Effects of Excited Species in Electron Cyclotron Resonance Plasma on SiN Film Resistivity

Saito, Kazutoshi; Chiba, Natsuyo; Fukuda, Takuya; Suzuki, Keiji; Ohue, Michio

doi:10.1143/jjap.31.1102

Cited by 14 publications

(4 citation statements)

References 7 publications

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“…1. 12,20 The nitrogen flow rate has no significant influence on the deposition rate ͑Fig. 2͒, despite the fact that the silane partial pressure becomes nearly three times smaller ͑from 0.04 to 0.012 mTorr͒ at high N 2 flows.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…It was found that the growth rate at increased microwave power, as shown in Table 1(a), remained constant. This is due to the silane that is already entirely consumed at 1 kW microwave power [11,12]. A greater ionization and dissociation of the oxygen would however explain the slight decrease in the refractive index with increased microwave power.…”

Section: Properties Of the Filmsmentioning

confidence: 99%

Deposition of dielectrics using a matrix distributed electron cyclotron resonance plasma enhanced chemical vapor deposition system

et al. 2007

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“…Electron cyclotron resonance plasma enhanced chemical vapor deposition ͑ECR-CVD͒ of thin films has distinct advantages over conventional rf plasma processes, including low process pressures that enable a good step coverage, low deposition temperatures, reduced process contamination ͑due to electrodeless coupling of plasma͒, and potentially low damage deposition. [1][2][3][4] ECR plasmas are known to produce a high degree of ionization, and the electron temperature T e is relatively high ͑can exceed 10 eV͒, depending strongly on discharge parameters, especially gas pressure. [5][6][7] At small pressures, a high degree of dissociation of reagents ͑N 2 and SiH 4 ) can be achieved not only in the ECR chamber, but also in the downstream region.…”

Section: Introductionmentioning

confidence: 99%

Deposition of silicon nitride by low-pressure electron cyclotron resonance plasma enhanced chemical vapor deposition in N2/Ar/SiH4

Moshkalyov¹

1997

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Plasma deposition of silicon nitride on silicon substrates in a microwave electron cyclotron resonance N 2 /Ar/SiH 4 discharge was studied as a function of gas pressure ͑1-5 mTorr͒, gas composition, and discharge power ͑250-1000 W͒. The dependencies of deposition parameters on discharge characteristics obtained at 1 mTorr appear to be essentially different from those at higher pressures. Optical emission spectroscopy was used for plasma characterization. A high degree of ionization and dissociation of gas molecules was observed under present plasma conditions. It is shown that the contribution of ionized species to film deposition is comparable with that of neutral ones under high power and low pressure conditions. The best quality of films was obtained at a moderate rather than the highest available dissociation degree of silane.

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Effects of Excited Species in Electron Cyclotron Resonance Plasma on SiN Film Resistivity

Cited by 14 publications

References 7 publications

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

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

Deposition of dielectrics using a matrix distributed electron cyclotron resonance plasma enhanced chemical vapor deposition system

Deposition of silicon nitride by low-pressure electron cyclotron resonance plasma enhanced chemical vapor deposition in N2/Ar/SiH4

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