JPH058050B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to an apparatus for producing a thin film, which is a functional part of a semiconductor or an optical device, and in particular,
This invention relates to an LB film fabrication device that uses a single molecule accumulation method, that is, the Langmiur-Blodget method (LB method).

<Background Art> Conventionally, the use of materials in the semiconductor technology field and the optical technology field has mainly focused on inorganic materials that are relatively easy to handle. One reason for this is that technological progress in the field of organic chemistry has lagged significantly behind that in the field of inorganic materials.

However, recent technological advances in the field of organic chemistry have been remarkable, and it is said that the development of materials for inorganic substances has almost reached its limit. Therefore, there is a demand for the development of functional organic materials as new functional materials that surpass inorganic materials. The advantages of organic materials are that they are inexpensive, easy to manufacture, and highly functional. On the other hand, organic materials that have overcome heat resistance and mechanical strength, which have been thought to be inferior, have recently been created one after another. Against this technical background, some of the functional parts (mainly thin film parts) of IC devices such as logic elements, memory elements, and photoelectric conversion elements, and optical devices such as microlens arrays and optical waveguides. Or, from the proposal to replace the conventional inorganic thin film with an organic thin film, we ended up with a molecular electronic device or bio-related material in which a single organic molecule has functions such as a logic element or a memory element. Proposals to create logic devices (eg, biochips) have recently been announced by several research institutions.

Thin films used to create the above-mentioned devices using such organic materials are prepared using a known single molecule accumulation method, namely the Langmiur-Blodget method (LB method).
It can be formed by

In the LB method, as shown in FIG. 1, a single molecule 1 consisting of a hydrophilic group 1a and a hydrophobic group 1b, that is, a membrane constituent material, is dissolved in a volatile solvent such as benzene or chloroform, and the mixture is placed in a water tank 3. The monomolecular film 2 (gas film at this point) left on the water surface after the solvent evaporates is reduced by reducing the area surrounded by the frame 4. This is a method in which the material is transformed into a solid film by increasing its areal density, and this is transferred to a substrate (not shown) by a vertical dipping method or a horizontal deposition method.

However, according to this method, the area of the monolayer on the water surface decreases by the amount of the monolayer transferred onto the substrate. In other words, since the monomolecular film (solid film) on the water surface is required to be uniform, if the monomolecular film is continuously transferred onto the substrate while keeping its surface density constant, Since the area surrounded by the frame gradually decreases and approaches 0, there is naturally a limit to the number of times it can be transferred.

<Disclosure of the Invention> The purpose of the present invention is to solve the above-mentioned problems, and for this purpose, a liquid flow generator is provided to control the surface pressure of the monomolecular film so as to obtain a desired areal density.
Furthermore, by changing the shape of the liquid tank so as to reduce the speed of the liquid flow, it is possible to facilitate the continuous accumulation of a monomolecular film and also to improve the accumulation achievement rate.

The principle of the present invention will be explained below with reference to FIG.

When a monomolecular film 2 is spread on a water surface with a certain flow velocity, the monomolecular film 2 moves in the direction of the water flow (in the direction of the arrow) due to the attraction between the molecules constituting the monomolecular film 2 and the water. ) is pulled with a constant force. At this time, if there is a barrier 8 in the path of the monomolecular film 2 that can block only the movement of the monomolecular film 2 without affecting the flow of water, the monomolecular film 2 will act against the barrier with a certain force. It is pressed against 8. That is, this shows that the force with which the monomolecular film 2 presses against the barrier 8, in other words, the surface pressure of the monomolecular film 2, can be easily controlled by changing the flow rate of water. The present invention is characterized by applying this principle.

<BEST MODE FOR CARRYING OUT THE INVENTION> Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in each drawing, the same reference numerals represent the same structural members and have the same functions.

First, a first embodiment will be described with reference to FIG. Stearic acid 1x in solvent chloroform
0.1 ml of a solution dissolved at a ratio of 10 ^-3 M/20
The water is dripped at a speed of cm/sec from the water flow generator 7 in the direction of the arrow in the water surface flowing in the water tank 3 in an area 9 upstream from the barrier 8 (hereinafter referred to as the dripping area 9) and spread. However, a monomolecular film 2 of approximately 120 cm ² was formed on the water surface surrounded by the barrier 8.
When the surface pressure of the monomolecular film 2 was measured using a surface pressure measuring device (not shown), it showed a value of 24 dyne/cm, confirming that the monomolecular film 2 had formed the desired solid state. Furthermore, when the velocity was varied in the range of 15 to 25 cm/sec, it was confirmed that the surface pressure changed almost in proportion to this, and it became clear that the surface pressure could be controlled by the flow velocity. Furthermore, at this time, when the dropping amount was varied within the range of 0.05 to 0.3 ml, it was confirmed that the surface pressure also varied in proportion to this.
In other words, it has become clear that the surface pressure can also be controlled by the dropping amount. On the other hand, in a region 10 near the barrier 8 (hereinafter referred to as the cumulative region 10),
When the monomolecular film was accumulated on the substrate by the vertical dipping method, a good film with an accumulation rate of 90 to almost 100% could be obtained.

Thereafter, while controlling the flow rate so that the surface pressure is constant, the decrease in the monomolecular film 2 transferred to the substrate in the accumulation region 10 is compensated for by dropping the film constituent material in the dropping region 9. As a result of repeating the accumulation operation, we were able to easily achieve continuous accumulation, which was difficult with conventional devices.

Next, a second embodiment will be described with reference to FIG.

This embodiment is a slight improvement of the first embodiment. That is, in the first embodiment, in the accumulation region 10, the flow of water is disturbed by the submerged substrate (not shown) in the case of vertical immersion accumulation, as well as the barrier 8, and the monolayer 2 This is undesirable because the surface pressure may be bent or the surface pressure, which should be constant, may fluctuate temporarily. Therefore, in this embodiment, the first embodiment is improved by varying the depth of the water tank 3 and slowing down the flow (flow velocity) of water in the accumulation region 10. in particular,
The depth of the water tank in the region 11 that forms the surface pressure of the monomolecular film 2 (hereinafter referred to as the surface pressure forming region 11), including the dropping region 10, is made shallow to 1 cm, and the depth of the water tank in the accumulation region 10 is reduced to 1 cm. The depth was 10cm.
As a result, the flow velocity in the surface pressure forming region 11 was reduced to 20
Even in terms of cm/sec, the flow rate in the accumulation region 10 is about 1/10, and when the monomolecular film is accumulated on the substrate, the yield was 20 to 60% in the first example, but It improved by 50-100%.

Next, a third embodiment will be explained with reference to FIG.

This embodiment is a modification of the second embodiment, and is a modification of the second embodiment.
This is an improvement on the first embodiment by varying the width of the flow rate and slowing down the flow velocity in the accumulation region 10. Specifically, the width of the water tank 3 in the surface pressure forming area 11 including the drip area 9 was narrowed to 2 cm, and the width of the water tank 3 in the accumulation area 10 was widened to 20 cm. As a result, even if the flow velocity in the surface pressure forming region 11 was 20 cm/sec, the flow velocity in the accumulation region 10 was about 1/10, and when the monomolecular film was accumulated on the substrate, the yield was lower than in the first embodiment. but
It improved from 20 to 60% to 50 to 100%.

Next, a fourth embodiment will be described with reference to FIGS. 6a and 6b.

In this embodiment, only the vicinity of the water surface is partitioned into one aquarium 3 by a plurality of fan-shaped barriers 8 (five in this embodiment) (hereinafter, the partitioned area will be referred to as a block). The structure is such that water flows into each block from the vicinity toward the outer periphery. The apparatus according to this embodiment is similar to the first embodiment in terms of the ability to accumulate the monomolecular film 2 on the substrate and the ease of continuous accumulation.

Furthermore, a unique feature of this embodiment is that it is possible to easily accumulate different types of single molecules (heterostructure). In other words, for each block in advance,
Monomolecular films of different materials are spread on the water surface,
After a monomolecular film is accumulated on a substrate using the vertical dipping method in one block, the same operation is repeated in another block to form a heterogeneous accumulation (the constituent molecules of the monomolecular film differ in the direction of accumulation). It was easy to form. At this time, it is possible to move between blocks in the gas phase or in the aqueous phase, so for example, in a heterojunction of a film forming a Y-type film, there is a gap between hydrophilic groups and between hydrophobic groups. I was able to set it freely in between.

Next, a fifth embodiment will be described with reference to FIG.

This embodiment differs from the previous embodiment by circulating the outflowing water and returning it to the water tank 3.
It is characterized by its efforts to reuse water.
In FIG. 7, Pyrex glass tubes are used for most of the circulation path 12, and the water accumulated in the water tank 13 is pumped out by a pump 14, and the flow rate is controlled by a gate valve 15. It's summery.

By circulating the outflowing water in this way, there is no need for a system to replenish lost water, and the entire device becomes simpler.

Next, a sixth embodiment will be described with reference to FIG.

This embodiment is characterized in that a filter 16 for removing dust is inserted in the middle of the circulation path 12, as shown in the figure. Specifically, when a filter 16 was inserted to remove dust of 0.5 μm or more,
Previously, it was possible to see visible dirt in the aquarium 3 after using the device only 2 to 5 times (5 to 10 hours), but now it is visible even after using the device over 100 times. No trash was found. In other words, water can be easily purified with a simple configuration of inserting a filter into the circulation system of the water channel.

Next, a seventh embodiment will be described with reference to FIG.

As shown in the figure, this embodiment is characterized in that a PH control device 30 is provided in a part of the circulation path 12. Specifically, when predetermined amounts of sodium hydroxide solution and hydrochloric acid were respectively mixed into the device using a micro cylinder, diffusion of sodium hydroxide and hydrochloric acid, which was difficult in the past, was achieved in this example. Because it is flowing, it takes a very short time (5~
It became possible to obtain the specified pH within 30 minutes).
Furthermore, it is clear that according to this device, it is also possible to control the PH while a monomolecular film is formed on the water surface.

Next, an eighth embodiment will be described with reference to FIG.

As shown in the figure, this embodiment is characterized in that a heat exchanger 31 is provided in a part of the circulation path 12. Specifically, the circulating water passes through 3/
A heat exchanger 31 is installed, which is a Pyrex glass tube with a diameter of 8 inches and a wall thickness of 0.5 mm, wrapped around a hollow copper pipe.
Via the temperature sensor 33 provided in the water tank 3,
The temperature of the circulating water was controlled by flowing a liquid at a desired temperature into the copper pipe while controlling it with the temperature control device 32. As a result, the water in tank 3 was
It was possible to control the temperature within a range of 80°C with an accuracy of ±0.5°C. Therefore, it has become possible to easily control the temperature conditions during monomolecular film accumulation.
Furthermore, it is clear that according to this apparatus, it is also possible to perform temperature control while the monomolecular film is formed on the water surface.

Finally, the ninth embodiment will be explained with reference to FIGS. 11a and 11b.

This embodiment is characterized in that the barrier 8 in the previous embodiment is configured to be movable in the vertical direction. Specifically, the barrier 8 is moved by a motor (not shown).
(However, manual operation is also possible.) It becomes possible to wash away the unnecessary monomolecular film 2 on the water surface and clean the water surface, reducing the monomolecular film accumulation. This greatly reduced the time and effort required for preparation.

As explained above, the present invention relates to a device for controlling the surface pressure of a monomolecular film using a liquid flow, and the present invention relates to a device for controlling the surface pressure of a monomolecular film by a liquid flow, and by providing a means for generating a liquid flow in a liquid tank, an arbitrary flow rate can be caused to flow into the tank, and the liquid can be further controlled. By providing a means for slowing down the liquid flow by varying the depth or width of the liquid tank so as to reduce the speed of the flow, it is possible to facilitate the continuous accumulation of a monomolecular film and also to improve the accumulation achievement rate. We can provide equipment that can.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a conventional LB film production apparatus, Fig. 2 is a diagram explaining the principle of a method for controlling the surface pressure of a monomolecular film by a water flow, and Fig. 3 is a schematic diagram of a conventional LB film production apparatus.
4 is a schematic sectional view of the second embodiment, FIG. 5 is a schematic perspective view of the third embodiment, and FIGS. 6a and 6b are respectively the fourth embodiment. 7 is a schematic diagram of the fifth embodiment, FIG. 8 is a schematic diagram of the sixth embodiment, FIG. 9 is a schematic diagram of the seventh embodiment, 10th
The figure is a schematic configuration diagram of the eighth embodiment, and Figures 11a and b
are schematic cross-sectional views before and after removing the barrier 8 in the ninth embodiment, respectively. 1... Monomolecule, 1a... Hydrophilic group, 1b... Hydrophobic group, 2... Monomolecular film, 3... Water tank, 4... Frame, 7
... Water flow generator, 8 ... Barrier, 9 ... Dripping region, 10 ... Accumulation region, 11 ... Surface pressure formation region, 12 ... Circulation path, 13 ... Water tank, 14 ...
Pump, 15...gate valve, 16...filter, 21...PH sensor, 30...PH control device, 3
1... Heat exchanger, 32... Temperature control device, 33...
…Temperature sensor.

Claims (1)

[Claims] 1. A film forming apparatus comprising a liquid tank in which film forming molecules are developed, and the liquid tank is provided with means for generating a liquid flow and means for decelerating the liquid flow.