Research on contact materials in silicon semiconductor devices has recently gained significant momentum due to the increasing performance demands as the complementary metal oxide semiconductor technology advances. Applications include transistor materials such as gate electrodes and contacts to highly doped semiconductors substrates. This review will discuss the key issues in the development of metal gate electrodes with high-κ dielectrics to replace the conventional polycrystalline silicon electrode. Challenges in establishing a work function measurement technique, the role of the metal/high-κ interface in modulating the effective work function, and a review of leading industry solutions will be discussed.

A novel contact technique to reduce the effective Schottky barrier height on Ge and III–V high mobility semiconductors is described. Single metals are used in combination with an ultrathin dielectric to tune the metal/semiconductor barrier height toward zero by shifting or suppressing the strong Fermi-level pinning. Barrier height reduction in the metal-insulator-semiconductor (MIS) contact structure is verified through direct measurements and deduced from increased diode current and reduced contact resistance. Current demonstrations of the MIS contact have barriers as low as 0.05 eV for Er/SiN/n-Ge and 0.18 eV for Al/Al2O3/n-GaAs. The underlying physics is discussed along with the dependence of the minimum achievable contact resistance and barrier height on the metal, dielectric material, dielectric thickness, and substrate doping. For Ge, the MIS contact provides a possible solution to the low n-type Ge dopant solubility problem and allows for the fabrication of Schottky barrier field-effect transistors. For III–V semiconductors, the MIS contact allows for the use of a non-alloyed contact that is crucial for the scalability of III–V metal oxide semiconductor field-effect transistors.

Effective schemes to address contact resistance between silicide and a highly doped diffused junction are examined. Some of the techniques introduced include (1) metal work function tuning, (2) interfacial dipole engineering, and (3) phase modulation of the nickel silicide. These techniques allow modulation of the Schottky barrier of NiSi to n-Si to less than 0.3 eV, which is crucial to achieve sub 10−8 Ω cm2 contact resistivity for the sub-32 nm technology node.

This paper provides an overview of directed self-assembly (DSA) options that exhibit potential for enabling extensible high-volume patterning of nanoelectronics devices. It describes the current set of research requirements, which a DSA technology must satisfy to warrant insertion consideration, and summarizes the state-of-the art. The primary focus is on chemical patterning and graphoepitaxial approaches to directing block copolymer (BCP) based assembly. These options exhibit the nearest-term potential, among the emerging DSA technologies, for satisfying projected International Technology Roadmap for Semiconductors (ITRS) patterning requirements. The paper concludes with a selected set of additional challenges, which represent potential barriers to the integration of directed BCP patterning into a nanoelectronics manufacturing line, as well as a few emerging application opportunities for related functional materials. A glossary of acronyms and terms may be found at the end of this manuscript.

Controlled bottom-up assembly of nanocylinders (e.g., nanotubes, nanorods, nanowires) into large area aligned arrays is widely recognized as a key obstacle impeding application development. Processing of lyotropic liquid crystal phases is a promising route for overcoming this obstacle, but nanocylinder liquid crystalline science is a nascent field that tends to be fractionated based on material type. This review explores the common challenges and achievements of nanocylinder liquid crystal research by focusing on three types of systems: (i) carbon nanotubes, (ii) inorganic nanocylinders, and (iii) cellulose nanocrystals.

Five lipids were self-assembled in aqueous dispersions into high axial ratio nanostructures. Thermal analysis was conducted on a glycolipid self-assembled into nanotubes, previously developed by Kamiya et al. [S. Kamiya, H. Minamikawa, J-H. Jung, B. Yang, M. Masuda, and T. Shimizu, Langmuir 21, 743 (2005)], showing a dry melting onset of 148.2 °C and evidence of a highly ordered supramolecular structure. A novel hybrid structure of the glycolipid nanotubes decorated with silver nanoparticles was created. The self-assembly of four new amphiphiles, with serine and glutamic acid head groups attached to vaccenic acid and diacetylenic hydrophobic tails, was also investigated. The morphologies of these aggregates included high axial ratio nanostructures, such as nanotubes; and flat, twisted, and helical ribbons. The supramolecular aggregates of the five lipids reflect aspects of the molecular structure, such as chirality, providing evidence that such organized aggregates can be created by a rational approach to molecular design.