Oxide Thickness Fluctuations Research Articles

Mobility degradation in very thin Oxide p-channel MOSFET's

The effective hole mobility in large-area p-channel MOSFET's decreases systematically over a wide range of oxide fields as the gate oxide thickness decreases from 240 to 31 Å. A scattering mechanism based on the variations of the gate-charge-induced Coulomb scattering potential in the channel resulting from gate oxide thickness and/or structural fluctuations over the gate area is proposed to explain the results.

The sensitivity of threshold voltage of ion-implanted MOSFET's to substrate doping and oxide thickness fluctuations : K. Board. Int. J. Electron.43, (2) 151 (1977)

The sensitivity of threshold voltage of ion-implanted MOSFET's to substrate doping and oxide thickness fluctuations : K. Board. Int. J. Electron.43, (2) 151 (1977)

The sensitivity of threshold voltage of ion-implanted MOSFET's to substrate doping and oxide thickness fluctuations

When the gate region of a MOSFET is implanted in order to adjust, the threshold voltage, the sensitivity of the threshold voltage to fluctuations in substrate doping will be affected. It is shown here that when the implanted ion is of the Same impurity type as the substrate, this sensitivity is lower than for a similar, unimplanted structure. However, the converse is found to he true when the implanted ion is of opposite type and the device is operating in a deep-depletion mode. The latter result has obvious importance in view of substrate–doping fluctuations over the surface of a single silicon wafer, and more so between many different wafers. The effect on the threshold voltage of oxide thickness variations is also investigated, and it is found there is a range of implant energy and dose over which the sensitivity can be very small. This is associated, however, with a sharp rise in the sensitivity outside this range.

The growth of thin PbO layers on lead films

Abstract The growth of ∼ 10 to 100 A thick, orthorhombic PbO layers on lead was investigated by ellipsometry, electron tunneling and X-ray diffraction. Oxides were grown on 2000 to 15000 A thick, vacuum-deposited lead films, using: oxygen pressures from 10 −2 to 10 +3 Torr; temperatures from −90 to + 150°C; and, times up to several weeks. Apparatus is described for monitoring ellipsometric parameters during oxidation and fabricating PbPbOPb tunnel junction devices in situ . The results indicate that lead recrystallization processes can accelerate the oxidation, so that the rates depend complexly on temperature, lead thickness and microsctructure. The refractive indices provide an indication of the extent of lead recrystallization effects on the oxidation process as well as the accuracy of the oxide thickness determination. X-ray findings indicate that the PbO has the orthorhombic PbO structure, is highly strained while being epitaxially related to the lead, and has a thickness close to that obtained ellipsometrically. Electron tunneling data provide a measure of oxide thickness fluctuations from the average or ellipsometrically-derived values.