In-plasma, vacuum ultraviolet photon-assisted etching of silicon

摘要: In-plasma photo-assisted etching (PAE) of p-type Si (100) in a Cl 2/Ar inductively-coupled plasma (ICP) was investigated. Experiments were carried out in a tandem reactor that allowed predominantly 104 and 106 nm Ar emission from the upper He/Ar ICP to enter the lower, main Cl 2/Ar ICP through a mesh that prevented plasma transmission. With ion energies below the ion-assisted etching threshold in the Faraday-shielded main ICP, VUV photons are found to be remarkably efficient in promoting etching, with measured yields of over 100 Si atoms etched per photon. Masked samples were found to etch with no undercutting and smooth sidewalls with angles of 125 o, corresponding to (111) planes. It was found that PAE in the main ICP was enhanced by up to 50% by simultaneous operation of both the upper and lower ICPs. When only the upper ICP VUV source was operated, irradiating the substrate in the lower …