NIST writes first MEMS standards.

The first microelectromechanical systems (MEMS) standards in the world will be published in the Annual Book of ASTM Standards this summer. The three-standard test methods are for measuring in-plane lengths, residual strain, and strain gradient. Written by a NIST staff member, these test methods are based on the research and analyses detailed in NIST Interagency Report 6779. The residual strain and strain gradient standard calculations can be performed on the NIST Web site (www.eeel.nist.gov/812/test-structures/) to facilitate quick and easy calculations.

MEMS is a rapidly growing component of the semi-conductor industry. Applications for MEMS demand high performance and reliability. The standard test methods are crucial for tightening the variations in the parametric measurements between laboratories. These international standards are expected to facilitate international commerce in MEMS technologies and improve manufacturing yields.

All three test methods apply to thin films such as found in MEMS materials, which can be imaged using a non-contact optical interferometer. The first test method shows how to measure an in-plane length (or deflection) measurement, given that each end is defined by a distinctive out-of-plane vertical displacement. The second test method shows how to calculate the residual strain from two cosine functions that are used to model the out-of-plane shape of fixed-fixed beams. The third test method shows how to measure the strain gradient from a circular function that is used to model the out-of-plane shape of cantilevers.

The three test methods are under the jurisdiction of ASTM Committee E08 on Fatigue and Fracture and are the direct responsibility of Subcommittee E08.05 on Cyclic Deformation and Fatigue Crack Formation.

CONTACT: Janet Marshall, [phone]; janet. [e-mail].