Abstract:
An apparatus for drying semiconductor wafers includes a bath for receiving semiconductor wafers and for holding a fluid, a chamber for providing an area where vapor is flowable over the bath, a supply pipeline for supplying vapor to the chamber, a vapor discharging pipeline for expunging vapor in the chamber, a fluid discharging pipeline for draining fluid in the chamber therefrom, and a protector for maintaining a distance between the semiconductor wafers during a drying process.

Description:
This application claims the priority of Korean Patent Application No. 2002-45611, filed Aug. 1, 2002, in the Korean Intellectual Property Office, the entire contents of which is hereby incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to an apparatus for drying a semiconductor wafer, and more particularly, to an apparatus for drying a semiconductor wafer using an isopropyl alcohol (IPA) vapor drying method. 
   2. Description of the Related Art 
   In general, a cleaning process of a semiconductor chip includes the removal of impurities generated on a semiconductor wafer during a manufacturing process. The cleaning process may include processing the semiconductor wafer using chemical solutions, rinsing the chemically processed semiconductor wafer using deionized water (DIW), and drying the rinsed semiconductor wafer. 
   In the prior art, a spin drying method is commonly used to dry a semiconductor wafer. Recently, due to an increase in an integration density of semiconductor devices, a vapor drying method has been used. The vapor drying method takes uses isopropyl alcohol (IPA) vapor to remove the DIW. 
   In a conventional apparatus for drying semiconductor wafers, semiconductor wafers are loaded in a chamber and an IPA solution is supplied into the chamber. The IPA solution supplied into the chamber is vaporized by heat produced by a heater positioned under the chamber. As the IPA solution is vaporized, the DIW remaining on the semiconductor wafers substantially removed. 
   The conventional apparatus for drying semiconductor wafers cannot precisely control the degree at which the IPA solution is vaporized. If the IPA solution is excessively vaporized in the chamber, a considerable amount of carbon (C) remains on the surfaces of the dried semiconductor wafers. 
   Recently, an apparatus for drying semiconductor wafers using IPA vapor, which includes an integrated bath and chamber, has been suggested. According to this apparatus, during a drying process DIW overflows the bath, and nitrogen gas and IPA vapor can be supplied to the chamber. More particularly, a drying process according to the apparatus is performed as follows. The bath, in which a semiconductor wafer is loaded, is made to overflow with DIW, and then nitrogen gas and IPA vapor are supplied from above the semiconductor wafer into the chamber. Simultaneously, the DIW is slowly discharged toward a lower part of the semiconductor wafer. 
     FIG. 1  is a cross-sectional view of a conventional apparatus for drying semiconductor wafers using a conventional IPA vapor drying method according to an exemplary embodiment of the present invention. Referring to  FIG. 1 , the apparatus for drying semiconductor wafers includes a bath  200 , which is provided so that a semiconductor wafer  100  can soak in DIW  210 . In addition, a chamber  300  is included, which surrounds the bath  200  and overlaps an upper part of the bath  200 . 
   The bath  200  includes a DIW outlet  220 , through which the DIW  210  can drain. A semiconductor wafer supporter  230  is arranged under the semiconductor wafer  100  to support the semiconductor wafer  100 . Guides are formed on the surface of the semiconductor wafer supporter  230  facing the semiconductor wafer  100 . The structure of the guides will be described in greater detail hereinafter. 
   A pipeline  312  for supplying nitrogen gas and/or, a pipeline  314  for supplying nitrogen gas and IPA vapor, and a pipeline  320 , through which overflowed DIW drains, are connected to the chamber  300 . An outlet  330 , through which nitrogen gas and IPA vapor in the chamber  300  drain to the outside, is provided through a sidewall of the chamber  300 . 
     FIG. 2A  is a diagram illustrating guides formed on the semiconductor wafer supporter  230  of the apparatus for drying semiconductor wafers shown in FIG.  1 .  FIG. 2B  is a cross-sectional view taken along line  2 B- 2 B′ of FIG.  2 A and as seen from a direction indicated by A. Referring to  FIGS. 2A and 2B , three guides, i.e., first, second, and third guides  231 ,  232 , and  233 , are formed on the surface of the semiconductor wafer supporter  230  facing the semiconductor wafer  100 . The first and second guides  231  and  232  are formed to have a substantially V-shaped groove so that the semiconductor wafer  100  can be inserted in the substantially V-shaped grooves of the first and second guides  231  and  232 . When a drying process is performed with semiconductor wafers supported by the semiconductor wafer supporter  230  having the three guides  231 ,  232 , and  233 , adjacent semiconductor wafers may be attached to one another, as will be described in greater detail in the following paragraphs. 
     FIGS. 3A through 3D  are diagrams illustrating a drying process performed in an apparatus for drying semiconductor wafers using a semiconductor wafer supporter having three guides. Referring to  FIG. 3A , semiconductor wafers  100  are loaded in the bath  200  filled with the DIW  210 . The semiconductor wafers  100  are supported by the semiconductor wafer supporter  230 . The structure of the semiconductor wafers  100  being supported by the semiconductor wafer supporter  230  has been described above with reference to  FIGS. 2A and 2B . When the semiconductor wafers  100  are loaded in the bath  200 , the bath  200  is filled so that the semiconductor wafers  100  can completely soak in the DIW  210 . 
   Referring to  FIG. 3B , the DIW  210  is drained from the bath  200  through the DIW outlet  220 , and nitrogen gas and IPA vapor are supplied toward the semiconductor wafers  100 . The DIW  210 , as marked by arrows  212  in  FIG. 3B , is drained in a downward direction so that an upper part of each of the semiconductor wafers  100  is exposed. The IPA vapor supplied into the bath  200  removes any residual DIW  210  remaining on the surfaces of the semiconductor wafers  100 . During the cleaning process, the semiconductor wafers  100  may move slightly, thereby possibly attaching to one another due to the surface tension therebetween. Various semiconductor wafers  100  in contact with each other are shown by points C in FIG.  3 B. 
   As shown in  FIG. 3C , the DIW  210  may remain attached between the semiconductor wafers  100 . Moreover, as illustrated in  FIG. 3D , the remaining DIW  210  may flow down a surface of a semiconductor wafer  100  due to gravity. This may cause the occurrence of a water mark  210 ′ on the surface of the semiconductor wafer  100 . 
   Recently, the size of semiconductor wafers has increased. In particular, many semiconductor wafers are manufactured having a size greater than 200 mm. In order to batch-process a considerable number of semiconductor wafers having an increased size, with an apparatus for drying semiconductor wafers using IPA vapor, the drying process is performed using a half pitch technique where a plurality of semiconductor wafers are loaded in the apparatus so that a gap between the semiconductor wafers is very small. If the half pitch drying technique is used, semiconductor wafers may move laterally, which may cause a plurality of the semiconductor wafers to attach to one another. If adjacent semiconductor wafers attach to one another during a drying process, DIW is likely to remain on the surface of the semiconductor wafers and ultimately leave watermarks. When this happens, device malfunctions may occur. 
   SUMMARY OF THE INVENTION 
   The exemplary embodiment of the present invention provides an apparatus for drying semiconductor wafers using an IPA vapor drying method, which reduces the likelihood that semiconductor wafers attach to one another during a drying process. 
   According to an exemplary embodiment of the present invention, an apparatus for drying semiconductor wafers includes a bath for receiving semiconductor wafers and for holding a fluid, a chamber for providing an area where vapor is flowable over the bath, a supply pipeline for supplying vapor to the chamber, a vapor discharging pipeline for expunging vapor in the chamber, a fluid discharging pipeline for draining fluid from the chamber therefrom, and a protector for maintaining a distance between the semiconductor wafers during a drying process. 
   The protector may be positioned so that a line connecting the center of the semiconductor wafers and the protector forms an angle of 0-45° with a horizontal line passing through the center of the semiconductor wafers. 
   The protector may be positioned so that the line connecting the center of the semiconductor wafers and the protector forms an angle of 22.5° with the horizontal line passing through the center of the semiconductor wafers. 
   Furthermore, an exemplary embodiment of the present invention provides an apparatus for drying a semiconductor wafers including a bath for receiving semiconductor wafers and for holding deionized water, a chamber for providing an area where vapor is flowable over the bath, a supply pipeline for supplying isopropyl alcohol (IPA) vapor to the chamber, an IPA vapor discharging pipeline for expunging vapor from the chamber, a fluid discharging pipeline for draining deionized water in the chamber therefrom, and a semiconductor wafer supporter arranged in the bath so as to support the semiconductor wafers, the supporter having a plurality of guides for receiving the semiconductor wafers, and a protector provided between the semiconductor wafers for maintaining a minimum distance between individual semiconductor wafers. 
   The protector may be positioned so that a line connecting the center of the semiconductor wafers and the protector forms an angle of 0-45° with a horizontal line passing through the center of the semiconductor wafers. 
   The protector may be positioned so that the line connecting the center of the semiconductor wafers and the protector forms an angle of 22.5° with the horizontal line passing through the center of the semiconductor wafers. 
   In addition, a semiconductor drying apparatus according to an exemplary embodiment of the present invention includes a bath, and a supporting member positioned within the bath, the supporting member having at least one protector for reducing the likelihood that adjacent semiconductor wafers positioned on the supporting member will come into contact. 
   Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The exemplary embodiments of the present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
       FIG. 1  is a cross-sectional view of a conventional apparatus for drying semiconductor wafers using a conventional IPA vapor drying method. 
       FIG. 2A  is a diagram illustrating guides formed on a semiconductor wafer supporter of the apparatus for drying semiconductor wafers shown in FIG.  1 . 
       FIG. 2B  is a cross-sectional view taken along line  2 B- 2 B′ of FIG.  2 A and seen from a direction indicated by A. 
       FIGS. 3A through 3D  are diagrams illustrating a drying process performed in an apparatus for drying semiconductor wafers, including a semiconductor wafer supporter having three guide. 
       FIG. 4A  is a diagram illustrating a protector and guides formed in a semiconductor wafer supporter of an apparatus for drying semiconductor wafers according to an exemplary embodiment of the present invention. 
       FIG. 4B  is a cross-sectional view taken along line  4 B- 4 B′ of FIG.  4 A and seen from a direction indicated by A′. 
       FIGS. 5A through 5C  are diagrams illustrating exemplary embodiments of first and second protectors shown in FIG.  4 A. 
       FIGS. 6A and 6B  are diagrams illustrating the principle of the first and second protectors shown in  FIG. 4A , for reducing the possibility that adjacent semiconductor wafers will come into contact, according to an exemplary embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention will be described more fully with reference to the accompanying drawings. The present invention may be embodied in many different forms and, therefore, should not be construed as being limited to the exemplary embodiments set forth herein. 
   In order to reduce the possibility that adjacent semiconductor wafers will contact one another during a drying process, an apparatus for drying semiconductor wafers according to an exemplary embodiment of the present invention may include a semiconductor wafer supporter having two protectors as well as three guides. 
     FIG. 4A  is a diagram illustrating guides and protectors formed on a semiconductor wafer supporter of an apparatus for drying semiconductor wafers according to an exemplary embodiment of the present invention.  FIG. 4B  is a cross-sectional view taken along line  4 B- 4 B′ of FIG.  4 A and seen from a direction indicated by A′. Referring to  FIGS. 4A and 4B , two protectors, i.e., first and second protectors  410  and  420 , as well as three guides, i.e., first, second, and third guides  231 ,  232 , and  233  are formed on the surface of a semiconductor wafer supporter  230  facing a semiconductor wafer  100 . The first and second guides  231  and  232  are formed to have, for example, a substantially V-shaped groove so that the semiconductor wafer  100  can be inserted into the substantially V-shaped grooves of the first and second guides  231  and  232 . The third guide  233  is formed to have, for example, a substantially Y-shaped groove so that the semiconductor wafer  100  can be inserted into the substantially Y-shaped groove. 
   The shapes of the various groves may be modified as required by the type of semiconductor wafers  100  used in the drying apparatus. The specific groove shapes disclosed herein are given by way of example. 
   The first and second protectors  410  and  420  are arranged between adjacent semiconductor wafers  100  so as to reduce the possibility that adjacent semiconductor wafers  100  will attache to one another during a drying process. The first and second protectors  410  and  420  are positioned below a horizontal line passing through the center of the semiconductor wafer  100 , so that a line  150 ′ between the center of the semiconductor wafer  100  and the first or second protector ( 410  or  420 ) forms an angle α of about 0-45° with the horizontal line. When the angle α is approximately 22.5°, the effect of reducing the likelihood that adjacent semiconductor wafers  100  will attach to one another may be increased. The positions of the first and second protectors  410  and  420  need not affect the operation of automation technology used to load or unload the semiconductor wafers  100 . 
     FIGS. 5A through 5C  are diagrams illustrating various exemplary embodiments of the first and second protectors  410  and  420  shown in FIG.  4 A. 
   Referring to  FIG. 5A , the first and second protectors  410  and  420  are rectangle-shaped so that the area of the surfaces of the first and second protectors  410  and  420  contacting a semiconductor wafer  100  can be increased. Accordingly, it is possible to reduce the likelihood that adjacent semiconductor wafers  100  will attach to one another. 
   Referring to  FIG. 5B , as is illustrated, the first and second protectors  410  and  420  have diamond-shaped end portions. The surface area of the first and second protectors  410  and  420  illustrated in  FIG. 5B  in contact with the semiconductor wafer  100  is reduced compared to other exemplary protector embodiments discussed herein. A watermark is less likely to be generated at the interface between the semiconductor wafer  100  and the first and second protectors  410  and  420  having the diamond-shaped end portions. 
   Referring to  FIG. 5C , as is illustrated, the first and second protectors  410  and  420  are relatively thin and each has a perpendicular portion at one end thereof. The first and second protectors  410  illustrated in  FIG. 5C  are referred to as having a “stick-shape.” The surface area of the first and second protectors  410  and  420  illustrated in  FIG. 5C  in contact with the semiconductor wafer  100  is relatively small compared to the exemplary protector embodiment illustrated in FIG.  5 A. Accordingly, a watermark is less likely to be generated at the interface between the semiconductor wafer  100  and the first and second protectors  410  and  420  having the stick-shape. 
   The exemplary embodiments illustrated in  FIGS. 5A-5C  should be considered as being only examples of the present invention. Other shapes and sizes for the first and second protectors  410  and  420  are well within the scope of the present invention. In particular, the protectors  410  and  420  may be triangular, elliptical, circular, etc., in shape. That is, the protectors may encompass entirely such shapes, or alternatively, only a portion of the protectors may have such a shape. Moreover, while two protectors ( 410  and  420 ) are shown in the included figures, the present invention may also be implemented with the use of a single protector. For example, a single protector may be used on a surface of the semiconductor wafer supporter  230  in order reduce the likelihood that semiconductor wafers will attach to each other. Deviations from the exemplary embodiments illustrated herein are within the purview of the present invention. 
     FIGS. 6A and 6B  are diagrams illustrating the principle of the first and second protectors  410  and  420  for averting adjacent semiconductor wafers from attaching to one another.  FIGS. 6A and 6B  show semiconductor wafers seen from above. 
   As shown in  FIG. 6A , if the first and second protectors  410  and  420  are not provided, the first and second semiconductor wafers  100   a  and  100   b  have a distance R therebetween. Therefore, the first and second semiconductor wafers  100   a  and  100   b  each have a movable distance of 
       R   2       
 
to the right and to the left, respectively. In other words, the first semiconductor wafer  100   a  located on the left may move to the right by as much as a distance of 
         R   2     .       
 
Likewise, the second semiconductor wafer  100   a  located on the right may move to the left by as much as a distance of 
         R   2     .       
 
The greater the movable distance of each of the first and second semiconductor wafers  100   a  and  100   b , the possibility the first and second semiconductor wafers  100   a  and  100   b  will slant increases. Once the first and second semiconductor wafers  100   a  and  100   b  start to slant, the force causing the first and second semiconductor wafers  100   a  and  100   b  to slant increases.
 
   However, if the first and second protectors  410  and  420  are provided, as shown in  FIG. 6B , the first and second semiconductor wafers  100   a  and  100   b  each have a movable distance of 
         R   -   r     2       
 
to the right and to the left, respectively, even though the first and second semiconductor wafers  100   a  and  100   b  have a distance of R therebetween, which is the same as in FIG.  6 A. In other words, the first semiconductor wafer  100   a  may move to the right by as much as a distance of 
           R   -   r     2     ,       
 
which is smaller than 
         R   2     .       
 
Likewise, the second semiconductor wafer  100   b  may also move to the left by as much as a distance of 
           R   -   r     2     .       
 
As the movable distance of each of the first and second semiconductor wafers  100   a  and  100   b  decreases, the first and second semiconductor wafers  100   a  and  100   b  are less likely to move laterally. In addition, since the distance between the first and second semiconductor wafers  100   a  and  100   b  cannot be smaller than the thickness (r) of the first and second protectors  410  and  420 , it is possible to reduce the likelihood that the first and second semiconductor wafers  100   a  and  100   b  will attach to each other.
 
   The exemplary embodiments of the present invention are not limited to drying apparatuses that use IPA vapor and DIW. In particular, the exemplary embodiments of the present invention may be used with drying apparatuses that use various types of vapors and fluids during a semiconductor drying process. Further, the exemplary embodiments of the present invention are not limited to a semiconductor wafer supporter having two protectors as well as three guides; other numbers of each, arranged in other geometries than described above, could be utilized as would be known to one of ordinary kill in the art. 
   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. 
   As described above, the apparatus for drying semiconductor wafers using an IPA vapor drying method according to exemplary embodiments of the present invention supports semiconductor wafers using a semiconductor wafer supporter, on which one or more protectors capable of maintaining a distance between the semiconductor wafers are mounted. Accordingly, during a drying process, it is likely the semiconductor wafers will not attach to each other. In addition, it is possible to adjust a movable distance of each of the semiconductor wafers, taking advantage of the thickness of the protectors.