First direct beta measurement for parasitic lateral bipolar transistors in fully-depleted SOI MOSFET´s

Summary form only given. Direct measurements of β values in SOI (silicon-on-insulator) MOSFETs biased in normal operating regimes are presented. The measurements were made on an SOI structure that allows for the efficient collection of the hole current after it has entered the source region and caused the bipolar back-injection of electrons. By measuring the drain and substrate currents and making extrapolated estimates of the intrinsic MOS channel current, it is possible to calculate values of the gain of the parasitic bipolar device for any bias condition. The V_GS=V_T case is of greatest interest, because the drain-to-source breakdown voltage is generally smallest for this value of gate potential. β was found to be highly dependent on the value of V _D, with β falling dramatically with increasing V_D. As V_D is increased from 2.5 V to 4.5 V, with V_GS-V_T held at 0 V, β falls from about 1000 to 20 for an L=1.3 μm, T_SOI=1000 Å device