Abstract:
CMP formulations for use on nickel/phosphorus alloys comprising abrasive particles and an oxidant, a modifier for the action of the oxidant and first and second accelerants to sequester removed materials containing phosphonate and ammonium or amine groups respectively and optionally an organic carboxylic acid.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application is a continuation application of U.S. patent application Ser. No. 10/831,946, filed Apr. 26, 2004, which is a continuation application of U.S. patent application Ser. No. 10/080,853, filed Feb. 22, 2002 (now U.S. Pat. No. 6,755,721), entitled “Chemical Mechanical Polishing of Nickel Phosphorous Alloys,” naming inventors Douglas Edwin Ward and David Solomos, both applications are incorporated herein by reference in their entirety. 
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0002]     This invention relates to CMP (“chemical mechanical planarization”) materials and specifically to CMP materials for use in treating nickel-phosphorous alloys. The specific alloys targeted by the present invention are known as high-phosphorus alloys and contain 9 to 12 wt % of phosphorus, such alloys are conventionally deposited via an auto catalytic nickel plating process, typically called electroless nickel plating. Specifically in the manufacture of hard disks for hard-disk-drives (memory storage media), said nickel-phosphorous alloys are deposited on an aluminum substrate.  
       BACKGROUND OF THE INVENTION  
       [0003]     To manufacture hard disk drives, certain processes require an electroless nickel-plated substrate to demonstrate a highly planar surface. “Planarity” is quantified through the measurement of “waviness”, “flatness” and “roughness”. In addition to planarity, certain criteria determine the further processing of post electroless nickel-plated, aluminum substrates. In totality, these criteria are “waviness”, “roughness”, “outer diameter curvature”, “flatness” and surface defects. Waviness, roughness, outer diameter curvature and flatness are to be at a minimum in this context. Surface defects such as “pits”, “bumps” and “scratches” are defined by any disruption in the nickel-phosphorus lattice, which has a depth or height greater than or equal to twelve angstroms. In addition to seeking a planar surface that is void of surface defects, the CMP process of nickel-phosphorous plated, aluminum substrates must be accomplished in an efficient manner with respect to cycle time and labor intensity.  
         [0004]     Currently available CMP formulations have not succeeded in removing a Ni—P layer at an adequate rate when using abrasive particles consistent with achieving an adequately planar surface. In practical terms this means abrasive particle sizes of from 15 to 120 nanometers. As a result the tendency has been to use abrasives with a larger particle size to reduce the mean distance from “peaks” to “valleys” across the nickel-phosphorous surface very rapidly and follow with a process using particles with a range from 15-120 nm to create a “fine” finish with respect to planarity and surface defects. A “fine” finish is defined by the optimum surface condition available to this specific process.  
         [0005]     The CMP formulation of this invention is specifically designed to create a surface on a nickel-phosphorous layer that is suitable in all respects for further operations in the fabrication of a superior electronic component. Specifically it is capable of producing a highly uniform, minimum waviness surface in a one-step operation. It does this by using a CMP formulation that greatly increases the material-removal effectiveness of abrasives with particle sizes more usually associated with the later polishing operation.  
         [0006]     Normally in this context the CMP surface-generating process is accomplished in two operations: a first involving aggressive material removal until an approximate level is achieved and thereafter a more gentle process in which the desired surface finish, in terms of low surface roughness and micro-waviness, is pursued. The solutions used in the first polishing stage are frequently comprised of abrasive particles, (usually of alumina), with a particle size of from about 0.3 to 0.44 micrometers, and a chemical accelerant. The second action is a planarization action in which the surface defects created by the first material removal action are removed and a surface with an acceptable pre-determined smoothness and minimal waviness is created. This second stage of polishing is typically accomplished, using a finer abrasive (colloidal silica) and a chemical accelerant, in the presence of an oxidizer.  
         [0007]     The two sequential operations can take a substantial amount of time and are labor intensive. As a two-step process also requires more handling of the substrates surface defects are commonly introduced by human handling and transport of the product. It is therefore desired to fabricate a process where a substrate is properly processed via CMP in one step and on a single piece of equipment. A suitable formulation meeting these criteria has now been devised which can be used on a nickel/phosphorus alloy surface to create a finish equivalent to that obtained using a conventional two-stage process, in the same as or reduced time frame. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a statistical analysis diagram of removal rate data.  
         [0009]      FIG. 2  is a statistical analysis diagram of surface roughness data. 
     
    
     GENERAL DESCRIPTION OF THE INVENTION  
       [0010]     The present invention provides a CMP formulation for the treatment of a nickel/phosphorus alloy which comprises a dispersion of abrasive particles with particle sizes from 15 to 80 nanometers and selected from the group consisting of silica, alumina, titania, ceria, zirconia and mixtures thereof dispersed in a formulation having a pH of from 2.4 to 2.6 comprising: 
        a. an oxidizer;     b. a chemical accelerant comprised of four groups: 
            (1) a phosphonate     (2) a carboxylic acid     (3) a phosphate or phosphite     (4) an amine    
            c. water.        
 
         [0018]     The invention further comprises a single-step process comprising subjecting a nickel-phosphorus alloy containing from 9 to 12% phosphorus deposited on a substrate to a CMP process using a formulation as described above.  
         [0019]     In preferred formulations according to the invention the formulation comprises an organic carboxylic acid. This compound attacks the surface and makes removal of the alloy more easily accomplished. Examples of suitable acids include citric acid, oxalic acid, lactic acid, tartaric acid, glycine and mixtures of such acids.  
         [0020]     The formulations of the invention are carefully balanced to provide that the attack of the oxidant, (and any organic carboxylic acid present), on the nickel-phosphorus alloy surface is not so vigorous that material is removed in uncontrollable amounts that can not be adequately sequestered by the phosphonate group in the accelerant which is a chelating agent effective to chelate nickel removed from the surface of the nickel-phosphorus alloy and prevent re-deposition, or increase solubility by reacting with ligand providing components in the formulation. An important element of the balance is to maintain the pH at the above level and the level of the second accelerant plays an important role in this regard.  
         [0021]     In selecting the oxidant, the most preferred example is hydrogen peroxide because of the purity of the product and because it leaves little or no residue. However other know oxidants, such as periodates, sulphurous acid and percarbamates, can be used in partial or complete substitution for hydrogen peroxide unless there is a compatibility problem as is the case for mixtures of hydrogen peroxide and potassium periodate. The preferred oxidant is however hydrogen peroxide and most preferably in the form of a 35% by weight solution in water.  
         [0022]     The moderator for the activity of the oxidant comprises a phosphite or phosphate group having the group —PO x , where x is from 1 to 4. The preferred exemplar is phosphoric acid, (including the meta-, ortho-, and pyrophosphoric acid versions).  
         [0023]     The accelerant also comprises chelating phosphonate groups and suitable examples include 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), aminotri (methylenephosphonic acid) (ATMP), N-(2-hydroxyethyl)-N,N-di (methylenephosphonic acid) (HEMPA) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC).  
         [0024]     Of these HEDP is preferred. This component increases the solubility of the nickel removed from the surface and aids in producing a clean surface readily flushed clean of all CMP residues.  
         [0025]     The accelerant also comprises amine, amide or ammonium groups and suitable exemplars of such compounds include ammonium hydroxide, ammonium salts such ammonium nitrate, urea, formamide acetate, biuret, ethylene diamine and glycine. Mixtures of such compounds can also be used. This compound also acts as a ligand to keep nickel in a soluble form after removal from the surface.  
         [0026]     The amounts of the components in the formulation are preferably as follows: 
    Abrasive: from 2 to 10 and more preferably from 3 to 6 wt. %;     Oxidizer: from 1 to 6 wt. % and preferably 1 to 4 wt % of the active oxidant.     Phosphate or Phosphite: from 0.1 to 6 and more preferably from 0.1 to 4 wt. %;     Phosphonate: from 0.1 to 6 and more preferably from 0.1 to 4 wt. %;     Amine Amid Amide or Ammonium: from 0.1 to 6 and more preferably from 0.1 to 4 wt. %; and     Organic Carboxylic Acid: from 0.1 to 6 and more preferably from 0.1 to 4 wt. %.     Water: The balance up to 100 wt. %    
 
         [0034]     The most preferred abrasive component of the mixture for use on nickel-phosphorus substrates is silica, having a mean particle size of 15 to 120 nm, preferably from 15 to 80 nm and most preferably from 15 to 60 nanometers. The most suitable silicas have mono-dispersed, essentially spherical particles. Two suitable silica solutions are available as 30% by weight solid dispersions. A-Green Corp. and DuPont AirProducts NanoMaterials manufacture these products under the trade names BESIL-38A and Syton HD-700 respectively. Of these solutions, Syton HD-700 is preferred.  
       DESCRIPTION OF PREFERRED EMBODIMENTS  
     EXAMPLES  
       [0035]     A statistically analytical approach was utilized to formulate this invention. In order to eliminate excess variables in the development process, certain equipment and parameters were held constant. These equipment and their parameters were as follows:  
                                                                                                             TABLE A                                       Polish Machine   Speedfan 9h-5                Lower Platen Speed   4.0   rpm           Sun Gear Radius   3.5   Inches           Sun Gear Speed   9.5   rpm           Ring Gear Speed   8.5   rpm           Carrier Diameter   9   inches           Number of Work Pieces   6           Total Down Force   48   kg           Process Time   6   minutes           Ramp to Down Force   20   seconds           Total Slurry Flow-Rate   126   mL/min                Polish Pad   Rodel - DPM 1000           Roughness Measurement   Schmitt TMS           Removal Measurement   Satorius 3100S Balance           Cleaning Machine   Oliver Singe Rail           Double-Spaced                Number of Work Pieces   10               Brush Pressure (air)   40   psi           Soap Time   1   sec           Rinse Time (D1 spray)   1   sec                Detergent   AmberClean 527-L           Drying Machine   Semitool Stand-Alone Dryer                Rotor Speed   2700   rpm           Rinse Cycle   30   sec           DI Flow Rate   .5   gpm           Dry Cycle   180   sec           Air Pressure   60   psi                      
 
         [0036]     The procedure by which slurry was evaluated through this development process is depicted in the flow chart below:  
               TABLE B                                                                                
 
         [0037]     In addition to holding the procedures and process equipment and parameters constant, the concentration of colloidal silica was held constant at 5.71 percent by weight. This is to say that in every iteration of slurry, the concentration of colloidal silica by weight was held constant at 5.71 percent.  
       Example 1  
       [0038]     This example illustrates the contribution to removal rate by individual chemical groups in the presence of an oxidizer. An initial screening was to be performed involving forty-eight different constituents. At this initial stage of testing, the concentration of hydrogen peroxide as a thirty-five percent by weight solution was held constant at 2.57. This is to say that during the first phase of the slurry development process hydrogen peroxide in the form of a thirty-five percent by weight solution was held constant in every iteration of slurry at a total percentage by weight of 2.57. Each of the remaining forty-seven constituents was evaluated as a one percent by weight solution comprised of silica as described above, hydrogen peroxide as described above, the specific constituent and the remaining weight percent water. A listing of these constituents and the product codes assigned to them are found in table 1a. The procedure by which each of these constituents was evaluated is according to the Process Flow Diagram depicted in table B. Removal rate data in the form of total grams removal was collected from each slurry evaluated. This data was then analyzed by analysis of variance and a p-value obtained. A p-value of 0.00 was observed indicating that there was greater difference in removal data from slurry to slurry than within the data set acquired for an individual slurry. This is to say that there is sufficient statistical data to make inferences about the performance of each slurry. The data concerning the total removal of the nickel-phosphorous layer facilitated by each slurry is displayed in table 1b.  
                           TABLE 1a                           Code               Date Run   Name   Accelerants   Comments                   Mar. 07, 2001   A0   Hydrogen peroxide, 35%               A1   Ammonium nitrate           A2   Hydroxylamine nitrate, 50%           A3   Monoethanolamine       Mar. 09, 2001   A4   Guanidine carbonate           A5   Ethylenediamine           A6   Aluminum nitrate, 9hydrate           A7   Calcium nitrate, 4hydrate           A8   Ceric ammonium nitrate       Mar. 12, 2001   A9   Chrome III nitrate, 9hydrate           A10   Copper II nitrate, 3hydrate           A11   Magnesium nitrate, 6hydrate           A12   Nickel nitrate, 6hydrate       Mar. 14, 2001   A13   Potassium nitrate           A14   Potassium stannate,   Incompatibility               3hydrate   with hydrogen                   peroxide,                   not evaluated           A15   Zinc II nitrate, 6hydrate           A16   Cyanic acid   Possible safety                   issues existed,                   not evaluated       Mar. 16, 2001   A17   HEDP, 60% aqueous           A18   Ammonium fluoroborate           A19   Sodium fluorophosphate           A20   HPA, 50% aqueous           A21   Potassium iodate       Mar. 19, 2001   A22   Potassium periodate   Incompatibility                   with hydrogen                   peroxide,                   not evaluated           A23   Phosphoric acid, 85%               aqueous           A24   Sodium selenate           A25   Ammonium thiocyanate           A26   Ammonium vanadate   Possible safety                   issues existed,                   not evaluated       Mar. 20, 2001   A27   Citric acid           A28   L-Cysteine           A29   Glycine           A30   Lactic acid           A31   Oxalic acid       Mar. 21, 2001   A32   Tartaric acid           A33   Hydrogen peroxide, 35%           A34   Urea           A35   Oxamide   Possible safety                   issues existed,                   not evaluated           A36   Cyanamide   Possible safety                   issues existed,                   not evaluated       Mar. 22, 2001   A37   Dimethylglyoxime   Incompatibility                   with hydrogen                   peroxide,                   not evaluated           A38   Manganese II nitrate, 50%           A39   Zirconyl nitrate   Incompatibility                   with hydrogen                   peroxide,                   not evaluated           A40   Tin IV oxide, 15%, 15 nm       Mar. 23, 2001   A41   Formamid Acetate           A42   Formamid Sulfinic Acid   Not evaluated                   due to                   unavailability                   of raw materials           A43   Mayoquest 1320           A44   Mayoquest 2100           A45   Taurine           A46   Biuret           A47   Mayoquest 1200   Not evaluated                   due to                   unavailability                   of raw materials                  
 
         [0039]    
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
               
               
               
               
               
             
               
               
             
           
               
                 TABLE 1b 
               
               
                   
               
               
                   
               
             
             
               
                 Analysis of Variance for Removal 
               
               
                   
               
             
          
           
               
                 Source 
                 DF 
                 SS 
                 MS 
                 F 
                 P 
               
               
                   
               
             
          
           
               
                 Slurry A 
                  36 
                 2.827991 
                 0.078555 
                 227.07 
                 0.000 
               
               
                 Error 
                 74 
                 0.025600 
                 0.000346 
               
               
                 Total 
                 110 
                 2.853591 
               
               
                   
               
             
          
           
               
                   
                 Individual 95% CTs For Mean 
               
               
                   
                 Based on Pooled StD 
               
               
                   
                   
               
             
          
           
               
                 Level 
                 N 
                 Mean 
                 StDev 
                 -----------+-----------+----------+---------- 
               
               
                   
               
             
          
           
               
                 0 
                 3 
                 0.23667 
                 0.00577 
                      *) 
               
               
                 1 
                 3 
                 0.34667 
                 0.01528 
                            (*) 
               
               
                 2 
                 3 
                 0.40333 
                 0.01155 
                             (*) 
               
               
                 3 
                 3 
                 0.33333 
                 0.02082 
                        (*) 
               
               
                 4 
                 3 
                 0.29667 
                 0.01528 
                      (*) 
               
               
                 5 
                 3 
                 0.41333 
                 0.02309 
                         (* 
               
               
                 6 
                 3 
                 0.55333 
                 0.03055 
                           (*) 
               
               
                 7 
                 3 
                 0.25333 
                 0.03055 
                      (*) 
               
               
                 8 
                 3 
                 0.36667 
                 0.00577 
                        (*) 
               
               
                 9 
                 3 
                 0.42000 
                 0.01000 
                         (*) 
               
               
                 10 
                 3 
                 0.29333 
                 0.01528 
                        (*) 
               
               
                 11 
                 3 
                 0.06000 
                 0.02646 
                    *) 
               
               
                 12 
                 3 
                 0.24333 
                 0.00577 
                       (*) 
               
               
                 13 
                 3 
                 0.30000 
                 0.02000 
                        (*) 
               
               
                 15 
                 3 
                 0.21333 
                 0.02309 
                       (* 
               
               
                 17 
                 3 
                 0.55000 
                 0.01732 
                           (*) 
               
               
                 18 
                 3 
                 0.35667 
                 0.00577 
                        (*) 
               
               
                 19 
                 3 
                 0.46667 
                 0.02887 
                         (*) 
               
               
                 20 
                 3 
                 0.56333 
                 0.02887 
                         (* 
               
               
                 21 
                 3 
                 0.27333 
                 0.00577 
                          (*) 
               
               
                 23 
                 3 
                 0.56000 
                 0.01000 
                            *) 
               
               
                 24 
                 3 
                 0.38333 
                 0.01528 
                       (*) 
               
               
                 25 
                 3 
                 0.08667 
                 0.00577 
                      *) 
               
               
                 27 
                 3 
                 0.58667 
                 0.01528 
                         *) 
               
               
                 28 
                 3 
                 0.03000 
                 0.00000 
                   (*) 
               
               
                 29 
                 3 
                 0.51000 
                 0.01000 
                           *) 
               
               
                 30 
                 3 
                 0.54333 
                 0.00577 
                        (*) 
               
               
                 31 
                 3 
                 0.73333 
                 0.03055 
                            (*) 
               
               
                 32 
                 3 
                 0.58000 
                 0.01000 
                       (*) 
               
               
                 34 
                 3 
                 0.27667 
                 0.01155 
                      (*) 
               
               
                 38 
                 3 
                 0.22000 
                 0.00000 
                      (*) 
               
               
                 40 
                 3 
                 0.28667 
                 0.00577 
                      *) 
               
               
                 41 
                 3 
                 0.50333 
                 0.04619 
                         (*) 
               
               
                 43 
                 3 
                 0.54000 
                 0.01732 
                           (* 
               
               
                 44 
                 3 
                 0.48333 
                 0.02807 
                        (*) 
               
               
                 45 
                 3 
                 0.25333 
                 0.00577 
                     (*) 
               
               
                 46 
                 3 
                 0.25667 
                 0.00577 
                     (*) 
               
             
          
           
               
                 Pooled StDev = 0.01860 
                 -----------+-----------+-----------+----------- 
               
               
                   
                    0.25   0.50   0.75 
               
               
                   
               
             
          
         
       
     
         [0040]     Table 1b, shows a myriad of possible constituents as candidates for slurry with adequate removal rate. Current state of the art colloidal silica slurries remove the nickel-phosphorous layer at rates from 7 mg-12 mg per minute per disk, which in comparison to this evaluation would equate to 0.252 g-0.432 g total removal. Table 1b shows thirteen slurries which surpass this current bench mark and have coded units of A6, A17, A19, A20, A23, A27, A29, A30, A31, A32, A41, A43, and A44. In uncoded unites, these constituents are respectively aluminum nitrate, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), sodium fluorophosphate, hydroxyphosphono acetate, phosphoric acid, citric acid, glycine, lactic acid, oxalic acid, tartaric acid, formamid acetate, aminotri (methylenephosphonic acid) (ATMP) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC). Each of these constituents in the presence of an oxidizer, (hydrogen peroxide in this specific example) show removal rate capabilities superior to the current state of the art.  
       Example 2  
       [0041]     This example illustrates the effects and interactions of ten specific constituents. A fractional factorial design of experiment model was utilized to approximate the magnitude of interactions of ten constituents up through the third-order. This is to say that through statistical analysis of removal data, the effects individually and interactions with any one or two other constituents were evaluated. Process procedures, parameters and equipment were held constant as described in tables A and B to evaluate constituents with coded units A0, A5, A6, A17, A20, A23, A27, A29, A31 and A32. In uncoded units, those constituents were hydrogen peroxide, ethylene diamine, aluminum nitrate, HEDP, HPA, phosphoric acid, citric acid, glycine, oxalic acid and tartaric acid respectively. A design of experiment model of resolution four was utilized where the forty-two slurries were formulated according to table 2a. Further, this table describes the actual percent by weight each constituent was present in a given slurry. This is to say that in the first slurry evaluated, denoted by RunOrder 1, constituents A29, A31, A32 and A5 each were present in concentrations of 1 percent by weight of the total solution while A0 was present in 2.57 percent by weight of the total solution. Silica was held constant as described above at a percent by weight of 5.71 and the remaining weight percent was water.  
                                                                                                     TABLE 2a                       Run                                               Order   A6   A17   A20   A23   A27   A29   A31   A32   A5   A0                                1   0   0   0   0   0   1   1   1   1   2.57       2   1   0   0   0   0   0   0   0   0   2.57       3   0   1   0   0   0   0   0   0   1   0.00       4   1   1   0   0   0   1   1   1   0   0.00       5   0   0   1   0   0   0   0   1   0   0.00       6   1   0   1   0   0   1   1   0   1   0.00       7   0   1   1   0   0   1   1   0   0   2.57       8   1   1   1   0   0   0   0   1   1   2.57       9   0   0   0   1   0   0   1   0   0   0.00       10   1   0   0   1   0   1   0   1   1   0.00       11   0   1   0   1   0   1   0   1   0   2.57       12   1   1   0   1   0   0   1   0   1   2.57       13   0   0   1   1   0   1   0   0   1   2.57       14   1   0   1   1   0   0   1   1   0   2.57       15   0   1   1   1   0   0   1   1   1   0.00       16   1   1   1   1   0   1   0   0   0   0.00       17   0   0   0   0   1   1   0   0   0   0.00       18   1   0   0   0   1   0   1   1   1   0.00       19   0   1   0   0   1   0   1   1   0   2.57       20   1   1   0   0   1   1   0   0   1   2.57       21   0   0   1   0   1   0   1   0   1   2.57       22   1   0   1   0   1   1   0   1   0   2.57       23   0   1   1   0   1   1   0   1   1   0.00       24   1   1   1   0   1   0   1   0   0   0.00       25   0   0   0   1   1   0   0   1   1   2.57       26   1   0   0   1   1   1   1   0   0   2.57       27   0   1   0   1   1   1   1   0   1   0.00       28   1   1   0   1   1   0   0   1   0   0.00       29   0   0   1   1   1   1   1   1   0   0.00       30   1   0   1   1   1   0   0   0   1   0.00       31   0   1   1   1   1   0   0   0   0   2.57       32   1   1   1   1   1   1   1   1   1   2.57       33   0   1   0   0   0   0   0   0   0   2.57       34   0   0   1   0   0   0   0   0   0   2.57       35   0   0   0   1   0   0   0   0   0   2.57       36   0   0   0   0   1   0   0   0   0   2.57       37   0   0   0   0   0   1   0   0   0   2.57       38   0   0   0   0   0   0   1   0   0   2.57       39   0   0   0   0   0   0   0   1   0   2.57       40   0   0   0   0   0   0   0   0   1   2.57       41   0   0   0   0   0   0   0   0   0   2.57       42   0   1   0   0   0   0   0   0   1   2.57                  
 
         [0042]     The quantitative results with respect to estimated effects and coefficients of this evaluation are found in table 2b. The coefficients denoted by “Coef” in table 2b indicate the magnitude of the effect of an individual constituent or interaction. The statistical significance of these results is described by a p-value which is denoted “P” in table 2b. A p-value less than 0.05 denotes a statistical significance. This is to say that when a p-value less than 0.05 is observed, these is sufficient statistical evidence to make inferences about the contribution of an individual constituent or interaction to the system with respect to removal rate.  
                                                                             TABLE 2b                       Estimated Effects and Coefficients (coded units)                                Term   Effect   Coef   SE Coef   T   P               Constant       0.3289   0.002580   123.60   0.000       A6   0.0156   0.0078   0.002580   3.03   0.003       A17   −0.0598   −0.0299   0.002580   −11.59   0.000       A20   0.0348   0.0174   0.002580   6.74   0.000       A23   −0.0127   −0.0064   0.002580   −2.46   0.016       A27   0.0281   0.0141   0.002580   5.45   0.000       A29   −0.0352   −0.0176   0.002580   −6.82   0.000       A31   0.0698   0.0349   0.002580   13.53   0.000       A32   −0.0677   −0.0339   0.002580   −13.12   0.000       A5   −0.0756   −0.0378   0.002580   −14.66   0.000       A0   0.3390   0.1685   0.002580   65.70   0.000       A6*A17   −0.0185   −0.0093   0.002580   −3.59   0.001       A6*A20   −0.0131   −0.0066   0.002580   2.54   0.013       A6*A23   0.0494   0.0247   0.002580   9.57   0.000       A6*A27   −0.0340   −0.0170   0.002580   −6.58   0.000       A6*A29   −1.0115   0.5057   0.024878   −20.33   0.000       A6*A31   −0.0140   −0.0070   0.002580   −2.71   0.008       A6*A32   0.0235   0.0118   0.002580   4.56   0.000       A6*A5   0.3246   0.1623   0.010319   15.73   0.000       A6*A0   −0.3925   −0.1962   0.011392   −17.23   0.000       A17*A20   0.0090   0.0045   0.002580   1.74   0.006       A17*A23   −0.0394   −0.0197   0.002580   −7.63   0.000       A17*A27   0.0698   0.0349   0.002580   13.53   0.000       A17*A29   0.0085   −0.0043   0.002580   −1.66   0.102       A17*A31   0.0131   0.0066   0.002580   2.54   0.013       A17*A32   0.4100   0.2050   0.013772   14.89   0.000       A17*A5   −0.1400   0.0700   0.007297   −9.59   0.000       A17*A0   −0.3748   −0.1874   0.010319   −18.16   0.000       A20*A23   0.0102   0.0051   0.002580   1.98   0.051       A20*A27   0.4994   0.2497   0.013772   18.13   0.000       A20*A29   1.1023   0.5511   0.025342   21.75   0.000       A20*A31   −0.5856   −0.2929   0.013772   −21.27   0.000       A20*A32   0.1665   0.0832   0.007297   11.41   0.000       A20*A5   −0.4369   −0.2184   0.013651   −16.00   0.000       A23*A27   0.0027   0.0014   0.002580   0.52   0.601       A23*A29   −0.0523   0.0261   0.002580   −10.14   0.000       A23*A31   0.1598   0.0799   0.007297   10.95   0.000       A23*A32   0.5769   0.2884   0.013092   20.76   0.000       A27*A29   0.2948   0.0974   0.007297   13.35   0.000       A27*A32   −1.0546   −0.5273   0.025210   20.92   0.000       A29*A32   −0.5333   −0.2667   0.013651   −19.53   0.000       A17*A20*A23   1.0433   0.5217   0.024744   21.08   0.000                    Analysis of Variance for Sample (coded units)            Source   DF   Seq SS   Adj SS   Adj MS   F   P               Main Effects   10   4.29746   3.25494   0.329494   515.73   0.000       2-Way   30   0.63745   0.67552   0.029184   45.68   0.000       Interactions       3-Way   1   0.28397   0.28397   0.283968   444.47   0.000       Interactions       Residual   84   0.05367   0.05367   0.000639       Error       Pure Error   84   0.05367   0.05367   0.000639       Total   125   0.25655                  
 
         [0043]     The beneficial second order interactions obtained from this evaluation are as follows:  
         [0000]     Beneficial Interactions  
         [0000]    
       
          HEDP:Ethylenediamine (slightly significant)  
          Aluminum Nitrate:Tartaric Acid  
          Aluminum Nitrate:Glycine  
          Aluminum Nitrate:Phosphoric Acid  
          Aluminum Nitrate:Glycine  
          Phosphoric Acid:HPA (slightly significant)  
          Citric Acid:HEDP  
          HPA:Glycine  
          Aluminum Nitrate:Ethylenediamine (slightly significant)  
          Citric Acid:Ethylenediamine  
          HPA:Glycine  
          Citric Acid:HPA:Glycine  
          HPA:Ethylenediamine  
          Phosphoric Acid:Citric Acid  
          Citric Acid:Glycine (slightly significant)  
       
     
       Example 3  
       [0059]     Example 3 illustrates the effects and interactions more specifically of constituents, in coded units, A17, A20, A23, A27 and A29. These constituents in uncoded units are HEDP, HPA, phosphoric acid, citric acid and glycine respectively. Again, process procedures, parameters and equipment were held constant as described in tables A and B. Silica was present in each slurry at a concentration of 5.71 percent by weight of the total solution. Hydrogen peroxide in a 35 percent by weight solution was held constant in each slurry at a level of 2.57 percent by weight of the total solution. A fractional factorial design of experiment model was created to incorporate these chemistries. By so doing, nineteen slurries were formulated and quantitatively analyzed by examining removal rate data. The design of experiment model is defined in table 3a. A statistical analysis of this data is found in table 3b where the estimated effects and coefficients of individual constituents and interactions up through the fourth order are displayed.  
                                                                         TABLE 3a                                   Run Order   A17   A27   A29   A20   A23                                        1   0.1   0.1   0.1   0.1   0           2   1.1   0.1   0.1   0.1   0           3   0.1   1.1   0.1   0.1   0           4   1.1   1.1   0.1   0.1   0           5   0.1   0.1   1.1   0.1   0           6   1.1   0.1   1.1   0.1   0           7   0.1   1.1   1.1   0.1   0           8   1.1   1.1   1.1   0.1   0           9   0.1   0.1   0.1   1.1   0           10   1.1   0.1   0.1   1.1   0           11   0.1   1.1   0.1   1.1   0           12   1.1   1.1   0.1   1.1   0           13   0.1   0.1   1.1   1.1   0           14   1.1   0.1   1.1   1.1   0           15   0.1   1.1   1.1   1.1   0           16   1.1   1.1   1.1   1.1   0           17   1.0   1.0   0.0   0.0   1           18   1.0   1.0   0.0   0.0   1           19   1.0   1.0   0.0   0.0   1                      
 
         [0060]    
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3b 
               
               
                   
               
               
                   
               
               
                 Estimated Effects and Coefficients for Sample (uncoded units) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Term 
                 Effect 
                 Coef 
                 SE Coef 
                 T 
                 P 
               
               
                   
               
               
                 Constant 
                   
                 0.53518 
                 0.007564 
                 70.76 
                 0.000 
               
               
                 A17 
                 0.05403 
                 0.02701 
                 0.002743 
                 9.85 
                 0.000 
               
               
                 A27 
                 0.02744 
                 0.01372 
                 0.002743 
                 5.00 
                 0.000 
               
               
                 A29 
                 −0.04166 
                 −0.02083 
                 0.003003 
                 6.94 
                 0.000 
               
               
                 A20 
                 −0.04533 
                 −0.02266 
                 0.003003 
                 −7.55 
                 0.000 
               
               
                 A23 
                 0.01349 
                 0.00674 
                 0.007677 
                 0.88 
                 0.385 
               
               
                 A17*A27 
                 −0.03435 
                 −0.01717 
                 0.002743 
                 −6.26 
                 0.000 
               
               
                 A17*A29 
                 −0.02003 
                 0.01001 
                 0.003003 
                 −3.34 
                 0.002 
               
               
                 A17*A20 
                 −0.03286 
                 0.01643 
                 0.003003 
                 −5.47 
                 0.000 
               
               
                 A27*A29 
                 −0.02727 
                 −0.01364 
                 0.003003 
                 −4.54 
                 0.000 
               
               
                 A27*A20 
                 −0.03460 
                 −0.01730 
                 0.003003 
                 −5.76 
                 0.000 
               
               
                 A29*A20 
                 −0.04084 
                 −0.02042 
                 0.003287 
                 6.21 
                 0.000 
               
               
                 A17*A27*A29 
                 0.03630 
                 0.01817 
                 0.003003 
                 6.05 
                 0.000 
               
               
                 A17*A27*A20 
                 0.03451 
                 0.01726 
                 0.003003 
                 5.75 
                 0.000 
               
               
                 A17*A29*A20 
                 0.04386 
                 0.02193 
                 0.003287 
                 6.67 
                 0.000 
               
               
                 A27*A29*A20 
                 0.03277 
                 0.01639 
                 0.003287 
                 4.99 
                 0.000 
               
               
                 A17*A27*A29*A20 
                 −0.00151 
                 −0.00076 
                 0.003287 
                 −0.23 
                 0.819 
               
               
                   
               
             
          
           
               
                 Analysis of Variance for Sample (coded units) 
               
             
          
           
               
                 Source 
                 DF 
                 Seq SS 
                 Adj SS 
                 Adj MS 
                 F 
                 P 
               
               
                   
               
               
                 Main Effects 
                 5 
                 0.117544 
                 0.100321 
                 0.0200643 
                 56.66 
                 0.000 
               
               
                 2-Way 
                 6 
                 0.049612 
                 0.060841 
                 0.0101402 
                 28.63 
                 0.000 
               
               
                 Interactions 
               
               
                 3-Way 
                 4 
                 0.049292 
                 0.048996 
                 0.0122491 
                 34.59 
                 0.000 
               
               
                 Interactions 
               
               
                 4-Way 
                 1 
                 0.000019 
                 0.000019 
                 0.0000187 
                 0.05 
                 0.819 
               
               
                 Interactions 
               
               
                   
               
             
          
         
       
     
         [0061]     Table 3a depicts the levels at which each of the constituents were evaluated. For example, in addition to silica and hydrogen peroxide which were afore mentioned, slurry number 3, indicated by RunOrder 3, comprised 0.1 percent A17, 1.1 percent A27, 0.1 percent A29, 0.1 percent A20 and no A23. Each of the percentages described above are indicative of a percent by weight of the total slurry. The significance of this example is that A29 and A20 are shown to have an adverse effect on removal rate when in the presence of all the other constituents in this specific evaluation. Approximate values of said negative impacts in this specific system are found in table 3b and are characterized by their estimated coefficients; denoted by “Coef”.  
       Example 4  
       [0062]     Example 4 depicts the effects of individual constituents and interactions of the preferred constituents in this invention. In coded units, these constituents are A0, A17, A23 and A27. Respectively, these constituents in uncoded units are hydrogen peroxide, HEDP, phosphoric acid and citric acid. All procedures, parameters and equipment were held constant as described in tables A and B. A fractional factorial design of experiment model was utilized to determine the magnitude of contributions with respect to removal rate of each constituent. The fractional factorial design of experiment model is portrayed in table 4a. Silica was present as 5.71 percent by total weight of each slurry. Ammonium hydroxide was utilized to standardize the pH throughout the evaluation at 2.5. Quantitative statistical analysis of the results of this example is available in table 4b. The concentrations of each constituent in each slurry is depicted in table 4a. For example, the first slurry evaluated, denoted by RunOrder 1, comprised of 0.25 weight percent A17, 0.25 weight percent A23, 0.27 weight percent A27 and 1.29 weight percent A0. Said weight percent values are indicative of total weight percent.  
                               TABLE 4a                       Run Order   A17   A23   A27   A0                   1   0.25   0.25   0.25   1.29       2   1.25   0.25   0.25   3.86       3   0.25   1.25   0.25   3.86       4   1.25   1.25   0.25   1.29       5   0.25   0.25   1.25   3.86       6   1.25   0.25   1.25   1.29       7   0.25   1.25   1.25   1.29       8   1.25   1.25   1.25   3.86                  
 
         [0063]    
       
         
               
             
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 4b 
               
               
                   
               
               
                   
               
               
                 Estimated Effects and Coefficients for Sample (coded units) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Term 
                 Effect 
                 Coef 
                 SE Coef 
                 T 
                 P 
               
               
                   
               
               
                 Constant 
                   
                 0.59000 
                 0.003773 
                 156.37 
                 0.000 
               
               
                 A17 
                 0.04167 
                 0.02093 
                 0.003773 
                 5.52 
                 0.000 
               
               
                 A23 
                 0.50000 
                 0.02500 
                 0.003773 
                 6.63 
                 0.000 
               
               
                 A27 
                 −0.02367 
                 −0.01083 
                 0.003773 
                 −2.87 
                 0.011 
               
               
                 A0 
                 0.03667 
                 0.01833 
                 0.003773 
                 4.86 
                 0.000 
               
               
                 A17*A23 
                 −0.03833 
                 −0.01917 
                 0.003773 
                 5.88 
                 0.000 
               
               
                 A17*A27 
                 0.00333 
                 0.00167 
                 0.003773 
                 0.44 
                 0.665 
               
               
                 A17*A0 
                 −0.00500 
                 −0.00250 
                 0.003773 
                 −0.66 
                 0.517 
               
               
                   
               
             
          
           
               
                 Analysis of Variance for Sample (coded units) 
               
             
          
           
               
                 Source 
                 DF 
                 Seq SS 
                 Adj SS 
                 Adj MS 
                 F 
                 P 
               
               
                   
               
               
                 Main Effects 
                 4 
                 0.036300 
                 0.036300 
                 0.0090750 
                 26.56 
                 0.000 
               
               
                 2-Way 
                 3 
                 0.009033 
                 0.009033 
                 0.0030111 
                 8.81 
                 0.001 
               
               
                 Interactions 
               
               
                 Residual 
                 16 
                 0.005467 
                 0.005467 
                 0.0003417 
               
               
                 Error 
               
               
                 Pure Error 
                 16 
                 0.005467 
                 0.005467 
                 0.0003417 
               
               
                 Total 
                 23 
                 0.050800 
               
               
                   
               
             
          
         
       
     
         [0064]     This example illustrates the significant interactions between the preferred constituents in this invention up through the second order.  
       Example 5  
       [0065]     This example illustrates the performance capability of this invention. All process parameters and equipment were held constant as described in Tables A and B when slurry comprising hydrogen peroxide, citric acid, HEDP, phosphoric acid, ammonium hydroxide, silica and water was evaluated. Thirty different runs were performed according to tables A and B. The removal and surface roughness data from these thirty runs were statistically analyzed. Removal rate data is portrayed graphically in  FIG. 1  while surface roughness data is portrayed in  FIG. 2 . The data acquired from this example depicts a mean removal rate of 18.37 mg/min/disk. Accompanying this mean removal rate is a standard deviation of 0.779 mg/min/disk. The surface of the nickel-phosphorous after polishing with this invention is void of defects. Defects are defined as any interruption in the nickel-phosphorous lattice having depth or height greater than twelve angstroms. This is observed through the surface roughness data obtained from this evaluation. A mean surface roughness of 1.47 angstroms was observed with a standard deviation of 0.17 angstroms. This value of 1.47 angstroms is indicative of the surface condition of the substrate. As measured on a TMS 2000, manufactured by Schmitt Inc., the average difference from peak to valley on the surface of the disks measured was 1.47 angstroms.