The evolution of pattern placement metrology for mask making

Beyer, Dirk; Rosenkranz, Norbert; Blaesing-Bangert, Carola

doi:10.1117/12.896892

Cited by 2 publications

(2 citation statements)

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“…The measurement results presented in the last section demonstrate that one-dimensional, traceable registration measurements with reproducibility of 0.2 nm (1σ ) are readily obtainable even with the current setup of the Nanometer Comparator. Mask measurement machines of the actual generator, such as Prove of Zeiss [10] and IPRO 5 of KLA Tencor [24] demonstrated nominal accuracies of 0.17 nm and 0.27 nm (1σ ). Due to their superior microscope optics, both reach these values even if structures as small as 100 nm are measured.…”

Section: Discussionmentioning

confidence: 99%

“…An analysis of the calibration procedure reveals that a traceable calibration can be obtained in the course of the self-calibration process if the separation of two features has been calibrated traceably. The use of a mask, which has been fully calibrated as referred to [10,11], does not lead to any advantage because possible influences of the mask position and orientation have to be determined as well by a very similar set of measurements as in the self-calibration procedure. Therefore, the PTB decided to discontinue two-dimensional position or registration calibrations of photomasks in the near future and offer only one-dimensional registration calibrations on photomasks by means of the Nanometer Comparator.…”

Section: Introductionmentioning

confidence: 99%

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Implementing registration measurements on photomasks at the Nanometer Comparator

Köning

Weichert

Przebierala

et al. 2012

Meas. Sci. Technol.

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Due to the introduction of double patterning schemes in the production processes of the semiconductor industry and the corresponding stringent specifications of the placement errors of the optical images of mask features (1.2 nm (3σ)) in the lithographic projection process, significant improvements of the registration measurements on photomasks are required. The Nanometer Comparator of the PTB, a one-dimensional vacuum-interference length comparator, has already demonstrated measurement reproducibility at this level on line scales and linear encoders, and therefore this comparator should also be applied for placement metrology on photomasks. Because a photomask is a relatively thin plate which is supported almost at its ends, the bending influence is much larger than for line scales and precautions had to be taken to reduce the influence of the sample support on the measurements results. A new sample mount was built, which exhibits mechanical alignment aids. In addition the position deviations caused by the mask bending were corrected by means of finite element calculations. Measurements performed with the Nanometer Comparator on a high-quality mask showed a maximum deviation of measured feature positions from the common mean of below 0.5 nm and a reproducibility of 0.2 nm. These results suggest that the use of a one-dimensional calibration of mask measuring machines allows us to perform traceable registration measurements with sufficient accuracy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%