JPS6012175A - Coating liquid supplying method - Google Patents

Abstract

PURPOSE:To obtain a product free from a pinhole or coating irregularity by preventing the generation of air bubbles during coating, by introducing a coating liquid using a solvent having strong polarity into a hermetically closed container while introducing high pressure has into said container to feed the coating liquid through a supply pipe under pressure. CONSTITUTION:A high pressure gas introducing pipe 8 and a coating liquid introducing pipe are inserted into a hermetically closed container 1 and the lower end part of the high pressure gas introducing pipe 8 is positioned above the liquid surface of the coating liquid 3 while the hermetically closed container 1 is filled with the coating liquid 3 using a solvent having strong polarity. At the same time, an article 7 to be treated is placed on a spinner head 6 to be sucked thereto under vacuum and gas such as He or Ne is introduced into the hermetically closed container 1 from the high pressure gas introducing pipe 8 to raise the pressure in said container 1. After a supply pipe 9 is filled with the coating liquid 3 by operating a valve 11, the valve 11 is once closed. The valve 11 is again opened to drip the coating liquid 3 on the surface of the article 7 to be treated from a nozzle 10 while the rotary shaft of the spinner 2 is rotated. The dripped coating liquid 3 is applied to the surface of the article 7 to be treated in a uniform thickness by centrifugal force.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for supplying a coating liquid dropwise onto an object to be treated using gas pressure.

Generally, to form a photoresist film, an impurity diffusing agent film, an optical film, or a protective film on the surface of a workpiece such as silicon quaver or glass, nitrogen gas is introduced into a sealed container containing a coating solution. A method is adopted in which the pressure inside the container is set at high pressure, and the coating liquid in the container is pumped through a supply pipe using this pressure and dripped onto the object to be treated.

If the above coating solution is prepared using a relatively weakly polar solvent such as toluene or xylene, no problem will occur, but if the coating solution is a positive photoresist film, an impurity diffusion agent film, a protective film, or an optical coating. In general, alcohol-based, ketone-based, logenated hydrocarbon-based,
Strongly polar solvents such as ester-based, ether-based, nitrogen-containing, ion-containing, or phosphorus-containing solvents are used, and in this case, the following problems occur.

In other words, when the inside of the sealed container is made high pressure with nitrogen gas,
Henry's law states that the mass of a gas dissolved in a certain amount of liquid at a certain temperature is proportional to the pressure of that gas, so the higher the pressure, the more nitrogen gas will dissolve in the coating liquid. The Ostwald absorption coefficient (solubility) of the gas is high, and therefore a large amount will be dissolved. Since the coating liquid is dripped onto the surface of the workpiece through the supply pipe under normal pressure, the nitrogen gas dissolved in the coating liquid in a supersaturated state forms fine bubbles when it is dripped. death,
The air bubbles are fixed in the film by being applied with the air bubbles still present.

As a result, pinholes or uneven coating occur, which leads to a decrease in product yield.

In order to solve this problem, it is possible to install a trap in the middle of the coating liquid supply pipe and remove air bubbles during pressure feeding, but this has the disadvantage that the device itself is complicated and it is not possible to completely remove air bubbles. .

The present invention was developed in view of the above-mentioned problems, and its purpose is to reduce the amount of dissolved gas in the coating liquid as much as possible without adding any special parts to the coating device. It is an object of the present invention to provide a method for supplying a coating liquid that prevents the generation of air bubbles during coating and allows a product without pinholes or uneven coating to be obtained.

In order to achieve such an object, the present invention includes placing a coating solution using a highly polar solvent in a closed container, supplying helium gas or neon gas with low solubility into the closed container via a high-pressure gas introduction pipe, The gist of the present invention is that the coating liquid is pumped through the supply pipe using this gas pressure.

Embodiments of the present invention will be described below based on the accompanying drawings.

In the figure, 1 is a sealed container, 2 is a spinner, and the sealed container 1
The inside is filled with a coating liquid 3 adjusted with a highly polar solvent, and a rotating shaft 5 is inserted from below into the bottomed cylindrical body 4 of the spinner 2, and a spinner head 6 is attached to the tip of the rotating shaft 5. The object to be processed 1 such as a silicon wafer is placed on the spinner head 6 .

On the other hand, a high-pressure gas introduction pipe 8 and a coating liquid supply pipe 9 are inserted into the closed container 1, and the lower end of the high-pressure gas introduction pipe 8 is positioned above the liquid level of the coating liquid 3, and the supply pipe The lower end of the container 9 is located below the liquid level and near the bottom of the closed container 1. A nozzle 1° for dropping the coating liquid is attached to the other end of the supply pipe 9, and this nozzle 10 faces above the spinner head 6. Furthermore, a valve 11 driven by high-pressure air or the like and a suck-back mechanism 12 for preventing the coating liquid from dripping after coating is stopped are provided in the middle of the supply pipe 9.

In the above process, the sealed container 1 is filled with 3t of coating liquid and left to stand to defoam, and at the same time, the spinner head 6
The object to be processed 7 is placed on top and vacuum-adsorbed. From this state, helium gas or neon gas is introduced into the closed container 1 through the high-pressure gas introduction pipe 8 to make the inside of the closed container 1 high pressure. Next, the valve 11 is operated to fill the entire supply pipe 9 from the closed container 1 to the nozzle 10 with the coating liquid 3, and then the valve 11 is temporarily closed. The extraction valve 11 is opened, and 3'ft of the coating liquid is dripped from the nozzle 10 onto the surface of the object 1 to be treated, and the rotating shaft 5 of the spinner 2 is rotated. Then, the dropped coating liquid 3 is applied to the surface of the object to be processed 1 to a uniform thickness by centrifugal force.

Here, since the pressurizing gas introduced into the closed container 1 is helium gas or neon gas with low solubility, even if the pressure inside the closed container 1 is increased, only a very small amount dissolves in the coating liquid 3. Even if the pressure is returned to the normal pressure state during dropping, the generation of bubbles in the coating liquid 3 can be suppressed, and the coating liquid 3 can be applied to the object 7 to be treated.
It is applied evenly to the dragon face.

As explained above, according to the present invention, even if a coating liquid is prepared using a highly polar solvent, the coating liquid is fed under pressure, and is dripped onto the surface of the object to be treated under normal pressure, No air bubbles are generated in the coating liquid on the surface of the object to be treated, so that disadvantages such as pinholes and uneven coating do not occur later.

Therefore, the product yield can be greatly increased, and the above can be achieved without providing any special equipment such as a trap.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a schematic side view of a coating device for carrying out the method of the invention. In the drawings, 1 is a closed container, 2 is a spinner, 3 is a coating liquid, 7 is an object to be processed, 8 is a pressure gas introduction pipe, 9 is a coating liquid supply pipe, and 10 is a nozzle.

Claims (1)

[Claims] A coating liquid using a highly polar solvent is filled into a closed container, and a high-pressure gas introduction pipe and a coating liquid supply pipe are placed inside the sealed container, and the lower end of the high-pressure gas introduction pipe is connected to the surface of the coating liquid. The lower end of the coating liquid supply pipe is positioned below the liquid level of the coating liquid, and then helium gas or neon gas is introduced into the sealed container through the high-pressure gas introduction pipe to fill the inside of the sealed container. A method for supplying a coating liquid, characterized in that the pressure is high and the coating liquid is dripped onto the surface of an object to be treated through a supply pipe using the pressure inside a closed container.