JPS63133526A - Application of resist - Google Patents

Abstract

PURPOSE:To lessen the usage of a resist liquid and to contrive to be able to execute a resist application having a superior uniformity by a method wherein a resist is fed on the surface of a wafer in a state that a gas is made to flow out on the surface of the wafer being rotated and a resist film is pressed and spread by the gas. CONSTITUTION:A resist is dripped on the central part of a wafer 13 being standstilled through a resist jet nozzle 15 and after the wafer 13 is turned into a regular rotation by a motor 16 in a short time, a gas feed valve 22 is opened and the mixed gas of nitrogen and a resist solvent, for example, of a flow rate adjusted by a flowmeter 23 is fed in a treating cup 10, and at the same time, while the gas is evacuated by an exhaust valve 18, the safer is further made the regular rotation for a constant time. At this time, the gas flowed in is turned into a uniform flow 25 of gas by the action of a gas flowingout part 24, brings the peripheral part of the wafer in a saturation state with a resist solvent, keeps the viscosity of the resist constantly, and at the same time, makes an action to press and spread uniformly a resist film 19. After the wafer is returned to a standstill state, an upper cup 12 is made to ascent and when the resist film is dried, there is no volatilization of the solvent during the application of the resist and the viscosity of the resist is not changed.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a resist coating method.

(Prior art) When applying resist to a substrate 1 to be coated, for example, a semiconductor wafer, there is a method in which the resist is dropped onto the center of the semiconductor wafer, the wafer is rotated at high speed, and the resist is spread over the wafer surface using centrifugal force. It is being done.

However, resist applied to the surface by centrifugal force
This is because the solvent contained within the resist evaporates from the resist surface and the viscosity of the resist changes.

There is a problem in that coating unevenness and non-uniform film thickness occur on the resist surface after coating.

If the thickness of the resist is not constant in this way, the exposure will not be uniform, and the pattern of the resist will be uneven after development.

As a method for solving this unevenness and non-uniformity of resist coating, there are techniques disclosed below.

For example, the technique disclosed in Japanese Patent Application Laid-Open No. 59-100526 performs resist coating by keeping the resist coating atmosphere temperature below a certain temperature and preventing the volatilization of the solvent; The technique disclosed in 2002-2012 is to perform coating and drying while controlling the amount of exhaust around the resist-coated surface.

Further, the technique disclosed in Japanese Patent Application Laid-Open No. 60-152029 has an upper cup 2 around the wafer 3 as shown in FIG.
A cover consisting of the lower cup 1 surrounds the wafer 3 to form a hermetically sealed state, and cysts are dropped from the dropping nozzle 5 onto the center of the wafer 3. The solvent in the resist evaporates to create a saturated state, and the resist is removed by rotating the Unino A3. The purpose is to make the film uniform.

(Problems to be Solved by the Invention) However, the above-mentioned prior art has the following problems.

In order to maintain the temperature of the resist coating atmosphere below a certain temperature, a large-scale temperature control device is required, and temperature control is also technically difficult.

Next, when controlling the exhaust volume around the resist coated surface, it is difficult to match the wafer rotation speed, exhaust time, exhaust volume, etc., and the control device required to detect and control the exhaust volume is complicated. .

Furthermore, when applying resist with the space inside the cover saturated by volatilization of the solvent in the resist,
Since a saturated state is created by volatilization of the solvent in the resist, a large amount of resist must be dropped in order to obtain a sufficient saturated state.

The present invention was made in response to the above-mentioned circumstances.
The present invention aims to provide a resist coating method that does not require a complicated control device, uses fewer resist layers, and provides excellent uniformity of the resist film.

[Structure of the invention]

(Means for Solving the Problems) That is, the present invention is characterized in that resist is supplied to the surface of the rotating wafer while gas is flowing out onto the surface of the wafer.

(Function) In the resist coating method of the present invention, when the resist is applied onto the substrate by dropping the resist onto the substrate and then rotating the substrate, the gas Equipped with an outflow mechanism, it keeps the area around the substrate to be saturated with the resist solvent by letting out a gas, such as a mixture of nitrogen (N2) and a solvent, and the gas flow presses the resist film. Since the viscosity of the resist does not change and the resist film thickness is flattened, a resist film with excellent uniformity can be formed.

(Example) Hereinafter, the resist coating method of the present invention will be explained based on the drawings.

The processing cup 1 is composed of a lower cup 11 and an upper cup 12, and the upper cup 12 is moved up and down by a lifting device 20 equipped with a moving means such as an air cylinder.
1, it is configured to be detachable at will.

A wafer chuck 14 is disposed inside the processing cup and holds the wafer 13 by suction using, for example, a vacuum chuck, and this wafer chuck 14 is rotated by a motor 16 .

A resist jetting nozzle 15 is provided above the upper cup 12 to face the wafer 13 and drop resist onto the wafer 13.

In addition, a gas outflow mechanism H is provided, which includes a gas supply pipe 21, a gas supply valve 22, a flow meter 23, and a gas outflow section 24, in order to cause gas to flow out into the processing cup.
A gas supply pipe 21 connected to a gas supply valve 22 and a flow meter 23 is connected to the processing cup at the upper part of the upper cup 12.

Further, the gas outflow section 24 is made of, for example, a metal mesh having ventilation holes, and is arranged at the opening of the upper cup 12.

Further, on the bottom surface of the lower cup 11, there is provided a waste liquid pipe 26 for discharging the resist waste liquid, and an exhaust mechanism consisting of an exhaust pipe 17, an exhaust valve 18, an exhaust device (not shown), etc. for exhausting gas from inside the processing cup. It is provided.

In the resist coating apparatus having the above configuration, resist coating is performed in the following manner.

First, the upper cup 12 is raised by the lifting device 20, and a gap is provided between it and the lower cup 11 so that an arm of a transfer device (not shown) can go in and out, and the wafer 13 is placed on the wafer chuck 14 by this transfer device and held by suction. . After that, the lifting device 20 is lowered to bring the upper cup 12 and the lower cup 11 into close contact with each other.

In this case, the lower cup 11 may be lowered instead of raising the second cup 12, and the wafer 13 is carried between the upper cup 12 and the lower cup 11 by relative movement.
Any method may be used as long as it provides enough space for removal.

Then, with the exhaust valve 18 and the gas supply valve 22 closed, resist is dropped from the resist jetting nozzle 15 onto the center of the wafer 13 which is stationary. In this case, the resist dropping nozzle 15 is fixed, but the present invention is not limited to this, and the resist may be dropped while moving the resist dropping nozzle 15.

Next, the motor 16 is rotated at high acceleration to rotate the wafer 13 steadily in a short period of time, and after maintaining the steady rotation state for a while, the gas supply valve 22 is opened and a gas, such as nitrogen (N2) and resist solvent, whose flow rate is adjusted by the flow meter 23, is supplied. The mixed gas is supplied into the processing cup, and at the same time, the exhaust valve is opened to exhaust the air, and the Eva 13 is further rotated steadily for a certain period of time.

At this time, the gas flowing into the upper cup 12 through the gas supply pipe 21 becomes a uniform gas flow 25 as shown in FIG. It saturates the resist with a resist solvent to keep the viscosity of the resist constant, and also acts to uniformly press and spread the resist film.

Then, the resist film is dried only after the gas supply valve 22 and the exhaust valve 18 are closed, the motor 16 is stopped, and the upper cup 12 is raised by the lifting device t20.

Therefore, the viscosity of the resist does not change due to volatilization of the solvent in the resist during application of the resist.

〔Effect of the invention〕

As described above, according to the resist coating method of the present invention, the peripheral area of the wafer can be sufficiently saturated with the solvent.

Furthermore, since the resist film is spread out by gas, the amount of resist solution used is small, and resist coating with excellent uniformity of the resist film can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a resist coating apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional resist coating apparatus. 1.11...lower cup, 2,12...upper cup. 3.13...Wafer, 4.14...Wafer chuck, 5.15...Resist jetting nozzle. 6.16...Motor, 7,17...Exhaust pipe, 18.
...Exhaust valve, 19...Resist film, 20...
- Lifting device, 21... gas supply pipe. 22... Gas supply valve, 23... Flow meter, 24...
...Gas outflow section, 25...Gas flow, 26...
- Waste liquid pipe, 10-... processing cup. U...Gas outflow mechanism, 28...Exhaust mechanism. Patent applicant: Tokyo Electron Ltd. Figure 2

Claims (2)

[Claims] (1) A resist coating method characterized in that resist is supplied to the wafer surface while gas is flowing out onto the rotating wafer surface. (2) The resist coating method according to claim 1, wherein the gas flowing out onto the wafer surface contains a resist solvent.