Asynchronous pulse-modulated plasma effect on the generation of abnormal high-energetic electrons for the suppression of charge-up induced tilting and cell density-dependent etching profile variation

Abstract

The formation of high-energy electrons and ion fluxes induced by an abnormal electron heating mode in asynchronous pulse-modulated plasma was investigated using particle-in-cell simulation. We demonstrate that the abnormally high electron heating mode was induced only for a short time in the asynchronous pulsed plasmas. Furthermore, enhanced production of energetic electrons accompanies this electron heating. In particular, the higher energy electrons (ε > 20 eV) are mainly produced by the abnormal electron heating during the first period of the abrupt sheath expansion phase in the asynchronous pulsed plasma with α1 = α3 = 0.05. These high-energy electrons are crucial for tailoring the expansion of plasma density and neutralizing the surface charging for the HARC etching process. A synergy of higher energy electrons and higher density ion fluxes in asynchronous pulsed plasma can be a promising solution to reduce statistical variation and charging-induced profile deterioration without the etch rate reduction in 3D NAND fabrication.