9nm node wafer defect inspection using three-dimensional scanning, a 405nm diode laser, and a broadband source

Zhou, Renjie; Edwards, Chris; Bryniarski, Casey; Popescu, Gabriel; Goddard, Lynford L.

doi:10.1117/12.2085683

Cited by 12 publications

(7 citation statements)

References 9 publications

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“…The rapid and precise imaging of three-dimensional (3D) semiconductor devices is of significant importance for semiconductor wafer inspection during the manufacturing process. In general, imaging techniques can be classified into two types, namely two-dimensional (2D) inspection and 3D inspection 1,2 . Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are techniques that can identify defects and measure the critical dimension (CD) of fine patterns in highresolution 2D images 3,4 .…”

Section: Introductionmentioning

confidence: 99%

Microsphere-assisted, nanospot, non-destructive metrology for semiconductor devices

et al. 2022

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As smaller structures are being increasingly adopted in the semiconductor industry, the performance of memory and logic devices is being continuously improved with innovative 3D integration schemes as well as shrinking and stacking strategies. Owing to the increasing complexity of the design architectures, optical metrology techniques including spectroscopic ellipsometry (SE) and reflectometry have been widely used for efficient process development and yield ramp-up due to the capability of 3D structure measurements. However, there has been an increasing demand for a significant reduction in the physical spot diameter used in the SE technique; the spot diameter should be at least 10 times smaller than the cell dimension (~30 × 40 μm2) of typical dynamic random-access memory to be able to measure in-cell critical dimension (CD) variations. To this end, this study demonstrates a novel spectrum measurement system that utilizes the microsphere-assisted super-resolution effect, achieving extremely small spot spectral metrology by reducing the spot diameter to ~210 nm, while maintaining a sufficiently high signal-to-noise ratio. In addition, a geometric model is introduced for the microsphere-based spectral metrology system that can calculate the virtual image plane magnification and depth of focus, providing the optimal distance between the objective lens, microsphere, and sample to achieve the best possible imaging quality. The proof of concept was fully verified through both simulations and experiments for various samples. Thus, owing to its ultra-small spot metrology capability, this technique has great potential for solving the current metrology challenge of monitoring in-cell CD variations in advanced logic and memory devices.

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Section: Introductionmentioning

confidence: 99%

Microsphere-assisted, nanospot, non-destructive metrology for semiconductor devices

et al. 2022

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“…N. T. Shaked et al [14] reported placing the interferometer in a vacuum-sealed enclosure to avoid the influence of the air flow and used a floating optical table to damp the device oscillations to some extent. R. Zhou et al [15] explored the use of high stability laser sources (i.e., temperature and current controlled semiconductor lasers) and broadband light sources to minimize the phase noise. G. Popescu et al [16] developed diffraction phase microscopy (DPM) with a common-path off-axis interferometry geometry to diminish the mechanical vibrations.…”

Section: Introductionmentioning

confidence: 99%

Beating temporal phase sensitivity limit in off-axis interferometry based quantitative phase microscopy

Nie

Zhou

2021

APL Photonics

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Phase sensitivity determines the lowest optical path length (OPL) value that can be detected from the noise floor in a quantitative phase microscopy (QPM) system. The temporal phase sensitivity is known to be limited by both photon shot-noise and a variety of noise sources from electronic devices and environment. To beat temporal phase sensitivity limit, we explore different ways to reduce different noise factors in off-axis interferometry-based QPM using laser-illumination. Using a high electron-well-capacity camera, we measured the temporal phase sensitivity values using non-common-path and common-path interferometry based QPM systems under different environmental conditions. A frame summing method and a spatiotemporal filtering method are further used to reduce the noise contributions, thus enabling us to push the overall temporal phase sensitivity to less than 2 picometers.

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“…Many defect inspection tools rely on the wafer periodic pattern and subtract between seemingly similar areas on the wafer along the defect inspection pipeline. The subtraction image enhances irregularities in the wafer pattern, and, if any defect is present, it will be revealed in the subtraction image, given the defect signal is stronger than the noise of the subtracted periodic pattern [3][4][5][6][7][8]. It is therefore important to enhance the defect signal over the pattern signal, as early as possible, hopefully during the image acquisition stage of the inspected area.…”

Section: Introductionmentioning

confidence: 99%

“…When imaging wafers, the phase distribution of an optical wave reflecting from the wafer indicates its surface topography. Irregularities in the wafer topography indicate defects in the wafer fabrication process [3,4,[9][10][11] and can damage the final semiconductor device. Without imaging phase variations, vital information about the wafer pattern is lost.…”

Section: Introductionmentioning

confidence: 99%

Wafer defect detection by a polarization-insensitive external differential interference contrast module

2018

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We present a system that is based on a new external, polarization-insensitive differential interference contrast (DIC) module specifically adapted for detecting defects in semiconductor wafers. We obtained defect signal enhancement relative to the surrounding wafer pattern when compared with bright-field imaging. The new DIC module proposed is based on a shearing interferometer that connects externally at the output port of an optical microscope and enables imaging thin samples, such as wafer defects. This module does not require polarization optics (such as Wollaston or Nomarski prisms) and is insensitive to polarization, unlike traditional DIC techniques. In addition, it provides full control of the DIC shear and orientation, which allows obtaining a differential phase image directly on the camera (with no further digital processing) while enhancing defect detection capabilities, even if the size of the defect is smaller than the resolution limit. Our technique has the potential of future integration into semiconductor production lines.

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9nm node wafer defect inspection using three-dimensional scanning, a 405nm diode laser, and a broadband source

Cited by 12 publications

References 9 publications

Microsphere-assisted, nanospot, non-destructive metrology for semiconductor devices

Microsphere-assisted, nanospot, non-destructive metrology for semiconductor devices

Beating temporal phase sensitivity limit in off-axis interferometry based quantitative phase microscopy

Wafer defect detection by a polarization-insensitive external differential interference contrast module

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