The surfaces of AlN powders, which are particularly sensitive to moisture and atmospheric oxygen, are characterized by x-ray photoelectron spectroscopy (XPS). The powders used were exposed to ambient air and then heat treated at 100 °C in air, argon, or nitrogen gas. Bremsstrahlung-excited Auger electron spectroscopy was used in combination with XPS to distinguish aluminum hydroxide from aluminum nitride on powder surfaces. The Auger peaks due to aluminum hydroxide and aluminum nitride were successfully resolved. The predominant surface oxygen-containing species was found to be aluminum hydrate with a composition near Al(OH)3, AlOOH, or a mixture of them, depending on the heat treatment employed. Such data are useful in understanding the feedstock surface chemistry involved in the fabrication of AlN ceramics.

As the semiconductor industry pushes toward increased transistor density and continues to develop faster, smaller, and less expensive microchips, it is necessary to continually meet significant technical challenges. The next generation technology will require more stringent tolerances on the composition, structure, and uniformity of silicon wafer surfaces and on the insulating and conducting layers that make up ultralarge scale integrated circuits (ULSIs). Specifically, ultrathin gate oxides used in these technologies are sensitive to surface contaminants and impurities that may be introduced during silicon wafer manufacturing and ULSI fabrication. Therefore, the understanding, optimization, and control of preoxidation cleaning sequences continue to be an important area of research.Al is ubiquitous in semiconductor fabrication processes. It is known that Al does not degrade the lifetime of silicon, does not increase leakage current, and does not lead to a drop in breakdown voltages of thermal oxides when it exists on the Si surface. However, negative effects of Al contamination have been reported on gate oxide properties. For example, Al contamination increased the n ϩ /p junction leakage current, decreased breakdown voltages due to the increase in SiO 2 /Si interface state density, 1 and generated fixed negative charge. 2 For an ultrathin gate oxide, such undesirable effects of Al on device performance can be exacerbated. Also as the feature size of ULSI circuits decrease, the gate oxide thickness must scale down, and its control becomes important. DeLarios et al. investigated the effect of Al on oxidation kinetics and reported that Al contamination on Si surfaces decreases the oxidation rate when oxide thickness is greater than 200 Å. 3,4 In their work, the oxidation rate degrades by 15ϳ20% for 1000 Å oxides. In this case, Al exists on the Si surface and is deposited from a "reverse RCA" clean. Such a large difference of oxidation rate may not be tolerable for ultrathin gate oxides. The deleterious effect of Al contamination on the oxide properties has to be elucidated. Therefore, in this study we show the effect of Al contamination on the oxidation kinetics and the corresponding dielectric breakdown trends for ultrathin oxides.Experimental p-Type silicon (100) wafers ( ϭ 5 ϳ 20 ⍀ cm) were used in this study. The Si wafers were first treated with the standard prediffusion clean used at Stanford's Center for Integrated Systems (CIS). The wafers were dipped into Piranha solution (H 2 SO 4 :H 2 O 2 ϭ 4:1) at 90ЊC for 10 min and followed by a deionized water rinse. Then they were immersed in 49% HF:H 2 O ϭ 1:50 solution at room temperature for 30 s and went though the deionized water rinse. They were dipped into the SC2 solution (HCl:H 2 O 2 :H 2 O ϭ 1:1:5) at 80ЊC for 10 min and rinsed in deionized water. The Si wafers were then immersed in an SC1 solution (NH 4 OH:H 2 O 2 :H 2 O ϭ 1:1:5) made from ultrapure chemicals (Kanto Co), which were spiked with 0, 0.1, 1, and 10 parts per billion of Al in solution. Al in 1...

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Organotitanate additives are known to reduce the viscosity of many filled polymer systems, including formulations of interest for ceramic powder injection molding. Mineral oil was used as a model solvent for these systems to examine the effects of Organotitanate additions on the stability and rheology of A1N dispersions. Addition of the titanate coupling agents neoalkoxy tri(neodecanoyl) titanate and neoalkoxy tri(dioctylphosphato) titanate resulted in better dispersion as measured by sedimentation tests and rheological characterizations. Excellent correlation of the sediment heights and measured viscosities with adsorption isotherms for the organotitanates was shown, with both lower sediment height and lower viscosity obtained when a monolayer of the titanate molecules was present on the powder surface. Comparison of the behavior of the mineral oil based systems with the viscosity of corresponding polypropylene based binder systems indicates that the titanate additions are effective in reducing particle‐particle interaction effects in both systems.