Mechanisms for Fatigue of Micron-Scale Silicon StructuralFilms
Although bulk silicon is not susceptible to fatigue,micron-scale silicon is. Several mechanisms have been proposed to explainthis surprising behavior although the issue remains contentious. Here wedescribe published fatigue results for micron-scale thin siliconfilms andfind that in general they display similar trends, in that lower cyclicstresses result in larger number of cycles to failure in stress-lifetimedata. We further show that one of two classes of mechanisms is invariablyproposed to explain the phenomenon. The first class attributes fatigue toa surface effect caused by subcritical (stable) cracking in thesilicon-oxide layer, e.g., reaction-layer fatigue; the second classproposes that subcritical cracking in the silicon itself is the cause offatigue in Si films. It is our contention that results to date fromsingle and poly crystalline silicon fatigue studies provide no convincingexperimentalevidence to support subcritical cracking in the silicon.Conversely, the reaction-layer mechanism is consistent with existingexperimental results, and moreover provides a rational explanation forthe marked difference in fatigue behavior of bulk and micron-scalesilicon.
- Research Organization:
- Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE Director. Office of Science. Office of AdvancedScientific Computing Research. Office of Basic Energy Sciences. MaterialsScience and Engineering Division
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 901525
- Report Number(s):
- LBNL--61886; BnR: KC0201020
- Journal Information:
- Advanced Engineering Materials, Journal Name: Advanced Engineering Materials Journal Issue: 1-2 Vol. 9; ISSN 1438-1656; ISSN AENMFY
- Country of Publication:
- United States
- Language:
- English
Similar Records
Mechanisms for fatigue and wear of polysilicon structural thinfilms
Fatigue of polycrystalline silicon for MEMS applications: Crack growth and stability under resonant loading conditions