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February 1, 2008

Characterization of the Poly Gate ACI Structure with Multiple Wavelength Scatterometry

Presented at SPIE 2008

Optical metrology techniques are essential for process control of gate formation process steps from lithography to the dielectric, spacers, gate and straining layer deposition in sub-90 nm technology nodes. Traditionally, optical metrology is based on the measurement of periodic lines or hole arrays using a spectroscopic ellipsometer or reflectometer, collecting data across a wide wavelength spectrum at a single angle of incidence. In this paper, we present results of measurements on periodic Poly-Si gate line arrays using laser based Focused Beam Scatterometry (FBS), illuminating at 3 discrete laser wavelengths while data is collected over an angle of incidence range from 45° to 65°. Accuracy, repeatability, and tool-to-tool matching results for the poly-Si gate line arrays are discussed. Comparison with the CD-SEM and cross-section TEM result for measurement/modeling accuracy is also presented.

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