JPH09206713A - Washing method and washing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively remove an adhered material on a surface of an object to be washed such as a liquid crystal substrate without being damaged the substrate by washing the object to be washed with purified water impressed a specific frequency of low frequency vibrations and then washing the object to be washed with the purified water impressed high frequency vibrations. SOLUTION: This washing device is successively provided with an introduction part A, a low frequency impressed water washing part B, a high frequency impressed ozonized water washing part C, a drying part D and a discharge part E, and connection ports 11 are formed on partition walls 10 for partitioning each chamber. The object to be washed is successively conveyed from the introduction part A to the discharge part E with a movement of a conveying member. At this time, ultrasonic vibrations <=100kHz are impressed to the purified water at the low frequency washing part B and this purified water is dropped on the object to be washed to remove the particles stuck on the object to be washed. Also in the high frequency vibration washing part C, ultrasonic vibrations 1MHz are impressed on the purified water and this purified water is dropped on the object to be washed or injected to remove contamination on the surface of the object to be washed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method and a cleaning apparatus for removing deposits on the surface of an object to be cleaned such as a substrate in a liquid crystal substrate manufacturing process or a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In the process of manufacturing a liquid crystal substrate, a film forming step of forming a metal film by sputtering a metal such as indium (In) on the surface of the substrate, and forming a resist layer on the metal film, There is a step of forming an electrode by etching the metal layer to partially remove the metal film, and a step of forming an alignment film on the metal electrode.
In the case of a liquid crystal substrate using a TFT, a metal film forming process by sputtering or CVD for forming a TFT,
A coating step for forming a resist layer, an etching step for removing a part of the metal film, and the like are included.

In the process of manufacturing such a liquid crystal substrate, particles in the air adhere to the surface of the substrate, and metals and organic substances adhere to the surface of the substrate during the etching process and the resist layer forming process, and the substrate surface is naturally oxidized. A film may also be formed. If such a contaminant adheres to the interface between the substrate and the electrode or the interface between the electrode and the alignment film, the contact between the electrodes deteriorates, resulting in an increase in resistance and wiring failure. Therefore, the removal of such deposits is a very important step for manufacturing a high-performance element, and it is necessary to clean the substrate surface at each stage of manufacturing the substrate to remove the deposits as much as possible. . Particularly, in the step of forming the TFT, it is necessary to make the surface on which the metal layers are laminated a highly cleaned interface, and therefore a work for surely removing the deposits is necessary.

Conventionally, in order to remove the deposits on the substrate surface,
Although the substrate surface was cleaned using CFCs, CFCs have a strong cleaning power, but they adversely affect the natural environment.
Currently not used. Therefore, a cleaning method and a cleaning apparatus using pure water as shown in FIG. 5 have been studied. In this cleaning method and cleaning apparatus, a step 1 of dropping pure water (or water) containing a detergent onto the surface of the liquid crystal substrate and cleaning with a brush, and applying ultrasonic vibration to the pure water, the pure water is applied to the surface of the substrate. It has a step 2 of dropping or jetting and a drying step 3 using an air knife.

[0005]

In the cleaning method and the cleaning apparatus shown in FIG. 5, in the step 1 of dropping a detergent and cleaning with a brush, removal of relatively large particles of 10 μm or more is effective. There is a limit to the removal of minute particles. In addition, although it is possible to remove organic substances to some extent, it is impossible to remove metal contaminants adhering to the substrate surface, and the substrate surface is easily damaged by the brush and the electrodes, etc. formed on the substrate surface are easily damaged. There are drawbacks.

Next, in the conventional cleaning step 2 using pure water to which ultrasonic vibration is applied, a relatively low frequency vibration of about 40 kHz or 50 kHz is applied to pure water. When ultrasonic vibrations are applied to pure water, the vibrations are reflected on the surface of the pure water and coarse and dense are formed in the liquid to form cavities in the dense portion (cavitation effect). Particles on the substrate surface are peeled off by this cavitation effect.

However, since the size of the particles that can be removed by the cavitation effect is inversely proportional to the frequency of ultrasonic vibration, the particles that can be removed by pure water given a relatively low frequency of 40 kHz or 50 kHz are relatively large. However, it is impossible to remove fine particles of 2 μm or less. Further, although the organic substances can be removed to some extent by the cleaning by the cavitation effect using low-frequency ultrasonic vibration, it is difficult to remove the metal adhering to the substrate surface.

As described above, the combination of the cleaning step 1 and the cleaning step 2 shown in FIG. 5 has a drawback that it is difficult to remove metal, and the removal of fine particles and organic substances is not perfect. Furthermore, the cleaning process using a brush has a fatal drawback that the substrate is easily damaged. Therefore, it is not preferable as a combination of cleaning steps.

The present invention solves the above-mentioned problems of the prior art by optimizing the combination of cleaning steps to remove both large and small particles, and is also effective for removing organic substances and metals. Another object of the present invention is to provide a cleaning method and a cleaning device that do not damage the substrate surface.

[0010]

The cleaning method of the present invention comprises:
Both the step of applying pure water to which low-frequency vibration of 00 kHz or less is applied to wash the object to be cleaned and the step of applying pure water to which high-frequency vibration of 1 MHz or more is applied to wash the object to be cleaned are provided. It is a feature.

In the above, it is preferable that ozone is mixed in pure water which gives high frequency vibration.

Further, the cleaning apparatus of the present invention comprises a low frequency cleaning chamber provided with a water supply section for supplying pure water to which low frequency vibration of 100 kHz or less is applied to the object to be cleaned, and pure water to which high frequency vibration of 1 MHz or more is applied. A high-frequency cleaning chamber provided with a water supply unit for supplying an object to be cleaned is arranged continuously, and the object to be cleaned can be moved between both cleaning chambers.

Further, in the above, it is preferable that an ozone mixing section is provided in the pure water supply path to the water supply section of the high frequency cleaning chamber.

In the present invention, a cleaning chamber for cleaning with two kinds of cleaning water, that is, pure water to which low-frequency vibration is applied and pure water to which high-frequency vibration is applied is continuously provided, and both cleaning chambers are provided. The object to be cleaned moves between the chambers, and two kinds of cleaning are continuously performed. However, a water supply unit for supplying the two types of cleaning water may be provided in one cleaning chamber, and cleaning using the two types of cleaning water may be continuously performed in the same cleaning chamber.

In the low-frequency cleaning room, pure water having a frequency of 100 kHz or less, for example, 70 kHz, 50 kHz, or 40 kHz is used.
Ultrasonic vibration of Hz is applied, and this pure water is dropped onto an object to be cleaned such as a liquid crystal substrate or jetted by a nozzle, or is dropped or injected onto a rotating object to be washed. When low-frequency vibration of 100 kHz or less is applied to pure water, the vibration propagates in the liquid and is reflected at the interface between the liquid and the air to form coarse and dense distribution on the liquid surface based on the vibration wavelength. A cavity is formed in this dense portion (cavitation), and the particles adhering to the object to be cleaned are peeled and removed by the cavitation effect. However,
Since the size of particles that can be removed by the cavitation effect is inversely proportional to the frequency of vibration in pure water, 1
10 for cleaning liquids with low-frequency vibration below 00 kHz
It is effective for removing relatively large particles of μm or more. However, the effect is slightly reduced by removing particles with a size of less than 10 μm, and it is difficult to remove fine particles with a size of 2 μm or less. In addition, removal of organic matter is possible, but not so effective.

Next, in the high-frequency cleaning chamber, high-frequency ultrasonic vibrations of 1 MHz or more are applied to the pure water, and the pure water is dropped or sprayed onto an object to be cleaned such as a liquid crystal substrate, or a rotating object to be cleaned. On the other hand, pure water is dropped or sprayed. High-frequency ultrasonic vibrations of 1 MHz or more easily escape into the air from the interface between the liquid and air when propagating in the liquid, and cannot exhibit the cavitation effect like low frequencies. However, the vibration propagating in the pure water gives an excessive acceleration to the surface of the object to be cleaned, and this acceleration has the effect of removing the contamination on the surface of the object to be cleaned.

The removal of contamination by high-frequency acceleration is effective for relatively small particles, the effect of removing particles having a size of 10 μm or less is high, and the minute particles of 2 μm or less can be sufficiently removed. is there. However, there is no effect of removing relatively large particles. This point is complemented by the cleaning to which the low frequency ultrasonic vibration is applied.

Further, the cleaning using the cleaning water to which high frequency ultrasonic vibration is applied is also effective for cleaning the organic substance. Organic matter can be effectively removed by high-frequency vibration shock waves or accelerations.

Next, it is difficult to remove metal contaminants attached to the object to be cleaned with pure water to which low frequency ultrasonic vibration is applied, but cleaning using pure water to which high frequency ultrasonic vibration is applied is performed. Then, the adhered metal can be removed by the acceleration of the high frequency vibration. When ozone is mixed with pure water to which ultrasonic vibration is applied to form washing water having oxidizing power, the metal is oxidized by ozone and becomes a positive ion of the metal, which easily dissolves in the pure water. In the case of cleaning with pure water containing ozone and having an oxidizing power, the organic substances adhering to the object to be cleaned are oxidized by ozone, and CO ₂ and O ₂
As it is decomposed into, and the like, the effect of removing organic substances becomes high.

As described above, by using the cleaning with the pure water to which the low frequency ultrasonic vibration is applied and the cleaning with the pure water to which the high frequency ultrasonic vibration is applied, relatively large particles and 10 μm or less can be obtained. Alternatively, fine particles of 2 μm or less can be effectively removed. Furthermore, it is possible to remove organic substances and metal contaminants. In particular, by using cleaning water in which pure water mixed with ozone is subjected to high-frequency ultrasonic vibration, organic substances and metal contaminants can be removed more effectively. .

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a structural block diagram showing the structure of a cleaning apparatus of the present invention, and FIG. 2 is a side view showing an example of the structure of a cleaning unit (cleaning chamber) using cleaning water to which low frequency vibration is applied. FIG. 3, FIG. 3 and FIG. 4 are side views showing a cleaning unit (cleaning chamber) using cleaning water to which high frequency vibration is applied for each configuration example. FIG.
In the cleaning device of the present invention, as shown in FIG.
A, low frequency application water cleaning section (cleaning room) B, high frequency application O ₃
A water washing unit (washing chamber) C, a drying unit (drying chamber) D, and a lead-out unit (lead-out chamber) E are continuously provided.

A communication port 11 is formed in a partition wall 10 which separates the respective parts (respective chambers), and the respective parts (respective chambers) A to E communicate with each other. The transfer member holding the object W to be cleaned continuously moves from the introduction part A to the outlet part E, or the transfer member reciprocates between the adjacent chambers, whereby the object W to be cleaned such as a liquid crystal substrate is introduced. The parts are sequentially transferred from the part A to the lead-out part E.

FIG. 2 shows an example of the structure of the low frequency applied water cleaning unit (cleaning chamber) B. In the cleaning unit B, the article W to be cleaned moves from the right side to the left side in the figure along the transport path L, and the cleaning liquid is supplied to the moving article W from the upper water supply unit 12 and the lower water supply unit 13. . In the example of FIG.
The water supply parts 12 and 13 are injection nozzles, and the water supply parts 12 and 13 inject the cleaning water onto the upper and lower surfaces of the object W to be cleaned. The pure water supply unit 14 is equipped with a membrane treatment device such as an ultrafiltration membrane or a reverse osmosis membrane device, an ion exchange device, an ultraviolet irradiation device, and the like, and fine particles of tap water, colloidal substances, organic substances, metals, and shadows. Ions and dissolved oxygen are removed to extremely low concentrations.

The water supply parts 12 and 13 are provided with ultrasonic vibration generating parts 12a and 13a at their bases. The oscillating units 12a and 13a oscillate at a relatively low frequency of 70 kHz, and the oscillating unit 1 is connected to the pure water supplying unit 14.
The low frequency vibration is applied to the pure water supplied to 2a and 13a, and the cleaning target W is supplied from the tip of the water supply parts 12 and 13.
Injected to. With pure water to which low-frequency ultrasonic vibration is applied, relatively large particles on the surface of the object to be cleaned are removed by the cavitation effect, and organic matter is also removed to some extent.

FIG. 3 shows an example of the structure of the high frequency application O ₃ water cleaning section (cleaning chamber) C. In this cleaning unit C,
The object W to be cleaned moves from the right side to the left side in the figure along the transport path L, and the upper and lower surfaces of the object W to be cleaned are sprayed with the cleaning water to give the cleaning water to the upper and lower surfaces thereof. To be The supply path from the pure water supply section 14 to each of the water supply sections 15 and 16 is provided with a path branched by valves 18a and 18b, and an ozone (O ₃ ) mixing section 17 is provided in this path. By switching the valves 18a and 18b, pure water supplied from the pure water supply unit 14 passes through the ozone mixing unit 17, and ozone is mixed. Ozone is mixed as necessary by switching the valves 18a and 18b, and pure water mixed with ozone and pure water not mixed with ozone can be selected and used.

The upper water supply section 15 and the lower water supply section 16 have
A 5 MHz relatively high frequency ultrasonic oscillator is integrally provided. To the pure water supplied from the pure water supply unit 14, a relatively high frequency ultrasonic vibration of 1.5 MHz is applied from the oscillating unit. When the pure water to which the ultrasonic vibration of 1.5 MHZ is applied is applied to the object W to be cleaned from the water supply parts 15 and 16, the acceleration and impact of the ultrasonic vibration cause relatively small particles from the surface of the object W to be cleaned. Are removed, and fine particles of, for example, 2 μm or less are also removed. In addition, organic substances on the surface of the object to be cleaned W can be removed.

When pure water from the pure water supply unit 14 is supplied through the ozone mixing unit 17, ozone is mixed with the pure water to generate cleaning water having an oxidizing power, and the water supply unit 15 is further added to the cleaning water. And 16 provide high frequency vibration.
When the cleaning water mixed with ozone is used, the organic substances on the surface of the object to be cleaned W can be decomposed and effectively removed, and the metal can be effectively oxidized and removed. When the object W to be cleaned introduced from the introduction part A passes through the low frequency applied water cleaning part B and the high frequency applied ozone (O ₃ ) water cleaning part C and is cleaned, large particles on the surface of the object W to be cleaned are generated. Fine particles, all types of contaminants such as organics and metals can be removed. The cleaned object W after cleaning is sent to the drying section D, dried by a drying means such as an air knife, and led out from the outlet section E.

FIG. 4 shows another structural example of the high frequency applied O ₃ water cleaning section C. In the structure shown in FIG. 4, the rotary table 21 is provided in the cleaning chamber, and the object W to be cleaned is placed on the rotary table 21 and rotated. A moving nozzle 22 is provided as a water supply unit, and the moving nozzle 22 has 1.5
An oscillating unit 22a that emits high-frequency ultrasonic vibration of MHz is provided. Pure water is supplied from the pure water supply unit 14 to the moving nozzle 22, or pure water mixed with ozone is supplied to the moving nozzle 22 by the ozone mixing unit 17. The moving nozzle 22 is moved left and right by the moving mechanism 23, and the cleaning water is sprayed onto the object W to be cleaned which is rotated by the rotary table 21.

This cleaning water is a mixture of pure water to which high frequency ultrasonic vibration is applied and which is further mixed with ozone. The cleaning water removes fine particles, organic substances, and metals. Further, in the structure shown in FIG. 4, since the cleaning target W rotates and the cleaning water is sprayed, high-frequency ultrasonic vibration uniformly acts on the cleaning target W. Further, after the injection of the cleaning water is completed, the object to be cleaned W can be rotated at high speed to drain water. In the configuration example, ozone is mixed with pure water supplied to the cleaning unit C that applies high-frequency ultrasonic vibration, but ozone is mixed with pure water in the cleaning unit B to which low-frequency ultrasonic waves are applied. May be done.

[0030]

As described above, according to the present invention, the object to be cleaned is washed with two kinds of washing water, that is, pure water to which low frequency vibration is applied and pure water to which high frequency vibration is applied. It can remove large and small particles and various organic contaminants.

By using pure water mixed with ozone, organic substances and metals can be effectively removed.

Further, since no brush is used, various contaminants can be effectively removed without damaging the object to be cleaned.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing a cleaning apparatus of the present invention,

FIG. 2 is a side view showing the configuration of a low-frequency applied water cleaning unit,

FIG. 3 is a side view showing the configuration of a high frequency application ozone water cleaning unit;

FIG. 4 is a side view showing the configuration of a high frequency application ozone water cleaning unit having another configuration;

FIG. 5 is a block diagram illustrating a conventional liquid crystal substrate cleaning process;

[Explanation of symbols]

 A introduction part B low frequency application water cleaning part C high frequency application ozone water cleaning part D drying part E derivation part W cleaning object 12, 13 water supply part 14 pure water supply part 15, 16 water supply part 17 ozone mixing part 18a, 18b valve 21 rotary table 22 moving nozzle

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yasuyuki Harada 2-1-14 Fuchu-cho, Fuchu-shi, Tokyo Pretec Co., Ltd.

Claims (4)

[Claims] 1. Both a step of cleaning pure water to which a low frequency vibration of 100 kHz or less is applied to clean an object to be cleaned and a pure water to which high frequency vibration of 1 MHz or higher is applied to clean an object to be cleaned. A cleaning method comprising: 2. The cleaning method according to claim 1, wherein pure water which gives high frequency vibration contains ozone. 3. A low-frequency cleaning chamber provided with a water supply section for supplying pure water to which low-frequency vibration of 100 kHz or less is applied to the object to be cleaned, and water supply for supplying pure water to which high-frequency vibration of 1 MHz or more is applied to the object to be cleaned. A high-frequency cleaning chamber provided with a section is continuously arranged, and an object to be cleaned can be moved between the cleaning chambers. 4. The cleaning apparatus according to claim 3, wherein an ozone mixing section is provided in the pure water supply path to the water supply section of the high frequency cleaning chamber.