The sensitivity of thermal donor generation in silicon to self-interstitial sinks

Thermal donor (TD) generation in silicon at 500 degrees C was found to depe nd significantly on the cooling rate used after sequential annealing steps and on the nature of the ambient (air or vacuum). By performing the anneals initially under some specified cooling rate and ambient, and then changing to a new set of conditions, it was found that the: TD concentration relaxe d to the value corresponding to the new conditions. These results are well explained by a self-interstitial enhancement of TD generation rate. Self-in terstitials are emitted by TD clusters, and their concentration, C-i, depen ds on the efficiency of sinks (sample surface, bulk voids). For vacuum anne aling the major sink is the sample surface. For air anneals this sink is "p assivated" presumably due to oxidation of the surface and/or by surface con tamination, thus leaving only voids to act as self-interstitial sinks. Fast cooling seems to partly passivate voids (presumably by a decoration mechan ism), further decreasing the sink efficiency, and therefore increasing Ci a nd the TD generation rate. The quantitative theory of sink-controlled TD ge neration provides a good description of the complicated experimental kineti c curves. (C) 2000 The Electrochemical Society. S0013-4651(00)02-007-3. All rights reserved.