Abstract:
An apparatus for agitating a workpiece in a high pressure environment comprises a workpiece holder, a bearing, a pressure chamber housing, and a nozzle. The workpiece holder couples to the pressure chamber housing via the bearing. The nozzle couples to the pressure chamber housing. The workpiece holder comprises protrusions and a region for holding the workpiece. In operation a fluid exits the nozzle and impinges the protrusions of the workpiece holder causing the workpiece holder to rotate, which agitates the workpiece.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. Provisional Patent Application 60/202,835, filed on May 8, 2000, which is incorporated by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to the field of high pressure processing. More particularly, this invention relates of high pressure processing where a workpiece is agitated.  
         BACKGROUND OF THE INVENTION  
         [0003]    Fluid processing of a workpiece often requires agitation of the workpiece. In high pressure processing, a prior art method of agitation of the workpiece includes placing the workpiece on a holder connected by a drive shaft through a pressure chamber housing to a drive mechanism. The drive mechanism rotates the drive shaft and consequently rotates the holder to provide agitation of the workpiece. A second prior art method of agitation of the workpiece uses a magnetically coupled motor, where a magnetic field drives a rotor within the pressure chamber housing.  
           [0004]    Providing either the drive shaft through the pressure chamber housing or a magnetically coupled motor complicates design and fabrication of a high pressure processing system. Further, providing either the drive shaft through the pressure chamber housing or the magnetically coupled motor is expensive.  
           [0005]    What is needed is a method of agitating a workpiece in a pressure chamber that does not use a drive shaft through a pressure chamber housing and that does not use a magnetically coupled motor.  
           [0006]    What is needed is a method of agitating a workpiece in a pressure chamber that is more economical than using a drive shaft through a pressure chamber housing and that is more economical than using a magnetically coupled motor.  
         SUMMARY OF THE INVENTION  
         [0007]    An apparatus for agitating a workpiece in a high pressure environment of the present invention comprises a workpiece holder, a bearing, a pressure chamber housing, and a nozzle. The workpiece holder couples to the pressure chamber housing via the bearing. The nozzle couples to the pressure chamber housing. The workpiece holder comprises protrusions and a region for holding the workpiece. In operation a fluid exits the nozzle and impinges the protrusions of the workpiece holder causing the workpiece holder to rotate, which agitates the workpiece. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 illustrates the preferred agitation device of the present invention.  
         [0009]    [0009]FIG. 2 illustrates the preferred agitation device and a lower portion of a pressure chamber housing of the present invention.  
         [0010]    [0010]FIG. 3 illustrates the preferred agitation device and the pressure chamber housing of the present invention.  
         [0011]    [0011]FIG. 4 illustrates an alternative agitation device, an alternative pressure chamber, and a light sensing arrangement of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]    The preferred agitation device of the present invention is illustrated in FIG. 1. The preferred agitation device  10  comprises a rotatable workpiece holder  12  and a bearing (not shown). The workpiece holder  12  comprises a jagged edge  16  of protrusions  18 . The bearing couples the workpiece holder  12  to a pressure chamber housing (not shown). In operation, an injection nozzle impels a fluid against the protrusions of the jagged edge  16  causing the workpiece holder  12  to rotate on the bearing.  
         [0013]    Preferably, the workpiece holder  12  is configured to hold a semiconductor substrate. Preferably, the semiconductor substrate is a semiconductor wafer. Alternatively, the semiconductor substrate is a different semiconductor substrate such as a puck. Preferably, the workpiece holder  12  comprises holding clamps  20 , which hold the semiconductor substrate to the workpiece holder  12 . Preferably, the preferred agitation device  10  operates in a high pressure environment. More preferably, the preferred agitation device  10  operates in a supercritical environment.  
         [0014]    Preferably, the preferred agitation device  10  includes one or more sweeper blocks  21 , which agitate fluid below the preferred agitation device  10 . Alternatively, the preferred agitation device  10  does not include the sweeper blocks  21 . The preferred agitation device  10  includes retractable arms  23  so that a small workpiece can be clamped at a center of the preferred agitation device  10 . Alternatively, the preferred agitation device  10  does not include the retractable arms  23 .  
         [0015]    Preferably, the bearing allows the workpiece holder  14  to rotate relative to a plate located proximate to an inner diameter of the bearing. The plate is rotatably coupled to the workpiece holder  12  via the bearing and comprises first screw holes. The plate is preferably coupled to the pressure chamber housing by screws through the first screw holes. Preferably, the screws are installed through second screw holes  22  in the workpiece holder  12 . Preferably, the bearing is a chemically neutral bearing.  
         [0016]    Since the preferred agitation device  10  is driven by the injection nozzle, the preferred agitation device  10  provides agitation of a workpiece without using a rotatable shaft through the pressure chamber housing and without using a magnetically coupled motor. This simplifies a high pressure processing system that includes the preferred agitation device and makes the high pressure processing system more economical.  
         [0017]    The preferred agitation device  10  and a lower portion of the pressure chamber housing are illustrated in FIG. 2. The preferred agitation device comprises the rotateable workpiece holder  12  and the bearing  31 . The preferred agitation device  10  couples to the lower portion  30  of the pressure chamber housing. Bolt holes  32  in the lower portion  30  of the pressure chamber housing provide for coupling of an upper portion of the pressure chamber housing to the lower portion  30  by bolts. When bolted together, the lower portion  30  of the pressure chamber housing and the upper portion of the pressure chamber housing form a pressure chamber. Alternatively, the upper portion of the pressure chamber housing couples to the lower portion  30  via a clamp. Further alternatively, the upper portion couples to the lower portion via a hydraulic actuator.  
         [0018]    The preferred agitation device  10  and the pressure chamber are further illustrated in FIG. 3. The pressure chamber  40  includes the injection nozzle  42 . In operation, the injection nozzle impels the fluid against the protrusions  18  of the workpiece holder  12  causing the workpiece holder  12  to rotate. Alternatively, one or more additional injection nozzles are provided to impel the fluid against the protrusions  18 .  
         [0019]    An alternative agitation device, an alternative pressure chamber, and a rotation speed sensing arrangement of the present invention are illustrated in FIG. 4. The alternative agitation device  10 A comprises an alternative workpiece holder  12 A, an alternative bearing  31 A, and alternative protrusions  18 A of an alternative jagged edge  16 A. The alternative bearing  31 A couples the alternative workpiece holder  12 A to the alternative pressure chamber  40 A. The alternative bearing  31 A is selected from a group comprising a roller bearing, a ball bearing, and a journal bearing. In operation, an alternative injection nozzle  42 A impels the fluid against the alternative protrusions  18 A causing the alternative workpiece holder  12 A to rotate. The rotation of the alternative workpiece holder  12 A causes agitation of the workpiece.  
         [0020]    The rotation speed sensing arrangement  50  comprises a light source  52 , first and second sight glasses,  54  and  56 , and a light sensor  58 . The light source  52  emits light  60  which couples to the light source  58  via the first and second sight glasses,  54  and  56 . As the first alternative workpiece holder  12 A rotates, the alternative jagged edge  16 A interrupts the light  60  coupling to the light sensor  58  as each of the alternative protrusions  18  passes through the light  60 . Thus, the light sensor  58  senses each time one of the alternative protrusions  18 A passes through the light  60  as an interruption of the light  60 . Electronics coupled to the light sensor  58  count the interruptions of the light  60  to provide a measurement of rotation speed of the first alternative workpiece holder  12 A. Further, a feedback loop in the electronics can control the rotation speed by adjusting a flow rate in the first alternative injection nozzle  42 A.  
         [0021]    An alternative rotation speed sensing arrangement of the present invention places the light source  52  and the light sensor  58  within the alternative pressure chamber  40 A. Thus, the alternative rotation speed sensing arrangement does not use the first and second sight glasses,  54  and  56 .  
         [0022]    It will be readily apparent to one skilled in the art that other various modifications may be made to the preferred embodiment without departing from the spirit and scope of the invention as defined by the appended claims.