Abstract:
There are provided an apparatus having a heating portion in a chemical bath for substrate wet treatment and a method of heating a chemical for substrate wet treatment using the apparatus. The apparatus includes a chemical bath containing a chemical for substrate wet treatment. A heating portion is installed in the chemical bath, and the heating portion includes a heating element and a housing accommodating the heating element. An inert gas is filled in the housing.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2006-0009808, filed on Feb. 1, 2006, in the Korean Intellectual Property Office, the contents of which are incorporated herein in their entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an apparatus for substrate wet treatment, and more particularly, to an apparatus having a heating portion in a chemical bath for substrate wet treatment. 
         [0004]    2. Description of the Related Art 
         [0005]    A substrate wet treating apparatus is a device for cleaning or etching a substrate. For this, the substrate wet treating apparatus includes a chemical bath containing a chemical for cleaning or etching the substrate. The chemical can be heated to a predetermined temperature for smooth cleaning or etching. 
         [0006]    The chemical can be heated by an indirect heating method or a direct heating method. In the indirect heating method, the chemical is heated outside the chemical bath and then supplied to the chemical bath. In the direct heating method, the chemical is directly heated in the chemical bath. In the indirect heating method, since heat is dissipated from the chemical while the heated chemical is supplied to the chemical bath, the chemical in the chemical bath cannot have a high temperature. Therefore, the direct heating method is currently in more widespread use. 
         [0007]    However, in the direct heating method, a heating portion is directly installed in the chemical bath. Therefore, the heating portion can be damaged by direct contact with the chemical, causing possible contamination of the chemical and fire. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides an apparatus for wet treatment of a substrate, the apparatus being designed to prevent contamination of a chemical inside a chemical bath and to prevent fire. 
         [0009]    The present invention also provides a method of heating a chemical for wet treatment of a substrate, the method being designed to prevent contamination of a chemical inside a chemical bath and to prevent fire. 
         [0010]    According to an aspect of the present invention, there is provided an apparatus for wet treatment of a substrate, including: a chemical bath containing a chemical for treating the substrate; a heating portion installed in the chemical bath, the heating portion including a heating element and a housing accommodating the heating element; and an inert gas filled in the housing. 
         [0011]    According to the invention, even when the housing is corroded by the chemical and thus a pin hole may be formed through the housing, the chemical cannot enter the housing through the pin hole since the inert gas filled in the housing is discharged through the pin hole in the form of bubbles to prevent inflow of the chemical. As a result, the chemical does not make direct contact with the heating element, so that contamination of the chemical or fire are prevented since the heating element is not corroded by the chemical. 
         [0012]    The apparatus may further include a gas pressure sensor gauging a pressure of the inert gas filled in the housing. The gas pressure sensor may generate an alarm when the gauged pressure is lower than a reference pressure. Therefore, an operator can be immediately notified when a pin hole is formed through the housing, so that necessary actions can be promptly taken. 
         [0013]    The apparatus may further include a control board connected with the gas pressure sensor. The control board may stop operation of the heating element when the gauged pressure by the gas pressure sensor is lower than a reference pressure. 
         [0014]    The apparatus may further include an inert gas supply tube and an inert gas discharge-tube that are connected to the housing. The apparatus may further include a gas pressure sensor connected with the inert gas discharge tube. The gas pressure sensor can generate an alarm when a gauged pressure is lower than a reference pressure. The apparatus can further comprise a control board connected with the gas pressure sensor, the control board stopping operation of the heating element when a gauged pressure by the gas pressure sensor is lower than a reference pressure. The apparatus may further include a gas regulator connected with the inert gas supply tube. The apparatus may further include a mass flow controller (MFC) connected with the inert gas supply tube. 
         [0015]    According to another aspect of the present invention, there is provided a method of heating a chemical for wet treatment of a substrate, the method including: installing a heating portion in a chemical bath containing the chemical, the heating portion including a heating element and a housing accommodating the heating element; and filling the housing with an inert gas. 
         [0016]    According to the invention, even when the housing is corroded by the chemical and thus a pin hole is formed through the housing, the chemical cannot enter the housing through the pin hole since the inert gas filled in the housing is discharged through the pin hole in the form of bubbles to prevent inflow of the chemical. As a result, the chemical does not make direct contact with the heating element, so that contamination of the chemical or a fire can be prevented since the heating element is not corroded by the chemical. 
         [0017]    The method may further include gauging a pressure of the inert gas filled in the housing. The method may further include generating an alarm when the gauged pressure is lower than a reference pressure. Therefore, an operator can be immediately notified when a pin hole is formed through the housing, so that necessary actions can be promptly taken. The method may further include stopping operation of the heating element when the gauged pressure is lower than a reference pressure. 
         [0018]    The filling of the housing may include discharging the inert gas from the housing while supplying the inert gas to the housing. In this case, the method may further include gauging a pressure of the discharging inert gas. The method may further include generating an alarm when the gauged pressure is lower than a reference pressure. The method may further include stopping operation of the heating element when the gauged pressure is lower than a reference pressure. The inert gas supplied to the housing may be kept at a constant pressure and flow rate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The foregoing and other objects, features and advantages of the invention will be apparent from the more particular description of preferred aspects of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
           [0020]      FIG. 1  is a schematic diagram of an apparatus for substrate wet treatment according to an embodiment of the present invention. 
           [0021]      FIG. 2  is a schematic diagram showing a portion of the apparatus depicted in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. 
         [0023]      FIG. 1  is a schematic diagram of an apparatus  100  for substrate wet treatment according to an embodiment of the present invention. 
         [0024]    Referring to  FIG. 1 , the substrate wet treating apparatus  100  includes a chemical bath containing a chemical (C) for treating a substrate. The chemical bath may include an inner chemical bath  101  and an outer chemical bath  102 . The inner chemical bath  101  has an opened top for receiving a substrate (W). The substrate (W) may a substrate for a semiconductor device. The outer chemical bath  102  may enclose the inner chemical bath  101  and include a lid on a top. 
         [0025]    The chemical (C) contained in the inner chemical bath  101  is used for cleaning the substrate (W) or etching a layer formed on the substrate (W). Thus, floating particles may exist in the chemical (C) of the inner chemical bath  101 . The chemical (C) is continuously supplied to the inner chemical bath  101  through a circulation tube  116 . As a result, the chemical (C) inside the inner chemical bath  101  overflows down to the outer chemical bath  102 , together with the floating particles. Then, the chemical (C) is again supplied to the inner chemical bath  101  from the outer chemical bath  102  through the circulation tube  116 . In the circulation tube  116 , the chemical (C) passes through a circulation pump  110  and a circulation filter  112 . The circulation filter  112  removes the floating particles or other foreign substances from the chemical (C) to keep the chemical (C) clean. 
         [0026]    Drain valves  113  may be connected to the circulation tube  116  and the inner chemical bath  101 , respectively. If necessary, the chemical (C) can be discharged to the outside by opening the drain valve  113 . 
         [0027]      FIG. 2  is a schematic diagram showing a portion of the substrate wet etching apparatus  100  depicted in  FIG. 1 . 
         [0028]    Referring to  FIG. 2 , a heating portion is installed in the chemical bath, specifically in the inner chemical bath  101 . The heating portion includes a heating element  155  and a housing  150  accommodating the heating element  155 . The heating element  155  may be a metal coil. The heating element  155  is connected with an electric wire  151 . One end of the electric wire  151  may be connected to a control board  170 . The control board  170  controls power to the electric wire  151 . 
         [0029]    The housing  150  may be formed of quartz or Teflon, and an inert gas is filled in the housing  150 . The housing  150  is in direct contact with the chemical (C). The chemical (C) may be HF, H 3 PO 3 , HCl, HNO 3 , NaCl, H 2 SO 4 , NH 4 OH, or NaOH. Since most of the substances referred to as the chemical (C) are strongly corrosive (strongly acid or alkaline), the housing  150  can be corroded. As a result, a pin hole (P) may be formed through the housing  150 . In this case, the inert gas filled in the housing  150  is discharged to the chemical (C) through pin hole (P), and the discharged inert gas is emitted to the outside through the chemical (C) in the form of bubbles (B). 
         [0030]    Therefore, the chemical (C) can be prevented from entering the housing  150  through the pin hole (P), and thus the heating element  155  can be prevented from making contact with the chemical (C). As a result, the heating element  155  is not corroded by the chemical (C), and thus the inner chemical bath  101  is not contaminated by the corrosion, thereby preventing the substrate (W) from being contaminated. Further, since the heating element  155  is not in contact with the chemical (C), a spark or electric short circuit can be prevented to reduce the possibility of fire. 
         [0031]    Furthermore, since the inert gas is not reactive, the chemical (C) may be not contaminated by the inert gas. The inert gas may be nitrogen. 
         [0032]    To allow the inert gas to be discharged from the housing  150  to the outside through the chemical (C), the pressure of the inter gas inside the housing  150  may be higher than the outside pressure. If the outside pressure is equal to the atmospheric pressure, the pressure of the inert gas may be higher than the atmospheric pressure. 
         [0033]    A gas pressure sensor  165  is installed to gauge the pressure of the inert gas filled in the housing  150 . The gas pressure sensor  165  may generate an alarm when the gauged pressure of the inert gas is lower than a reference pressure. The reference pressure is a pressure of the inert gas filled inside the housing  150  when the pin hole (P) is not formed in the housing  150 . Therefore, when the pin hole (P) is formed in the housing  150 , the pressure of the inert gas in the housing  150  decreases below the reference pressure. In this case, the gas pressure sensor  165  may detect the pressure drop and generate an alarm. Therefore, an operator can be immediately notified whether the pin hole (P) is formed in the housing  150 , so that the operator can take necessary action promptly. 
         [0034]    In addition, the control board  170  may be connected with the gas pressure sensor  165 . When the pressure of the inert gas gauged by the gas pressure sensor  165  is lower than the reference pressure, the control board  170  may interrupt the operation of the heating element  155 . In detail, the control board  170  can interrupt power to the electric wire  151  connected to the heating element  155 . Therefore, heating the chemical (C) contained in the inner chemical bath  101  can be stopped. Further, the control board  170  can suspend the process by preventing an additional substrate (W) from being inserted into the inner chemical bath  101 . 
         [0035]    The housing  150  may be connected with an inert gas supply tube  163  and an inert gas discharge tube  164 . Therefore, while the inert gas is supplied to the housing  150  through the inert gas supply tube  163  and simultaneously discharged from the housing  150  through the inert gas discharge tube  164 , the housing can be filled with the inert gas. 
         [0036]    In this case, the gas pressure sensor  165  may be connected with the inert gas discharge tube  164  to gauge the pressure of the inert gas when the inert gas is discharged from the housing  150 . Further, a discharge cap  166  may be installed on the inert gas discharge tube  164 . The discharge cap  166  is opened when the pressure inside the housing  150  increases excessively. Therefore, extreme conditions of pressure inside the housing  150  can be prevented. 
         [0037]    A gas regulator  161  may be connected with the inert gas supply tube  163 . The gas regulator  161  keeps the pressure of the inert gas at a constant level when the inert gas is supplied to the housing  150 . Further, a mass flow controller (MFC)  162  may be connected with the inert gas supply tube  163 . The MFC  162  may keep the flow rate of the inert gas to the housing  150  at a constant level. Further, when the flow rate of the inert gas to the housing  150  exceeds a reference level, the MFC  162  may generate an alarm. 
         [0038]    As described above, according to the present invention, even when the housing is corroded by the chemical and thus a pin hole is formed through the housing, the chemical cannot enter the housing through the pin hole since the inert gas filled in the housing is discharged through the pin hole in the form of bubbles to prevent inflow of the chemical. Therefore, the chemical does not make direct contact with the heating element, so that contamination of the chemical and fire can be prevented since the heating element is not corroded by the chemical. 
         [0039]    Further, when the gas pressure sensor is installed, an operator can be immediately notified when the pin hole is formed through the housing. Therefore, necessary actions can be promptly taken. 
         [0040]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.