Methods are provided for depositing a dielectric material for use as an anti-reflective coating and sacrificial dielectric material in damascene formation. In one aspect, a process is provided for processing a substrate including depositing an acidic dielectric layer on the substrate by reacting an oxygen-containing organosilicon compound and an acidic compound, depositing a photoresist material on the acidic dielectric layer, and patterning the photoresist layer. The acidic dielectric layer may be used as a sacrificial layer in forming a feature definition by etching a partial feature definition, depositing the acidic dielectric material, etching the remainder of the feature definition, and then removing the acidic dielectric material to form a feature definition.