A Silicon-on-Insulator Transistor Resistant to Substrate Potential

A silicon-on-insulator transistor that is resistant to substrate potential is demonstrated. The 0.18 μm independently double-gated Flexfet transistor with implanted JFET bottom gate shows little change in either threshold voltage or leakage current across a wide range of substrate potentials. Threshold voltage shifts (ΔVt) and changes in leakage current for both nMOS and pMOS transistors are analyzed for substrate biases ranging from -20 V to + 20 V. Results show no more than 20 mV and 10 mV ΔVt for the nMOS and pMOS transistors, respectively, and leakage currents that change less than 12 pA. The Flexfet transistors are therefore ideally suited for applications that require large potentials in the SOI substrates, such as CMOS SOI pixel detectors.