Atomically controlled processing for group IV semiconductors

Atomic-order surface reaction processes on the group IV semiconductor surface are formulated based on the Langmuir-type surface adsorption and reaction scheme. In in situ doped Si_1-xGe_x epitaxial growth on the (100) surface in an SiH₄-GeH₄-dopant (PH₃, B₂H₆ or SiH₃CH₃)-H₂ gas mixture, the deposition rate, the Ge fraction and the dopant concentration are explained quantitatively by assuming that the reactant gas adsorption/reaction depends on the surface site materials and that the dopant incorporation in the grown film is conducted by Henry's law. The self-limiting formation of 1-3 monolayers of group IV or related atoms in the thermal adsorption and reaction of hydride gases (SiH₄, GeH₄, NH₃, PH₃, CH₄ and SiH₃CH₃) on Si(100) and Ge(100) is also generalized based on the Langmuir-type model. The Si epitaxial growth over the phosphorus layer already formed on Si(100) by PH₃ treatment is achieved. Moreover, atomic layer-by-layer etching of Si and Ge is achieved by alternate chlorine supply and irradiation of low-energy Ar⁺ ions, where the chlorine adsorption is described by the Langmuir-type model. Silicon nitride is also etched layer by layer via a role-share method with an argon and hydrogen mixed plasma. These results open the way to atomically controlled processing for ultra-large-scale integration.