Side Magnet Designs and Magnetic Field Effects on Effective Gap Filling of Longthrow Sputtering PVD for 3DIC Application

Abstract

This study used Finite Volume Method to simulate the magnetic profile of PVD (physical vapor deposition) chamber. It can be applied to different kinds of magnet arrangements to the longthrow sputtering PVD. For this long throw PVD, the best optimized process conditions and results from simulations included effects from chamber adaptor height, side magnet space, and magnet arangements. The side magnets consist of a total of 44 sets for one supporter around the chamber adaptor. Each set has three magnets. Each magnet has the magnetic field strength of 5,500 Gauss. The adaptor of gap filling chamber has a height of 120 mm and 44 sets of magnets around the adaptor. The polarity of side magnets is the same as the top magnets of the chamber. These magnets can very effectively increase of electron mobility and collision frequency with sputtered atoms. The plasma simulation result shows that the ionization rate on supttered atoms can be up to 26% from such a longthrow PVD system along with such magnets arrangement. Therefore, it shows a significant improvement on bottom side-wall step coverage in via hole up to 45%. The deposition rate increases by 40%. In addition, by adjusting RF bias and resputtering power, further improvement with 3/4 depth of side-wall step coverage by 30% and corner step coverage by 70% can be obtained. This study uses a simple method to apply to 3DIC gap filling capability for an increase of aspect ratio (AR). The improvement from this longthrow sputtering PVD with side magnets design around the adaptor not only results in low cost target design but also provides a very effective gap filling capability with higher deposition rate for 3DIC application.