Fluid Dynamic Modeling of Plasma Reactors

Abstract

The trend by the micro-electronic industry toward ultra large scale integrated circuits is driving the development of high plasma density sources with good plasma uniformity over a large area (up to 400 mm diameter in size). These new plasma reactor sources are used to deposit layers or to etch patterns. Characteristics of the plasma reactors under consideration are high plasma densities (≥ 10¹⁰ cm^-3) to ensure large ion flux rates to surfaces, low plasma potential (10–30 eV) to minimize surface damage, and low neutral gas pressure (≤ 30 mTorr) to minimize collisions by ions as they pass from the bulk of the plasma through the sheath so as to maintain high isotropy of the ion flux to surfaces. The high ion flux isotropy is essential for generating the sharp walled trenches used in integrated circuits. One of the most promising new sources is the inductively coupled plasma (ICP) source. One attractive feature of this source is its relative simplicity, e.g., no DC magnetic fields are required for their operation. Recent studies have reported experimental characterizations [1, 2] and computer modeling [3, 4] of these devices. Most of the studies have concentrated on smaller area ICPs. Here we present modeling of the LLNL 76 cm diameter ICP [5] and compare our results with recent measurements.