Patent Document

REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of provisional application 62/121,573, filed on Feb. 27, 2015, the entire contents of which are incorporated by this reference. 
     
    
     BACKGROUND 
       [0002]    Various systems are known within the semiconductor industry for handling wafers during the processing of fragile semi-conductor material. One type of devices is known as the Bernoulli wand typically used for high-temperature, touch-free applications. Bernoulli wands utilize jets of gas downward from the wand toward the wafer to create a region of low pressure above the wafer, therefore lifting it without damaging the wafer material. 
         [0003]    The design of the channel for the flow of the working gas within the wand is commonly created by multiple channels that intersect and are formed at angles to each other. The fabrication of these channels may create stress points within the quartz substrate at the intersection of channels. Stress points may also be formed in a single channel in any region where one or more sidewalls of a channel form a step, which is seen as an angle between two common surfaces. Upon the application of the working gas or upon experiencing a significant temperature change, these stress points may result in small fractures which may propagate and ultimately destroy the wand. Prior Art wands are typically used around 400 degrees C. to 1200 degrees C. 
         [0004]    What is needed is a Bernoulli wand construction that resists this failure mode. 
       BRIEF SUMMARY 
       [0005]    The present invention has several embodiments. One embodiment provides a Bernoulli wand useful for transporting semiconductor wafers during manufacturing of integrated circuits. These wands are especially useful for transporting or manipulating the wafers when the processing steps cause the wafer to have a high temperature. 
         [0006]    In some embodiments, the wand has top and bottom plates. The underside of the top plated contains several small gas orifices penetrating through the bottom plate emerging inside of a curved channel created in or on the upper surface of the bottom plate. In some embodiments, the small gas orifices have a diameter of 0.1-2.0 hundredths of an inch. 
         [0007]    In these or other embodiments, the curve as a path that is smoothly curved, continuous, and does not cross itself. In these or other embodiments, the wand comprises or consists essentially of a quartz material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an isometric view of a bottom plate of an embodiment of the invention showing a channel in the bottom plate and small gas orifices. 
           [0009]      FIG. 2  is a side view of the wand of an embodiment of the invention showing the top plate bonded to the bottom plate. 
           [0010]      FIG. 3  is a top view of the wand of an embodiment of the invention depicting bonded top and bottom plates and a smooth, continuous channel shown in covered relief. 
           [0011]      FIG. 4  is a top view of the wand, with bonded top and bottom plates, and a smooth continuous channel showing the direction of gas flow illustrated by vectors through the multiple small orifices in covered relief. 
           [0012]      FIG. 5  is the view of  FIG. 2  additionally showing a semiconductor wafer. 
           [0013]      FIG. 6  is the view of  FIG. 1  additionally showing a semiconductor wafer. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]      
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Component 
                 Reference number 
               
               
                   
                   
               
             
             
               
                   
                 Wand 
                 102 
               
               
                   
                 Top Plate 
                 104 
               
               
                   
                 Bottom Plate 
                 106 
               
               
                   
                 Channel 
                 108 
               
               
                   
                 Air Outlets 
                 110 
               
               
                   
                 Underside of Bottom Plate 
                 112 
               
               
                   
                 Air Inlet 
                 114 
               
               
                   
                 Semiconductor wafer 
                 116 
               
               
                   
                   
               
             
          
         
       
     
         [0015]      FIG. 1  shows a positive pressure Bernoulli-type wand  102  typically used in the processing of semiconductor material. In some embodiments, the device is made primarily of quartz. It has top plates  104  and bottom plates  106 . The plates are joined to form or contain a working gas flow channel  108  that has a smooth, continuously curving path.  FIG. 1  also shows several small openings  110 , and bottom plate  106  has underside  112 . Small openings  110  allow working gas to flow out of channel  108  through the bottom plate  106 . Small outlet orifices should be small enough to maintain a pressure difference of P 1  (inside wand)&gt;P 2  (atmosphere/air) in order to provide for sufficient mass flow rate to provide lift/suction of the wafer. Typically, the diameter of these holes is on the order of hundredths of inches to maintain an appropriate mass flow-rate. 
         [0016]      FIG. 2 , also, shows top and bottom plates  104  and  106  in a bonded configuration.  FIG. 2  also illustrates the underside  112  of bottom plate  106 , not directly shown. In  FIG. 2 , small openings  110  are not shown. 
         [0017]      FIG. 3  shows a top view of wand  102 . This view is looking down through the device. Channel  108  is shown in relief. Channel  108  is formed into or onto the surface of the bottom plate  106  such as by milling or other technique known to those of ordinary skill in the art. The surface of the bottom plate comprising channel  108  faces or bonds to top plate  104 . The working gas enters channel  108  through air inlet  114 . Alternatively, channel  108  is formed into or onto top plate  104  such as by milling or other technique known to those of ordinary skill in the art. In this alternative, the surface of the top plate containing channel  108  bonds to bottom plate  106 . In some embodiments, channel  108  is formed into or onto both top plate  104  and bottom plate  106 . 
         [0018]      FIG. 4  shows working gas flow is illustrated by vectors. Gas flows out of small orifices  110  and generates the Bernoulli effect. The indicated gas flow through small orifices  110  in underside  112  of bottom plate  106  is down upon the upper surface of an object beneath wand  102 . This flow of the working gas induces a vacuum above the surface of the object beneath wand  102 . Under normal atmospheric pressure, the vacuum above the object beneath wand  102  pulls the object toward wand  102  until it comes in close contact with underside  112 . The downward flow of the working gas (vectors in  FIG. 4 ) prevents the object from contacting wand  102 . This prevents damage to the object that would normally occur if the object contacted a tool. 
         [0019]      FIGS. 5 and 6  depict semiconductor  116  being manipulated by wand  102 .  FIG. 5  shows that semiconductor  116  approaches underside  112 , but does not contact it. 
         [0020]    Top and bottom plates  104  and  106 , shown in  FIG. 2  may be made of any material suited for use in the semiconductor reactor arena including; Quartz (SiO2), Silicon Carbide (SiC), Magnesium Oxide (MgO), Aluminum Oxide (Al2O3), Titanium Carbide (TiC). In some embodiments, the top and bottom plates  104  and  106  comprise quartz or consist essentially of quartz. 
         [0021]    The plates may be joined with any adhesive known for use in the semiconductor processing field Including materials comprising graphite, alumina, silica, magnesium oxide. In some embodiments, adhesives comprise ceramic or graphite. The plates may be joined with thermally worked frit comprising or consisting essentially of quartz, such as thermally worked solid intermediary quartz, glass, related ceramic, or epoxy. 
         [0022]    The plates may be joined using other methods commonly used to connect quartz in a heat process known to those in the semiconductor field. 
         [0023]    In some embodiments, the joint is a bond. A bond is an adhesive, cementing material, or fusible ingredient that combines or unites top plate  104  to bottom plate  106  into a rigid unit. 
         [0024]    The plates may be bonded using laser bonding, where the laser, such as a CO2 laser, is focused at the bond line allowing a weld seam to be created between the plates. Those of ordinary skill in the art will recognize that other bonding or heating techniques would suit this invention. 
         [0025]    This invention uses a smooth and continuously curved channel  108 , as shown in  FIGS. 1, 3, and 4 , within wand  102 . Channel  108  does not cross back upon or intersect with itself. And channel  108  has no sharp angles or no macroscopic sharp angles, as shown in  FIGS. 1, 3 and 4 . This smooth and continuous curving of channel  108  reduces potential stress points, which may otherwise occur at the intersection of two channels or in the region of a step of a sidewall within a channel. 
         [0026]    Without wishing to be bound by any theory, using a smooth continuous channel  108  allows wand  102  to be manufactured with fewer built-in stress-crack-initiation points. This may yield fewer stress cracks over time and may yield a more durable wand  102 . In prior art devices, discontinuous or sharply angled changes in the channel&#39;s path can create stress-crack-initiation points. These stress points may help to create or to propagate stress fractures during gas flow. 
       EXAMPLES 
       [0027]    This wand is made in a manner common to the current manufacturing methodology of Bernoulli wands in use in the semiconductor processing industry today. Two quartz plates, a top plate and bottom plate, are made to specifications common to wand manufacture in the semiconductor field. Therefore, they are made to fit commonly used semiconductor reactors. Channel  108  is created by milling a groove into either or both plates  104  and  106  before bonding them together. In this embodiment, channel  108  is milled or bonded with a channel width of 6.35 mm and an overall length of 470 mm. Channel width and length may vary according to the overall dimensions of the wand  102 . The plates are bonded together using thermally worked frit comprising or consisting essentially of quartz, glass, or related ceramic. The bonding of the two plates to each other may be done using epoxy, melted glass or quartz particles or other methods commonly used to bind quartz in a heat process known to those in semiconductor field. 
         [0028]    The creation of the continuous curved channel groove  108  in the plates  104  and  106  may be done by milling, grinding, drilling or other common methods used in the machining of quartz. This application may be applied to one or both plates that are part of wand  102 .

Technology Category: 7