84%-Efficiency Fully Integrated Voltage Regulator for Computing Systems Enabled by 2.5-D High-Density MIM Capacitor

Abstract

We present a mu m-thin-profile power delivery solution including a charge pump with integrated passives. Targeting 1 W/mm(2) or higher power density, a 2.5-D high-density metal-insulator-metal (MIM) capacitor deposited on high aspect ratio (HAR) (up to 5) oxide studs is proposed. With approximately 25-nm-thick HfAlOx dielectric, its measured capacitance density is 25.4 nF/mm(2) for a capacitor size ranging from 1/16 mm(2) to 1 mm(2). This shows 3.6x density improvement compared with the planar MIM. Theoretically, 86 nF/mm(2) density@1.36-V bias can be obtained if a 10-nm dielectric is deposited. Moreover, the measured leakage current density is within 65 pA/mm(2) at 1-V bias (negligible for a 1 W/mm(2)-power delivery). For a backside (BS) power delivery, this 2.5-D MIM capacitor can be realized by only three BS metal layers. This enables the low-cost and thin-profile delivery system (similar to mu m thickness), and the whole power delivery efficiency including a 1/2-ratio charge pump is eta = 84%@1 W/mm(2) (>5% boost in the power efficiency).