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Utzny C.,Advanced Mask Technology Center GmbH
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Traditional control of critical dimensions (CD) on photolithographic masks considers the CD average and a measure for the CD variation such as the CD range or the standard deviation. Also systematic CD deviations from the mean such as CD signatures are subject to the control. These measures are valid for mask quality verification as long as patterns across a mask exhibit only size variations and no shape variation. The issue of shape variations becomes especially important in the context of contact holes on EUV masks. For EUV masks the CD error budget is much smaller than for standard optical masks. This means that small deviations from the contact shape can impact EUV waver prints in the sense that contact shape deformations induce asymmetric bridging phenomena. In this paper we present a detailed study of contact shape variations based on regular product data. Two data sets are analyzed: 1) contacts of varying target size and 2) a regularly spaced field of contacts. Here, the methods of statistical shape analysis are used to analyze CD SEM generated contour data. We demonstrate that contacts on photolithographic masks do not only show size variations but exhibit also pronounced nontrivial shape variations. In our data sets we find pronounced shape variations which can be interpreted as asymmetrical shape squeezing and contact rounding. Thus we demonstrate the limitations of classic CD measures for describing the feature variations on masks. Furthermore we show how the methods of statistical shape analysis can be used for quantifying the contour variations thus paving the way to a new understanding of mask linearity and its specification. © 2013 SPIE. Source


Standiford K.,Globalfoundries | Burgel C.,Advanced Mask Technology Center GmbH
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

When compared to conventional chrome absorber masks, electron beam patterning of EUV masks requires additional corrections to account for intermediate range electron backscattering from the mirror and tantalum based absorber layers. The performance of this Mask Proximity Correction software should not be specified based solely on traditional mask linearity measures. We propose a new mask linearity specification based on Time Dependent Dielectric Breakdown requirements for metal layers. © 2013 SPIE. Source


Burgel C.,Advanced Mask Technology Center GmbH | Standiford K.,Globalfoundries | Chua G.S.,Globalfoundries
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The 50keV ebeam exposure of EUV blanks leads to additional electron backscattering from the tantalum layer and the mirror portion of the blank substrate that cannot be adequately corrected by in-tool algorithms. Coupling this additional backscatter with process effects, such as develop and etch micro/macro loading, results in significant systematic Critical Dimension (CD) errors for through pitch and linearity patterns on EUV masks. In wafer production EUV masks are targeted as single layer exposure, which requires extremely stringent CD control. The systematic CD errors can easily exceed the CD requirements of a typical EUV mask, facilitating the need for a correction scheme or mask process correction (MPC). AMTC and GLOBALFOUNDRIES have started a program to evaluate MPC solutions and drive improvements. Working closely with companies that provide solutions for ebeam and process modelling along with the corresponding correction, we have completed several iterations of MPC evaluations. Specifically, we have tested different equipment, processes and process partitioning for model calibration including a verification of the results. We report on the results of these evaluations, which include simulation of available models, as well as verification data from mask prints. We conclude by summarizing the current capabilities of available MPC solutions and present the remaining gaps for model and correction accuracy as well as the remaining questions for fully implementing MPC into the process landscape. © 2013 SPIE. Source


Wurm M.,Physikalisch - Technische Bundesanstalt | Bonifer S.,Physikalisch - Technische Bundesanstalt | Bodermann B.,Physikalisch - Technische Bundesanstalt | Richter J.,Advanced Mask Technology Center GmbH
Measurement Science and Technology | Year: 2011

A novel type of deep ultraviolet scatterometer recently developed and set up at PTB has been significantly improved with respect to the dynamic range and the signal-to-noise ratio of the measured scatterograms. The main modifications concern a novel digital data acquisition technique and a new method for the calibration of the applied detectors. With the improved system linewidths (critical dimensions), measurements on periodic structures on a state-of-the-art MoSi photomask have been carried out. The results are compared to those achieved with a scanning electron microscope and a spectroscopic scatterometer. © 2011 IOP Publishing Ltd. Source


Nesladek P.,Advanced Mask Technology Center GmbH
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

EUV lithography is currently the favorite and most promising candidate among the next generation lithography (NGL) technologies. Decade ago the NGL was supposed to be used for 45 nm technology node. Due to introduction of immersion 193nm lithography, double/triple patterning and further techniques, the 193 nm lithography capabilities was greatly improved, so it is expected to be used successfully depending on business decision of the end user down to 10 nm logic. Subsequent technology node will require EUV or DSA alternative technology. Manufacturing and especially process development for EUV technology requires significant number of unique processes, in several cases performed at dedicated tools. Currently several of these tools as e.g. EUV AIMS or actinic reflectometer are not available on site yet. The process development is done using external services /tools with impact on the single unit process development timeline and the uncertainty of the process performance estimation, therefore compromises in process development, caused by assumption about similarities between optical and EUV mask made in experiment planning and omitting of tests are further reasons for challenges to unit process development. Increased defect risk and uncertainty in process qualification are just two examples, which can impact mask quality / process development. The aim of this paper is to identify critical aspects of the EUV mask manufacturing with respect to defects on the mask with focus on mask cleaning and defect repair and discuss the impact of the EUV specific requirements on the experiments needed. © 2014 SPIE. Source

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