Convertible hot edge ring to improve low-k dielectric etch

Abstract

Two-step process to improve low-K dielectric etch uniformity, apparatus to perform the method, and semiconductor devices formed in accordance with the method. In a first etching step, an insulating hot edge ring is provided. When the photoresist clearing signal is observed using end-point software, the insulating cover is moved aside to expose the conductive edge ring for the remainder of the etch. One aspect of this invention contemplates an insulator cover over a conductive edge ring at the start of wafer etching, which cover is removed after end-pint detection. The present invention contemplates a number of physical configurations whereby the insulator ring is urged into, and away from, its masking of the conductive edge ring. Alternatively, the etching of a wafer bearing low-K material may be conducted using two edge rings, where the first etch step is conducted using an insulating hot edge ring, and a second etch step is conducted using a conductive hot edge ring. According to this aspect, the two step process may thus be performed in a plurality of reactor vessels, or in one reactor vessel having a plurality of processing stations. Different low-K materials may require differing etchant/passivant/diluent combinations. Accordingly, the two-step etch process is taught in conjunction with any number of different etch chemistries.