An investigation of improved titanium/titanium nitride barriers for submicron aluminum-filled contacts by energy-filtered transmission electron microscopy

The adaptation of titanium/titanium nitride barriers which are commonly used for tungsten-filled contacts to aluminum-filled contacts has encountered some limitations. A main issue is the decomposition of titanium nitride manufactured by physical vapour deposition through reaction with aluminum. In this investigation two different concepts for barrier improvement have been pursued: 1. stuffing of a conventional barrier by a rapid thermal process in an oxygen-rich atmosphere and, 2. use of a barrier manufactured by chemical vapour deposition. The aim of the transmission electron microscopic analysis was to explain different electrical breakdown characteristics during thermal stressing of chips with these barriers. Energy-filtered transmission electron microscopy was used to monitor elemental distributions down to nanometer scale. Both concepts are found to improve barriers for aluminum-filled contacts.