Contribution of Ion Energy and Flux on High-Aspect Ratio SiO2 Etching Characteristics in a Dual-Frequency Capacitively Coupled Ar/C4F8 Plasma: Individual Ion Energy and Flux Controlled

As the process complexity has been increased to overcome challenges in plasma etching, individual control of internal plasma parameters for process optimization has attracted attention. This study investigated the individual contribution of internal parameters, the ion energy and flux, on high-aspect ratio SiO2 etching characteristics for various trench widths in a dual-frequency capacitively coupled plasma system with Ar/C4F8 gases. We established an individual control window of ion flux and energy by adjusting dual-frequency power sources and measuring the electron density and self-bias voltage. We separately varied the ion flux and energy with the same ratio from the reference condition and found that the increase in ion energy shows higher etching rate enhancement than that in the ion flux with the same increase ratio in a 200 nm pattern width. Based on a volume-averaged plasma model analysis, the weak contribution of the ion flux results from the increase in heavy radicals, which is inevitably accompanied with the increase in the ion flux and forms a fluorocarbon film, preventing etching. At the 60 nm pattern width, the etching stops at the reference condition and it remains despite increasing ion energy, which implies the surface charging-induced etching stops. The etching, however, slightly increased with the increasing ion flux from the reference condition, revealing the surface charge removal accompanied with conducting fluorocarbon film formation by heavy radicals. In addition, the entrance width of an amorphous carbon layer (ACL) mask enlarges with increasing ion energy, whereas it relatively remains constant with that of ion energy. These findings can be utilized to optimize the SiO2 etching process in high-aspect ratio etching applications.

[1]  H. Lee,et al.  Control of the ion flux and energy distribution of dual-frequency capacitive RF plasmas by the variation of the driving voltagesss , 2023, Journal of Vacuum Science & Technology A.

[2]  M. Kushner,et al.  Voltage waveform tailoring for high aspect ratio plasma etching of SiO2 using Ar/CF4/O2 mixtures: Consequences of ion and electron distributions on etch profiles , 2023, Journal of Vacuum Science & Technology A.

[3]  W. V. van Gennip,et al.  Control of ion flux-energy distribution at dielectric wafer surfaces by low frequency tailored voltage waveforms in capacitively coupled plasmas , 2022, Journal of Physics D: Applied Physics.

[4]  Youngseok Lee,et al.  Investigation into SiO2 Etching Characteristics Using Fluorocarbon Capacitively Coupled Plasmas: Etching with Radical/Ion Flux-Controlled , 2022, Nanomaterials.

[5]  Y. Im,et al.  Effect of heavy inert ion strikes on cell density-dependent profile variation and distortion during the etching process for high-aspect ratio features , 2022, Physics of Plasmas.

[6]  J. J. Lee,et al.  Purgeless atomic layer etching of SiO2 , 2022, Journal of Physics D: Applied Physics.

[7]  Chang-Koo Kim,et al.  Plasma Etching of SiO2 Contact Holes Using Hexafluoroisopropanol and C4F8 , 2022, Coatings.

[8]  C. S. Hwang,et al.  Review of Semiconductor Flash Memory Devices for Material and Process Issues. , 2022, Advanced materials.

[9]  M. Sochacki,et al.  A Review: Inductively Coupled Plasma Reactive Ion Etching of Silicon Carbide , 2021, Materials.

[10]  S. Kim,et al.  Characterization of SiO2 Over Poly-Si Mask Etching in Ar/C4F8 Capacitively Coupled Plasma , 2021, Applied Science and Convergence Technology.

[11]  S. Kim,et al.  Characterization of SiO2 Etching Profiles in Pulse-Modulated Capacitively Coupled Plasmas , 2021, Materials.

[12]  Duksun Han,et al.  Ion and Radical Characteristics (Mass/Energy Distribution) of a Capacitively Coupled Plasma Source Using Plasma Process Gases (CxFy) , 2021, Coatings.

[13]  Nomin Lim,et al.  A Comparison of CF4, CHF3 and C4F8 + Ar/O2 Inductively Coupled Plasmas for Dry Etching Applications , 2021, Plasma Chemistry and Plasma Processing.

[14]  R. Nirmala,et al.  A Quantification Method in Quadrupole Mass Spectrometer Measurement , 2021, Applied Science and Convergence Technology.

[15]  J. Schulze,et al.  Voltage waveform tailoring in radio frequency plasmas for surface charge neutralization inside etch trenches , 2019, Plasma Sources Science and Technology.

[16]  J. J. Lee,et al.  A transmission line model of the cutoff probe , 2019, Plasma Sources Science and Technology.

[17]  M. Kushner,et al.  Plasma etching of high aspect ratio features in SiO2 using Ar/C4F8/O2 mixtures: A computational investigation , 2019, Journal of Vacuum Science & Technology A.

[18]  R. Pessoa,et al.  A global model study of low pressure high density CF4 discharge , 2019, Plasma Sources Science and Technology.

[19]  D. Mocuta,et al.  Progress in nanoscale dry processes for fabrication of high-aspect-ratio features: How can we control critical dimension uniformity at the bottom? , 2018 .

[20]  P. Ventzek,et al.  Quasiatomic layer etching of silicon oxide selective to silicon nitride in topographic structures using fluorocarbon plasmas , 2017 .

[21]  S. Rauf,et al.  SiO2 etching in an Ar/c-C4F8/O2 dual frequency capacitively coupled plasma , 2017 .

[22]  S. Sriraman,et al.  Role of neutral transport in aspect ratio dependent plasma etching of three-dimensional features , 2017 .

[23]  M. Matsui,et al.  Relationship between formation of surface-reaction layers and flux of dissociated species in C4F8/Ar plasma for SiO2 etching using pulsed-microwave plasma , 2016 .

[24]  G. Yeom,et al.  Application of Si and SiO2 Etching Mechanisms in CF4/C4F8/Ar Inductively Coupled Plasmas for Nanoscale Patterns. , 2015, Journal of nanoscience and nanotechnology.

[25]  Gwan-Ha Kim,et al.  Study of Surface Reaction and Gas Phase Chemistries in , 2015 .

[26]  G. Yeom,et al.  A comparative study of CF4/O2/Ar and C4F8/O2/Ar plasmas for dry etching applications , 2015 .

[27]  F. Roqueta,et al.  SF6 and C4F8 global kinetic models coupled to sheath models , 2014 .

[28]  G. Yeom,et al.  Etching characteristics and mechanisms of Mo thin films in Cl2/Ar and CF4/Ar inductively coupled plasmas , 2014 .

[29]  M. Jhon,et al.  Study on the etching characteristics of amorphous carbon layer in oxygen plasma with carbonyl sulfide , 2013 .

[30]  Jane P. Chang,et al.  Perspectives in nanoscale plasma etching: what are the ultimate limits? , 2011 .

[31]  Pascal Chabert,et al.  Physics of radio-frequency plasmas , 2011 .

[32]  Jon Tomas Gudmundsson,et al.  Low pressure hydrogen discharges diluted with argon explored using a global model , 2010 .

[33]  N. Lee,et al.  Ultrahigh Selective Etching of SiO2 Using an Amorphous Carbon Mask in Dual-Frequency Capacitively Coupled C4F8 / CH2F2 / O2/Ar Plasmas , 2010 .

[34]  E. Gogolides,et al.  A global model for C4F8 plasmas coupling gas phase and wall surface reaction kinetics , 2008 .

[35]  Jie Lian,et al.  Angular dependence of sputtering yield of amorphous and polycrystalline materials , 2008 .

[36]  S. Kadomura,et al.  On-wafer monitoring of charge accumulation and sidewall conductivity in high-aspect-ratio contact holes during SiO2 etching process , 2007 .

[37]  A. Lichtenberg,et al.  Principles of Plasma Discharges and Materials Processing: Lieberman/Plasma 2e , 2005 .

[38]  Jung-hyung Kim,et al.  Wave cutoff method to measure absolute electron density in cold plasma , 2004 .

[39]  M. Kushner,et al.  Properties of c-C4F8 inductively coupled plasmas. II. Plasma chemistry and reaction mechanism for modeling of Ar/c-C4F8/O2 discharges , 2004 .

[40]  M. Barela,et al.  Fluorocarbon-based plasma etching of SiO2: Comparison of C4F6/Ar and C4F8/Ar discharges , 2002 .

[41]  D. Hash,et al.  Impact of Gas Heating in Inductively Coupled Plasmas , 2001 .

[42]  S. Pearton,et al.  A unified global self-consistent model of a capacitively and inductively coupled plasma etching system , 2000 .

[43]  N. R. Rueger,et al.  Role of steady state fluorocarbon films in the etching of silicon dioxide using CHF3 in an inductively coupled plasma reactor , 1997 .

[44]  S. Savas Estimation of Ion Impact Energies and Electrode Self-Bias Voltage in Capacitive RF Discharges , 1987 .