Wavelength-dependent mask defect inspection and printing

McCallum, Martin

doi:10.1117/12.458326

Cited by 3 publications

(4 citation statements)

References 4 publications

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“…Additionally, RET's build on optical effects to enhance image quality and reduce printable feature size. Inspection systems, which do not illuminate the reticle at the same wavelength as the stepper, cannot take these effects into consideration in the inspection [ 4]. Furthermore, the shrinking of the feature size, especially in layers such as contact layers, may result in the appearance of MEEF.…”

Section: Aerial Imaging Inspection Conceptmentioning

confidence: 92%

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Aerial image-based inspection of binary (OPC) and embedded-attenuated PSM

et al. 2002

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The paper presents a revolutionary technology to inspect advanced contact layers. Instead of finding defects based on a size-dependent defect specification, defects are found according to their impact at the wafer CD result. The inspection methodology used is aerial imaging. The main advantage of this method is that only defects, which actually affect the wafer result, will be detected and classified. The paper presents first inspection results on contact layers designed for the 130nm and 90 nm technology node.

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Section: Aerial Imaging Inspection Conceptmentioning

confidence: 92%

“…The most prominent one is AIMS TM [1][2][3][4], most commonly used for final qualification of reticles after repair. AIMS TM is considered a reliable tool for defect dispositioning and many studies in the past have shown compatibility between printability and AIMS TM imaging [ 1].…”

Section: Aerial Imaging Inspection Conceptmentioning

confidence: 99%

Aerial image-based inspection of binary (OPC) and embedded-attenuated PSM

et al. 2002

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“…Also two different Numerical Aperture (NA) settings were studied for each source: O.7NA and O.9NA. In all cases, partial coherence of 0.99 has been assumed for the illumination source, though inspectability may be improved with a more coherent source [4].…”

Section: Sill Conmentioning

confidence: 99%

Optical inspection of EPL stencil masks

2003

Self Cite

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We are now at a major junction in lithography where non-optical lithographies, such as Electron Projection Lithography (EPL) [1], are being introduced. The mask used in EPL is a silicon substrate with a thin silicon (-2im) membrane, with openings for electrons to pass through, acting as a scatterer. This must be inspected as mask defects may print effecting pattern fidelity. Initial mask inspection work has used SEM inspection to find these defects. However, we have historically used optical mask inspection tools, utilising wavelengths at or above those we are using for imaging, to qualify masks. This technology has been increasingly difficult to sustain as we have moved from imaging using mercury lamp based sources to pulsed excimer laser based sources that are not very suited to the inspection imaging. Indeed, review of defects found has moved from optical microscopes to SEM based tools. Inspection tools have also evolved, with the first SEM based mask inspection tools being developed to find the smallest defects, however these have the penalty of very low throughput. We will show the potential of using optical systems for the transmissive inspection of EPL masks. The high potential of existing tools will be shown together with the need for a next generation of inspection tools. We will show that simulations indicate that an inspection source with 193nm wavelength would be required for the detection of 5Onm defects on a mask. It will also be shown how the position of the defect within the membrane greatly influences detection as well as the implications of moving to a thinner silicon membrane.

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“…Nevertheless, this leads to sufficient defect detection for current technologies though systematic failures for certain defect types have been reported. 2,3 In general, the question can be raised how far the defect sensitivity can be improved using the current approach. The critical defect size for the 65-nm technology is only 20 % of the inspection wavelength with an even more unfavourable balance in the future.…”

Section: Introductionmentioning

confidence: 99%

Wafer inspection as alternative approach to mask defect qualification

Holfeld

Katzwinkel²,

Seifert³

et al. 2007

SPIE Proceedings

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Defect inspection is one of the major challenges in the manufacturing process of photomasks. The absence of any printing defect on patterned mask is an ultimate requirement for the mask shop, and an increasing effort is spent in order to detect and subsequently eliminate these defects. Current DUV inspection tools use wavelengths five times or more larger than the critical defect size on advanced photomasks. This makes the inspectability of high-end mask patterns (including strong OPC and small SRAF's) and sufficient defect sensitivity a real challenge. The paper evaluates the feasibility of inspecting the printed wafer as an alternative way for the high-sensitivity defect inspection of photomasks. Defects originating in the mask can efficiently be filtered as repeated defects in the various dies on wafer. Using a programmed-defect mask of 65-nm technology, a reliable detection of the printing defects was achieved with an optimized inspection process. These defects could successfully be traced back to the photomask in a semi-automated process in order to enable a following repair step. This study shows that wafer inspection is able to provide a full defect qualification of advanced photomasks with the specific advantage of assessing the actual printability of arbitrary defects.

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Wavelength-dependent mask defect inspection and printing

Cited by 3 publications

References 4 publications

Aerial image-based inspection of binary (OPC) and embedded-attenuated PSM

Aerial image-based inspection of binary (OPC) and embedded-attenuated PSM

Optical inspection of EPL stencil masks

Wafer inspection as alternative approach to mask defect qualification

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