An optical detection device and its control method

Abstract

The present invention relates to the field of optical detection technologies, and particularly to an optical detection device and a control method therefor. The optical detection device includes: a defect detection device, which includes a large defect avoidance system and an illumination system. The illumination system is configured to emit high-power illumination light to scan a sample. When the illumination system scans a large defect on the sample, the large defect avoidance system is configured to send a shutter closing signal to the illumination system to turn off the high-power illumination light, so that the large defect on the sample is avoided from being scanned by the high-power illumination light; an air purification device, which includes an optical machine chamber air flow field system, and the optical machine chamber air flow field system includes a first purging component that blows a first purging air flow towards the illumination system; wherein, when the large defect avoidance system sends the shutter closing signal, it also sends a first purging signal to the first purging component, and the first purging component that receives the first purging signal increases the air pressure of the first purging air flow. The present invention is at least beneficial to improving the performance of the optical detection device.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and in particular relates to an optical detection device and a control method thereof. Background Art

[0002] The existence of defects on a wafer may lead to chip failure, and it is necessary to detect them during the manufacturing process. Detecting wafer defects based on dark-field scattering is an optical defect detection method. It realizes defect judgment by collecting the scattered light on the wafer surface, and has the advantages of high sensitivity and fast speed, and is widely used in wafer detection.

[0003] A high-precision dark-field scattering wafer defect detection system mainly uses a high-power, short-wavelength laser as the detection light source. Increasing the illumination power of the detection light source can increase the scattered signal intensity of defects of the same size, and thus increase the detection sensitivity. However, a high illumination power also poses higher requirements on the purification system of the detection device. Although an air purification system is usually provided in the detection device, pollution such as dust particles still inevitably exists and falls on optical components such as lenses. Under the irradiation of high illumination power, the pollution will generate a thermal effect, which may damage the film layer on the optical component, resulting in a decline or even failure of the performance of the detection device. To address the pollution problem, related technologies introduce a device for purging the optical components in the air purification system, which can effectively reduce the pollution of the optical components. However, purging with a small pressure is not strong enough to remove some pollution, and purging with a large pressure will cause the optical components to vibrate, and then the illumination light will vibrate accordingly, resulting in a decline in the detection positioning accuracy.

[0004] Therefore, how to clean the optical components on the basis of minimizing the impact on the parameters of dark-field scattering wafer defect detection is a key problem to be solved in the wafer defect detection system. Summary of the Invention

[0005] In view of this, the present invention aims to provide an optical detection device and a control method thereof, which are at least beneficial to improving the performance of the optical detection device.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] On the one hand, the present invention provides an optical detection device, comprising: a defect detection device, which includes a large defect avoidance system and an illumination system. The illumination system is used to emit high-power illumination light to scan a sample. When the illumination system scans a large defect on the sample, the large defect avoidance system is used to send a shutter closing signal to the illumination system to turn off the high-power illumination light, so that the large defect on the sample is avoided from being scanned by the high-power illumination light; an air purification device, which includes an optical machine chamber air flow field system, and the optical machine chamber air flow field system includes a first purging component for blowing a first purging air flow to the illumination system; wherein, when the large defect avoidance system sends the shutter closing signal, it also sends a first purging signal to the first purging component, and the first purging component receiving the first purging signal increases the air pressure of the first purging air flow.

[0008] Further, the first purging component includes a first control unit and a first air intake component. The first air intake component is used to blow the first purging air flow, and the first control unit is used to receive the first purging signal and control the first air intake component to increase the air pressure of the first purging air flow.

[0009] Further, the first purging component further includes a first exhaust component. The air intake volume of the first air intake component per unit time is less than the exhaust volume of the first exhaust component.

[0010] Further, the optical detection device further includes an optical machine chamber housing. The optical machine chamber housing encloses an optical machine chamber. The illumination system is arranged in the optical machine chamber. The first exhaust component includes a first exhaust duct and a first exhaust fan. The optical machine chamber is communicated with the first end of the first exhaust duct through a first exhaust port, and the other end of the first exhaust duct is connected to the first exhaust fan.

[0011] Further, the illumination system includes a light source component, a power regulation component, a spot stabilization component, a spot modulation component and a signal collection component.

[0012] Further, the illumination system includes a plurality of optical elements, and the optical machine chamber air flow field system includes a plurality of first air intake components. One first air intake component is used to purge one or more optical elements.

[0013] Further, the optical element is fixed in the optical machine chamber by a damping structure.

[0014] Further, the damping structure includes a main body part and a bearing part. The bearing part is connected to the main body part through a spring. The bearing part is used to arrange the optical element, and the main body part is arranged in the optical machine chamber.

[0015] Further, the first purging component has a stable purging mode and an instantaneous purging mode. The air pressure of the first purging air flow in the instantaneous purging mode is greater than the air pressure of the first purging air flow in the stable purging mode. When the high-power illumination light is turned on, the first purging component is in the stable purging mode, and at least the first purging component receiving the first purging signal is in the instantaneous purging mode.

[0016] Further, the lighting system further includes a beam power and quality monitoring unit, which is used to monitor the optical power of the illumination light or the spot distribution of the illumination light. When the optical power of the illumination light is abnormal or the spot distribution of the illumination light is abnormal, the beam power and quality monitoring unit sends a second purge signal to the first purge assembly, and the first purge assembly that receives the second purge signal and the first purge signal enters the instantaneous purge mode.

[0017] Further, the first purge assembly has N instantaneous purge modes, and the air pressure of the first purge air flow corresponding to the N instantaneous purge modes increases. When the first purge assembly purges the lighting system in an instantaneous purge mode with a lower air pressure, if the first purge assembly still receives the second purge signal, then when the first purge assembly receives the first purge signal again, it purges the lighting system in an instantaneous purge mode with a higher air pressure.

[0018] Further, the beam power and quality monitoring unit includes: a detection unit, which is used to obtain the optical signal formed by the optical element in the lighting system processing the illumination light; a processing unit, which is used to judge whether the optical power of the illumination light is abnormal or judge whether the spot distribution of the illumination light is abnormal based on the optical signal.

[0019] Further, the detection unit includes: an optical signal detection element and a control element. The optical signal detection element is used to obtain the optical signal, and the control element is used to control the optical signal detection element to cut into or out of the transmission optical path of the optical signal.

[0020] Further, the detection unit includes: an optical signal detection element and a beam splitting element. The beam splitting element is arranged on the transmission optical path of the optical signal to split the optical signal into a first optical signal and a second optical signal. The transmission directions of the first optical signal and the second optical signal are different. The optical signal detection element receives the first optical signal to detect the illumination light, and the second optical signal is used for sample scanning.

[0021] Further, the defect detection device further includes a scanning detection system, which is used to carry the sample to move to realize the detection of different positions of the sample; the air purification device further includes a detection chamber air flow field system, and the detection chamber air flow field system at least includes a second purge assembly that blows a second purge air flow to the scanning detection system.

[0022] Further, the second purge assembly includes a second control unit, a second air intake assembly and a second air exhaust assembly. The second control unit is used to control the air intake volume of the second air intake assembly and control the air exhaust volume of the second air exhaust assembly, so that the air intake volume of the second air intake assembly per unit time is equal to the air exhaust volume of the second air exhaust assembly.

[0023] Further, the optical detection device further includes a detection housing that encloses a detection cavity. The scanning detection system is disposed in the detection cavity. The second exhaust assembly includes a second exhaust duct and a second exhaust fan. The detection cavity communicates with the first end of the second exhaust duct through a second exhaust opening, and the other end of the second exhaust duct is connected to the second exhaust fan.

[0024] Further, the second intake assembly includes a second intake duct and a wind-equalizing structure. The wind-equalizing structure is disposed at one end of the second intake duct extending into the detection cavity and is located above the sample. The second purge air flow is blown out from the wind-equalizing structure through the second intake duct, and the direction of the second purge air flow blown out from the wind-equalizing structure is parallel to the direction of the sample surface.

[0025] Further, the wind-equalizing structure includes a wind-equalizing grille and a sector-shaped wind-equalizing portion. The side surface of the second intake duct connected to the wind-equalizing structure has an air outlet. The wind-equalizing grille is arranged at intervals along the circumferential direction of the second intake duct at the air outlet. The sector-shaped wind-equalizing portion has a wind-equalizing cavity that communicates with the air outlet. The side surface of the sector-shaped wind-equalizing portion away from the air outlet has a plurality of wind-equalizing holes. The second purge air flow blown out from the air outlet flows into the detection cavity through the wind-equalizing holes after passing through the wind-equalizing cavity.

[0026] On the other hand, the present invention provides a control method for an optical detection device, including: providing the above-mentioned optical detection device, the optical detection device includes a defect detection device and an air purification device, the defect detection device includes a large defect avoidance system and a lighting system, the air purification device includes an optical machine chamber wind field system, and the optical machine chamber wind field system includes a first purge assembly for blowing a first purge air flow to the lighting system; the control method of the optical detection device includes: when the lighting system scans a large defect on the sample, using the large defect avoidance system to send a shutter closing signal to the lighting system to turn off the high-power illumination light, so that the large defect on the sample avoids the scanning of the high-power illumination light; wherein, when the large defect avoidance system sends the shutter closing signal, it also sends a first purge signal to the first purge assembly, and the first purge assembly receiving the first purge signal increases the air pressure of the first purge air flow.

[0027] Compared with the prior art, the present invention can achieve the following beneficial effects: The optical detection device provided in the embodiment of the present invention is usually a wafer dark field defect detection device, which includes an air purification device. The air purification device includes an optical machine chamber wind field system, and the optical machine chamber wind field system is used for air purification of the lighting system to solve the problem that the pollution in the optical machine chamber during detection falls on the optical elements, causing light source fluctuations or damage to the optical elements. The optical machine chamber wind field system includes a first purge assembly. The first purge assembly and the large defect avoidance system act jointly. When a large defect is encountered in the dark field detection and the high-power illumination light is turned off and the detection is skipped, an instantaneous large-pressure purge is performed in the optical machine chamber, increasing the ability to remove the pollution on the optical elements and avoiding the influence of the jitter caused by the purge on the lighting system, and solving the problem that the detection accuracy decreases due to the purge. Brief Description of the Drawings

[0028] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0029] Figure 1 is a modular schematic diagram of the optical detection device according to an embodiment of the present invention;

[0030] Figure 2 is a partial structural schematic diagram of the optical detection device according to an embodiment of the present invention;

[0031] Figure 3 is a structural schematic diagram of the power regulation component according to an embodiment of the present invention;

[0032] Figure 4 is a three-dimensional structural schematic diagram of the damping structure according to an embodiment of the present invention;

[0033] Figure 5 is a side schematic diagram of the damping structure according to an embodiment of the present invention;

[0034] Figure 6 is a structural schematic diagram of the air distribution structure according to an embodiment of the present invention;

[0035] Figure 7 is a spot diagram of the optical signal formed by the optical element processing light obtained by the detection unit according to an embodiment of the present invention;

[0036] Figure 8 is Figure 7 a partial enlarged view of the spot shown;

[0037] Figure 9 is Figure 7 a curve diagram of the optical signal intensity distribution along the short side direction at the position of X = a in the long side direction of the spot shown;

[0038] Figure 10 is Figure 7 a curve diagram of the optical signal intensity distribution along the long side direction of the spot shown. Detailed Description of the Invention

[0039] After analysis, it is found that for the pollution problem in the wafer inspection equipment in the prior art, the effective solutions in the related technologies mainly include the following two categories. The first category is to perform atmospheric pressure purging when the equipment is not in inspection. When the wafer inspection result is abnormal, this method can only stop the equipment to clean the pollution, and then perform inspection after cleaning the pollution. Therefore, it has an impact on the equipment throughput. The second category is to improve the intake component to rectify the purging gas generated by it and reduce the jitter generated by the purging gas. However, the limit of solving the jitter by this method is limited, and the jitter cannot be completely eliminated.

[0040] To solve the above problems, an embodiment of the present invention provides an optical inspection equipment, which does not need to stop the equipment for purging and can avoid the impact of the jitter generated by purging on the inspection accuracy.

[0041] In order to make the purpose, technical solution and advantages of the present invention clearer, the following further details the present invention in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0042] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0043] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0044] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0045] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0046] Referring to Figure 1 , the optical detection device includes: a defect detection device, the defect detection device includes a large defect avoidance system 11 and an illumination system 10. The illumination system 10 is used to emit high-power illumination light to scan the sample. When the illumination system 10 scans a large defect on the sample, the large defect avoidance system 11 is used to send a shutter closing signal to the illumination system 10 to turn off the high-power illumination light, so that the large defect on the sample is avoided from being scanned by the high-power illumination light; an air purification device, the air purification device includes an optical machine chamber 101 wind field system, and the optical machine chamber 101 wind field system includes a first purge component that blows a first purge air flow to the illumination system 10; wherein, when the large defect avoidance system 11 sends a shutter closing signal, it also sends a first purge signal to the first purge component, and the first purge component that receives the first purge signal increases the air pressure of the first purge air flow.

[0047] The sample involved in the embodiment of the present invention is usually a semiconductor substrate such as a wafer or a chip used to form a chip.

[0048] The defect detection device is at least used to realize the dark field defect detection of the wafer. It should be noted that for a wafer defect detection device based on dark field scattering, high-power illumination light can improve the signal intensity, but it may also bring thermal damage problems. According to the different thermal damage objects, thermal damage can generally be divided into the following two categories:

[0049] Category 1: Damage caused by the absorption of illumination light and heat generation on the surface of the wafer under test. This kind of thermal damage will directly lead to the damage of the sample under test. The higher the illumination light power or the larger the defect, the more obvious the thermal effect and the greater the possibility of damage. When such large defects that can cause thermal damage exist, the size and position information of the large defect can be obtained in the low-power illumination mode. High-power illumination may instead cause damage to the sample. To prevent such damage, a large defect avoidance system 11 can be set in the dark-field defect detection device. Before formally detecting with high-power illumination light, the large defect avoidance system 11 first uses low-power illumination light for pre-inspection to obtain the size and position information of the large defect, and pre-judges the large defects that may cause damage. When performing high-power scanning detection and scanning to the positions of these specified large defects, the large defect avoidance system 11 sends a shutter closing signal to the illumination system 10 to quickly turn off the illumination light by operating the shutter of the illumination system 10, skipping the detection of these large defects. There are various implementation methods for the large defect avoidance system 11 provided in the embodiments of the present invention. For example, the large defect avoidance system 11 includes two parallel detection systems, one for low-power pre-scanning and the other for high-power detection; or, the same detection system is scanned twice, the first time with low-power illumination light and the second time with high-power illumination light. The embodiments of the present invention do not limit the specific structure of the large defect avoidance system 11.

[0050] Category 2: Contamination falls on the optical elements of the illumination system 10, and the contamination absorbs the illumination light and causes damage to the optical elements. Although this kind of damage will not damage the sample, it will cause changes in the illumination conditions and affect the detection parameters. In view of this problem, the present invention combines with the large defect avoidance system 11 to control the pressure of the first purge air flow blown by the first purge assembly of the air flow system of the optical machine chamber 101, and instantaneously purges the optical elements with atmospheric pressure while the large defect avoidance system 11 gives a shutter closing signal, purging the contamination on the optical elements, and purging within the time when the illumination light is turned off, reducing the influence of the jitter caused by purging on the detection accuracy and avoiding the influence of purging on the throughput of the equipment.

[0051] In some embodiments, the first purge assembly includes a first control unit and a first air intake assembly 110. The first air intake assembly 110 is used to blow the first purge air flow to the illumination system, and the first control unit is used to receive the first purge signal and control the first air intake assembly 110 to increase the air pressure of the first purge air flow.

[0052] In some embodiments, the first purge assembly further includes a first exhaust assembly. The air intake volume of the first air intake assembly 110 per unit time is less than the exhaust volume of the first exhaust assembly, so that the optical machine chamber 101 where the illumination system is located presents a slightly negative pressure state.

[0053] In some embodiments, within a unit time, the air intake volume of the first air intake assembly 110 is slightly less than the air exhaust volume of the first air exhaust assembly.

[0054] In some embodiments, referring to Figure 2 , the optical detection device further includes an optical machine chamber housing 100. The optical machine chamber housing 100 encloses an optical machine chamber 101. The illumination system 10 is disposed within the optical machine chamber 101. The first air exhaust assembly includes a first air exhaust pipe 111 and a first air exhaust fan 112. The optical machine chamber 101 communicates with the first end of the first air exhaust pipe 111 through a first air exhaust port. The other end of the first air exhaust pipe 111 is connected to the first air exhaust fan 112. The first air exhaust fan 112 continuously exhausts air to discharge the gas within the optical machine chamber 101 to the outside of the device.

[0055] In some embodiments, the first air intake assembly 110 includes a first air intake pipe and a first purging end. The first air intake pipe is configured to introduce purified clean air to the first purging end, and the first purging end is configured to blow a first purging gas to an optical element.

[0056] In some embodiments, referring to Figure 1 , the illumination system 10 includes a light source assembly, a power regulation assembly, a spot stabilization assembly, a spot modulation assembly, and a signal collection assembly. The light source assembly, the power regulation assembly, the spot stabilization assembly, the spot modulation assembly, and the signal collection assembly cooperate with each other to complete a series of processes such as the generation, stabilization, modulation, and signal light collection of illumination light. These components mainly include active optical elements such as lasers and passive optical elements such as optical lenses, mirrors, and polarizers.

[0057] In some embodiments, each component in the illumination system 10 is correspondingly provided with one or more first purging assemblies. The first purging end of the first purging assembly is aligned with the irradiation location of a key optical element. Taking the power regulation assembly as an example for illustration, referring to Figure 3 , the power regulation assembly corresponds to two first air intake assemblies 110 and one first air exhaust assembly. The power regulation assembly includes a first mirror frame 160 and a second mirror frame 161. The first mirror frame is used to mount a first optical element, and the second mirror frame is used to mount a second optical element. One of the two first air intake assemblies 110 is configured to purge the first optical element, and the other first air intake assembly 110 is configured to purge the second optical element. The first optical element and the second optical element are disposed within a closed cavity. In order to reduce the vibration of the optical element caused by instantaneous large-pressure purging, the first mirror frame and the second mirror frame can adopt the damping structures shown in Figure 4 and Figure 5 so that the optical element directly purged by the first purging end is in a critically damped state during the purge of a large air flow.

[0058] In some embodiments, the optical element is fixed in the optical engine housing 101 by a damping structure. In this way, it can be ensured that the optical element quickly returns to the equilibrium position after being purged by the first purge air flow with a relatively large air pressure.

[0059] In some embodiments, the damping structure includes a main body portion 141 and a bearing portion 140. The bearing portion 140 is connected to the main body portion 141 by a spring 144. The bearing portion 140 is used to arrange the optical element, and the main body portion 141 is arranged in the optical engine housing 101.

[0060] Specifically, referring to Figure 4 and Figure 5 , the damping structure can be provided with a plurality of springs 144. For example, three springs 144 can be provided. By cooperating with the rotating nut 143, the stretching degree of the spring 144 can be changed, and the angle of the loaded optical element can be precisely adjusted from three angles. Furthermore, arbitrary fine adjustment of the three-dimensional angle and spatial position of the optical element can be realized. The thickness of the spring 144 can be selected according to the wind pressure reaching the optical element during purging with a large pressure, so as to realize the damping control of the optical element.

[0061] In some embodiments, the lighting system 10 includes a plurality of optical elements, and the wind field system of the optical engine housing 101 includes a plurality of first air intake components 110. One first air intake component 110 is used to purge one or more optical elements.

[0062] It should be noted that for the optical engine housing 101, except for the light inlet and the light outlet, the optical engine housing 101 is sealed and not connected to the outside, presenting a nearly independent chamber.

[0063] In some embodiments, the first purge component has a stable purge mode and an instantaneous purge mode. The air pressure of the first purge air flow in the instantaneous purge mode is greater than the air pressure of the first purge air flow in the stable purge mode. When the high-power illumination light is turned on, the first purge component is in the stable purge mode, and the first purge component that receives at least the first purge signal is in the instantaneous purge mode.

[0064] In some embodiments, the lighting system 10 further includes a beam power and quality monitoring unit. The beam power and quality monitoring unit is used to monitor the optical power of the illumination light or the spot distribution of the illumination light. When the optical power of the illumination light is abnormal or the spot distribution of the illumination light is abnormal, the beam power and quality monitoring unit sends a second purge signal to the first purge component. The first purge component that receives the second purge signal and the first purge signal enters the instantaneous purge mode.

[0065] The beam power and quality monitoring unit is arranged in the spot modulation system. When it is detected that the illumination light power is abnormal or the spot distribution of the illumination light is abnormal, it may be due to the abnormal light power or spot caused by dust and other contaminants on the optical elements. Therefore, detecting the abnormality can be used as a condition to trigger the instantaneous purging mode with a relatively high air pressure. That is to say, in some embodiments, the instantaneous purging mode is not switched on during large defect avoidance. The instantaneous purging mode will be switched on only when large defect avoidance is enabled and the spot modulation system detects an abnormality in the illumination light.

[0066] In some embodiments, the first purging assembly has N instantaneous purging modes, and the air pressure of the first purging air flow corresponding to the N instantaneous purging modes increases. After the first purging assembly purges the illumination system 10 in an instantaneous purging mode with a relatively low air pressure, if the first purging assembly still receives the second purging signal, then when the first purging assembly receives the first purging signal again, it will purge the illumination system 10 in an instantaneous purging mode with a relatively high air pressure. That is to say, when the quality of the illumination light still has not been restored after purging in the low-order mode, the purging mode with a higher air pressure will be switched on next time.

[0067] In some embodiments, the beam power and quality monitoring unit includes: a detection unit, which is used to obtain the optical signal formed by the optical element in the illumination system 10 processing the illumination light; a processing unit, which is used to judge whether the light power of the illumination light is abnormal or judge whether the spot distribution of the illumination light is abnormal based on the optical signal.

[0068] In some embodiments, the detection unit includes: an optical signal detection element and a control element. The optical signal detection element is used to obtain the optical signal, and the control element is used to control the optical signal detection element to cut into or cut out the transmission optical path of the optical signal.

[0069] In an embodiment of the present invention, when the optical signal detection element is located on the transmission optical path of the optical signal, the optical signal is vertically irradiated onto the optical signal detection element to improve the accuracy of obtaining the optical signal by using the optical signal detection element.

[0070] Specifically, in an embodiment of the present invention, the optical element is a reflective optical element. The optical signal detection element is located on the transmission optical path of the reflected optical signal formed by the light emitted by the reflective optical element and is fixedly connected to the control element; in another embodiment of the present invention, the optical element is a transmissive optical element. The optical signal detection element is located on the transmission optical path of the transmitted optical signal formed by the light emitted by the transmissive optical element and is fixedly connected to the control element.

[0071] In some embodiments, the detection unit includes: an optical signal detection element and a beam splitting element. The beam splitting element is disposed on the transmission optical path of the optical signal to split the optical signal into a first optical signal and a second optical signal. The transmission directions of the first optical signal and the second optical signal are different. The optical signal detection element receives the first optical signal to detect the illumination light, and the second optical signal is used for sample scanning. That is, the normal operation of the optical element is ensured by using the second optical signal. Thus, it is beneficial to further reduce the influence of the process of the optical signal detection element acquiring the optical signal on the normal operation of the optical element.

[0072] In some embodiments of the present invention, the detection unit includes an optical signal detection element and a target element. The target element is located on the transmission optical path of the optical signal, and the optical signal acquired by the optical signal detection element is the optical signal formed by the optical element processing the light beam irradiating on the target element.

[0073] Optionally, in an embodiment of the present invention, the optical signal detection element obtains the optical signal formed by the optical element processing the light beam on the target object based on the scattered signal formed by the optical signal formed by the optical element processing the light beam irradiating on the target element. Optionally, in an embodiment of the present invention, the target element is a wafer, and the optical signal acquired by the optical signal detection element is the scattered optical signal formed by the optical signal formed by the optical element processing the light beam irradiating on the wafer. However, the present invention does not limit this, and it depends on the specific situation.

[0074] Specifically, as Figure 7 shown, Figure 7 is the spot pattern of the optical signal formed by the optical element processing the light beam acquired by the detection unit irradiating on the target element. Among them, the X direction is defined as the long side direction of the spot, and the Y direction is defined as the short side direction of the spot. Figure 8 is Figure 7 a partial enlarged view of Figure 7 In the spot pattern shown, cross-sections are taken at various positions in the long side direction of the spot. For example, the spot is intercepted along the Figure 8 shown white line. By analogy, the optical signal intensity distribution curves in the short side direction at various positions in the long side direction of the spot can be obtained. As Figure 9 shown, on this basis, the optical signal intensity distribution curve in the long side direction of the spot can be further obtained. As Figure 10 shown. The formula definition of the spot uniformity is:

[0075] ;

[0076] wherein, I max is the maximum optical signal intensity of the spot, and I minis the minimum optical signal intensity of the light spot. It can be seen from the above formula that on the basis of Figure 10 having obtained the maximum optical signal intensity of the light spot, by setting the light spot uniformity, the minimum optical signal intensity satisfying the preset uniformity in the light spot can be obtained, and then the size of the region satisfying the preset uniformity in the light spot can be obtained. Therefore, in the embodiments of the present invention, it is possible to judge whether the light spot distribution of the illumination light is abnormal according to the length of the region satisfying the preset uniformity in the light spot of the optical signal formed by the optical element processing the light, and / or the width of the light spot region. When the length of the region satisfying the preset uniformity in the light spot of the optical signal formed by the optical element processing the light is less than the first preset value, and / or the width of the light spot region is greater than the second preset value, it indicates that there may be contamination on the optical element and the detection accuracy cannot be guaranteed. Among them, the present invention does not limit the first preset value and the second preset value, and can be specifically set according to the needs of the user and the detection accuracy requirements of the optical detection device and other situations.

[0077] In some embodiments, referring to Figure 1 , the defect detection device further includes a scanning detection system for carrying the sample to move to achieve detection of different positions of the sample; the scanning detection system is mainly faced with the above-mentioned first type of damage; the air purification device further includes a detection chamber air flow field system for purifying the air of the scanning detection system, and the detection chamber air flow field system at least includes a second purging component for blowing a second purging air flow to the scanning detection system.

[0078] In some embodiments, the second purging component includes a second control unit, a second air intake component 120, and a second exhaust component. The second control unit is used to control the air intake volume of the second air intake component 120 and the exhaust air volume of the second exhaust component, so that the air intake volume of the second air intake component 120 per unit time is equal to the exhaust air volume of the second exhaust component.

[0079] For the scanning detection chamber 131, the second air intake component 120 does not directly purge the sample and the device components, but through the second control unit, ensures that the air intake volume is equal to the exhaust air volume per unit time, so that the scanning detection chamber 131 presents a zero-pressure structure.

[0080] In some embodiments, referring to Figure 2 , the optical detection device further includes a detection housing 130. The detection housing 130 encloses a detection chamber 131. The scanning detection system is arranged in the detection chamber 131. The second exhaust component includes a second exhaust duct 121 and a second exhaust fan 122. The detection chamber 131 is communicated with the first end of the second exhaust duct 121 through a second exhaust port, and the other end of the second exhaust duct 121 is connected to the second exhaust fan 122.

[0081] In some embodiments, referring to Figure 6, the second air intake assembly 120 includes a second air inlet pipe and a wind homogenizing structure. The wind homogenizing structure is arranged at one end of the second air inlet pipe extending into the detection chamber 131, and the wind homogenizing structure is located above the sample. The second purging air flow blows out from the wind homogenizing structure through the second air inlet pipe, and the direction of the second purging air flow blowing out from the wind homogenizing structure is parallel to the direction of the sample surface.

[0082] In some embodiments, the wind homogenizing structure includes a wind homogenizing grille 153 and a fan-shaped wind homogenizing portion 150. The side surface of the end of the second air inlet pipe connected to the wind homogenizing structure has an air outlet. The wind homogenizing grille 153 is arranged at the air outlet at intervals along the circumferential direction of the second air inlet pipe. The fan-shaped wind homogenizing portion 150 has a wind homogenizing cavity 152. The wind homogenizing cavity 152 is communicated with the air outlet. The side surface of the fan-shaped wind homogenizing portion 150 away from the air outlet has a plurality of wind homogenizing holes 151. The second purging air flow blown out from the air outlet flows into the detection chamber 131 through the wind homogenizing holes 151 after passing through the wind homogenizing cavity 152.

[0083] In this way, a stable laminar flow protection can be formed on the scanning surface, and the air flow disturbance in the remaining space is small, so that particle contamination is not easily excited, and the risk of contaminating the sample is reduced.

[0084] The present invention also provides a control method for an optical detection device, including: providing the optical detection device according to any one of the above, the optical detection device includes a defect detection device and an air purification device, the defect detection device includes a large defect avoidance system 11 and an illumination system 10, the air purification device includes an optical machine chamber 101 wind field system, and the optical machine chamber 101 wind field system includes a first purging assembly for blowing a first purging air flow to the illumination system 10; the control method for the optical detection device includes: when the illumination system 10 scans a large defect on the sample, using the large defect avoidance system 11 to send a shutter closing signal to the illumination system 10 to turn off the high-power illumination light, so that the large defect on the sample avoids the scanning of the high-power illumination light; wherein, when the large defect avoidance system 11 sends the shutter closing signal, it also sends a first purging signal to the first purging assembly. The first purging assembly receiving the first purging signal increases the air pressure of the first purging air flow. After turning off the high-power illumination light to skip scanning the large defect on the sample, the shutter will be opened to continue scanning the sample along the scanning path with the high-power illumination light. While opening the shutter, the air pressure of the first purging air flow is reduced, that is, the instantaneous purging mode is turned off, and it is restored to normal purging.

[0085] In the optical detection device provided by the present invention, when the large defect avoidance system 11 reaches the large defect position, it simultaneously gives a shutter closing signal and a first purging signal. At this time, increasing the air pressure of the first purging air flow can achieve the effect of cleaning and purging the optical elements. Moreover, since no light passes through the illumination system 10 when the shutter is closed, the jitter of the optical elements caused by strong wind will not affect the detection accuracy of the optical detection device. In addition, adding a damping structure can accelerate the elimination of jitter, and it will not affect the optical detection after the shutter is opened after passing through the large defect area, achieving the effect of enhancing the cleaning of the optical elements by strong wind without affecting the optical detection. In addition, during detection, strong wind purging and cleaning are realized, improving the efficiency and avoiding affecting the throughput of the device.

[0086] It should be understood that various forms of the processes shown above can be used, with steps reordered, added, or deleted. For example, the steps recited in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and no limitation is made herein.

[0087] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An optical detection device, characterized in that: include: A defect detection device, the defect detection device comprising a large defect avoidance system and an illumination system, the illumination system being used to emit high-power illumination light to scan a sample, and when the illumination system scans a large defect on the sample, the large defect avoidance system being used to send a shutter closing signal to the illumination system to close the high-power illumination light, so that the large defect on the sample avoids the scanning of the high-power illumination light; An air purification device, the air purification device comprising an optical machine room wind farm system, the optical machine room wind farm system comprising a first purge component that blows a first purge airflow toward the lighting system; Wherein, the large defect avoidance system sends the shutter closing signal and also sends a first purge signal to the first purge component. The first purge component that receives the first purge signal increases the pressure of the first purge airflow.

2. The optical detection device according to claim 1, characterized in that: The first purge assembly includes a first control unit and a first air intake assembly, the first air intake assembly is used to blow the first purge airflow, and the first control unit is used to receive the first purge signal and control the first air intake assembly to increase the air pressure of the first purge airflow.

3. The optical detection device according to claim 2, characterized in that: The first purge component also includes a first exhaust component. In a unit time, the air intake volume of the first air intake component is smaller than the air exhaust volume of the first exhaust component.

4. The optical detection device according to claim 3, characterized in that: The optical detection equipment also includes an optical machine room shell, which encloses an optical machine room. The lighting system is arranged in the optical machine room. The first exhaust component includes a first exhaust duct and a first exhaust fan. The optical machine room is connected to the first end of the first exhaust duct through a first exhaust port, and the other end of the first exhaust duct is connected to the first exhaust fan.

5. The optical detection device according to claim 4, characterized in that: The lighting system includes a light source component, a power regulation component, a light spot stabilization component, a light spot modulation component and a signal collection component.

6. The optical detection device according to claim 4, characterized in that: The lighting system includes a plurality of optical elements, and the optical chamber wind farm system includes a plurality of first air intake components, one of the first air intake components being used to achieve purging of one or more of the optical elements.

7. The optical detection device according to claim 6, characterized in that: The optical element is fixed in the optical machine chamber by using a damping structure.

8. The optical detection device according to claim 7, characterized in that: The damping structure includes a main body and a bearing part, the bearing part is connected to the main body through a spring, the bearing part is used to set the optical element, and the main body is set in the optical machine chamber.

9. The optical detection device according to claim 1, characterized in that: The first purge component has a stable purge mode and an instantaneous purge mode. The air pressure of the first purge airflow in the instantaneous purge mode is greater than the air pressure of the first purge airflow in the stable purge mode. When the high-power lighting light is turned on, the first purge component is in the stable purge mode. At least the first purge component that receives the first purge signal is in the instantaneous purge mode.

10. The optical detection device according to claim 9, characterized in that: The lighting system also includes a beam power and quality monitoring unit, which is used to monitor the optical power of the illumination light or the spot distribution of the illumination light. When the optical power of the illumination light is abnormal or the spot distribution of the illumination light is abnormal, the beam power and quality monitoring unit sends a second purge signal to the first purge component, and the first purge component that receives the second purge signal and the first purge signal enters the instantaneous purge mode.

11. The optical detection device according to claim 10, characterized in that: The first purge component has N instantaneous purge modes, and the air pressure of the first purge airflow corresponding to the N instantaneous purge modes increases gradually. After the first purge component adopts the instantaneous purge mode with lower air pressure to purge the lighting system, if the first purge component still receives the second purge signal, the first purge component adopts the instantaneous purge mode with higher air pressure to purge the lighting system when it receives the first purge signal again.

12. The optical detection device according to claim 10, characterized in that: The beam power and quality monitoring unit includes: a detection unit, which is used to obtain a light signal formed by the optical element in the lighting system processing the illumination light; and a processing unit, which is used to determine whether the light power of the illumination light is abnormal, or whether the spot distribution of the illumination light is abnormal based on the light signal.

13. The optical detection device according to claim 12, characterized in that: The detection unit includes: an optical signal detection element and a control element, wherein the optical signal detection element is used to obtain the optical signal, and the control element is used to control the optical signal detection element to switch in or out of the transmission optical path of the optical signal.

14. The optical detection device according to claim 12, characterized in that: The detection unit includes: an optical signal detection element and a spectroscopic element. The spectroscopic element is arranged on the transmission optical path of the optical signal to separate the optical signal into a first optical signal and a second optical signal. The transmission directions of the first optical signal and the second optical signal are different. The optical signal detection element receives the first optical signal to detect the illumination light, and the second optical signal is used for scanning the sample.

15. The optical detection device according to claim 1, characterized in that: The defect detection device further includes a scanning detection system, and the scanning detection system is used to carry the sample to move so as to realize detection of different positions of the sample; The air purification device further comprises a detection chamber wind field system, and the detection chamber wind field system at least comprises a second purge component for blowing a second purge airflow toward the scanning detection system.

16. The optical detection device according to claim 15, characterized in that: The second purge assembly includes a second control unit, a second air intake assembly and a second exhaust assembly. The second control unit is used to control the air intake volume of the second air intake assembly and to control the air exhaust volume of the second exhaust assembly so that the air intake volume of the second air intake assembly is equal to the air exhaust volume of the second exhaust assembly per unit time.

17. The optical detection device according to claim 16, characterized in that: The optical detection device also includes a detection shell, which encloses a detection cavity. The scanning detection system is arranged in the detection cavity. The second exhaust component includes a second exhaust duct and a second exhaust fan. The detection cavity is connected to the first end of the second exhaust duct through a second exhaust port, and the other end of the second exhaust duct is connected to the second exhaust fan.

18. The optical detection device according to claim 17, characterized in that: The second air intake assembly includes a second air intake pipe and a uniform wind structure, wherein the uniform wind structure is arranged at one end of the second air intake pipe extending into the detection cavity, and the uniform wind structure is located above the sample, and the second purge air flow is blown out from the uniform wind structure through the second air intake pipe, and the direction of the second purge air flow blown out from the uniform wind structure is parallel to the direction of the sample surface.

19. The optical detection device according to claim 18, characterized in that: The uniform wind structure includes a uniform wind grid and a fan-shaped uniform wind portion. The side of one end of the second air inlet pipe connected to the uniform wind structure has an air outlet. The uniform wind grid is arranged at intervals at the air outlet along the circumference of the second air inlet pipe. The fan-shaped uniform wind portion has a uniform wind cavity, which is connected to the air outlet. The side of the fan-shaped uniform wind portion away from the air outlet has a plurality of uniform wind holes. The second purge airflow blown out of the air outlet passes through the uniform wind cavity and then flows into the detection cavity through the uniform wind holes.

20. A control method for an optical detection device, characterized in that: include: Provided is an optical inspection device according to any one of claims 1 to 19, the optical inspection device comprising a defect detection device and an air purification device, the defect detection device comprising a large defect avoidance system and a lighting system, the air purification device comprising an optical machine room wind field system, the optical machine room wind field system comprising a first purge component that blows a first purge airflow toward the lighting system; The control method of the optical inspection device comprises: when the illumination system scans a large defect on a sample, using the large defect avoidance system to send a shutter closing signal to the illumination system to close the high-power illumination light, so that the large defect on the sample avoids the scanning of the high-power illumination light; Wherein, the large defect avoidance system sends the shutter closing signal and also sends a first purge signal to the first purge component. The first purge component that receives the first purge signal increases the pressure of the first purge airflow.

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