JPH0757998A - Formation of polymer thin film - Google Patents

Abstract

PURPOSE:To form a polymer thin film having uniform thickness by reducing the pressure in a reactor to a level higher than a specific level. CONSTITUTION:A plurality of substrates are disposed in a holder 4 within a reactor 1 which is then evacuated. When a predetermined pressure is reached, an exhaust valve 5 is closed to stop evacuation. A gas valve 7 is then opened to introduce a predetermined quantity of catalyst. Subsequently, a gas valve 8 is opened to introduce a predetermined quantity of monomer into the reactor 1 thus forming a polymer thin film on the substrate. In this regard, inner pressure of the reactor 1 is reduced to a level higher than about 1Torr when the catalyst and monomer are introduced. Preferably, the inner pressure is reduced to a level in the range of 10-500Torr. This method allows simultaneous formation of polymer thin film having uniform thickness on the plurality of substrates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polymer thin film, and more particularly to a method for producing a polymer thin film most suitable for a lower layer thin film for radiation sensitive resist.

[0002]

2. Description of the Related Art In the manufacture of semiconductors, with the increase in capacity of semiconductor memories, finer processing techniques continue to be required. A lithography technique is generally used for the fine processing.

Here, a general lithography technique will be described. A radiation-sensitive resist is formed on a semiconductor substrate, and radiation is selectively irradiated so as to obtain a desired resist pattern, and then development is performed to form a resist pattern. Using the resist pattern as a mask material, processes such as etching, ion implantation and vapor deposition are performed, and these steps are repeated to manufacture a semiconductor.

Currently, a resist pattern having a size of about 0.5 μm is being industrially put into practical use.
Further miniaturization is required. As a method of miniaturizing the resist pattern, for example, there is a method of pattern exposure by using light of a single wavelength as radiation and reducing and projecting the original image. Especially for the purpose of microfabrication, it is required to shorten the wavelength of light, and the technology of irradiating with a wavelength of 436 nm has already been established.
Development of a technique for irradiating with light in the deep ultraviolet region of m or less is under study.

Such a lithographic technique has the following problems. First, due to reflection from the substrate, radiation interference occurs in the radiation-sensitive resist film, and as a result, the amount of radiation energy imparted to the radiation-sensitive resist film changes due to fluctuations in the thickness of the radiation-sensitive resist film. It will have varying characteristics. That is, the dimension of the resist pattern obtained by the minute change in the thickness of the radiation-sensitive resist is likely to change. Further, as the wavelength of the radiation is shortened for the purpose of miniaturization of processing, radiation reflection from the substrate generally increases, and this characteristic becomes remarkable. The change in the thickness of the resist layer is caused by the characteristic changes of the radiation-sensitive resist material due to the passage of time or the difference between lots, and the changes in the coating conditions of the radiation-sensitive resist. A change in thickness occurs. As described above, the dimensional change of the resist pattern due to the change of the thickness of the resist layer reduces the process tolerance at the time of manufacturing, which is an obstacle to finer processing.

Further, when the substrate is highly reflective and the steps are arranged in a complicated manner, diffuse reflection of radiation occurs, so that the shape is likely to locally change from the desired resist pattern shape. There is.

In order to solve such a problem, the present inventors have already proposed, as a method of suppressing the above-mentioned reflection, in Japanese Patent Application No. 3-202686 between a substrate and a radiation-sensitive resist. A method of interposing a thin film containing a conjugated polymer as a main component is proposed.

[0008]

However, in such a technique, when an attempt is made to form a thin film on a plurality of substrates, the introduction of the monomer into each substrate becomes non-uniform, so that the film thickness becomes non-uniform. There was a problem that became.

The present invention is intended to solve the above problems of the prior art, and provides a method for forming a polymer thin film having a uniform film thickness on each of a plurality of substrates at once. It is provided.

[0010]

The present inventors have achieved the present invention as a result of intensive studies to solve the above problems. That is, the present invention is characterized in that in the method of introducing a vaporized catalyst and a monomer into a reactor to form a polymer thin film on a substrate, the pressure inside the reactor is reduced to a pressure exceeding 1 Torr. The present invention relates to a method for producing a polymer thin film.

The present invention will be described in detail below.

As the catalyst used in the production method of the present invention, an amine compound is preferable from the viewpoint of film formation rate, and among them, an amine compound having a tertiary amino group is preferably used. Examples of the amine compound having a tertiary amino group include triethylamine, tripropylamine, tributylamine, hexamethylethylenediamine, pyridine, 4-dimethylaminopyridine, N, N-dimethylaminoethanol and the like.

In the present invention, the monomer forming the polymer thin film is selected from acetylene or a monomer containing substituted acetylene as a main component. Examples of the substituted acetylene include cyanoacetylene, methylacetylene, phenylacetylene, fluoroacetylene and the like.

The substrate used in the present invention is not particularly limited, but is arbitrarily selected, for example, from a material on which a lithographic process is performed. INDUSTRIAL APPLICABILITY The present invention is effective in the manufacturing process of semiconductor integrated circuits, and in this case, substrates having semiconductor characteristics such as silicon, germanium, gallium compound, and indium compound, or impurity diffusion, nitride, and oxide on these substrates Those coated with an insulating film, a conductive layer, an electric wiring, etc. are exemplified.

The present invention is also effective in the manufacturing process of a flat panel display, and for example, a substrate obtained by processing a metal, a semiconductor or the like on a transparent substrate such as glass is also preferably used. Further, the substrate is preferably placed in a substrate holder and used during the production of the polymer thin film.

The method of using the polymer thin film of the present invention will be described. The polymer thin film of the present invention is useful as an underlayer film of a two-layer structure radiation sensitive resist. For example, a polymer thin film is formed on a substrate by the method shown in the present invention to form a lower layer film. Further, an upper layer resist capable of forming a pattern sensitive to radiation is formed on the polymer thin film to obtain a two-layer structure radiation sensitive resist. Then, patterning radiation is irradiated, and then a developing operation is performed to form a pattern of the upper layer resist. Next, by using the upper layer resist as a mask, the lower layer resist in the opening of the upper layer resist is removed by dry etching, and the two-layer structure radiation sensitive resist is patterned.

Here, as the radiation for pattern formation,
Although it is arbitrarily selected in the lithography technique, the lower layer resist is effective in the present invention by electromagnetic waves, that is, light, and particularly electromagnetic waves having a wavelength of 150 nm or more. For example, the wavelength is about 436 nm, about 405n
m, about 365 nm, about 245 nm, and the like, and mercury lamp emission lines, about 364 nm, about 248 nm, and about 193 nm laser light.

An example of the method for producing a polymer thin film of the present invention will be described below with reference to the drawings. FIG. 1 is an example of a schematic diagram of an apparatus for carrying out the manufacturing method of the present invention.
In FIG. 1, 1 is a reactor, 2 is a catalyst, 3 is a monomer, 4
Is a substrate holder on which a plurality of silicon wafers can be placed. Further, 5 is an exhaust valve, 6 is a gas valve for introducing an inert gas, 7 is a gas valve for introducing a catalyst, and 8 is a gas valve for introducing a monomer.

After placing a substrate such as a silicon wafer on the substrate holder 4, the reactor 1 is evacuated by using an exhaust device (not shown) such as a dry pump to reduce the pressure. When the predetermined pressure is reached, the exhaust valve 5 is closed and the exhaust is stopped.

After opening the gas valve 7 and introducing a predetermined amount of the catalyst, the gas valve 7 is closed to stop the introduction of the catalyst. Then, the gas valve 8 is opened and a predetermined amount of a monomer is introduced into the reactor 1 to obtain a polymer thin film on the substrate.

In the present invention, it is important that the pressure in the reactor is reduced to a level not higher than 1 Torr when a predetermined amount of the catalyst or monomer is introduced. By setting the pressure range, it is possible to form polymer thin films with a uniform film thickness on a plurality of substrates. When the pressure is 1 Torr or less, the film formation rate is low and not practical, and when the pressure is higher than the atmospheric pressure, the film thickness uniformity decreases. Further, the range of 10 Torr to 500 Torr is preferable.

After introducing a predetermined amount of monomer, the gas valve 8 is closed. 9 is a gas introduction plate having a large number of fine holes. 10
Is a pressure gauge.

As the method of introducing the catalyst and the monomer, a method of introducing the catalyst and the monomer at the same time, a method of introducing them in a mixed manner, a method of introducing the catalyst after introducing the monomer, and the like are used. After that, the method of introducing the monomer is preferable from the viewpoint of controllability of film thickness and film quality. The catalyst and the monomer may be supplied at the same time as the inert gas, or after being mixed and diluted with an inert gas,
May be introduced.

After the polymer thin film is formed by the above method, the exhaust valve 5 is opened and the inside of the reactor 1 is exhausted again. After exhausting for a certain period of time, the exhaust valve 5 is closed to stop the exhausting. An inert gas such as nitrogen is introduced into the reactor to return the inside of the reactor to normal pressure. Next, the substrate on which the polymer thin film is formed is taken out of the reactor and heat-treated. The heat treatment is preferably performed in order to improve the chemical resistance in the subsequent lithography process and the like. The heat treatment is preferably performed on the substrate on which the polymer thin film is formed in an inert gas atmosphere or under vacuum. The heat treatment temperature is preferably 200 ° C. or higher,
Further, it is preferably 500 ° C. or higher.

In order to further improve the in-plane and inter-plane film thickness uniformity, it is preferable to control the temperature of the substrate holder 4 to set and maintain the substrate at a constant temperature. Also a catalyst,
In order to control the film formation rate, it is desirable to keep the temperature of the monomer container and the vapor pressure constant in a constant temperature bath.

Further, the catalyst and the monomer are introduced into the reactor in the form of gas, but in order to uniformly supply the gas to the substrate,
It is preferable to dispose a gas introduction plate having a large number of fine holes or a ring-shaped gas blowing nozzle having a large number of fine holes.

Prior to forming the polymer thin film by the manufacturing method of the present invention, the substrate may be subjected to heat treatment, plasma treatment or other surface treatment in order to improve the adhesion between the substrate and the polymer thin film. It doesn't matter.

The plurality of substrates can be deposited in any direction such as the vertical direction, the horizontal direction, or an intermediate direction between them, and film formation can be performed, and the substrates can be placed on a flat plate-shaped substrate holder having a large area. A plurality of substrates may be arranged in one direction. Needless to say, the present invention can be applied to even one substrate.

The production method of the present invention is suitable for an underlayer thin film for a radiation-sensitive resist, but the polymer thin film obtained by the production method of the present invention is black and has excellent light ray absorption performance and electrical insulation. It is also applicable as a method for manufacturing a light-shielding film of a color liquid crystal display or a color image sensor, etc., because it is also excellent in wraparound property. Since it is possible to form a film from the above, it is suitable as a mass production method of various black thin films such as an antireflection (light absorption) film for optical parts.

[0030]

EXAMPLES Examples 1 to 3 Hereinafter, the present invention will be described more specifically with reference to Examples using the apparatus of FIG. A commercially available wafer carrier capable of accommodating 25 silicon wafers is used as a substrate holder, a silicon wafer which is a substrate is arranged, and then the exhaust system evacuates the reactor to 0.1 Torr or less. Close the exhaust valve 5 to stop the exhaust, the gas valve 7
The reactor is opened and the catalyst vaporized triethylamine is introduced into the reactor. The gas valve 7 was closed to stop the introduction of triethylamine, and then the gas valve 8 was opened to introduce cyanoacetylene as a monomer into the reactor to form a cyanoacetylene polymer thin film on a silicon wafer. Examples in which the amounts of triethylamine and cyanoacetylene introduced are set under the conditions shown in Table 1 are Examples 1 to 3.

The silicon wafer on which the polymer thin film is formed is transferred to a heat treatment chamber, and it is placed in a vacuum of 0.1 Torr or less for 3 minutes.
Heat treatment was performed at 50 ° C. for 1 minute.

Table 1 shows the measurement results of the film thickness of the polymer thin films of Examples 1 to 3 by the step thickness gauge. The cyanoacetylene polymer thin films obtained on each substrate are located at the position from the gas introduction port. ± 10% for the average film thickness of 25 sheets regardless of
Within the range of fluctuation, it was clear that the production method of the present invention was industrially useful.

In Examples 1 to 3, since a commercially available wafer carrier was used as the substrate holder, the cyanoacetylene polymer thin film was formed on both surfaces of the silicon wafer. However, when the back surface was not formed, each substrate was used. It suffices to provide a tray for arranging the substrates one by one and arrange the substrates so that the substrates are in close contact with each other. Further, the temperature of the substrate can be controlled by controlling the temperature of the tray.

[0034]

[Table 1] Comparative Example 1 After placing 25 silicon wafers on a wafer carrier in the same manner as in Example 1, the reactor was kept at normal pressure without being evacuated, and the reactor was bubbled with nitrogen gas to vaporize the catalyst. The resulting triethylamine was introduced for 1 minute to adsorb the catalyst on the surface of the silicon wafer. Then, by bubbling with nitrogen gas, vaporized cyanoacetylene which is a monomer was introduced for 1 minute to form a cyanoacetylene polymer thin film. Then, the silicon wafer was transferred to a heat treatment chamber and heat-treated in nitrogen at 350 ° C. for 1 minute.

A cyanoacetylene polymer thin film was formed on each of the 25 substrates, but the thin films on the substrates arranged near the gas inlet tended to be thicker and those far away tended to be thinner. The thickest film has a film thickness twice or more that of the thinnest film, and it has been difficult to control a plurality of films to have the same film thickness under normal pressure.

[0036]

According to the production method of the present invention, that is, the vaporized catalyst and the monomer are sequentially or simultaneously introduced, and the pressure inside the reactor is reduced to more than 1 Torr. A polymer thin film having a uniform film thickness can be formed on a substrate, and an industrially useful manufacturing method can be provided.

[Brief description of drawings]

FIG. 1 is an example of a schematic diagram of an apparatus for carrying out a manufacturing method of the present invention.

[Explanation of symbols]

 1: Reactor 2: Catalyst 3: Monomer 4: Substrate holder 5: Exhaust valve 6: Gas valve for introducing an inert gas 7: Gas valve for introducing a catalyst 8: Gas valve for introducing a monomer 9: Many Gas introduction plate having fine holes of 10: Pressure gauge

Claims (2)

[Claims] 1. A vaporized catalyst and vaporized acetylene or substituted acetylene monomer are introduced into a reactor,
In the method for producing a polymer thin film for forming a polymer thin film on a substrate, the pressure inside the reactor when introducing the monomer is set to 1 To.
A method for producing a polymer thin film, which comprises reducing the pressure within a range not exceeding rr. 2. The pressure in the reactor is 10 Torr or more, 5
The method for producing a polymer thin film according to claim 1, wherein the thickness is 00 Torr or less.