Cosmic and Terrestrial Single-Event Effects in Dynamic Random Access

A review of the literature on single-event radiation effects (SEE) on MOS integrated-circuit dynamic random access memories (DRAM's) is presented. The sources of single-event (SE) radiation particles, causes of circuit informatidn loss, ex- perimental observations of SE information upset, technological developments for error mitigation, and relationships of develop- mental trends to SE vulnerability are discussed. I. INTRODUCTION HE first circuit error due to cosmic rays (space-borne, ionizing radiation particles) was observed in the bipolar flip-flop circuits of a space-borne communication system in 1975 (l). This discovery was followed in short order by an industry-shaking observation of errors due to ionizing particles in ground-bused systems-the culpable electronic circuit in this case was a metal-oxide-semiconductor (MOS) dynamic random access memory (DRAM). In 1978, May and Woods (2) experimentally observed soft (correctable) errors in 4-k DRAM's due to single alpha particles passing through the silicon substrate-single events. Later that same year, Pickel and Blandford reported cosmic-ray-induced single-event up- sets (SEU) in space-borne DRAM's (3). Since these early reports, the so-called single-event effects (SEE)--circuit re- sponses to impinging single, high-energy, particles of ionizing radiation-have generated a plethora of debate, study, analysis, and modeling. Concern over these radiation effects, and the vulnerability of electronic circuits to both space and terrestrial varieties of these particles, has driven two decades of research and technological advances. While the MOS DRAM has, historically, been an important circuit class for the study of single-event effects, the acute susceptibility of these circuits to radiation has influenced two major technological trends. First is the development of more complex sister circuits, i.e., static random access memories (SRAM's) and radiation-hardened SRAM's, for specialized tasks requiring radiation tolerance; these tasks include both military hi-re1 and space applications. High-re1 users have, historically, passed over DRAM'S in preference to radiation- hardened and noise-tolerant SRAM technologies (4)-(6)-a trend that may be changing-leading to limited research in the effects of cosmic radiation on these parts. Second, because DRAM's are so SEU vulnerable as to be susceptible to even the relatively benign and attenuated environment of the desk top, as well as the natural radiation-decay emissions from