A robust method for etching an organic low-k insulating layer on a semiconductor device, as disclosed herein, includes introducing into a processing chamber a substrate with an organic insulating layer and an overlying mask layer having an aperture. A plasma is then developed within the chamber from an oxidizing gas and a passivation gas. The passivation gas is preferably either a silicon containing gas or a boron containing gas, or both. The ratio of the oxidizing gas to the passivation gas is preferably at least 10:1. In addition, an inert carrier gas may be provided. The plasma is then used to etch the organic insulating layer through the mask layer, thereby forming a via having essentially vertical sidewalls in the organic low-k insulating layer.