The dry etching of aluminum layers for subhalf-micron technologies in a transformer coupled plasma etcher is investigated. Characterization of the system is performed in terms of etch rate, self-bias voltage, resist selectivity, and underlying oxide loss as functions of pressure, BCl3/Cl-2 ratio, and bottom power. It is shown that the deposition temperature of the aluminum film affects its etching behavior and, in particular, the appearance of postetch residues. A new etch process is developed that effectively eliminates residues while satisfying the requirements for sufficiently high etch rate, good resist, and oxide selectivity and profile control. The presence of Si-containing precipitates in the aluminum film is believed to be the origin of the residues and their removal is facilitated by etching at reduced pressure.