JP2008294169A - Method and apparatus for high-concentration ozone water preparation and method and apparatus for substrate surface treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare high-concentration ozone water efficiently, and to remove an organic matter on a substrate without causing any popping phenomenon. <P>SOLUTION: In the method for preparing high-concentration ozone water, ozone gas and water vapor are supplied to a chamber 2. The ozone gas is supplied from an ozone generator 9 for liquefying and separating only ozone from gas containing ozone based on a difference in vapor pressure and then vaporizing it again to generate ultra-high concentration ozone gas. The chamber 2 is heated by a heater 4 to the extent of preventing the water vapor from being liquefied. The ozone gas and water vapor are mixed while the inner pressure of the chamber 2 is being controlled to pressure lower than atmospheric pressure by a vacuum pump 3. Dew is condensed at the bottom of the chamber 2 by cooling to obtain high-concentration ozone water. Then, by dipping a substrate into the high-concentration ozone water, the organic matter, such as resist, on the substrate is removed. Ultrapure water may be supplied to the substrate treated by the high-concentration ozone water for cleaning. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for removing organic substances exemplified in a resist on a substrate surface.

  For example, there are a dry method and a wet method disclosed in Patent Document 1 as a method for removing organic substances exemplified in the resist on the substrate.

  An oxygen plasma ashing method is exemplified as the dry method. This method is non-polluting, but there are problems such as damage to the substrate and expensive equipment for generating oxygen gas plasma.

  In the wet method, an organic or inorganic solvent is used as a peeling solvent. Examples of the organic solvent include those containing phenol and a halogen solvent as main components. Examples of inorganic solvents include those containing sulfuric acid and hydrogen peroxide, those containing ammonia and hydrogen peroxide, those containing hydrofluoric acid, and those containing hydrochloric acid and hydrogen peroxide. Yes. Since these eluents are harmful, equipment for detoxifying the resist removal waste liquid is required.

  In order to solve the problems of the dry method and the wet method, the photoresist removal method disclosed in Patent Document 1 removes the resist on the substrate and cleans the substrate with wet ozone containing water, alcohol, or solvent molecules composed of these. Is doing. However, when vapor condenses on the substrate, the decomposition of the resist by ozone is hindered. Therefore, it is desirable that the substrate does not condense.

Further, although not a resist removal technique, according to the semiconductor etching method and the semiconductor device manufacturing method of Patent Document 2, ozone gas containing water vapor obtained by bubbling ozone gas into ultrapure water is added to the substrate together with an acidic or alkaline gas. Supply. At this time, the surface of the substrate is condensed by setting the temperature of the bath for bubbling to a temperature higher than the temperature of the substrate and the table for holding the substrate, and the action of the condensed water vapor, ozone gas and alkali component causes the GaAs system. It is said that the material can be etched reliably and at high speed.
JP 2001-290287 A JP 2004-235316 A

  Since the ozone concentration in ozone water depends on the solubility of ozone in water and the ozone partial pressure in the gas in contact with water (Henry's law), even if 100% ozone gas and water contact at atmospheric pressure, the concentration is 5 It is about hundreds of ppm. In general, even when an ozone-containing gas (most components are oxygen) having an ozone concentration of about 10 vol% is pressurized to increase the ozone partial pressure to increase the ozone concentration, the ozone concentration of ozone water remains at a few tens of ppm.

Furthermore, although ozonizer used for industry is widely used those silent discharge type, it is necessary to add nitrogen to increase the ozone concentration, the ozone-containing gas generated therefrom contains NO _X When dissolved in water, it becomes nitric acid, which may have undesirable effects.

  Therefore, in the method for producing high-concentration ozone water according to claim 1, ozone gas and water vapor are mixed under a pressure lower than atmospheric pressure, and then the water-containing ozone is cooled and condensed to produce high-concentration ozone water. To manufacture. Since ozone gas and water vapor are mixed under a pressure lower than the atmospheric pressure, high-concentration ozone water having a higher ozone concentration than ozone water generated under the atmospheric pressure can be produced by optimizing the mixing ratio. Further, the concentration can be freely changed by changing the mixing ratio of ozone gas and water vapor. The ozone gas may be one having an ozone concentration of several tens of percent or more. In the present invention, the risk of explosion can be avoided because ozone gas and water vapor are mixed at a pressure lower than atmospheric pressure.

  The method for producing high-concentration ozone water according to claim 2 is the method for producing high-concentration ozone water according to claim 1, wherein the ozone gas is obtained by vaporizing ozone-containing gas again after liquefying and separating only ozone based on the difference in vapor pressure. It is an ultra-high concentration ozone gas. By using this ultra-high concentration ozone gas, high concentration ozone water can be produced efficiently.

  The apparatus for producing high-concentration ozone water according to claim 3 heats the chamber to which ozone gas and water vapor are supplied, a pump for controlling the internal pressure of the chamber to be lower than the atmospheric pressure, and the inner surface and the ceiling surface of the chamber. Heating means and a cooling mechanism for cooling the bottom surface of the chamber, the chamber is heated by the heating means to such an extent that water vapor is not liquefied, and the internal pressure of the chamber is lower than atmospheric pressure by the pump. After the ozone gas and the water vapor are mixed in a controlled state, the water vapor containing ozone is condensed on the bottom surface portion cooled by the cooling mechanism. Since ozone gas and water vapor are mixed under a pressure lower than atmospheric pressure, high-concentration ozone water having a higher ozone concentration than ozone water generated under atmospheric pressure can be produced. Further, the concentration can be freely changed by changing the mixing ratio of ozone gas and water vapor. The ozone gas may be one having an ozone concentration of several tens of percent or more. In the present invention, the risk of explosion can be avoided because ozone gas and water vapor are mixed at a pressure lower than atmospheric pressure.

  The high-concentration ozone water production apparatus according to claim 4 is the high-concentration ozone water production apparatus according to claim 3, wherein the supply of the ozone gas is vaporized again after liquefying and separating only ozone from the ozone-containing gas based on the difference in vapor pressure. This is done by an ozone generator that generates ultra-high-concentration ozone gas. High concentration ozone water can be efficiently manufactured by supplying the ultra high concentration ozone gas from the ozone generator to the chamber.

  The high-concentration ozone water production apparatus according to claim 5 is the high-concentration ozone water production apparatus according to claim 3 or 4, wherein the cooling mechanism has a refrigerant flow path embedded in the bottom of the chamber. Since the bottom part of the chamber is cooled by the refrigerant flowing through the flow passage, when the water vapor containing ozone comes into contact with the bottom part, the water vapor mixed with the ozone condenses.

  The substrate surface treatment method according to claim 6 is a method in which ozone gas and water vapor are mixed under a pressure lower than atmospheric pressure and then the water vapor containing ozone is cooled and condensed to generate high-concentration ozone water. The organic substance including the resist on the substrate surface is removed by immersion. The substrate is immersed in high-concentration ozone water obtained by mixing ozone gas and water vapor at a pressure lower than atmospheric pressure, whereby the organic matter on the substrate surface is removed at a temperature lower than 100 ° C. Therefore, the popping phenomenon seen in the high dose ion implantation resist does not occur. The ozone gas may be one having an ozone concentration of several tens of percent or more. In the present invention, the risk of explosion can be avoided because ozone gas and water vapor are mixed at a pressure lower than atmospheric pressure.

  The substrate surface treatment method according to claim 7 is the substrate surface treatment method according to claim 6, wherein the ozone gas is obtained by vaporizing again ozone-containing gas after liquefying and separating only ozone based on the difference in vapor pressure. Ozone gas. By using this ultra-high-concentration ozone gas, high-concentration ozone water is efficiently generated, so that the organic matter can be effectively removed.

  A substrate surface treatment method according to an eighth aspect is the substrate surface treatment method according to the sixth or seventh aspect, wherein the substrate treated with the high-concentration ozone water is washed with ultrapure water. The organic component of the substrate treated with the ozone gas and water vapor is oxidized and decomposed into a water-soluble component (for example, aldehyde or hydroxide) by the reaction with the ozone gas and water vapor. Therefore, the residue which consists of the said water-soluble component of a board | substrate surface is easily removed by wash | cleaning a board | substrate with an ultrapure water.

  A substrate surface processing apparatus according to claim 9 stores a substrate having an organic substance on the surface and is supplied with ozone gas and water vapor, a pump for controlling the internal pressure of the chamber to be lower than atmospheric pressure, A heating unit that heats the inner surface and the ceiling surface; and a cooling mechanism that cools the bottom surface of the chamber. The chamber is heated by the heating unit to the extent that water vapor is not liquefied, and the pump High-concentration ozone generated by mixing the ozone gas and the water vapor in a state where the internal pressure is controlled to be lower than the atmospheric pressure, and then condensing the water vapor containing ozone on the bottom surface cooled by the cooling mechanism The organic substance is removed by immersing the substrate in water. By immersing the substrate in high-concentration ozone water obtained by mixing ozone gas and water vapor at a pressure lower than atmospheric pressure, organic substances on the substrate surface are removed at a temperature lower than 100 ° C. Therefore, the popping phenomenon seen in the high dose ion implantation resist does not occur. The ozone gas may be one having an ozone concentration of several tens of percent or more. In the present invention, the risk of explosion can be avoided because ozone gas and water vapor are mixed at a pressure lower than atmospheric pressure.

  The substrate surface treatment apparatus according to claim 10 is the substrate surface treatment apparatus according to claim 9, wherein the supply of the ozone gas is performed by vaporizing the ozone-containing gas again after liquefying and separating only ozone based on the difference in vapor pressure. This is done with an ozone generator that generates high-concentration ozone gas. Since the ultra-high-concentration ozone gas is supplied from the ozone generator to the chamber, high-concentration ozone water is efficiently generated, so that organic substances can be effectively removed.

  The substrate surface treatment apparatus according to an eleventh aspect is the substrate surface treatment apparatus according to the ninth or tenth aspect, wherein ultrapure water is supplied to the chamber for cleaning the substrate treated with the high-concentration ozone water. Organic residue on the substrate surface is removed by washing with ultrapure water.

  A substrate surface treatment apparatus according to a twelfth aspect of the present invention is the substrate surface treatment apparatus according to any one of the ninth to eleventh aspects, wherein the cooling mechanism has a refrigerant flow path embedded in a bottom portion of the chamber. Since the bottom part of the chamber is cooled by the refrigerant flowing through the flow passage, when the water vapor containing ozone comes into contact with the bottom part, the water vapor mixed with the ozone condenses.

  The substrate surface treatment method and apparatus described above are particularly effective for removing novolak resists that are sensitive to G- and I-ray light.

  Therefore, according to the high concentration ozone water manufacturing method and apparatus of the above invention, high concentration ozone water can be manufactured efficiently. And the organic substance on the said board | substrate can be removed by immersing a board | substrate in this high concentration ozone water. In particular, a high dose ion implantation resist can be removed without causing a popping phenomenon.

  FIG. 1 is a cross-sectional view showing a schematic configuration of a high-concentration ozone water production apparatus (hereinafter referred to as an ozone water production apparatus) according to an embodiment of the invention.

  The ozone water production apparatus 1 includes a chamber 2, a vacuum pump 3, a heater 4, and a cooling mechanism 5.

The chamber 2 introduces ozone gas (O ₃ ) and water vapor (H ₂ O). The chamber 2 includes a chamber container 20 and a lid 21 that seals the chamber container 20. Ozone gas (O ₃ ) and water vapor (H ₂ O) are introduced through a pipe 6 heated to a temperature at which water vapor does not condense. The pipe 6 is installed on the lid 21. The lid 21 seals the chamber 2 via an O-ring 22 that is an auxiliary sealing member. As the O-ring 22, a sealing ring made of an ozone resistant material such as silicon rubber is employed. A pipe 7 for discharging the manufactured high-concentration ozone water is connected to the bottom 23 of the chamber 2. The pipe 7 is provided with a drain valve 8. The chamber 2, lid 21, piping and valves may be formed of a material having resistance to ozone gas such as stainless steel. In particular, in the microfabrication field represented by semiconductor manufacturing requiring a low metal impurity concentration, it is preferable to coat the inner surface with Teflon (registered trademark) or the like.

  As the ozone gas, an ultra-high concentration ozone gas is used. The ultra-high concentration ozone gas is obtained, for example, by vaporizing ozone-containing gas again after liquefying and separating only ozone based on the difference in vapor pressure. More specifically, ozone gas obtained from an ozone generator disclosed in Japanese Patent Application Laid-Open Nos. 2001-304756 and 2003-20209 can be given. The ozone generator produces an ultra-high-concentration (ozone concentration≈100%) ozone gas by liquefying and separating only ozone based on the difference in vapor pressure between ozone and other gas components (for example, oxygen). In particular, the ozone supply device disclosed in Japanese Patent Application Laid-Open No. 2003-20209 includes a plurality of chambers that liquefy and vaporize only ozone, and the temperature of these chambers can be individually controlled to continuously supply ultra-high-concentration ozone gas. . And as a commercially available ozone generator based on this super high concentration ozone gas continuous supply system, the pure ozone generator (MPOG-HM1A1) by Meidensha is mentioned, for example.

  The ozone gas is not limited to the ultra-high concentration ozone gas. For example, ozone gas having an ozone concentration of several tens% or more can be mentioned. At atmospheric pressure, the ozone concentration ranges from 14.3 to 38 vol% and becomes the persistent decomposition region, the ozone concentration ranges from -44 vol% to the impact region, and the ozone concentration ranges from 44 vol% to the ozone region (Hidetoshi Sugimitsu, Basic and Application of Ozone Kogyosha, 1996, pp. 187). In the ozone water production apparatus 1, since ozone gas and water vapor are mixed under a pressure lower than atmospheric pressure, the risk of explosion can be avoided.

  The vacuum pump 3 is a pump for reducing the pressure in the chamber 2. A pipe 10 connecting the chamber 2 and the vacuum pump 3 includes a valve 11. The valve 11 seals the gas phase in the chamber 2 so that the pressure in the chamber 2 becomes a predetermined value. The chamber 2, the pipe 10 and the valve 11 may be made of a material having resistance to ozone gas such as stainless steel.

  The heater 4 heats the side surfaces of the lid 21, the pipe 6, and the chamber 22 so that at least the water vapor introduced into the chamber 2 is not liquefied. What is necessary is just to apply the heater 4 used for the semiconductor technology.

  The cooling mechanism 5 cools the bottom so that water vapor containing ozone is condensed at the bottom of the chamber 2. The cooling mechanism 5 is formed by embedding a refrigerant flow passage 24 exemplified by cooling water in the bottom 23 of the chamber 2. The flow passage 24 is provided so as to cool the bottom surface of the chamber 2 as uniformly as possible.

  An operation example of the ozone water production apparatus 1 will be described with reference to FIGS. 1 and 3.

Ultra high-concentration ozone gas is enclosed in the chamber 2 under reduced pressure, and then water vapor is introduced. At this time, the inner surface and the ceiling surface of the chamber 2 (the lower surface of the lid 21) are heated to such an extent that the water vapor is not liquefied. For example, when the internal pressure of the chamber 2 is 100 hPa, the temperatures of the inner surface and the ceiling surface are kept at a temperature higher than 45 ° C., for example, 100 ° C. based on the saturation vapor pressure curve of FIG. On the other hand, the bottom of the chamber 2 is cooled by the cooling water flowing through the embedded flow passage 24. For example, when the internal pressure of the chamber 2 is 100 hPa, the temperature of the bottom is cooled to, for example, 45 ° C. or less, for example, 20 to 40 ° C. based on the saturated vapor pressure curve. As a result, water vapor mixed with ozone liquefies as dew condensation 25 on the bottom surface of the chamber 2. The above steps are repeatedly executed, and high-concentration ozone water 26 that does not contain impurities other than O ₃ such as NO _x and O ₂ is stored in the chamber 2. When a certain amount is stored, the supply of ultra-high concentration ozone gas and water vapor is stopped. The stored high-concentration ozone water 26 is discharged by the valve 8.

  FIG. 2 is a cross-sectional view showing a schematic configuration of a substrate surface processing apparatus according to an embodiment of the invention.

  The substrate surface treatment apparatus 30 removes organic substances including the resist on the surface of the substrate 31 with high-concentration ozone water. The substrate surface treatment apparatus 30 has the same configuration as the ozone water production apparatus 1 except that a holding part 32 on which a substrate 31 to be used for the removal of organic substances is placed is formed on the bottom surface part in the chamber 2. The holding portion 32 is formed by scraping the bottom portion according to the shape of the substrate.

  An example of the operation of the substrate surface treatment apparatus 30 will be described with reference to FIG.

Ultra high-concentration ozone gas is enclosed in the chamber 2 under reduced pressure, and then water vapor is introduced. At this time, the inner surface and the ceiling surface of the chamber 2 (the lower surface of the lid 21) are heated to such an extent that the water vapor is not liquefied as shown in FIG. For example, when the internal pressure of the chamber 2 is 120 hPa (ozone partial pressure 90 hPa, water vapor partial pressure 30 hPa), the temperature of the inner surface and the ceiling surface is a temperature higher than 45 ° C. based on the saturated vapor pressure curve of FIG. Incubated at ℃. On the other hand, the bottom 23 of the chamber 2 is cooled by cooling water (refrigerant) flowing through the embedded flow passage 24. For example, when the internal pressure of the chamber 2 is 120 hPa (ozone partial pressure 90 hPa, water vapor partial pressure 30 hPa), the temperature of the holding unit 32 is cooled to 45 ° C. or lower, for example, 20 to 40 ° C. based on the saturated vapor pressure curve. Thereby, water vapor mixed with ozone is condensed on the bottom surface of the chamber 2. The above steps are repeatedly performed to store high-concentration ozone water 26 that does not contain impurities other than O ₃ such as NO _x and O ₂ . This process is performed until the substrate 31 in the chamber 2 is immersed. When a certain amount is stored, the supply of ultra-high concentration ozone gas and water vapor is stopped. The stored high-concentration ozone water 26 is discharged by the valve 8. The substrate 31 treated with high-concentration ozone water is further cleaned with ultrapure water. The ultrapure water may be introduced from the pipe 6. The organic components of the substrate 31 treated with ozone gas and water vapor are oxidized and decomposed into water-soluble components (eg, aldehydes and hydroxides) by reaction with ozone gas and water vapor (edited by the Chemical Society of Japan, quarterly chemistry review). , No. 7, Chemistry of active oxygen, published April 20, 1990, pp. 36-37). Therefore, the residue made of the water-soluble component on the surface of the substrate 31 is easily removed by cleaning the substrate 31 with ultrapure water. In addition, it is considered that the resist which has deteriorated by being washed with ultrapure water can be removed and thinned.

  Table 1 shows a test example in which the resist was removed as an example of the organic substance by the substrate surface treatment apparatus 30. A Si substrate having OFPR-800 (resist having sensitivity to light of G-line (436 nm)) manufactured by Tokyo Applied Chemical Industry as a novolak / diazonaphthoquinone-based resist was stored in the chamber 2. The temperature of the side wall of the chamber 2 was adjusted to about 100 ° C., and the temperature of the holding unit 32 was adjusted to 40 ° C. or less (36 to 40 ° C.). Next, ultra high concentration ozone gas and water vapor were supplied to the chamber 2 to cause condensation to such an extent that the substrate was immersed. A pure ozone generator (MPO-HM1A1) manufactured by Meidensha was used as the ozone generator 9 for supplying the ultra-high concentration ozone gas. The substrate was sealed for 5 minutes under an ozone partial pressure of 9000 Pa and a water vapor partial pressure of 3000 Pa, and then washed with ultrapure water. Table 1 shows the resist film thickness [nm] before and after treatment, the difference between the film thickness [nm] before and after treatment, and the stripping rate [nm / min]. Table 1 discloses the results of ashing the three samples S1 to S2 (substrate having the resist).

  As is clear from the results shown in Table 1, it was confirmed that the organic material exemplified in the resist can be removed under a temperature lower than 100 ° C. according to the substrate surface treatment method according to the invention. It was also confirmed that no popping phenomenon occurred in any of the substrates.

Sectional drawing which showed schematic structure of the high concentration ozone water manufacturing apparatus which concerns on embodiment of invention. Sectional drawing which showed schematic structure of the substrate surface processing apparatus which concerns on embodiment of invention. Saturated water vapor pressure curve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ozone water production apparatus 2 ... Chamber 3 ... Vacuum pump 4 ... Heater 5 ... Cooling mechanism, 23 ... Bottom part, 24 ... Flow path 25 ... Condensation, 26 ... High concentration ozone water 6, 7, 10 ... Pipe 8, 11 ... Valve 9 ... Ozone generator 30 ... Substrate surface treatment device 31 ... Substrate 32 ... Holding part

Claims (12)

  A method for producing high-concentration ozone water, comprising mixing ozone gas and water vapor at a pressure lower than atmospheric pressure, and then cooling and condensing the water vapor containing ozone to produce high-concentration ozone water.   2. The method of producing high-concentration ozone water according to claim 1, wherein the ozone gas is an ultra-high-concentration ozone gas obtained by vaporizing ozone-containing gas again after liquefying and separating only ozone based on a difference in vapor pressure. . A chamber to which ozone gas and water vapor are supplied;
A pump for controlling the internal pressure of the chamber to be lower than the atmospheric pressure;
Heating means for heating the inner surface and the ceiling surface of the chamber;
A cooling mechanism for cooling the bottom surface of the chamber,
After the chamber is heated by the heating means to the extent that water vapor is not liquefied, and the ozone gas and the water vapor are mixed with the pump while the internal pressure of the chamber is controlled to be lower than atmospheric pressure, the ozone is An apparatus for producing high-concentration ozone water, wherein the contained water vapor is condensed on the bottom surface cooled by the cooling mechanism.   The ozone gas supply is performed by an ozone generator that generates an ultra-high-concentration ozone gas by liquefying and separating only ozone from the ozone-containing gas based on a difference in vapor pressure and then vaporizing the ozone-containing gas again. The high-concentration ozone water production apparatus described.   5. The high-concentration ozone water production apparatus according to claim 3, wherein the cooling mechanism has a refrigerant flow passage embedded in a bottom portion of the chamber.   After mixing ozone gas and water vapor at a pressure lower than atmospheric pressure, the substrate is immersed in high-concentration ozone water generated by cooling and condensing the water vapor containing ozone to remove organic substances on the substrate surface. And a substrate surface treatment method.   7. The substrate surface treatment method according to claim 6, wherein the ozone gas is an ultra-high-concentration ozone gas obtained by vaporizing ozone-containing gas again after liquefying and separating only ozone based on a difference in vapor pressure.   The substrate surface treatment method according to claim 6 or 7, wherein the substrate treated with the high-concentration ozone water is washed with ultrapure water. A chamber for storing a substrate having an organic substance on the surface and supplied with ozone gas and water vapor;
A pump for controlling the internal pressure of the chamber to be lower than the atmospheric pressure;
Heating means for heating the inner surface and the ceiling surface of the chamber;
A cooling mechanism for cooling the bottom surface of the chamber,
After the chamber is heated by the heating means to the extent that water vapor is not liquefied, and the ozone gas and the water vapor are mixed with the pump while the internal pressure of the chamber is controlled to be lower than atmospheric pressure, the ozone is An apparatus for treating a surface of a substrate, comprising: dipping the substrate in high-concentration ozone water generated by condensation of water vapor contained in the bottom surface cooled by the cooling mechanism to remove the organic matter.   The ozone gas supply is performed by an ozone generator that generates ultra-high-concentration ozone gas by liquefying and separating only ozone from the ozone-containing gas based on a difference in vapor pressure and then vaporizing again. The substrate surface treatment apparatus as described.   11. The substrate surface processing apparatus according to claim 9, wherein ultrapure water is supplied to the chamber to clean the substrate treated with the high-concentration ozone water.   12. The substrate surface processing apparatus according to claim 9, wherein the cooling mechanism has a refrigerant flow path embedded in a bottom portion of the chamber.

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