection unit that detects the thickness of the alignment film formed on the substrate surface, An alignment film forming apparatus, comprising: a control unit that controls the number of rotations of the holding table by the driving unit based on a detection value detected by the film thickness detection unit and a reference value. 11. The control device according to claim 10, wherein:
An alignment film forming apparatus, wherein the number of rotations of the holding table is calculated every predetermined number of times of application of the alignment film. 12. The alignment film according to claim 10, further comprising a firing furnace, wherein the film thickness detecting section detects the thickness of the alignment film of the substrate fired in the firing furnace. Forming equipment. 13. An electro-optical device manufactured by the manufacturing method according to claim 1. Description: 14. A projection display device using the electro-optical device defined in claim 13, wherein the light source, a light guide optical system for guiding light emitted from the light source to a light modulation unit, and the light modulation device And a magnifying projection optical system for magnifying and projecting light modulated by the means, wherein the electro-optical device is used as the light modulating means. 15. A projection display device using the electro-optical device according to claim 13, comprising: a light source; a color light separation unit configured to separate light emitted from the light source into a plurality of color lights; Light modulating means for modulating each of the color lights separated by the means, a color light synthesizing means for synthesizing the color lights modulated by the light modulating means, and a magnifying projection optic for enlarging and projecting the light synthesized by the color light synthesizing means. A projection-type display device, comprising: the electro-optical device as the light modulation unit.