Influence of H2-annealing on the hydrogen distribution near SiO2/Si(100) interfaces revealed by in situ nuclear reaction analysis

Abstract

Employing hydrogen depth-profiling via 1H(15N,αγ)12C nuclear reaction analysis (NRA), the “native” H concentration in thin (19–41.5 nm) SiO2 films grown on Si(100) under “wet” oxidation conditions (H2+O2) was determined to be (1–2)×1019 cm−3. Upon ion-beam irradiation during NRA this hydrogen is redistributed within the oxide and accumulates in a ∼8-nm-wide region centered ∼4 nm in front of the SiO2/Si(100) interface. Annealing in H2 near 400 °C introduces hydrogen preferentially into the near-interfacial oxide region, where apparently large numbers of hydrogen trap sites are available. The amount of incorporated H exceeds the quantity necessary to H-passivate dangling Si bonds at the direct SiO2/Si(100) interface by more than one order of magnitude. The H uptake is strongly dependent on the H2-annealing temperature and is suppressed above 430 °C. This temperature marks the onset of hydrogen desorption from the near-interfacial oxide trap sites, contrasting the thermal stability of the native H, which prevails homogeneously distributed in the SiO2 films after oxidation at 900 °C. Hydrogen bound in the near-interface oxide region is not redistributed by the ion-beam irradiation, further emphasizing its different chemical interaction with the SiO2 network as opposed to the native oxide H. The mechanism of the irradiation-induced H redistribution and its possible relation to the degradation of electrically stressed electronic devices are discussed.

Hydrogen induced passivation of Si interfaces by Al2O3 films and SiO2/Al2O3 stacks

“…13,15 This is consistent with the high mobility of molecular hydrogen in SiO 2 in combination with the Si substrate acting as a diffusion barrier, 16 which promotes the diffusion of hydrogen along the interface and significantly increases its interaction with electronically active recombination centers, 16,17 and other defects present in this interfacial region. 13,[15][16][17] Overall, the data indicate that approximately 4% of the D present in the Al 2 O 3 films initially, diffused into the SiO 2 layer during annealing, which is approximately a quarter of the total amount of D that was removed from the Al 2 O 3 film. After a subsequent high temperature step ͑800°C, 30 s͒, a strong reduction in ͓D͔ in both the Al 2 O 3 and SiO 2 layers was observed.…”

Hydrogen-Induced Rupture of Strained Si─O Bonds in Amorphous Silicon Dioxide

“…A supply of hydrogen (H 2 or forming gas) during thermal treatment or irradiation may lead to formation of additional densities of intrinsic defects, as revealed by electron paramagnetic resonance (EPR) studies of defects in various forms of a-SiO 2 [15]. These densities may by far exceed the density of the same defects in identical a-SiO 2 films processed in the absence of hydrogen [16]. The additional defects are predominantly Si dangling bonds in the bulk of a-SiO 2 [17] or at the Si/SiO 2 interface [18,19], suggesting that Si-O bond rupture occurs in the initially defect-free a-SiO 2 network as well as at the Si/a-SiO 2 interface.…”

Model Systems in Heterogeneous Catalysis: Selectivity Studies at the Atomic Level

“…Tunneling was performed at the following conditions: U = 2.2 V, I = 0.07 nA (VO x /Al 2 O 3 ); U = 3.3 V, I = 0.12 nA (VO x /SiO 2 ). In both cases, particle number densities between *1.8 1.9 9 10 13 and 1.9 9 10 13 particles per cm -2 were determined [27] Top Catal (2008) 48:137-144 139 [41][42][43]. Experiments in this direction for the specific systems discussed above are under way.…”