CMOS Detector using Customized Bolt-Wrench Capacitor on Backend Oxide Layer

A CMOS detector with a customized capacitor is proposed to improve the detection performance for terahertz imaging systems. The proposed gate-drain capacitor is formed based on the bolt-wrench shape integrated into the layout design of the detector core. The proposed capacitor is implemented using a metal-insulator-metal stack in the backend oxide layer of the TSMC 0.25- $\mu \text{m}$ CMOS technology. The detector using the customized capacitor exhibits an 18% improvement in the voltage responsivity simulation compared to the detector using the capacitor in the process design kit (PDK). The measurement results of the detector, including the integrated antenna and amplifiers, indicate a voltage responsivity of 2.99 MV/W and a noise-equivalent power of 46.3 pW/ $\surd $ Hz. The 200-GHz images obtained using the proposed detector demonstrate a 30% correlation improvement with the sample compared to the images obtained using the detector with the PDK capacitor.