Ionized titanium deposition into high aspect ratio vias and trenches

The deposition of titanium into high aspect ratio vias and trenches is investigated using ionized physical vapor deposition (I-PVD). Sputtered titanium atoms are ionized by a high density, inductively coupled plasma of argon at 10 and 30 mTorr. The Ti+is then collimated by the plasma sheath and directionally deposited into vias and trenches ∼1 μm in width. The ability of I-PVD to deposit titanium at the bottom of narrow, deep vias and trenches is characterized by cross sectional scanning electron micrographs. The bottom coverage of 3:1 aspect ratio vias increases from 45% to 75% as the argon pressure and plasma density increase. The percentage of titanium flux that is ionized by I-PVD is extracted from analysis of bottom coverage data and falls between 50% and 85%. A method of extracting the effective transverse temperature of Ti+ is also developed. Transverse temperatures increase from 0.13 to 0.18 eV as argon pressure and radio frequency power are increased.