target value

Target Value in SPC is the ideal, optimal value for a measured parameter — the nominal design value around which specifications are set, representing the center of the specification range where the product performs best or the process is most robust.

Target Value Context

• Design Nominal: The intended value from the design — e.g., 28nm target CD for a 28nm gate.
• Best Performance: The value that optimizes device performance — may differ from the spec center.
• Process Center: Ideally, the process mean equals the target value — perfectly centered process.
• Offset: Sometimes the target is intentionally offset from the spec center to account for downstream processing.

Why It Matters

• Taguchi: The Taguchi loss function says quality loss increases as the parameter deviates from target — even within spec.
• Centering: Centering the process on target maximizes process capability (Cpk approaches Cp).
• APC: Advanced Process Control (APC) systems target the nominal value — run-to-run controllers adjust recipes to maintain on-target.

Target Value is the bullseye — the optimal nominal value that represents perfect process centering and best product performance.