Ultra-thin on-chip ALD LiPON capacitors for high frequency application

Abstract

Multi-layer ceramic capacitors have been used for high frequency decoupling application due to a lower overall impedance leading to fast current response. However, high parasitic inductance limits the application of these capacitors in ultra-high frequency domain. Thus, Multlayer Ceramic Capacitors (MLCCs) are placed close to the IC to improve circuit efficiency and reduce inductance. With next generation applications, the demand for frequency range has further increased which not only requires enhanced capacitor material but improved manufacturing techniques to limit the inductive path. Here, we demonstrate ALD of two different polymorphs of ultra-thin film lithium phosphorus oxynitride (LiPON) as an inorganic solid state electrolyte (SSE) for on chip capacitors for decoupling application. Both the LiPON capacitors shows an electric double layer behavior with a capacitance of 15 μF/cm2 and a low leakage current (<20 nA/cm2) at 2V. The LiPON shows EDLC behavior up to 10 kHz and beyond, both the polymorphs show an electrostatic behavior with a high dielectric constant (14). This dual frequency behavior along with low parasitic inductance and on chip integration allows for operation in extended frequency ranges.