&lt;title&gt;A Stepper Image Monitor For Precise Setup And Characterization&lt;/title&gt;

Brunner, Timothy A.; Cheng, Stone; Norton, A.

doi:10.1117/12.968434

Cited by 8 publications

(3 citation statements)

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“…Many techniques have been developed to measure the best focus for steppers and scanners. [1][2][3][4][5][6][7][8][9] One technique for monitoring the best focus uses focal dot arrays to create patterns that can be read by the naked eye. 1 The small dots ͑opaque area͒ are drawn on the test reticle.…”

Section: Introductionmentioning

confidence: 99%

Focus measurement with a simple pattern design

Lei

Lin

2001

Appl. Opt.

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The increasingly smaller depth of focus of advanced lithographic tools requires that the position of best focus be determined to ensure accuracy and efficiency. We present what we believe is a novel bar in bar that is drawn on a conventional chrome binary mask to translate focal errors into center-to-center shifts of outer and inner bars. An overlay measurement tool can easily measure this shift. A symmetrical center-to-center shift against best focus is created during defocus, and this shift can be well fitted by a second-order polynomial equation. Simply differentiating the fitted equation leads to an accurate and reliable focus value, with a maximum error of less than 0.05 microm. The proposed technique can also be employed to evaluate the tilt, field curvature, and astigmatism of advanced lithographic tools.

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Section: Introductionmentioning

confidence: 99%

Focus measurement with a simple pattern design

Lei

Lin

2001

Appl. Opt.

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“…The work by Brunner et al showed that it is feasible to detect the fluorescent signal from the marker in a dry scanner [6][7][8] . Since then, changes are made to the expose area in the scanner that block a direct line of sight.…”

Section: Embodiments For the Fluorescence Detectionmentioning

confidence: 99%

“…That fluorescent markers can indeed be used to measure the positioning and imaging performance of a lithography scanner is shown by Brunner et el. in the 80s of the precious century [6][7][8] . Albeit addressing lens heating, Brunner's experiments did not use at-product-pitch features in the markers.…”

Section: Introductionmentioning

confidence: 99%

Real-time focus and overlay measurement by the use of fluorescent markers

Maas

Zwet

2014

SPIE Proceedings

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In lithography, overlay control is getting increasingly complex. Advanced Process Control (APC) is introduced to minimize excursions from the process window for the present exposure. APC uses metrology data of previously exposed wafers, hence, there is always a delay of tens of minutes before the required information is available. This paper proposes the combination of a patterned expose beam and a patterned fluorescent marker on a wafer to generate a fluorescent signal that carries real-time information of the focus and/or position error of the expose pattern with the pattern on the wafer. A practical realization requires some changes to the exposure process, stepper design and reticle lay-out. Firstly, a matched pair of markers on the wafer and reticle is required. Secondly, the generated fluorescent signal must be measured, for example with a (spectrally filtered) photon counter close to the expose area of the wafer. At last, the markers from the previous lithography step shall, after development, be filled with fluorescent material. This deposition requires an additional process step. Photon budget calculations suggest an overlay measurement accuracy of less than a tenth of a nm (real-time).

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Techniques and Tools for Optical Lithography

Waldo

1991

Handbook of Vlsi Microlithography

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<title>A Stepper Image Monitor For Precise Setup And Characterization</title>

Cited by 8 publications

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Focus measurement with a simple pattern design

Focus measurement with a simple pattern design

Real-time focus and overlay measurement by the use of fluorescent markers

Techniques and Tools for Optical Lithography

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