Comparison of Existing Linewideth Measuring Systems to an Experimental Unit that Enables Minimization of Vibration During Measurement

An experimental unit was built to minimize vibration during measurement of linewidths on integrated circuit photomasks. Linewidths in the range of 0.522 microns to 12.076 microns were measured with the Nikon LASER scanning system. Optical Specialties Inc. VLS-I video system, Nikon Micro Pattern Analyzer slit-scanning system, and the experimental unit. Average variances of 0.0096, 0.0164, 0.0377, and 0.3627 were calculated for each system respectively. The variances were compared using an F-test with the result that each system was significantly different for each linewidth. A mathematical model was derived to predict the smallest resolvable detail given the frequency and amplitude of vibration, the exposure time of the camera, numerical aperture of the objective, magnification of the system, and the size of the elements in the imaging array