Fluid simulation and experimental validation of plasma radial uniformity in 60 MHz capacitively coupled nitrogen discharges

Abstract

A two-dimensional self-consistent electrostatic fluid model and the experimental diagnostic method are employed to investigate the plasma radial uniformity in capacitively coupled nitrogen discharges driven at 60 MHz. The effects of the rf power and electrode gap on the spatial profiles of the N2+ ion density and the radial profiles of the ion flux to the lower electrode are demonstrated. It is found in the simulation that with the increase of rf power or the decrease of electrode gap, the electrostatic edge effect becomes remarkable, which gives rise to an increase in the positive ion density at the electrode edge and thus the radial uniformity of plasma becomes worse. Moreover, the radial profiles of the N2+ ion flux to the lower electrode show a similar behavior to that of the ion density. These results are further understood by the calculated axial and radial components of the power deposition, which exhibit pronounced peaks at the electrode edge at high rf power or small electrode gap. In order to validate the simulation results, the radial profiles of the N2+ ion density were measured by a floating double probe. A general qualitative agreement between the experimental and calculated results is achieved.

Influence of dielectric materials on uniformity of large-area capacitively coupled plasmas for N 2 /Ar discharges

“…In recent years, Wang and his group developed a software platform for Multi-physics Analysis of Plasma Sources (MAPS), which contains three models, i.e., the fluid model, [4][5][6][9][10][11] the Particle-In-Cell/Monte Carlo (PIC/MC) model [8,[12][13][14][15] and the global model. [16] The MAPS can be used to investigate the plasma behaviors in CCP and inductively coupled plasma (ICP) discharges.…”

“…Besides, other BCs, which are also needed to complete the model, have been described previously in Ref. [4]. So a brief description is here.…”

“…Our previous work showed both theoretically and experimentally that the edge effect could be effectively suppressed and the more uniform plasma was obtained by properly decreasing the rf power or enlarging the electrode gap. [4,5] Furthermore, Xu et al studied the phaseshift effect on the CCP discharge, especially on the radial uniformity of the plasma density and the ion flux. [6] They found that the edge effect could be controlled by adjusting the phase difference.…”

Customized modulation on plasma uniformity by non-uniform magnetic field in capacitively coupled plasma

“…Moreover, in recent years, the feature size of the chip continues shrinkage, which leads to more stringent requirements for CCP density uniformity. Therefore, the modulation of CCP plasma uniformity has become a current research focus [15,16].…”

Importance of Dielectric Elements for Attaining Process Uniformity in Capacitively Coupled Plasma Deposition Reactors

“…Despite various efforts, technically complex issues such as the electron heating mechanism and the plasma distribution control have not been sufficiently resolved in the coating process using the capacitively coupled plasma (CCP) deposition reactors [1,2]. However, CCP deposition reactors have been widely adopted in the current semiconductor industry [3].…”