Ab Initio Study of the Early Stage of Si Epitaxy on the Chlorinated Si(100) Surface

Abstract

The homoepitaxial growth of Si on Si(100) covered by a resist mask is a necessary technological step for the fabrication of donor-based quantum devices with scanning tunneling microscope lithography. In the present work, the chlorine monolayer is selected as the resist. Using density functional theory, we investigated the adsorption of a single silicon atom on Si(100)-2×1-Cl as the starting process of Si epitaxy. The incorporation of a silicon atom under a Cl monolayer proved to be the most energetically favorable process. Our results show that chlorine segregates on the surface during Si deposition and does not incorporate into homoepitaxial layers. In addition, we found that SiCl * 2 , SiCl * 3 , and SiCl * 4 clusters can be formed above a Si(100)-2×1-Cl surface while Si is adsorbed. SiCl * 2 clusters are bound weakly to the substrate, and their desorption leaves the silicon surface free of chlorine. To check whether the Si epitaxy is possible on the chlorine resist, we compare our results with the well-studied case of a hydrogen resist. We find the two processes to be similar; moreover, epitaxy on chlorine resist appears to have an advantage.

Area-selective deposition and B $δ$-doping of Si(100) with BCl$_{3}$

“…While there is a measured peak Cl concentration of 3.3(3) × 10 18 cm −3 at the buried interface, a substantially larger amount of Cl was found within the epitaxial Si layer closer to the surface. Cl is expected to act as a surfactant during Si growth and exchange places with deposited Si, altering the growth kinetics 28 in much the same way as H, leading to the profile seen in Fig. 2.…”

“…Surfactant-mediated growth is known to enhance layer-by-layer growth in homoepitaxy and suppress threedimensional (3D) islanding 29,30 . In addition, theoretical investigations have suggested a pathway towards removing Cl from the growth front due to lowered barriers to desorption for SiCl 2 28 . Under the growth conditions utilized in these investigations, we find evidence of Cl exchanging with Si adatoms and floating to the surface, but are unable to quantify amount of Cl lost.…”

B-Doped δ-Layers and Nanowires from Area-Selective Deposition of BCl3 on Si(100)

“…This alters the growth kinetics in much the same way as H, leading to the profile seen in Figure b. Surfactant-mediated growth is known to enhance layer-by-layer growth in homoepitaxy and suppress three-dimensional (3D) islanding. , In addition, theoretical investigations have suggested a pathway toward removing Cl from the growth front due to lowered barriers to desorption for SiCl 2 . Under the growth conditions utilized in these investigations, we found evidence of Cl exchanging with Si adatoms and segregation to the surface, as is evidenced by the Cl profile in Figure b peaking near the surface.…”

“…While the measured peak Cl concentration at the buried interface is only C p = 3.3(3) × 10 18 cm –3 , a substantially larger amount of Cl was found within the epitaxial Si layer closer to the surface. Cl is expected to act as a surfactant during Si growth and exchange with Si as it deposits . This alters the growth kinetics in much the same way as H, leading to the profile seen in Figure b.…”

Adsorption Behaviors of Chlorosilanes, HCl, and H2 on the Si(100) Surface: A First-Principles Study

“…Besides, some interesting phenomena can be observed after single-molecule adsorption on Si(100). For example, the SiCl 2 , SiCl 3 , and SiCl 4 clusters can be formed after the Si atom is adsorbed on the chlorinated Si(100) surface . When the Cl atom is adsorbed on the Si(100) surface under ultrahigh vacuum conditions, the dissociated Cl 2 and the active Cl radicals can lead to the formation of SiCl 4 .…”