# Electrical Coupling of Monolithic 3D Inverters (M3 INVs): MOSFET and Junctionless FET
## 5 Conclusions  
In this paper, we investigated the electrical coupling through the threshold voltage, transconductance, and gate capacitance variation according to \(T_{ILD}\) of M3 INV-MOS and M3 INV-JL through TCAD simulation and compared the VTC and \(V_{m}\) and SNM characteristics in M3 INV-MOS and M3 INV-JL. In both M3 INV-MOS and M3 INV-JL, \(\Delta V_{th}\), \(\Delta V_{gm}\), and \(\Delta V_{Cheng}\) increase as \(T_{ILD}\) decreases. The smaller \(L_{G}\), the larger \(\Delta V_{th}\) and \(\Delta V_{gm}\), but \(\Delta V_{Cheng}\) is not significant. In addition, as \(T_{ILD}\) increased, M3 INV-MOS and M3 INV-JL shifted VTCs from right to left and from left to right, respectively. The larger \(L_{G}\), the larger and smaller \(\Delta V_{m}\) of M3 INV-MOS and M3 INV-JL, respectively. The noise margin and inverter characteristics of M3 INV-MOS is larger and better than those of M3 INV-JL. M3 INV-MOS has less electrical coupling in terms of \(\Delta V_{th}\), \(\Delta V_{Sm}\), \(\Delta V_{Cheng}\), \(\Delta V_{m}\), \(NM_{H}\), \(NM_{L}\), and propagation delay than M3 INV-JL. When \(T_{ILD}\) is over 30 nm, \(\Delta V_{th}\), \(\Delta V_{gm}\), and \(\Delta V_{Cheng}\) are below 50 mV, \(\Delta V_{m}\) are below 10 mV, the maximum variations of \(\text{SNM}\) of both M3 INV-MOS and M3 INV-JL are below 20 mV, and the maximum variations of propagation delay of both M3 INV-MOS and M3 INV-JL are below 0.2 ps, and thus the coupling in the structures can be ignored.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{\(L_{G}\)} & \multicolumn{2}{c}{**20 nm**} & \multicolumn{2}{c}{**30 nm**} & \multicolumn{2}{c}{**50 nm**} \\ \cline{2-7}  & **MOS** & **JL** & **MOS** & **JL** & **MOS** & **JL** & **MOS** & **JL** \\ \(T_{ILD}\) & **Delay [ps]** & **Delay [ps]** & **Delay [ps]** & **Delay [ps]** & **Delay [ps]** & **Delay [ps]** & **Delay [ps]** \\ \hline
5 nm & 4.42 & 4.18 & 4.56 & 4.58 & 6.56 & 5.84 \\
10 nm & 4.39 & 4.82 & 4.52 & 5.21 & 6.5 & 6.42 \\
30 nm & 4.37 & 5.43 & 4.49 & 5.57 & 6.43 & 6.93 \\
50 nm & 4.36 & 5.52 & 4.48 & 5.7 & 6.42 & 7.01 \\
70 nm & 4.35 & 5.55 & 4.47 & 5.72 & 6.41 & 7.06 \\
100 nm & 4.34 & 5.57 & 4.46 & 5.74 & 6.4 & 7.1 \\ \hline \end{tabular}
\end{table}
Table 2: Propagation delay of M3 INV-MOS and M3 INV-JL at different \(L_{\delta}\)s and \(T_{ILD}\)s.  
Figure 10: Transient responses at different \(T_{ILD}\)s. (**a**) M3 INV-MOS cell and (**b**) M3 INV-JL cell. Here \(L_{G}\) = 20 nm and \(V_{all}\) = 1 V.  
**Author Contributions:** Conceptualization, T.J.A. and Y.S.Y.; methodology, T.J.A. and Y.S.Y.; investigation, T.J.A. and Y.S.Y.; data curation, T.J.A.; writing--original draft preparation, T.J.A.; writing--review and editing, T.J.A. and Y.S.Y.; supervision, Y.S.Y.; project administration, Y.S.Y.; funding acquisition, Y.S.Y. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1A2C1085295).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The raw/processed data required to reproduce these findings will be shared upon request from the corresponding author.  
This work was supported by IDEC (EDA tool).  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.