Through-pellicle inspection of EUV masks

Mochi, Iacopo; Rajeev, Rajendran; Helfenstein, Patrick; Fernandez, Sylvie; Kazazis, Dimitrios; Ekinci, Yasin

doi:10.1117/12.2297436

Cited by 2 publications

(3 citation statements)

References 11 publications

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“…After the exposure and development, the HSQ structures have a thickness of ~140 nm, providing sufficient absorption at EUV wavelengths. Such HSQ absorber patterns have previously been used, showing good image contrast [2,3,4].…”

Section: ) Sample C -A Blank Sample With Programmed Isolated Phase Dmentioning

confidence: 99%

“…1) and records the far-field diffraction patterns and reconstructs the complex amplitude of the reticle using iterative phase retrieval algorithms [1]. Over the last few years with this lens-less technique, also referred to as scanning coherent diffractive imaging (SCDI), we have (1) demonstrated actinic imaging of the complex exit wave on an EUV reticle [1], (2) mapped the absorber defects on EUV reticles in die-to-die and die-to-database modes [2], (3) demonstrated through pellicle imaging [3], (4) developed an EUV-optimized high-performance imaging detector for high throughput and high sensitivity operation modes [1] and (5) proposed a standalone solution for the fab integration of the tool with a bright compact EUV source [4].…”

Section: Introductionmentioning

confidence: 99%

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Phase defect inspection on EUV masks using RESCAN

Rajeev

Mochi

Kazazis

et al. 2018

International Conference on Extreme Ultraviolet Lithography 2018

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As extreme ultraviolet (EUV) lithography is entering the high-volume manufacturing (HVM) phase, the ability to identify printable defects on EUV reticles becomes increasingly important to achieve the required wafer yield. However, no commercially available tool exists today for actinic patterned mask inspection (APMI). RESCAN is an APMI tool based on scanning coherent diffraction imaging (SCDI) under development at the Paul Scherrer Institut. In the last years, using RESCAN, we have demonstrated actinic identification of absorber defects on mask down to 36 nm size, and throughpellicle defect inspection. In this paper, we address a very critical but hitherto not reported feature of an APMI tool, namely the identification and characterization of phase defects on a patterned mask. Phase defects could be due to imperfections on the blank substrate leading to modification of the multilayer topology or due to particles embedded within the multilayer itself. Independent of the origin, the wave exiting the multilayer surface will have domains of phase variations as it propagates in the three-dimensional reticle stack. Mapping the exit wave that leave the EUV reticle both in amplitude and phase would be of paramount importance towards accurately predicting the EUV aerial images. Exploiting the amplitude and phase maps provided by SCDI, we use RESCAN for phase contrast imaging and to characterize programmed phase defects in a hybrid absorber-phase sample in a lens-less scheme, demonstrating the capability of the method and the tool.

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Section: ) Sample C -A Blank Sample With Programmed Isolated Phase Dmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase defect inspection on EUV masks using RESCAN

Rajeev

Mochi

Kazazis

et al. 2018

International Conference on Extreme Ultraviolet Lithography 2018

Self Cite

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“…Therefore, from an ideal EUV source we need 1,000-10,000 W/mm 2 ⋅sr brightness for patterned mask inspection. Lensless imaging methods that rely on the coherence property of the light, despite being a relatively exotic method [7][8][9], are the only methods that have shown, in the past, promising results. They require a brightness that is several orders of magnitude higher than that of the incoherent microscopy techniques.…”

Section: Introductionmentioning

confidence: 99%

A high-brightness accelerator-based EUV source for metrology applications

Ekinci

Garvey

Streun

et al. 2018

Photomask Technology 2018

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One of the challenges of actinic metrology tools for EUV lithography is the availability of light sources with high brightness, stability, and availability. In particular, actinic patterned mask inspection on EUV reticles is considered an essential tool for the EUV lithography ecosystem and it requires an EUV source of high brightness. We present the design of a compact and accelerator-based light source producing EUV radiation with high-brightness for actinic metrology applications in the semiconductor industry. Our design is based on the well-established components and design principles. The specifications required for actinic mask inspection is achieved using a short period undulator and 430 MeV electron energy. The concentric design of storage and booster rings enables stable operation with a relatively small footprint. This study shows the commercial viability of a compact and high-brightness EUV source with high stability and reliability and demonstrates its feasibility for actinic metrology applications.

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Through-pellicle inspection of EUV masks

Cited by 2 publications

References 11 publications

Phase defect inspection on EUV masks using RESCAN

Phase defect inspection on EUV masks using RESCAN

A high-brightness accelerator-based EUV source for metrology applications

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