Complementary silicon MESFETs for VLSI

The dominant device used in modern VLSI circuits today is the MOS transistor. As technology has advanced several limitations of MOSFETs have become apparent: hot electron effects with their associated threshold voltage shifts, short channel effects, and also the practical technological problems of shrinking junctions and growing high integrity, low defect, thin gate oxides. MESFETs do not require thin gate oxides and hence are not susceptible to the problems of obtaining reliable thin gate oxides or to threshold voltage shifts due to hot carriers. Also, MESFETs are best suited to low voltage operation which is a common feature of most advanced VLSI technologies. In addition, MESFET devices have been shown to be quite radiation hard compared to other technologies. Finally, the MESFET can achieve bulk carrier mobility whereas MOSFETs are often restricted to less than half this value due to their surface conduction. The limited use of MESFETs for VLSI in the past has been due in part to their power requirements and limited variety of circuit configurations. The development of a complementary MESFET process not only reduces their power requirement and increases circuit flexibility, but also results in an improved speed performance thus improving their viability for VLSI applications.