Experiments and Global Model Analysis of Inductively Coupled CF₄/O₂/Ar Plasmas

Abstract

Measurements using a Langmuir probe and optical emission spectroscopy combined with actinometry are carried out in inductively coupled CF 4 /O 2 /Ar discharges at total pressures lower than 30 mTorr for Ar contents ranging from 10 to 90%. The measured structure of the electron energy probability functions can be changed from being Druyvesteyn-like to being Maxwellian-like as Ar content decreases. The electron density measured at each fixed Ar content gradually decreases with increasing O 2 content, whereas the measured electron temperature is not sensitive to O 2 content. The atomic fluorine density measured at each fixed Ar content reaches its maximum when the ratio (R OC ) of O 2 content to the sum of CF 4 and O 2 contents is around 0.2, beyond which it decreases with increasing R OC . The atomic fluorine density measured at R OC ¼ 0:2 remains constant for Ar contents lower than 60%, beyond which it monotonically decreases with increasing Ar content. These results are shown to be in reasonably good agreement with the predictions of the global model for electronegative plasma.

Determination of Plasma Parameters in a Dual-Frequency Capacitively Coupled CF4Plasma Using Optical Emission Spectroscopy

“…In our oblate cylindrical reactor, due to the small electrode spacing, the axial diffusion to the electrode surfaces is more significant than the radial diffusion. When the gas pressure is 50 mTorr and gas temperature fitted by LIFBASE is about 600 K, D F is calculated to be about 4.0×10 3 cm 2 • s −1 , γ is reported about 0.02 [25] , K D ≈4000 s −1 and K w ≈500 s −1 . Due to the faster diffusion, the wall loss is considered to be the rate limiting step, K loss ≈ K w [24] .…”

Parallel 2D Axisymmetric Fluid Modeling of CF4 Discharge in an Inductively Coupled Plasma Source During SiO2 Etching

“…In addition, Table 7 also summarizes the list of surface reactions at metal walls based on a concept of sticking coefficients, in which 30 reaction processes are considered. [17,62] …”

“…θ P <<1), and the SiO 2 deposition yield does not occur in the simulation. In addition, Table also summarizes the list of surface reactions at metal walls based on a concept of sticking coefficients, in which 30 reaction processes are considered …”

“…[11][12][13] The models for studying tetrafluoromethane (CF 4 ) plasma in either capacitive coupled plasma or inductively coupled plasma used for etching purpose have been reported. These include the global models with complex gas-phase reactions [14][15][16][17] and the fluid models considering feeding gas-phase reactions and highly simplified surface reactions using the concept of stick coefficients without taking any etching products into account. [18][19][20][21] However, the consideration of etching products from the substrate is critical in faithfully modeling of these discharges since they can significantly influence the composition of the gas phase species in CF 4 discharge for the etching of SiO 2 and Si.…”

Studies about Flow Rate Effect on Atomic Fluorine Generation in Inductively Coupled CF4 Plasmas: A Global Model Investigation

“…The gas phase/surface reactions and respective rate coefficients considered in this model are based in the last reaction sets proposed by Kimura et al for CF 4 (9) and Kokkoris et al for C 4 F 8 (10). Seven neutral species (CF 4 , CF 3 , CF 2 , CF, C, F and F 2 ) and eight charged species (electrons, F -, CF 3 + , CF 2 + , CF + , C + , F + and F 2 + ) that compose the CF 4 gas phase are considered.…”