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
It has been used to measure the maximum length of defect size for the defect decision method at the reticle inspection review. But since 0.25-0. 1 8um node, we need to have another method to measure and judge the defect because of the complicated pattern like OPC (Optical Proximity Correction) shape and defects which could not decide to be acceptable or not for sensitive defect printability. The best way to know the effect of defects is to print on wafer or to use special review tool so called optical lithography simulation microscope like AIMS in order to judge these defects. But AIMS requires optical parameter of the wafer exposure machine. And its operation takes much time. And most of the detected defects can be judged at the photomask inspection process. We propose new judgement method for defect review precisely and easily. We have developed pattern shape analysis tool that makes defect shape of inspection review image some contact hole pattern example measured by its area and intensity values. or another image acquisition system like SEM some quantitative expression. This method is useful for measuring the defect on a complicated pattern like OPC, corner rounding or edge roughness as pattern quality, or area size of a contact hole. Moreover, this method doesn't remain at the measurement with 2-dimensional pattern and can take the total quantity of the light as the flux (3-demention), too. We measured the shape of the mask pattern and the defect quantitatively using this method and evaluated print possibility about the defect print step. Topic: Inspection and Repair
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