Effects of nickel and palladium activations on the adhesion and I-V characteristics of As-plated electroless nickel deposits on polished crystalline silicon

• Published in: Journal of the Electrochemical Society 2004, Vol.151 (9), p.C554-C558
• Main Authors: KARMALKAR, Shreepad, PRADEEP KUMAR, V
• Format: Article
• Language: English
• Subjects: Cross-disciplinary physics: materials science; rheology; Electrodeposition, electroplating; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics
• ISSN: 0013-4651; 1945-7111
• DOI: 10.1149/1.1773582

We present a study of the adhesion and current-voltage characteristics of as-plated electroless nickel deposits on polished crystalline silicon activated using nickel and palladium. A highlight of this study is the derivation of practically significant trends by collating the results of a large number of simple experiments as a function of substrate doping polarity, doping level, plating area, and plating duration. The study reveals that palladium activation is most effective on P+ substrates while nickel activation is most effective on N+ substrates, due to the requirement of substrate holes in the former activation and electrons in the latter. An activation process always improves adhesion, but, in some cases, degrades the electrical properties of the plating-silicon interface, because it introduces an intermediate silicide layer between nickel and silicon. Electroless nickel layer adheres better to nickel activated silicon, than to palladium activated silicon. However, the rectifying nature of the electroless nickel contacts on palladium activated silicon is superior to those on nickel activated silicon. Further, palladium silicide forms at 200DGC, which is much lower than the temperature of 400DGC required for nickel silicide formation.