Analysis of resistance behavior in Ti- and Ni-salicided polysilicon films

• Published in: IEEE transactions on electron devices Vol. 41; no. 12; pp. 2305 - 2317
• Main Authors: Ohguro, T., Nakamura, S., Koike, M., Morimoto, T., Nishiyama, A., Ushiku, Y., Yoshitomi, T., Ono, M., Saito, M., Iwai, H.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-12-1994; Institute of Electrical and Electronics Engineers
• Subjects: Annealing; Boron; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electric resistance; Electrical properties of specific thin films; Electrical resistance measurement; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Elemental semiconductors; Exact sciences and technology; Pattern analysis; Physics; Semiconductor films; Silicidation; Silicides; Silicon; Testing; Thin films; Electrical properties; Complementary MOS technology; Polycrystals; Electric resistivity; Silicon; Experimental study
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/16.337443

The sheet resistance of TiSi/sub 2/-polycide (TiSi/sub 2/-polysilicon) lines increases as they are made narrower. This phenomenon has been investigated in detail. It is found that the relationship between sheet resistance and line width (W) is characterized by three distinct regions according to the value of W. The abrupt increase in sheet resistance observed in the region W/spl les/0.2 /spl mu/m cannot be explained in terms of the phase transition from C54 to C49, which we show to be the cause of the rising resistance at larger W. By adopting a new test pattern for sheet resistance measurements and using it in combination with TEM and EDX analysis we conclude that the cause of this abrupt increase is the presence of large inter-grain layers where silicide is very sparse. On the contrary, NiSi films have no such inter-grain layers, and good resistance values can be obtained even with 0.1 /spl mu/m lines. The NiSi process appears to be a suitable candidate to replace TiSi/sub 2/ in future deep-sub-micron high-speed CMOS devices.< >