Analysis of the oxygen contamination present in SiN<i>x</i> films deposited by electron cyclotron resonance

García, Silvia; Martin, Jarad; Fernández, M.; Mártil, I.; González-Dı́az, G.

doi:10.1116/1.579835

Cited by 15 publications

(4 citation statements)

References 8 publications

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“…On the other hand, had it been due to a very low (<3%) oxygen content remaining in the bulk of the film, it would have shifted to a lower frequency, as observed by Galeener and Lucovsky [33] and Lucovsky and Tsu [34]. Therefore, contrary to Garcia et al [35], we do not think that a very slight amount of incorporation of oxygen into the films can be related to the very strong absorption at 1070 cm −1 observed when the angular incidence increased. So the vibration mode at around 1040-1070 cm −1 observed by specular measurement can probably be ascribed to a Si-N mode with a β-like character [27] which may be related to a dimidelike structure of amorphous silicon nitride and then the peaks at 840 and 1070 cm −1 indicate short-range vibration modes: a parallel 'LO mode' (at 1050-1070 cm −1 ) and a parallel and perpendicular 'TO mode' (at 840 cm −1 ).…”

Section: The Possible Presence Of a Siomentioning

confidence: 83%

Structural properties of N-rich a-Si - N:H films with a low electron-trapping rate

Dupont

Caquineau

Despax

et al. 1997

J. Phys. D: Appl. Phys.

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Hydrogenated amorphous silicon nitride films with a high nitrogen content were prepared by RF plasma-enhanced chemical vapour deposition from a mixture of and at . The influence of the main operating variables on the quality of the material was examined. Characteristics and properties of the films were investigated using optical absorption, infrared spectroscopy, x-ray photo-electron spectroscopy and capacitance - voltage measurements. From infrared transmission and reflection measurements, it was found most of the IR peaks obtained by direct transmission in the range , which have often been mentioned in the literature, are caused not by absorption but rather by a strong reflection due to the Reststrahlen effect. IR studies carried out with polarized light revealed an anisotropic beam - sample interaction probably due to short-range phonon vibration modes: a parallel `LO mode' (), a parallel and perpendicular `TO mode' (). For sufficiently high values of the N/Si ratio, a decreasing percentage of or an increasing RF power leads to a decrease in the trapped charge density which should be related simultaneously to an increase in the N/Si ratio and a decrease in the Si - H bond density in the deposited films. It is suggested that, under our experimental conditions, the charged particle bombardment due to the RF discharge does not play an important role in the charge trapping and that the trapping rate seems to be controlled only by the nature of the traps.

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Section: The Possible Presence Of a Siomentioning

confidence: 83%

Structural properties of N-rich a-Si - N:H films with a low electron-trapping rate

Dupont

Caquineau

Despax

et al. 1997

J. Phys. D: Appl. Phys.

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“…4,5 Films with different ͓N͔/͓Si͔ ratios and, some of them, with low oxygen content are analyzed. As we have already reported, 5 sputtering of the quartz liner inserted into the plasma source by the energetic nitrogen ions at microwave powers higher than 150 W and N 2 /SiH 4 ratios higher than 6 results in oxygen incorporation into the SiN x :H films. This incorporation is unintentional but reproducible, as the conditions of the sputtering of the liner are determined by the microwave power and N 2 /SiH 4 ratio used.…”

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confidence: 99%

Role of oxygen on the dangling bond configuration of low oxygen content SiNx:H films deposited at room temperature

García

Bravo

Fernández

et al. 1995

Applied Physics Letters

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SiNx:H films with a wide composition range and, some of them, with low oxygen content are deposited at room temperature. The defects observed in the films are attributed to Si-dangling bonds, with a structure depending on film composition. For the N-rich films they are of the form ⋅Si≡(N3), whereas for the films with similar [N]/[Si] ratio but containing oxygen, the predominant defect is proposed to be ⋅Si≡(Si2O), despite of the high N content and the low O content of these films. The spin density of the films has been related to the bonds that hydrogen establishes (either Si–H or N–H), with the maximum value corresponding to the minimum hydrogen content. Both maximum and minimum values, respectively, are obtained at the silicon percolation limit of the Si–Si bonds into the SiNx:H network, x∼1.10.

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“…17 However, the reduction of the oxygen contamination, by modifying the deposition pressure and improving the dissociation of nitrogen, was not investigated in detail.…”

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confidence: 99%

“…Several studies have shown the presence of oxygen contamination in ECR nitrides 3,10,[12][13][14][15][16][17] and the attempts to minimize the oxygen content, by reducing the sputtering process at low microwave power. 17 However, the reduction of the oxygen contamination, by modifying the deposition pressure and improving the dissociation of nitrogen, was not investigated in detail.…”

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confidence: 99%

Low Hydrogen Content Silicon Nitride Films Deposited at Room Temperature with an ECR Plasma Source

Isai

Holleman

Wallinga

et al. 2004

J. Electrochem. Soc.

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Silicon nitride layers with very low hydrogen content ͑less than 1 atomic percent͒ were deposited at near room temperature, from N 2 and SiH 4 , with a multipolar electron cyclotron resonance plasma. The influences of pressure and nitrogen flow rate on physical and electrical properties were studied in order to minimize the hydrogen and oxygen content in the layers. The optimized layers were characterized by a refractive index of 1.98, a dielectric constant of 7.2, and Si/N ratio values of 0.78. The layers exhibited very good dielectric strength, which was confirmed by large breakdown fields of 12 MV/cm, very high resistivities of 10 16 ⍀ cm, and maximum charges to breakdown values of 90 C/cm 2 . Increasing the deposition pressure and decreasing the N 2 flow improved the SiN/Si interface, due to increased oxygen incorporation. The dominant conduction mechanism in the layers was the PooleFrenkel effect. The critical field and the trap energy had similar dependencies on deposition pressure. Fowler-Nordheim tunneling occurred at high gate biases, for the layers deposited at the highest pressure of about 22 mTorr.Decreasing the temperature at which dielectrics are deposited without causing any deterioration of the dielectrics properties has become a priority in the thin film research area. Low-temperature deposition is needed, for example, for producing thin film transistors ͑TFTs͒ on ultrathin, plastic substrates that can withstand temperatures of up to 100°C. 1,2 Such flexible substrates may replace the glass screens in future displays due to several advantages, e.g., lower cost, lower power consumption, lower weight, and better flexibility.The standard gate dielectric nowadays for amorphous TFTs is silicon nitride (Si 3 N 4 ) deposited by radio-frequency plasma enhanced chemical vapor deposition ͑rf-PECVD͒. However, the processing temperature of rf-PECVD is 300°C, which is too high for flexible displays. Furthermore, these layers exhibit high hydrogen contents of up to 20 atomic percent ͑atom %͒ and low dielectric strength. In contrast, electron cyclotron resonance ͑ECR͒ PECVD Si 3 N 4 layers with good material and electrical properties have been successfully deposited in recent years, at much lower temperatures. 3-5 ECR plasma operates at a low pressure, has a low electron and ion energy, and a high degree of ionization. 6,7 Because of these soft and dense characteristics of the ECR plasma, 8 the deposition temperature can be lowered, while reducing the concentration of unwanted hydrogen bonds through ion bombardment.Although very good quality Si 3 N 4 films with good interfaces and high breakdown fields have been deposited at room temperature using divergent ECR plasma sources and distributed ECR plasma sources, 3,9,10 the level of hydrogen contamination could not be reduced below 5 atom %.A less known ECR discharge configuration, called multipolar ECR 11 has been shown to reduce the hydrogen content even more. This new technique has certain advantages such as a magnetic field parallel to the substrate, which mi...

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Analysis of the oxygen contamination present in SiNx films deposited by electron cyclotron resonance

Cited by 15 publications

References 8 publications

Structural properties of N-rich a-Si - N:H films with a low electron-trapping rate

Structural properties of N-rich a-Si - N:H films with a low electron-trapping rate

Role of oxygen on the dangling bond configuration of low oxygen content SiNx:H films deposited at room temperature

Low Hydrogen Content Silicon Nitride Films Deposited at Room Temperature with an ECR Plasma Source

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