Voltage levels decay over the life of the shimmed target as well, but since they do so more slowly, power settings need be altered less frequently. Thus, a more stable process and a more consistent product is realized. In addition, with reduced trenching there may be a reduction in spitting or sputter splatter. There is some thought that the splatter effect is due to high intensity sputtering in the trench. However, there are no statistics to confirm or deny this speculation.
Modified targets are more stable over lifetime.
This technique of modifying magnetrons with a shunt was developed for use in a large in-line sputtering system with rectangular targets. It could be easily adapted to other planar targets that use static magnetic fields produced by permanent magnets or DC electromagnets. Although the design work would be best done with the aid of computer modeling it is possible to design a useful shunt without the computer. One can cut a shim to a best guess shape and size, put it in place, and measure the field with a gauss meter. Plotting the component of the field which is parallel to the target surface as a function of position, one can see whether the physical model has the desired structure.