ETCHING ALUMINIUM OVER REFRACTORY METAL WITH SUCCESSIVE PLASMAS

摘要

PURPOSE: An etching apparatus is provided to etch an exposed region of a multi-layer metal having at least two layers so as to minimize undercutting of the aluminum side wall as the refractory metal layer becomes depleted. CONSTITUTION: Provided is a process for etching an exposed region of a multi-layer metal having at least two layers, namely a layer of aluminum or aluminum alloy, and an underlying layer of refractory metal. The etching process includes at least two steps. In a first step, the aluminum layer is etched by processing the substrate with a first plasma chemistry that etches aluminum. Optionally a portion, but not all, of the refractory metal layer also is etched by the first plasma chemistry. In a subsequent second step, the remainder of the refractory metal layer is etched by a second plasma chemistry that etches the lower refractory metal much faster than it etches aluminum.