An 0.28-mu m CMOS for mixed digital and analog applications with zero-volt-v(th) epitaxial-channel MOSFET's

An 0.18-mu m CMOS technology with multi-V-th's for mixed high-speed digital and RF-analog applications has been developed. The V-th's of MOSFET's for digital circuits are 0.4 V for NMOS and -0.4 V for PMOS, respectively. In a ddition, there are n-MOSFET's with zero-volt-V-th for RF analog circuits, T he zero-volt-V-th MOSFET's were made by using undoped epitaxial layer for t he channel regions, Though the epitaxial film was grown by reduced pressure chemical vapor deposition (RP-CVD) at 750 degrees C, the film quality is a s good as the bulk silicon because high pre-heating temperature (940 degree s C for 30 s) is used in H-2 atmosphere before the epitaxial growth. The ep itaxial channel MOSFET shows higher peak g(m) and f(T) values than those of bulk cases, Furthermore, the g(m) and f(T) values of the epitaxial channel MOSFET show significantly improved performances under the lower supply vol tage compared with those of bulk, This is very important for RF analog appl ication for low supply voltage, The undoped-epitaxial-channel MOSFET's with zero-V-th will become a key to realize high-performance and low-power CMOS devices for mixed digital and RF-analog applications.