SINGLE EVENT UPSET

 SINGLE  EVENT  UPSET 

INTRODUCTION :

A single - event upset ( SEU ) , also known as a single - event error ( SEE ) , is a change of state caused by one single ionizing particle ( ions , electrons , photons... ) striking a sensitive node in a micro - electronic device , such as in a microprocessor , semiconductor memory , or power transistors . The state change is a result of the free charge created by ionization in or close to an important node of a logic element ( e.g. memory " bit " ) . The error in device output or operation caused as a result of the strike is called an SEU or a soft error .

The SEU itself is not considered permanently damaging to the transistor's or circuit's functionality unlike the case of single - event latch - up ( SEL ) , single - event gate rupture ( SEGR ) , or single - event burnout ( SEB ) . These are all examples of a general class of radiation effects in electronic devices called single - event effects ( SEEs ) .

HISTORY :

Single - event upsets were first described during above - ground nuclear testing , from 1954 to 1957, when many anomalies were observed in electronic monitoring equipment . Further problems were observed in space electronics during the 1960s , although it was difficult to separate soft failures from other forms of interference . In 1972 , a Hughes satellite experienced an upset where the communication with the satellite was lost for 96 seconds and then recaptured . Scientists Dr. Edward C. Smith , Al Holman , and Dr. Dan Binder explained the anomaly as a single - event upset ( SEU ) and published the first SEU paper in the IEEE Transactions on Nuclear Science journal in 1975 . In 1978 , the first evidence of soft errors from alpha particles in packaging materials was described by Timothy C. May and M.H. Woods . In 1979 , James Ziegler of IBM , along with W. Lanford of Yale , first described the mechanism whereby a sea - level cosmic rays could cause a single event upset in electronics . 1979 also saw the world’s first heavy ion “ single event effects ” test at a particle accelerator facility , conducted at Lawrence Berkeley National Laboratory's 88 - inch Cyclotron and Bevatron .

CAUSE :

Terrestrial SEU arise due to cosmic particles colliding with atoms in the atmosphere , creating cascades or showers of neutrons and protons , which in turn may interact with electronic circuits . At deep sub - micron geometries , this affects semiconductor devices in the atmosphere .
In space , high - energy ionizing particles exist as part of the natural background , referred to as galactic cosmic rays ( GCR ) . Solar particle events and high - energy protons trapped in the Earth's magnetosphere ( Van Allen Radiation Belts ) exacerbate this problem . The high energies associated with the phenomenon in the space particle environment generally render increased spacecraft shielding useless in terms of eliminating SEU and catastrophic single -event phenomena ( e.g. destructive latch - up ) . Secondary atmospheric neutrons generated by cosmic rays can also have sufficiently high energy for producing SEUs in electronics on aircraft flights over the poles or at high altitude . Trace amounts of radioactive elements in chip packages also lead to SEUs .

Written By - Ritesh Pandita  ©