COMPLEMENTARY MOS FIELD-EFFECT TRANSISTORS ON HIGH-RESISTIVITY SILICON SUBSTRATES

p-Channel enhancement mode MOS field-effect transistors have been fabricated on high-resistivity p-type (π) silicon substrates. A high off-state impedance can be achieved with zero gate voltage if the substrate resistivity is sufficiently high so that the p+π low-high junctions formed by the diffusion of the drain and source regions exhibit the desired rectifying characteristics. n-channel MOSFETs can also be fabricated on these high-resistivity π substrates. While the n-channel devices usually exhibit depletion mode characteristics, both n- and p-channel enhancement type MOSFETs can be simultaneously fabricated on a single substrate if Al2O3-SiO2 gate insulating layers are used and if QSS is kept sufficiently small. Selective gold-doping techniques can also be employed to achieve enhancement-type characteristics for both n- and p-channel devices. The channel lengths must be sufficiently large to eliminate SCL current flow from drain to source with zero gate voltage. By using techniques such as beam-lead interconnections or dielectric isolation, complementary MOS integrated circuits can be fabricated on a single substrate and only two diffusions are required. Additional advantages of this approach include extremely high carrier mobilities, very low threshold voltages for both units, and negligible variation of MOSFET characteristics with reverse substrate bias. © 1969.