Articles you may be interested inNanofabrication of high aspect ratio (50:1) sub-10nm silicon nanowires using inductively coupled plasma etching J. Vac. Sci. Technol. B 30, 06FF02 (2012); 10.1116/1.4755835Elaboration of high aspect ratio monocrystalline silicon suspended nanobridges by low temperature alkaline treatment of dry etched trenchesThe ability to predict and optimize the effects of the process parameters during silicon dry etching is vital for the fabrication of emerging hyperintegration technologies, as well as many microelectromechanical systems and integrated circuit devices. This article outlines the establishment of reactive ion etching protocols for fabrication of high aspect ratio trenches with minimum scalloping and undercut, employing the Bosch process. High aspect ratio submicron trench array patterns were transferred into silicon substrates using a Unaxis Versalock deep reactive ion etch tool equipped with a time multiplexed plasma etch/passivation cycle scheme which uses an inductively coupled plasma etcher. Through careful optimization of Bosch etch process conditions, successful etching of high aspect ratio ͑20:1͒ 170 nm trench features was achieved.

Conductive hafnium nitride films were deposited from a plasma-assisted atomic layer deposition ͑PA-ALD͒ process using a metallorganic hafnium precursor, tetrakis͑ethylmethylamino͒hafnium ͑TEMAH͒, using H 2 plasma as a reducing agent, at a substrate temperature of 250°C. The effects of radio frequency plasma pulse time and power on film resistivity, composition, and microstructure were investigated. The deposited films consisted of cubic HfN phase as shown by X-ray diffraction analysis, and the resistivity ranged from ϳ2300 to 8200 ⍀ cm depending on the plasma conditions. The most conductive films were observed to result from conditions of higher plasma power, which is attributed to microstructural modifications as well as a decrease in N:Hf ratio, which approached unity at the highest plasma powers employed. Carbon incorporation in the form of HfC x phase was shown to be beneficial in terms of improving both post-rapid-thermal-anneal stability and electrical conductivity. A midgap work function ͑4.63 eV͒ was obtained for a HfN x electrode structure integrated into a metal-oxide-semiconductor capacitor featuring a SiO 2 dielectric.

Eisenbraun, E.T.; Upham, A.; Dash, R.; Zeng, W.; Hoefnagels, J.P.M.; Lane, S.; Anjum, D.; Dovidenko, K.; Kaloyeros, A.E.; Arkles, B.; Sullivan, J.J.

A metallorganic chemical vapor deposition ͑MOCVD͒ process has been developed for the growth of Ta 2 O 5 films from the reaction of tantalum penta-ethoxide ͓Ta(OEt) 5 ͔ and oxygen in a 200 mm wafer tool platform. An optimized process was identified by performing a systematic study of the reaction-rate-limiting steps as a function of substrate temperature, Ta(OEt) 5 partial pressure, and O 2 partial pressure. Subsequent chemical and microstructural analyses showed that as-deposited Ta 2 O 5 films were stoichiometric, amorphous, pure, and exhibited a smooth surface morphology. Carbon contamination was below the detection limits of the analytical techniques employed ͑Ͻ1 atom %͒. Typical as-deposited film dielectric constant and leakage current density were measured to be 27 and 2.0 ϫ 10 Ϫ9 A/cm 2 ͑at 1 V͒, respectively. Annealing at 650°C for 30 min in O 2 decreased both the dielectric constant and leakage current, while a similar anneal in Ar resulted in increased dielectric constant and associated decrease in leakage current. It was determined that Schottky emission was the dominant leakage current conduction mechanism in the MOCVD Ta 2 O 5 films.

A low-temperature plasma-enhanced atomic layer deposition (PEALD) process has been developed for the growth of ultrathin WNxCy films, using a halide-free W precursor. A 32-nm-thick PEALD WNxCy film deposited using this process at 250 °C possesses a composition of W72C20N5, resistivity of ∼250 μΩ·cm, a root-mean-square (rms) surface roughness of 0.23 nm, and a thickness conformality of more than 80% on trench structures with a width of 120 nm and an aspect ratio of 11. The WNxCy films exhibited excellent thermal stability, whereby resistivity, thickness, surface roughness, and crystal structure were stable after 30 min anneals in 700 Torr, forming gas ambient at temperatures up to 700 °C. Copper diffusion barrier performance measurements show that a 9 nm thick WNxCy film could prevent copper diffusion after a 30 min anneal at 700 °C, while a 2-nm-thick film could prevent copper diffusion after a 30 min anneal at 500 °C.