Composition for tungsten CMP
A chemical mechanical polishing composition for polishing a substrate having a tungsten layer includes a water based liquid carrier, abrasive particles dispersed in the liquid carrier, an iron containing accelerator, and a cationic polymer having an amino acid monomer. 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;
abrasive particles dispersed in the liquid carrier, wherein the abrasive particles comprise a colloidal silica abrasive, and the colloidal silica abrasive has a permanent positive charge of at least 10 mV, wherein the permanent positive charge is obtained by incorporating an aminosilane compound in the colloidal silica particles;
an iron containing accelerator, wherein the iron containing accelerator is a soluble iron containing catalyst present in the composition in an amount sufficient to provide a range from about 0.5 to about 20 ppm Fe based on the total weight of the composition;
a hydrogen peroxide oxidizer; and
a cationic polymer having an amino acid monomer unit, wherein the cationic polymer comprises at least one of polylysine, polyarginine, and polyhistidine.
2 . The composition of claim 1 , further comprising 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.
3 . The composition of claim 1 , having a pH in a range from about 1.0 to about 5.0.
4 . The composition of claim 1 , wherein the cationic polymer comprises polylysine.
5 . The composition of claim 4 , wherein the cationic polymer comprises ε-poly-L-lysine.
6 . The composition of claim 1 , comprising from about 1 to about 200 ppm by weight of the cationic polymer.
7 . The composition of claim 1 , comprising from about 5 to about 50 ppm by weight of the cationic polymer.
8 . The composition of claim 1 , wherein the cationic polymer has a molecular weight in a range from about 1 to about 100 kDa.
9 . A chemical mechanical polishing composition comprising:
a water based liquid carrier;
colloidal silica abrasive particles dispersed in the liquid carrier, wherein the colloidal silica abrasive has a permanent positive charge of at least 10 mV, and wherein the permanent positive charge is obtained by incorporating an aminosilane compound in the colloidal silica particles;
a soluble iron containing catalyst present in the composition in an amount sufficient to provide a range from about 0.5 to about 20 ppm Fe based on the total weight of the composition;
a hydrogen peroxide oxidizer;
a stabilizer bound to the soluble iron containing catalyst;
a cationic polymer having an amino acid monomer unit, the cationic polymer comprising at least one of polylysine, polyarginine, and polyhistidine; and
wherein the composition has a pH in a range from about 1 to about 5.
10 . The composition of claim 9 , wherein the cationic polymer is polylysine.