Abstract:
A wedge-shaped nozzle for dispensing fluids onto a round surface is disclosed. The nozzle dispenses the fluid with a generally uniform volume of fluid per unit area of the round surface to achieve rapidly a uniform thickness of applied fluid on the round surface. The wedge-shaped nozzle has orifices of equal size disposed on its bottom through which the fluid is dispensed. The orifices are disposed along arcs, with increasing numbers of orifices on the arcs at greater and greater distances of the arcs from the apex of the wedge-shaped nozzle. The numbers of the orifices on each arc are proportional to the area of an annular region determined by the arcs.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the field of semiconductor integrated circuits. The invention is illustrated in an example with regard to a semiconductor integrated circuit wet processing method and apparatus, but it will be recognized by those of skill in other arts that the invention has a wider range of applicability. Merely by way of example, the invention can also be applied to the manufacture of raw wafers, disks and heads, flat panel displays, microelectronic masks, and other applications requiring high purity wet processing such as steps of rinsing, drying, and the like. The present invention generally relates to a nozzle and a method for dispensing process liquids onto a surface. More particularly, the present invention relates to a fluid dispense nozzle for dispensing fluids of photoresist developer chemicals, photoresist chemicals, cleaning and rinsing chemicals, etchant chemicals, or dielectric chemicals onto a rotating semiconductor substrate material. 
     Integrated circuits are typically constructed by depositing a series of individual layers of predetermined materials on a wafer shaped semiconductor substrate, or “wafer.” The individual layers of the integrated circuit are in turn produced by a series of manufacturing steps. For example, in forming an individual circuit layer on a wafer containing a previously formed circuit layer, an oxide, such as silicon dioxide, is deposited over the previously formed circuit layer to provide an insulating layer for the circuit. A pattern for the next circuit layer is then formed on the wafer using a radiation alterable material, known as photoresist. Two very common families of photoresists are phenol-formaldehyde polymers and polyisoprene polymers. 
     Photoresist materials are generally composed of a mixture of organic resins, sensitizers and solvents. Sensitizers are compounds, such as bio-aryldiazide and o-naphthaquinone-diazide, that undergo a chemical change upon exposure to radiant energy, such as visible and ultraviolet light resulting in an irradiated material having differing solvation characteristics with respect to various solvents than the nonirradiated material. Resins are used to provide mechanical strength to the photoresist and the solvents serve to lower the viscosity of the photoresist so that it can be uniformly applied to the surface of the wafers. 
     After a photoresist layer is applied to the wafer surface, the solvents are evaporated and the photoresist layer is hardened, usually by heat treating the wafer. The photoresist layer is then selectively irradiated by placing a radiation opaque mask containing a transparent portion defining the pattern for the next circuit layer over the photoresist layer and then exposing the photoresist layer to radiation. The photoresist layer is then exposed to a chemical, known as developer, in which either the irradiated or the nonirradiated photoresist is soluble and the photoresist is removed in the pattern defined by the mask, selectively exposing portions of the underlying insulating layer. Common developers are tetramethyl ammonium hydroxide, sodium hydroxide, xylene and Stoddard solvent. After development rinsing is performed with fluids such as water or n-Butylacetate. 
     The exposed portions of the insulating layer are then selectively removed using an etchant to expose corresponding sections of the underlying circuit layer. The photoresist must be resistant to the etchant, so as to limit the attack of the etchant to only the exposed portions of the insulating layer. 
     Alternatively, the exposed underlying layer(s) may be implanted with ions which do not penetrate the photoresist layer thereby selectively penetrating only those portions of the underlying layer not covered by the photoresist. The remaining photoresist is then stripped using either a solvent, or a strong oxidizer in the form of a liquid or a gas in the plasma state. The next layer is then deposited and the process is repeated until fabrication of the semiconductor device is complete. 
     Photoresist solution, developer solution and other process liquids are typically applied to the wafer using a spin coating technique in which the process liquid is sprayed on the surface of the wafer as the wafer is spun on a rotating chuck. The spinning of the wafer distributes the liquid over the surface of the material. In particular, when developer chemicals are applied to the surface, it is necessary to quickly and gently produce a deep puddle of developer on the wafer to ensure that the photoresist layer is dissolved uniformly in areas that are soluble in the developer. In a developing process, among other manufacturing processes for a semiconductor device, a developer should be uniformly applied to a resist film on a semiconductor wafer within a predetermined time. The reason is that the developing uniformity for the resist film is generally supposed to depend on the state of development, so that the development is subject to irregularity unless the developer is first uniformly supplied to the whole surface of the wafer. Conventionally, therefore, liquid coating nozzles of various types have been proposed. 
     U.S. Pat. No. 4,267,212 discloses a process for spin coating a semiconductor wafer uniformly with a coating solution such as a photographic emulsion by rotating the wafer at a first speed while simultaneously applying the coating solution through a circular nozzle at a radially moving position. Once the semiconductor wafer has been initially covered, the speed of rotation of the wafer is increased and rotation continues until a uniform coating has been obtained. A similar process having a stationary nozzle is disclosed in U.S. Pat. No. 3,695,928. 
     In each of the aforedescribed apparatuses and methods, the fluid coating material is dispensed in a column of fluid whose cross-section approximates a circle, either during wafer rotation or while the wafer is stationary. Wafer coating is achieved by building up a pool of the fluid coating material in the nature of a thick layer and spin casting a film thereof by accelerating the rotation of the wafer about its own center in order to remove the excess material and to leave a thin film coating therebehind. The amount of fluid coating material, such as photoresist, remaining on the wafer is known to be a very small fraction of the amount that is initially dispensed, approximately one part in one thousand. This results in a substantial material loss of unusable photoresist along with its attendant cost. In addition, this creation of a pool of the fluid coating material on the wafer surface can result in the formation of uneven films which might adversely effect subsequent wafer processing. 
     Very specifically, in the prior art, a variety of devices, called nozzles, are used to apply fluids to a wafer surface. In FIG. 1, a simple spout nozzle  5  is depicted with an orifice  10  at the end of a spout attached to a fluid supply tube  15 . The nozzle is positioned above the center of a rotating wafer  20  shown in the plan view. 
     FIG. 2 depicts a side view of this device dispensing fluid  31  onto the wafer  20  supported by a spin chuck  33  connected to a motor (not shown) that rotates the chuck and thus the wafer. In this nozzle  5 , the fluid reaches the wafer center  35  first and only gradually is dispersed by centrifugal force to the perimeter  37  of the wafer. In fact, even after distribution to the perimeter, a greater amount of developer remains near the center  35  as shown in FIG.  3 . 
     FIG. 4 depicts a cross-sectional view along a longitudinal axis of another version of the prior art, known as a block nozzle  55 , which tries to solve some of the difficulties of the spout nozzle. In this case, the block nozzle  55  is a rectangular vessel  40  with an interior  42  serving as a liquid reservoir. The nozzle&#39;s top surface  44  has two inlet fittings  46 A, B for attachment to a fluid supply tube  48 A, B, a support  41  for connection to an external apparatus not depicted, and an outlet fitting  43  for attachment to a gas outlet tube. The bottom  45  of the nozzle has a portion downwardly projecting called a nozzle tip  47  with a multiplicity of openings or orifices, e.g.,  49 , out of which the fluid is dispensed. 
     FIG. 5 depicts a transverse cross-section of the block nozzle  55 . The figure shows the orifices, e.g.  49 , in fluid communication with the vessel&#39;s interior  42  through a slit  51  in the nozzle tip  47  and small passages  53  in the bottom wall of the interior. The nozzle tip and its orifices are arranged on the nozzle in a row approximately the diameter of the wafer, and each of the orifices have similar opening areas. 
     FIG. 6, in bottom plan view looking upwards from a rotating wafer  20  below the block nozzle  55 , shows the block nozzle with its row of orifices  49 A-I. A variation of the block nozzle is the partial-block nozzle  57  depicted in bottom plan view looking upwards from a rotating wafer  20  in FIG.  7 . The difference between the block and partial-block nozzle is apparent by comparison to the wafer diameter. The partial-block nozzle is only about half the length of the block nozzle, and when placed over the wafer, extends about one wafer radial length from the center to the perimeter  59 . The cross-sectional views of the partial-block nozzle  57 , along both its longitudinal axis and its transverse axis, would be similar to the cross-sectional views of the block nozzle  55  shown in FIG.  4  and FIG.  5 . 
     Unlike the spout nozzle, the block nozzle and partial-block nozzle dispense fluid near the perimeter  59  of the wafer and at points between the perimeter and center  52  at the same time that those two nozzles dispense fluid to the center of the wafer, thereby solving the most extreme difficulty of the spout nozzle. However, despite the improvement in uniform distribution of the dispensed fluid on the wafer, substantial non-uniformity persists. 
     To understand the cause of the persisting non-uniformity, suppose the wafer is 8 inches in diameter, suppose that the nozzle is of the partial-block design, and suppose that there are four equally-spaced orifices of equal opening area. Suppose further that in FIG. 7 the nozzle is placed so that one end orifice  54 E overlies the center of the wafer  52 , while the other end orifice  54 A overlies a wafer region just inside the wafer&#39;s perimeter  59 . The first end orifice dispenses fluid onto the wafer&#39;s center while each of the other three orifices dispenses fluid onto a separate annulus. 
     FIG. 8 shows a circular region  60  of one inch radius and three concentric annular regions  62 ,  64  and  66  of inner and outer radii, respectively, of 1″ and 2″, 2″ and 3″, and 3″ and 4″. The area of each annulus is π (r 2   outer −r 2   inner ) and, accordingly, FIG. 9 shows the area  61  of the 1″ circle  68  and the three successive annuluses as a function of the radius  63  of the circle and the outer radius of the three annuluses. From FIG. 9 it is evident that the area of the circle is {fraction (1/7)}th of the outer-most annulus. Accordingly, assuming approximately equal fluid flow per unit time through the opening of each orifice, the fluid dispensed from the central orifice  54 E in FIG. 7 is spread over an area only {fraction (1/7)}th that of the fluid dispensed from the orifice nearest the wafer&#39;s perimeter  54 A. As a result, assuming for simplicity fluid dispensed over the circle  68  remains in the circle and fluid dispensed over the perimeter annulus  66  remains there, serious non-uniformity with a radial dependence exists because the average thickness of the dispensed fluid over the center circle is seven times that over the perimeter annulus. This non-uniformity will be further exaggerated as the semiconductor industry over time employs wafers of ever-increasing diameter. As a result, over-development can occur in the wafer center compared to the wafer perimeter. 
     The timing of the application of developer fluid to the wafer can also affect the uniformity of the results of development. For example, chemically amplified photoresists tend to develop much more rapidly than non-chemically amplified photoresists. The speed of chemically amplified photoresists can be as little as one second. That time is often less than the time required to apply the developing solution to the entire wafer surface. Consequently, if some portions of the wafer are covered with developer earlier than other portions, the developing process will proceed to a farther stage at those earlier portions in a given amount of time. 
     In the use of the partial-block design described in FIG. 7, the center circle  68  is covered with at least some fluid at the onset of fluid dispensing, while the perimeter annulus  66  receives fluid along its full extent only at the end of one revolution of the wafer spun by the chuck. Accordingly, if the fluid is developer, development begins much sooner on the center circle than at many portions of the wafer perimeter. That development might even run to completion much sooner at the central circle than in the perimeter annulus in the event chemically-amplified photoresists are used, for the reasons discussed above. 
     Accordingly, there is a need for a nozzle which applies fluid uniformly per unit wafer area to wafer portions of increasing distance from the center to produce more uniform thickness of the dispensed fluid over the whole wafer area and therefore more uniform photoresist layers and more uniform development processes. 
     Moreover, there is a need for more rapid application of the wafer fluid to wafer regions distant from the wafer center. That more rapid application will produce more uniform development times from the beginning of fluid dispensing independent of the distance of the wafer region from the wafer center. 
     Accordingly, there is an unsolved need for an apparatus which minimizes consumption of the coating material, such as photoresist, during spin casting and the like, as well as providing a more uniform and more rapidly applied thin film coating on semiconductor wafers during the fabrication of integrated circuits and other electronic components therefrom in the semiconductor industry. 
     Thus, it is apparent that a need exists for an improved nozzle for spin dispensing apparatuses which overcomes, among others, the above-discussed problems so as to produce a more uniform and more rapidly applied layer of process liquid over the surface of the wafer. 
     SUMMARY OF THE INVENTION 
     The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiments described below relate to a wedge-shaped nozzle for dispensing fluids onto a round surface with a generally uniform volume of fluid per unit area of the round surface to achieve rapidly a uniform thickness of applied fluid on the round surface. The wedge-shaped nozzle has orifices of equal size disposed on its bottom through which the fluid is dispensed. The orifices are disposed along arcs, with increasing numbers of orifices on the arcs at greater and greater distances of the arcs from the apex of the wedge-shaped nozzle. The numbers of the orifices on each arc are proportional to the area of an annular region determined by the arcs. 
     Accordingly, the present invention provides an improved nozzle that allows process liquid to be dispensed more uniformly on a rotating surface, which provides for a more uniform distribution of the process liquid on the surface of the layer, while requiring less process liquid and slower rotational speed to ensure full coverage of the surface. 
     One object of the present invention is to provide an apparatus for applying a thin layer of a fluid material such as photoresist or developer fluid on the surface of a wafer which eliminates pooling of the material. 
     Another object of the present invention is to provide an apparatus for applying a layer of a fluid material such as a photoresist or developer fluid on the surface of a wafer which reduces the amount of the material required for a given coating thickness. 
     Another object of the present invention is to provide an apparatus for applying a layer of a fluid material such as a photoresist or developer fluid on the surface of a wafer which enhances uniformity of coating thickness. 
     Another object of the present invention is to provide an apparatus which renders uniformity of fluid material application to a wafer more insensitive to greater and greater wafer diameters. 
     Another object of the present invention is to provide a photoresist application or developing treatment apparatus making it possible to form a resist pattern having a very small measurement error range and high precision and improve the yield rate of the resist pattern. 
     Another object of the invention is to provide a method for photoresist application or developing treatment making it possible to form a resist pattern having a very small measurement error range and high precision and improve the yield rate of the resist pattern. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinbefore. These and other details, objects, and advantages of the invention will become apparent as the following detailed description of the present preferred embodiment thereof proceeds. 
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a bottom plan view of a spout nozzle looking upwards from a rotating wafer disposed below the spout nozzle and showing its orifice. 
     FIG. 2 is a side view of the spout nozzle. 
     FIG. 3 is a side view of the non-uniform distribution of fluid material on a wafer. 
     FIG. 4 is a longitudinal cross-sectional view of a prior art block nozzle. 
     FIG. 5 is a transverse cross-section of the prior art block nozzle. 
     FIG. 6 is a bottom plan view of the prior art block nozzle showing its orifices looking upwards from a rotating wafer. 
     FIG. 7 is a bottom plan view of a prior art partial-block nozzle looking upwards from a rotating wafer disposed below the partial-block nozzle and showing its orifices. 
     FIG. 8 is a top plan view of concentric annular regions of a wafer receiving dispensed fluid from the prior art partial-block nozzle. 
     FIG. 9 is a graph depicting the areas of the circular region and annular regions of the wafer as a function of the radii of the regions. 
     FIG. 10 is a perspective view of a first embodiment of the invention called a half-block nozzle. 
     FIG. 11 is a longitudinal cross-sectional view of the half-block nozzle. 
     FIG. 12 is a transverse cross-sectional view of the half-block nozzle. 
     FIG. 13 is a bottom plan view of the half-block nozzle looking upwards from a wafer disposed below the half-block nozzle and showing its orifices. 
     FIG. 14 is a bottom plan view of an alternative embodiment of the half-block nozzle showing concentric annuluses used for measuring fluid flow. 
     FIG. 15 is a bottom plan view of a second embodiment of the invention called the full-block (even) nozzle looking upwards from a wafer disposed below the full-block nozzle and showing its orifices. 
     FIG. 16 is a bottom plan view of an alternative embodiment of the full-block (even) nozzle showing concentric annuluses used for measuring fluid flow. 
     FIG. 17 is a bottom plan view of a third embodiment of the invention called the full-block (odd) nozzle looking upwards from a wafer disposed below the full-block nozzle and showing its orifices. 
     FIG. 18 is a bottom plan view of an alternative embodiment of the full-block (odd) nozzle showing concentric annuluses used for measuring fluid flow. 
     FIG. 19 is a perspective view of the fourth and preferred embodiment of the invention called a wedge nozzle. 
     FIG. 20 is a cross-sectional view of the wedge nozzle along an axis connecting the middle side edge and a point on the perimeter edge. 
     FIG. 21 is a transverse cross-section of the wedge nozzle. 
     FIG. 22 is a bottom plan view of the wedge nozzle, looking upward from a wafer disposed below the wedge nozzle and showing its orifices. 
     FIG. 23 is a bottom plan view of an alternative view of the wedge nozzle and more preferable embodiment of the invention showing concentric annuluses used for measuring fluid flow. 
     FIG. 24 is a perspective view of the fifth embodiment of the invention called a general-purpose (full) nozzle. 
     FIG. 25 is a cross-sectional view of the general-purpose (full) nozzle. 
     FIG. 26 is a transverse cross-section of the general-purpose (full) nozzle. 
     FIG. 27 is a bottom plan view of the general-purpose (full) nozzle, looking upward from a wafer disposed below the general-purpose (full) nozzle and showing its orifices. 
     FIG. 28 is a bottom plan view of an alternative embodiment of the general-purpose (full) nozzle showing concentric annuluses used for measuring fluid flow. 
     FIG. 29 is a bottom plan view of the alternative embodiment of the general-purpose (full) nozzle showing concentric annuluses used for measuring fluid flow for the case where a bottom subregion contains the middle point. 
     FIG. 30 is a bottom plan view of the sixth embodiment of the invention, called a general-purpose (half) nozzle, looking upward from a wafer disposed below the general-purpose (half) nozzle and showing its orifices. 
     FIG. 31 is a bottom plan view of an alternative embodiment of the general-purpose (half) nozzle showing concentric annuluses used for measuring fluid flow. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 10 depicts a perspective view of a first embodiment of the invention known as a half-block nozzle  70 . This embodiment is a generally rectangular vessel  72  with a longitudinal axis  74 , a total surface and a generally rectangular top surface  76 . Of course variations in this general shape will be readily apparent to those of ordinary skill in the art. 
     FIG. 11 depicts a cross-sectional view along the longitudinal axis  74  and perpendicular to the top surface  76  of this embodiment of the invention showing the interior  78  serving as a liquid reservoir. The half-block nozzle&#39;s top surface  76  has one or more inlet fittings  71  A, B for attachment to a fluid supply tube  73 A, B, a support  75  for connection to an external apparatus (not depicted) to support the nozzle, and an outlet fitting  77  for attachment to a gas outlet tube. Nevertheless, it will be apparent to those of ordinary skill in the art that these items shown on the top surface may or may not be present in the numbers, or in the locations on the nozzle, or in fact may be entirely absent. The bottom of the nozzle has a portion downwardly projecting called a nozzle tip  79  with a multiplicity of openings or orifices, e.g.,  81 , out of which the fluid is dispensed. Again, it will be apparent to those of ordinary skill in the art that the orifices might be disposed on a bottom that has no nozzle tip. 
     FIG. 12 depicts a transverse cross-section of the half-block nozzle  70 . The figure shows one of the orifices  81  in fluid communication with the vessel&#39;s interior  78  through a slit  83  in the nozzle tip  79  and a small passage  85  in the bottom wall of the interior. The nozzle tip and its orifices are arranged on the nozzle in a row whose length is approximately half the diameter of the wafer. 
     FIG. 13, in bottom plan view looking upwards from a rotating wafer  20  below the half-block nozzle  70 , shows the half-block nozzle with its row of orifices  81 A-D. In this view and this orientation of the nozzle with respect to the wafer, the orifices face the wafer sufficiently to allow fluid dispensed from the orifices to contact the wafer surface with minimal disturbance of the desired dispensing process. Although the orifices  81 A-D are depicted in FIG. 13 as being generally co-planar, circular in shape, and equidistant from each other in center-to-center distance, it will be apparent to those of ordinary skill in the art that the bottom may not be planar, the nozzle tip bottom ends in which the orifices are openings may not be co-planar, that the orifice centers  88 A-D might not be equidistant from each other, and that the orifice shapes might not be planar or two-dimensional and, even if two-dimensional and planar, might be semi-circular, elliptical, square or hexagonal in shape or of some other shape altogether. The half-block nozzle  70 , when placed over the wafer  20 , extends about one wafer radial length from the wafer center  86  to the wafer perimeter  87 . It will be apparent to one of skill in the art that the center of the one end orifice  88 A might be placed substantially overlying the wafer center  86 . 
     The central orifice  81  A is the orifice at one end of the row of orifices, i.e., the orifice closest to one of the two opposite side surfaces  82 A, B depicted in FIGS. 10 and 11 and called the first side surface  82 B. The characteristics of the nozzle are selected so that the volume of fluid flow per unit time through a given orifice exceeds, or is at least substantially equal to, the volume of fluid flow per unit time through any other orifice closer to the central orifice  81  A than the given orifice. As depicted in FIG. 13, the areas of the circular orifices increase along the row beginning with the central orifice. The increasing orifice areas is one nozzle characteristic that can produce the result of generally increasing, or non-decreasing, volume of fluid flow just described. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages, can produce pressure, viscosity and other physical effects with the same result. 
     More particularly, this embodiment can be employed so that the first side surface  82 B is that one of the two opposite side surfaces closest to the center  86  of the wafer. So utilized, the half-block nozzle provides greater uniformity of dispensed fluid on the wafer than the prior art by providing greater amounts of fluid into annular regions of the wafer with greater area. 
     An alternative version of this embodiment of the half-block nozzle provides an even closer match between the amount of fluid dispensed onto the annular regions of the wafer and the area of those regions. The extent to which the desired uniform dispensing of fluid onto a wafer results can be measured by defining concentric annuluses using physical distances determined by the structure of the nozzle. FIG. 14 depicts the half-block nozzle  72  again, but this time with concentric annuluses  90 A-C drawn. In this version, although depicted as circles with equidistant centers e.g.  88 C,D, it will be appreciated by those of skill in the art that more generally, the orifices  81 C are merely two-dimensional with a variety of possible non-circular shapes and have an approximate center, but may not have equidistant centers. 
     The center of the concentric annuluses is an end point  94 . The end point is a point on the bottom surface lying anywhere between the center of the central orifice  81 A and the linear intersection  96  of the bottom and the first side surface, preferably along a line  98  connecting the center of the central circle and the center of that linear intersection. 
     To assist in defining the concentric annuluses, the halfway points  91 A,  91 B between the centers of adjacent orifices, e.g.  88 B,  88 C,  88 D are employed, whether or not those halfway points are points within, on, or outside the nozzle. To further assist the defining of the concentric annuluses, a flow circle with a perimeter  93  is defined by a center at the end point  94  and by a radius at least substantially equal in length to the distance from the end point to the furthest possible point  95  or points from the end point yet lying on an orifice (that orifice being called a perimeter orifice  81 D). Except for the outermost concentric annulus or perimeter annulus  90 C, the concentric annuluses are defined as annuluses within the flow circle, having centers at the end point and having inner  100  and outer  102  radiuses (one set of which is depicted), in the plane of the flow circle, defined as the distances, respectively, in length equal to the distances from the end point to two successive halfway points  91 A,  91 B. The outermost concentric annulus is defined in the same way except that its outer perimeter is not defined by an outer radius but by the perimeter  93  of the flow circle. 
     Finally, in the middle of, and within, the flow circle and inside the concentric annuluses is a central circle  104  corresponding to the central orifice  81 A. The central circle is defined by a center at the end point  94  and a radius (not depicted), in the plane of the flow circle, in length equal to the distance from the end point to the halfway point  91 C closest to the end point. 
     Each of the concentric annuluses corresponds to an orifice, the perimeter annulus  90 C corresponding to the perimeter orifice  81 D and the other concentric annuluses corresponding to the orifice between the two halfway points which define the radii of these other concentric annuluses. For example concentric annulus  90 B corresponds to orifice  81 C. 
     The measurement of uniform dispensing of fluid onto a wafer is accomplished by measuring the volume of fluid flow per unit time through each orifice and comparing that volume to the area of the corresponding concentric annulus, or, in the case of the central orifice, to the area of the central circle. The areas of the orifices can be selected by methods well known in the art to produce a volume of fluid flow per unit time dispensed through each orifice proportional to the area of the corresponding concentric annulus or corresponding central circle, all with the same proportionality constant. The areas of the orifices are one nozzle characteristic that can produce the proportional variation in, and affect, the volume of fluid flow just described. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages, can produce pressure, viscosity and other physical effects with the same proportional variation. 
     A second embodiment of the invention, called the full block (even) nozzle, has the same perspective view, cross-sectional view along the longitudinal axis and transverse cross-sectional view as the half-block nozzle shown in FIGS. 10,  11  and  12 . However, the nozzle tip and its orifices, even in number, are arranged on the nozzle in a row whose length is approximately the diameter of the wafer. One of the pairs of side surfaces depicted in FIG. 11 as  82 A,B comprises a first side surface  1118 B and a second side surface  118 A. 
     FIG. 15, in bottom plan view looking upwards from a rotating wafer  20  below the nozzle, shows the full-block (even) nozzle  110  with its row of orifices  111 A-H. In this view and this orientation of the nozzle with respect to the wafer, the orifices face the wafer sufficiently to allow fluid dispensed from the orifices to contact the wafer surface with minimal disturbance of the desired dispensing process. Although the orifices  111 A-H are depicted in FIG. 15 as being generally co-planar, circular in shape and equidistant from each other in center-to-center distance, it will be apparent to those of ordinary skill in the art that the bottom may not be planar, the nozzle tip bottom ends in which the orifices are openings may not be co-planar, that the orifice centers  113  might not be equidistant from each other, and that the orifice shapes might not be planar or two-dimensional and, even if two-dimensional and planar, might be semi-circular, elliptical, square or hexagonal in shape or of some other shape altogether. The nozzle  110 , when placed over the wafer  20 , extends about one wafer diameter between opposite points on the perimeter of the wafer. 
     For measurement convenience, a middle point  115  is defined as the point halfway between the middle two members  111 D,  111 E of the row of orifices. This middle point may be a point within, on or outside the nozzle, depending upon the exact geometry of the bottom of the nozzle. The characteristics of the nozzle are selected so that the volume of fluid flow per unit time through a given orifice exceeds, or is at least substantially equal to, the volume of fluid flow per unit time through any other orifice closer to the middle point  115  than the given orifice. As depicted in FIG. 15, the diameters of the circular orifices increase along the row beginning with the middle point. The increasing orifice diameter is one nozzle characteristic that can produce the result of generally increasing, or non-decreasing, volume of fluid flow just described. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages, can produce pressure, viscosity and other physical effects with the same result. 
     More particularly, this embodiment can be employed so that the middle point  115  lies approximately over the center of the wafer (not depicted). So utilized, this embodiment provides greater uniformity of dispensed fluid on the wafer than the prior art by providing greater amounts of fluid into annular regions of the wafer with greater area. 
     An alternative version of this embodiment of the invention provides an even closer match between the amount of fluid dispensed onto the annular regions of the wafer and the area of those regions. The extent to which the desired uniform dispensing of fluid onto a wafer results can be measured by defining concentric annuluses using physical distances determined by the structure of the nozzle. FIG. 16 depicts the full-block (even) nozzle  110  again, but this time with concentric annuluses drawn. In this version, although depicted as circles with equidistant centers, e.g.  112 A,  112 B,  112 C, it will be apparent to those of skill in the art that more generally the orifices  111 A-F are merely two-dimensional with a variety of possible non-circular shapes and have an approximate center but may not have equidistant centers. The center of the concentric annuluses is the middle point. 
     One-half of the row of orifices  111 A,  111 B,  111 C, a half on one side of the middle point  115 , is referred to as the half row, and that side is the side closest to the first side surface  118 B. The two perimeter orifices  111 F,  111 A comprise the two orifices furthest from the first side surface  118 B and the second side surface  118 A, respectively. The orifices are disposed in pairs, e.g.  111 B and  111 E, on opposite sides of the middle point  115  so that the center of each orifice in a pair, e.g.  112 B,  112 D is at a substantially equal distance from the middle point  115 , each orifice in a pair being a partner of the other orifice in that pair. 
     To assist in defining the concentric annuluses, the halfway points  120 A,  120 B between the centers of adjacent orifices, e.g.  111 A,  111 B in the half row are employed, whether or not those halfway points are points within, on, or outside the nozzle. To further assist the defining of the concentric annuluses, a flow circle with a perimeter  122  is defined by a center at the middle point  115  and by a radius at least substantially equal in length to the distance from the middle point to one of the points the furthest  190  from the middle point lying on the perimeters of the perimeter orifices  111 A,  111 F. Except for the outermost concentric annulus or perimeter annulus  191 , the concentric annuluses are defined as annuluses within the flow circle, having centers at the middle point and having inner and outer radiuses  124 ,  126 , in the plane of the flow circle, defined as the distances, respectively, in length equal to the distances from the middle point to two successive halfway points  120 B,  120 A. The outermost concentric annulus is defined in the same way except that its outer perimeter is not defined by an outer radius but by the perimeter  122  of the flow circle. 
     Finally, in the middle of, and within, the flow circle and inside the concentric annuluses is a middle circle  128 . The middle circle is defined by a center at the middle point  115  and a radius  124 , in the plane of the flow circle, in length equal to the distance from the middle point to the halfway point  120 B closest to the middle point. 
     Each of the concentric annuluses corresponds to an orifice, the perimeter annulus  191  corresponding to the perimeter orifice  111 A in the half row and the other concentric annuluses corresponding to the orifice between the two halfway points which define the radii of these other concentric annuluses. For example concentric annulus  121  corresponds to orifice  111 B. 
     The measurement of uniform dispensing of fluid onto a wafer is accomplished by measuring the volume of fluid flow per unit time through each orifice and its partner and comparing that volume to the area of the corresponding concentric annulus, or, in the case of the two orifices closest to the middle point, to the area of the middle circle. The areas of the orifices can be selected by methods well known in the art to produce a volume of fluid flow per unit time dispensed in the aggregate through each orifice (other than the two orifices closest to the middle point) and its partner proportional to the area of the corresponding concentric annulus, all with the same proportionality constant, and dispensed in the aggregate through the two orifices closest to the middle part proportional to the area of the middle circle with such proportionality constant. The areas of the orifices are one nozzle characteristic that can produce the proportional variation in, and affect, the volume of fluid flow just described. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages, can produce pressure, viscosity and other physical effects with the same proportional variation. 
     A third embodiment of the invention, called the full block (odd) nozzle, has the same perspective view, cross-sectional view along the longitudinal axis and transverse cross-sectional view as the half-block nozzle shown in FIGS. 10,  11  and  12 . However, the nozzle tip and its orifices, odd in number, are arranged on the nozzle in a row whose length is approximately the diameter of the wafer. One of the pairs of side surfaces depicted in FIG. 11 as  82 A,B comprises a first side surface  139 B and a second side surface  139 A. 
     FIG. 17, in bottom plan view looking upwards from a rotating wafer below the nozzle, shows the full-block (odd) nozzle  130  with its row of orifices  131 A-G. In this view and this orientation of the nozzle with respect to the wafer, the orifices face the wafer sufficiently to allow fluid dispensed from the orifices to contact the wafer surface with minimal disturbance of the desired dispensing process. Although the orifices  131 A-G are depicted in FIG. 16 as being generally co-planar, circular in shape and equidistant from each other in center-to-center distance, it will be apparent to those of ordinary skill in the art that the bottom may not be planar, the nozzle tip bottom ends in which the orifices are openings may not be co-planar, that the orifice centers  133  might not be equidistant from each other, and that the orifice shapes might not be planar or two-dimensional and, even if two-dimensional and planar, might be semi-circular, elliptical, square or hexagonal in shape or of some other shape altogether. The nozzle  130 , when placed over the wafer  20 , extends about one wafer diameter between opposite points on the perimeter of the wafer. 
     For measurement convenience, a middle orifice  131 D is defined as the middle member of the row of orifices. The characteristics of the nozzle are selected so that the volume of fluid flow per unit time through a given orifice exceeds, or is at least substantially equal to, the volume of fluid flow per unit time through any other orifice closer to the middle orifice  115  than the given orifice. As depicted in FIG. 17, the diameters of the circular orifices increase along the row beginning with the middle orifice. The increasing orifice diameter is one nozzle characteristic that can produce the result of generally increasing, or nondecreasing, volume of fluid flow just described. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages, can produce pressure, viscosity and other physical effects with the same result. 
     More particularly, this embodiment can be employed so that the middle orifice  131 D lies approximately over the center of the wafer (not depicted). So utilized, this embodiment provides greater uniformity of dispensed fluid on the wafer than the prior art by providing greater amounts of fluid into annular regions of the wafer with greater area. 
     An alternative version of this embodiment of the invention provides an even closer match between the amount of fluid dispensed onto the annular regions of the wafer and the area of those regions. The extent to which the desired uniform dispensing of fluid onto a wafer results can be measured by defining concentric annuluses using physical distances determined by the structure of the nozzle. FIG. 18 depicts the full-block (odd) nozzle  130  again, but this time with concentric annuluses drawn. In this version, although depicted as circles with equidistant centers, e.g.,  131 G,  131 F,  131 E, it will be apparent to those of skill in the art that more generally the orifices  131 A-G are merely two-dimensional with a variety of possible non-circular shapes and have an approximate center but may not have equidistant centers. The center of the concentric annuluses is the center  137  of middle orifice  131 D. 
     The middle orifice  131 D, together with one-half  131 E, F, G of the row of other orifices, a half on one side of the middle orifice, is referred to as the half row, and that side is the side closest to the first side surface  139 B. The two perimeter orifices  131 A,  131 G comprise the two orifices furthest from the first side surface  139 B and the second side surface  139 A, respectively. The orifices other than the middle orifice are disposed in pairs on opposite sides of the middle orifice  131 D so that the center of each orifice in a pair, e.g.,  132 A, B is at a substantially equal distance from the center  137  of the middle orifice, each orifice in a pair being a partner of the other orifice in that pair. 
     To assist in defining the concentric annuluses, the halfway points, e.g.,  134 A, B between the centers of adjacent orifices in the half row are employed, whether or not those halfway points are points within, on, or outside the nozzle. To further assist the defining of the concentric annuluses, a flow circle with a perimeter  136  is defined by a center at the center  137  of the middle orifice and by a radius at least substantially equal in length to the distance from the center of the middle orifice to one of the points the furthest  138  from such center lying on the perimeters of the perimeter orifices  131 G,  131 A. Except for the outermost concentric annulus or perimeter annulus  140 , the concentric annuluses are defined as annuluses within the flow circle, having centers at the center  137  of the middle orifice and having inner and outer radiuses, e.g.,  142 A, B, in the plane of the flow circle, defined as the distances, respectively, in length equal to the distances from the center of the middle orifice to two successive halfway points  134 B, A. The outermost concentric annulus is defined in the same way except that its outer perimeter is not defined by an outer radius but by the perimeter  136  of the flow circle. 
     Finally, in the middle of, and within, the flow circle and inside the concentric annuluses is a middle circle  144 . The middle circle is defined by a center at the center  137  of the middle orifice and a radius, in the plane of the flow circle, in length equal to the distance from the center of the middle orifice to the halfway point  134 C closest to the middle orifice. 
     Each of the concentric annuluses corresponds to an orifice, the perimeter annulus  140  corresponding to the perimeter orifice  131 G in the half row and the other concentric annuluses corresponding to the orifice between the two halfway points which define the radii of these other concentric annuluses. For example concentric annulus  146  corresponds to orifice  131 F. 
     The measurement of uniform dispensing of fluid onto a wafer is accomplished by measuring the volume of fluid flow per unit time through each orifice and its partner and comparing that volume to the area of the corresponding concentric annulus, or, in the case of the middle orifice, to the area of the middle circle. The areas of the orifices can be selected by methods well known in the art to produce a volume of fluid flow per unit time dispensed in the aggregate through each orifice (other than the middle orifice) and its partner, proportional to the area of the corresponding concentric annulus, all with the same proportionality constant, and dispensed through the middle orifice proportional to the area of the middle circle with such proportionality constant. The areas of the orifices are one nozzle characteristic that can produce the proportional variation in, and affect, the volume of fluid flow just described. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages, can produce pressure, viscosity and other physical effects with the same proportional variation. 
     FIG. 19 depicts a perspective view of a fourth and preferred embodiment of the invention known as a wedge nozzle  150 . The nozzle is a generally wedge-shaped vessel with a total surface, a top surface  151 , a bottom  153 , a first side surface  155 , a second side surface  157 , and a very small middle side surface  159 . The bottom has a perimeter edge  152 , a first side edge  154 , a second side edge  156  and a very small middle side edge  158 . In a more preferable embodiment, the perimeter is arc-shaped and the small middle side edge  158  is substantially a point. Of course variations in this general shape will be readily apparent to those of ordinary skill in the art. 
     FIG. 20 a depicts a cross-sectional view of the preferred embodiment along an axis  160  connecting the middle side edge  158  and a point on the perimeter edge  152  and perpendicular to the top surface  151  of this embodiment. This view shows the interior  161  serving as a liquid reservoir. The nozzle&#39;s top surface has one or more inlet fittings  163 A, B for attachment to a fluid supply tube  165 A, B, a support  167  for connection to an external apparatus (not depicted) to support the nozzle, and an outlet fitting  169  for attachment to a gas outlet tube. Nevertheless, it will be apparent to those of ordinary skill in the art that these items shown on the top surface may or may not be present in the numbers, or in the locations on the nozzle, or in fact may be entirely absent. The bottom of the nozzle has portions downwardly projecting called nozzle tips  262 A, B, C, D, E, F, G, H with a multiplicity of openings or orifices  264 A, B, C, D, E, F, G, H out of which the fluid is dispensed. With the exception of the nozzle tips, the bottom is generally planar. Again, it will be apparent to those of ordinary skill in the art that the orifices might be disposed on a bottom that has no nozzle tips. 
     FIG. 21 depicts a transverse cross-section of the wedge nozzle  150  perpendicular to the longitudinal axis  160  and to the top surface  151 . The figure shows several orifices  362 A-F, possibly in several different arcs (described below), in fluid communication with the vessel&#39;s interior  161  through slits, e.g.,  364 , in the nozzle tips and small passages, e.g.,  366 , in the bottom wall  368  of the interior. 
     FIG. 22, in bottom plan view looking upwards from a rotating wafer  20  below the nozzle, shows the wedge nozzle  150  with its arc-shaped rows of orifices, e.g,  164 A-E. The bottom plan view depicts a reference point  170  situated on or in proximity to the bottom  153  and lying on a reference line (not shown) generally perpendicular to the bottom  153 . A plurality of non-intersecting arcs  171 A-E are shown, each with a center lying substantially on the reference line. For simplicity of depiction, the centers of the arc are shown at only one point on the reference line, the reference point  170 . The arcs have a substantially circular shape and are defined by an arc radius, e.g.,  173 A-C. The orifices and their nozzle tips(not shown in FIG. 22) are depicted as disposed substantially along the arcs and it is implicit in the figure that the nozzle tips themselves also have this arc-like contour, with each orifice on a specific arc regarded as corresponding to that specific arc. Nevertheless, it will be apparent to one of skill in the art that the orifices and their nozzle tips can be disposed along only one or a small number of arcs or, for that matter, in patterns other than along arcs. In fact, it is apparent to one of skill in the art that there could be an individual nozzle tip for each orifice. 
     In this bottom plan view and this orientation of the nozzle with respect to the wafer, the orifices face the wafer sufficiently to allow fluid dispensed from the orifices to contact the wafer surface with minimal disturbance of the desired dispensing process. Although the orifices, e.g.,  164 A-E, are depicted in FIG. 22 as being generally co-planar, circular in shape with equal diameters (and are so in the most preferable embodiment), and equidistant from each other in center-to-center distance along a given arc, it will be appreciated by those of ordinary skill in the art that the bottom may not be planar, the nozzle tip bottom ends in which the orifices are openings may not be co-planar, that the orifice centers, e.g.,  175 A,  175 B, might not be equidistant from each other, and that the orifice shapes might not be planar or two-dimensional and, even if two-dimensional and planar, might be semi-circular, elliptical, square or hexagonal in shape or of some other shape altogether. The wedge nozzle, when its small middle side edge  158  is placed over the wafer&#39;s center  177 , covers an approximately arc-shaped segment of the wafer. 
     The characteristics of the nozzle are selected so that the aggregate volume of fluid flow per unit time through the orifices corresponding to one arc, e.g.,  171 C, defined by its arc radius is greater than or substantially equal to such fluid flow through the orifices corresponding to another arc, e.g.,  171 B, with a smaller arc radius. As depicted in FIG. 22, the numbers of the orifices increase along the rows beginning with the row  171 A closest to the reference point  170 . The increasing orifice numbers, and corresponding increase in aggregate area of the orifices along the rows, are one nozzle characteristic that can produce the result of generally increasing, or non-decreasing, volume of fluid flow just described and that can affect that volume of fluid flow. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages, can produce pressure, viscosity and other physical effects with the same result. 
     More particularly, this embodiment can be employed so that the small middle edge  158  is placed over the center  177  of the wafer. So utilized, the wedge nozzle provides greater uniformity of dispensed fluid on the wafer than the prior art by providing greater amounts of fluid into annular regions of the wafer with greater area. 
     A more preferable embodiment of the wedge nozzle provides an even closer match between the amount of fluid dispensed onto the annular regions of the wafer and the area of those regions. The extent to which the desired uniform dispensing of fluid onto a wafer results can be measured by defining concentric annuluses lying within a circle using physical distances determined by the structure of the nozzle. This embodiment applies only when there are two or more arcs. The description that will be provided applies to the case when there are three or more arcs. The modification of this discussion for application to nozzles with two arcs will be apparent to one of skill in the art, but will nonetheless be briefly discussed below. 
     FIG. 23 depicts the wedge nozzle  150  again in a fashion similar to FIG. 22, but this time with concentric annuluses formed by halfway circles drawn with dashed lines. In this embodiment, although depicted as circles with equidistant centers, e.g.,  175 A,  175 B, along a given arc, it will be apparent to those of skill in the art that in a less preferable embodiment the orifices, e.g.,  164 A-E, can be merely two-dimensional with a variety of possible non-circular shapes, but with an approximate center, and along a given arc may not have equidistant centers. In addition, in the more preferable embodiment, the perimeter edge is arc-shaped, the middle side edge is substantially a point and the reference point is situated at or in proximity to the middle side edge. 
     To assist in defining the concentric annuluses, several geometric concepts are defined: a perimeter curve  171 E as the arc having the longest arc radius, and a central curve  171 A as the arc closest to the reference point  170 . In addition, a flow circle radius  179  is defined as the distance greater than or substantially equal to the distance from the reference point  170  to one of the points  177  furthest from the reference point of all of the points on the orifices corresponding to the perimeter curve  171 E. With that definition, a flow circle  172  is defined by a radius equal to the flow circle radius and a center at the reference point. 
     Several additional geometric concepts are defined as well. Two arcs, e.g.,  171 A, B, are said to be adjacent when they are defined respectively by two arc radiuses  173 A,B of successively greater length. An arc triplet comprises three arcs, e.g.,  171 A,B,C, defined respectively by three arc radiuses  173 A,B,C of successively greater length. The inside arcs of the arcs of the arc triplet are the two arcs  171 A,B of the arc triplet with the smallest two arc radiuses, while the outside arcs of the arc triplet are the two arcs  171 B,C with the largest two arc radiuses. The middle arc of the arc triplet is the arc  171 B with the arc radius of length between the lengths of the other two arc radiuses in the arc triplet. Finally, a halfway circle, e.g.,  174 B, is defined as a substantially circular shape within the flow circle having a radius  180 A substantially halfway in length between the lengths of two arc radiuses  173 B,C, defining any adjacent arcs, e.g.,  171 B,C. 
     Now the defining characteristics of the concentric annuluses can be laid out. An inner annular perimeter  174 B comprises that halfway circle  174 B of any two adjacent halfway circles, e.g.  174 B,C, which is closer to the reference point  170 . The inner annular perimeter  174 B is said to correspond to that arc  171 C which is the middle arc of that arc triplet  171 B,C,D whose two inside arcs  171 B,C define that closer halfway circle  174 B. Conversely, an outer annular perimeter  174 C comprises that halfway circle  174 C of any two adjacent halfway circles, e.g.,  174 B,C, which is further from the reference point. The outer annular perimeter  174 C corresponding to that arc  171 C which is the middle arc of that triplet  171 B,C,D whose two outside arcs  171 C,D define that further halfway circle  174 C. However, at the periphery, the inner final perimeter  174 D is the halfway circle furthest from the reference point, while the outer final perimeter  172  is the perimeter of the flow circle. 
     At this point the concentric annuluses themselves can be described. An interior annulus, e.g.,  181 , is an annulus within the flow circle defined by an inner annular perimeter., e.g.,  174 B, corresponding to an arc  171 C, and the outer annular perimeter  174 C, corresponding to that arc. The interior annulus, e.g.,  181  is deemed to correspond to that arc  171 C. On the other hand, the perimeter annulus  183  is an annulus within the flow circle  172  defined by the inner final perimeter  174 D and the outer final perimeter  172 . The perimeter annulus is deemed to correspond to the perimeter curve  171 E. 
     Putting together these two groups of annuluses, the concentric annuluses corresponding to an arc are defined as the perimeter annulus  183  corresponding to the perimeter curve (which is also an arc) and any interior annulus, e.g.,  181 , corresponding to any arc, e.g.,  171 C, other than the perimeter curve  171 E. Together with the concentric annuluses, a central circle  185  is employed for. measurement. That circle lies within the flow circle and is defined by a perimeter identical to the halfway circle  174 A closest to the reference point  120  and by a center at the reference point. This central circle is employed in connection with the central curve  171 A. 
     The measurement of uniform dispensing of fluid onto a wafer is accomplished by measuring the combined volume of fluid flow per unit time through the orifices on an arc, e.g.,  171 C, and comparing that volume to the area of the concentric annulus, e.g.,  181 , corresponding to that arc (for all arcs other than the central curve), or, in the case of that arc  171 A which is the central curve, to the area of the central circle  185 . The areas of the orifices can be selected by methods well known in the art to produce a combined volume of fluid flow per unit time dispensed through each orifice on an arc (other than the central curve) proportional to the area of the corresponding concentric annulus or dispensed through each orifice on the central curve proportional to the area of the corresponding central circle, all with the same proportionality constant. For example, if the orifices on the nozzle are all of equal area, the number of orifices on each arc will be selected to produce the required proportional volume of fluid flow. 
     As mentioned above, the more preferable embodiment has been described for cases in which there are three or more arcs. By modifying the description in one major respect, the description would apply to the case of two arcs. This modification consists in eliminating the notion of the interior annulus. The measurements of fluid flow are then undertaken only for the perimeter annulus and the central circle. The areas and numbers of the orifices on each of the two arcs are then selected to produce the same proportionality achieved in the case where there are at least three arcs. 
     The areas or numbers of the orifices are one nozzle characteristic that can produce the proportional variation in, and affect the, volume of fluid flow just described. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages, can produce pressure, viscosity and other physical effects with the same proportional variation. 
     FIG. 24 depicts a perspective view of a fifth embodiment of the invention known as a general-purpose (full) nozzle  350 . This embodiment is a vessel with a longitudinal axis  370 , a total surface, a top surface  351 , a bottom  353 , a first side surface  305 A, and a second side surface  305 B. FIG. 24 depicts the intersections of various surfaces as linear. Other contours for those intersections and other variations in the general shape depicted will be readily apparent to those of ordinary skill in the art. 
     FIG. 25 depicts a cross-sectional view along the longitudinal axis  370  and perpendicular to the top surface  351  of this embodiment of the invention showing the interior  378  serving as a liquid reservoir. The general-purpose (full) nozzle&#39;s top surface  351  has one or more inlet fittings  363 A, B for attachment to a fluid supply tube  367 A, B, a support  367  for connection to an external apparatus (not depicted) to support the nozzle, and an outlet fitting  369  for attachment to a gas outlet tube. Nevertheless, it will be apparent to those of ordinary skill in the art that these items shown on the top surface may or may not be present in the numbers, or in the locations on the nozzle, or in fact may be entirely absent. The bottom of the nozzle has portions downwardly projecting called nozzle tips  372 A, B, C with a multiplicity of openings or orifices  384 A, B, C out of which the fluid is dispensed. Again, it will be apparent to those of ordinary skill in the art that the orifices might be disposed on a bottom that has no nozzle tip. 
     FIG. 26 depicts a transverse cross-section of the general-purpose (full) nozzle  350  perpendicular to the longitudinal axis  370  and to the top surface  351  of this embodiment. The figure shows several orifices  394 A, B, C, D in fluid communication with the vessel&#39;s interior  378  through slits, e.g.,  392 , in the nozzle tips and small passages, e.g.,  386  in the bottom wall  388  of the interior. 
     FIG. 27, in bottom plan view looking upwards from a rotating wafer  280  below the nozzle  290 , shows the general-purpose (full) nozzle  290  and orifices, e.g.,  310 C 1 ,  310 C 2 ,  310 C 3 . In this view and this orientation of the nozzle with respect to the wafer, the orifices face the wafer sufficiently to allow fluid dispensed from the orifices to contact the wafer surface with minimal disturbance of the desired dispensing process. Although the orifices, e.g.,  310 C 1 ,  310 C 2 ,  310 C 3 , are depicted in FIG. 27 as being generally co-planar and circular in shape, it will be apparent to those of ordinary skill in the art that the bottom may not be planar and the nozzle tip bottom ends in which the orifices are openings may not be co-planar and that the orifice shapes might not be planar or two-dimensional and, even if two-dimensional and planar, might be semi-circular, elliptical, square or hexagonal in shape or of some other shape altogether. The nozzle  290 , when placed over the wafer  280 , extends about one wafer diameter between opposite points on the perimeter of the wafer  280 . 
     For measurement convenience, several geometrical features of the bottom are defined. The bottom is subdivided into two or more non-overlapping portions called bottom subregions  310 A,B,C,D. One of these is called the first perimeter subregion  310 A which is one of the one or more bottom subregions closest to the first side surface  305 A, while the second perimeter subregion  310 D is one of the one or more bottom subregions closest to the second side surface  305 B. Each orifice is wholly contained within one of the bottom subregions and each bottom subregion contains at least one orifice. 
     In addition to bottom subregions, special points are isolated. The first perimeter point  315 A is one of the one or more points on the first perimeter subregion closest to the first side surface  305 A, while the second perimeter point  315 B is one of the one or more points on the second perimeter subregion closest to the second side surface  305 B. The halfway point  320  is a point substantially halfway between the first perimeter point and the second perimeter point, while the middle point  330  is one of the one or more points on the bottom closest to the halfway point. This halfway point may be a point within, on or outside the nozzle  290 , depending upon the exact geometry of the bottom of the nozzle while the middle point is on the nozzle bottom. 
     The characteristics of the nozzle are selected so that the aggregate volume of fluid flow per unit time through all the orifices in a given bottom subregion, e.g.,  310 B, are greater than or substantially equal to such flow through all the orifices in any other bottom subregion, e.g.,  310 C, closer to the middle point  330  than the given bottom subregion. As depicted in FIG. 27, the numbers of the circular orifices are generally larger in bottom subregions further from the middle point. This increasing number of orifices is one nozzle characteristic that can produce the result of generally increasing, or non-decreasing, volume of fluid flow just described. However, it will be apparent to those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages as well as the diameters of the orifices, can produce pressure, viscosity and other physical effects with the same result. 
     More particularly, this embodiment can be employed so that the middle point  330  lies approximately over the center of the wafer (not depicted). So utilized, this embodiment provides greater uniformity of dispensed fluid on the wafer than the prior art by providing greater amounts of fluid into annular regions of the wafer with greater area. 
     An alternative version of this embodiment of the invention provides an even closer match between the amount of fluid dispensed onto the annular regions of the wafer and the area of those regions. The extent to which the desired uniform dispensing of fluid onto a wafer results can be measured by defining concentric annuluses using physical distances determined by the structure of the nozzle. FIG. 28 depicts the general-purpose (full) nozzle  290  again, but this time with a variety of concentric annuluses, e.g.,  365 P-T, drawn. In this version, although depicted as circles, it will be appreciated by those of skill in the art that more generally the orifices, e.g.,  310 C 1 ,  310 C 2 ,  310 C 3 , are merely two-dimensional with a variety of possible non-circular shapes and have an approximate center. The center of the concentric annuluses is the middle point  330 . 
     To assist in defining the concentric annuluses, a long distance, e.g.,  310 BL, for each bottom subregion is defined as the distance from the middle point to one  310 BF of that one or more points on the perimeter  310 BF of that subregion which are furthest from the middle point. Similarly, a short distance, e.g.,  310 BS, for each bottom subregion is defined as the distance from the middle point to one  310 BC of that one or more points on the perimeter of that subregion which are closest to the middle point. To further assist the defining of the concentric annuluses, a flow circle  360  is defined as the circle with the middle point as its center and having a radius  361  greater than or substantially equal to the long distance  310 AL for the first perimeter subregion. 
     Defining the concentric circles is more difficult for this embodiment than the earlier ones due to possible overlap of geometric areas. The defining process has three steps. 
     First a “concentric annulus” is defined as an annulus (e.g., the area enclosed by inner perimeter  320 BI and outer perimeter  320 BO which is a combination of areas  365 R,S in the flow circle) with a center at the middle point, with an outer radius equal to the long distance  310 BL for a bottom subregion, e.g.,  310 B, not containing the middle point  330 , and with an inner radius equal to the short distance  310 BS for that bottom subregion. The annulus is said to correspond to that bottom subregion. The special case where there is a bottom subregion containing the middle point will be described below. 
     Second, a “simple annulus” is defined as an annulus of the flow circle comprising both (i) any group of two or more concentric annuluses, each of which contains, is contained in (area  365 Q is contained in the combination of areas  365 Q,R), is identical to, or substantially overlaps (the combination of areas  365 Q,R overlaps the combination of areas  365 R,S) at least one other concentric annulus within such group, as well as (ii) any one concentric annulus (area  365 T) not containing, not contained in, not identical to, and not substantially overlapping any other concentric annulus. 
     Third, a “bottom simple subregion” is defined as any group of one  310 C or more ( 310 A,B,D) bottom subregions corresponding, respectively, to the one (the area  365 T) or more (the multiple concentric annuluses comprising the area  365 Q as one concentric annulus, the areas  365 Q,R, in combination as another concentric annulus, and the areas  365 R,S in combination as yet another concentric annulus) concentric annuluses which together comprise a simple annulus. That bottom simple subregion is said to correspond to that simple annulus. Thus, the bottom simple subregion  310 A,B,D corresponds to the simple annulus determined by radii  310 AL and  310 BS, while the bottom simple subregion  365 T corresponds to the simple annulus  365 T determined by radii  310 CS and  310 CL. 
     The measurement of uniform dispensing of fluid onto a wafer is accomplished by measuring the combined volume of fluid flow per unit time through the orifices, e.g.,  365 C 1 , 2 , 3 , in each bottom simple subregion, e.g.,  310 C,and comparing that volume to the area of the corresponding simple annulus  365 T. The areas of the orifices can be selected by methods well known in the art to produce a volume of fluid flow per unit time dispensed in the aggregate through the orifices in each bottom simple subregion proportional to the area of the simple annulus, all with the same proportionality constant. The areas of the orifices are one nozzle characteristic that can produce the proportional variation in, and affect, the volume of fluid flow just described. However, it will be appreciated by those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages as well as the diameters of the orifices, can produce pressure, viscosity and other physical effects with the same proportional variation. 
     For the special case depicted in FIG. 29 showing the same nozzle as in FIG. 28, but with a bottom subregion  310 E containing the middle point  330 , no concentric or simple annulus or bottom simple subregion is defined by the dimensions of that bottom subregion  310 E. Instead, a central circle  325  is defined as the circle having a center at the middle point  330  and a radius equal to the long distance  325 R of the bottom subregion containing the middle point. Assume for the moment (as depicted in FIG. 31) that no simple annulus substantially overlays the central circle  325 . In this special case, the characteristics of that bottom subregion (e.g., its number of orifices or their area) are selected so that the total volume of fluid flow per unit time through the orifices, e.g.,  310 E 1 , in that bottom subregion  310 E is substantially proportional to the area of the central circle  325  with the same proportionality constant described above for the simple annuluses. 
     If the assumption is false for this special bottom subregion  310 E and there is a substantially overlapping simple annulus (not depicted), the central circle  325  must be expanded to define a circle that will include that simple annulus. From the foregoing teachings regarding the definitions of simple annulus and bottom simple subregion and their use to account for overlap, it will be apparent to those of skill in the art how to perform that expansion and it will also be apparent to those of skill in the art how to select the area of the orifices in the bottom simple subregions and the characteristics of the bottom subregions defining the expanded central circle, all to the end that the same proportionalities of fluid flow to areas are achieved. In fact, the claims associated with this embodiment describe in detail that very expansion and selection process. 
     A sixth embodiment of the invention, called the general-purpose (half) nozzle has perspective and cross section views of the general-purpose (half) nozzle substantially identical to those depicted in FIGS. 24,  25 , and  26  for the general-purpose (full) nozzle. 
     FIG. 30, in bottom plan view looking upwards from a rotating wafer  480  below the nozzle  490 , shows the general-purpose (half) nozzle  490  and orifices, e.g.,  510 C 1 ,  510 C 2 ,  510 C 3 . In this view and this orientation of the nozzle with respect to the wafer, the orifices face the wafer sufficiently to allow fluid dispensed from the orifices to contact the wafer surface with minimal disturbance of the desired dispensing process. Although the orifices, e.g.,  510 C 1 ,  510 C 2 ,  510 C 3 , are depicted in FIG. 30 as being generally co-planar and circular in shape, it will be appreciated by those of ordinary skill in the art that the bottom may not be planar and the nozzle tip bottom ends in which the orifices are openings may not be co-planar and that the orifice shapes might not be planar or two-dimensional and, even if two-dimensional and planar, might be semi-circular, elliptical, square or hexagonal in shape or of some other shape altogether. The nozzle  490 , when placed over the wafer  480 , extends about one wafer radial length from the center of the wafer (not shown) to the perimeter of the wafer  480 . 
     For measurement convenience, several geometrical features of the bottom are defined. The bottom is subdivided into two or more non-overlapping portions called bottom subregions  510 A, B, C, D and one of those is called the first perimeter subregion  510 A, which is one of the one or more bottom subregions closest to the first side surface  505 A, while the second perimeter subregion  510 D is one of the one or more bottom subregions closest to the second side surface  505 B. Each orifice is wholly contained within one of the bottom subregions and each bottom subregion contains at least one orifice. 
     In addition to the bottom subregions, special points are isolated. The first perimeter point  515 A is one of the one or more points on the first perimeter subregion closest to the first side surface  505 A. The central point  530  lies on the bottom and is one of the one or more points on the second perimeter subregion  510 D closest to the second side surface  505 B. 
     The characteristics of the nozzle are selected so that the aggregate volume of fluid flow per unit time through all the orifices in a given bottom subregion, e.g.,  510 B, are greater than or substantially equal to such flow through all the orifices in any other bottom subregion, e.g.,  510 C, closer to the central point  530  than the given bottom subregion. As depicted in FIG. 30, the numbers of the circular orifices are generally larger in bottom subregions further from the central point. This increasing number of orifices is one nozzle characteristic that can produce the result of generally increasing, or non-decreasing, volume of fluid flow just described. However, it will be appreciated by those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages as well as the diameters of the orifices, can produce pressure, viscosity and other physical effects with the same result. 
     More particularly, this embodiment can be employed so that the central point  530  lies approximately over the center of the wafer (not depicted). So utilized, this embodiment provides greater uniformity of dispensed fluid on the wafer than the prior art by providing greater amounts of fluid into annular regions of the wafer with greater area. 
     An alternative version of this embodiment of the invention provides an even closer match between the amount of fluid dispensed onto the annular regions of the wafer and the area of those regions. The extent to which the desired uniform dispensing of fluid onto a wafer results can be measured by defining concentric annuluses using physical distances determined by the structure of the nozzle. FIG. 31 depicts the general-purpose nozzle (half)  490  again, but this time with a variety of concentric annuluses, e.g.,  565 P-T, drawn. In this version, although depicted as circles, it will be appreciated by those of skill in the art that more generally the orifices, e.g.,  510 C 1 ,  510 C 2 ,  510 C 3 , are merely two-dimensional with a variety of possible non-circular shapes and have an approximate center. The center of the concentric annuluses is the central point  530 . 
     To assist in defining the concentric annuluses, a long distance, e.g.,  510 BL, for each bottom subregion is defined as the distance from the central point to one  510 BF of that one or more points on the perimeter  510 BP of that subregion which are furthest from the central point. Similarly, a short distance, e.g.,  510 BS, for each bottom subregion is defined as the distance from the central point to one  510 BC of that one or more points on the perimeter of that subregion which are closest to the central point. To further assist the defining of the concentric annuluses, a flow circle  560  is defined as the circle with the central point as its center and having a radius  561  greater than or substantially equal to the long distance  510 AL for the first perimeter subregion. 
     Defining the concentric circles is more difficult for this embodiment than the earlier ones due to possible overlap of geometric areas. The defining process has three steps. 
     First a “concentric annulus” is defined as an annulus (e.g., the area enclosed by inner perimeter  520 BI and outer perimeter  520 BO which is a combination of areas  565 R,S in the flow circle) with a center at the central point, with an outer radius equal to the long distance  510 BL for a bottom subregion, e.g.,  510 B, not containing the central point, and with an inner radius equal to the short distance  510 BS for that bottom subregion. The annulus is said to correspond to that bottom subregion. The bottom subregion  510 D containing the central point  530  will be disregarded temporarily. 
     Second, a “simple annulus” is defined as an annulus of the flow circle comprising both (i) any group of two or more concentric annuluses, each of which contains, is contained in, is identical to, or substantially overlaps (the combination of areas  565 Q,R overlaps the combination of areas  565 R, S) at least one other concentric annulus within such group, as well as (ii) any one concentric annulus area  565 T not containing, not contained in, not identical to, and not substantially overlapping any other concentric annulus. 
     Third, a “bottom simple subregion” is defined as any group of one  510 C or more bottom subregions corresponding to the one (the area  565 T) or more (the multiple concentric annuluses comprising the areas  565 Q,R in combination as one concentric annulus and the areas  565 R,S in combination as another concentric annulus) concentric annuluses which together comprise a simple annulus. That bottom simple subregion is said to correspond to that simple annulus. Thus the bottom simple subregion  553   10 A,B, corresponds to the simple annulus determined by radii  510 AL and  510 BS, while the bottom simple subregion  565 T corresponds to the simple annulus determined by radii  510 CS and  510 CL. 
     The measurement of uniform dispensing of fluid onto a wafer is accomplished by measuring the combined volume of fluid flow per unit time through the orifices, e.g.,  510 C 1 ,  2 ,  3 , in each bottom simple subregion, e.g.,  510 C, and comparing that volume to the area of the corresponding simple annulus  565 T. The areas of the orifices can be selected by methods well known in the art to produce a volume of fluid flow per unit time dispensed in the aggregate through the orifices in each bottom simple subregion proportional to the area of the simple annulus, all with the same proportionality constant. The areas of the orifices are one nozzle characteristic that can produce the proportional variation in, and affect, the volume of fluid flow just described. However, it will be appreciated by those of ordinary skill in the art that other characteristics of the nozzle, including its nozzle tips and small passages as well as the diameters of the orifices, can produce pressure, viscosity and other physical effects with the same proportional variation. 
     The special bottom subregion  510 D containing the central point  530  was temporarily disregarded. No concentric or simple annulus, or bottom simple subregion is defined by the dimensions of that bottom subregion  510 D. Instead, a central circle  525  defined as the circle having a center at the central point  530  and a radius equal to the long distance  525 R of the bottom subregion containing the central point. Assume for the moment (as depicted in FIG. 31) that no simple annulus substantially overlays the central circle  525 . For this special bottom subregion, the characteristics of that bottom subregion (e.g., its number of orifices or their area) are selected so that the total volume of fluid flow per unit time through the orifices in that bottom subregion  510 D is substantially proportional to the area of the central circle  525  with the same proportionality constant described above for the simple annuluses. 
     If the assumption is false for this special bottom subregion  510 D and there is a substantially overlapping simple annulus (not depicted), the central circle  525  must be expanded to define a circle that will include that simple annulus. From the foregoing teachings regarding the definitions of simple annulus and bottom simple subregion and their use to account for overlap, it will be apparent to those of skill in the art how to perform that expansion and it will also be apparent to those of skill in the art how to select the area of the orifices in the bottom simple subregions and the characteristics of the bottom subregions defining the expanded central circle, all to the end that the same proportionalities of fluid flow to areas are achieved. In fact, the claims associated with this embodiment describe in detail that very expansion and selection process. 
     The various embodiments of the invention have many physical characteristics in common, such as the composition of materials forming the vessel, orifice size and the like, as will be appreciated by those of skill in the art, and those characteristics will be apparent to those of such skill. For example, the height of the block or wedge embodiments will typically be in the approximate range of ¾″-1½″, the fluid supply also used with the embodiments will typically be in the approximate range of ⅛″-¼″ or greater in diameter, the inlet fittings will typically be at one end or another of the top surface or on an upper portion of the side surfaces, the orifice diameters will typically be in the approximate range of 0.1 mm-5 mm, perhaps most effectively at about 0.5 mm. The nozzle tip will have a height in the approximate range of 1 mm-2 mm. The arc angle formed by the wedge shape will typically be in the range of approximately 15°-45°. 
     The nozzles are generally fabricated of plastics that are both mechanically stable and resistant to chemical attack, characteristics well known to those of skill in the art. The nozzle is usually fabricated in two monolithic pieces: the top surface and the remainder of the nozzle. 
     Typically, the nozzle is positioned above the wafer below a distance ranging between 1 mm and 1 cm.