A semiconductor inspection apparatus

Abstract

The present application relates to the technical field of optical detection, and particularly relates to a semiconductor detection device, which comprises a re-inspection light source for emitting re-inspection light, a bright field light source for emitting bright field light, and a dark field light source for emitting dark field light, the re-inspection light, the bright field light, and the dark field light are guided to irradiate the wafer surface respectively, the re-inspection light is reflected by the wafer to form re-inspection signal light, the bright field light is reflected by the wafer to form bright field signal light, and the dark field light is scattered by the wafer to form dark field signal light; an optical separation element is used for collecting the bright field signal light, the dark field signal light, and the re-inspection signal light and spatially separating them, so that the dark field signal light, the bright field signal light, and the re-inspection signal light are emitted to different transmission paths to be imaged respectively; wherein the dark field illumination spot formed by the dark field light on the wafer surface, the bright field illumination spot formed by the bright field light on the wafer surface, and the re-inspection illumination spot formed by the re-inspection light on the wafer surface do not overlap with each other. The present application is at least beneficial to improve the detection speed and the detection precision of wafer defect detection.

Description

Technical Field

[0001] This invention belongs to the field of optical detection technology, and in particular relates to a semiconductor detection device. Background Technology

[0002] In the semiconductor chip manufacturing process, unavoidable contamination and manufacturing errors are major causes of semiconductor chip failure. Therefore, during semiconductor chip manufacturing, defect detection on the wafers used to produce semiconductor chips can improve yield and thus obtain higher profits. Among existing wafer defect detection equipment, optical imaging-based defect detection methods have the advantages of rapid and non-contact detection, making them the most commonly used method for wafer defect detection.

[0003] For optical imaging-based wafer defect detection, detection speed and accuracy are crucial indicators. Detection accuracy refers to the smallest detectable defect size. Understanding this, increasing magnification achieves lower optical resolution and improves accuracy, but simultaneously reduces detection speed. To achieve rapid and high-precision defect detection, wafer defect detection typically includes two steps: initial inspection and re-inspection. Initial inspection involves scanning a designated area at low magnification to obtain preliminary information about the defect location and morphology. Re-inspection moves the defect location to a re-inspection probe and uses high magnification for imaging, obtaining a more precise defect image and enabling more detailed analysis of the defect.

[0004] However, the detection accuracy and speed of current optical imaging-based wafer defect detection need to be improved. Summary of the Invention

[0005] In view of this, the present invention aims to provide a semiconductor inspection device that at least helps to improve the detection speed and accuracy of wafer defect detection.

[0006] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0007] This invention provides a semiconductor testing device, comprising: a re-examination light source emitting re-examination light, a bright field light source emitting bright field light, and a dark field light source emitting dark field light. The re-examination light, bright field light, and dark field light are respectively guided to illuminate the surface of a wafer. The re-examination light is reflected by the wafer to form a re-examination signal light, the bright field light is reflected by the wafer to form a bright field signal light, and the dark field light is scattered by the wafer to form a dark field signal light. An optical separation element is used to collect the bright field signal light, dark field signal light, and re-examination signal light and spatially separate them, so that the dark field signal light, bright field signal light, and re-examination signal light are emitted to different transmission paths for imaging respectively. The dark field illumination spot formed by the dark field light on the wafer surface, the bright field illumination spot formed by the bright field light on the wafer surface, and the re-examination illumination spot formed by the re-examination light on the wafer surface do not overlap.

[0008] Furthermore, the distance between the two with the largest spacing among the dark field illumination spot, the bright field illumination spot, and the re-inspection illumination spot is greater than a first preset value and less than a second preset value. The first preset value is in the range of 0.1 mm to 0.5 mm, and the second preset value is in the range of 1 mm to 3 mm.

[0009] Furthermore, the re-inspection illumination spot is located between the dark field illumination spot and the bright field illumination spot, and the distance from the dark field illumination spot to the re-inspection illumination spot is the same as or different from the distance from the bright field illumination spot to the re-inspection illumination spot.

[0010] Furthermore, the bright-field signal light, dark-field signal light, and re-examination signal light reach the optical separation element along a common optical path. The optical separation element has a through hole, a first reflective surface, and a second reflective surface. The bright-field signal light incident on the optical separation element is reflected by the first reflective surface and then emitted to the first transmission path. The dark-field signal light incident on the optical separation element is reflected by the second reflective surface and then emitted to the second transmission path. The re-examination signal light incident on the optical separation element passes through the through hole and is emitted to the third transmission path.

[0011] Furthermore, the semiconductor testing equipment also includes: a bright-field detector, which is located in the first transmission path and is used to image the bright-field signal light emitted by the optical separation element; a dark-field detector, which is located in the second transmission path and is used to image the dark-field signal light emitted by the optical separation element; and a re-inspection detector, which is located in the third transmission path and is used to image the re-inspection signal light emitted by the optical separation element.

[0012] Furthermore, the optical separation element is a trapezoidal prism, with a through hole penetrating the top and bottom surfaces of the trapezoidal prism. The first and second reflecting surfaces are respectively located on the two oblique sides of the trapezoidal prism. The transmission directions of the dark field signal light, the bright field signal light, and the re-examination signal light emitted from the trapezoidal prism are all distributed in the same horizontal plane. The bright field detector, the dark field detector, and the re-examination detector are set on the same horizontal platform to reduce the influence of horizontal platform vibration on imaging.

[0013] Furthermore, bright-field and dark-field light sources include continuous light sources; re-examination light sources include strobe light sources; bright-field and dark-field detectors include line scan cameras; and re-examination detectors include color area array cameras.

[0014] Furthermore, the semiconductor inspection equipment also includes: an objective lens and a beam splitter arranged sequentially in a direction away from the wafer; both the re-inspection light and the bright field light are incident on the wafer surface through the beam splitter and the objective lens in sequence; the bright field signal light, the dark field signal light, and the re-inspection signal light are incident on the optical separation element through the objective lens and the beam splitter in sequence; the bright field signal light, the dark field signal light, and the re-inspection signal light are transmitted in a common optical path between the objective lens and the optical separation element and maintain mutual spatial isolation.

[0015] Furthermore, the semiconductor testing equipment also includes an imaging lens group, which is positioned between the beam splitter and the optical separation element. The bright field signal light, dark field signal light, and re-inspection signal light emitted from the beam splitter all pass through the imaging lens group and are incident on the optical separation element.

[0016] Furthermore, the beam-splitting element includes a beam splitter, the beam splitter's beam-splitting surface facing the objective lens is at an angle of 45° to the horizontal direction, and the imaging lens group, bright field detector, dark field detector and re-examination detector are set on the same horizontal platform.

[0017] Furthermore, the target surface size of the bright-field detector is the same as that of the dark-field detector, and the imaging field of view of the imaging lens group satisfies the following formula:

[0018]

[0019] Where D is the diameter of the imaging field of view, l is the length of the target surface, w is the width of the target surface, and d is the distance between the bright field illumination spot and the dark field illumination spot.

[0020] Furthermore, the transmittance of the beam splitter is in the range of 0 to 50%, and the reflectance of the beam splitter is in the range of 50% to 100%.

[0021] Furthermore, the semiconductor testing equipment also includes a re-examination illumination modulation mirror group and an illumination mirror group disposed between the re-examination light source and the beam splitter. The re-examination light emitted by the re-examination light source passes through the re-examination illumination modulation mirror group and the illumination mirror group in sequence and is incident on the beam splitter.

[0022] Furthermore, the illumination mirror assembly is also positioned between the bright field light source and the beam splitter. The semiconductor testing equipment also includes a bright field illumination modulation mirror assembly. The bright field light emitted by the bright field light source passes through the bright field illumination modulation mirror assembly and the illumination mirror assembly in sequence and is incident on the beam splitter.

[0023] Furthermore, the objective lens includes multiple sub-objective lenses, each with a different magnification. One of the sub-objective lenses is located in the beam transmission optical path between the beam splitter and the crystal, and the sub-objective lens located in the beam transmission optical path can be switched.

[0024] Furthermore, the semiconductor testing equipment also includes an autofocus module, which includes an autofocus light source and a dichroic mirror. The dichroic mirror is positioned between the beam splitter and the objective lens. The autofocus light source is used to emit focused light, which is guided by the dichroic mirror to illuminate the wafer surface. The wavelength of the focused light is different from the wavelengths of the re-inspection light, bright field light, dark field signal light, bright field signal light, and re-inspection signal light.

[0025] Furthermore, the semiconductor inspection equipment also includes a dark field illumination modulation mirror group that works in conjunction with the dark field light source. The dark field light emitted by the dark field light source is incident on the wafer surface through the dark field illumination modulation mirror group.

[0026] Furthermore, the semiconductor testing equipment also includes a support stage, which has a support surface for carrying wafers.

[0027] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0028] In this embodiment of the invention, the bright-field light source, dark-field light source, and re-inspection light source are independent of each other, avoiding the problem of limited wavelength selection during the detection process; the bright-field signal light, re-inspection signal light, and dark-field signal light are independent and do not overlap with each other, avoiding the need to split the signal light to obtain the bright-field signal light and re-inspection signal light, which helps to ensure that the bright-field signal light and re-inspection signal light with strong intensity are obtained, thereby improving the detection accuracy; and the distance between the two largest distances among the dark-field illumination spot, bright-field illumination spot, and re-inspection illumination spot is not too far. Thus, during the switching process between bright-field detection, dark-field detection, and re-inspection, the difficulty of locating the same detection position is avoided, which helps to realize the rapid switching between different detection methods and improve the detection speed. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0030] Figure 1A schematic diagram of the semiconductor testing device described in an embodiment of the present invention;

[0031] Figure 2 A schematic diagram of the structure of the optical separation element described in the embodiment of the present invention;

[0032] Figure 3 This is another schematic diagram of the semiconductor testing device described in the embodiment of the present invention;

[0033] Figure 4 A schematic diagram of the imaging field of view layout of the imaging lens group of the semiconductor detection device described in the embodiment of the present invention;

[0034] Figure 5 This is a schematic diagram of a single frame image using a strobe light source and a single frame image using a constant light source.

[0035] Explanation of reference numerals in the attached figures: 120, re-examination light source; 100, bright field light source; 110, dark field light source; 191, wafer; 180, optical separation element; 183, through hole; 181, first reflecting surface; 182, second reflecting surface; 200, bright field detector; 210, dark field detector; 220, re-examination detector; 160, objective lens; 150, beam splitter; 170, imaging lens group; 121, re-examination illumination modulation lens group; 130, illumination lens group; 101, bright field illumination modulation lens group; 122, first reflecting mirror group; 140, second reflecting mirror group; 161, sub-objective lens; 230, autofocus light source; 231, dichroic mirror; 111, dark field illumination modulation lens group; 190, stage. Detailed Implementation

[0036] Analysis revealed that for wafer defect detection, the detection time primarily depends on the initial scan time, the number of defects inspected in subsequent scans, and the speed at which defects are located. Within a fixed detection time, improving the initial defect identification capability becomes crucial for enhancing wafer defect detection accuracy. Considering the diverse types of defects that may exist on chips, and the varying resolution capabilities of bright-field and dark-field imaging for different defect types, a proposal was made to employ both bright-field and dark-field imaging methods in the initial scan. Therefore, the key to successful optical defect detection technology based on optical imaging lies in the rational design of the optical paths for bright-field imaging, dark-field imaging, and subsequent scans.

[0037] Existing implementation schemes can be divided into three categories: The first category sets up two or three completely independent optical systems for bright-field imaging, dark-field imaging, and re-inspection imaging, respectively. This requires switching between different optical systems to switch between bright-field detection, dark-field detection, and re-inspection, increasing the difficulty of locating defects and thus significantly increasing inspection time. The second category employs a common optical path design, where the field of view for bright-field and dark-field imaging is the same. Bright-field and dark-field imaging use different wavelengths of light for illumination, and the different wavelengths are separated at the signal collection end to achieve simultaneous bright-field and dark-field imaging. Re-inspection is then achieved by splitting the signal light. Considering the sensitivity of different defect materials to the wavelength of the detection light... Due to varying degrees of intensity, the selection of detection wavelengths for bright and dark fields in this scheme is limited. The third type of scheme also adopts a common optical path design, with bright and dark fields corresponding to different regions of the field of view, enabling regional detection of bright and dark fields. The re-inspection and bright field share the same light source, and the collected signal light from the bright field is split to achieve re-inspection imaging (such as the optical scheme disclosed in patent US20090059215A1). This scheme achieves simultaneous detection of bright and dark fields under the same optical path system, which can effectively achieve rapid and high-precision judgment of defect location. However, the re-inspection beam splitting reduces the intensity of the bright field signal and the re-inspection signal. At the same time, the rapid movement of the wafer during re-inspection can easily cause motion blur in the re-inspection imaging, thus affecting the detection accuracy.

[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 specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0039] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0040] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] refer to Figures 1 to 3 This invention provides a semiconductor testing device, comprising: a re-examination light source 120 emitting re-examination light, a bright field light source 100 emitting bright field light, and a dark field light source 110 emitting dark field light. The re-examination light, bright field light, and dark field light are respectively guided to illuminate the surface of a wafer 191. The re-examination light is reflected by the wafer 191 to form a re-examination signal light, the bright field light is reflected by the wafer 191 to form a bright field signal light, and the dark field light is scattered by the wafer 191 to form a dark field signal light. An optical separation element 180 is used to collect the bright field signal light, the dark field signal light, and the re-examination signal light and spatially separate them, so that the dark field signal light, the bright field signal light, and the re-examination signal light are emitted to different transmission paths for imaging respectively. The dark field illumination spot formed by the dark field light on the surface of the wafer 191, the bright field illumination spot formed by the bright field light on the surface of the wafer 191, and the re-examination illumination spot formed by the re-examination light on the surface of the wafer 191 do not overlap.

[0044] Among them, the bright field light source 100, the dark field light source 110, and the re-inspection light source 120 are independent of each other, which solves the problem of limited wavelength selection in the detection process; the bright field signal light, the re-inspection signal light, and the dark field signal light are independent of each other and do not overlap, avoiding the need to split the signal light to obtain the bright field signal light and the re-inspection signal light, which is conducive to ensuring that the bright field signal light and the re-inspection signal light with strong intensity are obtained, thereby improving the detection accuracy.

[0045] The semiconductor inspection equipment provided in this embodiment of the invention is used to perform defect inspection on wafer 191. In some examples, wafer 191 can be a patterned or unpatterned wafer.

[0046] In one specific embodiment, the distance between the two largest distances among the dark field illumination spot, bright field illumination spot, and re-inspection illumination spot is greater than a first preset value and less than a second preset value. The first preset value can be in the range of 0.1mm to 0.5mm, and the second preset value can be in the range of 1mm to 3mm. In other words, the distance between the two largest distances among the dark field illumination spot, bright field illumination spot, and re-inspection illumination spot is neither too far nor too close. The advantages of this setting are: If the distance is not too far, it avoids increasing the difficulty of locating the same detection position during the switching between bright field detection, dark field detection, and re-inspection, thus facilitating rapid switching between different detection methods and improving detection efficiency; if the distance is not too close, it helps ensure that bright field detection, dark field detection, and re-inspection do not interfere with each other, thus improving detection accuracy.

[0047] In the semiconductor detection equipment provided by this invention, the bright field illumination spot, dark field illumination spot, and re-inspection illumination spot are ensured to be non-overlapping and not too far apart, which is beneficial to improving detection efficiency and detection accuracy. On this basis, in order to realize the detection of bright field signal light, re-inspection signal light, and dark field signal light that are close to each other, an optical separation element 180 is used to spatially separate the bright field signal light, dark field signal light, and re-inspection signal light, so that the corresponding signal light is received by the corresponding detector. This solves the problem of high detector setting difficulty caused by the close distance between the bright field signal light, re-inspection signal light, and dark field signal light.

[0048] In one specific embodiment, the re-inspection illumination spot is located between the dark field illumination spot and the bright field illumination spot, and the distance from the dark field illumination spot to the re-inspection illumination spot is the same as or different from the distance from the bright field illumination spot to the re-inspection illumination spot.

[0049] In one specific embodiment, reference Figure 1 and Figure 2Bright-field signal light, dark-field signal light, and re-examination signal light reach optical separation element 180 along a common optical path. Optical separation element 180 has a through-hole 183, a first reflecting surface 181, and a second reflecting surface 182. Bright-field signal light incident on optical separation element 180 is reflected by the first reflecting surface 181 and exits to the first transmission path. Dark-field signal light incident on optical separation element 180 is reflected by the second reflecting surface 182 and exits to the second transmission path. Re-examination signal light incident on optical separation element 180 passes through the through-hole 183 and exits to the third transmission path. It should be noted that the extension directions of the first, second, and third transmission paths are all different. In some examples, the first and second transmission paths can extend in opposite directions, and the extension direction of the third transmission path can be perpendicular to the extension directions of the first or second transmission paths.

[0050] In one specific embodiment, the semiconductor testing device further includes: a bright-field detector 200, disposed in the first transmission path, for imaging the bright-field signal light emitted from the optical separation element 180; a dark-field detector 210, disposed in the second transmission path, for imaging the dark-field signal light emitted from the optical separation element 180; and a re-inspection detector 220, disposed in the third transmission path, for imaging the re-inspection signal light emitted from the optical separation element 180. The bright-field detector 200 is conjugate to the bright-field illumination spot, the dark-field detector 210 is conjugate to the dark-field illumination spot, and the re-inspection detector 220 is conjugate to the re-inspection illumination spot.

[0051] In one specific embodiment, reference Figure 2 The optical separation element 180 is a trapezoidal prism, and the through hole 183 penetrates the top and bottom surfaces of the trapezoidal prism. The first reflecting surface 181 and the second reflecting surface 182 are respectively disposed on the two oblique sides of the trapezoidal prism. The transmission directions of the dark field signal light, the bright field signal light, and the re-examination signal light emitted from the trapezoidal prism are all distributed in the same horizontal plane. In this way, the bright field detector 200, the dark field detector 210, and the re-examination detector 220 can be set on the same horizontal platform to reduce the impact of horizontal platform vibration on imaging.

[0052] In one specific embodiment, the bright field light source 100 and the dark field light source 110 include continuous light sources for forming efficient linear illumination spots (elongated spots) on the wafer surface; in some examples, linear fiber-coupled bright field / dark field light sources can be used as illumination inputs.

[0053] In some embodiments of the present invention, the bright field detector 200 and the dark field detector 210 include line scan cameras; in some examples, both the bright field detector 200 and the dark field detector 210 are integral delay line scan cameras. The integral delay line scan camera can maintain high-resolution image capture capability even when the wafer 191 is moving at high speed, and is suitable for application scenarios of high-precision detection of continuous and rapid movement of the wafer 191.

[0054] In some embodiments of the present invention, the re-inspection light source 120 includes a strobe light source. Using a strobe light source as the re-inspection light source 120 helps to alleviate the imaging ghosting phenomenon generated when re-inspecting a high-speed moving wafer 191. The specific explanation for using a strobe light source for illumination to alleviate the high-speed photography ghosting problem is as follows: During re-inspection and re-capture, to increase speed, photos are usually taken during movement. However, the re-inspection camera is an area scan camera. If the light source is a constant light source, due to the limited frequency of the area scan camera, the displacement caused by movement within the exposure time of a single frame can easily produce significant ghosting. Figure 5 As shown in (a); when using a stroboscopic light source for re-inspection, the frequency of the light source is higher than that of the area scan camera, meaning the stroboscopic time of the light source is very short, resulting in less ghosting, such as Figure 5 As shown in (b) above, this can alleviate the ghosting problem. In some examples, the re-inspection light source 120 can be a flickering high-brightness LED (light-emitting diode) light source; in some examples, the re-inspection illumination spot is circular; in other examples, the re-inspection illumination spot can also be shaped into a square or rectangle.

[0055] In some embodiments of the present invention, the re-inspection detector 220 includes a color area array camera, which can acquire high-precision images with higher resolution and faster sensitivity, and can capture more details and more accurate colors, which helps technicians to identify defect features by observing the color images.

[0056] In some embodiments of the present invention, both the bright-field illumination spot and the dark-field illumination spot can be elongated linear spots, while the re-inspection illumination spot is a circular spot. Specifically, refer to... Figure 4 The outermost circle represents the maximum field of view of the optical system. The maximum field of view refers to the field of view formed by the combination of the field of view of the detector receiving bright field signal light, the field of view of the detector receiving dark field signal light, and the field of view of the detector receiving re-examination signal light according to their respective relative positions. The field of view of the detector receiving bright field signal light and the field of view of the detector receiving dark field signal light can be symmetrically distributed about the center of the maximum field of view, and the center of the field of view of the detector receiving re-examination signal light can coincide with the center of the maximum field of view.

[0057] Figure 4The imaging field of view layout diagram shown is also equivalent to the illumination field of view diagram. The bright field illumination spot and the dark field illumination spot can be symmetrically distributed about the center of the field of view, and the center of the re-inspection illumination spot can coincide with the center of the maximum field of view.

[0058] It should be noted that, in order to ensure that bright-field and dark-field detection do not interfere with each other, it is essential to ensure that the bright-field illumination spot and the dark-field illumination spot do not interfere with each other. Therefore, a gap region needs to be maintained between the bright-field illumination spot and the dark-field illumination spot, which serves as an isolation zone. The width d of this gap region should be as small as possible, ideally 0. However, due to the influence of aberrations and stray light in the illumination light, the bright-field and dark-field illumination spots may have a halo or diffuse pattern. If the width d of the gap region is 0, it would require a significant investment to ensure that the surfaces of all related optical components are sufficiently clean and free of defects, and that the illumination path is free of aberrations. Therefore, considering the engineering difficulty and cost, and also to accommodate the re-inspection illumination spot, the width d of the gap region needs to be set reasonably. It is necessary to ensure that bright-field and dark-field detection do not interfere with each other, to allow the inclusion of the re-inspection illumination spot, and to prevent the bright-field and dark-field illumination regions from being too far apart, resulting in an excessively large imaging field of view. In this embodiment of the invention, the preferred width d of the gap region is 0.2 mm to 2 mm.

[0059] In one specific embodiment, reference Figure 1 The semiconductor testing equipment also includes an objective lens 160 and a beam splitter 150 arranged sequentially in a direction away from the wafer 191. The re-examination light and the bright field light are both incident on the surface of the wafer 191 through the beam splitter 150 and the objective lens 160 in sequence. The bright field signal light, the dark field signal light and the re-examination signal light are all incident on the optical separation element 180 through the objective lens 160 and the beam splitter 150 in sequence. The bright field signal light, the dark field signal light and the re-examination signal light are transmitted in the common optical path between the objective lens 160 and the optical separation element 180 and maintain mutual spatial isolation.

[0060] In one specific embodiment, the semiconductor detection device further includes an imaging lens group 170, which is disposed between the beam splitter 150 and the optical separation element 180. The bright field signal light, dark field signal light and re-examination signal light emitted from the beam splitter 150 are all incident on the optical separation element 180 through the imaging lens group 170. The imaging lens group 170 can achieve high-resolution imaging effect through different lens combinations, thereby forming a magnified image on the corresponding detector.

[0061] In one specific embodiment, the beam splitter 150 includes a beam splitter with the beam splitter surface facing the objective lens 160 at an angle of 45° to the horizontal direction. The imaging lens group 170, the bright field detector 200, the dark field detector 210 and the re-examination detector 220 are arranged on the same horizontal platform to reduce the impact of platform vibration on imaging. The principle behind reducing the impact of vibration by placing the components on the same horizontal platform is as follows: Typically, the platform used to house the imaging lens group 170, bright-field detector 200, dark-field detector 210, and re-examination detector 220 has supporting and damping structures underneath. If the components are placed on the platform and arranged horizontally, their centers of gravity are lower than the platform and they can be better fixed to it. If the components are arranged vertically, the overall center of gravity is higher, and the components on the upper level cannot be directly fixed to the marble platform, requiring additional supporting structures. This makes the upper components more susceptible to vibration. Therefore, in this embodiment of the invention, placing the imaging lens group 170, bright-field detector 200, dark-field detector 210, and re-examination detector 220 on the same horizontal platform helps reduce the impact of platform vibration on imaging.

[0062] In one specific embodiment, the target surface size of the bright-field detector 200 is the same as that of the dark-field detector 210, and the imaging field of view of the imaging lens group 170 satisfies the following formula:

[0063]

[0064] Among them, reference Figure 4 D is the diameter of the imaging field of view, l is the target surface length, i.e. the target surface length of the dark field detector 210 or the target surface length of the bright field detector 200, w is the target surface width, i.e. the target surface width of the bright field detector 200 or the target surface width of the dark field detector 210, and d is the interval distance between the bright field illumination spot and the dark field illumination spot.

[0065] In one specific embodiment, the transmittance of the beam splitter 150 is in the range of 0% to 50%, and the reflectance of the beam splitter 150 is in the range of 50% to 100%. It is understood that the re-examination light emitted from the re-examination light source 120 and the bright field light emitted from the bright field light source 100 can pass through the beam splitter 150 to reach the objective lens 160. Furthermore, the bright field signal light, dark field signal light, and re-examination signal light emitted from the objective lens 160 can be reflected by the beam splitter 150 and enter the subsequent transmission optical path. Because the bright field detection signal is sufficient (i.e., the bright field light intensity is high), while the dark field detection signal is weak (both the dark field light intensity and the dark field signal light intensity are weak), the reflectance of the beam splitter 150 is high and the transmittance is low, thereby balancing the light efficiency of bright field detection and dark field detection.

[0066] In one specific embodiment, the semiconductor testing equipment further includes a re-examination illumination modulation mirror group 121 and an illumination mirror group 130 disposed between the re-examination light source 120 and the beam splitter 150. The re-examination light emitted from the re-examination light source 120 passes sequentially through the re-examination illumination modulation mirror group 121 and the illumination mirror group 130 before being incident on the beam splitter 150. It is understood that the re-examination illumination modulation mirror group 121 may include optical elements such as relay lenses, filters, polarizers, and apertures, which play a role in shaping and modulating the re-examination light.

[0067] In one specific embodiment, the illumination mirror group 130 is further disposed between the bright-field light source 100 and the beam splitter 150. The semiconductor detection device also includes a bright-field illumination modulation mirror group 101. The bright-field light emitted from the bright-field light source 100 passes sequentially through the bright-field illumination modulation mirror group 101 and the illumination mirror group 130 before being incident on the beam splitter 150. It can be understood that the bright-field illumination modulation mirror group 101 may include some optical elements such as relay lenses, filters, polarizers, and apertures, which are used to shape and modulate the bright-field light.

[0068] In other words, in some embodiments of the present invention, the re-inspection and bright-field inspection share the same illumination lens group 130, beam splitter 150, objective lens 160 and imaging lens group 170. This not only helps to reduce the cost of semiconductor inspection equipment, but also helps to ensure that the bright-field illumination spot and the re-inspection illumination spot are not too far apart.

[0069] In some embodiments of the present invention, the semiconductor testing device further includes a first reflector group 122. The re-examination light emitted from the re-examination illumination modulation mirror group 121 undergoes optical path reversal via the first reflector group 122 before entering the illumination mirror group 130. By setting the first reflector group 122, the problem of positional conflict between the bright field light source 100 and the re-examination light source 120 caused by sharing the illumination mirror group 130 with the bright field light can be solved. Of course, in some cases, the first reflector group 122 can be omitted, and a beam transmission device such as an optical fiber can be used directly to transmit the re-examination light to the illumination mirror group 130.

[0070] In some embodiments of the present invention, the semiconductor detection device further includes a second reflector group 140, which can be used to realize the optical path switching between the re-examination light and the bright field light. Specifically, refer to... Figure 1 and Figure 3The second reflector group 140 is positioned on the transmission optical path of the re-examination light emitted from the illumination mirror group 130 and the bright field light emitted from the illumination mirror group 130. After being reflected by the second reflector group 140, the re-examination light and the bright field light undergo optical path reversal before entering the beam splitter 150. By setting the second reflector group 140 to achieve optical path reversal, the positions of various components in the semiconductor testing equipment can be rationally arranged, thereby helping to reduce the overall size of the semiconductor testing equipment. Of course, in some cases, the second reflector group 140 can be omitted, allowing the re-examination light and the bright field light to directly enter the beam splitter 150.

[0071] Further reference Figure 1 Objective lens 160 includes multiple sub-objectives 161, each with a different magnification. One of the sub-objectives 161 is located in the beam transmission optical path between beam splitter 150 and crystal 191. The sub-objective 161 located in the beam transmission optical path is switchable. For bright-field and dark-field detection, the lower-magnification sub-objective 161 can be switched to the beam transmission optical path. For re-examination, the higher-magnification sub-objective 161 can be switched to the beam transmission optical path for re-examination imaging. The selected objective magnification needs to be flexibly configured according to actual needs; no specific limitation is made here.

[0072] In some embodiments of the present invention, the optical axis of the re-examination light and the optical axis of the re-examination signal light may both coincide with the optical axis of the system.

[0073] In one specific embodiment, reference Figure 3 The semiconductor testing equipment also includes an autofocus module, which includes an autofocus light source 230 and a dichroic mirror 231. The dichroic mirror 231 is positioned between the beam splitter 150 and the objective lens 160. The autofocus light source 230 emits focused light, which is guided by the dichroic mirror 231 to illuminate the surface of the wafer 191. The focused light is reflected on the surface of the wafer 191 to form focused detection light. The focused detection light reaches the autofocus module along the original optical path. The autofocus module may also include an imaging detector, which collects the spectral information or shape information of the focused detection light. Based on this information, the position of the wafer 191 relative to the front focal plane of the objective lens can be determined. Furthermore, the wavelength of the focused light differs from the wavelengths of the re-inspection light, bright field light, dark field signal light, and re-inspection signal light. Therefore, the dichroic mirror 231 can reflect the focused light while transmitting the re-inspection light, bright field light, dark field signal light, bright field signal light, and re-inspection signal light. This ensures that the focused light passes through the objective lens 160 and is incident on the surface of the wafer 191, while also preventing the autofocus module from affecting the re-inspection, bright field detection, and dark field detection. It can be understood that the wafer 191's position is measured in real-time by the autofocus module, and the wafer 191 is adjusted to be in focus at the front focal plane of the objective lens before the wafer can undergo initial and re-inspection.

[0074] In some embodiments of the present invention, the autofocus module may use a red-band detection beam as the focusing beam. In some examples, a detection beam with a wavelength in the range of 650nm to 700nm is preferred as the focusing beam. The spectrum of the detection beam (re-examination beam, bright field beam, dark field signal beam, bright field signal beam, and re-examination signal beam) is preferably in the 400nm to 650nm band. The dichroic mirror 231 can reflect beams with wavelengths above 650nm and transmit light with wavelengths below 650nm, so that the focusing beam and the detection beam of the autofocus module do not interfere with each other.

[0075] Furthermore, the semiconductor testing equipment also includes a dark field illumination modulation mirror group 111 that works in conjunction with the dark field light source 110. The dark field light emitted by the dark field light source 110 is incident on the surface of the wafer 191 through the dark field illumination modulation mirror group 111.

[0076] It should be noted that the dark field illumination modulation mirror group 111, bright field illumination modulation mirror group 101, re-examination illumination modulation mirror group 121, imaging mirror group 170 and illumination mirror group 130 involved in the embodiments of the present invention are all used to realize optical modulation of the light beam. Optical modulation includes, but is not limited to, collimation, filtering and focusing.

[0077] In one specific embodiment, the semiconductor testing apparatus further includes a stage 190 having a support surface for supporting a wafer 191. In some examples, the stage 190 is an electrically driven displacement stage, capable of horizontally supporting the wafer 191 and moving it in the XYZ directions respectively.

[0078] The following is based on Figure 1 The working principle of the semiconductor testing equipment provided by the present invention will be further explained using the semiconductor testing equipment shown as an example.

[0079] refer to Figure 1 During the re-inspection, the re-inspection light emitted by the re-inspection light source 120 passes through the re-inspection illumination modulation mirror group 121 and the first reflecting mirror group 122 and enters the illumination mirror group 130. After passing through the second reflecting mirror group 140 and the beam splitter 150, it is uniformly illuminated on the pupil plane of the objective lens 160. The objective lens 160 forms a uniformly bright re-inspection illumination spot on the surface of the wafer 191. After a part of the wafer 191 is illuminated by the re-inspection light, a re-inspection signal light is emitted. The re-inspection signal light passes through the objective lens 160 and is reflected by the beam splitter 150 before entering the imaging mirror group 170. The re-inspection signal light emitted from the imaging mirror group 170 is incident on the optical separation element 180 and enters the imaging tube of the re-inspection detector 220 through the through hole 183 of the optical separation element 180 to achieve re-inspection imaging.

[0080] Continue to refer to Figure 1During bright-field testing, the bright-field light source 100 emits bright-field light. This bright-field light passes through the bright-field illumination modulation mirror group 101 and the incident illumination mirror group 130. The beam path of the bright-field light from the incident illumination mirror group 130 is offset from the beam path of the re-examination light from the incident illumination mirror group 130. The bright-field light emitted from the illumination mirror group 130 undergoes a light path reversal through the second reflecting mirror group 140, and then passes through the beam splitter 150 and the objective lens 160 to form a uniform bright-field illumination on the surface of the wafer 191. Because the bright field light transmitted along the common optical path is offset relative to the re-examination light, the bright field illumination spot is also offset relative to the center of the objective lens 160. After part of the surface of the wafer 191 is illuminated by the bright field light, it reflects the bright field signal light. The bright field signal light passes through the objective lens 160 and is reflected by the beam splitter 150 before entering the imaging lens group 170. It is then collected by the optical separation element 180 and received by the bright field detector 200 after being reflected by the optical separation element 180 for bright field imaging.

[0081] Continue to refer to Figure 1 The dark field light source 110 is an external light source. When performing dark field detection, the dark field light emitted by the dark field light source 110 is incident on the surface of the wafer 191 through the dark field illumination modulation mirror group 111. A dark field illumination spot is formed on the wafer 191, which is offset from the imaging field of view of the objective lens 160 and is symmetrically distributed with the bright field illumination spot about the imaging field of view of the objective lens 160. After part of the surface of the wafer 191 is illuminated by the dark field light, dark field signal light is scattered. The dark field signal light passes through the objective lens 160 and is reflected by the beam splitter 150 before entering the imaging mirror group 170. It is then collected by the optical separation element 180 and received by the dark field detector 210 after being reflected by the optical separation element 180 for dark field imaging.

[0082] It should be noted that the wafer inspection process in this invention can be divided into preliminary inspection and re-inspection. Preliminary inspection includes bright-field and dark-field inspections, which are performed simultaneously without interference. A lower-magnification objective lens can be switched into the optical path to assist with bright-field and dark-field inspections. After the bright-field and dark-field inspections are completed, a higher-magnification objective lens can be switched into the optical path to assist with the re-inspection. Of course, in some cases, preliminary and re-inspections can also be performed simultaneously. For example, a suitable magnification objective lens can be selected and switched into the optical path, allowing bright-field, dark-field, and re-inspections to proceed concurrently. Because illumination and imaging are separated, they can operate without interference, thus significantly improving inspection efficiency.

[0083] In summary, the bright-field detection, dark-field detection, and re-inspection performed by the semiconductor detection equipment provided in this embodiment of the invention separate the fields of view and integrate the re-inspection optical path, which is beneficial to improving the detection speed. The re-inspection optical path uses a separate re-inspection light source 120 and uses a stroboscopic light source to solve the imaging ghosting problem caused by the rapid movement of the wafer 191 during re-inspection. The bright-field signal light, dark-field signal light, and re-inspection signal light are separated by an isosceles trapezoidal prism (optical separation element 180) with a central opening, and then received by the corresponding detectors, which solves the problem of the signal light weakening after beam splitting caused by using beam splitters and other methods.

[0084] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0085] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A semiconductor testing device, characterized in that, include: The re-examination light source emits re-examination light, the bright field light emits bright field light, and the dark field light emits dark field light. The re-examination light, the bright field light, and the dark field light are respectively guided to illuminate the surface of the wafer. The re-examination light is reflected by the wafer to form re-examination signal light, the bright field light is reflected by the wafer to form bright field signal light, and the dark field light is scattered by the wafer to form dark field signal light. An optical separation element is used to collect the bright field signal light, the dark field signal light, and the re-examination signal light and spatially separate them, so that the dark field signal light, the bright field signal light, and the re-examination signal light are emitted to different transmission paths for imaging respectively; The bright field signal light, the dark field signal light, and the re-examination signal light reach the optical separation element along a common optical path. The optical separation element has a through hole, a first reflective surface, and a second reflective surface. The bright-field signal light incident on the optical separation element is reflected by the first reflective surface and then emitted to the first transmission path; the dark-field signal light incident on the optical separation element is reflected by the second reflective surface and then emitted to the second transmission path; and the re-examination signal light incident on the optical separation element passes through the through hole and is emitted to the third transmission path. The dark field illumination spot formed by the dark field light on the wafer surface, the bright field illumination spot formed by the bright field light on the wafer surface, and the re-inspection illumination spot formed by the re-inspection light on the wafer surface do not overlap.

2. The semiconductor testing equipment according to claim 1, characterized in that, The distance between the two largest spacings among the dark field illumination spot, the bright field illumination spot, and the re-inspection illumination spot is greater than a first preset value and less than a second preset value, wherein the first preset value is in the range of 0.1 mm to 0.5 mm and the second preset value is in the range of 1 mm to 3 mm.

3. The semiconductor testing equipment according to claim 1 or 2, characterized in that, The re-inspection illumination spot is located between the dark field illumination spot and the bright field illumination spot. The distance from the dark field illumination spot to the re-inspection illumination spot is the same as or different from the distance from the bright field illumination spot to the re-inspection illumination spot.

4. The semiconductor testing equipment according to claim 1, characterized in that, The semiconductor testing equipment also includes: A bright-field detector is located in the first transmission path and is used to image the bright-field signal light emitted by the optical separation element. A dark field detector, located in the second transmission path, is used to image the dark field signal light emitted by the optical separation element; A re-inspection detector is located in the third transmission path and is used to image the re-inspection signal light emitted by the optical separation element.

5. The semiconductor testing equipment according to claim 4, characterized in that, The optical separation element is a trapezoidal prism. The through hole penetrates the top and bottom surfaces of the trapezoidal prism. The first reflective surface and the second reflective surface are respectively disposed on two oblique sides of the trapezoidal prism. The transmission directions of the dark field signal light, the bright field signal light, and the re-examination signal light emitted from the trapezoidal prism are all distributed in the same horizontal plane. The bright field detector, the dark field detector, and the re-examination detector are disposed on the same horizontal platform to reduce the influence of horizontal platform vibration on imaging.

6. The semiconductor testing equipment according to claim 4, characterized in that, The bright-field light source and the dark-field light source include continuous light sources; the re-examination light source includes a strobe light source; the bright-field detector and the dark-field detector include a line scan camera; the re-examination detector includes a color area array camera.

7. The semiconductor testing equipment according to claim 4, characterized in that, The semiconductor testing equipment further includes an objective lens and a beam splitter arranged sequentially along a direction away from the wafer. The re-examination light and the bright field light are both incident on the wafer surface through the beam splitter and the objective lens in sequence. The bright field signal light, the dark field signal light, and the re-examination signal light are all incident on the optical separation element through the objective lens and the beam splitter in sequence. The bright field signal light, the dark field signal light, and the re-examination signal light are transmitted in a common optical path between the objective lens and the optical separation element and maintain mutual spatial isolation.

8. The semiconductor testing equipment according to claim 7, characterized in that, The semiconductor testing equipment further includes an imaging lens group, which is disposed between the beam splitter and the optical separation element. The bright field signal light, the dark field signal light, and the re-examination signal light emitted from the beam splitter all pass through the imaging lens group and are incident on the optical separation element.

9. The semiconductor testing equipment according to claim 8, characterized in that, The beam-splitting element includes a beam splitter, the beam splitter's beam-splitting surface facing the objective lens is at an angle of 45° to the horizontal direction, and the imaging lens group, the bright-field detector, the dark-field detector and the re-examination detector are arranged on the same horizontal platform.

10. The semiconductor testing equipment according to claim 8, characterized in that, The target surface size of the bright-field detector is the same as that of the dark-field detector, and the imaging field of view of the imaging lens group satisfies the following formula: ； in, D Where is the diameter of the imaging field of view. l The length of the target surface. w The target width, d This refers to the distance between the bright field illumination spot and the dark field illumination spot.

11. The semiconductor testing equipment according to claim 7, characterized in that, The transmittance of the beam splitter is in the range of 0 to 50%, and the reflectance of the beam splitter is in the range of 50% to 100%.

12. The semiconductor testing equipment according to claim 7, characterized in that, The semiconductor testing equipment further includes a re-examination illumination modulation mirror group and an illumination mirror group disposed between the re-examination light source and the beam splitter. The re-examination light emitted by the re-examination light source passes through the re-examination illumination modulation mirror group and the illumination mirror group in sequence and is incident on the beam splitter.

13. The semiconductor testing equipment according to claim 12, characterized in that, The illumination mirror group is also disposed between the bright field light source and the beam splitter. The semiconductor detection device also includes a bright field illumination modulation mirror group. The bright field light emitted by the bright field light source passes through the bright field illumination modulation mirror group and the illumination mirror group in sequence and is incident on the beam splitter.

14. The semiconductor testing equipment according to claim 7, characterized in that, The objective lens includes multiple sub-objective lenses, each with a different magnification. One of the multiple sub-objective lenses is located in the beam transmission optical path between the beam splitter and the wafer, and the sub-objective lens located in the beam transmission optical path is switchable.

15. The semiconductor testing equipment according to claim 7, characterized in that, The semiconductor testing equipment further includes an autofocus module, which comprises an autofocus light source and a dichroic mirror. The dichroic mirror is disposed between the beam splitter and the objective lens. The autofocus light source is used to emit focused light, which is guided by the dichroic mirror to illuminate the wafer surface. The wavelength of the focused light is different from the wavelength of the re-examination light, the wavelength of the bright field light, the wavelength of the dark field signal light, the wavelength of the bright field signal light, and the wavelength of the re-examination signal light.

16. The semiconductor testing equipment according to claim 1, characterized in that, The semiconductor testing equipment also includes a dark field illumination modulation mirror group that works in conjunction with the dark field light source. The dark field light emitted by the dark field light source is incident on the surface of the wafer after passing through the dark field illumination modulation mirror group.

17. The semiconductor testing equipment according to claim 1, characterized in that, The semiconductor testing equipment also includes a support platform having a support surface for supporting wafers.

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