A SURFACE PLASMON MONITOR FOR IN-SITU THIN FILM ANALYSIS

PERFORMANCE OF OPTICAL DEVICES IS GREATLY AFFECTED BY SMALL SURFACE IRREGULARITIES. IN X-RAY OPTICS, FOR INSTANCE, ROUGHNESS CHARACTERIZED BY A ROOT-MEAN-SQUARE HEIGHT OF A FEW ANGSTROMS ON A THIN FILM SURFACE CAN SEVERLY AFFECT DEVICE PERFORMANCE, AND HIGHLY SENSITIVE TOOLS ARE GENERALLYREQUIRED FOR CHARACTERIZATION. SOPHISTICATED METHODS BASED ON X-RAY AND ELECTRON PROBE TECHNIQUES ARE RATHER SENSITIVE IN THE ANALYSIS OF STRUCTURE AND COMPOSITION OF THIN FILMS. HOWEVER, THE COMPLEXITY AND HIGH COST INVOLVED IN ADAPTING THESE TECHNIQUES FOR ON-LINE THIN FILM MONITORING, E.G., FORQUALITY CONTROL, LIMIT THEIR USE TO SPECIALLY DESIGNED VACUUM DEPOSITION SYSTEMS. EXISTING OPTICAL METHODS ARE RELATIVELY SIMPLE TO IMPLEMENT FOR ON-LINE THIN FILM THICKNESS MONITORING, BUT IN GENERAL CANNOT YIELD INFORMATION ON SURFACE STRUCTURE. IN THIS PROJECT, LIMITATIONS FOUND IN CONVENTIONAL OPTICAL TECHNIQUES ARE ELIMINATED BY EMPLOYING THE SURFACE PLASMON RESONANCE PHENOMENON FOR THE ANALYSIS OF THIN FILMS. IT WILL BE DEMONSTRATED THAT THE NEW TECHNIQUE IS CAPABLE OF SIMULTANEOUSLY MEASURING THIN FILM OPTICAL CONSTANTS, SUBMICROSCOPIC SURFACE ROUGHNESS, AND THICKNESS DOWN TO SUBANGSTROM DIMENSIONS. THE MOST PROMINENT FEATURE OF THE PLANNED APPROACH IS THE POTENTIAL FOR MULTIPARAMETER PROCESSING BY USE OF RELATIVELY SIMPLE OPTICAL PRINCIPLES AND LOW COST INSTRUMENTATION. PHASE I OF THE PROJECT COMPRISES THE DESIGN OF A PROTOTYPE INSTRUMENT AS WELL AS THEORETICAL AND COMPUTER SOFTWARE DEVELOPMENT FOR DATA PROCESSING. DURING THIS PART OF THE RESEARCH, THE FEASIBILITY OF THE APPROACH IS BEING TESTED FOR ACCURACY ANDSENSITIVITY IN THE MULTIPARAMETER EVALUATION OF SILVER AND GOLD FILMS PREPARED ON GLASS SUBSTRATES. PHASE II RESEARCH AND DEVELOPMENT WILL EXTEND THE PHASE I WORK TO INCLUDE ALTERNATIVE FILM-SUBSTRATE COMBINATIONS AND FOCUSES ON THE DEVELOPMENT OF A COMPACT, ALL-SOLID-STATE RUGGED OPTICAL DEVICE TO BE USED INSIDE A FILM PREPARATION CHAMBER FOR REAL-TIME SURFACE AND THIN FILM CHARACTERIZATION DURING GROWTH.