Effect of electrode spacing on the density distributions of electrons, ions, and metastable and radical molecules in SiH{sub 4}/NH{sub 3}/N{sub 2}/He capacitively coupled plasmas
- AE R&D Center, Kyungwon Tech, Inc., Seongnam-si 463-828 (Korea, Republic of)
- Department of Materials Science and Engineering, Kunsan National University, Kunsan-si 573-701 (Korea, Republic of)
Semiconductor fabrication often requires the deposition of hydrogenated silicon nitride (SiN{sub x}H{sub y}) film using SiH{sub 4}/NH{sub 3}/N{sub 2}/He capacitively coupled plasma (CCP) discharge. As analysis of the discharge geometry is essential to understanding CCP deposition, the effect of electrode spacing on the two-dimensional distributions of electrons, ions, and metastable and radical molecules was analyzed numerically using a fluid model. The simulation shows that the spatial variations in the ionization rates near the sheath become more obvious as the electrode spacing increases. In addition, as molecule-molecule gas-phase reactions are significantly affected by the local residence time, large electrode spacings are associated with significant volumetric losses for positive ions. Consequently, an increase of the electrode spacing leads axial density profiles of ions to change from bell shaped to double humped. However, NH{sub 4}{sup +} persistently maintains a bell-shaped axial density profile regardless of the degree of electrode spacing. We set the mole fraction of NH{sub 3} to only 1% of the total flow at the inlet, but NH{sub 4}{sup +} is the most abundant positive ion at the large electrode spacings. As the gas flow can transport the radicals around the space between the electrodes, we found that radical density distribution shifts toward the grounded electrode. The shift becomes pronounced as the electrode spacing increases. Finally, to validate our model, we compared the calculated deposition rate profile with the experimental data obtained along the wafer radius. According to our numerical results, the SiN{sub x}H{sub y} deposition rate decreases by approximately 16% when the electrode spacing increases from 9 to 20 mm.
- OSTI ID:
- 22494639
- Journal Information:
- Journal of Applied Physics, Vol. 118, Issue 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
AMMONIA
CATIONS
COMPUTERIZED SIMULATION
DEPOSITION
ELECTRIC DISCHARGES
ELECTRODES
ELECTRON DENSITY
EXPERIMENTAL DATA
GAS FLOW
HELIUM
HYDROGENATION
METASTABLE STATES
MOLECULE-MOLECULE COLLISIONS
MOLECULES
PLASMA
RADICALS
SEMICONDUCTOR MATERIALS
SILICON NITRIDES
THIN FILMS
TWO-DIMENSIONAL CALCULATIONS