One of the main requirements for Si-based ultrasmall device is atomic-order control of process technology. Here, we show the concept of atomically controlled processing for group IV semiconductors based on atomic-order surface reaction control in Si-based CVD epitaxial growth. Self-limiting
formation of 1–3 atomic layers of group IV or related atoms after thermal adsorption and reaction of hydride gases on Si1−xGex(100) (x = 0–1) surface are generalized based on the Langmuir-type model. Moreover, Si-based epitaxial
growth on N, P or C atomic layer formed on Si1−xGex(100) surface is achieved at temperatures below 500 °C. N atoms of about 4 × 1014 cm−2 are buried in the Si epitaxial layer within about 1 nm thick region. In
the Si0.5Ge0.5 epitaxial layer, N atoms of about 6 × 1014 cm−2 are confined within about 1.5 nm thick region. The confined N atoms in Si1−xGex preferentially form Si–N bonds. For unstrained
Si cap layer grown on top of the P atomic layer formed on Si1−xGex(100) with P atomic amount of below about 4 × 1014 cm−2 using Si2H6 instead of SiH4, the incorporated P atoms are almost
confined within 1 nm around the heterointerface. It is found that tensile-strain in the Si cap layer growth enhances P surface segregation and reduces the incorporated P atomic amount around the heterointerface. Heavy C atomic-layer doping suppresses strain relaxation as well as intermixing
between Si and Ge at the nm-order thick Si1−xGex/Si heterointerface. These results open the way to atomically controlled technology for ULSIs.
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