Simulation Of Inductively Coupled Plasma In MEMS Process Based On PIC/MCC Method

Plasma processing technology is an indispensable key technology in IC manufacturing process.Compared with other plasmas,inductively coupled plasma(ICP)has many advantages,such as low discharge pressure,high plasma density,good uniformity and great verticality of ions.Therefore,it has important application prospects in microelectronic technology such as deposition and etching.In this paper,the PIC/MCC method is used to construct the inductively coupled plasma discharge model,which aims to explore the distribution of charged particle density,particle angle and ion energy distribution in the cavity,so as to provide the physical particle information for the process simulation module and improve the simulation accuracy.The main work includes:1.The general algorithm of PIC/MCC model is given,and the main process of PIC/MCC simulation is described.At the same time,the processing method of PIC cylindrical coordinates under uniform grid is given.For the electromagnetic module of ICP simulation,the finite difference time domain(FDTD)algorithm is used to solve the problem,and the perfectly matched layer(PML)boundary condition with the best absorption effect is used to solve the problem of electromagnetic wave propagation at the truncation point.The construction of ICP module is completed.2.Based on the simplicity of argon simulation,the two-dimensional inductively coupled plasma discharge process of argon in cylindrical cavity is simulated.The influence of air pressure and coil current on argon inductive discharge was investigated.The results show that the plasma density increases and the electron temperature decreases with the increase of air pressure;the plasma density can be effectively increased by increasing the current through the coil,but the effect of electron temperature is not obvious.3.Finally,the SiH₄/O₂ inductively coupled plasma discharge process in the actual process cavity is simulated.The cavity is divided into two areas:the discharge area and the wafer processing area.First,the inductive discharge of SiH₄/O₂ in the discharge area is simulated,and the density distribution of charged particles is given.The main ion products are O₂⁺,SiH₂⁺and SiH₃⁺.Finally,based on the ICP stable results of the discharge source area,the SiH₄/O₂ discharge simulation in the lower wafer processing area is carried out,and the final distribution of charged particles,spatial potential distribution,main charged particle energy and angle distribution are given.To sum up,PIC/MCC model was adopted to establish the two-dimensional cylindrical coordinate discharge system of inductively coupled plasma in this paper to simulate the inductive discharge process of Ar and SiH₄/O₂.The accuracy of the simulation module can be improved by obtaining the charged particle Angle and energy distribution in steady state.