Meson Interactions in NMOS and CMOS Static RAMs

Nuclear interactions of heavy particles, such as neutrons, protons, and heavy ions are one of the primary causes of errors in memory chips exposed to radiation in the environment. Pions, the quanta associated with the nuclear force, and muons are produced in large quantities in such reactions and can be responsible for a portion of those errors attributed to primary particles. Pions and muons also are important constituents of cosmic rays at lower elevations. The rate of error induction in 4K static RAMs from high-energy pion and muon beams has been measured at three energies and as a function of depth in plastic. Preliminary data for 16K NMOS and 64K CMOS static RAMs were also obtained. Only two errors were observed from muon beams incident upon 4K chips for 1.4 × 10
¹⁰
particles/cm
²
. In contrast, energetic pion beams produced errors in the same chips at the rate of typically 5 × 10
^-8
errors per incident particle per cm2 . In the pion beams the rate decreased slowly with decreasing energy until the particles approached the end of their range. In the stopping region, the error rate continued to decrease for positively charged pions but increased about a factor of seven for negatively charged pions. Monte Carlo programs have been run both to simulate the production of pions in the atmosphere as a function of elevation and to simulate the inteactions of pions in the 4K chip.