The SEMATECH high-NA actinic reticle review project (SHARP) EUV mask-imaging microscope

The SEMATECH high-NA actinic reticle review project (SHARP) EUV mask-imaging microscope Kenneth A. Goldberg,*a Iacopo Mochif‘ Markus P. Benkf‘ Chihcheng Lin,b Arnaud Allezy,a Michael Dickinsonf‘ Carl W. Cork,a James B. Macdougallf Erik H. Andersonf‘ Weilun Chao,a F arhad Salmassif‘ Eric. M. Gulliksonf Daniel Zehm,a Vamsi Vytlaf‘ William Cork,” Jason DePonte,a Gino Picchif‘ Ahmet Pekedisf Takeshi Katayanagif Michael G. J ones,a Elizabeth Martinf‘ Patrick P. Naulleauf and Senajith B. Rekawaa aLawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA USA 94720; bSEMATECH, 257 Fuller Rd. Suite 2200, Albany, NY USA 12203 ABSTRACT The SEMATECH High Numerical Aperture Actinic Reticle Review Project (SHARP) is a newly commissioned, synchrotron-based extreme ultraviolet (EUV) microscope dedicated to photomask research. SHARP offers several major advances including objective lenses with 4XNA values from 0.25 to 0.625, flexible, lossless coherence control through a Fourier—synthesis illuminator, a rotating azimuthal plane of incidence up to i25°, illumination central ray angles from 6 to 10°, and a continuously tunable, EUV illumination wavelength. SHARP is now being used to study programmed and native mask defects, defect repairs, mask architecture, optical proximity correction, and the influence of mask substrate roughness on imaging. SHARP has the ability to emulate a variety of current and future lithography tool numerical apertures, and illumination properties. Here, we present various performance studies and examples where SHARP’s unique capabilities are used in EUV mask research. 1. INTRODUCTION The SEMATECH High—NA Actinic Reticle review Project (SHARP) microscope is a new, synchrotron-based extreme ultraviolet (EUV, l3.5—nm wavelength) microscope created to support advanced photomask research for the semiconductor industry. The microscope serves photolithography generations to the year 2020 and beyond, when printed feature sizes are expected to fall below 10 nm. SHARP is designed to emulate the optical properties of current and future EUV lithography tools, enabling the study of mask defects, pattern architectures, optical proximity correction, phase- shifting patterns, and more.“2‘3 SHARP, which was commissioned in Spring 2013 is the successor to the SEMATECH Berkeley Actinic Inspection Tool (AIT) which was decommissioned in September, 2012 after eight years of operation. Owing to their highly wavelength—specif1c optical properties, the creation of production-quality EUV masks may come to rely upon dedicated EUV—wavelength mask-blank inspection and/or pattem-imaging tools. With commercial tools still months to years years from deployment, SHARP was created by an industry/govemment partnership to provide advanced research and development capabilities. SHARP utilizes several advanced short—wavelength optical elements and systems, including an array of user-selectable Fresnel zoneplate lenes to achieve high spatial resolution imaging, and a lossless, Fourier synthesis illuminator4 to provide customizable coherence control. The zoneplate lenses are fabricated with electron-beam lithography in a free- standing nickel absorber membrane featuring a stenciled design for mechanical strength. A number of lenses are available with 4XNA values ranging from 0.25 to 0.625 and five separate azimuthal angles between —25° and +25° to reproduce a rotating plane of incidence across the aperture of a ring-field system. SHARP’s mechanical design and vibration isolation strategy have been described previously} SHARP’s monochromator enables illumination with a tunable wavelength and a AE/E bandwidth that is typically below 1/1450. Multilayer mirrors limit the usable range to approximately 13.2-13.7 nm. In its first four months of operation, SHARP has been used to study patterned and native defects, repairs, mask architecture, multilayer surface roughness, line-edge rouglmess, and the dependence of imaging on illumination properties. This last subject is particularly well aligned with SHARP’s measurement capabilities.