Effect of Chelating Agents on High Resolution Electron Beam Nanolithography of Spin-Coatable Al2O3 Gel Films

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Abstract
The effect of chelating agents on the electron beam exposure characteristics as well as environmental stability of the spin-coatable Al2O3 gel films is discussed. It was found that the Al2O3 gel films prepared by reacting aluminium tri-sec-butoxide, Al(OBus)3, with acetylacetone (AcAc), AcAc/Al2O3, gave better environmental stability and patterning characteristic than the gel films prepared by reacting the Al(OBus)3 with ethylacetoacetate (EAcAc), EAcAc/Al2O3. The latter suffered from a faster moisture attack in the laboratory atmosphere. Both EAcAc/Al2O3 and AcAc/Al2O3 films are ∼106 times more electron beam sensitive than sputtered AlO x films, thus bringing the formers' sensitivity very close to some of the organic electron beam resists. It was seen that the baking temperature up to 70°C has almost no effect on either the sensitivity or the contrast in both the films; but it has a significant effect on the developing characteristics. Electron beam nanolithography gave 20 nm linewidth with a rectangular cross-section in both EAcAc/Al2O3 and AcAc/Al2O3 films. It was observed that the etching characteristics of Al2O3 films in the electron cyclotron resonance (ECR) plasma are dependent upon the final baking temperature of the developed pattern. Preliminary plasma etching studies show that 15 nm lines on polysilicon can be etched.