A highly reliable interconnection for a BF⁺ ₂-implanted junction utilizing a TiN/Ti barrier metal system

Abstract

A submicrometer-rule interconnection structure of the Al-Si layer to the BF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -implanted Si region is described. The contact resistance of Al-Si to BF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -implanted Si increases more than those to B <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> - or As <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -implanted Si, as contact hole size is scaled down to around 1 µ2. Through SEM and TEM analyses, it is found that solid phase epitaxial growth of Si takes place on the contact interfaces, where crystalline defects induced by BF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> implantation act as seeds. Thus, the effective metal contact area to Si is reduced very much. In order to realize a stable metallization system, a TiN/Ti barrier metal structure is introduced. The TiN/Ti structure is optimized in terms of contact resistance and contact barriers, and its feasibility for submicrometer-rule CMOS VLSI's is clarified.