Electrical properties of thin films deposited from TMS/O2 in Microwave Multipolar Plasma reactor

Thin films have been deposited from Tetramethylsilane or a mixture of Tetramethylsilane and oxygen (TMS/O2). The plasma discharge power and the working pressure in the reactor were kept constant and equal to 400 W and 1 mTorr,... [ view full abstract ]

Thin films have been deposited from Tetramethylsilane or a mixture of Tetramethylsilane and oxygen (TMS/O₂). The plasma discharge power and the working pressure in the reactor were kept constant and equal to 400 W and 1 mTorr, respectively. It has been observed that the oxygen proportion addition in the plasma mixture lead to the change of the structure films from organic character to inorganic character close to SiOx-like structure [1].               The current voltage characteristics I (V) study of Metal-Insulating-Metal structures for organic and inorganic films structure suggest that the carrier transport in the deposited films is limited by a space charge conduction mechanism. Moreover, it has been revealed that the electrical current of inorganic films decrease compared to the organic films, which is probably due to the decrease of the defects in the elaborated films. 

On the other hand, C-V characteristics exhibit deltaV shift towards negative values for organic films. The area of delta-V shift as we can see in figure 1 decrease with the increase of the oxygen ratio until disappear for inorganic films (deposited with high oxygen ratio). This behavior indicated the presence of defects in the organic films and the decrease of these defects according to the change of films structure from organic to inorganic character, this result is in good agreement with I(V) study. Therefore, the formation of more inorganic groups  improve the electrical properties films.

[1] M. Kihel, S. Sahli, A. Zenasni , P. Raynaud, Y. Segui, "Dielectric properties of SiOx like films deposited from TMS/O2 mixture in low pressure microwave plasma", Vacuum 107 (2014), pp264-268.