OPO reduction in scatterometry metrology by rotated quadrupole illumination

Dirawi, Rawi; Yaziv, Tal; Milo, Renan; Gutman, Nadav; Bachar, Ohad

doi:10.1117/12.2608255

Cited by 2 publications

(2 citation statements)

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“…With the latest illumination pupil with a Rotated-Quadruple apodizer, the capability to resolve wavelength range is enlarged [6]. A DRAM device consists of repeated perpendicular data switching signal lines with the high aspect of the capacitor.…”

Section: Methodology 21 Scol Accuracy Meritsmentioning

confidence: 99%

ADI to in-cell overlay stability improvement for DRAM using novel scatterometry and comprehensive process control

Kim

Jeong

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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As the cell size of memory devices continues to shrink, tighter on-product overlay (OPO) specs require more accurate and robust overlay control. The overlay error budget mainly consists of the reticle, scanner, process, and metrology errors. The metrology budget is generally required to be <10% of the OPO control budget so that the accuracy and robustness of overlay metrology become more crucial as pattern size gets smaller on current 1x nm DRAM nodes. For overlay control in high-volume manufacturing (HVM), the primary optical overlay metrology typically used is Image-Based Overlay (IBO). In many cases, scatterometry overlay (SCOL), using a direct grating-scanning method, was shown to achieve more accurate After Development Inspection (ADI) overlay measurements. Using a tunable source and customized illumination pupil to directly scan within the grating cell, this technology improves accuracy by reducing the contribution of pattern surroundings in the scribe line, resulting in improved OPO control stability. Since the purpose of overlay control is to minimize actual device pattern misregistration, as measured after the etching process (AEI), achieving accurate and stable characterization of the systematic deviation between ADI and AEI overlay known as Non-Zero-Offset (NZO) is critically important. Accurate NZO applied to the scanner via the Advanced-Process-Control (APC) loop enables effective scanner overlay control at the post-lithography ADI step. This paper demonstrates a new scatterometry overlay technology adopted in DRAM use cases that resulted in OPO and NZO stability improvement. In addition, we demonstrate an efficient method to monitor HVM run-to-run overlay performance and NZO stability by comprehensive dataset modeling combining ADI and AEI.

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Section: Methodology 21 Scol Accuracy Meritsmentioning

confidence: 99%

ADI to in-cell overlay stability improvement for DRAM using novel scatterometry and comprehensive process control

Kim

Jeong

et al. 2023

Metrology, Inspection, and Process Control XXXVII

View full text Add to dashboard Cite

show abstract

“…Focus Assist (FA) is an illumination scheme utilizing low-NA on-axis illumination, which was the fundamental illumination pattern. But FA illumination has suffered from limited wavelength coverage with signal overlap on small-pitch targets, which on one hand couldn't play to the strengths of SCOL broadband illumination source, on the other hand, would miss the possible best measurement wavelength range [4]. The newly added rotated quadrupole (RQ) scheme, instead of on-axis illumination, utilizes low-NA oblique illumination with two opposing oblique illumination beams direction.…”

Section: Rq Apodizer and Landscape Extensionmentioning

confidence: 99%

Enhancement of overlay metrology accuracy by multi-wavelength scatterometry with rotated quadrupole illumination

Kim

Jeong

Hong

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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As DRAM technology continues to evolve, advanced nodes shrink the device dimensions and raise the requirements for on-product overlay control to reduce residual error. Increased process complexity also demands tighter accuracy and robustness in metrology control, which necessitates new and innovative metrology enhancements and methods. Scatterometry-based overlay (SCOL®) metrology is a unique overlay metrology architecture that uses angle-resolved pupil imaging for overlay analysis and calculation. KLA’s SCOL metrology system offers wide-spectrum tunable laser and multi-wavelength (MWL) illumination patterns along with custom-designed advanced algorithms that provide multiple measurement conditions to meet unique layer and target requirements. This paper demonstrates improved overlay metrology accuracy and residual error on DRAM FEOL critical layer with SCOL technology. Multiwavelength and rotated quadrupole (RQ) illumination in the metrology tool are utilized to provide significantly improved residuals compared with the traditional single-wavelength (SWL) and on-axis illumination.

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OPO reduction in scatterometry metrology by rotated quadrupole illumination

Cited by 2 publications

References 0 publications

ADI to in-cell overlay stability improvement for DRAM using novel scatterometry and comprehensive process control

ADI to in-cell overlay stability improvement for DRAM using novel scatterometry and comprehensive process control

Enhancement of overlay metrology accuracy by multi-wavelength scatterometry with rotated quadrupole illumination

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