Kla Tencor Corporation

Kla Corporation

Ido Adam

Noga Sella

Amnon Manassen

Yoel Feler

Barak Bringoltz

Yuval Lamhot

Lilach Saltoun

Tal Yaziv

Tom Leviant

Vladimir Levinski

Daniel Kandel

Eran Amit

Ohad Bachar

Nuriel Amir

Yuval Lubashevsky

Tal Marciano

Evgeni Gurevich

Einat Peled

Boris Efraty

Dror Alumot

Nadav Carmel

Ofer Zaharan

Oded Kaminsky

Wei-Te Cheng

Amir Handelman

Yaron De Leeuw

Eltsafon Ashwal-Island

Zeng Zhao

Eltsafon Ashwal

Roee Sulimarski

Moshe Cooper

Ze'ev Lindenfeld

Yaron Deleeuw

Methods, metrology modules and target designs are provided, which improve the accuracy of metrology measurements. Methods provide flexible handling of multiple measurement recipes and setups and enable relating them to landscape features that indicate their relation to resonance regions and to flat regions. Clustering of recipes, self-consistency tests, common processing of aggregated measurements, noise reduction, cluster analysis, detailed analysis of the landscape and targets with skewed cells are employed separately or in combination to provide cumulative improvements of measurement accuracy.

Accuracy improvements in optical metrology

A method of determining overlay ('OVL') in a pattern in a semiconductor wafer manufacturing process comprises capturing images from a cell in a metrology target formed in at least two different layers in the wafer with parts of the target offset in opposing directions with respect to corresponding parts in a different layer. The images may be captured using radiation of multiple different wavelengths, each image including +1 and &#x2212;1 diffraction patterns. A first and second differential signal may be determined for respective pixels in each image by subtracting opposing pixels from the +1 and &#x2212;1 diffraction orders for each of the multiple wavelengths. An OVL for the respective pixels may be determined based on analyzing the differential signals from multiple wavelengths simultaneously. Then an OVL for the pattern may be determined as a weighted average of the OVL of the respective pixels.

Overlay measurement using multiple wavelengths

Scatterometry overlay targets as well as target design and measurement methods are provided, which mitigate the effects of grating asymmetries in diffraction based overlay measurements. Targets comprise additional cells with sub-resolved structures replacing resolved coarse pitch gratings and/or comprise alternating sub-resolved structures with coarse pitch periodicity&#x2014;to isolate and remove inaccuracies that result from grating asymmetries. Measurement methods utilize orthogonally polarized illumination to isolate the grating asymmetry effects in different measurement directions, with respect to the designed target structures.

Mitigation of inaccuracies related to grating asymmetries in scatterometry measurements

Methods are provided for deriving a partially continuous dependency of metrology metric(s) on recipe parameter(s), analyzing the derived dependency, determining a metrology recipe according to the analysis, and conducting metrology measurement(s) according to the determined recipe. The dependency may be analyzed in form of a landscape such as a sensitivity landscape in which regions of low sensitivity and/or points or contours of low or zero inaccuracy are detected, analytically, numerically or experimentally, and used to configure parameters of measurement, hardware and targets to achieve high measurement accuracy. Process variation is analyzed in terms of its effects on the sensitivity landscape, and these effects are used to characterize the process variation further, to optimize the measurements and make the metrology both more robust to inaccuracy sources and more flexible with respect to different targets on the wafer and available measurement conditions.

Method of analyzing and utilizing landscapes to reduce or eliminate inaccuracy in overlay optical metrology

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Qiriat Ono, Israel

Ido Adam