Naslov
Atomic relocation processes in semiconductor materials

Autori
Deenapanray, Prakash N.K.

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, doktorska disertacija

Fakultet
Department of Electronic Materials Engineering

Mjesto
Canberra

Datum
20.04

Godina
2000

Stranica
164

Mentor
Petravić, Mladen

Neposredni voditelj
Petravić, Mladen

Ključne riječi
semiconductors; atomic relocations; Secondary ion mass spectrometry

Sažetak
Oxygen and nitrogen ions have a strong affinity for compound formation with semiconductor materials, especially Si. Bombardment with these reactive ions, therefore, allows the investigation of the fundamental ion-induced chemical reactions in the near-surface region of Si.1, 2 The athermal formation of dielectric materials, such as SiO2 and, especially, Si3N4, by ion bombardment has attracted considerable interest as an alternative to their thermodynamically induced thermal synthesis and chemical vapour deposition.2 For instance, the kinetics of thermal nitridation, which is 3 X 10-12 nms-1 at 1100°C, is extremely slow compared to ∼0.3 nms-1 for the oxidation of Si at the same temperature.3 Layers produced by chemical deposition have their structural composition and properties which depend strongly on the deposition parameters, such as deposition pressure, gas flow rates, and substrate temperature.4, 5 This will be further demonstrated in chapter 6 for plasma enhanced chemical vapour deposited silica layers. It is also known that the thermal stability of plasma deposited Si- nitride layers are adversely affected by the incorporation of hydrogen, whereas the presence of moisture could degrade the dielectric property of oxides.6 Ion beam oxidation of Si has been used to produce device quality buried oxide layers in silicon-on- insulator structures, 7, 8 while ion beam synthesized nitride layers have been employed as oxidation barriers and gate dielectrics.9, 10 The depth resolution, i.e. the ability of an anlytical technique to detect and resolve abrupt signal changes, is one of the most important parameters in depth profiling of impurities in solids by secondary ion mass spectrometry (SIMS). The depth resolution of impurity profiles is influenced by the angle of incidence, the energy, and species of the primary ion beam used in SIMS. The energy dependence of the profile broadening of various impurities, resulting from both nonreactive (Ar, Xe, Ne) and reactive (Cs, N2, O2) beams, has been studied using mostly near-normal incidence.1-4 The depth resolution has been correlated with the penetration depth of low energy inert ions (0.5-15 keV), featuring an increase with impact energy. Increasing the angle of incidence, θ, measured from the surface normal, also improves the depth resolution of impurity profiles. Several theoretical models predict a (cosθ)-f angular dependence of profile braodening for polycrystalline and isotropic materials (1 ≤ f ≤ 5/3).5, 6 However, the theoretical predictions break down at the glancing incidence, when most of atom recoils are generated close to the surface and the reflection coefficient of the primary beam becomes large, and the near-normal incidence with low energy reactive ions, which results in compound formation at the surface of Si. For instance, it has been shown that near-normal incidence with nitrogen2 or oxygen3 ions resulted in better depth resolution compared to neon ions. The previously reported enhancement in depth resolution with reactive ions was attributed to beam-induced compound formation.2, 3 It was, however, pointed out that better depth resolution was only achieved when dealing with nonsegregating impurities during compound formation.2

Izvorni jezik
Engleski

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