Title :
The influence of fluorine on threshold voltage instabilities in p/sup +/ polysilicon gated p-channel MOSFETs
Author :
Baker, F.K. ; Pfiester, J.R. ; Mele, T.C. ; Tseng, H.-H. ; Tobin, P.J. ; Hayden, J.D. ; Gunderson, C.D. ; Parrillo, L.C.
Author_Institution :
Motorola Inc., Austin, TX, USA
Abstract :
It is shown that fluorine plays a major role in the penetration of boron into and through the gate oxides of p-channel MOSFETs that use p/sup +/ doped polysilicon gates. Boron penetration results in large positive shifts in V/sub FB/, increased p-channel subthreshold slope and electron trapping rate, and decreased low-field mobility and interface trap density. Inclusion of a phosphorus coimplant or TiSi/sub 2/ salicide is shown to minimize this effect. The boron penetration phenomenon is modeled by the creation of a very shallow, fully depleted p-type layer in the silicon substrate close to the SiO/sub 2/-Si interface. Elemental boron is shown to be superior to BF/sub 2/ as an implant species for surface channel submicron PMOS devices.<>
Keywords :
boron; carrier mobility; electron traps; elemental semiconductors; fluorine; insulated gate field effect transistors; interface electron states; ion implantation; phosphorus; silicon; LOCOS; MOSFETs; Si; Si:BF/sub 2/,P; SiO/sub 2/-Si:B; TiSi/sub 2/ salicide; boron penetration phenomenon; electron trapping rate; interface trap density; low-field mobility; p-channel; p-type layer; polysilicon; positive shifts; substrate; subthreshold slope; surface channel submicron PMOS devices; threshold voltage instabilities; Annealing; Boron; Capacitance-voltage characteristics; Channel bank filters; Electron traps; Hydrogen; Implants; MOSFETs; Temperature; Threshold voltage;
Conference_Titel :
Electron Devices Meeting, 1989. IEDM '89. Technical Digest., International
Conference_Location :
Washington, DC, USA
Print_ISBN :
0-7803-0817-4
DOI :
10.1109/IEDM.1989.74317
