Interface Properties of Nickel-silicide Films Deposited by Using Plasma-assisted Atomic Layer Deposition

Abstract

Nickel was deposited by using plasma-assisted atomic layer deposition (PAALD) with a Bis-Ni precursor and H(2) reactant gas at 220 degrees C with a deposition rate of 1.55 angstrom/cycle. The as-deposited nickel film exhibited a very low sheet resistance (R(s)) of 3.10 Omega/square with a cubic structure. The films were silicided by using a rapid thermal process (RTP) which was performed by varying the temperature from 400 degrees C to 900 degrees C in a nitrogen ambient. The obtained sheet resistances of the nickel-silicide films were 1.95 similar to 2.50 Omega/square in the annealing temperature range of 500 similar to 800 degrees C. The interface and crystalline properties of the films were analyzed by using X-ray diffraction (XRD) the Anger electro spectroscopy (AES) depth profile and high resolution transmission electron microscopy (HRTEM) with selected-area electron diffraction (SAD) From the XRD data, the as-deposited nickel film exhibited a good crystalline structure. The NiSi structure was obtained in the temperature range from 500 similar to 600 degrees C with a low sheet resistance. On the other hand below 400 degrees C and around 700 similar to 800 degrees C the films showed no diffraction peak with a phase transition. Also, using by the AES depth profile, we verified that the observed interface of the films was clean without a notable oxide formation. We can conclude that the properties of films fabricated using ALD and RTP methods are better than those of the films fabricated using the conventional physical vapor deposition method.