Inductively coupled plasmas (ICPs) containing Cl2 are widely used for plasma etching in the semiconductor industry. One common issue during plasma etching is aspect ratio dependent etching (ARDE), which is generally attributed to variation in the flux of etchant species to the bottom of features with different dimensions. Insufficient fluxes of neutral etchants to the bottom of high aspect ratio features can also result in sputtering, which tends to distort the feature profile. This article addresses two issues relevant to Cl2 ICP and plasma etching in these plasmas. First, a comprehensive set of diagnostics is used to validate a model for Cl2 ICP for gas pressure between 3 and 90 mTorr. The plasma diagnostics include microwave resonant hairpin probe-based measurements of electron density, photolysis-calibrated two-photon laser induced fluorescence measurement of Cl density, photo-detachment-based measurement of Cl− density, and laser diode absorption spectroscopy of argon metastable species to measure the gas temperature. Consistent with the experiments, the model shows that the electron density peaks near the center of the chamber at low gas pressure due to rapid diffusion. The electron density peak moves under the coils at higher pressures. Using the validated Cl2 model, we investigate ICPs with rectangular pulsed DC voltage for bias. It is shown that the Cl flux at the bottom of a trench decreases significantly with increasing aspect ratio of the trench. Neutral to ion flux ratio is therefore low at the bottom of higher aspect ratio trenches. The duty cycle of the pulsed bias waveform is found to be an effective means of increasing the neutral to energetic ion flux ratio, which should help with ARDE and sputter reduction.
Skip Nav Destination
On the use of pulsed DC bias for etching high aspect ratio features
Article navigation
January 2025
Research Article|
December 02 2024
On the use of pulsed DC bias for etching high aspect ratio features
Xingyi Shi
;
Xingyi Shi
a)
(Conceptualization, Data curation, Formal analysis, Investigation, Writing – original draft, Writing – review & editing)
1
Applied Materials, Inc.
, 3333 Scott Blvd., Santa Clara, California 95054
Search for other works by this author on:
Samaneh Sadighi
;
Samaneh Sadighi
(Conceptualization, Data curation, Formal analysis, Validation)
1
Applied Materials, Inc.
, 3333 Scott Blvd., Santa Clara, California 95054
Search for other works by this author on:
Shahid Rauf
;
Shahid Rauf
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Project administration, Software, Validation, Visualization, Writing – original draft, Writing – review & editing)
1
Applied Materials, Inc.
, 3333 Scott Blvd., Santa Clara, California 95054
Search for other works by this author on:
Han Luo
;
Han Luo
(Data curation, Formal analysis, Software)
1
Applied Materials, Inc.
, 3333 Scott Blvd., Santa Clara, California 95054
Search for other works by this author on:
Jun-Chieh Wang
;
Jun-Chieh Wang
(Conceptualization)
1
Applied Materials, Inc.
, 3333 Scott Blvd., Santa Clara, California 95054
Search for other works by this author on:
Jason Kenney
;
Jason Kenney
(Software, Validation)
1
Applied Materials, Inc.
, 3333 Scott Blvd., Santa Clara, California 95054
Search for other works by this author on:
Jean-Paul Booth
;
Jean-Paul Booth
(Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Project administration, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
2
Laboratoire de Physique des Plasma (LPP), CNRS, Sorbonne Université, École Polytechnique, Institut Polytechnique de Paris
, 91120 Palaiseau, France
Search for other works by this author on:
Daniil Marinov
;
Daniil Marinov
(Data curation)
2
Laboratoire de Physique des Plasma (LPP), CNRS, Sorbonne Université, École Polytechnique, Institut Polytechnique de Paris
, 91120 Palaiseau, France
Search for other works by this author on:
Mickaël Foucher;
Mickaël Foucher
(Data curation)
2
Laboratoire de Physique des Plasma (LPP), CNRS, Sorbonne Université, École Polytechnique, Institut Polytechnique de Paris
, 91120 Palaiseau, France
Search for other works by this author on:
Nishant Sirse
Nishant Sirse
(Data curation)
3
Institute of Science and Research and Centre for Scientific and Applied Research, IPS Academy
, 452012 Indore, India
Search for other works by this author on:
a)
Electronic mail: [email protected]
J. Vac. Sci. Technol. A 43, 013001 (2025)
Article history
Received:
July 30 2024
Accepted:
November 12 2024
Citation
Xingyi Shi, Samaneh Sadighi, Shahid Rauf, Han Luo, Jun-Chieh Wang, Jason Kenney, Jean-Paul Booth, Daniil Marinov, Mickaël Foucher, Nishant Sirse; On the use of pulsed DC bias for etching high aspect ratio features. J. Vac. Sci. Technol. A 1 January 2025; 43 (1): 013001. https://doi.org/10.1116/6.0003943
Download citation file:
Pay-Per-View Access
$40.00
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
453
Views
Citing articles via
Low-temperature etching of silicon oxide and silicon nitride with hydrogen fluoride
Thorsten Lill, Mingmei Wang, et al.
Surface passivation approaches for silicon, germanium, and III–V semiconductors
Roel J. Theeuwes, Wilhelmus M. M. Kessels, et al.
Atomic layer deposition of nanofilms on porous polymer substrates: Strategies for success
Brian C. Welch, Jeanne Casetta, et al.
Related Content
Deep GaN through-substrate via etching using Cl2/BCl3 inductively coupled plasma
J. Vac. Sci. Technol. A (October 2020)
Recombination coefficients for Cl on plasma-conditioned yttrium oxide chamber wall surfaces
J. Appl. Phys. (January 2019)
Experimental investigation of the electron impact excitation behavior in pulse-modulated radio frequency Ar/O 2 inductively coupled plasma
J. Appl. Phys. (January 2019)
Experimental and numerical investigations on time-resolved characteristics of pulsed inductively coupled O2/Ar plasmas
J. Vac. Sci. Technol. A (November 2016)
Velocity boundary conditions for positive ions entering radio-frequency sheaths in electronegative plasmas
J. Appl. Phys. (August 2017)