  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 \ce{PH3}, \ce{PCl3}, and \ce{BCl3} molecules. We calculated reaction
pathways for \ce{PH3}, \ce{PCl3}, and \ce{BCl3} adsorption on a bare and
Cl-terminated Si(100)-2$\times$1 surface, as well as for \ce{PH3} adsorption on
H-terminated Si(100)-2$\times$1, which is widely used in current technologies
for atomically precise doping of Si(100) with phosphorus. It was found that the
Si(100)-2$\times$1-Cl surface has a higher reactivity towards phosphine than
Si(100)-2$\times$1-H, and, therefore, unpatterned areas are less protected from
undesirable incorporation of \ce{PH3} fragments. On the contrary, the
resistance of the Si(100)-2$\times$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.
