Making silicon stronger.

Conference · Mon Nov 01 04:00:00 EDT 2010

OSTI ID:1035625

Boyce, Brad Lee

Silicon microfabrication has seen many decades of development, yet the structural reliability of microelectromechanical systems (MEMS) is far from optimized. The fracture strength of Si MEMS is limited by a combination of poor toughness and nanoscale etch-induced defects. A MEMS-based microtensile technique has been used to characterize the fracture strength distributions of both standard and custom microfabrication processes. Recent improvements permit 1000's of test replicates, revealing subtle but important deviations from the commonly assumed 2-parameter Weibull statistical model. Subsequent failure analysis through a combination of microscopy and numerical simulation reveals salient aspects of nanoscale flaw control. Grain boundaries, for example, suffer from preferential attack during etch-release thereby forming failure-critical grain-boundary grooves. We will discuss ongoing efforts to quantify the various factors that affect the strength of polycrystalline silicon, and how weakest-link theory can be used to make worst-case estimates for design.

• Research Organization: Sandia National Laboratories
• Sponsoring Organization: USDOE
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 1035625
• Report Number(s): SAND2010-8380C
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DEFECTS
DESIGN
FRACTURE PROPERTIES
GRAIN BOUNDARIES
MICROSCOPY
RELIABILITY
SILICON
SIMULATION
STATISTICAL MODELS