Abstract:
An improved polishing pad and process for polishing a multitude of materials is invented. The process includes steps to liberate material from the surface of the pad and in doing so form a desired surface texture for polishing, while allowing the bulk of the pad to remain solid and hence less compressible and stiffer. These material properties yield a polishing better suited for applications such as semiconductor wafer silicon dioxide, damascene tungsten metal, damascene copper polishing, and the like.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is entitled to the benefit of Provisional Patent Application Ser. No. 60/262999, dated Jan. 19, 2001. 
     
    
     
       BACKGROUND  
         [0002]    1. Field of the Invention  
           [0003]    This patent relates to the art of polishing pads, but not limited to the polishing of silicon wafers, semiconductor wafers, patterned packaging and circuit boards, compound semiconductors, gem stones and the like.  
           [0004]    2. Description of Prior Art  
           [0005]    Prior art teaches that polishing pads need surface texture (or topography) to effectively polish semiconductor wafers and the like. Several methods have been used to create such texture as cited in U.S. Pat. No. 5,489,233 including:  
           [0006]    1. Urethane Impregnated polyester felts (examples in U.S. Pat. No. 4,927,432) possess a micro texture derived from the ends of projecting fibers within the bulk composite, together with associated voids.  
           [0007]    2. Micro-porous urethane pads of the type sold as Politex by Rodel, Inc. of Newark, Del. have a surface texture derived from the ends of columnar void structures within the bulk of a urethane film which is grown on a urethane felt base.  
           [0008]    3. Filled and/or blown composite urethanes such as IC-series, Mh-series and LP-series polishing pads manufactured by Rodel, Inc. of Newark, Del. have a surface structure made up of semicircular depressions derived from the cross-section of exposed hallow spherical elements or incorporated gas bubbles.  
           [0009]    4. Abrasive-filled polymeric pads such as those of U.S. Pat. No. 5,209,760 possess a characteristic surface texture consisting of projections and recesses where filler grains are present or absent.  
           [0010]    In addition to these referenced methods, other methods of providing surface texture have been cited and patented.  
           [0011]    5. Sintering polymeric particles (U.S. Pat. No. 6,017,265), where the micro-texture is derived from the pre-sintered particles, gaps between particles and fused polymeric-particle-sections.  
           [0012]    6. Mechanically creating micro-texture via such methods as diamond pad conditioning (U.S. Pat. No. 5,489,233).  
           [0013]    Upon review, in all of these cases, successful pads for polishing semiconductor wafer and the like utilize at least 2 of 3 key levels of pad texturing:  
           [0014]    I. Macro texturing, such as pad grooving, which is on the scale of millimeters. This texture is usually formed by mechanical means, such as using a metallic cutting tools or some form of patterned molding.  
           [0015]    II. Intermediate scale—on the size scale of 5 to 250 microns (micro-meters=μm), usually in the form of a closed or an open pore structure.  
           [0016]    III. Micro-texture—on the scale of less than 5 microns, usually 2-3 microns. Micro-texture often is created by mechanical means, such as with diamond conditioning methods.  
           [0017]    The six above mentioned pad types create the necessary texturing for polishing all by different and distinct methods.  
           [0018]    In the examples discussed in the background section, the need for macro surface texturing is partially dictated by the availability of intermediate surface texturing. In cited methods 1 and 2, abundant intermediate texturing is available. Examples of these pads include Suba-4 and Politex polishing pads from Rodel Inc. of Newark, Del. When used for polishing Semiconductor wafers, these pads often do not need any surface macro-texturing such as grooving, embossing or perforating. With pads made by method 6, such as Rodel Inc. of Del. products examples of IC-2000 and OXP-3000, mechanical conditioning is used to create surface texture from a surface that starts out intentionally smooth. Methods such as diamond pad conditioning, generally speaking, create only a fine microstructure. These pads have a scarcity of intermediate texturing when compared to method examples 1 and 2. For method 6, macro-texturing is key to the polishing pads performance with respect to removal rate, uniformity and ability to sustain long polishes without significant rate drop. An example would include, glass polishing using a fumed silica slurry, such as Cabot SC-112. As a result, optimal macro-texturing is expected to vary from application to application.  
           [0019]    In addition to surface texture, the physical and mechanical properties of polishing pads are very important for certain application Semiconductor planarization application and the like, require a polishing pad system that can effectively be used to reduce the surface topography from several thousands of Angstroms to below one-thousand Angstroms. Planarization performance is affected by pad topography (when excessive) &lt;physical shape&gt;, pad stiffness &lt;bending&gt;, pad hardness, pad thickness and pad compressibility. Many of these performance factors are affected by the sub-pad, when using a “stacked pad”. First order effects for pad planarization performance are pad stiffness, as determined by the pad modules and then pad thickness (Stiffness=modulus/thickness 3 ). Stiff pads tend to be “hard”, so often this term is used in place of “stiff” in the literature.  
           [0020]    Currently, two types of polishing pads are used predominantly for Semiconductor wafer planarization; Rodel&#39;s IC-1000 (method 3) and OXP-3000 (method 6) type polishing pads. In the case of the IC-1000 stacked pad on a Suba-4 or similar, the polishing planarization distance is approximately 2.5 cm (ref. D. Oma, P. Burke). When using similar OXP-3000 based pads, the planarization distances are improved to 3-4 cm, when comparing similar thicknesses (0.05 inches). The IC-1000 polishing matrix is stiffer than that used in the OXP-3000, yet the planarization length is shorter. The IC-1000 contains a high percentage of void space, greater than 20%. The OXP-3000 pad is a solid material. The void spaces, or “hollow microsphere” used the IC-1000, allow for this material to bend, compress, expand and act as a more compliant material than the OXP-3000, by virtue of the added “void space”. The combination of the IC-1000 base material and void spaces yields a lower combined materials modulus than that of the OXP-3000. The design of the IC-1000 limits the achievable planarization distance.  
           [0021]    Currently there are many polishing pads available and many methods to make these pads. All of these methods have their limitations. Method 3 is used to manufacture the industry standard IC-1000 polishing pad, by Rodel Inc. The void spaces in this pad limit the planarization length achievable with this pad. Other methods, to date, have been unable to render a polishing pad with adequate planarization performance or that contain the necessary intermediate surface texture necessary to provide a stable polishing pad.  
           [0022]    This invention teaches a new method of forming and using polishing pads that offers the needed combination of a solid and stiff bulk material with the said needed density of intermediate surface texture. The invention further teaches that the creation of well controlled and reproducible intermediate texturing is critical to formation of a desirable polishing pad.  
         SUMMARY  
         [0023]    A polishing pad is formed, consisting of two distinct material phases. The first phase is the polishing pad matrix material The second phase consist of a dispersion of substantially void-free particles or pockets in the polishing pad matrix material. In this invention, the said second phase material is liberated from the pad when in contact with the surface of the pad, by a variety of methods. This invention offers a unique way of forming a solid polishing pad and simultaneously forming a controllable and reproducible surface texture. 
       
    
    
     DRAWINGS  
       [0024]    [0024]FIG. 1 is a schematic microscopic cross sectional and surface view of an article (polishing pad), in accordance to the present invention, after a surface pore has been created as described in this invention. Micro-texture is also shown as would be created by a diamond pad-conditioning process.  
         [0025]    [0025]FIG. 2 is a wider schematic microscopic cross sectional and surface view of an article (polishing pad), in accordance to the present invention, as made, prior to the creation of the surface pores.  
         [0026]    [0026]FIG. 3 is a wider schematic microscopic cross sectional and surface view of an article (polishing pad), in accordance to the present invention, after a surface pores have been formed from the structure shown initially in FIG. 2.  
         [0027]    [0027]FIG. 4 is a schematic microscopic cross sectional and surface view of an article (polishing pad), in accordance to the present invention, after the surface pores have been formed, with a detail of the role that cuts made from the conditioning process play in the formation of the surface pores.  
         [0028]    [0028]FIG. 5 is a schematic cross sectional surface view of an article (polishing pad), in accordance to the present invention, with the addition of macro-texturing groove cuts (the view does not include the detail shown in earlier figures).  
         [0029]    [0029]FIG. 6 is a schematic top surface view of an article (entire polishing pad), in accordance to the present invention, showing the conceptual design of concentric circular grooving which is used to create surface macro-texturing of a polishing pad.  
         [0030]    [0030]FIG. 7 is a schematic microscopic cross sectional surface view of an article (polishing pad), in accordance to the present invention. In this embodiment, the dispersed second phase has irregular shapes. Surface pores have been opened up by the liberation of the second phase.  
         [0031]    [0031]FIG. 8 is a schematic microscopic top surface view of two articles (polishing pads), both in accordance with the present invention. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0032]    Referring to the drawings, wherein like numerals indicate like elements throughout, there is shown in FIGS.  1 - 7  embodiments of an article of manufacture, generally designated  100 ,  200 ,  300 ,  400 ,  500 ,  600  and  700 , in accordance with the present invention.  
         [0033]    Preferably, the articles  100 ,  200 ,  300 ,  400 ,  500 ,  600 , and  700  are generally circular sheets or polishing pads, as best shown in FIG. 6( 600 ). One of ordinary skill in the art would understand that the pad  600 , may for example be square, rectangular, in long sheets or belts or any desired suitable shape.  
         [0034]    The article  400  et seq. of the present invention may be used as a polishing pad either by itself or as a substrate in a polishing operation in which a polishing fluid is used to provide a desired surface finish for semiconductor devices, silicon devices, crystals, glass, ceramic, polymeric plastic material, metal, stone or the like. Polishing pads  600  made with the article  400  et seq. of the present invention may be used with lubricants, coolants, and various abrasive and non-abrasive polishing slurries, all well known to those skilled in the art and readily available commercially.  
         [0035]    Intermediate texturing can limit the planarization applications of the polishing pad if this texturing either protrudes excessively (&gt;5 microns) from a localized surface plane of the polishing pad or if the material used in construction of the pad, which generated the intermediate texture, is too compliant and flexible. Hence this invention teaches that for beneficial planarization performance, surface texture on the intermediate scale (5-250 microns) should minimized the number or amount of protruding elements above the primary load bearing surface of the polishing pad Ideally, there should be only one said surface plane of the polishing pad, with-in the range of 1-5 μm of normal surface micro-texture.  
         [0036]    This invention teaches a unique method of achieving a superior polishing pad by creating surface intermediate scale-texture by a new and novel method. The new method includes building a polishing pad comprised of at least two distinct phases,  12  solid or substantially void-free particles (VFP) or void-free pockets (henceforth called VFP) and  11  polymeric pad matrix. Then in the course of polishing, pad conditioning, work-piece or pad cleaning or pad rinsing, these particles or pockets of substantially void free material are liberated from the pad preferably by rapidly chemically dissolving during a pad conditioning treatment. The release of the said VFP phase leaves the surface pore  14 , usually closed cell, which becomes the surface  13  intermediate texturing needed for polishing. By this design, this intermediate-scale texturing is nearly all recessed below the major load-bearing surface of the polishing pad (See FIGS. 3 and 4). Any protruding particle or pocket will, by the design of this invention, be liberated into the polishing, pad conditioning, or pad-cleaning environment, depending upon the method of particle liberation. Pore structures that act to hold the polishing fluid without escape are desired for maintaining good fluid-pad-work-piece contact. Closed cell pore designs, as described in this invention, act to hold the polishing fluid at the surface of the pad, when properly constructed.  
         [0037]    For the purpose of this invention, the abbreviated term, VFP, is defined as said space occupied by the said second phase of material which is either solid or substantially void free and may appear nearly round as a particle or follow irregular shapes such as a pocket or a vain of material.  
         [0038]    The shape and texture of the said pore structure will vary with the shapes formed by the VFP. In FIGS. 1, 2,  3 , and  4 , the VFP phase is nearly spherical. Top said pore structures are shaped like sliced spheres, As shown in FIGS.  1 ( 100 ),  3 ( 300 ),  4 ( 400 ) and  8 ( 300 ). The said VFP or second phase materials are essentially solid and can take irregular shapes as shown in FIGS.  7 ( 700 ) and  8 ( 700 ). The schematic top views in  
         [0039]    [0039]FIG. 8( 300  and  700 ) of the said pore structures give an example of the possible range of surface textures possible with the different embodiments of this invention. The size, shape, density and critical dimensions of the VFP phase are used in this invention, in part, to define the surface texture of the polishing pad.  
         [0040]    Methods for the liberation of the second phase or VFP  12  include but are not limited to:  
         [0041]    a) Chemical dissolution into the usually aqueous media of the polishing solution, pad or work-piece cleaning or rinsing solution or pad conditioning solution. This action may be enhanced by the addition of acids, bases, or dilute solvents into said above solutions.  
         [0042]    b) Chemical reactions with a contacting liquid or gas, which results in by-products which are liberated from the pad. This method may be enhanced by placing reactive species in either the polishing, pad conditioning, work-piece rinsing or pad rinsing fluids.  
         [0043]    c) Phase changes due to exposure to atmospheric pressure, increased temperatures, induced shear, or induced strain during polishing or pad conditioning type processes.  
         [0044]    d) Significantly higher physical wear rates between phases  12  and  11 .  
         [0045]    e) Surface degradation, decomposition, reaction, dissolution, increase mobility or other means of surface liberation due to an applied surface energy flux, including but not limited to light, acoustic or sonic energy, vibrations or thermal energy.  
         [0046]    f) Deformation and increased mobility due to increases in the surrounding temperature or by means of induced pressures and shear rates.  
         [0047]    g) Swelling or partial dissolution of material in concert with means of surface abrasion or agitation.  
         [0048]    h) Combinations of the above.  
         [0049]    Examples of methods and materials include but are not limited to:  
         [0050]    Method (a) chemical dissolution:  
         [0051]    Using solid or substantially void free pockets  12  of materials made from a size range of 5 to 250 microns including but not limited to:  
         [0052]    i. water soluble polymers such as Polyacrylic acids, hydroxypropylcellulose, or Polyethylene oxide (as sold by Union Carbide of Danbury, Conn. as Polyoxy products WSRN-10 and others), and blends of these types of polymers such that the overall mixture of materials is soluble in a desired polishing, rinsing, conditioning or other fluid. For example WSRN-10 VFP dissolves in water, when used a pad conditioning fluid.  
         [0053]    ii. Water-soluble solid salts or crystals such as sugars, soluble solid acid, potassium nitrite or for example solid oxalic or citric acid in water.  
         [0054]    iii. Inorganic particles such as CaCO 3  in dilute acid, Ca(NO 3 ) 2  in water, CaO in acid, ammonium nitrate in water, K 2 CO 3  in water, Zr(SO 4 ) 2  in water or potassium acetate in alkaline conditions, as examples.  
         [0055]    iv. Inorganic-organic complexes such as partially coagulated or reacted silica, ceria or other inorganic particles or molecular level species of inorganic materials (ceria, silica) with polyethylene oxide polymers, as an example.  
         [0056]    v. Combinations of the above, including combining materials to provide fast void creation to facilitate polymer dissolution, which is often accompanied by an initial swelling. These materials may also be combined with inert fillers that are substantially removed when the other materials are liberated.  
         [0057]    In this method, the VFP phase  12  examples listed above are fashioned into a polishing pad. The said polishing pad is then contacted with example fluids discussed in method (a). The VFP phase  12 , hence dissolves into the said fluids leaving said desired void  14 .  
         [0058]    Methods (b) chemical reaction:  
         [0059]    Using solid or substantially void free pockets  12  made from a size range of 5 to 250 microns including but not limited to:  
         [0060]    i. Lithium metal particle reacting with water.  
         [0061]    ii. Sulfur particles with hydrogen peroxide solutions.  
         [0062]    iii. Combinations reactive species with inert or partially soluble fillers.  
         [0063]    This method works in a similar manner as discussed in method (a), with the added distinction that rather than the VFP phase  12  dissolving, the said VFP chemically reacts with the contacting fluid, hence liberating a reaction by product from the surface of the said polishing pad forming said desired void  14 .  
         [0064]    Methods (c) of phase changes:  
         [0065]    Using solid or substantially void free pockets  12  made from a size range of 5 to 250 microns including but not limited to:  
         [0066]    i. Low melting temperatures materials, materials sensitive to phase changes caused by pressure changes, increased temperatures, induced shear or strain. For example, elastomeric polymers will act as solids under compression or impact, yet will flow when introduced to some flow conditions.  
         [0067]    Method (d) of wear rates:  
         [0068]    Using solid or substantially void free pockets  12  made from a size range of 5 to 250 microns which have a significantly higher physical wear rate than the polishing pad matrix  11 , including but not limited to:  
         [0069]    i. Matrix polymers such as Texin 250 Thermoplastic urethane ( 11 ) as sold by Bayer Incorporated of Pittsburgh, Pa., combined with VFP materials of higher wear such as highly cross-linked and high filler amount rubber particles, for example.  
         [0070]    All VFP phases listed above can be of any shape, as long as the polishing matrix  11  can remain functional during the described operation of the polishing pad. The size of these particles can be controlled by any number of the methods including, but not limited to granulation, grinding, cold-milling, solubolizing material and freeze drying the material into particles, and other methods used by those skilled in the art.  
         [0071]    Void free particle (VFP) phases need not be spherical. These said phase- 2  sections can be tracks or channels of material. In these cases, the aforementioned critical dimensions are similar, but represent the minimum average width or narrowest surface portion of the created pore. An example is shown in FIG. 7, where the VFP  12  can take many shapes. As one example, such shapes can be formed by providing a means for a polymer melt of the two precursor phases to be mixed to the scale of the desired intermediate surface texture, as practiced by ones skilled in the art.  
         [0072]    Examples of the polymeric matrix material  11  include but are not limited to urethane polymer, an acrylated urethane, and acrylated epoxy and ethylenically unsaturated organic compound having a carboyxl, benzyl or amide functionality, aminoplast derivative having a pendant unsaturated carbonyl group, and isocyanrate derivative having at least one pendant acrylate group, a vinyl ether, a polyacrylamide, an ethylene/ester copolymer or an acid derivative thereof, a polyvinyl alcohol, a polymethyl methacrylate, an ABS, a polysulfone, a polyamide, a polycarbonate, a polyvinyl chloride, an epoxy, a copolymer of the above or a combination thereof.  
         [0073]    The polymer matrix  11  could have the following bulk or surface physical properties:  
         [0074]    Hydrophilic intrinsically or at least after a diamond pad conditioning has been used to form surface micro-texture on the scale of 1-5 microns.  
         [0075]    A density of greater than 0.5 g/cm3  
         [0076]    A critical surface tension of greater than 33.5 milliNewtons/m  
         [0077]    A tensile modulus of 0.02 to 5 gigapascals  
         [0078]    A ratio of tensile modulus at 30C to tensile modulus at 60C of 1.0to 2.5  
         [0079]    A shore-D hardness of 25 to 90.  
         [0080]    A yield stress of 300-6000 psi  
         [0081]    A tensile strength of 1000 to 15000 psi  
         [0082]    An elongation to break less than or equal to 500%  
         [0083]    Method of Manufacturer:  
         [0084]    Example of proposed manufacturing methods are shown below. By no means are the examples limiting the materials nor methods available for making the above described invention.  
         [0085]    EXAMPLE 1  
         [0086]    A polymeric matrix can be prepared by mixing 2997 grams of Uniroyal adiprene L-325 polyether-based liquid urethane with approximately 50% by volume granular Polyox WSRN-80 (from Union Carbide) powder (or other substantially void polymeric powder, as described above, which are insoluble in Adiprene L-325). The mean diameter size of the VFP powder used is approximately 100 microns. This blend is mixed thoroughly in such a manner to maintain the particle integrity and still disperse the particle with the Adiprene L-325. This blend is then mixed with 768 grams of Curene® 442 at about 65C., using an in-line vented micro-mixer or homogenizer and poured into a mold and allowed to gel for about 15 minutes.  
         [0087]    The mold is then placed in a curing oven at about 95C for about 5 hours. The mold and now formed cake are slowly cooled in a controlled linear temperature ramp from 95C to 25C over the period of 5 hours. The molded article is then cut to form polishing pads either using a skiving tool or a veneering tool as appropriate based upon methods available and the shape of the mold used. Water jet cutting tools may also be used to cut polishing pads, with the added advantage that some surface porosity may be created by means discussed earlier, such as dissolution.  
         [0088]    Pads at this time are grooved using standard cutting blades on ether circular lathes or cutting arms fastened above a rotating table, to create circular grooves as shown in FIG. 6. Adhesive is then laminated to the backside of the polishing pad, which is then cut to the appropriate size for use.  
       EXAMPLE 2  
       [0089]    Texin 250 Thermal plastic urethane from Bayer Incorporated of Pittsburgh, Pa. (polymeric matrix phase  11 ), is mixed with Polyoxy® WSRN-750 from Union Carbide of Danbury, Conn. (VFP Phase  12 ). The said VFP phase is in the size range of 5-250 microns in diameter. These materials are combined in a commercially available extruder set to the following conditions. The said Texin 250 is introduced into the extruder in a manner known by those skilled in the art to achieve a substantially melted and well-mixed material (at approximately 190C.). The VFP phase, said Polyoxy® WSRN-750 is introduced at a reduced temperature and rapidly mixed and extruded into the said Texin 250 blend. The extruder conditions are designed as such that the VFP phase remains essentially intact within the polymer melt (particles are dispersed, not melted and mixed into polymer blend).  
         [0090]    Depending upon the extruder design and temperature used, the VFP phase WSRN-750, may need to be encapsulated in a higher melt temperature polymer from the list furnished in the description of the invention. Particle encapsulation of the said VFP by the said higher melting temperature polymer can be accomplished by any standard method known, by one skill in this art.  
         [0091]    The above-extruded melt is forced though a flat die creating a desired sheet of the combined material. The extruded film can fed right onto a desired substrate such as Mylar (from Dupont), Suba-4 (from Rodel Inc.) or commercially available rubber or foam sheets. The extruded sheets can be cast with continuous grooves by use of a grooved die. The final pads can then be heat-pressed into the desired macro-shape and size by using metallic molds with the desired pad structure cut into the mold. In this example a concentric groove design is pressed into the pad by heating the mold to an effective temperature. The pad is then cut into the desired shape and laminated with adhesive.  
         [0092]    Operation:  
         [0093]    Use of a polishing pad is a well-documented method for a variety of polisher types, and is easily conducted by one skilled in the art. Briefly, the operation of this polish pad is reviewed.  
         [0094]    The finished pad is first attached to the working surface of a polisher by a desired method of adhesion, usually using a pressure-sensitive-adhesive (PSA) and applied pressure along the top surface of the pad  600  to fasten the pad via the PSA to the working surface of the polisher. After the pad is attached, the pad surface must be treated to enact the appropriate method of creating surface pores  14 . Using the preferred embodiment of a the polishing pad (examples 1 or 2), a 5 minute conditioning run is employed while flowing a generous amount of room temperature water. The conditioning method uses a standard diamond-conditioning disk as the work-piece on the polishers conditioning arm at approximately 12 lbf on a 4-inch conditioner using a sweeping motion with the table rotating at a rate of usually over 10 RPM. During this initial break-in the diamond disk erodes the surface of the pad and creates tiny cuts  15  with-in the polymeric matrix. These actions open the surface of the solid or substantially void free particle or filled pockets  12  to the flow of water and in doing so starts the dissolution of this material. After sufficient time and pad erosion to open up the said VFP, the particle material dissolves and is carried away by the wafer flow rate in conjunction with the pad conditioning, creating the desire pore structure  14 . This operation can be enhanced by any method than enhances solubility of the VFP phase- the use of pressurized wafer delivery systems and high water temperatures as examples. At the end of the initial break-in, the desired surface pore  14  structure of the pad has been created.  
         [0095]    The depth of the cuts  15  made by the conditioning disk can control the depth pores created in the manner discussed above, as indicated in FIG. 4.  
         [0096]    After this initial break-in, wafers are loaded on the polisher where a polishing arm or other apparatus holds the wafer in contact with the polishing pad in the presence of slurry or other fluid. These slurries or fluids usually flow across the surface of the pad and are then moved between the wafer and the pad by virtue of the motion of the pad with respect to the wafer. The desired polishing of the wafer or work-piece usually takes place by virtue of the contact of the slurry or fluid with the wafer or work-piece in the presence of the polishing pad, in motion, at elevated contacting pressures.  
         [0097]    Conclusions, Ramifications and Scope:  
         [0098]    The invention teaches a novel structure, means of constructing and operation for a polishing pad. The advantages of this invention include:  
         [0099]    1. The invented polishing pads can be made microscopically and macroscopically substantially harder and stiffer than those used currently for most Semiconductor applications (Rodel IC-1000). The blending of the two solid phases with the VFP phase creates a substantially harder and stiffer polishing pad than that consisting of nearly 50% void space. This design will improve the planarization ability of the polishing pad. The presence of void spaces with in the polishing pad, as made by method 3, facilitate the compliance and flexing of a polymeric polishing pad.  
         [0100]    2. The polishing pad can incorporate a slowly dissolving Particle phase, which can act as a self cleaning method for the pad, thus lowering the criticality of the pad conditioning process, for some applications.  
         [0101]    3. The top surface polishing pore depth can be substantially controlled by the pad manufacturing method and the pad conditioning process.  
         [0102]    4. The methods of pad manufacturing can be substantially simplified over cake and skive methods. Less expensive and more manufacturable methods such as extruding or injection molding are difficult to use in pad manufacturing because they operate at extreme conditions and tend to yield smooth polymer surfaces (microscopically). This invention allows for these methods to be employed and still have a viable route for creating surface texture.  
         [0103]    5. VFP phases can be designed to release gases when combined with the correct chemistry to facilitate wafer lift-off, lessening the need for overall pad grooving.  
         [0104]    6. The chemistry with in the VFP phase may aid in pad conditioning, wafer cleaning or work-piece polishing performance.  
         [0105]    7. Softer pad matrix materials  11 , than IC-1000, can be used in this pad design with out sacrificing overall stiffness and bulk hardness of the pad. The resulting pad with a softer polymeric matrix will have fewer polishing scratches on the workpiece, which may be necessary for some substrate polishing applications.  
         [0106]    Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but merely providing illustrations of some of the presently preferred embodiments of this invention.