Phase amplification microscopic imaging method

Abstract

The invention provides a phase amplification microscopic imaging method with sub-angstrom level measurement precision. The method comprises the following steps: providing a phase cavity implementation method and connecting the phase cavity with an interference imaging system so as to effectively amplify a weak phase signal of a target sample; modeling the resonance effect in the phase cavity; and optimizing parameters of the phase cavity, such as a material of the phase cavity, a thickness of each layer of the phase cavity, and an illumination wavelength, to maximize amplification of the phase signal of the target sample. The phase cavity is arranged on the sample side of the interference imaging system. The method may further include obtaining a phase diagram through an interference imaging system based on laser illumination, and executing a transmission matrix-based model on the measured phase diagram to reconstruct a thickness mapping result, enabling effective detection of deep sub-wavelength size defects in the three-dimensional stacked sample. The measurement precision of the interference imaging system can reach 0.1 angstrom.

Description

Technical Field

[0001] Embodiments of the present invention relate to metrological methods based on optical microscopy. In particular, the present invention relates to a phase-magnification microscopy imaging method with sub-angstrom level measurement accuracy, which can be used to reveal electronic coupling between atomic layers and detect deep subwavelength size defects in three-dimensional stacked samples. Background Technology

[0002] In recent years, the emerging field of twist electronics has enabled the manipulation of the bandgap in two-dimensional (2D) layered materials by altering the relative angles between adjacent layers. 1-3 This method can be used to customize the electronic properties of 2D layered materials, creating electronic and photonic devices based on these novel atomic materials. 4-10 This has the potential to surpass the scaling limits of complementary metal-oxide-semiconductor (CMOS) technology, thereby revolutionizing the way information is processed. 11 .

[0003] The large-scale manufacturing of atomic devices requires advancements in atomic fabrication technologies. Since the Moore's Law era, the increase in device yield, driven by the shrinking size of transistors, has always been accompanied by progress in metrology. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) are widely used to characterize device structures, but their measurement throughput is low. 12 Optical metrology methods, such as bright-field imaging and scattering measurement, have been used for online metrology and critical dimension measurement due to their advantages of being non-contact, non-destructive, and high-throughput.

[0004] To study interlayer electronic coupling related to torsion angle, such as Raman microscopy... 13 and spectral ellipsometry 14 Optical characterization techniques such as [insert optical characterization techniques here] have been used. However, these methods are limited by measurement throughput, hindering their potential application in large-scale manufacturing. On the other hand, interlayer spacing at the atomic scale varies at the subatomic scale with changes in the torsion angle. Current metrology tools lack the precision and throughput required to effectively detect such weak signals. Therefore, to develop technologies beyond CMOS, it is essential to overcome this major bottleneck in metrology tools.

[0005] As a highly sensitive detection method, laser interferometers have recently made significant progress in detecting extremely weak signals, such as the detection of cosmic gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO). 15 As laser pulse durations have increased from femtoseconds to attoseconds, attosecond pulsed lasers have been used to study electron dynamics in complex molecules and hold promise for ultrafast imaging of electron motion within materials. 16The wide-field imaging capabilities of optical microscopes offer a solution for high-throughput metrology, but they often face the challenge of low imaging contrast when imaging weak-signal samples. Zernike's introduction of the phase contrast concept in optical microscopy can enhance image contrast, thereby achieving high-sensitivity imaging of phase objects. 17,18 Furthermore, the integration of laser interferometers and optical microscopes facilitated the emergence of quantitative phase microscopy (QPM). 19-23 .

[0006] Recently, breakthroughs have been achieved in the development of high-sensitivity QPM, enabling the measurement of the geometric thickness of atomic layers. 24 Dynamic monitoring of neuronal deformation 25 and single protein quality measurement 26 This makes it possible. However, the accuracy of measurements of subatomic structures remains limited because the weak phase signals from these features are often obscured by spatial noise. Various strategies have been proposed, including illumination coherent modulation. 27-29 Average processing (such as frame summation and spatiotemporal filtering) is used to improve sensitivity by suppressing noise. However, these methods cannot meet the detection requirements of subatomic features due to the inherent limitation of the photon shot noise limit. Summary of the Invention

[0007] There is a need in this field to invent a phase-magnification microscopy imaging method.

[0008] According to embodiments of the present invention, a microscopic imaging method with sub-Ångström level measurement accuracy is provided. The method includes: proposing a phase cavity implementation method and connecting the phase cavity to an interferometric imaging system to effectively amplify the phase signal of a target sample; modeling the resonance effect in the phase cavity; and optimizing the parameters of the phase cavity to maximize the amplification of the phase signal of the target sample while suppressing noise. The phase cavity is disposed on the sample side of the interferometric imaging system. Furthermore, the phase cavity is formed by two cavity ends and a cavity body formed by a uniformly manufactured transparent film. Optimizing the parameters of the phase cavity includes optimizing the material of the phase cavity, the thickness of each layer of the phase cavity, and the illumination wavelength. Optimizing the parameters of the phase cavity includes defining a phase gain G factor as an evaluation parameter for phase amplification. The microscopic imaging method may further include acquiring a phase map using a laser-illuminated interferometric imaging system. Additionally, the microscopic imaging method may further include performing a transfer matrix-based model on the measured phase map to reconstruct the thickness mapping results. Furthermore, the microscopic imaging method may further include improving the spatial resolution of the interferometric imaging system by providing synthetic aperture illumination, angular scanning illumination, or short-wavelength illumination. The short wavelength can be extreme ultraviolet (EUV). Furthermore, the phase cavity can be formed from oxide layers such as silicon dioxide (SiO2), nitride layers such as silicon nitride (Si3N4), or by stacking oxide and nitride materials. The measurement accuracy of the interferometric imaging system can reach 0.1 angstroms (Å). Moreover, the method can be further extended to the efficient detection of deep subwavelength defects in three-dimensional stacked samples with a burial depth greater than 2 μm, such as buried defects in 3D NAND flash memory chips. Attached Figure Description

[0009] Figures 1A to 1D This is a schematic diagram of a phase magnifying microscope (Phi-AMP) according to an embodiment of the present invention, wherein... Figure 1A This shows the settings for Phi-AMP; Figure 1B Phi-AMP is built on a reflective high-sensitivity interferometric imaging system. The phase cavity is designed and placed on the sample side of the imaging system using the resonance effect to amplify the weak phase signal that is drowned out by noise through the phase gain G, while the phase noise remains unchanged. Therefore, weak signals that were previously undetectable can be clearly mapped. Figure 1C The transmission matrix model is shown, which accurately simulates the propagation of light in the system, thus allowing the reconstruction of an accurate geometric thickness map from the phase magnification map; Figure 1D This paper presents a theoretical estimate of the subatomic interlayer spacing difference caused by electronic coupling in bilayer graphene (BLG) with different torsion angles, calculated using density functional theory (DFT). Figure 1E The imaging system design of Phi-AMP is shown; Figure 1FThe diagram illustrates the design of a multi-wavelength illumination module, an interferometric detection module, and the corresponding Fourier space multiplexing method for simultaneously acquiring phase maps at multiple wavelengths.

[0010] Figures 2A to 2G The simulation results, experimental verification, and measurement accuracy verification of the phase gain according to an embodiment of the present invention are shown, wherein... Figure 2A The diagram shows the phase gain G versus wavelength λ0 and cavity length. H The simulation results of the relationship between G and cavity length are shown above, with the graph plotted at 532 nm wavelength. H The periodic relationship between 2; Figure 2B The simulation and measurement results show the phase values ​​and CNR, and the analysis of the monolayer graphene sample in 5 chambers is presented. H The second set includes 500 phase maps at 0.262 µm, 0.275 µm, 0.285 µm, 0.305 µm, and 0.322 µm, with a scale bar of 5 µm; Figure 2C The thickness reconstruction model of the 3-layer sample is shown; Figure 2D A comparison of the geometric thickness maps of the sample-free regions with and without cavities is shown; Figure 2E Show along Figure 2D The outline of the area marked in the middle is shown in the figure. The dashed line represents the outline of the area without cavities, and the solid line represents the outline of the area with cavities. Figure 2F An enlarged view of the local geometric thickness of the cavity is shown; Figure 2G Show Figure 2D The histogram of geometric thickness in the figure shows the measurement accuracy in two cases.

[0011] Figures 3A to 3J This illustrates the metrological performance verification of Phi-AMP according to an embodiment of the present invention, wherein... Figure 3A This shows a pattern based on a single-layer graphene material fabricated using electron beam lithography; Figure 3B This shows a geometric thickness diagram of the CUHK pattern produced by Phi-AMP; Figure 3C Show Figure 3B Histogram analysis; Figure 3D This shows a geometric thickness diagram of the CUHK pattern produced by AFM; Figure 3E Show along Figure 3B Comparison of the Phi-AMP and AFM measurement profiles (white dashed lines in the image); Figure 3F and Figure 3G The measurements taken by Phi-AMP and AFM are shown respectively. Figure 3B Geometric thickness diagram of the "K" shape within the white box; Figure 3H Show Figure 3F and Figure 3G Histogram comparison; Figure 3I Showing a resolution version of the geometric thickness diagram of the design; Figure 3J Show along Figure 3I The outline of the dashed lines in the diagram.

[0012] Figures 4A to 4G The diagram shows interlayer spacing measurements of AB-BLG and 30°-tBLG according to an embodiment of the present invention. Figure 4A The synthesis and transfer process of the BLG sample is shown; Figure 4B The stacking configuration of AB-BLG and 30°-tBLG and the corresponding selected area electron diffraction (SAED) pattern are shown. Figure 4C Raman spectra and Lorentz fits in the 2D bands for MLG, AB-BLG, and 30°-tBLG are shown respectively. Figure 4D The DFT calculation results of BLG at different torsion angles are shown; Figure 4E The reconstructed geometric thickness maps of Phi-AMP for AB-BLG and 30°-tBLG are shown respectively. Figure 4F Show each Figure 4E Histograms of the geometric thickness maps of AB-BLG and 30°-tBLG; Figure 4G The independent sample t-test shows that there is a 0.33 Å difference in interlayer spacing (P<0.01) between bilayer graphene samples with different θ. The results show the same trend as the density functional theory (DFT) calculations marked with an asterisk, and are in agreement with the results estimated by low-energy electron microscopy (LEEM) in the literature.

[0013] Figures 5A to 5C This illustrates an embodiment of the invention where further enhancement of phase gain is achieved through optimization of cavity design, such as a Si3N4 / SiO2 cavity, wherein... Figure 5A A schematic diagram of a four-layer sample with two cavities is shown. Figure 5B The phase gain G and the length of the two-layer cavity are shown at a wavelength of 532 nm. d 1 and d The simulation results of the relationship between 2 are plotted. d When 1=0.2 μm, G and d The relationship between 2 and 3 could result in a phase gain of around 1000. Simulation results show that, for example... Figure 5C As shown, a multi-cavity design is used to achieve higher phase amplification. Detailed Implementation

[0014] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, the singular forms "a," "an," and "the / described" are intended to include both the singular and plural forms unless the context clearly indicates otherwise. It will be further understood that the terms "comprising" and / or "including" as used herein indicate the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0015] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will be further understood that terms such as those defined in common dictionaries should be interpreted as having the same meaning as they have in the context of the relevant art and this disclosure, and will not be construed as having an idealized or overly formal meaning unless expressly defined herein.

[0016] When the term “about” is used in conjunction with a numerical value in this document, it will be understood that the value can be in the range of 90% to 110% of the numerical value, that is, the value can be + / - 10% of the stated value. For example, “about 1 kg” refers to 0.90 kg to 1.1 kg.

[0017] In describing this invention, it will be understood that numerous techniques and steps are disclosed. Each technique and step has its own advantages, and each technique and step can be used in conjunction with one or more techniques, or in some cases with all other disclosed techniques. Therefore, for clarity, this specification will avoid unnecessarily repeating every possible combination of the individual steps. However, upon reading the specification and claims, it should be understood that these combinations are fully within the scope of this invention and the claims.

[0018] As a platform for customizing the band gap of atomic materials, torsion electronics plays a crucial role in next-generation electronic devices. The fabrication of these atomic devices urgently requires subatomic-scale metrology techniques to improve device yield. However, existing metrology tools are insufficient to meet these needs due to inadequate precision, accuracy, and throughput.

[0019] According to embodiments of the present invention, a phase magnification microscope (Phi-AMP) can achieve subatomic-level measurement precision. Utilizing the high sensitivity of a laser interferometer and exploring an optimized phase cavity, Phi-AMP can significantly amplify weak phase signals drowned out by noise. Furthermore, the working principle of the phase cavity was investigated, and a 30x phase magnification was demonstrated in a compact system with an imaging time of less than 2 milliseconds by fabricating a phase cavity compatible with an atomic-scale silicon platform. By developing a model of light propagation based on the transfer matrix, graphene geometric thickness maps with an accuracy of 0.1 angstroms within a single frame can be accurately obtained. Thanks to the sub-angstrom level precision, the interlayer spacing difference in torsional bilayer graphene samples was quantified, which is a measurement of the electronic coupling strength as a function of the torsion angle. Moreover, experimental measurements of sub-angstrom-level interlayer spacing differences using Phi-AMP can provide a potential new reference material for torsional bilayer graphene, thus establishing a new metrological standard for sub-angstrom units. Furthermore, the phase cavity can achieve even higher phase magnification through the use of a multilayer cavity design. Therefore, the Phi-AMP method holds promise for new discoveries in torsional electronics and for improving wafer-level atomic fabrication. In addition, addressing the issue that existing wafer buried defect detection solutions cannot simultaneously measure depth and accuracy due to insufficient precision, Phi-AMP aims to amplify the signal of deep subwavelength scale wafer defects by optimizing the measurement target under different buried layer materials and thicknesses, thereby achieving effective detection of deep subwavelength size defects in three-dimensional stacked samples.

[0020] The phase magnification microscope (Phi-AMP) of this invention provides a reliable solution to the challenges of measurement precision, accuracy, and flux in atomic metrology. By studying the working principle of the phase cavity, measurements of monolayer graphene on a SiO2-based phase cavity demonstrated a 30-fold phase magnification, where SiO2 is commonly used as a dielectric layer in atomic devices.

[0021] By integrating an optimized phase cavity into a high-sensitivity laser interferometry imaging system, selectively amplified weak phase maps generated by subatomic structures can be retrieved with high visibility and stability. To extract geometric thickness maps from the amplified phase maps, a thickness reconstruction model was established by accurately simulating light propagation, and experiments determined that the thickness measurement accuracy for a wide field within a single frame is approximately 0.1 Å, with an imaging time of less than 2 milliseconds. This rapid mapping demonstrates that Phi-AMP's measurement throughput is at least 500 times that of existing metrology tools.

[0022] To evaluate the measurement capabilities of the Phi-AMP embodiment of the present invention, geometric thickness maps of patterned atomic structures fabricated using electron beam lithography (EBL) were obtained, and the lateral resolution was quantized. Interlayer spacing maps of AB stacked BLG (AB-BLG) and 30° twisted BLG (30°-tBLG) were plotted with deep sub-angstrom precision, differing by approximately 0.3 angstroms.

[0023] Notably, the precise measurement of sub-angstrom interlayer spacing differences using Phi-AMP positions torsion bilayer graphene as a potential new reference material for sub-angstrom unit measurement standards. Furthermore, the possibility of extending the phase cavity to higher phase amplification levels, potentially achieving sub-picometer accuracy, is discussed. Phi-AMP is expected to drive the development of torsion electronics and next-generation semiconductor manufacturing. In addition, Phi-AMP can be used for the efficient detection of deep subwavelength defects in three-dimensional stacked samples, such as buried defects in 3D NAND flash memory chips. First, utilizing the resonance effect of the phase cavity proposed in Phi-AMP, the corresponding illumination wavelength is optimized for wafer defect detection targets under buried layers of different thicknesses to maximize the amplification of the target defect's phase signal and reflectivity. Then, a high-sensitivity interferometric imaging method based on laser illumination is used to achieve efficient detection of deep subwavelength scale defects.

[0024] In one embodiment, Phi-AMP is based on a reflective laser interferometry imaging system to minimize the impact of environmental noise, which is crucial for achieving high measurement accuracy. To circumvent the limitations of phase noise on measurement accuracy, an optical phase cavity is designed on the sample side of the imaging system. The phase cavity is naturally formed at both ends by the silicon (Si) substrate required for imaging and the sample itself, and the main body of the phase cavity consists of a uniformly fabricated transparent film. By optimizing the cavity design, the resonance effect within the phase cavity can maximize the filtering and amplification of the phase signal of the target sample while suppressing other interfering signals. This ensures that the amplified phase signal of weak signal samples is not masked by noise, thereby improving the visibility of phase imaging. Unlike cavities designed to amplify intensity signals, the sample information encoded in the phase signal can be quantitatively reconstructed based on their physical relationship with the geometric thickness. Using the recursive relationship between defined effective complex refractive index values, the reflected field can be... E r Simplified to equivalent reflection coefficient of equivalent reflective interface r 0,N The expression. Then, it can be derived from... E r The reflected phase value was retrieved when a phase cavity ΔΦ was present. The retrieved amplified phase can be correlated with the sample thickness. H 1. Quantitatively link them, that is Therefore, a geometric thickness reconstruction model can be established, i.e. The geometric thickness map is accurately reconstructed from the magnified phase image. Thanks to phase gain, a high-sensitivity interferometric imaging system, and an accurate thickness reconstruction model, Phi-AMP can resolve subatomic interlayer spacing differences between adjacent layers of the BLG at different torsion angles. The measurement results show the same trend as the theoretical estimates calculated by density functional theory (DFT).

[0025] Reference Figure 1A This shows the settings for the Phi-AMP method. Figure 1B The Phi-AMP is built upon a reflective high-sensitivity interferometric imaging system. A phase cavity designed using resonance effects is introduced on the sample side of the imaging system to amplify weak phase signals drowned out by noise through a phase gain G. On the other hand, the phase noise remains unchanged, allowing previously undetectable weak signals to be clearly mapped. Figure 1C The image shows a thickness reconstruction model that accurately simulates light propagation in a system, thereby obtaining a geometric thickness map. Figure 1D This shows a theoretical estimate of the subatomic interlayer spacing difference caused by electronic coupling in BLGs with different torsion angles, calculated using DFT. Figure 1E The imaging system design of Phi-AMP is shown. Figure 1F The diagram illustrates the design of a multi-wavelength illumination module, an interferometric detection module, and the corresponding Fourier space multiplexing method for simultaneously acquiring phase maps at multiple wavelengths.

[0026] Figures 2A to 2G The simulation results and experimental verification of the phase gain, as well as the measurement accuracy verification, are shown. Specifically, Figure 2A The diagram shows the phase gain G versus wavelength λ0 and cavity length. H The simulation results of the relationship between G and cavity length are shown above, with the graph plotted at a wavelength of 532 nm. H The periodic relationship between 2. Figure 2B The simulation and measurement results show the phase values ​​and CNR, and the analysis of the monolayer graphene sample in 5 chambers is presented. H The second set includes 500 phase maps at 0.262 µm, 0.275 µm, 0.285 µm, 0.305 µm, and 0.322 µm, with a scale bar of 5 µm. Figure 2C The thickness reconstruction model of the three-layer sample is shown. Figure 2D A comparison of the geometric thickness maps of the sample-free regions with and without cavities is shown. Figure 2E Show along Figure 2D The outline of the area marked in the middle is shown, where the dashed line represents the outline of the area without cavities and the solid line represents the outline of the area with cavities. Figure 2F An enlarged view of the local geometric thickness of the cavity is shown. Figure 2G In, it is shown Figure 2DThe histogram of the geometric thickness map shows the measurement accuracy in two cases.

[0027] Figures 3A to 3J The metrological performance verification of Phi-AMP is shown. Specifically, Figure 3A This shows a pattern based on a single-layer graphene material, fabricated using electron beam lithography. Figure 3B This is a geometric thickness map of the CUHK pattern created by Phi-AMP. Figure 3C Show Figure 3B Histogram analysis. Figure 3D This shows a geometric thickness diagram of the CUHK pattern created using AFM. Figure 3E Show along Figure 3B Comparison of the Phi-AMP and AFM measurement profiles (white dashed lines in the middle). Figure 3F and Figure 3G The measurements obtained by Phi-AMP and AFM are shown respectively. Figure 3B Geometric thickness diagram of the "K" shape within the white box. Figure 3H supply Figure 3F and Figure 3G Histogram comparison. Figure 3I It is the geometric thickness map of the design resolution. Figure 3J Show along Figure 3I The outline of the white dashed line in the image.

[0028] Figures 4A to 4G The interlayer spacing measurements and material characterization diagrams for AB-BLG and 30°-tBLG are shown. Specifically, Figure 4A The synthesis and transfer process of the BLG sample is shown. Figure 4B The stacking arrangement of AB-BLG and 30°-tBLG and the corresponding SAED pattern are shown. Figure 4C Raman spectra and Lorentz fits in the 2D bands for MLG, AB-BLG, and 30°-tBLG are shown respectively. Figure 4D Provides DFT calculation results for BLG with different torsion angles. Figure 4E The reconstructed geometric thickness maps of Phi-AMP for AB-BLG and 30°-tBLG are shown respectively. Figure 4F Show each Figure 4E Histograms of the geometric thickness maps of AB-BLG and 30°-tBLG. Figure 4G The independent sample t-test shows that there is a 0.33 Å difference in interlayer spacing (P<0.01) between bilayer graphene samples with different θ, and the results show the same trend as the DFT calculations marked with an asterisk, and are in agreement with the results estimated by low-energy electron microscopy (LEEM) in the literature.

[0029] Figure 5A and Figure 5BThis demonstrates how further enhancements in phase gain can be achieved through optimized cavity design, such as Si3N4 / SiO2 cavities. Specifically, Figure 5A A schematic diagram of a four-layer sample with two cavities is shown. Figure 5B The phase gain G and the length of the two-layer cavity are shown at a wavelength of 532 nm. d 1 and d The simulation results of the relationship between 2 are plotted. d When 1=0.2 μm, G and d The relationship between 2 and 3 could result in a phase gain of around 1000. Simulation results show that, for example... Figure 5C As shown, a multi-cavity design is used to achieve higher phase amplification.

[0030] Materials and methods

[0031] By using the phase gain theoretical model, and by selecting appropriate cavity materials, cavity length and illumination wavelength, an optimized phase cavity can be designed, thereby enabling the target sample to obtain the maximum phase amplification.

[0032] A silicon substrate with a designed cavity was fabricated, and the target sample was transferred onto the silicon substrate. The sample was then imaged using a reflective high-sensitivity interferometric imaging system to quantitatively retrieve the phase map. Subsequently, a geometric thickness map could be obtained using a thickness reconstruction model.

[0033] Example 1:

[0034] In one embodiment, a monolayer graphene film is first synthesized using chemical vapor deposition (CVD). The optimal cavity length for maximizing phase amplification is selected. The fabricated monolayer graphene film is then transferred onto a Si / SiO2 substrate. A designed pattern is then fabricated on the graphene sample using electron beam lithography (EBL). Phase maps of the two graphene samples are obtained using a reflective high-sensitivity interferometric imaging system. The geometric thickness maps of the two graphene samples are obtained using a thickness reconstruction model. Imaging results of line pairs with a spacing of 750 nm demonstrate the lateral resolution of the imaging system. A comparison of the morphological characteristics of the CUHK pattern between AFM and the method of this invention demonstrates the ability of the method of this invention to accurately profile individual atomic layers.

[0035] Example 2:

[0036] In another embodiment, bilayer graphene samples were synthesized using chemical vapor deposition (CVD) and then transferred to a Si / SiO2 substrate for further imaging. The optimal cavity length for maximum phase magnification was selected. The stacking order and exact twist angle of the bilayer graphene samples were characterized using SAED and Raman microscopy. For consistency, identical samples characterized by Raman microscopy were selected for subsequent measurements. Phase maps of two bilayer graphene samples with different stacking orders were obtained using Phi-AMP. The geometric thickness maps of the two graphene samples were obtained using a thickness reconstruction model. The results show that the method of this invention can distinguish an interlayer spacing difference of ~0.3 Å between AB-stacked graphene and 30-degree twist graphene.

[0037] Example 1. A microscopic imaging method with sub-angstrom level measurement accuracy, comprising: proposing a phase cavity implementation method and connecting the phase cavity to an interferometric imaging system to effectively amplify the phase signal of the target sample; modeling the resonance effect in the phase cavity; and optimizing the parameters of the phase cavity to maximize the amplification of the weak phase signal of the target sample while suppressing noise.

[0038] Example 2. According to the method of Example 1, wherein the phase cavity is disposed on the sample side of the interferometric imaging system.

[0039] Example 3. According to the method of Example 1, wherein the phase cavity is formed by two substrates.

[0040] Example 4. According to the method of Example 3, each substrate of the phase cavity is formed of a uniformly manufactured transparent film.

[0041] Example 5. According to the method of Example 1, the parameters of the phase cavity are optimized, including: optimizing the material of the phase cavity, the length of the phase cavity, or the illumination wavelength.

[0042] Example 6. According to the method of Example 1, the optimization of the phase cavity parameters includes: defining the phase gain G factor as an evaluation parameter for phase amplification.

[0043] Example 7. The method according to Example 1 further includes: acquiring a phase map using a laser illumination-based interferometric imaging system.

[0044] Example 8. The method according to Example 7 further includes: performing a model based on the transfer matrix to simulate light propagation in the interferometric imaging system, and reconstructing the thickness mapping results based on the measured phase map.

[0045] Example 9. The method according to Example 8 further includes: performing a numerical method based on finite-difference time-domain (FDTD) or finite element method (FEM) to simulate light propagation in the interferometric imaging system, and reconstructing the thickness mapping results based on the measured phase map.

[0046] Example 10. The method according to Example 7 further includes: improving the spatial resolution of the interferometric imaging system by providing synthetic aperture illumination.

[0047] Example 11. The method according to Example 7 further includes: improving the spatial resolution of the interferometric imaging system by providing angular scanning illumination.

[0048] Example 12. The method according to Example 7 further includes: improving the spatial resolution of the interferometric imaging system by providing short-wavelength illumination.

[0049] Example 13. The method according to Example 1 further includes: further improving phase sensitivity and measurement accuracy by utilizing spatiotemporal filtering and frame summation methods.

[0050] Example 14. The method according to Example 7 further includes: simultaneously acquiring phase maps at multiple wavelengths by providing multi-wavelength illumination and Fourier space multiplexing.

[0051] Example 15. The method according to Example 1, wherein the phase cavity is formed of an oxide layer, such as silicon dioxide (SiO2).

[0052] Example 16. The method according to Example 1, wherein the phase cavity is formed of a nitride layer, such as silicon nitride (Si3N4).

[0053] Example 17. According to the method of Example 1, wherein the phase cavity is formed by stacking an oxide layer and a nitride layer.

[0054] Example 18. The method according to Example 1, wherein the measurement accuracy of the interferometric imaging system reaches 0.1 angstroms.

[0055] Example 19. The method according to Example 1 further includes: effective detection of deep subwavelength size defects in three-dimensional stacked samples with a burial depth greater than 2 μm, such as burial defects in 3D NAND flash memory chips.

[0056] All patents, patent applications, provisional applications and publications mentioned or cited herein are incorporated in their entirety by reference, including all figures and tables, unless otherwise expressly required by this specification.

[0057] It should be understood that the examples and embodiments described herein are for illustrative purposes only, and those skilled in the art can make various modifications or alterations based on these examples and embodiments, which should be included within the spirit and scope of this application and the scope of the appended claims. Furthermore, any element or limitation of any invention or embodiment disclosed herein may be combined with any and / or all other elements or limitations disclosed herein (alone or in any combination) or any other invention or embodiment thereof, all such combinations being within the scope of this invention and not limited thereto.

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Claims

1. A phase magnification microscopy imaging method with sub-angstrom level measurement accuracy, comprising: A phase cavity implementation method is proposed, and the phase cavity is connected to an interferometric imaging system to effectively amplify the phase signal of the target sample; The resonance effect in the phase cavity is modeled; as well as The parameters of the phase cavity are optimized to maximize the amplification of the phase signal of the target sample while suppressing noise.

2. The method according to claim 1, wherein the phase cavity is disposed on the sample side of the interferometric imaging system.

3. The method according to claim 1, wherein the phase cavity is formed by two cavity ends.

4. The method according to claim 3, wherein the cavity body between the two cavity ends is formed of a uniformly manufactured transparent membrane.

5. The method of claim 1, wherein optimizing the parameters of the phase cavity comprises: Optimize the material of the phase cavity, the length of the phase cavity, or the illumination wavelength.

6. The method of claim 1, wherein optimizing the parameters of the phase cavity comprises: Define the phase gain G factor as an evaluation parameter for phase amplification.

7. The method of claim 1, further comprising: Phase maps are obtained using the laser-illuminated interferometric imaging system.

8. The method of claim 7, further comprising: A model based on the transfer matrix is ​​executed to simulate light propagation in the interferometric imaging system, and the thickness mapping results are reconstructed based on the measured phase map.

9. The method of claim 7, further comprising: Numerical methods based on finite-difference time-domain (FDTD) or finite element method (FEM) are used to simulate light propagation in an interferometric imaging system, and thickness mapping results are reconstructed from the measured phase map.

10. The method of claim 7, further comprising: The spatial resolution of the interferometric imaging system is improved by providing synthetic aperture illumination.

11. The method of claim 7, further comprising: The spatial resolution of the interferometric imaging system is improved by providing angular scanning illumination.

12. The method of claim 7, further comprising: The spatial resolution of the interferometric imaging system is improved by providing short-wavelength illumination.

13. The method of claim 12, wherein the short wavelength is an extreme ultraviolet wavelength.

14. The method of claim 1, further comprising: Phase sensitivity and measurement accuracy can be further improved by using spatiotemporal filtering and frame summation methods.

15. The method of claim 1, further comprising: Phase maps at multiple wavelengths can be obtained simultaneously by providing multi-wavelength illumination and Fourier spatial multiplexing methods.

16. The method of claim 1, wherein the phase cavity is formed of an oxide layer, such as silicon dioxide, i.e., SiO2.

17. The method of claim 1, wherein the phase cavity is formed of a nitride layer, such as silicon nitride, i.e., Si3N4.

18. The method of claim 1, wherein the phase cavity is formed by stacking an oxide layer and a nitride layer.

19. The method of claim 1, wherein the measurement accuracy of the interferometric imaging system reaches 0.1 angstroms.

20. The method of claim 1, further comprising: Effective detection of deep subwavelength size defects in three-dimensional stacked samples with a burial depth greater than 2 μm, including burial defects in 3D NAND flash memory chips.

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