The performance of scanning driver circuits fabricated with self-aligned aluminum gate polysilicon thin-film transistors (TFT's) is demonstrated. After the gate electrode patterning, the fabrication process temperature is kept below 400° C to enable the use of aluminum gate electrodes. The low-temperature crystallization phenomenon, which occurs when protons are implanted simultaneously with boron or phosphorus dopants, is employed to eliminate the 600° C activation-annealing process. A maximum clock frequency of about 2.0 MHz is achieved when the driver operating voltage is 24 V and the TFT channel length is 12 µm.
We investigated the relative oxidation rates of single-crystalline Si substrates with various orientations to study the formation of thermally grown oxide films on multicrystalline Si at low temperatures in high-pressure water vapor. The oxidation rates depended greatly on the Si substrate orientation, but the increasing pressure did not change the proportion of their relative oxidation ratio even though the oxidation rate was accelerated by the pressure. On the basis of our modeling of the Si surface structure, we consider that the dependence of oxidation ratio on substrate Si orientation depends in turn on interface atomic density for a structure that has one or two Si-O bonds.
Crystallization induced by proton beam irradiation using large area ion implantation at low temperature (less than 600°C) have been investigated. Phosphine gas containing hydrogen of more than 95% is discharged by RF power of 100W. Both phosphorus ions and protons are accelerated by a potential of 100kV and implanted into polycrystalline silicon (poly-Si) layers. At a range of beyond 2×1015 ions/cm2 P1 ions dose, amorphous phase is primarily formed and then changes into polycrystals again and its grain sizes grow up to 50nm in average diameter. The crystallization is found to occur simultaneously with phosphorus doping and to depend on the amount of the irradiated protons. This technique enables us to eliminate the activation annealing process for implanted dopant.
A new diagnostic method for target deposition profiles of light ion beams is described. The deposition profile can be determined from the incident deuteron and the D-D reaction neutron energy distributions. Plasma effects on beam deposition profiles in high-temperature targets can be investigated by applying this method to focused beam-target experiments.
A single-crystalline Si film was transferred onto a Si wafer and non-alkaline glass by hydrogen-induced exfoliation and the effect of pulsed green-laser annealing was investigated. Above a laser energy of 1285 mJ/cm 2 , the crystallinity of the Si film was recovered both on the Si wafer and the glass. The linewidth of micro-Raman spectra of the Si film on the Si wafer was constant at about 3.9 cm À1 which was close to that for commercial silicon-on-insulator (SOI) wafer. On the other hand, the linewidth of the Si film on the glass was constant at about 4.1 cm À1 . A Raman peak shift toward a lower frequency was observed on the Si film on the glass; it was assumed that the difference of the linewidth on the Si wafer and that on the glass originated from the tensile stress in the Si film due to the difference of thermal expansion coefficients. The results of numerical simulation suggested that the thickness of the region damaged by hydrogen ion implantation was greater than 300 nm; the damaged region had to be melted and resolidified to obtain the recovered single-crystalline silicon upon pulsed laser annealing.
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