IN-SITU CHARACTERIZATION OF THE TRANSIENT-BEHAVIOR OF PARTICLES IN LOW-PRESSURE PLASMAS

Contamination due to plasma-generated particles is one of the major is sues affecting the yield loss in microelectronics fabrication. Laser l ight scattering performed in situ during the process provides importan t information about particle distributions both spatially resolved and as a function of time. It is therefore well suited for the investigat ion of the transient behavior of process-generated particles that can influence the performance of etching or deposition plasmas. The presen t light scattering system allows the quantitative determination of par ticle size and number density by detecting the scattering intensity at two separate angles (angular dissymmetry) and/or at two different pol arization states (polarization dissymmetry), respectively. A special c alibration procedure is required in order to obtain quantitative resul ts for particle size and number density. Based on this analysis, we re port the temporal evolution of the spatial distribution of aluminum pa rticles in an argon discharge. We examine the transition from a contin uous cloud of particles filling the entire interelectrode gap to a nar row band of intense scattering near the grounded electrode. Other chan ges of light scattering patterns with time have been observed under ot her conditions. The implications of these observations in terms of par ticle generation and evolution in gas discharge plasmas are discussed. (C) 1996 American Vacuum Society.