Copper Adsorption Behavior on Silicon Substrates

Yoshimi SHIRAMIZU  Makoto MORITA  Akihiko ISHITANI  

IEICE TRANSACTIONS on Electronics   Vol.E76-C   No.4   pp.635-640
Publication Date: 1993/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Sub-Half Micron Si Device and Process Technologies)
Category: Process Technology
metallic impurity,  adsorption behavior,  silicon substrate,  charge transfer reaction,  ion complex,  

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Copper contamination behavior is studied, depending on the pH level, conductivity type P or N of a silicon substrate, and contamination method of copper. If the pH level of a copper containing solution is adjusted by using ammonia, copper atoms and ammonia molecules produce copper ion complexes. Accordingly, the amount of copper adsorption on the substrate surface is decreased. When N-type silicon substrates are contaminated by means of copper containing solutions, copper atoms on the surfaces diffuse into bulk crystal even at room temperature. But for P-type silicon substrates, copper atoms are transferred into bulk crystal only after high temperature annealing. In the case of silicon substrates contaminated by contact with metallic copper, no copper atom diffusion into bulk crystal was observed. The above mentioned copper contamination behavior can be explained by the charge transfer interaction of copper atoms with silicon substrates.