JPH04214880A - Organic monomolecular film accumulation method and chemical adsorbent used therein - Google Patents

Abstract

PURPOSE:To offer the accumulating method of a chemisorption monomolecular film regardless of the atmosphere and a chemisorption agent without causing a side reaction. CONSTITUTION:An org. molecule having a covalent bond forming group or a hydroxylating group is used. A monomolecular film is formed with the covalent bond forming group, substrate and chemical reaction through the covalent bond. The hydroxylating group is then substituted for a hydroxyl group by the oxidation with hydrogen peroxide or alkali treatment. The chemisorption agent is then subjected to a reaction, and a monomolecular film is easily and safely accumulated. No defect is caused even in the molecule by irradiation with a high-energy beam, and a safe chemisorption agent without the explosive reactivity like diborane is offered.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic monomolecular film, and more particularly to a method of accumulating an organic monomolecular film on an organic monomolecular film and a chemical adsorbent therefor.

0002

2. Description of the Related Art Conventional methods for forming organic monomolecular films include the Langmuir-Blodgett method and the chemisorption method.

[0003] In the Langmuir-Blodgett method, a linear hydrocarbon molecule with a hydrophilic group at the end is developed on the air-water interface, and the area occupied by the developed molecule at the air-water interface is minimized. This is a method of transferring onto an arbitrary substrate. Since one end of the linear hydrocarbon molecule is hydrophilic, the hydrophilic group of the molecule faces the water at the air-water interface. In order to minimize the area occupied by the molecules, one end of the air-water interface is generally pushed with a jig called a barrier, reducing the area of the interface where the molecules are expanded and increasing the density of the molecules. By this operation, a monomolecular film is formed in which the hydrophilic groups of the molecules are directed toward the water, and the linear hydrocarbon portions are erected against the water surface. A film obtained by transferring a film in this state to a substrate is called a Langmuir-Blodgett film. Further, by repeating the same operation, it becomes possible to accumulate a monomolecular film.

On the other hand, the chemisorption method utilizes the reaction between chemical bonding groups, such as hydrophilic ones, exposed on the substrate surface and active groups in hydrocarbon molecules to form a monomolecular film through chemical bonds. The monomolecular film obtained in this way is particularly called a chemisorption monomolecular film.

[0005]

[Problems to be Solved by the Invention] In the monomolecular film formed by the conventional Langmuir-Blodgett method, the bond with the substrate is van der Waals force or ionic bond, and there is a problem in the cumulative film formation. Bonds between membranes are also van der Waals forces or ionic bonds. In this type of bonding, the bonding energy between the substrate and the film, as well as between the films, is extremely weak, which has the serious drawback that, for example, during processing of the film, the monomolecular film may peel or dissolve, resulting in destruction of the film itself. Ta.

[0006] A chemical adsorption method was devised as a new method for forming a monomolecular film to solve this weak bonding force. In this method, since the hydrocarbon molecules constituting the monomolecular film and the substrate are chemically bonded, the monomolecular film maintains a bonding force sufficient to withstand processing after film formation.

[0007] One of the methods of accumulating a monomolecular film using chemisorption is a method in which the surface of the monomolecular film is changed into a chemically bonding group by irradiation with an electron beam, thereby making the surface of the monomolecular film capable of chemical adsorption. has been reported. However, this method using electron beam irradiation has the disadvantage that the irradiation energy is applied not only to the membrane surface but also to the inside of the membrane, and secondary reactions such as polymerization, crosslinking, or decomposition occur on the membrane surface and inside the membrane.

[0008] As another method for forming a cumulative monomolecular film formed by chemisorption, when the terminals of the hydrocarbon molecules constituting the monomolecular film are unsaturated bonds such as vinyl groups, There is a method that forms a cumulative film by utilizing the hydroxylization of the terminal group due to the cleavage reaction of the terminal unsaturated bond group by diborane. However, the diborane used in this method reacts explosively when it comes into contact with moist air, even at low temperatures, making it an extremely difficult chemical to handle. Therefore, its method of operation has been a challenge in industrialization.

[0009] Furthermore, there have been no new chemical adsorbents to improve the cumulative techniques of these chemical adsorption methods.

[0010] The present invention has been made to solve the conventional problem, and provides an organic monomolecular cumulative film having very strong bonds between the films, without causing any side reactions. ,
Another object of the present invention is to provide a single molecule accumulation method that does not require special attention to the atmosphere, and a chemical adsorbent used therein.

[0011]

[Means for Solving the Problems] The present invention includes a monomolecular film forming step of forming a monomolecular film on a substrate using monomolecular-forming hydrocarbon molecules, and oxidizing the monomolecular film with hydrogen peroxide. This is an organic monolayer accumulation method that includes a hydroxylization step in which the terminal end of a hydrocarbon molecule is replaced with a hydroxyl group, and a monolayer accumulation step in which a monolayer is accumulated with monolayer-forming hydrocarbon molecules, which solves the conventional problems. This is the solution.

0012

[Operation] The compound constituting the organic monomolecular film of the present invention has a covalent bond-forming group at one end and a hydroxyl group-forming group at the other end, at least in the monomolecular film immediately above the substrate. This covalent bond-forming group is a so-called chemisorbent group that forms a monomolecular film through covalent bonds with the substrate, and this covalent bond-forming group adsorbs between the substrate and the film through strong covalent bonds. Because there are
A monomolecular film with excellent film processability can be formed. In addition, the hydroxyl-forming group at the other end of the compound of the present invention is easily hydroxylized by hydrogen peroxide oxidation or alkali treatment, and this end is contacted with a compound having a covalent bond-forming group on the hydroxyl-formed monomolecule. By doing so, a monomolecular film is accumulated through covalent bonds between the films, and a strong monomolecular cumulative film can be formed.

[0013]

[Example] The substrate used in the present invention may be any substrate as long as the chemical adsorbent can form a covalent bond with the substrate, such as metal, silicon, glass, plastic, etc. . However, in order for the chemical adsorbent to form a covalent bond, a hydrophilic group must be exposed on the substrate surface. Examples include groups having hydrogen. Among them, hydroxyl groups, amino groups, and carboxyl groups are easily obtained by ordinary treatments, and hydroxyl groups are particularly preferred because of their high activity. Furthermore, in the case of a plastic substrate in which the proportion of hydrophilic groups exposed on the surface is low, the substrate is made hydrophilic in advance by a method such as electron beam irradiation in an oxygen or nitrogen atmosphere before use.

[0014] The molecules constituting at least the monomolecular film immediately above the substrate used in the present invention have a covalent bonding group and a hydroxyl forming group. Examples of this covalent bond-forming group include reactive silyl groups such as chlorosilyl group and lower alkoxysilyl group. Among these reactive silyl groups, a chlorosilyl group is preferable because it reacts even at room temperature and can easily form a monomolecular film. Note that the chlorosilyl group can be any trichlorosilyl group, dichlorosilyl group, or monochlorosilyl group, but S in cases other than trichlorosilyl group
The Si bond that does not participate in the bond between the i atom and the Cl atom bonds with an alkyl group, a lower alkoxy group, or a hydrogen atom.

[0015] Furthermore, examples of the hydroxyl group-forming group used in the present invention include organosilicon groups. By reacting this group with hydrogen peroxide, the C--Si bond is oxidized, the C--Si bond is cut, and a C--OH bond is formed. As a result, the second layer of chemisorbed monolayer and the first layer of chemisorbed monolayer accumulated on the C-OH bonded monolayer form a covalent bond (-C-O-Si-). This makes it possible to form a very strong film. Alternatively, in the case of a dimethylsilyl group (-Si(CH3)2H) having an Si-H bond, the alkali treatment oxidizes the Si-H bond and breaks the Si-H bond, resulting in Si
-OH bonds are formed. As a result, the second chemisorbed monomolecular film and the first chemisorbed monomolecular film accumulated on the Si-OH bonded monomolecular film are covalently bonded (-S
i-O-Si-), making it possible to form a very strong film.

That is, the chemical adsorbent used in the present invention has a general formula of SiX3-nYn group (n=1,2,
and Y is a halogen, an amino group, an alkylamino group, an alkyl group, an alkoxy group, an alkenyl group, an alkenyloxy group, an alkadienyl group, an alkadienyloxy group,
Indicates any of an alkynyl group, an alkynyloxy group, an alkadinyl group, or an alkadinyloxy group, and X and Y
are not the same group), for example, S
i(CH3)2F group, Si(CH3)F2 group, Si(C
H3)2Cl group, Si(CH3)Cl2 group, Si(CH
3) 2(NR2) group, Si(CH3)2(OR) group, S
i(CH3)(OR)2 groups or Si(CH3)2Ph
group (wherein R in the formula is a lower alkyl group, Ph is a phenyl ring), and the like.

Regarding the molecules constituting the monomolecular film of the present invention, in consideration of adsorption density, the molecules between the covalent bond-forming group and the hydroxyl group-forming group are preferably linear molecules.

In particular, a functional group (Z) expressing an arbitrary function is included between the linear carbon chains, that is, the general formula S
iX3-nYn-(CH2)p-(Z)r-(CH2)
q-SiClnX3-n (where n is an integer of 1 to 2,
m is an integer of 1 to 3, r is 0 or 1, p and q are non-negative integers, X is a lower alkyl group, Y is hydrogen, halogen,
Lower alkoxy group, lower alkylamino group, aryl group, pyridyl group, Z is alkenylene, alkynylene,
Phenylene, aminophenylene, alkylphenylene,
Phenylenevinylene, phenyleneethynylene, pyridynylene, pyridylvinylene, pyridylethynyl, chenylene, pyrrolinylene, pyridinopyridynylene, acene (i.e. fused polycyclic) skeleton, W is hydrogen, halogen, alkyl group, alkenyl group, alkadienyl group, Alkynyl group, alkoxy group, H-(CH2)p-(Z)r-(C
H2) q- group, silicon-containing alkyl group, silicon-containing alkenyl group, silicon-containing alkadienyl group, silicon-containing alkynyl group, S
iX3-nYn-(CH2)p-(Z)r-(CH2)
The use of adsorbents for chemically adsorbed monomolecular film accumulation represented by q-groups is extremely effective in producing functional thin films.

Specifically, SiX3-nYn- group includes, for example, Si(CH3)2F group, Si(CH3)F2 group, Si
(CH3)2Cl group, Si(CH3)Cl2 group, Si(
CH3)2(N(CH3)2) group, Si(CH3)2(
OCH3) group, Si(CH3)(OCH3)2 group, Si
(CH3)2Ph (where Ph is a phenyl ring) group, Si (
CH3)2H group, Si(CH3)H2 group, etc. In addition, Z can be, for example, the functional group shown below (Chemical formula 1), etc. Among these, when it has a linear unsaturated bond, if this unsaturated bond is polymerized after monomolecular film accumulation, it becomes stronger. This is preferable because a monomolecular cumulative film can be formed.

[0020]

[Chemical formula 1]

Furthermore, as the -SiClmW3-m group, for example, -SiCl3, -SiCl2CH3, -SiC
l2C2H5, -SiCl(CH3)2, -SiCl(
C2H5)2, -SiCl(CH=C(CH3)2)2
, -SiCl2(OCH3) etc., -SiCl((C
H2)q-(Z)r-(CH2)pH)2,-SiCl
((CH2)q-(Z)r-(CH2)pSiX3-n
Yn)2 and the like.

The chemical adsorbent mentioned above may be used as the uppermost layer of the organic monomolecular cumulative film of the present invention, but the terminal of the uppermost monomolecular film does not necessarily have to be a hydroxyl group.

Examples of the alkali source for the alkali treatment used in the present invention include inorganic bases such as KOH and NaOH, quaternary bases such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide.
Any organic base such as grade ammonium or piperidine can be used.

The method for accumulating an organic monomolecular film of the present invention and one embodiment of the chemical adsorbent therefor will be schematically explained step by step using FIGS. 1 to 7 below.

Example 1 As shown in FIG. 2, a silicon oxide film 2 is formed on a silicon substrate 1 on which an organic monomolecular film and a cumulative film are to be formed. The thickness of the silicon oxide film is 0.2 μm, and the size of the substrate is 30×70 mm. A large number of hydroxyl groups (OH groups) 3 are exposed on the surface of the silicon oxide film.

As shown in FIG. 3, the substrate 1 is immersed in a chemical adsorbent solution 4 that forms a monomolecular film.

The chemical adsorbents used in this example were (1):
H(CH3)2Si(CH2)18SiCl3(2):
F(CH3)2Si(CH2)18SiCl3(3):
F2(CH3)Si(CH2)18SiCl3(4):
Cl(CH3)2Si(CH2)18SiCl3(5)
:Cl2(CH3)Si(CH2)18SiCl3(6
):(CH3)2N(CH3)2Si(CH2)18S
iCl3 (7): H3CO(CH3)2Si(CH2)18Si
Cl3(8): (H3CO)2(CH3)Si(CH2
)18SiCl3 (9): Ph(CH3)2Si(CH2)18SiCl
There are 9 types of 3. That is, this molecule is a hydrocarbon molecule with a trichlorosilyl group at one end and a dimethylsilyl or monomethylsilyl group at the other end, and the number of carbon atoms in the straight chain hydrocarbon portion of this chemical adsorbent is 18. be.

Each chemical adsorbent was dissolved in a mixed solvent of 80% by weight of normal hexadecane, 12% by weight of chloroform, and 8% by weight of carbon tetrachloride to a concentration of 10mM to obtain chemical adsorbent solution 4. .

25 ml of each of these solutions was separately taken and one of the above-mentioned substrates 1 was immersed as shown in FIG. At this time,
The liquid temperature was 30° C., and the substrate 1 was immersed for 1 hour. Further, the atmosphere during dipping was a dry nitrogen atmosphere.

Typically, in the case of adsorbent (1), as shown in FIG. 4, by immersing the substrate 1 in a chemical adsorbent solution 4, the hydroxyl groups 3 exposed on the substrate surface and the end of the chemical adsorbent are removed. The trichlorosilyl group undergoes a dehydrochlorination reaction to form a covalent bond of Si--O, and a monomolecular film 5 made of linear hydrocarbon molecules, which is a chemical adsorbent, is formed on the substrate 1. On the surface of this monomolecular film 5, dimethylsilyl groups 6 at the ends of linear hydrocarbon molecules of the chemical adsorbent are uniformly arranged.

Next, the surface of the monomolecular film 5 formed by the chemisorption method is subjected to hydrogen peroxide oxidation as shown in FIG. The hydrogen peroxide oxidation reaction solution 7 is shown below (Table 1)
), potassium fluoride as a reaction accelerator was dissolved in methanol, potassium hydrogen carbonate was dissolved in tetrahydrofuran (hereinafter referred to as THF), and 30% hydrogen peroxide solution was added.

[0032]

[Table 1]

Further, hydrogen peroxide oxidation was carried out by the method shown below. After thorough stirring and dissolution at room temperature, the two solutions were mixed to create hydrogen peroxide oxidation reaction solution 7. The substrate 1 on which the monomolecular film 5 was formed was immersed in this reaction solution 7 for 10 hours at room temperature. By immersing the substrate 1 on which the monomolecular film is formed in the reaction solution 7, as shown in FIG.
The C-Si bond of the dimethylsilyl group at the terminal of the linear hydrocarbon molecule forming the monomolecular film was cut, and a hydroxyl group (OH group) 8 was formed at the terminal of the linear hydrocarbon molecule.

Next, as shown in FIG.
The chemically treated substrate 1 was again immersed in the chemical adsorbent solution 9 to form a cumulative film. As the chemical adsorbent solution 9, chemical adsorbents (1) to (9) each having a linear hydrocarbon molecule with a trichlorosilyl group at one end and a dimethylsilyl group or a monomethylsilyl group at the other end were used, as in the previous example. The organic solvent for dilution is the same mixed solvent as before, and its concentration, solution temperature, immersion time, and atmosphere are also the same as before. By soaking, as shown in Figure 1,
A cumulative film 10 made of linear hydrocarbon molecules was newly formed on the monomolecular film 5 formed on the substrate 1 via oxygen atoms.

FIG. 8 shows infrared absorption spectra before and after cumulative film formation when the chemical adsorbent (1) is used as a representative example of this example. The infrared absorption spectrum indicated by a in FIG. 8 is the state of the monomolecular film before accumulation, and the spectrum indicated by b in FIG. 8 is the state after accumulation. middle of the spectrum 2
925 cm-1 is an absorption caused by the antisymmetric stretching vibration of CH2, and 2850 cm-1 is an absorption caused by the symmetric stretching vibration of CH2. Since the number of CH2 is doubled before and after accumulation, the absorption due to the antisymmetric stretching vibration of CH2 in the infrared absorption spectrum and the absorption intensity due to the symmetric stretching vibration in the infrared absorption spectrum due to the accumulation process are also doubled. As expected, when comparing the absorption caused by CH2 in a and b in Fig. 8, both antisymmetric and symmetric stretching vibrations are almost twice as large, indicating that a cumulative film is indeed formed. .

[0036] Hereinafter, another example of the organic monomolecular film accumulation method of the present invention and the chemical adsorbent used therein will be described.
9 to 12 schematically for the case of chemical adsorbent
will be explained in order.

Example 2 A silicon substrate 1 was immersed in the chemical adsorbent solution (1) described in Example 1 to obtain a monomolecular film 5 having dimethylsilyl groups 6. Next, as shown in FIG. 9, the surface of the monomolecular film 5 formed by the chemical adsorption method is treated with an alkali treatment reaction liquid 11. This alkali treatment reaction solution 11 contains 1%
A treatment reaction was carried out using a tetramethylammonium hydroxide aqueous solution for about 10 minutes at room temperature. By immersing the substrate 1 on which the monomolecular film 5 is formed in the reaction solution 11, the ≡SiH bond of the dimethylsilyl group 6 at the terminal of the linear hydrocarbon molecule forming the monomolecular film 5 is severed, and as shown in FIG. As shown in Figure 3, a hydroxyl group (OH group) 8 was formed at the end of the linear hydrocarbon molecule.

Next, as shown in FIG. 11, the ends of the linear hydrocarbon molecules constituting the monomolecular film 5 have OH groups
The chemically treated substrate 1 was again immersed in the chemical adsorbent solution 9 to form a cumulative film. Note that as the chemical adsorbent solution used was one in which the terminal end of the linear hydrocarbon molecule was a trichlorosilyl group and the other terminal end was a dimethylsilyl group. Furthermore, the same mixed solvent as before was used as the organic solvent for dilution, and the concentration, solution temperature, immersion time, and atmosphere were also the same as before. By soaking for about 10 minutes, Figure 1
2, a cumulative film 10 made of linear hydrocarbon molecules is newly formed on the monomolecular film 5 formed on the substrate 1 via oxygen atoms of -Si-O-Si- bonds. Been formed.

FIG. 13 shows the infrared absorption spectra of the monomolecular cumulative film 10 obtained in this way before and after the cumulative film formation. However, the infrared absorption spectrum shown in FIG. 13(a) is for the monolayer film 5 before accumulation, and the spectrum shown in FIG. 13(b) is for the monolayer film 10 after accumulation. 29 in the spectrum
25 cm-1 is absorption due to antisymmetric stretching vibration of CH2, and 2850 cm-1 is absorption due to symmetric stretching vibration of CH2. Since the number of CH2 is doubled before and after accumulation, the absorption caused by antisymmetric stretching vibration of CH2 in the infrared absorption spectrum due to accumulation processing and the absorption intensity caused by symmetric stretching vibration are also doubled. However, in reality, (a) in Figure 13 and (
Comparing the absorption caused by CH2 with b), both the antisymmetric and symmetric stretching vibrations are almost twice as large, indicating that a cumulative film is certainly formed.

Although a silicon oxide film was formed on the substrate used in this example, when a silicon substrate is normally handled, a natural oxide film is immediately formed on the surface of the silicon substrate due to air oxidation. There may be cases where it is not necessary to provide a silicon oxide film. Furthermore, although a silicon substrate was used as the substrate in the above embodiments, it goes without saying that the organic monomolecular cumulative film of the present invention is not limited to silicon. Furthermore, materials and conditions such as chemical adsorbent, chemical adsorbent solution, hydrogen peroxide oxidation reaction liquid, alkali treatment reaction liquid, various reaction times and reaction temperatures are not limited to the above examples, and organic monomolecules It is selected depending on the required function of the cumulative film.

[0041]

[Effects of the Invention] The method of accumulating an organic monomolecular film and the chemical adsorbent therefor of the present invention are such that the bond between the films is a covalent bond, which could not be achieved in the conventional cumulative film of Langmuir-Blodjut. , it became possible to form an extremely strong film. Furthermore, compared to accumulation by electron beam irradiation, which is one of the accumulation methods used in conventional chemisorption methods, it is thought that there is no damage to the monomolecular film because a chemical reaction at room temperature is used. Further, it can be said that it is an ideal accumulation method without causing any side reactions. In addition, compared to the other accumulation method, which uses diborane, the accumulation method of the present invention does not require sufficient control of the atmosphere, allowing the reaction to be carried out safely, and causing no industrial problems. It can be said.

[Brief explanation of the drawing]

[Fig. 1] A cross-sectional view of a monomolecular cumulative film of an embodiment of the organic monomolecular film of the present invention.

FIG. 2 is a cross-sectional view of a substrate according to an embodiment of the present invention.

[Fig. 3] A cross-sectional view illustrating the chemical adsorption process of an example of the organic monomolecular film of the present invention.

FIG. 4: Cross-sectional view of an example of the organic monolayer of the present invention after formation of a chemically adsorbed monolayer

FIG. 5 is a cross-sectional view illustrating the hydrogen peroxide oxidation treatment step of an example of the organic monomolecular film of the present invention.

[Fig. 6] Cross-sectional view of an example of the organic monomolecular film of the present invention after hydrogen peroxide oxidation treatment

FIG. 7 is a cross-sectional view illustrating the accumulation process of an example of the organic monomolecular film of the present invention.

[Figure 8] Infrared absorption spectrum diagrams before and after accumulation in an example of the organic monomolecular film of the present invention

FIG. 9 is a cross-sectional view illustrating the alkali treatment step of another example of the organic monomolecular film of the present invention.

FIG. 10: Cross-sectional view of another example of the organic monomolecular film of the present invention after alkali treatment

FIG. 11 is a cross-sectional view illustrating the accumulation process of another example of the organic monolayer of the present invention.

FIG. 12 is a cross-sectional view of a monomolecular cumulative film of another embodiment of the organic monomolecular film of the present invention.

FIG. 13: Infrared absorption spectrum diagrams before and after accumulation in another example of the organic monolayer of the present invention

[Explanation of symbols]

1 Silicon substrate 2 Silicon oxide film 3 Hydroxyl group (OH group) 4. Chemical adsorbent solution 5 Monolayer 6 Dimethylsilyl group 7 Hydrogen peroxide oxidation reaction solution 8 Hydroxyl group (OH group) 9 Chemical adsorbent solution 10 Cumulative film 11 Alkaline treatment reaction solution

Claims (7)

[Claims] 1. A monomolecular film forming step of forming a monomolecular film on a substrate using monomolecular-forming hydrocarbon molecules, and oxidizing the monomolecular film with hydrogen peroxide to convert the ends of the hydrocarbon molecules into hydroxyl groups. 1. A method for accumulating an organic monolayer, comprising a hydroxyl substitution step and a monolayer accumulation step of accumulating a monolayer with monolayer-forming hydrocarbon molecules. 2. A monomolecular film forming step of forming a monomolecular film on a substrate with monomolecular-forming hydrocarbon molecules, and a hydroxyl group in which the monomolecular film is treated with an alkali and the ends of the hydrocarbon molecules are replaced with hydroxyl groups. 1. A method for accumulating an organic monomolecular film, the method comprising: a step of forming a monomolecular film, and a monomolecular film accumulation step of accumulating a monomolecular film with monomolecular film-forming hydrocarbon molecules. 3. The method for accumulating an organic monomolecular film according to claim 1, wherein any one of a hydroxyl group, an amino group, or a carboxyl group is exposed on the surface of the substrate. 4. At least the monomolecule-forming hydrocarbon molecule used in the monomolecule-forming step is a silane surfactant having a reactive silyl group at one end and an organosilicon group at the other end. The method for accumulating an organic monomolecular film according to claim 1 or 2. 5. The organosilicon group is a Si(CH3)2H group, a Si(CH3)2F group, a Si(CH3)F2 group, an Si
(CH3)2Cl group, Si(CH3)Cl2 group, Si(
CH3)2NR2 group, Si(CH3)OR group, Si(C
The organic monomolecule according to claim 4, characterized in that it is either a H3)(OR)2 group (wherein each R in the formula represents a lower alkyl group) or a Si(CH3)2Ph group. Membrane accumulation method. 6. The method for accumulating an organic monomolecular film according to claim 4, wherein the silane surfactant is a chlorosilane surfactant having a chlorosilane bond. Claim 7: General formula SiX3-nYn-(CH2)
p-(Z)r-(CH2)q-SiClmW3-m (where n is an integer of 1 to 2, m is an integer of 1 to 3, r is 0 or 1, p and q are non-negative integers , X is a lower alkyl group, Y is hydrogen, halogen, lower alkoxy group, lower alkylamino group, aryl group, pyridyl group, Z is alkenylene, alkynylene, phenylene, aminophenylene, alkylphenylene, phenylenevinylene, phenyleneethynylene, pyridylene , pyridylvinylene,
Pyridylethynyl, chenylene, pyrrolinylene, pyridinopyridenylene, acene (i.e. fused polycyclic) skeleton, W
is hydrogen, halogen, alkyl group, alkenyl group, alkadienyl group, alkynyl group, alkoxy group, H-(C
H2) p-(Z)r-(CH2)q- group, silicon-containing alkyl group, silicon-containing alkenyl group, silicon-containing alkadienyl group,
Silicon-containing alkynyl group, SiX3-nYn-(CH2)
A chemical adsorbent represented by p-(Z)r-(CH2)q- group).