JPH03175616A - Spin applying apparatus - Google Patents

Abstract

PURPOSE:To form the thickness of a film on a wafer uniformly by the spin application of highly volatile treating liquid by providing a spin chuck, a nozzle, a specified air-temperature control means, a specified concentration control means, a control means and an evacuation means. CONSTITUTION:A spin chuck 3 is rotated with a wafer being held. A nozzle 5 supplies treating liquid to the central part of the wafer 2. A clean-air- temperature control means 13 forms air whose temperature is adjusted to a preset value. A concentration control means 14 forms solvent whose concentration is adjusted to a preset value. A control means supplies solvent vapor on the wafer 2 from the above described concentration control means 14 in the applying stage, ventilates the inside of a treating chamber for forming application atmosphere when the application is finished and supplies air from the above described air-temperature control means 13 at the following drying stage. A forced chamber evacuation means 19 exhausts the solvent vapor or air which is supplied to the wafer 2. When these means are provided, the accuracy of the thickness of the applied film can be improved even if the volative treating liquid is used.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a technique for coating a rotating wafer by discharging a processing solution, particularly for coating a highly volatile processing solution in a solvent atmosphere. It is about effective techniques.

[Conventional technology]

For example, in wafer exposure using light, a wafer with an oxide film, nitride film, metal film, etc. be transferred.

One of the above resist coating methods is spin coating.
The general structure is that a wafer is placed horizontally in a closed space, and as the wafer is rotated, a resist processing solution is discharged toward the wafer surface from a nozzle placed on the center of rotation.The centrifugal force generated by the rotation It is possible to form a uniform resist film on the wafer surface using this method.

By the way, the present inventor has studied the redeposition of the processing liquid scattered from the wafer during spin coating and the non-uniformity of the drying state of the processing liquid on the wafer.

The following are the techniques studied by the present inventor, and the outline thereof is as follows.

That is, a spin coating apparatus using a spin coating method has a configuration as shown in FIG. A chuck 3 is installed, and a motor 4 is provided as its rotational drive source. Further, a nozzle 5 is provided on the center line of the wafer 2 for discharging a resist processing liquid onto the surface of the wafer 2. Further, an inclined surface 1a is provided at a portion of the coating cup 1 facing the periphery of the wafer 2, so that the resist processing liquid scattered from the wafer 2 can easily fall downward.

When resist coating is performed using this apparatus, the wafer 2 that has been dehydrated is held on the spin chuck 3 (held by vacuum suction), and the motor 4 is energized to rotate the wafer 2 at a constant speed. Next, the resist treatment liquid is discharged from the nozzle 5 to adhere to the surface of the wafer 2. At the same time, air-conditioned air at a constant temperature is blown from above the coating cup 1 to flow down the periphery of the wafer 2 (hereinafter, this means is referred to as cup exhaust).

Since the wafer 2 is rotating, the resist processing liquid adhering to the surface flows in the circumferential direction and at the same time flows out in the peripheral direction due to the centrifugal force of the rotation. The excess resist processing liquid that has reached the edge of the wafer 2 flies toward the inclined surface 1a,
Most of it adheres to the inclined surface 1a, and some of it rebounds and flies towards the wafer 2 again, but it is swept downward by the air supplied from above and is prevented from adhering to the wafer 2.

Note that highly volatile processing liquids (e.g. photoresist,
When applying ECA (ethyl cellosolve acetate), SOG nisbin on glass, etc., if the air contact conditions differ locally, there will be differences in the degree of drying, and this will appear as a difference in film thickness. . Therefore, in order to make the film thickness uniform, it has been proposed to apply the treatment liquid in a solvent atmosphere (for example, Japanese Patent Laid-Open No. 63
There is one described in Publication No.-72373>.

[Problem to be solved by the invention]

However, when spin coating is performed using a highly volatile processing liquid as described above, the liquid viscosity increases as the processing liquid that drops directly below the nozzle stretches to the periphery of the wafer. Because it concentrates in the surrounding areas, the surrounding areas will dry out faster. The inventors have discovered that as a result, the coating film thickness differs between the center and the periphery of the wafer, deteriorating the film thickness accuracy.

As a solution to this problem, as in the above-mentioned known example,
It is conceivable to apply the treatment liquid in a solvent atmosphere, but this poses a problem of delayed drying and is currently difficult to put into practical use. Therefore, the conventional method was to control the temperature of the processing liquid, but in coating equipment that handles multiple processing liquids, even if temperature control is performed, the coating film thickness cannot be controlled for all processing liquids. It is difficult to make it uniform.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a technique that can uniformly form a spin coating film on a wafer using a highly volatile processing liquid.

The above objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, a spin chuck that rotates while holding a wafer, a nozzle that supplies a processing liquid to the center of the wafer, an air temperature control means that generates air whose temperature is adjusted to a set value, and an air temperature control means that adjusts the concentration to the set value. a concentration control means for producing a solvent, and a concentration control means for supplying solvent vapor onto the wafer from the concentration control means in the coating stage, ventilating the inside of the processing chamber forming a coating atmosphere upon completion of the coating, and supplying the solvent vapor from the concentration control means onto the wafer in the subsequent drying stage; The structure includes a control means for supplying air from the temperature control means and an exhaust means for exhausting the solvent vapor or air supplied onto the wafer.

[Effect]

According to the above-mentioned means, solvent vapor is supplied from the concentration control means to the atmosphere in which the wafer is placed before coating.

The processing liquid is then supplied onto the rotating wafer.
This continues to be spread over the entire surface of the wafer by centrifugal force to form a desired film thickness.

Thereafter, the atmosphere in which the wafer is installed is ventilated with air supplied from the air temperature control means, and the processing liquid on the wafer is dried by the subsequently supplied air. Therefore, even when a volatile processing liquid is used, the difference in film thickness in the radial direction of the wafer can be reduced, and the accuracy of the coating film thickness can be improved.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of a spin coating apparatus according to the present invention. Note that in FIG. 1, the same reference numerals are used for the same parts as used in the explanation of FIG. 2, and therefore, duplicate explanations will be omitted below.

A coating cup 6 having an opening at the center of the upper part and an annular opening at the lower part is arranged with the spin chuck 3 at the center. A conical diffusion section 7 having cylindrical bodies standing upright at predetermined intervals around the periphery is disposed in the upper opening. Furthermore, a processing chamber 8 is arranged to enclose the application cup 6 and the diffusion section 7, and the openings of each of the application cup 6 and the diffusion section 7 are exposed from the processing chamber 8.

The upper end of the diffusion section 7 is connected to a pipe 9 and a pipe 10, and a damper 11, 12 is provided at the base pipe of this connection part. A clean air temperature controller 13 that maintains air from an air supply source (not shown) at a constant temperature is connected to the pipe 9, and a clean air temperature controller 13 that maintains the air from a solvent storage source (not shown) to a set concentration is connected to the pipe 10. A solvent atmosphere concentration controller 14 is connected.

A branch pipe 15 for bypassing air is connected to the pipe 9 near the damper 11, and a damper 16 is disposed within the branch pipe 15. Furthermore, a short pipe 17 that can communicate with the outside air is provided on the ceiling of the processing chamber 8, and a leak valve 18 is disposed within this pipe 17. Further, at the bottom of the processing chamber 8, a chamber forced exhaust device 19 is provided for forcibly discharging the vaporized solvent and air inside the chamber.
is installed.

Further, in order to detect the temperature of the air supplied to the coating cup 6, a temperature sensor 20 is attached to the pipe 9 near the damper 11, and a concentration sensor 21 is attached to the processing chamber 8 to detect the solvent concentration in the processing chamber 8. attached to the side wall.

Next, the operation of the embodiment with the above configuration will be explained.

First, the damper 11 and the leak valve 18 are closed, the chamber forced exhaust device 19 is stopped, and the damper 12 and the damper 1 are closed.
Leave 6 open. Here, the wafer 2 is placed on the spin chuck 3.
The clean air temperature controller 13 and the solvent atmosphere concentration controller 14 are operated, and the application cup 6 is
Solvent vapor is supplied into the tank, and air is discharged to the atmosphere from the branch pipe 15. As a result, the inside of the coating cup 6 is made into a solvent atmosphere. The concentration of the solvent in the coating cup 6 is monitored by the concentration sensor 21, and when the detected value by the concentration sensor 21 reaches the set concentration, the processing liquid is discharged from the nozzle 5 and application of the processing liquid to the surface of the wafer 2 is started. do.

The processing liquid on the wafer 2 spreads around the wafer 2 as the wafer 2 rotates. However, since the applied treatment liquid is in a solvent atmosphere, drying does not proceed. The supply of the processing liquid from the nozzle 5 is stopped at the discharge setting time.

The film thickness is determined by changes in the rotational speed of the motor 4, the energization time, and the concentration setting value of the solvent atmosphere concentration controller 14. When the film thickness reaches the set value, the dampers 12,1
6 is closed, the damper 11 and the leak valve 18 are opened, the supply of solvent to the coating cup 6 is stopped, and air is introduced instead.

At the same time, the chamber forced exhaust device 19 is operated.

As a result, air from the clean air temperature controller 13 flows into the diffusion section 7 and is drawn out from the bottom of the coating cup 6 while contacting the surface of the wafer 2 . At this time, the solvent remaining in the applicator cup 6 is also discharged by the air flow. The air flowing into the diffusion section 7 is monitored by a temperature sensor 20, and the temperature is controlled by a clean air temperature controller 13 so that the detected value becomes a set temperature.

On the other hand, as the forced exhaust device 19 in the chamber is operated and the leak valve 18 is opened, the solvent present in a gaseous state is drawn out by the negative pressure generated in the processing chamber 8, and at the same time, a leak is caused in the processing chamber 8. Outside air is introduced via valve 18.

This allows the application cup 6 and the processing chamber 8 to be ventilated.

Next, the chamber forced exhaust device 19 is stopped, and the leak valve 18 is closed. As a result, a drying processing atmosphere is formed in the application cup 6 and the processing chamber 8 only by the air supplied from the clean air temperature controller 13. This air is controlled to maintain a constant value using the force detected by the temperature sensor 20 as a feedback signal. The air supplied into the coating cup 6 dries the processing liquid on the wafer 2 .

In the above embodiment, the wafer 2 is rotated at a constant speed for a certain period of time, and thereafter dried by air supplied from the clean near temperature controller 13. A configuration may be added that applies vibration to the wafer and then rotates the wafer again to uniformly form a film in a pattern with high steps.

Above, the invention made by the present inventor has been specifically explained based on Examples, but it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. stomach.

For example, by changing the rotation time of the wafer during coating, it is possible to form a film with a wide range of thickness while using a processing liquid of a constant viscosity.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical ones are as follows.

That is, a spin chuck that rotates while holding a wafer, a nozzle that supplies a processing liquid to the center of the wafer, an air temperature control means that generates air whose temperature is adjusted to a set value, and an air temperature control means that adjusts the concentration to the set value. and a concentration control means for supplying the solvent onto the wafer from the concentration control means in the coating stage, ventilating the inside of the processing chamber forming a coating atmosphere upon completion of the coating, and controlling the air temperature in the subsequent drying stage. Since the control means for supplying air from the control means and the exhaust means for exhausting the solvent or air supplied onto the wafer are provided, even when a volatile processing liquid is used, the film thickness in the radial direction of the wafer can be reduced. The difference can be reduced, and the accuracy of coating film thickness can be improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a spin coating apparatus according to the present invention, and FIG. 2 is a sectional view showing an example of a conventional spin coating apparatus. DESCRIPTION OF SYMBOLS 1... Application cup, la... Inclined surface, 2... Wafer, 3... Spin chuck, 4... Motor, 5...
・Nozzle, 6... Application cup, 7... Diffusion part, 8.
...Processing chamber, 9.10.17...Piping, 11.
12 16... Dumper, 13... Clean air temperature controller, 14... Solvent atmosphere concentration controller, 15... Branch pipe, 18... Leak valve, 19...
Chamber internal forced exhaust device, 20... Temperature sensor, 21
...Concentration sensor.

Claims (1)

[Claims] 1. A spin chuck that rotates while holding a wafer;
a nozzle for supplying a processing liquid to the center of the wafer; an air temperature control means for generating air whose temperature is adjusted to a set value; and a concentration control means for generating a solvent whose concentration is adjusted to the set value; control means for supplying solvent vapor onto the wafer from the concentration control means, ventilating the inside of the processing chamber forming a coating atmosphere upon completion of coating, and supplying air from the air temperature control means in the subsequent drying stage; 1. A spin coating apparatus comprising: exhaust means for exhausting solvent vapor or air supplied onto a wafer. 2. The spin coating apparatus according to claim 1, wherein the processing liquid is highly volatile. 3. The spin coating apparatus according to claim 1, wherein the concentration control means adjusts the concentration according to a required film thickness. 4. The spin coating apparatus according to claim 1, wherein the rotation of the spin chuck is changed depending on the required film thickness. 5. In the coating process, means for applying ultrasonic vibration to the processing liquid on the wafer is provided.
Spin coating apparatus as described. 6. The atmosphere in which the wafer is installed includes a coating cup having an air flow passage and the spin chuck disposed in the center, and a closed space surrounding the coating cup and allowing outside air to be introduced and exhausted. 2. The spin coating apparatus according to claim 1, further comprising a processing chamber for forming a spin coating apparatus.