Symmetric Vertical Parallel Plate Capacitors for On-Chip RF Circuits in 65-nm SOI Technology

Abstract

This letter presents symmetric vertical parallel plate (VPP) capacitors in 65-nm silicon-on-insulator CMOS technology. Three VPP capacitors with different metal layer options are examined with respect to effective capacitance density and Q-factor. An effective capacitance of 2.18 fF/µm 2 and a Q-factor of 23.2 at 1 GHz are obtained from a 1x + 2x (M1-M6) metal layer configuration's pre-de-embedding measurement. VPP capacitor symmetry, mismatch, leakage current density, vertical scalability, and variation characteristics from a 300-mm wafer are discussed. Index Terms-Radio frequency (RF) passive component, vertical and horizontal scalability, vertical native back-end-of-line (BEOL) capacitor, vertical parallel plate (VPP) capacitor, 65-nm silicon-on-insulator (SOI) CMOS technology.

Electrical performance of vertical natural capacitor for RF system-on-chip in 32-nm technology

“…The last three key parameters are derived from the admittance parameter by the electromagnetic solver and a Pi-type equivalent circuit model of the VNCAP. Although measurement data for VNCAPs in 32-nm technology are not available, we performed simulation on VNCAPs in 65-and 45-nm technology, and the simulation results correlate well with experimental data reported in [3] and [4]. Our study shows that the capacitance densities of VNCAPs in 32-nm technology can be as high as 5.79 2 fF/μm with a self-resonant frequency of 9.5 GHz, and a quality factor of 104.7 at 1GHz.…”

“…Note that since the actual dimensions of the BEOLs in 32-nm (T32) technology are not available in open literature, the dimensions shown Fig. 1(b) are based on partial data from [3,4,6] and by applying a 0.7x scaling factor [7]. Fig.…”

“…Unlike MIM capacitors, VNCAPs do not require additional process steps during wafer fabrication, and can be built by conventional back-end-of-line (BEOL) technology in CMOS. Beyond 65 nm technology the capacitance density of the VNCAP is comparable to that of the MIM capacitor [3,4]. Therefore, the VNCAP becomes an attractive alternative of an MIM capacitor in RF SoC.…”

“…VNCAPs were studied experimentally in 65 nm technology in [3] and 45 nm technology in [4]. Performance of VNCAPs in 32 nm technology has not yet been reported, and studying VNCAP by RF modeling and simulation instead of measurement was rarely found in the literature.…”

“…A new design of the VNCAP is finally presented to increase its capacitance density by adding side fingers to its main interdigited fingers. [3,4,6], or are scaled parameters by a factor of 0.7 [7].…”