Bulletin of the American Physical Society
70th Annual Gaseous Electronics Conference
Volume 62, Number 10
Monday–Friday, November 6–10, 2017; Pittsburgh, Pennsylvania
Session FT1: Inductively Coupled Plasmas |
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Chair: Peter Ventzek, Tokyo Electron (TEL) Room: Salon D |
Tuesday, November 7, 2017 1:30PM - 1:45PM |
FT1.00001: Theoretical investigation of power balance and hysteresis of a miniature microwave ICP-plasmajet Michael Klute, Horia-Eugen Porteanu, Wolfgang Heinrich, Peter Awakowicz, Ralf Peter Brinkmann Microwave-driven plasmas-jets offer attractive properties for various technical applications. They are usually operated in a capacitive mode. However, experimental experience shows a number of disadvantages for capacitive coupling such as high boundary sheath voltage and thus high electrical losses. Due to these characteristics, inductively coupled plasmas are of particular interest for technical applications. Recently \textit{Porteanu et al.}[1] proposed a small scale plasma-jet operated as an inductive discharge. The key characteristic of the suggested plasma-jet is the implementation of an LC-resonance-circuit into a cavity resonator. In this work the proposed plasma-jet is examined theoretically. A global model for the electromagnetic fields and energy balance is presented. Mathematical analysis of the electromagnetic fields leads to a description based on a sum of different modes. It is found that the modes of zero and first order can be identified with inductive and capacitive coupling. In a second step the matching network and its frequency depended characteristic are taken into account. Finally an investigation of possible hysteresis effects is carried out. \newline [1]Porteanu et al.\textit{Plasma Sources Sci.Technol.}\textbf{22}, 035016(2013) [Preview Abstract] |
Tuesday, November 7, 2017 1:45PM - 2:00PM |
FT1.00002: Experimental Investigation of pulsed inductively coupled Ar and Ar/N2 plasmas by a time-resolved Langmuir probe Fei Gao, Yu-Ru Zhang, Yong-Xin Liu, You-Nian Wang Pulsed inductively coupled plasmas have been widely used in the etching process of the semiconductor manufacturing due to its many advantages, such as more flexible control of the ion energy distribution. The time evolutions of the radial distribution of electron density and electron energy probability function (EEPF) are measured in pulsed inductively coupled Ar and Ar/N$_{\mathrm{2}}$ plasmas by using a Langmuir probe. In Ar discharge, the electron density generally exhibits a parabolic distributions during the whole active-glow period at a low pressure. However, at a high pressure, the electron density first increases and then decreases with the increase of the radial distance during the initial active-glow. As the time evolves, the peak of the electron density gradually moves towards the chamber center, and finally the radial distribution of electron density tend to be parabolic during the late active-glow period. In Ar/N$_{\mathrm{2}}$ discharge, the maxima of the electron density is off-centered during the whole active-glow. In addition, the peak of electron density in Ar/N$_{\mathrm{2}}$ discharge occurs earlier than that in pure Ar discharge. To better understand the underlying physics, the radial distribution of the EEPF are analyzed. [Preview Abstract] |
Tuesday, November 7, 2017 2:00PM - 2:15PM |
FT1.00003: Fundamental Studies of Pulsed Processing Plasmas Kristopher Ford, Joel Brandon, Kyung Sun Kim, Tyler List, Tianyu Ma, Priyanka Arora, Shuo Huang, Sang Ki Nam, Steven Shannon, Vincent Donnelly, Mark Kushner Pulsed plasmas present new opportunities for semiconductor processing, which include unique chemistries, reduced substrate heating, and decreased charge damage. Transient plasmas also present new challenges compared to constant power delivery systems due to their dynamic behavior. Power delivery, diagnostics, and simulation tools must provide $\mu $s-scale time resolution and response. System measurement and control on this time scale not only ensures repeatable process conditions; it also enables new process control and optimization methods. This work reviews time resolved characterizations efforts on inductively coupled plasmas that focus on system characterization, chemistry, and plasma surface interaction using an array of diagnostics (optical emission, Langmuir probe, microwave hairpin, fast CCD imaging, RF measurement) along with pulsed RF simulation in the HPEM framework. Time resolved measurements of n$_{\mathrm{e}}$, T$_{\mathrm{e}}$, V$_{\mathrm{p}}$, V$_{\mathrm{f}}$, V$_{\mathrm{RF}}$, I$_{\mathrm{RF}}$, and optical emission will be presented together with simulation cases. From these studies, compelling pathways for transient plasma control and optimization will be presented. [Preview Abstract] |
Tuesday, November 7, 2017 2:15PM - 2:30PM |
FT1.00004: Model Describing The E-H Mode Transition With Intrinsic Electrical Properties Of Inductively Coupled Plasma Reactors Shaun Smith, David J. Coumou For inductively coupled plasma sources, there exists a minimum operating power, below which, the plasma source abruptly shifts from the inductive coupling mode. This transition point for an RF driven ICP is from the electrostatic mode to the electromagnetic mode, or more commonly referred to, as the E-H mode transition. For increasing current, the power absorbed during E-mode precipitously \textit{drops} toward a minimum defined by a power loss boundary, similar to that seen in a toroidal plasma source. After the transition to H-mode, the plasma current \textit{increases} the power absorbed by the plasma source. For pattern transfer, the E and H modes both serve selectivity and etch benefits, however the mode transition remains a vexing challenge for RF power delivery systems. \newline The existence of the E-H mode transition is well known in RF inductively coupled plasmas, but has not been extended to toroidal plasma sources. We present a self-consistent electrical description of the mechanism for the E-H mode transition. We show the transition point can be intentionally manipulated with the variation of an electrical property of the system. Commensurate with model experimental results, we describe the impact the E-H mode imposes on RF power delivery coupled to ICP reactors. [Preview Abstract] |
Tuesday, November 7, 2017 2:30PM - 2:45PM |
FT1.00005: E-H mode detection and symmetry effects in ICP plasmas with bias power Michael Klick ICP based plasma etchers are widely used in the semiconductor industry. Parameters from industrial chambers are usually not suited to detect different plasma modes. Here the Self Excited Electron Resonance Spectroscopy (SEERS) is extended to provide parameters which describe the electron heating and the symmetry of the plasma. During ignition and at lower power the plasma in a ICP chamber is in the E-mode. With increasing RF power the electron density increases, the inductive heating becomes more efficient. The investigations were focused on the dependency of the transition on the chamber hardware, pressure, ICP power, and phase angle in two commercial ICP chambers. The E-H mode transition is clearly identified and it shows a well pronounced dependence on the pressure. Due to the chamber geometry, the plasma shows a different symmetry in E and H mode. In the H mode at high source power, substrate and bias power play no role and the plasma shows the classical asymmetry. A phase shift shows a larger impact on the transition than the pressure. At lower source power, the power coupling at the driven substrate electrode dominates → no influence of phase shift. One chamber shows always an earlier transition – indicating here a higher efficiency of the inductive power coupling system. [Preview Abstract] |
Tuesday, November 7, 2017 2:45PM - 3:00PM |
FT1.00006: Effects of electron energy probability function on the negative ion production in low pressure inductively coupled hydrogen plasmas. Wei Yang, Hong Li, Fei Gao, Alexander Khrabrov, Igor Kaganovich, You-Nian Wang Dissociative attachment of low energy electrons to vibrationally excited hydrogen molecules plays a key role in the formation of volume negative hydrogen ions. The vibrationally excited hydrogen molecules are generated in collisions with fast electrons, while negative ions are generated in collisions with low energy electrons.$^{\mathrm{1}}$ Therefore, the generation of negative hydrogen ions greatly depends on the electron energy probability function (EEPF) The effects of EEPF on the negative ion production are investigated in low-pressure inductively coupled hydrogen plasmas. The particle species, i.e., ground-state hydrogen molecules and atoms, 14 vibrationally excited molecules, positive ions, negative ions and electrons, accompanied by the relevant chemical reactions, are included in the model. The plasma parameters, i.e., temperatures of the electrons and H atoms and number densities of all species, as a function of gas pressure, are evaluated for different EEPFs. To validate the model, the calculated EEPFs and the electron density and temperature are compared with experimental measurements; and a reasonable agreement between simulated plasma parameters and experimental data is achieved. [Preview Abstract] |
Tuesday, November 7, 2017 3:00PM - 3:15PM |
FT1.00007: Circuit induced pulsed RF transients: impact on plasma parameters and source design considerations Joel Brandon, Kris Ford, Sang-Ki Nam, Jang-Gyoo Yang, Sangheon Lee, Steve Shannon The transient characteristics of pulse-modulated inductively coupled plasmas in argon are experimentally investigated. Time resolved measurements are made by Langmuir probe and microwave hairpin probe for a cylindrical ICP configuration driven at 13.56MHz with nominal peak power densities between 0.01 W/cm$^{\mathrm{3}}$ -- 0.1 W/cm$^{\mathrm{3}}$and nominal 1 kHz pulse frequency. Optimized conjugate match tuning to plasma impedance at a defined time after pulse initiation provides control of the initial n$_{\mathrm{e}}$ and T$_{\mathrm{e}}$ transient comparable to generator-driven pulse shaping methods at the expense of non-optimal time averaged reflected power. Source design considerations can also contribute to time dependent control of power delivery, particularly when tuning strategies such as delivered power leveling and agile frequency control are considered. Time resolved measurement of plasma parameters and power dissipation in the system are presented, demonstrating control of n$_{\mathrm{e}}$ and T$_{\mathrm{e}}$ rise times through matching network and source topology design, controlling rise time by as much as a factor of four and enabling within-pulse power delivery control. [Preview Abstract] |
Tuesday, November 7, 2017 3:15PM - 3:30PM |
FT1.00008: A novel linear microwave plasma source using circular TE$_{\mathrm{11}}$ mode and continuous line slot antenna Ju-Hong Cha, Ho-Jun Lee For conventional linear microwave plasma sources with co-axial TEM waveguide, there is relatively large resistive loss in inner conductor of the waveguide. The wave electric field is directed normal to the quartz window surface, which enhances electron loss. To improve performances of linear microwave plasma sources, a novel linear microwave plasma source suitable for large area deposition and etching processing has been developed. In the proposed plasma source, circular TE$_{\mathrm{11}}$ mode has been used for plasma generation. After mode conversion from rectangular TE$_{\mathrm{10}}$ to circular TE$_{\mathrm{11}}$, 2.45 GHz microwave power is transferred to plasma via continuous line slot antenna along the wave propagation direction. The direction of radiated electric field is almost parallel to the quartz window. Diagnostics on the basic plasma properties using electrical probe and microwave cutoff probe confirmed that proposed source has better plasma generation efficiency compared with the conventional source. For 200 mTorr Ar plasma with 1 kW microwave input power, plasma density improvement about 80{\%} was achieved. In addition, more stable impedance matching characteristics has been observed in proposed plasma source. [Preview Abstract] |
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