Metrology in the Nanoelectronics Era

Moving more and more into the nanoscale regime can help reduce the cost per function and increase the performance of ICs, but designing and building these new devices and structures will require new materials, manufacturing paradigms, and metrology. Radical, innovative approaches should be adopted as to how we invent, develop and use metrology tools in the future. Industry collaboration with the National Institute of Standards and Technology (NIST) is becoming more important than ever to address these challenges.

NIST is currently carrying out an economic impact study to assess the net benefits of the following technical infrastructure on the U.S. semiconductor industry: product design tools, quality/reliability of data assessment techniques, interoperability of measurement data among databases and equipment, production equipment calibration, in situ/ex situ process control techniques, and quality assurance techniques. The focus will be on metrology developments that have occurred over the past decade, and the expected completion date is Spring 2007.

A new Center for Nanoscale Science and Technology is designed to provide essential measurement methods, instrumentation and standards to support all phases of nanotechnology development from discovery to production. This state-of-the-art facility will help NIST and industry researchers resolve many of the challenges associated with nanoscale science and engineering at the atomic and molecular level.

At a biennial meeting, “Frontiers of Characterization and Metrology for Nanoelectronics ,” top researchers from the industry, universities and government gather to help solve new metrology challenges as we move into the nanoscale regime. As Tom Friedman says in The World is Flat, the emerging era will be “characterized by the collaborative innovation of many people working in gifted communities, just as innovation in the industrial era was characterized by individual genius.”

The next “Frontiers” conference will be held March 27-29, 2007, in Gaithersburg, Md.

Frontiers in reliability

Aggressive scaling by introducing new materials and device structures, more efficient and reliable processing techniques, functional design methods, and patterning have propelled the semiconductor industry into the extreme CMOS and nanoelectronics era. However, a trade-off has developed between the device performance/scalability and its reliability. The emerging new materials systems involving high-k, low-k and metal gates have introduced us to new failure mechanisms. We need a better fundamental understanding of these new failure mechanisms and their kinetics. Innovative ideas are critically needed in metrology to help continue these advances.

Characterization and modeling are critical factors in predicting the life of a device or product. The correct physics to interpret the results of accelerated stress tests are also needed. There are major areas in reliability that need to be addressed now: dielectrics (high-k, SiO_x), interconnects (low-k, copper), transistors (NBTI, hot carrier, PBTI), ESD/latch up, soft error rate, MEMS, compounds/wide bandgap materials, and failure analysis.

As scaling reaches its fundamental ultimate limits, new paradigms are needed for investigating fundamental reliability mechanisms and developing new standards that can be effectively used by industry.

Future challenges include:

1. Improved device models are needed to better understand current transport and the effects of defects and traps on nanoscale devices. For example, random telegraph signals (RTSs) will become very important because they can upset the drain current of a nanoscale device by as much as tens of a percent due to one trap state.
2. Electrical characterization and atomic imaging of interfaces becomes more critical. Nanoscale devices will be comprised primarily of interfaces between different materials where more defects exist. Also, individual atoms become a larger fraction of nanoscale devices, and any changes in those atoms or bonding arrangement become more important for reliability.
3. The need for standards grows as reliability characterization becomes more difficult with nanoscale devices and chip manufacturers use more off-shore foundries for fabrication and assembly. NIST is playing a major role in the national standards committees to develop these new device reliability characterization standards.