The kinetics of lattice distortion introduction and lattice relaxation at the surface of thermally-oxidized 4H-SiC (0001)

Abstract

The kinetics of lattice distortion introduction and lattice relaxation at the surface of thermally-oxidized 4H-SiC (0001) were investigated. Our results suggested that lattice distortion introduction and lattice relaxation seem to follow zeroth and second order rate laws, respectively. The obtained activation energy of ∼3.9 eV for lattice distortion introduction and ∼1 eV for its relaxation indicate that the lattice distortion is determined by a bond rearrangement or movement process with a relatively low activation energy. Furthermore, the formation of byproducts which remain at the surface region of 4H-SiC was predicted to be a possible origin of the significant lattice distortion.

Similarity and difference of the impact of ion implantation and thermal oxidation on the lattice structure of 4H-SiC (0001) surface

“…Different from Ar-implanted samples, the lattice relaxation of thermally-oxidized sample seems to follow second order rate law, since we found that inverse of D (D −1 ) was linearly correlated to annealing time. 10) Figure 4(c) shows the annealing temperature dependence of k relaxation of thermally-oxidized 4H-SiC samples, where the activation energy was estimated to be 1 ± 0.01 eV, which is larger than the one for Ar-implanted samples. Considering the observed activation energy and the fact that the invasion of oxygen into the surface region of thermally-oxidized 4H-SiC was physically detected using thermal desorption spectroscopy, 10) it would be reasonable to be attributed to the movement of invading oxygen into 4H-SiC lattice to form Si-O-C structure and/or formation of CO to be emitted out, [27][28][29] as already indicated in our previous work.…”

“…7) In our previous work, we have already reported thermal oxidation-induced lattice distortion locally at the surface region of 4H-SiC caused by the formation of the SiO 2 /4H-SiC interface. 8,9) The byproducts that remain at the 4H-SiC surface after oxidation was considered as one of the possible origins based on the detailed study of the kinetics of lattice distortion and relaxation processes, 10) even though the mechanisms of introduction of such significant distortion have not yet been clarified.…”

“…Since both ion implantation and thermal oxidation induce 4H-SiC surface modification, study on the similarity and difference of the impact of both processes on the lattice structure of the 4H-SiC surface should provide an important information for the consideration of mechanism of thermal oxidation-induced anomalous lattice distortion on the surface regions of 4H-SiC. Furthermore, considering the existence of O-related byproducts 10) and/or interstitial atoms 5,6) in the surface region of 4H-SiC after thermal oxidation, the impact of oxygen presence on the lattice of 4H-SiC surface through the comparison between the implantations of O-ion and an inert ion, for example, an Ar-ion, may also be informative. In this work, we investigated the impact of implantations of those ions on the lattice structure of 4H-SiC (0001) surface to be compared with that induced by thermal oxidation observed in our previous studies, [8][9][10] directly from the changes of the interspacing of lattice planes perpendicular to the wafer surface, based on the in-plane X-ray diffractometry (XRD) analysis.…”

“…Furthermore, considering the existence of O-related byproducts 10) and/or interstitial atoms 5,6) in the surface region of 4H-SiC after thermal oxidation, the impact of oxygen presence on the lattice of 4H-SiC surface through the comparison between the implantations of O-ion and an inert ion, for example, an Ar-ion, may also be informative. In this work, we investigated the impact of implantations of those ions on the lattice structure of 4H-SiC (0001) surface to be compared with that induced by thermal oxidation observed in our previous studies, [8][9][10] directly from the changes of the interspacing of lattice planes perpendicular to the wafer surface, based on the in-plane X-ray diffractometry (XRD) analysis. The possible mechanism of the lattice distortion induced by those processes were then investigated based on the consideration of the kinetics of lattice relaxation induced by Ar annealing at various temperatures and durations.…”

“…This result clearly indicates the important role of oxygen inclusion in SiC for the lattice distortion, which seems quite consistent with the fact that thermal oxidation induces anomalous lattice distortion at SiC surface. [8][9][10] The kinetics of lattice relaxation of thermally-oxidized and implanted 4H-SiC were then clarified to obtain some hints to investigate the possible difference of the origins and/or mechanisms of distortion introduction between those samples. Figure 3 shows the lattice relaxation of O-implanted (at the dose of 1.0 × 10 15 atoms cm −2 ), Ar-implanted (at the same dose as O), and thermally-oxidized 4H-SiC as a function of Ar annealing time performed at 1150, 1300, and 1400 °C.…”