OPO robustness and measurability improvement via extended wavelengths

Katz, Shlomit; Roy, Nikhil Aditya Kumar; McCandless, Steve; Reece, Jason; Gillespie, Nathan A.; Monserud, Nils C.; Grauer, Yoav; Stakely, Mark; Gray, Greg; Li, Yonglei; Kimani, Peter K.; Park, Nahee; Yasuhisa, Iwata; Koichi, Imura; Ito, Kosuke; Zhang, Yuqian

doi:10.1117/12.2655161

Cited by 2 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Significant TMU and residual improvements were found on the image-based OVL (IBO) tool by using near-infrared spectrum (WL>820nm) on storage node layers. [2] Both simulations and wafer measurements demonstrate the requirement for long wavelengths over thick layers. Target simulation is completed on the Metrology Target Design (MTD) tool with stack information input and determines the appropriate wavelength for each layer.…”

Section: Comparison Of Thin and Thick Layer Simulations And Measureme...mentioning

confidence: 90%

SCOL long wavelength measurements on DRAM thick layers

Lee,

Lee

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

View full text Add to dashboard Cite

As the semiconductor industry rapidly approaches lithography nodes beyond 3nm, On Product Overlay (OPO) becomes a critical factor in enabling process control and manufacturing yield. The correspondingly tight OPO error budget emphasizes the importance of accurate overlay (OVL) metrology for capturing and tracking ever-smaller processes and patterning variations. In the DRAM memory segment, additional challenges arise in layers around the storage node, where the critical patterning steps are on thick layers with denser patterns than on other layers.A major challenge for optical overlay measurement on storage node layers comes from opaque optical stack materials whose optical properties reduce signal penetration effectiveness. Another key challenge is the high aspect ratio between the stack height and the target pitch, reducing diffraction efficiency and sensitivity. IBO (Image-Based Overlay) studies have shown that long wavelength (WL) improves the measurability of thick layers and significantly improves overlay results. In this paper, it is reported that longer WL (>800nm) can overcome the measurability challenges and achieve accurate results on a DRAM storage node layer. We present how improvements in raw overlay signal (pupil-plane image uniformity) further result in Total Measurement Uncertainty (TMU) and residual improvements over previous baseline solutions. Long WL enables DRAM manufacturers to meet and tighten OPO specifications on thick, storage node layers in their advanced technology architectures.

show abstract

Section: Comparison Of Thin and Thick Layer Simulations And Measureme...mentioning

confidence: 90%

SCOL long wavelength measurements on DRAM thick layers

Lee,

Lee

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

View full text Add to dashboard Cite

show abstract

“…Optical techniques such as Image Based Overlay (IBO) and Diffraction Based Overlay (DBO) are commonly used for overlay metrology. The main challenges lie in the design of small and process-representative targets which has driven the research for the past decade [4][5][6][7]. The usage of dedicated targets causes a lack of measurements statistics and, despite the efforts of the industry, representativeness of the process.…”

Section: Introductionmentioning

confidence: 99%

Small angle x-ray scattering overlay metrology for advanced nodes

Choisnet,

Freychet,

Blancquaert

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

View full text Add to dashboard Cite

With a sub-nanometric resolution required for nodes below 14 nm, according to the International Roadmap for Devices and Systems (IRDS), exploring new overlay characterization methods is key to drive further component size reduction and develop better-performing technologies. In this work, we present our first Small-Angle X-ray Scattering (SAXS) results of overlay measurements on stacks of silicon line gratings. Our method, novel for SAXS overlay measurements, is based on inverse problem resolution and reconstructs the in-depth profile (approximated as a stack of trapezoids) of the structure. We are thus able to extract overlay with SAXS with a very fine sensitivity, high precision and sub-nanometric resolution that suit the requirements for advanced technological nodes. We compared these results with those of Scanning Electron Microscopy (SEM) contour-based on product overlay. The reconstructed structures are compared to profiles obtained with Scanning Transmission Electron Microscopy (STEM). From the differences between these multi-scale techniques we can conclude on the high potential of SAXS to become a complementary to those existing, and assess its potential for advanced technology nodes.

show abstract

OPO robustness and measurability improvement via extended wavelengths

Cited by 2 publications

References 0 publications

SCOL long wavelength measurements on DRAM thick layers

SCOL long wavelength measurements on DRAM thick layers

Small angle x-ray scattering overlay metrology for advanced nodes

Contact Info

Product

Resources

About