A method of forming a microelectronic device while preventing photoresist poisoning. Various layers of conductive metals and dielectric materials are deposited onto a substrate in selective sequence to form an integrated circuit. Vias and trenches are formed throughout the structure by exposing and patterning a photoresist material. The dielectric materials of the insulating layers are protected from the photoresist to prevent chemical reactions which lead to photoresist poisoning. This is done by forming a modified surface layer on the dielectric material by either depositing an additional layer that covers the dielectric material, or by modifying the exposed surface of the dielectric material to a plasma or chemical treatment.