Optical equipment for wafer detection

Abstract

The invention provides optical equipment for wafer detection, and the equipment comprises a light source system which comprises a bright field light source system and / or a dark field light source system; the line scanning system comprises a line scanning camera and a first light splitting device which are arranged in sequence; the area array system comprises an area array camera; the objective lens system comprises a plurality of objective lenses, and a third light splitting device is arranged above the objective lens system; the position adjusting system comprises a camera adjusting mechanism and an equipment adjusting mechanism, the camera adjusting mechanism is used for adjusting the position of the line scanning camera and / or the area-array camera, and the equipment adjusting mechanism is used for adjusting the position of the optical equipment.

Description

Technical Field

[0001] The present application relates to the field of optical detection, and in particular to an optical device for wafer detection. Background Art

[0002] Existing optical inspection equipment is of various types and functions. There are different single-item test equipment for different inspection needs, such as line scanning equipment, area array equipment, autofocus equipment, etc. However, there is currently a lack of optical inspection equipment that integrates multiple functions on the market, especially optical equipment for wafer inspection. As a result, during the wafer inspection process, the equipment needs to be constantly replaced to meet different test needs. Not only is the time cost high, but switching equipment may also introduce unexpected interference and affect the inspection results. Summary of the invention

[0003] In order to solve the problem of low integration of current optical inspection equipment, the present application proposes an optical device for wafer inspection, including: a light source system, including a bright field light source system and / or a dark field light source system; a line scan system, including a line scan camera and a first spectroscopic device arranged in sequence; an area array system, including an area array camera; an objective lens system, including multiple objective lenses, wherein a third spectroscopic device is arranged above the objective lens system; a position adjustment system, including a camera adjustment mechanism and a device adjustment mechanism, the camera adjustment mechanism is used to adjust the position of the line scan camera and / or the area array camera, and the device adjustment mechanism is used to adjust the position of the optical device.

[0004] Optionally, the bright field light source system includes a bright field light source, a first lens and a second lens.

[0005] Optionally, the bright field light source system further includes a reflective device for reflecting the light beam generated by the bright field light source system to the first beam splitter of the line scanning system.

[0006] Optionally, the optical device further includes an automatic focusing system configured to automatically focus the sample to be measured; and the area array system further includes a second spectroscopic device.

[0007] Optionally, the automatic focusing system comprises: An automatic focusing light source component, comprising an infrared light source, a third lens and a fourth light splitting device; an automatic focusing detection component configured to generate a detection result for automatic focusing of the objective lens system based on the infrared light generated by the infrared light source; The auto-focusing filter device is arranged between the auto-focusing light source component and the auto-focusing detection component, and is used for filtering out visible light.

[0008] Optionally, the autofocus detection component includes a first detection component and a second detection component, the first detection component includes a first detection unit, a first aperture and a fourth lens arranged in sequence, and the second detection component includes a second detection unit, a second aperture and a fifth lens arranged in sequence; wherein the fourth lens and the fifth lens have the same focal length, the first aperture is arranged at a first distance at the front end of the focus of the fourth lens, and the second aperture is arranged at a second distance at the rear end of the focus of the fifth lens, and the first distance is equal to the second distance; The automatic focusing system further comprises a fifth beam splitter, which is used to project the light beam to the first detection component and the second detection component respectively.

[0009] Optionally, the first detection unit and the second detection unit are photodetectors.

[0010] Optionally, the automatic focusing detection component includes a four-quadrant detector, a cylindrical lens and a sixth lens arranged in sequence.

[0011] Optionally, the line scan system further includes a first tube lens, and the area array system further includes a second tube lens.

[0012] Optionally, the line scan system further includes a first optical filter device, and the area array system further includes a second optical filter device.

[0013] Optionally, the optical device further comprises a differential interference system, wherein the differential interference system comprises: A polarizing device, arranged between the light source system and the line scanning system; A first film inspection device is arranged between the first tube lens and the first filter device; A second film inspection device is arranged between the second tube lens and the second filter device; The Nomarski prism is arranged between the objective lens system and the third beam splitter.

[0014] Optionally, the device adjustment mechanism is used to adjust the rotation angle of the optical device.

[0015] Optionally, the camera adjustment mechanism comprises: The moving plate is provided with a first waist-shaped groove and a second waist-shaped groove; The fixed plate is provided with a first pushing mechanism and a second pushing mechanism, wherein the first pushing mechanism and the second pushing mechanism are used to push the movable plate to rotate; A first screw, disposed in the first waist-shaped groove, for connecting the movable plate and the fixed plate; The second screw is disposed in the second waist-shaped groove and is used to connect the movable plate and the fixed plate; wherein, When the movable plate rotates, the first waist-shaped groove and the second waist-shaped groove make a circular motion with the midpoint between the first screw and the second screw as the center, and the first ejection mechanism and the second ejection mechanism make a circular motion with the midpoint as the center.

[0016] Optionally, the movable plate includes a protruding first pushing surface and a second pushing surface, the first pushing mechanism is perpendicular to the first pushing surface, and the second pushing mechanism is perpendicular to the second pushing surface.

[0017] Optionally, a line connecting the first ejection mechanism and the midpoint is perpendicular to a line connecting the second ejection mechanism and the midpoint.

[0018] The above optical device proposed in the present application well integrates various optical detection functions into a relatively compact unified device, which not only saves device space, but also greatly improves detection efficiency. In addition, by adjusting the position of each device in the optical device through the position adjustment system, not only can the optical device be easily adjusted to the optimal working state, but also friction is reduced, avoiding dust generated by friction during position adjustment from affecting the dust-free detection environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of an optical device for wafer detection according to an embodiment of the present application.

[0020] Figure 2 It is a schematic diagram of the optical path structure of an optical device for wafer detection according to an embodiment of the present application.

[0021] Figure 3 It is a schematic structural diagram of an automatic focusing detection component of an optical device for wafer inspection according to an embodiment of the present application.

[0022] Figure 4 It is a schematic diagram of the optical path structure of an optical device for wafer detection according to an embodiment of the present application.

[0023] Figure 5 It is a schematic diagram of the optical path structure of an optical device for wafer detection according to an embodiment of the present application.

[0024] Figure 6 Schematic diagram of the light spot of a four-quadrant detector according to an embodiment of the present application.

[0025] Figure 7 It is a stereoscopic diagram of a camera adjustment mechanism of an optical device for wafer inspection according to an embodiment of the present application.

[0026] Figure 8 It is a plan view of a camera adjustment mechanism of an optical device for wafer inspection according to an embodiment of the present application.

[0027] Fig. 9 The invention relates to an optical device for wafer inspection provided with a device adjustment mechanism according to an embodiment of the present application.

[0028] Fig.10 It is a flow chart of position adjustment of an optical device for wafer inspection according to an embodiment of the present application.

[0029] Figure numerals: 1, bright field light source; 2, first lens; 3, second lens; 4, reflector; 5, dark field light source; 6, sample to be measured; 7, line scan camera; 8, first tube lens; 9, first spectrometer; 10, array camera; 11, second tube lens; 12, second spectrometer; 13, objective lens; 14, objective lens turret; 15, third spectrometer; 16, infrared light source; 17, third lens; 18, fourth spectrometer; 19, third A detection unit; 20, a first aperture; 21, a fourth lens; 22, a second detection unit; 23, a second aperture; 24, a fifth lens; 25, a fifth spectrometer; 26, an autofocus filter; 27, a first filter; 28, a second filter; 29, a polarizing device; 30, a first film inspection device; 31, a second film inspection device; 32, a Nomarski prism; 33, a four-quadrant detector; 34, a cylindrical lens; 35, a sixth lens. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0031] Figure 1 The schematic diagram of the structure of the optical device for wafer detection proposed in the present application mainly includes a light source system 101 for optical detection, a line scanning system 102, a surface array system 103, an objective lens system 104 and a position adjustment system 105 for mechanical adjustment. Among them, the light source system 101 provides a light source for imaging the sample to be tested (i.e., the wafer to be tested), the line scanning system 102 is used for line scanning imaging of the sample to be tested, the surface array system 103 is used for surface scanning imaging of the sample to be tested, the objective lens system 104 is used to switch different objective lenses according to the detection requirements, and the position adjustment system 105 is used to adjust the position of the entire optical device and the position of each system therein. Furthermore, in other embodiments, the automatic focusing system a can also be integrated into the optical device one to further improve the integration and automation of the optical device one.

[0032] The light source system 101, the line scanning system 102, the area array system 103, the objective lens system 104 and the automatic focusing system a are the optical path structure of the optical device, and the position adjustment system 105 is the mechanical structure of the optical device. Next, the optical path structure will be described first.

[0033] In response to different testing requirements, the light source system 101 can be different light source systems, for example, it can be a bright field light source system, which projects a light beam vertically onto the surface of the sample to be tested, and projects the reflected light of the sample to be tested onto the scanning camera to produce a bright and high-contrast image; it can also be a dark field light source system, which projects a light beam onto the surface of the sample to be tested at a low angle, so that most of the reflected light beam will not be projected onto the scanning camera, thereby producing a dark field image with more obvious defects; a bright field light source system and a dark field light source system can also be used at the same time. The bright field light source system mainly includes a bright field light source, a first lens and a second lens. Among them, the light beam emitted by the bright field light source can become uniform and bright enough after passing through the first lens and the second lens to form a Kohler illumination system. In addition, a reflective device can be set in the bright field light source system to reflect the light beam emitted by the bright field light source system into other systems.

[0034] The line scanning system 102 includes a line scanning camera and a first spectroscopic device arranged in sequence. The line scanning camera is used to perform line scanning imaging on the sample to be tested to preliminarily scan out the defects of the sample to be tested; the first spectroscopic device is used to split the light beam emitted by the bright field light source system into two, and project them respectively to the line scanning system and subsequent other systems.

[0035] The area array system 103 includes an area array camera, which is used to perform surface scanning imaging on the sample to be tested, so as to further detect and re-judge the defects detected by the line scan. When the optical device includes an automatic focusing system, the area array system can be provided with a second beam splitter, which is used to split the light beam into two and project them to the area array camera and the automatic focusing system respectively.

[0036] The objective lens system 104 includes a plurality of objective lenses, for example, objective lenses with different magnifications. All objective lenses are arranged in the same objective lens system 104, and objective lenses with different magnifications are switched by the same objective lens converter (such as an objective lens turret). All systems share the same set of objective lens systems, so that the travel of the motion axis (i.e., the axis that drives the sample to be tested to move during detection) only needs to meet the size of the wafer diameter.

[0037] A third spectroscopic device is arranged above the objective lens system 104, which can split the light beam projected from the first spectroscopic device into two and project them to the area array system 103 and the objective lens system 104 respectively, and can also project the light beam reflected by the sample to be tested to the line scanning system 102 and the area array system 103 respectively.

[0038] The position adjustment system 105 includes a camera adjustment mechanism and a device adjustment mechanism. The camera adjustment mechanism is used to adjust the position of the line scan camera and / or the area array camera, for example, the rotation angle of the camera can be adjusted to improve the imaging quality. The device adjustment mechanism is used to adjust the position of the optical device as a whole, for example, the rotation angle of the optical device can be adjusted as a whole.

[0039] In addition, the optional automatic focusing system a includes an automatic focusing light source component, an automatic focusing detection component and an automatic focusing filter device. The automatic focusing light source component includes an infrared light source, a third lens and a fourth spectroscopic device, which is used to generate a light beam required for automatic focusing without interfering with the line scanning system and the area array system. The automatic focusing detection component is configured to generate a detection result for automatic focusing of the objective lens system based on the infrared light generated by the infrared light source. The automatic focusing detection component can perform automatic focusing by detecting light energy or by detecting an imaging shape. The automatic focusing filter device is arranged between the automatic focusing light source component and the automatic focusing detection component, and is used to filter out visible light to prevent visible light from interfering with the automatic focusing system.

[0040] Next reference Figure 2-5 The structure of the system used for the optical detection part in the optical device is explained based on the specific optical path structure.

[0041] like Figure 2 In the embodiment 1 shown, the optical device 1 includes a light source system 101, a line scanning system 102, a surface array system 103, an objective lens system 104 and an automatic focusing system a. It can be understood that in the actual detection process, the optical device 1 is arranged from top to bottom according to the direction of the arrow. First, the composition structure of each system is described.

[0042] The light source system 101 includes a bright field light source system 1011 and a dark field light source system 1012. The bright field light source system 1011 includes a bright field light source 1, a first lens 2, a second lens 3 and a reflector 4 arranged in sequence. The first lens 2 and the second lens 3 constitute a Kohler illumination system. In one embodiment, the focal length of the first lens 2 is 160nm, and the focal length of the second lens 3 is 10nm. The reflection band of the reflector 4 is 400nm~780nm (i.e., the visible light band) to ensure that only visible light is reflected into the subsequent system. The dark field light source system includes a dark field light source 5, which is arranged on the side of the sample to be tested 6 and emits a dark field illumination beam to the surface of the sample to be tested 6 at a certain angle. In one embodiment, the dark field light source 5 can use a white light LED lamp. It can be understood that the light beams emitted by the bright field light source system 1011 and the dark field light source system 1012 are both visible light.

[0043] The line scan system 102 includes a line scan camera 7, a first tube lens 8, and a first spectroscopic device 9, which are arranged in sequence. The area array system 103 includes an area array camera 10 and a second tube lens 11, which are arranged in sequence. When an automatic focusing system is provided in the optical device, the area array system 103 further includes a second spectroscopic device 12, which is arranged behind the second tube lens 11. Figure 2 As shown. In one embodiment, the first tube lens 8 and the second tube lens 11 both use tube lenses with a focal length of 200nm, and use a line scan camera of 8K5um, and a surface array camera with a resolution of 5120*5120 and a pixel size of 2.5*2.5um. The first spectrometer 9 and the second spectrometer 12 preferably use 55 splitter prisms to ensure that the light beam is vertically incident and vertically emitted when passing through the prism, so as to avoid the deflection of the light path caused by different light propagation media. In addition, the line scan system 102 has high requirements for accuracy for defect detection and is sensitive to the light path (that is, the light path needs to be as perpendicular as possible to the photosensitive surface of the line scan camera 7). The quality of the collected image seriously affects the calculation results of the algorithm, while the surface array system 103 is only used to re-inspect and re-judge the defects scanned by the line scan system 102, and is not very sensitive to the light path. Therefore, preferably, the line scan system is vertically arranged just above the sample to be tested 6, and the area array system 103 is horizontally arranged on the side of the sample to be tested 6, that is, the photosensitive surface of the line scan camera 7 is parallel to the measured surface of the sample to be tested 6, and the photosensitive surface of the area array camera 10 is perpendicular to the measured surface of the sample to be tested 6, so that the light beam reflected from the measured surface of the sample to be tested 6 can be directly projected vertically to the photosensitive surface of the line scan camera 7, thereby ensuring the verticality of the light path, such as Figure 2 shown.

[0044] The objective lens system 104 includes a plurality of objective lenses 13 and an objective lens turret 14. The plurality of objective lenses 13 may include bright and dark field objective lenses and interference objective lenses of different magnifications, for example, 2X (X means magnification), 5X, 10X, 20X bright and dark field objective lenses and 20X interference objective lenses (used by the area array system to collect interference images of the sample 6 to be tested, construct the three-dimensional morphology of the sample 6 to be tested, and perform size measurement). Correspondingly, the objective lens turret 14 uses a 6-hole objective lens turret. A third beam splitter 15 is arranged above the objective lens system 104 to split the light beam into two and project them to the objective lens system 104 and the second beam splitter 12 of the area array system 103, respectively.

[0045] In addition, the embodiment also integrates an automatic focusing system a. In the embodiment, the automatic focusing system a automatically focuses by analyzing the light energy received by the two detection units. The automatic focusing light source component of the automatic focusing system a includes an infrared light source 16, a third lens 17 and a fourth spectrometer 18. The use of the infrared light source 16 as the automatic focusing light source can prevent interference with the line scanning system and the area array system that use visible light imaging. In the embodiment, the infrared light source uses light in the wavelength band above 800nm, and preferably uses a 940nm infrared LED lamp. The automatic focusing detection component includes a first detection component and a second detection component. The first detection component includes a first detection unit 19, a first aperture 20 and a fourth lens 21 arranged in sequence, and the second detection component includes a second detection unit 22, a second aperture 23 and a fifth lens 24 arranged in sequence. Among them, the first detection unit 19 and the second detection unit 22 are photoelectric detectors that can detect light energy, and the first aperture 20 and the second aperture 23 are preferably small holes with a diameter of 0.4mm, and d is preferably 5mm. In order to meet the splitting requirements of visible light and infrared light at the same time, the splitting bands of the second splitter 12 and the third splitter 15 are preferably 400nm~1100nm, and since the infrared light does not need to pass through the first splitter 9, the splitting band of the first splitter 9 is 400nm~780nm. It can be understood that the infrared light source can also be replaced by a line light source, and the first aperture and the second aperture can be replaced by slits, so as to realize the automatic focusing function through line light.

[0046] In addition, in order to realize the automatic focusing function, the positions of the first aperture and the second aperture need to be set to a "conjugate position". Figure 3 As shown, the fourth lens 21 and the fifth lens 24 have the same focal length, the focus of the fourth lens 21 is P1, and the focus of the fifth lens 24 is P2. The first aperture 20 is set at a first distance D1 from the front end of the focus P1 (for the convenience of explanation, the side close to the first detection unit 19 is regarded as the front end, and the side close to the fourth lens 21 is regarded as the rear end, and the second detection component is the same), and the second aperture 23 is set at a second distance D2 from the rear end of the focus P2, wherein D1=D2=d. In summary, the positions of the two apertures are the focal positions P±d, and are therefore called conjugate positions. It can be understood that Figure 3 For the convenience of explaining the aperture position, the two detection components are placed in parallel. In fact, the physical positions of the two detection components are preferably as follows: Figure 2 As shown. And Figure 3 As a non-limiting implementation, only two apertures need to be set at conjugate positions based on the focus, and there is no limitation on the actual positions.

[0047] Since two detection components are included in this embodiment, in order to ensure that the light beams entering the fourth lens 21 and the fifth lens 24 are as similar as possible, a fifth optical splitter 25 is also required to be provided to split the light beam into two and project them to the first detection component and the second detection component respectively. In order to prevent visible light from interfering with the detection of the first detection unit 19 and the second detection unit 22, an automatic focusing filter 26 is also provided to filter out the visible light component in the light beam before the light beam enters the fourth lens 21 and the fifth lens 24. The automatic focusing filter 26 is preferably a long-wave pass filter to filter out light in the band below 800nm. In addition, since the infrared light generated by the infrared light source 16 introduced by the automatic focusing system may also affect the imaging of the line scan camera 7 and the area array camera 10, a first filter 27 can also be provided in the line scan system, and a second filter 28 can be provided in the area array system to filter out the infrared light component in the light beam before the light beam enters the line scan camera 7 and the area array camera 10. The first optical filter device 27 and the second optical filter device 28 are preferably short-wave pass filters to filter out light in the wavelength band above 800nm.

[0048] The above is a structural description of the optical detection part of the optical device in the first embodiment. Next, each optical path in the first embodiment is described to illustrate its working principle.

[0049] The light beam emitted from the bright field light source 1 forms a first light path, and the first light path is used to provide illumination to the sample to be tested 6. The first light path passes through the first lens 2, the second lens 3, and the reflector 4 in sequence, and then is reflected to the first spectrometer 9. After being split by the first spectrometer 9, one of the light beams is split by the third spectrometer 15 and projected to the objective lens 13, and finally projected to the surface of the sample to be tested 6. It can be understood that the dark field light source 5 directly projects the light beam to the surface of the sample to be tested 6 without passing through an optical device, and the subsequent light path is the same as that of the bright field light source, so it will not be repeated.

[0050] The surface of the sample 6 to be tested reflects the light beam of the first optical path (and / or the light beam projected by the dark field light source 5 to the surface of the sample 6 to be tested) back to the optical device, and forms a second optical path and a third optical path after being split by the third optical splitter 15. The second optical path is used for imaging of the line scan system, and the third optical path is used for imaging of the area array system. The second optical path passes through the first optical splitter 9, the first optical filter 27, and the first tube lens 8 in sequence, and is projected onto the imaging surface of the line scan camera 7 to perform defect detection on the sample 6 to be tested. The third optical path passes through the second optical splitter 12, the second optical filter 28, and the second tube lens 11 in sequence, and is projected onto the imaging surface of the area array camera 10 to re-inspect and re-judge the defects of the sample 6 to be tested.

[0051] The first optical path, the second optical path and the third optical path are used for the detection function of the sample 6 to be tested, namely the line scanning system and the area array system. Next, the fourth optical path, the fifth optical path and the sixth optical path used for the automatic focusing system are described.

[0052] The infrared light beam emitted by the infrared light source 16 forms a fourth light path. The fourth light path passes through the third lens 17, the fourth light splitter 18, the second light splitter 12 and the third light splitter 15 in sequence, and is projected onto the surface of the sample 6 to be tested.

[0053] The surface of the sample to be tested 6 reflects the light beam of the fourth light path back to the optical device, and then projects to the fifth light splitter 25 through the objective lens 13, the third light splitter 15, the second light splitter 12, the fourth light splitter 18, and the automatic focusing filter 26, and is divided into the fifth light path and the sixth light path through the fifth light splitter 25. The fifth light path is projected to the first detection unit 19 through the fourth lens 21 and the first aperture 20. Similarly, the sixth light path is projected to the second detection unit 22 through the fifth lens 24 and the second aperture 23. Although the fifth light splitter 25 is a semi-transparent and semi-reflective spectroscope, since the first aperture 20 and the second aperture 23 are set to a conjugate position, the light energy of the light beam projected to the first detection unit 19 and the second detection unit 22 is also different. Therefore, the relative distance between the sample to be tested 6 and the positive focus position of the objective lens can be calculated by analyzing the light energy of the first detection unit 19 and the second detection unit 22, and the objective lens is adjusted based on the relative distance to achieve rapid automatic focusing.

[0054] Figure 4 This is the second implementation of the optical device proposed in this application. Figure 3 The optical device shown is based on the optical path structure of Figure 4 The optical device 2 shown in the figure is additionally added with a differential interference system to realize the differential interference function. Specifically, based on the optical device 1, the optical device 2 further includes a polarizing device 29, a first film inspection device 30, a second film inspection device 31 and a Nomarski prism 32 shown in the dotted box.

[0055] like Figure 4As shown, the various components in the differential interference system are dispersed in different systems, the polarizing device 29 is arranged between the reflecting device 4 and the first spectroscopic device 9; the first film inspection device 30 is arranged between the first tube lens 8 and the first spectroscopic device 9, preferably between the first tube lens 8 and the first filter device 27; the second film inspection device 31 is arranged between the second tube lens 11 and the second spectroscopic device 12, preferably between the second tube lens 11 and the second filter device 28; the Nomarski prism 32 is arranged between the third spectroscopic device 15 and the objective lens 13; wherein the polarizing device 29, the first film inspection device 30 and the second film inspection device 31 are preferably polarizing plates, and the polarization directions of the first film inspection device 30 and the second film inspection device 31 are orthogonal to the polarization direction of the polarizing device 29. Through the above structure, differential interference scanning of the sample 6 to be tested can be realized, so that the ups and downs, concave and convex (i.e., "relief") of the sample 6 to be tested can be clearly seen through the collected image.

[0056] Figure 5 This is the third implementation mode of the optical device proposed in this application. Figure 3 The optical device shown is based on the optical path structure of Figure 5 The optical device shown will Figure 3 The autofocus system a shown is replaced by an autofocus system b with a simpler structure.

[0057] like Figure 5 As shown, the autofocus system b only replaces the autofocus detection components of the autofocus system a, including the four-quadrant detector 33, the cylindrical lens 34 and the sixth lens 35 arranged in sequence. Among them, the cylindrical lens 34 uses a cylindrical lens with a focal length of 300mm, and the sixth lens 35 uses a lens with a focal length of 200mm. Through the combination of the sixth lens 35 and the cylindrical lens 34, the shape of the light spot at the four-quadrant detector 33 can be changed. Figure 6 As shown, when the sample 6 to be tested is located at different positions, the four-quadrant detector 33 will generate light spots of different shapes. For example, when the sample 6 to be tested is located in front of the focal length, the generated pre-focus light spot is an ellipse in the horizontal direction; when the sample 6 to be tested is located after the focal length, the generated post-focus light spot is an ellipse in the vertical direction; when the sample 6 to be tested is exactly at the focal length, the generated positive focus light spot is a perfect circle. Therefore, automatic focusing can be achieved through a four-quadrant detector 33, simplifying the device and making the device structure more compact.

[0058] It is understandable that the above three methods are only non-limiting embodiments, which can be combined and deformed at will. For example, the second embodiment and the third embodiment can be combined to achieve the effects of differential interference scanning and simplified devices at the same time; the automatic focusing system in the three embodiments can also be removed, so that for example, the second spectroscopic device and the filter device in the line scanning system and the area array system can also be removed, so as to make the structure more compact.

[0059] The above is a description of the optical path structure of the optical device of this application. Figure 7-Figure 9 The mechanical structure of the optical device is described below. The mechanical structure mainly includes a position adjustment system, which adjusts the position of each component in the optical path structure to eliminate optical path deviations caused by installation errors, component errors, etc.

[0060] The position adjustment system mainly includes a camera adjustment structure and a device adjustment structure, wherein the line scan system and the area array system are respectively provided with a camera adjustment mechanism for adjusting the position (especially the rotation angle) of the line scan camera and / or the area array camera, so that the camera photosensitive surface is perpendicular to the light beam incident on the camera; the device adjustment mechanism is used to adjust the position of the optical device as a whole. The position adjustment system also includes some other devices for adjusting the position of the device, such as a ball screw for adjusting the position of the aperture, a rotating nut for adjusting the height of a detector seat provided with a detection unit and a lens seat provided with a lens, etc. Since these devices are conventional technical means in this field, this application mainly describes the camera adjustment mechanism and the device adjustment mechanism in detail. It can be understood that the camera adjustment structure principles of the line scan camera and the area array camera are the same, so they are described together.

[0061] Figure 7 This is a three-dimensional diagram of the camera adjustment mechanism (the bottom surface is the camera photosensitive surface). Figure 8 701 and 702. The first waist-shaped groove 703 ( Figure 7 The first waist-shaped groove 703 is provided with a first screw 705 ( Figure 7The second waist-shaped groove 704 is provided with a second screw 706, and the first screw 705 and the second screw 706 are used to connect the movable plate 701 and the fixed plate 702 together, and the tightness of the movable plate 701 and the fixed plate 702 is adjusted by adjusting the tightness of the two screws; the fixed plate 702 is provided with a first push-up mechanism 707 and a second push-up mechanism 708, which are used to push the movable plate 701 to rotate. The first push-up mechanism 707 and the second push-up mechanism 708 are preferably knob structures, and the movable plate 701 can be pushed to rotate by rotating the knob, thereby driving the camera disposed thereon to rotate. For example, when the movable plate 701 needs to rotate clockwise, the first push-up mechanism 707 is rotated, and when the movable plate 701 needs to rotate counterclockwise, the second push-up mechanism 708 is rotated.

[0062] like Figure 8 As shown, when the movable plate 701 rotates, the first screw 705 and the second screw 706 remain stationary relative to the fixed plate 702, and the first waist-shaped groove 703 and the second waist-shaped groove 704 move in a circle with the midpoint P between the first screw 705 and the second screw 706 as the center to reduce the friction between the waist-shaped groove and the screw; the first push mechanism 707 and the second push mechanism 708 also move in a circle with the midpoint P as the center, that is, their movement direction is the tangent direction of the circle with the midpoint P as the center, and the force applied is a tangential force, thereby avoiding the radial force component, thereby reducing the force required to push the movable plate 701 to rotate, and preventing the excessive friction from causing the device to wear and produce dust, affecting the dust-free environment. In addition, in order to reduce the friction between the waist-shaped groove and the screw as much as possible, the arcs on both sides of the waist-shaped groove are also arcs with the midpoint P as the center.

[0063] like Figure 7 As shown, in order to facilitate pushing, a protruding first pushing surface 709 and a second pushing surface 710 are also provided on the movable plate 701. In order to reduce the force required when the first pushing mechanism 707 and the second pushing mechanism 708 push the movable plate 701, the planes where the first pushing surface 709 and the second pushing surface 710 are located intersect at the midpoint P, and it is preferred that the first pushing mechanism 707 is perpendicular to the first pushing surface 709, and the second pushing mechanism 708 is perpendicular to the second pushing surface 710.

[0064] Fig. 9 Schematic diagram of an optical device with a device adjustment mechanism. As mentioned above, the optical device is usually arranged vertically, for example Figure 1The arrow directions in the figure are set from top to bottom. Therefore, the overall verticality of the optical device will have a great impact on the detection results. For example, when the optical device is tilted, the light path may be deflected, especially the light path entering the line scan system and the area array system may be deflected, resulting in poor imaging effect and affecting the detection results. Therefore, the present application also introduces a device adjustment mechanism to adjust the optical device as a whole. In one embodiment, the fixed axis of the optical device as a whole is usually located at the upper part, such as the fixed axis Q. The device adjustment mechanism may include two knobs located below the fixed axis Q, such as a first knob 901 and a second knob 902. When the optical device is tilted to the left, rotating the first knob 901 can push the optical device to rotate counterclockwise. When the optical device is tilted to the right, rotating the second knob 902 can push the optical device to rotate clockwise, so that the photosensitive surface of the line scan camera is parallel to the surface of the sample to be tested. In addition, in order to reduce the force required to be applied, the device adjustment mechanism can be set at a position farther away from the fixed axis Q based on the torque principle. It can be understood that, Fig. 9 The fixed axis Q and the installation positions of the first knob 901 and the second knob 902 shown are only examples, and any installation position that can adjust the position of the optical device can be used.

[0065] Next reference Fig.10 The steps of adjusting the position of the optical device using the position adjustment system are described in detail.

[0066] Step 1001, turn on the bright field light source to provide illumination. Since the imaging of the camera needs to be referred to when adjusting the position, illumination is required to enable the camera to form an image.

[0067] Step 1002, the line scan camera performs imaging, and the position of the line scan camera is adjusted based on the imaging of the line scan camera. When the imaging is not clear, it is determined that there is an angle between the line scan camera and the axis of motion of the sample to be tested, and the rotation angle of the line scan camera is adjusted by the camera adjustment mechanism so that the linear field of view is perpendicular to the axis of motion of the sample to be tested. When the imaging is tilted, it is determined that the photosensitive surface of the line scan camera is not parallel to the surface of the sample to be tested, and the rotation angle of the entire device is adjusted by the device adjustment mechanism so that the photosensitive surface of the line scan camera is parallel to the surface of the sample to be tested. It can be understood that since the line scan camera has higher requirements for the optical path, it is usually preferred to use the device adjustment mechanism to adjust the position of the line scan camera.

[0068] Step 1003: The area array camera performs imaging, and the position of the area array camera is adjusted based on the imaging of the area array camera. When the four corners of the area array camera imaging are not clear, the photosensitive surface of the area array camera is adjusted to be perpendicular to the wafer through the camera adjustment mechanism; when the image appears tilted on the display screen, the rotation angle of the camera is adjusted through the camera adjustment mechanism.

[0069] It is understandable that the above steps only describe the position adjustment of the line scan camera and the area array camera required for detection, and since the line scan camera has a higher accuracy requirement, it needs to be adjusted first. The positions of other components are mainly adjusted in relative height so that each component is exactly in the required optical path, so they can be adjusted at any time during the equipment preparation stage before starting the detection.

[0070] The above specific embodiments illustrate the implementation of the present application, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Although the description of the present application will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to the implementation. In addition, in order to avoid confusion or blurring the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0071] Furthermore, various operations will be described as multiple discrete operations in a manner that is most helpful for understanding the illustrative embodiments; however, the order of description should not be construed as implying that these operations are necessarily order dependent. In particular, these operations do not need to be performed in the order presented.

[0072] Unless the context dictates otherwise, the terms "comprising," "having," and "including" are synonymous. The phrase "A / B" means "A or B." The phrase "A and / or B" means "(A and B) or (A or B)."

[0073] As used herein, the term "module" or "unit" may refer to, be or include: an application specific integrated circuit (ASIC), an electronic circuit, a (shared, dedicated or group) processor and / or memory that executes one or more software or firmware programs, a combinational logic circuit and / or other suitable components that provide the described functionality.

[0074] In the accompanying drawings, some structural or method features are shown in a specific arrangement and / or order. However, it should be understood that such a specific arrangement and / or order may not be required. In some embodiments, these features may be arranged in a manner and / or order different from that shown in the illustrative drawings. In addition, the inclusion of structural or method features in a specific figure does not mean that such features are required in all embodiments, and in some embodiments, these features may not be included or may be combined with other features.

[0075] It should be understood that although the terms "first", "second", etc. may be used here to describe various units or data, these units or data should not be limited by these terms. These terms are used only to distinguish one feature from another. For example, without departing from the scope of the exemplary embodiment, a first feature may be referred to as a second feature, and similarly, a second feature may be referred to as a first feature.

[0076] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0077] While the present invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims

1. An optical device for wafer inspection, characterized in that: include: A light source system, including a bright field light source system and / or a dark field light source system; A line scanning system, comprising a line scanning camera and a first spectroscopic device arranged in sequence; Area array system, including area array camera; An objective lens system, comprising a plurality of objective lenses, wherein a third light splitting device is arranged above the objective lens system; The position adjustment system comprises a camera adjustment mechanism and a device adjustment mechanism, wherein the camera adjustment mechanism is used to adjust the position of the line scan camera and / or the area array camera, and the device adjustment mechanism is used to adjust the position of the optical device.

2. The optical device according to claim 1, characterized in that The bright field light source system includes a bright field light source, a first lens and a second lens.

3. The optical device according to claim 2, characterized in that The bright field light source system further includes a reflective device for reflecting the light beam generated by the bright field light source system to the first beam splitter device of the line scanning system.

4. The optical device according to claim 1, characterized in that The optical device further includes an automatic focusing system configured to automatically focus on the sample to be measured; the area array system further includes a second spectroscopic device.

5. The optical device according to claim 4, characterized in that The automatic focusing system comprises: An automatic focusing light source component, comprising an infrared light source, a third lens and a fourth light splitting device; an automatic focusing detection component configured to generate a detection result for automatic focusing of the objective lens system based on the infrared light generated by the infrared light source; The auto-focusing filter device is arranged between the auto-focusing light source component and the auto-focusing detection component, and is used for filtering out visible light.

6. The optical device according to claim 5, characterized in that The autofocus detection component includes a first detection component and a second detection component, the first detection component includes a first detection unit, a first aperture and a fourth lens arranged in sequence, and the second detection component includes a second detection unit, a second aperture and a fifth lens arranged in sequence; wherein the fourth lens has the same focal length as the fifth lens, the first aperture is arranged at a first distance from the front end of the focus of the fourth lens, and the second aperture is arranged at a second distance from the rear end of the focus of the fifth lens, and the first distance is equal to the second distance; The automatic focusing system further comprises a fifth beam splitter, which is used to project the light beam to the first detection component and the second detection component respectively.

7. The optical device according to claim 6, characterized in that The first detection unit and the second detection unit are photodetectors.

8. The optical device according to claim 5, characterized in that The automatic focusing detection component includes a four-quadrant detector, a cylindrical lens and a sixth lens which are arranged in sequence.

9. The optical device according to claim 5, characterized in that The line scanning system further includes a first tube lens, and the area array system further includes a second tube lens.

10. The optical device according to claim 9, characterized in that The line scan system further includes a first optical filter device, and the area array system further includes a second optical filter device.

11. The optical device according to claim 10, characterized in that The optical device further comprises a differential interference system, wherein the differential interference system comprises: A polarizing device, arranged between the light source system and the line scanning system; A first film inspection device is arranged between the first tube lens and the first filter device; A second film inspection device is arranged between the second tube lens and the second filter device; The Nomarski prism is arranged between the objective lens system and the third beam splitter.

12. The optical device according to claim 1, characterized in that The device adjustment mechanism is used to adjust the rotation angle of the optical device.

13. The optical device according to claim 1, characterized in that The camera adjustment mechanism comprises: The moving plate is provided with a first waist-shaped groove and a second waist-shaped groove; The fixed plate is provided with a first pushing mechanism and a second pushing mechanism, wherein the first pushing mechanism and the second pushing mechanism are used to push the movable plate to rotate; A first screw is disposed in the first waist-shaped groove and is used to connect the movable plate and the fixed plate; The second screw is disposed in the second waist-shaped groove and is used to connect the movable plate and the fixed plate; wherein, When the movable plate rotates, the first waist-shaped groove and the second waist-shaped groove make a circular motion with the midpoint between the first screw and the second screw as the center, and the first ejection mechanism and the second ejection mechanism make a circular motion with the midpoint as the center.

14. The optical device according to claim 13, characterized in that The movable plate includes a protruding first pushing surface and a second pushing surface, the first pushing mechanism is perpendicular to the first pushing surface, and the second pushing mechanism is perpendicular to the second pushing surface.

15. The optical device according to claim 14, characterized in that A line connecting the first ejection mechanism and the midpoint is perpendicular to a line connecting the second ejection mechanism and the midpoint.

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