I. INRTODUCTION
Recently, with the rapid development of the technologies of terahertz, various passive and active components in terahertz monolithic integrated circuit (TMIC) are designed by using different technologies [1]–[2]. As a result, there are some terahertz applications in terahertz imaging, terahertz detection and terahertz communication [3]. However, along with high integration features required for the increasingly high demands, some efforts among different passive devices such as filters have been made [4], and a defected ground structure structure is adopted for higher harmonic rejection in the stopband [5]. Moreover, the MIM capacitors play an important role in TMIC design, and the capacitors are wildly used in matching, DC blocking and coupling. Besides, an accurate model will decrease the iteration times between layout and EM-schematic co-simulation. The mainstream MIM capacitor models include line-capacitor-line (LCL) model, couple line (CL) model, lumped model, and open-stub-line (OL) model [6]–[8]. However, the accuracy and reliability of the model is affected by sensitive components to parasitic effects at terahertz frequency. The emergence of the 3D electromagnetic simulation method make it possible to characterize various effects operating at terahertz frequencies. In recent years, several attempts using the three dimension electromagnetic simulation based parameters extraction method have been reported [9]–[10].