High-K/metal gate technology, introduced by Intel, to replace the conventional oxide gate dielectric and polysilicon gate has truly revolutionized transistor technology more than any other change over the last 40 years. First introduced at the 45nm node, this complex process has now been adopted for advanced nodes. The capability of picosecond ultrasonic measurements (PULSE™) for in-line monitoring of High-K/metal gate structures was evaluated and the benefits of this technology for measuring various structures including SRAM, pad array, and line array key with excellent correlation to cross sectional TEM was demonstrated. We have shown that, only a direct measurement of SRAM structures can represent true variations of the metal gate height due to CMP process and is strongly affected by the design and layout of pattern, including pattern density, dummy design, and spacing. The small spot, non-contact, non-destructive nature of this technology allows for in-line measurements directly on these structures with excellent repeatability at a very high throughput.
The defectivity control of replacement metal gate (RMG) chemical mechanical polishing was important for high-k metal gate (HKMG) process. Micro-scratches of RMG CMP easily caused shorting or open of devices. In this study, the micro-scratch reduction of aluminum chemical mechanical polishing (AICMP) has been investigated to provide solutions for preventing the formation of micro-scratches. Micro-scratches can be reduced by implementing soft pads at platen 2 and platen 3, pad cleaning chemical, and optimized post cleaning condition. Soft pads can reduce micro-scratch levels of AlCMP process, especially at platen 2. However, AlCMP with soft pads easily suffer serious dishing or erosion. Therefore, the balance between micro-scratches and dishing or erosion was crucial for pad selection of AICMP. Besides, removal of pad stain was also important. Pad stain removed by pad cleaning chemical could get a lower micro-scratch level of AICMP. In addition to polishing process, post cleaning process was a source of micro-scratch for AICMP. An unsuitable post cleaning condition caused a counter effect of micro-scratch reduction.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.