Stack detection method and stack detection system

Abstract

A layer detection method and a layer detection system are provided that enable non-contact and non-destructive detection of non-transparent solid materials. [Solution] The stack detection method includes step 134 of generating terahertz emitting electromagnetic waves and emitting the terahertz emitting electromagnetic waves into a solid material at an arbitrary angle; step 136 of detecting a plurality of reflected or transmitted terahertz receiving electromagnetic waves after the terahertz emitting electromagnetic waves are incident on the solid material and pass through the entire thickness of the solid material in a first direction; step 138 of measuring and analyzing a plurality of characteristic signals based on the terahertz emitting electromagnetic waves and the plurality of terahertz receiving electromagnetic waves to divide the solid material into a plurality of parallel layers along the first direction and determine a plurality of characteristics of the plurality of layers; and step 140 of determining at least one defect information of each of the plurality of layers based on the plurality of characteristics of the plurality of layers.

Description

[Technical Field]

[0001] The present invention relates to a stacking detection method and a stacking detection system, and more specifically, to a stacking detection method and a stacking detection system that enable non-contact, non-destructive detection of opaque solid materials. [Background technology]

[0002] Semiconductor wafers, ceramics, and polymer materials are primarily insulators or semiconductors and are widely used in various fields, including electronics, architecture, aerospace, chemical, and medical industries. The physical properties of these solid materials, such as mechanical, thermal, and optoelectronic properties, are all indicators of whether a material is suitable for use, and the quality of the finished product after the material has been processed is also primarily determined by these physical properties. During the acceptance inspection of raw materials, or the functional verification of semi-finished and finished products, several key parameters are typically selected as pass or fail criteria.

[0003] The general mechanical properties of a material include Vickers hardness, fracture toughness, flexural strength, and modulus of elasticity. Thermal properties include the coefficient of thermal expansion, thermal conductivity, and specific heat capacity. Optoelectronic properties include the refractive index, dielectric constant, and conductivity, which represent these parameters. Furthermore, the thickness, warpage, and surface roughness of a solid material are also important reference properties. However, conventional methods for measuring the above parameters require applying force, high temperature, voltage, etc., to the sample surface, or bending and deforming the sample, all of which involve contact with the sample and cause some degree of damage.

[0004] On the other hand, the presence of defects within the material is also an evaluation metric. Common internal defects include crystal defects, microcracks, porosity, and residual stress. Traditional inspection methods typically use techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), but these are not only expensive and time-consuming, but in most cases they can only detect the sample surface and cannot detect multiple parameters simultaneously.

[0005] While existing techniques such as optical coherence tomography (OCT), total internal reflection fluorescence microscopy (TIRFM), and scanning acoustic microscopy (SAM) are mature for detecting defects beneath the surface of samples, they have significant limitations on the materials being inspected. For example, they cannot inspect low-light-scattering or opaque materials, or even if they can, the resolution is insufficient.

[0006] Therefore, it is necessary to improve the conventional technology. [Overview of the project]

[0007] Therefore, the present invention aims to provide a stacking detection method and a stacking detection system that enable non-destructive detection of opaque solid materials.

[0008] One embodiment of the present invention discloses a layered detection method, the layered detection method comprising: generating terahertz emitted electromagnetic waves and emitting the terahertz emitted electromagnetic waves onto a solid material at an arbitrary angle; detecting a plurality of terahertz received electromagnetic waves that have been reflected or transmitted after the terahertz emitted electromagnetic waves have been incident on the solid material and passed through the entire thickness of the solid material in a first direction; measuring and analyzing a plurality of characteristic signals based on the terahertz emitted electromagnetic waves and the plurality of terahertz received electromagnetic waves to divide the solid material into a plurality of parallel layers along the first direction and to determine a plurality of characteristics of the plurality of layers; and determining at least one defect information for each of the plurality of layers based on the plurality of characteristics of the plurality of layers.

[0009] Another embodiment of the present invention discloses a stacking detection system comprising: a terahertz electromagnetic wave generator configured to generate terahertz emitted electromagnetic waves and emit the terahertz emitted electromagnetic waves onto a solid material at an arbitrary angle; a terahertz electromagnetic wave receiver configured to detect a plurality of terahertz received electromagnetic waves that are reflected or transmitted after the terahertz emitted electromagnetic waves have entered the solid material and passed through the entire thickness of the solid material in a first direction; and a detection device coupled to the terahertz electromagnetic wave generator and the terahertz electromagnetic wave receiver, configured to measure and analyze a plurality of characteristic signals based on the terahertz emitted electromagnetic waves and the plurality of terahertz received electromagnetic waves to divide the solid material into a plurality of parallel layers along the first direction, to determine a plurality of characteristics of the plurality of layers, and to determine at least one defect information for each of the plurality of layers based on the plurality of characteristics of the plurality of layers.

[0010] These and other objects of the present invention will become undoubtedly apparent to those skilled in the art after reading the following detailed description of preferred embodiments shown in various figures and drawings. [Brief explanation of the drawing]

[0011] [Figure 1] This is a functional block diagram of a stacking detection system according to one embodiment of the present invention. [Figure 2] This is a schematic diagram illustrating reflection and refraction when electromagnetic waves propagate through a medium. [Figure 3] This is a schematic diagram of a stacking detection system according to one embodiment of the present invention. [Figure 4A] Figure 3 is a schematic diagram of the time-domain optical spectrum detected by the stacked detection system shown. [Figure 4B] Figure 3 is a schematic diagram of the frequency-domain optical spectrum detected by the stacked detection system shown. [Figure 5] This is a schematic diagram of a stacking detection system according to one embodiment of the present invention. [Figure 6A] Figure 5 is a schematic diagram of the time-domain optical spectrum detected by the stacked detection system shown. [Figure 6B] It is a schematic diagram of the frequency-domain optical spectrum detected by the stacking detection system shown in FIG. 5. [Figure 7] It is a schematic diagram of the scanning result of the entire sample. [Figure 8] It is a schematic diagram of a wafer. [Figure 9A] It is a schematic diagram of the refractive index distribution diagram obtained without performing the stacking calculation of the wafer shown in FIG. 8. [Figure 9B] It is a schematic diagram of the refractive index distribution diagram obtained by the stacking detection system shown in FIG. 3. [Figure 10] It is a schematic diagram of the wafer stacking structure according to an embodiment of the present invention. [Figure 11A] It is a refractive index distribution diagram of the first wafer. [Figure 11B] It is a refractive index distribution diagram of the first wafer. [Figure 11C] It is a refractive index distribution diagram of the first wafer. [Figure 12A] It is a refractive index distribution diagram of the second wafer. [Figure 12B] It is a refractive index distribution diagram of the second wafer. [Figure 12C] It is a refractive index distribution diagram of the second wafer. [Figure 13] It is a schematic diagram of the stacking detection process according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0012] Certain terms are used throughout the specification and the claims below to refer to specific components. As those skilled in the art will understand, hardware manufacturers may refer to components by different names. This document is not intended to distinguish between components that have different names but the same function. In the specification and claims below, the terms “include” and “comprise” are used in open-ended form and should be interpreted as “including, but not limited to…”. The term “combined” is intended to mean indirect or direct electrical connection. Thus, when one device is combined with another, the connection may be via a direct electrical connection or via an indirect electrical connection through other devices and connections.

[0013] Semiconductor wafers, ceramics, and polymers undergo multiple processes during their manufacturing. High-temperature processes (such as sintering and annealing) and mechanical / physical processes (such as grinding, polishing, crushing, and compression) all potentially introduce defects within the material. Appropriate inspection methods must be implemented during production and manufacturing processes to ensure that the physical properties of these materials meet requirements. However, most non-destructive testing methods can only detect the surface, and most methods for detecting the interior of a material require the destruction of the sample. Therefore, one of the industry's goals is to effectively analyze whether there are anomalies inside a material in a non-contact and non-destructive manner. In this context, the present invention achieves non-contact and non-destructive detection using terahertz electromagnetic waves. Terahertz electromagnetic waves are 10 11 Hz~10 13It operates in a frequency range of Hz (0.1 THz to 10 THz), thereby enabling the transmission of non-conductive materials and the measurement of highly water-containing materials. The advantage of terahertz detection is that it has good penetration for many materials and can be used to detect optical coefficients, electrical properties, layer thickness, or structural defects of various materials and structures inside a test specimen. Terahertz detection can also be used for technical inspection in processes, and inspection of semi-finished or finished products. When detecting a test specimen using terahertz electromagnetic waves, the frequency of the terahertz electromagnetic waves is the same as the frequency of infrared waves (10 THz). 13 Hz~10 15 Because the energy is much lower than that of terahertz electromagnetic waves, the photons carried by terahertz electromagnetic waves have lower energy, so the molecular structure is not destroyed, thereby maintaining structural integrity, preventing further damage or defects, and significantly reducing the probability of failure in destructive testing of the finished product.

[0014] Specifically, please refer to Figure 1, a functional block diagram of a stacking detection system 1 according to one embodiment of the present invention. The stacking detection system 1 includes a terahertz electromagnetic wave generator 10, a terahertz electromagnetic wave receiver 12, and a detection device 14 capable of detecting the internal structure of a solid material. More specifically, the stacking detection system 1 can perform stacking detection within a solid material, and the solid material may be one or more selected from semiconductor wafers, ceramic materials, and polymer materials. The semiconductor wafer may be at least one of silicon wafers (Si), germanium wafers (Ge), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), cadmium sulfide (CdS), indium phosphide (InP), zinc oxide (ZnO), gallium oxide (Ga2O3), and aluminum nitride (AlN). The terahertz electromagnetic wave generator 10 is used to generate terahertz emitted electromagnetic waves, which are incident on the solid material at any angle. The terahertz electromagnetic wave receiver 12 is used to detect multiple terahertz received electromagnetic waves that have been reflected or transmitted after terahertz emitted electromagnetic waves have been incident on a solid material and passed through the entire thickness of the solid material in a first direction. The detection device 14 is coupled to the terahertz electromagnetic wave generator 10 and the terahertz electromagnetic wave receiver 12 and is used to measure and analyze multiple characteristic signals based on the terahertz emitted electromagnetic waves and the multiple terahertz received electromagnetic waves to divide the solid material into multiple parallel layers along the first direction and determine multiple characteristics of the multiple layers, thereby determining at least one defect information for each of the multiple layers. The first direction is the normal direction of the interface between the multiple layers.

[0015] In short, the detection device 14 can determine the internal defect conditions of the solid material, such as material heterogeneity, bubbles or porosity, uneven mixing of multiple materials, residual stress, crystal dislocations, and uneven doping concentrations, by dividing the solid material into multiple layers and analyzing the properties of each layer. The relevant principle is explained as follows.

[0016] Please refer to Figure 2, which is a schematic diagram of reflection and refraction when electromagnetic waves propagate through a medium. As shown in Figure 2, the incident electromagnetic wave I has a complex refractive index.

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[0017] Define the ratio of the incident electromagnetic wave I reflected by the interface of the medium as the reflectance R, and the ratio of the refracted electromagnetic wave as the transmittance T. The relationship between the two is expressed by T = 1 - R (Equation 2).

[0018] The specific forms of the reflectance and transmittance are also related to the polarization of the incident electromagnetic wave I. When the electric field component of the polarized incident electromagnetic wave I is perpendicular to the plane formed by the incident electromagnetic wave I and the reflected electromagnetic wave Q, the state of the incident electromagnetic wave I is called the "s-polarized state". Conversely, when the electric field component of the polarized incident electromagnetic wave I is parallel to the plane formed by the incident electromagnetic wave I and the reflected electromagnetic wave Q, the state of the incident electromagnetic wave I is called the "p-polarized state". Based on Fresnel's formula, for the case of the s-polarized incident electromagnetic wave I, the reflectance is as follows.[[ID=--]] [[ID=--]]

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[0019] The detection device 14 can determine defect information for each layer by dividing the interior of a solid material into multiple layers based on the above formula and determining the characteristics of each layer. The detection device 14 is not limited to a specific technique for determining the characteristics of each layer. For example, the applicant provides a composite structure detection method and a composite structure detection system in U.S. Patent Application No. 18 / 813045, and this method and system may be appropriately modified and applied to the present invention. For example, in one embodiment, the detection device 14 can compare the signal of terahertz emitted electromagnetic waves for detecting air with the signal of terahertz emitted electromagnetic waves for detecting a solid material, analyze the time-domain optical spectrum and frequency-domain optical spectrum to measure characteristic signals, and further analyze the refractive index, dielectric constant, conductivity, doping concentration, etc., of each layer of the solid material, and can also analyze the structure and defects of each layer inside the solid material, or provide a basis for determining defects. Defects may be, for example, material heterogeneity (e.g., bubbles, heterogeneous mixing of multiple materials), lattice dislocations, heterogeneous doping concentrations, etc. Specifically, the detection device 14 measures the transient electric field of each terahertz received electromagnetic wave in the time domain to obtain the electric field strength, electric field phase, and electric field frequency of the transient (time domain) electric field, and applies a transformation (e.g., Fourier transform) to obtain the spectral electric field between the terahertz received electromagnetic waves to obtain the electric field amplitude, electric field polarization, and electric field phase of the spectral electric field. That is, the characteristic signal measured by the detection device 14 may include the transient electric field strength and phase of each terahertz received electromagnetic wave in the time domain, as well as the spectral electric field amplitude, polarization, and phase between the terahertz received electromagnetic waves in the frequency domain. Since the characteristic signal (transient electric field strength and phase, and spectral electric field amplitude, polarization, and phase) is highly sensitive to material properties, the optical coefficients (absorptivity, refractive index, reflectivity, transmittance, etc.), electrical coefficients (conductivity, resistivity, doping concentration, dielectric constant, charge carrier mobility, etc.) and structural properties of the material can be directly measured by calculating physical formulas. On the other hand, the detection device 14 can measure the flight time of multiple terahertz received electromagnetic waves and analyze the flight time to determine the thickness of each layer inside the solid material.Thus, the detection device 14 can analyze whether there are abnormalities in the interlayer structure, abnormalities in the position of components, whether the thickness is as designed, changes in stress, etc., based on the time-domain time-of-flight spectral signal, and can also be used to determine whether the process technology is wrong or whether the components are defective.

[0020] Therefore, the detection device 14 can measure multiple characteristic signals relating to a solid material by comparing the signal of terahertz-emitting electromagnetic waves that detects air (or a metal plate, a highly conductive material, etc.) with the signal that detects the solid material, thereby determining the characteristics of multiple layers of the solid material. The characteristic signals may include the electric field strength and electric field phase of the time-domain electric field of each terahertz-received electromagnetic wave, and / or the electric field amplitude and electric field phase of the spectral electric field between the terahertz-received electromagnetic waves. The characteristics of each layer may include at least one of the thickness of each layer, optical coefficients, electrical coefficients, structural state, resistance, and stress changes. The electrical coefficients may be at least one of conductivity, resistivity, doping concentration, dielectric constant, and charge carrier mobility, and the optical coefficients may be at least one of absorptivity, refractive index, reflectivity, and transmittance. Therefore, the detection device 14 can further determine whether the solid material contains defects or provide evidence for confirming defects.

[0021] Formulas 1 to 4 above form the basis for the stacking operation of the detection device 14 in the stacking detection system 1. The operation method for performing detection after the detection device 14 has completed the stacking operation is not limited to the composite structure detection method and composite structure detection system disclosed in the aforementioned U.S. Patent Application No. 18 / 813045. It may be any method or system for detection using electromagnetic waves. For example, the applicant provides a semiconductor wafer detection method and semiconductor wafer detection apparatus in Taiwan Patent No. I788105, which uses terahertz electromagnetic waves to detect the characteristics of multiple interface layers of a semiconductor wafer and may be appropriately adjusted and applied to the present invention.

[0022] Furthermore, the stacked detection system 1 shown in Figure 1 is represented by functional blocks which are essential components for carrying out the present invention. However, when implementing the stacked detection system 1, those skilled in the art can design or select an appropriate architecture based on actual requirements. For example, Figure 3 is a schematic diagram of a stacked detection system 3 according to one embodiment of the present invention. The stacked detection system 3 is derived from the stacked detection system 1 and uses a through-type terahertz electromagnetic wave detection architecture. For simplicity, Figure 3 omits the specific location of the detection device 14, which those skilled in the art can infer from Figure 1. In detail, the stacked detection system 3 uses a terahertz electromagnetic wave generator 30 to generate terahertz emitted electromagnetic waves I, which are incident on a test specimen TS (e.g., a solid material). A terahertz electromagnetic wave receiver 32 detects a plurality of terahertz received electromagnetic waves R that have been transmitted through the test specimen TS after the terahertz emitted electromagnetic waves I have been incident on the test specimen TS. Furthermore, the term "layered structure" in the test specimen TS does not indicate that the test specimen TS itself has a layered structure, but rather is used to represent the relationship between the results of the layered calculation performed by the detection device 14 and the terahertz emitted electromagnetic wave I or the terahertz received electromagnetic wave R.

[0023] The stacked detection system 3 utilizes a transmissive terahertz electromagnetic wave detection architecture. This electromagnetic wave detection architecture compares the signal of terahertz emitted electromagnetic waves used to detect air with the signal of terahertz emitted electromagnetic waves used to detect solid materials, analyzes the time-domain and frequency-domain optical spectra, and measures characteristic signals. For example, refer to Figures 4A and 4B, which are schematic diagrams of the time-domain and frequency-domain optical spectra detected by the stacked detection system 3, respectively. In Figure 4A, the solid line represents the result of the electric field against the optical delay (time-domain optical spectrum) of the terahertz emitted electromagnetic wave used to detect air (without setting the solid material to be inspected), and the dotted line represents the result of the electric field against the optical delay (time-domain optical spectrum) of the terahertz emitted electromagnetic wave used to detect solid materials. In Figure 4B, the solid line represents the result of the electric field against the frequency spectrum (frequency-domain optical spectrum) of the terahertz emitted electromagnetic wave used to detect air (without setting the solid material to be inspected), and the dotted line represents the result of the electric field against the frequency spectrum (frequency-domain optical spectrum) of the terahertz emitted electromagnetic wave used to detect solid materials. Therefore, the detection device 14 with a transmission-type detection architecture can measure characteristic signals by analyzing time-domain and frequency-domain optical spectra, and can also analyze and obtain the refractive index, dielectric constant, conductivity, doping concentration, etc., of each layer of the solid material, and can analyze the internal structure of the solid material and the presence or absence of defects, and provide a basis for determining defects. Defects may be, for example, material heterogeneity (e.g., bubbles, heterogeneous mixing of multiple materials), lattice dislocations, or heterogeneous doping concentrations.

[0024] Furthermore, the stacked detection system 3 has a transmission architecture, meaning that the terahertz electromagnetic waves received by the terahertz electromagnetic wave receiver 32 are the transmission result after the incident electromagnetic wave I has passed through the entire thickness of the solid material. Therefore, the detection device 14 defines a specific depth within the solid material as an interface, and determines the angle θ between the electric field strength of the incident electromagnetic wave I and the refracted electromagnetic wave F corresponding to this interface and the normal to the point of incidence. i , θ tIt is possible to obtain the complex refractive index of the medium (layer) on both sides of this interface (i.e., by equations 1 to 4 (or their derivations)

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[0025] On the other hand, please refer to Figure 5, which is a schematic diagram of a stacked detection system 5 according to one embodiment of the present invention. The stacked detection system 5 is derived from the stacked detection system 1 and uses a reflective terahertz electromagnetic wave detection architecture. For simplicity, Figure 5 omits the specific location of the detection device 14, which a person skilled in the art could infer from Figure 1. Specifically, the stacked detection system 5 uses a reflective detection structure, and in this reflective detection structure, the terahertz electromagnetic wave generator / receiver 50 integrates the functions of emitting and receiving terahertz electromagnetic waves. That is, the terahertz electromagnetic wave generator / receiver 50 generates terahertz emitted electromagnetic waves I, emits the terahertz emitted electromagnetic waves I onto a test piece TS (such as a solid material), and can detect multiple terahertz received electromagnetic waves R that are reflected by the test piece TS after the terahertz emitted electromagnetic waves I have entered the test piece TS. Furthermore, the operation method of the stacked detection system 5 can be referred to in the aforementioned operation methods of stacked detection systems 1 and 3.

[0026] Furthermore, please refer to Figures 6A and 6B, which are schematic diagrams of the time-domain and frequency-domain optical spectra detected by the stacked detection system 5, respectively. In Figure 6A, the solid line represents the result of the electric field against the optical delay (time-domain optical spectrum) of the terahertz emitted electromagnetic wave used to detect a metal plate or highly conductive material, and the dotted line represents the result of the electric field against the optical delay (time-domain optical spectrum) of the terahertz emitted electromagnetic wave used to detect a solid material. In Figure 6B, the solid line represents the result of the electric field against the frequency spectrum (frequency-domain optical spectrum) of the terahertz emitted electromagnetic wave used to detect a metal plate or highly conductive material, and the dotted line represents the result of the electric field against the frequency spectrum (frequency-domain optical spectrum) of the terahertz emitted electromagnetic wave used to detect a solid material. Therefore, the detection device 14 with a reflective detection architecture can measure characteristic signals by analyzing the time-domain optical spectrum and frequency-domain optical spectrum, and can also analyze and obtain the refractive index, dielectric constant, conductivity, doping concentration, etc., of each layer of the solid material, and can analyze the internal structure and presence or absence of defects of the solid material, or provide evidence for confirming defects. Defects may include, for example, material heterogeneity (e.g., air bubbles, uneven mixing of multiple materials), lattice dislocations, or uneven doping concentrations.

[0027] Furthermore, the stacked detection system 5 has a reflective architecture, meaning that the terahertz electromagnetic waves received by the terahertz electromagnetic wave generator receiver 50 are the result of reflection after the incident electromagnetic wave I has passed through the entire thickness of the solid material. Therefore, the detection device 14 defines a specific depth within the solid material as an interface, and determines the angle θ between the electric field strength of the incident electromagnetic wave I and the reflected electromagnetic wave Q corresponding to this interface and the normal to the point of incidence. i , θ r It is possible to obtain the complex refractive index of the medium (layer) on both sides of this interface (i.e., by equations 1 to 4 (or their derivations)

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[0028] Furthermore, the stacked detection systems 3 and 5 use transmissive and reflective terahertz electromagnetic wave detection architectures derived from stacked detection system 1. Those skilled in the art should, however, select an appropriate structure based on their actual needs or inspection items, without being limited thereto. Generally speaking, transmissive terahertz electromagnetic wave detection architectures can directly penetrate solid materials to obtain information on overall phase differences and signal intensity differences, while reflective terahertz electromagnetic wave detection architectures can reflect signals as they pass through the interfaces between layers, thus returning one or more terahertz waves. Based on these signals, the structural surface distribution and thickness changes of each layer, as well as material parameters such as refractive index, dielectric constant, conductivity, doping concentration, and stress, can be analyzed.

[0029] Figures 4A, 4B, 6A, and 6B show the results of single-point detection of solid materials by stacking detection systems 3 and 5. Next, application scenarios for stacking detection will be described.

[0030] As described above, embodiments of the present invention are applicable to the detection of various solid materials. For example, in one embodiment, the solid material may be a bare wafer. Generally, semiconductor wafers are called bare wafers / substrates before undergoing integrated circuit-related processes. Bare wafers undergo various manufacturing processes from the raw material stage, such as crystal growth, slicing, grinding, etching, annealing, and polishing, to become quality-assured bare wafers, which are then processed into semiconductor wafers or products. When embodiments of the present invention (such as stacked detection systems 1, 3, and 5) are applied to the detection of a bare wafer, single-point detection can be performed on the bare wafer, and results similar to those shown in Figures 4A, 4B, 6A, and 6B can be obtained. Furthermore, embodiments of the present invention can also detect the entire sample in scanning mode by moving the detector or sample stage, and obtain scanning results as shown in Figure 7. Based on these results, the signals in each region of the sample can be observed to determine whether the thickness is correct, the distribution of surface warpage, internal non-uniformity, or other structural defects. However, in some applications, even if overall detection of thermal conductivity, bending strength, thickness, etc. is performed on the wafer, it may not be possible to observe differences within the wafer. In this case, the stacking detection systems 1, 3, and 5 of the present invention can perform stacking calculations on solid materials based on the Fresnel equation and its derivation algorithm, and further obtain various physical parameters for each layer. That is, the method of stacking solid materials of the present invention is not limited by the actual structure of the solid material, but can be stacked according to the number of layers, the thickness of each layer, etc., and different stacking calculations can be performed on the same solid material in different detection procedures. For example, in the detection procedure, embodiments of the present invention can perform full-thickness detection without performing stacking calculations on the wafer. If the detection result at this time does not reflect the differences in the internal structure of the wafer, embodiments of the present invention can start another detection procedure to perform stacking calculations on the same wafer, for example, by dividing the wafer into two layers and detecting the characteristics of these two layers. If the detection result at this time is still insufficient to reflect the differences in the internal structure of the wafer, the detection procedure can be performed again and the wafer can be divided into more layers for calculation.Furthermore, when performing layered calculations, the thickness of each layer can be arbitrarily specified according to different analytical purposes and is not limited to any specific rules.

[0031] Embodiments of the present invention allow for a more accurate determination of the internal structure of a wafer by layering its interior, and therefore, the condition of defects within the wafer. For example, refer to Figure 8, which is a schematic diagram of wafer 80. In one embodiment, to detect the structure of wafer 80, an operator uses the stacking detection system 3 shown in Figure 3, i.e., a transmissive terahertz electromagnetic wave detection architecture, to detect the wafer 80 and obtain a refractive index distribution diagram of the entire thickness of wafer 80 as shown in Figure 9A. That is, Figure 9A is a refractive index distribution diagram obtained without performing a stacking calculation on wafer 80, and based on this, it is not possible to determine whether there is local non-uniformity in wafer 80. Next, in order to more accurately detect the structure of wafer 80, the operator performs a stacking calculation on wafer 80 using the stacking detection system 3, for example, dividing / splitting wafer 80 into layers L1 and L2, setting the thickness of layer L1 to 10 μm, and using the stacking detection system 3, obtain a refractive index distribution diagram of the interface between layer L1 and layer L2 (10 μm below the surface) as shown in Figure 9B. As can be seen from Figure 9B, there is clear distribution non-uniformity between the upper and lower halves of wafer 80.

[0032] Comparing Figure 9A and Figure 9B, it can be seen that while an overall analysis of wafer 80 (i.e., an unlayered analysis) cannot determine whether wafer 80 has localized non-uniformity, the refractive index distribution diagram 10 μm below the surface clearly shows that wafer 80 has distributed non-uniformity. Therefore, the stacking calculation and subsequent stacking characteristic detection of the present invention can clearly reflect the internal structure and the presence or absence of defects, and can provide a basis for determining defects.

[0033] The items for detecting the stacking characteristics of the present invention can be adjusted as appropriate according to system requirements. For example, please refer to Figure 10, which is a schematic diagram of the wafer stacking structure 100. In one embodiment, in order to detect the structure of the first wafer and the second wafer, the operator uses the stacking detection system 5 shown in Figure 5, i.e., a reflective terahertz electromagnetic wave detection architecture, to divide the first wafer and the second wafer into layers L1 to L3, respectively, according to the wafer stacking structure 100. The thickness of layer L1 is 2 μm, and the thickness of layer L2 is 8 μm, that is, the total thickness of layers L1 and L2 is 10 μm. After stacking, the stacking detection system 5 detects the first wafer and the second wafer separately and obtains inspection results as shown in Figures 11A to 11C and Figures 12A to 12C. Figure 11A is the refractive index distribution diagram for the entire thickness of the first wafer, Figure 11B is the refractive index distribution diagram for the interface between layers L2 and L3 of the first wafer (10 μm below the surface), Figure 11C is the refractive index distribution diagram for the interface between layers L1 and L2 of the first wafer (2 μm below the surface), Figure 12A is the refractive index distribution diagram for the entire thickness of the second wafer, Figure 12B is the refractive index distribution diagram for the interface between layers L2 and L3 of the second wafer (10 μm below the surface), and Figure 12C is the refractive index distribution diagram for the interface between layers L1 and L2 of the second wafer (2 μm below the surface).

[0034] As can be seen from Figures 11A-11C and 12A-12C, the refractive index distribution diagrams of the first and second wafers are both very uniform, making it difficult to distinguish between the two wafers. In this case, the present invention can further calculate the standard deviation of the refractive index of the entire wafers of the first and second wafers. For example, the standard deviation of the refractive index in Figure 11A is 0.007, and the standard deviation of the refractive index in Figure 12A is 0.006, and these are not significantly different. The standard deviation of the refractive index in Figure 11B is 0.026, and the standard deviation of the refractive index in Figure 12B is 0.027, and these are slightly different. The standard deviation of the refractive index in Figure 11C is 0.19, and the standard deviation of the refractive index in Figure 12C is 0.09. Since the former is 2.1 times that of the latter, it can be inferred that the first wafer has many defects and that the refractive index distribution is highly non-uniform in the shallow layers.

[0035] Therefore, embodiments of the present invention can accurately analyze or compare the internal structure of solid materials through stacking detection, determine the presence or absence of defects, or provide a basis for determining defects.

[0036] The operation methods of the above-described stacking detection systems 1, 3, and 5 can be combined into a stacking detection process 130, as shown in Figure 13. The stacking detection process 130 is used to detect solid materials and includes the following steps.

[0037] Step 132: Start

[0038] Step 134: Generate terahertz-emitting electromagnetic waves and direct them onto a solid material.

[0039] Step 136: After the terahertz emitted electromagnetic wave is incident on the solid material and passes through the entire thickness of the solid material in a first direction, multiple terahertz received electromagnetic waves that have been reflected or transmitted are detected.

[0040] Step 138: Based on terahertz emitted electromagnetic waves and multiple terahertz received electromagnetic waves, multiple characteristic signals are measured and analyzed to divide the solid material into multiple parallel layers along a first direction and determine multiple characteristics of the multiple layers.

[0041] Step 140: Based on multiple characteristics of multiple layers, determine at least one defect in each of the multiple layers.

[0042] Step 142: Finish.

[0043] For a detailed explanation of the operation and deformation of the stacking detection process 130, please refer to the above explanation.

[0044] Conventional techniques cannot inspect the completed structure using visible light microscopy if the material is not transparent to visible light. This completed structure may have defects such as differences in the thickness of the deposited layers, residual internal defects, misalignment coverage errors, and differences in material doping concentrations. Even if the completed structure can undergo some tests, the resolution may be insufficient. In contrast, the present invention measures multiple characteristic signals based on terahertz emitted electromagnetic waves and multiple terahertz received electromagnetic waves, analyzes these multiple characteristic signals to separate the solid material into multiple layers, and determines multiple characteristics of each layer based on the multiple characteristic signals. Since terahertz electromagnetic waves penetrate many materials, they can be used to detect optical coefficients, electrical properties, layer thickness, or structural defects of different materials and structures within a substrate, and can be used for process technology inspection, inspection of semi-finished or finished products. More importantly, the present invention can accurately analyze or compare the internal structure of solid materials through layered detection, determine the presence or absence of defects, or provide a basis for judging defects. Therefore, the present invention can achieve non-contact, non-destructive detection of opaque solid materials and improve detection resolution through layered detection.

[0045] Those skilled in the art will readily recognize that many modifications and changes can be made to the apparatus and method while maintaining the teachings of the present invention. Accordingly, the above disclosure should be construed as being limited only by the boundaries and scope of the appended claims.

Claims

1. The steps include generating terahertz-emitting electromagnetic waves and emitting the terahertz-emitting electromagnetic waves onto a solid material at an arbitrary angle, The steps include detecting a plurality of terahertz received electromagnetic waves that have been reflected or transmitted after the terahertz emitted electromagnetic waves have been incident on the solid material and passed through the entire thickness of the solid material in a first direction, The steps include: measuring and analyzing multiple characteristic signals based on the terahertz emitted electromagnetic wave and the multiple terahertz received electromagnetic waves, and performing calculations on multiple characteristic signals based on the Fresnel equation, Snell's law, and reflectance and transmittance derived from the complex refractive index, thereby actively dividing the solid material into multiple parallel layers along the first direction and determining multiple characteristics of the multiple layers; A stacking detection method comprising the step of determining at least one defect information for each of the plurality of layers based on the plurality of characteristics of the plurality of layers.

2. The frequency of the aforementioned terahertz emitted electromagnetic wave is 10 １１ Hz to 10 １３ The stacking detection method according to claim 1, wherein the frequency is Hz.

3. The stacked detection method according to claim 1, wherein the plurality of characteristic signals include the electric field strength, electric field frequency, and electric field phase of each of the plurality of terahertz received electromagnetic waves.

4. The stacked detection method according to claim 3, wherein the plurality of characteristic signals further include at least one spectral electric field between the plurality of terahertz received electromagnetic waves, each spectral electric field includes electric field amplitude, electric field phase, and electric field polarization.

5. The stacking detection method according to claim 1, wherein the plurality of characteristics include at least one of the electrical coefficients and optical coefficients of each of the plurality of layers.

6. The stacked detection method according to claim 5, wherein the electrical coefficient is at least one of conductivity, resistivity, doping concentration, dielectric constant, and charge carrier mobility, and the optical coefficient is at least one of absorptivity, refractive index, reflectivity, and transmittance.

7. The stacking detection method according to claim 1, wherein the solid material is one or more selected from semiconductor wafers, ceramic materials, and polymer materials.

8. The semiconductor wafers include silicon wafers (Si), germanium wafers (Ge), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), cadmium sulfide (CdS), indium phosphide (InP), zinc oxide (ZnO), and gallium oxide (Ga ２ O ３ The stacking detection method according to claim 7, wherein the stacking detection method is at least one of the following: ), and aluminum nitride (AlN).

9. The stacking detection method according to claim 1, wherein at least one of the defect information is at least one of the following: material non-uniformity, bubbles or porosity, non-uniform mixing of a plurality of materials, residual stress, crystal dislocation, and non-uniform doping concentration.

10. The stacking detection method according to claim 1, wherein the first direction is the normal direction of at least one interface between a plurality of layers.

11. A terahertz electromagnetic wave generator configured to generate terahertz-emitting electromagnetic waves and emit the terahertz-emitting electromagnetic waves onto a solid material at an arbitrary angle, A terahertz electromagnetic wave receiver is configured to detect a plurality of terahertz received electromagnetic waves that are reflected or transmitted after the terahertz emitted electromagnetic waves are incident on the solid material and pass through the entire thickness of the solid material in a first direction, A stacking detection system comprising: a detection device coupled to the terahertz electromagnetic wave generator and the terahertz electromagnetic wave receiver, configured to actively divide the solid material into a plurality of parallel layers along the first direction, determine a plurality of characteristics of the plurality of layers, and determine at least one defect information for each of the plurality of layers based on the plurality of characteristics of the plurality of layers.

12. The frequency of the aforementioned terahertz emitted electromagnetic wave is 10 １１ Hz to 10 １３ The stacking detection system according to claim 11, wherein the frequency is Hz.

13. The stacked detection system according to claim 11, wherein the plurality of characteristic signals include the electric field strength, electric field frequency, and electric field phase of each of the plurality of terahertz received electromagnetic waves.

14. The stacked detection system according to claim 13, wherein the plurality of characteristic signals further include at least one spectral electric field between the plurality of terahertz received electromagnetic waves, each spectral electric field includes electric field amplitude, electric field phase, and electric field polarization.

15. The stacked detection system according to claim 11, wherein the plurality of characteristics include at least one of the electrical coefficients and optical coefficients of each of the plurality of layers.

16. The stacked detection system according to claim 15, wherein the electrical coefficient is at least one of conductivity, resistivity, doping concentration, dielectric constant, and charge carrier mobility, and the optical coefficient is at least one of absorptivity, refractive index, reflectivity, and transmittance.

17. The stacking detection system according to claim 11, wherein the solid material is one or more selected from semiconductor wafers, ceramic materials, and polymer materials.

18. The semiconductor wafers include silicon wafers (Si), germanium wafers (Ge), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), cadmium sulfide (CdS), indium phosphide (InP), zinc oxide (ZnO), and gallium oxide (Ga ２ O ３ The stacked detection system according to claim 17, wherein the material is at least one of the following: ), and aluminum nitride (AlN).

19. The stacking detection system according to claim 11, wherein at least one of the defect information is at least one of the following: material non-uniformity, bubbles or porosity, non-uniform mixing of multiple materials, residual stress, crystal dislocations, and non-uniform doping concentration.

20. The stacking detection system according to claim 11, wherein the first direction is the normal direction of at least one interface between the plurality of layers.

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