Title :
Fluorine effect on boron diffusion of p/sup +/ gate devices (MOSFETs)
Author :
Sung, J.M. ; Lu, C.Y. ; Chen, M.L. ; Hillenius, S.J. ; Lindenberger, W.S. ; Manchanda, L. ; Smith, T.E. ; Wang, S.J.
Author_Institution :
AT&T Bell Lab., Allentown, PA, USA
Abstract :
A device characteristics instability in MOSFETs associated with fluorine incorporation in the p/sup +/-gate fabrication is reported. MOSFETs with BF/sub 2/ or boron-implanted polysilicon gates are fabricated identically except at gate implantation. A substantial shift and fluctuation in the threshold voltages of MOSFETs with BF/sub 2/-implanted gates are observed, even under moderate annealing conditions, while the boron-implanted gate devices still exhibits normal characteristics. The threshold voltage is found to shift more positively, and the subthreshold swing shifted to a large value as the fluorine concentration increased in the gate. The physical causes accounting for the threshold voltage shift are identified to be the fluorine-enhanced boron penetration and/or negative charge generation.<>
Keywords :
boron; boron compounds; diffusion in solids; elemental semiconductors; insulated gate field effect transistors; ion implantation; silicon; MOSFETs; SiO/sub 2/-Si:B; SiO/sub 2/-Si:BF/sub 2/; device characteristics instability; fluorine incorporation; gate implantation; moderate annealing conditions; negative charge generation; p/sup +/-gate fabrication; subthreshold swing; threshold voltage; threshold voltage shift; Annealing; Boron; CMOS technology; Fabrication; Fluctuations; Furnaces; Hydrogen; MOSFETs; Temperature sensors; 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.1989.74318
