Atomic-layer-deposited alumina (ALD Al 2 O 3 ) can be utilized for passivation, structural, and functional purposes in electronics. In all cases, the deposited film is usually expected to maintain chemical stability over the lifetime of the device or during processing. However, as-deposited ALD Al 2 O 3 is typically amorphous with poor resistance to chemical attack by aggressive solutions employed in electronics manufacturing. Therefore, such films may not be suitable for further processing as solvent treatments could weaken the protective barrier properties of the film or dissolved material could contaminate the solvent baths, which can cause cross-contamination of a production line used to manufacture different products. On the contrary, heat-treated, crystalline ALD Al 2 O 3 has shown resistance to deterioration in solutions, such as standard clean (SC) 1 and 2. In this study, ALD Al 2 O 3 was deposited from four different precursor combinations and subsequently annealed either at 600, 800, or 1000 °C for 1 h. Crystalline Al 2 O 3 was achieved after the 800 and 1000 °C heat treatments. The crystalline films showed apparent stability in SC-1 and HF solutions. However, ellipsometry and electron microscopy showed that a prolonged exposure (60 min) to SC-1 and HF had induced a decrease in the refractive index and nanocracks in the films annealed at 800 °C. The degradation mechanism of the unstable crystalline film and the microstructure of the film, fully stable in SC-1 and with minor reaction with HF, were studied with transmission electron microscopy. Although both crystallized films had the same alumina transition phase, the film annealed at 800 °C in N 2 , with a less developed microstructure such as embedded amorphous regions and an uneven interfacial reaction layer, deteriorates at the amorphous regions and at the substrate–film interface. On the contrary, the stable film annealed at 1000 °C in N 2 had considerably less embedded amorphous regions and a uniform Al–O–Si interfacial layer.

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Chemicals from various suppliers were tested for the metal contamination levels left on silicon wafers after cleaning. During the investigations, hydrochloric acids and ammonium hydroxides from three vendors and hydrogen peroxides from four vendors, were evaluated. The wafers were cleaned in RCA standard solutions, after which particle counts and metal contamination were measured. Total reflection x-ray fluorescence analysis was used for metal contamination measurements. Hot ammonium hydroxide-hydrogen peroxide mixture (APM), an efficient particle remover, results in iron deposition on silicon. The amount of deposited iron is strongly dependent on the quality of the peroxide used in the mixture, and it can be reduced by using a shorter cleaning time. The deposition rate of iron on a wafer is probably diffusion limited for short times before the equilibrium is reached between the metal concentrations on the wafer and in the solution. The iron concentration after APM is not very sensitive to the age of the chemical mixture. There is, however, more zinc deposited in an aged chemical mixture. The same type, but weaker, dependence of iron concentration on chemical supplier observed after APM was also found after hot hydrochloric acid-hydrogen peroxide mixture (HPM). The iron concentrations were much lower. The HPM mixture however, causes a considerable increase in particle counts. These particles are, fortunately, loosely bound to the wafer surface and can therefore be easily removed. The copper concentration on silicon remained essentially constant, independent of chemical supplier, cleaning solution, or the time used for the cleaning. If APM is used as the last cleaning solution, the choice of the peroxide supplier is critical. However, if HPM is used, all the tested chemical grades give essentially the same metal contamination levels. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 193.0.65.67 Downloaded on 2015-03-25 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 193.0.65.67 Downloaded on 2015-03-25 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 193.0.65.67 Downloaded on 2015-03-25 to IP