Zinc sulfide planarization

Abstract

A procedure for planarizing a group II-VI composition which includes a resist and etch-back procedure wherein a thick resist coating relative to the degree of non-planarity is spun over a non-planar group II-VI layer to provide a planar resist surface. The resist is then etched back to the group II-VI layer with etching of both the resist and the group II-VI layer then continuing simultaneously and at substantially the same etch rate until all of the resist has been removed. The etching takes place in a chamber having a parallel plate RF plasma etcher using a dry etchant which uses the RF plasma. The etchant is a hydrogen and oxygen combination at low pressure which is activated by the RF excitation. An inert gas, preferably argon, and methane can optionally be added to the gas flow. The flow rate at each inlet is continuously adjustable. The flow of gas into the chamber continues while the chamber is also being pumped simultaneously to maintain the desired pressure within the chamber. This produces hydrogen radicals and oxygen radicals and this mixture etches both the group II-VI insulator and the photoresist. By controlling the etch conditions, the group II-VI insulator and the photoresist are etched at the same rate.