CF
                  2
           production and loss mechanisms in fluorocarbon discharges: Fluorine-poor conditions and polymerization

Cunge, G.; Booth, Jean‐Paul

doi:10.1063/1.370296

Cited by 174 publications

(121 citation statements)

References 49 publications

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“…However, other researchers argue that there is no direct correlation between gas-phase CF 2 and fluorocarbon film growth. 5,18,42 In these simulations, CF 2 fragments are found to be the second most abundant and reactive species produced, regardless of the type of ion in the beam. In the case of C 3 F 5 + , over 50% of the deposited CF 2 fragments form covalent bonds with the PS chains, and in the case of CF 3 + , 61% of the deposited CF 2 ions form covalent bonds with the PS chains.…”

Section: Resultsmentioning

confidence: 84%

Molecular Dynamics Simulations of the Chemical Modification of Polystyrene through C_xF_y⁺Beam Deposition

Jang

Sinnott

2004

J. Phys. Chem. B

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The chemical modification of polystyrene through the deposition of a beam of polyatomic fluorocarbon ions (C 3 F 5 + and CF 3 + ) at experimental fluences is studied using classical molecular dynamics simulations with many-body empirical potentials. To facilitate these simulations, a new C-H-F potential is developed on the basis of the second-generation reactive empirical bond-order potential for hydrocarbons developed by Brenner. Lennard-Jones potentials are used to model long-range van der Waals interactions. The incident energy of the ion beam is 50 eV/ion, and it is deposited normal to the surface. The simulations illustrate the important differences in the chemical interactions of these polyatomic ions with the polystyrene. The CF 3 + ions are predicted to be more effective at fluorinating the polystyrene than C 3 F 5 + ions, and the dissociation of the C 3 F 5 + ions produce long-lived precursors to fluorocarbon thin film nucleation.

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Section: Resultsmentioning

confidence: 84%

Molecular Dynamics Simulations of the Chemical Modification of Polystyrene through C_xF_y⁺Beam Deposition

Jang

Sinnott

2004

J. Phys. Chem. B

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“…Under these conditions CF 2 has been proposed to act as a monomer in the formation of oligomeric species, which ultimately control polymer deposition. 6,7 Deposited fluorocarbon polymers provide control of etch selectivity, and of the profile and dimensions of the etched feature. The ability to accurately measure CF 2 densities in plasmas is a valuable tool in the effort to understand critical plasma etch mechanisms and extend the capabilities of etch technology.…”

Section: Introductionmentioning

confidence: 99%

“…Several methods are commonly used to measure densities of reactive intermediates in processing-type plasmas, including Laser-Induced Fluorescence Spectroscopy ͑LIF͒, [2][3][4][5][6][7][8] Infra-Red Laser Absorption Spectroscopy, 2 and Ultraviolet Absorption Spectroscopy ͑UVAS͒. Of these, broadband UVAS has been used by a number of groups to detect CF 2 .…”

Section: Introductionmentioning

confidence: 99%

Use of the ultraviolet absorption spectrum of CF2 to determine the spatially resolved absolute CF2 density, rotational temperature, and vibrational distribution in a plasma etching reactor

Bulcourt

Booth

Hudson

et al. 2004

The Journal of Chemical Physics

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Broadband ultraviolet absorption spectroscopy has been used to determine CF 2 densities in a plasma etch reactor used for industrial wafer processing, using the CF 2 Ã 1 B 1 ←X 1 A 1 absorption spectrum. Attempts to fit the experimental spectra using previously published Franck-Condon factors gave poor results, and values for the higher vibrational levels of the Ã state ͓(0,v 2 ,0), with v 2 ЈϾ6] from the ground state were missing; hence new values were calculated. These were computed for transitions between low-lying vibrational levels of CF 2 X 1 A 1 to vibrational levels of CF 2 Ã 1 B 1 (v 1 Ј ,v 2 Ј,0) up to high values of the vibrational quantum numbers using high level ab initio calculations combined with an anharmonic Franck Condon factor method. The Franck Condon factors were used to determine the absorption cross sections of CF 2 at selected wavelengths, which in turn were used to calculate number densities from the experimental spectra. Number densities of CF 2 have been determined in different regions of the plasma, including the center of the plasma and outside the plasma volume, and CF 2 rotational temperatures and vibrational energy distributions were estimated. For absorption spectra obtained outside the confined plasma volume, the CF 2 density was determined as (0.39Ϯ0.08)ϫ10 13 molecule cm Ϫ3 and the vibrational and rotational temperatures were determined as 303 and 350 K, respectively. In the center of the plasma reactor, the CF 2 density is estimated as (3.0Ϯ0.6)ϫ1013 molecules cm Ϫ3 with T rot Ϸ500 K. The fitted vibrational distribution in the CF 2 ground state corresponds to two Boltzmann distributions with T vib Ϸ300 and T vib Ϸ1000 K, indicating that CF 2 molecules are initially produced highly vibrationally excited, but are partially relaxed in the plasma by collision.

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“…Although the actual deposition process can be considerably more complicated involving, for example, production of high mass neutrals 9 and creation of activated sites, 7 we used this simpler mechanism to expedite the study. The mechanism con- sists of direct deposition of a fluorocarbon polymer by CF 2 and CF 3 radicals and the sputtering of the polymer by positive ions…”

Section: Reaction Mechanismmentioning

confidence: 99%

Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas

Babaeva

Kushner

2007

Journal of Applied Physics

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In plasma etching equipment for microelectronics fabrication, there is an engineered gap between the edge of the wafer and wafer terminating structures, such as focus rings. The intended purpose of these structures is to make the reactant fluxes uniform to the edge of the wafer and so prevent a larger than desired edge exclusion where useful products cannot be obtained. The wafer-focus ring gap ͑typicallyϽ 1 mm͒ is a mechanical requirement to allow for the motion of the wafer onto and off of the substrate. Plasma generated species can penetrate into this gap and under the beveled edge of the wafer, depositing films and possibly creating particles which produce defects. In this paper, we report on a computational investigation of capacitively coupled plasma reactors with a wafer-focus ring gap. The penetration of plasma generated species ͑i.e., ions and radicals͒ into the wafer-focus ring gap is discussed. We found that the penetration of plasma into the gap and under the wafer bevel increases as the size of the gap approaches and exceeds the Debye length in the vicinity of the gap. Deposition of, for example, polymer by neutral species inside the gap and under the wafer is less sensitive to the size of the gap due the inability of ions, which might otherwise sputter the film, to penetrate into the gap.

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CF 2 production and loss mechanisms in fluorocarbon discharges: Fluorine-poor conditions and polymerization

Cited by 174 publications

References 49 publications

Molecular Dynamics Simulations of the Chemical Modification of Polystyrene through C_xF_y⁺Beam Deposition

Molecular Dynamics Simulations of the Chemical Modification of Polystyrene through C_xF_y⁺Beam Deposition

Use of the ultraviolet absorption spectrum of CF2 to determine the spatially resolved absolute CF2 density, rotational temperature, and vibrational distribution in a plasma etching reactor

Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas

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CF 2 production and loss mechanisms in fluorocarbon discharges: Fluorine-poor conditions and polymerization

Cited by 174 publications

References 49 publications

Molecular Dynamics Simulations of the Chemical Modification of Polystyrene through CxFy+Beam Deposition

Molecular Dynamics Simulations of the Chemical Modification of Polystyrene through CxFy+Beam Deposition

Use of the ultraviolet absorption spectrum of CF2 to determine the spatially resolved absolute CF2 density, rotational temperature, and vibrational distribution in a plasma etching reactor

Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas

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Molecular Dynamics Simulations of the Chemical Modification of Polystyrene through C_xF_y⁺Beam Deposition

Molecular Dynamics Simulations of the Chemical Modification of Polystyrene through C_xF_y⁺Beam Deposition