Composition for tungsten CMP
A chemical mechanical polishing composition for polishing a substrate having a tungsten layer includes a water based liquid carrier, a colloidal silica abrasive dispersed in the liquid carrier and having a permanent positive charge of at least 6 mV, an amine containing polymer in solution in the liquid carrier, and an iron containing accelerator. A method for chemical mechanical polishing a substrate including a tungsten layer includes contacting the substrate with the above described polishing composition, moving the polishing composition relative to the substrate, and abrading the substrate to remove a portion of the tungsten from the substrate and thereby polish the substrate.
1. A chemical mechanical polishing composition comprising:
a water based liquid carrier;
a colloidal silica abrasive dispersed in the liquid carrier, the colloidal silica abrasive having a permanent positive charge of at least 6 mV;
an amine containing polymer in solution in the liquid carrier; and
an iron containing accelerator.
2. The composition of claim 1 , wherein the colloidal silica has a permanent positive charge of at least 15 mV.
3. The composition of claim 1 , wherein the colloidal silica is treated with an aminosilane compound selected from the group consisting of such as bis(2-hydroxyethyl)-3-aminopropyl trialkoxysilane, diethylaminomethyltrialkoxysilane, (N,N-diethyl-3-aminopropyl)trialkoxysilane), 3-(N-styrylmethyl-2-aminoethylaminopropyl trialkoxysilane, aminopropyl trialkoxysilane, (2-N-benzylaminoethyl)-3-aminopropyl trialkoxysilane), trialkoxysilyl propyl-N,N,N-trimethyl ammonium chloride, N-(trialkoxysilylethyl)benzyl-N,N,N-trimethyl ammonium chloride, (bis(methyldialkoxysilylpropyl)-N-methyl amine, bis(trialkoxysilylpropyl)urea, bis(3-(trialkoxysilyl)propyl)-ethylenediamine, bis(trialkoxysilylpropyl)amine, bis(trialkoxysilylpropyl)amine, and mixtures thereof.
4. The composition of claim 1 , wherein the iron containing accelerator comprises a soluble iron containing catalyst and the polishing composition further comprises a stabilizer bound to the soluble iron containing catalyst, the stabilizer being selected from the group consisting of phosphoric acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, glutaconic acid, muconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, and mixtures thereof.
5. The composition of claim 1 , further comprising a hydrogen peroxide oxidizer.
6. The composition of claim 1 , having a pH in a range from about 2.0 to about 3.5.
7. The composition of claim 1 , wherein the amine containing polymer is selected from the group consisting of triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polymers including the following amine containing functional groups methacryloylox-ethyl trimethyl ammonium methylsulfate, diallyl dimethyl ammonium chloride, and methacrylamido-propyl trimethyl ammonium chloride, and mixtures thereof.
8. A method of chemical mechanical polishing a substrate including a tungsten layer, the method comprising:
(a) contacting the substrate with a polishing composition comprising:
(i) a water based liquid carrier;
(ii) a colloidal silica abrasive dispersed in the liquid carrier, the colloidal silica abrasive having a permanent positive charge of at least 6 mV;
(iii) an amine containing polymer in solution in the liquid carrier; and
(iv) an iron containing accelerator;
(b) moving the polishing composition relative to the substrate; and
(c) abrading the substrate to remove a portion of the tungsten from the substrate and thereby polish the substrate.
9. The method of claim 8 , wherein the colloidal silica has a permanent positive charge of at least 15 mV.
10. The method of claim 8 , wherein the colloidal silica is treated with an aminosilane compound selected from the group consisting of such as bis(2-hydroxyethyl)-3-aminopropyl trialkoxysilane, diethylaminomethyltrialkoxysilane, (N,N-diethyl-3-aminopropyl)trialkoxysilane), 3-(N-styrylmethyl-2-aminoethylaminopropyl trialkoxysilane, aminopropyl trialkoxysilane, (2-N-benzylaminoethyl)-3-aminopropyl trialkoxysilane), trialkoxysilyl propyl-N,N,N-trimethyl ammonium chloride, N-(trialkoxysilylethyl)benzyl-N,N,N-trimethyl ammonium chloride, (bis(methyldialkoxysilylpropyl)-N-methyl amine, bis(trialkoxysilylpropyl)urea, bis(3-(trialkoxysilyl)propyl)-ethylenediamine, bis(trialkoxysilylpropyl)amine, bis(trialkoxysilylpropyl)amine, and mixtures thereof.
11. The method of claim 8 , wherein the iron containing accelerator comprises a soluble iron containing catalyst and the polishing composition further comprises a stabilizer bound to the soluble iron containing catalyst, the stabilizer being selected from the group consisting of phosphoric acid, phthalic acid, citric acid, adipic acid, oxalic acid, malonic acid, aspartic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, glutaconic acid, muconic acid, ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, and mixtures thereof.
12. The method of claim 8 , wherein the polishing composition further comprises a hydrogen peroxide oxidizer.
13. The method of claim 8 , wherein the amine containing polymer is selected from the group consisting of triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polymers including the following amine containing functional groups methacryloylox-ethyl trimethyl ammonium methylsulfate, diallyl dimethyl ammonium chloride, and methacrylamido-propyl trimethyl ammonium chloride, and mixtures thereof.