Influence of the prominent charging effect on the precision of measuring EUV mask features using CD-SEM was studied. The dimensions of EUV mask features continuously measured by CD-SEM gradually varied because of the charging. The charging effect on the measured CD variation mainly consists of three factors: 1) shift of the incident points of primary electrons deflected by the surface charge, 2) distortions of the profiles of secondary electron signal intensity caused by the deflection of the secondary electrons, 3) deviation of the maximum slope points of the secondary electron signal intensity due to the variation of the image contrast. For those three factors described above, how the material constant affect the CD variation measured by CD-SEM is discussed.
We developed a pattern shape analysis tool MaskEXPRESS) which can evaluate quantitatively photomask pattern ai thbñcalion process by means of image processing atising from -SEM or IN microscope, or inspedion mhine. AlthOUgh evaluation of mplicaS mask pattern has been rformed qualitatively as yet, MaSkEXPRESS makes it possible to evaluate it quantitatively. MaskEXPRESS can also be applied to quantitative evaluation of sensitivity of inspection machine, aorwacy of ER wifl and optimitionofphotornaskMxicafion pmor This paper describes the ouffine of MaskPRESS and its functions. We investigated about the precision critia of MaslXPRESS and found out the conditions ofimage processing for having accurany equal to repeatabifity airacy ofmeasurement SEM. By changing expimentally mask ftbñcation conditions and analyzing the patterns, tl following thin became cleat Hole pattern's ama increases with keeping analogous shape as etching time increases. Inner serif pattern tends to clmnge in tl direction of slant as wilting dose increases. The redangle fidelity ofinner and outer serifpattern is improved according to tl condition ofresist pmorss We also present the relationship between defe size and aeii image on wafer simUlaS utilizing MaskEXPRESS.
, INTRODUCHONNowadays design rule is downsizing from 0.18 Urn to 0.13 Urn and below with progress ofdevior integration. Pattern shape tends to berne rnplicated with OPC (Optical PrOXirnity thnecton) patterns. As a rnatter of urse, difficult of photornask fabrication is increasing nre and more. Slight en of rnask pattern becornes fatal en on the wafer with rnagnification of MEF(Mask Error Enhancernent Factor) . Therefore we need new rnethod that evaluates pattern quality different frorn conventional evaluation such as only prong chip and CD error.It is needed to perfiron arnately quantifiesfios in order to cornpare and evaluate paftern shape of photornask. But we have judged differenor of patt shape by qualitative cornpariron using pattern irnages as yet One reason of it was that we did not have handy rnachine or tool for quantitative evaluation. Recently necessity ofnurnerieally evaluating of a pattern shape is increasing. Especially it is very irnpflntto rasp quantitatively the influenor that a rnanufactuzingprocess has on a pattern shape. Therefore, we developed a pattern shape analysis tool MaskEXPRESS) which can evaluate quantitatively photornask pattern by rneans ofirnages frorn -SEM orUV rnispe, or inapection rnachine. MS5kEXPRESS can evaluate various characteñsties ofmask pattern quantitatively, which were dcult as ye by rneans ofrneasuring pattern profila after irnage proorssing. It can rneasure characteristic size ofpatterns including OP rncr rnundin& and thair areas, sirnultaneously evaluate the fidelity oftlt rnaskpatterns. We can rnake use of MaskEXPRESS to evaluate nct only pattern shape quality but the rnfluence ofthe change ofphotornaskftbncabon process
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