Steven Marcus

TiCl4 as a Precursor in the TiN Deposition by ALD and PEALD

This study explores TiN film deposition using the plasma enhanced atomic layer deposition (PEALD) technique, comparing the results of PEALD-TiN with the previous results of ALD-TiN and ALD-TiN with in situ reduction. Eachof the studies used TiCl 4 precursor as the titanium source. The ALD-TiN study used ammonia as the reducing agent. Nitrogen and hydrogen gases are not reactive in the ALD-TiN deposition, but they were successfully used in PEALD-TiN. This study shows that the concept of self-saturating reaction in ALD differs from PEALD. Although the growth rate saturates as a function of pulse lengths, the number of active surface sites and the film composition can be changed by the plasma pulsing parameters. In all deposition techniques the TiN films exhibit excellent film properties including low resistivity, low impurity concentration, and high-density films. PEALD provides significant advantages if the deposition temperature is lower than 350°C.

Nanochemistry, nanostructure, and electrical properties of Ta2O5 film deposited by atomic layer deposition and plasma-enhanced atomic layer deposition

Ta2O5 films were deposited by plasma-enhanced atomic layer deposition (PEALD) and thermal ALD on native oxide surface (SiOx∕Si). The properties of as-deposited and forming gas annealed films were examined and qualitatively compared with respect to nanostructural, nanochemical, capacitance-voltage and leakage-current–voltage (JL-V), and oxide breakdown characteristics. Although high-resolution transmission electron microscopy showed structurally sharp Ta2O5∕SiOx interfaces in forming gas annealed PEALD Ta2O5∕SiOx∕Si stacks, electron energy loss spectroscopy revealed interdiffusion of Ta and Si across this interface, the indiffusion length of Ta being higher than the outdiffusion length of Si. The consequent formation and enhancement of Ta–O–Si bond linkages in thicker Ta2O5 films were clearly reflected in the JL-V data. Moreover, the fixed charge density (Qf=5×1011qC∕cm−2) was thickness invariant in PEALD Ta2O5. For similar PEALD and ALD Ta2O5 thickness in Ta2O5∕SiOx∕Si stacks, the latter showed a lower Di...