Overlay measurement and analysis of x-ray/optical lithography for mix-and-match device applications

Yanof, Arnold W.; Cummings, K. D.; Seese, P. A.; Thompson, Matthew A.; Drew, Mark; DeMay, Daniel J.; Oberschmidt, James; Fair, Robert H.; Lamberti, Angela C.

doi:10.1117/12.175807

Cited by 1 publication

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“…Standard grid error corrections are easy to implement, but have the disadvantage of leaving a residual of noncorrected error which reduces the effectiveness of the reticle correction technique. This is the approach used by Puisto [6] and Yanof [7] to manufacture x-ray photomasks. Because of its significant cost advantages, this is also the approach that was selected for this study.…”

Section: Reticle Correctionsmentioning

confidence: 99%

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<title>Reticle correction technique to minimize lens distortion effects</title>

Flack¹,

Flores²,

Walther³

et al. 1994

SPIE Proceedings

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Mix-and-match lithography is broadly accepted as a valuable strategy for reducing capital costs and increasing productivity in semiconductor manufacturing. The main technical challenge for mix-and-match lithography is to provide adequate overlay to support advanced device design rules. The overlay error consists of a number of components, including lens distortion of the various lithography tools. All optical lithography systems have a characteristic distortion signature which results from lens design and manufacturing. Lenses of a given design are usually matched during manufacturing to minimize the overlay effect of distortions in a multistepper environment. However, mix-and-match lithography frequently requires the use of systems of different field sizes from multiple vendors and technologies (lx, 5x, 4x). In this case, the lens distortion signatures can be very different between the lithography systems.One approach to minimize the effect of lens distortion is to apply a series of corrections to the design database before reticle manufacturing. These corrections can be optimized to a specific lens or can be generic to remove the systematic errors of a class of lenses. This flexible approach offers the potential to remove lens distortion as a major factor in overlay error for mix-and-match lithography.In this study, the distortion signature of an Ultratech 2244i lens was measured using an advanced registration measurement system. A correction for this distortion signature was applied to the design database and a mix-and-match test reticle fabricated. In order to quantify the effectiveness of this technique, a mix-and-match overlay study was performed using the same Ultratech 2244i and an advanced 5x reduction stepper. Overlay experiments were performed using both corrected and noncorrected reticles on the Ultratech system. An automated metrology system was used to collect overlay measurements distributed over the entire lens field area. Detailed analysis of the lens intrafield component of the overlay error using both reticles illustrates the advantages of applying reticle distortion corrections. O-8194-1653-3/94/$6.OO SPIE Vol. 2322 Photomask Technology and Management (1994) / 259 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/15/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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Section: Reticle Correctionsmentioning

confidence: 99%

“…In another study, x and y magnification corrections were applied during the e-beam exposure of x-ray masks. These corrected masks were used on an x-ray stepper for mixand-match lithography with an optical lithography tool [7].…”

Section: Introductionmentioning

confidence: 99%