Simulation Analysis of the Characteristics of a High Magnification Imaging Optics for the Observation of Extreme Ultraviolet Lithography Mask to Predict Phase Defect Printability

Abstract

By employing simulation, we analyzed the characteristic of the optics of high-magnification multilayer-coated mirror employed for the examination of extreme ultraviolet lithography (EUVL) mask, and we also examined the performance of phase defect printability prediction. The imaging optics comprises Schwarzschild optics and a concave mirror; and it is modeled as an imaging means with an annular-shaped pupil. In this simulation, tilted coherent illumination that was successfully applied in an EUV microscope constructed at a beamline of the NewSUBARU, was assumed. Observation images of mask patterns affected by phase defects were simulated assuming EUVL masks representing half pitches of 16 and 11 nm generations; and those simulated results were compared with the simulated reduction-projection images on wafer formed by an exposure tool. Although the high-magnification observation optics does not completely emulate the printed pattern images on wafer it predicts the existence of phase defects and predict the value of their impacts.

Analysis of image distortion on projection electron microscope image

“…9) Especially the ULSI wafer with several types of insulators such as SiO 2 , Si 3 N 4 , HfO 2 , and wafers with three-dimensionally-stacked pattern such as contact/via hole patterns lead to the difficulty for the homogenization of the surface potential. We have been developing a projection electron microscope (PEM) [7][8][9][10] for patterned photomask inspection for extreme ultraviolet (EUV) lithography; [11][12][13][14] and we have evaluated its feasibility. [15][16][17][18][19][20][21][22] PEM is one of the electron microscope techniques that is based upon the imaging EO, and has an advantage of giving a considerably higher throughput than achievable in the case of conventional scanning electron microscope (SEM) type inspection system.…”

Recent results from EUVL patterned mask inspection using projection electron microscope system

“…From the simulation, it is learned that more than 13 nm extrusion defect, or more than 20 nm intrusion defect, can cause more than 10% Critical Dimension (CD) error for hp 11 nm EUV lithography. 15 These values have roughly met the specifications as prescribed by the ITRS 2013 Edition. So for hp 11 nm node EUV mask pattern defect detection, we targeted on defects larger than 11 nm.…”

“…[1][2][3][4][5][6] As prescribed by the ITRS 2013 Edition, and based on defect printability simulation, the sensitivity requirement for EUV patterned mask inspection system at sub-16 nm nodes is investigated. 14, 15 We have designed a novel Projection Electron Microscopy (PEM) system, which has proven to be quite promising for hp 1Xnm node mask inspection. [7][8][9][10][11][12] Currently, the PEM optics is integrated with a pattern inspection system for the defect detection sensitivity evaluation.…”

Extreme ultraviolet patterned mask inspection performance of advanced projection electron microscope system for 11nm half-pitch generation

“…[1][2][3][4][5] According to the 2013 International Technology Roadmap for Semiconductors (ITRS 2013) and based on defect printability simulations, the required sensitivity for an EUVL patterned mask inspection system must be better than 13 nm for inspection of hp 11-nm node devices. 6,14,15 We have already designed novel projection electron microscope (PEM) optics that have been integrated into a new inspection system named EBEYE-V30 ("Model EBEYE" is an EBARA's model code) and this system has shown promise for hp 16-nm node EUVL patterned mask inspection. [7][8][9][10][11][12][13] Improvement of the inspection throughput for 11-nm hp generation defect detection would require a data processing rate of more than 1.5 gigapixels per second (GPPS) to provide an inspection time of less than 8 hours.…”