Al-PLAPH (Aluminum-PLANarization by Post-Heating) process for planarized double metal CMOS applications

Contact planarization in ULSI multi-level interconnections has been achieved by using a newly developed contact filling technology called Al-PLAPH (Aluminum-Planarization by Post-Heating). In the Al-PLAPH process, Al was initially deposited at room temperature without any substrate bias followed by an annealing step without breaking vacuum. In-situ annealing was carried out at a temperature range of 400°C~550°C in a vacuum-isolated modular sputtering system. Sub-micron contacts with high-aspect-ratio (⩾1) were completely filled by heating above 500°C. The process has been applied to a full CMOS device which did not show any degradation of electrical characteristics such as contact resistance and junction leakage. Reliability tests with line test patterns revealed better electromigration resistance with enhanced stress migration tolerance than conventionally grown Al lines