Effects of device aging on microelectronics radiation response and reliability

We review recent work that shows that, for several kinds of devices built by several different manufacturers, MOS and bipolar device radiation response can change significantly with pre-irradiation elevated temperature stress and/or with aging time after device fabrication or packaging. The primary effects that have been observed are related to changes in interface-trap charge buildup, but some effects are also noted for charge trapped in the oxide. On the basis of a wide array of experimental data and first-principles calculations, these changes are attributed to the motion and reactions of hydrogenous species, e.g., protons and water. Similar reactions with hydrogen can also affect the reliability of MOS devices and integrated circuits, as illustrated here for the case of negative bias-temperature instability for high-kappa alternative gate dielectrics. Heating the device accelerates some kinds of aging effects, but reverses the effects of others. These observations are consistent with a dual role for hydrogen in improving or degrading device performance, depending on its particular incorporation in the device and subsequent motion and reactions. These results emphasize that measurements used to provide estimates of MOS radiation response and long-term reliability can vary significantly with time. In some cases, typical margins built into radiation response and reliability tests may be inadequate to account for aging-related changes in device performance. (C) 2006 Elsevier Ltd. All rights reserved.