The gate oxide films have been grown at a temperature as low as 450 °C by direct oxidation of silicon. Such a low-temperature oxidation has been realized by employing a precision controlled ion bombardment in an Ar/O2 mixed plasma for the surface activation. Perfectly controlled Ar ions give the bombardment energy for the oxide film growth. Dielectric breakdown fields of 10 MV/cm are achieved. Integration in a total low-temperature device process has been demonstrated by fabricating self-aligned Al-gate metal-oxide-silicon field effect transistor (MOSFET) formed without any heat processing over 450 °C. The precise control of the ion bombardment is quite essential for the low-temperature process.
Low temperature, 600~ annealing of LPCVD films was investigated using x-ray diffraction, ESR, TEM, and carrier mobility measurements. An optimum deposition temperature of about 550~ was found to yield good crystallinity and high electron mobility for annealed films; large grain sizes, a maximum crystallite size, and a maximum electron spin density were also observed for films deposited at the optimum temperature. The crystallite number was shown to be constant if the deposition temperature was below 570~ Electron spring density for the as-deposited films correlated with the crystalline volume by x-ray diffraction measurements on the films after annealing. This implies that only those amorphous components with high electron spin density can be converted into the crystalline phase by 600~ annealing.
We investigated Cu/low-k integration to test the time-dependent dielectric breakdown ͑TDDB͒ reliability of Cu interconnects. We described the relationship between TDDB lifetime and defects possibly caused by the Cu chemical-mechanical polishing ͑CMP͒ process, such as rough copper surface corrosion, crevice corrosion, and scratches, using Cu/silicon oxycarbide interconnects. Although rough copper surface corrosion has an insignificant effect on the TDDB lifetime, crevice corrosion at the edges of wires does cause TDDB degradation. We also found that a structure's TDDB lifetime was affected by the kind of post-CMP cleaning solutions used when barrier metal slurries do not contain benzotriazole ͑BTA͒. These results indicate that two types of processes for post-CMP cleaning should be used. It is best to use solutions that do not have strong oxidized copper dissolution ability but can remove particles when a barrier metal slurry with an inhibitor other than BTA is used. Also good are solutions with a strong oxidized copper dissolution ability that have been optimized to prevent Cu corrosion when a barrier metal slurry with BTA is used. To improve TDDB reliability, care must be taken with regard to the combination of the barrier metal slurry and the post-CMP cleaning solution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.