Title :
The effect of substrate resistivity on threshold voltage shifts due to radiation-induced damage in IGFET
Author :
Savio, A.D. ; Bhattacharya, P.K. ; Kousik, G.S. ; Nandakumar, R.P.
Author_Institution :
Dept. of Electr. & Comput. Eng., Louisiana State Univ., Baton Rouge, LA, USA
fDate :
6/1/1992 12:00:00 AM
Abstract :
The authors describe the dependence of the radiation-induced threshold voltage shift (ΔVt) of n-channel IGFET devices on the substrate doping concentration and the concentration of segregated boron atoms in the oxide. Substrate resistivities of 0.1 and 0.5 ohm/cm were used. The thicknesses of the investigated gate oxides varied from 17.0 to 50.0 um. The devices were irradiated with Al Kα (1.49 keV) X-rays to different radiation doses at identical dose rates. The threshold voltages were measured before and after irradiation, employing an optically assisted hot electron injection technique. Following irradiation and hot electron injection, the threshold voltage shifts due to fixed positive charge (ΔVFPC) and neutral electron traps (ΔVNET) were determined. The radiation-induced threshold voltage shifts due to FPCs were greater for the 0.5 ohm/cm wafer than for the 0.1 ohm/cm wafer, and the threshold voltage shifts due to NETs were greater for the 0.1 ohm/cm substrate. The interface concentration of boron in the oxide at different depths obtained from Suprem-III simulations was related to induced threshold voltage shifts
Keywords :
X-ray effects; electron traps; hot carriers; impurity distribution; insulated gate field effect transistors; 0.1 to 0.5 ohmcm; 17 to 50 nm; IGFET; Si-SiO2:B; Suprem-III simulations; X-rays; fixed positive charge; gate oxides; n-channel; neutral electron traps; optically assisted hot electron injection technique; oxide thickness; radiation-induced damage; substrate doping concentration; substrate resistivity; threshold voltage shifts;
Journal_Title :
Circuits, Devices and Systems, IEE Proceedings G
