Characterization of LPCVD and PECVD silicon oxynitride films

The chemical composition and structure of silicon oxynitrides, deposited in low pressure and plasma enhanced chemical vapour deposition processes are discussed. From an extrapolation of the characteristics of plasma grown oxynitrides a model for the deposition of LPCVD material is derived. A main conclusion of this model is that Si-Si bonds have a larger tendency to occur in this material than Si dangling bonds

The kinetics of the interactions of O2 and N20 with a Cu(110) surface and of the reaction of CO with adsorbed oxygen studied by means of ellipsometry, AES and LEED

Ellipsometry, LEED and Auger electron spectroscopy have been used to study the interactions of O2 and N2O with a clean annealed Cu(110) surface and the reaction of CO with adsorbed oxygen in the monolayer range. Gas pressures were in the range 10−8–10−4 Torr and crystal temperatures varied between 23–400°C. The changes in the ellipsometric angles Δ and ψ per oxygen atom upon adsorption and removal of oxygen depend on the coverage θ, the temperature and on the azimuth of the plane of incidence of the light beam. The kinetics of the chemisorption of oxygen is independent of the crystal temperature, initial sticking probability ≈ 0.2. The LEED data and the adsorption kinetics indicate an attractive interaction in the adsorbed layer in the [001] direction. The initial decomposition probability of N2O at room temperature is 0.15 and decreases with increasing temperature; the maximum coverage is 0.5 monolayer. The LEED patterns observed were the same as those with O2. The reaction probability of CO with adsorbed oxygen increases with decreasing oxygen coverage (order of magnitude 10−5, apparent activation energy 6 kcal/mol). This increase has been attributed to the operation of the Langmuir-Hinshelwood mechanism

The adsorption and incorporation of oxygen on Cu(100) and its reaction with carbon monoxide; comparison with Cu(111) and Cu(110)

Ellipsometry, LEED, Auger electron spectroscopy and monitoring of work function changes have been used to study the interactions of O2 and N2O with a clean annealed Cu(100) surface and of the reaction of CO with sorbed oxygen. Gas pressures were in the range 10−7−10−4 Torr and crystal temperatures varied between 25–400°C. The initial interaction of oxygen with Cu(100) occurs in three stages. Oxygen chemisorbs with an initial sticking coefficient of ˜10−7 at room temperature and an apparent activation energy of 1.3−3.5 kcal/mol, depending on the substrate temperature. The first stage is the formation of a (√2 × √2)R45° LEED pattern up to a coverage of 0.5, which is converted with an apparent activation energy of 3.2 kcal/mol to a (√2 × 2√2)R45° structure at a coverage of 0.75 in the second stage. The work function increases inthe first stage in an amount of ˜300 meV, but decreases in the second stage to the value of the clean surface. In a third stage after an induction period further oxygen uptake could be registered only with ellipsometry. The apparent activation energy is 4.5 kcal/mol. The initial decomposition probability of N2O at room temperature is 5 × 10−5, its apparent activation energy 3.2 kcal/mol. The LEED patterns observed were the same as with O2. The sorbed oxygen can be removed at all coverages with CO. The reaction appears to follow Langmuir-Hinshelwood kinetics with an activation energy for the reaction COad + Oad → CO2 of 19–20 kcal/mol. A comparison is made with the data obtained for Cu(111) and Cu(110)

A study of the kinetics of the interactions of O2 and N2O with a Cu(111) surface and of the reaction of CO with adsorbed oxygen using aes, LEED and ellipsometry

The interactions of O2 and N2O in the low pressure range with a Cu(111) surface and of CO with adsorbed oxygen have been studied with ellipsometry, Auger electron spectroscopy and LEED. The adsorption of O2 was investigated in the 10−6–10−4 Torr range and at crystal temperatures ranging from 23 to 400°C. O2 chemisorbs dissociatively with an initial reaction probability of about 10−3 and an apparent activation energy of 2–4 kcal/mol, which depends on the substrate temperature, up to a saturation coverage of 0.45. The probability of decomposition of N{ib2}O is 10−5 at 300°C, and the activation energy is 10.4 kcal/mol for 250 < T < 400°C. The oxygen coverage saturates at θ = 0.45 as well. For both oxidation reactions the kinetics can be described with a precursor state model. With LEED no superstructures were observed. The probability of the reaction of CO with adsorbed oxygen is 4 × 10−5 at 250°C and is initially independent of the oxygen coverage. The reaction is assumed to proceed via a Langmuir-Hinshelwood mechanism. The activation energy for the reaction COad + Oad → CO2 is 18–20 kcal/mol