Nanoscaled niobium trilayer technology, using temperature controlled pattern transfer

We study the etching behavior of niobium in a pure SF6 plasma at low bias voltage as a function of substrate temperatures for a low- and high-atomic fluorine/ion density ratio plasma regime. The experiments are performed in an electron cyclotron resonance (ECR) etcher to obtain a well-controlled independent set of decoupled plasma parameters. An increase of activation energy from 0.1 to 0.4 eV is observed at 20 °C in the high atomic fluorine density/ion density ratio plasma regime. In contrast to the low atomic fluorine/ion density ratio regime, where the activation energy stays constant at 0.1 eV for the studied temperature range. We use this etching behavior to explore a process window for anisotropic niobium etching.