Abstract:
A substrate holder is defined to support a substrate. A rotating mechanism is defined to rotate the substrate holder. An applicator is defined to extend over the substrate holder to dispense a cleaning material onto a surface of the substrate when present on the substrate holder. The applicator is defined to apply a downward force to the cleaning material on the surface of the substrate. In one embodiment the cleaning material is gelatinous.

Description:
CLAIM OF PRIORITY 
       [0001]    This application is a Divisional application of U.S. patent application Ser. No. 11/519,354, filed on Sep. 11, 2006, entitled “Method and System for Using a Two-Phases Substrate Cleaning Compound,” which 1) claims the benefit of U.S. Provisional Patent Application No. 60/755,377, filed on Dec. 30, 2005, and 2) is a Continuation-In-Part of U.S. patent application Ser. No. 10/608,871, filed on Jun. 27, 2003. The disclosure of each above-identified patent application is incorporated in its entirety herein by reference. 
       CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0002]    This application is related to the following U.S. patent applications: 
         [0003]    U.S. patent application Ser. No. ______ , filed on even date herewith, and entitled “Two-Phase Substrate Cleaning Material;” 
         [0004]    U.S. patent application Ser. No. 10/816,337, filed on Mar. 31, 2004, and entitled “Apparatuses and Methods for Cleaning a Substrate,” now U.S. Pat. No. 7,441,299; 
         [0005]    U.S. patent application Ser. No. 11/173,132, filed on Jun. 30, 2005, and entitled “System and Method for Producing Bubble Free Liquids for Nanometer Scale Semiconductor Processing,” now U.S. Pat. No. 7,452,408; 
         [0006]    U.S. patent application Ser. No. 11/153,957, filed on Jun. 15, 2005, and entitled “Method and Apparatus for Cleaning a Substrate Using Non-Newtonian Fluids;” 
         [0007]    U.S. patent application Ser. No. 11/154,129, filed on Jun. 15, 2005, and entitled “Method and Apparatus for Transporting a Substrate Using Non-Newtonian Fluid,” now U.S. Pat. No. 7,416,370; 
         [0008]    U.S. patent application Ser. No. 11/174,080, filed on Jun. 30, 2005, and entitled “Method for Removing Material from Semiconductor Wafer and Apparatus for Performing the Same;” 
         [0009]    U.S. patent application Ser. No. 10/746,114, filed on Dec. 23, 2003, and entitled “Method and Apparatus for Cleaning Semiconductor Wafers using Compressed and/or Pressurized Foams, Bubbles, and/or Liquids,” now U.S. Pat. No. 7,568,490; and 
         [0010]    U.S. patent application Ser. No. 11/336,215 filed on Jan. 20, 2006, and entitled “Method and Apparatus for Removing Contamination from Substrate,” now U.S. Pat. No. 7,648,584. 
         [0011]    The disclosure of each above-identified patent application is incorporated in its entirety herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0012]    In the fabrication of semiconductor devices such as integrated circuits, memory cells, and the like, a series of manufacturing operations are performed to define features on semiconductor substrates (“substrates”). During the series of manufacturing operations, the substrate surface is exposed to various types of contaminants. Essentially any material present in a manufacturing operation is a potential source of contamination. For example, sources of contamination may include process gases, chemicals, deposition materials, etch by-products, and liquids, among others. The various contaminants may deposit on the wafer surface in particulate form (particles). 
         [0013]    The surface of semiconductor substrates must be cleaned of substrate contaminants. If not removed, the devices within the vicinity of the contamination will likely be inoperable. Substrate contaminants may also affect device performance characteristics and cause device failure to occur at faster rates than usual. Thus, it is necessary to clean contaminants from the substrate surface in a substantially complete manner without damaging the substrate surface and the features defined on the substrate. The size of particulate contamination is often on the order of the critical dimension size of features fabricated on the wafer. Removal of such small particulate contamination without adversely affecting the surface and features on the substrate can be quite difficult. 
         [0014]    In view of the foregoing, there is a need for an improved substrate cleaning technique to remove contaminants from substrate surface to improve device yield. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    Broadly speaking, the embodiments fill the need by providing improved substrate cleaning techniques to remove contaminants from the substrate surface to improve device yield. It should be appreciated that the present invention can be implemented in numerous ways, including as a solution, a method, a process, an apparatus, or a system. Several inventive embodiments of the present invention are described below. 
         [0016]    In one embodiment, a cleaning compound to remove particulate contaminants from a semiconductor substrate surface is provided. The cleaning compound includes a viscous liquid with a viscosity between about 1 cP to about 10,000 cP. The cleaning compound also includes a plurality of solid components dispersed in the viscous liquid, the plurality of solid components interact with the particulate contaminants on the substrate surface to remove the particulate contaminants from the substrate surface. 
         [0017]    In another embodiment, an apparatus for cleaning particulate contaminants from a substrate surface of a substrate is provided. The apparatus includes a substrate support assembly for holding the substrate. The apparatus also includes an applicator to dispense a cleaning compound to clean the particulate contaminants from the substrate surface, wherein the cleaning compound is a viscous liquid having a viscosity between about 1 cP to about 10,000 cP at the shear rate of 1 per second and a plurality of solid components are dispersed in the viscous liquid. 
         [0018]    In yet another embodiment, a method to clean particulate contaminants from a substrate surface is provided. The method includes applying a viscous liquid having solid components dispersed therein to the substrate surface. The method also includes applying a force having a down-ward component and a shear component to the viscous liquid to bring at least one solid component within proximity of a particulate contaminant on the substrate surface. The method further includes removing the at least one solid component and the particulate contaminant away from the substrate surface. 
         [0019]    In one embodiment, an apparatus is disclosed for cleaning particulate contaminants from a semiconductor substrate surface. The apparatus includes a substrate holder defined to support a substrate. The apparatus also includes a rotating mechanism defined to rotate the substrate holder. The apparatus further includes an applicator defined to extend over the substrate holder to dispense a cleaning material onto a surface of the substrate when present on the substrate holder. The applicator is defined to apply a downward force to the cleaning material on the surface of the substrate. 
         [0020]    In one embodiment, an apparatus is disclosed for cleaning particulate contaminants from a semiconductor substrate surface. The apparatus includes a substrate holder defined to support a substrate. The apparatus also includes a rotating mechanism defined to rotate the substrate holder. The apparatus further includes an applicator defined to extend over the substrate holder to dispense a gelatinous cleaning material through multiple dispense holes onto a surface of the substrate when present on the substrate holder. The gelatinous cleaning material is dispensed between the substrate and the applicator. The applicator is defined to apply a downward force to the gelatinous cleaning material on the surface of the substrate. 
         [0021]    Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1A  shows a physical diagram of a cleaning solution for removing particulate contamination from a substrate surface, in accordance with one embodiment of the present invention; 
           [0023]      FIG. 1B  shows a physical diagram of a cleaning solution with a gel and a network of solid compounds; 
           [0024]      FIG. 1C  shows a diagram of stress and viscosity as a function of shear rate for a non-Newtonian fluid; 
           [0025]      FIG. 1D  shows a physical diagram of a solid component of the cleaning solution of  FIG. 1A  in the proximity of a contaminant on the substrate surface; 
           [0026]      FIG. 1E  shows a physical diagram of solid component of the cleaning solution of  FIG. 1A  making contact with contaminant on the substrate surface; 
           [0027]      FIG. 1F  shows a physical diagram of solid component of the cleaning solution of  FIG. 1A  moving contaminant away from the substrate surface; 
           [0028]      FIG. 2  shows an embodiment of a process flow for removing particulate contaminants from the surface of a substrate; and 
           [0029]      FIG. 3  shows a schematic diagram of an embodiment of a substrate surface cleaning system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Several exemplary embodiments for improved substrate cleaning technique to remove particulate contaminants from the substrate to improve process yield are provided. It should be appreciated that the present invention can be implemented in numerous ways, including as a solution, a process, a method, an apparatus, or a system. Several inventive embodiments of the present invention are described below. It will be apparent to those skilled in the art that the present invention may be practiced without some or all of the specific details set forth herein. 
         [0031]    The embodiments described herein provide for a cleaning technique that eliminates the need for abrasive contact and is efficient at cleaning contaminants from semiconductor substrates, some of which may contain high aspect ratio features. While the embodiments provide specific examples related to semiconductor cleaning applications, these cleaning applications may be extended to any technology requiring the removal of contaminants from a substrate. As described below, a cleaning solution having a continuous liquid phase and a dispersed solid phase is provided. Solid particles are dispersed throughout the liquid phase. 
         [0032]      FIG. 1A  shows a physical diagram of a cleaning solution (or compound)  101  for removing contaminants  103  from a surface  106  of a semiconductor substrate  105 , in accordance with one embodiment of the present invention. The cleaning solution  101  includes a viscous liquid  107 , and solid components  109 . The solid components  109  are dispersed within the viscous liquid  107 . The viscous liquid  107  provides a vehicle to bring the solid components  109  proximate to the contaminants  103  in order for the solid components  109  and the contaminants  103  to interact to eventually remove the contaminants  103  from the substrate surface  106 . In one embodiment, the solid components  109  are hydrolyzed by a chemical agent, or by added surfactant. In one embodiment, the cleaning solution  101  can be prepared by dissolving a carboxylic acid solid in de-ionized water (DIW) with a weight/weight percent greater than 2%. The solid compounds  109  are carboxylic acid solids precipitated from dissolved carboxylic acid in the DIW. In one embodiment, the carbon number of the carboxylic acid is ≧4. The dissolved carboxylic acid would form a viscous liquid  107  with a viscosity between 1 cP (centi-Poise) to about 10,000 cP at the shear rate of 1 per second. One thing to note is that the cleaning compound (or solution) can be made by mixing carboxylic acid(s) (or salts) in solvents other than water. Other polar or non-polar solvents, such as alcohol, can also be used. 
         [0033]    The solid components  109  are dispersed in suspension within the viscous liquid  107 . In one embodiment, the viscous liquid  107  is a gel that combines with a network of solid components  109  to form the cleaning compound  101 , which can be applied on the substrate surface  106 , as shown in  FIG. 1B . The solid components  109  interact with one another to form the network of solid compound through van der Waals forces. The solid components  109  are suspended within the viscous liquid  107 , which is in the form of a gel. The relatively high viscosity of the gel allows a force applied on the gel to transmit the force on the solid compound in the gel. The cleaning compound  101 , as shown in  FIG. 1B , can be formed by mixing higher concentration of the carboxylic acid solids, such as between about 3% to about 5% and preferably between about 4% to about 5%, with DIW. In one embodiment, the mixture of carboxylic acid solids and DIW can be heated to about 75° C. to about 85° C. to shorten the duration for the solids to be dissolved in DIW. Once the solids are dissolved, the cleaning solution can be cooled down. During the cooling down process, solid compounds in the form of needles or plates would precipitates. 
         [0034]    In one embodiment, the viscous liquid  107  is a non-Newtonian fluid whose viscosity decreases with the increase of shear rate. However, the viscous fluid  107  can be a Newtonian fluid.  FIG. 1C  shows a diagram of a non-Newtonian fluid of the described embodiment. The viscosity approaches zero when the shear rate is very high. The viscosity of the non-Newtonian fluid decreases as the shear rate increases. During the cleaning operation, a certain range of shear rate is selected. As an example, a liquid gel with 3-4 weight/weight % carboxylic acid in DIW has a viscosity of about 1000 cP at 0.1 per second shear rate and the viscosity falls to about 10 cP when the shear rate increases to 1000 per second. 
         [0035]    As described above, the viscous liquid  107  has a viscosity between about 10 cP to about 10,000 cp. When a shear force is applied on a surface of the solution  101 , the viscous liquid  107  can transfer part of the shear force to the solid compounds  109 . The solid compounds  109  would contact contaminants  103  and move the contaminants away from the substrate surface. 
         [0036]    It should be understood that depending on the particular embodiment, the solid components  109  within the cleaning material  101  may possess physical properties representing essentially any sub-state within the solid phase, wherein the solid phase is defined as a phase other than liquid or gas. For example, physical properties such as elasticity and plasticity can vary among different types of solid components  109  within the cleaning material  101 . Additionally, it should be understood that in various embodiments the solid components  109  can be defined as crystalline solids or non-crystalline solids. Regardless of their particular physical properties, the solid components  109  within the cleaning material  101  should be capable of avoiding adherence to the surface of substrate surface  106  when positioned in either close proximity to or in contact with the substrate surface  106 . Additionally, the mechanical properties of the solid components  109  should not cause damage to the substrate surface  106  during the cleaning process. In one embodiment, the hardness of the solid components  109  is less than the hardness of the substrate surface  106 . 
         [0037]    Furthermore, the solid components  109  should be capable of establishing an interaction with the contaminants  103  present on the substrate surface  106  when positioned in either close proximity or contact with the contaminants  103 . For example, the size and shape of the solid components  109  should be favorable for establishing the interaction between the solid components  109  and the contaminants  103 . In one embodiment, the solid compounds  109  have cross-sectional areas greater than the cross-sectional areas of the contaminants. As shown in  FIG. 1D , when a solid compound  109 ′ with a large surface area A 109′  compared to the surface area A 103′  of a particulate contaminant  103 ′, the shear force F S′  exerted on the solid compound  109 ′ is transmitted upon the particulate contaminant  103 ′ at a shear force multiplied roughly by the area ratio (F S ′×A 109′ /A 103′ ). For example, the effective diameter D of the particulate contaminant  103 ′ is less than about 0.1 micron. The width W and length L of the solid compound  109 ′ are both between about 5 micron to about 50 micron and the thickness of the solid compound  109 ′ is between about 1 micron to about 5 micron. The area ratio (or force multiplier) could be between 2,500 to about 250,000 or greater. The shear force exerted on the particulate contaminant  103 ′ could be very large and could dislodge particulate contaminant  103 ′ from the substrate surface  106 . 
         [0038]    Energy transferred from the solid component  109 ′ to the contaminant  103 ′ can occur through direct or indirect contact and may cause the contaminant  103 ′ to be dislodged from the substrate surface  106 . In this embodiment, the solid component  109 ′ may be softer or harder than the contaminant  103 ′. If the solid component  109 ′ is softer than the contaminant  103 ′, greater deformation of the solid component  109 ′ is likely to occur during the collision, resulting in less transfer of kinetic energy for dislodging the contaminant  103 ′ from the substrate surface  106 . In the case where the solid component  109 ′ is softer than the contaminant  103 ′, the adhesive connection between the solid component  109 ′ and the contaminant  103 ′ may be stronger. Conversely, if the solid component  109 ′ is at least as hard as the contaminant  103 ′, a substantially complete transfer of energy can occur between the solid component  109 ′ and the contaminant  103 ′, thus increasing the force that serves to dislodge the contaminant  103 ′ from the substrate surface  106 . However, in the case where the solid component  109 ′ is at least as hard as the contaminant  103 ′, interaction forces that rely on deformation of the solid component  109 ′ may be reduced. It should be appreciated that physical properties and relative velocities associated with the solid component  109 ′ and the contaminant  103 ′ will influence the collision interaction there between. 
         [0039]      FIGS. 1E and 1F  show another embodiment of how the cleaning material  101  functions to remove the contaminant  103  from the substrate surface  106 . During the cleaning process a downward force F D , which is a downward component of force F, is exerted on the solid components  109  within the viscous liquid  107  such that the solid components  109  are brought within close proximity or contact with the contaminants  103  on the substrate surface  106 . The relatively high viscosity of the viscous liquid  107  enables a significant portion of the downward force applied on the viscous liquid  107  to be exerted on the solid components  109 . When the solid component  109  is forced within sufficient proximity to or contact with the contaminant  103 , an interaction is established between the solid component  109  and the contaminant  103 . The interaction between the solid component  109  and the contaminant  103  is sufficient to overcome an adhesive force between the contaminant  103  and the substrate surface  106 , as well as any repulsive forces between the solid component  109  and the contaminant. Therefore, when the solid component  109  is moved away from the substrate surface  106  by a sheer force F S , which is a shear component for force F, the contaminant  103  that interacted with the solid component  109  is also moved away from the substrate surface  106 , i.e., the contaminant  103  is cleaned from the substrate surface  106 . In one embodiment, the interaction between the solid component  109  and contaminant  103  occurs when the solid component  109  is forced sufficiently close to the contaminant  103 . In one embodiment, this distance may be within about  10  nanometers. In another embodiment, the interaction between the solid component  109  and contaminant  103  occurs when the solid component  109  actually contacts the contaminant  103 . This interaction may also be referred to as solid component  109  engaging contaminant  103 . 
         [0040]    The interaction force between the solid component  109  and the contaminant  103  is stronger than the force connecting the contaminant  103  to the substrate surface  106 .  FIG. 1F , shows when a solid component  109  is moved away from the substrate surface  106 , the contaminant  103  bound to the solid component  109  is also moved away from the substrate surface  106 . It should be noted that multiple contaminant removal mechanisms can occur during the cleaning process. 
         [0041]    It should be appreciated that because the solid components  109  interact with the contamination  103  to affect the cleaning process, contamination  103  removal across the substrate surface  106  will be dependent on how well the solid components  109  are distributed across the substrate surface  106 . In a preferred embodiment, the solid components  109  will be so well distributed that essentially every contaminant  103  on the substrate surface  106  will be in proximity to at least one solid component  109 . It should also be appreciated that one solid component  109  may come in contact with or interact with more than one contaminant  103 , either in a simultaneous manner or in a sequential manner. Furthermore, solid component  109  may be a mixture of different components as opposed to all the same component. Thus, the cleaning solution is capable of being designed for a specific purpose, i.e., targeting a specific contaminant, or the cleaning solution can have a broad spectrum of contaminant targets where multiple solid components are provided. 
         [0042]    Interaction between the solid component  109  and the contaminant  103  can be established through one or more mechanisms including adhesion, collision, and attractive forces, among others. Adhesion between the solid component  109  and contaminant  103  can be established through chemical interaction and/or physical interaction. For example, in one embodiment, chemical interaction causes a glue-like effect to occur between the solid component  109  and the contaminant  103 . In another embodiment, physical interaction between the solid component  109  and the contaminant  103  is facilitated by the mechanical properties of the solid component  109 . For example, the solid component  109  can be malleable such that when pressed against the contaminant  103 , the contaminant  103  becomes imprinted within the malleable solid component  109 , In another embodiment, the contaminant  103  can become entangled in a network of solid components  109 . In this embodiment, mechanical stresses can be transferred through the network of solid components  109  to the contaminant  103 , thus providing the mechanical force necessary for removal of the contaminant  103  from the substrate surface  106 . 
         [0043]    Deformation of the solid component  109  due to imprinting by the contaminant  103  creates a mechanical linkage between the solid component  109  and the contaminant  103 . For example, a surface topography of the contaminant  103  may be such that as the contaminant  103  is pressed into the solid component  109 , portions of the solid component  109  material enters regions within the surface topography of the contaminant  103  from which the solid component  109  material cannot easily escape, thereby creating a locking mechanism. 
         [0044]    In addition to the foregoing, in one embodiment, interaction between the solid component  109  and contaminant  103  can result from electrostatic attraction. For example, if the solid component  109  and the contaminant  103  have opposite surface charges they will be electrically attracted to each other. It is possible that the electrostatic attraction between the solid component  109  and the contaminant  103  can be sufficient to overcome the force connecting the contaminant  103  to the substrate surface  106 . 
         [0045]    In another embodiment, an electrostatic repulsion may exist between the solid component  109  and the contaminant  103 . For example, both the solid component  109  and the contaminant  103  can have either a negative surface charge or a positive surface charge. If the solid component  109  and the contaminant  103  can be brought into close enough proximity, the electrostatic repulsion there between can be overcome through van der Waals attraction. The force applied by the viscous liquid  107  to the solid component  109  may be sufficient to overcome the electrostatic repulsion such that van der Waals attractive forces are established between the solid component  109  and the contaminant  103 . 
         [0046]    Additionally, in another embodiment, the pH of the viscous liquid  107  can be adjusted to compensate for surface charges present on one or both of the solid component  109  and contaminant  103 , such that the electrostatic repulsion there between is reduced to facilitate interaction, or so that either the solid component or the contamination exhibit surface charge reversal relative to the other resulting in electrostatic attraction. For example, a base, such as Ammonium Hydroxide (NH 4 OH), can be added to a carboxylic acid gel, made by dissolving 3-4% of a carboxylic acid in DIW, with fatty acid solid components to increase the pH value of the gel (viscous liquid). The amount of NH 4 OH added is between about 0.05% to about 5%, preferably between about 0.25% to about 2%. Ammonium Hydroxide helps the fatty acid solids to be hydrolyzed and to be dispersed in the gel. Ammonium Hydroxide can also hydrolyze the contaminants  103 . To clean metal contaminants, lower pH solution can also be used. Buffered HF solution can be used to tune the pH value to be between about 6 to about 8. 
         [0047]    In addition to using a base, such as Ammonium Hydroxide, to enhance cleaning efficiency, a surfactant, such as ammonium dodecyl sulfate, CH 3 (CH 2 ) 11 OSO 3 NH 4 , can also be added to the carboxylic acid gel. In one embodiment, about 0.1% to about 5% of surfactant is added to the cleaning solution  101 . In a preferred embodiment, about 0.5% to about 2% surfactant is added to the cleaning solution  101 . 
         [0048]    In addition, the solid components  109  should avoid dissolution or having limited solubility in the viscous liquid  107 , and should have a surface functionality that enables dispersion throughout the viscous liquid  107 . For solid components  109  that do not have surface functionality that enables dispersion throughout the liquid medium  107 , chemical dispersants may be added to the liquid medium  107  to enable dispersion of the solid components  109 . Depending on their specific chemical characteristics and their interaction with the surrounding viscous liquid  107 , solid components  109  may take one or more of several different forms. For example, in various embodiments the solid components  109  may form aggregates, colloids, gels, coalesced spheres, or essentially any other type of agglutination, coagulation, flocculation, agglomeration, or coalescence. In other embodiments, the solid components  109  may take a form not specifically identified herein. Therefore, the point to understand is that the solid components  109  can be defined as essentially any solid material capable of functioning in the manner previously described with respect to their interaction with the substrate surface  106  and the contaminants  103 . 
         [0049]    Some exemplary solid components  109  include aliphatic acids, carboxylic acids, paraffin, cellulose, wax, polymers, polystyrene, polypeptides, and other visco-elastic materials. The solid component  109  material should be present at a concentration that exceeds its solubility limit within the viscous liquid  107 . In addition, it should be understood that the cleaning effectiveness associated with a particular solid component  109  material may vary as a function of temperature, pH, and other environmental conditions. 
         [0050]    The aliphatic acids represent essentially any acid defined by organic compounds in which carbon atoms form open chains. A fatty acid is an example of an aliphatic acid and an example of a carboxylic acid that can be used as the solid components  109  within the cleaning material  101 . Examples of fatty acids that may be used as the solid components  109  include lauric, palmitic, stearic, oleic, linoleic, linolenic, arachidonic, gadoleic, eurcic, butyric, caproic, caprylic, myristic, margaric, behenic, lignoseric, myristoleic, palmitoleic, nervanic, parinaric, timnodonic, brassic, clupanodonic acid, lignoceric acid, cerotic acid, and mixtures thereof, among others. In one embodiment, the solid components  109  can represent a mixture of fatty acids defined by various carbon chain lengths extending from C4 to about C-26. Carboxylic acids are defined by essentially any organic acid that includes one or more carboxyl groups (COOH). Also, the carboxylic acids can include other functional groups such as but not limited to methyl, vinyl, alkyne, amide, primary amine, secondary amine, tertiary amine, azo, nitrile, nitro, nitroso, pyrifyl, carboxyl, peroxy, aldehyde, ketone, primary imine, secondary imine, ether, ester, halogen isocyanate, isothiocyanate, phenyl, benzyl, phosphodiester, sulfhydryl, but still maintaining insolubility in the viscous liquid  107 . 
         [0051]    Additionally, the surface functionality of the solid component  109  materials can be influenced by the inclusion of moieties that are miscible with the viscous liquid  107 , such as carboxylate, phosphate, sulfate groups, polyol groups, ethylene oxide, etc. The point to be understood is that the solid components  109  should be dispersible in a substantially uniform manner throughout the viscous liquid  107  such that the solid components  109  avoid clumping together into a form that cannot be forced to interact with the contaminants  103  present on the substrate  105 . 
         [0052]    It should be understood that the viscous liquid  107  can be modified to include ionic or non-ionic solvents and other chemical additives. For example, the chemical additives to the viscous liquid  107  can include any combination of co-solvents, pH modifiers, chelating agents, polar solvents, surfactants, ammonium hydroxide, hydrogen peroxide, hydrofluoric acid, tetramethylammonium hydroxide, and rheology modifiers such as polymers, particulates, and polypeptides. 
         [0053]      FIG. 2  is an illustration showing a flowchart of a method for removing contaminants from a substrate surface, in accordance with one embodiment of the present invention. It should be understood that the substrate referenced in the method of  FIG. 2  can represent a semiconductor wafer or any other type of substrate from which contaminants associated with a fabrication process need to be removed. Also, the contaminants referenced in the method of  FIG. 2  can represent essentially any type of surface contaminant associated with the semiconductor wafer fabrication process, including but not limited to particulate contamination, trace metal contamination, organic contamination, photoresist debris, contamination from wafer handling equipment, and wafer backside particulate contamination. 
         [0054]    The method of  FIG. 2  includes an operation  201  for disposing a cleaning material (or solution) over a substrate, wherein the cleaning material includes solid components dispersed within a viscous liquid, or a gel. The cleaning material referenced in the method of  FIG. 2  is the same as previously described with respect to  FIGS. 1A-1F . Therefore, the solid components within the cleaning material are dispersed in suspension within the viscous liquid. Also, the solid components are defined to avoid damaging the substrate and to avoid adherence to the substrate surface. 
         [0055]    The method also includes an operation  203  for applying a force to a solid component to bring the solid component within proximity to a contaminant present on the substrate, such that an interaction is established between the solid component and the contaminant. 
         [0056]    Additionally, in one embodiment, the method can include an operation for controlling a temperature of the cleaning material to enhance interaction between the solid component and the contaminant. More specifically, the temperature of the cleaning material can be controlled to control the properties of the solid component. For example, at a higher temperature the solid component may be more malleable such that it conforms better when pressed against the contaminant. Then, once the solid component is pressed and conformed to the contaminant, the temperature is lowered to make the solid component less malleable to better hold its conformal shape relative to the contaminant, thus effectively locking the solid component and contaminant together. The temperature may be used to control the viscosity of the viscous liquid. The temperature may also be used to control the solubility and therefore the concentration of the solid components. For example, at higher temperatures the solid component may be more likely to dissolve in the viscous liquid. The temperature may also be used to control and/or enable formation of solid components in-situ on the substrate from liquid-liquid suspension. In a separate embodiment, the method can include an operation for precipitating solids dissolved within the viscous liquid. This precipitation operation can be accomplished by dissolving the solids into a solvent and then adding a component that is miscible with the solvent but that does not dissolve the solid. 
         [0057]    The method further includes an operation  205  for moving the solid component away from the substrate surface such that the contaminant that interacted with the solid component is removed from the substrate surface. In one embodiment, the method includes an operation for controlling a flow rate of the cleaning material over the substrate to control or enhance movement of the solid component and/or contaminant away from the substrate. The method of the present invention for removing contamination from a substrate can be implemented in many different ways so long as there is a means for applying a force to the solid components of the cleaning material such that the solid components establish an interaction with the contaminants to be removed. 
         [0058]    In one embodiment, the method can include an operation of a final clean. In the operation of final clean, the substrate the cleaning material, that contains dislodged contaminants, is cleaned with a suitable chemical(s) that facilitates the removal of all the cleaning material from the substrate surface. For example, if the viscous liquid of the cleaning material is a carboxylic acid gel, NH 4 OH diluted in DIW could be used to remove carboxylic acid off the substrate surface. NH 4 OH hydrolyzes (or ionizes by deprotonating) the carboxylic acid and enables the hydrolyzed carboxylic acid to be lifted off the substrate surface. Alternatively, a surfactant, such as ammonium dodecyl Sulfate, CH 3 (CH 2 ) 11 OSO 3 NH 4 , can be added in DIW, to remove carboxylic acid gel off the substrate surface. 
         [0059]    In another embodiment, a rinse operation follows the final clean operation described above. After the final clean, the substrate surface can be rinsed with a liquid, such as DIW, to remove the chemical(s) used in the final clean from the substrate surface. The liquid used in final rinse should leave no chemical residue(s) on the substrate surface after it evaporates. 
         [0060]      FIG. 3  shows a schematic diagram of an embodiment of a substrate surface cleaning system  300 , System  300  has a container  307  that houses a substrate support assembly  304 . The substrate support assembly  304  has a substrate holder  305  that supports a substrate  301 . The substrate support assembly  304  is rotated by a rotating mechanism  310 . System  300  has a cleaning material dispensing assembly  303  that include a cleaning material applicator  306 . In the applicator  306 , there are multiple dispensing holes  308  that allow the cleaning material to be dispensed on the surface of substrate  301 . With the aid of the rotating mechanism  310 , the cleaning material  307  covers the entire substrate surface. In one embodiment, the applicator  306 , through the action of dispensing of the cleaning material, provides a down-ward force to cleaning material and to the substrate surface. The cleaning material can be pressed out of the applicator  306  by air pressure or by a mechanical pump. In another embodiment, the applicator  306  provides a down-ward force on the cleaning material on the substrate surface by a down-ward mechanical force. The rotating mechanism  310  provides a sheer force to the cleaning material and to the substrate surface. In one embodiment, the rotating mechanism  310  is rotated at a speed between about 1 round per minute (RPM) to about 100 RPM, preferably between about 5 RPM to about 30 RPM. The pressure exerted on the cleaning material (or compound) to push the cleaning material out of the applicator  306  is between about 5 PSI to about 20 PSI. Alternatively, the applicator  306  can rotates around the center of the substrate  301  to provide the shear force. 
         [0061]    In one embodiment, system  300  also includes a dispenser  320 , which can dispense DIW  321  on the substrate surface to clean the substrate surface of the cleaning material after the process of contaminant-removal by the cleaning material is completed. In another embodiment, the dispenser  320  can dispense a cleaning solution, such as NH 4 OH in DIW described above, on the substrate surface to hydrolyze the viscous liquid to enable the viscous liquid to be lifted off the substrate surface. Afterwards, the same dispenser  320  or a different dispenser (not shown) can dispense DIW to remove the cleaning solution from the substrate surface. 
         [0062]    While this invention has been described in terms of several embodiments, it will be appreciated that those skilled in the art upon reading the preceding specifications and studying the drawings will realize various alterations, additions, permutations and equivalents thereof. Therefore, it is intended that the present invention includes all such alterations, additions, permutations, and equivalents as fall within the true spirit and scope of the invention. hi the claims, elements and/or steps do not imply any particular order of operation, unless explicitly stated in the claims.