Differential signal scatterometry overlay metrology: an accuracy investigation

Kandel, Daniel; Adel, Mike; Dinu, Berta; Golovanevsky, Boris; Izikson, Pavel; Levinski, Vladimir; Vakshtein, Irina; Leray, Philippe; Vasconi, Mauro; Salski, Bartłomiej

doi:10.1117/12.725929

Cited by 20 publications

(14 citation statements)

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“…Huang et al have demonstrated a way of increasing sensitivity to overlay by using a multi-spectra RCWA regression approach [8]. However, it is not clear if the RCWA approaches can yield sufficient accuracy and tool matching performance [10]. The linear-response approach also greatly simplifies the applications flow by eliminating the modeling requirement.…”

Section: Diffraction-based Overlay (Dbo) -General Methodsmentioning

confidence: 98%

“…Chun-Hung Ko used angular scatterometry combined with an experimental library to determine the overlay error on ADI stacks with intermediate poly-silicon lines [9]. H.-T. Huang et al use spectra from reflection symmetry gratings and a rigorous coupled-wave analysis (RCWA) regression approach to calculate the overlay error [10]. W. Yang et al [11] and D. Kandel et al [12] use specially constructed pads with programmed offsets to determine regression-free overlay vectors.…”

Section: Introductionmentioning

confidence: 99%

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Evaluating diffraction based overlay metrology for double patterning technologies

Saravanan¹,

Liu²,

Dasari³

et al. 2008

SPIE Proceedings

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Demanding sub-45 nm node lithographic methodologies such as double patterning (DPT) pose significant challenges for overlay metrology. In this paper, we investigate scatterometry methods as an alternative approach to meet these stringent new metrology requirements. We used a spectroscopic diffraction-based overlay (DBO) measurement technique in which registration errors are extracted from specially designed diffraction targets for double patterning. The results of overlay measurements are compared to traditional bar-in-bar targets. A comparison between DBO measurements and CD-SEM measurements is done to show the correlation between the two approaches. We discuss the total measurement uncertainty (TMU) requirements for sub-45 nm nodes and compare TMU from the different overlay approaches.

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Section: Diffraction-based Overlay (Dbo) -General Methodsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Evaluating diffraction based overlay metrology for double patterning technologies

Saravanan¹,

Liu²,

Dasari³

et al. 2008

SPIE Proceedings

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“…The number of cells in a scatterometry target depends strongly on the required dynamic range for overlay. Zero-order scatterometry provides an accurate solution for a broad dynamic range with a 12-cell target 8 . The number of cells may be reduced to six or eight for a reduced dynamic range.…”

Section: Dynamic Range and Target Sizementioning

confidence: 99%

Diffraction order control in overlay metrology: a review of the roadmap options

et al. 2008

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Resolution enhancement in advanced optical lithography will reach a new plateau of complexity at the 32 nm design rule manufacturing node. In order to circumvent the fundamental optical resolution limitations, ultra low k 1 printing processes are being adopted, which typically involve multiple exposure steps. Since alignment performance is not fundamentally limited by resolution, it is expected to yield a greater contribution to the effort to tighten lithographic error budgets. In the worst case, the positioning budget usually allocated to a single patterning step is divided between two. A concurrent emerging reality is that of high order overlay modeling and control. In tandem with multiple exposures, this trend creates great pressure to reduce scribeline target real estate per exposure. As the industry migrates away from metrology targets formed from large isolated features, the adoption of dense periodic array proxies brings improved process compatibility and information density as epitomized by the AIM target 1 . These periodic structures enable a whole range of new metrology sensor architectures, both imaging and scatterometry based, that rely on the principle of diffraction order control and which are no longer aberration limited. Advanced imaging techniques remain compatible with side-by-side targets while scatterometry methods require grating-over-grating targets. In this paper, a number of different imaging and scatterometry architectures are presented and compared in terms of random errors, systematic errors and scribespace requirements. It is asserted that an optimal solution must combine the TMU peak performance capabilities of scatterometry with the cost of ownership advantages of target size and multi-layer capabilities of imaging. INTRODUCTIONBrightfield imaging has been the mainstay sensor architecture of overlay metrology since the inception of automated methods in the 1980s. Throughout this period, the vast majority of measurements have been performed on so called boxin-box targets, which can be conveniently described as "large and isolated" test structures. By virtue of their smoothly varying centralized pupil distribution functions, such structures present well understood imaging challenges to the metrology tool designer. However, the features of interest for which today's advanced processes are optimized and the distances between them are rapidly shrinking away from the lumbering dimensions of these structures. This is burdening the process engineer with major compatibility challenges between metrology and device structures.At the outset of the 32 nm design rule era, these trends are driving the emergence of a whole new generation of overlay metrology structures, which are at various stages of industry adoption. The majority of these new structures differ fundamentally from their box-in-box predecessors in the crucial metrics of information content and feature density. They are enabled by replacing isolated structures from two patterning steps with periodic ones, either side-by-side or gratin...

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“…W. Yang et al [10] and D. Kandel et al [11] used arrays of specially constructed pads with programmed offsets to determine overlay without the need for model fitting. These DBO methods have the potential to meet the demanding overlay metrology budget for sub-32nm technology nodes.…”

Section: Introductionmentioning

confidence: 99%