We introduce 0.18 μm CMOS with multi-Vth's for mixed high-speed digital and RF-analog applications. The Vth's of MOSFETs for digital circuits are 0.4 V for NMOS and -0.4 V for PMOS, respectively. In addition, there are n-MOSFETs with zero-volt-Vth for RF analog circuits. The zero-volt-Vth MOSFETs were made by using undoped epitaxial layer for the channel regions. Though the epitaxial film was grown by reduced pressure chemical vapor deposition (RP-CVD), the film quality is good because higher pre-heating temperature (940 °C for 30 seconds) is used in H2 atmosphere before epitaxial growth. The epitaxial channel MOSFET shows higher peak gm and fT than those of bulk cases. Furthermore, the gm and fT values show significantly improved performances under the low supply voltage, which is important for 0.18 μm CMOS with low power/low supply voltage operation. Additionally, in our experiment no significant difference was observed between the reliability of gate oxide grown on bulk and the reliability of that grown on epitaxial layers. The undoped-epitaxial-channel MOSFETs with zero-Vth will be effective to realize high performance and low power CMOS devices for mixed digital and RF-analog applications.
|Number of pages||4|
|Journal||Technical Digest - International Electron Devices Meeting, IEDM|
|State||Published - 1997|
|Event||1997 International Electron Devices Meeting - Washington, DC, USA|
Duration: 7 Dec 1997 → 10 Dec 1997