Channeling of low-energy implanted ions through the poly-Si gate

Ion channeling through the poly-Si gate is investigated using Monte Carte s imulations. It is shown that even at very low energies, channeling may lead to dopant penetration through the gate oxide, resulting in large threshold voltage variations, in particular, of narrow-channel, submicron devices, U nlike thermally activated dopant diffusion through the gate dielectric that is severe only in the case of B, direct penetration due to channeling is a potential problem with all commonly used dopants, The maximum channeling r ange (minimum poly-Si thickness to prevent dopant penetration) is calculate d as a function of implant energy for B, P, and As ions.