Reactivity of the Si(100)-2 × 1-Cl surface with respect to PH3, PCl3, and BCl3: comparison with PH3 on Si(100)-2 × 1-H

Abstract

Despite the interest in a chlorine monolayer on Si(100) as an alternative to hydrogen resist for atomic-precision doping, little is known about its interaction with dopant-containing molecules. We used the density functional theory to evaluate whether a chlorine monolayer on Si(100) is suitable as a resist for PH3, PCl3, and BCl3 molecules. We calculated reaction pathways for PH3, PCl3, and BCl3 adsorption on a bare and Cl-terminated Si(100)-2 × 1 surface, as well as for PH3 adsorption on H-terminated Si(100)-2 × 1, which is widely used in current technologies for atomically precise doping of Si(100) with phosphorus. It was found that the Si(100)-2 × 1-Cl surface has a higher reactivity toward phosphine than Si(100)-2 × 1-H, and, therefore, unpatterned areas are less protected from undesirable incorporation of PH3 fragments. On the contrary, the resistance of the Si(100)-2 × 1-Cl surface against the chlorine-containing molecules turned out to be very high. Several factors influencing reactivity are discussed. The results reveal that phosphorus and boron trichlorides are well-suited for doping a patterned Cl-resist by donors and acceptors, respectively.