Interface-based thin film metrology using second harmonic generation

Abstract

The metrology system may include an illumination source for generating an illumination beam and an illumination subsystem for directing the illumination beam toward a sample having an inversion-symmetric substrate and one or more films disposed on the inversion-symmetric substrate. The system may further include a filter configured to block wavelengths of the illumination beam and pass wavelengths associated with second harmonics of the illumination beam, and a detector for capturing second harmonic generation (SHG) light. The system may further include a controller for receiving metrology data from the detector associated with the SHG light from an interface between the inversion-symmetric substrate and the one or more films, and generating one or more metrology measurements associated with the one or more films based on the metrology data.

Description

[Technical Field]

[0001] The present disclosure relates generally to thin film metrology, and more particularly to surface-selective thin film metrology using second harmonic generation. [Background technology]

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. § 119 of U.S. Provisional Application No. 63 / 428,446, filed November 29, 2022, with Qiang Zhao, Ming Di, Xi Chen, Shova Subedi, and Tianhao Zhang as inventors, which is incorporated herein by reference.

[0003] In the fabrication of advanced semiconductor MOSFET (Metal-On-Silicon Field Effect Device) devices, high-k dielectric metal gates (HKMGs) have been widely used to pursue better performance, lower power, smaller area, and lower cost (PPAC). High-k dielectrics, such as interfacial SiO2 and HfO2, are commonly used as gate materials in MOSFET devices. To modify the device threshold voltage without significantly increasing the gate dielectric thickness, a widely used approach is to introduce or dope another oxygen-rich or oxygen-deficient metal oxide into the high-k film, also known as an interfacial dipole engineering (IDE) layer. Tight control of the doping content is crucial for achieving device performance and higher yields. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 5,392,124 [Patent Document 2] U.S. Patent Application Publication No. 2020 / 0400732 [Patent Document 3] U.S. Patent Application Publication No. 2017 / 0205377 Summary of the Invention [Problem to be solved by the invention]

[0005] Because the IDE equivalent thickness is very small, it is difficult to measure the exact amount of IDE in the high-k film, as well as the efficiency of this IDE content in the gate dielectric film stack, using existing techniques. Similar needs exist for additional devices, such as, but not limited to, ferroelectric field effect transistor (FET) devices, ferroelectric memory devices, and two-dimensional (2D) FET devices. [Means for solving the problem]

[0006] A metrology system is disclosed according to one or more illustrative embodiments. In one illustrative embodiment, the system includes an illumination source for generating an illumination beam. In another illustrative embodiment, the system includes an illumination subsystem including one or more optical elements configured to direct the illumination beam toward a sample, the sample including an inversion-symmetric substrate and one or more films disposed on the inversion-symmetric substrate. In another illustrative embodiment, the system includes a filter configured to block wavelengths of the illumination beam and pass wavelengths associated with the second harmonic of the illumination beam. In another illustrative embodiment, the system includes a detector for capturing second harmonic generation (SHG) light associated with the second harmonic of the illumination beam. In another illustrative embodiment, the system includes a controller for receiving metrology data from the detector associated with SHG light from an interface between the inversion-symmetric substrate and the one or more films, and generating one or more metrology measurements associated with the one or more films based on the metrology data.

[0007] A metrology system is disclosed in accordance with one or more illustrative embodiments. In one illustrative embodiment, the system includes a controller for receiving metrology data from a detector associated with second harmonic generation (SHG) light from a sample in response to an illumination beam, the sample including an inversion-symmetric substrate and one or more films disposed on the inversion-symmetric substrate. In another illustrative embodiment, the controller generates one or more metrology measurements associated with the one or more films based on the SHG light associated with an interface between the inversion-symmetric substrate and the one or more films.

[0008] A method is disclosed according to one or more illustrative embodiments. In one illustrative embodiment, the method includes directing an illumination beam to a sample, the sample including an inversion-symmetric substrate and one or more films disposed on the inversion-symmetric substrate. In another illustrative embodiment, the method includes capturing metrology data based on second harmonic generation (SHG) light from the sample associated with an interface between the inversion-symmetric substrate and the one or more films. In another illustrative embodiment, the method includes generating one or more metrology measurements associated with the one or more films based on the metrology data.

[0009] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description, serve to explain the principles of the invention.

[0010] The many advantages of the present disclosure may be better understood by those skilled in the art by reference to the accompanying drawings. [Brief explanation of the drawings]

[0011] [Figure 1A] FIG. 1 is a block diagram of a second harmonic generation (SHG) measurement system in accordance with one or more embodiments of the present disclosure. [Figure 1B]1 is a simplified diagram of an SHG measurement system in accordance with one or more embodiments of the present disclosure. [Figure 2] FIG. 1 is a schematic side view of a sample suitable for interfacial SHG measurements, in accordance with one or more embodiments of the present disclosure. [Figure 3A] 1 is a schematic side view of an inversion-symmetric substrate formed from silicon with a first film formed as an interfacial layer (II) of SiO 2 and a second film formed as a high-k material, in accordance with one or more embodiments of the present disclosure. [Figure 3B] FIG. 3B is a schematic side view of the material of FIG. 3A after an interfacial dipole engineering (IDE) process, in accordance with one or more embodiments of the present disclosure. [Figure 4] 1 is a schematic side view of a gate region of a multi-channel field effect transistor (FET) in accordance with one or more embodiments of the present disclosure. [Figure 5A] 10 is a simulated graph of SHG light intensity as a function of time for different variations of a sample, in accordance with one or more embodiments of the present disclosure. [Figure 5B] 1 is a simulated graph of SHG light intensity as a function of time as a result of intermittent exposure of a sample to SHG conditions, in accordance with one or more embodiments of the present disclosure. [Figure 6] 1 is a graph of the optical extinction coefficient (k) as a function of wavelength for silicon, in accordance with one or more embodiments of the present disclosure. [Figure 7] 5 is a schematic side view of the gate region of the multi-channel FET of FIG. 4 further depicting wavelength-dependent interfacial SHG measurements in accordance with one or more embodiments of the present disclosure. [Figure 8] FIG. 10 illustrates a simplified simulation of the intensity trend of interfacial SHG in a FET as a function of wavelength, in accordance with one or more embodiments of the present disclosure. [Figure 9] FIG. 1 is a flow diagram illustrating steps performed in a method for interface SHG measurements in accordance with one or more embodiments of the present disclosure. [Figure 10] FIG. 1 is a flow diagram of a method depicting generation of a metrology recipe to meet application-specific requirements, in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Reference will now be made in detail to the disclosed subject matter, which is illustrated in the accompanying drawings. The present disclosure has been particularly shown and described with reference to certain embodiments and particular features thereof. The embodiments set forth herein are to be considered illustrative and not limiting. It will be readily apparent to those skilled in the art that various changes and modifications in form and detail can be made therein without departing from the spirit and scope of the present disclosure.

[0013] Embodiments of the present disclosure are directed to systems and methods for surface-selective metrology of thin films based on second harmonic generation (SHG) techniques. In particular, embodiments of the present disclosure are directed to interfacial SHG measurements for surface-selective metrology of thin film stacks, including substrates with inversion symmetry that hinder SHG in the bulk, such as, but not limited to, silicon. For the purposes of this disclosure, the term inversion-symmetry material will be used to describe materials that have inversion symmetry such that SHG is zero or weak in the bulk of the material. In other words, the second-order nonlinear susceptibility (χ (2) ) is zero or sufficiently small so that SHG in the bulk of the material is negligible for a particular application (e.g., the intensity of SHG in the bulk of the material induced by an illumination beam at a selected intensity is negligible).

[0014] SHG is a nonlinear optical process in which two photons of the same frequency / wavelength interact with an optically nonlinear material, combining their energy and generating a new photon with twice the energy and half the wavelength of the initial photon. Efficient SHG generation typically requires a material lacking inversion symmetry to provide the necessary conditions for the nonlinear optical process. In other words, SHG depends on the second-order nonlinear susceptibility of the material, which is typically low or zero for centrosymmetric or isotropic materials, such that SHG is prevented or at least weak. However, it is contemplated herein that SHG can be generated at the interface of materials with inversion symmetry due to the localized breakdown of this inversion symmetry at the interface. For example, the interface region of such materials may contain an electric dipole that can give rise to SHG.

[0015] As one example, the crystal structure of silicon is a diamond cubic lattice with inversion symmetry (e.g., centrosymmetric), so the electric field and polarization vectors within the Si bulk are unchanged by the inversion system, thus preventing SHG. However, SHG can be generated from higher-order nonlinear responses from inversion-symmetric materials due to electric dipoles on the Si surface and electric quadrupole responses from the Si bulk when an external electric field is applied. In particular, the inversion symmetry is broken along the normal direction at the surface of silicon, and as a result, the second-order surface susceptibility at the interface is nonzero.

[0016] It is further contemplated herein that the strength of SHG generation at the interface of such inversion-symmetric materials is highly sensitive to the presence of additional dipoles near the interface. As used herein, the terms intensity and amplitude, when associated with SHG generation, are used interchangeably to refer to the strength or amount of SHG light. Some embodiments of the present disclosure are directed to systems and methods that utilize interfacial SHG to characterize the properties of one or more thin films adjacent to an inversion-symmetric substrate. Thus, such measurements can provide an indirect measurement of such thin films based on their proximity to the inversion-symmetric substrate.

[0017] It is further contemplated herein that such SHG measurements are well suited for surface-selective metrology of various field-effect transistor (FET) devices, including, but not limited to, field-effect transistors (FETs), metal-oxide-semiconductor FETs (MOSFETs), planar FETs, FinFETs, gate-all-around (GAA) nanosheet FETs, forked-sheet FETs, complementary GAA FETs, ferroelectric FETs, or 2D FETs.

[0018] For example, the gate region of such a FET device typically comprises a silicon substrate (e.g., a centrosymmetric material), an interfacial layer (IL) of silicon dioxide (SiO2), and an interfacial layer (IL) of, but not limited to, hafnium dioxide (HfO2), zirconium dioxide (ZrO2), HfSi x O y , or HfO x N y By way of example, current dielectric gate structures for high performance semiconductor devices include a silicon substrate, an IL SiO2 layer having a thickness of about 5-8 Angstroms, and a high-k layer having a thickness of about 10-30 Angstroms. The voltage characteristics (e.g., V t Precise control over the kV (value) is typically achieved through an interfacial dipole engineering (IDE) layer on the high-k material, which introduces or dopes the high-k dielectric material with an oxygen-rich or oxygen-deficient metal oxide to generate a dipole for voltage control. The effective thickness of this IDE layer is typically very small (e.g., on the order of 2 angstroms or thinner) and therefore difficult to monitor for process control, yet has a significant impact on FET performance.

[0019] For example, typical thickness or material analysis techniques, such as spectroscopic ellipsometry, x-ray reflectometry (XRR), x-ray fluorescence (XRF), x-ray diffraction (XRD), MetaPULSE, x-ray photoelectron spectroscopy (XPS), or transmission electron microscopy (TEM), either provide insufficient resolution, cannot target critical gate / channel regions that affect device performance, and / or are not suitable for characterizing 3D structures. Furthermore, in the case of 3D FET device structures, current techniques, whether real or proxy, cannot measure IDE-doped high-k thin films, ferroelectric thin films, and 2D layered thin films in selected regions, such as the transistor's channel / gate region, without including the same materials elsewhere in the transistor. For example, current techniques can perform suitable thickness and material composition / dosage measurements, but lack sensitivity to specific surface and interface regions and provide only limited value for measurements directly related to device performance. As another example, surface-based techniques, such as scanning probe microscopy, are limited to surface measurements, typically have low measurement throughput, and / or are not suitable for measuring 3D structures.

[0020] In some embodiments, interfacial SHG light from the interface of an inversion-symmetric substrate (e.g., silicon) is used to characterize the properties of the adjacent IL / high-k / IDE material, including, but not limited to, layer thickness, layer composition, presence of defects, charge / trap states, stress / strain, charge mobility, or surface / interface roughness.

[0021] Additionally, high-k / I-D layers are commonly fabricated over various portions of FET devices, which can significantly impact device performance (e.g., V tThe interfacial SHG (SHG) value is primarily determined by the properties of the high-k / IdE layer at the gate / channel interface, which is fabricated on top of the interfacial SiO2 layer and silicon substrate (e.g., an inversion-symmetry material). As a result, the selective presence of the centrosymmetric substrate at a region of interest on a FET device not only provides a mechanism for interfacial SHG, but also provides highly selective measurements localized to this region of interest. Such interfacial SHG measurements, as presented herein, can therefore provide highly sensitive and selective measurements that can be directly correlated to device performance.

[0022] Some embodiments of the present disclosure are directed to various SHG measurement techniques or modes. In some embodiments, an illumination beam is directed to a sample (e.g., containing a FET device), and the SHG light is captured using a detector and a filter (e.g., a bandpass filter) to isolate the SHG signal. The illumination beam can generally be directed to the sample at any angle, including normal or off-axis incidence. In some embodiments, the sample is further exposed to additional stimuli to enhance the SHG signal and thus the signal-to-noise ratio (SNR) of the measurement. For example, the sample can be simultaneously illuminated with a separate light source and / or electric field to excite dipoles in the IDEs layer during measurement. In some embodiments, time-domain SHG signals (TD-SHG) are measured. For example, the evolution of the SHG signal over time in response to incident illumination and / or additional stimuli can be measured to provide additional information about the IDEs layer and associated dipoles. In some embodiments, SHG signals associated with different wavelengths of incident illumination are measured. It is contemplated herein that the penetration depth of incident illumination into a multi-channel FET device may vary based on wavelength, such that different wavelengths of incident illumination may probe different depths of the FET.

[0023] 1A-10, systems and methods for selective metrology using SHG will be described in more detail in accordance with one or more embodiments of the present disclosure.

[0024] 1A and 1B are block and simplified diagrams of an SHG measurement system 100, in accordance with one or more embodiments of the present disclosure.

[0025] In some embodiments, the SHG measurement system 100 includes an illumination source 102 configured to generate an illumination beam 104, an illumination subsystem 106 including one or more optical elements for directing the illumination beam 104 to a sample 108, and a collection subsystem 110 including one or more optical elements for directing SHG light 112 generated by the sample 108 in response to the illumination beam 104 to a detector 114. For example, the spectrum of the SHG light 112 may have twice the frequency or half the wavelength of the spectrum of the illumination beam 104.

[0026] Illumination source 102 may be any light source known in the art suitable for generating illumination beam 104 suitable for inducing SHG light 112 in sample 108. In some embodiments, illumination source 102 is a laser source, such that illumination beam 104 is a coherent laser beam.

[0027] Illumination beam 104 may further have any selected spectral content. For example, illumination beam 104 may have a selected wavelength (or center wavelength) within any spectral range, such as, but not limited to, ultraviolet (UV), visible, infrared (IR), or near-IR. In some embodiments, illumination source 102 may include a laser source. In some embodiments, illumination source 102 is a tunable source (e.g., a tunable laser source or a tunable non-laser source). In this manner, illumination beam 104 may have a tunable wavelength, center wavelength, or more generally, spectrum. For example, illumination source 102 may include, but is not limited to, a Ti:Sapphire laser source or a Yb-KGW laser source.

[0028] The illumination beam 104 can generally have any temporal profile. In some embodiments, the illumination beam 104 is formed as a train of pulses. Such pulses can have any pulse duration. As a non-limiting example, the illumination beam 104 can have pulse durations on the picosecond, femtosecond, or attosecond scale, commonly referred to as ultrashort pulses. Such ultrashort pulses can beneficially provide high peak power suitable for efficiently inducing SHG within the sample 108. Such pulses can also have any repetition rate, including, but not limited to, repetition rates in the kHz-MHz range.

[0029] The illumination subsystem 106 may include any combination of optical components suitable for directing the illumination beam 104 to the sample 108 and / or controlling the characteristics of the illumination beam 104. For example, the illumination subsystem 106 may include one or more lenses 116 to control the spot size of the illumination beam 104 on the sample 108. As another example, the illumination subsystem 106 may include one or more illumination control components 118 to control parameters of the illumination beam 104, such as, but not limited to, the intensity, wavelength (or more generally, spectrum), polarization, spot size on the sample 108, or angle of incidence on the sample 108. For example, the illumination control components 118 may include, but are not limited to, one or more polarizers, one or more spectral filters, one or more spatial filters, or one or more apodizers. Such illumination control components 118 may be located in any suitable location, including, but not limited to, a pupil plane or a field plane. Furthermore, the illumination subsystem 106 may direct the illumination beam 104 to the sample at any angle of incidence, including normal incidence (eg, as depicted in FIG. 1B) or off-axis incidence.

[0030] The collection subsystem 110 may include any combination of optical components suitable for directing the SHG light 112 from the sample 108 to the detector 114. In some embodiments, the collection subsystem 110 includes one or more lenses 120 for collecting light from the sample 108. In some embodiments, the collection subsystem 110 includes one or more collection control components 122 for controlling parameters of the collected light, such as, but not limited to, the intensity, wavelength (or more generally, spectrum), polarization, collection location on the sample 108, or angle of collection. For example, the collection control components 122 may include, but are not limited to, one or more polarizers, one or more spectral filters, one or more spatial filters, or one or more apodizers.

[0031] In some embodiments, the collection subsystem 110 (e.g., the collection control component 122) includes a filter 124 to selectively pass the SHG light 112 to the detector 114 or to at least block reflected light associated with the spectrum of the illumination beam 104. For example, the filter 124 may include one or more spectral filters (e.g., a dielectric filter, or the like), such as, but not limited to, a bandpass filter to selectively pass the SHG light 112, a bandstop filter to selectively reject the spectrum of the illumination beam 104, or a low-pass filter (e.g., a low-pass wavelength filter) having a cutoff to block the spectrum of the illumination beam 104 and pass the spectrum of the SHG light 112. As another example, the filter 124 may include a spatial filter to selectively pass the SHG light 112 followed by a dispersive element to spectrally disperse the light exiting the sample 108.

[0032] In some embodiments, various components of the illumination subsystem 106 and the collection subsystem 110 are coupled or operated in conjunction. For example, the SHG process is dependent on the polarization of the illumination beam 104. Accordingly, the illumination subsystem 106 may include a polarizer (e.g., one of the illumination control components 118) configured to provide a polarization of the illumination beam 104 that maximizes the intensity of the SHG light 112. The collection subsystem 110 may then include a polarizer (e.g., one of the collection control components 122) configured to isolate the filters 124 having associated polarizations.

[0033] The detector 114 may include any component or combination of components suitable for detecting the SHG light 112 and providing measurement data associated with the SHG light 112. In some embodiments, the detector 114 includes a single-pixel device, such as, but not limited to, a photodetector, an avalanche photodiode, or a photomultiplier. In some embodiments, the detector 114 includes a multi-pixel device, such as, but not limited to, a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) device. In some embodiments, the detector 114 includes a spectrometer suitable for measuring the spectrum of light emerging from the sample 108 in response to the illumination beam 104. In general, the SHG measurement system 100 may include any number or type of detectors 114. In this manner, the SHG measurement system 100 may more generally be suitable for additional measurements beyond SHG measurements, such as, but not limited to, Raman spectroscopy or photoluminescence.

[0034] In some embodiments, SHG measurement system 100 includes one or more excitation sources 126 to enhance SHG generation by illumination beam 104. Excitation source 126 may include any type of source suitable for enhancing SHG generation associated with illumination beam 104, such as, but not limited to, an additional illumination source or an electric field source.

[0035] In some embodiments, the excitation source 126 includes an additional illumination source configured to generate an additional illumination beam 128. In this configuration, the SHG measurement system 100 may direct the additional illumination beam 128 to the same portion of the sample 108 at the same or a different illumination angle as the illumination beam 104. For example, FIG. 1B depicts the additional illumination beam 128 incident on the sample 108 at a normal incidence angle. As a result, the additional illumination beam 128 may generate charge separation at one or more interfaces of the sample 108, thus inducing a DC electric field, which may contribute to the SHG process and thus increase the intensity of the SHG light 112.

[0036] In some embodiments, the excitation source 126 includes an electric field source (not explicitly shown in FIG. 1B ) configured to generate an electric field 130. For example, the electric field 130 can be oriented perpendicular to the surface of the sample 108 to modify the SHG behavior of the sample 108. It should be appreciated that electric-field-induced second-harmonic generation (EFISH) is a third-order nonlinear process depending on the interaction of the electric field with incident photons. In some embodiments, the DC electric field 130 is applied to the symmetry-broken surface to enhance the generation of interface SHG light 112 associated with the illumination beam 104. In particular, the SHG light 112 is generated by the interface SHG process and can be enhanced by the contribution of third-order electric susceptibility due to the external electric field 130. It is contemplated herein that EFISH techniques have been commonly utilized to analyze material properties, but not for surface-selective SHG measurements as disclosed herein.

[0037] In some embodiments, the overlay metrology system 100 further includes a controller 132 having one or more processors 134 configured to execute program instructions maintained in a memory 136 (e.g., a memory medium). The controller 132 may be communicatively coupled to any of the components of the SHG metrology system 100, such as, but not limited to, the detector 114. In this manner, the controller 132 may receive metrology data from the detector 114 associated with the SHG light 112 from the sample 108 and generate one or more metrology measurements associated with the sample (e.g., a film near an interface with an inversion-symmetric substrate) based on the metrology data (e.g., according to a metrology recipe).

[0038] The one or more processors 134 of the controller 132 may include any processor or processing element known in the art. For purposes of this disclosure, the term “processor” or “processing element” may be broadly defined to encompass any device having one or more processing or logic elements (e.g., one or more microprocessor devices, one or more application specific integrated circuit (ASIC) devices, one or more field programmable gate arrays (FPGAs), or one or more digital signal processors (DSPs)). In this sense, the one or more processors 134 may include any device configured to execute algorithms and / or instructions (e.g., program instructions stored in memory). In one embodiment, the one or more processors 134 may be embodied as a desktop computer, mainframe computer system, workstation, image computer, parallel processor, networked computer, or any other computer system configured to execute programs configured to operate or in conjunction with the overlay metrology system 100, as described throughout this disclosure.

[0039] Furthermore, different subsystems of overlay metrology system 100 may include processors or logic elements suitable for performing at least a portion of the steps described in this disclosure. Accordingly, the above description should not be construed as a limitation on embodiments of the present disclosure, but merely as illustrative. Furthermore, the steps described throughout this disclosure may be performed by a single controller 132, or alternatively, by multiple controllers. Additionally, controller 132 may include one or more controllers housed in a common housing or within multiple housings. In this manner, any controller or combination of controllers may be packaged separately as a module suitable for integration into overlay metrology system 100.

[0040] The memory 136 may include any storage medium known in the art suitable for storing program instructions executable by the associated one or more processors 134. For example, the memory 136 may include a non-transitory memory medium. As another example, the memory 136 may include, but is not limited to, read-only memory (ROM), random access memory (RAM), magnetic or optical memory devices (e.g., disks), magnetic tape, solid-state drives, and the like. It is further noted that the memory 136 may be housed together with one or more processors 134 in a common controller housing. In one embodiment, the memory 136 may be located remotely relative to the physical location of the one or more processors 134 and the controller 132. For example, the one or more processors 134 of the controller 132 may access a remote memory (e.g., a server) accessible over a network (e.g., the Internet, an intranet, and the like).

[0041] 2-8, interfacial SHG for thin film metrology will be described in more detail in accordance with one or more embodiments of the present disclosure.

[0042] FIG. 2 includes a schematic side view of a sample 108 suitable for interfacial SHG measurements, in accordance with one or more embodiments of the present disclosure.

[0043] In some embodiments, the sample 108 includes an inversion-symmetric substrate 202 and one or more films 204 (eg, thin films) of a material to be characterized disposed on the inversion-symmetric substrate 202 .

[0044] The inversion symmetric substrate 202 may include any type of material known in the art that possesses inversion symmetry, such as, but not limited to, a centrosymmetric material (e.g., centrosymmetric crystal) or an isotropic material (e.g., glass). In this manner, SHG may be zero or weak within the bulk of the inversion symmetric substrate 202. Furthermore, the inversion symmetric substrate 202 may have any material phase, such as, but not limited to, crystal, glass, or ceramic. In some embodiments, the inversion symmetric substrate 202 is reflective to at least the wavelength of the SHG light 112 such that the SHG light 112 is reflected from the sample 108 and collected by the collection subsystem 110 on the side of the illumination subsystem 106 common to the sample 108. In some embodiments, the inversion symmetric substrate 202 includes a crystalline semiconductor substrate, such as, but not limited to, silicon.

[0045] The one or more films 204 can comprise any type of material known in the art. In some embodiments, the one or more films 204 also have inversion symmetry. In some embodiments, the one or more films 204 are SiO 2( For example, IL), and / or without limitation, Si3N4, Al2O3, Ta2O5, TiO2, ZrO2, HfO2, HfSi x O y , or HfO x N y and other high-k materials.

[0046] It is contemplated herein that interface SHG may be suitable for thin film metrology of a wide variety of devices and materials (e.g., features on a sample 108). For example, a sample 108 suitable for interface SHG metrology may include a ferroelectric random access memory (FeRAM) and a ferroelectric FET device. By way of example, the sample 108 may include a ferroelectric thin film stack, which may include one or more HfO2 films 204 doped with materials such as, but not limited to, Zr, Al, Gd, La, Si, Sr, and Y. As another example, the sample 108 may include one or more HfO2 films 204 with oxides, such as, but not limited to, SiO2 / HfO2 / AlO3 or HfO2 / ZrO2 / HfO2. As another example, interface SHG may be used to measure various aspects of 2D materials, such as, but not limited to, the number of layers, thickness, or the presence of defects. By way of example, the sample 108 may include a transition metal dichalcogenide, such as, but not limited to, MoS2, MoSe2, MoTe2, WS2, or WSe2. As another example, the sample 108 may include a III-IV chalcogenide, such as, but not limited to, InSe or GaSe.

[0047] 3A and 3B are side views of thin film stacks formed from materials common to at least some FET devices. In particular, FIG. 3A is a schematic side view of an inversion-symmetric substrate 202 formed from silicon with a first film 204a formed as an IL of SiO2 and a second film 204b formed as a high-k material (e.g., an annealed high-k material) in accordance with one or more embodiments of the present disclosure. FIG. 3B is a schematic side view of the material of FIG. 3A after an IDE process in accordance with one or more embodiments of the present disclosure.

[0048] As depicted in Figure 3A, the interface associated with the film 204 on the inversion-symmetric substrate 202 may have an electric dipole 302 that can contribute to interfacial SHG. The electric dipole 302 in Figure 3A may be primarily associated with the breaking of inversion symmetry at the interface. In Figure 3B, the interface may have an additional electric dipole 302 associated with the IDE layer that may further contribute to the interfacial SHG process. In this manner, interfacial SHG may be suitable for characterizing various materials associated with the interface, including, but not limited to, the IDE electric dipole 302 associated with the IDE process.

[0049] Referring now to FIG. 4, the use of interfacial IHG for surface-selective metrology will be described in more detail in accordance with one or more embodiments of the present disclosure.

[0050] 4 is a schematic side view of the gate region of a multi-channel FET 402, in accordance with one or more embodiments of the present disclosure. In FIG. 4, the FET 402 includes a series of vertically distributed silicon substrates coated with an IL SiO2 layer and a high-k / IdE layer.

[0051] The performance of the FET 402 (e.g., V t The V value is highly sensitive to, and can be controlled by, the specific characteristics of the high-k / IDE layer in the gate channel region (e.g., the generation of electric dipoles 302 in these regions), and is much less sensitive to the specific characteristics of the high-k / IDE layer in other regions of the FET 402. It is further contemplated herein that the gate channel region of the FET 402 beneficially has the structure depicted in FIG. 3B . In particular, these regions include various interfaces of an inversion-symmetric substrate 202 (e.g., a silicon substrate) coated with an IL and a high-k / IDE film 204 as depicted in FIG. 3B . As a result, such regions can generate interface SHG light 112 with measurable properties related to the electric dipoles 302 in these interface regions. The measured properties of the SHG light 112 from these regions not only characterize the physical properties of the Si / IL / high-k / IDE interface region, but also the operational characteristics (e.g., V tIt can also be directly related to the

[0052] Additionally, high-k / I-D layers may be present in various additional portions of the FET 402 (e.g., the gate spacer 404, inner spacer 406, or source / drain EPI regions 408 in various configurations), but such additional portions of the FET 402 lack the specific Si / IL / high-k / I-D interface and may therefore exhibit substantially different interface SHG characteristics. Thus, SHG light 112 from the gate channel region of interest can be distinguished from SHG light 112 (if present) from other regions to provide surface-selective metrology of these regions of interest. Furthermore, as described in more detail with respect to FIGS. 6-8 , SHG light 112 from individual channels 410 or interfaces therein can be separately distinguished (e.g., identified, separated, or the like) to provide selective measurements of the characteristics of each channel 410.

[0053] 4, it should be understood that FIG. 4 and the associated description are provided for illustrative purposes only and should not be construed as limiting. Rather, interfacial SHG can be used for surface-selective thin film metrology of any suitable interface between an inversion-symmetric substrate 202 and one or more adjacent films 204.

[0054] 5A-8, various interface SHG measurements (or measurement modes) will be described in more detail in accordance with one or more embodiments of the present disclosure. Such measurements may be performed using, but are not limited to, the SHG measurement system 100 depicted in FIGS. 1A-1B.

[0055] 5A is a simulated graph of the intensity of SHG light 112 as a function of time for different sample variations represented by lines 502, 504, and 506, in accordance with one or more embodiments of the present disclosure. Such regions may generally correspond to variations in the thin film stack (e.g., as depicted in FIG. 3B), such as, but not limited to, composition variations, thickness variations, IDE variations, or surface roughness variations. As depicted in FIG. 5A, the intensity of the interface SHG light 112 generally exhibits a sharp rise followed by saturation at the saturated intensity.

[0056] It is contemplated herein that metrology data associated with the interface between the target film 204 and the inversion-symmetric substrate 202 may be generated based on any aspect of SHG light 112 measurable by the detector 114 based on illumination of the sample 108 by the illumination beam 104, with or without additional excitation from an excitation source 126 (e.g., an additional illumination beam 128, an electric field 130, or the like).

[0057] In some embodiments, metrology data associated with the interface between the film of interest 204 and the inversion-symmetric substrate 202 is generated based on the saturation intensity of the SHG light 112. For example, the saturation intensity may correspond to a number of electric dipoles 302 introduced by the IDE process and / or the thickness of the IDE layer. As one non-limiting example, in applications where the composition and thickness of the IL and / or high-k layer are known, the different saturation intensities depicted by lines 502-506 may correspond to different IDE layer thicknesses (and corresponding numbers of generated electric dipoles 302).

[0058] In some embodiments, metrology data associated with the interface between the film of interest 204 and the inversion-symmetric substrate 202 is generated based on time-dependent characteristics of the SHG light 112, such as, but not limited to, the initial slope of intensity, the intensity of the SHG light 112 at any particular time (I @ Tm in FIG. 5A ), the intensity of the SHG light 112 at the saturation point (I @ Saturation in FIG. 5A ), or the time required to reach saturation intensity. For example, a time-dependent SHG (TD-SHG) graph, such as that depicted in FIG. 5A , can provide information about properties, such as, but not limited to, charges and traps, originating from the thin film stack adjacent to the interface with the inversion-symmetric substrate 202, which can further facilitate the determination of properties, such as, but not limited to, thin film thickness, composition, electrical structure, defects, or surface / interface roughness. Furthermore, such TD-SHG graphs can provide metrology data associated with photon-induced charge traps and dopant levels, carrier dynamics, and interface local fields. It is contemplated herein that such measurements may not be achievable by conventional electrical measurements.

[0059] FIG. 5B is a simulated graph of the intensity of SHG light 112 as a function of time as a result of intermittent exposure (e.g., cycles) of a sample 108 to SHG conditions, according to one or more embodiments of the present disclosure. In FIG. 5B, conditions for generating SHG light 112, such as, but not limited to, the illumination beam 104 and / or excitation source (e.g., additional illumination beam 128, electric field 130, or the like), are cycled on and off. For example, the illumination beam 104 and / or excitation source are turned off at the times marked "X" in FIG. 5B and turned on at the times marked "O." Such a graph may be suitable for, but is not limited to, measuring charge mobility within the sample 108, which may provide insight into device clock performance, reliability, or the like. By way of example, the initial intensity of SHG light 112 for different cycles increases in FIG. 5B, showing information about the lifetime of excited states.

[0060] By way of example, when cycling the electric field 130 and a sample 108 having a Si / SiO2 / high-k / IDE stack (e.g., as depicted in FIG. 3B), charges and traps can be generated by any combination of IDE doping into the high-k film 204, the additional illumination beam 128, if present, or the primary illumination beam 104. The presence of the external electric field 130 can then excite electrons in the silicon valence band through a three-photon excitation process. This can leave vacancy states, allowing the excited electrons to drift to the oxide conduction band. The remaining holes and electrons in the silicon valence band can then be captured by oxygen molecules from the SiO2 IL to create a capacitor-like structure that generates a DC electric field across the SiO2 IL, which can affect the characteristics of the interface SHG light 112. By way of example, for Si / SiO2 / HK / IDE samples 108 with different IDE concentrations, the charge and trap densities in the SiO2 IL may be different, which leads to differences in the DC electric field in the presence of an external electric field 130 and corresponding differences in the resulting SHG light 112. Such an approach is called electric-field-induced SHG (EFISH).

[0061] However, in a general sense, a time-dependent SHG graph such as that illustrated in FIG. 5B can be generated by cycling the illumination source 102, maintaining the illumination source 102 but cycling the additional illumination beam 128 and / or electric field 130, or cycling any combination of these.

[0062] 6-8, depth-dependent interfacial SHG signals using wavelength tuning will be described in more detail in accordance with one or more embodiments of the present disclosure.

[0063] It is contemplated herein that depth-dependent interface SHG information can be generated by controlling the wavelength of the illumination beam 104 (and thus the generated SHG light 112 at half the wavelength of the illumination beam 104) relative to the attenuation characteristics of the sample 108. In particular, the attenuation characteristics of the sample 108 can limit both the initial penetration depth of the illumination beam 104 into the sample 108 as well as the extent to which the subsurface-generated SHG light 112 can propagate outside the surface for detection.

[0064] 6 is a graph of the optical extinction coefficient (k) as a function of wavelength for silicon (e.g., a common inversion-symmetric substrate 202 for semiconductor applications) in accordance with one or more embodiments of the present disclosure. As depicted in FIG. 6, silicon is generally transparent at wavelengths above 380 nm, with an extinction peak at approximately 290 nm.

[0065] 7 is a schematic side view of the gate region of the multi-channel FET 402 of FIG. 4 further illustrating wavelength-dependent interfacial SHG measurements in accordance with one or more embodiments of the present disclosure. In FIG. 7, wavelengths with increasing wavelength are illustrated as propagating deeper into the FET 402. In particular, FIG. 7 depicts the interaction of the illumination beam 104 with the various channels 702 at different depths.

[0066] FIG. 8 is a simplified simulation of the intensity trend of interfacial SHG within FET 402 as a function of wavelength, in accordance with one or more embodiments of the present disclosure.

[0067] 6 and 7, increasing the wavelength of the illumination beam 104 can result in both increased penetration of the illumination beam 104 and increased transmission of the half-wavelength SHG light 112. For silicon, the effect of increasing wavelength is particularly noticeable when the wavelength of the SHG light 112 is around 290 nm (e.g., associated with the peak attenuation coefficient in FIG. 6) and above.

[0068] 7, SHG light 112 can be generated at multiple interfaces within a given penetration depth (particularly the surface-selective interface between an inversion-symmetric substrate 202 as described herein and a film of interest 204 associated with one or more channels 702). As a result, the intensity of SHG light 112 can generally be based on the cumulative emission from interfaces within the penetration depth. As a result, various depth-based metrology measurements are possible.

[0069] In some embodiments, depth-dependent metrology data is generated based on scanning the wavelength of the illumination beam 104 (and thus the wavelength of the SHG light 112) through a region where the attenuation of the illumination beam 104 and / or the SHG light 112 varies. In this manner, increasing the wavelength advantageously provides increasing SHG light 112 as additional interfaces of interest are characterized. By way of illustration, FIG. 8 depicts increasing SHG light 112 as a function of wavelength and further depicts different plateaus of SHG light 112 associated with various channels 702 within the FET 402. In this manner, the trend of the SHG light 112 as a function of wavelength can provide specific information related to the structure of the FET 402. Furthermore, gathering cumulative information about the various interfaces allows for quantitative metrology measurements of each interface and / or each channel 702.

[0070] In some embodiments, metrology data can be generated based on measurements of SHG light 112 at specific selected wavelengths. For example, for reasons such as measurement efficiency, it may not be desirable to perform a wavelength scan in some applications. In this case, metrology data associated with measurements of SHG light 112 at known wavelengths associated with known penetration depths can provide cumulative or average information for all interfaces of interest within the penetration depth. Illustratively, scanning all three channels of FET 402 at known selected wavelengths (e.g., wavelengths within the plateau region associated with the lower channel as shown in FIG. 8 ) can provide information about all three channels. For example, such data can be used to provide average data for interfaces within the penetration depth, and attenuation as a function of depth can be taken into account, if necessary. Furthermore, additional assumptions or knowledge about various channels and / or attenuation trends as a function of depth can be used to generate specific information about any of the interfaces of interest.

[0071] 6-8 and the associated description are provided for illustrative purposes only and should not be construed as limiting. Rather, the concepts disclosed herein may be extended to any type of sample 108 having any type of structure or combination of materials.

[0072] 5A-8, metrology data related to an interface of interest within the sample 108 may be generated using any combination of time-domain and wavelength-domain measurements. For example, time-domain measurements may be generated for any number of wavelengths.

[0073] 9 and 10, a method for performing interfacial SHG measurements will be described in more detail.

[0074] 9 is a flow diagram illustrating steps performed in a method 900 for interface SHG measurement, in accordance with one or more embodiments of the present disclosure. Applicant notes that the embodiments and enabling techniques described herein above in the context of SHG measurement system 100 should be construed as extending to method 900. However, it is further noted that method 900 is not limited by the architecture of SHG measurement system 100.

[0075] In some embodiments, the method 900 includes a step 902 of directing an illumination beam 104 to a sample 108 having an inversion-symmetric substrate 202 and one or more films 204 disposed on the inversion-symmetric substrate 202. In some embodiments, the method 900 includes a step 904 of capturing metrology data based on SHG light 112 from the sample 108 associated with an interface between the inversion-symmetric substrate 202 and the one or more films 204. For example, steps 902 and 904 may be, but are not required to be, performed using an SHG metrology system 100 such as illustrated in FIGS. 1A-1B. Furthermore, steps 902 and 904 may be performed using any suitable technique. For example, the illumination beam 104 may be scanned across the sample 108 or may be stationary during measurements. By way of example, although not explicitly illustrated in FIG. 1B, the illumination beam 104 may be scanned relative to the sample 108 using a beam scanning optical element (e.g., a galvo mirror, or the like), and / or the sample 108 may be translated relative to the illumination beam 104 using one or more translation stages.

[0076] In some embodiments, the method 900 includes generating 906 one or more metrology measurements associated with the one or more films 204 based on the metrology data. As described previously herein, the SHG light 112 may be generated based on the interface between the inversion-symmetric substrate 202 and the one or more films 204 of interest due to the breaking of inversion symmetry at the interface. It is contemplated herein that characteristics of the SHG light 112 (e.g., amplitude, temporal characteristics, or the like) may be sensitive to electric dipoles 302 in the one or more films 204 adjacent to the interface. In this manner, the SHG light 112 may provide an indirect metrology measurement of properties of these adjacent films 204, such as, but not limited to, layer thickness, layer composition, presence of defects, charge / trap states, stress / strain, charge mobility, or surface / interface roughness. As a non-limiting example, for a FET (e.g., the multi-channel FET 402 depicted in FIG. 4), metrology measurements may be associated with such properties of the high-k / I-D film 204 adjacent to the inversion-symmetric substrate 202 (e.g., silicon, or the like). In some embodiments, the metrology measurements generated in step 906 are associated with operational and / or performance characteristics of a functional device. Continuing with the illustration of the multi-channel FET 402 depicted in FIG. 4, the metrology data may be associated with V t value or V t For example, the value of Vt of the FET 402 when fully fabricated may be directly affected by the electric dipoles 302 in the high-k / I-D films 204 in the gate / channel region, and as a result, metrology measurements made in step 906 based on the SHG light 112 at the interface between these films 204 and the inversion-symmetric substrate 202 may predict Vt. t The value of V can be directly estimated or used for process control. t can be used either to provide a value indicative of

[0077] Furthermore, the characteristics of the SHG light 112 may be highly specific to particular interfaces and thus may provide surface-selective metrology at these interfaces. In some embodiments, the metrology measurements generated in step 906 are based on the SHG light 112 identified as associated with the interfaces of interest. For example, the method 900 may include identifying regions of interest on the sample 108 based on the SHG light 112 captured in step 904 and using the associated SHG light 112 to generate surface-selective metrology measurements. As a non-limiting example, in the case of a multi-channel FET 402 such as that depicted in FIG. 4, the characteristics of the SHG light 112 (e.g., intensity, temporal characteristics, wavelength-specific characteristics, or any combination thereof) may be distinguishable in the gate / channel region depicted in FIG. 4 based on the selective presence of the inversion-symmetric substrate 202 coated with the high-k / Ide layer in that region but not in other regions. In some embodiments, design data associated with the sample 108 may additionally or alternatively be used to identify the SHG light 112 from the regions of interest for generation of the metrology measurements.

[0078] In some embodiments, the method further includes controlling one or more fabrication processes based on the metrology data. Such control may include any combination of feedback control (e.g., to control the fabrication process for additional samples 108 in the lot) or feedforward control (e.g., to control the fabrication process for the same sample 108 to compensate for measured variations). Continuing with the illustration of a multi-channel FET 402 as depicted in FIG. 4 , the method may include controlling processes associated with fabricating the high-k and / or IDE film 204 based on metrology measurements based on SHG light 112 from and associated with electric dipoles 302 in gate regions of the FET (e.g., FET 402).

[0079] In some embodiments, metrology measurements based on the SHG light 112 (or metrology data from the detector 114 indicative of such SHG light 112) are generated in part using calibration metrology data associated with known variations in the interface between the inversion-symmetric substrate 202 and the one or more films 204. For example, the method 900 may include fabricating one or more calibration samples having known variations in the interface between the inversion-symmetric substrate 202 and the one or more films 204 to provide a design of experiments (DOE). Illustratively, the DOE may provide variations in the FET 402 associated with known variations in the IDE process, the thickness of any component, the composition of any component, or any other parameter. The method 900 may then include generating calibration metrology data (e.g., time-resolved and / or wavelength-resolved measurements of the SHG light 112 with or without the additional illumination beam 128 and / or electric field 130) of the one or more calibration samples and correlating the metrology data with the known variations. In this manner, quantitative metrology measurements for a new sample 108 having unknown parameters can be generated based on the metrology data from the new sample 108 and the calibration metrology data.

[0080] 10 , generation of a metrology recipe will be described in accordance with one or more embodiments of the present disclosure. The metrology recipe may generally describe various parameters of the SHG measurement system 100 being measured. In some embodiments, the metrology recipe includes various parameters associated with the illumination beam 104, such as, but not limited to, intensity, wavelength, polarization, spot size on the sample 108, or angle of incidence on the sample 108. In some embodiments, the metrology recipe includes various parameters associated with the collected SHG light 112, such as, but not limited to, polarization. In some embodiments, the metrology recipe includes various parameters associated with the detector 114, such as, but not limited to, gain settings. In some embodiments, the metrology recipe includes various parameters associated with the excitation source 126 to enhance the SHG process. For example, the metrology recipe may include various parameters associated with the additional illumination beam 128, such as, but not limited to, intensity, wavelength, polarization, spot size on the sample 108, or angle of incidence on the sample 108. As another example, the metrology recipe may include various parameters associated with the electric field 130 , such as, but not limited to, the field strength or angle relative to the sample 108 .

[0081] 10 is a flow diagram of a method 1000 depicting the generation of a metrology recipe to meet application-specific requirements, in accordance with one or more embodiments of the present disclosure. Applicant notes that the embodiments and enabling techniques described herein above in the context of SHG metrology system 100 should be construed as extending to method 1000. However, it is further noted that method 1000 is not limited by the architecture of SHG metrology system 100.

[0082] In some embodiments, the method 1000 includes generating 1002 calibration data (e.g., associated with a DOE) for multiple wavelengths (e.g., of the illumination beam 104). For example, a common sample 108 may be measured at different wavelengths, and the amplitude of the SHG light 112 may be measured each time. In some embodiments, the method 1000 includes selecting 1004 a wavelength. For example, a wavelength providing the highest or optimal amplitude (e.g., within an acceptable range) may be selected. In some embodiments, the method 1000 includes generating 1006 test measurement data at the selected wavelength. For example, the test measurement data may be generated for additional samples. In some embodiments, the method 1000 includes determining 1008 a process control range. For example, the process control range may be associated with a range of acceptable wavelengths to be used during runtime measurements. In some embodiments, the method 1000 includes testing 1010 the process control range on additional samples. For example, this may involve determining whether application-specific requirements (e.g., intensity of SHG light 112 and associated signal-to-noise ratio, or the like) are met using the process control range for the additional sample. In some embodiments, method 1000 includes step 1012 of checking whether the process control range is satisfactory. If the application-specific requirements are met, method 1000 includes step 1014 of saving the metrology recipe so that it can be used during runtime.

[0083] If the application-specific requirements are not met, various additional steps may be taken to provide a metrology recipe that includes an additional excitation source 126 to enhance the SHG light 112 to meet the application-specific requirements. In some embodiments, the method 1000 includes step 1016 of generating calibration data for one or more parameters of the additional illumination beam 128. Any suitable parameters may be considered, such as, but not limited to, the intensity, wavelength, or polarization of the additional illumination beam 128. In some embodiments, the method 1000 includes step 1018 of selecting one or more parameters of the additional illumination beam 128 based on the calibration data. For example, the parameter providing the highest or optimal amplitude (e.g., within an acceptable range) may be selected. In some embodiments, the method 1000 includes step 1020 of determining a process control range (e.g., for use during runtime measurements). In some embodiments, the method 1000 includes step 1022 of testing the process control range on one or more additional samples. In some embodiments, the method 1000 includes step 1024 of determining whether the process control range is satisfactory. If the application-specific requirements are met, the method 1000 includes saving 1026 the metrology recipe so that it can be used during runtime.

[0084] If the application-specific requirements are not met, various additional steps may be taken to provide a metrology recipe that includes a different excitation source 126 for enhancing the SHG light 112 to meet the application-specific requirements. In some embodiments, method 1000 includes step 1028 of generating calibration data for one or more parameters of the external electric field 130. Any suitable parameters may be considered, such as, but not limited to, the strength or direction of the electric field 130. In some embodiments, method 1000 includes step 1030 of selecting one or more parameters of the electric field 130 based on the calibration data. For example, the parameter providing the highest or optimal amplitude (e.g., within an acceptable range) may be selected. In some embodiments, method 1000 includes step 1032 of determining a process control range (e.g., for use during runtime measurements). If the application-specific requirements are met, method 1000 includes step 1034 of saving the metrology recipe so that it can be used during runtime.

[0085] The subject matter described herein sometimes illustrates different components contained within or connected to other components. It should be understood that any such depicted architectures are merely exemplary and that, in fact, many other architectures that achieve the same functionality may be implemented. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Thus, any two components herein that combine to achieve a particular functionality may be viewed as being “associated” with each other such that the desired functionality is achieved, regardless of the architecture or intermediate components. Similarly, any two components so associated may also be viewed as being “connected” or “coupled” to each other to achieve the desired functionality, and any two components that can be so associated may also be considered to be “couplable” to each other to achieve the desired functionality. Specific examples of being couplable include, but are not limited to, physically interactable and / or physically interacting components, and / or wirelessly interactable and / or wirelessly interacting components, and / or logically interactable and / or logically interacting components.

[0086] The present disclosure and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes can be made in the form, construction, and arrangement of elements without departing from the disclosed subject matter or sacrificing all of its physical advantages. The described forms are merely exemplary, and it is the intent of the following claims to embrace and include such modifications. It will be further understood that the invention is defined by the appended claims.

Claims

1. 1. A measurement system comprising: an illumination source for generating an illumination beam; an illumination subsystem including one or more optical elements configured to direct the illumination beam to a sample, the sample including an inversion-symmetric substrate and one or more films disposed on the inversion-symmetric substrate; a filter configured to block wavelengths of the illumination beam and pass wavelengths associated with a second harmonic of the illumination beam; a detector for capturing second harmonic generation (SHG) light associated with the second harmonic of the illumination beam; a controller communicatively coupled to the detector, the controller including one or more processors configured to execute program instructions, the program instructions causing the one or more processors to: receiving metrology data from the detector associated with the SHG light from an interface between the inversion-symmetric substrate and the one or more films; and generating one or more metrology measurements associated with the one or more films based on the metrology data; A controller and A measurement system comprising:

2. 2. The metrology system of claim 1, wherein the metrology measurements are: a metrology system including at least one of a layer thickness, a layer composition, a presence of defects, a charge / trap state, a stress / strain, a charge mobility, or a surface / interface roughness associated with at least one of the one or more films;

3. 10. The metrology system of claim 1, wherein the interface between the inversion-symmetric substrate and the one or more films is associated with a gate region of a field-effect transistor (FET).

4. 4. The measurement system according to claim 3, wherein the FET comprises:

1. A metrology system comprising at least one of a metal oxide semiconductor FET (MOSFET), a planar FET, a FinFET, a gate-all-around (GAA) nanosheet FET, a forked-sheet FET, a complementary GAA FET, a ferroelectric FET, or a 2D FET.

5. 4. The measurement system of claim 3, wherein the one or more membranes: A metrology system comprising at least one of a high-k layer or an interfacial dipole engineering layer.

6. 6. The measurement system of claim 5, wherein the one or more membranes: Si ３ N ４ , Al ２ O ３ , Ta ２ O ５ , TiO ２ , ZrO ２ , or HfO ２ A measurement system comprising at least one of the following:

7. 6. The measurement system according to claim 5, wherein the inversion symmetric substrate comprises: silicon A measurement system comprising:

8. 6. The metrology system of claim 5, wherein at least one of the one or more metrology measurements comprises: Threshold voltage (V ｔ ), or the threshold voltage (V ｔ ) a value indicative of the measurement system.

9. 6. The measurement system of claim 5, wherein the one or more processors are configured to: controlling one or more process tools for fabricating the at least one of the high-k layer or the interface dipole engineering layer based on the one or more metrology measurements. The metrology system further configured to execute program instructions.

10. 10. The measurement system of claim 1, wherein the one or more processors are configured to: controlling one or more process tools for manufacturing at least a portion of the specimen based on the one or more metrology measurements. The metrology system further configured to execute program instructions.

11. 10. The metrology system of claim 1, wherein the metrology data from the detector associated with the second harmonic of the illumination beam comprises: a measurement system including time-resolved measurements of the SHG light in response to illuminating the sample with the illumination beam, wherein at least one of the one or more metrology measurements is generated based on the time-resolved measurements of the SHG light.

12. 12. The measurement system of claim 11, wherein at least one of the one or more measurement values ​​is based on at least one of a saturation intensity of the SHG light, a slope of the intensity of the SHG light, or an intensity of the SHG light at a selected time.

13. 12. The metrology system of claim 11, wherein the time-resolved measurements are associated with intermittent illumination of the sample by the illumination beam.

14. 12. The metrology system of claim 11, wherein at least one of the one or more metrology measurements is based on the intensity of the SHG light associated with the intermittent illumination of the sample by the illumination beam.

15. 10. The metrology system of claim 1, wherein the wavelength of the illumination beam is tunable, and the metrology data from the detector associated with the second harmonic of the illumination beam is: a wavelength-resolved measurement of the SHG light in response to illuminating the sample with the illumination beam having two or more wavelengths, wherein at least one of the one or more metrology measurements is generated based on the wavelength-resolved measurement of the SHG light.

16. 16. The metrology system of claim 15, wherein at least one of the one or more metrology measurements comprises a depth-dependent measurement.

17. 10. The measurement system of claim 1, 10. The metrology system of claim 9, further comprising one or more excitation sources for directing at least one of an additional illumination beam or an electric field toward the sample to enhance the SHG light associated with the interface between the inversion-symmetric substrate and the one or more films.

18. 18. The metrology system of claim 17, wherein the metrology data from the detector associated with the second harmonic of the illumination beam comprises: a time-resolved measurement of the SHG light in response to illuminating the sample with at least one of the additional illumination beam or the electric field, wherein at least one of the one or more metrology measurements is generated based on the time-resolved measurement of the SHG light.

19. 20. The metrology system of claim 18, wherein the time-resolved measurements are associated with intermittent illumination of the sample with at least one of the additional illumination beam or the electric field while the illumination beam is constant.

20. 20. The metrology system of claim 18, wherein the time-resolved measurements are associated with intermittent illumination of the sample by the illumination beam and the at least one of the additional illumination beam or the electric field.

21. 10. The measurement system of claim 1, a first polarizer for controlling the polarization of the illumination beam incident on the sample; a second polarizer for controlling the polarization of light incident on the detector; The measurement system further comprises:

22. 22. The metrology system of claim 21, wherein an orientation of at least one of the first polarizer or the second polarizer is adjusted to maximize the intensity of the second harmonic of the illumination beam within a selected tolerance.

23. 2. The measurement system of claim 1, wherein the detector comprises: at least one of a photomultiplier tube, a charge-coupled device, or a photodiode A measurement system comprising:

24. 1. A measurement system comprising: a controller including one or more processors configured to execute program instructions, the program instructions causing the one or more processors to: receiving metrology data from a detector associated with second harmonic generation (SHG) light from a sample in response to an illumination beam, the sample including an inversion-symmetric substrate and one or more films disposed on the inversion-symmetric substrate; generating one or more metrology measurements associated with the one or more films based on the SHG light associated with an interface between the inversion-symmetric substrate and the one or more films; A measurement system characterized by performing the following.

25. 25. The metrology system of claim 24, wherein the metrology measurements are: a metrology system including at least one of a layer thickness, a layer composition, a presence of defects, a charge / trap state, a stress / strain, a charge mobility, or a surface / interface roughness associated with at least one of the one or more films;

26. 25. The metrology system of claim 24, wherein the interface between the inversion symmetric substrate and the one or more films is associated with a gate region of a field effect transistor (FET).

27. 27. The measurement system of claim 26, wherein the FET comprises:

1. A metrology system comprising at least one of a metal oxide semiconductor FET (MOSFET), a planar FET, a FinFET, a gate-all-around (GAA) nanosheet FET, a forked-sheet FET, a complementary GAA FET, a ferroelectric FET, or a 2D FET.

28. 27. The measurement system of claim 26, wherein the one or more membranes: At least one of a high-k layer or an interfacial dipole engineering layer A measurement system comprising:

29. 29. The measurement system of claim 28, wherein the one or more membranes: Si ３ N ４ , Al ２ O ３ , Ta ２ O ５ , TiO ２ , ZrO ２ , or HfO ２ At least one of A measurement system comprising:

30. 29. The metrology system of claim 28, wherein the inversion symmetric substrate comprises: silicon A measurement system comprising:

31. 29. The metrology system of claim 28, wherein at least one of the one or more metrology measurements comprises: Threshold voltage (V ｔ ), or the threshold voltage (V ｔ ) A measurement system comprising:

32. 30. The metrology system of claim 28, wherein the one or more processors are configured to: controlling one or more process tools for fabricating the at least one of the high-k layer or the interface dipole engineering layer based on the one or more metrology measurements. The metrology system further configured to execute program instructions.

33. 25. The metrology system of claim 24, wherein the one or more processors are configured to: controlling one or more process tools for manufacturing at least a portion of the specimen based on the one or more metrology measurements. The metrology system further configured to execute program instructions.

34. 25. The metrology system of claim 24, wherein the metrology data from the detector associated with the second harmonic of the illumination beam comprises: a measurement system including time-resolved measurements of the SHG light in response to illuminating the sample with the illumination beam, wherein at least one of the one or more metrology measurements is generated based on the time-resolved measurements of the SHG light.

35. 35. The measurement system of claim 34, wherein at least one of the one or more measurement values ​​is based on at least one of a saturation intensity of the SHG light, a slope of the intensity of the SHG light, or an intensity of the SHG light at a selected time.

36. 35. The metrology system of claim 34, wherein the time-resolved measurements are associated with intermittent illumination of the sample by the illumination beam.

37. 35. The metrology system of claim 34, wherein at least one of the one or more metrology measurements is based on the intensity of the SHG light associated with intermittent illumination of the sample by the illumination beam.

38. 25. The metrology system of claim 24, wherein the metrology data from the detector associated with the second harmonic of the illumination beam comprises: a wavelength-resolved measurement of the SHG light in response to illuminating the sample with the illumination beam having two or more wavelengths, wherein at least one of the one or more metrology measurements is generated based on the wavelength-resolved measurement of the SHG light.

39. 39. The metrology system of claim 38, wherein at least one of the one or more metrology measurements comprises a depth dependent measurement.

40. 25. The metrology system of claim 24, wherein the metrology data from the detector associated with the second harmonic of the illumination beam comprises: a time-resolved measurement of the SHG light in response to illuminating the sample with at least one of an additional illumination beam or an electric field, wherein at least one of the one or more metrology measurements is generated based on the time-resolved measurement of the SHG light.

41. 41. The metrology system of claim 40, wherein the time-resolved measurements are associated with intermittent illumination of the sample with at least one of the additional illumination beam or the electric field while the illumination beam is constant.

42. 41. The metrology system of claim 40, wherein the time-resolved measurements are associated with intermittent illumination of the sample by the illumination beam and the at least one of the additional illumination beam or the electric field.

43. A measurement method comprising: directing an illumination beam to a sample, the sample including an inversion symmetric substrate and one or more films disposed on the inversion symmetric substrate; capturing metrology data based on second harmonic generation (SHG) light from the sample associated with an interface between the inversion-symmetric substrate and the one or more films; generating one or more metrology measurements associated with the one or more films based on the metrology data; A measuring method comprising:

44. 44. The metrology method of claim 43, wherein generating one or more metrology measurements associated with the one or more films based on the SHG light associated with an interface between the inversion-symmetric substrate and the one or more films comprises: generating metrology measurements associated with at least one of the one or more films of at least one of layer thickness, layer composition, presence of defects, charge / trap states, stress / strain, charge mobility, or surface / interface roughness.

45. 44. The metrology method of claim 43, wherein the interface between the inversion-symmetric substrate and the one or more films is associated with a gate region of at least one of a field-effect transistor (FET), a metal-oxide-semiconductor FET (MOSFET), a planar FET, a FinFET, a GAA nanosheet FET, a fork-sheet FET, a complementary GAA FET, a ferroelectric FET, or a 2D FET.

46. 46. ​​The metrology method of claim 45, wherein generating one or more metrology measurements associated with the one or more films based on the SHG light associated with an interface between the inversion-symmetric substrate and the one or more films comprises: Threshold voltage (V ｔ ) to generate metrology measurements A measuring method comprising:

47. 46. ​​The method of claim 45, wherein the one or more membranes are: At least one of a high-k layer or an interfacial dipole engineering layer A measuring method comprising:

48. 46. ​​The measurement method according to claim 45, controlling one or more process tools for fabricating the at least one of the high-k layer or the interface dipole engineering layer based on the one or more metrology measurements. The measurement method further comprises:

49. 44. The measurement method according to claim 43, controlling one or more process tools for manufacturing at least a portion of the specimen based on the one or more metrology measurements. The measurement method further comprises:

50. 44. The metrology method of claim 43, wherein generating one or more metrology measurements associated with the one or more films based on the SHG light associated with the interface between the inversion-symmetric substrate and the one or more films comprises: generating calibration metrology data based on the SHG light associated with known variations of the interface between the inversion-symmetric substrate and the one or more films; generating one or more metrology measurements for the sample associated with the one or more films based on the SHG light from the sample and the calibration metrology data; A measuring method comprising:

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