Uniformity of radio frequency bias voltages along conducting surfaces in a plasma

Stevens, J.; Sowa, Mark J.; Cecchi, J. L.

doi:10.1116/1.579909

Cited by 25 publications

(17 citation statements)

References 3 publications

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“…This nonuniformity is generally associated with the reduced wavelength of electromagnetic waves that are established in these sources and the ratio of this wavelength to the chamber electrode dimensions as originally described by Stevens and coworkers. 1) Therefore, understanding how the plasma uniformity evolves is important as the wafer diameter increases from 300 to 450 mm.…”

Section: Introductionmentioning

confidence: 99%

Relationship between center-peaked plasma density profiles and harmonic electromagnetic waves in very high frequency capacitively coupled plasma reactors

Sawada¹,

Ventzek²,

Lane³

et al. 2014

Jpn. J. Appl. Phys.

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An understanding of the factors that control radial plasma uniformity in very high frequency (VHF) capacitively coupled plasma (CCP) sources is important for many plasma processes in semiconductor device manufacturing. Here, we report experimental measurements and high-resolution self-consistent numerical simulations that illustrate the plasma density profile and the higher harmonic wave content in two types of VHF-CCP testbench reactors. A distinct sharp center peak superimposed on a broad center peak in argon plasma was observed for driving frequencies of 60 and 106 MHz. Experimental measurements and numerical simulations of the electric field power spectrum reveal the presence of UHF waves when the electron density is over 5 ' 10 16 (#/m 3). The presence of UHF waves closely correlates with the occurrence of a distinct and sharp-center-peaked electron density. The numerical simulations show that specific frequency bands in the UHF spectrum are amplified in the plasma and lead to the evolution of the sharp-center-peaked electron density.

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Section: Introductionmentioning

confidence: 99%

Relationship between center-peaked plasma density profiles and harmonic electromagnetic waves in very high frequency capacitively coupled plasma reactors

Sawada¹,

Ventzek²,

Lane³

et al. 2014

Jpn. J. Appl. Phys.

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“…As τ i /τ increases, the width of the distribution decreases and, for very high τ i /τ , the IED becomes single peaked. However, for very high frequencies (very small τ ), the wavelength of the applied field may become comparable to the substrate dimension, resulting in undesirable effects, such as non-uniform voltage distribution on the substrate electrode [20]. Other investigators have controlled the IED by applying a bias on a separate electrode in contact with the plasma.…”

Section: Introductionmentioning

confidence: 99%

Control of ion energy distributions using a pulsed plasma with synchronous bias on a boundary electrode

Shin¹,

Zhu²,

Xu³

et al. 2011

Plasma Sources Sci. Technol.

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Ion energy distributions (IEDs) on a grounded substrate in a Faraday-shielded argon inductively coupled plasma were measured with a retarding field energy analyzer. A Langmuir probe was also used to measure space-and time-resolved plasma parameters. IEDs and plasma parameters were studied with continuous or pulsed positive dc bias voltage on a 'boundary electrode' in contact with the plasma. For continuous wave plasmas without applied bias, the IED exhibited a single broad peak at the plasma potential. Applying a continuous positive dc bias on the boundary electrode shifted the peak of the IED to higher energy. Application of a synchronous dc bias on the boundary electrode during the afterglow of a pulsed plasma resulted in a double-peaked IED. The mean energies of the two peaks, as well as the peak separation, were controlled by adjusting the applied dc bias and the discharge pressure. The full width at half maximum (FWHM) of the peak corresponding to the synchronous dc bias diminished with decreasing electron temperature. The FWHM was controlled by varying the time window in the afterglow during which dc bias was applied.

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“…The width of IED becomes significantly mass dependent for high bias frequencies, and as a result the IED remains bimodal for low mass ions often produced in processing plasmas. Moreover, at frequencies where the rf wavelength is comparable to the substrate dimensions, voltage nonuniformities across the substrate surface can be induced, 6 leading to process nonuniformities.…”

Section: Introductionmentioning

confidence: 99%

Accurate control of ion bombardment in remote plasmas using pulse-shaped biasing

Kudlacek

Rumphorst

Sanden

2009

Journal of Applied Physics

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This paper deals with a pulsed biasing technique employed to a downstream expanding thermal plasma. Two pulsed biasing approaches are presented: asymmetric rectangular pulses and modulated pulses with a linear voltage slope during the pulse, and their applicability is discussed on the basis of the intrinsic capacitance of the processed substrate-layer system. The substrate voltage and current waveforms are measured, and the relation to the obtained ion energy distributions is discussed. Accurate control of the ion bombardment is demonstrated for both aforementioned cases, and the cause of broadening of the peaks in the ion energy spectra is determined as well. Moreover, several methods to determine the modulated pulse duration, such that the sloping voltage exactly compensates for the drop of the substrate sheath potential due to charging, are presented and their accuracy is discussed.

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Uniformity of radio frequency bias voltages along conducting surfaces in a plasma

Cited by 25 publications

References 3 publications

Relationship between center-peaked plasma density profiles and harmonic electromagnetic waves in very high frequency capacitively coupled plasma reactors

Relationship between center-peaked plasma density profiles and harmonic electromagnetic waves in very high frequency capacitively coupled plasma reactors

Control of ion energy distributions using a pulsed plasma with synchronous bias on a boundary electrode

Accurate control of ion bombardment in remote plasmas using pulse-shaped biasing

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