A study of defect measurement techniques and corresponding effects on the lithographic process window for a 193-nm EPSM photomask

Nhiev, Anthony; Hickethier, Jason; Zhou, Hai-Qing; Hutchinson, Trent; Howard, William H.; Ahmadian, Mohsen

doi:10.1117/12.518048

Cited by 2 publications

(1 citation statement)

References 3 publications

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“…[6][7][8][9][10] Currently, a lot of effort is put on the simulation of defect printing to reduce the time consumption of printing studies and also to disposition defects in production. [11][12][13][14] However, the matching between AIMS TM results and simulations is often unsatisfactory since the imperfections of the AIMS TM optics are normally not included in simulations (e.g., flare, aberrations, cross-talk, inhomogeneous illumination). 15,16 This discrepancy between simulation and measurement is exemplified in the upper part of Figure 1 on a lines and spaces (referred to as l&s hereafter) pattern for annular illumination † .…”

Section: Introductionmentioning

confidence: 98%

The importance of being homogeneous: on the influence of illumination inhomogeneity on AIMS images

et al. 2005

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Defect disposition and qualification with stepper simulating AIMS TM tools on advanced masks of the 90 nm node and below is key to match the customer's expectations for "defect free" masks, i.e. masks containing only nonprinting design variations. For defect dispositioning usually printability studies are carried out using the same illumination settings at the AIMS TM tool as later on at the steppers in the wafer fab. These studies then establish an AIMS TM criterion (e.g., CD variation or transmission deviation) a structure deviation must not exceed. For ever more advanced technologies the accessible process window gets smaller and thus more and more complex apertures have to be used to allow for a still suitable contrast and reliable printing of the patterns. This results in more time-consuming printability studies and tighter AIMS TM specs. Simulations of the printing of mask defects could potentially help to decrease the amount of time for printability studies and also the time for defect disposition in the production. However, usually simulations in their first approximation do not account for effects such as flare, aberrations or illumination inhomogeneities of the AIMS TM tool. This makes it difficult to derive the AIMS TM criterion by simulations. In this paper we show that a homogeneous aperture illumination is crucial for the image contrast and the defect disposition. We present a method to characterize the pupil illumination and investigate the impact of illumination inhomogeneities on various structures and their orientation employing two different aperture types. The experimental results are compared to simulations with both homogeneous illumination and the real illumination distribution. It turns out that for correct simulation predictions on experimental results it is important to provide the correct illumination distribution to the simulations.

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Section: Introductionmentioning

confidence: 98%

The importance of being homogeneous: on the influence of illumination inhomogeneity on AIMS images

et al. 2005

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Evaluation of litho printability of DRAM contact hole patterns with various programmed defects

Seo¹,

Lee²,

Kim³

et al. 2007

SPIE Proceedings

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As the photomask design rules continue to shrink towards 45nm and below, the defect classification criteria is becoming more challenging to be set accurately. Pattern fidelity issues and masks defects that were once considered insignificant or merely nuisances are now yield-limiting. On the other hand, there are still cases of small defects captured during reticle inspection but will not print on the wafer. In addition, in a production setting environment it is critical to ascertain quickly and efficiently the true lithographic effect of reticle defects in order to avoid yield and cycle time impacts.As a starting point, it is best to inspect the reticle at the highest sensitivity to find all defects and anomalies. From there, fast and efficient means to sort and prioritize defects are necessary for inspection operators' and engineers' convenience. Then, it is critical to model all the defects accurately for their lithographic impact. Finally, an accurate lithographybased set of reticle defect disposition criteria can be developed for the manufacturing process flow.The focus of this study is on contact or hole patterns since the issues regarding capture of defects on such patterns are typically more complex than the ones on line and space patterns. The intent is to assess and devise defect disposition criteria for contact hole layers utilizing KLA-Tencor's 5X6 DUV inspection system with both standard die-to-die and Litho2 algorithms and the Automated Mask Defect Disposition (AMDD) system. AMDD lithographic printability results will be compared to AIMS results and printed results on wafer.

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A study of defect measurement techniques and corresponding effects on the lithographic process window for a 193-nm EPSM photomask

Cited by 2 publications

References 3 publications

The importance of being homogeneous: on the influence of illumination inhomogeneity on AIMS images

The importance of being homogeneous: on the influence of illumination inhomogeneity on AIMS images

Evaluation of litho printability of DRAM contact hole patterns with various programmed defects

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