SrTiO3 (STO) is one of the key compounds in the emerging field of oxide electronics. Because of the low carrier concentration needed to turn it into the conducting state (10(18) e/cm(3)) and to its high bulk mobility (10(4) cm(2)/Vs @ 4.2 K), we consider STO suitable as functional conducting element in future oxide based devices. In this work we show how by applying a negative voltage to the conducting tip of an atomic force microscope it is possible to modify on sub-micron scale structural and electrical properties of conducting SrTiO3-delta thin films grown on insulating LaAlO3 substrates, thus realizing sub-micrometric STO electrical circuits. After discussing the mechanisms of the process, we present the fabrication of a SrTiO3-delta based side gate field effect transistor. (C) 2003 Elsevier Ltd. All rights reserved.