Properties and applications of electron cyclotron plasma deposited SiOxNy films with graded refractive index profiles

et al. 2003

SiO x N y H z films were deposited from O 2 , N 2 , and SiH 4 gas mixtures at room temperature using the electron cyclotron resonance plasma method. The absolute concentrations of all the species present in the films ͑Si, O, N, and H͒ were measured with high precision by heavy-ion elastic recoil detection analysis. The composition of the films was controlled over the whole composition range by adjusting the precursor gases flow ratio during deposition. The relative incorporation of O and N is determined by the ratio Qϭ(O 2 )/(SiH 4 ) and the relative content of Si is determined by R ϭ͓(O 2 )ϩ(N 2 )͔/(SiH 4 ) where (SiH 4 ), (O 2 ), and (N 2 ) are the SiH 4 , O 2 , and N 2 gas flows, respectively. The optical properties ͑infrared absorption and refractive index͒ and the density of paramagnetic defects were analyzed in dependence on the film composition. Single-phase homogeneous films were obtained at low SiH 4 partial pressure during deposition; while those samples deposited at high SiH 4 partial pressure show evidence of separation of two phases. The refractive index was controlled over the whole range between silicon nitride and silicon oxide, with values slightly lower than in stoichiometric films due to the incorporation of H, which results in a lower density of the films. The most important paramagnetic defects detected in the films were the K center and the EЈ center. Defects related to N were also detected in some samples. The total density of defects in SiO x N y H z films was higher than in SiO 2 and lower than in silicon nitride films.

Section: A Control Of Compositionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Optical and structural properties of SiOxNyHz films deposited by electron cyclotron resonance and their correlation with composition

et al. 2003

“…1,2 One of the most extended techniques for the deposition of silicon oxynitride films ͑in the following SiO x N y H z ) at low temperatures is plasma enhanced chemical vapor deposition ͑PECVD͒, [3][4][5] with the remote PECVD 1,6,7 or electron cyclotron resonance ͑ECR-PECVD͒ [8][9][10][11] variants. While these techniques meet the low thermal budget requirement, the quality of the as-deposited dielectric films is not as good as that of thermally grown SiO 2 films.…”

Section: Introductionmentioning

confidence: 99%

Microstructural modifications induced by rapid thermal annealing in plasma deposited SiOxNyHz films

et al. 2003

The effect of rapid thermal annealing ͑RTA͒ processes on the structural properties of SiO x N y H z films was investigated. The samples were deposited by the electron cyclotron resonance plasma method, using SiH 4 , O 2 and N 2 as precursor gases. For SiO x N y H z films with composition close to that of SiO 2 , which have a very low H content, RTA induces thermal relaxation of the lattice and improvement of the structural order. For films of intermediate composition and of compositions close to SiN y H z , the main effect of RTA is the release of H at high temperatures (TϾ700°C). This H release is more significant in films containing both Si-H and N-H bonds, due to cooperative reactions between both kinds of bonds. In these films the degradation of structural order associated to H release prevails over thermal relaxation, while in those films with only N-H bonds, thermal relaxation predominates. For annealing temperatures in the 500-700°C range, the passivation of dangling bonds by the nonbonded H in the films and the transition from the paramagnetic state to the diamagnetic state of the K center result in a decrease of the density of paramagnetic defects. The H release observed at high annealing temperatures is accompanied by an increase of density of paramagnetic defects.

“…4 Finally, the control of the refractive index of SiO x N y H z between the values of SiN y H z and SiO 2 allows many interesting optical applications, such as graded index films or antireflection coatings. [5][6][7] Owing to the possibility to deposit films at low temperature, one of the most frequently used methods for the growth of SiO x N y H z films is the plasma enhanced chemical vapor deposition ͑PECVD͒, 3,8,9 with the remote PECVD 1,10,11 and the electron cyclotron resonance ͑ECR-PECVD͒ 5,12-14 variants. In these techniques precursor gases containing H, such as SiH 4 and NH 3 , are frequently used, so that H is incorporated into the films.…”

Section: Introductionmentioning

confidence: 99%

Influence of H on the composition and atomic concentrations of “N-rich” plasma deposited SiOxNyHz films

et al. 2004

The influence of H on the composition and atomic concentrations of Si, O, and N of plasma deposited SiOxNyHz films was investigated. The bonding scheme of H was analyzed by Fourier-transform infrared spectroscopy. The composition and absolute concentrations of all the species present in the SiOxNyHz, including H, was measured by heavy-ion elastic recoil detection analysis (HI–ERDA). Samples were deposited from SiH4, O2, and N2 gas mixtures, with different gas flow ratios in order to obtain compositions ranging from SiNyHz to SiO2. Those samples deposited at higher SiH4 partial pressures show both Si–H and N–H bonds, while those deposited at lower SiH4 partial pressures show N–H bonds only. The Si–H and N–H bond concentrations were found to be proportional to the N concentration. The concentration of H was evaluated from the Si–H and N–H stretching absorption bands and compared to the HI–ERDA results, finding good agreement between both measurements. The deviation from H-free stoichiometric SiOxNy composition due to the presence of N–H bonds results in an effective coordination number of N to produce Si–N bonds lower than 3. By fitting the experimental composition data to a theoretical model taking into account the influence of N–H bonds, the actual concentration of N–H bonds was obtained, making evident the presence of nonbonded H. The presence of Si–H and Si–Si bonds was found to partially compensate the effect of N–H bonds, from the point of view of the relative N and Si contents. Finally, the presence of N–H bonds results in a lower Si atom concentration with respect to the stoichiometric film, due to a replacement of Si atoms by H atoms. This decrease of the Si concentration is lower in those films containing Si–H and Si–Si bonds. A model was developed to calculate the Si, O, and N atom concentrations taking into account the influence of N–H, Si–H, and Si–Si bonds, and was found to be in perfect agreement with the experimental data measured by HI–ERDA.