JPH0152065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of dripping and supplying a coating liquid onto an object to be processed 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 a silicon wafer or glass, nitrogen gas is introduced into a sealed container containing a coating solution. A method is adopted in which the interior of the container is kept under 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 order to form In this case, the following problems occur.

In other words, if the pressure inside a closed container is made high with nitrogen gas, Henry's law states that the mass of gas dissolved in a certain amount of liquid at a certain temperature is proportional to the pressure of that gas. In particular, the Ostwald absorption coefficient (solubility) of nitrogen gas is high, so a large amount of nitrogen gas is 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. However, by applying the coating with the air bubbles present, the air bubbles are fixed in the film.

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

In order to solve this problem, it may be 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 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 is that the coating liquid is force-fed 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 an airtight container, and 2 is a spinner. The airtight container 1 is filled with a coating liquid 3 adjusted with a highly polar solvent, and the bottomed cylindrical body 4 of the spinner 2 is filled with a rotating shaft 5 from below. A spinner head 6 is attached to the tip of the rotating shaft 5, and an object 7 to be processed, 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.
The lower end of the supply pipe 9 is located above the liquid level of the coating liquid 3, and the lower end of the supply pipe 9 is located below the liquid level and near the bottom of the closed container 1. Further, at the other end of the supply pipe 9, there is a nozzle 1 for dropping the coating liquid.
0 is attached, and this nozzle 10 faces above the spinner head 6. Furthermore, a valve 11 driven by high-pressure air or the like and a suction 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 coating liquid 3 is filled into the closed container 1 and left to stand for defoaming, and at the same time, the object to be processed 7 is placed on the spinner head 6 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. Then, valve 11
is operated to fill the entire supply pipe 9, that is, the 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. After that, the valve 11 is opened, and the coating liquid 3 is dripped from the nozzle 10 onto the surface of the object to be processed 7, 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 7 to a uniform thickness by centrifugal force.

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

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, There are no bubbles in the coating liquid on the surface of the object to be treated, and therefore disadvantages such as pinholes and uneven coating do not occur later.
Therefore, the yield of products can be greatly improved, and furthermore, the above can be achieved without providing any special equipment such as a trap, etc., and many other effects are exhibited.

[Brief explanation of drawings]

The drawing is a schematic side view of a coating device for carrying out the method of the invention. In addition, in the drawing, 1 is a closed container, 2 is a spinner, and 3 is a closed container.
is a coating liquid, 7 is an object to be treated, 8 is a high-pressure gas introduction pipe,
9 is a supply pipe for the coating liquid, and 10 is a nozzle.

Claims (1)

[Claims] 1 Fill a sealed container with a coating liquid using a highly polar solvent, place a high-pressure gas introduction pipe and a coating liquid supply pipe facing into the sealed container, and connect the lower end of the high-pressure gas introduction pipe to the coating liquid. The lower end of the coating liquid supply pipe is positioned above the liquid level of the coating liquid, and then helium gas or neon gas is introduced into the sealed container via the high-pressure gas introduction pipe to cause the inside of the sealed container to rise. A method for supplying a coating liquid, characterized in that the pressure inside the sealed container is set at high pressure, and the coating liquid is dripped onto the surface of the object to be treated through a supply pipe.