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Plasma Etching for desired nano-Feature shape and nano-texture: An Advanced Reactor and Simulation Software for Feedback-Loop Plasma Control

Final Report Summary - NANOPLASMA (Plasma Etching for desired nano-Feature shape and nano-texture: An Advanced Reactor and Simulation Software for Feedback-Loop Plasma Control)

Through plasma and surface modelling software, plasma diagnostics and improved plasma etch tool design, the 'Plasma etching for desired nano-feature shape and nano-texture: an advanced reactor and simulation software for feedback-loop plasma control' (Nanoplasma) project aimed to improve the reproducibility and control of some of the more difficult etching processes at the nanoscale.

Notable achievements of the project were:

- a validated software simulation of plasma etching, working from process control inputs (gas flows, plasma power…) directly to etch rate and etch profile of a gas-chopped silicon etch process. This is believed to be a world first to obtain an integrated code of this kind.
- An advanced plasma etcher featuring a new plasma source, radio frequency (RF) automatch, integrated spectroscopy and closed loop control features, shown to reduce substantially the variation of etch rate with exposed silicon area (the loading effect), and to be capable of very high aspect ratio silicon etching.
- A robust plasma resonance probe (the hairpin probe) which measures electron number density in reactive gas plasmas with unprecedented precision.
- Nanoscale roughness control in plasma etching: a theoretical and experimental demonstration of the cause of nanoscale roughness evolution during plasma etching, showing both how to reduce the roughness, or to use it as a method to create 50 nm textured pillars.

The consortium of one industrial partner, two SME partners and three academic institutes have produced significant outputs, notably:

- A plasma etch tool incorporating a new plasma source and control system, shipped two beta versions to the molecular foundry at LBNL, USA;
- A plasma etch simulator ready for beta shipment. It will be pursued first via a collaboration with LBNL, USA;
- A new plasma diagnostic hardware ready for beta shipment;
- 15 academic journal articles;
- 50 academic conference publications;
- 4 patent applications.

The academic output should be noted for its productivity, especially from Demokritos.

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