Compensation for the proximity effect in electron lithography can be achieved by equalization of the backscattered dose received by all pattern points. This is accomplished by exposing the reverse tone of the required pattern with a beam diameter dc=2σb ×(1+ηe)−1/4 and dose Qc=Qe ×[ηe/(1+ηe)], where σb is the radius of the Gaussian spatial distribution function of backscattered electrons at normally exposed pixels, ηe is the ratio of backscattered to forwardscattered energy, and Qe is the dose delivered to normally exposed pixels. This correction method has been confirmed to work for 500-nm features by computer simulation of electron beam exposure and development and by experiment on a raster scan electron beam lithography system.

Thin film silicon is found to be a desirable interlayer material for e-beam lithography with multilayer resist systems. It is easily etched in CF4 plasma (Si/PMMA: 30/1) yet resists O2 reactive ion etch (Si/HPR: 1/300). It is sufficiently conductive to avoid charging effects, both during lithography and SEM inspection. High optical contrast aids in inspection. Monte Carlo calculations show that a 2.5 μm bottom layer of polymer can substantially alleviate the proximity effect, even with an 80 nm Si interlayer. Pattern transfer with less than 100 nm linewidth loss is demonstrated. Lines as narrow as 200 nm in 2 μm of Hunt positive resist were holographically produced.

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Abstract-In plasma processing, especially during the etching process in microelectronics, and as the feature size decreases, charging damage to thin gate oxides can be produced which does not occur when wet chemical processes are used. It is currently believed that such damage occurs when excess charge is deposited on a wafer because of nonuniformities in the plasma parameters across the surface of the wafer. To predict the occurrence of charging damage, unpatterned wafers are exposed to a plasma in which nonuniformity is introduced across the wafer surface. Surface photovoltage (SPV) and contact potential difference (CPD) techniques can be used to determine the regions where excess charge is deposited and thus where the potential for charging damage exists. Wafer maps of these measurements are made to show the difference between uniform and nonuniform charge distributions. Amplification -Data Acquisition Non-coherentOR THE NEXT generation of microelectronics fabrica-

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