Barrier Characteristics of Chemical Vapor Deposited Amorphous‐like Tungsten Silicide with In Situ Nitrogen Plasma Treatment

Abstract

Our team investigated the characteristics of inserting an 80 nm amorphous‐like barrier layer between aluminum film and a shallow diode to retard aluminum and silicon interdiffusion. In one chamber without breaking vacuum, we used a nitrogen plasma treatment to stuff nitrogen atoms into the grain boundaries of amorphous‐like tungsten silicide film. The nitrogen atoms eliminated the fast diffusion paths of film, thus giving the amorphous‐like tungsten silicide film a smaller diffusion coefficient. We then examined the failure of diodes with amorphous‐like barriers which were annealed at 575°C for 30 min and which had leakage currents of and . These diodes failed due to the diffusion of aluminum along the sidewalls of the barriers and the field oxide interface. In the search for a solution to this problem we investigated the use of tetraethylorthosilicate, which is known for its thermal stability as a stress buffer. In this experiment we used tetraethylorthosilicate to form a “contact array structure” which in turn prevented diode failure at 575°C annealing for 30 min, and furthermore, the diodes in the contact array structure only began to show evidence of degradation at 600°C. © 1999 The Electrochemical Society. All rights reserved.