Application of a dielectric discontinuity microscope to process development at the Fairchild Research Center of National Semiconductor

摘要

Abstract: A new type of microscope (DDM) has been applied tosubmicron process development at the Fairchild ResearchCenter. This high resolution video microscope producesan image which is the superposition of a dielectricdiscontinuity (phase contrast) and an absorptiveoptical image. With this instrument a Sparrow'sresolution of 0.08 $mu@m has been achieved atmagnifications from 1150 times to 18,000 times. VIA andcontact clearing have been observed from 0.1 $mu@m to1.4 $mu@m at aspect ratios of up to 3:1. CDmeasurements have been made on both latent images anddeveloped images and the results used to optimize theexposure energy for an I-line stepper. The DDM has alsobeen used to visualize defects which are not visiblewith conventional microscopy. Both metallic anddielectric contaminant films have been detected and asubmicron dielectric sidewall has been visualized on anadvanced interconnect system. Material deposited duringdevelopment using the MIMMI process has been observed.A simplified phase contrast transition theory ispresented and applied to the observations. !7