JP2006272069A - Cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a washing device capable of being applied to the washing of an electronic material requested to have high cleanliness such as a silicon substrate for a semiconductor, a glass substrate for a liquid crystal or a quartz substrate for a photomask and simultaneously eliminating organic material contamination and particulate contamination. <P>SOLUTION: This cleaning device, which has a holding part for holding the object to be washed and in which the object to be washed is washed by bringing it into contact with gas-dissolved water, has a photocatalyst carrier and a light irradiation device arranged adjacently to the holding part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cleaning apparatus. More specifically, the present invention is applied to the cleaning of electronic materials that require high cleanliness, such as silicon substrates for semiconductors, glass substrates for liquid crystals, and quartz substrates for photomasks, and simultaneously removes organic contamination and particulate contamination. The present invention relates to a cleaning device capable of

  Conventionally, a cleaning technique using a high concentration chemical solution called RCA cleaning at a high temperature has been applied to cleaning an electronic material that requires a highly clean surface. It has also been known that the cleaning effect can be enhanced by using ultraviolet irradiation in combination with cleaning using a high concentration chemical solution. For example, as a method of obtaining a highly washed object without using an organic solvent that causes environmental pollution, the washing process can be easily controlled, and a 3: 1: 1 mixture of sulfuric acid, hydrogen peroxide, and water. An example is a method of cleaning an object to be cleaned coated with a resist while irradiating ultraviolet rays with a low-pressure mercury lamp using a 1: 1: 5 mixed solution of ammonium hydroxide, hydrogen peroxide and water (patent) Reference 1).

  In recent years, it has been required to reduce the cost of the cleaning process and to reduce the environmental load, and the practical application of room temperature cleaning technology using a dilute cleaning liquid has been studied. Under such circumstances, ultrasonic cleaning technology using ultrapure water in which a specific gas is dissolved has been developed. In particular, so-called hydrogen water in which hydrogen gas is dissolved at a high concentration is used in combination with ultrasonic waves. It has been clarified that it exhibits a very high particle removal effect that exceeds the concentration chemical cleaning. Furthermore, it has been found that hydrogen water is effective in preventing natural oxidation of the substrate surface, and also has an effect of promoting hydrogen termination on the outermost surface when the object to be cleaned is a bare silicon substrate.

On the other hand, when ultrasonic waves are applied to cleaning, it has been pointed out that there is a possibility of damaging a finely processed pattern. For this reason, there has been a demand for a cleaning apparatus capable of performing cleaning with hydrogen water without fear of damaging an object to be cleaned having a finely processed surface. From such a situation, for example, as a cleaning device that can clean an electronic material that requires a high degree of cleanliness without fear of damaging the surface, by combining gas-dissolved water, ultraviolet rays, and even ultrasonic waves, An apparatus that improves the cleaning effect and does not damage the pattern has been proposed (Patent Document 2). However, even when a combination of gas-dissolved water, ultraviolet rays, and ultrasonic waves is used, there remains a problem that only one of fine particles and organic substances attached to the object to be cleaned is effective.
Japanese Patent Laid-Open No. 4-179225 (pages 2 and 3) JP 2002-45806 A (2nd page)

  The present invention is applied to cleaning of electronic materials such as silicon substrates for semiconductors, glass substrates for liquid crystals, quartz substrates for photomasks and the like that require high cleanliness, and can simultaneously remove organic contamination and particulate contamination. It was made for the purpose of providing.

  As a result of intensive research to solve the above problems, the present inventors brought the gas-dissolved water into contact with the photocatalyst in the vicinity of the object to be cleaned when cleaning the object to be cleaned in contact with the gas-dissolved water. Furthermore, it was found that by irradiating the photocatalyst with light, a part of the water molecule decomposes to generate hydrogen radicals and hydroxyl radicals, and a very high cleaning effect is exerted on both fine particles and organic matter. Based on this, the present invention has been completed.

That is, the present invention
(1) A cleaning device having a holding unit for holding an object to be cleaned and cleaning the object to be cleaned by bringing it into contact with gas-dissolved water, comprising a photocatalyst carrier and a light irradiation device in the vicinity of the holding unit. A cleaning device,
(2) The cleaning device according to (1), including a vibration applying device that applies vibration to the dissolved gas in the vicinity of the holding unit,
(3) The cleaning device according to (1) or (2), wherein the gas-dissolved water is pure water in which hydrogen gas, oxygen gas or rare gas is dissolved, and
(4) The cleaning device according to (1), (2) or (3), wherein at least one of the holding unit, the photocatalyst carrier and the light irradiation device is relatively movable,
Is to provide.

Furthermore, as a preferred embodiment of the present invention,
(5) The cleaning device according to (1), wherein the object to be cleaned is a plate-like object,
(6) The cleaning apparatus according to (5), wherein the plate-like material is a silicon substrate for semiconductor, a glass substrate for liquid crystal, or a quartz substrate for photomask,
(7) The cleaning apparatus according to (1), wherein the distance between the surface of the object to be cleaned held by the holding unit and the photocatalyst carrier is 10 mm or less,
(8) The cleaning device according to (1), wherein the distance between the photocatalyst carrier and the irradiation part of the light irradiation device is 100 mm or less,
(9) The cleaning device according to (1), wherein the gas-dissolved water is pure water in which a gas having a saturation solubility of 30% or more is dissolved.
(10) The cleaning device according to (1), wherein the photocatalyst is a metal oxide or a metal sulfide.
(11) The cleaning apparatus according to (10), wherein the metal oxide is zinc oxide, tungsten oxide, titanium oxide, or cerium oxide,
(12) The cleaning apparatus according to (10), wherein the metal sulfide is zinc sulfide, cadmium sulfide, or mercury sulfide.
(13) The cleaning device according to (1), wherein the photocatalyst is doped with impurity ions,
(14) The cleaning device according to (13), wherein the impurity ions are nitrogen ions or sulfur ions,
(15) The cleaning device according to (10), wherein the photocatalyst carries platinum on a metal oxide or metal sulfide,
(16) The cleaning device according to (1), wherein the light emitted from the light irradiation device has a wavelength of 100 to 650 nm, and
(17) The cleaning device according to (2), wherein the vibration applying device is an ultrasonic oscillation device,
Can be mentioned.

  By using the cleaning apparatus of the present invention, it is possible to achieve both high particle removal effect comparable to conventional megasonic cleaning and surface protection of the same object as cleaning without using megasonic. Can be removed.

  The cleaning device of the present invention has a holding unit for holding an object to be cleaned, and in the cleaning device for cleaning an object to be cleaned by bringing it into contact with gas-dissolved water, the photocatalyst carrier and the light irradiation device are arranged close to the holding unit It is a cleaning device. The cleaning apparatus of the present invention can be suitably applied to cleaning plate-like materials that require high cleanliness with respect to particulate contamination and organic contamination, and in particular, semiconductor silicon substrates, liquid crystal glass substrates, and photomask quartz. It can be suitably used for cleaning a substrate or the like.

  There is no particular limitation on the holding unit for holding the object to be cleaned used in the apparatus of the present invention, and examples thereof include a chuck of a single wafer type spin cleaning apparatus, a fixture for a batch type cleaning tank, and the like.

  The gas-dissolved water used in the apparatus of the present invention is not particularly limited, but pure water in which a rare gas such as hydrogen gas, oxygen gas or helium, neon, argon, krypton, or xenon is dissolved can be suitably used. Dissolved hydrogen water can be particularly preferably used. In the apparatus of the present invention, gas-dissolved water in which one of these gases is dissolved can be used, or gas-dissolved water in which two or more of these gases are combined can be used. By cleaning with gas-dissolved water in which hydrogen gas, oxygen gas, or rare gas is dissolved, fine particles attached to the surface of the object to be cleaned can be effectively removed.

  Although there is no restriction | limiting in particular in the dissolved gas concentration of the gas dissolution water used for this invention apparatus, It is preferable that it is a density | concentration of 30% or more of the saturation solubility of each gas. For example, at 20 ° C., the saturation solubility in water is 1.63 mg / L for hydrogen gas, 44.0 mg / L for oxygen gas, and 60.8 mg / L for argon, so 30% of the saturation solubility is 0.49 mg / liter for hydrogen gas. L, oxygen gas 13.2 mg / L, and argon 18.2 mg / L. If the dissolved gas concentration of the gas-dissolved water is less than 30% of the saturation solubility, the cleaning effect may be insufficient.

  The gas-dissolved water used in the apparatus of the present invention has a higher cleaning effect as the concentration of dissolved gas is increased. However, when the concentration exceeds the saturated concentration, bubbles are generated and may adhere to the surface of the object to be cleaned and cause uneven cleaning. Therefore, it is preferable that the dissolved gas concentration of the gas dissolved water does not exceed the saturation concentration. When using a pressurizable sealed container as the cleaning part, gas-dissolved water that is equal to or lower than the saturation concentration at the container internal pressure can be used. Although there is no restriction | limiting in particular in the temperature of the gas dissolution water used for washing | cleaning, Generally, the washing | cleaning effect becomes large, so that it is high temperature.

  A small amount of an auxiliary substance for enhancing the cleaning effect can be added to the gas-dissolved water used in the apparatus of the present invention as necessary. Examples of auxiliary substances that enhance the cleaning effect include alkaline reagents and surfactants. By adding these auxiliary substances, a zeta potential control effect that prevents the reattachment of the foreign substances detached from the object to be cleaned is exhibited.

  In the apparatus of the present invention, there is no particular limitation on the method of bringing the object to be cleaned into contact with the gas-dissolved water. For example, using a single-wafer type spin cleaning device, the gas-dissolved water is sprayed from the nozzle onto the object to be cleaned. Alternatively, the object to be cleaned can be immersed and brought into contact with the gas-dissolved water using a batch-type cleaning tank.

  The cleaning device of the present invention includes a photocatalyst carrier and a light irradiation device in the vicinity of a holding unit that holds an object to be cleaned. When light is irradiated to the photocatalyst carrier from the light irradiation device, radicals are generated on the surface of the photocatalyst, and the radicals attack the organic matter contamination adhered to the surface of the object to be cleaned, and decompose and remove the organic matter contamination by radical reaction. . In the apparatus of the present invention, the distance between the surface of the object to be cleaned held by the holding part and the photocatalyst carrier is preferably 10 mm or less, and more preferably 5 mm or less. When the distance between the surface of the object to be cleaned and the photocatalyst carrier held by the holding unit exceeds 10 mm, radicals generated on the surface of the photocatalyst disappear by recombination or side reaction before reaching the surface of the object to be cleaned. The ratio may increase. In the device of the present invention, the distance between the photocatalyst carrier and the irradiation part of the light irradiation device is preferably 100 mm or less, and more preferably 50 mm or less. If the distance between the photocatalyst carrier and the irradiation part of the light irradiation device exceeds 100 mm, the light energy irradiated from the light irradiation device may not be sufficiently utilized for generation of radicals.

  The photocatalyst used in the apparatus of the present invention is a catalyst that decomposes and removes organic pollutants on the surface of an object to be cleaned, which absorbs light in a phenomenon and does not absorb light efficiently. Examples of the photocatalyst used in the apparatus of the present invention include metal oxides such as zinc oxide, tungsten oxide, titanium oxide, and cerium oxide, and metal sulfides such as zinc sulfide, cadmium sulfide, and mercury sulfide. Among these, titanium oxide is excellent in terms of structure stability, performance of removing organic contaminants by a photooxidation-reduction reaction, safety in handling, and the like, and can be suitably used in the apparatus of the present invention. Examples of titanium oxide include, in addition to general-purpose titanium dioxide, titanium oxides such as metatitanic acid, orthotitanic acid, hydrous titanium oxide, hydrated titanium oxide, titanium hydroxide, and titanium peroxide, and titanium hydroxide. be able to. Among these, titanium oxide having anatase or rutile crystal structure can be suitably used because it is relatively inexpensive and has excellent performance. However, the titanium oxide used in the apparatus of the present invention is not limited to the crystal structure and crystallinity as long as it has a photocatalytic function.

  In the apparatus of the present invention, the photocatalyst such as a metal oxide or metal sulfide can be doped with impurity ions such as nitrogen ions or sulfur ions, or supported with platinum or the like to enhance the catalytic activity. Titanium oxide absorbs an ultraviolet light region with a wavelength of 380 nm or less and exhibits an effect. However, by doping impurity ions such as nitrogen ions and sulfur ions, titanium oxide has a photocatalytic function even in a visible light region with a wavelength of 380 to 650 nm. The light irradiation device other than the ultraviolet irradiation device can be applied. Furthermore, by supporting a metal such as platinum on a metal oxide, metal sulfide or the like, the efficiency in the photoreaction can be improved.

  There is no restriction | limiting in particular in the light irradiation apparatus used for this invention apparatus, For example, the apparatus provided with the hydrogen discharge tube, the xenon discharge tube, the mercury lamp, the laser, etc. can be mentioned. By providing a light irradiation device in the vicinity of the photocatalyst carrier and irradiating the photocatalyst carrier immersed in the gas-dissolved water being washed with light, the cleaning effect can be enhanced.

  In the proposed hydrogen water cleaning, ultrasonic waves such as megasonic are applied. This is because it was originally expected to promote the detachment of fine particles due to a physical effect derived from ultrasonic waves. Certainly, physical forces such as generation and growth of microbubbles due to microcavitation caused by ultrasonic waves and vibration with a large acceleration exert an effect on the separation of foreign matters from the surface of the object to be cleaned. However, the decisive difference between hydrogen water and ordinary ultrapure water is that it effectively generates hydrogen radicals, which cause chemical reactions with the surface of the object to be cleaned and foreign matter, which makes it extremely expensive. A cleaning effect is exhibited.

  Even if it is not hydrogen water, hydrogen radicals are generated in the water irradiated with ultrasonic waves, but hydrogen water is particularly effective because hydrogen radicals ( It is considered that, among H) and hydroxyl radical (.OH), a part of the hydroxyl radical reacts with dissolved hydrogen gas to become water, so that the hydrogen radical becomes relatively excessive. However, when strong ultrasonic waves pass through the cleaning water, ultrasonic cavitation occurs in the water, which may cause damage to the surface of the object to be cleaned. When the object to be cleaned is a silicon substrate for a semiconductor having a fine pattern processed on the surface, damage due to cavitation is a particularly serious problem.

  According to the apparatus of the present invention, when the object to be cleaned is brought into contact with the gas-dissolved water and cleaned, the photocatalyst carrier is placed in the vicinity of the object to be cleaned, and the photocatalyst is irradiated with light using the light irradiation device. The photocatalyst that has absorbed the light energy is excited to electrons and holes, the water molecules are decomposed into hydrogen radicals and hydroxyl radicals, and an excellent cleaning effect can be obtained as in the case of oscillating ultrasonic waves. Moreover, when light is applied to the photocatalyst, no physical force such as ultrasonic waves acts on the photocatalyst, so that cavitation does not occur and the surface of the object to be cleaned is not damaged.

  In the device of the present invention, the wavelength of light emitted from the light irradiation device is preferably 100 to 650 nm. Extreme ultraviolet rays having a wavelength of less than 100 nm require an ultraviolet irradiation device using a special material for a light source, a transmission window, a reflecting mirror, and the like, which may impair economic efficiency. When the wavelength of light exceeds 650 nm, light cannot be effectively absorbed by the photocatalyst, and radical generation by a photoexcitation reaction may be difficult.

  In the device of the present invention, it is preferable to provide a vibration applying device that applies vibration to the gas dissolved water in the vicinity of the holding portion. There is no restriction | limiting in particular in the vibration provision apparatus installed, For example, an ultrasonic oscillation apparatus, the nozzle for jet fluids, etc. can be mentioned. An ultrasonic oscillator can transmit ultrasonic waves to gas-dissolved water using, for example, a megasonic irradiation nozzle as a nozzle of a single wafer type spin cleaning device, or ultrasonic waves can be applied to a cleaning liquid in a batch cleaning tank. It can also be communicated.

  In the device of the present invention, the frequency of the ultrasonic wave is not particularly limited, but is preferably 20 kHz or more, more preferably 400 kHz or more, and further preferably 800 kHz or more. By increasing the frequency of the ultrasonic wave, the occurrence of cavitation can be controlled and the occurrence of damage to the object to be cleaned can be suppressed. In addition, it is preferable to use the ultrasonic wave with a lower output than in the case of normal ultrasonic cleaning so as not to damage the finely processed surface.

  As a nozzle for a jet fluid, for example, a nozzle for a bubble jet (registered trademark) fluid that mixes gas-dissolved water sent at high pressure and gas sent at high pressure in a nozzle as a nozzle of a single-wafer type spin cleaning device, For example, a cavitation jet fluid nozzle that jets high-pressure gas-dissolved water from a small-area opening in the center of the nozzle and jets low-pressure gas-dissolved water from a large-area opening around the nozzle can be used. The output of the ultrasonic wave and the strength of the jet fluid can be appropriately selected as long as the surface of the object to be cleaned is not damaged.

  In the cleaning device of the present invention, it is preferable that at least one of the holding portion, the photocatalyst carrier, and the light irradiation device is relatively movable. There is no particular limitation on the method of relatively moving the holding unit, the photocatalyst carrier, and the light irradiation device. For example, the holding tool that holds the object to be cleaned may be movable with respect to the fixed light irradiation device. The holding device for holding the object to be cleaned can be fixed, and the photocatalyst carrier and the light irradiation device can be moved. Alternatively, all of the holding device for holding the object to be cleaned, the photocatalyst unit and the light irradiation device can be used. It can also be movable. By making at least one of the holding part, the photocatalyst carrier, and the light irradiation device relatively movable, it is possible to irradiate the entire surface of the plate-shaped object to be cleaned using a light irradiation device having a rod-shaped light source. . In addition, radicals can be generated evenly by irradiating the entire surface of the object to be cleaned almost uniformly, or radicals can be generated by intensively irradiating a portion requiring cleaning. .

  FIG. 1 is a plan view and a side view of an embodiment of the cleaning apparatus of the present invention. In the cleaning apparatus of this aspect, the semiconductor silicon substrate 1 is held by the three chucks 2. The photocatalyst carrier 3 is fixed close to the semiconductor silicon substrate, and the light irradiation device 4 is installed on the top. Light is irradiated from the light irradiation device to rotate the semiconductor silicon substrate, and gas dissolved water 6 is jetted from the gas dissolved water nozzle 5 onto the semiconductor silicon substrate. After irradiating light, rotating the silicon substrate for semiconductor, and jetting the gas dissolved water continuously for a predetermined time, stop jetting the gas dissolved water, separate the photocatalyst carrier and the light irradiation tube from the silicon substrate for semiconductor, The rotational speed of the silicon substrate can be increased and spin-dried. The shape of the photocatalyst carrier is not particularly limited. For example, a photocatalyst supported on the surface of the quartz plate to be cleaned, or a catalyst immobilized on a three-dimensional structure such as a foam or non-woven fabric. And so on. FIG. 2 is a plan view of another embodiment of the light irradiation device used in the device of the present invention. In the device of the present invention, the light irradiation device may have a bent shape shown in FIG. 2 in addition to the rod-like shape shown in FIG.

  FIG. 3 is a plan view and a cross-sectional view of another embodiment of the cleaning apparatus of the present invention. In the apparatus of this aspect, the semiconductor silicon substrate 1 is held by the holding table 8 provided in the cleaning tank 7 and immersed in the gas-dissolved water 6. The light irradiation device 4 swings between the position indicated by the solid line and the position indicated by the dotted line in FIG. 3, and irradiates the photocatalyst carrier 3 provided on the upper part of the semiconductor silicon substrate with light. The semiconductor silicon substrate immersed in the gas-dissolved water for a predetermined time and having been cleaned is taken out of the cleaning tank and dried.

  In the cleaning apparatus of the present invention, it is preferable that the gas-dissolved water has an appropriate flow so that the foreign matter detached from the surface of the object to be cleaned does not reattach to the object to be cleaned. In the embodiment shown in FIG. 1, the gas-dissolved water ejected from the nozzle is discharged out of the system in a transient manner after contacting the surface of the object to be cleaned. Further, in the embodiment shown in FIG. 3, the gas-dissolved water flows into the cleaning tank from the inlet 9 and flows out from the overflow port 10.

  By using the cleaning apparatus of the present invention, a high particle removal effect comparable to conventional megasonic cleaning using ultrasonic waves can be obtained, and the surface of the object to be cleaned can be prevented from being damaged in the same way as cleaning without using ultrasonic waves. Organic contamination can be removed simultaneously with particulate contamination in the process.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
In the examples and comparative examples, a 6-inch silicon wafer which was left in a clean room for 10 days, was contaminated with organic matter by clean room air, and was forcibly contaminated with alumina abrasive fine particles having an average particle size of 0.3 μm, and A 6-inch silicon wafer provided with a pattern having a minimum line width of 0.25 μm was used as an object to be cleaned.
For cleaning the silicon wafer, a spin cleaning machine is used, the silicon wafer is rotated at 500 rpm, hydrogen water in which 1.2 mg / L of hydrogen gas is dissolved is sprayed from a 1.5 L / min nozzle, and the nozzle is centered on the silicon wafer. Washing was performed for 30 seconds while swinging between the edges in a cycle of 10 seconds. When oscillating ultrasonic waves, a megasonic nozzle was used to transmit ultrasonic waves having a frequency of 1.0 MHz to hydrogen water. After completion of the cleaning process, the rotation speed of the silicon wafer was increased to 1,500 rpm and dried for 20 seconds.
The cleaning effect of organic contamination was evaluated by measuring the contact angle of ultrapure water dropped on a silicon wafer using a contact angle meter, and the smaller the contact angle, the greater the cleaning effect. The contact angle of the silicon wafer contaminated by standing for 10 days was 51 degrees.
The number of fine particles was measured using a laser scattering foreign substance inspection apparatus [Topcon Corporation, WM-1500]. The particle contamination state of the silicon wafer contaminated with the alumina abrasive particles was 5,000 to 7,000 particles / wafer having a particle diameter of 0.2 μm or more. The fine particle removal rate was calculated from the number of fine particles on the surface of the silicon wafer after washing and drying and the number of fine particles on the surface of the silicon wafer before washing.
About the silicon wafer which gave the pattern, the presence or absence of pattern damage was observed using the scanning electron microscope.

Comparative Example 1
Hydrogen water was sprayed through a nozzle to perform spin cleaning.
The contact angle after washing was 40 degrees, and the fine particle removal rate was 20%. No pattern damage was observed.
Comparative Example 2
Using a megasonic nozzle, ultrasonic spin cleaning was performed by jetting hydrogen water onto a silicon wafer while oscillating ultrasonic waves with an output of 15 W / cm ² .
The contact angle after washing was 23 degrees, and the fine particle removal rate was 99%. In addition, there was a slight pattern collapse.
Comparative Example 3
Ultrasonic spin cleaning was performed in the same manner as in Comparative Example 2 except that the ultrasonic output was lowered to 5 W / cm ² .
The contact angle after washing was 31 degrees, and the fine particle removal rate was 35%. No pattern damage was observed.
Comparative Example 4
An ultraviolet irradiation tube (length 150 mm) having a central wavelength of 254 nm was fixed to the nozzle used in Comparative Example 1, and spin cleaning was performed while irradiating ultraviolet rays and swinging on the silicon wafer together with the nozzle. The distance between the ultraviolet irradiation tube and the silicon wafer was adjusted to 2 mm.
The contact angle after washing was 15 degrees, and the fine particle removal rate was 96%. No pattern damage was observed.
Comparative Example 5
The same ultraviolet irradiation tube as in Comparative Example 4 is fixed to the same megasonic nozzle as in Comparative Example 2, and the ultrasonic wave with an output of 5 W / cm ² is swung on the silicon wafer together with the megasonic nozzle while irradiating ultraviolet rays. Ultrasonic spin cleaning in which hydrogen water was jetted onto a silicon wafer while oscillating was performed.
The contact angle after washing was 10 degrees, and the fine particle removal rate was 99%. No pattern damage was observed.

Example 1
A photocatalyst carrier having titanium oxide supported on one side of a quartz glass plate by a sol-gel method is fixed at a position 2 mm above the silicon wafer to be cleaned, and the ultraviolet irradiation tube (length 150 mm) used in Comparative Example 4 is 2 mm above it. It was made to swing at the position. The nozzle used in Comparative Example 1 was also subjected to spin cleaning while swinging on the silicon wafer.
The contact angle was 5 degrees or less, and the fine particle removal rate was 96%. No pattern damage was observed.
Example 2
In the same manner as in Example 1, the photocatalyst carrier is fixed to the upper part of the silicon wafer, the ultraviolet irradiation tube is swung, and an ultrasonic wave with an output of 5 W / cm ² is oscillated using the same megasonic nozzle as in Comparative Example 2. Ultrasonic spin cleaning in which hydrogen water was jetted onto the silicon wafer was performed.
The contact angle was 5 degrees or less, and the fine particle removal rate was 99%. No pattern damage was observed.
The results of Comparative Examples 1-5 and Examples 1-2 are shown in Table 1.

As seen in Table 1, in Comparative Example 1 in which spin cleaning was performed using hydrogen water, the contact angle was large and the particulate removal rate was low. In Comparative Example 2 in which strong ultrasonic waves were applied, the fine particle removal rate was improved, but the pattern collapsed slightly, and the silicon wafer surface was damaged. In Comparative Example 3 in which the ultrasonic wave is weakened, the silicon wafer surface is not damaged, but the contact angle is increased and the particle removal rate is also reduced. In Comparative Example 4 in which the spin cleaning was performed while irradiating with ultraviolet rays, the contact angle decreased to 15 degrees, but removal of organic contamination was insufficient. Further, in Comparative Example 5 in which ultrasonic waves are used in combination, the contact angle decreases to 10 degrees, but the removal of organic contamination is still insufficient.
In contrast, in Example 1 in which spin cleaning was performed using hydrogen water while irradiating the photocatalyst carrier with ultraviolet rays using the apparatus of the present invention, the contact angle was 5 degrees or less, the fine particle removal rate was high, and silicon There is no damage on the wafer surface. Further, in Example 2 in which weak ultrasonic waves were transmitted and ultrasonic spin cleaning was performed using hydrogen water while irradiating the photocatalyst carrier with ultraviolet rays, the contact angle was 5 degrees or less, and the fine particle removal rate was 99%. And no damage to the silicon wafer surface.
From these results, when the photocatalyst carrier placed in the vicinity of the silicon wafer is irradiated with ultraviolet rays and ultrasonic spin cleaning is performed using hydrogen water while transmitting weak ultrasonic waves, hydrogen water is transmitted while transmitting strong ultrasonic waves. It can be seen that the effect of removing fine particles is almost the same as that obtained by ultrasonic spin cleaning using, and organic contamination is removed at the same time, so that the surface of the silicon wafer is not damaged.

  By using the cleaning apparatus of the present invention, it is possible to achieve both high particle removal effect comparable to conventional megasonic cleaning and surface protection of the same object as cleaning without using megasonic. Can be removed.

It is the top view and side view of an aspect of the cleaning apparatus of the present invention. It is a top view of the other aspect of the light irradiation apparatus used for this invention apparatus. It is the top view and sectional drawing of the other aspect of the washing | cleaning apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate for semiconductors 2 Chuck 3 Photocatalyst carrier 4 Light irradiation apparatus 5 Gas dissolution water nozzle 6 Gas dissolution water 7 Washing tank 8 Holding stand 9 Inlet 10 Overflow opening

Claims (4)

  A cleaning apparatus having a holding unit for holding an object to be cleaned and cleaning the object to be cleaned by bringing it into contact with gas-dissolved water, and having a photocatalyst carrier and a light irradiation device in the vicinity of the holding unit apparatus.   The cleaning apparatus according to claim 1, further comprising a vibration applying device that applies vibration to the gas-dissolved water near the holding unit.   The cleaning apparatus according to claim 1 or 2, wherein the gas-dissolved water is pure water in which hydrogen gas, oxygen gas or a rare gas is dissolved.   The cleaning apparatus according to claim 1, 2 or 3, wherein at least one of the holding part, the photocatalyst carrier and the light irradiation device is relatively movable.

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