Semiconductor detection system and dark field lighting device thereof

Abstract

The invention belongs to the technical field of semiconductor detection, and particularly relates to a semiconductor detection system and a dark field lighting device thereof. The dark field lighting device comprises a light source, an objective lens, a light beam conversion unit and a light path adjusting unit. The light source emits a first beam; the objective lens forms a dark field light path channel; the light beam conversion unit is used for converting the first light beam into a second light beam, and the light beam intensity in the second light beam is sequentially increased from the light beam center to the outer edge; the light path adjusting unit is used for transmitting at least part of light beams, close to the outer edge, in the second light beams to the dark field light path channel. In the dark field illumination device, part of the light beam entering the dark field light path channel through the light path adjusting unit is the outer edge part with high light beam intensity in the second light beam, so that the dark field illumination efficiency is improved, and the detection precision is improved. Certainly, the semiconductor detection system with the dark field illumination device has high dark field illumination efficiency.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor detection technology, and in particular, relates to a semiconductor detection system and a dark field lighting device thereof. Background Art

[0002] Traditional light sources generally include halogen lamp lighting, LED light source lighting, and laser lighting.

[0003] Halogen lamp light source lighting has low luminous efficiency, generates large heat power consumption, and has poor light source collimation. It usually requires a special focusing collimation system to shape the light beam. The lighting efficiency is low and the life is short. It needs to be frequently replaced and recalibrated, which makes it difficult to meet the long-term stable and reliable operation requirements of the equipment. Although LED light source lighting has a high luminous efficiency, the LED light source has a very large divergence angle, and also requires a special shaping system to correct the light beam. At the same time, LED lighting has high requirements for the electric drive source. When the power supply has low-frequency ripple, it is easy to have a stroboscopic effect, which affects the image detection of the OM system. Similarly, LED light sources also have the problem of light intensity attenuation. When the light intensity is attenuated, if the electric drive compensation is performed, the divergence of the light source will be inconsistent with the initial state, which makes it very difficult to calibrate the system. Therefore, laser lighting is usually used in the field of semiconductor detection lighting technology.

[0004] Laser illumination uses a collimated beam expansion method to make the light beam have a larger beam diameter and a lower divergence angle, and then uses an annular aperture to block the invalid area in the light beam, so that the effective area of ​​the light beam can pass through the dark field channel of the microscope objective to converge and irradiate the detection area of ​​the sample.

[0005] However, the laser beam in the existing laser lighting device needs to pass through an annular aperture after expansion, and the annular aperture can block and absorb the central area with the highest energy density of the laser beam, and allow the part with lower energy density near the edge to pass through, resulting in very low actual lighting efficiency. A higher-power laser and a larger-aperture beam expander are required to improve the lighting efficiency to a limited extent. In addition, most of the light energy absorbed by the annular aperture generates a large amount of heat, which has an adverse effect on the stability of the system.

[0006] In view of this, the invention is proposed. Summary of the invention

[0007] The present application provides a semiconductor detection system and a dark field illumination device thereof to solve the technical problem of low illumination efficiency of the dark field channel of the existing objective lens.

[0008] In a first aspect, the present application provides a dark field illumination device, which includes a light source, an objective lens, a beam conversion unit, and an optical path adjustment unit. The light source is used to emit a first light beam; the objective lens forms a dark field optical path channel; the beam conversion unit is used to convert the first light beam into a second light beam, and the light beam intensity in the second light beam increases from the center of the light beam to the outer edge; the optical path adjustment unit is used to transfer at least a portion of the second light beam near the outer edge to the dark field optical path channel.

[0009] In an optional scheme of the present application, the light beam transformation unit has an incident surface, a reflection surface and an exit surface connected in sequence; at least part of the first light beam is refracted to the reflection surface via the incident surface, totally reflected to the exit surface via the reflection surface, and emitted after being refracted via the exit surface, so that at least part of the first light beam is flipped from the center of the first light beam to the outer edge to form a second light beam.

[0010] In an optional solution of the present application, the incident angle of the light in the first light beam toward the incident surface is the same as the refraction angle of the light beam out of the exit surface.

[0011] In an optional scheme of the present application, the beam transformation units are arranged in pairs; the reflection surfaces of the two beam transformation units arranged in pairs are relatively arranged in the up and down directions perpendicular to the optical axis direction of the light source, and the two beam transformation units are respectively used to flip the upper half beam and the lower half beam of the first light beam in the up and down directions from the beam center to the outer edge respectively, so as to form a second light beam after convergence; or the reflection surfaces of the two beam transformation units arranged in pairs are relatively arranged in the left and right directions perpendicular to the optical axis direction of the light source, and the two beam transformation units are respectively used to flip the left half beam and the right half beam of the first light beam in the left and right directions from the beam center to the outer edge respectively, so as to form a second light beam after convergence.

[0012] In an optional solution of the present application, the cross-sectional shape of the first light beam is a circle; accordingly, the cross-sectional shape of the second light beam is two semicircles in the up and down directions; or, the cross-sectional shape of the second light beam is two semicircles in the left and right directions.

[0013] In an optional solution of the present application, each light beam transformation unit is a right-angle prism; two light beam transformation units arranged in pairs together form a cubic structure.

[0014] In an optional scheme of the present application, the beam transformation units are arranged in two pairs, and the two pairs of beam transformation units are arranged sequentially along the optical axis direction; the two beam transformation units in one pair of beam transformation units are arranged opposite to each other in the up and down direction, and the two beam transformation units in the other pair of beam transformation units are arranged opposite to each other in the left and right direction.

[0015] In an optional solution of the present application, the dark field illumination device further includes a beam expander, which is used to expand the first light beam; the beam transformation unit is arranged between the beam expander and the optical path adjustment unit in the direction of the optical axis; or the beam transformation unit is arranged between the light source and the beam expander in the direction of the optical axis.

[0016] In an optional solution of the present application, the optical path adjustment unit includes a first adjustment aperture and a reflector; the first adjustment aperture is arranged between the reflector and the beam transformation unit, and is used to allow at least a portion of the second light beam near its outer edge to pass through; the reflector is used to receive the light beam passing through the first adjustment aperture and reflect it to the dark field light path channel.

[0017] A second aspect of the present application provides a semiconductor inspection system, comprising an imaging device and the above-mentioned dark field illumination device, wherein the imaging device is used to receive light reflected and / or scattered by the surface of a workpiece to be inspected in a dark field light path channel for imaging.

[0018] In summary, the semiconductor inspection system and dark field illumination device provided by the present application have at least the following beneficial effects:

[0019] The dark field illumination device provided by the present application at least comprises a light source, an objective lens, a beam conversion unit and an optical path adjustment unit. The light source can form a first light beam with the maximum beam intensity at the center and the minimum beam intensity at the outer edge. The objective lens forms a dark field optical path channel for guiding the dark field illumination beam to the surface of the workpiece to be inspected.

[0020] The beam conversion unit is used to change the energy distribution of the first beam emitted by the light source to form a second beam. Specifically, the first beam whose beam intensity decreases from the center to the outer edge is switched to a second beam whose beam intensity increases from the center to the outer edge. In other words, the beam intensity at the center position of the second beam is smaller than the beam intensity at the edge position.

[0021] The optical path adjustment unit is used to introduce at least a portion of the edge of the second light beam converted by the beam conversion unit into the dark field light path channel, and focus on the workpiece to be inspected through the dark field light path channel. Specifically, the optical path adjustment unit can block the central portion of the second light beam from passing through, and allow the outer portion of the second light beam to pass through.

[0022] As can be seen from the above, the intensity of the second light beam increases from the center to the outer edge, that is, the center part with low intensity is blocked, and the edge part with high intensity is allowed to pass.

[0023] Such a setting has at least the following advantages:

[0024] First, the part of the light beam that enters the dark field light path channel through the light path adjustment unit is the outer edge part of the second light beam with high light intensity, which improves the dark field lighting efficiency and helps improve the detection accuracy. Of course, the semiconductor detection system with the dark field lighting device has a higher dark field lighting efficiency.

[0025] Secondly, the optical path adjustment unit blocks the central part of the second light beam with low beam intensity from passing through. Since the heat generated by the central part of the second light beam is relatively low, failures caused by high heat are avoided, which is conducive to improving the operating stability and reliability of the device. Accordingly, the semiconductor detection system equipped with the dark field illumination device has good operating stability and reliability.

[0026] Thirdly, compared with directly using the first light beam for dark field illumination, a lower power light source and a suitable beam expander can be used to reduce the cost of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific implementation of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific implementation or the prior art description. Obviously, the drawings described below are some implementations of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A schematic diagram of a dark field lighting device provided according to one embodiment of the present application;

[0029] Figure 2 A schematic diagram of a first light beam being switched into a second light beam 62 via a light beam conversion unit according to one embodiment of the present application;

[0030] Figure 3a A schematic diagram of light beam transformation units relatively arranged in the up-down direction L1 of the optical axis direction C according to one embodiment of the present application;

[0031] Figure 3b A schematic diagram of light beam transformation units being relatively arranged in a left-right direction L2 of an optical axis direction C according to one embodiment of the present application;

[0032] Figure 4 A schematic diagram of a dark field lighting device provided according to another embodiment of the present application;

[0033] Figure 5 This is a schematic diagram of a dark field lighting device provided according to yet another embodiment of the present application.

[0034] The reference numerals are as follows:

[0035] 100. Dark field lighting device;

[0036] 10. Light source;

[0037] 20. Objective lens;

[0038] 30. beam transformation unit; 31. incident surface; 32. reflection surface; 33. exit surface;

[0039] 40. Optical path adjustment unit; 41. First adjustment aperture; 42. Reflector;

[0040] 50. Beam expander;

[0041] 61. first light beam; 62. second light beam;

[0042] C, optical axis direction; L1, up and down direction; L2, left and right direction; T1, dark field optical path channel;

[0043] 200. Workpiece to be inspected. DETAILED DESCRIPTION

[0044] In the description of the present application, it should be understood that if terms such as "upper", "lower", "front", "rear", "left", "right", "axial" or the like appear to indicate orientation or positional relationships, unless otherwise specified, they are understood to be based on the orientation or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0045] In addition, if there is a feature defined as "first" or "second", it is only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Features defined as "first" or "second" may explicitly or implicitly include at least one of the defined features. If there is a description of "plurality", the general meaning is to include at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0046] In this application, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed" and so on should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection, it can be a direct connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0047] In the description of this specification, if the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" appear, it means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0048] Figure 1 FIG. 1 is a schematic diagram of a dark field lighting device 100 provided according to one embodiment of the present application. Figure 1 In one aspect of the present application, a dark field illumination device 100 is provided, which includes a light source 10, an objective lens 20, a beam transformation unit 30, and an optical path adjustment unit 40. The light source 10 is used to emit a first light beam 61. The objective lens 20 forms a dark field optical path channel T1. The beam transformation unit 30 is used to transform the first light beam 61 into a second light beam 62, and the light beam intensity in the second light beam 62 increases from the center of the light beam to the outer edge. The optical path adjustment unit 40 is used to transfer at least a portion of the second light beam 62 near its outer edge to the dark field optical path channel T1.

[0049] In this embodiment, the dark field illumination device 100 at least includes a light source 10 , an objective lens 20 , a light beam transformation unit 30 , and a light path adjustment unit 40 .

[0050] It should be noted that since the laser light source has the advantages of spatial Gaussian distribution, narrow beam waist, small divergence angle, focus, self-focusing, high coherence, etc., the light source 10 preferably adopts a laser light source. Among them, spatial Gaussian distribution means that the energy of the light beam is normally distributed. Specifically, the position of the maximum intensity of the light beam is the center of the light spot, and the light intensity gradually decreases in the direction of radiation outward from the center of the light spot as the reference point.

[0051] That is, in this embodiment, the beam intensity at the center position of the first light beam 61 emitted by the light source 10 is the largest, and the beam intensity at the outer edge position is the smallest.

[0052] Exemplarily, the laser light source may be a laser emitted by a fiber laser, a semiconductor laser, a solid laser, a gas laser, etc., but is certainly not limited to the above lasers, and the light source 10 is not limited to a laser light source.

[0053] In addition, the objective lens 20 is an important component of the electron beam imaging device, which can provide a stable imaging environment. Moreover, the objective lens 20 is formed with a dark field optical path channel T1, which is used for the dark field illumination optical path to pass through and focus the dark field light beam on the workpiece 200 to be inspected.

[0054] In this embodiment, the dark field optical path channel T1 is a channel with a ring-shaped cross section, which can be a cylindrical ring channel, but is not limited thereto, and can be adjusted and designed according to the shape of the introduced dark field light beam.

[0055] The beam conversion unit 30 is used to change the energy distribution in the first beam 61 emitted by the light source 10 to form the second beam 62. Specifically, the first beam 61 whose beam intensity decreases from the center to the outer edge is switched to the second beam 62 whose beam intensity increases from the center to the outer edge. In other words, the beam intensity at the center of the second beam 62 is smaller than the beam intensity at the edge.

[0056] The optical path adjustment unit 40 is used to introduce at least a portion of the edge of the second light beam 62 converted by the light beam conversion unit 30 into the dark field light path channel T1, and focus on the workpiece 200 to be inspected through the dark field light path channel T1. Specifically, the optical path adjustment unit 40 can block the central portion of the second light beam 62 from passing through, and allow the outer portion of the second light beam 62 to pass through.

[0057] As can be seen from the above, the intensity of the second light beam 62 increases from the center to the outer edge, that is, the center portion with low intensity is blocked, and the edge portion with high intensity is allowed to pass.

[0058] It can be seen that the dark field lighting device 100 provided in the present application has at least the following advantages:

[0059] First, the portion of the light beam that enters the dark field light path channel T1 through the light path adjustment unit 40 is the outer edge portion of the second light beam 62 with high light intensity, which improves the dark field lighting efficiency and helps to improve the detection accuracy.

[0060] Secondly, the optical path adjustment unit 40 blocks the central part of the second light beam 62 with low beam intensity from passing through. Since the heat generated by the central part of the second light beam 62 is relatively low, failures caused by high heat are avoided, which is beneficial to improving the operating stability and reliability of the device.

[0061] Thirdly, compared with directly using the first light beam 61 for dark field illumination, a lower-power light source 10 and a matching beam expander can be used, thereby reducing the cost of the device.

[0062] Figure 2Schematic diagram of a first light beam 61 being switched to a second light beam 62 via a light beam conversion unit 30 according to one embodiment of the present application. The left side of the light beam conversion unit 30 is the spot shape of the first light beam 61, and the right side of the light beam conversion unit 30 is the spot shape of the second light beam 62. Figure 2 The beam transformation unit 30 has an incident surface 31, a reflection surface 32 and an exit surface 33 which are connected in sequence.

[0063] At least a portion of the first light beam 61 is refracted from the incident surface 31 to the reflective surface 32, totally reflected from the reflective surface 32 to the emitting surface 33, and refracted from the emitting surface 33 to be emitted, so that at least a portion of the first light beam 61 is flipped from the center of the first light beam 61 to the outer edge to form the second light beam 62.

[0064] In this embodiment, the light beam transformation unit 30 is a transparent optical element having multiple planes, that is, a polyhedral optical element. Some of the planes can be divided into an incident surface 31, a reflection surface 32, and an exit surface 33 according to their functions, wherein both the incident surface 31 and the exit surface 33 can allow the light beam to pass through, while the reflection surface 32 cannot allow the light beam to pass through and can only reflect the light beam.

[0065] Specifically, the first light beam 61 first enters the light beam conversion unit 30 after being refracted by the incident surface 31, reaches the reflection surface 32, is reflected by the reflection surface 32 to the emission surface 33, and then is refracted by the emission surface 33 and emitted from the light beam conversion unit 30. In this process, the central part of the first light beam 61 is flipped toward the outer edge, that is, the central part with high light beam intensity moves toward the outer edge, that is, the light beam intensity distribution of the first light beam 61 is adjusted so that the light beam intensity of the outer edge part is high, and the second light beam 62 is formed accordingly.

[0066] In a further optional embodiment, the beam transformation units 30 are arranged in pairs. Figure 3a It is a schematic diagram of the light beam transformation units 30 relatively arranged in the up-down direction L1 of the optical axis direction C according to one embodiment of the present application.

[0067] In one of the optional embodiments, the reflection surfaces 32 of the two beam transformation units 30 arranged in a pair are arranged relative to each other in the up-down direction L1 perpendicular to the optical axis direction C of the light source 10, and the two beam transformation units 30 are respectively used to flip the upper half beam and the lower half beam of the first light beam 61 in the up-down direction L1 from the beam center to the outer edge of the first light beam 61, so as to form a second light beam 62 after convergence.

[0068] In this embodiment, the paired beam transformation units 30 are arranged opposite to each other in the up-down direction L1 of the optical axis direction C. The beam transformation unit 30 located at the upper side in the up-down direction L1 flips the center portion of the upper half of the first beam 61 toward the outer edge, and correspondingly, the outer edge portion of the upper half of the first beam 61 flips toward the center to form the upper half of the second beam 62.

[0069] Correspondingly, the beam transformation unit 30 located at the bottom in the up-down direction L1 flips the center portion of the lower half beam of the first beam 61 toward the outer edge, and accordingly, the outer edge portion of the lower half beam of the first beam 61 flips toward the center to form the lower half beam of the second beam 62. In this way, the two half beams converge to form the second beam 62, and for the upper and lower half beams of the second beam 62, the beam intensity of the outer edge portion is higher than the beam intensity of the central portion.

[0070] Please continue reading Figure 2 Furthermore, the cross-sectional shape of the first light beam 61 is a circle. Accordingly, the cross-sectional shape of the second light beam 62 is two upper and lower semicircles in the up-down direction L1.

[0071] It should be understood that the cross-sectional shape of a light beam is the shape of its light spot. In the present embodiment, the light spot formed by the first light beam 61 is circular. The circular light spot of the first light beam 61 is divided into an upper semicircle and a lower semicircle in the optical axis direction C. The upper semicircular light beam of the first light beam 61 is flipped through the upper light beam transformation unit 30 to form an upper semicircular light beam of the second light beam 62.

[0072] The lower semicircular beam of the first light beam 61 is flipped through the beam transformation unit 30 below to form the lower semicircular beam of the second light beam 62. The two semicircular beams converge to form the second light beam 62.

[0073] To understand this solution, please refer to Figure 2 In the embodiment shown, the outer edge ray 1 of the upper semicircular beam in the first beam 61 is flipped through the upper beam transformation unit 30 to form the center ray 1' of the upper semicircular beam in the second beam 62. The center ray 2 of the upper semicircular beam in the first beam 61 is flipped through the upper beam transformation unit 30 to form the outer edge ray 2' of the upper semicircular beam in the second beam 62.

[0074] Similarly, the center light ray 3 of the lower semicircular beam in the first light beam 61 is flipped through the upper beam transformation unit 30 to form the outer edge light ray 3' of the lower semicircular beam in the second light beam 62. The outer edge light ray 4 of the lower semicircular beam in the first light beam 61 is flipped through the upper beam transformation unit 30 to form the outer edge light ray 4' of the lower semicircular beam in the second light beam 62.

[0075] From the above, it can be seen that under the action of the beam transformation unit 30 arranged in pairs in the upper and lower directions of the optical axis direction C, the first light beam 61 is separated into upper and lower semicircular parts in the optical axis direction C and flipped, specifically, the central part with high beam intensity is flipped to the outer edge part, and the outer edge part with low beam intensity is flipped to the central part, so as to form a second light beam 62 with low central beam intensity and high outer edge beam intensity.

[0076] Figure 3b It is a schematic diagram of the beam transformation units 30 being relatively arranged in the left-right direction L2 of the optical axis direction C according to one embodiment of the present application.

[0077] In another optional embodiment, the reflection surfaces 32 of two beam transformation units 30 arranged in a pair are relatively arranged in the left-right direction L2 perpendicular to the optical axis direction C of the light source 10, and the two beam transformation units 30 are respectively used to flip the left half beam and the right half beam of the first light beam 61 in the left-right direction L2 from the beam center to the outer edge of the first light beam 61, so as to form a second light beam 62 after convergence.

[0078] In this embodiment, the paired beam transformation units 30 are arranged opposite to each other in the left-right direction L2 of the optical axis direction C. The beam transformation unit 30 located on the left in the left-right direction L2 flips the center portion of the left half beam of the first beam 61 toward the outer edge, and correspondingly, the outer edge portion of the left half beam of the first beam 61 flips toward the center to form the left half beam of the second beam 62.

[0079] Correspondingly, the beam transformation unit 30 located on the right side in the left-right direction L2 flips the center portion of the right half beam of the first beam 61 toward the outer edge, and accordingly, the outer edge portion of the right half beam of the first beam 61 flips toward the center to form the right half beam of the second beam 62. In this way, the two half beams converge to form the second beam 62, and for the left and right half beams of the second beam 62, the beam intensity of the outer edge portion is higher than that of the center portion.

[0080] Furthermore, the cross-sectional shape of the first light beam 61 is a circle. Accordingly, the cross-sectional shape of the second light beam 62 is two left and right semicircles in the left-right direction L2.

[0081] It should be understood that the cross-sectional shape of a light beam is the shape of its light spot. In the present embodiment, the light spot formed by the first light beam 61 is circular. The circular light spot of the first light beam 61 is divided into a left semicircle and a right semicircle in the optical axis direction C. The left semicircular light beam of the first light beam 61 is flipped through the beam transformation unit 30 on the left to form the left semicircular light beam of the second light beam 62.

[0082] The right semicircular beam of the first light beam 61 is flipped by the right beam transformation unit 30 to form the right semicircular beam of the second light beam 62. The two semicircular beams converge to form the second light beam 62.

[0083] It should be noted that although the drawings do not show a schematic diagram of how the first light beam 61 forms the second light beam 62 via the light beam transformation units 30 arranged in pairs in the left and right directions L2 of the optical axis direction C, it can be referred to Figure 2 To understand.

[0084] Figure 4 FIG. 1 is a schematic diagram of a dark field lighting device 100 provided according to another embodiment of the present application. Figure 4 In a further optional embodiment, the beam transformation unit 30 is provided in two pairs, and the two pairs of beam transformation units 30 are sequentially arranged along the optical axis direction C;

[0085] The two beam transformation units 30 in one pair of beam transformation units 30 are disposed opposite to each other in the up-down direction L1 , and the two beam transformation units 30 in the other pair of beam transformation units 30 are disposed opposite to each other in the left-right direction L2 .

[0086] In this embodiment, there are two pairs of beam transformation units 30 , one of which is disposed opposite to the other in the vertical direction L1 of the optical axis direction C, and the other is disposed opposite to the other in the horizontal direction L2 of the optical axis direction C.

[0087] exist Figure 4 In the illustrated embodiment, in the optical axis direction C, the beam transformation units 30 arranged in the up-down direction L1 are located upstream of the beam transformation units 30 arranged in the left-right direction L2. The two pairs of beam transformation units 30 are not limited to an upstream-downstream relationship in the optical axis direction C, and they can be arranged in sequence along the optical axis direction C.

[0088] Please continue to combine Figure 4 The beam conversion unit 30 relatively arranged in the up-down direction L1 upstream of the first light beam 61 emitted by the light source 10 realizes the replacement of the central part of the light beam with the edge part of the light beam in the up-down direction L1. The light beam converted for the first time passes through the beam change element relatively arranged in the left-right direction L2 downstream, thereby replacing the central part of the light beam with the edge part of the light beam again in the left-right direction L2.

[0089] In other words, in this embodiment, the intensity distribution of the light spot of the first light beam 61 is adjusted successively in two different directions, so that the intensity distribution of the light spot of the formed second light beam 62 better meets the requirements of low center intensity and high edge intensity.

[0090] In some optional embodiments, the incident angle of the light in the first light beam 61 toward the incident surface 31 is the same as the refraction angle of the light out of the exit surface 33 .

[0091] In this embodiment, the incident angle formed by the first light beam 61 on the incident surface 31 and the refraction angle formed on the exit surface 33 are the same, which indicates that the light propagation direction of the first light beam 61 does not change after passing through the beam transformation unit 30, and only the distribution of its beam intensity changes.

[0092] That is, the light beam transformation unit 30 does not change the direction of the light path, nor does it focus or expand the light beam, but only adjusts the intensity distribution of the light beam.

[0093] In the embodiment shown in 2, after the light in the first light beam 61 passes through the light beam transformation unit 30, the incident light beam is parallel to the outgoing light beam and moves in the vertical direction L1, that is, only the position is changed, and the propagation direction of the light beam is not changed. As shown in the figure, light beam 1 and light beam 1'.

[0094] exist Figure 2 In the illustrated embodiment, the incident angle of the light in the first light beam 61 to the incident surface 31 and the refraction angle of the light out of the exit surface 33 are both 45°. It should be noted that the incident angle here refers to the acute angle formed by the light and the incident surface 31, and the exit angle refers to the acute angle formed by the exiting light and the exit surface 33.

[0095] It should be noted that the incident angle and the exit angle are not limited to the illustrated embodiment, and are determined by the angles between the incident surface 31 and the exit surface 33 and the reflection surface 32 , that is, determined according to the shape of the light beam transformation unit 30 .

[0096] For the case where the light beam transformation units 30 are arranged in pairs. In an optional embodiment, each light beam transformation unit 30 is a right-angle prism, and the two light beam transformation units 30 arranged in pairs together form a cubic structure.

[0097] In this embodiment, the light beam transformation unit 30 is a right-angle prism, which is a transparent lens. Its material can be glass or crystal, etc., and the planes where its two right-angle sides are located correspond to the incident surface 31 and the exit surface 33 respectively, and the plane where its hypotenuse is located corresponds to the reflection surface 32.

[0098] The two beam transformation units 30 form a cubic structure, that is, the reflection surfaces 32 of the two beam transformation units 30 face each other and are arranged in contact. That is, the two beam transformation units 30 are connected to form a hexahedron structure, and each plane in the optical axis direction C acts on the beam.

[0099] It should be noted that the beam transformation unit 30 is not limited to a right-angle prism. For example, the beam transformation unit 30 can also be an isosceles trapezoidal prism, where the planes where the two waists of the trapezoidal prism are located correspond to the incident surface 31 and the exit surface 33, and one of the planes where the two parallel sides are located is used as the reflection surface 32. Of course, the beam transformation unit 30 is not limited to the above.

[0100] In some optional embodiments, the dark field illumination device 100 further includes a beam expander 50, and the beam expander 50 is used to expand the first light beam 61. In one optional embodiment, the beam transformation unit 30 is disposed between the beam expander 50 and the light path adjustment unit 40 in the optical axis direction C.

[0101] In this embodiment, the first light beam 61 is first expanded by the beam expander 50 and then converted by the beam conversion unit 30 to obtain the second light beam 62 .

[0102] It should be understood that the beam diameter of the first light beam 61 becomes larger under the action of the beam expander 50 , and accordingly, a beam transformation unit 30 with a relatively large size needs to be matched to cover the first light beam 61 after expansion.

[0103] With such configuration, the energy of the first light beam 61 received by the light beam conversion unit 30 is relatively dispersed, so that the service life of the light beam conversion unit 30 is prolonged.

[0104] Figure 5 FIG. 1 is a schematic diagram of a dark field illumination device 100 provided according to another embodiment of the present application. In another optional embodiment, the beam transformation unit 30 is disposed between the light source 10 and the beam expander 50 in the optical axis direction C.

[0105] In this embodiment, the first light beam 61 is first converted by the light beam conversion unit 30 to obtain the second light beam 62 , and then the second light beam 62 is expanded by the beam expander 50 .

[0106] It should be understood that, since the first light beam 61 is converted by the beam conversion unit 30 before being expanded by the beam expander 50, the beam diameter of the second light beam 62 is relatively small, and accordingly, the size of the beam conversion unit 30 is relatively small. Such an arrangement can make the structure of the entire dark field lighting device 100 more compact and have better space utilization.

[0107] It should be noted that the beam expander 50 here may be a beam expander lens group, that is, the first light beam 61 is expanded by using a plurality of lenses.

[0108] In a further optional embodiment, the optical path adjustment unit 40 includes a first adjustment aperture 41 and a reflector 42. The first adjustment aperture 41 is disposed between the reflector 42 and the beam transformation unit 30, and is used to allow at least a portion of the second light beam 62 near its outer edge to pass through. The reflector 42 is used to receive the light beam passing through the first adjustment aperture 41 and reflect it to the dark field optical path channel T1.

[0109] In this embodiment, the optical path adjustment unit 40 at least comprises a first adjustment aperture 41 and a reflector 42. The first adjustment aperture 41 is used to block the middle portion of the second light beam 62, i.e., the portion with lower energy, to allow the outer portion, i.e., the portion with higher energy, to pass through.

[0110] The reflector 42 is used to reflect the second light beam 62 filtered by the first adjustment aperture 41 to introduce the filtered second light beam 62 into the dark field light path channel T1 of the objective lens 20, so as to focus the outer edge part of the second light beam 62 with higher beam intensity on the surface of the workpiece 200 to be inspected.

[0111] In a specific application, when the light beam is a circular light beam, an annular through hole is provided on the first adjustment aperture 41, which allows the outer edge of the circular light beam to pass through and blocks the light beam in the center. Since the energy of the light beam in the center is relatively low, the heat generated on the first adjustment aperture 41 is relatively small. It should be understood that the through hole on the first adjustment aperture 41 for allowing the light beam to pass through is not limited to a circular ring shape.

[0112] In a further optional embodiment, the optical path adjustment unit 40 further includes a second adjustment aperture (not shown). The second adjustment aperture is disposed between the reflector 42 and the objective lens 20, and is used for allowing at least part of the light beam reflected by the reflector 42 to pass through.

[0113] In this embodiment, a second adjustment aperture may be provided between the reflector 42 and the objective lens 20 to further filter the second light beam 62 filtered by the first adjustment aperture 41 to obtain a portion of the outer edge light beam with more concentrated energy.

[0114] Another aspect of the present application also includes a semiconductor inspection system, including an imaging device and the above-mentioned dark field illumination device 100. The imaging device is used to receive light reflected and / or scattered by the surface of the workpiece 200 to be inspected in the dark field light path channel T1 for imaging.

[0115] It should be noted that the imaging device here may refer to an electron beam imaging device, including, for example, a scanning electron microscope. In the dark field illumination device 100, the beam conversion unit 30 can convert the first beam 61 with high center beam intensity into the second beam 62 with high outer beam intensity, that is, the energy distribution of the illumination beam is converted from decreasing from the inside to the outside to increasing from the inside to the outside. The part of the beam with high energy at the outer edge is filtered by the first adjustment aperture 41 and enters the dark field illumination channel T1, so as to converge the beam to illuminate the surface of the workpiece 200 to be inspected, thereby improving the illumination of the surface and thus improving the resolution of the dark field measurement.

[0116] The workpiece 200 to be inspected here may be a wafer. Of course, the semiconductor body inspection system also has other advantages brought by the dark field lighting device 100, which will not be repeated here.

[0117] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A dark field lighting device, characterized in that: include: A light source (10) for emitting a first light beam (61); An objective lens (20) is formed with a dark field optical path channel (T1); A beam conversion unit (30) for converting the first beam (61) into a second beam (62), wherein the beam intensity of the second beam (62) increases from the beam center to the outer edge; and The optical path adjustment unit (40) is used to transmit at least a portion of the second light beam (62) close to its outer edge to the dark field optical path channel (T1).

2. The dark field lighting device according to claim 1, characterized in that: The light beam transformation unit (30) comprises an incident surface (31), a reflection surface (32) and an exit surface (33) which are connected in sequence; At least part of the first light beam (61) is sequentially refracted via the incident surface (31) to the reflection surface (32), totally reflected via the reflection surface (32) to the exit surface (33), and refracted via the exit surface (33) before being emitted, so that at least part of the first light beam (61) is flipped from the center of the first light beam (61) to the outer edge to form the second light beam (62).

3. The dark field lighting device according to claim 2, characterized in that: The incident angle of the light in the first light beam (61) incident on the incident surface (31) is the same as the refraction angle of the light out of the exit surface (33).

4. The dark field lighting device according to claim 2, characterized in that: The light beam transformation units (30) are arranged in pairs; The reflection surfaces (32) of the two beam conversion units (30) arranged in a pair are arranged opposite to each other in an up-down direction (L1) perpendicular to the optical axis direction (C) of the light source (10), and the two beam conversion units (30) are respectively used to flip the upper half beam and the lower half beam of the first light beam (61) in the up-down direction (L1) from the beam center to the outer edge of the first light beam (61) to form the second light beam (62) after convergence; or The reflection surfaces (32) of the two light beam conversion units (30) arranged in pairs are arranged opposite to each other in a left-right direction (L2) perpendicular to the optical axis direction (C) of the light source (10), and the two light beam conversion units (30) are respectively used to flip the left half light beam and the right half light beam of the first light beam in the left-right direction (L2) from the beam center to the outer edge of the first light beam, so as to form the second light beam after converging.

5. The dark field lighting device according to claim 4, characterized in that: The cross-sectional shape of the first light beam (61) is circular; Correspondingly, the cross-sectional shape of the second light beam (62) is two upper and lower semicircles in the up-down direction (L1); or, the cross-sectional shape of the second light beam (62) is two left and right semicircles in the left-right direction (L2).

6. The dark field lighting device according to claim 4, characterized in that: Each of the light beam transformation units (30) is a right-angle prism; The two light beam transformation units (30) arranged in pairs together form a cubic structure.

7. The dark field lighting device according to claim 4, characterized in that: The light beam transformation units (30) are arranged in two pairs, and the two pairs of light beam transformation units (30) are arranged in sequence along the optical axis direction (C); Two of the beam transformation units (30) in one pair of the beam transformation units (30) are arranged relative to each other in the up-down direction (L1), and two of the beam transformation units (30) in the other pair of the beam transformation units (30) are arranged relative to each other in the left-right direction (L2).

8. The dark field lighting device according to any one of claims 1 to 7, characterized in that: The dark field illumination device (100) further comprises a beam expander (50), wherein the beam expander (50) is used to expand the first light beam (61); The light beam transformation unit (30) is arranged between the beam expander (50) and the light path adjustment unit (40) in the optical axis direction (C); or The light beam transformation unit (30) is arranged between the light source (10) and the beam expander (50) in the optical axis direction (C).

9. The dark field lighting device according to claim 8, characterized in that: The optical path adjustment unit (40) comprises a first adjustment aperture (41) and a reflecting mirror (42); The first adjustment aperture (41) is arranged between the reflector (42) and the light beam transformation unit (30) and is used for allowing at least a portion of the second light beam close to its outer edge to pass through; The reflector (42) is used to receive the light beam passing through the first adjustment aperture (41) and reflect it to the dark field light path channel (T1).

10. A semiconductor testing system, characterized in that: The invention comprises an imaging device and a dark field illumination device (100) as claimed in any one of claims 1 to 9, wherein the imaging device is used to receive light reflected and / or scattered by the surface of a workpiece (200) to be inspected in the dark field optical path channel (T1) for imaging.

Images