JPH0290968A - Production equipment of organic thin film - Google Patents

Abstract

PURPOSE:To obtain a uniform and stable Langmuir-Blodgett's membrane by equipping a trough for holding water surface on which a monomolecular membrane is developed, a barrier compressing the monomolecular membrane and a surface pressure gauge for measuring the surface pressure of the monomolecular membrane. CONSTITUTION:The ultrasonic wave-generating sources being a disturbing and impressing groove 5 are attached along both side walls 4 of a trough. As a water flow system, two rollers becoming the disturbing and impressing mechanism 5 are provided under the water surface near to both side walls 4 are rotated with a motor from the outside by driving a roller belt. Thereby surface water flow is caused toward the center of the trough from the side walls 4. As an air flow system, the shape of the barrier is regulated to 1-2mm thickness and the air nozzles becoming the disturbing and impressing mechanism 5 are arranged along both side walls 4. The air nozzles are set to such direction that the air flow is allowed to slantingly collided against water surface near to the side walls from the direction of 45 deg. and the surface water flow is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention] (Industrial Application Field) The present invention is an organic thin film manufacturing apparatus for manufacturing an organic thin film by the Langmuir-Prodgett method.

(Prior art) The Langmuir-Prodgett (LB) method is a method in which a monomolecular film is compressed and formed on a water surface, and this monomolecular film is accumulated on a substrate to form an ultra-thin organic film. It is expected to be applied to electrical and optical devices, and research has become active.

Conventional LB film production equipment consists of a trough that holds the water surface where molecules are spread, a barrier that compresses the spread monomolecular film, a surface pressure gauge that monitors the compression state, and a surface pressure gauge that holds the substrate and performs cumulative operations. It consists of an accumulator and an accumulator. The trough has a rectangular shape, and is generally a unidirectional compression type with one barrier or a two-way compression type with two barriers.

In the LB method, LB molecules dissolved in a solvent such as chloroform are dropped onto the water surface using a syringe or the like and developed. The monolayer is then compressed by advancing the barrier and reducing the water surface area. The surface molecular density of the monomolecular film on the water surface is monitored by a surface pressure meter as the surface pressure, and considering that the LB film, which becomes a solid condensed film, is applied to electrical and optical elements, the film structure must be uniform and free of defects. becomes important. To achieve this, it is necessary to first form a uniform monomolecular film on the water surface, and then use film-forming technology and equipment to accumulate it on the substrate without destroying it. However, with the conventional device IK, only a limited number of molecules such as aliphatic molecules can be uniformly compressed into a monomolecular film on the water surface, and molecules containing polymers and dyes can only form an unstable film due to the compression action of the barrier. The reason for this failure is thought to be that the monomolecular film on the water surface, which consists of molecules containing polymers and pigments, has extremely high viscosity. It is said that this viscosity causes the molecules on the trough sidewall to move during the compression operation of the barrier, resulting in large deformation of the monomolecular film. Moving wall compression devices are commercially available to improve this problem. Although this moving wall device improves the deformation of the film in the vicinity of the barrier and trough sidewall to some extent, the deformation of the film on the substrate side facing the barrier increases, which is insufficient.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an organic thin film manufacturing apparatus that can produce a uniform and stable Langmuir-Prodgett film.

[Structure of the invention]

(Means for Solving the Problems) The present invention includes a trough that holds a water surface on which a monomolecular film is spread, a barrier that compresses the monomolecular film, a surface pressure meter that measures the surface pressure of the monomolecular film, and a substrate. This is an organic thin film production apparatus characterized by comprising an accumulation mechanism for holding and performing an accumulation operation, and a disturbance application mechanism for disturbing at least a portion of the monomolecular film near the barrier and the inner wall of the trough.

The disturbance application mechanism is: ■ applying mechanical vibrations or sound waves along the trough side wall; ■ generating a water surface flow from the side wall toward the center of the water surface so that the membrane adheres to the trough; and ■ starting from the side wall. A method in which an air flow is blown onto the water surface toward the center of the water surface, resulting in a surface flow that causes the membrane to stick to the trough. How to reduce the viscosity of ■
A method that takes advantage of the fact that a monomolecular film has a surface dipole and applies a high electric field near the trough sidewall in a direction that repels molecules, ■
It is constructed using a method of irradiating light such as infrared light along the vicinity of the trough side wall.

Further, the monomolecular film to be disturbed may be at least a portion near the barrier and the inner wall of the trough, but it is effective to disturb the monomolecular film near the inner wall of the trough side wall located perpendicular to the barrier.

(Function) First, uniform compression of the monomolecular film means that the surface molecular density of the monomolecular film on the water surface must be controlled to be constant. Since surface pressure is another measure of the surface molecular density of a monolayer on a water surface, it is actually necessary to compress it so that the surface pressure is constant. Also, it is important for the accumulation that the surface pressure is uniformly controlled to a predetermined value.

Regarding the deformation of the monomolecular film on the water surface due to the compression action of the barrier, the issue is not the magnitude of the deformation, but whether or not this deformation leads to non-uniformity of the surface pressure. Therefore, the inventors performed multi-point measurement using a plurality of surface pressure gauges as shown in FIG.

As a result, it was found that the surface pressure was highest near the intersection of the barrier and the trough (Figure 9). As shown in Figure 10,
In fluid mechanics, when a liquid flows through a tube, the velocity of the liquid at the tube wall is zero. The further away from the wall, the faster the flow velocity becomes, reaching the original flow velocity. This low flow velocity region is called a boundary layer, and the thickness δ of this boundary layer decreases as the flow velocity V increases.
It increases as the viscosity η of the liquid increases.

A similar situation can be considered in a two-dimensional system such as a monomolecular film on a water surface. That is, due to the compressive action of the barrier, the monomolecular film on the water surface flows forward, albeit slightly. At the trough sidewall, the membrane flow velocity becomes zero and a boundary layer is formed. For aliphatic molecules, the viscosity of the membrane is very small, so the thickness of this boundary layer δ
is very small and can be ignored. However, molecules containing polymers and dyes have an order of magnitude higher film viscosity, and δ is several cm or more.

Although the membrane moves in this boundary layer, the barrier is forcibly advanced, causing local compression and generating a very high surface pressure.

One way to prevent this boundary layer effect is to advance the sidewall at the same speed as the membrane flow rate. This is the principle of the moving wall system, but since the membrane is not just a fluid but a fluid that shrinks due to compression, the sidewalls must shrink accordingly.

In addition, when the barrier faces the movable side wall: τ, the substrate is fixed, and local compression occurs near the intersection of the side wall and the substrate.
The moving wall method is incomplete.

The present invention is characterized in that a mechanism is provided to provide disturbance along the trough side wall so as to eliminate this boundary layer. In the case of the sound wave generation method, the action is that the sound waves disrupt the membrane near the trough, thereby destroying the boundary layer.

Both the water surface flow and the air flow directly or indirectly lower the molecular density near the trough side wall, lowering the viscosity, thinning the boundary layer, and also making the water surface flow have a component in the compression direction. I will assist the flow of this process.

The viscosity can also be reduced by heating the material. Since heating the entire trough is unfavorable for the stability of the monomolecular film, the viscosity of the boundary layer is reduced by heating only the vicinity of the trough sidewall. The light irradiation method also has a similar effect when infrared rays are used as the light.

Also, by supplying a small amount of molecules with very low viscosity from the trough side wall during compression, the flow in the boundary layer can be made smoother.

(Example) The trough 1 is rectangular, and there is one barrier 2 in the long axis direction.
Directional compression. Surface pressure systems are set at the center of the barrier, one end of the barrier, the center of the trough, and the ends of the trough to measure surface pressure distribution, and one to two of these systems are sufficient.

Next, other embodiments will be described below. An ultrasonic generation source, which is a disturbance applying structure 5, is attached along the both side walls 4 of the trough (the first
figure).

In the water flow system, two rollers serving as a disturbance applying mechanism 5 are installed under the water surface near the side walls 4 of the trough. It is rotated by an external motor using this roller belt drive.

When the roller is rotated in the rotation direction shown in the figure, a water surface flow is generated from the trough side wall 4 toward the center of the trough (Fig. 3).

In the air flow method, the barrier shape is made to have a thickness of 1 to 2 mm, and air nozzles serving as the disturbance applying mechanism 5 are arranged along the both side walls 4 of the trough. The direction of the air nozzle is set so that the air flow hits the water surface near the side wall at an angle of 45 degrees and generates a water surface flow at an angle of 45 degrees to the compression direction of the barrier 2.

From this K, the water surface flow generated by the air flow has a trough l.
There is a component flowing toward the center and a component flowing in the compression direction (Figure 4).

In the heating method, thin heating elements serving as the disturbance applying mechanism 5 are placed under the water surface near both sides of the trough 4 along the trough 1. By passing a current through this heating element, only the monomolecular film on the water surface near the side wall can be heated, making it possible to lower the viscosity. At this time, the trough 1 has a water jacket structure, and low-temperature constant-temperature water is flowed through it to maintain the desired temperature (FIG. 5).

In the light irradiation method, infrared rays are irradiated from above the water surface by a disturbance application mechanism 5 instead of placing a heating element in the water. The infrared source is focused into a long, narrow beam. This makes it possible to heat only the monomolecular film on the water surface near the side wall (FIG. 6).

The second molecule supply system provides gutter along the side wall which is connected at places to the trough water surface by water channels. Molecules with low viscosity, such as stearyl alcohol or stearylamide, are deployed in this gutter (disturbance application mechanism 5). When the barrier 2 moves forward, the molecules in the side gutter are compressed and supplied to the water surface inside the trough l through the narrow passage. Molecules on the water surface inside the trough l have a high viscosity, so they do not enter the gutter. As a result, a region with low viscosity is formed near the trough side wall 4 (FIG. 7).

The occurrence of surface pressure distribution on highly viscous aluminum stearate molecules was measured using various types of organic film forming apparatus using C. When the barrier is expanded to its maximum width, the trough size is 100 mm wide and 3001 mm long. The surface measurements were set at three points: in front of the center of the barrier, near the intersection of barrier 2 and side wall 4, and on the opposite side of barrier 2. An aqueous solution of 2×10' mol/l of aluminum chloride is placed in the trough 1, and stearic acid dissolved in chloroform is developed.

In a conventional trough that does not implement the above method, compression speed = 5
When the compression operation was started at u+/min, the largest surface pressure was exhibited near the intersection of the trough side wall 4 and the barrier 2 (FIG. 9). On the other hand, in the apparatus in which the above embodiment was implemented, the surface pressure distribution was almost eliminated (FIG. 8). Furthermore, as a result of X-ray diffraction evaluation of 50 FrI accumulated on a silicon substrate, the accumulated film made from the monomolecular film according to the present invention showed a high-order diffraction peak, indicating that it had a layered structure. Do you get it. However, almost no diffraction peaks were observed in the cumulative films made from single molecules that were not subjected to the present invention.

〔Effect of the invention〕

By using the organic thin film forming apparatus of the present invention, it is possible to compressively form a monomolecular film on a water surface having a uniform surface pressure, that is, a surface molecular density, and thus a good organic thin film can be obtained.

[Brief Description of the Drawings] Fig. 1 is a schematic diagram of an embodiment of the present invention, Fig. 2 is a diagram for explaining the present invention, and Figs. 3 to 7 are schematic diagrams of an embodiment of the present invention. FIG. 8 is a diagram showing the characteristics of the present invention, FIG. 9 is a diagram showing the characteristics of a comparative example, and FIG. 10 is a diagram for explaining the present invention in detail. l...Trough 1 2...Barrier, 3...Water surface, 4...Trough side wall, 5...Disturbance application mechanism. Agent Patent Attorney Noriyuki Ken Yudo Matsuyama Hikaru Noza 2-Ka, Misaki-to ↓ Te 7F- Sai, ρ-sai and Bini'-togure, 5 houses (Ru to 2 ←-ro, Natto H Doθ l〃 , ≧ψ 9ρθ Fig.θ !lθ 21′θ 3ρθ Be°〕Year front U 0ml Fig. Fig.

Claims (1)

[Claims] (1) A trough that holds the water surface on which the monomolecular film is developed, a barrier that compresses the monomolecular film, a surface pressure meter that measures the surface pressure of the monomolecular film, and an accumulation mechanism that holds the substrate and performs the cumulative operation. An apparatus for producing an organic thin film, comprising a mechanism for applying disturbance to at least a portion of the monomolecular film near the barrier and the inner wall of the trough.