Wafer surface defect detection device

Abstract

The invention relates to a wafer surface defect detection device, and belongs to the field of wafer surface defect detection. The wafer surface defect detection device comprises a first photoelectric conversion part and a stray light elimination part, wherein the first photoelectric conversion part is arranged to generate a first electric signal in response to scattered light in a first angle range; the stray light eliminating part is arranged in front of the first photoelectric conversion part along the light transmission direction, the stray light eliminating part is arranged to eliminate stray light signals generated by an optical machine, and the intensity of the stray light signals is greater than that of background signals caused by wafer surface roughness. The stray light eliminating component which is uniformly designed is placed in front of the first photoelectric conversion component, stray light signals generated by an optical machine can be eliminated, weak scattering signals corresponding to smaller particles are collected into the first photoelectric conversion component, one-to-one correspondence of a polaroid and a diaphragm in the spatial position does not need to be established, the overall mechanical structure is simple, and the cost is low. And the mechanical design and adjustment requirements are reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of wafer surface defect detection, and in particular to a wafer surface defect detection device. Background Art

[0002] The integrated circuit industry is the core pillar industry supporting the national economy and high-tech development, and is an important symbol to measure a country's modernization process and comprehensive national strength. With the development of lithography exposure technology, which allows for the formation of finer circuit structures in integrated circuits, measurement systems / devices capable of detecting tinier defects or particles in the wafer production line have become increasingly important. With the development of advanced lithography nodes, the requirements for detecting defects on bare wafers have become increasingly stringent; wafer defects can include defects such as wafer particle contamination, crystal defects, surface roughness, and scratches during the polishing process. Among them, if the surface roughness of the wafer under test is very large, it will result in a high proportion of stray light. Particle defects account for 75% of the chip production scrap rate. In addition to detecting particles, a non-destructive wafer surface defect measurement system also needs to be able to detect the non-uniformity of the wafer surface, the inconsistency of the wafer film thickness, and the crystal defects on the surface of single-crystalline wafers. For this reason, each step of chip production is usually monitored to detect problems as early as possible and avoid scrapping; among them, the detection of wafer surface particle contamination is an effective means for monitoring the introduction of defects in multiple production steps of the chip.

[0003] For non-destructive measurement devices for wafer surface defects, in order to improve the defect signal and suppress the noise signal, in related technologies, a method of combining a polarizer and a diaphragm is respectively set in wide and narrow channels to improve the signal-to-noise ratio of the defect signal. For different types of defects, by modulating the incident polarization state P and polarization state S, the corresponding polarization state is extracted in the wide and narrow collection channels, and the light field amplitude is modulated in this polarization state to improve the signal-to-noise ratio of different types of defect signals. In addition, different-sized particle defects are classified through wide and narrow channels. For small particle sizes, larger particle sizes are more sensitive to the polarization state. The wide channel collects the scattering signals of smaller-sized defects, and the design of the polarizer is also more complex. Therefore, a series of methods combining polarization states and diaphragm shapes are designed and applied in the wide channel.

[0004] In the above technical solution, since the polarization state distributions of the wafer defect signal and the background signal are different, a special design combining a polarizer and a diaphragm is adopted to extract the defect signal and suppress the background signal. Therefore, for different types of wafers and different types of defects, the polarizer and the diaphragm need to be designed separately, and a one-to-one correspondence between the polarizer and the diaphragm should be achieved, resulting in a complex mechanical structure. In addition, due to the light intensity distributions of different polarization states, a special design of the diaphragm is required to extract the defect signal from the background signal specifically. The spatial distribution and angular distribution of the polarizer and the diaphragm need to correspond one by one. Otherwise, the extraction of the defect signal will be inhibited. Therefore, high requirements are imposed on the mechanical design and alignment accuracy of the polarizer and the diaphragm. Summary of the Invention

[0005] To solve the above technical problems or at least partially solve the above technical problems, the present disclosure provides a wafer surface defect detection device.

[0006] The present disclosure provides a wafer surface defect detection device, including:

[0007] A first optoelectronic conversion component configured to generate a first electrical signal in response to scattered light within a first angular range;

[0008] A stray light elimination component disposed in front of the first optoelectronic conversion component along the light transmission direction; the stray light elimination component is configured to eliminate the stray light signal generated by the optical machine, and the intensity of the stray light signal is greater than the intensity of the background signal caused by the surface roughness of the wafer.

[0009] The technical solution provided by the present disclosure has the following advantages compared with the prior art:

[0010] In the wafer surface defect detection device provided by the present disclosure, by placing a uniformly designed stray light elimination component in front of the first optoelectronic conversion component, the stray light signal generated by the optical machine can be eliminated, and the weak scattering signals corresponding to smaller particles can be collected into the first optoelectronic conversion component. There is no need to establish a one-to-one correspondence between the spatial positions of the polarizer and the diaphragm, and the overall mechanical structure is simple, reducing the mechanical design and alignment requirements. Brief Description of the Drawings

[0011] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present disclosure and used together with the specification to explain the principles of the present disclosure.

[0012] To more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0013] Figure 1 Structural schematic diagram of a wafer surface defect detection device provided by an embodiment of the present disclosure;

[0014] Figure 2 Irradiance distribution diagram provided by an embodiment of the present disclosure;

[0015] Figure 3 Schematic diagram for comparing signal-to-noise ratios provided by an embodiment of the present disclosure;

[0016] Figure 4 Another irradiance distribution diagram provided by an embodiment of the present disclosure;

[0017] Figure 5 Another schematic diagram for comparing signal-to-noise ratios provided by an embodiment of the present disclosure;

[0018] Figure 6 Yet another irradiance distribution diagram provided by an embodiment of the present disclosure;

[0019] Figure 7 Yet another schematic diagram for comparing signal-to-noise ratios provided by an embodiment of the present disclosure.

[0020] Among them, 10 is a wafer surface defect detection device; 11 is a first photoelectric conversion component; 12 is a stray light elimination component; 13 is a first filter component; 14 is a polarizer; 16 is an ellipsoidal reflector; 17 is an illumination light source; 171 is a first illumination light source; 172 is a second illumination light source; 21 is a second photoelectric conversion component; 22 is a second lens group; 23 is a reflection component; 24 is a second filter component. Detailed implementation manners

[0021] In order to more clearly understand the above objects, features and advantages of the present disclosure, the solutions of the present disclosure will be further described below. It should be noted that, without conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other.

[0022] Many specific details are set forth in the following description in order to fully understand the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present disclosure, rather than all of the embodiments.

[0023] In the wafer surface defect detection device provided by the embodiments of the present disclosure, the main setting is for the main inspection optical imaging system. Specifically, considering the case where the wafer background signal is also stray light, that is, the stray light signal generated by the optical machine, for the particle signal defect, a unified stray light elimination component, such as a stray light diaphragm, can be used to filter out the stray light background signal. This not only simplifies the mechanical structure and reduces the complexity of mechanical design and alignment, but also avoids introducing new defects and impurities due to actions such as the switching of electric devices during the use of the equipment / device, ensuring relatively high detection accuracy.

[0024] In some implementation manners, based on the wafer surface defect detection device provided by the embodiments of the present disclosure, mainly the main inspection optical imaging system in the device can use a unified stray light diaphragm to suppress the background signal and enhance the scattering signal of the particles; further, for wafers of different types, due to the difference in the distribution of their background scattering signals, by adjusting the opening size of the stray light diaphragm, background noise suppression can be flexibly achieved. Thus, for particles of different size ranges on the wafer surface, by using the stray light diaphragm to suppress the background signal and obtain a higher signal-to-noise ratio of the particles, the detection sensitivity of the particles can be improved.

[0025] Next, with reference to the accompanying drawings, an exemplary description will be given of the wafer surface defect detection device provided by the embodiments of the present disclosure.

[0026] Exemplarily, Figure 1 is a schematic structural diagram of a wafer surface defect detection device provided by the embodiments of the present disclosure. Referring to Figure 1 , the wafer surface defect detection device 10 may include: a first photoelectric conversion component 11 and a stray light elimination component 12.

[0027] Among them, the first photoelectric conversion component 11 is configured to generate a first electrical signal in response to the scattered light within a first angular range; exemplarily, the first photoelectric conversion component 11 may include a photomultiplier tube (PMT), or may also include other structural components with photoelectric conversion functions known to those skilled in the art, which is not limited herein. The first photoelectric conversion component 11 converts the received scattered light signal into a first electrical signal for subsequent data processing based on the electrical signal to determine the defects on the wafer surface.

[0028] In some embodiments, the first angular range may be 15° - 83°, and this first angular range includes 15°, 83°, and any angle or angular range between 15° and 83°. Based on this, the first photoelectric conversion component 11 is a photoelectric conversion component for wide-channel collection.

[0029] Exemplarily, the first optoelectronic conversion component 11 can be a wide-channel PMT, which is applied to the wide-channel collection part of the imaging system of the wafer surface defect detection device 10 and can respond to the scattered light with a collection angle of 15° - 83° for small particles, so as to realize the detection of small particles on the wafer surface.

[0030] Among them, the stray light elimination component 12 can be arranged in front of the first optoelectronic conversion component 11 along the light transmission direction; the stray light elimination component 12 is set to eliminate the stray light signal generated by the optical machine, and the intensity of the stray light signal is greater than the intensity of the background signal caused by the surface roughness RMS (Root Means Square Error) of the wafer.

[0031] Specifically, the stray light signal generated by the optical machine is background stray light and belongs to noise signal. At the stray light elimination component 12, the stray light signal is distributed in a certain pattern. By setting the stray light elimination component 12, the stray light signal can be filtered out, thereby reducing the noise signal and improving the signal-to-noise ratio.

[0032] In the related technical solutions in the background art, the diaphragm is directed at the particle signal, filters out the background signal, and enhances the particle signal. Due to different polarization state distributions, their light intensity distributions are also different, and it is necessary to achieve a one-to-one correspondence between the polarization state and the light intensity distribution.

[0033] In the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, what has an important impact on the signal-to-noise ratio of the particle signal is the stray light of the optical machine system, that is, the stray light signal generated by the optical machine, rather than the background signal caused by the surface roughness of the wafer, that is, the signal intensity of the stray light generated by the optical machine is higher than the intensity of the background signal caused by the surface roughness of the wafer.

[0034] In view of this, in the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, by placing a uniformly designed stray light elimination component 12 in front of the first optoelectronic conversion component 11 in the wide-channel collection part, smaller particle signals can be collected into the optoelectronic conversion component of the wide channel. Especially for smaller particles, their scattered signals are weaker, which is beneficial to improving the signal-to-noise ratio; in addition, it is not necessary to establish a one-to-one correspondence between the spatial positions of the polarizer and the diaphragm. For various types of particle defects, the requirements for the polarization state distribution are low, that is, the one-to-one correspondence between the spatial distribution of the light field polarization state and the spatial position and angular position of the light field amplitude distribution. It has applicability to particles in a wider size range, the mechanical structure is simple, and the mechanical design and adjustment difficulty are low; moreover, during the use of the device, it is not necessary to switch repeatedly, avoiding the introduction of impurity particles and improving the detection accuracy.

[0035] In some embodiments, the stray light elimination component 12 includes a stray light diaphragm; the center of the stray light diaphragm is opaque and can transmit light within the angular range of 15° - 83°, facilitating the detection of small-sized particles.

[0036] Specifically, the stray light diaphragm is easy to process and prepare, and has the advantage of low alignment requirements.

[0037] In the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, by setting a unified stray light diaphragm, the stray light signal of the optical machine system can be filtered, and the signal-to-noise ratio of the particle signal can be enhanced. It is distinguished from the related technical solutions in enhancing the particle signal by filtering the background signal caused by the surface roughness of the wafer.

[0038] In some embodiments, in the wafer surface defect detection device 10, the light transmission size / aperture of the stray light diaphragm is adjustable.

[0039] Among them, the light transmission size / aperture of the stray light diaphragm can also be referred to as the opening of the stray light diaphragm. By setting the opening size, the background scattering signal caused by different surface roughnesses of the wafer can be filtered, and the signal-to-noise ratio can be improved.

[0040] In the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, by setting the aperture of the stray light diaphragm in the wide-channel collection part to be adjustable, the background stray light caused by different surface roughnesses of the wafer can be filtered, and the signal-to-noise ratio of small particles in the wide channel can be improved. The stray light diaphragm in the wide-channel collection part does not need to establish a one-to-one correspondence with the polarization filter. Through the uniformly set aperture and shape, and for the change in the spatial distribution of the polarization state of the scattered light caused by the difference in the defect morphology or particle orientation, that is, the particle scattering signal and background signal with any polarization state distribution, using this stray light diaphragm, the background scattering signal caused by different surface roughnesses of the wafer can be filtered.

[0041] In some embodiments, in the wafer surface defect detection device 10, the stray light diaphragm is set as a concentric ring structure, and the ring structure includes an opaque central circle; and the radius of the central circle is adjustable.

[0042] Among them, the center of the ring structure is an opaque circle, and the edge is a light-transmitting ring. Based on this, by adjusting the radius of the opaque central circle, the inner diameter of the light-transmitting ring can be correspondingly adjusted, thereby realizing the adjustment of the aperture of the stray light diaphragm. Moreover, the structure of the stray light diaphragm is simple, and the aperture adjustment method of the stray light diaphragm is simple.

[0043] In some embodiments, in the wafer surface defect detection device 10, the light transmission size of the stray light diaphragm is adjusted based on the surface roughness of the wafer and / or the surface particle size of the wafer.

[0044] Specifically, before the detection, the surface roughness and surface particle size of the wafer are known, and different stray light apertures are set for different surface roughnesses, or different stray light apertures are set for different surface particle sizes, or different stray light apertures are set in combination with different surface roughnesses and different surface particle sizes, so that by flexibly adjusting the aperture of the stray light aperture, the background stray light caused by the surface roughness of the wafer can be filtered out, and the signal-to-noise ratio of small particles in a wide channel can be improved. It can be understood that the background stray light is caused by the optical-mechanical system, and at the stray light aperture, its light intensity distribution has a certain regularity, so by adjusting the aperture of the stray light aperture, the background stray light can be filtered out.

[0045] In some embodiments, based on the above embodiments, the wafer surface defect detection device 10 may further include a first filter component 13 and a polarizer 14 .

[0046] The first filter component 13 is located between the stray light elimination component 12 and the first photoelectric conversion component 11; illustratively, the first filter component 13 may be a wide channel filter OD.

[0047] The polarizer 14 is located between the first filter component 13 and the stray light elimination component 12; illustratively, the polarizer 14 may be a wide-channel polarizer.

[0048] In the wafer surface defect detection device 10 provided by the embodiment of the present disclosure, the wide-channel polarizer and the wide-channel filter do not need to establish a one-to-one correspondence with the aperture for different polarization states, the mechanical structure is simple, and the mechanical design and assembly difficulty are relatively low.

[0049] In some embodiments, the wafer surface defect detection device 10 may further include a first lens group (not shown in the figure) and an ellipsoidal reflector 16 .

[0050] The first lens group is located between the polarizer 14 and the stray light elimination component 12; the first lens group is configured to map the object surface light spot associated with the wafer to the detection surface of the first photoelectric conversion component 11. Exemplarily, the first lens group is a wide channel lens group. The ellipsoidal reflector 16 is arranged in front of the stray light elimination component 12 along the light transmission direction; the ellipsoidal reflector 16 maps the object surface light spot associated with the wafer through the stray light elimination component 12 to the object surface of the first lens group based on two mutually mapped focal points.

[0051] In the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, in the wide-channel collection part of the imaging system, scattered light signals with a collection angle of 15°-83° associated with small-sized particles are mainly collected. The wide-channel collection part may include an ellipsoidal mirror 16, a stray light diaphragm, a wide-channel filter, and a wide-channel PMT. Among them, the wide-channel collection part can establish an object-image relationship between the object plane illumination spot associated with the wafer and the detection surface of the wide-channel PMT. Specifically, the two mutually mapped focal points of the ellipsoidal mirror 16 are used to establish an object-image mapping, and then the object plane spot and the detection surface of the wide-channel PMT are established with an object-image mapping through the wide-channel lens group, so that the wide-channel PMT can receive the image plane spot of the wafer, facilitating imaging.

[0052] In some embodiments, the wafer surface defect detection device 10 may further include an illumination light source 17; the illumination light source 17 is configured to provide light for illuminating the wafer to form a spot associated with the wafer.

[0053] Among them, the illumination light source 17 is used to illuminate the surface of the wafer, so as to perform optical imaging detection on the surface of the wafer by using the collection part (including the wide-channel collection part described above and the narrow-channel collection part described below), and further realize the detection of wafer surface defects.

[0054] In some embodiments, in the wafer surface defect detection device 10, the illumination light source 17 includes a first illumination light source 171 and a second illumination light source 172; the first illumination light source 171 is configured to vertically illuminate the wafer; the second illumination light source 172 is configured to obliquely illuminate the wafer.

[0055] Among them, the optical axis of the first illumination light source 171 may coincide with the optical axis of the above-mentioned wide-channel collection part to vertically illuminate the wafer.

[0056] Among them, there is an included angle between the optical axis of the second illumination light source 172 and the optical axis of the above-mentioned wide-channel collection part to obliquely illuminate the wafer.

[0057] In the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, by setting the illumination light source 17 to include the first illumination light source 171 that vertically illuminates the wafer and the second illumination light source 172 that obliquely illuminates the wafer, when performing wafer surface defect detection, the light source can be flexibly applied based on the detection requirements, and different wafer surface defect detection requirements can be flexibly met.

[0058] In some embodiments, in the wafer surface defect detection device 10, the centers of the ellipsoidal mirror 16, the stray light elimination component 12, the first lens group, the polarizer 14, the first filter component 13, and the first photoelectric conversion component 11 are all located on the same first straight line.

[0059] With such a setting, in the wafer surface defect detection device 10, the optical path of the wide-channel collection part is relatively simple, and the mechanical design and alignment difficulty are relatively low.

[0060] In other implementation manners, the components of the wide-channel collection part can also be arranged in other spatial position relationships, which are not limited herein.

[0061] In some embodiments, the wafer surface defect detection device 10 may further include a second photoelectric conversion component 21 and a second lens group 22.

[0062] Among them, the second photoelectric conversion component 21 is configured to generate a second electrical signal in response to the scattered light within a second angle range; by way of example, the second photoelectric conversion component 21 may include a photomultiplier tube (PMT), or may also include other structural components with photoelectric conversion functions known to those skilled in the art, which are not limited herein. The second photoelectric conversion component 21 converts the received scattered light signal into a second electrical signal, so as to perform data processing based on the electrical signal subsequently to determine the defects on the wafer surface.

[0063] Among them, the angles within the second angle range are all smaller than the angles within the first angle range; the scattered light within the second angle range corresponds to the scattered light formed by surface particles with larger sizes.

[0064] In some embodiments, the second angle range may be 0° - 10°, and this second angle range includes 0°, 10°, and any angle or angle range between 0° and 10°. Based on this, the second photoelectric conversion component 21 is the photoelectric conversion component of the narrow-channel collection part.

[0065] By way of example, the second photoelectric conversion component 21 may be a narrow-channel PMT, which is applied to the narrow-channel collection part of the imaging system of the wafer surface defect detection device 10 and can respond to the scattered light with a collection angle of 0° - 10° for large particles, so as to realize the detection of large particles on the wafer surface.

[0066] Among them, the second lens group 22 is arranged in front of the second photoelectric conversion component 21 along the light transmission direction; the second lens group 22 is configured to map the object plane light spot associated with the wafer to the detection surface of the second photoelectric conversion component 21. By way of example, the second lens group 22 is a narrow-channel lens group. By way of example, the second lens group 22 may include two lens groups or other numbers of lens groups, which are not limited herein.

[0067] In the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, in the narrow-channel collection part of the imaging system, scattered light signals with a collection angle of 0° - 10° associated with large-sized particles are mainly collected. The narrow-channel collection part may include a narrow-channel lens group and a narrow-channel PMT. The narrow-channel lens group can establish an object-image mapping between the object-plane light spot associated with the wafer and the detection plane of the narrow-channel PMT, so that the narrow-channel PMT can receive the image-plane light spot of the wafer, facilitating imaging.

[0068] In some embodiments, the wafer surface defect detection device 10 may further include a reflection component 23, and the reflection component 23 is located between the second lens group 22 and the second photoelectric conversion component 21; the reflection component 23 is arranged to reflect the light after passing through the second lens group 22 to the second photoelectric conversion component 21.

[0069] Specifically, the reflection component 23 can reflect the received light. Specifically, the light after passing through the second lens group 22 irradiates the reflection component 23 and is reflected by the reflection component 23; the light after being reflected by the reflection component 23 irradiates the second photoelectric conversion component 21, so that the optical path of the narrow-channel collection part can be set non-linearly, enabling the narrow-channel PMT and the wide-channel PMT to be staggered in spatial orientation, such that the mechanical structure does not affect the detection light, ensuring relatively high detection accuracy.

[0070] In some embodiments, in the wafer surface defect detection device 10, the center of the reflection component 23 and the center of the second lens group 22 are located on a first straight line.

[0071] Specifically, the second lens group 22 and the reflection component 23 of the narrow-channel collection part can be coaxially arranged with the wide-channel collection part, so that the free space in the wide-channel collection part that is not occupied by scattered light associated with small-sized particles can be utilized by the narrow-channel collection part, improving the space utilization rate and reducing the overall volume of the imaging system in the wafer surface defect detection device 10.

[0072] In some embodiments, in the wafer surface defect detection device 10, the center of the reflection component 23 and the center of the second photoelectric conversion component 21 are located on the same second straight line; wherein, the second straight line intersects with the first straight line. Exemplarily, the second straight line is perpendicular to the first straight line.

[0073] Among them, the reflection component 23 is located on both the first straight line and the second straight line, and the center of the second photoelectric conversion component 21 is not on the first straight line but only on the second straight line, that is, the second photoelectric conversion component 21 is arranged in the space outside the wide-channel collection part.

[0074] With such a setting, the second photoelectric conversion component 21 and the first photoelectric conversion component 11 are spatially separated, and the mechanical structure does not affect the transmission of optical signals, thereby ensuring the imaging accuracy on the wafer surface and ensuring relatively high detection accuracy.

[0075] In some embodiments, in the wafer surface defect detection device 10, the reflection component 23 includes a reflector; the reflection surface of the reflector intersects the first straight line at a 45-degree angle and intersects the second straight line at a 45-degree angle.

[0076] With such a setting, the second straight line is perpendicular to the first straight line, which is convenient for arranging the components of the wide-channel collection part and the narrow-channel collection part in the imaging system.

[0077] In some embodiments, in the wafer surface defect detection device 10, the reflection component 23 is disposed between the ellipsoidal reflector 16 and the stray light elimination component 12; wherein, the light after being reflected by the ellipsoidal reflector 16 passes around the reflection component 23 and then is incident on the stray light elimination component 12.

[0078] Specifically, the light incident on the stray light elimination component 12 after being reflected by the ellipsoidal reflector 16 does not occupy the axis of the ellipsoidal reflector 16 and the stray light elimination component 12 and the nearby part of the space. The reflection component 23 can be disposed in the free space not occupied by the light in this part, thereby improving the space utilization rate and facilitating the bending and collection of the light in the narrow-channel collection part.

[0079] In some embodiments, in the wafer surface defect detection device 10, the second lens group 22 is disposed inside the ellipsoidal reflector 16; wherein, the second lens group 22 is configured to receive the scattered light within the second angle range, and the ellipsoidal reflector 16 is configured to receive the scattered light within the first angle range.

[0080] Specifically, the light incident on the ellipsoidal reflector 16 and the light after being reflected by the ellipsoidal reflector do not occupy the axis of the ellipsoidal reflector and the nearby part of the space. The second lens group 22 can be disposed in the free space not occupied by the light in this part, thereby improving the space utilization rate and facilitating the collection of the light in the narrow-channel collection part.

[0081] In some embodiments, the wafer surface defect detection device 10 may further include a second filter component 24, and the second filter component 24 is located between the reflection component 23 and the second photoelectric conversion component 21. Exemplarily, the second filter part 24 can be a narrow-channel filter.

[0082] In the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, the narrow-channel collection part of the imaging system may include a narrow-channel lens group, a reflector, a narrow-channel filter, and a narrow-channel PMT. An object-image mapping is established between the object plane light spot associated with the wafer and the detection surface of the narrow-channel PMT through the narrow-channel lens group, so as to realize the detection of larger-sized particles.

[0083] When the wafer surface defect detection device 10 provided by the embodiments of the present disclosure is used for wafer detection, based on the start of scanning, the wafer to be detected is moved under the ellipsoidal reflector, and the laser shutter is moved out, so that the illumination light source emits laser light, and the laser light is incident on the wafer to be detected through the two paths of inclined illumination and vertical illumination. The scattered light emitted by the particle defects on the wafer, the scattered light with a large divergence angle passes through the wide-channel collection part and is incident on the wide-channel PMT; the small-angle scattered light passes through the narrow-channel collection part and is incident on the narrow-channel PMT, thereby realizing the imaging of the wafer surface.

[0084] In the wafer surface defect detection device 10 provided by the embodiments of the present disclosure, on the basis of the wide and narrow channel main detection optical system, by setting a stray light diaphragm in the wide-channel collection part, the signal-to-noise ratio of small-sized particles relative to the background noise signal on the wafer surface can be improved. Among them, the wide-channel collection part also includes an ellipsoidal reflector, a wide-channel lens group, and a wide-channel PMT; based on the mutual mapping relationship between the first focal point and the second focal point of the ellipsoidal reflector, the ellipsoidal reflector maps the wafer object plane light spot located at the first focal point to the second focal point. On this basis, the stray light diaphragm is placed after the second focal point of the ellipsoidal reflector. By adjusting the aperture of the stray light diaphragm, the background stray light caused by the surface roughness of the wafer can be filtered, and the signal-to-noise ratio of small particles in the wide channel can be improved. The stray light diaphragm does not need to establish a one-to-one correspondence with the polarization filter. Through the uniformly set aperture and shape, and for the change in the spatial distribution of the polarization state of the scattered light caused by the difference in the defect morphology or the particle orientation, that is, the particle scattering signals and background signals with any polarization state distribution, the stray light diaphragm can filter the background scattering signals caused by different surface roughness RMS (Root Means Square Error) of the wafer surface. By setting the aperture of the stray light diaphragm to be continuously adjustable, particles in the particle diameter range of 30-70 nm can be detected, and the background signals caused by the surface roughness of the wafer in the range of 0.1 nm to 50 nm RMS can be filtered, and the signal-to-noise ratio of the particle signals can be improved.

[0085] Exemplarily, Figure 2 is an irradiance distribution diagram provided by the embodiments of the present disclosure, Figure 3A schematic diagram of signal-to-noise ratio comparison provided by an embodiment of the present disclosure shows the detection imaging results and the signal-to-noise ratio improvement effect of a detection device with a stray light diaphragm provided in a wide channel part on a wafer with a surface roughness of 1 nm RMS and a surface particle size of 60 nm. Figure 2 In it, the abscissa is the X-axis, the ordinate is the Y-axis, and it is the irradiance distribution of the scattered light received by the wide channel. The legend is radiation irradiance, count represents count, and the unit is W / mm 2 . Figure 3 In it, the ordinate is irradiance, the abscissa is X = 0, the corresponding Y; and X corresponding to Y = 0, position represents position. Refer to Figure 2 and Figure 3 , for PSL (Polystyrene) particles with a diameter of 60 nm, the target signal of the particles is defined by assigning the three-dimensional spatial distribution of the particle BRDF (Bidirectional Reflectance Distribution Function) to the wafer surface. The Lambert distribution is adopted to approximate the BRDF of 60 nm PSL. The two-dimensional roughness of the wafer surface is directly defined by directly assigning the surface roughness RMS. The surface roughness of the wafer is 1 nm. By adjusting the aperture of the stray light diaphragm to 20 mm, for PSL particles with a diameter of 60 nm, its signal-to-noise ratio (Signal / noise, S / N) is 12.83, and the improvement effect of the wide channel is obvious.

[0086] Exemplarily, Figure 4 Another irradiance distribution diagram provided by an embodiment of the present disclosure, Figure 5 Another schematic diagram of signal-to-noise ratio comparison provided by an embodiment of the present disclosure shows the detection imaging results and the signal-to-noise ratio improvement effect of a detection device with a stray light diaphragm provided in the wide channel part on a wafer with a surface roughness of 10 nm RMS and a surface particle size of 50 nm. Refer to Figure 4 and Figure 5 , for PSL particles with a diameter of 50 nm, the BRDF of the PSL particles in three-dimensional space is also approximated by the Lambert distribution. The two-dimensional roughness of the wafer surface is 10 nm RMS. By adjusting the aperture of the stray light diaphragm to 18 mm, the signal-to-noise ratio S / N of the particles is 4.9.

[0087] Exemplarily, Figure 6 Another irradiance distribution diagram provided by an embodiment of the present disclosure, Figure 7 Another schematic diagram of signal-to-noise ratio comparison provided by an embodiment of the present disclosure shows the detection imaging results and the signal-to-noise ratio improvement effect of a detection device with a stray light diaphragm provided in the wide channel part on a wafer with a surface roughness of 70 nm RMS and a surface particle size of 40 nm. Refer to Figure 6 andFigure 7 For PSL particles with a diameter of 40 nm, the BRDF in the three-dimensional space of the PSL particles is also approximated by the Lambert distribution. The two-dimensional surface roughness of the wafer is 70 nm RMS. By adjusting the aperture of the stray light diaphragm to 22 mm, the particle signal-to-noise ratio S / N is 6.2.

[0088] In other embodiments, the wafer surface defect detection device 10 provided by the embodiments of the present disclosure can also detect wafers with other roughnesses and particle sizes.

[0089] In other embodiments, the wafer surface defect detection device 10 may further include other structural components, which will not be elaborated or limited herein.

[0090] It should be noted that in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0091] The above are only specific embodiments of the present disclosure, enabling those skilled in the art to understand or implement the present disclosure. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A wafer surface defect detection device, characterized in that: include: a first photoelectric conversion component configured to generate a first electrical signal in response to scattered light within a first angular range; A stray light elimination component is arranged in front of the first photoelectric conversion component along the light transmission direction; the stray light elimination component is arranged to eliminate the stray light signal generated by the optical machine, and the intensity of the stray light signal is greater than the intensity of the background signal caused by the surface roughness of the wafer.

2. The wafer surface defect detection device according to claim 1, characterized in that: The stray light elimination component includes a stray light stop; The center of the stray light stop is light-proof.

3. The wafer surface defect detection device according to claim 2, characterized in that: The light transmission size of the stray light aperture is adjustable.

4. The wafer surface defect detection device according to claim 3, characterized in that: The stray light aperture is configured as a concentric ring structure, wherein the ring structure includes an opaque central circle; The radius of the center circle is adjustable.

5. The wafer surface defect detection device according to claim 3, characterized in that: The light transmission size of the stray light aperture is adjusted based on the surface roughness of the wafer and / or the surface particle size of the wafer.

6. The wafer surface defect detection device according to claim 1, characterized in that: The first angle ranges from 15° to 83°.

7. The wafer surface defect detection device according to any one of claims 1 to 6, characterized in that: Also includes: a first light filtering component, located between the stray light eliminating component and the first photoelectric conversion component; The polarizing plate is located between the first filter component and the stray light eliminating component.

8. The wafer surface defect detection device according to claim 7, characterized in that: Also includes: A first lens group is located between the polarizing plate and the stray light eliminating component; The first lens group is configured to map the object plane spot associated with the wafer to the detection surface of the first photoelectric conversion component; An ellipsoidal reflector is arranged in front of the stray light elimination component along the light transmission direction; the ellipsoidal reflector maps the object plane spot associated with the wafer to the object plane of the first lens group through the stray light elimination component based on two mutually mapped focusing points.

9. The wafer surface defect detection device according to claim 8, characterized in that: Also includes: The illumination light source is configured to provide light for illuminating the wafer to form a light spot associated with the wafer.

10. The wafer surface defect detection device according to claim 9, characterized in that: The illumination light source comprises a first illumination light source and a second illumination light source; The first illumination light source is configured to vertically illuminate the wafer; The second illumination light source is configured to illuminate the wafer obliquely.

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