Electrode impedance effect in dual-frequency capacitively coupled plasma

Yamazawa, Yohei

doi:10.1088/0963-0252/24/3/034015

Cited by 20 publications

(11 citation statements)

References 37 publications

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“…Electrical discontinuity leads to plasma sheath bending. The ion trajectory in the child Langmuir region is perpendicular to the plasma sheath, and the bended sheath causes the ion injection direction to yield an undesired etch pattern at the edge [18]. The materials for the edge ring (e.g., quartz, silicon, and silicon carbide) are etch-resistive, and the etch rate of the edge ring is much retarded compared with the materials to be etched on the wafer.…”

Section: Rf Power In the Plasma Systemmentioning

confidence: 99%

Dual-Frequency RF Impedance Matching Circuits for Semiconductor Plasma Etch Equipment

Lee

Hong

2021

Electronics

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The change in electrode impedance of semiconductor equipment due to repetitive processes is a major issue that creates process drift. In the current plasma etch chamber with a dual-frequency power system, the high-powered radio frequency (RF) source contributes to the enhancement of the plasma density, and the low-frequency bias power at the bottom electrode is adopted to enhance the injected ion energy in the plasma. The impedance control of the top electrode in dual-frequency capacity coupled plasma limits the impedance matching capability of the RF matching system because it only considers the high-frequency RF source. To control the precise impedance in dual-frequency semiconductor equipment, independent impedance control is required for each frequency. In this study, the impedance corresponding to a specific frequency was independently controlled using L (inductor) and C (capacitor). A 60 MHz stop filter and VVC were used to control 2 MHz impedance at a specific point, and a 2 MHz stop filter and VVC were used to control 60 MHz impedance. In the case of 2 MHz impedance control, the 2 MHz impedance changed from 10.9−j893 to 0.3−j62 and the 60 MHz impedance did not change. When controlling the 60 MHz impedance, the 60 MHz impedance changed from 0.33 + j26.53 to 0.2 + j190 and the 2 MHz impedance did not change. The designed LC circuits cover the impedance of 60 and 2 MHz separately and are verified by the change in the capacitance of the vacuum variable capacitors implemented in the RF impedance matching system.

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Section: Rf Power In the Plasma Systemmentioning

confidence: 99%

Dual-Frequency RF Impedance Matching Circuits for Semiconductor Plasma Etch Equipment

Lee

Hong

2021

Electronics

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“…which includes the change of all harmonics in the current k ∈ [1, K] due to the mth probing harmonic in the voltage at frequency mω. The influence of the DC current component neglected in equation ( 13) is immaterial, as any contribution is integrated out in equation (10). Again, equation ( 13) is not defined for DC.…”

Section: Harmonic Balance Algorithmmentioning

confidence: 99%

“…The voltage waveform at the driven electrodes and the current flowing through the plasma discharge depend decisively on the electrical properties of the network elements, which the plasma interacts with. Plasmas operated at radio frequency and low pressure also show a nonlinear behavior, making the interaction not easily predictable [3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

A generic method for equipping arbitrary rf discharge simulation frameworks with external lumped element circuits

Schmidt

Trieschmann

Gergs

et al. 2019

Journal of Applied Physics

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External electric circuits attached to radio-frequency plasma discharges are essential for the power transfer into the discharge and are, therefore, a key element for plasma operation. Many plasma simulations, however, simplify or even neglect the external network. This is because a solution of the circuit's auxiliary differential equations following Kirchhoff's laws is required, which can become a tedious task especially for large circuits. This work proposes a method, which allows to include electric circuits in any desired radio-frequency plasma simulation. Conceptually, arbitrarily complex external networks may be incorporated in the form of a simple netlist. The suggested approach is based on the harmonic balance concept, which splits the whole system into the nonlinear plasma and the linear circuit contribution. A mathematical formulation of the influence of the applied voltage on the current for each specific harmonic is required and proposed.It is demonstrated that this method is applicable for both simple global plasma models as well as more complex spatially resolved Particle-in-Cell simulations.

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“…Furthermore, design of the matching networks is one of the key issues in some new CCP configurations, to achieve better control over specific plasma characteristics. Recent efforts include dual-frequency CCP [9,[13][14][15][16], pulsed CCP [17,18] and CCP driven by tailored voltage waveforms (TVWs) [19][20][21][22][23] used in etching at low pressure, as well as CCP at atmosphere [24], or even using CCP as a tunable impedance element for RF systems [25].…”

Section: Introductionmentioning

confidence: 99%

Self-consistent simulation of the impedance matching network for single frequency capacitively coupled plasma

Gao¹,

Yu²,

Wu³

et al. 2022

J. Phys. D: Appl. Phys.

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Matching networks are of vital importance for capacitively coupled plasmas to maximize the power transferred to the plasma discharge. The nonlinear interaction between the external circuit and plasma has to be considered to design suitable matching networks. To study the effect of the matching circuit, we coupled PIC/MC model and nonlinear circuit equations based on Kirchhoff’s laws, in a fully nonlinear and self-consistent way. The single-frequency capacitively coupled discharge with ”L”-Type matching networks are simulated. Fully self-consistently results of circuit and plasma parameters are presented and then power absorbed by the plasma and efficiency are calculated. With the tune of the matching network, the efficiency can reach 28.7 %, leading to higher potential as well as higher electron density at fixed source voltage. Besides, only very small components of the third harmonics are found in the plasma voltage and current while surface charge densities have multiple harmonics on account of the strong plasma nonlinearity. Finally, the effects of matching capacitors on discharge are analyzed, results show that smaller Cm1 and Cm2 of 500 pF to 1000 pF may be a proper choice for better matching, resulting in higher voltage across the CCP, and thus higher electron density and power absorption efficiency are obtained.

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Electrode impedance effect in dual-frequency capacitively coupled plasma

Cited by 20 publications

References 37 publications

Dual-Frequency RF Impedance Matching Circuits for Semiconductor Plasma Etch Equipment

Dual-Frequency RF Impedance Matching Circuits for Semiconductor Plasma Etch Equipment

A generic method for equipping arbitrary rf discharge simulation frameworks with external lumped element circuits

Self-consistent simulation of the impedance matching network for single frequency capacitively coupled plasma

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