PIC/MCC Simulations For The Magnetized Capacitively Coupled Plasmas

Low-pressure Capacitively Coupled Plasma(CCP)has the advantages of simple structure and cost-effectiveness,and has been widely used in the microelectronics industry.With the rapid development of the microelectronics industry,the requirements of plasma technology for process technology are getting higher and higher,and some new sources configurations of CCP discharge systems have been proposed.The CCP driven by the DC/RF sources can effectively suppress the local charging effect during the etching process,but its lower plasma density affects the etching rate during the process.The electrically asymmetric CCP can independently control the ion flux and the ion bombardment energy of the electrodes,thus meeting the requirements for line width,selectivity and control damage in the integrated circuit manufacturing process.Although there have been many studies on the CCP for the above source configuration,so far there has been little research work to take into account the influence of the magnetic field.The magnetic field can increase the absorption of power by the plasma,enhance the binding of electrons,and thus reduce the sheath voltage and increase the plasma density,which plays a very important role in improving plasma parameters.Therefore,the purpose of this paper is to systematically study the influence of magnetic field on the CCP of different source configurations,optimize the discharge parameters of plasma,and obtain the ideal plasma process effect,which provides a scientific basis for process optimization in the microelectronics industry.The effect of magnetic field on DC/RF sources driven CCP discharge was studied by one-dimensional PIC/MCC method.By comparing plasma properties under RF discharge,DC/RF discharge,RF discharge with magnetic field and DC/RF discharge with magnetic field,it is found that the introduction of external magnetic field in DC/RF sources driven CCP discharge system can increase the plasma density by an order of magnitude.With the effect of magnetic field,the DC/RF sources driven CCP not only retains the advantages of the traditional CCP,such as the simple structure and cost-effectiveness of the device,but also increase the plasma density.This configuration is expected to provide a new type of plasma source for etching in the microelectronics industry,which is of great significance for the etching process.The effects of magnetic field on the electrical asymmetry effect in the CCP were studied by one-dimensional PIC/MCC method.The effects of magnetic field coupling pressure,RF voltage and secondary electron emission coefficient on plasma properties were simulated.It is found that in a weak magnetic field,the density of the plasma can be increased to some extent and the self-bias is hardly affected.Under a strong magnetic field,the effect of secondary electrons on the discharge is critical,and the plasma density can be increased by an order of magnitude,but the cost is that the self-bias voltage is reduced,leading to a reduction on the adjustable range of ion energy.The results show that the introduction of an external magnetic field in an electrically asymmetric discharge system not only maintains the independent control of ion flux and ion bombardment energy,but also increases the plasma density and ion flux to a certain extent.The effects of magnetic field on the heating mechanism and heating mode transition in an electrically asymmetric CCP discharge system were studied by one-dimensional PIC/MCC method.The plasma properties under different magnetic field strengths and harmonic numbers were simulated,such as self-bias and plasma bulk density,ion flux and ion energy and so on.It is found that in the weak magnetic field,the electron heating is in the collisionless heating mode and the plasma density is low.When the magnetic field is increasing,the electron heating is in the ohmic heating mode,and the plasma density can be increased by an order of magnitude.By increasing the magnetic field strength,the dominate electron heating in the CCP discharge system can be switched from the collisionless heating mode to the ohmic heating mode.The magnetical asymmetry effect is proposed.The effect of non-uniform magnetic field on CCP discharge is studied by one-dimensional PIC/MCC method.By introducing a magnetic field gradient in the discharge space,the magnetic field strength near the powered electrode and the grounded electrode is different.The ion flux reaching the electrodes on both sides is not conserved,so under the effect of the capacitor in the external circuit,one electrode will generate a self-bias voltage.The self-bias voltage makes the plasma density,the electron heating rate and the ionization rate distribution asymmetrical,and the self-bias can be adjusted by changing the magnetic field gradient,thereby realizing the regulation of the ion bombardment energy.The magnetical asymmetry effect becomes a new method for causing plasma asymmetry and generating self-bias voltage.