Kyoung-won Lee

Prevention of adhesion failure of a W/TiN/Ti(Co) layer on SiO2

Abstract The delamination of W/TiN/Ti(Co) based metal lines was investigated. The adhesion failure was mostly induced by the formation of an interfacial layer between metal liner and inter-layer-dielectric (ILD) oxide. This interfacial layer could be a TiF x , formed by reaction between Ti and WF 6 during W deposition, or a ‘reacted layer’ caused by reaction between Ti (or Co) and ILD oxide at relatively high temperature. The quality of TiN barrier layer was a key factor influencing the formation of TiF x during W deposition. On the other hand, stripping of TiN/Ti (Co) liner after rapid thermal nitridation (RTN) was an essential process to prevent the reaction between the Ti (Co) and SiO 2 during the post high temperature processes. The RTN temperature should be lower than 600°C to minimize the interaction between the liner and ILD oxide. RF sputter cleaning after liner stripping was an effective method to remove the interfacial layer and to prevent the delamination of the metal layers.