Semiconductor Design Technology Co-Optimization (DTCO) — Bridging Process and Design for Maximum Scaling Benefit

Design Technology Co-Optimization (DTCO) is a collaborative methodology where process technology development and circuit design are simultaneously optimized rather than treated as sequential, independent activities. As traditional transistor scaling delivers diminishing returns, DTCO extracts additional performance, power, and area (PPA) improvements by co-engineering the interactions between device physics, interconnect technology, standard cell architecture, and design rules — often recovering benefits equivalent to a partial node shrink.

DTCO Methodology and Workflow — How process and design teams collaborate:

• Technology pathfinding evaluates multiple process options (device architectures, materials, integration schemes) through their impact on circuit-level metrics rather than device-level parameters alone
• SPICE-to-system modeling propagates device-level changes through compact models, standard cell characterization, block-level synthesis, and system-level benchmarking to quantify real-world PPA impact
• Design rule optimization iteratively adjusts layout constraints (minimum widths, spaces, enclosures) to balance manufacturing yield against circuit density and routing efficiency
• Standard cell architecture exploration evaluates different cell heights, pin access configurations, and transistor arrangements to maximize utilization of the available process capabilities
• Cross-functional teams bring together process engineers, device physicists, library developers, and chip designers in integrated working groups that share data and make joint optimization decisions

Key DTCO Optimization Levers — Where co-optimization delivers the greatest impact:

• Fin depopulation and nanosheet width tuning adjusts transistor dimensions to optimize drive current versus area for different cell types
• Cell height reduction through track height optimization directly reduces logic area but requires co-optimization of pin access and power rail width
• Buried power rail (BPR) moves power lines below the transistor level, freeing routing tracks for signal wires
• Contact-over-active-gate (COAG) allows contacts above the gate electrode, eliminating spacing that wastes cell area
• Self-aligned patterning reduces critical lithography steps by using existing features as alignment references

Standard Cell Library Co-Optimization — The critical interface between process and design:

• Multi-height cell libraries provide cells at different track heights allowing designers to mix compact and high-performance cells
• Pin access optimization ensures cell pins are accessible from the routing grid without design rule violations
• Drive strength granularity provides finely spaced transistor sizing options for power-delay optimization
• Special-purpose cells including scan flip-flops and clock buffers receive dedicated DTCO attention due to their large quantity impact

DTCO at Advanced Nodes — Addressing escalating challenges:

• GAA nanosheet DTCO optimizes sheet count, width, and spacing to balance drive current, parasitic capacitance, and manufacturability at 3 nm and below
• Backside power delivery DTCO co-optimizes through-silicon via placement and backside routing with frontside cell architecture
• EUV patterning DTCO determines optimal mask decomposition and design rule formulation to maximize yield and density benefits
• Interconnect DTCO addresses wire delay dominance through co-optimization of metal pitch, barrier thickness, and routing architecture

DTCO has evolved from an optional enhancement to an essential methodology, delivering PPA improvements rivaling traditional transistor shrinkage by systematically optimizing interactions between manufacturing technology and circuit design.