Abstract:
The present invention relates to an end point detector for etching equipment. The embodiment of the present invention has a unique feature which allows for a minimal contact between a connector and viewing window. This feature prevents scratches on the surface of the viewing window when the connector is removed or replaced.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application claims the priority of Korean Patent Application No. 2003-75748, filed on 29 Oct. 2003, the contents of which are hereby incorporated by reference in their entirety as if fully set forth herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to an end point detector used in etching equipment. More particularly, the present invention relates to an end point detector that minimizes a contact area between a viewing port and an optical cable-fixing connector, which reduces scratches and wear and tear on the surface of a viewing window during removal and replacement of connector.  
         [0003]     An end point detector (EPD) is an apparatus applied to a process chamber, specifically an etching chamber, used for a semiconductor device fabrication process.  
         [0004]     More specifically, a window is installed over an opening in a wall of an etching chamber, and light emitted or received through the window is transmitted to detection equipment via an optical cable connected between the detection equipment and the window.  
         [0005]     The transmitted light is analyzed to monitor processes within the chamber, such as the amount of etching reactants in order to monitor the etching process, i.e., control the end point.  
         [0006]     As used herein, the term “end point” refers to the amount of time required to etch and expose a silicon substrate or other films. For detection of light and wavelengths used for end point detection, the optical cable should not be bent or abruptly turned for accurate transmission of light.  
         [0007]      FIG. 1  is a cross-section view of conventional etching equipment having an EPD.  
         [0008]     The conventional etching equipment has, as illustrated, an electrostatic chuck  2  to hold a wafer by electrostatic force in a process chamber, and electrodes  3  and  4  disposed in an upper portion of the process chamber and on a bottom of electrostatic chuck  2 , respectively. In operation, reaction gas is injected between the electrodes to generate plasma.  
         [0009]     This configuration also includes a viewing window  5 , typically made of a quartz material, installed on a chamber wall  1  of the etching equipment so as to extend over the opening in chamber wall  1 . EPD controller (not shown) is installed outside of viewing window  5  to monitor the end point in the process chamber.  
         [0010]     Referring to  FIG. 2 , a bracket  5   a  is disposed external to, and tightly surrounding, viewing window  5 . An optical cable  6  extends from the EPD controller, and at its other end is fixedly inserted into a connector  7 , which is removably engaged with bracket  5   a.    
         [0011]     Typically, with an increase in the number of uses of the etching equipment, residual impurities accumulate in the process chamber, whereupon some of the impurities adhere to a surface of viewing window  5 . The impurities on viewing window  5  deteriorate light transmittance and may cause errors in the end point detection. In an attempt to minimize the errors, a periodic check of the equipment as well as a periodic replacement of one or more components of the equipment must be performed.  
         [0012]     A method of preventing a viewing window from accumulating impurities is disclosed in Korean Patent Publication No. 0159224 (“End Point Detector for Plasma Etching Equipment”). In addition, a method of preventing damage to a viewing window is described in Korean Patent Laid-Open No. 1999-74934 (“Window Assembly of Chamber Equipment for Fabrication of Semiconductor Device) and U.S. Pat. No. 6,322,660.  
         [0013]     Periodic cleaning of the chamber and replacement of components are essential. However, continual removal and replacement of connector  7  from/into bracket  5   a  leave scratches on the surface of viewing window  5 . The scratches on the surface of viewing window  5  cause errors in the EPD wavelength detection.  
       SUMMARY OF THE INVENTION  
       [0014]     It would therefore be desirable to provide an arrangement that can reduce or eliminate damage, such as scratches, on the surface of a viewing window during removal and replacement of a connector from/into a bracket of the viewing window.  
         [0015]     In one aspect of the invention, an end point detector apparatus for etching equipment includes a chamber wall having an opening therein, and a window disposed over the opening, a connector having a first end in the first end of said connector having a recess formed therein in contact with the window, and a bracket connected to the chamber wall around a periphery of the window and engaging the connector.  
         [0016]     In another aspect, an end point detector apparatus for etching equipment includes a chamber with a chamber wall having an opening therein, a window disposed over the opening, and a bracket connected to the chamber body around a periphery of the window, a connector adapted to be engaged within the bracket, said connector having a first end adapted to be in contact with the window, the first end of the connector having a recess formed therein, and an optical cable disposed within the connector, said optical cable having a first end adapted to receive light from the chamber via the window.  
         [0017]     In yet another aspect, equipment for semiconductor fabrication includes, a process chamber including a chamber wall having an opening therein, a window disposed over the opening in the chamber wall, a bracket connected to the chamber wall around a periphery of the window, and an optical cable connector engaged within the bracket, said connector having a first end in contact with the window, the first end of the connector having a recess formed therein. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a cross-section view of conventional etching equipment;  
         [0019]      FIG. 2  is a cross-section view of a conventional EPD apparatus; and  
         [0020]      FIG. 3  is a cross-section view of etching equipment having an EPD apparatus according to one of more aspects of the present invention.  
         [0021]      FIG. 4  is a cross-section view of etching equipment having an EPD apparatus according to one or more aspects of the present invention without an optical cable inserted therein. 
     
    
     DETAILED DESCRIPTION  
       [0022]     Now, the present invention will be described in detail by way of an embodiment with reference to the accompanying drawings.  
         [0023]      FIG. 3  shows a portion of a process chamber  11  including a chamber wall  10  having an opening formed therein, a viewing window  20  disposed over the opening in the chamber wall  10 , a bracket  30  connected to the chamber wall  10  around a periphery of the viewing window  20 , a connector  40  engaged within the bracket  30  having a first end  43  in contact with the viewing window  20 , and an optical cable  41  disposed within the connector  40  having a first end adapted to receive light from the inside of process chamber  11  by means of the viewing window  20 .  
         [0024]     Advantageously, the first end  43  of connector  40  is recessed to a predetermined depth to form a recess  42 , minimizing the contact area between connector  40  and a viewing window  20 .  
         [0025]     Beneficially, process chamber  11  includes an electrostatic chuck (see  FIG. 1 ) to hold a wafer, and electrodes for generating plasma to etch a pattern on the wafer.  
         [0026]     Beneficially, viewing window  20 , which is provided on one side of chamber wall  10 , is a transparent material, for example a quartz material, to allow the inside of the process chamber  11  to be viewed from the outside.  
         [0027]     Bracket  30  is provided on the outside of chamber wall  10  with a profile surrounding viewing window  20 . The bracket  30  is tightly welded on the periphery of the opening of the viewing window  20  and in communication with the outer periphery of the viewing window  20  outside of the process chamber  11 . Beneficially, bracket  30  is in communication with chamber wall  10  at the periphery of the opening in the chamber wall  10 . Beneficially, bracket  30  is in communication with chamber wall  10  by screw connection.  
         [0028]     Beneficially, connector  40  is removably engaged within bracket  30 , with one end of an optical cable  41  being fixedly inserted into connector  40 . With connector  40  engaged into bracket  30 , the first end  43  of connector  40  is in contact with viewing window  20 .  
         [0029]     Advantageously, a first end  43  of connector  40  in contact with viewing window  20  is horizontally recessed to a predetermined area to minimize the contact area between connector  40  and viewing window  20 . Beneficially, recess  42  extends from the first end  43  of the connector  40  to a bottom interior surface  44  of the connector  40 . As shown in  FIGS. 3 and 4 , the recess  42  is beneficially concave. Optionally, the recess  42  may have a stepped shape.  
         [0030]     Beneficially, the diameter of recess  42  of the connector  40  is larger than the diameter of optical cable  41 , thereby forming the bottom interior surface  44 . Beneficially, a surface area of a portion of connector  40  that contacts viewing window  20  is less than a surface area of the first end of an optical cable  41  that confronts and is spaced apart from the window  20 . Also beneficially, the first end of the optical cable  41  is positioned in a same plane as the bottom interior surface  44  of the connector  40 .  
         [0031]      FIG. 4  illustrates a case where optical cable  41  is not inserted in connector  40 , helping to better illustrate recess  42 .  
         [0032]     Now, the operation of the arrangement of  FIGS. 3 and 4  will be described as follows.  
         [0033]     Advantageously, first end connector  40  in contact with viewing window  20  is recessed to a predetermined area and predetermined depth to form recess  42 , thereby minimizing the contact area between connector  40  and viewing window  20 .  
         [0034]     An end point detector monitors the end point of an etching process by passing light between the process chamber and an EPD controller through viewing window  20  via optical cable  41  inserted in the connector  40 .  
         [0035]     Particularly, recess  42  of the connector  40  is formed over a portion of viewing window  20 , preventing impact and scratches caused by the engagement of connector  40 .  
         [0036]     In this way, scratches can be minimized or avoided on the surface of viewing window  20  when the first end of connector  40  is removed from and replaced into bracket  30 .  
         [0037]     While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the present invention is not limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.