How to improve the efficiency of sputtering target material

Although increasing the pressure can improve the ionization rate, but at a higher pressure, the chance of collision between the sputtering target particles and gas also increases, the actual sputtering rate is difficult to improve greatly.  If a magnetic field parallel to the surface of the cathode is applied, the motion of the initial electron can be confined to the region adjacent to the cathode, thus increasing the ionization efficiency of the gas atom.