3 - Electrostatically-Shielded Inductively-Coupled RF Plasma Sources

Abstract

This chapter highlights the technological evolution of plasma sources. Inductively coupled plasmas (ICP) are as old as the process of generating plasmas. Most inductively coupled plasmas are a combination of inductive and capacitive coupling. Every researcher hoping to eliminate the effect of electrode material in the reactor has wrapped a coil around a tube and generated inductively coupled plasma. Depending upon the geometry, gas species, and pressure, the relative amounts of power delivered to the plasma by the inductively versus the capacitively generated electric field can vary greatly. Significant research in the application of inductively coupled plasmas also has occurred in the area of lighting, where inductively coupled plasma provides an efficient, although expensive, method of delivering long-lasting, energy efficient lighting sources. The development of plasma sources for use in the manufacturing of semiconductor devices has intensified the levels of research that have lead to production tools using inductively coupled plasma sources. ICPs are classified by geometric characteristics and include the following types—helical inductive couplers, spiral inductive couplers and electron cyclotron resonance (ECR) and several others. In etching applications, these sources provide much more control over the energy distribution and wider operating parameters, electron cyclotron resonance (ECR). Electrostatically shielded electrostatic RF plasma sources represent the state-of the-art in plasma technology, yet are available now with only an incremental cost versus performance trade-off.