ALD Ru and its Application in DRAM MIM-Capacitors and Interconnect

Abstract

Ruthenium is proposed as electrode for next generation DRAM metal-insulator-metal capacitors and interconnect barrier/seed. This study compares different ALD processes to deposit Ru and RuO2 films. ALD with oxygen results in the deposition of either Ru or RuO2, depending on deposition conditions. We also report the growth and scalability of Ru films by plasma-enhanced ALD (PEALD) with ammonia. The inorganic precursor RuO4 was studied as an alternative chemical pathway, of which the characteristics and film properties were studied at temperature range 100-250ºC using various process conditions. The quality of films deposited with thermal ALD and PEALD is compared with respect to the targeted applications. In particular, the investigation of the thermal stability of the different Ru and RuO2 films under typical DRAM anneal conditions is presented.