OVERLAY AND GRATING LINESHAPE METROLOGY USING OPTICAL SCATTEROMETRY

IN MICROELECTRONICS PROCESSING DIFFRACTION GRATING TEST PATTERNS ARE CREATED ON THE WAFER FOR CHARACTERIZING A PROCESS STEP. IN THIS APPLICATION THE SHAPE OF THE LINE IS MEASURED SINCE IT IS DETERMINED BY PROCESSING CONDITIONS. COMPLETE CHARACTERIZATION OF GRATING LINESHAPE IS TEDIOUS AND OFTEN DESTRUCTIVE, SUCH AS BY USING SEM TECHNIQUES. RAPID, NON-CONTACT, NON-DESTRUCTIVE TECHNIQUES TO CHARACTERIZE GRATING LINESHPAE DO NOT EXIST, ESPECIALLY FOR SUB-MICRON GEOMETRIES AND FOR IN-SITU APPLICATIONS. THIS PHASE I EFFORT ADDRESSES NOVEL TECHNIQUES TO DETERMINE LINESHAPE, BASED UPON SCATTERED LIGHT. THE INTENSITY OF LIGHT DIFFRACTED INTO DIFFERENCT ORDERS IS VERY SENSITIVE TO THE LINESHAPE (E.G., THE HEIGHT AND WIDTH, FOR A SPECIFIC PITCH), AND THIS DISTRIBUTION IS EASILY MEASURED. DEVIATIONS FROM THE OPTIMAL SHAPE, DUE TO PROCESSING ERROS, CAN BE EASILY BE MONITORED. QUANTITATIVE GRATING LINESHAPE DATA OBTAINED USING STATISTICAL ANLYSIS OF SCATTERED LIGHT WHICH IS BASED ON A RIGOROUS DIFFRACTION ANALYSIS. WE WILL IDENTIFY KEY APPLICATIONS FOR MONITORING PROCESSING IN CLUSTER TOOL ARRANGEMENTS AND OVERLAY, DESIGN SCATTEROMETER ARRANGEMENTS FOR THESE APPLICATIONS, AND DETERMINE OPTIMAL ANALYSIS TECHNIQUES TO USE. THESE WILL BE IMPLEMENTED IN A PHASE II EFFORT. ANTICIPATED BENEFITS: OVERALY AND PROCESS MONITORING ARRANGEMENTS WILL BE DEVELOPED FOR SMALL GEOMETRIES.