ITRS Adds Emerging Tech Materials

The Emerging Research Devices (ERD) chapter of the International Technology Roadmap for Semiconductors (ITRS) aims to gather in one place "substantive, alternative concepts for memory, logic and information processing architectures that would, if successful, substantially extend the roadmap beyond CMOS." Examples of ERDs range from evolutionary devices, such as transport-enhanced FETs made possible by strained silicon, to novel devices, such as spin transistors and resonant tunneling devices. The recently updated version of the ITRS, released in December, includes a new section focused on the material aspect of emerging research.

The scope of emerging research materials (ERM) is to identify material properties, synthesis techniques and metrology required for ERDs. Since many of the evolutionary and some of the revolutionary ERDs can be fabricated with conventional materials and process technology that are already covered in other sections of the ITRS, the ERM section does not cover these materials and processes.

The most difficult challenges for ERM, according to the 2004 ITRS, is to characterize the material properties that will enable device operation at the nanometer scale. To improve material quality, metrology and characterization techniques are required that can identify defects, impurities and interfaces that will limit the ability of these materials to function properly. Modeling and simulation may be needed to analyze the experimental results, but several critical phenomena are not accurately modeled. Significant improvements must be made for them to be effective at the nanometer scale. These challenges are summarized in the Table .

The new ITRS notes that the fabrication of many of the new materials for ERDs may require new chemicals, synthesis techniques, and metrology to characterize and improve their performance: Successful evaluation of the ERD will require materials that have bulk and interface material properties that are optimized for device operation, and this will require characterization and modeling to identify the material properties that must be changed or improved. The synthesis of new chemicals for use in molecular devices will require increased understanding of the switching mechanisms, contact formation and transport mechanisms.

Similarly, fabrication of nano-structured materials, such as nanotubes or nanowires, for devices will require improved control and understanding of the impact of process on the structure, the resulting electronic properties and interface properties. The synthesis of materials for application in spin devices may require control of isotopic purity, impurity levels, spin relaxation and interface spin transmission and spin decoherence mechanisms. If self-assembly mechanisms are to be useful to fabricate high-density device materials, the synthesis mechanism must be capable of reproducibly constructing materials into desired patterns at a higher density than can be achieved with lithography. These challenges will require new metrology to characterize the resulting structure and critical materials and interface properties at the nanometer scale. In addition, modeling and simulation will be needed to analyze and identify chemical and structural changes to improve material properties and the resulting device operation.

Included in the 2004 ITRS are sections on ERM synthesis and characterization, as well as simulation and modeling.