Effect of vacuum ultraviolet and ultraviolet irradiation on mobile charges in the bandgap of low-k-porous organosilicate dielectrics

Sinha, H.; Nichols, M. T.; Sehgal, Akshey; Tomoyasu, M.; Russell, N. M.; Antonelli, G. A.; Nishi, Yoshio; Shohet, J. L.

doi:10.1116/1.3520433

Cited by 11 publications

(12 citation statements)

References 14 publications

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“…12,13 Specific electrical reliability concerns for low-and high-k dielectrics include line-line interconnect 14,15 and gate dielectric leakage, 16,17 dielectric breakdown (V bd ), [18][19][20] time-dependent dielectric breakdown, [21][22][23][24] stress-induced leakage currents, 25,26 bias temperature instabilities, 27,28 charge trapping, [29][30][31][32] and a host of other charge-related buildup phenomena. 33,34 Despite the wide range of reliability concerns, a key ingredient in the models for all of these phenomena is some type of "defect" or "trap" in the dielectric material. [35][36][37][38][39][40][41][42][43][44][45] Tremendous resources and effort have been devoted to detecting and identifying the chemical identity and physical structure of such defects and traps in SiO 2 , [46][47][48] and they continue to be the subject of significant research interest.…”

Section: Introductionmentioning

confidence: 99%

Detection of surface electronic defect states in low and high-k dielectrics using reflection electron energy loss spectroscopy

French

King

2013

J. Mater. Res.

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The continuation of Moore's law requires new materials at both extremes of the dielectric permittivity spectrum and an increased understanding of the fundamental mechanisms limiting their electrical reliability. To address the latter, reflection electron energy loss spectroscopy has been utilized to measure the band gap of various oxide-based low and high dielectric constant (k) materials of interest to the semiconductor industry. In situ Ar 1 sputtering has been additionally utilized to simulate process-induced defect states that are believed to contribute to electrical leakage, time-dependent dielectric breakdown, charge trapping, and other fixed-charge reliability issues in nano-electronic devices. It is observed that Ar 1 sputtering predominantly generates surface oxygen vacancy defects in the upper portion of the band gap for both low and high-k dielectric materials. These results are in agreement with numerous theoretical investigations of defects in low and high-k dielectric materials and models for mechanisms that limit their reliability.

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Section: Introductionmentioning

confidence: 99%

Detection of surface electronic defect states in low and high-k dielectrics using reflection electron energy loss spectroscopy

French

King

2013

J. Mater. Res.

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“…1,7 For low-k materials, it has been additionally shown that electrical traps and defects can be created by downstream porogen removal and plasma etching processes that expose the low-k material to intense UV-VUV radiation, energetic ions, and chemically active radicals. [17][18][19][20][21][22][23] Further studies have shown a direct correlation between trap/defect densities, leakage currents and TDDB failures. 18,24 Unfortunately, the current understanding of the chemical identity, structure, and energy level of electrical traps and defects in low-k materials is still limited.…”

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confidence: 97%

Detection of defect states in low-k dielectrics using reflection electron energy loss spectroscopy

King

French

Mays

2013

Journal of Applied Physics

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A reverse Monte Carlo method for deriving optical constants of solids from reflection electron energy-loss spectroscopy spectra Reflection electron energy loss spectroscopy (REELS) has been utilized to measure the band gap (E g ) and energy position of sub-gap defect states for both non-porous and porous low dielectric constant (low-k) materials. We find the surface band gap for non-porous k ¼ 2.8-3.3 a-SiOC:H dielectrics to be ffi 8.2 eV and consistent with that measured for a-SiO 2 (E g ¼ 8.8 eV). Ar þ sputtering of the non-porous low-k materials was found to create sub-gap defect states at % 5.0 and 7.2 eV within the band gap. Based on comparisons to observations of similar defect states in crystalline and amorphous SiO 2 , we attribute these sub-gap defect states to surface oxygen vacancy centers. REELS measurements on a porous low-k a-SiOC:H dielectric with k ¼ 2.3 showed a slightly smaller band gap (E g ¼ 7.8 eV) and a broad distribution of defects states ranging from 2 to 6 eV. These defect states are attributed to a combination of both oxygen vacancy defects created by the UV curing process and carbon residues left in the film by incomplete removal of the sacrificial porogen. Plasma etching and ashing of the porous low-k dielectric were observed to remove the broad defect states attributed to carbon residues, but the oxygen vacancy defects remained.

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“…[19][20][21] When a VUV photon is incident on a dielectric surface, there are several processes that can occur depending on the thickness of the dielectric layer and the energy of the VUV photon. 22 If there is an electric field within the dielectric layer, the free electrons and holes can move in response to the electric field until they become trapped, recombine, or leave the dielectric. The location of the electron-hole pairs that are generated within the dielectric depends on the penetration depth of the VUV photons ($10 nm for SiO 2 ).…”

Section: Introductionmentioning

confidence: 99%

Plasma and vacuum ultraviolet induced charging of SiO2 and HfO2 patterned structures

Lauer

Upadhyaya

Sinha

et al. 2011

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Characterization of atomic layer deposition HfO2, Al2O3, and plasma-enhanced chemical vapor deposition Si3N4 as metal-insulator-metal capacitor dielectric for GaAs HBT technology J. Vac. Sci. Technol. A 31, 01A134 (2013); 10.1116/1.4769207 In situ study of the atomic layer deposition of HfO2 on Si J. Vac. Sci. Technol. A 30, 01A143 (2012); 10.1116/1.3668080Effect of thermal annealing on charge exchange between oxygen interstitial defects within HfO 2 and oxygendeficient silicon centers within the SiO 2 / Si interface Appl.The authors compare the effects of plasma charging and vacuum ultraviolet (VUV) irradiation on oxidized patterned Si structures with and without atomic-layer-deposited HfO 2 . It was found that, unlike planar oxidized Si wafers, oxidized patterned Si wafers charge up significantly after exposure in an electron-cyclotron resonance plasma. The charging is dependent on the aspect ratio of the patterned structures. This is attributed to electron and/or ion shading during plasma exposure. The addition of a 10 nm thick HfO 2 layer deposited on top of the oxidized silicon structures increases the photoemission yield during VUV irradiation, resulting in more trapped positive charge compared to patterns without the HfO 2 dielectric.

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Effect of vacuum ultraviolet and ultraviolet irradiation on mobile charges in the bandgap of low-k-porous organosilicate dielectrics

Cited by 11 publications

References 14 publications

Detection of surface electronic defect states in low and high-k dielectrics using reflection electron energy loss spectroscopy

Detection of surface electronic defect states in low and high-k dielectrics using reflection electron energy loss spectroscopy

Detection of defect states in low-k dielectrics using reflection electron energy loss spectroscopy

Plasma and vacuum ultraviolet induced charging of SiO2 and HfO2 patterned structures

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