Improved residue cleaning process via combined remote radical generator and powered electrode in a capacitively coupled plasma reactor

Abstract

In this thesis, an improved residue cleaning process via combined remote radical generator and a powered electrode in a capacitively coupled plasma reactor was introduced. Experimental comparisons between the conventional processing and the improved residue cleaning process were discussed. In a conventional residue cleaning process, the remote radical generator in tandem with main processing reactor is widely used. The radical generator is typically connected to the main processing reactor via small neck, and generate reactive radicals. These reactive species diffuse to the main processing reactor from` the top of the main processing reactor and the chemical reaction for residue cleaning occurs. In this process, the plasma is only generated in the remote radical generator, and charged particles are not diffused to the main processing reactor. Thus, the plasma-induced damage can be avoided in the main processing reactor as well as on the wafer. However, when radical does not sufficiently diffuse to the main processing reactor, the residue is not perfectly removed. Especially, a considerable residue remains on the powered electrode because of this electrode, located below the remote radical generator, is a shadowing region for radical flux. To remove the remaining residue on the powered electrode, the RF power was applied to the electrode with the remote radical generator. When RF power was applied, the plasma is also generated in the main processing reactor. Thus, minimizing plasma-induced damage is challenging issue. In addition, other processing parameters such as cleaning rate, defect level, deposition rate, and non-uniformity should be kept at a reasonable level. The processing result shows that the cleaning efficiency was considerably improved, and other processing parameters were maintained compared to the conventional cleaning process. These results imply that the plasma generated in the main processing reactor considerably enhances chemical reaction for residue cleaning process.