JPH0670961B2 - How to apply photoresist - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a glass used in a spin coating apparatus, particularly for coating a photoresist on a silicon wafer in the manufacture of a semiconductor integrated circuit, or for mastering a compact disc, a video disc or the like. The present invention relates to a photoresist coating method for coating a master with photoresist.

[Conventional technology]

In the manufacture of a semiconductor integrated circuit (LSI), for example, a silicon wafer is coated with a photoresist as a photosensitizer, exposed, developed, and etched using a mask, and patterned to form a circuit. Further, in mastering of compact discs, video discs, etc., a glass master having a polished surface is coated with photoresist, recorded with a laser beam modulated with a signal, and developed to form a signal pit.

Therefore, the spin coating device has a configuration shown in the schematic configuration diagram of FIG.

In the figure, a housing 1 is divided into a coating chamber 3 and a storage chamber 7 by a partition plate 2, and a hole 8 for loosely inserting a rotary shaft 15 for transmitting a driving force of a drive motor 4 is provided in a substantially central portion of the partition plate 2. There is. Then, the rotary table 13 is mounted on the rotary shaft 15 protruding into the coating chamber 3, and the substrate 16 is placed thereon. A partition 27 is provided around the turntable 13 so as to surround the turntable 13, and the housing 1 of the coating chamber 3 is provided.
An exhaust duct 22 is provided in the exhaust duct 5, and the exhaust fan 5 compulsorily exhausts the air. Further, in the coating chamber 3, there is a hollow coating arm 23 for coating photoresist, a nozzle 24 is provided at the tip end, and the other end is connected to a flexible pipe 25 to make the housing 1
The photoresist solution is supplied from outside. The coating arm 23 is rotatably supported by an arm base 26 standing upright from the partition plate 2, and a nozzle 24 at the tip is movable from the center of the rotary table 13 to the outside of the partition wall 27 with a distance from the substrate 16.

In the spin coater configured as described above, the rotary table
Place the substrate 16 on 13, rotate the rotary table 13 to move the nozzle 24 to the center of the substrate 16 to drop a predetermined amount of photoresist solution, and spread the photoresist solution over the entire surface of the substrate 16 by centrifugal force. A photoresist film is formed.

In this way, the photoresist solution on the rotating substrate 16 is spread toward the outer periphery of the substrate 16 by receiving the centrifugal force according to the rotation speed. Then, a photoresist film having a thickness suitable for the rotation speed and the viscosity of the photoresist solution is formed on the substrate 16, and the excess photoresist solution is scattered from the periphery of the substrate 16.

As described above, when the substrate surface is clean, a defect-free photoresist film is formed on the substrate surface.

[Problems to be Solved by the Invention]

The conventionally used photoresist solution is a non-hydrophilic solution which is diluted with ethylene glycol monoethyl ether acetate (hereinafter referred to as cellosolve acetate) alone or a mixed solvent of xylene and butyl acetate mixed therein. When it is hydrophobic, the photoresist can spread well on the surface of the substrate to form a uniform photoresist film. However, if adsorbed water or the like is partially present on the substrate surface, the wettability with the photoresist is deteriorated because the portion is hydrophilic, and bubbles are generated in the coating film as shown in FIGS. 4 (a) and 4 (b). Defects such as coating unevenness and pinholes occur.

[Means for Solving the Problems]

Therefore, on the surface of the substrate that is detachably fixed on the rotating table and rotates, a positive photoresist that is condensed or mixed with a novolac resin using naphthoquinone diazito as a photosensitive group, ethylene glycol monoethyl ether acetate alone,
Alternatively, a means for injecting a liquid flow of a photoresist solution diluted with a mixed solvent of ethylene glycol monoethyl ether acetate mixed with xylene and butyl acetate by a nozzle, and using centrifugal force to spread and spread the photoresist solution on a substrate to form a coating film. And a nozzle for continuously flowing down a liquid flow of a photoresist solution in which isopropyl alcohol is added to the mixed solvent, and an ultrasonic transducer installed inside the nozzle. The ultrasonic vibration applied to the photoresist solution is applied to the surface of the substrate while being transmitted.

[Action]

Therefore, by continuously flowing down the coating liquid onto the substrate while superimposing ultrasonic waves, even if adsorbed water or the like is present, the adsorbed water on the substrate surface is absorbed by the coating solution due to the ultrasonic energy and the hydrophilicity of isopropyl alcohol. It is dissolved and absorbed in the isopropyl alcohol therein, and the wettability between the substrate surface and the coating solution is improved, so that the entire surface can be uniformly wetted and defects can be avoided.

〔Example〕

An embodiment of the present invention will be described below with reference to the schematic configuration diagram of FIG.

In the figure, a glass master 16 is fixed on a turntable 13 and rotated by a motor 4. Next rotating glass master
A photoresist diluted with a mixed solvent of 85% cellosolve acetate and 15% isopropyl alcohol on the surface of 16 is passed through a pipe 25 and continuously flowed down from a nozzle 30 provided with an ultrasonic vibrator. Then, the photoresist moves from the outer periphery of the glass master 16 to the center of the inner periphery and the photoresist flows down on the entire surface of the glass master. At this time, the output of the ultrasonic oscillator 36 is applied to the ultrasonic vibrator 31 of the nozzle 30 shown in the schematic diagram of FIG. 2 to apply ultrasonic vibration to the photoresist. The frequency of the ultrasonic waves used at this time is 1.5 MHz and the output is 10 W.

Next, when the photoresist is spread over the entire surface, the number of rotations is increased and the photoresist is rotated to form a resist film on the glass master. Thus, by superimposing the ultrasonic liquid on the photoresist and applying the photoresist so as to continuously flow down on the surface of the glass master, a high quality photoresist film having no defects is formed. The frequency of the ultrasonic wave used is in the range of 800 KHz to 2 MHz, and the output of the ultrasonic oscillator is appropriately 1 W to 20 W.

In addition, the liquid flow of the photoresist to which ultrasonic waves are applied has its pouring pressure adjusted so that a continuous flow can be obtained up to the surface of the glass master disk 16, so that ultrasonic vibrations can be efficiently transmitted to the surface of the glass master disk. I have to. Incidentally, the mixed solvent is not limited to the above, cellosolve acetate 60-80
%, Isopropyl alcohol 10-20%, xylene 0-10
%, Butyl acetate 0 to 10% may be used as a mixed solvent.

〔The invention's effect〕

According to the present invention, due to the vibration energy of ultrasonic waves and the hydrophilicity of isopropyl alcohol in the coating liquid, the coating liquid penetrates to the surface of the substrate to obtain a coating film without defects.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, and FIG.
FIG. 3 is a partially enlarged view of the figure, FIG. 3 is a schematic configuration diagram showing a conventional example, and FIGS. 4 (a) and 4 (b) are explanatory diagrams for explaining the problem. 30 …… Nozzle 31 …… Ultrasonic transducer 36 …… Ultrasonic oscillator

Claims (1)

[Claims] 1. A positive photoresist in which naphthoquinone azide is a photosensitive group and is condensed or mixed with a novolak resin is formed on a surface of a substrate which is detachably fixed on a rotary table.
Means for injecting a liquid flow of a photoresist solution diluted with a mixed solvent of ethylene glycol monoethyl ether acetate alone or ethylene glycol monoethyl ether acetate mixed with xylene and butyl acetate by a nozzle, and the photoresist solution using centrifugal force. A method for coating a photoresist having a means for spreading and forming a coating film on a substrate, wherein the nozzle for continuously flowing down a liquid flow of a photoresist solution obtained by adding isopropyl alcohol to the mixed solvent to the substrate surface, and the nozzle. A method of coating a photoresist, characterized in that the ultrasonic vibration applied to the photoresist solution is transmitted to the surface of the substrate by an ultrasonic vibrator installed inside the substrate, and is applied.