Abstract:
The invention relates to wafer processing apparatus having a chamber with an upper wall with gas supply openings formed therein which promote more even processing of a wafer. According to one embodiment of the invention, the openings are formed so as to create a circular flow path in the chamber. Another embodiment of the invention provides for the formation of the openings to create turbulent flow. A further embodiment of the invention provides for a nonuniform distribution of the openings so as to counteract a tendency for a flow over a wafer in one area to be higher than in another area.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1). Field of the Invention  
           [0002]    This invention relates to wafer processing apparatus.  
           [0003]    2). Discussion of Related Art  
           [0004]    [0004]FIG. 1 of the accompanying drawings illustrates apparatus  310 , according to the prior art, that is used for processing a wafer  312 . The wafer  312  is located on a susceptor  314 . A pump  316  is operated to create a vacuum within a chamber  318 . A processing gas flows through a gas supply line  320  into a manifold cavity  322 . The gas then flows through openings  324  in an upper wall  326  of the chamber  318 . The openings  324  in the upper wall  326  are all entirely vertical and uniformly spaced over the upper wall  326 . The gas then flows radially outwardly over the wafer  312  and into a channel  328  surrounding the susceptor  314 . The gas then exits through an exhaust line  330  which is connected on a left-hand side of the chamber  318 .  
           [0005]    Because the exhaust line  330  is connected to a location on a left-hand side of the chamber  318 , there is a tendency for flow over the wafer  312  to be more to the left. A higher flowrate results over the left of the wafer than over the right of the wafer  312 .  
           [0006]    [0006]FIG. 2 illustrates how the wafer  312  is processed. In the example described, a layer  332  is deposited on the wafer  312 . The layer  332  is thicker on the right-hand side  312  than on a left-hand side of the wafer  312  because of a higher flowrate over the left-hand side of the wafer  312 .  
         SUMMARY OF THE INVENTION  
         [0007]    This invention relates to a wafer processing apparatus of the kind including a processing chamber, a susceptor, a manifold, a gas supply line, and an exhaust line. The processing chamber is defined by a lower wall, an upper wall, and sidewalls extending from the lower wall to the upper wall. A wafer supply opening is formed in one of the walls for transferring the wafer into the chamber. The upper wall has a plurality of gas supply openings, each formed into an upper surface and out of a lower surface thereof. The susceptor is located in the chamber. A wafer can be located so that an upper surface of the wafer faces the upper wall. The manifold component is located on the chamber and, together with the upper surface of the upper wall, defines a manifold cavity. The gas supply line is connected to the manifold component. The exhaust line is connected to the chamber. A gas, when flowing in the gas supply line, flows from the gas supply line into the manifold cavity and from the manifold cavity through the gas supply openings into the chamber. The wafer is exposed to the gas. The gas flows from the chamber through the exhaust line.  
           [0008]    According to one aspect of the invention, lower ends of at least some of the openings extend at an angle other than at right angles relative to the upper surface of the wafer so that the gas, when leaving the openings flows at an angle other than at right angles relative to the upper surface. A flow pattern created by flow from the openings promotes even processing over the upper surface of the wafer.  
           [0009]    According to another aspect of the invention the gas supply openings are nonuniformily distributed over the upper wall so that the gas, after leaving the gas supply openings, create a flow pattern that promotes even processing over the upper surface of the wafer.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The invention is further described by way of examples with reference to the accompanying drawings wherein:  
         [0011]    [0011]FIG. 1 is a cross-sectional side view of a wafer processing apparatus according to the prior art;  
         [0012]    [0012]FIG. 2 is a cross-sectional side view illustrating deposition on a wafer utilizing apparatus of FIG. 1;  
         [0013]    [0013]FIG. 3 is a cross-sectional side view of wafer processing apparatus according to one embodiment of the invention;  
         [0014]    [0014]FIG. 4 is a cross-sectional side view illustrating a gas supply opening in an upper wall of a chamber of the apparatus of FIG. 4;  
         [0015]    [0015]FIG. 5 is a plan view of the upper wall;  
         [0016]    [0016]FIG. 6 is a plan view illustrating a flow pattern of gas as the gas enters the chamber;  
         [0017]    [0017]FIG. 7 illustrates a flow pattern over a wafer in the chamber;  
         [0018]    [0018]FIG. 8 is a cross-sectional side view of apparatus for processing wafer, according to another embodiment of the invention;  
         [0019]    [0019]FIG. 9 is a cross-sectional side view of an upper wall of a chamber of the apparatus of FIG. 8;  
         [0020]    [0020]FIG. 10 is a cross-sectional side view of wafer processing apparatus according to a further embodiment of the invention; and  
         [0021]    [0021]FIG. 11 is a plan view of an upper wall of a chamber of the apparatus of FIG. 10.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    [0022]FIG. 3 of the accompanying drawings illustrates wafer processing apparatus  10  according to an embodiment of the invention. The apparatus  10  includes a wafer processing chamber  12 , a susceptor  14 , a resistive heating element  16 , a manifold component  18 , a gas supply line  20 , an exhaust line  22 , a pump  24 , and a control valve  26 .  
         [0023]    The chamber  12  has a lower wall  28 , sidewalls  30 , an upper wall  32 , and a slitvalve  34 . The lower wall  28  forms a base of the chamber  12 . An opening  38  is formed in the lower wall  28  on a side thereof. The side walls  30  extend upwardly from edges of the lower wall  28 . A wafer supply opening  40  is formed in one of the sidewalls  30 . The supply opening  40  has dimensions which allow for a wafer to be inserted into the chamber  12  in a horizontal orientation. The slitvalve  34  is mounted to the chamber  12  for movement between a position wherein the slitvalve  34  closes the wafer supply opening  40  and a position wherein the slitvalve  34  is moved out of the way of the wafer supply opening  40  to allow for insertion of a wafer into the chamber  12 . The upper wall  32  is located on upper edges of the sidewalls  30 . A plurality of gas supply openings  42  are formed through the upper wall  32 .  
         [0024]    [0024]FIG. 4 illustrates one of the openings  42  in more detail. The opening  42  has an upper end  44  formed into an upper surface  46  of the upper wall  32 . The opening  42  extends vertically downwardly into the upper wall  46 , whereafter the opening  42  changes direction. A lower end  48  of the opening  42  extends out of a lower surface  50  of the upper wall  32 . The lower end  48  extends at an angle of, for example, about 45° relative to vertical. A gas can flow into the upper end  44  in a vertical direction  52  and exit from the lower end  48  in a direction  54  at an angle of, in the present example, about 45° relative to vertical.  
         [0025]    Referring again to FIG. 3, the upper wall  32  is formed with a peripheral edge  56 . The peripheral edge  56  extends upwardly from an edge of the upper surface  46 . The manifold component  18  is located on the peripheral edge  56 . A manifold cavity  60  is defined between the upper surface  46 , a lower surface  62  of the manifold component  18 , and inner surfaces of the peripheral edge  56 . A gas supply opening  64  is formed centrally in the manifold component  18 .  
         [0026]    The gas supply line  20  is connected to the manifold component  18 . A gas can flow through the gas supply line  20  into the manifold cavity  60 . The exhaust line  22  is connected to the opening  38  so that a gas can flow from the chamber  12  into the exhaust line  22 . The exhaust line  22  is connected to a pump  24  through a control valve  26 .  
         [0027]    The susceptor  14  is located centrally on an upper surface of a lower wall  28 . A channel  68  is formed concentrically around the susceptor  14 . The resistive heating element  16  is located within an upper portion of the susceptor  14 . The resistive heating element  16  is connected to a power supply (not shown). The power supply can be operated to supply current to the resistive heating element  16  to cause the resistive heating element  16  to heat up.  
         [0028]    [0028]FIG. 5 illustrates the upper wall  32  in more detail. The upper wall  32  is shown as viewed from above. The upper wall  32  has a center point  70 . The openings  42  are located around the center point  70 . Upper ends  44  of the openings are shown in solid lines and lower ends  48  of the openings are shown in hidden lines. The lower end  48  of a particular opening is displaced in an angular direction  72  relative to an upper end  44  thereof. As such one opening  42 A on one side of the center point  70  has a lower end  48  which is displaced in the angular direction  72  relative to the upper end  44  thereof and another opening  42 B, located on a side of the center point  70  opposing the opening  42 A, also has a lower end  48  which is displaced relative to the upper end  44  thereof in the angular direction  72  about the center point  70 .  
         [0029]    In use, the slitvalve  34  is moved into its open position. A wafer  74  is then transferred, on a blade that is moved by a robot, through the wafer supply opening  40  into the chamber  12 . The wafer  74  is located on an upper surface of the susceptor  14 . The blade carrying the wafer  74  into the chamber  12  is then removed through the wafer supply opening  40  and the slitvalve  34  is closed.  
         [0030]    A current is then provided through the resistive heater elements  16 , thereby heating the resistive heating elements  16 . The resistive heating element heats the susceptor  14 , which, in turn, heats the wafer  74 . The wafer  74  is heated to a required processing temperature.  
         [0031]    The pump  24  is operated and the control valve  26  opened. A vacuum is thereby created within the chamber  12 . Because of the vacuum in the chamber  12 , a gas is drawn through the gas supply line  20  into the manifold cavity  60 . The gas then flows through the openings  42  into the chamber  12 .  
         [0032]    [0032]FIG. 6 illustrates a flow pattern of the gas upon exit from lower ends of the openings  32 . Because of the angle at which the gas exits in the direction  54  shown in FIG. 4, and the relative positionings of the lower ends  48  relative to the upper ends  44  of the openings as shown in FIG. 5, circular flow is imparted on the gas. The gas initially moves in a direction  76 . The direction  76  is the same direction as the direction  72  shown in FIG. 5. The circular movement in the direction  76  counteracts a tendency of the gas to flow directly towards the exhaust line  22 . More even processing over an upper surface of the wafer  74  is thereby promoted. The gas flowing through the chamber  12  and over the wafer also has a radial component  78  as shown in FIG. 7. The gas flows from the central region of the wafer  74  radially outwardly towards a peripheral edge of the wafer  74  and then over the peripheral edge of the wafer  74  downwardly into the channel  68 .  
         [0033]    Gas accumulates in the channel  68  and then flows around the susceptor in directions  80  towards a location  82  where the exhaust line  22  is connected. The flow shown in FIGS. 6 and 7 is entirely laminar at all times.  
         [0034]    [0034]FIG. 8 illustrates the apparatus  10  having an upper wall  132 , according to another embodiment of the invention. The upper wall  132  has a plurality of openings  142  formed therein.  
         [0035]    As shown in FIG. 9, each opening  142  has an upper end  144  and a lower end  146 . A lower end  140  of a first opening  142  is displaced in a direction  148  relative to an upper end  144  thereof. The lower end  140  of a second opening  142  is displaced in a direction  150 , opposing the direction  152 , relative to an upper end  134  thereof. The opening  142 B is located adjacent the opening  142 A. An opening  142 C is located on a side of the opening  142 B opposing the opening  142 A. The opening  142 C has a lower end  140  which is displaced in the direction  150  relative to the upper end  144  thereof. Gases flow in directions  152  and  154  downwardly and towards one another out of lower ends  130  of the openings  142 A and  142 B respectively. Collision of the gases causes turbulent flow  156  in a substantially downward direction. In a similar manner gases from the opening  142 C and another opening (not shown) adjacent the opening  142 C collide to cause turbulent flow. The turbulent flow  156  counteracts a tendency of the gas to flow directly to an exhaust line  122 . Other aspects of the apparatus  10  shown in FIG. 8 are the same as the apparatus  10  of FIG. 3.  
         [0036]    [0036]FIG. 10 illustrates apparatus  10  having an upper wall  232  according to a further embodiment of the invention. A plurality of entirely vertical and straight openings  242  are formed through the upper wall  232 . The openings  242  in a right-hand half of the upper wall  232  are more densely populated than the openings  242 B in a left hand half of the other wall  232 . There are about twice as many ones of the openings  242 A in a given area of the right-hand half of the upper wall  232  than the openings  242 B over an equivalent area of the left hand half of the upper wall  232 . All the openings  242 A and  242 B have the same diameter.  
         [0037]    Because of more openings in the right-hand half of the upper wall  232 , more of the gas is supplied into a right-hand half of the chamber. The flowrate of the gas over a right-hand half of the wafer  274  is thereby increased. Should there be an equal number of vertical openings, the flowrate over the left hand half of the wafer  274  would be greater than the flowrate over the right-hand half of the wafer  274  because of the tendency of the flow to be towards the left over the wafer  274 . The increase in the number of openings in the right-hand half of the upper wall  232  thus counteracts the tendency for the flow to be higher over the left of the wafer  274 .  
         [0038]    [0038]FIG. 11 is a plan view illustrating the upper wall  232 . It can be seen that the openings  242 A are located over the entire right-hand half of the upper wall  242  and the openings  242 B are located over the entire left hand half of the upper wall  232 .  
         [0039]    While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive of the current invention, and that this invention is not restricted to the specific constructions and arrangements shown and described since modifications may occur to those ordinarily skilled in the art.