Impact of CNT arrangement on capacitance and inductance in mixed bundles

Increasing limitations of copper interconnect with technology scaling drives us to look for new wiring solutions in high performance IC design. Carbon nanotubes (CNTs) are promising candidates to address this challenge. Here the possibility of using a rearranged mixed bundle structure consisting of single wall carbon nanotubes (SWCNT) and multi wall carbon nanotubes (MWCNT) has been explored. SWCNT and MWCNT exhibit characteristics, which can be better exploited for interconnect application when a combination (in the form of a mixed CNT bundle) of the two is used for short interconnect lengths (0.1 um to 1 um). This combination could provide great performance boost with lower interaction and crosstalk between neighboring CNT bundles. Simulation results and theoretical analysis show that the capacitance and inductance of a CNT depends on the probability of metallic CNTs present in a CNT bundle. Assuming that metal-nanotube contact is perfect, and the contact is maintained only for the outer shell of MWCNT, it is observed that using higher number of MWCNT on the outer periphery of the bundle would aid the bundle performance by acting as shield.