JPS6223581Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a structure for preventing volatilization of a solvent in a coating liquid in a nozzle portion for dropping a coating liquid (coating diffusion agent, photoresist liquid) in a spin coating device for a substrate (glass, semiconductor wafer).

In the manufacturing process of semiconductor integrated circuits, coating solutions such as diffusion agents and photoresist solutions are mainly applied onto semiconductor wafers using a spindle (rotating disk ) Rotary coating equipment is generally used that coats the entire surface of a semiconductor wafer by utilizing the rotational centrifugal force. This spin coating device attracts and holds a semiconductor wafer on the upper surface of a spindle, drops the coating solution onto the center of the semiconductor wafer surface with the spindle stopped rotating, and then rotates the spindle to perform a centrifugal centrifuge. The force spreads the coating liquid over the entire surface and at the same time scatters unnecessary liquid to the outside of the wafer, forming a diffusion agent film or photoresist film with a uniform thickness on the semiconductor wafer surface.

However, when forming the coating film using an automatic coating device, the coating solution is dropped onto a semiconductor wafer and processed by rotating the spindle, and then the next semiconductor wafer is replaced and the coating solution is applied for a period of time between drops. When this is necessary, the solvent in the coating liquid that is in contact with the atmosphere at the coating liquid nozzle portion evaporates, thereby changing the viscosity of the coating liquid at the nozzle portion.

Even if such a change in viscosity is extremely small, it greatly affects the film thickness when a film is formed by spin coating, causes variations in diffusion concentration when coating with a diffusing agent, and causes uneven film thickness in the case of photoresist. As a result, the exposure of the photoresist is internally distorted, and as a result, accurate exposure cannot be performed, and as a result, it is extremely difficult to obtain a fine pattern with high precision.

Therefore, the purpose of the present invention is to prevent solvent volatilization in the coating liquid at the nozzle and eliminate changes in coating liquid viscosity by changing the structure around the nozzle in automatic coating equipment, thereby increasing the film thickness over the entire surface of the semiconductor wafer. An object of the present invention is to provide an automatic coating device capable of uniformly coating the entire surface.

In accordance with the above object, the present invention has a structure in which the coating liquid dripping nozzle is moved by a first cylinder for a certain distance in the vertical direction in order to prevent solvent volatilization at the nozzle part, and the nozzle is connected to the lower surface of the nozzle to form a sealed structure. The upper open cap allows the solvent to be stored at the bottom of the cap, and the second
It is installed so that it can be moved horizontally by a cylinder,
When not in use, cover the bottom of the nozzle at a certain height above the spindle to maintain a solvent vapor atmosphere around the nozzle at all times.When dropping coating liquid, release the connection between the nozzle and the cap, and close the nozzle. The device is characterized in that it is configured to be lowered close to the top of the substrate and drop the coating liquid thereon.

The present invention will be explained below with reference to the drawings.

Fig. 1 shows a state in which the coating liquid 5 is being dropped onto a semiconductor wafer 1, and Fig. 2 shows a state in which the coating liquid 5 is not being dropped, and the nozzle 4 is covered with a cap 6 in which a solvent is stored at the bottom of the cap. This shows the state in which the solvent is prevented from volatilizing at the nozzle.

To explain the operation in FIGS. 1 and 2, the semiconductor wafer 1 is vacuum chucked by the spindle 2, and as the first cylinder 10 contracts, the nozzle 4 passes through the nozzle support rod 9 and descends close to the semiconductor wafer 1. The coating liquid 5 is dropped from the nozzle 4. When the dripping is finished, the nozzle 4 moves to the upper limit by extending the first cylinder 10, and then by extending the second cylinder 8, the cap 6 moves to below the nozzle 4 through the cap support rod 7. If the air supply ports at both ends of the first cylinder 10 are opened, the nozzle 4 and the nozzle support rod 9 will descend due to their own weight, so the nozzle 4 can be covered by the cap 6. And again,
Next, when dropping the coating liquid, use the first cylinder 10.
By extending the nozzle 4 and moving the nozzle 4 to the upper limit, and then retracting the second cylinder 8, the cap 6 is separated from the nozzle 4. Then, by retracting the first cylinder 10, the nozzle 4 is lowered to the lower limit, and the coating liquid 5 is released. Drip.

By repeating the above steps, it is possible to drop a coating liquid with a constant viscosity even if the drop interval changes, so that a uniform coating film can be formed. Furthermore, since the nozzle 4 can move up and down, the coating liquid can be dropped as close as possible to the semiconductor wafer 1, which reduces the volatilization of the solvent when the coating liquid is dropped. It is possible to form a uniform coating film with no uneven coating even with a coating/diffusing agent using .

FIG. 3 shows an enlarged view of the nozzle 4 covered with the cap 6. When the nozzle 4 is covered with the cap 6, the solvent 11 and the coating liquid 5 are deposited in the area surrounded by the nozzle 4 and the cap 6. As more solvent evaporates, it gradually fills up, and when it reaches a saturated state, it no longer evaporates, making it possible to prevent an increase in viscosity.

The present inventor conducted a coating experiment on a semiconductor wafer using a coating dispersion agent using an alcohol solvent as a coating solution, and using alcohol as a solvent.
With the conventional method that does not use a cap, the viscosity of the solvent at the nozzle changes in the two minutes it takes from one drop of the coating dispersant to the next, resulting in uneven coating on semiconductor wafers. When using the coating dispersion agent mentioned above, even after 12 hours have elapsed from one drop of the coating dispersion agent to the next, the viscosity of the nozzle part does not change, resulting in uneven coating on the semiconductor wafer. I didn't.

As explained above, according to the present invention, it is possible to prevent solvent volatilization of the coating solution and eliminate local changes in viscosity, so even if the interval between drops of the coating solution changes, the coating film thickness remains constant. When applying a diffusing agent, a uniform diffusing agent film can always be formed.
This eliminates variations in diffusion concentration, making it possible to create semiconductors with uniform characteristics. Furthermore, in the case of photoresist coating, a uniform and even photoresist film can always be formed, so the effect is remarkable especially when a fine pattern is required.

The present invention is not limited to semiconductor wafers, and similar effects can be obtained even when applying a coating liquid to substrates such as glass masks and other metal plates.

[Brief explanation of the drawing]

The drawings are cross-sectional views showing the present invention. Figure 1 is an explanatory diagram showing the state in which the coating liquid is being dropped onto a semiconductor wafer, and Figure 2 is an illustration of the nozzle being covered with a cap to prevent solvent volatilization. FIG. 3 is an enlarged view of the nozzle covered with a cap. 1... Semiconductor wafer, 2... Spindle, 3...
... saucer, 4 ... nozzle, 5 ... coating liquid, 6 ... cap, 7 ... cap support rod, 8 ... second cylinder, 9 ... nozzle support rod, 10 ... first cylinder, 11 ... Solvent, 12...Solvent vapor, 13
...Hose, 14...Container.

Claims (1)

[Scope of utility model registration request] In addition to installing a downward facing nozzle for dispensing the coating liquid at a position above the spindle so that it can be moved a certain distance in the vertical direction by the first cylinder, a cap is installed at the bottom of the cap to cover the bottom surface of the nozzle and create a sealed structure. The solvent is stored in the nozzle, and it is moved horizontally by a second cylinder.When not in use, the bottom surface of the nozzle is covered at a certain height above the spindle to create a solvent vapor atmosphere around the nozzle. When the coating liquid is dripped, the second cylinder is activated to release the connection between the nozzle and the cap, and the first cylinder is activated to lower the nozzle as close to the substrate as possible, allowing the coating liquid to drip. A rotary coating device characterized in that it is configured so that it can be coated.