A complete dry lithography using plasma processes

Abstract

Abstract This work was carried out to develop a pattern, on the nanometer scale, using plasma polymerization and plasma etching. It is also aimed at developing a resist for the nano process and a vacuum lithography process. The thin films of plasma polymerization were fabricated by the plasma polymerization of inter-electrode capacitively coupled gas flow system. After delineating the pattern, an accelerating voltage of 30 kV, varying the dose in the range 1–500 μC/cm2, the pattern was developed with dry type and formed by plasma etching. Analyzing the molecule structure using Fourier transform-infrared spectrometry (FT-IR), it was confirmed that the thin films of plasma polymerized methylmethacrylate+styrene+tetramethyltin (PPMST) contain the functional groups of the methylmethacrylate+styrene+tetramethyltin (MST) monomer. The thin films of PPMST had a highly cross-linked structure resulting in a higher molecular weight than the conventional resist. The deposition rate of the PPMST thin films was 230–600 A/min as a function of 50–200 W power and 200–60 A/min as a function 0.1–0.7 Torr pressure. The etching rate of the thin films of PPMST was 875–3520 A/min as a function of 50–200 W power and 2870–360 A/min as a function of 0.2–0.7 Torr pressure. The sensitivity and contrast of the PPMST resist were 5 μμC/cm2 and 4.5 respectively. The resolution of the resist was 50 nm and various patterns having sizes 0.2 m, 100 nm, 70 nm , 50 nm and 35 nm and 20 nm were successfully formed.