Coupling of a vacuum-ultraviolet-radiation source to a processing system

Chatterton, J. D.; Upadhyaya, G. S.; Shohet, J. L.; Lauer, J. L.; Bathke, R. D.; Kukkady, K.

doi:10.1063/1.2335688

Cited by 8 publications

(10 citation statements)

References 5 publications

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“…This is also verified by the fact that as the photon energies increases from the UV range to the VUV range, the penetration depth of the photons becomes smaller. 21 Furthermore, in order to verify the plasma ion and photon bombardment penetration depths, a capillary-array window 22 was used to cover a portion of the dielectric sample. The capillary-array window filters out the ion flux while allowing photons to pass through to the dielectric.…”

Section: H108mentioning

confidence: 99%

Changes to Charge and Defects in Dielectrics from Ion and Photon Fluences during Plasma Exposure

Nishi

Shohet

2011

Electrochem. Solid-State Lett.

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A methodology is introduced to investigate the effects of ion and photon fluences on dielectrics during plasma exposure. Ion and photon fluences were separated using a capillary-array window. The fluences can be varied separately by varying the plasma parameters. Most of the charge accumulation came from the ion fluence, while the photon fluence introduced most of the defect-state modifications. It was further shown that during plasma exposure, UV photons can penetrate through the dielectric layer and cause modifications of the defect states. Based on the results, optimized conditions were found to minimize both the charge accumulation and the defect-state formation during plasma exposure.Plasma-processing-induced damage has been an important issue in manufacturing microelectronic devices. 1 Damage includes dielectric charging, 2 defect-state formation, 3,4 chemical and physical changes, 5,6 and mechanical degradation. 7 This processing-induced damage can be from ions, photons, and radicals striking the dielectric. 8,9 Among these damage sources, ion bombardment has been believed to be the greatest for changing the properties of dielectrics. 8 However, such ion-induced damage may only happen within an ion penetration depth. 10 Vacuum ultraviolet ͑VUV͒-modified dielectric layers were typically shown to be deeper than the ion-modified layer. 11 Based on this, it is our contention that, within the dielectric, beyond the ion penetration depth, photons are responsible for the damage in this region, while on the surface, the damage is primarily caused by ions. Here, the two sources of damage generated during plasma processing will be considered to determine the effects of ion and photon fluences on the damage. They are charge accumulation and defect-state formation. This article establishes the roles of photons and ions in charge accumulation and defect-state formation in dielectric materials.In order to determine this, electron-spin resonance ͑ESR͒ spectroscopy measurements were made to detect the modifications of the interfacial defect states and surface potential measurements with a Kelvin probe were used to detect the charge accumulation. Previously, VUV and UV exposures from synchrotron radiation and HgAr lamp have been shown to be responsible for the interlayer defect-state modifications in the dielectrics. 12 As a test sample, we used atomic-layer-deposited 20-nm-thick HfO 2 on ͑100͒Si. Note that the dielectric sample is ultrathin which guarantees a modification of the interfacial defects. The resistivity of silicon substrate is 4000 ⍀ cm which is needed to obtain effective ESR measurements. 13 An electron cyclotron resonance plasma system 9 was utilized to provide the plasma exposure of the dielectric films. Argon plasma was used to minimize the creation of free radicals, 14 so that the ion and photon bombardments were the primary sources of potential damage.To vary the ion and photon fluences, pressure and microwave power were scanned between ranges of 5 and 30 mTorr and 100 and 400 W, respectively. The pressu...

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Section: H108mentioning

confidence: 99%

Changes to Charge and Defects in Dielectrics from Ion and Photon Fluences during Plasma Exposure

Nishi

Shohet

2011

Electrochem. Solid-State Lett.

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“…33 The argon plasma conditions used for these exposures were previously found to emit radiation primarily in the VUV range, with dominant emission peaks at 11.6 and 11.8 eV. 34 Each of the VUV-exposed samples was exposed to a photon fluence of approximately 5 Â 10 15 photons/cm 2 . Figure 1 shows a typical leakage-current profile under stress voltage as a function of time on a VUV-irradiated (i.e., capillary-array window covered) sample.…”

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Time-dependent dielectric breakdown of plasma-exposed porous organosilicate glass

Nichols

Sinha

Wiltbank

et al. 2012

Applied Physics Letters

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“…Each sample was attached to the wafer chuck with conductive tape. One of the samples was covered with the capillary-array window to keep particles from travelling to the sample while allowing VUV photons to pass through [29]. The uncovered area of the wafer chuck was covered with Kapton tape such that no plasma-wafer-chuck contact took place during exposure.…”

Section: Methodsmentioning

confidence: 99%

“…A capillary-array window was used to separate the plasma radiation from charged-particle bombardment. The capillary-array window shields out most of the particles while allowing the plasma radiation [29]. After simultaneous plasma exposure to both uncovered and covered dielectrics, we examined the changes in the electrical properties.…”

Section: Introductionmentioning

confidence: 99%

Damage to low-k porous organosilicate glass from vacuum-ultraviolet irradiation

Shohet

Sinha

et al. 2011

SPIE Proceedings

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We investigate the effects of VUV and UV radiation on a number of low-k dielectric films. Two different systems were used to investigate the effects: (1) a synchrotron radiation system as a pure VUV radiation source, and (2) an electron-cyclotron resonance (ECR) plasma system as a plasma source (VUV plus ions). Using the synchrotron-radiation system, we find VUV causes trapped charge accumulation within low-k dielectric films by electron depopulation from the defect states. For organosilicate glass (SiCOH) , the defect states were located 1 eV above the valence band of the dielectric. A model was developed to calculate in-situ charge accumulation. Trapped charges can be depleted with UV-lamp exposure. We examined the use of different energy barriers between layers so that less charge will be accumulated. Using the ECR plasma system, the photon effects can be separated from charged particle effects using a capillary-array window to cover the low-k dielectric films so that only photons from plasma can reach the dielectric. Photon fluence from the plasma can be predicted with a model and measured with a VUV monochromator. Photons from the plasma were shown to be responsible for trapped-charge accumulation within the dielectric, while it was found that ions bombardment results primarily on charge on the surface of the dielectrics.

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Coupling of a vacuum-ultraviolet-radiation source to a processing system

Cited by 8 publications

References 5 publications

Changes to Charge and Defects in Dielectrics from Ion and Photon Fluences during Plasma Exposure

Changes to Charge and Defects in Dielectrics from Ion and Photon Fluences during Plasma Exposure

Time-dependent dielectric breakdown of plasma-exposed porous organosilicate glass

Damage to low-k porous organosilicate glass from vacuum-ultraviolet irradiation

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