Abstract:
An apparatus for applying a layer to a hydrophobic surface. The apparatus including: a chuck having a top surface and rotatable about a axis perpendicular to the top surface and passing through a center point of the top surface; and hollow first and second dispense nozzles having respective first and second bores, the first and second dispense nozzles mounted on a application head disposed above the top surface of the chuck, the application head moveable in a direction parallel to the top surface of the chuck, the first dispense nozzle alignable over the center point when the application head is in a first position and the second dispense nozzle alignable over the center point when the application head is in a second position, at least a portion of the bore of second dispense tube having a maximum cross-sectional dimension of between about 0.5 millimeters and about 2.0 millimeters.

Description:
RELATED APPLICATION 
     The present invention claims priority to and is a division of U.S. patent application Ser. No. 11/161,214 filed on Jul. 27, 2005, now U.S. Pat. No. 7,384,878, which is a continuation-in-part of abandoned U.S. patent application Ser. No. 10/709,654, filed May 20, 2004 now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of applying layers of material to hydrophobic surfaces; more specifically, it relates to method for reducing the quantity of the material applied to a substrate having a hydrophobic surface in order to form a uniform layer of the material on the hydrophobic surface. 
     BACKGROUND OF THE INVENTION 
     There are many aqueous based materials that must be applied to surfaces that are hydrophobic or water repelling surfaces. In order to form a uniform coating, especially by spinning or spin coating, an excess of the aqueous based material must be applied, and the excess then removed and discarded. Since in many applications, for example, in the application of a top anti-reflective coating (TARC) to a photoresist layer formed on a semiconductor substrate or wafer, the amount of discarded material is very many times the amount of material in the finished coating and thus the wastage and resultant cost is very high. Therefore, there is a need for a method to reduce the amount of material required to form a uniform layer on a hydrophobic surface. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention an apparatus, a chuck having a top surface and rotatable about a axis perpendicular to the top surface and passing through a center point of the top surface; and hollow first and second dispense nozzles having respective first and second bores, the first and second dispense nozzles mounted on a application head disposed above the top surface of the chuck, the application head moveable in a direction parallel to the top surface of the chuck, the first dispense nozzle alignable over the center point when the application head is in a first position and the second dispense nozzle alignable over the center point when the application head is in a second position, at least a portion of the bore of second dispense tube having a maximum cross-sectional dimension of between about 0.5 millimeters and about 2.0 millimeters. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The features of the invention are set forth in the appended claims. The invention itself, however, will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
         FIGS. 1A through 1D  are partial cross-sectional drawing illustrating application of the present invention to a photo-lithographic process according to the present invention; 
         FIGS. 2A through 2D  are schematic diagrams illustrating a method of forming a uniform layer on a hydrophobic surface according to the present invention; 
         FIG. 3  is a flowchart of a method of applying a layer to a hydrophobic surface according to a control method; 
         FIG. 4  is a flowchart of a method of applying a layer to a hydrophobic surface according to the present invention; 
         FIG. 5  is a chart illustrating thickness of a TARC layer applied to hydrophobic surface versus the volume of TARC used to form the layer according to the control method of  FIG. 3 ; 
         FIG. 6  is a chart illustrating thickness of a TARC layer applied to hydrophobic surface versus the volume of TARC used to form the layer according to the method of the present invention of  FIG. 4 ; 
         FIG. 7  is a chart, illustrating image size control versus the volume of TARC applied according to the method of the present invention; 
         FIG. 8  is a chart comparing the control method and the method of the present invention to of resist thickness versus the size of subsequently printed and developed images; and 
         FIGS. 9A ,  9 B and  9 C are cross-sectional views through a TARC dispense nozzle as illustrated in  FIG. 2D . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     For the purposes of the present invention the terms layer and coating may be used interchangeably. A substrate may have any shape, including square, round, rectangular or irregular. Substrate may comprise almost any material, including but not limited to metal, plastic and glass. A wafer is a substrate having the geometry of a thin disk. When preferenced by the word “semiconductor” the terms substrate and wafer imply the wafer or substrate comprises semiconductor materials such as silicon and/or germanium including bulk silicon wafers and silicon-on-oxide (SOI) wafers. Unless otherwise noted, the water used describing in the present invention is de-ionized (DI) water having resistivity of about 10 18  megohms or higher to avoid ionic and particulate contamination of the wafer. Any other purified water, such as distilled or water produced by reverse osmosis may be used. Where ionic contamination is not a concern, substantial amount of impurities may be present provided they do not adversely effect the operation of the present invention. The terms resist and photoresist are used interchangeably. 
     The present invention will be primarily described in the context of the semiconductor industry in general and in application of TARCs to photoresist layers in particular but is applicable to any product or process requiring coating a hydrophobic surface. An anti-reflective layer suppresses thin film interference effects by reducing the amount of energy reflected back into the photoresist layer from the photoresist/anti-reflective coating interface. Both the index of refraction and thickness of the anti-reflective layer are critical parameters in achieving optimal thin film interference suppression. A TARC is therefore an antireflective coating applied to the top surface of the photoresist layer. Examples of photoresist materials are given in TABLE I and of TARC materials in TABLE II, but the invention should not be construed as limited to the particular photoresist or TARC materials listed in TABLES I and II. 
     The application of the present invention to the semiconductor industry should thus be considered as a primary example of the problem of coating hydrophobic surfaces. 
       FIGS. 1A through 1D  are partial cross-sectional drawing illustrating application of the present invention to a photolithographic process according to the present invention. In  FIG. 1A , a photoresist layer  100  having a top surface  105  has been formed on the top surface  110  of a substrate  115 . Top surface  105  is a hydrophobic surface, which is not unexpected based on the chemical composition of modern photoresists (see TABLE I infra) since most photoresists are solvent based hydrophobic monomers, polymers or resins. The degree of hydrophobicity of a surface is measured by its water contact angle. Water contact angle is discussed infra more fully in reference to  FIG. 2B . In  FIG. 1B  a water layer  120  having a top surface  125  has been formed on top surface  110  of photoresist later  115 . In step  1 C, a TARC layer  130  has been formed on top surface  125  of water layer  120 . It is possible, in light of the chemical composition of TARC layer  130 , being a small amount of water soluble polymer dissolved in water (see TABLE II infra), that water layer  120  is absorbed into TARC layer  130  although the water layer and TARC layer are shown as separate in  FIG. 1C . The lifetime of water layer  120  is very short under normal clean room conditions of about 20° C. and about 38% to 40% relative humidity, being about less than a few seconds, so TARC layer  130  must be formed within a limited amount of time after formation of water layer  120 . In  FIG. 1D , photoresist layer  100  has been patterned by exposure to ultraviolet light and developed thus exposing top surface  110  of substrate  115  where the photoresist layer has been developed away. The developing process removes TARC layer  130  and water layer  120 . 
     TABLE I is a list of exemplary photoresist materials suitable for use in the present invention when applied to semiconductor fabrication. Mid-ultraviolet (MUV) indicates a photoresist suitable for exposure at mid-ultraviolet wavelengths of light of about 365 nm. Deep-ultraviolet (DUV) indicates a photoresist suitable for exposure at deep-ultraviolet wavelengths of light of about 248 nm or less. Other photoresists may be used as well. 
     
       
         
               
               
               
               
             
           
               
                 TABLE I 
               
               
                   
               
               
                 TYPE 
                 MANUFACTURER 
                 NAME 
                 COMPOSITION 
               
               
                   
               
             
             
               
                 MUV 
                 TOK OHKA 
                 TSMR-iN011 PM 
                 Propylene glycol monomethyl 
               
               
                   
                 KOGYO CO., LTD 
                 TSMR-iN027 PM 
                 ether acetate (60-95%) 
               
               
                   
                 Kawasaki City, Japan 
                   
                 Polyhydroxy styrene type resin (5-35%) 
               
               
                   
                   
                   
                 Photoacid generator (&lt;5%) 
               
               
                   
                   
                   
                 Crosslinking agent (&lt;5%) 
               
               
                   
                   
                 THMR-iP3250 LB 
                 Ethyl lactate (61-79%) 
               
               
                   
                   
                   
                 n-Butyl acetate (6-9%) 
               
               
                   
                   
                   
                 Novolac resin (10-25%) 
               
               
                   
                   
                   
                 Photoactive compound (2-8%) 
               
               
                   
                 Sumitomo Chemical 
                 Sumiresist PFI-58 
                 Methyl amyl ketone(2-Heptanone) 
               
               
                   
                 Co., LTD 
                   
                 (63-88%) 
               
               
                   
                 Osaka, Japan 
                   
                 Novolac resin (8-25%) 
               
               
                   
                   
                   
                 Photoactive compound (4-12%) 
               
               
                 DUV 
                 JSR Microelectronics 
                 JSR ARF AR 237J 
                 Poly(meth)acrylate (5-25%) 
               
               
                   
                 Inc. 
                   
                 Alicyclic carboxylic ester (0-5%) 
               
               
                   
                 Tokyo, Japan 
                   
                 Photoacid generator (0.1-3%) 
               
               
                   
                   
                   
                 Propylene glycol monomethyl 
               
               
                   
                   
                   
                 ether acetate (60-95%) 
               
               
                   
                   
                   
                 Gamma-Butyrolactone (0-10%) 
               
               
                   
                   
                 JSR ARF AR 
                 Poly(meth)acrylate (5-25%) 
               
               
                   
                   
                 1570J 
                 Alicyclic carboxylic ester (0-10%) 
               
               
                   
                   
                   
                 Photoacid generator (0.1-3%) 
               
               
                   
                   
                   
                 Propylene glycol monomethyl 
               
               
                   
                   
                   
                 ether acetate (75-85%) 
               
               
                   
                   
                   
                 Gamma-Butyrolactone (0-10%) 
               
               
                   
                   
                 JSR KRF M20G 
                 Polyhydroxy styrene derivative 
               
               
                   
                   
                   
                 (10-30%) 
               
               
                   
                   
                   
                 Iodonium salt compound (0.1-1%) 
               
               
                   
                   
                   
                 Ethyl lactate (50-70%) 
               
               
                   
                   
                   
                 Ethyl 3-ethoxypropionate (20-30%) 
               
               
                   
                 Rohm and Haas 
                 UV(TM) 110-0.4 
                 Ethyl lactate (&gt;70%) 
               
               
                   
                 Electronic Materials 
                   
                 Aromatic Sulfur Compound (&lt;2%) 
               
               
                   
                 LLC 
                   
                 Aromatic Acrylic Polymer (&lt;30%) 
               
               
                   
                 Marlborough, MA, 
                   
                 Nonionic surfactant (&lt;1%) 
               
               
                   
                 USA 
               
               
                   
                   
                 UVII(TM) HS-0.8 
                 Ethyl lactate (75-88%) 
               
               
                   
                   
                   
                 Acrylic Copolymer (10-20%) 
               
               
                   
                   
                   
                 Organic Siloxane Surfactant (0-1%) 
               
               
                   
                   
                   
                 Aromatic Sulfur Compound (0.1-1%) 
               
               
                   
               
             
          
         
       
     
     TABLE II is a list of exemplary TARC materials suitable for use in the present invention when applied to semiconductor fabrication. MUV indicates a TARC suitable for coating a photoresist exposed with mid-ultraviolet wavelength light. DUV indicates a TARC suitable for coating a photoresist exposed with deep-ultraviolet wavelength light. Other TARC materials may be used as well. 
     
       
         
               
               
               
               
             
           
               
                 TABLE II 
               
               
                   
               
               
                 TYPE 
                 MANUFACTURER 
                 NAME 
                 COMPOSITION 
               
               
                   
               
             
             
               
                 MUV 
                 Clariant Corporation 
                 AZ Aquatar 
                 Fluoroalkyl acid ammonium salt (3%) 
               
               
                   
                 Somerville, NJ, USA 
                   
                 2-propenoic acid homopolymer (1.5%) 
               
               
                   
                   
                   
                 Water (95.5%) 
               
               
                 DUV 
                 JSR Microelectronics 
                 JSR NFC 540 
                 Fluoro acrylic polymer (1-10%) 
               
               
                   
                 Inc. 
                   
                 Anionic surfactant (0.1-1%) 
               
               
                   
                 Tokyo, Japan 
                   
                 Water (90-99%) 
               
               
                   
               
             
          
         
       
     
     As may be seen in Table II from the composition of AZ Aquatar is about 95.5% and JSR NFC 540 being about 90-99% water, TARC materials comprise substantial amounts of water. 
       FIGS. 2A through 2D  are schematic diagrams illustrating a method of forming a uniform layer on a hydrophobic surface according to the present invention. In  FIG. 2A , a semiconductor wafer  150  is positioned on top surface  155  of a wafer chuck  160 . Semiconductor wafer  150  has, for example, a diameter of 100, 125, 200 or 300 mm. A layer of photoresist  165  has been formed on a top surface  170  of semiconductor wafer  150 . Wafer chuck  160  is rotatable about an axis  175  that is ideally perpendicular to top surface  155  of wafer chuck  160 . Ideally axis  175  also passes through the geometric center  180  of wafer chuck  160  and the geometric center  185  of semiconductor wafer. 
     In  FIG. 2B , an application head  200  has a first nozzle  205  for applying water and a second nozzle  210  for applying TARC. Application head  200  can move laterally in order to align either first nozzle  205  or second nozzle  210  with axis  175  so the material dispensed from the nozzles is ideally dispensed in the center of wafer  150 . In  FIG. 2B , first nozzle  205  is aligned with axis  175  and a predetermined amount of water sufficient to form a globule of water  215  on a top surface  220  of photoresist layer  165  is dispensed. Since top surface  220  of photoresist layer may not be level (as measured by a spirit level for example) and nozzle  205  may not be exactly centered on axis  175 , wafer chuck  160  is rotated at a predetermined speed before and during the water dispense cycle. In one example, wafer chuck is rotated from about 5 to 50 rpm and about 2 to 20 ml of water are dispensed at a rate of about 0.5 to 3.0 ml/sec. The exact amount of water dispensed must not exceed an amount that would cause water globule  215  to collapse and not be less than an amount that will not subsequently spread evenly over the entire top surface  220  of photoresist layer  165 . The exact speed of rotation of wafer chuck  160  must not exceed a speed of rotation that would cause globule of water  215  to break apart. 
     It will be seen that globule of water  215  contacts top surface  220  of photoresist layer along a line  225  tangent to the surface  230  of the globule of water. A water contact angle θ, is thus defined as the angle between a plane tangent to surface  230  of water globule  215  and top surface  220  of photoresist layer  165 , at any point along their line of contact. The higher the water contact angle, the less wettable (more hydrophobic) the surface. The photoresists in Table I when spin coated on a substrate have top surfaces having water contact angles in the range of about 40° to 60°. 
     The phenomenon of wetting (hydrophilicity) or non-wetting (hydrophobicity) of a surface by a liquid (water) is measured by the liquid (water) contact angle. Contact angle measurement methods have been developed extensively over the past four decades and are well known in the art. A large body of reliable data and literature exists correlating contact angle data with the properties of surface tension. 
     In  FIG. 2C , a water layer  235  is formed on top surface  220  of photoresist layer  165  by ramping up rotation of wafer chuck  160  after the predetermined volume of water has been dispensed at a ramp rate of about 10,000 rpm/sec to a water spin off speed of about 500 to 2000 rpm and spinning for a spin off time of about 0.3 to 5.0 seconds. Simultaneously, second nozzle  210  of application head  200  is moved to align with axis  175 . Water globule  215  (see  FIG. 2B ) is thus spread out to form water layer  235  and excess water spun off. Formation of water layer  235  is observable by formation of interference fringes during the spinning. Because water layer  235  will completely vaporize within a few seconds, it is difficult to determine the exact thickness of the water layer. 
     In  FIG. 2D , a layer of TARC  240  is formed on a top surface  245  of water layer  235  by ramping up the rotation speed of wafer chuck  160  by about 10,000 rpm/sec from the spin-off speed to a TARC apply speed of about 2 000-5,000 rpm within about 0 to 2 seconds of the spin off time for forming water layer  235  expiring, dispensing TARC at a rate of about 1.0 ml of TARC/sec for a predetermined amount of time (the time is a function of the total volume of TARC to be applied) and then ramping down the rotation speed of wafer chuck  160  by about −1,000 rpm/sec from the TARC apply speed to a casting speed of about 2,500 rpm and spinning at the casting speed for about 15 seconds. 
     Water layer  235  may be only one to several molecular layers thick (or may not even be a continuous layer). Water layer  235  may even be no more than a collection of water molecules temporarily bound to the surface molecules of photoresist layer  165 . Water layer  235  may be immediately absorbed into TARC layer  240  as soon at the TARC layer forms. It has been experimentally determined that the amount of TARC dispensed and still have a TARC layer of fixed thickness and uniformity is reduced by the spin application of water before application of TARC. It is believed that this reduction in TARC dispense volume is possible because water layer  235  alters the surface tension characteristics of the photoresist/TARC system and allows better wetting of photoresist layer  165  by TARC layer  240 . 
     Consider a drop of a liquid resting on a solid surface. The drop of liquid may be considered as resting in equilibrium by balance the three forces involved, namely, the interfacial tensions between solid and liquid, between solid and vapor and between liquid and vapor. The surface tension of the solid will favor spreading of the liquid, but this is opposed by the solid-liquid interfacial tension and the vector of the surface tension of the liquid in the plane of the solid surface. In the present invention, it is believed that the water layer increases the surface tension of the surface to be coated (photoresist surface), decreases the solid-liquid interfacial tension between the liquid (TARC) and surface being coated (photoresist surface), decreases the surface tension of the material being coated (TARC) or a combination of the forgoing effects. 
     The most important consideration for our purposes is that surface tension values are intimately related to the surface constitution. Even small changes in the outermost atomic layer of the photoresist are reflected in a change of surface tension and thus wettability (degree of hydrophilicity or hydrophobicity) of the photoresist. 
     In order to establish the reduction in volume of TARC required to coat a wafer to a fixed thickness and still have acceptable thickness uniformity across a wafer, from wafer to wafer and from tool to tool a set of experiments were performed against a control process. The control process and experimental process are illustrated in  FIGS. 3 and 4  respectively and described infra. The photoresist and TARC materials were selected from TABLE I and TABLE II respectively. Wafers were 200 mm diameter semiconductor wafers. 
       FIG. 3  is a flowchart of a method of applying a layer to a hydrophobic surface according to a control method. In step  300 , a layer of photoresist is applied. The photoresist layer is pre-baked to drive out excess solvent and cooled to room temperature. In step  305 , a volume of TARC at about 1 ml/sec is applied at 0 rpm spin speed. The volume of TARC varies by experimental cell and is discussed infra. In a nominal case the volume of TARC dispensed is about 5 ml. Then, in step  310 , the wafer is ramped up to a casting speed of about 2,500 rpm at a ramp rate of 1,000 rpm/sec and spun for about 15 seconds to spin off excess TARC. The wafer rotation is then stopped. 
       FIG. 4  is a flowchart of a method of applying a layer to a hydrophobic surface according to the present invention. In step  350 , a layer of photoresist is applied. The photoresist layer is pre-baked to drive out excess solvent and cooled to room temperature. In step  355 , the wafer is rotated at about 15 rpm and about 10 ml of water is dispensed at a rate of about 0.65 ml/sec. In step,  360 , as soon as the water dispense is completed, the wafer is ramped from about 15 rpm to about 1,000 rpm at a ramp rate of about 10,000 rpm/sec and spun for a total time of about 0.3 seconds. In step  365 , the wafer is ramped from about 1,000 rpm to about 3,500 rpm at a ramp rate of about 10,000 rpm/sec and a volume of TARC at about 1 ml/sec is applied. The volume of TARC varies by experimental cell and is discussed infra. In a nominal case the volume of TARC dispensed is about 0.3 ml. There is now an option. The method can proceed to step  370 A or  370 B. In step  370 A, the wafer rotation is ramped down to a casting speed of about 2,500 rpm at a rate of about −1,000 rpm/sec and allowed to spin for about 15 seconds. The wafer rotation is then stopped. In step  370 B, the wafer rotation is ramped down to about 150 rpm at a ramp rate of about −50,000 rpm/sec and held at about 150 rpm for about 1 second. Then the wafer the wafer rotation is ramped up to a casting speed of about 2,500 rpm at a rate of about 1,000 rpm/sec and allowed to spin for about 15 seconds. The wafer rotation is then stopped 
       FIG. 5  is a chart illustrating thickness of a TARC layer applied to hydrophobic surface versus the volume of TARC used to form the layer according to the control method of  FIG. 3 . In  FIG. 5 , the volume of TARC indicated was applied to several wafers using the control method illustrated in  FIG. 3  and described supra. A TARC volume of 5 ml is the nominal volume. It is readily seen that a minimum volume of about 2 ml of TARC is required to obtain a thickness close to a target thickness of about 650 Å. However, at a volume of 2 ml of TARC, many area of de-wets (no TARC coverage) are seen so in reality a minimum of 3 ml of TARC is required for a de-wet free coating. Note, the standard deviation of the TARC thickness becomes unacceptable at volumes of about 4.0 ml or less. 
       FIG. 6  is a chart illustrating thickness of a TARC layer applied to hydrophobic surface versus the volume of TARC used to form the layer according to the method of the present invention of  FIG. 4 . The method of the present invention is referred to as the water pretreatment process on several occasions hereafter. In  FIG. 6 , the volume of TARC indicated was applied to several wafers using the method of the present invention illustrated in  FIG. 4  and described supra. In  FIG. 6 , it is readily seen that a minimum volume of about 0.3 ml of TARC is required to obtain a thickness close to a target thickness of about 650 Å. In other studies a minimum volume of 0.15 ml of TARC was required to give a uniform thickness TARC layer. This is about 15% of the 2 ml minimum volume of TARC volume required for the control method and about 6% of the 5 ml nominal volume of TARC used in the control method. Note, the standard deviation of the TARC thickness remained acceptable down to a TARC dispense volume of about 0.3 ml in this study. In other studies the TARC dispense volume was about 0.15 ml. 
       FIG. 7  is a chart, illustrating image size control versus the volume of TARC applied according to the method of the present invention. In  FIG. 7 , both the top of a resist image and a bottom of the resist image at several positions on a wafer (several wafers per dispense volume) are plotted as well as the standard deviation of the measured linewidths. It can be readily seen that top and bottom image size remain nearly constant and the uniformity remains consistent with TARC dispense volumes as low as 0.3 ml. In other studies image size uniformity was obtained with a TARC dispense volume of 0.15 ml. Note, image sizes were measured on a commercially available critical dimension scanning electron microscopes (CD SEM) with edge detection/measurement software. 
       FIG. 8  is a chart comparing the control method and the method of the present invention to resist thickness versus the size of subsequently printed and developed images. In  FIG. 8 , image size versus resist thickness is plotted for nominal control process of  FIG. 3  (using a TARC dispense volume about 5 ml) and for the method of the present invention (TARC dispense volume about 0.5 ml) at a constant exposure energy. The chart of  FIG. 8  shows that the method of the present invention did not significantly, if at all, alter the anti-reflective properties (i.e. index of refraction or TARC thickness) as there is little difference between the amplitudes of the control method and the water pre-treatment method. In addition there is very little difference in resist thickness. 
     It is possible for tool type and tool-to-tool differences of the water and TARC apply tool to affect the accuracy and repeatability of a process. TABLE III lists experimental measurements of TARC thickness and thickness standard deviation for the control process of  FIG. 3  using techniques of a TARC dispense volume of 5 ml and the water pretreatment method of  FIG. 4  using a TARC dispense volume of 0.5 ml, both techniques using TARC material AZ Aquatar (see TABLE II supra) various tools. 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE III 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Water 
                   
               
               
                   
                   
                 Control 
                 Control 
                 Water 
                 Pretreatment 
                 Water 
               
               
                   
                   
                 Wafer to 
                 within 
                 Pretreatment 
                 Wafer to 
                 Pretreatment 
               
               
                   
                   
                 Wafer 
                 Wafer 
                 Mean 
                 Wafer 
                 within Wafer 
               
               
                   
                 Control Mean 
                 Std Dev 
                 Std Dev 
                 Thickness 
                 Std Dev 
                 Std Dev 
               
               
                 Tool 
                 Thickness (Å) 
                 (Å) 
                 (Å) 
                 (Å) 
                 (Å) 
                 (Å) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 A 
                 669 
                 14.5 
                 3.0 
                 648 
                 5.2 
                 3.4 
               
               
                 B 
                 653 
                 13.0 
                 3.2 
                 655 
                 8.6 
                 4.0 
               
               
                 C 
                 660 
                 4.4 
                 2.4 
                 644 
                 5.5 
                 3.3 
               
               
                 D 
                 663 
                 11.3 
                 2.7 
                 667 
                 5.5 
                 3.1 
               
               
                 E 
                 665 
                 12.5 
                 4.8 
                 668 
                 9.6 
                 3.9 
               
               
                   
               
             
          
         
       
     
     The data in TABLE III indicates that there is essentially no difference in TARC thickness or with wafer standard deviation between the control method and the method of the present invention and that the wafer to wafer standard deviation of the method of the present invention is superior to the wafer to wafer standard deviation of the control process for AZ Aquatar. 
     TABLE IV lists experimental measurements of TARC thickness and thickness standard deviation for the control process of  FIG. 3  using techniques of a TARC dispense volume of 5 ml and the water pretreatment method of  FIG. 4  using a TARC dispense volume of 0.3 ml, both techniques using TARC material JSR NFC-540 (see TABLE II supra). 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE IV 
               
               
                   
               
               
                   
                   
                   
                   
                   
                 Water 
                   
               
               
                   
                   
                 Control 
                 Control 
                 Water 
                 Pretreatment 
                 Water 
               
               
                   
                   
                 Wafer to 
                 within 
                 Pretreatment 
                 Wafer to 
                 Pretreatment 
               
               
                   
                   
                 Wafer 
                 Wafer 
                 Mean 
                 Wafer 
                 within Wafer 
               
               
                   
                 Control Mean 
                 Std Dev 
                 Std Dev 
                 Thickness 
                 Std Dev 
                 Std Dev 
               
               
                 Tool 
                 Thickness (Å) 
                 (Å) 
                 (Å) 
                 (Å) 
                 (Å) 
                 (Å) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 A 
                 335 
                 12.2 
                 4.9 
                 336 
                 5.0 
                 2.5 
               
               
                 B 
                 335 
                 10.1 
                 4.7 
                 335 
                 6.5 
                 2.9 
               
               
                 C 
                 335 
                 7.9 
                 6.8 
                 336 
                 5.9 
                 2.6 
               
               
                   
               
             
          
         
       
     
     The data in TABLE IV indicates that there is essentially no difference in TARC thickness between the control method and the method of the present invention and that the uniformity (as measured by wafer to wafer and within wafer standard deviation) of the method of the present invention is superior to the uniformity of the control process for JSR NFC-540. 
       FIGS. 9A ,  9 B and  9 C are cross-sectional views through a TARC dispense nozzle as illustrated in  FIG. 2D . In  FIG. 9A , a TARC dispense nozzle  210 A has a length L and a uniform bore  250  having a maximum cross-sectional dimension of B 1 . TARC dispense nozzle  210 A has a tip  255 . In one example, bore  250  has a circular cross-section any place along length L. In one example B 1  is between about 0.5 millimeters and about 2.0 millimeters. In  FIG. 9B , a TARC dispense nozzle  210 B has an over all length L and an upper bore  260  having a length L 1  and a lower bore  265  having a length L 2 . Lower bore  265  is proximate to tip  255 . Lower bore  265  has a maximum cross-sectional dimension of B 1 . Upper bore  260  has a maximum cross-sectional dimension of B 2 , where B 2 &gt;B 1 . In one example, upper bore  260  and lower bore  265  each have a circular cross-section any place along respective lengths L 2  and L 1 . In  FIG. 9C , a TARC dispense nozzle  210 C has over all length L and a bore  270  having a restriction  275  Bore  275  has a maximum cross-sectional dimension of B 1 . Restriction  275  has a maximum cross-sectional dimension of B 2 . In one example, bore  270  has a circular cross-section any place along lengths L. In one example, opening  280  in tip  255  has a maximum cross-section dimension between B 1  and B 2 . In one example, opening  280  in tip  255  has a maximum cross-section dimension equal to or greater than B 1 . In one example, opening  280  in tip  255  has a maximum cross-section dimension equal to or greater than B 2 . 
     At maximum cross-section dimension B 1  of the bore of the TARC application nozzle, the small quantities of TARC material described supra, can be dispensed at a slower rate. In one example, the TARC dispense rate is between about 0.1 milliliter per second to about 0.4 milliliter per second. These slow TARC dispense rates, provide time for the TARC to spread with a more uniform thickness over the surface of the photoresist layer without defects such as voids and streaks. TARC dispense rates between about 0.1 milliliter per second to about 0.4 milliliter per second reduce the acceleration and maximum spin speed required as well. 
     Thus, the present invention provides a method to reduce the amount of material required to form a uniform layer on a hydrophobic surface. 
     The description of the embodiments of the present invention is given above for the understanding of the present invention. It will be understood that the invention is not limited to the particular embodiments described herein, but is capable of various modifications, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. For example, small quantities of additives such as surfactants may be added to the water dispensed prior to TARC application. Therefore, it is intended that the following claims cover all such modifications and changes as fall within the true spirit and scope of the invention.