Process for etching silicon dioxide layer without micro masking effect

摘要

A process for etching a silicon dioxide layer is disclosed. The novel two step etch process is used, for example, to perform a contact etch through a BPSG layer. Both etch steps are carried out in a flow of O.sub. 2 and CHF.sub.3. In the first step, a high flow rate of oxygen (approximately 19 SCCM) is used. During this step, the bulk of the oxide is removed, without the problem of micro masking wherein small localized regions remain partially un-etched. In the second step, the remaining oxide is removed in a lower O.sub.2 flow rate, giving good oxide to silicon selectivity.