THE INFLUENCE OF THE BURIED OXIDE DEFECTS ON THE GATE OXIDE RELIABILITY AND DRAIN LEAKAGE CURRENTS OF THE SILICON-ON-INSULATOR METAL-OXIDE-SEMICONDUCTOR FIELD-EFFECT TRANSISTORS

The relation between gale oxide and buried oxide (BOX) reliabilities w as investigated for several silicon on insulator (SOI) materials. The yield values of the gale oxide breakdown depend on the BOX leakage cur rents. The gate leakage currents and BOX leakage currents were observe d at the same position by optical luminescence. By scanning electron m icroscope (SEM) observation at the luminescence region in the low-dose separation by implanted oxygen (SIMOX) substrate, it was round that t he SOI layer had disappeared, and voids appeared in the BOX layer. In addition, Q(bd) of the gate oxide was low in the capacitor where the B OX leakage currents were observed. It is thought that the crystalline quality of the SOI layer on the imperfect BOX layer sas degraded, caus ing the gate leakage currents. Moreover, it was observed that the yiel d value of the drain leakage currents of the SOI metal-oxide-semicondu ctor field-effect transistors (MOSFET's) also depended on the BOX leak age currents.