MOS-bipolar monolithic integrated circuit technology

A technique for the fabrication of p-channel MOS transistors and bipolar transistors within monolithic integrated circuits is described. Total process compatibility has been achieved without compromising either the n-p-n bipolar or p-channel MOS characteristics. The technology developed is similar to that used for conventional integrated circuits until the channel oxidation step, A low temperature oxidation followed by a high temperature anneal process that produces negligible changes in preceding diffusion profiles was used to form this oxide. Bias temperature tests of MOS capacitors have shown the oxide to be reproducibly free of contamination. A high slew rate MOS bipolar operational amplifier has been designed and fabricated on 0.045- by 0.045-in chip using the new technology. Typical characteristics are slew rate =80 V/µs voltage gain = 70 dB. The MOS transistors are used as active loads and level shifters in this circuit and provide a much improved frequency response over conventional circuits using p-n-p lateral transistors.