Bulletin of the American Physical Society
61st Annual Gaseous Electronics Conference
Volume 53, Number 10
Monday–Friday, October 13–17, 2008; Dallas, Texas
Session XF1: Material Processing II |
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Chair: S.G. Walton, Naval Research Laboratory Room: Salon E |
Friday, October 17, 2008 1:30PM - 1:45PM |
XF1.00001: Evaluation of Plasma Ashing Damages on Porous SiOCH Films by Measurement of H and N Radical Densities Hiroshi Yamamoto, Keigo Takeda, Makoto Sekine, Masaru Hori The damage free plasma processes for Low dielectric constant (low-k) films are required for next generation ULSIs devices. Measurement of the radical densities which have a large impact on the damage generation in low-k film is important for clarification of plasma damage mechanism. We built up an \textit{in situ} measuring system to evaluate the properties of low-k films and behavior of radicals. H$_{2}$/N$_{2}$ ashing plasma damages on porous SiOCH films have been investigated. The surface reactions were measured by using \textit{in situ} Fourier transform infrared reflection absorption spectroscopy and spectroscopic ellipsometry. The H and N radical densities were measured by vacuum ultraviolet absorption spectroscopy. When the flow rate ratios of H$_{2}$/(H$_{2}$+N$_{2})$ for the plasma ashing were changed, the variation of damaged layer thickness agreed well with the H radical density in the plasma. From these result, damages on the porous SiOCH are probably determined by chemical reactions of H radicals which reduce the Si-CH$_{3}$ bonds and N radicals which have an effect of inhibition of the damages. [Preview Abstract] |
Friday, October 17, 2008 1:45PM - 2:00PM |
XF1.00002: Threshold energy for plasma etching of high-$k$ dielectric HfO$_{2}$ films in BCl$_{3}$-containing plasmas Yoshinori Ueda, Keisuke Nakamura, Hiroaki Kiyokami, Hiroaki Ohta, Koji Eriguchi, Kouichi Ono Plasma etching of high dielectric constant ($k)$ materials is indispensable for fabricating of future high performance ULSIs. This paper presents the dependence of HfO$_{2}$ etch rate on incident ion energy onto a wafer stage, with emphasis being placed on the threshold energy for HfO$_{2}$ etching in BCl$_{3}$-containing plasmas. Experiments were performed in both an electron cyclotron resonance (ECR) and an inductively coupled plasma (ICP) reactor by varying the rf bias power, indicating that the threshold in pure BCl$_{3}$ plasma was $E_{th}\approx $5-14 eV, which is lower than the known $E_{th}\approx $26 eV previously reported. In addition, the threshold was further lowered by adding O$_{2}$ to BCl$_{3}$, where the HfO$_{2}$ etch rate was found to increase more significantly with increasing substrate temperature. These imply that the etching was chemically enhanced by O$_{2}$ addition to lower the threshold, probably because a small amount of added O$_{2}$ reduced the concentration of surface inhibitor species BCl$_{x}$ and increased the concentration of atomic reactant Cl in the plasma [e.g., 2BCl$_{2}$ + O $\to $ BOCl + BCl + 2Cl]. We also investigated reactant and product species therein by using optical emission spectroscopy and quadrupole mass spectrometry, to discuss the etching mechanisms responsible for HfO$_{2}$ etching and their differences in ECR and ICP. [Preview Abstract] |
Friday, October 17, 2008 2:00PM - 2:15PM |
XF1.00003: Etch Challenges Brought by the Metal Hardmask Approach for Advanced Contact Patterning with Fluorocarbon-based Plasma Jean-Francois de Marneffe, Danny Goossens, Denis Shamiryan, Herbert Struyf, Werner Boullart In order to overcome patterning challenges brought by dimensional scaling and aggressive pitches, extreme ultra-violet (EUV) lithography has been recently pushed forward as a possible solution for IC manufacturing, allowing extended exposure latitude at sub-50nm dimensions. This work address the technological solutions used for contact holes patterning by means of EUV lithography. A metal hard-mask (MHM) approach has been selected, in order to combine the etching of high-aspect ratio features with thin EUV photoresist. The pre-metal dielectric stack covering the active fins was composed of 15nm Si$_{3}$N$_{4}$ as an etch-stop liner, covered by 240nm SiO$_{2}$. The MHM was made of a 30nm TiN film on top of which was spun 20nm of organic underlayer and 100nm of EUV photoresist. This presentation will describe in details the various plasma processing issues and challenges met with this patterning strategy, for down to $\sim $50nm contact hole sizes: SiO$_{2}$:TiN and SiO$_{2}$:Si$_{3}$N$_{4}$ selectivities by means of fluorocarbon-based chemistries; loading effects; profile and mask undercut control with CCP plasma; residue cleaning. [Preview Abstract] |
Friday, October 17, 2008 2:15PM - 2:30PM |
XF1.00004: Porous Low-k Material Etch For 32 nm and Beyond Yifeng Zhou, Qingjun Zhou, Ryan Patz, Hairong Tang, Jeremiah Pender, Michael Armacost, Catherine Labelle, David Horak Porous low-k materials with k $\sim $2.2 pose new challenges for plasma etch/strip damage, rough etch front/micro-trenching and via faceting are the top issues in ULK all-in-one etch. In this paper, low-k damage has been characterized for both etch and strip. The impacts of etch and strip on ULK etch and dependence of via faceting on plasma conditions and plug height have been studied. Process window of faceting control has also been discussed. It has been demonstrated that all-in-one etch and strip for via first approach can be extended to ULK (2.2) integration. [Preview Abstract] |
Friday, October 17, 2008 2:30PM - 2:45PM |
XF1.00005: ABSTRACT WITHDRAWN |
Friday, October 17, 2008 2:45PM - 3:00PM |
XF1.00006: Control Capabilities of Low-Inductance-Antenna-Driven RF Plasmas for Low-Damage Processing of Polymers Yuichi Setsuhara, Kosuke Takenaka, Ken Cho, Akinori Ebe, Masaharu Shiratani, Makoto Sekine, Masaru Hori Low-damage processing of polymers is of key importance for fabrication of next-generation devices including electronics on polymers, which require development of plasma sources with reduced plasma potential in order to control interface between the polymer substrate and functional films without suffering degradations due to ion bombardment. Furthermore, applications to polymer-based displays and photovoltaic devices require ultra-large area processes at high throughput. To meet these requirements, we have developed plasma processing technologies with low-inductance antenna (LIA) modules to sustain inductively-coupled RF plasmas. Ion energy distributions showed considerably suppressed ion energy as low as 3.8 eV. The polymer surfaces after plasma exposure were analyzed via hard x-ray photoelectron spectroscopy (HXPES) at SPring8 (National SOR facility in Japan), which exhibited nano-surface modification of polymer surface without suffering degradation of molecular structures underneath. Furthermore, plasma-enhanced deposition of silicon films showed low-temperature (200 deg.C) formation of micro-crystalline silicon films due to sufficiently reduced damage during deposition. [Preview Abstract] |
Friday, October 17, 2008 3:00PM - 3:15PM |
XF1.00007: Impact of Wafer Bias in an Inductively Coupled Plasma Reactor Prashanth Kothnur, Ananth Bhoj, Xiaohui Yuan, Laxminarayan Raja Inductively Coupled Plasma (ICP) reactors such as the Novellus SPEED HDP-CVD product enable void-free dielectric deposition in high-aspect ratio trenches for microelectronics fabrication. The physical phenomena involves production of a high-density plasma by the inductive coils and charged species extraction and high-energy impact at the biased wafer surface. The talk will present a simulation study of an ICP discharge in a dome-shaped reactor with different bias voltage waveforms on the wafer surface. The waveforms considered include different shapes (e.g. sinusoidal, triangular) and pulsed bias waveforms. The distribution of species fluxes and Ion Energy Angular Distribution functions at the wafer will be presented. The study will use VizGlow, an unstructured, mixed-mesh plasma simulator. Simulations are performed in two steps. First, the power deposition due to the inductive coils is simulated to steady-state with the assumption of a quasi-neutral plasma with ambipolar transport of charged species in the presence of an unbiased surface. The simulation is subsequently continued in the self-consistent mode using the Poisson equation to determine the electric field in the vicinity of the surface. Secondary power deposition and plasma generation owing to the applied bias is simulated self-consistently. [Preview Abstract] |
Friday, October 17, 2008 3:15PM - 3:30PM |
XF1.00008: The effect of plasmas on the equilibrium shapes of semi-conducting nanocrystals Eugene Tam, Kostya Ostrikov Consumer needs drives the electronics market and as consumers require faster computers, chips are required to be miniaturized. There is a physical limit in MOSFETs can be scaled down and alternatives must be presented. Semi-conducting Nanowires (NWs) are a potential candidate in the production of logic gates. The production of NWs is an active research area and a recurring theme that occurs in this area is the fact that the growth conditions affect the morphology of the semi-conducting crystal. There are some papers in which the equilibrium shapes of semi-conducting nanocrystals under various growth conditions is discussed however, few mention the effects of charged surfaces or the presence of a charged fluid affecting the final outcome, despite the fact that plasmas are sometimes present to aid the fabrication of NWs. Here we present the results of our simulations which determine the equilibrium shape of ZnO nanocrystals in the presence of plasmas by considering the surface energy, surface stress and precursor distribution along the surface of the structure and attempt to determine what are the optimum conditions in which NWs can form. [Preview Abstract] |
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