JPH08262443A - Method for vertically orienting liquid crystal and device therefor - Google Patents

Abstract

PURPOSE: To provide a device for vertically orienting a liq. crystal capable of being easily fabricated in high yield. CONSTITUTION: A carrier gas with the flow rate specified by a mass flow controller 3 is introduced into R-OH held at a specified temp. in a cleaned bubbler 7, the carrier gas including a fixed amt. of R-OH is generated from the bubbler 7, the gaseous R-OH is mixed with a dilution gas with the flow rate controlled by a mass flow controller 13, the gaseous mixture is blown into a vapor-phase reaction chamber 17 contg. a substrate with an oxide layer exhibiting anisotropy in a specified direction formed on the surface, and a complete vapor-phase reaction between the oxide and R-OH is allowed to proceed on the substrate in the chamber 17 heated to a specified temp. with a heating means. After a specified amt. of the gaseous R-OH is introduced into the chamber 17, the supply of the gaseous R-OH to the chamber 17 is stopped, only the high-temp. dilution gas is supplied to the chamber 17, and the unreacted R-OH component remaining in the pipeline, in the chamber and on the substrate in the chamber is completely removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for inducing vertical alignment of liquid crystals.

[0002]

2. Description of the Related Art A liquid crystal display device in which an image is displayed by a liquid crystal display element has conventionally been widely used as an image display device for various electronic devices because an image display portion can be constructed to be thin. In addition, an image projector in which a liquid crystal display element is used as a light valve and the intensity of light from a light source is intensity-modulated by an image signal and projected on a screen through a projection optical system has come into practical use. . The liquid crystal display element uses a thermotropic liquid crystal and changes the alignment state of liquid crystal molecules in a nematic phase by an electric field so that a display operation in a specific display mode is performed. The basic alignment state of liquid crystal molecules in the nematic phase is the horizontal (homogeneous) alignment in which the director is in the horizontal position with respect to the substrate,
There are two types of vertical orientation (homeotropic orientation) in which the director is vertical to the substrate, and twists (or twisted) orientations, hybrid (hybrid) orientations, and tilts (tilt orientations) are available as deformations of the basic orientation states. It is well known that there are orientations and the like.

When a liquid crystal display device having better characteristics can be constructed by vertically aligning liquid crystal molecules of a nematic phase, the director or long axis of the liquid crystal molecules should be perpendicular to the surface of the substrate. Required to do. And, as a method conventionally proposed as a guiding method for vertically aligning liquid crystal molecules, a method of adding a dopant to a liquid crystal mixture (for example, US Pat. No. 3,656,834, US Pat. No. 3,698,449,
US Pat. No. 3,809,456, etc.), a method of using a surface-coated film for vertical alignment on the surface of a substrate (for example, US Pat.
No. 803050), a method of changing the surface of a substrate by a chemical reaction (eg, US Pat. No. 4022).
934 specification) and the like are known.

[0004]

Among the above-mentioned methods listed as examples of the conventional method for inducing the liquid crystal molecules to be vertically aligned, in the above method, the addition of a dopant is The characteristics such as conductivity are affected, the characteristic change with time becomes a problem, and the temperature dependence of the liquid crystal alignment occurs due to the dopant interposed between the surface of the substrate and the liquid crystal. In addition to problems with stability over a long period of time, there are also problems with uniformity in the above-mentioned method, and further, in the above-mentioned method, the substrate is placed in a liquid bath of alcohol. It is necessary to clean it by soaking the excess alcohol on the surface of the substrate by immersing it, and if the method of exhausting the alcohol while heating is adopted, Conflict Therefore, it is expected that the controllability of the reaction itself will be improved, but it is difficult to control so that the amount of alcohol introduced is just enough, and despite the introduction of the same amount of alcohol. In addition, there may be a problem in reproducibility because an excessive amount of alcohol is present on the surface of the substrate or an alcohol is insufficient on the surface of the substrate. . Therefore, it has been desired to develop a method and apparatus for inducing vertical alignment of liquid crystal that does not suffer from the drawbacks of the conventional method.

[0005]

According to the present invention, a step of holding R-OH at a designated temperature in a container kept in a clean state and a carrier gas kept at the designated temperature in the container are designated. Introducing at a flow rate, heating a substrate on the surface of which an oxide layer exhibiting anisotropy in a specific direction is heated, and depositing the above-mentioned carrier gas containing R-OH on the substrate without condensing it. A method for inducing vertical alignment of liquid crystal, which comprises a step of spraying and reacting the oxide with R-OH, and a step of purging an excess gas with a purge gas, and R- in a bubbler kept in a clean state. A means for holding OH at a specified temperature, a means for introducing a carrier gas maintained at a specified temperature into the bubbler at a specified flow rate, and a carrier gas containing R-OH output from the bubbler in a specified direction. Different to Is supplied to the vapor phase reaction chamber where the substrate oxide layer showing a sex is configured on the surface is housed,
Provided is a device for vertically aligning liquid crystals, which comprises a means for reacting an oxide and R-OH on the substrate heated to a predetermined temperature by a heating means, and a means for purging an excess gas by a purge gas. To do.

[0006]

In a bubbler kept in a clean state and kept at 1 atm, a specified temperature, such as 14 degrees Celsius, is set.
A carrier gas (for example, high-purity nitrogen gas) at a specified temperature, for example 140 degrees Celsius, is charged into R-OH held at 0 degrees at a specified flow rate (for example, 300 ml / min) by a mass flow controller. Introduce.
The bubbler generates and outputs bubbles of a carrier gas containing R-OH which is saturated at a vapor pressure corresponding to 140 degrees Celsius at 1 atmosphere. A certain amount of R-OH gas output from the bubbler is mixed with a diluting gas (for example, high-purity nitrogen gas) controlled to a specified flow rate by a mass flow controller, and oxidation that exhibits anisotropy in a specific direction. The material layer is supplied into a gas phase reaction chamber in which a substrate having a surface formed thereon is housed.

The substrate contained in the vapor phase reaction chamber is heated to a predetermined temperature, for example, 150 to 200 degrees Celsius by the heating means, and is output from the bubbler as described above. By introducing a gas in a state in which the R-OH gas having a constant flow rate diluted with a diluent gas is introduced into the gas phase reaction chamber, a complete gas phase reaction is promoted between the oxide on the substrate and R-OH. Let The supply of the R-OH gas from the bubbler to the gas phase reaction chamber is stopped after a lapse of a time period in which a predetermined amount of R-OH gas can be introduced from the bubbler to the gas phase reaction chamber. High temperature dilution gas (eg high-purity nitrogen gas)
Is supplied to completely remove the unreacted R—OH component remaining on the substrate in the piping system, the gas phase reaction chamber, and the gas phase reaction chamber.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents of the method and apparatus for inducing vertical alignment of liquid crystals of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal vertical alignment guide device for carrying out the liquid crystal vertical alignment guide method of the present invention. In FIG. 1, 1 is a carrier gas supply source.
From the above-mentioned carrier gas supply source 1, a gas suitable as a carrier gas, for example, high-purity nitrogen gas, high-purity hydrogen gas, inert gas (argon gas, helium gas)
A gas selected from the above can be supplied as a carrier gas. In the following description of the examples, it is assumed that high-purity nitrogen gas is used as the carrier gas. Further, as the diluent gas to be supplied from the diluent gas supply source 11, the same carrier gas as described above is used. In the following description of the embodiments, the diluent gas supply source 11 supplies the diluent gas. Nitrogen gas of high purity is supposed to be used as the dilution gas to be used.

The carrier gas of the carrier gas supply source 1 is supplied to the mass flow controller 3 through the pipe 2, and the diluent gas of the diluent gas supply source 11 is supplied to the mass flow controller 13 through the pipe 12. . The mass flow controller 3, 13
As is well known, the flow rate of gas can be controlled with high accuracy, and the mass flow controllers 3 and 13 described above supply the gas at the flow rates set respectively to the pipes 4 and 14 on the output side. Reference numerals 5 and 9 are valves and 7 is a bubbler. The bubbler 7 is filled with high-purity R-OH (R is an aliphatic carbon chain having up to about several tens of carbon atoms). Then, the bubbler 7, the pipes 4, 6, 8, 10, 14,
The components including 16, the valves 5, 9, the pressure controller (needle valve) 15 and the like are always kept at a predetermined temperature, for example, 140 degrees Celsius by the constant temperature bath 22.

Reference numeral 17 denotes a vapor phase reaction chamber. The vapor phase reaction chamber 17 is heated by a heating device, for example, an electric heater 18, so that the temperature of the substrate accommodated in the vapor phase reaction chamber 17 is Predetermined temperature, for example 150 to 20 degrees Celsius
It is designed to be held at 0 degrees. The gas phase reaction chamber 17 is provided with an exhaust pump (vacuum pump) 2 through a pipe 19.
When the exhaust pump 20 is operated, the gas in the gas phase reaction chamber 17 is discharged into the atmosphere through the pipes 19 and 21. In each of the above-mentioned constituent parts which are kept at a predetermined high temperature by the constant temperature bath 22 and in the gas phase reaction chamber 17, the R-OH supplied from the bubbler 7 is kept in the gas phase and is condensed. There is no such thing.

In the liquid crystal vertical alignment guide apparatus for carrying out the liquid crystal vertical alignment guide method of the present invention shown in FIG. 1, a substrate to be treated is first housed in a gas phase reaction chamber 17. After that, the exhaust pump 20 is operated to exhaust the gas phase reaction chamber 17, and the temperature of the substrate housed in the gas phase reaction chamber 17 by the electric heater 18 is set to a predetermined temperature, for example, 150 degrees Celsius. It is heated so that the temperature is maintained at 200 to 200 degrees. High-purity R-OH in bubbler 7
(Where R is an aliphatic carbon chain having up to about several tens of carbon atoms, for example, an aliphatic carbon chain having 18 carbon atoms),
The bubbler 7 and the pipes 4, 6, 8, 10,
The components including 14, 16 and the valves 5, 9 and the pressure controller (needle valve) 15 are kept at a predetermined temperature, for example, 140 degrees Celsius.

Each mass flow controller 13 has a flow rate of the diluent gas supplied from the diluent gas supply source 11 through the pipe 12 so that the pressure in the gas phase reaction chamber 17 becomes a predetermined vacuum degree. Control the piping 14, 1
0, the gas phase reaction chamber 17 via the needle controller 15
Supply dilution gas into the inside. The flow rate control by the mass flow controller 13 described above is performed by, for example, the gas phase reaction chamber 17
It may be performed based on the measured value of the atmospheric pressure in the gas phase reaction chamber 17 detected by a pressure sensor (not shown) installed therein. Next, when the valves 5 and 6 are opened, the mass flow controller 3 to which the carrier gas is supplied from the carrier gas supply source 1 through the pipe 2
The carrier gas having a predetermined flow rate set therein, for example, a flow rate of 300 ml / min, passes through the pipe 4, the valve 5 and the pipe 6 and is liquefied in the bubbler 7 with high purity R-OH (R is Bubbles form in an aliphatic carbon chain having up to about several tens of carbon atoms (for example, an aliphatic carbon chain having 18 carbon atoms).

In the bubble of the carrier gas, R-OH gas which is saturated at a vapor pressure corresponding to 140 degrees Celsius at 1 atmosphere in the bubbler 7 is contained. Therefore, the amount of R-OH gas delivered from the bubbler 7 to the pipe 8 by the carrier gas having a constant flow rate supplied into the bubbler 7 via the pipe 6 is always kept constant. Become. The carrier gas containing the R—OH gas sent from the bubbler 7 to the pipe 8 is supplied to the pipe 10 through the valve 9 in the open state.
No. 0 is supplied with the diluent gas from the mass flow controller 13 via the pipe 14, so the carrier gas containing the R—OH gas is diluted with the diluent gas supplied via the pipe 14. After being brought into the state, it is blown into the gas-phase reaction chamber 17 in the depressurized state through the needle valve 15 and the pipe 16.

As described above, the temperature of the substrate to be processed contained in the vapor phase reaction chamber 17 is
Since it is heated so as to be maintained at a predetermined temperature, for example, 150 to 200 degrees Celsius, it is introduced into the gas phase reaction chamber 17 in the depressurized state as described above via the needle valve 15 and the pipe 16. Between the R-OH gas in the carrier gas containing the blown R-OH gas and the above-mentioned oxide layer (for example, SiO2) in the substrate on the surface of which an oxide layer exhibiting anisotropy in a specific direction is formed. , The gas phase reaction proceeds.
After a lapse of time when a predetermined amount of R-OH gas is considered to be introduced from the bubbler 7 into the gas phase reaction chamber 17, the valve 9,
5 to close the bubbler 7 to the gas phase reaction chamber 17 R-
The supply of OH gas is stopped. In the gas phase reaction chamber 17,
From the mass flow controller 13 to the pipe 14, the pipe 10,
Diluting gas is supplied through the needle controller 15, the pipe 16 and the like to completely remove the unreacted R-OH component remaining on the pipe system, the vapor phase reaction chamber 17 and the substrate in the vapor phase reaction chamber 17. To do.

[0015]

As is apparent from the above description in detail, in the method and apparatus for inducing the vertical alignment of liquid crystal of the present invention, the liquid crystal is specified in the bubbler which is kept clean and kept at 1 atm. R- held at a predetermined temperature
Carrier gas at a specified temperature specified in OH,
The carrier gas containing a certain amount of R-OH introduced by the mass flow controller is introduced at a specified flow rate, and the certain amount of R-OH gas output from the bubbler is specified by the mass flow controller. After being mixed with a diluent gas whose flow rate is controlled, the mixture is blown into a gas phase reaction chamber in which a substrate having an oxide layer exhibiting anisotropy in a specific direction on the surface thereof is housed, so that a predetermined amount can be obtained by a heating means. A complete gas phase reaction can be made to proceed with the oxide and R-OH in the substrate housed in the gas phase reaction chamber that has been heated to the temperature of After a lapse of a time capable of introducing a predetermined amount of R-OH gas into the phase reaction chamber, the supply of R-OH gas from the bubbler into the gas phase reaction chamber is stopped, and the gas phase reaction is stopped. It is possible to completely remove the unreacted R-OH component remaining on the substrates in the piping system, the gas phase reaction chamber and the gas phase reaction chamber by supplying only the above-mentioned high temperature dilution gas to the chamber. Because it was done like this,
According to the present invention, the supply amount of R-OH (alcohol) can be accurately controlled, and the excess or unreacted alcohol component can be completely purged. The stability is greatly improved, and since the alcohol is not exposed to the air and it is not necessary to weigh each time, it is very unlikely that impurities are mixed in the alcohol, and therefore the yield is not adversely affected on the liquid crystal. Can be expected to improve significantly.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal vertical alignment guide device for carrying out a liquid crystal vertical alignment guide method of the present invention.

[Explanation of symbols]

1 ... Carrier gas supply source, 2, 4, 6, 8, 10, 1
2, 14, 16, 19, 21 ... Piping, 3, 13 ... Mass flow controller, 5, 9 ... Valve, 7 ... Bubbler, 11
... Diluting gas supply source, 15 ... Pressure controller (needle valve), 17 ... Gas phase reaction chamber, 18 ... Heating device (electrothermal heater), 20 ... Exhaust pump,

Claims (3)

[Claims] 1. A substrate having a surface on which an oxide layer exhibiting anisotropy in a specific direction is heated, and a carrier gas containing R—OH saturated at a specified temperature is sprayed onto the substrate to obtain a substrate surface. A method for inducing vertical alignment of liquid crystals, which comprises reacting the oxide layer with R-OH. 2. In a container kept in a clean state, R-
A step of holding OH at a specified temperature, a step of introducing a carrier gas maintained at the specified temperature into the container at a specified flow rate, and a substrate having an oxide layer exhibiting anisotropy in a specific direction on its surface. And a step of spraying the carrier gas containing R-OH onto the substrate without condensing the R-OH to react the oxide with the R-OH, and purging excess gas with a purge gas. A method for inducing vertical alignment of liquid crystal, which comprises the step of: 3. R- in a bubbler kept in a clean state.
A means for holding OH at a specified temperature, a means for introducing a carrier gas maintained at a specified temperature into the bubbler at a specified flow rate, and a carrier gas containing R-OH output from the bubbler in a specified direction. The oxide in the substrate in the state of being supplied to the gas phase reaction chamber in which the substrate having the oxide layer exhibiting anisotropy is housed and being heated to a predetermined temperature by the heating means. And a device for reacting R-OH with a means for purging excess gas with a purge gas.