PLASMA PARTICULATE CONTAMINATION CONTROL .1. TRANSPORT AND PROCESS EFFECTS

The transport and behavior of particulates during plasma processing is imaged in real time using rastered laser light scattering combined with video detection. Results show the distribution of particles is highly ordered and predictable. Two effects have major influence on the distribution and location of particles: feed gas drag and electrostatic traps. Particle traps form from plasma disturbances and design properties of the electrode and the tooling. These results are confirmed in normal plasma conditions used in microelectronics fabrication. A strategy is presented for plasma contamination control. Complete elimination of trapping effects is not feasible. Instead, process techniques are used to minimize or defeat the attractive nature of the traps. Several examples are discussed.