High-Density MIM Capacitors With Porous Anodic Alumina Dielectric

Abstract

We report on the fabrication and electrical characterization of MIM capacitors using as dielectric a thin porous anodic alumina layer between two Al films. The Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /Al stack is grown electrochemically by partly anodizing an Al film on Si, while a top Al film is then deposited on the aluminum oxide and patterned in order to define the capacitor area. The obtained MIM capacitors exhibit at the same time large capacitance density (above ~5 fF/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), low leakage current density (below ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 2 V), and good thermal stability of operation, demonstrated by an a coefficient that changes by less than 10% for temperature changes of the order of 100 K. The temperature stability is further demonstrated by the low leakage current density (below ~7 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) even at temperatures as high as 420 K.