Abstract:
A wafer chuck illumination device for illuminating a light source to detect a position of foreign substances polluting a wafer chuck is provided. The device includes a lamp for generating a white light source, and a collimator lens for transforming the white light source into a beam of parallel rays and for directing the beam of parallel rays to a wafer chuck for detecting and cleaning foreign substances on the wafer chuck.

Description:
TECHNICAL FIELD 
   The present invention relates to semiconductor manufacturing equipment, and more particularly, to a wafer chuck illumination device for illuminating a light source to detect foreign substances polluting a wafer chuck. 
   DISCUSSION OF THE RELATED ART 
   In order to selectively remove photoresist and simultaneously etch semiconductor wafer and then form a pattern thereon after depositing the photoresist on the semiconductor wafer, an exposure device is used to remove the photoresist from the semiconductor wafer. 
   Generally, an exposure device requires a resolution over 0.3 μm and an adequate depth-of-focus to manufacture a highly integrated semiconductor device. For example, to form a sub-half micron pattern, certain devices and techniques are used, including an excimer laser for reducing a light source&#39;s wavelength, an exposure method using a phase-inversion mask, and a transform or tiled illumination method. The transform illumination method is disclosed in U.S. Pat. No. 5,446,587. 
   In a prior art exposure device, a light source penetrates first and second filters and an input lens positioned between the first and second filters by passing through a change mirror of a first light path. The light also penetrates a first lens and a relay lens, and is reflected to a change mirror of a second light path. The two lenses are respectively used to prevent an arcing portion of the light from being darkened by an ultraviolet (U.V.) lamp and irradiate light penetrated through a front end lens of, for example, the relay lens. The relay lens is also used to control a focal point of the light source to improve a focal point of an image. The light reflected from the second light path mirror is passed through a condenser lens through which the light source penetrates uniformly and in parallel, a reticle and projection lens, and then is exposed to a wafer positioned on a stage. 
   As shown in  FIG. 1 , in order to align wafers in an exposure device, light generated from a superhigh temperature mercury lamp is irradiated to align a reticle  18 , and the light is then irradiated to a third scope  20  to sense a tilt of the reticle  18 . First and second halogen lamps  10  and  12  perform an auto global alignment (AGA) measurement. Light generated from the first halogen lamp  10  is reflected through a first scope  14  and a first reflection mirror  36 , and light generated from the second halogen lamp  12  is reflected to a second reflection mirror  38  through a second scope  16 . The light reflected through the first and second reflection mirrors  36  and  38  is illuminated to an alignment mark of a wafer  26  through a projection lens  22 . The light reflected from the alignment mark is again reflected through the first and second reflection mirrors  36  and  38 . The light reflected through the first and second reflection mirrors  36  and  38  is transferred to the first and second scopes  14  and  16  to sense a tilt of an X-Y stage  24 . 
   In the exposure device a wafer chuck for safely receiving wafers may be polluted with foreign substances such as several kinds of polymers. When the wafer chuck is polluted, a partial focus defect is generated in an exposure procedure. In other words, a pattern is partially distorted or collapses. Thus, the wafer chuck should be cleaned to prevent the defect. However, the interior of the exposure device is dark, and a wafer stage where the wafer chuck is located is in a stand-by position or an initial position. Thus, in order to clean the wafer chuck, the wafer stage must be moved to a working position. 
   As the wafer chuck is in a dark state one can detect whether foreign substances exist thereon by observing the surface of the wafer chuck by projecting light onto the wafer chuck. However, when an instrument such as a flashlight is used to illuminate the surface of the wafer chuck it is difficult to observe the existence of foreign substances and to determine whether to clean the wafer chuck. Furthermore, the interior of the exposure device may be damaged by mistakenly using a flashlight to observe pollutants. 
   SUMMARY OF THE INVENTION 
   A wafer chuck illumination device which is capable of automatically irradiating light on a wafer chuck to perform a cleaning operation for the wafer chuck is provided. The device prevents the interior of semiconductor manufacturing equipment from being damaged by automatically irradiating light on the wafer chuck without using an instrument such as a flashlight. 
   One aspect of the present invention provides a wafer chuck illumination device for use in semiconductor manufacturing equipment, including a lamp that is installed on an equipment inner wall and that generates a white light source and irradiates the white light source to a wafer chuck. 
   Another aspect of the present invention provides a wafer chuck illumination device for use in semiconductor manufacturing equipment, including a lamp that is installed on an equipment inner wall and that generates a white light source, and a collimator lens for transforming the white light source generated from the lamp to a beam of parallel rays and for penetrating the beam of parallel rays through the wafer chuck. 
   The beam of parallel rays penetrated from the collimator lens is diffusedly reflected by foreign substances of the wafer chuck, thus a user can check a position of the foreign substances. Herewith, at least one lamp and collimator lens may be installed. 
   Another aspect of the present invention provides a wafer chuck illumination device for use in semiconductor manufacturing equipment, including a wafer stage for transferring a wafer chuck to a cleaning working position, the wafer stage being provided with the wafer chuck on which wafers for an exposure are mounted, at least one lamp that is installed on an equipment inner wall and that generates a white light source, and at least one collimator lens for transforming the white light source irradiated from the lamp to a beam of parallel rays and for penetrating the beam of parallel rays through the wafer chuck. 
   Another aspect of the invention provides a wafer chuck illumination device, including a wafer stage, which is provided with a wafer chuck on which wafers for an exposure are mounted, and which moves the wafer chuck forward and backward, right and left, upward and downward and in a tilt direction, etc. to an exposure working position or a cleaning working position; a controller for outputting a lamp drive signal after moving the wafer stage to the cleaning position when a drive command for cleaning the wafer chuck is performed; at least one lamp that is installed on an equipment inner wall and that generates a white light source in response to the lamp drive signal of the controller; and a monitor for displaying on a screen several kinds of commands under control of the controller and for providing the controller with the command selected on the screen. 
   Another aspect of the invention provides a wafer chuck illumination device for use in semiconductor manufacturing equipment, including a lamp that is installed on an equipment inner wall and that generates a white light source, a collimator lens for transforming the light source generated from the lamp to a beam of parallel rays and for penetrating the beam of parallel rays through the wafer chuck, and a switch for turning the lamp on or off. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Exemplary embodiments of the invention are described with reference to the accompanying drawings, of which: 
       FIG. 1  illustrates a conventional exposure device for use in manufacturing a semiconductor device; 
       FIG. 2  is a perspective view of a wafer chuck illumination device for use in semiconductor manufacturing equipment according to an exemplary embodiment of the invention; 
       FIG. 3  is a sectional view of the wafer chuck illumination device; 
       FIG. 4  is a block diagram illustrating driving a lamp according to an exemplary embodiment of the invention; and 
       FIGS. 5   a  and  5   b  are screens illustrating commands to be selected according to an exemplary embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 2 and 3 , a wafer chuck illumination device includes a wafer chuck  102 , a wafer stage  100 , an equipment inner wall  112 , a first socket  114 , a second socket  116 , first and second lamps  108  and  110 , and first and second collimator lenses  104  and  106 . 
   Semiconductor wafers are mounted on the wafer chuck  102  so that the wafers may be exposed. The wafer stage  100  is provided with the wafer chuck  102 , and moves the wafer chuck  102  forward and backward, right and left, upward and downward and in a tilt direction, etc. to an exposure position and cleaning working position. The first socket  114  is installed on one side of the equipment inner wall  112 . The second socket  116  is installed on another side of the equipment inner wall  112 . 
   The first and second lamps  108  and  110  are each fastened to the first and second sockets  114  and  116 , to generate a white light source. The first and second collimator lenses  104  and  106  transform a light source irradiated from the first and second lamps  108  and  110  to a beam of parallel rays, and penetrate the beam of parallel rays through the wafer chuck  102 . 
     FIG. 4  is a schematic block diagram illustrating driving a lamp for irradiating a light source to the wafer chuck according to another exemplary embodiment of the invention. 
   With reference to  FIG. 4 , a wafer chuck illumination device includes the wafer stage  100 , a controller  120  and a monitor  122 . The wafer stage  100  is provided with the wafer chuck  102  on which wafers to be exposed are mounted, and moves the wafer chuck  102  forward and backward, right and left, upward and downward and in a tilt direction, etc. to an exposure position and a cleaning working position. 
   The controller  120  moves the wafer stage  100  to the cleaning working position when a drive command for cleaning the wafer chuck  102  is performed, and then drives the first and second lamps  108  and  110  for outputting a lamp drive signal. 
   The monitor  122  displays a screen for selecting several kinds of commands to be controlled by the controller  120  and provides the controller  120  with the command selected on the screen. 
     FIGS. 5   a  and  5   b  are screens illustrating commands to be selected according to an exemplary embodiment of the invention. Referring to  FIGS. 5   a  and  5   b , an operation of the exemplary embodiments of  FIGS. 2-4  will be described in detail. 
   The controller  120  displays on the monitor  122  a screen for selecting a command as shown in  FIG. 5   a . At this time, when, for example, a user, selects a manual operation command displayed on the monitor  122 , the controller  120  displays sub commands for an execution of several kinds of commands on the screen as shown in  FIG. 5   b . When the user selects a white light command by using a mouse or cursor, the controller  120  drives the wafer stage  100  to move the wafer chuck  102  to the cleaning working position. When a transfer of the wafer chuck  102  to the cleaning working position is completed, the controller  120  lights the first and second lamps  108  and  110 . 
   When the first and second lamps  108  and  110  are lighted, a light source, which is irradiated from the first and second lamps  108  and  110 , is turned into a beam of parallel rays after passing through the first and second collimator lenses  104  and  106 , and is then directed to the wafer chuck  102 . Thus, the user can locate and remove foreign substances  124  on/from the wafer chuck  102  because the parallel light is diffusedly reflected by the foreign substances  124  that have, for example, diffracting or reflecting properties that are different than the wafer chuck  102 . 
   Though one exemplary embodiment of the invention provides lighting the first and second lamps  108  and  110  after moving the wafer stage  100  to the cleaning working position, the first and second lamps  108  and  110  may also be lighted after moving the wafer stage  100  to the cleaning working position when a user manually manipulates a switch. 
   Though another exemplary embodiment of the invention provides lighting the first and second lamps  108  and  110  after moving the wafer stage  100  to the cleaning working position so that a light source generated from the first and second lamps  108  and  110  is transformed to a beam of parallel rays through the first and second collimator lenses  104  and  106  and is then irradiated to the wafer chuck  102 ; a light source generated from the first and second lamps  108  and  110  without passing through the first and second collimator lenses  104  and  106  may be directly radiated. 
   As described above, according to an exemplary embodiment of the invention, a lamp is turned on after moving a wafer chuck to a cleaning working position by driving a wafer stage in exposure equipment for use in manufacturing a semiconductor device, and then light is irradiated onto the wafer chuck, thereby a user can locate and clean a position of foreign substances by using light diffusedly reflected by the wafer chuck. The position of foreign substances can be easily found without using an instrument such as a flashlight, etc. In addition, damage to or pollution of the equipment caused by improper use of the instrument can be prevented. 
   While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled 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 appended claims.