Gettering property of Cu and Ni was investigated after MCP thinned process wafer. The test samples were prepared to various dopant concentration types of CZ or Epitaxial wafer, and various processed thinning conditions corresponding with a total remaining thickness of 100 µm, 50 µm, and 30 µm by backside grinding. It was found that the 30 µm thinned wafer maintains its Cu gettering ability for heavily boron doped samples but Ni contamination decrease the gettering ability for all samples.

A planar metal–insulator–semiconductor (MIS)-type field emitter using epitaxial γ-Al2O3 (111)/Si (111) structure was successively fabricated and field-emission phenomena were observed. Planar MIS-type field emitters using epitaxially grown Al2O3 were fabricated by molecular beam epitaxy (MBE) method and characteristics of these emitters were evaluated. It was confirmed that the Al2O3 possessed good crystalline quality and surface morphology. The breakdown field of the epitaxial Al2O3 layer was able to increase in situ annealing at the substrate temperature of 750 °C. From experimental measurements of diode current, conduction band offset (ΔEc) value between the epitaxial γ-Al2O3 and Si (111) substrate was calculated to be 2.5 eV. Fowler–Nordheim (F–N) tunneling was observed from the 8-nm-thick epitaxial Al2O3 film. Emission characteristics were obtained from the 10-nm-thick epitaxial Al2O3 insulator with a 20-nm-thick Al gate electrode. The maximum transfer ratio of emission current was confirmed to be 1%.

A novel concept of MCP substrates that shows the enhanced internal gettering ability even in thinned state was proposed. To achieve the concept, RTA treatment in high temperature was applied to the CZ-Si substrate with a high initial oxygen concentration. It was confirmed that precipitates were formed as high density even in the near surface shallower than 100 μm, where major portion of internal gettering should take place in the MCP process. Moreover, comparable gettering ability to the EPI wafer was confirmed in our concept after thinning, especially in Ni gettering. In conclusion, it was expected that this concept is one of the possible substitutions of EPI wafers in practical MCP process.

The characteristics of epitaxial γ-Al2O3 film deposited by molecular beam epitaxy (MBE) on a Si substrate have been studied for its application to quantum devices with different thicknesses. The epitaxial growth properties and surface morphology of the film were studied by in situ reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). Epitaxial γ-Al2O3 films on Si substrates with film thicknesses ranging from 2 to 10 nm exhibited an appropriate surface flatness. We observed that the epitaxial γ-Al2O3 films exhibit appropriate dielectric properties (6–12 MV/cm) and very low leakage currents. From the electrical characteristics, we observed Fowler–Nordheim (F–N) tunneling phenomena with a large band offset. The same properties in thick epitaxial γ-Al2O3 films may be suitable for quantum tunneling applications.

The control and evaluations of alkali metal such as Na have been important issues in device process. LTO layer was deposited on backside of wafer as backseal of epitaxial substrate. The backseal wafer with LTO was evaluated to study effect of Na contamination which was observed after NaOH mixture dip. We found Na out diffusion from LTO layer inducing surface oxidation rate increase in oxidation process. These phenomena considered to Na property of low boiling temperature point. However, Na from LTO layer did not affect epitaxial process because of hydrogen pre-baking in the epitaxy process.