An investigation was carried out into the chemical breakdown of the anodic oxides grown on p- and n-doped (100) orientated silicon in tetramethylammonium hydroxide (TMAH) solutions. The anodic oxides were grown by sweeping the potential anodic of the passivation potential (PP) and into the passive region. The effect of various parameters on the chemical breakdown of the anodic oxide was studied. In particular, an extensive study on the influence of temperature, concentration and carrier type on the breakdown of the anodic oxide was carried out, with the effect of sweep rate studied to a lesser extent. The oxide breakdown time (OBT) was found to decrease with increasing temperature for all concentrations investigated. The OBT was found to increase with increasing concentration at lower temperatures with the concentration not having a major effect on the breakdown at higher temperatures. The OBT was consistently found to be greater for those anodic oxides grown on p-type (100) Si with the values for the two carrier types converging at higher temperatures. The OBT also decreased when grown at higher sweep rates. It is shown that a number of factors are involved in the explanation of the effect of temperature and concentration on the breakdown time of the anodic oxides. (C) 2003 Elsevier Science Ltd. All rights reserved.