Methods for etching doped oxides in the manufacture of microfeature devices

A method for forming capacitors on a microfeature workpiece, the workpiece including a plurality of conductive plugs, a first nitride layer over the conductive plugs, a dielectric layer over the first nitride layer, and a second nitride layer over the dielectric layer, the method comprising:

• patterning and etching the second nitride layer to form a mask over the dielectric layer;
• forming a plurality of first openings in the dielectric layer with a first etching process, wherein the dielectric layer includes a doped oxide material;
• forming a plurality of second openings in the first nitride layer with a second etching process, the individual second openings exposing at least a portion of the individual conductive plugs;
• depositing a first conductive layer in at least a portion of the individual openings and in electrical contact with corresponding conductive plugs, wherein the first conductive layer includes TiN;
• depositing a second conductive layer over at least a portion of the first conductive layer in the individual openings, wherein the second conductive layer includes polysilicon;
• and
• removing at least substantially all the dielectric layer from the workpiece with a third etching process, wherein the third etching process includes an etchant comprising DI:HF and an acid to provide a pH of the etchant such that the etchant includes (a) a selectivity of phosphosilicate glass (PSG) to nitride of greater than 250:1, and (b) an etch rate through PSG of greater than 9,000 Å/minute.