fabricating metallization lines within a base dielectric layer by etching and filling with metallization;

depositing a barrier over the metallization lines and the base dielectric layer;

depositing an inorganic dielectric layer over the barrier;

depositing a low dielectric constant (low K) layer over the deposited inorganic dielectric layer immediately after the inorganic dielectric layer is deposited, wherein a thickness of the low dielectric constant layer is greater than a thickness of the inorganic dielectric layer;

etching a trench in the low K layer using a first etch chemistry, the etching being timed to etch through a partial thickness of the low K layer, and wherein the first etch chemistry is optimized to a selected low dielectric constant material;

defining locations of via holes in the trench with a photoresist mask;

etching the via holes through a remaining thickness of the low dielectric constant layer using the first etch chemistry; and

etching the via holes through the inorganic dielectric layer to the barrier using a second etch chemistry, the second etch chemistry being highly selective to the barrier.