The results of the NRL program focuses on high resolution, high aspect ratio, patterning of W are summarized. The work investigates three parallel approaches: reactive ion etching (RIE), electron cyclotron resonance (ECR) etching, and chemically assisted ion beam etching (CAIBE). Key issues that are analyzed for each process are the etch mask, anisotropy, selectivity, etch stop, compatibility with high resolution (sub-250 nm) lithographic patterning of W, and applicability to membranes. In the first two methods, prevention of sidewall undercutting was the key issue. Here the effort focuses on sidewall passivation and substrate cooling. RIE is a commonly utilized fabrication tool and the process has been developed to etch 100 nm lines. ECR is a relatively new process and there are more degrees of freedom than RIE. Both SF6 chemistry and CBrF3 chemistry have been investigated. Methods to minimize the mask erosion are described and a comparison of Cl2 chemistry to SF6 chemistry is made. The results on the three dry etching techniques are described and contrasted.