Magnetic Circuit Analysis / Magnetic Fields for Plasmas
In a sputter device using magnetron plasma, it is required to form the optimum magnetic field in order to improve the uniformity of the thin film making up the substrate, to diversify the target materials, and to extend the target service life. Therefore, it is necessary to design the magnetic circuit using simulation of the condition of electron tracking due to the electric field and magnetic field.
Figure (a) is a cross-sectional diagram of a sputter device. The magnetic circuits are laid out to make the magnetic field horizontal on the target. Figure (b) shows the electron trajectory on the magnetic circuit. The electrons move circumferentially while circling the cyclotron radius. It can be seen that since the farther from the magnetic circuit, the weaker the magnetic field, the cyclotron radius increases at the top, which is farther from the target. On the other hand, the circumferential trajectory radius corresponds to the position at which the magnetic field is horizontal.
Figure (c) shows the change in the electron orbit over time. The electrons on the target drift in a direction perpendicular to the electric field and magnetic field and finally draw a circumferential trajectory at the position where the magnetic field is horizontal. Therefore, it is expected that the erosion on the target will proceed fastest on this circumferential trajectory.
Click the thumbnail for the large figure.
Figure (a) Cross-sectional diagram of a sputter device
Figure (b) Electron trajectory on the magnetic circuit
Figure (c) Change in the electron orbit over time
