Patent Publication Number: US-2019189470-A1

Title: Wafer cleaning apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Korean Patent Application No. 10-2017-0175715, filed on Dec. 20, 2017, in the Korean Intellectual Property Office, and entitled: “Wafer Cleaning Apparatus,” is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     Embodiments relate to a wafer cleaning apparatus. 
     2. Description of the Related Art 
     As the development of integration techniques in the semiconductor industry has accelerated, various films formed on a wafer tend to have a high step portion, which may pose a challenge to providing stable processing and yield. Accordingly, planarization technologies have come to prominence, and among them, a chemical mechanical polishing (CMP) technology has been widely employed. A degree of polishing may affect semiconductor yield and quality. 
     SUMMARY 
     Embodiments are directed to a wafer cleaning apparatus, including a wafer roller to rotate a wafer in a first direction, first and second roller brushes disposed to be parallel to each other, the first and second roller brushes to be brought into contact with opposing surfaces of the wafer to clean the opposing surfaces of the wafer, respectively, while rotating in mutually opposing directions, first and second pipes having a longitudinal direction parallel to each other, the first and second pipes being above the first and second roller brushes and conveying a cleaning liquid for cleaning the wafer, first and second nozzle groups disposed along the longitudinal direction of the first and second pipes, respectively, and including a plurality of nozzles to spray the cleaning liquid onto the opposing surfaces of the wafer at a predetermined angle, respectively, and a binding part connecting the first and second pipes to restrain movement of the first and second pipes. 
     Embodiments are also directed to a wafer cleaning apparatus, including first and second roller brushes disposed to be adjacent and parallel to each other in a longitudinal direction, to clean a front surface and a rear surface of a wafer, respectively, and to rotate in mutually opposing directions, first and second pipes disposed to be parallel to each other above the first and second roller brushes, and allowing a cleaning liquid for cleaning the wafer to be introduced into the first and second pipes, first and second nozzle groups disposed along the longitudinal direction of the first and second pipes, respectively, and including a plurality of nozzles to spray the cleaning liquid to the front surface and the rear surface of the wafer at a predetermined angle, respectively, and a binding part connecting the first and second pipes to restrain movement of the first and second pipes. 
     Embodiments are also directed to a wafer cleaning apparatus, including first and second pipes disposed to be parallel to each other to face a front surface and a rear surface, respectively, of a vertically oriented wafer, the first and second pipes each including a plurality of nozzles to spray a cleaning liquid, a number of nozzles of the first pipe being greater than a number nozzles of the second pipe, a binding part connecting and fixing the first and second pipes, and first and second roller brushes disposed to be parallel to each other, the first and second roller brushes to be brought into contact with the front surface and the rear surface of the wafer to clean the front surface and the rear surface, respectively, while rotating in mutually opposing directions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will become apparent to those of skill in the art by describing in detail example embodiments with reference to the attached drawings in which: 
         FIG. 1  illustrates a plan view schematically illustrating a chemical mechanical polishing (CMP) facility employing a wafer cleaning apparatus according to an example embodiment; 
         FIG. 2  illustrates a plan view of a wafer cleaning apparatus according to an example embodiment; 
         FIG. 3  illustrates a side view of the wafer cleaning apparatus of  FIG. 2  in a direction of I; 
         FIG. 4  illustrates a side view of the wafer cleaning apparatus of  FIG. 2  in a direction of II; 
         FIG. 5A  illustrates a graph illustrating a cleaning effect of a wafer cleaning apparatus according to a comparative example; and 
         FIG. 5B  illustrates a graph illustrating a cleaning effect of a wafer cleaning apparatus according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described in detail with reference to the accompanying drawings. 
     First, a chemical mechanical polishing (CMP) facility will be described with reference to  FIG. 1 .  FIG. 1  is a plan view schematically illustrating a CMP facility employing a wafer cleaning apparatus according to an example embodiment. 
     The CMP facility  1  may include a load lock facility  50  in which a cassette on which a plurality of wafers are stacked is placed, a polishing apparatus  70  performing a planarization process on a wafer, a wafer transfer robot  60  loading or unloading a wafer to or from the polishing apparatus  70 , a wafer cleaning apparatus  100  performing a cleaning process on a wafer unloaded from the polishing apparatus  70 , and a pre-inspection apparatus  500 . The pre-inspection apparatus  500  may include a load cup part  501  for mounting a load cup facility and a head part  502  for mounting a polishing head. 
     Hereinafter, the wafer cleaning apparatus  100  will be described with reference to  FIG. 2  through  FIG. 4 .  FIG. 2  is a plan view (from above) of a wafer cleaning apparatus according to an example embodiment,  FIG. 3  is a side view of the wafer cleaning apparatus of  FIG. 2  viewed in a direction I in  FIG. 2 , and  FIG. 4  is a side view of the wafer cleaning apparatus of  FIG. 2  viewed in a direction II in  FIGS. 2 and 3 . 
     Referring to  FIGS. 2 and 3 , the wafer cleaning apparatus  100  according to an example embodiment may include first and second roller brushes  110  and  120 , first and second pipes  130  and  140 , first and second nozzle groups N 1  and N 2 , and a binding part  150 . 
     The first and second roller brushes  110  and  120  may be arranged to face each other with a wafer W (on which a cleaning operation is to be performed) interposed therebetween. The wafer W may be a semiconductor substrate on which the CMP process has been performed in a previous stage. 
     The first roller brush  110  may be disposed to be in contact with a front surface W 1  of the wafer W and the second roller brush  120  may be disposed to be in contact with a rear surface W 2  of the wafer W. The first and second roller brushes  110  and  120  may rotate in different directions D 2  and D 3  and clean the front surface W 1  and the rear surface W 2  of the wafer W, respectively. The first and second roller brushes  110  and  120  may have a length (e.g., in a lengthwise direction along the x-axis in  FIG. 2 ) greater than a radius of the wafer W. 
     Protrusions  111  and  121  for improving a cleaning effect of the wafer W may be provided on the surfaces of the first and second roller brushes  110  and  120 , respectively. Also, the front surface W 1  of the wafer W may be a surface on which a semiconductor layer for manufacturing a semiconductor chip has been grown. 
     The wafer W may be rotated in a first direction D 1  (for example, counter-clockwise as shown in  FIG. 4 , or out of the page at the top of the wafer W and into the page at the bottom of the wafer W as shown in  FIG. 3 ) between the first and second roller brushes  110  and  120  by a wafer roller  160 . In an example embodiment, for example, three wafer rollers  160  may be disposed (see  FIG. 4 ). According to an example embodiment, a plurality of idlers may support the wafer W and a single wafer roller  160  may rotate the wafer W. 
     The wafer roller  160  may be rotated by a driving device such as a motor. The wafer roller  160  may be brought into contact with an edge portion of the wafer W, and as the wafer roller  160  rotates, the wafer W may rotate in a first direction D 1 . For example, referring to  FIG. 4 , the wafer roller may rotate in a clockwise direction and the wafer W may rotate in a counter-clockwise direction. 
     The first and second pipes  130  and  140  may have flow channels through which a cleaning liquid to be sprayed to the wafer W is supplied. The first and second pipes  130  and  140  may have a long cylindrical rod shape and may be disposed to be parallel to each other, with the wafer W interposed therebetween, and may be disposed above the first and second roller brushes  110  and  120 . The first and second pipes  130  and  140  may have substantially the same length, and first and second nozzle groups N 1  and N 2  including a plurality of nozzles  131  and  141  may be disposed in the first and second pipes  130  and  140 , respectively. 
     The first and second nozzle groups N 1  and N 2  may be arranged to face the front surface W 1  and the rear surface W 2  of the wafer W in a longitudinal length direction of the first and second pipes  130  and  140 , respectively. The first and second nozzle groups N 1  and N 2  may be arranged to spray a cleaning liquid at predetermined angles θ 1  and θ 2  toward the front surface W 1  and the rear surface W 2  of the wafer W, respectively. 
     Referring to  FIG. 4 , the first and second nozzle groups N 1  and N 2  may be arranged to spray the cleaning liquid to a region A in which the wafer W rotates between the first and second roller brushes  110  and  120 , i.e., to a region in which a rotation direction D 1  of the wafer W and rotation directions D 2  and D 3  of the first and second roller brushes  110  and  120  match. Since the region A is a region in which the wafer W, while being introduced to space between the first and second roller brushes  110  and  120 , is cleaned, when the cleaning liquid is sprayed to the region, the cleaning liquid may be sufficiently used during a cleaning process of the first and second roller brushes  110  and  120 . 
     Referring to  FIG. 3 , the nozzles  131  and  141  of the first and second nozzle groups N 1  and N 2  may be positioned with a tilt of, for example, 50° to 70° with respect to the front surface W 1  and the rear surface W 2  of the wafer W to spray the cleaning liquid. For example, angles θ 1  and  02  may independently be about 50° to about 70°. The plurality of nozzles  131  and  141  may be arranged in a row at a predetermined interval in the first and second pipes  130  and  140 . 
     The plurality of nozzles  131  and  141  of the first and second nozzle groups N 1  and N 2  may be arranged such that an injection amount of the cleaning liquid injected per unit time is uniform. In an implementation, the injection amount per unit time may be about 500 ml/min or more to supply a suitable amount of the cleaning liquid required for cleaning the wafer W. 
     Further, the amount of the plurality of nozzles  131  of the first nozzle group N 1  may be greater than the amount of the plurality of nozzles  141  of the second nozzle group N 2  so that an injection amount of the cleaning liquid injected from the first nozzle group N 1  per unit time is greater than an injection amount of the cleaning liquid injected from the second nozzle group N 2  per unit time. In an implementation, the front surface W 1  of the wafer W may be a surface on which a semiconductor layer has been grown and the amount of the cleaning liquid sprayed to the front surface W 1  of the wafer W may be greater than that of the cleaning liquid sprayed to the rear surface W 2  of the wafer W. 
     The binding part  150  may connect and fix regions of the first and second pipes  130  and  140 , whereby spray angles of the plurality of nozzles  131  and  141  of the first and second nozzle groups N 1  and N 2  may be fixed. The binding part  150  may be prepared separately from the first and second pipes  130  and  140  and adhered or press-fit to the first and second pipes  130  and  140 , or may be integrally formed with the first and second tubing tubes  130  and  140 . The binding part  150  may be disposed to connect first ends of the first and second pipes  130  and  140 . In an implementation, the binding part  150  may be disposed proximate to ends of the first and second pipes  130  and  140  that are opposite to ends where the cleaning liquid is supplied and may space apart centers of the first and second pipes  130  and  140  by a first width WIDTH 1  in a y-axis direction. The binding part  150  may fix a centerline L of the first and second pipes  130  and  140  by a second width (distance) WIDTH 2  above the wafer W in a z-axis direction. In other implementations, the binding part  150  may be disposed in another region suitable to firmly fix the first and second pipes  130  and  140 . 
     The binding part  150  may connect and fix the first and second pipes  130  and  140 . Thus, the first and second pipes  130  and  140  may not rotate with respect to a central portion thereof in a longitudinal direction, preventing a change in the spray angle of the plurality of nozzles  131  and  141  of the first and second nozzle groups N 1  and N 2 . Therefore, the cleaning liquid may be uniformly applied to the wafer W at a predetermined angle. On the other hand, if the first and second pipes are separated, e.g., without the binding part  150 , the angle of spraying the cleaning liquid may change due to vibrations generated during a manufacturing process, in which case an area of a surface, for example, the front surface W 1 , of the wafer W to which a large amount of the cleaning liquid has been sprayed may be excessively cleaned to have a surface profile lower than that intended and an area of the surface of the water to which a small amount of cleaning liquid has been sprayed may have a surface profile higher than intended. If the surface profiles of the wafers differ by regions, quality of semiconductor chips manufactured in the wafer may not be uniform. These effects will be described with reference to  FIGS. 5A and 5B . 
       FIG. 5A  is a graph illustrating a cleaning effect of a wafer cleaning apparatus according to a comparative example, and  FIG. 5B  is a graph illustrating a cleaning effect of a wafer cleaning apparatus according to an example embodiment. 
     In the comparative example of  FIG. 5A  in which a binding part is not provided, it can be seen that a surface profile has a height difference of about 50 Å according to regions of the wafer. In contrast, in the case of  FIG. 5B , it can be seen that a surface profile has a height difference of about 20 Å or less, which is relatively uniform, compared with the comparative example. Therefore, the wafer cleaning apparatus of an example embodiment may improve efficiency of the CMP process. 
     By way of summation and review, facilities used in a CMP process may include a polishing apparatus performing polishing and a wafer cleaning apparatus performing cleaning. The wafer cleaning apparatus may be used for removing slurry residues and other particles remaining on a polished wafer. 
     As set forth above, embodiments may enhance efficiency of equipment used in a chemical mechanical polishing (CMP) process. Embodiments may provide a wafer cleaning apparatus that may increase efficiency of the CMP process. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.