1.  Field of the Invention
The present invention relates to a developing unit and a developing method for a substrate. 
2.  Description of the Related Art
In a photolithography process in semiconductor device fabrication processes, for example, resist coating treatment in which a resist solution is applied on a top surface of a wafer and a resist film is formed thereon, exposure processing in which the wafer is exposed in a pattern, developing treatment in which development is performed for the wafer after being exposed, and the like are performed in order, and thereby a predetermined circuit pattern is formed on the wafer. 
The aforementioned developing processing is normally performed in a developing unit.  The developing unit has a spin chuck for holding an undersurface of the wafer by suction and rotating the wafer, and a long thin developing solution supply nozzle moving in a predetermined direction above the wafer, with a plurality of supply ports of the same diameter being formed along a longitudinal direction thereof.  The wafer is kept rotated at a predetermined speed previously, and the developing solution supply nozzle is moved from one end above the wafer to a center portion while discharging a developing solution.  Subsequently, in a state in which the developing solution supply nozzle is stopped above the center portion of the wafer, it further continues to supply the developing solution, thereby performing solution heaping of the developing solution on an entire top surface of the wafer. 
In order to supply the developing solution onto the rotating wafer evenly within the wafer surface, it is necessary to decrease a supply amount to the center portion having a smaller supply area than a peripheral portion of the wafer.  In a conventional developing unit, however, a plurality of supply ports are designed to have the same diameter, and therefore a larger quantity of developing solution is supplied to the center portion of the wafer compared with the peripheral portion of the wafer. 
Meanwhile, since it is sufficient if the developing.  solution can be supplied to the entire surface of the wafer, the developing solution supply nozzle is conventionally moved to the center area above the wafer and is stopped there to discharge the developing solution to the rotating wafer.  However, if the developing solution supply nozzle is stopped above the wafer and continues to discharge the developing solution as it is, which causes more developing solution to be supplied to the wafer center portion compared with the wafer peripheral portion. 
The present invention is made in view of the above points, and its object is to balance the amount of developing solution supplied to a substrate within a substrate surface when developing treatment is performed for a substrate such as a wafer. 
In order to attain the above object, a developing unit of the present invention has a rotating device for rotating the substrate while holding the substrate, and a developing solution supply nozzle movable above the substrate in a horizontal direction and in a predetermined direction including a center of the substrate, for supplying a developing solution to the substrate, and the developing solution supply nozzle has a plurality of supply ports provided to be aligned in a direction forming a predetermined angle with the predetermined direction, and the supply ports include supply ports of which diameter sizes are different. 
Further, according to another aspect of the present invention, a developing method of the present invention has the steps of moving a developing solution supply nozzle from one end to the other end of the substrate along a horizontal direction and a predetermined direction above the rotating substrate, and supplying a developing solution to the substrate from the developing solution supply nozzle during the aforementioned movement, and when the developing solution supply nozzle moves from one end of the substrate to the other end, a rotational speed of the substrate is changed. 
By using the developing solution supply nozzle having the supply ports of different diameters, the flow rate of the developing solution discharged form each supply port is regulated, and thus the amount of the developing solution finally supplied onto the substrate can be made even within the substrate surface.  In concrete, the diameters of the supply ports corresponding to the portions with a comparatively large supply amount of the developing solution are made smaller, while the diameters of the support ports corresponding to the portions with less supply amount are made larger, whereby the amount of the developing solution supplied to the substrate surface is adjusted to be even.  The sizes of the supply ports of which diameters are changed, position, the number thereof and the like differ depending on developing treatment units, thus it is suitable to adopt the support ports individually corresponding to each apparatus.  Further, the predetermined angle of about 0xc2x0 to 30xc2x0 is suitable. 
According to the method of the present invention, the developing solution supply nozzle moves from one end of the substrate to the other end, thereby reducing the necessity for supplying the developing solution onto the substrate with the developing solution supply nozzle being stopped for a long period of time as conventionally, thus making it possible to supply the developing solution while it moves from the center to the other end.  Accordingly, the time, which is taken to supply the developing solution with the developing solution supply nozzle being stopped above the center of the substrate, is shortened, thus preventing a relatively large amount of developing solution from being supplied to the center portion of the substrate having a small supply area.  Further, if the rotational speed of the substrate is changed, for example, to a lower speed, more developing solution is supplied to the same portion on the substrate, and to the contrary, if it is changed to a higher speed, a smaller amount of the developing solution is supplied to the same portion, thus making it possible to change and control the supply amount of the developing solution.  Accordingly, the amount of the developing solution finally supplied on the substrate can be made even within the surface of the substrate.