Sub-110 nm line width standards for accuracy calibration of CD-SEM and CD-AFM

Abstract:
To keep pace with the Total Measurement Uncertainty (TMU) suggested in the International Technology Roadmap for Semiconductors (ITRS), it is necessary to have low tool precision for critical dimensions below 110 nm, and also low-uncertainty, traceable reference standards for tool calibration and matching. The adoption of traceable standards at wafer fabs and reticle shops will help to guarantee that metrology requirements are met through the smallest technology nodes. We present a technique for calibration of accuracy and precision in critical dimension scanning electron microscopy (CD-SEM) and critical dimension atomic force microscopy (CD-AFM) metrology tools for line widths between 13 nm and 110 nm, with accuracy certified as low as +/- 0.5 nm linewidth uncertainty (2 σ) over a 3 mm length. The standard, which also has low line edge roughness, can be used as a monitor for TMU, linearity, magnification and other advanced metrology applications through proper algorithm development. A case study is presented to demonstrate the statistical importance of a unified metrology standard in this regime to wafer foundries and reticle manufacturers.