JP2000282240A - Method of forming organic monomolecular film and patterning method thereof - Google Patents

Abstract

(57) [Abstract] (with correction) [PROBLEMS] To provide a method for self-assembling a dense monomolecular film on a substrate by a simple method, and a method for patterning an organic monomolecular film with high accuracy and a simple method. . An organic monomolecular film is formed by preliminarily cleaning a substrate by some method, hydrophilizing the surface, and forming a monomolecular film of fluorinated alkylsilane on the substrate by a chemical vapor deposition method. Form. Further, the organic monomolecular film is patterned by irradiating ultraviolet rays in an atmosphere containing oxygen and removing the monomolecular film of fluorinated alkylsilane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a dense monomolecular film on a substrate which can be subjected to a hydrophilic treatment by a simple method, and a method for patterning the formed monomolecular film. More specifically, a method of forming a monolayer of fluorinated alkylsilane by a simple method and patterning it by a simple method to arbitrarily create a hydrophilic and water-repellent region on the substrate, or a method of generating a large friction. It relates to a method of arbitrarily creating a region and a small region.

[0002]

2. Description of the Related Art As a method for forming an organic monomolecular film, a silane coupling material, a titanium coupling material, and the like have been conventionally known, and are widely used industrially. These molecules are adsorbed and bonded to the substrate as single molecules, but the density is not so high and only one molecule is adsorbed per hundred atoms of the substrate, which is sparse from the microscopic point of view. . In recent years, denser monolayers can be produced by a method called SAM (Self Assembling Molecule).

[0003] Known self-assembled molecules include long-chain alkyl carboxylic acid compounds (-COOH) and thiol compounds (-SH). In the former, a monomolecular film can be formed by using the LB (Langmuir-Blodgett) method. That is, this is a method in which a monomolecular film is previously formed on the water surface, and is transferred to the substrate surface by vertical pulling or horizontal transfer. However, the monomolecular film formed by the LB method has disadvantages such as low adhesion to a substrate, difficulty in high purity due to use of a salt, low productivity and poor uniformity, and many restrictions on materials. Not suitable for industrial use.

On the other hand, in the latter thiol compound, the thiol compound is self-assembled on the surface of gold only by dipping in the solution, hydrogen is removed, and sulfur is covalently bonded to gold. It has been confirmed that this gold thiol monomolecular film self-assembles very densely. Almost one molecule corresponds to one gold atom. In addition, various types of thiol molecules have been synthesized, and when they are self-assembled, the terminal functional groups of the molecules appear on the surface, so that the gold surface can be changed to a surface having various properties. For example, when a thiol molecule having a terminal of fluorocarbon is used, a high-quality water-repellent surface can be manufactured. In the same manner, a completely hydrophilic surface can be obtained (Japanese Patent Application Laid-Open No. 9-827059). However, the gold thiol self-assembled film must have a gold surface. Therefore, it is necessary to previously form a gold film having a certain thickness. In addition, there is an inconvenience that an operation for partially removing the gold film is required later, and when a device or the like is manufactured using water repellency or hydrophilicity, gold remains on the base. Therefore, there is a disadvantage that the range of application of the gold thiol self-assembled film is limited.

[0005]

An object of the present invention is to provide a method for self-assembling a dense monolayer on a substrate by a simple method. It is desirable that the surface of the substrate is not a special material such as gold, but has a property generally observed to some extent. Further, when manufacturing a device or the like utilizing water repellency or hydrophilicity, it is desirable that the substrate surface has no significant impurities left on the underlayer, and it is of course necessary to have high industrial productivity.

[0006] In addition, if an organic monomolecular film can be patterned with high accuracy and a simple method, application fields can be opened up, but no patterning method has been proposed in the past.

[0007]

In order to solve the above problems, the method of forming an organic monomolecular film according to the present invention has the following features.

(1) The method is characterized in that after the substrate has been washed by some method in advance, the surface is made hydrophilic, and a monomolecular film of fluorinated alkylsilane is formed on the substrate by chemical vapor deposition. .

(2) The substrate is cleaned by ultraviolet or oxygen plasma treatment.

(3) A monomolecular film of a fluoroalkylsilane is formed on a substrate by a chemical vapor deposition method using a silicon compound represented by the general formula (I).

(4) Chemical vapor deposition is performed under atmospheric pressure or
It is characterized in that it is performed in a reduced pressure atmosphere close to the atmospheric pressure of Torr or less.

(5) The method is characterized in that the chemical vapor deposition is performed at a temperature of 200 ° C. or less.

(6) An appropriate amount of the silicon compound represented by the general formula (I) or its solvent diluted solution is finely sprayed on a substrate in advance by an ink-jet method, and is evaporated to form a chemical vapor over the entire surface of the substrate. It is characterized by being deposited. In order to solve the above problems, the method for patterning an organic monomolecular film according to the present invention has the following features.

(7) The method is characterized in that a monomolecular film of fluorinated alkylsilane is removed by irradiating ultraviolet rays in an atmosphere containing oxygen.

(8) Only a desired region is irradiated with ultraviolet rays using a mask to remove the monomolecular film.

(9) The monomolecular film of fluorinated alkylsilane is removed by using an electron beam.

(10) After removing the monomolecular film, a silicon compound containing no fluorine atom is adsorbed. The lithography method of the present invention has the following features.

(11) The monomolecular film of fluorinated alkylsilane left by patterning is used as an etching stopper as a resist film.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Using a Xe ₂ excimer lamp (manufactured by Ushio) on an oxide surface, ultraviolet light of 172 nm was applied under atmospheric pressure.
After irradiation for 1 minute, light washing occurs, resulting in the formation of -OH groups at a high density. Infrared spectroscopy, and density -OH6 pieces / nm ² hydroxyl groups from the analysis results, such as Atsushi Nobori spectroscopy (TDS), sufficient bonding group to finely filled with silicon compound monomolecular film had occurred I understand. Although this effect depends on the wavelength of the ultraviolet light used, it was similarly recognized. The effect of hydrophilization was also observed in the oxygen plasma treatment.

Subsequently, the fluorinated alkylsilane is evaporated,
It has been found that a very dense monomolecular film can be formed by chemical vapor deposition on the substrate. Based on the following examples,
The present invention will be described in detail. The method for cleaning the substrate, the fluorinated alkylsilane material to be used, and the conditions for the chemical vapor deposition method are not particularly limited.

(Example 1) As a material of an organic monomolecular film,
3,3,3-trifluoropropyltrimethoxysilane (hereinafter F
AS-3), tridecafluoro-1,1,2,2-tetrahydrooctyltrimethoxysilane (hereinafter referred to as FAS-13), heptadecafluoro-1,1,2,2-tetrahydrodecyltrimethoxysilane (Hereinafter referred to as FAS-17) were prepared. Table 1 shows the chemical formula, molecular weight, and boiling point / pressure of the materials used.

[0022]

[Table 1]

Single crystal silicon was used as a substrate. First, the surface of the silicon substrate was washed with ultraviolet light (wavelength: 172 nm) to remove organic impurities to obtain a clean surface. Since the surface of the substrate is covered with a natural oxide film (SiO ₂ ), water vapor in the air is immediately adsorbed on the surface of the substrate, and the surface is covered with OH groups to become a hydrophilic surface. Next, using an apparatus as shown in FIG.
Fluoroalkylsilane molecules were deposited on the hydrophilized silicon substrate by a chemical vapor deposition method. First, place the beaker containing the fluoroalkylsilane and the Si substrate in a Teflon sealed container, then place the entire container in an electric furnace, raise the temperature, and the fluoroalkylsilane evaporates, leaving the substrate on the substrate. Chemical vapor deposition.

The temperature inside the closed vessel was 100 ° C. FIG. 3 shows the relationship between the deposition time and the film thickness. The film thickness was measured with an ellipsometer. Atomic force microscope (AFM), measurement using X-ray (XP
S) identified the formation of a monolayer. FIG. 1 shows the structure of the prepared monomolecular film after adsorption. The surface energy of each monolayer after 7 hours of deposition was calculated from the contact angle with water, methylene iodide and hexadecane.
mN / m, FAS-13 was 20 mN / m, and FAS-17 was 16 mN / m. The Si-OH that did not form a monomolecular film was 80 mN / m.

Next, the frictional force of the three materials was determined by LEM (Lateral Foam).
rce Microscopy). According to this method, the longitudinal deflection and the lateral deflection are simultaneously measured as shown in FIG. 4 using an apparatus modified from a nuclear microscope, and the frictional force acting on the sample surface can be detected. As shown in Fig. 1, the end of each material is a fluorocarbon chain, so if the substrate is densely covered with fluorinated alkylsilane, the frictional force will be very low, and if the substrate is covered with SiO2 When it comes out, the frictional force increases. The frictional force takes an intermediate value depending on the coating degree of the fluoroalkylsilane. As a result of the measurement, the frictional force was relatively as follows: Si-OH> FAS-3 >> FAS-13 ≧ FAS-17. From these results, it is inferred that FAS-3 has a low coverage and does not form a sufficiently dense monomolecular film. Looking at the film thickness and molecular length of FAS-13 and FAS-17, the results shown in Table 2 were obtained.

[0026]

[Table 2]

From these results, it is presumed that in FAS-17, molecules are integrated vertically to the substrate, and the integration rate is at a considerably high level. That is, a dense monomolecular film is formed. On the other hand, FAS-13 seems to be formed obliquely on the substrate, and the coverage is considered to be somewhat inferior to FAS-17. XPS confirmed this result.

The fluorinated alkylsilane monomolecular film forms a siloxane bond (Si-O-Si) between the fluorinated alkylsilane molecules and with silicon oxide, and is strongly bonded to the silicon substrate surface by a covalent bond. , Mechanical strength was strong.
Further, it was chemically very stable even when immersed in an acid, alkali or organic solvent.

(Example 2) In the same manner as in Example 1, the surface of the silicon substrate was first cleaned with ultraviolet light (wavelength 172 nm) to remove organic impurities to obtain a clean surface. Since the surface of the substrate is covered with a natural oxide film (SiO ₂ ), water vapor in the air is immediately adsorbed on the surface of the substrate, and the surface is covered with OH groups to become a hydrophilic surface. Next, FAS-17 was deposited on the hydrophilized silicon substrate by chemical vapor deposition at 100 ° C. for 2 hours to form a monomolecular film.

A light-shielding thin film of chromium was formed on quartz glass at a pitch of 5 μm and a pitch of 10 μm to form a photomask. A photomask was adhered to the surface of the silicon substrate, and ultraviolet light (wavelength: 172 nm) was irradiated through the mask. The irradiation intensity was 10 mW / cm ² and the irradiation time was 10 minutes. In the light irradiation region, the CC bond is broken by ultraviolet light, so that the fluoroalkylsilane monomolecular film is decomposed and removed.

It was confirmed by AFM and LFM that the monomolecular film was removed in the light irradiation area. From the results of the friction force by LFM, it was found that the substrate surface from which the monomolecular film had been removed was Si-OH. As a result, water-repellent regions having a surface energy of 16 mN / m and hydrophilic regions having a surface energy of 80 mN / m could be alternately formed at intervals of 5 μm.

Example 3 FAS-3 was deposited at 100 ° C. for 2 hours by chemical vapor deposition on the FAS-17 patterned silicon substrate in Example 2. From the AFM and LFM measurement results, it was confirmed that the monolayer of FAS-17 was left as it was, and the monolayer of FAS-3 was formed only in the removed region. It was possible to arbitrarily create hydrophilic and water-repellent regions, or regions with large and small friction on the silicon substrate.

Example 4 A glass substrate was exposed to oxygen plasma for cleaning and hydrophilization. Place a beaker containing tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane and a hydrophilic glass substrate in a stainless steel vacuum container, and then place the entire container in an electric furnace. Was. The molecular weight of the fluorinated alkylsilane is 510.36, 1.5 mmH
The boiling point in g is 86 ° C. When the pressure in the vacuum vessel was reduced to 10 Torr, the temperature was raised to 100 ° C., and the temperature was maintained for 10 minutes, the fluorosilane was evaporated, and chemical vapor deposition was performed on the substrate.

The surface energy calculated from the contact angle with water, methylene iodide and hexadecane was 25 mN / m, and that of Si-OH which did not form a monomolecular film was 75 mN / m. Although it is expected that the density of the monomolecular film is lower than that of Example 1, it has sufficient mechanical durability and chemical resistance, and can be used industrially as ordinary water / oil repellent treatment.

Example 5 A polyethylene film was first cleaned with ultraviolet light (wavelength 172 nm) to obtain a clean surface. Ultraviolet light was absorbed near the surface, and only the surface was hydrophilized, and the physical properties of the film itself were not changed. (Tridecafluoro-1,1,2,2-tetrahydrooctyl) trichlorosilane, (tridecafluoro
-1,1,2,2-tetrahydrooctyl) methyldichlorosilane and (tridecafluoro-1,1,2,2-tetrahydrooctyl) dimethylchlorosilane were prepared. The molecular weights are 481.54, 461.12, and 440.70, respectively, and the boiling points at 1 atm are 192-3 ° C, 189-90 ° C, and 189-91 ° C, respectively. A beaker containing each fluorinated alkyl silane and a hydrophilic polyethylene film were placed in a Teflon sealed container, and then the entire container was placed in an electric furnace. Raise the temperature to 80 ° C 1
Upon holding for a period of time, the fluorinated alkylsilane evaporated and was deposited on the film by chemical vapor deposition.

The surface energy of the film on which each of the fluoroalkylsilanes was deposited was calculated from the contact angles with water, methylene iodide, and hexadecane and found to be 25 mN / m, and no difference was observed. The polyethylene film surface (C-OH or C-OOH) that did not form a monomolecular film was 60 mN / m. Although the density of the monomolecular film is expected to be lower than that on the SiO2 of Example 1, it has sufficient mechanical durability and chemical resistance, and can be used industrially as ordinary water / oil repellent treatment.

(Example 6) The surface of a glass substrate on which an ITO transparent electrode was formed was irradiated with ultraviolet light (wavelength: 172 nm) for cleaning.
It was made hydrophilic. Tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane was jetted from an ink jet head and sprayed on the glass substrate with ITO in 10 picoliters at 140 micron intervals. The substrates were placed in a glass sealed container at intervals of 1 cm, and 20 substrates were stacked and placed horizontally. Raise the temperature in the sealed container to 180 ° C 2
When held for a while, all of the fluoroalkylsilane evaporates,
Chemical vapor deposition was performed on each substrate.

The formation of a monomolecular film was confirmed by AFM, LEM and XPS, and it was identified that the monomolecular film was exactly the same as FAS-13 in Example 1. When the surface energy was calculated from the contact angle with water, methylene iodide, and hexadecane, 20 mN / m
And an ITO surface that does not form a monomolecular film (In-OH or Sn-
OH) was 70 mN / m.

Example 7 Ultraviolet light was applied to the surface of a quartz glass substrate on which an aluminum electrode having a width of 1 micron was patterned.
(Wavelength: 172 nm) to remove organic impurities to obtain a clean surface. The surface of the aluminum electrode is a natural oxide film (Al ₂ O ₃ )
Therefore, water vapor in the atmosphere is immediately adsorbed on the substrate surface, and the surface is covered with OH groups to become a hydrophilic surface. 5 parts by weight of tridecafluoro-1,1,2,2-tetrahydrooctyltriaminosilane is dissolved in tetralin and sprayed from an ink jet head, and sprayed on the quartz glass substrate with the aluminum electrode in 10 picoliters at 70 micron intervals. did. Place the substrate in a closed glass container 1cm
At intervals, 20 sheets were stacked and placed horizontally. When the temperature in the closed vessel was raised to 180 ° C. and held for 2 hours, all of the fluoroalkylsilane was evaporated and chemical vapor deposition was performed on each substrate.

The formation of a monomolecular film on both the aluminum electrode and the quartz glass was confirmed by AFM, LEM and XPS, and it was identified that the monomolecular film was exactly the same as FAS-13 in Example 1.
The surface energy was calculated from the contact angles with water, methylene iodide, and hexadecane, and found to be 20 mN / m on both the aluminum electrode and the quartz glass.

Ultraviolet light (wavelength: 172 nm) was irradiated from the back surface of the quartz glass substrate on which the aluminum electrode was patterned. The irradiation intensity was 10 mW / cm ² and the irradiation time was 10 minutes. The monofluorinated alkylsilane monolayer on the aluminum electrode was maintained as it was, and only the monofluoroalkylsilane monolayer on the surface of the quartz crow was decomposed and removed.

The patterning substrate was immersed in an ethanol solution of 3-aminopropyltriethoxysilane for 30 minutes,
Heated at 80 ° C. for 1 hour. As a result, aminoalkylsilane was formed only on the quartz glass surface, and the surface became a stable hydrophilic surface. Water repellency was maintained only in a 1 micron wide area on the aluminum electrode.

Example 8 The surface of a silicon substrate was first washed with ultraviolet light (wavelength 172 nm) to make it hydrophilic, and then perfluorooctyltrimethoxysilane was placed in a vacuum container made of stainless steel. A beaker and a hydrophilic glass substrate were placed, and then the entire container was placed in an electric furnace. When the pressure in the vacuum vessel was reduced to 100 Torr, the temperature was raised to 100 ° C., and the temperature was maintained for 5 minutes, whereby the fluorosilane was evaporated, and chemical vapor deposition was performed on the substrate.

An electron beam was applied to an arbitrary position on the obtained monomolecular film of fluorinated alkylsilane to remove the monomolecular film with a width of 0.1 μm. 0.6 nm for monolayer
The patterning was very good with edge shape and dimensional accuracy.

On the patterned silicon substrate,
Trimethylchlorosilane was deposited for 1 hour at 80 ° C. under atmospheric pressure by chemical vapor deposition. The trimethylsilyl group was formed only in the removed portion, and a lipophilic and oleophobic region, or a region with large friction and a region with small friction could be arbitrarily created on the silicon substrate.

Example 9 The surface of a silicon substrate was first cleaned using ultraviolet light (wavelength: 172 nm) to remove organic impurities to obtain a clean surface. Since the surface of the substrate is covered with a natural oxide film (SiO ₂ ), water vapor in the air is immediately adsorbed on the surface of the substrate, and the surface is covered with OH groups to become a hydrophilic surface. Next, FAS-17 was deposited on the hydrophilized silicon substrate by chemical vapor deposition at 100 ° C. for 2 hours to form a monomolecular film.

A chrome light-shielding thin film of 0.3%
A pattern was formed with a micron width of 1 micron pitch to obtain a photomask. A photomask was adhered to the surface of the silicon substrate, and ultraviolet light (wavelength: 172 nm) was irradiated through the mask.
The irradiation intensity was 10 mW / cm ² and the irradiation time was 10 minutes. In the light irradiation region, the CC bond is broken by ultraviolet light, so that the fluoroalkylsilane monomolecular film is decomposed and removed.

It was confirmed by AFM and LFM that the monomolecular film was removed in the light irradiation area. From the results of the friction force by LFM, it was found that the substrate surface from which the monomolecular film had been removed was Si-OH. As a result, a water-repellent region having a surface energy of 16 mN / m and a hydrophilic region having a surface energy of 80 mN / m were formed alternately with submicron accuracy.

Example 10 The silicon substrate subjected to FAS-17 patterning in Example 9 was immersed in a 0.5% hydrofluoric acid etching solution. Since the native oxide film (SiO ₂ ) on the silicon surface has a thickness of 2 nm and an etching rate of 5 nm / min, the immersion time was 30 seconds. The FAS-17 monomolecular film was damaged by the etchant, and it took more than 10 minutes for the underlayer to be exposed, so that it functioned sufficiently as a resist film for lithography.

As a result of the etching, a natural oxide film on the silicon surface is formed in a pattern of 0.3 micron width and 1 micron pitch.
(SiO ₂ ) could be removed.

[0051]

As described above, according to the present invention, a method of self-assembling a dense monomolecular film on a substrate by a simple method can be provided. An organic monomolecular film could be formed on the surface of the substrate, which is not a special material such as gold but has a property generally observed to some extent. The productivity was high, and especially when the ink jet method was used, the use amount of the fluoroalkylsilane was minimized, and the efficiency was very good. Further, the present invention has provided a method of patterning an organic monomolecular film with high accuracy and a simple method. As a result, it was possible to arbitrarily create hydrophilic and water-repellent regions, or regions with large and small friction on the substrate. In addition, the patterned fluoroalkylsilane could be applied as a resist film for lithography.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a monomolecular surface of a fluorinated alkylsilane in Example 1 of the present invention.

FIG. 2 is a cross-sectional view illustrating an outline of a chemical vapor deposition apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a diagram showing the relationship between the deposition time of fluorinated alkylsilane and the film thickness in Example 1 of the present invention.

FIG. 4 is a diagram showing a measurement principle of an LEM in the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Teflon closed container 2 ... Beaker 3 ... Fluoroalkylsilane 4 ... Silicon substrate 5 ... Heater

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroyuki Sugimura 3-1 Meijo Housing, Kita-ku, Nagoya-shi, Aichi 9-609 F-term (reference) 2H096 AA30 BA09 BA13 CA01 CA03 CA17 CA20 EA02 FA04 HA23 4K030 AA04 AA06 AA09 CA04 CA07 DA03 EA01 FA10

Claims (11)

[Claims] 1. An organic method comprising: washing a substrate in advance by any method; hydrophilizing the surface thereof; and forming a monomolecular film of fluorinated alkylsilane on the substrate by a chemical vapor deposition method. A method for forming a monomolecular film. 2. The method for forming an organic monomolecular film according to claim 1, wherein the substrate is washed by ultraviolet or oxygen plasma treatment. 3. The method according to claim 1, wherein a monomolecular film of fluorinated alkylsilane is formed on a substrate by a chemical vapor deposition method using a silicon compound represented by the following general formula (I). The method for forming an organic monomolecular film according to the above. _{C n F 2n + 1 -C m} H 2m -Si-X 3 (I) ( wherein n represents an integer of 1 or more, m represents 0 and an integer of 1 or more, X is an alkoxy group or an amino group, or Represents a halogen atom, wherein X ₃ may be partially substituted with an alkyl group containing a hydrogen atom. 4. The method according to claim 1, wherein the chemical vapor deposition is performed under atmospheric pressure or 1 Torr.
The method for forming an organic monomolecular film according to claim 1, wherein the method is performed in a reduced pressure atmosphere close to the atmospheric pressure of r or less. 5. The method according to claim 4, wherein the chemical vapor deposition is performed at a temperature of 200 ° C. or less. 6. An appropriate amount of a silicon compound represented by the general formula (I) or a diluted solution of a solvent thereof is finely dispersed on a substrate in advance by an ink-jet method, and is evaporated to be chemically vapor-deposited on the entire surface of the substrate. The method for forming an organic monomolecular film according to any one of claims 1 to 5, wherein: 7. A method for patterning an organic monomolecular film, comprising irradiating ultraviolet light in an atmosphere containing oxygen to remove the monomolecular film of fluorinated alkylsilane. 8. A monomolecular film is removed by irradiating only a desired region with ultraviolet light using a mask.
The method for patterning an organic monomolecular film according to the above item. 9. A method for patterning an organic monomolecular film, comprising removing a monomolecular film of fluorinated alkylsilane using an electron beam. 10. The method for patterning an organic monomolecular film according to claim 7, wherein after removing the monomolecular film, a silicon compound containing no fluorine atom is adsorbed. 11. A lithography method characterized in that a monomolecular film of fluorinated alkylsilane left by patterning is used as an etching stopper as a resist film.