In Situ Auger Electron Spectroscopy Study of Atomic Layer Deposition:  Growth Initiation and Interface Formation Reactions during Ruthenium ALD on Si−H, SiO₂, and HfO₂ Surfaces

Abstract

Growth initiation and film nucleation in atomic layer deposition (ALD) is important for controlling interface composition and achieving atomic-scale films with well-defined composition. Ruthenium ALD is studied here using ruthenocene and oxygen as reactants, and growth initiation and nucleation are characterized on several different growth surfaces, including SiO2, HfO2, and hydrogen terminated silicon, using on-line Auger electron spectroscopy and ex-situ X-ray photoelectron spectroscopy. The time needed to reach the full growth rate (typically approximately 1 A per deposition cycle) is found to increase as the surface energy of the starting surface (determined from contact angle measurements) decreased. Growth starts more readily on HfO2 than on SiO2 or Si-H surfaces, and Auger analysis indicates distinct differences in surface reactions on the various surfaces during film nucleation. Specifically, surface oxygen is consumed during ruthenocene exposure, so the nucleation rate will depend on the availability of oxygen and the energetics of surface oxygen bonding on the starting substrate surface.

Effects of Ar plasma treatment for deposition of ruthenium film by remote plasma atomic layer deposition

“…These surface energies were derived from contact-angle data by using water and diiodomethane, and calculated from the Young-Dupré relationship: were quite similar, but the polar components varied with Ar plasma treatment and temperatures. 26 However, in our experiments, the growth rate was faster in the initial transient region on the SiO 2 surface with fewer hydroxyl groups. The polar component decreased with increases in temperature, and the polar component of SiO 2 after Ar plasma treatment at 400 C was smaller than that of SiO 2 alone heated at 400 C [ Fig.…”

Recent Developments of Atomic Layer Deposition Processes for Metallization

“…The robustness of the Ru ALD process, and the high quality of the resulting thin films, has triggered extensive research activities due to potential applications in DRAM, interconnect technologies, and in the nano‐sciences 94–103. It was quickly found that the Ru metal process can be extended to other metal‐organic precursor systems, and covers the entire Group VIII noble metals.…”

The Role of the Methyl and Hydroxyl Groups of Low-k Dielectric Films on the Nucleation of Ruthenium by ALD

“…4 In most ALD systems, however, a transient cycle region exists before the growth process reaches the linear growth region with increasing number of deposition cycles. 5,6 If there are not enough nucleation sites on the surface, sparse nucleation may occur ͑i.e., long transient time͒, which may cause a significant variation in the growth rate with the number of deposition cycles. This sparse nucleation may also lead to the generation of pinholes through which Cu can easily penetrate, raising serious reliability concerns.…”