Detection of 60° phase defects on alternating PSMs

Spence, Chris; Emery, David; Zurbrick, Larry S.; Prakash, D.P.; Chang, X.; Khanna, Steve; Leback, Brent D.; Tsujimoto, Eiji; Hughes, Greg; Yang, B.

doi:10.1117/12.328859

Cited by 2 publications

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“…However, it has been difficult to assure zero defects on reticule and we needed to rely on customers for wafer print check as the final assurance of Alt-PSMs. There were two reasons, (1) no inspection tools that could detect all kinds of phase shift defects, (2) no appropriate repair method for phase shift defects which contain various types and heights. In order to resolve these problem, we experimented below l-3.…”

Section: Introductionmentioning

confidence: 99%

Detection and repair of multiphase defects on alternating phase-shift masks for DUV lithography

et al. 1999

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Alternating Phase-Shift Mask (Alt-PSM) is one of the key technologies for O.l5pm or below rule device fabrication. But it is not yet widely utilized because of difficulty on phase controllability and defect controllability. Through more than 7 years at our commercial base operation and feedback from customers, we have improved our Alt-PSM both on its performance on wafer resist image and defect minimization.We have focused on the two elements, defects detection and repair, that made it difficult to control defect quantity on Alt-PSMs. In this paper, we describe results of experiment and optimization method that aims to assure zero defect on Alt-PSM for DUV lithography.We prepared evaluation plates. The plates contain series of programmed quartz defect on O.6pm line & space, each has phase errors of 60, 120 and 1 80 degrees at KrF wavelength. We used several latest models of inspection tools to evaluate phase shift quartz defect detectability, which are KLA353UV, STARlight, 9MD84SR(i). Micrion8000 was used as the repair tool. MSM-lOO/AIMS was used to evaluate wafer CD error ofdefect area before and after repair.As results, we found that inspection by short wavelength, especially by 9MD845R(i), was effective for detection of phase shift defects, and that if this method were combined with STARlight inspection, detectability ofthe phase shift defect would be improved. With combination of this inspection method and our FIB repair, which is optimized for pre-measured height of each phase shift defect by use of AFM, we would be able to supply zero defect Alt-PSMs for O.l5pm design rule devices.

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Section: Introductionmentioning

confidence: 99%

Detection and repair of multiphase defects on alternating phase-shift masks for DUV lithography

et al. 1999

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Phase defects on DUV alternating PSMs

et al. 2000

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To extend the life of photo lithography, it has been proceeded the development of the strong PSMs which has no printing "phase shifter" defects. At PMJ'98, a defect inspection algorithm for phase shifter defects of 60 degrees on i-line multi-phase alternating PSMs was discussed1. At BACUS'99, a defect printability and inspection sensitivity of multi-phase shifter defect for KrF exposure had also discussed2. It was reported that the inspection tool combining 9MD84SR(i) and STARlight had enough sensitivity for quartz bump defect that caused ÷1-10% CD-error on l5Onm L&S pattern. But, the delay of AsP exposure tool and process requires DUV low-k1-lithography for next generation devices. And then, we tried to evaluate defects printability and inspection sensitivity for Logic-Gate pattern mask, that line width is narrower than the line width evaluated by precede researchers.We fabricated DUV alternating PSMs with programmed defects. These PSMs contain 1 lOnm Logic-Gate patterns whose pitches were 440nm, 660nm and so on. The defects consist of quartz bumps that placed on line edges and space (clear) centers. These defects have three phase errors, 180, 120 and 60 degrees. The shape and size of the defects may be transformed during process, we need measurements of the final size of defects with mask observation SEM. By comparing line CD with and without defects in printed wafer (NA=O.6, a=O.3, X=248nm), we evaluated the defect printability. In the case of intermediate phase defects, we can see that the resist CD error changes as defocus. Therefore we evaluated the defect printability in +300nm focus position. We defined the size of a defect which causes +1-1 mm (i.e. 10% of 1 lOnm line width) CD error as critical defect size. Also, we evaluated the inspection performance of current inspection systems.As a result, we found out that the critical defect sizes for 180,120 and 60 degrees phase defects were 175, 200 and 325nm respectively. From inspection sensitivity evaluation, for 180 and 120 degrees defects, we would be able to detect the critical defect with 9MD84SR(i). But, for 60 degrees defects, we wouldn't be able to detect the critical defect. The other hands, KLA SL3-UV has a low inspection sensitivity for 120 and 180 degrees. But, for 60 degrees defects, inspection sensitivity is fairly high. For 1 lOnm Logic-Gate patterns, we can say that combination of inspection with 9MD84SR(i) and KLA SL3-UV can detect most of the critical defects.

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Detection of 60° phase defects on alternating PSMs

Cited by 2 publications

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Detection and repair of multiphase defects on alternating phase-shift masks for DUV lithography

Detection and repair of multiphase defects on alternating phase-shift masks for DUV lithography

Phase defects on DUV alternating PSMs

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