Enhanced Process Control for Dry Etching of Functional TiN Structures on 300 mm Wafer Level

Titanium nitride (TiN) is an attractive material for various applications due to its unique physical, chemical and electrical properties. Heterogeneous system integration (HI) is a key driver in advanced packaging and has seen increased interest in TiN for new innovative applications. Despite its established use in integrated circuits, TiN patterning processes have been scarcely investigated on 300 mm wafer level. In this study, we investigated the influence of different dry etching process parameters, such as CF4/SF6 mixing ratio, process pressure, total gas flow, inductively coupled plasma (ICP) power, and bias power on the TiN etch rate, selectivity of the TiN etch rate to the etch rate of photoresist, and substrate materials Si, SiO2, polyimide on 300 mm wafers using image reversal photoresist. The study results reveal complex dependencies of TiN etching characteristics on these process parameters, identifying key parameters such as total gas flow, process pressure, and ICP power as universal tuning settings. The CF4/SF6 ratio has a significant, yet inversely proportional, impact on the TiN etch rate and its uniformity. A positive correlation between the TiN etch rates, selectivities, and their uniformity, along with the flank angles of etched TiN structures were observed. Furthermore, a correlation between the uniformity of the TiN etch rate and the average depth of substrate over-etching during TiN patterning was identified. These investigations provide substantial advancements in TiN patterning processes on 300 mm wafers under pilot-scale manufacturing conditions, delivering crucial insights for optimizing process performance and quality yield. The findings support the further integration of TiN patterning in advanced packaging technologies, addressing the challenges of smaller critical structure dimensions.