| Transistor Architecture | FinFETs, transitioning to Gate-All-Around (GAA) FETs (e.g., MBCFETs) at 3nm and below. Complex 3D structures. | Planar MOSFETs (at 28nm), early FinFETs (at 16/14/12nm). Simpler structures. |
| Lithography & Patterning | EUV (Extreme Ultraviolet) lithography for critical layers is essential. Multi-patterning (e.g., SAQP) for some DUV layers if EUV not fully deployed. Extremely complex and restrictive design rules. | Primarily DUV (Deep Ultraviolet) immersion lithography. Double patterning (DPT) common for critical layers. Simpler design rules. |
| Parasitics (RC) | Interconnect Resistance (R) and Via Resistance are highly dominant over Capacitance (C). Significant impact on wire delay and IR drop. Higher variability in parasitics. Coupling capacitance (Cc) is still a major concern. | Capacitance (C) was often more dominant in interconnect delay compared to Resistance (R). |
| Variability (PVT, OCV) | Very high impact of process variations (Random Dopant Fluctuations - RDF, Line Edge Roughness - LER, Work Function Variation). Statistical timing (e.g., POCV) and variation-aware design are mandatory. | Lower relative impact of process variations. Deterministic timing models (OCV, AOCV) were more commonly sufficient. |
| Operating Voltage (Vdd) | Significantly lower (e.g., < 0.8V, approaching 0.5-0.7V). Smaller noise margins. | Higher (e.g., ~0.9V to 1.V+). Larger noise margins. |
| Leakage Current | Higher relative leakage current due to smaller device dimensions and lower Vt. Complex leakage control mechanisms are vital. | Lower relative leakage current. |
| Power Density & Thermal | Much higher transistor density leads to significantly increased power density and severe thermal hotspots. Thermal management is a critical design constraint. | Lower power density, thermal issues generally more manageable. |
| Design Rules & DFM | Extremely complex, numerous, and restrictive design rules. Extensive Design for Manufacturability (DFM), Design for Yield (DFY), and Design for Reliability (DFR) checks are mandatory. Litho hotspots, CMP effects, stress effects are major concerns. | More relaxed design rules. DFM was important but less acutely critical. |
| Interconnect Materials | Exploration/use of new materials like Cobalt (Co), Ruthenium (Ru) for liners, vias, or even wires to combat high resistance of Cu at very small dimensions. | Predominantly Copper (Cu) interconnects with traditional barrier/liner materials (e.g., Tantalum, Titanium). |
| IR Drop & Electromigration (EM) | More severe due to lower Vdd, higher wire R, and higher current densities. Requires very robust power distribution network (PDN) design. | Less severe compared to lower nodes. |
| Cost (Design & Manufacturing) | Exponentially higher NRE (Non-Recurring Engineering) costs (masks, IP), more complex manufacturing processes, and longer design cycles. | More mature processes with lower NRE costs. |
| Design Complexity | Significantly higher, requiring more sophisticated EDA tools, advanced modeling, and larger design teams. | High, but less complex than cutting-edge nodes. |
| Standard Cell Height | Smaller (e.g., 6-track, 5-track, or even lower). Tighter pin access. | Larger (e.g., 9-track, 10-track, 12-track). Easier pin access. |
