The direct resist-free deposition of a lithographic mask from vapor initiated by an electron beam

Abstract

A dry resist-free process of electron-beam vapor deposition of an undecane precursor (C11H24) mask on SiO2-on-silicon and copper-on-silicon substrates was studied. The band section was trapezoidal, and the band width at the base was much larger than the diameter of the electron beam and depended on the substrate (it was three or four times larger on copper than on SiO2). In mask deposition on copper, the mask thickening rate v was found to depend strongly on the scan time τsc when scanning was performed along the band. When τsc changed from 20 ms to 13 s, v decreased by a factor of 7.4 (beam current 1.0 nA). This was probably caused by significant diffusion delay of precursor transport to the reaction zone during pixel time when τsc was 13 s. The ion-beam etching of the substrates through the deposited masks was performed (the SiO2 substrate was etched with SF6 ions, and the copper substrate, with Ar ions).