ELECTRON CYCLOTRON RESONANCE (ECR) SEMICONDUCTOR ETCHING PROCESS CONTROL BY ELLIPSOMETRY

THE NEED FOR SMALLER SEMICONDUCTOR DEVICE STRUCTURES FOR USE IN VERY HIGH SPEED MICROELECTRONICS REQUIRES A NEW GENERATION OF PLASMA ETCHING TECHNOLOGY. ECR PROMISES TO PROVIDE FEATURES AS SMALL AS 0.2 MICRONS IN SIZE, AS WELL AS A HIGH DEGREE OF ETCHING ANISOTROPY, SELECTIVITY, ETCH RATES, AND LOW DAMAGE. FOR MANUFACTURING PROCESS CONTROL INVOLVING ECR ETCHING IN PRODUCTION OF ELECTRONICS AND OPTO-ELECTRONICS ON SILICON AND COMPOUND SEMICONDUCTORS, CONSIDERABLE FURTHER RESEARCH AND DEVELOPMENT IS NEEDED. SPECTROSCOPIC ELLIPSOMETRY USES POLARIZED LIGHT REFLECTANCE, AND HAS SENSITIVITY TO SURFACE AND INTERFACE EFFECTS A FRACTION OF AN ATOMIC MONOLAYER THICK. THUS SURFACE DAMAGE, SURFACE ROUGHNESS, AND SURFACE COMPOUND/ALLOY STOICHIOMETRY CAN BE DETERMINED. WE RECENTLY DEVELOPED THE ABILITY TO CONVERT ELLIPSOMETRIC PSI AND DELTA DATA IN REAL TIME INTO DESIRED MATERIALS PROPERTIES SUCH AS THICKNESS, ALLOY RATIO, SURFACE TEMPERATURE DURING SEMICONDUCTOR CRYSTAL GROWTH. THE PURPOSE OF THE PROPOSED RESEARCH IS TO DEMONSTRATE THAT SPECTROSCOPIC ELLIPSOMETRY WILL BE EFFECTIVE IN MONITORING AND CONTROLLING ECR ETCHING OF III-V (E.G., INGAAS) AND II-VI (E.G., HGCDTE) SEMICONDUCTOR MATERIALS. A MAJOR GOAL IN PHASE I IS TO DEMONSTRATE THAT ELLIPSOMETRIC SENSING CAN DETERMINE ETCH RATES IN REAL TIME, AND TO DEMONSTRATE THE ABILITY TO STOP AN ETCH AT A PRECISE PRESELECTED DEPTH.