The concept of atomically controlled processing for group IV semiconductors is shown based on atomic-order surface reaction control in Si-based CVD epitaxial growth. Si epitaxial growth on B or P atomic layer formed on Si(100) or Si1-xGex (100) surfaces, is achieved at temperatures below 500 °C. B doping dose of about 7×1014 cm-2 is confined within an about 1 nm thick region, but the sheet carrier concentration is as low as 1.7 ×1013 cm-2. The in-situ B doping in tensile-strained Si epitaxial growth suggests that the low electrical activity is caused by B clustering as well as the increase of interstitial B atoms. For unstrained Si cap layer grown on top of the P atomic layer formed on Si1-xGex(100) with P atom amount 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 amount around the heterointerface. The electrical inactive P atoms are generated by tensile-strain in heavy P doped region. These results demonstrate that atomically controlled processing for doping is influenced by strain.