Reactivity of the Si(100)-2$\times$1-Cl surface with respect to PH$_3$, PCl$_3$, and BCl$_3$: Comparison with PH$_3$ on Si(100)-2$\times$1-H

TL;DR

This study uses density functional theory to compare the reactivity of Si(100)-2×1-Cl and H surfaces with dopant molecules, revealing chlorine monolayers' potential as a resist for atomic doping with specific molecules.

Contribution

It provides the first detailed theoretical comparison of chlorine monolayer resistance and reactivity with dopant molecules on Si(100) surfaces.

Findings

Cl monolayer increases reactivity towards PH3 compared to H monolayer

Cl monolayer offers high resistance against chlorine-containing molecules

PCl3 and BCl3 are suitable for doping through patterned Cl-resist

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 \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.