Deep submicron contact fabrication by electron beam direct writing with intraproximity effect correction

Abstract

Electron beam (EB) direct-writing lithography with intraproximity effect correction has been developed for fabricating contact holes having deep submicron size. The dimensional accuracy of contact holes is strongly influenced by the intraproximity effect. In delineating contact hole patterns by using EB direct writing, it is necessary to increase the exposure dose a great deal. This is because the effect of backscattered electrons on the smaller hole patterns is decreasing. It was found that the forward scattering parameter in proximity function should be optimized in order to obtain high dimensional accuracy for contact holes with the minimum feature size of 0.2 μm. The accuracy within ±0.03 μm was realized for contact holes with their dimensions from 1.0 to 0.2 μm at the same time by using present intraproximity effect correction and noncharging trilayer resist process. When this high-performance EB direct writing was applied to fabricate 0.2 μm size contact holes, the yield of the 104 contact hole chains was improved to over 95% by using selectively deposited W film on the bottom of the contact holes.