UNDOPED EPITAXIAL SI CHANNEL N-MOSFET GROWN BY UHV-CVD WITH PREHEATING

Undoped epitaxial channel n-MOSFET with high transconductance was deve loped, In order to obtain a good crystal quality of the epitaxial laye r and, thus, to achieve high performance, it is important to reduce th e oxygen concentration at the epitaxial Si/Si substrate interface, In this paper, we describe the relationship between the electrical charac teristics and the surface density of oxygen at the epitaxial Si/Si sub strate. We also describe the dependence of the electrical characterist ics on epitaxial Si thickness, The g(m) of n-MOSFET with 40-nm epitaxi al Si for 0.10-mu m gate length was 630 mS/mm at V-d - 1.5 V, and the drain current was 0.77 mA/mu m. This g(m) value in the case of the epi taxial Si channel is about 20% larger than that of bulk the MOSFET. Th ese results show that epitaxial Si channel MOSFET's are useful for fut ure high-speed ULSI devices.