Plasma-based cleaning and stripping for semiconductor applications.

摘要

This thesis presents results from dry plasma cleaning and stripping studies applied to semiconductor industry relevant materials. Particular focus has been placed upon developmental stages critical to the fabrication of advanced integrated circuits. These studies ranged from reactor cleaning suitable for amorphous silicon deposition systems, to organic thin film removal both on blanket surfaces and within actual structures. Generally, several gas phase and surface analysis techniques were used to obtain mechanistic insights towards the reactions critical to these cleaning and/or stripping technologies. These methods include in-situ ellipsometry and interferometry, mass spectrometry and optical emission spectroscopy, and x-ray photoelectron spectroscopy. Focus has been placed on gas phase chemistries using fluorine and/or oxygen and/or nitrogen as the reactive species. Both remote plasma systems devoid of sample-ion interaction and a low pressure high density plasma reactor configuration which takes advantage of ion bombardment, were used in this work. Mechanistic insights into the role of nitrogen in plasma chemistries involving fluorine and oxygen have been obtained. Such insights have allowed for a deeper understanding of both Si based etching and the removal of organic films, such as photoresist. The efficiency of organic thin film removal on several relevant metallization and barrier layer conductors have been evaluated along with the effects on the dielectric layers which are, by the nature of the process, exposed to the cleaning chemistry during the metal treatment. The effect of feature geometry on these cleaning processes has been studied, and novel insights into the role of aspect ratio on cleaning efficiency have been found.