Extrasmall-Area Three-Dimensional Solenoid-Shaped Inductor Integrated into High-Speed Signal Processing Complementary Metal–Oxide–Semiconductor Ultralarge-Scale Integrated Circuits

Abstract

Using fine-pitched ultralarge-scale integrated (ULSI) circuit local interconnects, an extrasmall-area, three-dimensional (3-D) solenoid-shaped inductor is developed for scaled-down high-speed logic LSIs. The 3-D solenoid inductor has a four-layered solenoid structure with fine-pitched local low-k/Cu interconnects, achieving an area reduction from 1/6 to 1/10 of the area of a conventional monolayer-spiral inductor using wide-pitched global interconnects. The small area also suppresses the crosstalk due to the compaction of the magnetic field around the inductor. The 3-D solenoid structure has a higher self-resonant frequency than a stacked-spiral inductor of the same area or the same inductance due to a small effective parasitic capacitance. A 20 Gb/s D-type flip-flop (D-F/F) using the 3-D solenoid inductor for peeking demonstrated a smaller degree of jitter than that using a monolayer-spiral inductor under a 1 V power supply. The 3-D solenoid inductor is a key component for scaled-down high-speed logic LSIs with a low power supply voltage.