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A novel angle-resolved scatterometer based on pupil optimization for feature profile measurement in a photolithography process is proposed. The impact of image sensor errors is minimized by optimizing the intensity distribution of the incident light using a spatial light modulator. The scatterometry sensitivity of feature measurement at different polarization conditions is calculated using the rigorous coupled-wave and first-order analyses, and the reproducibility of the scatterometer is evaluated. The results show that the sensitivity and reproducibility of the angle-resolved scatterometer increase by 90% and 40% with pupil optimization, respectively.

The impact of lens aberrations becomes severe when the critical dimensions (CDs) shrink. The accurate measurement of both low- and high-order Zernike aberrations is important during a photolithographic process. Based on the multi-illumination settings and principal component analysis of aerial images, a novel in situ aberration measurement technique that can accurately measure all the Zernike aberrations, except for the sinusoidal 2-\theta and sinusoidal 4-\theta terms (under polar coordinates, and Z1 to Z4 are not considered) is proposed in this letter. The estimated maximum error of the Zernike aberrations ranges from 0.43 to 0.78 m\lambda when the amplitudes of the Zernike coefficients range from –20 to 20 m\lambda. The standard and root mean square errors are both in the range from 0.14 to 0.4 m\lambda.