A wafer inspection device and method for hyperspectral and 3D measurement

Abstract

This invention discloses a wafer inspection device and method for hyperspectral and 3D measurement, comprising: a movable stage for carrying the sample to be measured; a light source module, a first slit, and a tube mirror arranged sequentially along a first optical path; the tube mirror includes a beam-splitting module installed inside it and an objective lens module installed on the side away from the light source module, the objective lens module including a first objective lens with axial dispersion and a second objective lens without axial dispersion, and an objective lens switching module for switching between the first and second objective lenses; and a tube mirror, a second slit, and a spectral imaging system arranged sequentially along a second optical path. Based on the characteristics of infinity-corrected microscopic imaging systems, this invention uses the differences between the 3D measurement module and the hyperspectral measurement module as a switching module, while designing other common parts as a single unit, reducing the volume, making the system simpler, lighter, and more efficient, and significantly saving costs.

Description

Technical Field

[0001] This invention mainly relates to semiconductor wafer inspection, and more specifically, to a wafer inspection device and method for hyperspectral measurement and 3D measurement. Background Technology

[0002] With technological advancements, semiconductor technology is finding increasingly widespread applications in everyday life. Semiconductor manufacturing involves numerous and complex process stages / processes from start to finish. Due to the complexity and numerous steps involved, each stage requires rigorous quality inspection and evaluation instruments and methods. For example, at the wafer stage, semiconductors need to undergo visual defect detection or photoluminescence measurement. This intercepts defective products from that process stage, preventing them from flowing into subsequent stages and affecting product yield. Furthermore, identifying defects can also promote process improvement and optimization.

[0003] In the semiconductor wafer inspection stage, high resolution is required, necessitating the use of microscopic imaging devices. However, this high-resolution microscopic imaging typically has a very small depth of field, generally below 50μm. But wafers generally have significant undulations, and the XY platform at the bottom of the inspection platform cannot guarantee strictly horizontal movement during operation. This means that when photographing different areas, the wafer may very well extend beyond the depth of field, resulting in blurred images and hindering accurate defect measurement.

[0004] In addition, current imaging detection methods that rely solely on camera imaging are no longer reliable. It is necessary to measure not only the defect characteristics of the surface product, but also the emission spectrum characteristics of the surface. Therefore, it is necessary to perform spectral measurements on the product during scanning.

[0005] Existing technical solutions, such as 3D measurement modules and spectral imaging measurements, typically require two separate machines and two sets of equipment due to the differences in their imaging systems. This results in large equipment sizes and difficulties in interaction. Summary of the Invention

[0006] To address at least one deficiency or improvement need in the prior art, this invention provides a wafer inspection device and method for hyperspectral measurement and 3D measurement. Based on the characteristics of the infinity microscopic imaging system, the differences between the 3D measurement module and the hyperspectral measurement module are used as switching modules, while other common parts are designed as a whole, reducing the volume, making the system simpler, lighter, and more efficient, and greatly saving costs.

[0007] To achieve the above objectives, according to a first aspect of the present invention, a wafer inspection apparatus for hyperspectral measurement and 3D measurement is provided, the apparatus comprising:

[0008] A mobile stage is used to carry the sample to be tested;

[0009] The system comprises a light source module, a first slit, and a tube mirror arranged sequentially along a first optical path. The tube mirror includes a beam splitter module installed inside it and an objective lens module installed on the side away from the light source module. The objective lens module includes a first objective lens with axial dispersion and a second objective lens without axial dispersion, and also includes an objective lens switching module for switching between the first objective lens and the second objective lens. The system also includes a tube mirror, a second slit, and a spectral imaging system arranged sequentially along a second optical path. The beam splitter module is used to separate the first optical path and the second optical path.

[0010] The light source module is used to emit polychromatic light, which travels along the first optical path, through the first slit and the tube mirror, and is then focused by the first objective lens and vertically illuminates the surface of the sample to be tested. The first objective lens is also used to collect the polychromatic light reflected from the surface of the sample to be tested, which travels along the second optical path, through the tube mirror and the second slit, and enters the spectral imaging system to perform 3D measurement on the surface of the sample to be tested.

[0011] After the surface height of the sample to be tested is measured, the objective lens is switched to the second objective lens, and the spectral imaging system receives the imaging light of the sample to be tested transmitted along the second optical path to perform hyperspectral measurement on the surface of the sample to be tested.

[0012] Furthermore, the aforementioned wafer inspection device for hyperspectral and 3D measurement also includes:

[0013] The first slit and the second slit are located at the image plane of the endoscope.

[0014] Furthermore, the aforementioned wafer inspection device for hyperspectral and 3D measurement also includes:

[0015] The spectral imaging system includes a dispersive system, an imaging lens, and an image acquisition system arranged in sequence.

[0016] Furthermore, the aforementioned wafer inspection device for hyperspectral and 3D measurement also includes:

[0017] The spectral imaging system also includes a collimation system located at the front end of the dispersive system.

[0018] Furthermore, the aforementioned wafer inspection device for hyperspectral and 3D measurement also includes:

[0019] The dispersion system is a grating.

[0020] Furthermore, the aforementioned wafer inspection device for hyperspectral and 3D measurement also includes:

[0021] The control module is used to control the moving stage to move along a specified path, so that the spectral imaging system can perform 3D measurements on different parts of the surface of the sample to be tested, and realize comprehensive 3D measurement of the surface of the sample to be tested.

[0022] Alternatively, when the sample to be tested is relatively flat, the spectral imaging system can perform 3D measurements at certain intervals on the surface of the sample to be tested, thereby realizing surface sampling 3D measurement of the sample to be tested.

[0023] Furthermore, the aforementioned wafer inspection device for hyperspectral and 3D measurement also includes:

[0024] The imaging light on the surface of the sample under test originates from the sample's own light emission or other illumination light.

[0025] Furthermore, the aforementioned wafer inspection device for hyperspectral and 3D measurement also includes:

[0026] The objective lens switching module is a nose wheel or a linear motor.

[0027] Furthermore, the aforementioned wafer inspection device for hyperspectral and 3D measurement also includes:

[0028] The magnification of the first objective lens and the second objective lens is selected according to the test requirements.

[0029] According to a second aspect of the present invention, a wafer inspection method for hyperspectral measurement and 3D measurement is also provided, which is implemented using a wafer inspection apparatus for hyperspectral measurement and 3D measurement as described in any of the preceding claims, comprising:

[0030] Switch the objective lens of the tube to the first objective lens, turn on the light source system, and generate polychromatic light that shines through the first slit and the tube onto the surface of the sample to be tested.

[0031] The spectral imaging system receives the polychromatic light reflected from the surface of the sample to be tested and performs 3D measurement on the surface of the sample to be tested;

[0032] The objective lens of the tube is switched to the second objective lens, and the spectral imaging system receives the imaging light from the surface of the sample to be tested and performs hyperspectral measurements on the surface of the sample to be tested.

[0033] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0034] The present invention provides a wafer inspection device and method for hyperspectral measurement and 3D measurement. Based on the characteristics of the infinity microscopic imaging system, the difference between the 3D measurement module and the hyperspectral measurement module is used as a switching module, while the other common parts are designed as a whole. This reduces the volume, makes the system simpler, lighter, and more efficient, and greatly saves costs. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a wafer inspection device for hyperspectral and 3D measurement provided in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of a spectral imaging system provided in an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0039] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0040] 3D inspection of wafer surfaces is a common inspection item in wafer inspection projects. The inspection method is to obtain the height information of various points on the wafer surface. Spectral confocal method is a displacement measurement system. Its principle is that point polychromatic light is focused onto planes of different depths after passing through a dispersive lens. Based on the principle of optical path reversibility, when the surface to be measured is located at a certain focal position, the focal spot of the corresponding wavelength is analyzed by spectral analysis after passing through the dispersive lens to determine the defocusing of the surface to be measured. For spectral confocal method, please refer to the following existing technical literature: Gao Xin, Deng Wenyi, Niu Chunhui. Research on displacement measurement system based on color confocal. Optical Technology, 38(1), 2012.

[0041] Based on the above principles, such as Figure 1 As shown, as a first embodiment of the present invention, a wafer inspection device for hyperspectral measurement and 3D measurement is provided. The wafer inspection device in this embodiment includes a first optical path and a second optical path. The first optical path, serving as the light source for 3D measurement, includes a light source module 1 and a tube lens 5. In this embodiment, the tube lens 5 is chosen as the specific structural form of the optical path. The tube lens 5 includes an objective lens located near the sample 7 to be measured, and the objective lens structure includes at least a first objective lens 81 with axial dispersion. Thus, when the light source module 1 emits polychromatic light (e.g., white light), the first objective lens 81 with axial dispersion can focus light of different wavelengths in the polychromatic light onto the surface at different depths. By receiving the reflected light from the surface of the sample 7 and performing spectral analysis, 3D measurement of the surface of the sample 7 can be achieved.

[0042] The dispersion of the first objective lens 81 is due to the different refractive indices of white light (polychromatic light) within the lens, causing it to focus at different points. Dispersion includes axial dispersion and off-axis dispersion. Dispersion may need to be eliminated or utilized depending on the application scenario. The first optical path in this invention utilizes the axial dispersion characteristics of the first objective lens 81 for spectral confocal ranging. The magnitude of the axial dispersion of the first objective lens 81 can be adjusted according to the size, structure, and form of the device; this invention does not impose any limitations on this.

[0043] The wafer inspection device in this embodiment also requires hyperspectral measurement of the surface of the sample 7. During hyperspectral measurement, the dispersion of the objective lens reduces image quality, which is detrimental to hyperspectral measurement and analysis. Therefore, the objective lens structure of this invention also needs to include at least one dispersion-free second objective lens 82. Thus, when the wafer inspection device performs 3D measurement, the objective lens is switched to the first objective lens 81, and when performing hyperspectral measurement, the objective lens is switched to the second objective lens 82. Without modifying other device structures, the same device and optical path can be used to achieve both 3D measurement and hyperspectral measurement functions. The objective lens switching method can be similar to a microscope nose wheel, or it can be controlled by a motor, or any other method readily conceived by those skilled in the art.

[0044] Furthermore, the magnification of the objective lens structure directly affects the effectiveness of 3D and hyperspectral measurements. Therefore, the magnification of the first objective lens 81 and the second objective lens 82 can be set according to requirements. For example, the specific structure of the first objective lens 81 and the second objective lens 82 can be simulated and calculated using common optical simulation software, such as Zemax and CodeV, based on dispersion and magnification requirements. Another implementation method is to set multiple first objective lenses 81 and / or multiple second objective lenses 82, and switch between objectives with different magnifications as needed to achieve 3D and hyperspectral measurements at various magnifications.

[0045] In this embodiment, the second optical path is an imaging optical path used for 3D measurement and hyperspectral detection, and the imaging device used is the spectral imaging system 2. For the spectral imaging system 2, such as... Figure 2 As shown, its structure consists of a collimation system 21, a dispersion system 22, an imaging lens 23, and an image acquisition system 24 arranged sequentially. After passing through the collimation system 21, the dispersion system 22, and the imaging lens 23, the light reaches the image acquisition system 24. The image acquisition system 24 can be used as a spectral analysis device in 3D measurement and as an imaging device in hyperspectral measurement.

[0046] In this embodiment, the first and second optical paths share the same lens 5. Therefore, a beam splitting module 4 is provided in the lens 5. This allows the first and second optical paths to be partially coaxial, while the beam splitting module 4 separates the first and second optical paths, ensuring that the light source module 1 and the spectral imaging system 2 do not interfere with each other.

[0047] Furthermore, slits are respectively provided between the light source module 1 and the tube mirror 5, and between the spectral imaging system 2 and the tube mirror 5. Specifically, a first slit 31 is provided between the light source module 1 and the tube mirror 5, and a second slit 32 is provided between the spectral imaging system 2 and the tube mirror 5. Since this embodiment is a dispersive system, information about the entire surface in the object direction is obtained through scanning. The purpose of the slits is to ensure that, at a specific scanning moment, only a single line of light in the scanning direction enters the optical system for subsequent dispersive spectral analysis.

[0048] Furthermore, to achieve omnidirectional coverage of the entire surface of the sample 7 under test, the movable stage 6 used to support the sample 7 is configured to be movable to perform comprehensive scanning 3D measurements of the sample 7. In this embodiment, depending on the flatness of the surface of the sample 7, two scanning methods can be selected: when the surface of the sample 7 is not sufficiently flat, the movable stage 6 moves along a specified path, allowing the spectral imaging system 2 to perform 3D measurements at different locations on the surface of the sample 7, achieving comprehensive 3D measurements of the surface of the sample 7; or when the sample 7 is relatively flat, the spectral imaging system 2 can perform 3D measurements at intervals on the surface of the sample 7, achieving sampling-type 3D measurements of the surface of the sample 7.

[0049] Furthermore, the movable stage 6 can also be configured to have six degrees of freedom, that is, to adjust its position arbitrarily in the xyz direction and to rotate arbitrarily around the xyz axis. In this way, when the tube lens 5 and the movable stage 6 are not aligned, the attitude of the movable stage 6 can be adjusted arbitrarily to achieve alignment, thereby achieving more accurate 3D measurement and hyperspectral measurement.

[0050] Considering the potential unevenness of the surface of the sample 7, a matching autofocus system can be installed. This allows for refocusing whenever the moving stage 6 moves, ensuring the quality of 3D and hyperspectral measurements. The autofocus system can utilize an internal coaxial autofocus system based on spectral confocality, with the spectral imaging system 2 described in this embodiment acting as a spectrometer. Other autofocus systems can also be used, but will not be elaborated upon here.

[0051] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wafer inspection apparatus of hyperspectral measurement and 3D measurement, characterized in that, The device comprises: a moving platform (6) for carrying a sample (7) to be measured; a light source module (1), a first slit (31), and a tube lens (5) arranged in sequence along a first light path; the tube lens (5) comprises a spectrometer module (4) installed inside and an objective module installed on the side away from the light source module (1); the objective module comprises a first objective (81) with axial dispersion and a second objective (82) without axial dispersion, and further comprises an objective switching module for switching the first objective (81) and the second objective (82); and further comprises a tube lens (5), a second slit (32), and a spectral imaging system (2) arranged in sequence along a second light path; the spectrometer module (4) is used for separating the first light path and the second light path; the light source module (1) is used for emitting polychromatic light, which, after passing through the first slit (31) and the tube lens (5) along the first light path, is focused by the first objective (81) and vertically irradiated on the surface of the sample (7) to be measured; the first objective (81) is also used for collecting the polychromatic light reflected by the surface of the sample (7) to be measured, which, after passing through the tube lens (5) and the second slit (32) along the second light path, enters the spectral imaging system (2) to perform 3D measurement on the surface of the sample (7) to be measured; after the height measurement of the surface of the sample (7) to be measured is completed, the objective is switched to the second objective (82), and the spectral imaging system (2) receives the imaging light of the sample (7) to be measured coming along the second light path to perform hyperspectral measurement on the surface of the sample (7) to be measured; further comprising a control module for controlling the moving platform (6) to move according to a specified path so that the spectral imaging system (2) performs 3D measurement on different parts of the surface of the sample (7) to be measured, thereby realizing comprehensive 3D measurement of the surface of the sample (2) to be measured; or, when the sample (7) to be measured is flat, the spectral imaging system (2) performs 3D measurement on the surface of the sample (7) to be measured at intervals of a certain distance, thereby realizing sampling style 3D measurement of the surface of the sample (2) to be measured.

2. The wafer detection device for hyperspectral measurement and 3D measurement according to claim 1, wherein: the first slit (31) and the second slit (32) are located at the image plane of the tube lens (5).

3. The wafer detection device for hyperspectral measurement and 3D measurement according to claim 1, wherein: the spectral imaging system (2) comprises a dispersion system (22), an imaging lens (23), and an image acquisition system (24) arranged in sequence.

4. The wafer detection device for hyperspectral measurement and 3D measurement according to claim 3, wherein: the spectral imaging system (2) further comprises a collimation system (21) arranged at the front end of the dispersion system (22).

5. The wafer detection device for hyperspectral measurement and 3D measurement according to claim 3, wherein: the dispersion system (22) is a grating.

6. The wafer detection device for hyperspectral measurement and 3D measurement according to claim 1, wherein: The imaging light of the surface of the sample (7) is derived from the self-luminous or other illuminating light of the sample (7).

7. The wafer detection device of claim 1, wherein: The objective lens switching module is a nose wheel or a linear motor.

8. The wafer detection device of claim 1, wherein: The first objective lens (81) and the second objective lens (82) select magnification according to test requirements.

9. A wafer inspection method of hyperspectral measurement and 3D measurement, characterized by, The wafer detection device of any one of claims 1-8 is applied to realize, comprising: Switching the objective lens of the tube lens (5) to the first objective lens (81), turning on the light source system (1), and generating complex light to irradiate the surface of the sample (7) through the first slit (31) and the tube lens (5); The spectral imaging system (2) receives the complex light reflected by the surface of the sample (7), and performs 3D measurement on the surface of the sample (7); Switching the objective lens of the tube lens (5) to the second objective lens (82), and the spectral imaging system (2) receives the imaging light of the surface of the sample (7), and performs hyperspectral measurement on the surface of the sample (7).

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