Investigation on the Effects of Interconnect RC in 3nm Technology Node Using Path-Finding Process Design Kit

Abstract

With the continuous development of front-end-of-line (FEOL) technology, the development of interconnection processes at nanoscale process nodes is becoming important. We conducted a post-layout circuit simulation to consider the effect of parasitic R and C components of middle-of-Line (MOL) and back-end-of-line (BEOL) on the circuit performance. We constructed a process design kit (PDK) for path-finding to analyze the circuit layout in a 3nm technology node based on gate-all-around FET (GAA-FET). It consists of the spice model library that satisfies the 3nm power performance area (PPA) target, and the layout versus schematic (LVS), parasitic extraction (PEX) model that checks whether the layout and schematic match, extracts the RC values in the FEOL MOL and BEOL areas. Subsequently, the effect of the interconnection on complex logic circuits (RO, full adder) was confirmed using PDK. As a result of quantifying the effects of FEOL, MOL, and BEOL on the circuit, circuit degradation due to the RC of MOL and BEOL accounts for more than 60%. Furthermore, we introduced the air spacer process as a way to improve the circuit performance by reducing the CMOL owing to the reduction in the dielectric constant of the spacer. When an air spacer is introduced, based on 9-stages FO1 INV RO with k = 7 at V_DD = 0.7V, under iso-speed condition, the active power decreases by 30%, 35% when k is 3.3, 1.65, respectively. Under iso-power condition, frequency increases by 9%, 11% when k is 3.3, 1.65, respectively. And based on full adder with k = 7 at V_DD = 0.7V, Under iso-speed conditions, the active power decreases by 47%, 58% when k is 3.3, 1.65, respectively. Under iso-power conditions, the delay decreases by 14%, 20% when k is 3.3, 1.65, respectively. PDP decreases by 22%, 32% when k is 3.3, 1.65, respectively. EDP decreases by 31%, 44% when k is 3.3, 1.65, respectively. In conclusion, in this work, we provide a guide for determining the BEOL load and developing an improved wiring process.