TY - JOUR
T1 - Lead zirconate titanate thin film capacitors on electroless nickel coated copper foils for embedded passive applications
AU - Kim, Taeyun
AU - Kingon, Angus I.
AU - Maria, Jon Paul
AU - Croswell, Robert T.
N1 - Funding Information:
The authors would like to acknowledge generous financial support from Motorola Labs' Physical Realization Research Center of Excellence, Schaumburg, IL, along with useful discussions with many members of their embedded passives team. Dr. Dan Lichtenwalner (NCSU) is also thanked for his careful reading of the manuscript, and helpful suggestions. Partial support from an NSF ITR contract ECS 0113350 is also acknowledged.
PY - 2007/6/25
Y1 - 2007/6/25
N2 - Lead zirconate titanate (PZT, 52/48) thin film capacitors were prepared on electroless Ni coated Cu foil by chemical solution deposition for printed wiring board embedded capacitor applications. Phase development, dielectric properties, and leakage characteristics of capacitors were investigated, in particular as a function of the process temperature. Dielectric properties of the capacitors were dependent on the crystallization temperature, and capacitance densities of more than 350 nF/cm2 and loss tangent of less than 0.03 were measured for capacitors crystallized below 600 °C. Lowest leakage current densities (around 2 × 10- 7 A/cm2 at 10 V direct current (DC)) and highest breakdown fields could be obtained for capacitors crystallized at 650 °C. Capacitors with different thickness and a two-layer capacitor model were used in analyzing the interface layer between PZT and the underlying electroless Ni. From the capacitance and leakage measurements, it is suggested that the interface reaction layer has low permittivity (K around 30) and high defect concentration, which has an important effect on the electrical properties of capacitors. This interface is from the reaction of the electroless nickel layer with the adjacent PZT, and may specifically be moderated by the nickel phosphide (Ni-P) phase, transformed from amorphous Ni during the annealing step. The results have significant implications for embedded capacitors in printed wiring boards. They demonstrate that the process can be tuned to produce either voltage independent capacitors with low leakage and high breakdown fields (above 30 V DC), or the more usual hysteretic, switching, ferroelectric capacitors with higher capacitance densities.
AB - Lead zirconate titanate (PZT, 52/48) thin film capacitors were prepared on electroless Ni coated Cu foil by chemical solution deposition for printed wiring board embedded capacitor applications. Phase development, dielectric properties, and leakage characteristics of capacitors were investigated, in particular as a function of the process temperature. Dielectric properties of the capacitors were dependent on the crystallization temperature, and capacitance densities of more than 350 nF/cm2 and loss tangent of less than 0.03 were measured for capacitors crystallized below 600 °C. Lowest leakage current densities (around 2 × 10- 7 A/cm2 at 10 V direct current (DC)) and highest breakdown fields could be obtained for capacitors crystallized at 650 °C. Capacitors with different thickness and a two-layer capacitor model were used in analyzing the interface layer between PZT and the underlying electroless Ni. From the capacitance and leakage measurements, it is suggested that the interface reaction layer has low permittivity (K around 30) and high defect concentration, which has an important effect on the electrical properties of capacitors. This interface is from the reaction of the electroless nickel layer with the adjacent PZT, and may specifically be moderated by the nickel phosphide (Ni-P) phase, transformed from amorphous Ni during the annealing step. The results have significant implications for embedded capacitors in printed wiring boards. They demonstrate that the process can be tuned to produce either voltage independent capacitors with low leakage and high breakdown fields (above 30 V DC), or the more usual hysteretic, switching, ferroelectric capacitors with higher capacitance densities.
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U2 - 10.1016/j.tsf.2007.02.085
DO - 10.1016/j.tsf.2007.02.085
M3 - Article
AN - SCOPUS:34249049466
SN - 0040-6090
VL - 515
SP - 7331
EP - 7336
JO - Thin Solid Films
JF - Thin Solid Films
IS - 18
ER -