Need for speed in semiconductors

A new type of standard to be issued by the National Institute of Standards and Technology (NIST) will help meet the need for speed in semiconductors.

The 'interactive reference material' is designed to help users calibrate instruments that determine the germanium fraction in silicon-germanium thin films, now used in the conducting channels of high-speed semiconductors for computers.

By measuring the composition of the standard material and comparing its results to NIST's values as part of the instrument calibration process, users can reduce measurement uncertainty and optimise thin-film compositions with the right amount of germanium.

Germanium causes strain in the silicon lattice, allowing electrons to move faster and thereby increasing device operating speed as much as twofold.

The new standard - which consists of sets of thin films of varying compositions - is among the first to be developed through interactions between industrial participants, who supply and characterise the materials and NIST staff who co-ordinate the process, conduct additional measurements and tests and assign values.

The process is less rigorous than the traditional Standard Reference Material (SRM) approach and may not result in certified values. But interactive materials can be made available relatively quickly, just 1 to 2 years after a need is identified, compared to about 5 years for a new SRM.

The need for the silicon-germanium standard was identified at an industry workshop 2 years ago. The uncertainty of compositional measurements currently is limited by available analytical tools to about 5%; the new standard has been measured with an uncertainty of about 1%.