JPH08124797A - Dielectric thin film, its manufacture, and capacitor - Google Patents

Abstract

PURPOSE: To obtain a dielectric thin film which is uniform in the nanometer level and has no electric pin holes, by chemically adsorbing, in order, two kinds of silicon compounds different in the length of molecular chain, on a specified substrate surface, and chemically coupling the adsorbed molecules to the substrate surface or chemically coupling the adsorbed molecules to each other. CONSTITUTION: After the surface of a glass substrate 11 is sufficiently cleaned, Al is evaporated on the surface to be 150nm thick, and a lower electrode 12 is formed. Chlorosilane based interface activator of long molecular chain containing six carbon fluoride chains is adsorbed on the surface by a chemical adsorption method, and a chemical adsorption molecular film 13 is formed. Chlorosilane based interface activator of short molecular chain is adsorbed on the film 13, and a chemical adsorption film 14 which is coupled to a monomolecular film via chemical bond is formed. By repeating processes from the chemical adsorption process to a rinsing process, a 4-molecular built-up film composed of two kinds of chemical adsorption is formed. On the surface of the 4-molecular built-up film, Al is evaporated to be 100nm thick, and an upper electrode is formed. Thereby a dielectric thin film wherein the thickness can be controlled to be uniform in the nanometer level, and pin holes are not present can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric thin film and its manufacturing method. In particular, the present invention relates to a dielectric film used for capacitors, display devices, molecular elements and the like.

[0002]

2. Description of the Related Art In recent years, along with the miniaturization of electronic devices and the like, there has been a rapid increase in the needs for light, thin, short and compact electronic components housed therein. Regarding dielectrics, there are many demands for thinning in various fields such as capacitors, magnetic heads, and display devices. A thin, strong mechanical strength, durable, pinholeless dielectric film is desired. There is.

As a conventional method for producing a thin film dielectric, vapor deposition, sputtering, CVD, spin coating, casting, etc. are generally used. However, as the film thickness changes from submicron to nanometer level, many pinholes are formed, It had a bad influence on various characteristics. Further, there is an LB film as a film whose thickness can be controlled at the nanometer level, but it was quite difficult to form a pinhole-free film.

Recently, as shown in Japanese Patent Publication No. Hei 3-143434, a silane-based surfactant is reacted on the electrode surface to chemically adsorb a siloxane-based monomolecular film, and a dielectric having a uniform thickness at the nanometer level. Methods have been proposed for providing (insulator) thin films.

[0005]

However, even if the manufacturing method is improved to increase the adsorption density or change the chemical structure of molecules to be adsorbed, the influence of the underlying layer forming the dielectric cannot be ignored. In reality, even if the dielectric is used as a monomolecular cumulative film, it is not possible to obtain a film having no pinhole, in particular, an electric pinhole.

In order to solve the above-mentioned prior art, the present invention provides a uniform dielectric thin film at the nanometer level, and
The purpose is to provide a film without electrical pinholes.

[0007]

In order to achieve the above object, the thin film dielectric of the first invention comprises at least two kinds of thin films, and these thin films are bonded through a chemical bond, and At least one of the thin films is a monomolecular film or a monomolecular cumulative film.

The method for producing a thin film dielectric of the second invention is different from the step of reacting one kind of compound on the surface of a substrate to form a monomolecular film and the compound on the monomolecular film. A step of reacting another compound to form a thin film so as to cover the monomolecular film.
It is characterized in that at least one cycle is repeated as a cycle.

The capacitor of the third invention is a capacitor in which an electrode is formed on at least one surface of a dielectric thin film, and the dielectric thin film is composed of at least two types of thin films. Each of the electrodes is bonded via a chemical bond and at least one of the thin films is
The type is a monomolecular film or a monomolecular cumulative film.

The above first, second and third inventions
In the above, the chemical bond is preferably a siloxane bond. Well
Also, the thin film is preferably a thin film formed by reacting a silicon compound.
Yes. Moreover, among the compounds formed by reacting with two kinds of thin films,
One is 0 carbon atoms having at least one reactive functional group.
It is a linear molecule from 7 to 7, and Y (SiY₂O)_nSiY₃
(However, n ≦ 3, n is an integer, Y is halogen or ar
Coxy group), the other is a linear molecule with 8 or more carbon atoms
And X_pY_3-pSi-R₁-(CZ₂)_n-R₂-SiX _qY
_3-q, Or R₃-R₁-(CZ₂)_n-R₂-SiX_qY
_3-q(However, 4 ≦ n ≦ 25; n is an integer, R₁, R₂Is-
(CH₂)₂-Or represents a substituent containing Si or O
R is good₃Is an unsaturated group or dimethyl
Ryl group, X is a substituent such as H or an alkyl group, and Y is a substituent.
Rogen or alkoxy group, Z is H or F, p and q are
0 or 1 or 2) is desirable.

[0011]

【Function】 It is known that the monomolecular film composed of linear molecules with 8 or more carbon atoms obtained by chemisorption reaction has the molecules oriented to the substrate surface (T. Ohtake et al, Lang
muir, Vol.8, No.9, 1992). Therefore, by using a monomolecular film composed of a linear molecule having 8 or more carbon atoms, it is possible to control the film thickness on the nanometer level by the molecular chain length.

According to the first and second inventions, the dielectric thin film is a monomolecular film composed of long molecular chains for controlling the film thickness at the nanometer level, and a thin film of short molecular chains is composed of long molecular chains. A film defect that occurs during the formation of a monolayer film consisting of, that is, a network-like molecular bond structure that closes the molecular level pinholes that are affected by the substrate surface etc. on the surface of the monolayer film. It is hard to receive and can be electrically pinhole free. In addition, since the combination of these two thin films makes it possible to obtain a defect-free film for each monomolecular film, by accumulating this dielectric thin film,
A dielectric thin film having a desired film thickness can be obtained.

Further, since these films are chemically bonded to each other, they can have high mechanical and thermal strength.

Further, according to the third aspect of the present invention, since the dielectric thin film and the electrode are chemically bonded, a capacitor having high adhesion strength and high reliability in electrical characteristics is provided. can do.

[0015]

[Examples] Conventionally, as a powerful one of thin film forming methods, especially monomolecular film forming methods, a substrate is dipped in a non-aqueous organic solvent in which surface-active molecules called a chemical adsorbent are dissolved to form a non-aqueous organic solvent. A chemisorption method in which a monomolecular film is formed by causing a chemical reaction in a solvent is known. The monomolecular film thus obtained is called a chemisorption monomolecular film.

Since the chemisorption monomolecular film is connected to the surface of the base material through a strong chemical bond, the chemisorption monomolecular film generally has an adhesive strength that does not cause peeling unless the surface of the substrate is scraped off.
In addition to such liquid phase adsorption, there is also a method of chemical adsorption in the gas phase.

The base material on which the chemical adsorbent is fixed is not particularly limited as long as it can be coated with the chemical adsorption film. Any surface group having at least one functional group selected from a hydroxyl group, a carboxyl group, a sulfonic acid group, a sulfinic acid group, a phosphoric acid group, a phosphorous acid group, a thiol group, and an amino group may be used.

The present invention uses a surface active agent as a dielectric for capacitors, display devices, etc., and as an interlayer insulating film for integrated circuits, molecular elements, etc., and uses a chemical adsorption method to produce pinhole-free excellent dielectrics on the substrate surface. It is characterized by forming a thin film.

That is, two kinds of silicon compounds having different molecular chain lengths are sequentially chemisorbed on a predetermined substrate surface, and the base material surface and the adsorbed molecules and the adsorbed molecules are chemically bonded to each other to obtain at least one kind of carbon number. 2 of a monomolecular film of a long molecular chain composed of 6 or more linear molecules and a thin film composed of a molecule of a short molecular chain of 0 to 5 carbon atoms having at least one reactive functional group.
It is characterized by forming a layered structure.

For example, a thin-film metal electrode is prepared, and the electrode is first placed in a non-aqueous solvent in which a long-chain fluorocarbon surfactant containing halosilyl groups or alkoxyl groups at both ends of the molecule is mixed. Upon contact, the hydroxyl group on the electrode surface reacts with the halosilyl group at one end of the surfactant to immobilize the surfactant on the electrode surface. After removing the unreacted excess surfactant remaining on the electrode using a non-aqueous organic solvent, it is reacted with water to form a long-chain surfactant containing a plurality of silanol groups on the electrode. Form a monolayer. Next, a hydroxyl group on the surface of the adsorption film of a long molecular chain chemically adsorbed on the electrode surface by contacting with a non-aqueous solvent mixed with a silicon surfactant of a short molecular chain and a silicon surfactant of a short chain molecule The surfactant having a short molecular chain is fixed by reacting with the halosilyl group or the alkoxysilyl group at one end. Then, after using a non-aqueous organic solvent to wash and remove the excess surfactant remaining on the electrode, it is reacted with water to form a monomolecular film of the surfactant containing a plurality of silanol groups on the electrode. . The dielectric thin film is formed by repeating these two steps at least once.

At this time, a halosilyl group, or
An alkoxysilyl group as a fluorocarbon surfactant of the long molecular chains containing a molecular _{end, X p Y 3-p Si} -R 1 - (C
_{F 2) n -R 2 -SiX q} Y 3-q ( However, 4 ≦ n ≦ 25;
n is an integer, R ₁ and R _{2 each} represents an alkyl group or a substituent containing Si or O, X is not necessary, X is a substituent such as H or an alkyl group, Y is a halogen, an alkoxy group,
It is convenient to use 0 or 1 or 2) for p and q.

In the step of forming a chemisorption monolayer having a long molecular chain, a non-aqueous system in which a surfactant having a halosilyl group or an alkoxysilyl group at one end and a reactive functional group at one end is mixed is used. By contacting with a solvent, a hydroxyl group on the electrode surface and a halosilyl group at one end of the fluorocarbon-based surfactant or an alkoxylysyl group are reacted to fix the surfactant on the electrode surface, and a non-aqueous organic solvent is used. After the excess unreacted surfactant remaining on the electrode is removed by washing, it is reacted with water to form a monomolecular film of the surfactant containing a plurality of silanol groups on the electrode. After that, the surface of the monomolecular film is treated with a chemical reagent, or plasma treatment is performed in a reactive gas, or an energy beam is irradiated in the reactive gas to change the reactive functional group on the electrode surface to the halosilyl group. It is also possible to change it to an active group.

At this time, a halosilyl group, or
As a surfactant having a plurality of alkoxysilyl groups at one end and a reactive functional group at the other end, R ₃ -R _1- (C
_{F 2) n -R 2 -SiX p} Y 3-p, R 1 -R 2 - (CF 2) n -
_{R 3 -SiX p (OA) 3} -p ( provided that, 4 ≦ n ≦ 25; n
Is an integer, R ₁ and R _{2 each} represent-(CH ₂ ) ₂ -or a substituent containing Si or O, but R ₃ is an unsaturated group or a dimethylsilyl group, and X is H or an alkyl group. Conveniently, a substituent, Y is halogen, an alkoxy group, and p is 0 or 1 or 2).

Examples of the silicon-based surfactant having a short molecular chain include SiY ₄ , SiHY ₃ , and SiH.
₂ Y ₂ , Y (SiY ₂ O) _n SiY ₃ (where n ≦ 3; n
Is an integer, Y is a halogen, an alkoxy group) and the like.

As the non-aqueous solvent used for chemisorption, for example, cyclohexane, n-hexadecane, toluene, xylene, dicyclohexyl, carbon tetrachloride, chloroform, etc. may be used alone or in combination of two or more. In the case of a silane-based surfactant other than a halosilane-based surfactant, methyl alcohol, ethyl alcohol, etc. can be applied in addition to this.

Although the halosilyl group and the alkoxysilyl group are used as the reactive functional groups of the surfactant, the chlorosilyl group gives better results when the reactivity is taken into consideration.

Next, specific examples of the dielectric thin film of the present invention will be described. (Embodiment 1) FIG. 1 is a schematic sectional view showing a manufacturing process when a dielectric thin film in Embodiment 1 of the present invention is used as an insulating film of a capacitor.

Reference numeral 11 is a glass substrate, 12 is a lower electrode vapor-deposited on the glass substrate 11, 13 is a chemisorption single molecule consisting of a long molecular chain, and 14 is a chemisorption film consisting of a short molecular chain.

First, after thoroughly cleaning the surface of the glass substrate 11, Al was pattern-deposited in a vacuum of 150 nm to form a lower electrode 12. The glass substrate 11 was taken out into the air and the surface of the lower electrode 12 was oxidized to form a thin natural oxide film. Then, after passing the glass substrate 11 into pure water,
It was dried sufficiently to form hydroxyl groups on the surface of the lower electrode 12 (FIG. 1 (a)).

Next, the fluorocarbon chain was converted into 6 by the chemisorption method.
A chlorosilane-based surfactant having a long molecular chain containing a single molecule is adsorbed to form the chemisorption monomolecular film 13.

The chemical adsorbent is Cl ₃ Si-(CH ₂ ) _2-.
(CF ₂ ) _6- (CH ₂ ) _2- SiCl ₃ is used, and 2 wt%
80 wt% hexadecane dissolved at a concentration of 12 wt%
When a carbon tetrachloride, 8 wt% chloroform solution was prepared and the glass substrate 11 was immersed for 2 hours, a natural oxide film existed on the surface of the lower electrode and a large amount of hydroxyl groups were contained, so chlorosilyl (-SiCl) A SiCl group and a hydroxyl group of any one of the substances containing a plurality of groups at both ends of the molecule react with each other to cause a dehydrochlorination reaction, and the entire surface of the electrode (Chemical formula 1)
The bond shown in was generated.

[0032]

Embedded image

Then, after further washing with an organic solvent to remove excess surfactant remaining on the electrode surface and washing with water, the siloxane-based monomolecular film 13 represented by the chemical formula (2) chemically reacts with the lower electrode surface. Approximately 1 when bound (covalently bound)
It was possible to form with a film thickness of 5 Å (Fig. 1
(B)).

[0034]

Embedded image

Next, a chemisorptive film 14 is formed by adsorbing a chlorosilane-based surfactant having a short molecular chain on the monomolecular film formed on the lower electrode and is bonded to the monomolecular film through a chemical bond. Form.

SiCl ₄ was used as the chemical adsorbent, and 2 wt.
When a chloroform solution dissolved at a concentration of 10% is prepared and the glass substrate 11 is immersed for 1 hour, many hydroxyl groups are formed on the surface of the siloxane-based monomolecular film 13 on the lower electrode. (-SiCl)
The group reacts with the hydroxyl group to cause a dehydrochlorination reaction, and the bonds shown in (Chemical Formula 2) and (Chemical Formula 3) are formed over the entire surface of the electrode.

[0037]

Embedded image

[0038]

[Chemical 4]

Then, after further washing with an organic solvent to remove excess surfactant remaining on the electrode surface and washing with water, chemical adsorption consisting of short molecular chains represented by (Chemical Formula 5) or (Chemical Formula 6) The film 14 could be formed in a state of being chemically bonded (covalently bonded) to the surface of the monomolecular film having long molecular chains on the lower electrode (Fig. 1).
(C)).

[0040]

Embedded image

[0041]

[Chemical 6]

In this way, the chemisorption process to the water washing process were repeated once again to prepare a four-molecule cumulative film consisting of two types of chemisorptive films.

On the surface of the obtained four-molecule cumulative film,
Al was pattern-deposited to a thickness of 100 nm to form an upper electrode. When the electrical characteristics of this parallel plate type capacitor were evaluated, the electrode area was 2 mmφ and the capacitance was 5 to 8 nF.
Met. In addition, the leakage current is 1 × at the measurement voltage of 2V.
It was 10 ^-10 A, the breakdown voltage was 7 V, and it was found that the dielectric thin film was electrically dense.

(Embodiment 2) FIG. 2 is a schematic sectional view showing a manufacturing process when a dielectric thin film in Embodiment 2 of the present invention is used as an insulating film of a capacitor.

Reference numeral 21 is a glass substrate, 22 is a lower electrode deposited on the glass substrate 21, 23 is a chemisorption monomolecular film consisting of long molecular chains, and 24 is a chemisorption film consisting of short molecular chains.

As in Example 1, after the surface of the glass substrate 21 was thoroughly washed, Al was pattern-deposited in a vacuum of 150 nm to form the lower electrode 22. The glass substrate 21 is taken out into the air and the surface of the lower electrode 22 is oxidized to form a thin natural oxide film. Then, the glass substrate 21 was passed through pure water and then sufficiently dried to form hydroxyl groups on the surface of the lower electrode 22 (FIG. 2A).

Next, a low molecular chain chlorosilane-based surfactant is adsorbed on the lower electrode to form a chemical adsorption film 24 of the chlorosilane-based surfactant.

SiCl ₄ was used as the chemical adsorbent, and 2 wt.
When a chloroform solution dissolved at a concentration of 10% is prepared and the glass substrate 21 is immersed for 1 hour, a lot of hydroxyl groups are contained on the lower electrode 22, so that the chlorosilyl (-SiCl) group reacts with the hydroxyl group. The dehydrochlorination reaction occurs and the bonds shown in (Chemical Formula 3) and (Chemical Formula 4) are generated over the entire surface of the electrode.

Then, the chemical adsorption monomolecular film 2 represented by (Chemical Formula 5) or (Chemical Formula 6) is obtained by further thoroughly washing with an organic solvent to remove the surplus surfactant remaining on the electrode surface and washing with water.
4 was chemically bonded (covalently bonded) to the lower electrode (FIG. 2 (b)).

Next, a chlorosilane-based surfactant containing 6 fluorocarbon chains is adsorbed on the chemisorption film 24 by a chemisorption method to form a chemisorption monomolecular film 23 of the chlorosilane-based surfactant. .

The chemical adsorbent is Cl ₃ Si-(CH ₂ ) _2-.
(CF ₂ ) _6- (CH ₂ ) _2- SiCl ₃ is used, and 2 wt%
80 wt% hexadecane dissolved at a concentration of 12 wt%
When a carbon tetrachloride, 8 wt% chloroform solution is prepared and the glass substrate 21 is immersed for 2 hours, a large number of hydroxyl groups are present on the surface of the chemisorption monomolecular film 24 on the lower electrode, so that a chlorosilyl (-SiCl) group is formed. The SiCl group and the hydroxyl group of one of the substances contained at both ends of the molecule react with each other to cause a dehydrochlorination reaction, and the bond shown in Chemical formula 1 is generated over the entire surface of the monomolecular film on the electrode surface.

Then, after further washing with an organic solvent to remove the surplus surfactant remaining on the electrode surface and washing with water, the chemisorption monomolecular film 23 represented by the chemical formula (2) is chemically formed on the lower electrode. A film having a film thickness of about 15 angstroms was formed in a state of being chemically bonded (covalently bonded) to the surface of the adsorption film 24 (FIG. 2 (c)).

Further, the low molecular chain chlorosilane type surfactant is again adsorbed on the chemisorption monomolecular film 23 formed on the lower electrode to form the chemisorption film 24.

SiCl ₄ was used as the chemical adsorbent, and 2 wt.
When a chloroform solution dissolved at a concentration of 10% is prepared and the glass substrate 21 is immersed for 1 hour, a large number of hydroxyl groups are formed on the surface of the chemisorption monomolecular film 24 on the lower electrode. The (-SiCl) group and the hydroxyl group react to cause a dehydrochlorination reaction, and the bond shown in (Chemical Formula 3) or (Chemical Formula 4) is generated over the entire surface of the electrode.

Then, the chemical adsorption monomolecular film 2 represented by (Chemical Formula 5) or (Chemical Formula 6) is obtained by further thoroughly washing with an organic solvent to remove the surplus surfactant remaining on the electrode surface and washing with water.
4 could be formed in a state of being chemically bonded (covalently bonded) to the surface of the monomolecular film having long chain molecules on the lower electrode (FIG. 2 (d)).

In this way, the steps from the chemical adsorption step to the water washing step are repeated once again and the long molecular chain and short molecular chain
Five kinds of films were accumulated by accumulating various kinds of films (Fig. 2).
(E)).

On the surface of the obtained 5 molecule cumulative film, Example 1 was applied.
In the same manner as above, Al is pattern-deposited with a thickness of 100 nm,
The upper electrode was used. When the electrical characteristics of this parallel plate type capacitor were evaluated, the electrode area was 2 mmφ and the electrostatic capacity was 3 to 6 nF. The leakage current was 4 × 10 ⁻¹⁰ A at a measurement voltage of 2 V and the dielectric breakdown voltage was 7.3 V, which was obtained with a dielectric thin film having a considerably high electrical performance. .

(Embodiment 3) FIG. 3 is a schematic cross-sectional view in the case where the dielectric thin film in Embodiment 3 of the present invention is used as an insulating film of a capacitor. Reference numeral 31 is a glass substrate, 32 is a lower electrode deposited on the glass substrate 31, and 36 is a fluorocarbon-based chemisorption monomolecular accumulated film.

After accumulating a 5-layer monolayer in Example 2, a substance having a plurality of chlorosilane groups at one end and carbon trifluoride at the other end, for example, F ₃ C- (CF ₂ ) ₇ −
(CH ₂ ) ₂ -SiCl ₃ was used to prepare 80 wt% hexadecane (toluene, xylene, dicyclohexyl, etc.) dissolved in a concentration of about 2 wt%, 12 wt% carbon tetrachloride, 8 wt% chloroform solution, and the cumulative film When the electrode prepared in (1) is dipped for 2 hours, the surface of the cumulative film contains a large number of hydroxyl groups. Therefore, one end contains a plurality of chlorosilyl groups and the other end is replaced with carbon trifluoride. The hydroxyl groups react to cause a dehydrochlorination reaction, and the bond shown in (Chemical Formula 7) is generated over the entire surface of the electrode.

[0060]

[Chemical 7]

Therefore, if the surface is covered with a fluorocarbon group and the surface is covered with a fluorocarbon group, the fluorocarbon-based chemisorption single molecule having an extremely high adhesion strength is obtained by further thoroughly washing the surface of the electrode with an organic solvent. A cumulative film 36 could be produced (Fig. 3).

Example 1 was applied to the surface of the obtained monomolecular cumulative film.
In the same manner as above, Al is pattern-deposited with a thickness of 100 nm,
The upper electrode was used. When the electrical characteristics of this parallel plate type capacitor were evaluated, the electrode area was 2 mmφ and the electrostatic capacity was 2 to 4 nF. The leakage current was 6 × 10 ⁻¹¹ A at a measurement voltage of 2 V, and the dielectric breakdown voltage was 7.6 V, which was obtained with a dielectric thin film having a considerably high electrical performance.

In the above Examples 1, 2 and 3, Cl
₃Si- (CH₂)₂− (CF₂)₆-(CH₂)₂-SiC
l₃And SiCl_FourAnd F₃C- (CF₂)₇-(CH₂)₂-S
iCl₃Was used, but with other chlorosilane-based surfactants
Then Cl₃Si- (CH₂)₂− (CF₂)₈-(CH₂)₂
-SiCl₃, Cl (CH₃)₂Si- (CH₂)₂− (C
F₂)₆-(CH₂)₂-SiCl₃, Cl (CH₃)₂Si
-(CH₂)₂− (CF₂) ₈-(CH₂)₂-SiCl₃,
Cl₃Si- (CH₂)₂− (CF₂)₆-(CH₂)₂-S
i (CH₃)₂Cl, Cl₃Si- (CH₂)₂− (CF₂)
₈-(CH₂)₂-Si (CH₃)₂Cl or Si
HCl₂, Cl₃SiOSiCl₃, Cl (SiCl₂O)
₂SiCl₃, Or F₃C- (CF₂)₉-(CH₂)
₂-SiCl ₃, F₃C- (CF₂)_Five-(CH₂)₂-Si
Cl₃, CF₃CH₂O (CH₂)_FifteenSiCl₃, CF₃(C
H₂)₂Si (CH₃)₂(CH₂)_FifteenSiCl₃, CF
₃(CF₂) _Four(CH₂)₂Si (CH₃)₂(CH₂)₉Si
Cl₃, CF₃COO (CH₂)_FifteenSiCl₃Etc. are available
You.

(Embodiment 4) FIG. 4 is a schematic sectional view showing a manufacturing process when a dielectric thin film of Embodiment 4 of the present invention is used as an insulating film of a capacitor.

41 is a glass substrate, 42 is a lower electrode deposited on the glass substrate 41, 43 is a chemisorption monomolecular film consisting of long molecular chains, 44 is a chemisorption film consisting of short molecular chains, 45 Is a chemisorption monomolecular cumulative film.

First, after thoroughly cleaning the surface of the glass substrate 41, Al was pattern-deposited in a vacuum of 150 nm to form a lower electrode 42. The glass substrate 41 is taken out into the atmosphere and the surface of the lower electrode 42 is oxidized to form a thin natural oxide film. Then, after passing the glass substrate 41 in pure water,
It was dried sufficiently to form hydroxyl groups on the surface of the lower electrode 42 (FIG. 4A).

Next, a chlorosilane-based surfactant containing a vinyl group is adsorbed at one end by a chemical adsorption method to form a single molecule or a plurality of monomolecular film-shaped dielectric thin films 43 made of the chlorosilane-based surfactant. .

The chemical adsorbent is CH ₂ ═CH— (CF ₂ ) ₆
- (CH ₂₎ using ₂ -SiCl _3, 2 wt% of the concentration of 80 wt% hexadecane dissolved in, 12 wt% carbon tetrachloride, to prepare an 8 wt% chloroform solution and immersing the glass substrate 41 of the 2 hours, the lower electrode Since there is a natural oxide film on the surface of and it contains a lot of hydroxyl groups,
The SiCl group of a substance containing a vinyl group at one end reacts with the hydroxyl group to cause a dehydrochlorination reaction, and the entire surface of the electrode (Chemical formula 8)
The bond shown in Fig. 4 was generated (Fig. 4 (b)).

[0069]

Embedded image

Therefore, the surface of the electrode is further washed thoroughly with an organic solvent to remove the surplus surfactant, and then an energy beam (electron beam, ion beam, gamma ray, ultraviolet ray) is irradiated (electron beam) in a reactive gas atmosphere. In the case of a line, when irradiated with about 5 Mrad in air), (Chemical formula 9), (Chemical formula 1)
0), a monomolecular film 4 containing the molecules represented by (Chemical Formula 11)
3 was formed in a state of being chemically bonded (covalently bonded) to the surface of the lower electrode (FIG. 4 (c)).

[0071]

[Chemical 9]

[0072]

[Chemical 10]

[0073]

[Chemical 11]

Furthermore, the same steps are repeated again,
The monomolecular film 43 was formed on the monomolecular film 43 to form a chemisorption monomolecular cumulative film 45 (FIG. 4 (d)).

Next, a chlorosilane-based surfactant having a low molecular chain is further adsorbed on the chemisorption single molecule accumulating film 45 formed on the lower electrode to form a chemisorption film 44.

Cl ₃ SiOSiCl ₃ was used as a chemical adsorbent, a chloroform solution prepared by dissolving it at a concentration of 2 wt% was prepared, and the glass substrate 41 was immersed for 1 hour. Since many hydroxyl groups, amino groups, etc. are formed on the surface, one or more chlorosilyl (-SiCl) groups react with hydroxyl groups, amino groups, etc. to cause dehydrochlorination reaction, and the entire surface of the electrode (Chemical Formula 2)
And the bond shown in (Chemical Formula 3) is generated.

Then, the chemical adsorption monomolecular film 4 represented by (Chemical Formula 5) or (Chemical Formula 6) is obtained by further thoroughly washing with an organic solvent to remove the surplus surfactant remaining on the electrode surface and washing with water.
4 could be formed in a state of being chemically bonded (covalently bonded) to the surface of the monomolecular film having long-chain molecules on the lower electrode (FIG. 4 (e)).

On the surface of the obtained trimolecular accumulation film, further,
Al was pattern-deposited to a thickness of 100 nm to form an upper electrode. When the electrical characteristics of this parallel plate type capacitor were evaluated, the electrode area was 2 mmφ and the electrostatic capacity was 5 nF. The leakage current is 8 × 10 at a measurement voltage of 2V.
^The dielectric breakdown voltage was ^-10 A and the breakdown voltage was 6.5 V.

(Example 5) With the same structure and manufacturing method as in Example 1, a chemical thin adsorbent was replaced with an alkoxysilyl group to prepare a dielectric thin film for an insulating film of a capacitor.

As the chemical adsorbent, (CH ₃ O) ₃ Si- (C
_{H 2) 2 - (CF 2} ) 6 - (CH 2) was used ₂ -Si (OCH _{3) 3.}

99.5 wt% melted at a concentration of 2 wt%
Example 1 was prepared by preparing a 0.5 wt% sulfuric acid solution of ethanol.
Similarly, when the glass substrate is immersed for 2 hours, a natural oxide film exists on the surface of the lower electrode on the glass substrate and contains a lot of hydroxyl groups, so methoxysilyl (-Si
One of the substances containing a plurality of (OCH ₃ ) ₃ ) groups at both ends of the molecule reacts with the Si (OCH ₃ ) ₃ ) group and the hydroxyl group to cause a dealcoholization reaction, which is shown in (Chemical Formula 12) over the entire electrode surface. A bond has been generated.

[0082]

[Chemical 12]

Therefore, the surface active agent was thoroughly washed with an organic solvent to remove the surplus surfactant remaining on the electrode surface, and after washing with water,
When heated at 85 ° C. for 1 hour, the siloxane-based monomolecular film 53 represented by (Chemical Formula 13) could be formed with a film thickness of about 15 Å in a state of being chemically bonded (covalently bonded) to the surface of the lower electrode.

[0084]

[Chemical 13]

Next, a short molecular chain alkoxysilane surfactant is adsorbed on the monomolecular film formed on the lower electrode to form a chemical adsorption film bonded to the monomolecular film through a chemical bond. Form.

Si (C ₂ H ₅ O) ₄ was used as the chemical adsorbent, and a solution of 99.5 wt% ethanol and 0.5 wt% sulfuric acid dissolved at a concentration of 2 wt% was prepared. When soaked for a long time, since many hydroxyl groups are formed on the surface of the siloxane-based monomolecular film 53 on the lower electrode, one or more ethoxysilyl (—Si (OC ₂ H ₅ ))
The group reacts with the hydroxyl group to cause dealcoholization reaction, and the bond shown in (Chemical formula 14) or (Chemical formula 15) is generated over the entire surface of the electrode.

[0087]

Embedded image

[0088]

[Chemical 15]

Therefore, the surface of the electrode was further washed thoroughly with an organic solvent to remove excess surfactant, and after washing with water, 8
When heated at 5 degrees for 1 hour, the chemisorption film consisting of short molecular chains represented by (Chemical formula 5) and (Chemical formula 6) chemically bonded (covalently bonds) to the surface of the monomolecular film having the long molecular chain on the lower electrode. It could be formed in the state.

In this way, washing from the chemical adsorption step with water
The heating process was repeated once again to prepare a four-molecule cumulative film composed of two types of chemisorption films.

On the surface of the obtained four-molecule cumulative film,
Al was pattern-deposited to a thickness of 100 nm to form an upper electrode. When the electrical characteristics of this parallel plate type capacitor were evaluated, the electrode area was 2 mmφ and the capacitance was 4 to 8 nF.
Met. Also, the leakage current is 7 × at a measurement voltage of 2V.
The dielectric breakdown voltage was 10 ⁻⁹ A and the dielectric breakdown voltage was 6.4 V, and it was found that the dielectric thin film was substantially the same as the dielectric thin film prepared in Example 1 and was electrically dense.

In the examples, a chlorosilane-based surfactant having a fluorine-based long molecular chain was used, but it goes without saying that the same result can be obtained with a hydrocarbon-based surfactant.

In Examples 1, 2, 3, and 4, SiCl
I used a surfactant with a group, but other halogens such as
The same result is obtained with the SiBr group.

The thin film formed of short molecular chains is not limited to the chemical adsorption film, but is limited to a monomolecular film composed of another long molecular chain or a film chemically bonded to the monomolecular accumulated film.

The monomolecular film composed of long molecular chains is not limited to the chemisorption monomolecular film, and the same result can be obtained as long as the monomolecular film is formed by chemical bonding with another thin film.

Further, in the embodiment, the monomolecular film has 1 carbon atom.
Although 0 was used, if the number of carbon atoms is 7 or less, it becomes difficult to control the film thickness at the nanometer level because molecular orientation is difficult. When the carbon number exceeds 25, it is difficult to obtain the material and the workability is deteriorated. Therefore, the carbon number is preferably 8 to 24.
Further, when the carbon number of the thin film exceeds 7, the effect of compensating for the defects of the monomolecular film is lost, so that the carbon number is preferably 0 to 7.

Further, although an Al vapor deposition electrode was used as an electrode in the examples, it is not limited to this as long as it is a metal on which an oxide film is formed on the surface.

Further, the dielectric thin film of the present invention has been described in the examples as the electrical density as a capacitor structure.
Since the monolayers are chemically bonded to each other, or the substrate and the monolayer are chemically bonded, it is clear that they are mechanically and electrically excellent dielectric thin films. Clearly, it can be used for dielectric films and insulating films.

[0099]

As described above, according to the present invention, a dielectric thin film capable of controlling a uniform thickness on the nanometer level, electrically pinhole-less, and excellent in adhesion strength is prepared. Can be provided to.

Furthermore, when this dielectric thin film is used, since the dielectric thickness is uniform on the molecular order, there is little variation in capacitance, leakage current is extremely small, and a highly durable capacitor with high durability is obtained. It can be obtained and has great industrial value.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view in which a substrate surface is enlarged to a molecular level, showing a manufacturing process in a first embodiment when a dielectric thin film of the present invention is used as a capacitor insulating film.

FIG. 2 is a schematic cross-sectional view in which a substrate surface is enlarged to a molecular level, showing a manufacturing process in a second embodiment when the dielectric thin film of the present invention is used as an insulating film of a capacitor.

FIG. 3 is a schematic cross-sectional view in which the substrate surface in the third embodiment in which the dielectric thin film of the present invention is used as an insulating film of a capacitor is enlarged to a molecular level.

FIG. 4 is a schematic cross-sectional view in which a substrate surface is enlarged to a molecular level, showing a manufacturing process in a fourth example when the dielectric thin film of the present invention is used as an insulating film of a capacitor.

[Explanation of symbols]

 11, 21, 31, 41 Glass substrate 12, 22, 32, 42 Lower electrode 13, 23, 43 Chemisorption monomolecular film consisting of long molecular chains 14, 24, 44 Chemisorption film consisting of short molecular chains 36 Fluorocarbon -Based chemisorption monomolecular cumulative film 45 Chemisorption monomolecular cumulative film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mamoru Soga 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (26)

[Claims] 1. A dielectric thin film comprising at least two types of thin films, wherein the thin films are bonded via a chemical bond, and at least one of the thin films is a monomolecular film or a monomolecular cumulative film. 2. A step of forming a monomolecular film by reacting one kind of compound on the surface of a base material, and another compound different from the compound is reacted on the monomolecular film so as to cover the monomolecular film. And a step of forming a thin film on the substrate, and these two steps are defined as one cycle, and at least one cycle is repeated. 3. A capacitor having an electrode formed on at least one surface of a dielectric thin film, wherein the dielectric thin film is composed of at least two types of thin films, and the two types of thin films and the electrodes are respectively formed through chemical bonding. A capacitor, wherein at least one of the thin films is a monomolecular film or a monomolecular cumulative film that is combined. 4. The dielectric thin film according to claim 1, wherein at least two types of thin films are alternately accumulated. 5. The capacitor according to claim 3, wherein at least two kinds of thin films are alternately accumulated. 6. The dielectric thin film according to claim 1, wherein the thin film is made of a silicon compound. 7. The method for producing a dielectric thin film according to claim 2, wherein the thin film is made of a silicon compound. 8. The capacitor according to claim 3, wherein the thin film is made of a silicon compound. 9. The dielectric thin film according to claim 1, wherein the chemical bond is a siloxane bond. 10. The method for producing a dielectric thin film according to claim 2, wherein the chemical bond is a siloxane bond. 11. The capacitor according to claim 3, wherein the chemical bond is a siloxane bond. 12. The dielectric thin film according to claim 1, wherein the monomolecular film is composed of a linear molecule having 8 to 24 carbon atoms. 13. The method for producing a dielectric thin film according to claim 2, wherein the monomolecular film is composed of a linear molecule having 8 to 24 carbon atoms. 14. The capacitor according to claim 3, wherein the monomolecular film is composed of a linear molecule having 8 to 24 carbon atoms. 15. One of the thin films comprises a molecule having 0 to 7 carbon atoms and having at least one reactive functional group.
The dielectric thin film according to. 16. One of the thin films comprises a molecule having at least one reactive functional group and having 0 to 7 carbon atoms.
The method for producing a dielectric thin film as described in. 17. One of the thin films comprises a molecule having at least one reactive functional group and having 0 to 7 carbon atoms.
Capacitor described in. 18. The monomolecular film is composed of a linear molecule having 8 to 24 carbon atoms, and the other thin film is composed of a molecule having 0 to 7 carbon atoms having at least one reactive functional group. The dielectric thin film described. 19. The method according to claim 2, wherein the monomolecular film is composed of a linear molecule having 8 to 24 carbon atoms, and the other thin film is composed of a molecule having 0 to 7 carbon atoms having at least one reactive functional group. A method for producing the dielectric thin film described. 20. The monomolecular film is composed of a linear molecule having 8 to 24 carbon atoms, and the other thin film is composed of a molecule having 0 to 7 carbon atoms having at least one reactive functional group. The listed capacitors. 21. Two types of thin films have the general formula --Si in the molecule.
X _p Y _3-p (where X is a substituent such as H or an alkyl group, Y is a halogen or alkoxy group, p is 0 or 1)
Alternatively, the dielectric thin film according to claim 1, which has at least one functional group represented by 2). 22. Two types of thin films have the general formula —Si in the molecule.
X _p Y _3-p (where X is a substituent such as H or an alkyl group, Y is a halogen or alkoxy group, p is 0 or 1)
Alternatively, the method for producing a dielectric thin film according to claim 2, having at least one functional group represented by 2). 23. Two types of thin films have the general formula --Si in the molecule.
X _p Y _3-p (where X is a substituent such as H or an alkyl group, Y is a halogen or alkoxy group, p is 0 or 1)
Or the capacitor according to claim 3, which has at least one functional group represented by 2). 24. Two types of thin films are Y (SiY ₂ O) _n Si
Y ₃ (where n ≦ 3, n is an integer, Y is a halogen or alkoxy group) and X _p Y _3-p Si-R _1- (CZ ₂ ) _n -R ₂
-SiX _q Y _{3-q or,, R 3 -R 1 - (} CZ 2) n -R 2
-SiX _q Y _3-q (where 8 ≦ n ≦ 24; n is an integer, R
₁ , R ₂ may or may not represent a substituent containing — (CH ₂ ) ₂ — or Si or O, R ₃ is an unsaturated group or a dimethylsilyl group, X is a substituent such as H or an alkyl group, The dielectric thin film according to claim 1, wherein Y is a halogen or an alkoxy group, Z is H or F, and p and q are 0 or 1 or 2. 25. Two types of thin films are Y (SiY ₂ O) _n Si
Y ₃ (where n ≦ 3, n is an integer, Y is a halogen or alkoxy group) and X _p Y _3-p Si-R _1- (CZ ₂ ) _n -R ₂
-SiX _q Y _{3-q or,, R 3 -R 1 - (} CZ 2) n -R 2
-SiX _q Y _3-q (where 8 ≦ n ≦ 24; n is an integer, R
₁ , R ₂ may or may not represent a substituent containing — (CH ₂ ) ₂ — or Si or O, R ₃ is an unsaturated group or a dimethylsilyl group, X is a substituent such as H or an alkyl group, The method for producing a dielectric thin film according to claim 2, wherein Y is a halogen or an alkoxy group, Z is H or F, and p and q are 0 or 1 or 2. 26. Two types of thin films are Y (SiY ₂ O) _n Si
Y ₃ (where n ≦ 3, n is an integer, Y is a halogen or alkoxy group) and X _p Y _3-p Si-R _1- (CZ ₂ ) _n -R ₂
-SiX _q Y _{3-q or,, R 3 -R 1 - (} CZ 2) n -R 2
-SiX _q Y _3-q (where 8 ≦ n ≦ 24; n is an integer, R
₁ , R ₂ may or may not represent a substituent containing — (CH ₂ ) ₂ — or Si or O, R ₃ is an unsaturated group or a dimethylsilyl group, X is a substituent such as H or an alkyl group, The capacitor according to claim 3, wherein Y is a halogen or an alkoxy group, Z is H or F, and p and q are 0 or 1 or 2).