Optimized structure of standard sample with programed defects for pattern inspection using electron beams

Abstract

Standard samples with programed defects, designed to evaluate pattern inspection tools that use electron beams, were fabricated on 12-in. Si wafer. By using a structure with a conductive pattern on an insulator layer, scanning electron microscope (SEM) images with various pattern contrasts, depending on the charging effect, were obtained under different observation conditions. The impact of captured-image contrast on defect detection capability was examined using different types of inspection algorithm. It was found that the accuracy of critical dimension measurement, effectiveness of the charge suppression technique, and defect detection capability of the SEM tool, and its robustness could all be evaluated using this standard sample with a particular stacked structure.

Role of landing energy in e-beam metrology of thin photoresist for high-numerical aperture extreme ultraviolet lithography

“…Additionally, the imaging contrast can be controlled by changing the landing energy (LE). 3 In general, in the case of thinner resist, the pattern is expected to have a better contrast at such lower landing energies, where the interaction volume is smaller, as illustrated in Fig. 1(a) for a situation where the underlayer is not charged.…”

“…In this regime, the number of secondary electrons emitted from the resist line is larger than the number of primary electrons penetrating the sample, so that the surface will become positively charged. [3][4][5] However, although charging of the resist and the underlayer is expected when shifting toward the low LE regime, the charging artifacts will have different magnitudes, as they depend on the different material yield curves for resist and underlayer. Moreover, the trajectory of the emitted electrons from the resist line edge might be influenced by charging in the underlayer as shown in Fig.…”

“…Lower landing energies are attractive for imaging the thin resist because of the smaller interaction volume between the electrons and the sample, hence higher lateral surface sensitivity. Additionally, the imaging contrast can be controlled by changing the landing energy (LE) 3 . In general, in the case of thinner resist, the pattern is expected to have a better contrast at such lower landing energies, where the interaction volume is smaller, as illustrated in Fig.…”

“…Considering the typical secondary (or total) electron emission yield curves of the material, the yield becomes >1 when lowering the LE. In this regime, the number of secondary electrons emitted from the resist line is larger than the number of primary electrons penetrating the sample, so that the surface will become positively charged 3 – 5 However, although charging of the resist and the underlayer is expected when shifting toward the low LE regime, the charging artifacts will have different magnitudes, as they depend on the different material yield curves for resist and underlayer.…”