JPH04359507A - Chemical-liquid coating apparatus - Google Patents

Abstract

PURPOSE:To eliminate that an evacuation air flow-velocity sensor for evacuation control use is contaminated with chemical-liquid sprays in a coating treatment and to prevent a change in the evacuation flow rate of a chemical-liquid coating treatment part in a chemical-liquid coating apparatus which is provided with the evacuation control function of the chemical-liquid coating treatment part. CONSTITUTION:An evacuation air flow-velocity sensor 11 is installed inside an outside-air suction pipe 12 connected to the immediately lower part of an evacuation port 7 at a coating treatment part 1; the evacuation flow rate of the coating treatment part 1 is controlled by measuring the wind velocity of the outside air flowing inside the outside-air inhalation pipe 12 and by means of a constant flow-rate control valve 10 inside an evacuation pipe 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical coating device for semiconductor manufacturing equipment.

0002

2. Description of the Related Art FIG. 2 shows a sectional view of an exhaust piping system of a conventional chemical coating device. In the coating processing section 1 , a semiconductor substrate 3 fixed by suction on a vacuum suction plate 2 is spin-coated with a chemical solution 5 dropped from a chemical solution nozzle 4 . At the bottom of the coating processing section 1, there are a chemical liquid waste port 6 and an exhaust port 7 for exhausting the chemical atmosphere inside the processing section. The chemical liquid droplet trap 8 at the lower part of the exhaust port 7 prevents chemical liquid droplets from entering the exhaust pipe 9 and clogging the pipe, and generally uses a metal net or the like.

[0003] The exhaust inside the coating processing section 1 is essential not only for removing the chemical atmosphere but also for suppressing the splashing of the chemical inside the coating processing section 1 during spin coating. And the semiconductor substrate 2 due to rebound
contamination is known to occur. On the other hand, it is known that when the exhaust flow rate is higher than the appropriate amount, the uniformity of the coating film thickness deteriorates. Therefore, in order to perform coating with a uniform film thickness and without contamination due to splashing of the chemical, it is necessary to keep an appropriate exhaust flow rate constant.

A constant flow control valve 10 attached to the exhaust pipe 9 in the figure is feedback-controlled by an exhaust air velocity sensor 11 also attached to the exhaust pipe 9. The constant flow rate control valve 10 moves in the direction in which the valve closes when the exhaust air speed increases, and in the direction in which the valve opens when the exhaust air speed decreases, and is controlled so that the exhaust air speed is always constant, and therefore the exhaust flow rate is also constant. The above is a generally used method for making the exhaust flow rate constant, but the reason why such a method has to be used is that the exhaust flow rate of the coating processing section fluctuates for two reasons that will be described later.

The first reason is that droplets of the applied chemical enter the exhaust pipe and clog the pipe. Normally, a chemical droplet trap as described above is used to prevent the intrusion of chemical droplets, but since the mesh of this trap also gets clogged with chemical droplets, the coating process is The exhaust flow rate in the area decreases. Therefore, the chemical droplet capture device needs to be replaced regularly.

The second reason is fluctuations in factory exhaust pressure. Generally, the exhaust piping of the coating processing section is connected to the factory exhaust. Normally, this factory exhaust line is shared by various equipment, so the exhaust pressure fluctuates depending on the amount of exhaust used by other equipment, and therefore the exhaust flow rate also fluctuates.

[0007]

The conventional exhaust flow rate control described above has a problem in that the controlled exhaust flow rate fluctuates due to contamination of the exhaust air velocity sensor by chemical droplets. In other words, most of the chemical droplets are captured by the chemical droplet trap, but some of them enter the exhaust piping. Exhaust air velocity sensors are generally thermal sensors, and if foreign matter adheres to the sensor surface, the sensitivity of the sensor decreases. This results in a detection lower than the true exhaust air speed. Therefore, in this state, the constant flow rate control valve is controlled in the opening direction, so that the controlled exhaust flow rate becomes greater than the true value. In other words, as the coating process continues, a phenomenon occurs in which the controlled exhaust flow rate gradually becomes larger than the appropriate value.

[0008] This phenomenon deteriorates the uniformity of the thickness of the chemical coating on the surface of the semiconductor substrate. For example, in the case of photoresist, with the current technology, the film thickness is about 1 μm, and the film thickness variation is said to be within 30 angstroms. Although it depends on the degree, if the exhaust flow rate of the coating processing section is higher than the appropriate amount, the film thickness variation will be more than twice the normal amount, that is,
There is a good possibility that it will be 60 angstroms or more.

[0009] In the conventional technology, this increase in exhaust flow rate cannot be corrected, and the exhaust air velocity sensor must be periodically cleaned. In addition, it was necessary to perform cleaning quite frequently, considering the margin of risk of deterioration of the uniformity of the chemical coating film thickness.

0010

[Means for Solving the Problems] In the chemical coating device of the present invention, an outside air suction pipe in which an exhaust air velocity sensor is installed is connected to an exhaust piping system directly below the chemical coating processing section.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a sectional view showing a piping system according to an embodiment of the present invention. The difference from the conventional technology is that the exhaust air speed sensor 11 is connected to the exhaust pipe directly below the coating processing section 1.
2.

The measured exhaust air speed is the air speed inside the outside air suction pipe 12, and the constant flow rate control valve 10 is also controlled by this exhaust air speed. In this case, the necessary conditions are that when the exhaust pipe 9 exhausts the constant flow control valve 10 to the full open position, the coating processing section 1
The exhaust flow rate must be sufficiently high to exceed the required exhaust flow rate. In other words, an exhaust capacity is required to compensate for the exhaust flow rate of the coating processing section, which is lower than originally due to the intake of outside air.

Since both outside air intake and exhaust from the coating processing section 1 are carried out through the exhaust pipe 9, the constant flow control valve 10
If is set so that the exhaust flow rate of the coating processing section 1 is set to an appropriate value, the exhaust flow rate of the coating processing section can be kept constant as in the conventional technique. The outside air intake from the outside air intake pipe 12 can be used for purposes such as exhausting the application liquid storage section, as long as it is not used in a way that changes the intake amount or in a way that contaminates the exhaust air speed sensor 11. . Therefore, under such usage, there is no overall reduction in exhaust capacity.

Furthermore, in this embodiment, the wind speed of the air taken in from the outside air suction pipe is constantly measured, and the constant flow control valve 11
Therefore, contamination of the exhaust air velocity sensor by coating chemical droplets, which has been a problem with conventional techniques, cannot occur.

[0015]

As explained above, in the present invention, since the constant flow rate control valve is controlled by the exhaust air velocity sensor in the outside air suction pipe, it is possible to eliminate contamination of the exhaust air velocity sensor due to spray of coating chemicals. Therefore, the phenomenon of an increase in the exhaust flow rate of the coating processing section due to contamination of the exhaust air speed sensor is resolved, and the variation in the thickness of the chemical coating on semiconductor substrates caused by this phenomenon is eliminated, thereby improving the yield of semiconductor products in semiconductor manufacturing. can be done.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of the present invention.

FIG. 2 is a sectional view of a conventional chemical coating device.

[Explanation of symbols]

1 Coating processing section 2 Vacuum suction plate 3 Semiconductor substrate 4 Chemical liquid nozzle 5. Chemical solution 6 Chemical liquid waste port 7 Exhaust port 8. Chemical liquid droplet trap 9 Exhaust piping 10 Constant flow control valve 11 Exhaust wind speed sensor 12 Outside air intake piping

Claims (1)

[Claims] 1. A chemical coating device having a function of controlling the exhaust air speed of a chemical coating processing section, characterized in that an outside air suction pipe having an internal exhaust air speed sensor is connected to the exhaust piping system directly below the chemical coating processing section. A chemical coating device.