title: Fabrication and Characteristics of High Capacitance Al Thin Films Capacitor Using a Polymer Inhibitor Bath in Electroless Plating Process.
abstract: An aluminum (Al) thin film capacitor was fabricated for a high capacitance capacitor using electrochemical etching, barrier-type anodizing, and electroless Ni-P plating. In this study, we focused on the bottom-up filling of Ni-P electrodes on Al2O3/Al with etched tunnels. The Al tunnel pits were irregularly distributed on the Al foil, diameters were in the range of about 0.5~1 μm, the depth of the tunnel pits was approximately 35~40 μm, and the complex structure was made full filled hard metal. To control the plating rate, the experiment was performed by adding polyethyleneimine (PEI, C2H5N), a high molecular substance. PEI forms a cross-link at the etching tunnel inlet, playing the role of delaying the inlet plating. When the PEI solution bath was used after activation, the Ni-P layer was deposited selectively on the bottoms of the tunnels. The characteristics were analyzed by adding the PEI addition quantity rate of 100~600 mg/L into the DI water. The capacitance of the Ni-P/Al2O3 (650~700 nm)/Al film was measured at 1 kHz using an impedance/gain phase analyzer. For the plane film without etch tunnels the capacitance was 12.5 nF/cm2 and for the etch film with Ni-P bottom-up filling the capacitance was 92 nF/cm2. These results illustrate a remarkable maximization of capacitance for thin film metal capacitors.
authors.forename: Young-Lae
authors.initials: YL
authors.lastname: Cho
authors.forename: Jung-Woo
authors.initials: JW
authors.lastname: Lee
authors.forename: Chang-Hyoung
authors.initials: CH
authors.lastname: Lee
authors.forename: Hyung-Seon
authors.initials: HS
authors.lastname: Choi
authors.forename: Sung-Su
authors.initials: SS
authors.lastname: Kim
authors.forename: Young Il
authors.initials: YI
authors.lastname: Song
authors.forename: Chan
authors.initials: C
authors.lastname: Park
authors.forename: Su-Jeong
authors.initials: SJ
authors.lastname: Suh