Particle trapping, transport and charge in capacitively and inductively-coupled plasmas in a gaseous electronics conference RF reference cell

Abstract

Particle contamination from plasma tools used for the manufacture of VLSI semiconductor devices on silicon wafers is a major cause of device failure. This has fostered a need to understand the fundamentals of particle transport and trapping in plasmas of the kind used to process semiconductor devices. This dissertation reports on particle transport and trapping in two types of plasmas. Particles in both a capacitively coupled and an inductively coupled plasma were investigated in a Gaseous Electronics Conference (GEC) radio frequency (rf) reference cell using a new method of laser light scattering and detection. In a capacitively coupled plasma the role of thermal force and coulombic force on particle transport in post-plasma period was determined through experiment. The charge on particles in the post-plasma was also determined through analysis of particle motion and found to be 1.4 to 12.4 elemental charges per particle. Particle trapping in a capacitively coupled plasma was determined for a simple subsurface electrode structure. For an inductively coupled plasma, the a technique of particle detection is utilized to image particles despite a bright emission from the plasma. Particle trapping was observed to be quite different from trapping in a capacitively coupled plasma, and the post-plasma motion of particles is reported.