Abstract:
Disclosed herein is a semiconductor wafer cleaning method using a semiconductor wafer cleaning device. The method includes providing a semiconductor wafer cleaning device with a back brush, bringing the back brush into contact with the entire lower surface of the semiconductor wafer, and cleaning an upper surface of the semiconductor wafer with a surface brush so as to clean the entire surface of the semiconductor wafer in an ever-horizontal state.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a device for cleaning a semiconductor wafer in the overall semiconductor process, and a method of cleaning the semiconductor wafer, using the device. 
     2. Description of the Related Art 
     As a device for and a method of cleaning a semiconductor wafer, a device for and a method of cleaning both surfaces of a semiconductor wafer have been proposed as disclosed in Japanese Patent Application Laid-Open. Nos. Hei 1-184831, 4-94537, 5-3184, 7-169732 and 8-71519. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a semiconductor wafer cleaning device capable of accurately holding even a large-diameter semiconductor wafer in a horizontal state and reliably effecting a process such as cleaning or the like thereon, and a semiconductor wafer cleaning method using the semiconductor wafer cleaning device. 
     According to one aspect of this invention, for achieving the above object, there is provided a semiconductor wafer cleaning device, comprising: 
     first cleaning means for holding a semiconductor wafer in a horizontal state and contacting the entire lower surface of the semiconductor wafer; and 
     second cleaning means for cleaning an upper surface of the semiconductor wafer. 
     According to another aspect of this invention, there is provided a method of cleaning a semiconductor wafer, comprising the following step: 
     a step for supporting the semiconductor wafer from a lower surface thereof so as to keep the same in a horizontal state and cleaning the lower surface of the semiconductor wafer and an upper surface thereof while the semiconductor wafer is being kept in the horizontal state. 
     Typical ones of various inventions of the present application have been shown in brief. However, the various inventions of the present application and specific configurations of these inventions will be understood from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which: 
     FIG. 1 is a cross-sectional view of a semiconductor wafer cleaning device showing a first embodiment of the present invention; 
     FIG. 2 is a cross-sectional view of a semiconductor wafer cleaning device illustrating a second embodiment of the present invention; 
     FIG. 3A is a cross-sectional view of a semiconductor wafer cleaning device depicting a third embodiment of the present invention; 
     FIG. 3B is a cross-sectional view of the semiconductor wafer cleaning device shown in FIG. 3A, which holds a semiconductor wafer thereon; and 
     FIG. 3C is an enlarged view of means for holding the semiconductor wafer placed on the semiconductor wafer cleaning device shown in FIG.  3 A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
     FIG. 1 is a cross-sectional view of a semiconductor wafer cleaning device showing a first embodiment of the present invention. 
     In FIG. 1, reference numerals  11 ,  12 ,  13 ,  14 ,  15 ,  16 ,  17 ,  18 ,  19 ,  20 ,  21 ,  22 ,  23 ,  24  and  25  indicate a semiconductor wafer, support pins, holding pins, a back brush which is brought into contact with the entire back of the semiconductor wafer  11 , a brush body, a chuck base, a shaft for the back brush, a motor for the back brush, a chuck-rotating belt, a shaft, a chuck-rotating motor, a surface brush, a brush arm, an arm for the holding pins, and a chuck shaft, respectively. 
     As shown in the present drawing, the chuck base  16  is provided with the support pins  12  and the holding pins  13 . The holding pins  13  are connected to the chuck-rotating belt  19  through the chuck shaft  25 . Further, the holding pins  13  are connected to the chuck-rotating motor  21  through the shaft  20 . The brush shaft  17  coupled to the motor  18  passes through a through portion lying in the center of the chuck shaft  25  and is connected to the back of the brush body  15 . The back brush  14  is provided over the brush body  15 . The reverse side of the brush body  15  and the back brush  14  are respectively shaped in the form of a circle substantially identical in size (surface area) to the semiconductor wafer  11 . Further, the arm  24  is connected to the holding pins  13 . 
     A method of cleaning a semiconductor wafer, using a semiconductor wafer cleaning device according to the first embodiment will next be explained. 
     Referring to FIG. 1, the semiconductor wafer  11  is placed on the support pins  12 . The arm  24  used for the holding pins  13  is driven by an air cylinder to move the holding pins  13 , so that the semiconductor wafer  11  is fixed. The chuck-rotating motor  21  rotates the chuck base  16  with the semiconductor wafer  11  placed thereon, through the shaft  20  and the chuck-rotating belt  19 . 
     Next, the brush arm  23  and the surface brush  22  are shifted to the surface of the semiconductor wafer  11  to start its cleaning. Simultaneously, the brush body  15  and the back brush  14  are rotated via the brush shaft  17  by the motor  18  and thereafter move up to the height of the back of the semiconductor wafer  11  under the action of the air cylinder to start the cleaning of both surfaces of the semiconductor wafer  11  simultaneously. 
     According to the first embodiment as described above, since the brush is brought into contact with the flexed entire reverse side of a 300-mm semiconductor wafer and supports the entire back thereof, the entire surface of the semiconductor wafer is kept in a substantially horizontal state, so that the semiconductor wafer can be washed uniformly. 
     Since both surfaces of the semiconductor wafer are cleaned simultaneously as distinct from one-side separate cleaning, the cleaning device can be reduced in size and an improvement in throughput can be achieved. 
     A second embodiment of the present invention will next be described. 
     FIG. 2 is a cross-sectional view of a semiconductor wafer cleaning device showing the second embodiment of the present invention. 
     In the same drawing, reference numerals  31 ,  32  and  33  indicate a semiconductor wafer, a vacuum chuck, and a purge chamber, respectively. This purge chamber is filled with fluid (liquid or gas). Reference numerals  34  and  35  indicate a surface brush and a brush arm respectively. 
     As shown in FIG. 2, a peripheral portion of the semiconductor wafer  31  is vacuum-chucked by about 5 mm by the vacuum chuck  32 . At this time, pressure applied to the upper surface of the semiconductor wafer  31  by the brush  34  is controlled so as to be substantially equal to that applied to the lower surface of the semiconductor wafer  31  by fluid. Thus, the semiconductor wafer  31  is no longer flexed. 
     Supporting the entire lower surface of the semiconductor wafer by fluid (liquid or gas) prevents “flexion” resulting from the weight of the semiconductor wafer itself. 
     Next, the semiconductor wafer is brushed from the upper surface thereof so as not to warp from the lower surface of the semiconductor wafer under the pressure of liquid or gas. Thereupon, the pressure of fluid is adjusted so that the semiconductor wafer can be always prevented from warping, i.e., the flatness of the semiconductor wafer can be made extremely satisfactory. 
     If a liquid or gas having cleaning action is used as the liquid or gas charged into the purge chamber  33 , then the lower surface of the semiconductor wafer can be washed while satisfactorily keeping the flatness of the semiconductor wafer. The gas or liquid having the cleaning action may include, for example, sulfuric acid (H 2 SO 4 ), ammonifying water, or water including a surface-active agent, etc. 
     A third embodiment of the present invention will next be explained. 
     FIG. 3A is a cross-sectional view of a semiconductor wafer cleaning device showing the third embodiment of the present invention, FIG. 3B is a cross-sectional view of the semiconductor wafer cleaning device holding a semiconductor wafer thereon, and FIG. 3C is an enlarged view of means for holding the semiconductor wafer placed on the semiconductor wafer cleaning device, respectively. 
     In these drawings, reference numerals  41  and  42  indicate support pins and holding pins respectively. Each of the holding pins  42  has a first supporter  42 A brought into contact with a more-inwardly extending portion of the lower surface of the semiconductor wafer, and a second supporter  42 B brought into contact with a more-outwardly extending portion of the upper surface of the semiconductor wafer. Reference numerals  43 ,  44 ,  45 ,  46  and  47  indicate a surface brush, a brush arm, an arm for the holding pins, a semiconductor wafer and a chuck base, respectively. 
     As shown in FIG. 3A, the chuck base  47  is provided with the support pins  41  and the holding pins  42 . The arm  45  is connected to the holding pins  42 . 
     As shown in FIG. 3B, the semiconductor wafer  46  is first placed on the support pins  41 . In doing so, the arm  45  is activated by an air cylinder to move the holding pins  42 , so that the semiconductor wafer  46  is fixed. Since, at this time, the holding pins  42  have the first supporters  42 A and the second supporters  42 B respectively, the flexed semiconductor wafer  46  is kept in a horizontal position to start its cleaning. 
     According to the third embodiment as described above, since the flexion of a semiconductor wafer having a large diameter (e.g., 300 mm) is corrected by the configurations of holding pins, the entire surface of the semiconductor wafer is kept at the same height so that the semiconductor wafer can be cleaned uniformly. 
     Further, since the holding pins may be simply changed in structure, the present cleaning device is cheapest in cost. Since the cleaning device is simple in mechanism, less trouble is achieved. 
     While the present invention has been described with reference to the illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to those skilled in the art on reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.