0.5 μm complementary metal–oxide–semiconductor structures were utilized to investigate the selective nature of a high density plasma reactor. The formation of borderless contacts and local interconnects by the selective etch stop film approach was discussed and shown to be affected by topography, planarization, and nonuniformities. A factorial design of experiments determined the optimum conditions of the selective oxide etch chemistry. The resulting etch chemistry was characterized by measurable quantities such as an oxide etch rate of 1200 nm/min, a patterned (0.5 μm image) etch‐rate ratio for oxide:nitride ≳100:1 and 5%‐3σ uniformity. And, finally, an integratedinsituoxide etch/resist strip/nitride etch was presented.