Analysis of Resistance Behavior in Ti-and Ni-Salicided Polysilicon Films

Tatsuya Ohguro, Shin ichi Nakamura, Mitsuo Koike, Toyota Morimoto, Akira Nishiyama, Yukihiro Ushiku, Takashi Yoshitomi, Mizuki Ono, Masanobu Saito, Hiroshi Iwai

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139 Scopus citations

Abstract

The sheet resistance of TiSi2-polycide (TiSi2- 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 < 0.2 µm 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 µm lines. The NiSi process appears to be a suitable candidate to replace TiSi2 in future deep-sub-micron high-speed CMOS devices.

Original languageEnglish
Pages (from-to)2305-2317
Number of pages13
JournalIEEE Transactions on Electron Devices
Volume41
Issue number12
DOIs
StatePublished - Dec 1994

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