Fig. 8

The DODE nanolithography process is demonstrated. a Cross sectional SEM images of a 50 nm of grooved nanostructure prepared via the DODE lithography process; a nanopattern on a residual SiO2 layer after isotropic deposition of a second SiO2 layer (inset shows high magnification image of the nanopattern) and SiO2-based grooved nanostructure on a Si substrate after anisotropic dry etching of a second SiO2 layer (inset shows high magnification image of the nanostructure). The nanopattern was obtained through 2nd SiO2 deposition process using PECVD on lithographically patterned microstructure. Then, the residual layer under nanopattern was removed using ICP etching process to define high aspect-ratio nanostructure. b Linewidth in microstructure is reduced according to the increased thickness of the second SiO2 layer by isotropic thin film deposition process (inset shows the SEM images of the 2nd SiO2 deposited nanopatterns). The linewidth of micropatterns was gradually decreased as the increase in 2nd SiO2 thickness up to 50 nm of nanopatterns. c Investigations of the anisotropic plasma etching process in terms of the effects of pressure, oxygen gas flow rate, and platen power. Anisotropy (A) increased as decrease in pressure and O2 gas flow rate, and increase in platen power (straight and dash lines represent anisotropy and etch rate, respectively) [51]