System Packaged Cu@CuxO Micro Supercapacitor With Large Capacity for Ultra-Compact Power Module Application

The on-chip micro supercapacitor (MSC), renowned for its exceptional capacitance and power density, holds great potential in compactifying micro systems by replacing bulky dielectric capacitors. However, traditional electrochemical materials and fabrication methods of MSC are incompatible with standard IC processes, posing a significant obstacle to its widespread application. In this paper, we report a novel strategy for fabricating an IC-compatible MSC with ultrahigh capacitance density on wafer-level. Specifically, we design a mesoporous Cu@CuxO material for MSC electrode, in which Cu is a common IC interconnection material with low cost and high conductivity, while CuxO covers Cu to provide large electrochemical capacity. This material is prepared by using standard co-sputtering, selective etching and in-situ oxidation processes sequentially. Subsequently, it is employed to construct high aspect ratio interdigital electrode (nearly $20~\mu $ m thickness) using developed ultra-thick peeling off technology. As a result, the MSC exhibits a superior capacitance density of 35.58 mF/cm2, surpassing commercial dielectric capacitors by 2 orders of magnitude. Furthermore, we propose a unique MSC packaging method based on 3D printing, which includes specially designed microchannels for liquid electrolyte injection and microgrooves for IC chip integration. This packaging method facilitates the integration of MSC with a power management integrated chip (PMIC), forming a System-in-Packaged (SiP) power module. This module, with dimensions of only $3.2\times 2.7\times 1$ mm3, successfully manages the output of a triboelectric nanogenerator, demonstrating its practical application and vast potential.[2024-0073]