Thin-Film Capacitor Technology for Improving Broadband Power Integrity

Thin-film capacitor (TF cap) technology together with chip-scale packaging (CSP) is studied as a method to achieve broadband power integrity into the gigahertz region. TF cap structures integrated into board-level supply interconnects are analyzed with transmission-line techniques. The behavior of the resulting superlow-impedance transmission lines (SLITs) is illustrated, and the role of TF metal resistance in reducing resonances is highlighted. A single 10-mil-wide-by-100-mil-long SLIT bypass structure supplying a CSP die provides an effective impedance through 6 GHz as low as
$2~\Omega $
. The preliminary measured results from TF caps and SLITs realized on low-temperature cofired ceramic boards are reported, and issues for practical realizations are discussed.