A Thermally Stable and High-Performance 90-nm ${\rm Al}_{2}{\rm O}_{3}\backslash{\rm Cu}$-Based 1T1R CBRAM Cell

Abstract

In this paper, we optimize the stack of a 90-nm CMOS-friendly <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm W}\backslash{\rm Al}_{2}{\rm O}_{3}\backslash{\rm Cu}$</tex></formula> conductive-bridging random access memory cell integrated in the one-transistor/one-resistor configuration. We show that the excellent Cu buffering properties of a TiW layer inserted at the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm Al}_{2}{\rm O}_{3}\backslash{\rm Cu}$</tex></formula> interface make it possible, on one hand, to ensure cell integrity after back-end-of-line processing at 400 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$^{\circ}{\rm C}$</tex></formula> and, on the other, to obtain excellent memory performances. After optimization of the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm Al}_{2}{\rm O}_{3}$</tex></formula> layer thickness, the cell exhibits highly controlled set and reset operations, a large memory window, fast pulse programming (10 ns) at low voltage <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$({&lt;}{\rm 3}~{\rm V})$</tex></formula> , and low-current (10 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm A}$</tex></formula> ), and multilevel operation. Finally, <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10^{6}$</tex></formula> cycles of write endurance lifetime with up to a three-decade memory window is demonstrated, and state stability is assessed up to 125 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ}{\rm C}$</tex></formula> .