Bulletin of the American Physical Society
63rd Annual Gaseous Electronics Conference and 7th International Conference on Reactive Plasmas
Volume 55, Number 7
Monday–Friday, October 4–8, 2010; Paris, France
Session QR2: Plasma Etching II |
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Chair: Remi Dussart, Universite d'Orleans Room: 151 |
Thursday, October 7, 2010 4:00PM - 4:30PM |
QR2.00001: Plasma-surface interactions in plasma etching processes for nanometer-scale microelectronic devices Invited Speaker: Chlorine- and bromine-based plasmas have been used for plasma etching processes in semiconductor industry, and a better understanding of plasma-surface interactions is indispensable for nanometer-scale control of sidewalls and bottom surfaces of the feature being etched. This paper presents our recent numerical and experimental study of plasma-surface interactions in Cl- and Br-based plasma etching of Si and other new materials. First, a Monte Carlo-based atomic-scale cellular model (ASCeM) was developed to simulate the feature profile evolution on nanometer scale during Si etching, including surface oxidation, inhibitor deposition, and ion reflection and penetration on surfaces. A classical molecular dynamics (MD) simulation was also developed with an improved Stillinger-Weber interatomic potential model, to clarify surface reaction kinetics on atomic scale during Si etching, and then to simulate the feature profile evolution on atomic scale. The numerical results reveal the origin of profile or surface anomalies such as microtrench, roughness, and residue, and also the etching fundamentals such as etch yield, product stoichiometry, and atomistic surface structures; and a comparison is made with etching experiments and surface diagnostics for further modeling. Moreover, the etching of high-$k$ dielectric and metal electrode materials was investigated to gain an understanding of the etch mechanisms for anisotropy and selectivity. As compared to Si, a competition between etching and deposition is significant and crucial in etching of these materials. [Preview Abstract] |
Thursday, October 7, 2010 4:30PM - 4:45PM |
QR2.00002: Simulations of an Ar/HBr/O$_2$ microwave source etch process and the effect of SiBr and SiBr$_2$ cross-sections on computed etch-profiles James Munro, Jonathan Tennyson, Song-Yun Kang, Daniel Brown Electron--molecule scattering calculations are performed for SiBr and SiBr$_2$ using Quantemol-N.\footnote{J. Tennyson {\it et al}, J. Phys.: Conf. Ser., 86, 012001 (2007)} These cross-sections are then used to construct a set gas phase reactions for the plasma simulation. An etch-profile simulation is then performed using the Monte Carlo Feature Profile Model (MCFPM)\footnote{R. J. Hoekstra {\it et al}, J. Vac. Sci. Technol. A 15, 1913 (1997)} with inputs supplied by simulation of an Ar/HBr/O$_2$ plasma. Computed cross-sections include the total elastic cross-section, dissociative electron impact cross-sections, ionisation cross-sections and an estimate of the dissociative attachment cross-section. The use of Ar/HBr/O$_2$ chemistries have been studied previously\footnote{J. M. Lane {\it et al}, J. Vac. Sci. Technol. A 18, 188 (1999)}$^,$\footnote{S. A. Vitale {\it et al}, J. Vac. Sci. Technol. A, 19, 2197 (2001)} and a reduction in microtrenching was found when HBr was included. An analysis of the contribution of SiBr and SiBr$_2$ to the computed etch profile will be presented at the conference. [Preview Abstract] |
Thursday, October 7, 2010 4:45PM - 5:00PM |
QR2.00003: Global Models for Virtual Metrology and Closed Loop Process Control Stephen Daniels, Yang Zhang, Bernard Keville, Evgueni Gudimenko, Chanel Hayden, Anthony Holohan, Miles Turner Global (0D) models of industrial plasmas have tremendous potential for informing virtual metrology schemes in IC manufacturing. These models can be integrated with feature scale simulators for process optimization and can be incorporated into closed loop process control schemes for within-wafer real time control of manufacturing tools. We will compare predictions from a global model of an industrially relevant plasma process, with experimental results obtained from process sensors and diagnostics, including actinometric OES, microwave resonance spectroscopy, and Langmuir probe analysis. The validity of the oxygen actinometry measurements is assessed using Laser Induced Fluorescence. The influence of wall interaction and wafer loading on the plasma process is examined. Real time, closed loop control of a laboratory capacitively coupled Ar/O2 plasma using OES and a microwave resonance probe as sensors is described. A dynamical process model, which includes a global model of the plasma chemistry, facilitates design and testing of the control algorithm. Model validation using step responses from the experimental process is discussed. The efficacy of the control algorithm is demonstrated by setpoint tracking and disturbance rejection over a range of operating points. [Preview Abstract] |
Thursday, October 7, 2010 5:00PM - 5:30PM |
QR2.00004: Fine ion energy control for sub-32 nm node device RIE using pulsed-DC superimposed 100 MHz rf CCP Invited Speaker: 1 MHz pulsed-DC superimposed (p-DCS) 100 MHz rf CCP (capacitive coupled plasma) RIE was studied to control the ion bombardment energy precisely. It was found that (a) the input p-DCS 100MHz waveform was reproduced on the wafer, (b) Maximum ion energy of the ion energy distribution could be controlled by the p-DC voltage, and also, about 70{\%} of the total ion flux was concentrated at the maximum ion energy region, which corresponded to the 70{\%} duty ratio of the 1 MHz pulsed-DC, and, (c) a narrow energy width was obtained by 100MHz. Fine ion energy control was realized by p-DCS CCP. The p-DCS CCP was applied to the SOC (spun-on carbon) RIE with SOG (spun-on glass) as mask. It was found that SOC etch rate increased with p-DC voltage, SOG mask erosion was suppressed by maximum ion energy control of p-DCS CCP, and as a result, CD shift was minimized at high etch rate by using p-DCS CCP. The p-DCS 100 MHz rf CCP was effective for sub-32 nm node device RIE. [Preview Abstract] |
Thursday, October 7, 2010 5:30PM - 5:45PM |
QR2.00005: Modification of Si-O-Si Structure in Porous SiOCH Low-$k$ Films with Ions, Radicals, and VUV Radiation in O$_{2}$ Plasma Hiroshi Yamamoto, Kohei Asano, Keigo Takeda, Kenji Ishikawa, Hiroki Kondo, Makoto Sekine, Masaru Hori Since the trench sidewall in porous SiOCH film is known to suffer serious damage during the plasma processes, understanding of the damage occurring mechanism is important for realizing damage free processes. In this work, the impact of ions, radicals and VUV radiation in O$_{2}$ plasma on Si-O-Si structure was investigated. To investigate the Si-O-Si bond modification in the films, IR absorption signal in 985-1250 cm$^{-1}$ were decomposed to three bands with peaks at 1035, 1065, and 1149 cm$^{-1}$, which correspond to the linear, network and cage structures, respectively. The Si-O-Si linear structure changed to network and cage structure with decrease in Si-CH$_{3}$ bond after O$_{2}$ plasma exposure. VUV radiation in O$_{2}$ plasma did not cause damage on the porous SiOCH films. O radicals caused the extraction of -CH$_{3}$ groups and the modification of the Si-O-Si structure and this reaction is enhanced by VUV radiation. [Preview Abstract] |
Thursday, October 7, 2010 5:45PM - 6:00PM |
QR2.00006: Study of a Charging Voltage during SiO$_{2}$ Etching in a 2f-CCP Takashi Yagisawa, Tetsuya Tatsumi, Toshiaki Makabe Top-down plasma micro/nano processing is increasingly important for a continuous development of ultra large scale integrated (ULSI) circuits. In particular, etching of contact holes through SiO$_{2}$ film to Si layer is a crucial process for the fabrication of multilayer interconnects. SiO$_{2}$ etching processes of high-aspect-ratio contact hole (HARC) have caused serious problems due to a local charge accumulation inside a deep contact hole, considered as one of the origins of plasma-induced damages. A surface conduction considered as one of possible mechanisms for reducing the charge accumulation at the bottom of a contact hole irradiated to SiO$_{2}$ etching in fluorocarbon gas chemistry is investigated by using both experimental and numerical techniques. The dependence of the charging potential on a biasing voltage obtained by a simulation gives a quite different behavior from that by the experimental result. Under the assumption that the discrepancy is mainly caused by the surface conduction on the sidewall due to C$_{x}$F$_{y}$ polymer deposition, the optimal value of surface conductivity can be estimated. [Preview Abstract] |
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