The Hybrid Simulation Of Pulse Modulated Radio Frequency Capacitively Coupled SiH₄/Ar Discharge

The low temperature plasma microelectronics technology makes great contributions to the world economic development. Especially in very large scale integrated circuit manufacturing processes, plasma technology is widely used during nearly one third of the production, including films deposition and etching. Plasma enhanced chemical vapor deposition (PECVD) is one of the key technology in semiconductor manufactures for its low operating temperature, good film uniformity, easily controlled processes. Silicon thin films for its good stability, mechanical and photoelectric performance are widely used as a function of a high-quality semiconductor films.The radicals’density and electron temperature are closely related with the quality of films in PECVD processes. Those factors can be controlled by the electron energy distribution for the reason that it plays a crucial role in gas dissociation. In radio frequency capacitively coupled plasma (RF-CCP) discharge, a bipolar electric field formed during electrodes and discharge center, the heating mechanism of the discharge center is ohmic heating, while the sheath’s heating mechanism are ohmic heating and stochastic heating. The plasma density distribution in CCP discharge is uniform relatively for the Symmetric and simple chamber structure, which is good for film uniformity. Pulse modulated rf discharge can provides more technical parameters for deposition processes. And the negative ions escape to electrodes during power-off times, which is beneficial for materials deposition. In addition, some deposition precursors become to spread to the electrode during the power-off period, which can prolong the time for deposition before the next power-on period. Using pulsed power, electron energy distribution deviates from Maxwell distribution for the unbalance of electron production and loss. For the purpose of better understanding of the effects ofpulse modulated processes, a fluid/MC hybrid model is used to simulate pulse modulated CCP in SiH4/Ar mixture discharge, in which the electron energy distribution is calculated by MC statistic method. It can be found that the electron energy distribution is strongly influenced by the duty cycle. Higher electron energy and dissociation rates can be obtained on the condition of low duty cycle comparing with continuous waves. At the same time, charged particles’ energy drop rapidly during the power off period, which can reduce plate damages during the deposition. The paper contains following three aspects: The first chapter introduces the basic knowledge of low temperature plasma, silicon thin films deposition techniques and pulse modulation research progresses in the experimental and theoretical.Second chapter introduces the research background of fluid/MC model, the hybrid model self-consistent process and models of fluid and MCLast chapter, pulse modulation radio frequency capacitively coupled plasma SiH4/Ar discharge is simulated by fluid/MC hybrid model. We mainly analysis the energy probability distribution and temperature of electron and plasma density changing under the influence of different duty cycle, pulse frequency, voltage and pressure during pulse modulation. By studying pulse electron energy probability distributions, the trends of electron temperature, density and even the thermal equilibrium are researched during power on and off period.