Optimized Overlay Metrology Marks: Theory and Experiment

Adel, Mike; Ghinovker, Mark; Golovanevsky, Boris; Izikson, Pavel; Kassel, Elyakim; Yaffe, Dan; Bruckstein, Alfred M.; Goldenberg, Roman; Rubner, Yossi; Rudzsky, Michael

doi:10.1109/tsm.2004.826955

Cited by 34 publications

(16 citation statements)

References 13 publications

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“…The WMS extends the technology currently employed within the KLA-Tencor overlay products for wafer alignment and overlay metrology 18 to the specific requirements of REBL.…”

Section: Wafer Registrationmentioning

confidence: 99%

REBL nanowriter: Reflective Electron Beam Lithography

Petric

Bevis

Brodie

et al. 2009

Alternative Lithographic Technologies

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REBL (Reflective Electron Beam Lithography) is being developed for high throughput electron beam direct write maskless lithography. The system is specifically targeting 5 to 7 wafer levels per hour throughput on average at the 45 nm node, with extendibility to the 32 nm node and beyond. REBL incorporates a number of novel technologies to generate and expose lithographic patterns at estimated throughputs considerably higher than electron beam lithography has been able to achieve as yet. A patented reflective electron optic concept enables the unique approach utilized for the Digital Pattern Generator (DPG). The DPG is a CMOS ASIC chip with an array of small, independently controllable cells or pixels, which act as an array of electron mirrors. In this way, the system is capable of generating the pattern to be written using massively parallel exposure by ~1 million beams at extremely high data rates (~ 1Tbps). A rotary stage concept using a rotating platen carrying multiple wafers optimizes the writing strategy of the DPG to achieve the capability of high throughput for sparse pattern wafer levels. The exposure method utilized by the DPG was emulated on a Vistec VB-6 in order to validate the gray level exposure method used in REBL. Results of these exposure tests are discussed.

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“…The WMS extends the technology currently employed within the KLA-Tencor overlay products for wafer alignment and overlay metrology 18 to the specific requirements of REBL.…”

Section: Wafer Registrationmentioning

confidence: 99%

REBL nanowriter: Reflective Electron Beam Lithography

Petric

Bevis

Brodie

et al. 2009

Alternative Lithographic Technologies

View full text Add to dashboard Cite

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“…The shifts due to the other terms depend on the corresponding phase differences within these terms, and can produce unpredictable results for the measured grating shift. Errors in image shifts due to phase differences are cancelled by summing images corresponding to source point (β, γ) with images corresponding to source point (-β, γ), provided that the light intensities I S (β, γ) and I S (−β, γ) of both illumination sources are equal and target has a symmetric form 1 …”

Section: Order Control In Imaging Overlay Metrology Theoretical Consimentioning

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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“…In this study the actual target area was reduced by a factor of 4 compared with the standard scribe line targets. One of the potential risks associated with this drastic reduction is the possible degradation in overlay mark fidelity (OMF) [1] and precision due to reduced spatial and temporal information content [2]. The data in Figure 5 below indicates that although some degradation is observed the performance is still deep within the 1.2 nm precision specifications of the Archer AIM tool.…”

Section: Metrology Target Insertion Into Product Diesmentioning

confidence: 99%

In-chip overlay metrology in 90 nm production

Schulz¹,

Seltmann²,

Paufler³

et al. 2005

ISSM 2005, IEEE International Symposium on Semiconductor Manufacturing, 2005.

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We have inserted, measured and demonstrated good metrology performance on in-die overlay targets on product wafers. It is shown that scanner aberration induced pattern placement errors (PPE) can be measured, simulated and validated by CD-SEM, but the magnitude of the effect on late generation scanners is small -of the order of ~1.5 nm peak to peak across the slit. It is observed that in-die overlay data contains additional sources of variation beyond PPE and the results have been verified by SEM. It is demonstrated that current practices based on linear models do not capture in-die variations which significantly impacts model residuals.Currently, in-die target insertion is an insurance policy which enables in-die trouble shooting when process issues are suspected and will potentially improve lot dispositioning in the future.

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Optimized Overlay Metrology Marks: Theory and Experiment

Cited by 34 publications

References 13 publications

REBL nanowriter: Reflective Electron Beam Lithography

REBL nanowriter: Reflective Electron Beam Lithography

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

In-chip overlay metrology in 90 nm production

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