Lamination detecting method and lamination detecting system

Abstract

To provide a lamination detection method and a lamination detection system capable of non-contact and non-destructive detection of a non-transparent solid material.SOLUTION: The lamination detection method includes step 134 of generating terahertz emission electromagnetic waves and emitting the terahertz emission electromagnetic waves to a solid material at an arbitrary angle, step 136 of detecting a plurality of terahertz reception electromagnetic waves reflected or transmitted after the terahertz emission electromagnetic waves are incident to the solid material and pass through an 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 emission electromagnetic waves and the plurality of terahertz reception 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 layer of the plurality of layers based on the plurality of characteristics of the plurality of layers.SELECTED DRAWING: Figure 13

Description

[Technical Field]

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

[0002] Semiconductor wafers, ceramic, 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 for assessing whether the material is suitable for use. The quality of the processed product is also primarily determined by these physical properties. During the incoming inspection of raw materials or the functional verification stage of semi-finished and finished products, several key parameters are typically selected as pass / fail standards.

[0003] Common mechanical properties of materials include Vickers hardness, fracture toughness, flexural strength, and elastic modulus. Thermal properties include thermal expansion coefficient, thermal conductivity, and specific heat capacity. Optoelectronic properties include refractive index, dielectric constant, and electrical conductivity, which represent these parameters. In addition, thickness, warpage, and surface roughness of solid materials 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 contact the sample and cause some degree of damage.

[0004] Meanwhile, the presence of defects inside the material can also be used as an evaluation indicator. 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). However, these are not only expensive and time-consuming, but in most cases can only detect the sample surface and cannot simultaneously detect multiple parameters.

[0005] Existing technologies for detecting defects below the sample surface, such as optical coherence tomography (OCT), total internal reflection fluorescence microscopy (TIRFM), and scanning acoustic microscopy (SAM), are mature, but they have significant limitations in the materials they can inspect. For example, they cannot inspect low-light-scattering or opaque materials, or even if they can, they suffer from insufficient resolution.

[0006] Therefore, there is a need to improve upon the prior art. Summary of the Invention

[0007] Therefore, an object of the present invention is to provide a layer detection method and a layer detection system that enable non-destructive detection of non-transparent solid materials.

[0008] One embodiment of the present invention discloses a layered detection method, which includes the steps of generating a terahertz emission electromagnetic wave and emitting the terahertz emission electromagnetic wave at an arbitrary angle to a solid material; detecting a plurality of terahertz reception electromagnetic waves that are reflected or transmitted after the terahertz emission electromagnetic wave is incident on the solid material and passes through an entire thickness of the solid material in a first direction; measuring and analyzing a plurality of characteristic signals based on the terahertz emission electromagnetic wave and the plurality of terahertz reception 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 determining at least one defect information of 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 layer detection system, the layer detection system including: a terahertz electromagnetic wave generator configured to generate a terahertz emission electromagnetic wave and emit the terahertz emission electromagnetic wave into a solid material at an arbitrary angle; a terahertz electromagnetic wave receiver configured to detect a plurality of reflected or transmitted terahertz reception electromagnetic waves after the terahertz emission electromagnetic wave is incident on the solid material and passes through an 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, and configured to measure and analyze a plurality of characteristic signals based on the terahertz emission electromagnetic wave and the plurality of received terahertz electromagnetic waves to separate 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 of each of the plurality of layers based on the plurality of characteristics of the plurality of layers.

[0010] These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a functional block diagram of a stack detection system according to an embodiment of the present invention. [Figure 2] 1 is a schematic diagram of reflection and refraction of an electromagnetic wave as it propagates through a medium. [Figure 3] 1 is a schematic diagram of a stack detection system according to an embodiment of the present invention; [Figure 4A] FIG. 4 is a schematic diagram of a time-domain optical spectrum detected by the stacked detection system shown in FIG. 3. [Figure 4B] FIG. 4 is a schematic diagram of a frequency domain optical spectrum detected by the stacked detection system shown in FIG. 3. [Figure 5] 1 is a schematic diagram of a stack detection system according to an embodiment of the present invention; [Figure 6A] FIG. 6 is a schematic diagram of a time-domain optical spectrum detected by the stacked detection system shown in FIG. 5. [Figure 6B] FIG. 6 is a schematic diagram of a frequency domain optical spectrum detected by the stacked detection system shown in FIG. 5. [Figure 7] FIG. 1 is a schematic diagram of the scan across the sample. [Figure 8] FIG. 1 is a schematic diagram of a wafer. [Figure 9A] FIG. 9 is a schematic diagram of a refractive index distribution map obtained without performing stacking calculations for the wafers shown in FIG. 8. [Figure 9B] FIG. 4 is a schematic diagram of a refractive index distribution map obtained by the stack detection system shown in FIG. 3. [Figure 10] 1 is a schematic diagram of a wafer stack structure according to an embodiment of the present invention. [Figure 11A] FIG. 3 is a refractive index distribution diagram of the first wafer. [Figure 11B] FIG. 3 is a refractive index distribution diagram of the first wafer. [Figure 11C] FIG. 3 is a refractive index distribution diagram of the first wafer. [Figure 12A] FIG. 10 is a refractive index distribution diagram of the second wafer. [Figure 12B] FIG. 10 is a refractive index distribution diagram of the second wafer. [Figure 12C] FIG. 10 is a refractive index distribution diagram of the second wafer. [Figure 13] FIG. 1 is a schematic diagram of a stack detection process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Certain terms are used throughout the specification and the claims that follow to refer to particular components. As one skilled in the art will appreciate, hardware manufacturers may refer to components by different names. This document does not intend to distinguish between components that differ in name but function. In the following specification and claims, the terms "include" and "comprise" are used in an open-ended manner and should be interpreted to mean "including, but not limited to." Additionally, the term "couple" is intended to mean either an indirect or direct electrical connection. Thus, when one device is coupled to another device, the connection may be through a direct electrical connection or through an indirect electrical connection via other devices and connections.

[0013] Semiconductor wafers, ceramics, and polymers undergo multiple steps in their manufacturing processes. These processes include high-temperature processes (such as sintering and annealing) and mechanical and physical processes (such as grinding, polishing, crushing, and compression), which can all cause defects inside the material. To ensure that the physical properties of these materials meet requirements, appropriate inspection methods must be implemented during the production and manufacturing process. However, most non-destructive testing methods can only detect the surface, and most methods for detecting the interior of the material require the destruction of the sample. Therefore, how to effectively analyze the interior of a material without contact and without destructive destruction has become one of the goals facing the industry. In this context, the present invention uses terahertz electromagnetic waves to achieve non-contact and non-destructive detection. Terahertz electromagnetic waves can be used for up to 10 11 Hz~10 13It operates in the frequency range of 100 Hz (0.1 THz to 10 THz), which allows for the penetration of non-conductive materials and the measurement of highly hydrated materials. The advantage of terahertz detection is that it has good penetration into many materials and can be used to detect the optical coefficients, electrical properties, layer thickness, or structural defects of various materials and structures inside test pieces. Terahertz detection can also be used for in-process technical inspections, inspection of semi-finished or finished products. When using terahertz electromagnetic waves to detect test pieces, the frequency of terahertz electromagnetic waves is higher than the frequency of infrared waves (10 13 Hz~10 15 Hz), the photons carried by terahertz electromagnetic waves have less energy and do not destroy molecular structures, thereby maintaining structural integrity and preventing further damage or defects, greatly reducing the probability of destructive testing of finished products.

[0014] Specifically, see FIG. 1 , which is a functional block diagram of a layered detection system 1 according to an embodiment of the present invention. The layered 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-state material. More specifically, the layered detection system 1 can perform layered detection within a solid-state material, which may be one or more selected from a semiconductor wafer, a ceramic material, and a polymer material. The semiconductor wafer may be at least one of a silicon wafer (Si), a germanium wafer (Ge), a silicon carbide (SiC), a gallium arsenide (GaAs), a gallium nitride (GaN), a gallium phosphide (GaP), a cadmium sulfide (CdS), an indium phosphide (InP), a zinc oxide (ZnO), a gallium oxide (Ga2O3), and an aluminum nitride (AlN). The terahertz electromagnetic wave generator 10 is used to generate terahertz radiation, which is incident on the solid-state material at an arbitrary angle. The terahertz electromagnetic wave receiver 12 is used to detect a plurality of reflected or transmitted terahertz received electromagnetic waves 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. 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 a plurality of characteristic signals based on the terahertz emitted electromagnetic waves and the plurality of received terahertz electromagnetic waves to divide the solid material into a plurality of parallel layers along the first direction and determine a plurality of properties of the plurality of layers, thereby determining at least one defect information for each of the plurality of layers. The first direction is a normal direction of the interfaces of the plurality of layers.

[0015] In short, the detection device 14 divides the solid material into multiple layers and analyzes the characteristics of each layer, thereby determining the defect conditions inside the solid material, such as material inhomogeneity, bubbles or porosity, uneven mixing of multiple materials, residual stress, crystal dislocations, uneven doping concentration, etc. The relevant principle is explained as follows:

[0016] See Figure 2, which is a schematic illustration of reflection and refraction as an electromagnetic wave propagates through a medium. As shown in Figure 2, an incident electromagnetic wave I is subjected to a complex refractive index

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

[0018] The specific forms of reflectance and transmittance also depend on 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-polarization 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-polarization state." Based on Fresnel's equation, for an s-polarized incident electromagnetic wave I, the reflectance is given by:

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[0019] The detection device 14 divides the solid material into multiple layers based on the above formula and determines the characteristics of each layer, thereby determining defect information for each layer. The detection device 14 is not limited to a specific technology for determining the characteristics of each layer. For example, the applicant provided a composite structure detection method and a composite structure detection system in U.S. Patent Application No. 18 / 813,045, which may be appropriately adapted and applied to the present invention. For example, in one embodiment, the detection device 14 compares a terahertz radiation signal detecting air with a terahertz radiation signal detecting a solid material, analyzes the time-domain optical spectrum and the frequency-domain optical spectrum to measure characteristic signals, and further analyzes the refractive index, dielectric constant, conductivity, doping concentration, etc. of each layer of the solid material, thereby analyzing the structure and defects of each layer within the solid material and providing a basis for determining defects. Defects may be, for example, material inhomogeneities (e.g., bubbles, uneven mixing of multiple materials), lattice dislocations, uneven doping concentrations, etc. Specifically, the detector 14 measures the transient electric field of each received terahertz electromagnetic wave in the time domain to obtain the field strength, field phase, and field frequency of the transient (time-domain) electric field, and applies a transform (e.g., Fourier transform) to obtain the spectral electric field between the received terahertz electromagnetic waves to obtain the field amplitude, field polarization, and field phase of the spectral electric field. That is, the characteristic signals measured by the detector 14 may include the transient electric field strength and phase of each received terahertz electromagnetic wave in the time domain, as well as the spectral electric field amplitude, polarization, and phase between the received terahertz electromagnetic waves in the frequency domain. Because the characteristic signals (transient electric field strength and phase, as well as the spectral electric field amplitude, polarization, and phase) are highly sensitive to material properties, the optical coefficients (absorption coefficient, 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. Meanwhile, the detector 14 can measure the time of flight of a plurality of received terahertz electromagnetic waves and analyze the time of flight to determine the thickness of each layer inside the solid material.In this way, the detection device 14 can analyze whether there is an abnormality in the structure between layers, whether there is an abnormality in the position of the components, whether the thickness is as designed, changes in stress, etc. based on the time-domain time-of-flight spectrum signal, and can also be used to determine whether the process technology is incorrect or whether the components are defective.

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

[0021] It should be noted that the above Equations 1 to 4 form the basis for the stacking operation of the detection device 14 in the stacking detection system 1. The operating 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 / 813,045. It may also be various methods or systems for detection using electromagnetic waves. For example, the applicant provides a semiconductor wafer detection method and semiconductor wafer detection device in Taiwan Patent No. I788105, which detects the characteristics of multiple interface layers of a semiconductor wafer using terahertz electromagnetic waves, and may be appropriately adjusted and applied to the present invention.

[0022] Furthermore, the stacked detection system 1 shown in FIG. 1 is represented by functional blocks, which are essential components for implementing 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, FIG. 3 is a schematic diagram of a stacked detection system 3 according to an embodiment of the present invention. The stacked detection system 3 is derived from the stacked detection system 1 and uses a transmission-type terahertz electromagnetic wave detection architecture. For simplicity, FIG. 3 omits the specific location of the detection device 14, which those skilled in the art can infer from FIG. 1 . Specifically, the stacked detection system 3 uses a terahertz electromagnetic wave generator 30 to generate a terahertz emission electromagnetic wave I, which is incident on a test piece TS (e.g., a solid material). A terahertz electromagnetic wave receiver 32 detects multiple terahertz reception electromagnetic waves R that are transmitted through the test piece TS after the terahertz emission electromagnetic wave I is incident on the test piece TS. Note that the layering in the test piece TS does not indicate that the structure of the test piece TS itself includes a layered structure, but is used to indicate 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 layered detection system 3 utilizes a transmission-type terahertz electromagnetic wave detection architecture, which can compare the signal of the terahertz emitted electromagnetic wave detecting air with the signal of the terahertz emitted electromagnetic wave detecting a solid material, analyze the time-domain and frequency-domain optical spectra, and measure characteristic signals. For example, see FIGS. 4A and 4B, which are schematic diagrams of the time-domain optical spectrum and the frequency-domain optical spectrum, respectively, detected by the layered detection system 3. In FIG. 4A, the solid line represents the result of the electric field versus the optical delay (time-domain optical spectrum) of the terahertz emitted electromagnetic wave detecting air (without the solid material to be inspected), and the dotted line represents the result of the electric field versus the optical delay (time-domain optical spectrum) of the terahertz emitted electromagnetic wave detecting a solid material. In FIG. 4B, the solid line represents the result of the electric field versus the frequency spectrum (frequency-domain optical spectrum) of the terahertz emitted electromagnetic wave detecting air (without the solid material to be inspected), and the dotted line represents the result of the electric field versus the frequency spectrum (frequency-domain optical spectrum) of the terahertz emitted electromagnetic wave detecting a solid material. Therefore, the detection device 14 of the transmission detection architecture can measure characteristic signals by analyzing the time-domain optical spectrum and the frequency-domain optical spectrum, and further analyze and obtain the refractive index, dielectric constant, conductivity, doping concentration, etc. of each layer of the solid material, thereby analyzing the internal structure of the solid material and the presence or absence of defects, and providing a basis for determining defects. Defects may be, for example, material inhomogeneities (e.g., bubbles, inhomogeneous mixture of multiple materials), lattice dislocations, inhomogeneous doping concentrations, etc.

[0024] Furthermore, the stacked detection system 3 has a transmission architecture. That is, the terahertz electromagnetic wave received by the terahertz electromagnetic wave receiver 32 is the result of the incident electromagnetic wave I passing 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 calculates the electric field strengths of the incident electromagnetic wave I and the refracted electromagnetic wave F corresponding to this interface, and the respective angles θ with the normal to the incident point. i , θ tcan be obtained, and the complex refractive index of the medium (layer) on both sides of this interface (i.e.,

number

[0025] Please refer to FIG. 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, FIG. 5 omits the specific location of the detection device 14, which a person skilled in the art can infer from FIG. 1 . Specifically, the stacked detection system 5 uses a reflective detection structure in which 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 a terahertz emission electromagnetic wave I, emits the terahertz emission electromagnetic wave I toward a test piece TS (e.g., a solid material), and detects multiple terahertz reception electromagnetic waves R reflected by the test piece TS after the terahertz emission electromagnetic wave I is incident on the test piece TS. Furthermore, the operation method of the stacked detection system 5 can be referenced to the operation methods of the stacked detection systems 1 and 3 described above.

[0026] 6A and 6B are schematic diagrams of time-domain and frequency-domain optical spectra detected by the layered detection system 5, respectively. In FIG. 6A, the solid line represents the electric field versus the optical delay (time-domain optical spectrum) of the terahertz-emitted electromagnetic wave detecting a metal plate or a highly conductive material, and the dotted line represents the electric field versus the optical delay (time-domain optical spectrum) of the terahertz-emitted electromagnetic wave detecting a solid material. In FIG. 6B, the solid line represents the electric field versus the frequency spectrum (frequency-domain optical spectrum) of the terahertz-emitted electromagnetic wave detecting a metal plate or a highly conductive material, and the dotted line represents the electric field versus the frequency spectrum (frequency-domain optical spectrum) of the terahertz-emitted electromagnetic wave detecting a solid material. Thus, the detection device 14 of the reflective detection architecture can measure characteristic signals by analyzing the time-domain optical spectrum and the frequency-domain optical spectrum, and can further analyze and obtain the refractive index, dielectric constant, conductivity, doping concentration, etc. of each layer of the solid material, which can analyze the internal structure and presence or absence of defects in the solid material, or provide evidence for identifying defects. Defects may be, for example, material inhomogeneities (eg, bubbles, uneven mixing of multiple materials), lattice dislocations, uneven doping concentrations, and the like.

[0027] Furthermore, the stacked detection system 5 is a reflective architecture, i.e., the terahertz received electromagnetic wave received by the terahertz electromagnetic wave generating / receiver 50 is the result of the incident electromagnetic wave I being reflected after passing 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 calculates the electric field strengths of the incident electromagnetic wave I and the reflected electromagnetic wave Q corresponding to this interface, and their respective angles θ with the normal to the incident point. i , θ r can be obtained, and the complex refractive index of the medium (layer) on both sides of this interface (i.e.,

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[0028] The stacked layer detection systems 3 and 5 use transmission and reflection terahertz electromagnetic wave detection architectures derived from the stacked layer detection system 1. Those skilled in the art should select appropriate architectures based on their actual needs and inspection requirements. Generally speaking, transmission terahertz electromagnetic wave detection architectures can directly transmit through solid materials to obtain information about the overall phase difference and signal intensity difference, while reflection terahertz electromagnetic wave detection architectures can reflect signals when transmitting through the interfaces between layers, returning one or more terahertz waves. Based on these signals, the structural 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] 4A, 4B, 6A and 6B show the results of single-point detection of solid materials by the layer detection systems 3 and 5. Next, application scenarios of layer 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. From the raw material stage, bare wafers undergo various manufacturing processes, 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 (e.g., stacked detection systems 1, 3, and 5) are applied to bare wafer detection, single-point detection can be performed on the bare wafer, obtaining results similar to those shown in FIGS. 4A, 4B, 6A, and 6B. Furthermore, embodiments of the present invention can also detect the entire sample in a scanning mode by moving the detector or sample stage, obtaining scanning results such as those shown in FIG. 7. Based on these results, signals from each region of the sample can be observed to determine whether the thickness is correct, the distribution of surface warpage, internal nonuniformities, or other structural defects. However, in some applications, performing global detection of the wafer, such as thermal conductivity, bending strength, and thickness, may not allow for the observation of internal 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 equations and their derivation algorithms, and can further obtain various physical parameters of each layer. That is, the stacking method for solid materials of the present invention is not limited by the actual structure of the solid material, but can be performed according to the number of layers, the thickness of each layer, etc. Different stacking calculations can be performed on the same solid material in different detection procedures. For example, in a detection procedure, embodiments of the present invention can perform full-thickness detection without performing stacking calculations on the wafer. If the detection results at this time cannot reflect 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 / separating the wafer into two layers and detecting the characteristics of these two layers. If the detection results at this time are still insufficient to reflect differences in the internal structure of the wafer, the detection procedure can be performed again, dividing more layers and performing calculations.Furthermore, when performing stacking calculations, the thickness of each layer can be arbitrarily specified according to different analysis purposes and is not limited to any particular rule.

[0031] The present invention provides a method for layering the wafer's interior, thereby enabling more accurate determination of the wafer's internal structure and, therefore, determining the defect status within the wafer. For example, see FIG. 8 , which is a schematic diagram of a wafer 80. In one embodiment, to detect the structure of the wafer 80, an operator uses the layer stack detection system 3 of FIG. 3 , i.e., a transmission-type terahertz electromagnetic wave detection architecture, to detect the wafer 80 and obtain a refractive index distribution map of the entire thickness of the wafer 80, as shown in FIG. 9A . That is, FIG. 9A is a refractive index distribution map obtained without performing layer stack calculations on the wafer 80, and based on this, it is not possible to determine whether the wafer 80 has local non-uniformities. Next, to more accurately detect the structure of the wafer 80, an operator can perform layer stack calculations on the wafer 80 using the layer stack detection system 3. For example, the operator can divide / split the wafer 80 into layers L1 and L2, set the thickness of layer L1 to 10 μm, and use the layer stack detection system 3 to obtain a refractive index distribution map of the interface between layers L1 and L2 (10 μm below the surface), as shown in FIG. 9B . As can be seen from FIG. 9B, there is a clear distribution non-uniformity between the top and bottom halves of wafer 80.

[0032] 9A and 9B, it can be seen that while a global analysis (i.e., unlayered analysis) of wafer 80 cannot determine whether there are local non-uniformities in wafer 80, the refractive index distribution map 10 μm below the surface shows that there are obvious distribution non-uniformities in wafer 80. Therefore, the stacking calculation and subsequent stacking property detection of the present invention can clearly reflect the internal structure and the presence or absence of defects, and provide a basis for determining defects.

[0033] The stacking characteristic detection items of the present invention can be adjusted as appropriate depending on system requirements. For example, see FIG. 10, which is a schematic diagram of a wafer stacking structure 100. In one embodiment, to detect the structure of the first and second wafers, an operator uses the stacking detection system 5 of FIG. 5, i.e., a reflective terahertz electromagnetic wave detection architecture, to divide the first and second wafers into layers L1 to L3 according to the wafer stacking structure 100. The thickness of layer L1 is 2 μm, and the thickness of layer L2 is 8 μm, i.e., the total thickness of layers L1 and L2 is 10 μm. After stacking, the stacking detection system 5 detects the first and second wafers separately and obtains the inspection results shown in FIGS. 11A to 11C and 12A to 12C. Figure 11A is a refractive index distribution map for the entire thickness of the first wafer, Figure 11B is a refractive index distribution map for the interface between layers L2 and L3 of the first wafer (10 μm below the surface), Figure 11C is a refractive index distribution map for the interface between layers L1 and L2 of the first wafer (2 μm below the surface), Figure 12A is a refractive index distribution map for the entire thickness of the second wafer, Figure 12B is a refractive index distribution map for the interface between layers L2 and L3 of the second wafer (10 μm below the surface), and Figure 12C is a refractive index distribution map 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 Figures 12A-12C, the refractive index distributions 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 across the first and second wafers. For example, the standard deviation of the refractive index in Figure 11A is 0.007, while the standard deviation of the refractive index in Figure 12A is 0.006, which are not significantly different. The standard deviation of the refractive index in Figure 11B is 0.026, while the standard deviation of the refractive index in Figure 12B is 0.027, which are slightly different. The standard deviation of the refractive index in Figure 11C is 0.19, while the standard deviation of the refractive index in Figure 12C is 0.09. The former is 2.1 times larger than the latter. This suggests that the first wafer has many defects and a large non-uniformity in the refractive index distribution in the shallow layer.

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

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

[0037] Step 132: Start.

[0038] Step 134: Generate terahertz radiation and direct it into a solid material.

[0039] Step 136: Detecting a plurality of reflected or transmitted terahertz received electromagnetic waves 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.

[0040] Step 138: Measuring and analyzing a plurality of characteristic signals based on the terahertz emitted electromagnetic waves and the plurality of terahertz received electromagnetic waves to separate the solid material into a plurality of parallel layers along the first direction and determine a plurality of characteristics of the plurality of layers.

[0041] Step 140: Determine at least one defect information of each layer of the plurality of layers based on the plurality of characteristics of the plurality of layers.

[0042] Step 142: End.

[0043] For a detailed description of the operation and variations of the stack detection process 130, please refer to the above description.

[0044] In conventional techniques, if a material is not transparent to visible light, the completed structure cannot be inspected using visible light microscopy. This may result in defects such as differences in deposition layer thickness, residual internal defects, exposure misalignment, coverage errors, and differences in material doping concentration. Even if the completed structure can undergo several 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 the multiple characteristic signals, divides the solid material into multiple layers, and determines the multiple characteristics of each layer based on the multiple characteristic signals. Because terahertz electromagnetic waves can penetrate many materials, they can be used to detect optical coefficients, electrical properties, layer thicknesses, or structural defects of different materials and structures within a substrate. They can also be used for process technology inspections, semi-finished products, or finished product inspections. More importantly, the present invention can accurately analyze or compare the internal structure of solid materials through layer detection, determining the presence or absence of defects or providing a basis for judging defects. Therefore, the present invention realizes non-contact, non-destructive detection of non-transparent solid materials and improves detection resolution through layer detection.

[0045] Those skilled in the art will readily recognize that numerous modifications and variations of the apparatus and method may be made while retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

Claims

1. generating a terahertz radiation electromagnetic wave and emitting the terahertz radiation electromagnetic wave at an arbitrary angle to a solid material; detecting a plurality of reflected or transmitted terahertz received electromagnetic waves 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; measuring and analyzing a plurality of characteristic signals based on the emitted terahertz electromagnetic waves and a plurality of the received terahertz electromagnetic waves to separate the solid-state material into a plurality of parallel layers along the first direction and determine a plurality of characteristics of the plurality of layers; determining at least one defect information for each layer of the plurality of layers based on the plurality of characteristics of the plurality of layers.

2. The frequency of the terahertz emitted electromagnetic wave is 10 １１ Hz to 10 １３ 10. The stack detection method of claim 1, wherein the frequency is 100 Hz.

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

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

5. The stack detection method of claim 1 , wherein the plurality of properties includes at least one of an electrical coefficient and an optical coefficient of each of the plurality of layers.

6. 6. The stack detection method of 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 absorption coefficient, refractive index, reflectivity, and transmittance.

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

8. The semiconductor wafer may be a silicon wafer (Si), a germanium wafer (Ge), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), cadmium sulfide (CdS), indium phosphide (InP), zinc oxide (ZnO), gallium oxide (Ga ２ O ３ 8. The method of claim 7, wherein the material is at least one of aluminum nitride (AlN) and aluminum nitride (AlN).

9. 2. The stack detection method of claim 1, wherein the at least one defect information is at least one of information on material inhomogeneity, bubbles or porosity, inhomogeneous mixing of multiple materials, residual stress, crystal dislocations, and inhomogeneous doping concentration.

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

11. a terahertz electromagnetic wave generator configured to generate terahertz radiation electromagnetic waves and emit the terahertz radiation electromagnetic waves at an arbitrary angle to a solid material; a terahertz electromagnetic wave receiver configured to detect a plurality of reflected or transmitted terahertz received electromagnetic waves 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 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 wave and a plurality of the received terahertz electromagnetic waves to separate 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 terahertz emitted electromagnetic wave is 10 １１ Hz to 10 １３ 12. The stacked detection system of claim 11, wherein the frequency is Hz.

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

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

15. The stacked detection system of claim 11 , wherein the plurality of properties includes at least one of an electrical coefficient and an optical coefficient of each of the plurality of layers.

16. 16. The stacked detection system of 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 absorption, refractive index, reflectivity, and transmittance.

17. The stacked detection system of claim 11 , wherein the solid material is one or more selected from a semiconductor wafer, a ceramic material, and a polymer material.

18. The semiconductor wafer may be a silicon wafer (Si), a germanium wafer (Ge), silicon carbide (SiC), gallium arsenide (GaAs), gallium nitride (GaN), gallium phosphide (GaP), cadmium sulfide (CdS), indium phosphide (InP), zinc oxide (ZnO), gallium oxide (Ga ２ O ３ 20. The laminated detection system of claim 17, wherein the metal is at least one of: aluminum nitride (AlN);

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

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

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