MICROCONTAMINATION REDUCTION IN PLASMA PROCESSING THROUGH CHARGE STATE MODIFICATION

PLASMA PROCESSING HAS MOVED TO THE FOREFRONT OF INTEGRATED CIRCUIT (IC) FABRICATION TECHNOLOGY. CONTAMINANTS CONTINUE TO PLAGUE THE INDUSTRY BEING RESPONSIBLE FOR MORE THAN 50 PERCENT OF THE YIELD LOSSES. THESE PARTICLES ALSO ACT TO LIMIT THE FEATURE DENSITY ON THE IC WAFERS. ADVANCES IN CLEANROOM TECHNOLOGY HAVE RESULTED IN THE PLASMA PROCESSOR BEING THE MAIN SOURCE OF MICROCONTAMINANTS. PARTICLES IN THE DISCHARGE HAVE BEEN OBSERVED TO CONGREGATE IN ELECTROSTATIC TRAPS NEAR THE WAFER. THE PRECIPITATION OF PARTICLES FROM THESE TRAPS IS A MAJOR SOURCE OF CONTAMINATION. RESEARCHERS ARE ACTIVELY CLEANING THE PARTICLE TRAPS BY MODIFYING THE CHARGE ON THE PARTICLES. THIS DISRUPTS THE ELECTROSTATIC TRAP CONFINEMENT ALLOWING THE PARTICLES TO BE REMOVED.