Aug. 15,2002  24  US 2002/0111024 Al  about 5 to 15%, and most preferably about 10%. The oxalic  acid is added to the Ammonium persulfate at a concentration  of between about 0.1 and 5%, and more preferably about  1 %. The gluconic acid is added to the Ammonium persulfate  at a concentration of between about 1 to 50%, more pref› erably between about 10 to 30%, and most preferably about  20%. The slurry is delivered at a flow rate of between about  5 to 50 ml/min., more preferably between about 10 to 40  ml/min., and most preferably about 20 ml/min.  [0299]  Low concentrations of Ammonium persulfate can  still provide reasonable aluminum polishing rates if other  parameters are adjusted. A 1 % Ammonium persulfate solu› tion added at 90 ml/min at a pH of 3.5 with a 5% Silica ST™  slurry added at 20 ml/minute using a Polytex™ pad on a 3  inch IWS wafer at 33 RPM and 2 psi gave a polishing rate  of 225 Nminute.  [0300]  This Ammonium persulfate composition is prefer› ably between about 0.5 to 5%, more preferably between  about 1 to 4%, and most preferably about 1 %. The silica is  preferably between about 0.5 to 10%, more preferably  between about 2 to 8%, and most preferably about 5%, and  the combined slurry is delivered at a flow rate of between  about 5 to 50 ml/min., more preferably between about 10 to  40 ml/min., and most preferably about 20 m/min.  [0301]  Additional tests were conducted with  100%  Ammonium persulfate solutions dispensed at 20 ml/min.  Using an alumina abrasive dispensed at 20 ml/min., a 1918  Nmin. polish rate was obtained for a 3 inch  EMF  wafer on  a Politex pad; and a 1646 Nmin. polish rate was obtained for  a 3 inch  IWS  wafer using a polyurethane pad. In compari› son, using a Sytron abrasive dispensed at 20 ml/min., a  polish rate of 303 Nmin. was obtained for a 3 inch  EMF  wafer on a Politex pad.  [0302]  Ammonium Salts  [0303]  Aluminum was polished with different ammonium  salt solutions added at 20 m/min. using a Polytex™ pad on  a 3 inch IWS wafer at 33 RPM and 2 psi. A 5% NH$_{4}$OH  solution (pH 12) gave a polishing rate of 3000 Nmin.  [0304]  A 10% NH$_{4}$Cl solution (pH 4.5) gave a polishing  rate of 25 Nmin.  [0305]  Furthermore, a 5%  NH$_{4}$HF$_{2 }$ solution (pH<2) gave  a polishing rate greater than 4000 Nmin. while a 0.2%  NH$_{4}$HF$_{2 }$ solution gave a polish rate of 1200 Nmin.  [0306]  It can be seen that by choosing the ammonia salts  reasonably high polishing rates can be obtained at a number  of pH ranges. The ammonia salt solutions can be enhanced  by the addition of acids, chelators, oxidizers, and the like.  [0307]  Hydroxylamine  [0308]  The use of hydroxylamine-based formulations on  aluminum substrates can provide a range of polishing rates  of aluminum.  [0309]  At pH 10, 5% and 10% formulations of Hydroxy› lamine had between 2 and 25 Angstrom per minute polishing  rates when applied at 20 ml per minute to a POLITEX pad  using 2 psi pressure on 3" IWS and 3" EMF substrates.  [0310]  Hydroxylamine Nitrate  [0311]  A variety of 5-10% hydroxylamine nitrate formu› lations adjusted to pH 2.9-4 showed less than 5 Angstroms  per minute polishing rate when applied with 2 psi pressure  and at 10-33 rpm on 3"  IWS  aluminum substrates.  [0312]  Water  [0313]  Water when applied with alumina slurries at about  20 ml per minute each showed surprisingly high polishing  rates on 3" EMF and IWS aluminum substrates, between  about 1600 and about 1900 Angstroms per minute, when  applied at 2 psi with a POLITEX or an Polyurethane pad.  With SYTRON 4% slurry added with water, the POLITEX  pad showed a polishing rate of about 300 Angstroms per  minute.  We claim:  1.  A  method for chemical mechanical polishing of tung› sten comprising:  providing a semiconductor substrate comprising on one  face tungsten and a dielectric material;  providing a chemical mechanical polishing composition  comprising between about 2% and about 15% ammo› nium persulfate, between about 0.1 % and about 10% of  a secondary oxidizer, a  pH  adjusting compound to  adjust the  pH  of the composition, and optionally an  abrasive, wherein the  pH  of the composition is between  about 6.5 to about 12;  movably contacting the substrate face with a pad exerting  between about 0.1 and about 9 psi pressure on the  substrate and with the composition under conditions  that tungsten is removed at a rate different than the  removal of the dielectric material.  2.  The process of claim 1 wherein the secondary oxidizer  comprises potassium peroxymonosulfate, peroxymonosul› furic acid, imidazole, malonic acid, or malonamide.  3.  The process of claim 1 wherein the chemical mechani› cal polishing composition comprises at least one of potas› sium iodate, potassium periodate, or lithium periodate.  4.  The process of claim 1, wherein the chemical mechani› cal composition comprises periodic acid, peracetic acid,  oxalic acid, citric acid, lactic acid,  NH$_{4}$HF$_{2}$ ,  or a mixture  thereof.  5.  The process of claim 1 wherein the secondary oxidizer  comprises hydrogen peroxide, a perborate, a peroxhydrate,  or a urea hydrogen peroxide complex.  6. The process of claim 1 wherein the chemical mechani› cal polishing composition additionally comprises an organic  acid selected from the group consisting of gluconic, malonic  acid, lactic acid, succinic acid, tartaric acid, citric acid,  oxalic acid, or salts thereof.  7. The process of claim 1 further comprising a second  polishing operation comprising the steps of:  providing a second chemical mechanical polishing com› position comprising an oxidizer, a  pH  adjusting com› pound to adjust the  pH  of the composition, and option› ally an abrasive, wherein the  pH  of the composition is  between about 3 to about 12;  movably contacting the substrate face with a pad exerting  between about 0.1 and about 9 psi pressure on the  substrate and with the second composition under con› ditions that tungsten is removed at a rate different than  the removal of the dielectric material.  8.  The process of claim 7 wherein the second chemical  mechanical polishing composition comprises ammonium 