JPH03121128A - Amphoteric polyimide precursor and mono-molecular thin film thereof - Google Patents

Abstract

PURPOSE:To obtain the title precursor which can form a lowly defective thin film by the LB method and, when heated, can give an ultrathin film having good heat resistance and electrical properties and excellent chemical resistance and mechanical properties by using specified repeating units as the principal components. CONSTITUTION:An amphoteric polyimide precursor mainly consisting of repeating units of formula I wherein R<1> is a tetravalent group having at least two carbon atoms; R<2> is a group of formula II; and R<3>, R<4>, R<5> and R<6> are each an aliphatic, alicyclic, or aromatic (or combined) 1-3C (halogen-, nitro-, amino-, cyano-, methoxy or acetoxy-substituted) monovalent group or H, and at least one of them is a 12-30C group. When the Langmuir-Blodgett method (LB method) is applied to this precursor, a lowly defective thin film can be formed, and when the obtained LB film is heated, an ultrathin polyimide film having a thickness <=10000Angstrom and very good heat resistance and electrical properties, being lowly defective and having good chemical resistance and mechanical properties can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a polyimide monomolecular thin film, more specifically an amphoteric polyimide precursor modified to be able to be formed by Langmuir-Prodgett (hereinafter referred to as LB method). and its manufacturing method.

The fortune is already 193
In the 1900s, Langmuir and Prodgett discovered that fatty acids with about 16 to 22 carbon atoms formed a monomolecular film on the water surface and accumulated it on the surface of the water.The application of this cumulative film was studied. It has only recently begun to be carried out. However, Langmuir-Prodgett membranes (hereinafter referred to as LB membranes) made of straight-chain saturated fatty acids have a problem in that they do not have sufficient heat resistance or mechanical strength for practical applications, and cannot be used as they are.

To improve these problems, for example, unsaturated fatty acids such as ω-tricosenoic acid, ω-hebutadecenoic acid, or α-octadecyl acrylic acid, or unsaturated fatty acid esters such as vinyl stearate and octadecyl acrylate, etc. Polymerized membranes are being researched, but their heat resistance is not sufficient.

On the other hand, there is a polyimide film as a heat-resistant film, but when using methods such as spin cord, it is possible to obtain a film with a thickness of at most 1000 Å or more, usually 1 μm or more, and a film with a thickness of less than 1000 Å without pinholes. It is extremely difficult to produce heat-resistant thin films.

The present inventors proposed in Japanese Patent Laid-Open No. 129317/1982 a material that can provide a heat-resistant ultra-thin film material with improved mechanical properties such as heat resistance and adhesive strength, and chemical resistance.

However, depending on the film forming method, it may be difficult to produce a defect-free polyimide thin film.

The present invention has been made by using a special diamine component in the polyamic acid unit, and has the general formula (1): (wherein R' is 4 containing at least 2 carbon atoms).
The valent group, R2 is (R3, R4, R5 and R6 are aliphatic, cycloaliphatic or aromatic (these may be combined with each other) monovalent groups having 1 to 30 carbon atoms (these The group may be substituted with a halogen atom, a nitro group, an amino group, a cyano group, a methoxy group, an acetoxy group) or a hydrogen atom, and at least one of R3, R4, R5 and R6 has 12 to 30 carbon atoms. , preferably 14 to 22 groups.

The present invention relates to an amphoteric polyimide precursor having a repeating unit represented by the following formula, and a monomolecular film or a cumulative film formed of the precursor on a substrate by the Langmuir-Prodgett method.

The amphoteric polyimide precursor of the present invention has a repeating unit represented by the general formula (1): % formula %) and has a number average molecular weight of 2.0.
00-300,000, preferably 10,000-1
50,000. Number average molecular weight is 2.000
If it is out of the range of ~300.000, the strength of the film produced will be too low or the viscosity will be too high, resulting in a tendency for the film to not be produced successfully.

R1 in general formula (1) is a tetravalent group containing at least 2 carbon atoms, preferably 5 to 20 carbon atoms, and may be an aromatic group, or an aliphatic group. It may be a group or a cycloaliphatic group,
These groups may be a combination of these groups (and furthermore, these groups may be aliphatic, cycloaliphatic, or aromatic (these may be combined with each other) and have 1 to 30 carbon atoms.
(These groups are halogen atoms, nitro groups,
may be substituted with a group such as an amino group, a cyano group, a methoxy group, or an acetoxy group) or the group
COO-, -NHCO-1-CO-1-s-, -css
It may also be a group substituted with a group bonded to -NHO2-1-C8- or the like to become a derivative. However, it is preferable from the viewpoint of heat resistance, chemical resistance, mechanical properties, etc. when R1 is a group characterized by benzenoid unsaturation having at least 6 carbon atoms.

Specific examples of R1 as described above include (hereinafter referred to as blank space).

The term "benzenoid unsaturation" as used herein is a term used in contrast to a quinoid structure regarding the structure of a carbocyclic compound, and refers to a structure having the same shape as a carbocyclic ring contained in ordinary aromatic compounds.

There is no particular limitation on the position of the joining hands, but if two of each of the four bonding hands are present on two adjacent carbon atoms constituting R1, it is formed using an amphoteric polyimide precursor. It is preferable because it is easy to form a 5-membered ring when polyimidizing a film or the like, and it is easy to imidize.

Preferred specific examples of R1 as described above include, for example, in the four bonds of p-quinoid benzenoid unsaturated R1, that is, in the repeating unit represented by general formula (1) (11710 and R11 in the above formula are both carbon (number 1 to 30 alkyl group or aryl group)] CH3-C-C)13 R2 is a divalent group, but if it is about 10 to 20%, the following divalent group can be used. They may be used in combination.

[During the ceremony, R9 is- (CHz)　r　　〜.

CH.

C.F.

-(CH2)7~1° CI,+ (CHI) a CH (CHz) zCH.

CH.

-(cut)IOCH(CH3)- Hff0 (CHz)s CH(CHz)z (CHz)s 0 -(CHz) * 0 (CHz)i etc.

In the general formula (1), R3, R4, R3
A valent group (these groups may be substituted with a halogen atom, a nitro group, an amino group, a cyano group, a methoxy group, an acetoxy group, etc. to form a derivative) or a hydrogen atom.

In general formula (1), R3, R4, R5 and R&
Both are groups introduced in order to impart hydrophobicity to the polyamic acid unit represented by the general formula (4): (% formula %) (in the formula, R1 and RZ are the same as above) and to obtain a stable condensed film. and at least one, preferably two of R3, R4, R5, and R6 have 12 to 12 carbon atoms.
30, preferably 14 to 22 of the above groups,
A stable condensed film is formed on the water surface, which is necessary for accumulation on the substrate by the LB method.

Specific examples of R3, R4, R5, and R6 as described above include:
For example, CHs(cH2su', (CTo) zC) I(C
(N is 12 to 30, preferably 16 to 2)
2) etc. In order for the amphoteric polyimide precursor of the present invention to be formed into a film by the LB method, the above group must be CH3 (C
A straight chain alkyl group represented by H, sn-1- is the most desirable in terms of performance and cost. Although the aforementioned halogen atoms, nitro groups, amino groups, cyano groups, methoxy groups, acetoxy groups, etc. are not essential, introducing fluorine atoms dramatically improves hydrophobicity compared to hydrogen atoms, so fluorine atoms It is preferable to use one containing

Specific examples of the repeating unit of the amphoteric polyimide precursor of the present invention in the case of two hydrogen atoms among R3, R4, R3, and R6 include general formula (2): % formula %) (wherein, R1, pt, R3, R4 are the same as above, except that R1 and R4 are groups having 12 to 30 carbon atoms), or general formula (3): When the repeating unit is represented by formula (3), is preferable because it is easy to manufacture and inexpensive.

Specific examples of the amphoteric polyimide precursor of the present invention having repeating units represented by general formulas (1) to (3) include (wherein R1, Rt, R5, and R6 are the same as above, only L
The repeating units of the amphoteric polyimide precursor of the present invention include general formula (2) and general (R in the formula
″, a specific example of R4 is CHs (CHz) +
+-5CH3 (Cut) + x-1CHs (CHt
) + sCHff(CHg)+-5CH3(CHt)
+-5CH3(CHt)t+CFs(CHz)t
As a specific example of door, R6, such as s-, CHs-1CH
s (CHt) z-2CHs (CHz) sCHs (
CHg) s-, etc.), (hereinafter referred to as margin), etc. → in the formula represents isomerism.

Isomerism means, for example, the general formula: (Specific examples of R1 and R4 in the formula include CHs(CHz
)+-5CH3(C)b)+5-1CHs (CHz)
+5-CHs(CHz)+-5CHff(CHz)
+*-1Cfl*((Jlt)z+-CF2 (CHz
) Is- etc.) The above formula is and (As a specific example of R55R& in the formula, CHs(CHt
)+-5CH3(CL)+5-5CHx (CHz)
l5CB! (CL)tt-1CHs(CTo) ++-
1CIlz(CHz)z+-1Ch(CH)3. -, etc.) 0 and 2 are expressed by two formulas, and in such cases, → is used to represent isomerism.

In the present specification, isomerism means that when a moiety represented by formula (a) or formula (b) is contained alone,
) represents any case where the parts expressed by the formula coexist.

The amphoteric polyimide precursor having a repeating unit represented by general formula (1) may consist of a single repeating unit (
, a copolymer consisting of different repeating units.

In general formula (1), at least one of RI, R6
Various copolymers are provided by using at least two groups selected from the specific examples of R1 to R6 described above.

(In the formula, x and y represent the ratio, 0<x<1.0<y<
l, x+y=1).

Further, when type 02 is selected as R2, the repeating unit of the amphoteric polyimide precursor is represented by the general formula: :%Formula%). The above examples are just a few examples. Also, R
Many examples can be given for 3, R4, and R8SR&, but when written as a repeating unit, for example (in the margin below) "-1-He21\ / \ / / \\ / \ / etc.

The amphoteric polyimide precursor of the present invention as described above can be prepared by dissolving -i in an organic polar solvent such as N,N-dimethylacetamide, N,N-dimethylformamide, N,N-diethylformamide, hexamethylphosphoramide, etc. Soluble in mixed solvents such as organic polar solvents and ordinary organic solvents such as chloroform, and poorly soluble in ordinary organic solvents such as benzene, ether, chloroform, acetone, methanol, etc.
It is insoluble and characteristic absorptions of amides, carboxylic acids (and in some cases carboxylic esters) and long-chain alkyl groups are observed in infrared ([R) absorption spectroscopy. The amphoteric polyimide precursor, which was selected for its good heat resistance, has characteristics in the results of thermal analysis: a rapid weight loss begins at about 200°C and is completed at about 400°C. After the weight reduction is completed, the absorption of amide, carboxylic acid (carboxylic acid ester in some cases), and long-chain alkyl group disappears in IR absorption spectrum analysis, and the absorption of imide ring disappears.

In the above description, the case where all the repeating units of the precursor of the present invention are repeating units represented by the general formula (1) was explained, but if it is within 30% of the repeating units, the general formula ( 5): [wherein R1 and R2 are the same as above, R is a monovalent aliphatic group having 1 to 11 carbon atoms, a cycloaliphatic group, or an aromatic group (these may be combined with each other)
A group in which these groups are substituted with a halogen atom, a nitro group, an amino group, a cyano group, a methoxy group, an acetoxy group, etc., or a hydrogen atom, and the four R's may be the same or different.] It may contain a repeating unit represented by .

Next, an LB film using the precursor of the present invention will be explained.

A method for producing an LB film using the precursor of the present invention is to spread the precursor on a water surface, compress it with a constant surface pressure to form a monomolecular film, and transfer the film onto a substrate. A certain LB
In addition to the method, methods such as the horizontal adhesion method and the rotating cylinder method (New Experimental Chemistry Course, Vol. 18, Interfaces and Colloids, pp. 498-508) can be cited, but there are no particular limitations as long as they are commonly used methods. It can be used without

Generally, when a substance that forms an LB film is spread on the water surface, benzene, which does not dissolve in water and evaporates into the gas phase,
A solvent such as chloroform is used, but in the case of the precursor of the present invention, it is desirable to use an organic polar solvent in combination to increase solubility.

Examples of such organic polar solvents include N, N-
Dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide,
dimethyl sulfoxide, N-methyl-2-pyrrolidone,
Examples include pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylenesulfone, and dimethyltetramethylenesulfone.

When benzene, chloroform, etc. are used in combination with an organic polar solvent, it is thought that when developed on the water surface, the benzene, chloroform, etc. will evaporate into the gas phase, and the organic solvent will dissolve in a large amount of water.

The concentration of the solution used when spreading the precursor of the present invention on the water surface is not particularly limited, but usually about 2 to 5XIO-'M is used.

The substrate on which the LB film using the precursor of the present invention is formed is not particularly limited, and may be selected depending on the purpose of the formed LB film, but when the LB film is heated and used as a polyimide, It is necessary to have good heat resistance.

Specific examples of the above-mentioned substrates include inorganic substrates such as glass, alumina, and quartz, as well as metal and plastic substrates, as well as group Ⅰ, IV group, such as St, GaAs, and ZnS. ■-■ group semiconductors, P b T
t Os , B a T i O3, LiNb0.
, LiTa0. Examples include ferroelectric substrates and magnetic substrates such as . Of course, these substrates may be used after being subjected to a commonly used surface treatment.

By using the precursor of the present invention, it is possible to form a thin film with few defects and good heat resistance on a substrate by the LB method, and by partially or completely imidizing this thin film, it is possible to further improve the heat resistance. An excellent thin film can be obtained.

There is no particular limitation on the imidization method, but 200~
Heating is generally performed at a temperature of around 400°C, and may be performed using laser light or the like.

Of course, acetic anhydride and pyridine used in the imidization of polyamic acid may be used, or they may be used in combination with thermal reaction. For example, in the case of the repeating unit represented by the general formula (2) In the case of the repeating unit represented by the general formula (3), the following reaction occurs to form a polyimide. Of course, in the case of the polyamic acid unit represented by the general formula (4), 8.0 is also produced and becomes a polyimide, but in this case it cannot be used as a material for an LB film.

Since the precursor of the present invention has improved heat resistance and chemical resistance than ordinary LB films, the LB film of the present invention can be used as it is for applications such as devices.

The polyimide thin film obtained as mentioned above has heat resistance,
Excellent chemical resistance, good mechanical properties, and 100%
It is a very thin film of 0 Å or less, and if desired, 5 to 1
It can be up to 000 people. Therefore, it can be used in the electronics field not only as an insulating film for ICs and LSIs, but also as an insulating layer in various electrical and electronic devices with structures such as capacitors, MIS, and MIM, and for field effect transistors, photoelectric conversion, etc. It can be used for elements, light receiving elements, light emitting elements, photodetecting elements, thermionic transistors, etc. JJ(
Josephson Junction). In addition, it can be used as a cladding material for unibu guides, an optical circuit component, etc., and can also be suitably used as a coating material, including for protection purposes. It can also be used in fields such as energy conversion and material separation.

Next, the precursor of the present invention and its manufacturing method will be explained based on Examples.

Example 1 2.18 g (0.01 mol) of pyromellitic dianhydride and 5.40 g (0.02 mol) of stearyl alcohol were reacted in a flask at about 100°C under dry nitrogen flow for 3 hours, It was purified by reconsolidation with ethanol.

Thionyl chloride 6d was added to 2.28 g (3 mmol) of the obtained half ester and acylated at about 70"C for 1 hour. Thereafter, excess thionyl chloride was distilled off.

The generated acid chloride was converted into hexamethylphosphoramide 4
Dissolve in 0 cc and add 20 cc of dimethylacetamide to this.
1.23 g (3 mmol) of 2,2°-bis(4-aminophenoxyphenyl)propane dissolved in
After dropping, the mixture was reacted for about 1 hour, and then the reaction was continued for 1 hour at a room temperature of 40°C. Pour the reaction solution into distilled water 2
The reaction product was precipitated by pouring into 50 cc. The precipitate was filtered and dried under reduced pressure at about 40°C to obtain about 3 g of pale yellow powder.

The obtained powder was subjected to molecular weight measurement by IR spectrum analysis, NMR analysis, and GPC method, and was confirmed to be the desired polyimide precursor.

(IR spectrum analysis) The analysis results measured by the KBr disk method are shown in FIG.

The chart shows ester, amide ■absorption band, ■absorption band, ■
There are absorption bands, characteristic absorptions of alkyl chains and ethers.

(Molecular weight measurement by GPC method) The number average molecular weight measured using N,N-dimethylacetamide solvent was about so, ooo in terms of polystyrene.

Example 2 Chloroform/distilled product of Example 1 55.1
A developing solution for LB membrane was prepared by dissolving it in a mixed solution of dimethylacetamide = 8/2 (volume ratio) to make a 25 ml solution.

Using the obtained developing solution, the relationship between the surface pressure π and the area per repeating unit (unit) was measured at 20° C. over double-distilled water, and the results shown in FIG. 2 were obtained. The surface pressure rose from about 105 people"/unit, forming a good condensed film. The ultimate area was 72 people"/unit, and the collapse pressure was 4Qdyne/cm, which is a very high value for a polymer membrane. .

Furthermore, even when the membrane was held on the water surface with a surface pressure of 25 dyne/am, the membrane remained stable with no decrease in area observed over 2 hours.

Next, the surface pressure of the membrane on the water surface was set to 25 dyne/1 at 20"C.
60 layers were accumulated on a glass substrate or a silicon plate by the LB method at a cumulative speed of 10 mm/ll1n.

When a film formed on a silicon plate was analyzed by FT-IR analysis, the spectrum was changed to have the same absorption peak as in Figure 1, and it was a cumulative film of the compound obtained in Example 1, and the area-time curve was It was confirmed that it was a Y-type film.

A film with fewer defects was observed by Nomarski microscopic observation compared to a cumulative film using diaminodiphenyl ether as the diamine.

Further, by heating the cumulative film at 400°C for 1 hour, α, β-unsaturated 5-membered ring imide was generated, as shown by the analysis results of 1790CII-' by FT-IR analysis.
It was confirmed by the peak at 1710 cm-'.

2jIB ■ By using the precursor of the present invention, it is possible to form a thin film with few defects by the LB method, and by heating the obtained LB film, it is possible to form a thin film with very good heat resistance and electrical properties, and with few defects and durability. Good chemical properties and mechanical properties, and thickness 1
0,000 Å or less, if necessary, the ultra-thin polyimide film of 5 to 1,000 layers can be used.

[Brief explanation of drawings]

FIG. 1 is an IR spectrum diagram of the substance obtained in Example 1, and FIG. 2 is a graph showing the relationship between the surface pressure and area per repeating unit of the LB membrane developing solution of Example 2.

Claims (1)

[Claims] (1) Amphoteric polyimide precursor mainly having repeating units of general formula (1) ▲ Numerical formulas, chemical formulas, tables, etc. are available ▼ (1) [In the formula, R^1 is a tetravalent polyimide containing at least two carbon atoms. The group R^2 has ▲ mathematical formulas, chemical formulas, tables, etc. ▼ R^3, R^4, R^5 and R^6 are aliphatic, cycloaliphatic or aromatic (these are not combined with each other) (which may be substituted with a halogen atom, a nitro group, an amino group, a cyano group, a methoxy group, or an acetoxy group) or a hydrogen atom. , R^3, R^4, R^5 and R^6 are groups having 12 to 30 carbon atoms. ] (2)
A monomolecular thin film or a cumulative film formed on a substrate by the Langmuir-Prodgett method of an amphoteric polyimide precursor having mainly repeating units of general formula (1).