Plasma over-treatment effect on the MOCVD-TiN contact glue layer

In a semiconductor-device process, in-situ hydrogen/nitrogen plasma treatment is commonly used to improve the quality of metallorganic-chemical-vapor-deposition titanium nitride (MOCVD-TiN) films for application as contact glue layers. This study found that overloaded plasma-treatment energy induced an increase in the contact resistance (Rc) of patterned wafers. A possible explanation is that overloaded plasma power loosened the density of TiN films, resulting in more external oxygen diffusing into the film to form a high-resistance oxidation layer. An offline plasma-treatment index calculated by dividing the reciprocal of under-treated TiN sheet resistance by the thickness of a non-treated TiN film was developed to monitor inline Rc. The physical interpretation of the index is the received plasma energy per unit TiN thickness. The offline plasma-treatment index was linearly correlated to the Rc of patterned wafers when the MOCVD-TiN film was over-treated by plasma.