Investigation On Characteristics Of Capacitively Coupled Plasma Driven By Very High Frequency(40.68mhz)

Capacitively coupled plasma has attracted much attention due to its application in the fields of microelectronics, advanced electronic device manufacturing and material handling, etc. What’s more, capacitively coupled plasma’s electrical characteristics, plasma diagnostic techniques and simulation methods are also increasingly becoming the focus of research. In this paper, we have studied the properties of capacitively coupled plasma of Ar including addition of 5% O2 and 10%O2 in it driven by 40.68 MHz frequency. Langmiur probe diagnostic technique was conducted to discover the evolution of plasma properties such as electron energy distribution function, electron temperature and electron density, etc.Firstly, we studied the Ar plasma properties by changing parameters such as discharge pressure, the RF input power, radial distance from center, axial distance from discharge electrode and distance between electrodes. Experimental results showed that discharge pressure and RF input power had a significant impact on the behavior of electron heating. As increasing discharge pressure, the transition for the electron energy probability function changed from bi-Maxwellian type under low pressure to single-Maxwellian type under moderate pressure and then to Druyvesteyn type. Increasing the RF input power promoted a rise in the number of low energy electron population. Further experiments showed that discharge gaps directly affected the proportion of high energy and low energy electron density and electron temperature distribution, which led to the transformation of electron heating mode.Low pressure has broad application prospects in material growth, etching and surfacemodified of micro-nano electronic industry due to the high chemical activity, controllable ion flux and energy, precise control still need plasma parameters to be an appropriate process window. For this reason, particular electronegative gases are usually incorporated into the plasma to alter its chemical properties. In this thesis, we have also studied the electronegative plasma characteristics with addition of 5% O2 and 10%O2 into argon. The electron energy probability function, electron temperature and electron density were investigated by changing discharge pressure, RF input power, the distance from center and the discharge gaps. It was found that, as adding a small amount of oxygen in the Ar plasma, electron energy probability distribution was deviated from the Maxwellian distribution. However, adding a small amount of oxygen in the Ar plasma appeared more uniform for the electron distribution in radial direction than that in Ar plasma. Tendency of electron temperature and electron density with discharge pressure, RF input power, the radial location, discharge gaps had not significant changes by adding a amount of oxygen in the Ar plasma, even though the plasma heating mechanisms becoming more complex.