New Type of Fatigue Discovered in Silicon

Invisible Pink Unicorn writes "Researchers at the National Institute of Standards and Technology (NIST) have discovered a phenomenon long thought not to exist. They have demonstrated a mechanical fatigue process that eventually leads to cracks and breakdown in bulk silicon crystals. Silicon — the backbone of the semiconductor industry — has long been believed to be immune to fatigue from cyclic stresses because of the nature of its crystal structure and chemical bonds. However, NIST examination of the silicon used in microscopic systems that incorporate tiny gears, vibrating reeds and other mechanical features reveals stress-induced cracks that can lead to failure. This has important implications for the design of new silicon-based micro-electromechanical system (MEMS) devices that have been proposed for a wide variety of uses. The article abstract is available from Applied Physics Letters."

DLP TV/Projectors, the first consumer victim?

[Radon360]

Are TI's DLP mirror arrays subject to this? Don't know for sure if DLP is presently the largest MEMS rollout (if it is considered a MEMS) to the consumer market right now, but I wonder if anyone has reported mirror failures after a number of longer operating hours?

Just curious.

Re:oh well... a more expensive alternative

[SEE]

Diamond is metastable. Graphite is forever.

I'm tired

[Anonymous Coward]

I wonder where they would get the idea that silicon wouldn't fatigue? Silicon exhibits both electrostriction and magnetostriction, and hence the lattice undergoes strains with changes in electric or magnetic field (as appropriate). Ideally these chips either have no dislocations or maybe just a single screw dislocation. Or rather, the substrate would be that way. But all of the gates and switches and what not will have interfacial dislocations. It would be unusual if dislocation multiplication couldn't take place under micro-plastic flow near these interfaces.

Re:Commodity

[Anonymous Coward]

My first thought was circuit boards in avionics. Surely all those cycles -- nevermind exposure to extreme cold -- are going to put mechanical stresses on boards, which is kinda scary when you consider the level of computer-control in modern airplanes.

Re:Is it just me?

[Auraiken]

I was actually starting to think that maybe "tiny gears" and "vibrating reeds" might be defective by design. Maybe the forms themselves cannot take the stresses very well and lead to fatigue. Is there any research for finding stresses in single forms? like break/crack points between edges and whatnot depending on how they are shaped and how much force is put on them relative to the rest of the structure? or is it 4:30am and i should've went to bed hours ago?