Adsorption of TripletO2on Si(100): The Crucial Step in the Initial Oxidation of a Silicon Surface

Abstract

It has long been understood that a precursor mediated chemisorption is a significant part of the dynamics for the adsorption of O(2) on Si(100), which is a much studied model system of surface reaction with considerable technological relevance. However, theoretical studies on the interaction between O(2) and Si(100) have been focused on the excited singlet state of O2 and unable to explain the observations in surface scattering experiments. We demonstrate by first principles calculations that such a focus is misplaced. In reality, triplet O(2) can also react with Si(100), after overcoming small barriers, and its reaction paths provide a full account for experiments. Our results highlight the important role played by triplet O(2) in surface oxidation.

Multi-scale modeling of oxygen molecule adsorption on a Si(100)-p(2×2) surface

“…In all tested configurations, we observe the spin conversion from the spin-triplet state to spin-singlet state as observed by Kato et al [1] and by Fan et al [6]. Among all the tested adsorption sites, we observe that the energy gain is larger when the molecule is completely dissociated on two different silicon sites and directly integrated into the surface, i.e.…”

“…It has been proven that the gate thickness cannot be thinner than five atomic silicon layers which should be reached by 2012 without generating basic problems such as the leakage current, reliability, tunneling. Despite a large amount of experimental and theoretical studies [1][2][3][4][5][6], the oxide growth mechanisms are still unknown or subject to much controversy. Understanding the first steps of silicon oxidation remains essential to control the oxide growth and to anticipate the addition of further materials such as high-k materials.…”

SiO adsorption on a p(2×2) reconstructed Si(100) surface

“…1b, with the Si bottom layer terminated with eight hydrogen atoms is used. This structure is similar to the silicon surface investigated in the recent papers of Fan and co-workers [25,26]. The top-most layer consists of four silicon atoms, which form into two Si dimer pairs with alternate buckling along the same row upon surface reconstruction.…”

“…In particular, if a Si adsorbate atom were to be replaced with O in configurations A 3 and A 7 , they would resemble that of the peroxides and the bridge geometries of oxygen molecule found in Ref. [25]. Considering only the absorption of the singlet states of O 2 , the adsorption energies of configuration A 3 and A 7 were reported to be À1.60 and À3.02 eV, respectively, which is lower than the SiO adsorption energies found here (À0.98 and À2.15 eV for A 3 and A 7 , respectively).…”

Frequencies of normal vibrations of oxygen complexes on silicon (111) face

“…So, it is extremely important to develop methods of crystalline silicon production capable to guarantee the oxygen content proper for the working characteristics. Another way of oxygen ingress into silicon is adsorption of O 2 molecules onto a surface of silicon crystals followed by dissociation into atoms and their further insertion into Si-Si bonds [6][7][8][9][10].…”