Barrier slurry compositions and barrier cmp methods

A new barrier slurry composition enables metal and barrier layer material (as well as cap layer material, if necessary) to be removed at a practical rate whilst eliminating, or significantly reducing, the removal of underlying low-k or ultra-low-k dielectric material. The barrier slurry composition comprises: water, an oxidizing agent such as hydrogen peroxide, an abrasive such as colloidal silica abrasive, a complexing agent such as citrate, and may comprise a corrosion inhibitor such as benzotriazole. The preferential removal of cap layer material relative to underlying ULK dielectric material can be enhanced by including in the barrier slurry composition a f irst additive, such as sodium bis(2- ethylhexyl) sulfosuccinate. The removal rate of the barrier layer material can be tuned by including in the barrier slurry composition a second additive, such as ammonium nitrate.