Vapour phase co‐deposition of Al—Cu thin film alloys

Abstract

The fabrication and characterisation of Al-Cu thin film alloys obtained using co-deposition geometry from individual Al and Cu sources were addressed. A compositional gradient ranging from 36 to 93 at.% Cu was obtained. The surface microstructure evolved with a strong influence on the Cu content. This was connected to the presence of the Cu(111) in the alloys. The electrical resistivity showed a decrease by almost one order of magnitude in the Cu rich region of the Al-Cu combinatorial library. Al-Cu thin films evaporated from a single source produced a surface compositional gradient of 7 at.%. X-ray photoelectron spectroscopy (XPS) depth profiling revealed an in-depth compositional gradient as well. This behaviour was attributed to the gas phase dynamics of Al and Cu during the thin film formation.

Copper-nickel combinatorial library screening for electrocatalytic formaldehyde oxidation

“…show an inflection point at Ni concentrations around 5 at.%. This value correlates well with the composition where the pure Cu phase is completely eradicated by increasing Ni amounts, as previously reported . The sudden decrease of the (111) peak intensity after 5 at.% Ni (inflection point) sustains the previous hypothesis regarding the disturbance effect of Ni.…”

“…Their mid‐range position is shifted by more than 10 mm as compared to the geometrical centre of the substrate. This is commonly encountered when dealing with thermal evaporation sources and the main disadvantage is usually represented by a localised too steep compositional variation. Depending on the used technique, this localisation may render impossible a fine compositional scan during screening of a particular property.…”

Customized 2D Structures for High Throughput Electromigration Measurements

“…Similar to the case of void evolution, some Al grains overgrow due to the extra atomic flux during the surface migration. Grains reaching 300 nm may be observable apparently forming a superimposed layer on the usual Al surface having 20–30 nm grains .…”

“…Such behavior was reproducibly observed on Cu lines and it can be attributed to a partial delamination of the metal from the thermally insulating substrate due to poor Cu adhesion on glass. [19] As a result the free Cu surface increases allowing an enhanced natural cooling before the exponential temperature increase that finally leads to line failure above 500 K.…”

“…Due to the notoriously poor quality of Al thin films by sputtering, in this study Al films were deposited on glass substrates by thermal evaporation. This was achieved by using a self-developed vacuum system with three sources and a base pressure of 10 À5 Pa. [19] High purity Al (99.995%, Alfa Aesar) was loaded into three independent tungsten evaporation boats, each monitored by a quartz crystal microbalance (QCM À Inficon). Using a deposition distance of 120 mm, Al thin films were deposited on the substrates simultaneously from all three sources.…”