JPH01313511A - Preparation of thin film of polymer - Google Patents

Abstract

PURPOSE:To obtain a thin film of polymer excellent in heat resistance, adhesiveness, etc., by evaporating specified vaporizable polymeric and/or polymerizable compound in a vacuum and reacting the formed vapors. CONSTITUTION:Evaporation tubes 6 and 9 charged with a bismaleimide of formula I [wherein Ar is a group of formula II or III (wherein X is -O-, -S-, -SO2-, -NH-, -CO-, -CS-or a 1-4C alkylene; R<1-2> are each H, a halogen atom, an OH group, a 1-4C alkyl or a 1-4C alkoxy; and n and m are the numbers of the substituents R<1-2> are each 1-4)] and vaporizable polymeric and/or polymerizable compounds are set in a vacuum chamber 1, and the chamber 1 is evacuated to 1X10<-4>Torr or below by operating a vacuum pump 12 while the evaporation tubes 6 and 9 are heated by applying a current to heaters 7 and 10 to evaporate the bismaleimide and the polymer. These vapors are allowed to deposit on a substrate 2 mounted on a substrate holder 3 and reacted with each other by heating with a heater 4 to form deposited film of a crosslinked bisimide polymer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to, for example, insulating films of electronic components such as semiconductors,
This invention relates to a method for manufacturing thin polymer films used as moisture-proof films, lubricating films, etc.

[Conventional technology]

The following methods are conventionally known as methods for producing polymer thin films, but each method has the problems listed below.

■ Method of dissolving the raw material monomer in a solvent, casting it onto a substrate, and polymerizing it: The solvent remains in the resulting thin film.

■ Method of vacuum evaporating and depositing polymers onto a substrate:
The types of polymers that can be deposited are limited, and decomposition may occur, resulting in a low molecular weight of the resulting polymer.

■ Method of adhering and depositing polymer on a substrate by sputtering Polymers are reduced in molecular weight during varnish sputtering, resulting in changes in physical properties such as a decrease in the thermal properties of the thin film.

[Problem to be solved by the invention]

Recently, as an alternative method for forming polymer thin films to these conventional methods, a vapor deposition polymerization method has been proposed in which a vapor-deposited polymer film is obtained on a substrate by single-polymerization by heating and evaporation of monomers, etc., and the following specific research is being carried out. is in progress.

(a) Method of forming polyparaxylylene thin film
This is a method of forming h-CHt÷0 on a substrate. With this method, the resulting thin film has low heat resistance.

(b) Method for forming a polyimide thin film from tetracarboxylic dianhydride and diamine This is a method in which the above two monomers are vapor-deposited together by heating, deposited on a substrate, and then heated and polymerized. This method has the advantage of producing a thin film with high heat resistance, but on the other hand, it is difficult to control the reaction molar ratio of the two monomers, making polymerization difficult (Japanese Patent Laid-Open No. 61-78463) , JP-A-61-138924, etc.).

(C) Method for forming a polyimide thin film from bismaleimide and diamine This is a method in which the above two monomers are deposited on a substrate by simultaneous heating vapor deposition, and then heated to form a crosslinked polyimide. In this method, the molar ratio can be controlled more easily than in (b) above, and a thin film with high heat resistance can be produced, but it also has low friction and non-adhesive properties.

It is difficult to impart various other properties such as low water absorption (see JP-A-61-211339).

In view of the above circumstances, it is an object of the present invention to provide a method for producing a polymer thin film that is easy to control reactions such as polymerization and has even better properties such as heat resistance and adhesion. Take it as a challenge.

[Means to solve the problem]

In order to solve the above problems, the method for producing a polymer thin film according to the present invention uses bis represented by the following general formula (where X is 10-, -S-, -so!-, -NH-).

-co-, -cs- or an alkylene group having 1 to 4 carbon atoms, R1 and Rz each independently represent hydrogen, Arogen,
Hydroxyl group, alkyl group having 1 to 4 carbon atoms, or 1 to 4 carbon atoms
4 alkoxyl group, n and m are R', R''
each independently represents an integer from 1 to 4)
] and a vapor-depositable polymer and/or a polymerizable compound are simultaneously evaporated under reduced pressure and then reacted to form a vapor-deposited film made of a crosslinked bismaleimide polymer on a substrate.

[For production]

The above bismaleimide does not polymerize in the evaporation tube,
It is easily evaporated by means such as heating, and then the following reaction proceeds between the evaporated polymer and/or polymerizable compound (hereinafter referred to as "reactive compound") and the bismaleimide. It is presumed that it will. First, bismaleimides radically react with each other at their double bond portions to produce a bismaleimide polymer (P or Q) having the structure shown below.

...(P) ...(Q) [However, as above, S and t represent positive integers. ] Here, the feature of this invention is that, simultaneously with the production of the bismaleimide polymers P and Q, a radical reaction between the same polymer or the raw material bismaleimide and a reactive compound, and a radical reaction between the reactive compounds occurs, the result,
A cross-linked bismaleimide polymer with a complexly branched three-dimensional structure is produced. Below, the structure of a part of the product [However, Ar is the same as above, -0-0 represents a polymer chain consisting of a reactive compound. ] The above structure is just an example, and the crosslinked bismaleimide polymer actually produced does not include the bismaleimide polymers P and Q, or polymerizable compounds such as hexamers or dimers. There are various bonding styles. Furthermore, it is presumed that other reactions than polymerization and crosslinking are also involved during polymer production.

As described above, a bismaleimide polymer with a complex crosslinked structure and the characteristics of a reactive compound is produced, so the resulting polymer thin film has very good physical properties including heat resistance. Become something.

〔Example〕

Hereinafter, the method for manufacturing a polymer thin film according to the present invention will be explained in detail.

The reactive compounds that react with the bismaleimide, that is, the vapor-depositable polymers and polymerizable compounds, are not particularly limited, and arbitrary compounds can be used alone or in combination of multiple types. Specifically, examples of polymers that can be vapor-deposited include polyethylene, polypropylene,
Polyvinylidene fluoride, polyvinyl chloride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, etc. are preferably used.

As a polymerizable compound, the above-mentioned baraxylylene dimer (
=diparaxylylene) and derivatives thereof (substituted benzene ring with halogen, lower alkyl group, hydroxyl group, etc.) are the most preferred examples. After evaporation, this diparaxylylene is converted into a heptamer by radical thermal decomposition, polymerized through a quinodimethane structure, and poly(p-
It is assumed that the result is xylylene). Furthermore, as polymerizable compounds other than those mentioned above, for example, compounds that are gaseous at room temperature and pressure (ethylene, propylene, tetrafluoroethylene, vinyl chloride, vinyl fluoride, etc.) can also be introduced into the reduced pressure chamber. . Further, a derivative of benzocyclobutene or the like may be used. The polymerizable compound may react with other components such as bismaleimide at the monomer stage, or may react with other components while polymerizing itself.

The bismaleimide and the reactive compound can be reacted at any mixing ratio. For example, in order to make full use of the properties of the reactive compound, it is appropriate to set the molar ratio of the reactive compound to bismaleimide to about 1 to 3, but it is acceptable to have a molar ratio outside of this range. Needless to say.

The method of vapor deposition of bismaleimide and the reactive compound is not particularly limited, and may include thermal vapor deposition (resistance heating vapor deposition, radio frequency heating vapor deposition, flash heating vapor deposition, electron beam heating vapor deposition, laser heating vapor deposition, etc.), ion blating method (ion vapor deposition, etc.). Method: DC ion brating, high frequency ion brating,
Methods such as reactive cluster ion deposition, ion beam deposition, etc.), sputtering methods (ion sputtering, magnetron sputtering, etc.) can be arbitrarily selected. In addition, the individual conditions for carrying out each of these methods are not particularly limited, and depending on the type of compound used, etc., it is necessary to provide energy that can appropriately evaporate the molecules without being broken down into pieces. , is preferably set appropriately. For example, the heating temperature when performing thermal evaporation is not particularly limited, but as a rough guide, bismaleimide is 140-180°C9 reactive compound is 200-400°C.
℃, and the reaction temperature for both was 180℃.
It is appropriate to set the temperature to about 250°C.

The degree of reduced pressure (or vacuum conditions) at the time of vapor deposition is not particularly limited, but it is appropriate to set the pressure to less than IXlO-'Torr, and more preferably to a pressure of about 1X10-' to 1×10 Torr. Under this level of reduced pressure, there is no need to raise the heating temperature too high for evaporating the raw material, and it is possible to suppress the polymerization of the raw material bismaleimide and the deterioration of the reactive compounds in the evaporation tube. Further, since the influence of residual gas on vapor deposition is relatively small, there is also the advantage that a clean vapor deposited film can be easily obtained.

Note that in order to obtain a clean deposited film, it is advantageous to have a higher degree of vacuum, but it is necessary to select a more powerful exhaust device, a material with less leakage, and the like.

The evaporated bismaleimide and the reactive compound may be deposited on the substrate (object) while or after undergoing a reaction such as polymerization or crosslinking, or both may be deposited on the substrate first, The reaction may then be carried out. The substrate material is not particularly limited, for example, glass, stainless steel, aluminum, copper, silicon steel, etc. It is also preferable to pre-treat the vapor deposition surface in advance according to a conventional method.

The thickness of the obtained polymer thin film is not particularly limited, but
For example, approximately 0.5 to 5 ha is appropriate.

If it is too thin, the uniformity may become insufficient.

FIGS. 1 to 3 are schematic cross-sectional views of an example of an apparatus used in the method for manufacturing a polymer thin film according to the present invention. It should be noted that among the structural members of the apparatus shown in FIGS. 2 and 3, those that are the same as those in FIG.

The apparatus shown in FIG. 1 includes an evaporation tube 6.9 in a vacuum chamber 1
and a substrate holder 3, and the reduced pressure chamber 1 is reduced to a predetermined pressure by operating a vacuum pump 12. Evaporation tubes 6, 9 of substrate holder 3
A substrate 2 to be vapor-deposited is attached to and detached from the surface facing the substrate holder 3 with the substrate 2 attached to the shaft 13.
It rotates around the center. The evaporation tubes 6 and 9 are
They are installed under the reduced pressure chamber 1 with their openings facing the substrate 2 side, and bismaleimide and a reactive compound are separately placed in each of them. The substrate 2 is heated to a predetermined temperature by a substrate heating heater 4, and the evaporation tube 6.9 is heated to a predetermined temperature by an evaporation tube heating heater 7.1o.

5.8 and 11 are power supplies for each of the above heaters, respectively.

The bismaleimide and the reactive compounds evaporated from the evaporation tube 6.9 are deposited on the substrate 2, and are then deposited on the substrate 2.
It is heated above and reacts to form a crosslinked bismaleimide polymer.

In the apparatus shown in FIG. 2, a heating furnace 14 is provided between the substrate 2 and the evaporation tubes 6, 9 instead of the substrate heater 4 in FIG. That is, the evaporated bismaleimide and the reactive compound react while passing through the heating furnace 14, and as a result, a crosslinked bismaleimide polymer is formed and then deposited on the substrate 2.

In the apparatus shown in FIG. 3, a pyrolysis furnace 15 and a power source 16 for the pyrolysis furnace 15 are provided between the evaporation tube 9 and the substrate 2, and a power source 16 is provided for the pyrolysis furnace 15 to generate radicals from the evaporated reactive compounds. It has become. Therefore, this device is particularly suitable when using a compound that requires thermal decomposition prior to polymerization, such as the above-mentioned diparaxylylene.

Below, more detailed examples will be described together with comparative examples.

Examples 1 to 10 - Using the apparatus shown in FIG. 1, polymer thin films were produced from bismaleimide and reactive compounds shown in Table 1 in the following manner. First, bismaleimide 1 is placed inside the evaporation tube 6.
00cm, 50cm of a reactive compound was put into the evaporation tube 9, and the pressure inside the vacuum chamber 1 was set to I x 10-'Torr. The evaporation tubes 6 and 9 were heated to the predetermined temperatures shown in Table 1, respectively, and bismaleimide and the reactive compound were vapor-deposited onto the substrate 2. Thereafter, heat treatment was performed at 200° C./1 hour using the substrate heating heater 4 to obtain a polymer thin film. In Examples 6 and 7, the amount of bismaleimide used was 50 .mu.m.

Comparative Example 1 A thin polymer film was obtained in the same manner as on the actual flow side, except that no reactive compound was used.

- Comparative Example 2 - A polymer thin film was obtained in the same manner as in the above example except that bismaleimide was not used.

Examples 11-16 Using the apparatus shown in FIG. 2, polymer thin films were produced from bismaleimide and reactive compounds shown in Table 2.

The heating furnace 14 was set at 200° C., and other conditions were the same as in the above examples. In Example 14, the amount of bismaleimide used was 50 .mu.m.

Comparative Example 3 - A polymer thin film was produced in the same manner as in Examples 11 to 16 above, except that no reactive compound was used.

Comparative Example 4 - A polymer thin film was produced in the same manner as in Examples 11 to 16 above, except that bismaleimide was not used.

Example 17 - Using the apparatus shown in FIG. 3, a thin polymer film was produced from 50 cm of bismaleimide and 50 cm of divaraxylylene shown in Table 2. The thermal decomposition furnace 15 was set at 600°C, and other conditions were the same as in the previous example.

The heat resistance and adhesion to the substrate of the obtained polymer thin films of Examples and Comparative Examples were investigated. Heat resistance was evaluated by determining a thermogravimetric loss curve using a thermobalance and determining the thermal decomposition onset temperature. Adhesion was determined by pasting adhesive tape (3M's Scotch Tape) on the surface of each thin film and determining whether the polymer thin film peeled off from the substrate (x) when it was peeled off.
○).

The above results are shown in Tables 1 and 2.

As shown in Tables 1 and 2, the polymer thin films obtained in each example had better heat resistance and better adhesion to the substrate than those of the comparative examples. It has been found.

〔Effect of the invention〕

According to the method for producing a thin polymer film according to the present invention, it is possible to easily control reactions such as polymerization and to obtain a thin polymer film that has better various properties such as heat resistance and adhesion. Therefore, the present invention is expected to be applicable to a wide range of fields such as the formation of insulating films or moisture-proof films for electronic components, semiconductor device manufacturing processes, and the formation of two metal surface protection circuits, and to bring great results.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are all schematic cross-sectional views showing an example of an apparatus used for carrying out the manufacturing method of the present invention. 1... Decompression chamber 2... Substrate 6,9...
Evaporation pipe agent Patent attorney Takehiko Matsumoto

Claims (1)

[Claims] 1 Bismaleimide represented by the following general formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, Ar is ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ or ▲ Numerical formulas, chemical formulas, tables, etc. etc.▼ (However, X is -O-, -S-, -SO_2-, -NH
-, -CO-, -CS- or an alkylene group having 1 to 4 carbon atoms; R^1 and R^2 each independently represent hydrogen, halogen, hydroxyl group, alkyl group having 1 to 4 carbon atoms, or an alkylene group having 1 to 4 carbon atoms; represents an alkoxyl group, n and m are R^
1, R^2, each independently representing an integer from 1 to 4)] and a vapor-depositable polymer and/or polymerizable compound are simultaneously evaporated under reduced pressure, and then reacted. A method for producing a polymer thin film in which a vapor-deposited film made of a crosslinked bismaleimide polymer is formed on a substrate.