C-V AND IV CHARACTERISTICS OF A MOSFET WITH SI-IMPLANTED GATE-SIO2

C-V and I-V characteristics of an N-MOSFET with Si-implanted gate-SiO2 of 50 nm are analyzed by using a test device with large equal channel width and length of 100 mum, and discussed for realizing a large hysteresis window of threshold voltage. Interface trap densities change logarithmically from approximately 3 x 10(10) to approximately 1 x 10(12) cm-2eV-1 as the Si-dose at 25 keV increases from zero to 3 x 10(16) cm-2. Threshold-voltage changes caused by 25 keV implantations are as high as +/-0.2 V. Effective mobilities (subthreshold swings) change from approximately 600 (approximately 0.10) to approximately 100 cm2/V.s (approximately 0.26 V/decade) as the Si-dose increases from 0 to 3 x 10(16) cm-2 at 25 keV, and both parameters are related with the change of interface trap densities. There is a close relationship between the hysteresis windows of gate current and threshold voltage, and the largest threshold voltage window in a low gate voltage region is obtained for the MOSFET with Si-implantation at 25 kev/3 x 10(16) cm-2.