JPWO2008153107A1 - Object cleaning method and object cleaning system - Google Patents

Abstract

In a method for cleaning an object by irradiating a mixed phase fluid containing gas and droplets, a degree of cavitation at the time of droplet collision that can occur when the droplets in the mixed phase fluid collide with the object A method characterized by obtaining a desired impact force by controlling.

Description

  The present invention uses a semiconductor substrate / glass substrate / lens / disk member / precision machined member / mold resin member as an object (particularly a semiconductor substrate having an aluminum material such as aluminum wiring on the surface). The present invention relates to a method for treating a part or a predetermined surface and a system thereof (for example, an object cleaning method and an object cleaning system), and more specifically, cleaning of a part or a surface, and removal or peeling of unnecessary materials there. , A method for polishing and processing the surface of an object and a system thereof (for example, a processing method in a semiconductor manufacturing apparatus such as a resist peeling apparatus, a polymer peeling apparatus and a cleaning apparatus, a printed board cleaning apparatus, a photomask cleaning apparatus, etc.) Is.

  In the semiconductor pretreatment process, cleaning is repeated 50 to 100 times for one wafer. The object of the cleaning is an organic substance such as a resist film or a polymer film, particles, or the like that affects device reliability. In this cleaning step, a combination of an alkali cleaning solution and an acid cleaning solution and other chemicals such as sulfuric acid / hydrogen peroxide are usually used, and a large amount of pure water is used in a rinsing step for removing the residue. In addition, a plasma ashing apparatus is generally used for removing the resist, but another cleaning apparatus is used for the subsequent cleaning of residues and impurities. Further, amine-based organic solvents are often used for removing the polymer film. This chemical solution may also be used for resist removal. Here, the chemicals used for the above-described conventional cleaning and thin film removal are 1) expensive, 2) large environmental load and special wastewater treatment equipment is required, and 3) safety and health of workers. In order to secure the equipment, the size of the equipment is increased, and cleaning with chemicals requires a large amount of pure water to wash away the chemicals. 4) One device cannot cover everything from thin film removal to cleaning. .

  Moreover, if it limits to the washing | cleaning process which does not use a chemical | medical solution, the following main techniques will exist. First, the ultrasonic cleaning apparatus is the most widely used cleaning technique at present and is sometimes combined with various cleaning liquids as well as pure water. The disadvantage is that there is concern about damage to soft materials, brittle materials and fine patterns due to cavitation (which is different from the mechanism of cavitation of the present invention as will be described later). For this reason, measures such as increasing the frequency are taken, but there is a trade-off with the cleaning power. Next, the water jet cleaning apparatus is applied to a relatively large cleaning object. The drawback is that high pressure (several MPa to 20 MPa) is required, which is not suitable for an object having a fine pattern. Next, the brass scrub cleaning apparatus is sometimes combined with various cleaning liquids as well as pure water. The disadvantage is that it is not suitable for surfaces with deep grooves or holes. In addition, since the object surface and the brush are in direct contact with each other, there is a possibility of generating dust and scratches.

  In addition, there is a cleaning apparatus that irradiates only water vapor. This apparatus also has a very small environmental load because it does not use chemicals. However, since this apparatus does not use 1) droplets, it is less effective for objects that are relatively strongly bonded, such as photoresist or foreign matter on the wafer. 2) The pressure of the steam generator is low. Since it is the only parameter, it has the disadvantage that the optimum condition according to the object cannot be adjusted.

Therefore, in recent years, a cleaning apparatus that irradiates a combination of water vapor and liquid fine particles has been proposed (Patent Document 1). In this technique, vaporized water (water vapor) first infiltrates into the resist film and reaches the interface between the resist film and the object surface, weakens the adhesive force of the resist film at this interface, and the resist film is removed from the object surface. Lift from (lift off). Next, mist-like water (water mist) containing liquid fine water particles with a predetermined spray pressure physically acts on the resist film lifted off and is peeled off from the interface. And paragraph number 0019 of patent document 1 describes the cavitation using a thermal effect phenomenon as a basic principle of the said technique. Specifically, when normal temperature pure water and high temperature water vapor are mixed, vibration having a certain frequency (10 KHz to 1 MHz) is generated by the heat exchange. This vibration causes the water molecules to be decomposed into hydrogen ions and hydroxide ions, and the high energy generated when these unstable ions return to the water molecules again is converted into a mechanical shock.
WO2006 / 018948

  However, when using a cleaning device that irradiates a combination of water vapor and water as disclosed in Patent Document 1, first, a phenomenon that requires a certain amount of time for the reaction, such as penetration of water molecules, and mist-like mist Since it uses the real-time phenomenon of removing the film and dirt by directly colliding with the resist film and particles, there is a problem that the treatment time is limited by the penetration time of water molecules, and secondly, cleaning There is a problem that often the situation where the power is insufficient and the dirt on the object cannot be sufficiently removed, or on the contrary, the cleaning power is too strong to damage the object. In such a case, for example, measures have been taken to increase the ejection pressure in the former case and lower the ejection pressure in the latter case. In this way, the present situation is that the cleaning power is adjusted by using only the hydrodynamic action (collision force or the like). However, in this case, in the former case, since the jet pressure is increased, the steam temperature becomes high and it becomes impossible to target a material having low heat resistance, or the collision force becomes too strong and damage to the object may occur. There is a concern. On the other hand, in the latter case, there is a problem that the cleaning of the object is insufficient even though the situation of damaging the object due to the low jet pressure can be avoided. Therefore, a first object of the present invention is to provide means for reliably washing without damaging the object without being limited by the water molecule permeation time.

  Furthermore, the present inventors have empirically found that when a semiconductor substrate is washed with a mixed phase flow of water and water vapor, aluminum formed on the surface of the semiconductor substrate is corroded early. As described above, if aluminum is corroded before the next treatment is performed, it may not function as a semiconductor device, resulting in a poor yield. Accordingly, the second aspect of the present invention provides a means for preventing the aluminum formed on the surface of the semiconductor substrate from being corroded for a long time even when the semiconductor substrate is washed with a mixed phase flow of water and water vapor. Objective.

  The present inventor pays attention to cavitation having a completely different mechanism of action from the above and controls the degree of cavitation on the object, thereby enabling effective and easy processing suitable for the object. And the present invention has been completed.

  Furthermore, in order to increase the cleaning power, the present inventor has focused on the speed of the droplets contained in the multiphase fluid rather than the pressure of the gas, and has intensively studied to increase the speed. Then, when the droplet velocity is increased using a specific nozzle, the object to be removed attached to the object has a sufficient impact force without causing the object to break or the surface pattern to collapse as described above. The present invention has been completed.

The present invention (1) is a method for cleaning an object, which includes a step of irradiating a mixed phase fluid containing water vapor in a continuous phase and water droplets in a dispersed phase, which is generated by mixing water vapor and water.
The irradiation is performed using an ultra-high speed nozzle, the speed of the water droplet is in the range of 100 to 600 m / s, the temperature when the mixed phase fluid reaches the target is 50 ° C. or more, and the mixed phase fluid reaches the target The pH is in the range of 7-9.

Further, in one aspect, the present invention (A) cleans an object including a step of irradiating a mixed phase fluid containing continuous phase water vapor and dispersed phase water droplets, which is generated by mixing water vapor and water. In the way to
The irradiation is performed using an ultra-high speed nozzle, and the speed of the water droplet is in the range of 100 to 600 m / s.

  Further, in one aspect, the present invention (B) is an invention in which the temperature when the mixed phase fluid reaches the target is 50 ° C. or higher, and the pH when the mixed phase fluid reaches the target is in the range of 7-9. This is the method (A).

  The present invention (2) is the method of the present invention (1), wherein the distance between the mixed phase fluid ejection outlet and the object is 30 mm or less.

  The present invention (3) is the method of the invention (1) or (2), wherein the object is a semiconductor substrate having an aluminum material such as an aluminum wiring on its surface.

The present invention (4) has a water vapor supply means {for example, a water vapor supply section (A)} for supplying water vapor and a water supply means {for example, a pure water supply section (B)} for supplying liquid water, In a system for cleaning an object by irradiating a mixed phase fluid containing water vapor and water droplets,
It is a system characterized by being provided with an ultra-high speed nozzle for performing the irradiation.

  Hereinafter, the meaning of each term in this specification is explained. First, the “water droplet” is a concept including not only water droplets derived from water but also minute water droplets derived from wet saturated water vapor. The “multiphase fluid” is a fluid having a plurality of fluid components such as two fluids and three fluids, for example, 1) saturated water vapor and pure water droplets having a boiling point or less, and 2) heated steam and pure water droplets having a boiling point or less. 3) A combination of the above 1) or 2) with an inert gas or clean high-pressure air can be mentioned. However, oxygen gas and other active gases may be used when used in applications where the oxidation or chemical reaction of the object is not concerned. From the viewpoint of preventing corrosion of aluminum, it is preferable to use a two-phase flow of only water and water vapor or a combination of these with an inert gas. The “object” is not particularly limited, and examples thereof include an electronic component, a semiconductor substrate, a glass substrate, a lens, a disk member, a precision machined member, and a mold resin member. The “treatment” is not particularly limited as long as it is applied to an object, and examples thereof include peeling, washing, and processing. "Water" is a characteristic that is used as pure water or ultrapure water for applications such as cleaning processes in semiconductor device manufacturing where contamination of fine foreign objects or metal ions is anxious. It refers to water, and uses that do not care about contamination such as minute foreign substances and metal ions on the object include even lower grade tap water. A “system” is not only an “apparatus” that houses each component in an integrated manner, but also each component is placed in a physically separated position (for example, a plant), or each component is information Even if it is not connected in a communicable manner, it is applicable to the system as long as it has all the components having the functions defined in the claims. “Ultra-high-speed nozzle” means a nozzle capable of accelerating a droplet at a speed higher than the sound speed.

  Here, the cavitation at the time of droplet collision according to the present invention will be described in detail with reference to the drawings in order to clarify the difference from cavitation of other mechanism of action known in the field related to object processing. . Note that the mechanism of action described here is only a prediction. Therefore, the present invention is not limited to the mechanism of action.

First, the general concept of cavitation is described below.
Normally, boiling begins when the temperature of the liquid rises above the saturation temperature at that pressure, but the liquid begins to boil even when the pressure of the liquid drops below the saturation pressure at that temperature. That is, vapor bubbles are generated in the liquid. In this way, bubbles generated by boiling due to the pressure reduction effect, not due to temperature change, are usually called cavitation bubbles. When the bubbles contract and collapse, high pressure is generated, and erosion, noise, and the like are generated. This phenomenon is sometimes called cavitation.

In an ultrasonic cleaning apparatus conventionally used for cleaning, cavitation occurs due to the following mechanism of action (FIG. 24).
1. The ultrasonic wave propagates into the liquid medium by the ultrasonic generator.
2. The sound wave travels through the liquid medium by repeating compression and decompression in a violent cycle.
3. In the process of moving from compression to decompression, the pressure is locally reduced to below the saturated water vapor pressure.
4). Then, bubble growth (room temperature boiling) starts.
5). Further, non-condensable gas dissolved in the liquid medium is also mixed into the growth vapor bubbles.
6). Bubbles grow further.
7). The bubbles receive the following compressive force and are compressed adiabatically to have high energy.
8). The bubbles are finally crushed and collapsed.
9. When crushed, it becomes extremely large impact energy locally and dissociates surrounding dirt.
10. A sound wave is normally generated by a traveling wave that travels in the medium and a reflected wave that is reflected by the liquid surface.
11. In this case, cavitation occurs in a striped manner in the medium along the maximum sound pressure body.

  Next, with regard to the cavitation generated by the method according to the present invention, a possible generation mechanism will be described with reference to a previously reported example (Martin Rein, “Drop-Surface Interactions (Cism International Center for Mechanical Sciences Courses and Lectures) "pp.39-102, Martin Eein ed., Springer-Verlag, 2002,).

1. When the droplet collides with the solid interface at a certain speed, the kinetic energy of the droplet is converted into pressure energy, and a high pressure is generated at the contact surface between the droplet and the solid interface (FIG. 25).
2. The generated pressure propagates upward inside the droplet as a pressure wave (compression wave) and reaches the boundary surface between the droplet and the surrounding gas, that is, the free interface (FIG. 26).
3. Since the acoustic impedance of water is overwhelmingly larger than the acoustic impedance of the surrounding gas, impedance mismatching occurs, and the pressure wave reflects almost 100%. That is, since the propagation of the pressure wave to the surrounding gas becomes very small, as a result, the pressure change on the free interface is suppressed to a small level (FIG. 27).
4). The pressure change on the free interface is reduced because an expansion wave that cancels the compression wave, that is, a pressure wave lower than the surroundings is generated and propagates into the liquid.
5). The expansion wave propagating into the droplet reduces the pressure inside the droplet. If the temperature of the droplet is about 30 ° C., about 0.04 atm, about 60 ° C. about 0.2 atm, about 80 ° C. If it drops to about 0.5 atm, boiling starts. Bubbles are generated and grow (FIGS. 28 and 29).
6). The generated vapor bubbles take in non-condensable gas in the liquid while growing and become larger.
7). Fully grown bubbles reach the growth limit and begin to rebound or shrink. Since the contraction process occurs abruptly compared to the expansion process, the bubbles contract extremely, and the internal pressure of the bubbles can reach an extremely higher pressure than that at the start of growth. This high pressure is called bubble collapse pressure.
8). Bubble collapse is also induced by the disturbance of the bubble ambient conditions. Also, the bubbles are not necessarily single and collapse, but rather collapse as a group of bubbles in which the bubbles are accumulated. It has been reported that the bubble collapse pressure in such a case is several hundred times or more of the single bubble collapse pressure.
9. The bubble collapse pressure generated inside the droplet propagates inside the droplet as a pressure wave (compression wave), reaches the contact surface between the droplet and the solid surface, and generates a very large pressure on the solid surface. . This is the collapse pressure of cavitation generated at the time of droplet collision, and cleaning is performed using this pressure.

  Essentially, in the present invention, the thermal environment around the droplet is kept sufficiently high by water vapor or prevents heat leakage from the droplet. Therefore, even if the pressure drop due to the expansion wave inside the droplet is not severe, it is a condition that bubbles can be generated sufficiently. Because of this characteristic, it is sufficient that the droplets have a rapid velocity and can generate a certain amount of compression waves even if they do not collide with the solid surface as in other inventions. .

  The most peculiar point of the present invention is that cavitation is generated by a droplet having a velocity generated at a pressure about two orders of magnitude lower than other inventions.

  According to the present invention, cavitation at the time of droplet collision that occurs when a droplet collides with the surface of the object is different from the conventional method in which the impact force to the object is controlled by adjusting the ejection pressure (hydrodynamic action). Is used to process the target, so there is a conventional problem caused by the high and low jet pressure, specifically, the collision force becomes too strong and the target may be damaged. In addition, even if the situation of damaging the object due to the low jet pressure can be avoided, the problem of insufficient cleaning of the object can be solved. Furthermore, since the droplet temperature at the time of collision greatly affects the cavitation at the time of the droplet collision, the degree of cavitation (whether or not it occurs and the degree thereof) can be easily controlled by changing the temperature of the droplet. It is possible. In addition, even under a low jet pressure, if the droplet temperature is increased, the object can be processed efficiently, and problems due to the high jet pressure can be avoided. Furthermore, when the gas is water vapor, even if it causes a heat transfer from the water vapor to another medium, the temperature of the entire system may decrease as a result of being utilized from the latent heat of the water vapor. It can be avoided.

  More specific actions and effects of the present invention are as follows. (1) Cracks or holes on the film that trigger film peeling are generated by a high-speed side jet generated after droplet collision, a shock wave due to bubble collapse, or an impact force (cavitation) of a chain reaction caused by the shock wave. (2) A droplet jet, shock wave, chain reaction by shock wave, and high-speed side jet are generated, and the film is turned up and peeled starting from the crack or hole described in (1). (3) The material of the object is made brittle by steam, which is water having a large thermal temperature energy, or stress is generated to weaken the adhesion at the interface between the object and the substrate. (4) By changing the combination of these functions according to the object, the object to be cleaned and the object to be removed can be expanded. (5) The present invention can be applied not only to removing impurities, but also to the use of removing unnecessary photoresist after the etching process or ion implantation process and removing unnecessary polymer after the etching process.

In addition, according to the present invention (1) {the present invention (A)} and (4), the speed of water droplets is increased by using an ultra-high speed nozzle. For this reason, the droplets are subdivided to reduce the droplet diameter. Therefore, it is difficult for droplets having a large diameter that cause cracking of the wafer or collapse of the pattern to be generated, and the problem is less likely to occur even if the pressure is increased.
Furthermore, when using an ultra-high speed nozzle, it was observed that the mixed phase fluid injecting water vapor and water droplets and the mixed phase fluid of air and water droplets exhibited the following two unique behaviors.
First, it has been clarified that by injecting a mixed phase fluid of water vapor and water using an ultra-high speed nozzle, a pressure wave is observed near the outlet in the nozzle (Example 30). As a result, the droplets are further subdivided in the nozzle and the droplet diameter is reduced. Therefore, there is an effect that even if the pressure is increased, problems such as wafer breakage and surface pattern collapse do not occur.
The second is the relationship between gas pressure and droplet velocity and / or average particle size. When the gas pressure is increased, in the case of a multiphase fluid of air and water, the droplet velocity increases as the pressure increases, whereas in the case of water vapor and water, measurement was possible up to a predetermined pressure. If the pressure is exceeded, measurement becomes impossible (Example 28). In addition, when observing the relationship between the gas pressure and the average particle size of water droplets, the particle size does not depend on the gas pressure in a mixed phase fluid of air and water. Was found to be unreliable (Example 29). This means that there is a pressure in a region that can be measured with a mixed phase fluid of air and water but cannot be measured with a mixed phase fluid of water vapor and water. That is, at the pressure, the mixed phase fluid of water vapor and water exhibits at least some different behavior from the mixed phase fluid of air and water. Although the difference in the behavior is not clear, it can be considered that the reason why the measurement is impossible is that the droplet velocity is too high or the droplet diameter is too small.

  Moreover, according to the present invention (1) {the present invention (B)}, in addition to sufficient impact obtained by the above cavitation, even when the semiconductor substrate is washed with a mixed phase flow of water and water vapor, There is an effect that aluminum formed on the surface of the semiconductor substrate is hardly corroded for a long time. For example, after the dry etching of aluminum, if the resist on the object is peeled off by the method according to the present invention (1) {the present invention (B)}, the effect that the aluminum wiring is not corroded in the time until the next step is obtained. Be looked at.

  According to the present invention (2), since the distance between the multiphase fluid injection outlet and the object is short, the multiphase fluid is difficult to take in carbon dioxide in the atmosphere, and the pH is less likely to be acidic. There is an effect of demonstrating.

  Hereinafter, as the best mode, a “wafer cleaning apparatus” is taken as an example of the object processing apparatus, and the present invention will be specifically described. The best mode is merely the best example and does not limit the technical scope of the present invention.

Configuration of Multiphase Fluid First, the multiphase fluid in the best mode includes continuous phase water vapor and dispersed phase water droplets generated by mixing water vapor and water. Here, the “water droplets” are made of pure water suitable for processing an object made of a material that dislikes chemicals (in addition, a part of water vapor with high wetness). The mixed phase fluid may optionally contain an inert gas such as argon or nitrogen and clean high-pressure air. However, from the viewpoint of preventing corrosion of aluminum, the optional gas is preferably argon or an inert gas.

  Here, the reason for using water vapor is that, in addition to high specific heat, latent heat can be used, and even under conditions where the amount of heat held by the droplets is deprived as the fluid pressure changes, the temperature is almost the same. This is because it is advantageous in that it does not decrease. When water droplets and gas are mixed in the fluid mixing unit, heat transfer occurs between the water droplets and the gas, or heat transfer occurs between the water droplets and the inner wall of the mixing unit or piping. Further, when the nozzle portion is accelerated and released into the atmosphere, decompression expansion occurs, so that the gas temperature decreases. At this time, whether or not the temperature of the water droplet is lowered is determined by the latent heat of the gas. When a gas that does not contain a lot of latent heat, for example, an inert gas or clean high-pressure air and pure water, is mixed, the temperature of the gas decreases and temperature control becomes difficult. On the other hand, when the gas is water vapor, it has a predetermined amount of latent heat, so even when mixed with relatively low temperature water droplets or when heat is taken away by the inner wall of the pipe, the temperature of the gas is moved by heat transfer. Is less likely to decrease, and the temperature tends to be easily controlled. However, if the latent heat of the water vapor is not sufficient, droplets are generated as a part of the water vapor is liquefied, which affects the shock wave generated on the surface of the object to be treated. In addition, when this multiphase fluid is finally accelerated at the nozzle part of the nozzle, the temperature of the fluid decreases to obtain the kinetic energy of the fluid, but the temperature of the fluid decreases due to the latent heat of water vapor. Can be reduced.

Overall Structure of Object Processing Apparatus FIG. 1 is an overall view of an object processing apparatus 100 according to an embodiment of the present invention. The apparatus 100 includes a water vapor supply unit (A), a pure water supply unit (B), a water vapor fluid adjustment unit (C), a mixed phase fluid irradiation unit (D), and a wafer holding / rotating / vertical mechanism unit (E). It is. Hereinafter, each part will be described in detail.

(A) Water vapor supply unit The water vapor supply unit (A) controls the generation amount of water vapor by generating water vapor by heating to a water supply pipe 111 for supplying pure water and a predetermined temperature D1 (° C.) or higher. The steam generator 112 that pressurizes the steam to a predetermined value C1 (MP), the steam opening / closing valve 113 that can open and close to supply and stop the steam, and the pressure of the steam supplied downstream from the steam generator 112 A pressure gauge 114 for measuring, a steam pressure adjusting valve 115 for adjusting the steam supply pressure to a desired value, and a heating steam generator / saturated steam with a temperature control mechanism for adjusting the amount of fine droplets in the supplied steam It comprises a wetness adjuster 116 and a pressure release valve 117 as a safety device.

(B) Pure water supply unit The pure water supply unit (B) includes a water supply pipe 121 for supplying pure water, a pure water temperature control mechanism additional heat unit 122 for giving pure water thermal energy, Pure water opening / closing valve 123 for controlling stop and restart of pure water, pure water flow meter 124 for confirming the flow rate of pure water, and stopping and restarting the supply of pure water downstream in the case of two fluids And a two-fluid production pure water on-off valve 125.

(C) Steam fluid adjusting unit The steam fluid adjusting unit (C) includes a steam fluid temperature control mechanism additional heat unit 131 for adjusting the temperature of the steam fluid and the wetness of the saturated steam.

ここで、κは気体の比熱比（定圧比熱／定容比熱）であり、P₁はノズルのど部の圧力であり、P₂はノズル出口における圧力である。当該、ひろがり率とのど部の断面積A_３により、ノズル出口の断面積A_２が求められる。ここで、ノズル出口の断面積Ａ_２は、特に限定されないが、例えば、７．０〜２８．０ｍｍ^２である。また、ノズルの長さは、ノズルの材料、粗度、流速（レイノルズ数）等の各種のパラメータを考慮に入れて、適宜値を設定可能である。また、拡径は、粘度、密度、流速等の各種パラメータを考慮に入れて、適宜値を設定可能である。尚、温度制御機能付混相流体気液混合部１４４については、後で詳述する。(D) Multi-phase fluid irradiation unit The multi-phase fluid irradiation unit (D) moves in the front-rear and left-right directions (X-axis nozzle scan range or Y-axis nozzle scan range in FIG. 1) for irradiating the target with the multi-phase fluid. Possible irradiation nozzle 141, flexible pipe 142 for smoothly moving the nozzle, pressure gauge 143 for measuring the pressure of the mixed phase fluid immediately before the nozzle, and pure water smoothly introduced into the steam pipe In addition, it is composed of a mixed phase fluid / gas / liquid mixing unit 144 with a temperature control function for minimizing a phase change in the mixing unit, and an orifice 145 for smoothly introducing pure water into the gas pipe. Here, the nozzle 141 is an ultra-high speed nozzle. The “ultra-high speed nozzle” is not particularly limited as long as it is a nozzle capable of accelerating the liquid droplets at a speed higher than the sound speed, and examples thereof include a sonic nozzle. FIG. 30 is a sectional view of the sonic nozzle according to the best mode. Position shape of the sonic nozzle is not particularly limited, the nozzle is abruptly reduced in diameter toward to the nozzle outlet is located in the drawing downward from the nozzle back of the drawing upwards, that further, the minimum cross-sectional area A ₃ It has a divergent nozzle structure where the diameter of the fluid gradually increases so that the fluid does not peel from the inner wall at the (throat), and the cross-sectional area is A ₂ at the nozzle outlet. Sectional area of the throat portion A ₃ is calculated by dividing the flow rate at the speed of sound. Sectional area _{A 3} of the throat portion is not particularly limited, for example, a 3.0~20.0mm ^2. Further, the spreading rate (A ₃ / A ₂ ) is calculated by the following equation (1).

Here, κ is the specific heat ratio of gas (constant pressure specific heat / constant volume specific heat), P ₁ is the pressure at the nozzle throat, and P ₂ is the pressure at the nozzle outlet. The, the cross-sectional area A ₃ of the spreading rate and the throat portion, the sectional area A ₂ of the nozzle outlet is required. Here, the cross-sectional area _{A 2} of the nozzle outlet is not particularly limited, for example, a 7.0~28.0mm ^2. The length of the nozzle can be appropriately set in consideration of various parameters such as nozzle material, roughness, flow rate (Reynolds number), and the like. Further, the diameter expansion can be appropriately set in consideration of various parameters such as viscosity, density, and flow rate. The mixed phase fluid / liquid mixing unit 144 with temperature control function will be described in detail later.

(E) Wafer Holding / Rotation / Up / Down Mechanism Unit The wafer holding / rotation / up / down mechanism unit (E) includes a stage 151 on which an object (wafer) can be mounted / held, and a rotation motor 152 for rotating the stage 151. , A wafer vertical drive mechanism 153 capable of adjusting the distance between the outlet of the nozzle 141 and the wafer by moving the stage 151 in the vertical direction, and a cooling water pipe 154 for supplying cooling water for cooling the object (wafer), , An openable / closable cooling water opening / closing valve 155 for stopping and restarting the cooling water supply, a cooling water flow rate adjusting valve 156 for adjusting the flow rate of the cooling water, and a cooling water for measuring the flow rate of the cooling water A flow meter 157.

  The overall configuration of the object processing apparatus according to the best mode has been outlined above. Next, the mixed phase fluid-gas-liquid mixing unit 144 with a temperature control mechanism in the pure water supply unit (D) will be described in detail. Here, FIG. 2 is a diagram illustrating a detailed configuration of the mixing unit 144. In the mixing unit 144, it is important to minimize the occurrence of a phase change phenomenon such as liquefaction of water vapor or vaporization of water on the inner wall of the mixing unit. For this reason, as shown in FIG. 2, it is preferable that the mixing unit 144 has the following structure.

1) In order to stabilize mixing, the direction of each fluid of gas and liquid has an angle of less than 90 degrees at the mixing portion.
2) The pipe diameter of the liquid fluid or the orifice attached to the pipe is sufficiently smaller than the cross-sectional area of the flow path of the gas fluid at the mixing section.
3) By incorporating a heater in the mixing section, the inner wall temperature of the mixing section is controlled to meet the following conditions. Further, the temperature of the inner wall does not greatly deviate from the saturation temperature of the liquid under the pressure in the mixing part (within ± 20%). Further, the temperature of the inner wall should not greatly deviate from the saturation temperature of the gas under the pressure in the mixing part (within ± 20%). In addition, since the inner wall of the mixing unit approaches the saturation temperature of the fluid over time, the temperature of the mixing unit is sufficiently kept for applications where the time until the state of the multiphase flow becomes stable is not an issue. Under this condition, the heating function by the heater can be removed.

  In an apparatus that processes an object with a mixed phase fluid in which droplets and gas are mixed, the fluid mixing unit is at room temperature when the apparatus is activated. If there is a temperature difference between the part and the water vapor, the liquid mixing device may have a temperature unevenness, which causes the discharge pressure of the multiphase fluid to be unsatisfactory due to a phase change of a part of the steam into water droplets. It becomes stable and it is difficult to stably apply a certain shock wave on the surface of the object to be processed, so that it takes time until the apparatus operates stably. That is, when a heater is installed in the mixed phase fluid adjustment unit, the fluid mixing unit can be set to the same temperature as the temperature of the water vapor from the beginning of the operation, and the device is less likely to cause a gas-liquid phase change in the mixing unit. A stable shock wave can be applied to the target processing surface.

Principle of cavitation control (bubble collapse related parameters)
The cleaning device according to the best mode includes a gas pressure, a water mixing flow rate in a multiphase fluid, a gas temperature, a temperature of water to be mixed, a nozzle shape, a distance from a nozzle outlet to an object, a temperature of the object, a nozzle and an object By adjusting the relative movement time between objects, the temperature of the droplet, the velocity of the droplet, the size of the droplet, the number of droplets, the temperature of the surface of the object to be processed, and the area of multiphase fluid irradiation per unit time It has a function to control. Among these bubble collapse related parameters, the flow velocity, temperature, and droplet density of the droplet are particularly important. By controlling these parameters, it is possible to obtain a shock wave due to a jet of droplets or bubble collapse on the surface of the object to be processed, and an impact force of a chain reaction due to the shock wave. I can do it. The flow velocity contributes to the generation of a shock wave due to the collapse of bubbles in the droplet when the droplet collides, and the temperature contributes to the generation of bubbles in the droplet. Also, the higher the droplet density, the higher the probability that a shock wave will occur. For example, if the number of droplets is zero, a shock wave due to droplet collision does not occur. However, even if the number of droplets becomes too dense, there is a possibility that the velocity of the multiphase fluid is lowered and the temperature is lowered, so that the probability of shock wave generation is lowered. Here, droplet density refers to the total number of droplets per unit volume and time in a multiphase fluid, but measuring instruments that accurately measure micro-order droplets moving at high speed are still being developed. Therefore, the amount of pure water introduced into the mixed phase fluid should be substituted.

Cavitation measurement means The system according to the present invention includes a measurement means for measuring how much cavitation occurs under the condition after irradiating the object or the measurement sample with a multiphase flow under a certain condition. Yes. Here, with the current technology, it is impossible to perform the peeling / cleaning process while monitoring the magnitude (cavity magnitude) and density (number of occurrences per unit area / time) of cavitation (shock wave). Therefore, in this system, a method is adopted in which parameters related to the occurrence of cavitation are changed in advance experiments, process processing is performed, and the size of cavitation is determined from the following data obtained as a result.

(1) Physical change measuring means for quantitatively measuring the physical change of an object or a measurement sample ・ Roughness of the metal surface when the metal surface is irradiated with a multiphase fluid ・ Resist when the resist surface is irradiated Peeling area and small amount of residue ・ Removal rate of foreign matter adhered to the entire wafer surface (2) Acoustic measurement means capable of detecting the magnitude of cavitation noise ・ Cavitation noise magnitude detected by an acoustic sensor (3) Object Or visual change measurement means for quantitatively measuring the visual change of the measurement sample ・ Image data of resist stripping process taken with a high-speed camera

  For example, the data of the multiphase fluid temperature and the degree of unevenness of the metal surface irradiated with it are confirmed as shown in FIG. Further, the correlation between the resist stripping performance and each parameter has been confirmed by a lot of data accumulated over the past three years. One example is the data shown in FIG. For example, if the pressure at which the mixed phase fluid is ejected from the nozzle is increased, the resist stripping area is increased and the residue is reduced. However, if the ejection pressure is increased too much, physical damage to the object is concerned, and the superiority of the low pressure process, which is a feature of this apparatus, is impaired. Therefore, in this apparatus, the maximum ejection pressure from the nozzle is 0.3 MPa. This also produces the result that it is not necessary to use special high pressure resistant parts, and it is possible to easily manufacture an inexpensive and safe device. When the type of nozzle and the distance between the nozzle and the object are made constant, the results shown in FIGS. 21, 22, and 23 are obtained. However, as described above, there is no specific unit that expresses the magnitude of the shock wave generated by a droplet that collides at high speed, and it is expressed as a relative value without a unit.

  The conventional technology (for example, Patent Document 1) also employs a configuration that is not greatly different from the best mode in terms of apparatus, except that an ultrahigh-speed nozzle is used. However, in the prior art, no attention has been paid to the physical force called “shock wave” when processing the object, and therefore, no control is performed to generate or not generate the shock wave on the object. Under the conditions of the prior art, “cavitation” occurs only in a nozzle having a tapered tip, and the generated shock wave is extremely short-lived and disappears before reaching the object. Specifically, when the multiphase fluid flowing in the nozzle reaches the tip of the nozzle, the flow velocity is increased. As a result of the reduced pressure due to the increased flow velocity, the liquid causes a cavitation phenomenon and a shock wave is generated. According to “Cavitation” by Yoji Kato, published by Tsuji Shoten, the collapse duration of hydrogen bubbles in a liquid shock wave tube is 2 to 3 μs. The movement time of the fluid having a flow rate of 400 m / sec for 3 μsec is only 1.2 mm, and the bubble collapse phenomenon disappears between the nozzle throat and the nozzle outlet. Further, even if bubble collapse occurs at the nozzle outlet, it is mechanically difficult to set the object distance to 1.2 mm or less. On the other hand, in the present invention, the nozzle mainly functions to accelerate the multiphase fluid or expand the irradiation area. The bubble collapse related parameters related to the occurrence of cavitation may be basically adjusted anywhere as long as the cavitation on the object is focused. For example, any parameter of the fluid piping in front of the nozzle may be adjusted. The fluid mixing section may be used. Specifically, it may be controlled anywhere within the range of the arrow indicated by α in FIG. 1 (between the steam generator and the nozzle outlet). Later, the main bubble collapse related parameters will be described in detail.

Aluminum Corrosion Prevention The object cleaning method according to the best mode of the present invention has an aluminum corrosion prevention effect together with the impact force described above. Again, by adjusting the gas temperature, the temperature of the water to be mixed, the nozzle shape, the distance from the nozzle outlet to the object, the temperature of the object, the relative movement time between the nozzle and the object, the corrosion prevention effect can be achieved. It is possible to control. Among these related parameters, in particular, the temperature when the mixed phase fluid reaches the object and the pH when the mixed phase fluid reaches the object are important. By controlling these parameters, it is possible to form a special protective film having a corrosion prevention effect on the aluminum surface. Hereinafter, parameters related to aluminum corrosion prevention will be described in detail along with main bubble collapse related parameters.

(A) Fluid temperature The shock wave is considered to be mainly generated by the cavitation generated when the droplet collides with the surface of the object to be processed and the collapse of the cavitation. Cavitation is a cavity generated when a low pressure portion is generated in a part of a liquid such as water, and tends to be generated more easily as the temperature of the gas and the liquid is higher. That is, the higher the temperature of the droplet, the easier it is to generate bubbles in the water droplet, and along with this, more bubble collapse occurs on the surface of the object to be processed, which is the basis of a large energy shock wave. When the processing method is used for removing the resist film, it is possible to remove the resist film and foreign matters that are relatively strongly bonded. On the other hand, if the temperature of the multiphase fluid or water droplets is set low, the generation of shock waves on the surface of the object to be treated can be suppressed and the object having a relatively low strength can be cleaned. However, there is a limit to the temperature that can be set due to the limitation due to the heat resistance of the object. In addition, when the distance from the object is increased in a state where the temperature is too high, it is expected that the gas component in the droplets is lost and it is difficult to generate bubble nuclei. It can be ignored at a distance of about 30 mm. In addition, 50-120 degreeC is suitable for the temperature of the water vapor | steam supplied in a nozzle, 80-115 degreeC is more suitable, and 90-110 degreeC is still more suitable. Moreover, 0-40 degreeC is suitable for the temperature of the water mixed with respect to the said water vapor | steam, 10-35 degreeC is more suitable, and 20-30 degreeC is still more suitable.

  Here, in particular, the temperature at which the mixed phase fluid reaches the object is preferably 50 ° C. or higher, more preferably 80 ° C. or higher, and further preferably 90 ° C. or higher. The temperature of the mixed phase fluid is measured by the method described in the examples. By setting it as the said range, the special film | membrane which has a corrosion prevention effect is formed in the aluminum on the target object surface.

(B) Droplet speed The higher the drop speed, the greater the impact when the drop collides with the surface of the object to be processed, so that an internal pressure difference is likely to occur, resulting in bubble collapse. Cavitation is likely to occur. That is, if the droplet velocity is set to a high value, a large energy shock wave is generated on the surface of the object to be processed. For example, when the processing method is used for removing the resist film, the adhesion is relatively strong. The resist film and foreign matters that are present can be removed. On the other hand, if the droplet velocity is set to be low, the generation of shock waves on the surface of the object to be treated can be suppressed, and the object having a relatively low strength can be cleaned. In addition, by increasing the speed of the droplets, the multiphase fluid is exposed to the air for a shorter time, so it is less likely to take in carbon dioxide in the atmosphere and is less likely to be acidic, and thus more effectively exhibits a corrosion prevention effect. . The velocity of the droplet is 100 to 600 m / s, more preferably 200 to 500 m / s, and further preferably 250 to 350 m / s. By setting the fluid velocity in this range, an impact force due to cavitation can be obtained. Note that the velocity of the droplet is substantially equal to the velocity of the fluid, and is [flow rate] / [nozzle cross-sectional area]. Here, the flow rate is the water vapor flow rate (m ³ / s), and the nozzle sectional area is the sectional area (m ² ) of the nozzle outlet.

(C) Other parameters First, as for the nozzle, an ultra-high speed nozzle is used as described above. By using this nozzle, the flow velocity of the fluid changes and the magnitude of the shock wave also changes. As a general rule, using a nozzle with a large flow velocity makes it easier to obtain shock waves. Further, by irradiating a multiphase fluid containing water vapor and water droplets using an ultra-high speed nozzle, a special behavior is observed in relation to the pressure of the water vapor and the speed and diameter of the water droplets. The water vapor pressure is not particularly limited as long as it is 0.05 to 0.25 MPa. In particular, under the condition where the water vapor pressure is 0.15 MPa or more, the mixed phase fluid of water vapor and water droplets is significantly different from the mixed phase fluid of air and water droplets. Indicates. Next, regarding the distance from the nozzle outlet to the object, the normal adaptive value is in the range of 2 to 30 mm (optimum range of 2 to 10 mm), preferably 5 mm or less, more preferably 3 mm or less, and 2 mm. Is more preferred. If the distance from the nozzle outlet to the wafer is shortened, the resist stripping performance is improved in the same manner. However, if the optimum distance exists and is too close, the stripping performance is lowered. On the other hand, if you want to suppress the peeling performance and cleaning performance, keep away from the optimum distance. In addition, the closer the distance from the nozzle outlet to the object, the less likely it is to capture carbon dioxide in the atmosphere and the less likely it is to be acidic.

In addition, when obtaining a particularly high impact force, it is important that the periphery is covered with water vapor when the droplet collides with the object. Here, the flow rate of water vapor is preferably 0.083 to 1.0 kg / min, more preferably 0.025 to 0.75 kg / min in terms of the mass flow rate of water vapor, and 0.33 to 0.50 kg / min. min is more preferable. The gas / liquid mixing ratio (liquid / gas) is preferably 0.00018 to 0.01. The droplet diameter is preferably 2 to 25 μm. The larger the droplet diameter, the smaller the surface area. Therefore, the amount of carbon dioxide in the atmosphere is reduced, so that the droplet diameter is less likely to be acidic. The droplet diameter is measured at a position 5 mm from the nozzle outlet by a PDA (Phase Doppler Anemometry) unless otherwise specified, using a device manufactured by TSI. 0.5-32.0 kgcm ^<-2 > min ^{< -1} > is suitable for fluid flow volume / jet outlet cross-sectional area.

  The pH when the mixed phase fluid reaches the object is preferably 7.0 to 9.0, more preferably 7.0 to 8.0, and even more preferably 7.0 to 7.5. By setting the pH within this range, a special film is formed on aluminum on the surface of the object, so that an effect of preventing corrosion of aluminum is obtained. In addition, the pH measuring method shall be based on the method as described in an Example.

Method of measuring the temperature at the time the object reaches the multiphase fluid Figure 31 is a schematic diagram of a device for performing temperature measurement in the object reach the multiphase fluid. A thermocouple TH (Alumel-Chromel thermocouple JIS C1602) is affixed to a silicon wafer W having a diameter of 6 inches and a thickness of 0.625 mm with a tape TA, and the distance between the fluid ejection outlet of the nozzle 141 and the object, water vapor Set the various conditions such as pressure and pure water flow rate to the same values as when processing the object, irradiate the thermocouple for 1 minute, and change the temperature when it reaches the steady state to the temperature when the object of the multiphase fluid reaches the object. And

Method of measuring pH during the object reaches the multiphase fluid Figure 32 is a schematic view of an apparatus for measuring the pH at the time of the object reaches the multiphase fluid. The outlet of the nozzle 141 is connected to a cooling pipe C (for example, a Graham-type pipe cooling pipe) via a pipe P, and the condensed water is collected in a container R, and the pH of the water is adjusted according to the method of JIS Z 8802. It was measured by. The aggregating operation is performed without touching the air.

Example 1
Under the following conditions, the aluminum surface was irradiated with a multiphase fluid (when steam was used as a gas and when air was used) for 10 minutes. AFM photographs before and after the treatment are shown in FIG. FIG. 5 shows surface roughness data. In this example, the surface roughness was measured by the profile analysis method attached to AFM.
Steam pressure: 0.2 MPa
Steam temperature: 130 ° C
Flow rate of pure water: 300cc / min
Pure water temperature: 20 ° C
GAP: 5mm
Nozzle scan: Fixed

Example 2
Under the same conditions as in Example 1, the steel surface was irradiated with a mixed phase fluid (when steam was used as a gas and when air was used) for 10 minutes. AFM photographs before and after the treatment are shown in FIG. FIG. 6 shows surface roughness data.

Example 3
Since the vapor cleaning technique disclosed in Patent Document 1 is to remove the resist by the chemical reaction of the vapor and the mechanical action of the jet, it takes a minute time to remove the resist. Visualization using high-speed video was performed to confirm whether this method is the same mechanism. FIG. 7 shows the change over time when the i-line positive resist is peeled off, as observed in the lower part of the quartz wafer, irradiated with the multiphase fluid under the same conditions as in Example 1 except that the nozzle scan speed is 100 mm / sec. Show. As shown in the figure, the resist was peeled off at a very high speed while the peeled area gradually expanded.

Example 4
Except that the nozzle scan speed was set to 40 mm / sec, the silicon wafer after the high concentration ion implantation was irradiated with the mixed phase fluid under the same conditions as in Example 1, and the change with time of i-line positive resist peeling was observed. The results are shown in FIG.

Examples 5-8
Under the following conditions, the gas and temperature of the mixed phase fluid were changed, and the aluminum surface was irradiated with the mixed phase fluid for 10 minutes. AFM photographs before and after the treatment are shown in FIG. FIG. 10 shows surface roughness data. The surface of the aluminum to be treated before irradiation had an Ra of 34.9 nm.
Gas pressure: 0.2MPa
Liquid flow rate: 300cc / min
Gap: 10mm

  As a result of irradiating the mixed phase fluid consisting of low temperature air (20 ° C.) and low temperature pure water droplets (20 ° C.), a surface with Ra of 30.5 nm was obtained. A surface AFM photograph is shown in FIG. 9A, and surface roughness data is shown in FIG. 10A (Example 5). Next, as a result of irradiating a multiphase fluid consisting of high-temperature air (130 ° C.) and low-temperature pure water droplets (20 ° C.), a surface with an Ra of 96.4 nm was obtained. The AFM photograph of the surface is shown in FIG. 9B, and the surface roughness data is shown in FIG. 10B (Example 6). Next, as a result of irradiating a mixed phase fluid composed of high-temperature air (130 ° C.) and high-temperature pure water droplets (60 ° C.), a surface having an Ra of 86.3 nm was obtained. The surface AFM photograph is shown in FIG. 9C, and the surface roughness data is shown in FIG. 10C (Example 7). Although the surface roughness of (c) is slightly smaller than that of (b), the density of the roughened portion is larger than that of (b), so that (c) is more affected by shock waves than (b). . Next, as a result of irradiating a multiphase fluid consisting of water vapor and low-temperature pure water droplets (20 ° C.), a surface with Ra of 257 nm was obtained. A surface AFM photograph is shown in FIG. 9D, and surface roughness data are shown in FIG. 10D (Example 8). From the above results, it has been clarified that the shock wave increases as the temperature rises. In particular, when water vapor is used as the gas, the largest shock wave is applied to the surface to be treated.

Examples 9-10
The surface of the Al alumite with Ra of 348.8 nm was irradiated under the same conditions as in Examples 5 to 8 while changing the gas and temperature of the mixed phase fluid. As a result of irradiating a mixed phase fluid composed of 20 ° C. air and 20 ° C. pure water droplets, a surface with Ra of 380 nm was obtained. A surface AFM photograph is shown in FIG. 11 (a), and surface roughness data is shown in FIG. 11 (c) (Example 9). Next, as a result of irradiating a mixed phase fluid composed of 130 ° C. water vapor and 20 ° C. pure water droplets, a surface with an Ra of 440 nm was obtained. A surface AFM photograph is shown in FIG. 11B, and surface roughness data is shown in FIG. 11D (Example 10).

Example 11
An SUS surface with an Ra of 8.1 nm was irradiated under the same conditions as in Examples 5 to 8 while changing the gas and temperature of the multiphase fluid. As a result of irradiating a multiphase fluid consisting of 130 ° C. water vapor and 20 ° C. pure water droplets, a surface with an Ra of 19.9 nm was obtained. The AFM photograph of the surface is shown in FIG. 12 (a), and the surface roughness data is shown in FIG. 12 (b) (Example 11).

Example 12
The titanium surface with Ra of 75.5 nm was irradiated under the same conditions as in Examples 5 to 8 while changing the gas and temperature of the multiphase fluid. As a result of irradiating a mixed phase fluid consisting of 130 ° C. water vapor and 20 ° C. pure water droplets, a surface with an Ra of 98 nm could be obtained. A surface AFM photograph is shown in FIG. 13A, and surface roughness data is shown in FIG. 13B (Example 12). In titanium, interference fringes were visually observed. There is a possibility that an oxide film is formed on the surface.

Example 13
The silicon surface with Ra of 1.9 nm was irradiated under the same conditions as in Examples 5 to 8 while changing the gas and temperature of the mixed phase fluid. As a result of irradiating a mixed phase fluid consisting of 130 ° C. water vapor and 20 ° C. pure water droplets, a surface with Ra of 7.6 nm could be obtained. The AFM photograph of the surface is shown in FIG. 14A, and the data of the surface roughness is shown in FIG. 14B (Example 13).

Examples 14-25
In Examples 14 to 25, it was examined whether there was a difference in the state of peeling depending on the resist coating conditions. The presence or absence of HMDS and the Bake temperature were changed to 90 ° C. and 110 ° C., and the influence of the condition change was observed. The result is considered that the surface profile after the treatment does not depend on the ground treatment HMDS. The experiment was performed under the following conditions.
Sample used: I-line resist Irradiation time: Until peeling is visually observed Gas pressure: 0.2 MPa
Liquid flow rate: 300cc / min
Nozzle scan: Fixed Gap: 10 mm

  15A to 15C and FIGS. 15A to 15C show the state where the treatment peeling boundary surface was observed with a microscope after applying a resist film under the conditions of baked 90 ° C. without HMDS and irradiating the sample under the above conditions. The observed state is shown in FIGS. FIG. 15A shows a state in which the surface was observed with a microscope after irradiation with a mixed phase fluid composed of 20 ° C. air and 20 ° C. pure water, and FIG. 15D is a corresponding AFM photograph ( Example 14). FIG. 15 (b) shows a state where the surface was observed with a microscope after irradiating a mixed phase fluid composed of 130 ° C. air and 90 ° C. pure water, and FIG. 15 (e) is a corresponding AFM photograph ( Example 15). FIG.15 (c) is a state which observed the surface with the microscope after irradiating the mixed phase fluid which consists of 130 degreeC water vapor | steam and 20 degreeC pure water, FIG.15 (f) is a corresponding AFM photograph ( Example 16).

  After applying a resist film under the conditions of HMDS-free and Bake 110 ° C. and irradiating the sample under the above-mentioned conditions, the state where the treatment peeling boundary surface was observed with a microscope is shown in FIGS. The observed state is shown in FIGS. FIG. 16A shows a state in which the surface was observed with a microscope after irradiation with a multiphase fluid composed of 20 ° C. air and 20 ° C. pure water, and FIG. 16D is a corresponding AFM photograph ( Example 17). FIG. 16 (b) shows a state in which the surface was observed with a microscope after irradiation with a multiphase fluid composed of 130 ° C. air and 90 ° C. pure water, and FIG. 16 (e) is a corresponding AFM photograph ( Example 18). FIG. 16 (c) shows a state in which the surface was observed with a microscope after irradiation with a mixed phase fluid composed of 130 ° C. water vapor and 20 ° C. pure water, and FIG. 16 (f) is a corresponding AFM photograph ( Example 19).

  After applying a resist film under the condition of HMDS and Bake at 90 ° C., and irradiating the sample under the above conditions, the state where the treatment peeling boundary surface was observed with a microscope is shown in FIGS. The observed state is shown in FIGS. FIG. 17A shows a state in which the surface was observed with a microscope after irradiation with a multiphase fluid composed of 20 ° C. air and 20 ° C. pure water, and FIG. 17D is a corresponding AFM photograph ( Example 20). FIG. 17 (b) shows a state in which the surface was observed with a microscope after irradiation with a multiphase fluid composed of 130 ° C. air and 90 ° C. pure water, and FIG. 17 (e) is a corresponding AFM photograph ( Example 21). FIG. 17 (c) shows a state in which the surface was observed with a microscope after irradiation with a mixed phase fluid consisting of 130 ° C. water vapor and 20 ° C. pure water, and FIG. 17 (f) is a corresponding AFM photograph ( Example 22).

  After applying a resist film under the conditions of HMDS and Bake 110 ° C. and irradiating the sample under the above conditions, the processing peeling boundary surface was observed with a microscope in FIGS. The observed state is shown in FIGS. FIG. 18 (a) shows a state in which the surface was observed with a microscope after irradiation with a mixed phase fluid composed of 20 ° C. air and 20 ° C. pure water, and FIG. 18 (d) is a corresponding AFM photograph ( Example 23). FIG. 18 (b) shows a state in which the surface was observed with a microscope after irradiation with a multiphase fluid composed of 130 ° C. air and 90 ° C. pure water, and FIG. 18 (e) is a corresponding AFM photograph ( Example 24). FIG. 18 (c) shows a state of observing the surface with a microscope after irradiating a mixed phase fluid composed of 130 ° C. water vapor and 20 ° C. pure water, and FIG. 18 (f) is a corresponding AFM photograph ( Example 25).

Example 26
The relationship between droplet diameter and flow velocity is shown in FIG. The water vapor pressure was constant (0.2 MPa), and the flow rate and diameter of the droplets were measured at various pure water flow rates. The results are shown in FIG. The relationship between droplet velocity v and diameter d measured by PDA is shown. Both v and d were close to a normal distribution, and the averages were about 280 m / s and 10 μm, respectively.

Example 27
FIG. 20 shows the results when the vapor pressure p and the distance h from the nozzle are used as parameters for v and d when the pure water flow rate q = 100 mL / min. For comparison, the result of the mixed jet of air and droplets is also indicated by a dotted line. It can be seen from the figure that the target droplet velocity is about 200 to 300 m / s and the droplet diameter is about 10 μm.

Example 28 (Relationship between gas pressure and droplet velocity)
Using a sonic nozzle with a mixed phase fluid of water vapor and water and a mixed fluid of air and water at a flow rate of water of 200 cc / min and a gas pressure of 0.05, 0.1, 0.2 MPa. The liquid droplets were jetted, and the velocity of the liquid droplets was measured at a position 5 mm or 10 mm from the jet nozzle with an LDA (Laser Doppler Anemometer) (FIG. 33). The measurement of LDA was performed with an LDA manufactured by TSI, and when data of 10,000 droplets could be acquired, the measurement was terminated, and measurement was performed three times under each condition. When a mixed phase fluid of water vapor and water was used, it was observed that the droplet velocity was higher at the 10 mm position than at the 5 mm position. In the case of a mixed phase fluid of air and water, there was a tendency that the higher the air pressure, the higher the droplet velocity. On the other hand, in the case of water vapor and water, the cause is unknown, but if the pressure of the water vapor is increased, it was observed that the speed of the droplet increased to a predetermined value, but at 0.2 MPa, according to the measured value Droplet velocity was lowered. However, it is speculated that this is an error. Under other conditions, the measurement did not take 10 seconds, but the measurement took several minutes only under the condition of a mixed phase fluid of water vapor and water and a water vapor pressure of 0.2 MPa. Therefore, it can be presumed that almost no noise was observed under these conditions.

Example 29 (Relationship between gas pressure and droplet diameter)
Using a sonic nozzle with a mixed phase fluid of water vapor and water and a mixed fluid of air and water at a flow rate of water of 200 cc / min and a gas pressure of 0.05, 0.1, 0.2 MPa. The droplet diameter was measured with a PDA at positions 5 and 10 mm from the ejection port (FIG. 34). In addition, the measurement of PDA was completed when data of 10,000 droplets could be acquired, and measurement was performed three times under each condition. In the case of a mixed phase fluid of air and water, the droplet velocity hardly changed even when the air pressure was changed. On the other hand, in the case of water vapor and water, the cause is unknown, but if the water vapor pressure is increased, there is almost no change in the diameter of the droplet up to a predetermined value, but at 0.2 MPa, the diameter of the droplet is small. A phenomenon of sudden reduction was observed. However, it is speculated that this is an error. Under other conditions, the measurement did not take 10 seconds, but the measurement took several minutes only under the condition of a mixed phase fluid of water vapor and water and a water vapor pressure of 0.2 MPa. Therefore, it can be presumed that almost no noise was observed under these conditions.

Example 30 (pressure wave in the nozzle)
Under the conditions of a water vapor pressure of 0.1 and 0.2 MPa, a pure water flow rate was set to 100 cc / min, and a mixed phase fluid of water vapor and water was injected using a quartz nozzle. A pressure wave was observed at the tip of the quartz nozzle. This is shown in FIG. FIG. 35 (a) shows the state of injection under the condition of 0.1 MPa, and FIG. 35 (b) shows the state of injection under the condition of 0.2 MPa. For comparison, a mixed phase fluid of air and water was irradiated using a quartz nozzle under a gas pressure of 0.1 and 0.2 MPa with a pure water flow rate of 100 cc / min. However, no pressure wave was observed at the tip of the quartz nozzle. This situation is shown in FIG. FIG. 36A shows the state of injection under the condition of 0.1 MPa, and FIG. 36B shows the state of injection under the condition of 0.2 MPa.

Examples 1-36
Using a cleaning device having a sonic nozzle according to the best mode, a mixed phase fluid of water vapor and water was sprayed onto an object under the following conditions to evaluate its cleaning effect, physical breakdown, and corrosion resistance of wiring. (Tables 1 and 2). As an object, an i-line negative resist (Tokyo Ohka THMRip3300) was applied at a thickness of 1 μm, baked at 90 ° C. for 120 min, exposed at 365 nm for 20 seconds, and TMAH ([N (CH ₃ ) ₄ at room temperature. ] A silicon wafer having aluminum wiring developed by ⁺ OH ⁻ ) was used.

Comparative Example Comparative Example 1 is when the fluid temperature is too low. If the fluid temperature was too low, the polymer was removed, but the wiring was eroded after 10 days.
Comparative Examples 2 and 3 are cases where the droplet velocity is too slow and too fast. If it was too slow, the polymer remained, and if it was too fast, physical destruction of the wiring was observed.
Comparative Examples 4 and 5 are cases where the pH is too low and too high. When the pH was too low, a protective film was not formed, and corrosion of the wiring was observed after 10 days. When the pH is too high, wiring corrosion occurs due to the high pH.

  The present invention can be applied to various processes over a very wide range of objects from materials having high strength to materials having low strength. For example, semiconductor devices, liquid crystals, magnetic heads, disks, printed circuit boards, lenses for cameras, precision-machined parts, molded resin products, etc., waste removal, cleaning, polishing, etc., and micro processing using silicon process technology The present invention can also be used for deburring processing in the fields of structures, mold processing, and the like. Furthermore, the present invention is particularly suitable for the treatment of materials that dislike chemicals.

FIG. 1 is a diagram showing an overall configuration of a processing apparatus according to the best mode. FIG. 2 is a schematic view of a mixed phase fluid gas-liquid mixing unit with a temperature control mechanism of the processing apparatus according to the best mode. FIG. 3 is a diagram showing a surface observation AFM photograph 10 minutes after irradiation of the multiphase fluid on the aluminum surface in Example 1. FIG. 4 is a diagram showing a surface observation AFM photograph 10 minutes after irradiation of the multiphase fluid on the steel surface in Example 2. FIG. 5 is a diagram showing surface roughness data in Example 1 after 10 minutes of irradiation of the multiphase fluid on the aluminum surface. FIG. 6 is a diagram showing surface roughness data after 10 minutes of irradiation of the multiphase fluid on the steel surface in Example 2. FIG. 7 is a diagram illustrating a result of observing a resist peeling process from the back surface with a high-speed camera while irradiating a resist coated on a transparent wafer with a mixed phase fluid in Example 3. FIG. 8 is a diagram showing resist stripping data by multiphase fluid irradiation after high-concentration ion implantation in Example 4. FIG. 9 is a diagram showing the results of Examples 5-8. FIG. 10 is a diagram showing the results of Examples 5-8. FIG. 11 is a diagram showing the results of Examples 9-10. FIG. 12 is a diagram showing the results of Example 11. In FIG. FIG. 13 is a diagram showing the results of Example 12. FIG. 14 is a diagram showing the results of Example 13. FIG. 15 is a diagram illustrating the results of Examples 14 to 16. FIG. 16 is a diagram showing the results of Examples 17-19. FIG. 17 shows the results of Examples 20-22. FIG. 18 is a diagram showing the results of Examples 23-25. FIG. 19 is a diagram showing the results of Example 26. In FIG. FIG. 20 shows the results of Example 27. In FIG. FIG. 21 is a diagram showing a change in the magnitude of the shock wave due to the difference in thermal energy of the multiphase fluid. FIG. 22 is a diagram showing a change in the magnitude of the shock wave due to the difference in velocity of the multiphase fluid. FIG. 23 is a diagram showing a change in the magnitude of the shock wave due to the difference in density of the multiphase fluid. FIG. 24 is a diagram showing a mechanism of cavitation generation by ultrasonic waves. FIG. 25 is a diagram showing a mechanism of cavitation that occurs at the time of droplet collision. FIG. 26 is a diagram showing a mechanism of cavitation that occurs at the time of droplet collision. FIG. 27 is a diagram showing a mechanism of cavitation that occurs at the time of droplet collision. FIG. 28 is a diagram showing a mechanism of cavitation that occurs at the time of droplet collision. FIG. 29 is a diagram showing a mechanism of cavitation that occurs at the time of droplet collision. FIG. 30 is a view showing the structure of a sonic nozzle. FIG. 31 is a schematic view of an apparatus for measuring a multiphase fluid temperature. FIG. 32 is a schematic view of an apparatus for measuring the pH of a multiphase fluid. FIG. 33 is a diagram showing the relationship between the gas pressure and the water droplet velocity. FIG. 34 is a diagram showing the relationship between gas pressure and water droplet diameter. FIG. 35 is a diagram illustrating a state of a pressure wave generated in the quartz nozzle. FIG. 36 is a diagram illustrating a state in which no pressure wave is generated in the quartz nozzle.

Explanation of symbols

100: Object processing apparatus 111: Water supply pipe 112: Steam generator 113: Steam opening / closing valve 114: Pressure gauge 115: Steam pressure adjusting valve 116: Heated steam generator with temperature control mechanism / saturated steam wetness adjuster 117: Pressure release valve 121: Water supply pipe 122: Pure water temperature control mechanism additional heat section 123: Pure water on / off valve 124: Pure water flow meter 125: Pure water on / off valve 131 for two fluid generation 131: Steam fluid temperature control mechanism additional heat section 141: Irradiation nozzle 142: Flexible pipe 143: Pressure gauge 144: Mixed phase fluid / gas / liquid mixing section 145 with temperature control function 145: Orifice 151: Mountable / holdable stage 152: Rotating motor 153: Wafer vertical drive mechanism 154: Cooling water pipe 155 : Cooling water on-off valve 156: Cooling water flow rate adjustment valve 157: Cooling water flow meter

Claims (4)

In a method for cleaning an object, the method comprising irradiating a mixed phase fluid containing continuous phase water vapor and dispersed phase water droplets, which is generated by mixing water vapor and water.
The irradiation is performed using an ultra-high speed nozzle, the speed of the water droplet is in the range of 100 to 600 m / s, the temperature when the mixed phase fluid reaches the target is 50 ° C. or more, and the mixed phase fluid reaches the target The pH of this is the range of 7-9.   Furthermore, the method of Claim 1 that the distance of the said multiphase fluid ejection outlet and a target object is 30 mm or less.   The method according to claim 1 or 2, wherein the object is a semiconductor substrate having an aluminum material such as an aluminum wiring on its surface. In a system for cleaning an object by irradiating a mixed phase fluid containing water vapor and water droplets, having a water vapor supply means for supplying water vapor and a water supply means for supplying liquid water,
A system comprising an ultra-high speed nozzle for performing the irradiation.

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