Patent Publication Number: US-2005139240-A1

Title: Rinsing and drying apparatus having rotatable nozzles and methods of rinsing and drying semiconductor wafers using the same

Description:
BACKGROUND OF THE INVENTION  
      1. Technical Field  
      The present invention generally relates to equipment used in the fabrication of semiconductor devices. More particularly, the present invention relates to a rinsing and drying apparatus having rotatable nozzles and a method of rinsing and drying semiconductor wafers using the same.  
      A claim of priority is made to Korean Application No. 2003-99117, the disclosure of which is incorporated herein by reference in its entirety.  
      2. Discussion of the Related Art  
      Wet processes such as a wet cleaning process or a wet etching process are used to fabricate semiconductor devices from semiconductor wafers. A rinsing process usually follows a wet process to remove chemical solutions from the wafers, and a drying process follows the rinsing process in order to remove de-ionized water used in the rinsing process. De-ionized water must be completely removed from the wafers during the drying process, if not, “water mark” defects may be formed on the wafers. This defect causes contaminate particles to accumulate on the wafers, thereby causing contact failures in subsequently manufactured semiconductor devices.  
      Recently, the Marangoni principle has been widely used to maximize drying efficiency in conventional drying processes. One conventional method and apparatus using the Marangoni principle is disclosed in U.S. Pat. No. 5,884,640 to Fishkin et al., entitled “Method and apparatus for drying substrates”. The Fishkin patent discloses draining de-ionized water during a drying process through a valve installed in an outlet of a bath. The valve is controlled by a liquid level control system which requires precise adjustment of the valve to gradually lower liquid level in the bath.  
      Another conventional apparatus used to dry semiconductor wafers is disclosed in U.S. Pat. No. 5,896,875 to Yoneda, entitled “Equipment for cleaning, etching and drying semiconductor wafer and its using method.” The Yoneda patent discloses, pipe-shaped spray nozzles installed in an upper portion inside a process chamber, and a first rotatable arm provided in a lower portion inside the process chamber. In addition, a pair of second rotatable arms is installed on both ends of the first arm. The second arms have blow-out ports to spray chemical solutions and de-ionized water in an upward direction. Accordingly, a jet stream of cleaning solution and/or de-ionized water is generated inside the process chamber. As a result, the cleaning and/or rinsing efficiency of the process chamber is increased.  
      However, it is difficult to uniformly inject a drying source such as a drying gas into the process chamber, because the spray nozzles are fixed inside the process chamber. As a result, the overall efficiency of conventional drying processes remains quite limited.  
     SUMMARY OF THE INVENTION  
      According to one aspect of the invention, a rinsing and drying apparatus includes a bath for holding liquid, a conduit installed over the bath, and a plurality of rotatable nozzles attached to the conduit to spray a drying source onto semiconductor wafers.  
      In another aspect of the invention, a rinsing and drying apparatus includes a bath for holding liquid, a lid covering an upper portion of the bath, a conduit attached to a lower surface of the lid, a plurality of nozzles attached to the conduit to spray a drying source supplied through the conduit, a first power source fixed to the conduit to rotate the nozzles via a belt, and a second power source for swinging the nozzles within a predetermined angle.  
      The present invention also discloses a method of rinsing semiconductor wafers in a bath using de-ionized water, and spraying through a plurality rotatable nozzles provided over the bath, a drying source towards the rinsed wafers, wherein the plurality of rotatable nozzles are attached to conduit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above described aspects and advantages of the present invention will become more apparent to those of ordinary skill in the art upon consideration of the following description of preferred embodiments with reference to the attached drawings in which:  
       FIG. 1  is a side cross-sectional view of a rinsing and drying apparatus according to an embodiment of the present invention;  
       FIG. 2  is a front cross-sectional view taken along “A” of  FIG. 1 ;  
       FIG. 3  is a bottom plan view of a lid taken along “B” of  FIG. 1 ; and  
       FIG. 4  is a process flow chart illustrating a method of rinsing and drying semiconductor wafers of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention will now be described more fully with reference to the accompanying drawings in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are teaching examples. Like numbers refer to like elements throughout the specification.  
       FIG. 1  is a side cross-sectional view of a rinsing and drying apparatus according to an embodiment of the present invention.  FIG. 2  is a front cross-sectional view taken along the orientation indicated by arrow “A” in  FIG. 1 .  FIG. 3  is a bottom plan view of a lid taken along the orientation indicated by arrow “B” in  FIG. 1 .  
      Collectively,  FIGS. 1 through 3  show a bath  1  used to hold liquid such as chemical solution or deionized water. A rinsing process or a drying process is also performed in bath  1 . An exhaust conduit  1   a  is connected to a base of bath  1 , and liquid in bath  1  is drained through exhaust conduit  1   a . A lid  3  is used to cover bath  1 . Lid  3  has an upper surface  3   a  and a lower surface  3   b . A plurality of rings comprising first through third groups of rings  5   a ,  5   b ,  5   c , respectively, are attached to the lower surface  3   b . Each group of rings preferably includes at least two rings. For example, a first group of rings may include three rings  5   a  aligned in a straight line as shown in  FIG. 1 . In other words, first group of rings  5   a  are located in a straight line that traverses above bath  1 . A first conduit  7   a  is inserted into first group of rings  5   a.    
      Further, second group of rings  5   b  and third group of rings  5   c  are respectively provided in parallel on both sides of first conduit  7   a . Second and third groups of rings  5   b ,  5   c  are also attached to the lower surface  3   b . A second conduit  7   b  is inserted into second group of rings  5   b , and a third conduit  7   c  is inserted into third group of rings  5   c . Conduits  7   a ,  7   b ,  7   c  are preferably rotatable about their central axes (“CA” of  FIGS. 1 and 2 ). Conduits  7   a ,  7   b ,  7   c  are provided to pass over wafers  53  loaded in bath  1 . Wafers  53  are supported by a wafer carrier  51 . Conduits  7   a ,  7   b ,  7   c  are drying source conduits, but are not limited to this embodiment. A three conduit system is disclosed in the embodiment of the present invention; however, a single conduit, a pair of conduits, or more than three conduits may be used in the present invention. Conduits  7   a ,  7   b ,  7   c  are connected to a main conduit  7  fixed at one end of lid  3 .  
      A first group of nozzles  9   a  are attached and evenly arranged along first conduit  7   a . Similarly, second and third groups of nozzles  9   b ,  9   c  are attached and evenly arranged along second and third conduits  7   b ,  7   c , respectively.  
      As shown in  FIG. 3 , each of nozzles  9   a ,  9   b ,  9   c  preferably has a slit-type opening  9   s . Nozzles  9   a ,  9   b ,  9   c  are rotatable. In this case, vertical axes passing through a central point of slit-type openings  9   s  acts as a rotating axis. A drying source introduced into conduits  7   a ,  7   b ,  7   c  is sprayed through slit-type openings  9   s  of nozzles  9   a ,  9   b ,  9   c  onto wafers  53 . Nozzles  9   a ,  9   b ,  9   c  are rotated to uniformly spray a drying source onto wafers  53 . In other words, rotating of nozzles  9   a ,  9   b ,  9   c  facilitate the injection of a drying source to uniformly fill gaps between wafers  53 . As a result, drying efficiency is improved, and water mark defects can be prevented without increasing a pitch size P between adjacent wafers  53 . The drying source may be isopropyl alcohol (IPA) or nitrogen gas, for example. Nitrogen gas may be hot nitrogen gas having a temperature above room temperature.  
      Further, embodiments of the present invention may optionally include IPA nozzles  9   i , which are attached to lower surface  3   b  of lid  3  between conduits  7   a ,  7   b ,  7   c . In this case, nozzles  9   a ,  9   b    9   c  preferably spray a first drying source, such as nitrogen gas, and IPA nozzles  9   i  preferably spray a second drying source, such as IPA.  
      Nozzles  9   a ,  9   b ,  9   c  are rotated by a first power source comprising one or more motors. Preferably, nozzles  9   a ,  9   b ,  9   c  are rotated by motors  11   a ,  1   b ,  1   c , respectively. In this case, motors  11   a ,  1   b ,  1   c  are preferably fixed to one end of conduits  7   a ,  7   b ,  7   c , respectively. A rotating mechanism associated with motors  11   a ,  1   b ,  1   c  is inserted and fixed to first through third pulleys  13   a ,  13   b ,  13   c , respectively. The rotating mechanism of motors  11   a ,  11   b , and  11   c  is adapted to run in parallel with the rotational axes of nozzles  9   a ,  9   b ,  9   c . Pulleys  13   a ,  13   b ,  13   c  are preferably installed at the same level as nozzles  9   a ,  9   b ,  9   c.    
      When motors  11   a ,  1   b ,  1   c , are in operation, rotational force applied to pulleys  13   a ,  13   b ,  13   c  are transferred to first third belts  15   a ,  15   b ,  15   c , which in turn rotate nozzles  9   a ,  9   b ,  9   c . Nozzles  9   a ,  9   b ,  9   c  and pulleys  13   a ,  13   b ,  13   c  have protrusions  9   p  and  13   p , respectively, and belts  15   a ,  15   b ,  15   c  have openings  15   h  in which protrusions  9   p  and  13   p  are inserted to assist in maximizing transfer efficiency of the rotating force supplied by motors  11   a ,  11   b ,  11   c.    
      In another embodiment of the present invention, nozzles  9   a ,  9   b ,  9   c  rotate like sprinklers. That is, nozzles  9   a ,  9   b ,  9   c  rotate and spray the drying source without the assistance of a power source. Instead of slit-type opening  9   s , each of nozzles  9   a ,  9   b ,  9   c  has at least one sloped opening (not shown) located at an edge of a lower surface. The sloped opening preferably has a predetermined angle with respect to a vertical plane passing through a center of the nozzle. The force of the drying source sprayed through the sloped openings rotates nozzles  9   a ,  9   b ,  9   c.    
      In another embodiment of the present invention, conduits  7   a ,  7   b ,  7   c  rotate in an oscillating manner back and forth in clockwise and counterclockwise directions in limited arcs defined by a predetermined angle (“a” of  FIG. 2 ) about their central axes (CA). A second power source  21  is used to oscillate nozzles  9   a ,  9   b , and  9   c . Second power source  21  is preferably a motor fixed to lid  3 . In this case, second power source  21  preferably includes a rotating mechanism  23 . Rotating mechanism  23  is connected to conduits  7   a ,  7   b ,  7   c  through a horizontal bar  19 , a buffer bar  27 , and an auxiliary bar  25 .  
      In some additional detail, first through third vertical bars  17   a ,  17   b ,  17   c  are attached to conduits  7   a ,  7   b ,  7   c , respectively. Horizontal bar  19  is connected via pins to an end of vertical bars  17   a ,  17   b ,  17   c . Horizontal bar  19  is preferably disposed perpendicular to conduits  7   a ,  7   b ,  7   c . Therefore, when horizontal bar  19  moves left or right along a perpendicular line to conduits  7   a ,  7   b ,  7   c , nozzles  9   a ,  9   b ,  9   c  oscillate within the predetermined are defined by angle α.  
      One end of buffer bar  27  is connected to an end of horizontal bar  19  by a pin, and the other end of buffer bar  27  is connected to one end of auxiliary bar  25  by another pin. And the other end of auxiliary bar  25  is fixed to rotating mechanism  23 . In this case, when second power source  21  rotates rotating mechanism  23 , horizontal bar  19  moves back and forth, and nozzles  9   a ,  9   b ,  9   c  oscillate accordingly. When nozzles  9   a ,  9   b ,  9   c  oscillate by operation of second power source  21 , it is preferable that motors  11   a ,  11   b ,  11   c  are respectively fixed to conduits  7   a ,  7   b ,  7   c  to move along accordingly.  
      As a result, a drying source is uniformly supplied onto wafers  53  with the rotation and oscillation of nozzles  9   a ,  9   b ,  9   c.    
      Methods of rinsing and drying semiconductor wafers using the rinsing and drying apparatus shown in  FIGS. 1 through 3  will be described.  
       FIG. 4  is a process flow chart illustrating a method of rinsing and drying semiconductor wafers according to an embodiment of the present invention.  
      Referring to  FIGS. 1 through 4 , first, semiconductor wafers  53  are cleaned or etched using a chemical solution (step  101 ). Wafers  53  in a bath  1  are rinsed using de-ionized (DI) water (step  103 ). The rinsing step is performed using conventional methods. For example, the rinsing process is preferably performed by continuously supplying over-flowing DI water into bath  1 . DI water is supplied into bath  1  through a DI water inlet (not shown) connected to bath  1 .  
      Optionally, after the rinsing step, IPA is supplied toward a surface of the DI water through IPA nozzles  9   i  installed over bath  1  (step  105 ). As a result, an IPA layer is formed on the surface of the DI water. Subsequently, DI water is slowly drained through an exhaust conduit  1   a  connected to the base of bath  1  (step  107 ). Subsequently, DI water is replaced with IPA because IPA has a better surface tension on wafers  53  than DI water.  
      After draining the DI water, a drying source such as nitrogen gas is supplied onto wafers  53  through nozzles  9   a ,  9   b ,  9   c  (step  109 ). Nitrogen gas may be hot nitrogen gas heated above room temperature. While the drying source is supplied, it is preferable that nozzles  9   a ,  9   b ,  9   c  are rotated. Nozzles  9   a ,  9   b    9   c  are rotated by a first power source comprising motors  11   a ,  11   b ,  11   c . Alternatively, nozzles  9   a ,  9   b ,  9   c  may rotate in a sprinkler manner without a power source.  
      Furthermore, a second power source  21  preferably oscillates nozzles  9   a ,  9   b ,  9   c . As a result, the drying source is uniformly supplied onto wafers  53  through the rotation and oscillation of nozzles  9   a ,  9   b ,  9   c , thereby preventing the formation of defects such as water marks on wafers  53 .  
      As described above, according to the present invention, a drying source can be uniformly sprayed onto wafers through the rotation and oscillation of nozzles. Therefore, the drying efficiency of semiconductor wafers rinsed in the bath can be significantly improved.