For the development of three-dimensional devices, selective epitaxial growth (SEG) technology has attracted much attention. SEG has been applied to fabricate many devices and it is expected to be used in future manufacturing processes. Therefore, its characteristics must be examined in detail to extend its application. For the fabrication of a three-dimensional device structure, the selectivity of epitaxial growth must be accurately controlled not only on Si and SiO2, but also on different impurity-type silicon surfaces. In this work, we investigated some characteristics of the SEG process, especially focusing on the surface roughness after SEG. Both vapor phase epitaxy (VPE) and solid phase epitaxy (SPE) were performed on ion-implanted silicon-on-insulator (SOI) thin wafers. It was often reported that epitaxial growth is very sensitive to the crystal condition of the substrate on which the films are deposited. However, we first revealed that the impurity type (p- or n-type) and its concentration at the substrate surface markedly changed the roughness and incubation times of the deposition. From our results, SPE with the oxide cap layer formation is effective for maintaining almost the same flatness as the original wafer surface. It is also effective to employ the low-temperature H2/Xe plasma treatment after the SEG to reduce roughness.

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The reduction of copper oxide by isopropyl alcohol (IPA) gas and its mechanism were investigated toward the selective process of copper (Cu) wiring. Also, the decomposition behavior of IPA gas and surface modification during the IPA treatment on Cu and copper oxide surfaces were studied. Two samples were measured: Cu surface having native oxide film and a metal Cu surface after a hydrogen reduction treatment. The decomposition and reaction behaviors and adsorption characteristics of IPA were investigated using the inline evaluation system equipped with a Cu reactor and Fourier transform infrared spectroscopy. The chemical structures of the Cu and copper oxide surfaces before and after IPA treatment were analyzed by x-ray photoelectron spectroscopy. Based on the experiments, the process condition to induce reduction of copper oxide by IPA gas during the Cu processes temperature range was identified. It was also found that different organic matter derived from IPA was adsorbed on each surface.

A low-temperature silicon nitride (SiNx:H) film-deposition technique that utilizes ultraviolet (UV)-irradiated ammonia (NH3) as the reactant gas and nonirradiated disilane (Si2H6) as the precursor gas was investigated. The UV light was only used to generate active species from NH3, not to irradiate the substrate. To determine the effect of the active species on the deposition process, SiNx:H films were deposited via chemical vapor deposition and their refractive index and composition ratio were evaluated. The results demonstrate that the highly reactive species generated from UV-light-irradiated NH3 enabled the deposition of nitrogen-containing films between 30°C and 450°C. N/Si ratio and refractive index of approximately 1.33 and 1.9–2.0, were obtained for a SiNx:H film deposited at 350°C and 450°C, respectively.

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