Fully-complementary BiCMOS on thin-film SOI utilizing high-performance lateral BJT's.

摘要

The first fully-complementary, deep-sub-micron BiCMOS technology using thin-film Silicon-on-Insulator (SOI) substrates is described. Fully-complementary, CBiCMOS technologies, which combine both PNP and NPN bipolar transistors with complementary MOSFET's, are especially important as gate lengths scale below 0.5{dollar}mu{dollar}m and power supplies are reduced below 3.3 volts. While CBiCMOS processes on bulk silicon are very complex, thin-film SOI substrates permit much simpler device integration. In addition, complementary BJT's are most easily integrated when their structure is lateral, instead of vertical. In this work, complementary, lateral BJT's and fully-overlapped LDD MOSFET's are fabricated on SOI with only ten masks. This process is substantially less complex than state-of-the-art BiCMOS processes.; Various means of achieving a thin-film SOI structure are investigated, including Separation by IMplanted OXygen (SIMOX), Bonded wafer with Etchback (BESOI), and Epitaxial Lateral Overgrowth (ELO). The crystalline quality of the silicon films is addressed with respect to the fabrication of minority-carrier, bipolar transistors.; Several potential SOI lateral bipolar transistor structures are analyzed in order to obtain the optimum structure for both high-performance and low-complexity. This lateral BJT structure is fully characterized to obtain both DC and AC performance characteristics.; Nearly-fully-depleted SOI MOSFET's with remarkable current drive and short channel behavior down to 0.15{dollar}mu{dollar}m are described. The threshold voltage control and series resistance of these partially-depleted devices are superior to ultra-thin-film, fully-depleted SOI MOSFET's. A novel isolation technique called ROSIE (Re-Oxidized Silicon Island Edges), is implemented and shown to be superior to LOCOS with regard to NMOS device edge behavior. NMOS and CMOS ring oscillators incorporating these SOI MOSFET's exhibit record propagation delays. In addition, various fully-complementary BiCMOS logic gates are investigated, in order to demonstrate the strength of this technology.; A novel "hybrid" mode of device operation is investigated, in which both lateral bipolar and MOSFET channel currents flow simultaneously. The g{dollar}sb{lcub}rm m{rcub}{dollar} and current drive in this mode of operation are significantly higher than either the MOSFET or lateral BJT alone. The turn-on voltage is reduced, permitting operation at supply voltages of less than one volt.; Finally, a new quasi-2-D analytical model for Gate-Induced Drain Leakage (GIDL) current in thin-oxide MOSFET's is developed. This off-state leakage current is particularly troublesome for deep-sub-micron SOI MOSFET's.