Spike Annealing as Second Rapid Thermal Annealing to Prevent Pure Nickel Silicide From Decomposing on a Gate

Abstract

To create a nickel-monosilicide (NiSi) film with superior electrical properties, two-step rapid thermal annealing (RTA) was optimized. Using <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> chemical dry cleaning and increasing initial RTA temperature makes it possible to macroscopically transform nickel into NiSi without causing oxygen contamination. Nevertheless, di-nickel silicide (Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Si) remaining on the top surface of NiSi on p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -doped gate degrades the electrical properties of the NiSi film. This top-surface Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Si is formed by decomposition of NiSi by conventional second RTA and appears as a disconnection of the NiSi film on the logic test device or agglomeration of silicon and nickel on the blanket NiSi film with activation energy of 2.92 eV. Using ldquospike RTArdquo with higher temperature suppresses the decomposition of NiSi and activates transformation of Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Si to NiSi. It is concluded that the proposed two-step RTA significantly improves the uniformity of the electrical properties of NiSi in 65-nm-node logic devices.