Kai-Erik Elers

Diffusion Barrier Deposition on a Copper Surface by Atomic Layer Deposition

Diffusion barrier materials, TiN and WN, were deposited by atomic layer deposition (ALD). The chlorine concentration of the TiN film was as low as 1.2 at.-%, and resistivity was below 200 μΩ cm. Ultra high aspect ratio (AR=85) trenches were used to assess step coverage. Tungsten nitride film, deposited from WF 6 and ammonia, was found to have high resistivity, although the residue content was low. The barrier deposition compatibility was studied using the copper surface exposed on the bottom of vias in the copper dual-damascene structure. The deposition on copper of both TiN and WN was found to be very challenging.

Reduction of Copper Oxide Film to Elemental Copper

The reduction of copper oxide film was studied as a process step in the manufacturing of elemental copper film via copper oxide film. Alcohols, carboxylic acids, and aldehydes were tested as reducing agents. The copper oxide film was exposed to reducing agents below 400°C using nitrogen as a carrier gas. The reduction efficiency was studied by characterizing the oxide residues with ion beam analysis and measuring the electrical resistance of the films. Thermodynamic calculations were compared with the observations. Most of the reducing agents performed well and copper oxide film as thick as 300-400 nm was completely reduced to elemental copper.

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.

Physical and electrical characterization of ALCVD TM TiN and WN x C y used as a copper diffusion barrier in dual damascene backend structures(08.2)

The application of copper diffusion barrier films deposited by atomic layer deposition (ALD, ALCVD™) on functional multilevel, dual damascene structures is in its infancy. In this study, two different ALD barrier films (TiN and WNC) were evaluated to determine how they affected the electrical properties of two-metal layer, dual damascene copper structures built in SiO2. In addition, bulk properties of each film were evaluated. It was found that ALD films show feasibility of functioning electrically in fully integrated interconnect structures as well as acting as a copper diffusion barrier and copper adhesion layer.

Atomic Layer CVD for Continuously Shrinking Devices

This paper will review the basics of the atomic layer chemical vapor deposition (ALCVD) thin film growth technique. The emphasis is on the ALCVD metal nitride growth and dual damascene barrier requirements.