JP3276385B2 - Method of forming polymer film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a conductive polymer film oriented on a substrate or the like and useful as a wiring material inside a printed board or an IC.

[0002]

2. Description of the Related Art In general, an integrated circuit uses an inorganic semiconductor such as Si or GaAs as a transistor portion.
Further, as the wiring portion, heavily doped Si, Al, W
And the like are used. On the other hand, it is known that an organic conductive polymer film such as polyacetylene has a property as a semiconductor, and a transistor can be formed using the polymer film. Further, in a conductive organic polymer film obtained by doping a dopant such as a halogen molecule or arsenic pentafluoride into the organic conductive polymer film,
For example, materials having an electric conductivity comparable to that of copper, such as polyacetylene, have been obtained. Since these films are organic, they are lightweight and flexible, and can be mass-produced at low cost.

Conventionally, in order to increase the electric conductivity of an organic polymer film, a catalyst is applied on a substrate and a conductive polymer film is formed on the substrate by polymerizing monomer molecules such as acetylene. This has been done by peeling off the polymer film from the substrate and stretching it. This is because, in a conductive polymer film immediately after polymerization, molecules in the film are generally non-oriented, and when this film is stretched, the orientation is increased, and the electric conductivity is improved by two to three digits. For example, a polyacetylene film In the case of (1), an electrical conductivity comparable to copper (several hundred thousand S (Siemens) / cm) can be obtained (Reference: H. Naarmann and N. Theophilou, Synthetic Metal)
s, 22 (1987) 1).

Another method is to dissolve a catalyst in a liquid crystal (solvent), apply a strong magnetic field of about 10 kGauss to the catalyst solution, and polymerize a monomer such as acetylene while the liquid crystal is oriented. An orientation film can be obtained without stretching. The electric conductivity in this case is about 10,000 S / cm (Reference: K. Akagi, S. Katayama, M. Ito, H. Shir)
akawa, and K. Araya, Synthetic Metals, 28 (1989) D
51).

[0005]

However, of the above-mentioned methods for obtaining an oriented conductive polymer film, the first stretching method involves peeling the polymer film from the substrate and stretching. With this stretching method, a polymer film having high electrical conductivity can be obtained, but it can be obtained using a printed board or IC.
In order to use it as an internal wiring, there is a problem that it needs to be attached to the substrate again. On the other hand, in a method using a catalyst dissolved in a liquid crystal (solvent) in a magnetic field, an alignment film can be directly obtained on a substrate. However, in this method, the value of electric conductivity is 1 compared to that obtained by a stretching method. There is a problem that a large-scale apparatus is required for polymerization under an intense magnetic field.

Accordingly, an object of the present invention is to provide a method for directly polymerizing an oriented conductive polymer film having high electric conductivity on a substrate with a simple structure.

[0007]

According to the present invention, a step of forming a thin film on a substrate surface, and a step of scanning the substrate surface in one direction with a laser beam to form unidirectional striped irregularities on the thin film surface. A step of applying a catalyst to the surface thereof, and a step of contacting a monomer with the catalyst to perform gas-phase catalytic polymerization. A method for forming a molecular film is provided.

According to the present invention, first, SiO ₂ , Si ₃ N ₄ , S
^- a thin film (e.g., thickness 0.5 to 10 [mu] m), such as polytetrafluoroethylene on the surface of a substrate, such as a conventional method by applying. Polytetrafluoroethylene is suitable for lamination on a substrate because it is insulative and has a certain degree of heat resistance and does not adversely affect electricity.

According to the present invention, the film of polytetrafluoroethylene or the like is scanned with a laser beam in one direction to form a unidirectional or uniaxial stripe-like unevenness (depth) on the film surface.
(Approximately 0.3 to 1.2 μm), and apply a catalyst to the surface. As the catalyst, a catalyst generally used for polymerization of polyacetylene or the like, for example, a Ziegler-Natta catalyst can be used.

A film having a thickness of 0.1 to 30 μm is grown by adjusting the time for bringing a monomer such as acetylene into contact with the catalyst coated on the unidirectional striped unevenness of the film such as polytetrafluoroethylene. The polymerization is stopped by applying vacuum to remove acetylene from the system.
Further, the catalyst can be removed from the polymer film by washing the formed film with a solvent such as toluene.

When the film is used as a wiring, the electric conductivity can be improved by doping this film with, for example, iodine from the gas phase. In the case of using as a transistor, it becomes possible by providing a gate electrode via an insulating film and forming a source / drain contact after undoping or lightly doping. As the dopant, for example, AsF ₅ , H ₂ SO ₄ , IC
l ₃ , HNO _{3 and the} like can also be used.

[0012]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, but it goes without saying that the present invention is not limited to the following Examples.

A polytetrafluoroethylene film 2 is applied to a surface of a SiO ₂ substrate 1 to a thickness of 1 μm, and this substrate 1 is placed on a hot chuck 3 provided on an XY stage 4 as shown in FIG. . While scanning the XY stage 4 in the XY directions, the entire surface was irradiated with the Ar laser 5. Thus, the polytetrafluoroethylene film 2 on the substrate 1
Was scanned in one direction by a laser beam 6. Laser power used is 0.5 W, scan speed is 10 mm
/ Sec, spot size is 30 μm, scan pitch is 10
μm, and the substrate temperature was 100 ° C. (heated by the hot chuck 3).

On the other hand, butoxytitanium and triethylaluminum are mixed at a molar ratio of 1: 4 and the amount of titanium in toluene is reduced.
The mixture was mixed at 100 mmol / liter, and then aged at room temperature for 1 hour in an argon atmosphere. The thus-prepared toluene solution of the catalyst was applied onto the polytetrafluoroethylene film 2 on the substrate 1 on which laser scanning was performed, and cooled to -78 ° C (improving the film quality). Next, using an apparatus as shown in FIG. 2, the internal atmosphere of the reaction bottle 7 was once evacuated, and then an acetylene gas 8 was introduced into the system at 0.4 atm for polymerization. Thus, a polyacetylene film as a conductive polymer film having a thickness of about 1.0 μm was grown on the substrate. The polymerization reaction was stopped by trapping acetylene gas in a cold trap and evacuating the atmosphere in the reaction bottle 7. In FIG. 2, 9 is a cold bath, and 10 is a cold trap for liquid nitrogen.

Next, as shown in FIG. 3, toluene 11 is introduced into the reaction bottle 7, the substrate on which the polyacetylene film is polymerized with toluene is washed, and the catalyst contained in the polyacetylene film is removed. did. Next, the polyacetylene film was vacuum-dried, and an oriented film of polyacetylene, which was a conductive polymer film, was obtained on a thin film of polytetrafluoroethylene.

In order to use the polyacetylene film obtained above as a wiring, the electrical conductivity can be improved by doping the film with, for example, iodine from a gas phase. An electrical conductivity of 50,000 S / cm was obtained by iodine doping at room temperature for about 5 hours.

In another embodiment, polysilicon is deposited on an SiO ₂ substrate by about 5,000 ° and laser-annealed in one direction, and then the same oriented polyacetylene film (electric conductivity: about 2 10,000 S / cm).
In this example, laser annealing was performed at a substrate temperature of 400 ° C. and a laser power of 3 W.

[0018]

As described above, according to the present invention,
An alignment film of a conductive polymer film can be easily formed directly on a substrate without using a large-scale facility such as application of a magnetic field.

[Brief description of the drawings]

FIG. 1 is a drawing for explaining an operation of laser annealing a polytetrafluoroethylene thin film on a substrate in a first embodiment of the present invention.

FIG. 2 is a view for explaining an operation of growing a polyacetylene film on a laser-annealed film on a substrate in the first embodiment of the present invention.

FIG. 3 is a view showing an operation of washing a grown polyacetylene film with toluene.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Polytetrafluoroethylene film 3 ... Hot chuck 4 ... XY stage 5 ... Ar laser 6 ... Laser beam 7 ... Reaction bottle 8 ... Acetylene gas 9 ... Cold bath 10 ... Cold trap of liquid nitrogen 11 ... Toluene

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI H05K 3/10 H01L 21/88 M (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 51/00 C08G 63 / 78 H01B 1/12 H01B 5/14 H01L 21/3205 H05K 3/10

Claims (2)

(57) [Claims] And 1. A process for forming a thin film on the substrate surface, the substrate surface was scanned in one direction with a laser beam, a step of applying a unidirectional stripe unevenness on the thin film surface, a catalyst to the thin film surface a step of applying, the step of performing a gas phase catalytic polymerization by contacting a monomer in the catalyst
Method of forming a polymer film, characterized in that it comprises a and. 2. The polymer film according to claim 1 , wherein said thin film is polytetrafluoroethylene .
Forming method .