James L. Walsh

Field testing for cosmic ray soft errors in semiconductor memories

This paper presents a review of experiments performed by IBM to investigate the causes of soft errors in semiconductor memory chips under field test conditions. The effects of alpha-particles and cosmic rays are separated by comparing multiple measurements of the soft-error rate (SER) of samples of memory chips deep underground and at various altitudes above the earth. The results of case studies on four different memory chips show that cosmic rays are an important source of the ionizing radiation that causes soft errors. The results of field testing are used to confirm the accuracy of the modeling and the accelerated testing of chips.

A symmetrical-transistor steering circuit

1. The greatest advantage of the circuit as fas as binary triggering is concerned seems to be that simultaneous triggering at both bases can be used. This reduces the regeneration time in the flip-flop. 2. The circuit is quite sensitive to changes in input level. This can be overcome by application of a bias at the input which is greater that the anticipated noise level. 3. The symmetrical circuit finds application wherever flip-flops are used, including rings, counters and shifting registers.