Abstract:
The present invention relates to a washing apparatus with bubbling reaction and a washing method of using bubbling reaction which are based on compression technology of an interface diffusion layer with bubbling, by the aid of using a bubble wall generated by a pneumatic means as a reaction interface in a gas-liquid-solid heterogeneous system and utilizing a pulling force generated by bubbles when climbing up along the surface of a material to be washed, to compress thickness of the liquid-solid interface and optimize mass transfer efficiency in multiphase that can remove organic matter from the material surface.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a washing apparatus which is used to remove organic matter from a specific material. Particularly, the present invention directs to a washing apparatus with bubbling reaction through ozone and a washing method of using such reaction.  
       BACKGROUND OF THE INVENTION  
       [0002]     Heterogeneous reaction systems widely exist in various industries, for instance, catalytic reaction systems and long-film processes for high level electronic components. To raise heterogeneous mass transfer efficiency in multiphase is important to develop technology related process. In a heterogeneous reaction system in which gas-liquid-solid phases coexist, because the reaction needs to be conducted through interfaces of the both gas-liquid and liquid-solid phases, the thickness of an interface diffusion layer and the replacing frequency in the reaction interface become a critical bottleneck to affect the reaction rate.  
         [0003]     Conventional technology commonly uses certain of manipulations such as a mechanical stirring, an ultrasonic wave, or an ultrasonic vibration to compress the thickness of the interface and increase the mass transfer efficiency. However, in a heterogeneous reaction system that a liquid phase exists in a large proportion and a gas phase belongs to a hardly-soluble gas, a critical step affecting the reaction rate mainly depends on the mass transfer rate between gas-liquid interfaces. The mechanical stirring cannot effectively compress the interface, and thus a restricted effect on the mass transfer diffusion can be accomplished. Recently, there is also a new research that utilizes a centrifugal force generated by high-speed rotation to centrifugally remove a water layer from a surface of a solid which can compress the thickness of water film and replace a contact interface. Nevertheless, this method has restrictions on the shape, size and dimension of a material to be treated because it needs to consume a larger electrical energy, and in addition, the high-speed rotation operating for a long time may cause a concern about generating pollution of micro-particles.  
         [0004]     At present, a method for controlling the interface diffusion layer in the heterogeneous system has not been published in the international research yet. Regarding a photoresist washed by aqueous ozone and its related equipment, the prior art describes the following technology. 
        1. A part of a substrate is directly soaked in a solution while gaseous ozone is introduced. The aqua solution brought by rotating the substrate can form a thin film on the surface of the substrate and then remove a photoresist.     2. The interface between heterogeneous phases is compressed by spraying aqueous ozone and rotating a substrate in high speed.     3. In addition to aqueous ozone, other solutions such as de-ionized water (DI-water), sulfuric acid, hydrochloric acid, aqueous ammonia, and so on are used which simultaneously mix with ozone in conjunction with an ultrasonic vibration.     4. Ozone vapor formed by an aqueous solution at a high temperature is used to remove the photoresist.     5. A substrate is heated by ultraviolet (UV) ray in conjunction with ozone to conduct a dry cleaning.        
 
         [0010]     These methods all needs to be conducted under conditions of a high-speed rotation, a high-temperature heating, an ultraviolet (UV) ray, or some additional oxidants, chemical solutions, etc. Especially, the operation of high-speed rotation has high restrictions on its applications because it has a great concern for a nanometer process. Specifically, the operation of high-speed rotation has strict requirements for size, shape, and symmetry of placement of a material to be treated and may generate pollution of micro-particles.  
         [0011]     How to effectively use an ozone gas-liquid system for washing is a valuable technology worthy to think over.  
         [0012]     According to the currently known technology, using sulfuric acid for washing is the oftenest used means which, however, has flaws in high-temperature (120° C.) process, a large amount of water consumption and discharging waste acid, and hard to treat a material containing a metal layer. In other words, the means deeply consumes resources and is not environmental protection.  
       SUMMARY OF THE INVENTION  
       [0013]     The main objective of the present invention is to provide a washing apparatus with bubbling reaction and a washing method of using bubbling reaction that resolve the restrictions on the current technology. The present invention utilizes a concept of compression technology of an interface diffusion layer with bubbling which is applied to design a washing process of a reaction tank removing organic matter. Under operational conditions of saving water and energy without rotating the substrate in high-speed, the present invention can efficiently remove the organic matter from a substrate surface.  
         [0014]     To accomplish the above objective, the present invention provides a washing apparatus with bubbling reaction and a washing method of using bubbling reaction, wherein the washing apparatus with bubbling reaction comprises a reaction tank to contain washing solution and simultaneously is installed with other working units for generating bubbles in the washing solution and for controlling the temperature of the washing solution and controlling the means of rotating a substrate during washing. Since the present invention can be manipulated under conditions of saving water and energy without rotating the substrate in high-speed, it can be carried out at ambient temperature and pressure without a concern about generating pollution of micro-particles and is highly flexible to the size of a material to be treated.  
         [0015]     Moreover, the present invention can apply to remove a lithography photoresist in various industries such as semiconductor, thin film transistor-liquid crystal display (TFT-LCD), micro/nanometer precision machined mold and so on, as well as to a process of washing a surface of the other material. In the future, the present invention can also apply to disinfect medical equipments or wash a surface of nanometer material during its production. 
     
    
     BRIEF DESCRIPTION OF FIGURES  
       [0016]     To further illustrate the above objectives, structural characteristics and functions of the present invention, detailed descriptions are disclosed as follows by reference to accompanying drawings, in which  
         [0017]      FIG. 1  shows a structure of a washing apparatus with bubbling reaction according to one embodiment of the present invention.  
         [0018]      FIG. 2A and 2B  is a flow chart illustrating washing method of using bubbling reaction according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]     The present invention discloses a washing apparatus with bubbling reaction which uses a bubbling reaction to remove organic matter from the surface of a substrate. First, please refer to  FIG. 1  which shows a structure of a washing apparatus with bubbling reaction according to one embodiment of the present invention.  
         [0020]     The washing apparatus with bubbling reaction of the present invention comprises a reaction tank  10 , a motion unit  20 , a temperature-control system  30 , a source  40  for supplying reaction liquid, a source  50  for supplying reaction gas, a pressure-control system  60 , a bubble-generating means  70 , and a source  80  for supplying washing solution. The reaction tank  10  is used to place a substrate  90  and provide a space for washing the substrate  90 . The substrate  90  is placed on the motion unit  20 , which lets the substrate  90  generate rotational displacement in the reaction tank  10  during washing. The source  50  for supplying reaction gas is used to supply the reaction tank  10  with the reaction gas, and the source  40  for supplying reaction liquid is used to supply the reaction liquid to the temperature-control system  30 . After receiving the reaction liquid, the temperature-control system  30  controls the temperature of the reaction liquid and then supplies the reaction liquid at an appropriate temperature to the reaction tank  10 .  
         [0021]     The reaction liquid forms a horizontal plane in the reaction tank  10  and completely covers the bubble-generating means  70 . The bubble-generating means  70  can be a pipe made from material capable against the erosion of ozone, on the pipe at least one exhaust outlet is installed to exhaust the gas or the means  70  can be made from a gas distributor disc. After receiving the reaction gas, the bubble-generating means  70  supplies the gas to the reaction liquid to generate bubbles  71 . The pressure-control system  60  also connects with the reaction tank  10  and is used to control the pressure in the reaction tank  10  and, after the reaction is completed, extract the surplus reaction gas from the reaction tank  10 . The washing procedure can then be carried out after the organic matter is successfully removed from the substrate  90 . At this moment, a source  80  for supplying washing solution can provide the washing solution to wash the substrate  90 . The washing procedure can be finished in the reaction tank  10  or accomplished in another washing tank by transferring the substrate  90  to another tank.  
         [0022]     In order to attain a good effect on removal, the foregoing reaction gas can use ozone or a mixed gas containing ozone. The ozone can be generated by a high-voltage electric field or ultraviolet (UV) irradiation. When the reaction gas enters into the reaction tank  10 , the concentration of the reaction gas is preferably 1% to 17%. The reaction liquid  81  can be selected from de-ionized water (DI-water), aqueous ozone, or an aqueous solution having an appropriate pH adjusted by HCl, H 2 SO 4 , NH 4 OH, and so on with a temperature of from room temperature to 80° C. The generated bubbles  71  may climb up along the substrate  90  which has already been fastened on the motion unit  20  by the fixed means  2   1 . The motion unit  20  can generate rotational motion with the rotational rate ranging from 1 to 10 rpm to rotate the substrate  90 . The motion unit  20  can be designed to rotate itself together with the substrate  90  or only to rotate the substrate  90 .  
         [0023]     Next, please refer to  FIG. 2A  which shows a flow chart (1) illustrating washing method of using bubbling reaction according to the present invention.  
         [0024]     Supposing a semiconductor wafer or a glass substrate is used as the substrate, when the substrate needs to be washed due to a photoresist or any organic contaminant during its production, the substrate is firstly placed into the reaction tank (Step  200 ). Subsequently, the reaction gas is supplied to form bubbles (Step  210 ) where the reaction gas needs to be supplied in appropriate concentration and flow rate and further delivered through the reaction liquid at an appropriate temperature to generate bubbles. The bubbling reaction is carried out afterward to remove the organic matter from the substrate (Step  220 ). At this moment, the bubbles may climb up along a surface of the substrate and remove the organic matter from the surface of the substrate. This procedure can be done by either a continuous reaction (Step  230 ) or a batch reaction (Step  240 ). After the reaction is completed, the remaining reaction gas is extracted and destroyed (Step  250 ). Then, the washing procedure is conducted; namely, the washing solution is used to wash the substrate on which surface the organic matter has been removed (Step  260 ). The washing procedure can be finished in the original reaction tank or accomplished in another washing tank by transferring the substrate to the washing tank. Finally, the completely washed substrate is taken out from the tank (Step  270 ) to finish the whole process. Now please refer to  FIG. 2B  which shows a flow chart (2) illustrating washing steps of using the washing apparatus with bubbling reaction of the present invention.  
         [0025]     In the reaction process of removing the organic matter, part of the substrate needs to be soaked in the reaction liquid. The height of the water level that the substrate soaks in the reaction liquid preferably occupies 5% to 80% of the diameter of the substrate. Meanwhile, the angle between the substrate and the plane of the reaction liquid is preferably in a range of from 5° to 90°. The exhaust outlet of the reaction gas needs to locate below the substrate and the reaction liquid in order to ensure generating the bubbles successfully. When Step  220  carries out, the substrate may further need rotational motion to ensure the effect on removing the organic matter. The rotational motion can set the rotational rate between 1 rpm and 10 rpm. The continuous reaction (Step  230 ) and the batch reaction (Step  240 ) can be optionally selected depending on situations, and the differences between these reactions are as follows. 
        The continuous reaction means that all the conditions are invariable in the whole reaction process, for example, the concentration and the flow rate of the reaction gas, the temperature of the reaction liquid, the water level for soaking the substrate, the rotational rate of the substrate, and the angle between the substrate and the plane of the reaction liquid.     The batch reaction means that the whole bubbling reaction process can be conducted by dividing into several steps, each of which can carry out under a different concentration and a different flow rate of the reaction gas, a different temperature of the reaction liquid, a different rotational rate of the substrate, and a different angle between the substrate and the plane of the reaction liquid.        
 
         [0028]     In the final washing procedure, the washing solution has no special restriction on entering into the reaction tank and can be infused from the top or the bottom. The means of washing can be selected from soaking, showering, or spraying.  
         [0029]     Moreover, the method of the present invention utilizes gaseous ozone to naturally form a bubble wall in liquid as a reaction interface in a gas-liquid-solid heterogeneous system. Without rotating the substrate in a high-speed, the bubbles are generated by a pneumatic means and climb up along a surface of a material to be washed. In a pull process when the bubbles climb up, the liquid-solid interface can be compressed to a minimal thickness and thus mass transfer efficiency in multiphase can be increased that can remove the organic contaminants effectively. The method of the present invention has advantages of saving water and energy, carrying out at ambient temperature and pressure without rotating the substrate in high-speed and without a concern about micro-particle pollution, and being flexible to the size and the type of material to be treated.  
         [0030]     Although the present invention is exemplified by the above preferable embodiment, it does not intend to use to restrict the scope of the present invention. Person skilled in the art can make a certain modification and change without departing from the sprit and scope of the present invention. Therefore, it is necessary to define the scope of the present invention based on the claims described below.