Signal integrity improvement with peripherally placed MWCNTs in mixed CNT bundle based TSVs

This paper presents a novel method to reduce the crosstalk induced delay in coupled carbon nanotube (CNT) bundle based through silicon vias (TSVs). A unique structure of mixed CNT bundled (MCB) TSV is proposed, wherein multi-walled CNTs (MWCNTs) are placed peripherally to the centrally located single-walled CNTs (SWCNTs). An electrical equivalent model is employed for analyzing these MCB configurations. The analysis demonstrates that a significant reduction in propagation delay and crosstalk induced delay is achieved for a larger number of peripheral layers containing MWCNTs. Moreover, the crosstalk reduction is prominently higher for MWCNTs with more number of shells in longer TSVs. For TSV heights from 30 to 120μm, an average reduction of out-phase, in-phase and propagation delays of 17.54%, 19.73% and 14.45%, respectively, is observed using novel MCB instead of conventional SWCNT bundle based TSV.