ANALYSIS OF PROCESS INDUCED DAMAGE BY SUBSURFACE SCATTER MEASUREMENT

LIGHT SCATTERED FROM CLEAN SEMICONDUCTOR WAFERS IS DUE TO BOTH SURFACE AND SUBSURFACE DEFECTS. SCATTER FROM SURFACE DEFECTS GENERALLY DOMINATES BY AN ORDER OF MAGNITUDE OR TWO. A METHOD TO SEPARATE SUBSURFACE SCATTER FROM SURFACE SCATTER HAS BEEN FOUND, AND IT IS PROPOSED HERE TO UTILIZE THAT TECHNIQUE TO INDICATE THE LOCATION AND AMPLITUDE OF SUBSURFACE DEFECTS BY COLOR MAPPING THE LOCATION AND INTENSITY OF SUBSURFACE SCATTER. THE PROPOSED DESIGN WILL ALLOW FAST MAPPING OF SEMICONDUCTOR WAFERS AT ADJUSTABLE RESOLUTIONS AND WILL PROVIDE FEEDBACK INFORMATION TO HELP IMPROVE THE PROCESSES USED TO FABRICATE III-IV AND II-V SEMICONDUCTOR WAFERS. MAPPING SPEEDS IN EXCESS OF ONE MILLION PIXELS/MINUTE ARE BELIEVED POSSIBLE IN A PHASE II VERSION OF THE INSTRUMENT. THE INFORMATION AVAILABLE FROM THE SYSTEM IS EXPECTED TO HAVE A VERY POSITIVE IMPACT ON REDUCING IN PROCESS DAMAGE IN II-V AND III-IV WAFERS.