Direct-write, cryogenic electron beam-induced deposition (EBID) was performed by condensing methylcyclopentadienyl-platinum-trimethyl precursor onto a substrate at −155 °C, exposing the condensate by a 15 keV electron beam, and desorbing unexposed precursor molecules by heating the substrate to room temperature. Dependencies of film thickness, microstructure, and surface morphology on electron beam flux and fluence, and Monte Carlo simulations of electron interactions with the condensate are used to construct a model of cryogenic EBID that is contrasted to existing models of conventional, room temperature EBID. It is shown that material grown from a cryogenic condensate exhibits one of three distinct surface morphologies: a nanoporous mesh with a high surface-to-volume ratio; a smooth, continuous film analogous to material typically grown by room temperature EBID; or a film with a high degree of surface roughness, analogous to that of the cryogenic condensate. The surface morphology can be controlled reproducibly by the electron fluence used for exposure.

Soldering to Cu interconnect pads with Sn-containing alloys usually leads to the formation of a layered Cu3Sn/Cu6Sn5 structure on the pad/solder interface. Frequently, microscopic voids within Cu3Sn have been observed to develop during extended thermal aging. This phenomenon, commonly referred to as Kirkendall voiding, has been the subject of a number of studies and speculations but so far the root cause has remained unidentified. In the present work, 103 different Cu samples, consisting of 101 commercially electroplated Cu and two high-purity wrought Cu samples, were surveyed for voiding propensity. A high temperature anneal of the Cu samples before soldering was seen to significantly reduce the voiding level in subsequent thermal aging. For several void-prone Cu foils, the anneal led to significant pore formation inside the Cu. In the mean time, Cu grain growth in the void-prone foils showed impeded grain boundary mobility. Such behaviors suggested that the root cause for voiding is organic impurities incorporated in the Cu during electroplating, rather than the Kirkendall effect.

Ultrafast science—the study of highly complex and extremely short-lived transient events—has become an area of significant interest in the materials sciences, physics, chemistry, and biology. This article focuses on the state-of-the-art instrumentation and a few of the available probes and techniques, and intends to give a brief overview of the possibilities and challenges for ultrafast materials sciences and for the instrumentation that is required. The pulsed laser-material interactions are briefly introduced, since they are the principal methods to access and trigger ultrafast processes in materials. The associated time and length scales and a few experimental possibilities in the materials sciences are discussed in the first part of this article. The second part deals with the two most applicable types of pulsed probes, x-rays and electrons, and the associated methods to interrogate ultrafast processes. Emphasis is on their differences, capabilities, and limitations.

The impact of contact materials on the performance of nanostructured devices is expected to be significant. This is especially true since size scaling can increase the contact resistance and induce many unseen phenomenon and reactions that greatly impact device performance. Nanowire and nanoelectromechanical switches are two emerging nanoelectronic devices. Nanowires provide a unique opportunity to control the property of a material at an ultra-scaled dimension, whereas a nanoelectromechanical switch presents zero power consumption in its off state, as it is physically detached from the sensor anode. In this article, we specifically discuss contact material issues related to nanowire devices and nanoelectromechanical switches.

In this article, we review current research activities in contact material development for electronic and nanoelectronic devices. A fundamental issue in contact materials research is to understand and control interfacial reactions and phenomena that modify the expected device performance. These reactions have become more challenging and more difficult to control as new materials have been introduced and as device sizes have entered the deep nanoscale. To provide an overview of this field of inquiry, this issue of MRS Bulletin includes articles on gate and contact materials for Si-based devices, junction contact materials for Si-based devices, and contact materials for alternate channel substrates (Ge and III–V), nanodevices.