JPS6250194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spin coating method and a spin coating device, and mainly relates to a spin coating method and a spin coating device for efficiently coating a photosensitive resin (hereinafter referred to as photoresist) on a semiconductor material substrate mainly in a photoetching process which is one of the manufacturing processes of semiconductor devices. The present invention provides a photoresist coating method and coating device that can form a uniform film and can be easily automated.

A conventional general photoresist coating method and a schematic structure of its apparatus will be explained with reference to the schematic perspective view of FIG.

A semiconductor substrate (hereinafter simply referred to as a substrate) 1 of the material on which a photoresist film is to be formed is installed and fixed on a rotary stage 2 of an applicator (hereinafter referred to as a spinner) by a method such as vacuum suction, and connected to a photoresist supply tank 3. A small amount of photoresist 5 is dripped onto the substrate 1 from the dripping nozzle 4 . Note that, in addition to the method described above, a method using a syringe or the like is also used for dropping photoresist. Thereafter, the rotation stage 2 rotates the motor 7 at high speed via the connected shaft 6, thereby applying the photoresist 5 on the substrate 1 onto the surface of the substrate 1 by centrifugal force.

The disadvantages of this conventional method are: (1) It is necessary to provide a partition wall 8 to prevent excess photoresist removed from the substrate surface due to rotation from scattering; is reflected by the wall surface, and a part of it becomes semi-hardened gel-like particles and falls onto the surface of the substrate 1 again, inhibiting the formation of a homogeneous coating film. Particularly in recent years, when attempting to increase the density and integration of integrated circuit devices, homogenization of the photoresist coating film has become an important issue.
The non-uniform coating film as described above is the main cause of defects such as pattern collapse.

(2) With the method of supplying photoresist dropwise from the supply tank 3 to the droplet nozzle 4 through the thin tube 9 as shown in Figure 1, there is almost no problem in continuous use;
When used intermittently, only a small amount of photoresist remains in the dripping nozzle 4, which tends to cause viscosity changes such as an increase in viscosity due to the influence of the surrounding conditions.In addition, the photoresist may harden at the nozzle tip. Difficult to maintain quality.

(3) Furthermore, it is well known that when a syringe or the like is used, the operability and the ratio of the loss amount to the actual amount of photoresist used are high.

In view of these problems, the present invention is characterized in that the substrate is placed facing downward to face the surface of the coating liquid, and the coating liquid is sprayed from an injection port installed in the coating liquid, thereby overcoming the defects of the conventional coating method. The present invention will now be described in detail by way of examples.

FIG. 2 shows the basic configuration of a spin coating device according to an embodiment of the present invention, and this device and spin coating method will be explained using this figure. In this apparatus, as shown in FIG.
3 is provided. The injection pipe is connected via a valve 15 to a pressurizing device (not shown), such as a high-pressure gas generator. Photoresist 501 is stored in the liquid chamber 12, and high pressure gas is sent to the injection piping to inject the photoresist. By adjusting the pressure, for example, making it weaker, the liquid level can be made partially convex,
Also, by increasing the strength, droplets can be jetted above the liquid surface. A rotary stage 17 is provided directly above the photoresist tank 11 in a state facing the liquid level 16 (a state in which the rotary stage of a normal spinner is inverted), and the rotary stage 17 is coupled to a main shaft 18. The other end of the main shaft 18 is connected to a sliding mechanism (not shown) for moving the main shaft 18 and the rotation stage 17 up and down, and the rotational force of the motor 701 is also applied to a part of the main shaft 18 to the rotation stage 17. Sliding rotational force transmission mechanism 2
0 and 20' are constructed by mechanisms such as gears or pulleys. That is, by providing the above mechanism, a structure is formed in which the rotation stage connected to one end of the main shaft changes its relative position with respect to the photoresist liquid level 16 while rotating.

In the above configuration, after fixing the substrate 101 to the rotary stage 17 with the surface to be coated of the material substrate 101 facing downward, the material substrate 101 and the rotary stage 17 are attached to the main shaft 18. Using a sliding mechanism provided at the other end, pressurized gas is introduced into the injection pipe 13 installed at a position () close to the photoresist liquid level 16, and the photoresist is injected onto the material substrate 101.
Adhere to the surface.

Next, the pressure of the pressurized gas is reduced to stop the injection of photoresist, and the rotation stage 17 is driven by the motor 701.
At the same time, the rotating stage 17 is pulled up to position ( ) by a sliding mechanism (not shown) connected to the main shaft 18, and a photoresist coating film is applied onto the surface of the material substrate (the downward surface in FIG. 2). form.

In the photoresist coating method using the spinner shown in Fig. 2, centrifugal force immediately after the start of rotation causes
Most of the photoresist that has left the surface of the substrate 101 and remains in a liquid state is collected into the photoresist liquid chamber 12, and the semi-cured photoresist that has left after the rotation progresses and the approximately coating film is formed on the substrate. The excess resist, which is in a gel state and cannot be reused, is separated from the substrate at position ( ) and is therefore separated and collected in the surrounding tank 21 . Therefore, compared to conventional methods in which most of the photoresist dropped onto the surface of the material substrate does not contribute to the coating film and is discarded as surplus photoresist, the apparatus shown in Figure 2 uses the photoresist more efficiently. It will be greatly improved.

In addition, to solve the conventional problem that semi-hardened gel particles reflect on the peripheral wall surface and fall onto the coated film surface of the material substrate, impairing the smoothness of the coated film surface, in the present invention, the coated film surface is directed downward. This prevents gel-like particles from falling and re-depositing onto the surface of the coating film, resulting in a homogeneous coating film.

As described above, according to the present invention, a homogeneous coating liquid film can be formed, and the efficiency of resist use can be greatly improved.

Next, another embodiment of the coating device for further enhancing the effects of the present invention will be described with reference to FIG. As shown in the schematic cross-sectional view of FIG. 3, the structure is such that an outer enclosure 21 is provided outside the photoresist liquid tank of the embodiment shown in FIG. . When the main shaft 18 that connects the rotary stage 17 and the motor 19 slides up and down (the coupling mechanism and sliding mechanism are not shown), that is, while the rotary stage 17 moves from position () to position (), the movable shield plate 22
maintains an open state and does not impede the sliding movement of the rotation stage 17 and the material substrate 101 fixed to the stage. However, when the rotation stage 17 is in positions () and (), Part 23
The structure is such that the interior of the tank 24 is kept in a nearly closed room atmosphere.

In addition, by storing a diluted solution 26 of the photoresist solution 12 (or a solution with a similar composition to the diluted solution) in the envelope chamber 25 formed by the photoresist solution chamber 11 and the envelope tank 21, the interior of the tank 24 is The evaporated gas of the liquid maintains the atmosphere of the diluted liquid composition, making it possible to suppress compositional changes (hardening) at the liquid level 16 of the photoresist liquid 12 in the photoresist liquid chamber 11. Further, due to the presence of this evaporated gas, spin coating is performed in the same gas atmosphere, and a homogeneous coating film can be obtained with good reproducibility due to effects such as controlling the coating atmosphere.

The process of applying photoresist using this apparatus is as follows. First, the silicon semiconductor substrate 101 is fixed to the rotation stage 17 at the rotation stage position ( ) by vacuum suction or the like. At this time, the movable bulletproof plate 22 is in a completely closed state, and the inside of the tank 24 maintains a sealed atmosphere. Next, the movable bulletproof plate 22 is temporarily opened, and the rotary stage 17 to which the substrate 101 is fixed is lowered to position () by a sliding mechanism (not shown), and then the movable bulletproof plate 22 is moved to the main shaft penetrating part. The hole is sealed until it is almost closed, leaving an opening of 23.

Thereafter, pressurized gas is introduced through the valve 15 and photoresist is sprayed to adhere the photoresist to the surface of the substrate. Next, as in the case of Embodiment 1 shown in FIG. 2, the rotating stage 17 is moved to position () by the sliding mechanism, and rotational force is applied by the motor 701, so that the rotation stage 17 is placed on the surface of the substrate 101 at position ().
A spin coating film of photoresist is formed.

After the rotational coating is completed, the movable shielding plate 22 is opened again, and the rotation stage 17 is moved to the position () outside the bath, and the material substrate 1 on which the photoresist film has been formed is moved.
01 is removed and the coating process ends.

In addition, the sliding speed when sliding the rotary stage from position () to position () is slowed down, and the rotation speed is changed so that it rotates at a low speed immediately after sliding starts, and rotates at a high speed after reaching position (). If a coating method is adopted, in the first rotational speed (low speed) region, the photoresist is spread over the substrate surface, and excess liquid photoresist is collected in the photoresist liquid chamber 11, and in the high rotational speed region at position (), the photoresist is spread on the substrate surface. A photoresist film is uniformly formed on the surface, and the efficiency of using the photoresist can be further improved.

Furthermore, since the coated surface faces downward, even if a large amount of photoresist is deposited or coating is performed at low speed, unlike the conventional example, the photoresist will not wrap around to the back surface.

In this example, the formation of a photoresist film on a semiconductor substrate is taken as an example, but this coating apparatus can be used in addition to the above-mentioned photoresist coating if it is used to form a coating film using a liquid substance with high viscosity. As in the example, a homogeneous film can be easily formed.

As described above, in the photoresist coating method using the method and apparatus of the present invention, since the coated surface of the photoresist faces downward, the gel-like particles of excess resist reflected from the peripheral wall surface do not fall onto the coated surface. Without,
Therefore, process defects such as poor surface smoothness of the photoresist and pattern collapse due to these impurities are prevented. Further, according to the present invention, excess liquid resist is collected in the resist liquid chamber, so that it is possible to exhibit a great effect in reducing waste of photoresist. Further, in the present invention, since the injection port is installed in the liquid, unlike the conventional example, even when used intermittently, the viscosity of the photoresist in the injection port does not change, and a uniform photoresist can be constantly applied.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of a conventional photoresist coating apparatus, and FIGS. 2 and 3 are sectional structural views of photoresist coating apparatuses according to embodiments of the present invention, respectively. 11...Photoresist tank, photoresist liquid chamber,
13...Injection piping, 17...Rotation stage, 1
8...Main shaft, 20, 20'...Rotational force transmission mechanism,
21... Surrounding tank, 25... Surrounding chamber, 26... Diluent, 101... Material substrate, 501... Photoresist.

Claims (1)

[Scope of Claims] 1. Spraying and depositing a coating liquid on the substrate with the surface to be coated of the material substrate facing downward, and then rotating the substrate to form a film of the coating liquid adhered to the surface to be coated. A rotary coating method characterized by: 2. The spin coating method according to claim 1, wherein the material substrate is rotated with the surface to be coated facing downward. 3. The spin coating method according to claim 1, wherein the coating is formed in an atmospheric gas that dilutes the coating solution. 4. The spin coating method according to claim 1, wherein the material substrate is a semiconductor substrate and the coating is a photoresist coating. 5. An injection pipe installed in the liquid chamber for storing the coating liquid, a rotary table installed above the coating liquid surface so that the coated film forming surface of the material substrate faces the coating liquid surface, and A rotary coating device comprising a rotary drive mechanism for rotating a base, applying pressure in the spraying pipe to spray the coating liquid, and causing the coating liquid to adhere to the surface on which the coating film is to be formed. 6. An injection pipe installed in the liquid chamber for storing the coating liquid, a rotary table installed above the coating liquid surface so that the coated film forming surface of the material substrate faces the coating liquid surface, and A rotation drive mechanism for rotating the table, and a rotation drive mechanism provided on the outer periphery of the liquid chamber in which the coating liquid is stored.
It is equipped with an outer peripheral tank in which a diluted coating solution is stored and a shielding plate provided on the upper part of the outer tank so that it can be opened and closed. A rotary coating device characterized by attaching a liquid to a surface on which a coating film is to be formed.