Modeling RF glow discharges for microelectronics manufacturing processes.

Abstract

The semiconductor industry is dependent on the use of plasma processing techniques for many steps in the manufacture of integrated circuits. Despite their heavy use, plasma processes remain relatively poorly understood. Computer models of these processes show great promise as a means of gaining more knowledge about these processes. The work presented in this thesis is aimed at developing rf glow discharge models for simulating reactive ion etching. Two rf glow discharge models are presented. The first model is based on the moments of the Boltzmann transport equation. This continuum model can be used to simulate any arbitrary mixture of gases. Swarm parameter data for this model are calculated using a Monte Carlo model which simulates a charged particle drifting in a uniform electric field. Experimental verification of the model is made with an argon rf glow discharge. Results of an oxygen rf glow discharge is also presented to show the models ability to simulate more complex discharges. The second rf glow discharge model merges particle and Monte Carlo modeling techniques. This model represents the discharge as a large swarm of particles which interact with each other through their self-generated electric field and with the neutral background gas through random collisions. Because of the few assumptions used to formulate the model, it is valid for all rf glow discharge operating conditions. Results from simulations with this model are compared with results from the continuum rf glow discharge model and with experimental measurements.