An Autonomously Controllable Plasma Etching System Based on Radical Monitoring

The optimum conditions for a plasma etching device are generally determined from the results of etching a sample while varying an external parameter (e.g., gas mass flow, gas mixing ratio, process chamber pressure, or plasma source power). However, to realize controlled plasma etching with few fluctuations on a subnanometer scale, it is essential to develop a system that is controlled in real-time based on internal plasma parameters (e.g., densities and energies of radicals and ions), which directly determine process characteristics, rather than external plasma parameters. We have developed an autonomously controlled plasma etching system that performs integrated monitoring of radicals in the gas phase and on the surface of films. The etching rate of organic materials could be autonomously controlled based on hydrogen and nitrogen radical densities obtained in real-time.