Performance study of new segmented overlay marks for advanced wafer processing

Adel, Mike; Allgair, John A.; Benoit, David C.; Ghinovker, Mark; Kassel, Elyakim; Nelson, Christopher E.; Robinson, John C.; Seligman, Gary Stanley

doi:10.1117/12.483477

Cited by 19 publications

(12 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most image-based overlay measurements assume that equations (3) and (5) are valid, that is that the targets are symmetric and that the tool creates a symmetric image of the target. If the assumption is not true then the measurement will be in error to some degree.…”

Section: Overlay Measurement By Imaging Systems (Ibo)mentioning

confidence: 99%

Overlay metrology at the crossroads

Smith¹,

Binns²,

Plambeck³

et al. 2008

SPIE Proceedings

View full text Add to dashboard Cite

The introduction of new techniques such as double patterning will reduce overlay process tolerance much faster than the rate at which critical feature dimensions are shrinking. In order to control such processes measurements with uncertainties under 0.4nm are desirable today and will become essential within the next few years. This very small error budget leads to questions about the capability of the imaging technology used in overlay tools today and to evaluation of potential replacement techniques. In this paper we will show that while imaging technology is in principle capable of meeting this requirement, the real uncertainty in overlay within devices falls well short of the levels needed. A proper comparison between techniques needs to focus on all of the possible sources of error, and especially those that cannot be simply reduced by calibration or by repeating measurements. On that basis there are more significant problems than the relative capability of different measurement techniques. We will discuss a method by which overlay within the device area can be controlled to the required tolerance.

show abstract

Section: Overlay Measurement By Imaging Systems (Ibo)mentioning

confidence: 99%

Overlay metrology at the crossroads

Smith¹,

Binns²,

Plambeck³

et al. 2008

SPIE Proceedings

View full text Add to dashboard Cite

show abstract

“…The first step was taken when KLA-Tencor introduced the AIM-target for overlay metrology 10 . As has been experienced by users of the AIM-target 11 , its robustness and enhanced information content have enabled overlay metrology with TMU well below 1 nm.…”

Section: Periodic Overlay Targets and Overlay Metrology Tool Architecmentioning

confidence: 99%

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

et al. 2008

Self Cite

View full text Add to dashboard Cite

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...

show abstract

“…Conventional box-in-box and frame-in-frame overlay marks (we will use the notation "BiB" for both types) have lacked both the robustness and the information content when they have been segmented to design rule dimensions. Recently developed grating-based metrology marks, so-called advanced imaging metrology (AIM) marks [7]- [9], have overcome these limitations. Fig.…”

Section: Introductionmentioning

confidence: 99%

Novel at-Design-Rule Via-to-Metal Overlay Metrology for 193-nm Lithography

Ueno

Tsujita

Kurita³

et al. 2004

IEEE Trans. Semicond. Manufact.

View full text Add to dashboard Cite

The effect of scanner aberrations on pattern placement errors (PPE) in the copper interconnect lithography process is studied both in simulations and experimentally. A new gratingbased overlay mark, advanced imaging metrology, enables measuring device feature overlay. It is shown that the grating mark exhibits superior performance over conventional box-in-box marks. A comparison between grating-based optical and direct CD scanning electron microscopic (SEM) device overlay measurements was done. Both CD SEM and grating mark optical measurements show sensitivity to PPE. Good matching between the new grating target and device overlays was demonstrated.Index Terms-Advanced imaging metrology (AIM), annular illumination, conventional illumination, low contrast, low-materials, overlay metrology, pattern placement error (PPE), process robustness, scanner aberrations.

show abstract

Performance study of new segmented overlay marks for advanced wafer processing

Cited by 19 publications

References 0 publications

Overlay metrology at the crossroads

Overlay metrology at the crossroads

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

Novel at-Design-Rule Via-to-Metal Overlay Metrology for 193-nm Lithography

Contact Info

Product

Resources

About