JPS63250820A - Coating device - Google Patents

Abstract

PURPOSE:To make the thickness of a coating film uniform by a method wherein a resist temperature adjuster is provided to slightly raise the temperature of resist immediately before it is dripped corresponding to the temperature of wafer chuck. CONSTITUTION:A resist temperature controller 10 whereto temperature data for wafer chuck are inputted from a chuck temperature sensor 8 transmits control signals conforming to the data to slightly raise the temperature of resist solution 6 higher than the temperature of wafer chuck to a resist temperature adjuster 9. As soon as the relation between temperatures of dripping resist solution 6 and a wafer 5 is properly adjusted, the resist solution 6 is dripped on the wafer 5 to be diffusion-coated. Thus, the evaporation of solvent is made almost constant to almost equalize the viscosity of resist solution for the whole term of coating process. Through these procedures, a coating film of resist solution 6 to be extended by centrifugal force can be formed to be uniform as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a coating device for uniformizing the thickness of a resist film coated on a wafer.

(Prior Art) FIG. 3 is a longitudinal sectional view showing a conventional coating device disclosed in, for example, Japanese Patent Laid-Open No. 137322/1983. This coating device is equipped with a processing cup (1), and this processing cup (
A wafer chuck (2) is provided inside the wafer chuck (1) so as to be rotated by suitable drive means (not shown).

The processing cup (1) has an air supply port (3
) is opened, and an exhaust port (14) is opened at a position outside the wafer chuck (2) on the lower surface of the processing cup (1). Directly above the center of the wafer chuck (2) in the processing cup (1) is a resist dropping nozzle (4) for dropping a resist liquid (6) as a coating material.
is inserted, a supply path (7) for resist liquid (6) is connected to the nozzle (4), and a temperature regulator (9) is interposed in the middle. A controller (10) is connected to the temperature regulator (9).
A liquid temperature detector (11) for detecting the temperature of the resist liquid (6) in the dropping nozzle (4) is connected to the negative input end of the resist liquid (6).

On the other hand, inside the processing cup (1), a temperature detector (12) for detecting the temperature of the surrounding air is arranged, and the temperature detector (12) is connected to the input end of the controller (10). There is.

The controller (lO) detects the liquid temperature detector (11) and the air temperature! Based on the detection results with (12), resist solution (6
) is configured to adjust and control the temperature regulator (9) so that the temperature of the processing cup (1) becomes equal to the ambient temperature of the processing cup (1).

Next, the operation of the conventional coating apparatus having the above configuration will be described with a focus on temperature control of the resist liquid.

The wafer (5) is placed on the wafer chuck (2) and held by a predetermined holding means, and the wafer (5) is rotated.

When the resist solution (6) is dropped from the dropping nozzle (4) onto the center of the rotating wafer, the resist solution (6) is dispersed in the radial direction by centrifugal force and is coated on the surface of the wafer (5). It turns out.

At the start of dropping, the resist liquid (6
) temperature and temperature sensor (12) from the treatment cup (1)
For example, if the temperature of the resist solution (6) is lower than the ambient temperature, the controller (
lO) heats the resist solution (6) by using a temperature regulator (9). The liquid temperature detector (11) indicates that the temperature of the resist liquid (6) has become equal to the ambient temperature due to this heating.
When confirmed by the output of the temperature sensor (12),
The controller (10
) adjusts the temperature regulator (9).

When the temperature of the resist solution (6) and the ambient temperature of the processing cup (1) become equal, the resist solution (6) that is dropped and diffused onto the wafer (5) is prevented from being heated or cooled. Therefore, the evaporation of the solvent becomes approximately constant, and therefore the viscosity of the resist solution (6) is approximately chemotactic throughout the entire application period. Since the viscosity is constant, the coating film of the resist liquid (6) that is spread by centrifugal force is uniformly formed over the entire area.

[Problem that the invention seeks to solve]

Conventional coating equipment attempts to make the resist film thickness uniform on the wafer by matching the temperature of the resist solution and the atmosphere inside the processing cup. The film thickness is not necessarily uniform due to the influence of the temperature distribution between the resist and the surrounding area, which is affected by the ambient temperature inside the processing cup.For example, when the resist temperature and the ambient temperature are equal to 24°C. As shown in FIG. 2A, the film thickness tends to be thinner at the center of the wafer and thicker at the periphery.For example, when the average film thickness is 10000A, the variation σ is 20 to 25A.

This is not necessarily a satisfactory level for fine patterns. Furthermore, both the wafer and the tip of the resist dropping nozzle are exposed to the atmosphere inside the cup, and controlling the ambient temperature is effective in keeping the wafer and the tip of the resist dropping nozzle at the same temperature. It is difficult to selectively apply and control a temperature difference between the tip and the wafer.

This invention was made to solve these problems, and it is possible to make the thickness of the coating film uniform by adjusting the temperature of the tip of the resist dropping nozzle according to the temperature of the wafer chuck. The purpose is to obtain a coating device that can.

('Means for Solving the Problems) The coating apparatus according to the present invention is provided with a sensor that detects the temperature of the wafer chuck, and is also equipped with a resist temperature regulator that controls the temperature of the tip of the resist dropping nozzle based on the temperature information of this sensor. It was established.

[Effect]

The resist temperature regulator of the present invention slightly increases the resist temperature just before dropping according to the temperature of the wafer chuck, so that the temperature of the resist solution becomes a temperature at which the evaporation of the solvent on the wafer can be constant. The viscosity is approximately chemotactic over the entire period of application. Since the viscosity is constant, the coating film of the resist liquid that is stretched by centrifugal force is formed uniformly over the entire area.

〔Example〕

FIG. 1 is a longitudinal cross-sectional view of a main part of a coating device according to an embodiment of the present invention. In the figure, (1) is a processing cup, and (2) is a wafer chuck, which are connected to a motor shaft (3). (4) is a resist nozzle that supplies resist liquid (6) onto the wafer (5). (8) is a chuck temperature sensor, (9) is a resist temperature regulator, and (10) is a resist temperature control unit that controls the resist temperature regulator (9) based on the output of the chuck temperature sensor (8).

Next, the operation of this embodiment will be explained based on the above configuration.

The resist temperature control section (10) has a chuck temperature sensor (8).
) When the temperature information of the wafer chuck is inputted, a control signal is sent to the resist temperature regulator (9) to raise the temperature of the resist liquid (6) slightly higher than the wafer chuck temperature based on the temperature information. At this time, the heat capacity of the wafer (5) is relatively small, and the wafer temperature is approximately equal to the temperature of the wafer chuck (2) within the normal resist processing time range. When the relative temperature relationship between the dropped resist solution and the wafer becomes appropriate in this way, the resist solution (6) that is dropped and diffused onto the wafer (5) is heated or cooled. Since the evaporation of the solvent is suppressed, the evaporation of the solvent becomes approximately constant, and therefore the viscosity of the resist solution (6) is approximately chemotactic throughout the entire application period. Since the viscosity is constant, the coating film of the resist liquid (6) that is spread by centrifugal force is uniformly formed over the entire area.

As an example, the temperature of the wafer chuck is 1 to 1.
By dropping a resist that is 5°C warmer, the film thickness at the center of the wafer becomes thicker as shown in Figure 2 (B), and with an average film thickness of 100%, the variation can be reduced to about IOA, compared to the conventional technology. A coating film thickness with good uniformity can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, by adjusting the temperature of the resist solution just before dropping according to the temperature of the wafer chuck, the correlation between the temperature of the solvent on the wafer and the temperature of the resist solution is optimized. Therefore, the viscosity of the coating material can be made constant over the entire coating period, thereby making it possible to obtain a coating apparatus that can make the thickness of the resist film uniform over the entire wafer.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a main part showing a coating apparatus according to an embodiment of the present invention, FIG. 2 is a graph showing the thickness of a resist coating film on a wafer, and FIG. 3 is a longitudinal cross-sectional view of a conventional coating apparatus. In the figure, (2) is a wafer chuck, (4) is a resist dropping nozzle, (5) is a wafer, (6) is a resist, (
8) is a chuck temperature sensor, (9) is a resist temperature regulator, and (lO) is a resist temperature 'MJ control section. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A coating device that supplies a resist solution onto a wafer placed on a rotating wafer chuck and forms a resist film on the wafer using centrifugal force, the coating device having a sensor that detects the temperature of the wafer chuck, and a sensor that detects the temperature of the wafer chuck. 1. A coating device characterized in that a resist dropping nozzle is provided with a temperature regulator that controls the temperature near the tip of the resist dropping nozzle based on temperature information of the resist dropping nozzle.