Highly selective SiO2 etching in low-electron-temperature inductively coupled plasma

Abstract

We develop a new oxide etching system having a low-electron-temperature plasma by setting a grid in the middle of the chamber. The electron temperature is less than 1.1 eV at 15 mTorr. We carry out the etching of silicon dioxide in the system to investigate the etching characteristics in a low-electron-temperature plasma. The etching characteristics after setting the grid are very different from those in the absence of a grid. The low dissociation rate due to the low electron temperature can explain such a difference. With the grid method, we can obtain a high etching selectivity of oxide for the photoresist of 74, which is ten times higher than that in the case without the grid.