84%-Efficiency Fully Integrated Voltage Regulator for Computing Systems Enabled by 2.5-D High-Density MIM Capacitor
Hesheng Lin, Dimitrios Velenis, P. Nolmans, Xiao Sun, Francky Catthoor, Rudy Lauwereins, Geert Van der Plas, Eric Beyne
Abstract
We present a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> -thin-profile power delivery solution including a charge pump with integrated passives. Targeting 1 W/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> 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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> for a capacitor size ranging from 1/16 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> to 1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . This shows <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.6\times $ </tex-math></inline-formula> density improvement compared with the planar MIM. Theoretically, 86 nF/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> [email protected] bias can be obtained if a 10-nm dielectric is deposited. Moreover, the measured leakage current density is within 65 pA/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 1-V bias (negligible for a 1 W/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -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 ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim \!\!\mu \text{m}$ </tex-math></inline-formula> thickness), and the whole power delivery efficiency including a 1/2-ratio charge pump is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\eta \,\,=84$ </tex-math></inline-formula> %@1 W/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (>5% boost in the power efficiency).