Experimental study of proximity effect corrections in electron-beam lithography

The computer aided proximity effect correction program CAPROX has been used to correct structures written at 20 keV electron beam energy. A new method has been developed to determine proximity parameters for a given e-beam/resist/substrate system. Proximity parameters for PMMA and EBR-9 and chemically amplified negative resist AZPN114 have been determined, and compared with those obtained from the established 'doughnut method'. The new method provides more reliable and accurate values, particularly for the forward scattering range. The dependence of (alpha) , (beta) and (eta) on resist thickness was also measured and the sensitivity of proximity correction using CAPROX to variation in all three scattering parameters was demonstrated. The new method improves CD linewidth linearity and accuracy in the range 0.1 approximately equals 4.0 micrometers , achieving linewidth for both lines and gaps within 100 nm of designed size.