Stray light measuring device and method thereof, and stray light measuring system

Abstract

The present invention provides a stray light measuring device and a measuring method thereof, as well as a stray light measuring system, which are provided by arranging a second sensor and a first sensor whose reflectivity is greater than that of the second sensor but whose photosensitive surface area is smaller than that of the second sensor on a workpiece stage, and arranging a first mark and a second mark with a light-transmitting area around them on a mask stage, wherein the measuring light irradiates the first mark to form a first dark spot, and irradiates the second mark to form a second dark spot. By eliminating the additional reflected light introduced when the first sensor is used to measure the light intensity of the first dark spot, the light intensity ratio of the stray light forming the first dark spot in the measuring light can be accurately obtained accordingly, thereby improving the accuracy of the stray light measurement.

Description

Technical Field

[0001] The present invention relates to the field of photolithography technology, and in particular to a stray light measuring device and a measuring method thereof, and a stray light measuring system. Background Art

[0002] With the development of semiconductor technology, the imaging performance requirements for projection exposure systems used in lithography are getting higher and higher. For projection exposure systems, the uniformity of the illumination system will directly affect the dose distribution at each point in the field of view. Therefore, in-situ measurement of illumination uniformity is a necessary function for any projection exposure device. In addition, stray light from the illumination system will also lead to reduced imaging performance and a smaller process window. Therefore, monitoring stray light performance is also one of the necessary functions of projection exposure devices.

[0003] Traditional projection exposure systems generally use a point energy sensor integrated on the workpiece stage, in conjunction with a stray light test mask stage, to scan the image side using the point energy sensor to detect the intensity of stray light. However, the accuracy of the stray light intensity measured by the existing stray light measurement device and method is relatively low. Summary of the invention

[0004] The object of the present invention is to provide a stray light measuring device and a measuring method thereof, and a stray light measuring system, so as to solve the problem of low accuracy of stray light testing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides a stray light measuring device, comprising a light source for providing measuring light, and the measuring device also comprises in sequence along the optical axis of the measuring light:

[0006] A movably arranged mask stage, wherein a first mark and a second mark are arranged on the mask stage, the photosensitive surface area of ​​the first mark is smaller than the photosensitive surface area of ​​the second mark, and the first mark and the second mark are surrounded by a light-transmitting area;

[0007] An objective lens and a movably arranged workpiece stage, wherein the objective lens is used to image the first mark irradiated by the measuring light onto the workpiece stage to form a first dark spot, and is used to image the second mark irradiated by the measuring light onto the workpiece stage to form a second dark spot, wherein at least one first sensor and at least one second sensor are arranged on the workpiece stage, and the reflectivity of the first sensor is greater than the reflectivity of the two sensors;

[0008] Among them, the first sensor is used to measure a first dark spot light intensity of the first dark spot, a second dark spot light intensity of the second dark spot, and a first transmitted light intensity of the measuring light passing through the light-transmitting area, and the second sensor is used to measure a third dark spot light intensity of the second dark spot and a second transmitted light intensity of the measuring light passing through the light-transmitting area, and the first sensor generates reflected light with equal light intensity when measuring the first dark spot light intensity and the second dark spot light intensity; and, according to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, the reflected light intensity of the reflected light generated by the first sensor is obtained, and based on the ratio of the first dark spot light intensity to the first transmitted light intensity after the reflected light intensity is eliminated, the intensity ratio of the stray light forming the first dark spot in the measuring light is obtained.

[0009] Optionally, the reflected light intensity is obtained by calculating using the following formula:

[0010]

[0011] And, the intensity ratio of the stray light is calculated according to the following formula:

[0012]

[0013] Wherein, Straylight represents: the light intensity ratio of the stray light;

[0014] Grid reflection Indicates: reflected light intensity;

[0015] Grid pad Indicates: the intensity of the first dark spot;

[0016] Grid point Indicates: the second dark spot intensity;

[0017] ESS point Indicates: the intensity of the third dark spot;

[0018] Grid blank Indicates: first transmitted light intensity;

[0019] ESS blank Indicates: Second transmitted light intensity.

[0020] Optionally, the first sensor is a projected image sensor, and the second sensor is a point energy sensor.

[0021] Optionally, the first mark and the second mark are in a shape of a circle, a rectangle, a triangle, etc.

[0022] Optionally, when measuring the first dark spot intensity, the first sensor is located at the center of the first dark spot, and when measuring the second dark spot intensity and measuring the third dark spot intensity, the first sensor and the second sensor are both located at the center of the second dark spot.

[0023] Optionally, the photosensitive surface areas of the images formed by the first mark and the second mark are both larger than the photosensitive surface area of ​​the first sensor.

[0024] In order to solve the above problem, the present invention also provides a stray light measurement method, comprising:

[0025] Providing a stray light measuring device as described in any one of the above, turning on a light source so that measuring light is irradiated onto a mask stage, and causing an objective lens to image the first mark irradiated by the measuring light onto a workpiece stage to form a first dark spot, and to image the second mark irradiated by the measuring light onto the workpiece stage to form a second dark spot;

[0026] Move the workpiece stage and / or the mask stage so that the first sensor measures a first dark spot light intensity of the first dark spot, a second dark spot light intensity of the second dark spot, and a first transmitted light intensity of the measuring light passing through the light-transmitting area, and the second sensor measures a third dark spot light intensity of the second dark spot and a second transmitted light intensity of the measuring light passing through the light-transmitting area;

[0027] According to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, the reflected light intensity of the reflected light generated by the first sensor is obtained, and based on the ratio of the reflected light intensity to the first transmitted light intensity after the first dark spot light intensity is removed, the intensity ratio of the stray light forming the first dark spot in the measuring light is obtained.

[0028] Optionally, the reflected light intensity is obtained by calculation according to the following formula:

[0029]

[0030] And, the intensity ratio of the stray light is calculated according to the following formula:

[0031]

[0032] Wherein, Straylight represents: the light intensity ratio of the stray light;

[0033] Grid reflection Indicates: reflected light intensity;

[0034] Grid pad Indicates: the intensity of the first dark spot;

[0035] Gridpoint Indicates: the second dark spot intensity;

[0036] ESS point Indicates: the intensity of the third dark spot;

[0037] Grid blank Indicates: first transmitted light intensity;

[0038] ESS blank Indicates: Second transmitted light intensity.

[0039] Optionally, the first sensor and the second sensor are each one, and the method for obtaining the first dark spot light intensity, the second dark spot light intensity, the third dark spot light intensity, the first transmitted light intensity, and the second transmitted light intensity includes:

[0040] Moving the workpiece stage and / or the mask stage so that the first sensor is located at the center of the first dark spot, and using the first sensor to measure the light intensity at the position of the first dark spot to obtain the light intensity of the first dark spot;

[0041] Moving the workpiece stage and / or the mask stage so that the first sensor is located under the light-transmitting area, and using the first sensor to measure the light intensity of the light-transmitting area to obtain the first transmitted light intensity;

[0042] Moving the workpiece stage and / or the mask stage so that the second sensor is located at the center of the second dark spot, and using the second sensor to measure the light intensity at the second dark spot position to obtain the third dark spot light intensity;

[0043] Moving the workpiece stage and / or the mask stage so that the second sensor is located under the light-transmitting area, and using the second sensor to measure the light intensity of the light-transmitting area to obtain the second transmitted light intensity;

[0044] The workpiece stage and / or the mask stage are moved so that the first sensor is located at the center of the first dark spot, and the light intensity at the second dark spot position is measured by using the first sensor to obtain the second dark spot light intensity.

[0045] Optionally, the number of the first sensor and the number of the second sensor are two each, and the method for obtaining the first dark spot light intensity, the second dark spot light intensity, the third dark spot light intensity, the first transmitted light intensity, and the second transmitted light intensity includes:

[0046] Move the workpiece stage and / or the mask stage so that one of the first sensors is located at the center of the first dark spot and measures the light intensity at the first dark spot to obtain the first dark spot light intensity, and another first sensor is located at the light-transmitting area and measures the light intensity at the light-transmitting area to obtain the first transmitted light intensity;

[0047] Move the workpiece stage and / or the mask stage so that one of the second sensors is located at the center of the second dark spot and measures the light intensity at the second dark spot to obtain the third dark spot light intensity, and another second sensor is located under the light-transmitting area and measures the light intensity of the light-transmitting area to obtain the second transmitted light intensity;

[0048] The workpiece stage and / or the mask stage are moved so that the first sensor is located at the center of the second dark spot, and the light intensity at the first dark spot position is measured to obtain the light intensity of the second dark spot.

[0049] To solve the above problems, the present invention also provides a stray light measurement system, which includes a stray light measurement device and a data processing module as described in any one of the above items, and the data processing module is communicatively connected to the first sensor and the second sensor to obtain the reflected light intensity of the reflected light generated by the first sensor according to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, and based on the ratio of the first dark spot light intensity after eliminating the reflected light intensity to the first transmitted light intensity, obtain the light intensity ratio of the stray light forming the first dark spot in the measuring light.

[0050] The present invention provides a stray light measuring device, which is provided by arranging a second sensor and a first sensor with a reflectivity greater than that of the second sensor but a smaller photosensitive surface area than that of the second sensor on a workpiece stage, and arranging a first mark and a second mark with a light-transmitting area around them on a mask stage, wherein the measuring light irradiates the first mark to form a first dark spot, and irradiates the second mark to form a second dark spot. By eliminating the additional reflected light introduced when the first sensor is used to measure the light intensity of the first dark spot, the light intensity ratio of the stray light forming the first dark spot in the measuring light can be accurately obtained accordingly, thereby improving the accuracy of the stray light measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram of the structure of a stray light measuring device according to an embodiment of the present invention.

[0052] Figure 2 Schematic diagram of stray light distribution in a stray light measurement device according to an embodiment of the present invention.

[0053] Figure 3 FIG. 4 is a flow chart of a stray light measurement method according to an embodiment of the present invention.

[0054] Reference numerals

[0055] 1- Light source;

[0056] 2-mask stage; 2A-light-transmitting area 2A;

[0057] 31-first mark; 32-second mark;

[0058] 4-Objective lens;

[0059] 5- Workpiece table;

[0060] 61- first sensor;

[0061] 61A-photosensitive area; 61B-high reflectivity area;

[0062] 62 - second sensor;

[0063] A-Measurement light;

[0064] B-stray light;

[0065] C-Reflected light. DETAILED DESCRIPTION

[0066] The following is a further detailed description of the stray light measurement device and its measurement method, and the stray light measurement system proposed in the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will become clearer. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis that each drawing needs to show is different, and sometimes different proportions are used.

[0067] Figure 1 FIG. 1 is a schematic diagram of the structure of a stray light measuring device according to an embodiment of the present invention. Figure 1 As shown, a stray light measuring device of this embodiment includes a light source 1 for providing measuring light A, and also includes the following components in sequence along the optical axis of the measuring light A.

[0068] A movably arranged mask stage 2 is provided with a first mark 31 and a second mark 32 , wherein the photosensitive surface area of ​​the first mark 31 is smaller than the photosensitive surface area of ​​the second mark 32 , and the first mark 31 and the second mark 32 are surrounded by a light-transmitting area 2A.

[0069] An objective lens 4 and a movably arranged workpiece stage 5, wherein the objective lens 4 is used to image the first mark 31 irradiated by the measuring light A on the workpiece stage 5 to form a first dark spot, and is used to image the second mark 32 irradiated by the measuring light A on the workpiece stage 5 to form a second dark spot, and at least one first sensor 61 and at least one second sensor 62 are provided on the workpiece stage 5, and the reflectivity of the first sensor 61 is greater than the reflectivity of the second sensor 62.

[0070] Among them, the first sensor 61 is used to measure the first dark spot light intensity of the first dark spot, the second dark spot light intensity of the second dark spot and the first transmitted light intensity of the measuring light A passing through the light-transmitting area 2A, and the second sensor 62 is used to measure the third dark spot light intensity of the second dark spot and the second transmitted light intensity of the measuring light A passing through the light-transmitting area 2A, and the first sensor 61 generates reflected light C with equal light intensity when measuring the first dark spot light intensity and the second dark spot light intensity; and, according to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, the reflected light intensity of the reflected light C generated by the first sensor 61 is obtained, and based on the ratio of the first dark spot light intensity after the reflected light intensity is eliminated to the first transmitted light intensity, the intensity proportion of the stray light B forming the first dark spot in the measuring light A is obtained.

[0071] The stray light B measuring device in this embodiment can accurately obtain the intensity ratio of the stray light B forming the first dark spot in the measuring light A by eliminating the additional reflected light introduced when the first sensor 61 is used to measure the intensity of the first dark spot, thereby improving the accuracy of the stray light B measurement.

[0072] Further, in this embodiment, the first mark 31 and the second mark 32 are set on the mask stage 2. Optionally, the first mark 31 and the second mark 32 can be set on the mask plate (not shown) located on the mask stage 2, which is hereinafter represented by the mask stage 2. That is, the first mark 31 and the second mark 32 are set on the mask stage 2, which means that the first mark 31 and the second mark 32 can be directly set on the mask stage 2, or can be set on the mask plate located on the mask stage 2.

[0073] In the present embodiment, the first sensor 61 has a photosensitive area 61A and a high reflectivity area 61B, and the high reflectivity area 61B has a high reflectivity. When the first sensor 61 is used to measure the stray light B, the stray light B irradiates the high reflectivity area 61B, and the stray light B irradiated on the high reflectivity area 61B is reflected by the reflective area 61B, and then reflected by the mask stage 2 and then irradiated to the first sensor 61. In this way, when the first sensor 61 measures the stray light B, the reflected light C formed by the reflection of the high reflectivity area 61B is introduced into the stray light B. Therefore, in the present embodiment, the second sensor 62 having a reflectivity lower than that of the first sensor 61 is provided to be used in conjunction with the first sensor 61 to measure the stray light B. In this way, not only does it not need to develop a new sensor, but the stray light B can be measured by using only the first sensor 61 and the second sensor 62 of the prior art, and the accuracy of the stray light B measurement can be improved.

[0074] In addition, in the present embodiment, the stray light B is divided into short-range stray light B, medium-range stray light B and long-range stray light B according to the lateral distance of the stray light B propagating toward the first mark 31 or the second mark 32. For example, the stray light B whose lateral propagation distance toward the first mark 31 or the second mark 32 is less than or equal to 5um is defined as short-range stray light, the stray light B whose lateral propagation distance toward the first mark 31 or the second mark 32 is between 5um and 20um is defined as medium-range stray light, and the stray light B whose lateral propagation distance toward the first mark 31 or the second mark 32 is greater than or equal to 20um is defined as long-range stray light. The long and short range of the stray light B is related to the machine characteristics of the lithography machine, and the above-mentioned distance distinction is only an exemplary classification, which shall be subject to the actual machine.

[0075] Since in this embodiment, the photosensitive surface area of ​​the first sensor 61 is smaller than the photosensitive surface area of ​​the second sensor 62, the first sensor 61 can be used to measure stray light with a shorter lateral propagation distance. For example, the stray light B propagating toward the first mark 31 is short-range stray light B, and the stray light B propagating toward the second mark 32 is long-range stray light B. Among them, the travel distance of the measured stray light B is ≥ (dark spot diameter-diameter of the sensor photosensitive surface) / 2. In this embodiment, the lateral propagation distance of the stray light toward the mark refers to the position where the stray light reaches, the distance from the edge of the image formed by the mark, and the distance is described on the image plane.

[0076] Figure 2 FIG. 1 is a schematic diagram of the distribution law of stray light B in a stray light B measurement device according to an embodiment of the present invention. Figure 2 As shown, the horizontal axis represents the travel distance of the stray light B (i.e., the distance that the stray light B propagates laterally), and the vertical axis represents the intensity of the stray light B, as shown in FIG. Figure 2 As shown, when the travel of stray light B is shorter, the intensity of stray light B is greater. And when the travel of stray light B changes from long range to short range, the shorter the travel of stray light B, the greater the rate of change of the intensity of stray light B. The spatial resolution of a general photosensitive sensor is related to its photosensitive diameter (a multi-pixel sensor is related to the pixel size), so it is more accurate to measure the short-range stray light B using a sensor with a smaller photosensitive surface area, and when measuring the long-range stray light B, the size of the sensor photosensitive surface area has little effect on the result. In this embodiment, the photosensitive surface area of ​​the first sensor 61 is smaller than the photosensitive surface area of ​​the second sensor 62, so the first sensor 61 is suitable for measuring the light intensity forming the first dark spot and the second dark spot, and the second sensor 62 is suitable for measuring the light intensity forming the second dark spot.

[0077] In this embodiment, the first sensor 61 and the second sensor 62 may be rectangular, triangular, circular, or the like.

[0078] Furthermore, in this embodiment, the image areas formed by the first mark 31 and the second mark 32 are larger than the photosensitive surface area of ​​the first sensor 61. In this way, the first sensor 61 can be used to measure the first dark spot light intensity of the first dark spot and the second dark spot light intensity of the second dark spot at the same time.

[0079] In addition, the shapes of the first mark 31 and the second mark 32 may be circular, triangular or rectangular. When the shapes of the first mark 31 and the second mark 32 are circular, the diameter of the first mark 31 may be, for example, 200um, and the diameter of the second mark 32 may be, for example, 110.5um, 90.5um, 70.5um, 50.5um, 38.5um, 35.5um, 32.5um.

[0080] Furthermore, in this embodiment, the first sensor 61 is a transmission image sensor, and the second sensor 62 is a point energy sensor.

[0081] Furthermore, in this embodiment, the intensity of the reflected light C can be calculated by the following formula (1):

[0082]

[0083] And, the light intensity ratio of the stray light B is calculated according to the following formula:

[0084]

[0085] Wherein, Straylight represents: the light intensity ratio of the stray light B; Grid reflection Indicates: reflected light C is strong; Grid pad Indicates: the intensity of the first dark spot; Grid point Indicates: Second dark spot intensity; ESS point Indicates: the intensity of the third dark spot; Grid blank Indicates: first transmitted light intensity; ESS blank Indicates: Second transmitted light intensity.

[0086] In addition, in this embodiment, when measuring the first dark spot intensity, the first sensor 61 is located at the center of the first dark spot, and when measuring the second dark spot intensity and the third dark spot intensity, the first sensor 61 and the second sensor 62 are both located at the center of the second dark spot. In this way, the stray light B can be measured more accurately.

[0087] Figure 3 FIG. 1 is a flow chart of a method for measuring stray light B according to an embodiment of the present invention. Figure 3 Combined with Figure 1 As shown, this embodiment further discloses a stray light B measurement method, and the stray light B measurement method includes the following steps.

[0088] Step S10: Provide the stray light B measuring device described above, turn on the light source 1 to allow the measuring light A to irradiate the mask stage 2, and enable the objective lens 4 to image the first mark 31 irradiated by the measuring light A on the workpiece stage 5 to form a first dark spot, and to image the second mark 32 irradiated by the measuring light A on the workpiece stage 5 to form a second dark spot.

[0089] Step S20: Move the workpiece stage 5 and / or the mask stage so that the first sensor 61 measures the first dark spot light intensity of the first dark spot, the second dark spot light intensity of the second dark spot and the first transmitted light intensity of the measuring light A passing through the light-transmitting area 2A, and the second sensor 62 measures the third dark spot light intensity of the second dark spot and the second transmitted light intensity of the measuring light A passing through the light-transmitting area 2A.

[0090] In this embodiment, if there is one first sensor 61 and one second sensor 62, the method for obtaining the first dark spot light intensity, the second dark spot light intensity, the third dark spot light intensity, the first transmitted light intensity and the second transmitted light intensity includes the following steps 1 to 5.

[0091] Step 1: Move the workpiece stage 5 and / or the mask stage 2 to make the first sensor 61 located at the center of the first dark spot, and use the first sensor 61 to measure the light intensity at the first dark spot position to obtain the first dark spot light intensity.

[0092] Step 2: Move the workpiece stage 5 and / or the mask stage 2 so that the first sensor 61 is located under the light-transmitting area 2A, and use the first sensor 61 to measure the light intensity of the light-transmitting area 2A to obtain the first transmitted light intensity.

[0093] Step three: Move the workpiece stage 5 and / or the mask stage 2 so that the second sensor 62 is located at the center of the second dark spot, and use the second sensor 62 to measure the light intensity at the second dark spot position to obtain the third dark spot light intensity.

[0094] Step 4: Move the workpiece stage 5 and / or the mask stage 2 so that the second sensor 62 is located under the light-transmitting area 2A, and use the second sensor 62 to measure the light intensity of the light-transmitting area 2A to obtain the second transmitted light intensity.

[0095] Step five: Move the workpiece stage 5 and / or the mask stage 2 so that the first sensor 61 is located at the center of the second dark spot, and use the first sensor 61 to measure the light intensity at the second dark spot position to obtain the second dark spot light intensity.

[0096] In addition, optionally, if there are two of the first sensor 61 and the second sensor 62, the method for obtaining the first dark spot light intensity, the second dark spot light intensity, the third dark spot light intensity, the first transmitted light intensity and the second transmitted light intensity includes the following first to third steps.

[0097] The first step: move the workpiece stage 5 and / or the mask stage 2 so that one of the first sensors 61 is located at the center of the first dark spot, and measures the light intensity at the first dark spot position to obtain the first dark spot light intensity, and the other first sensor 61 is located in the light-transmitting area 2A, and measures the light intensity of the light-transmitting area 2A to obtain the first transmitted light intensity.

[0098] The second step: move the workpiece stage 5 and / or the mask stage 2 so that one of the second sensors 62 is located at the center of the second dark spot, and measures the light intensity at the second dark spot position to obtain the third dark spot light intensity, and the other second sensor 62 is located under the light-transmitting area 2A, and measures the light intensity of the light-transmitting area 2A to obtain the second transmitted light intensity.

[0099] The third step: move the workpiece stage 5 and / or the mask stage 2 so that the first sensor 61 is located at the center of the second dark spot, and measure the light intensity at the second dark spot position to obtain the second dark spot light intensity.

[0100] Step S30: According to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, the reflected light intensity of the reflected light C generated by the first sensor 61 is obtained, and based on the ratio of the first dark spot light intensity after the reflected light intensity is eliminated to the first transmitted light intensity, the intensity ratio of the stray light B forming the first dark spot in the measuring light A is obtained.

[0101] Furthermore, in this embodiment, the intensity of the reflected light C can be obtained by calculation using the following formula (1):

[0102]

[0103] And, the intensity ratio of the stray light B is obtained by calculating according to the following formula:

[0104]

[0105] Wherein, Straylight represents: the light intensity ratio of the stray light B; Grid reflection Indicates: reflected light C is strong; Grid pad Indicates: the intensity of the first dark spot; Grid point Indicates: Second dark spot intensity; ESS point Indicates: the intensity of the third dark spot; Grid blank Indicates: first transmitted light intensity; ESS blank Indicates: Second transmitted light intensity.

[0106] In addition, since the data on both sides of the equal sign in formula (1) and formula (2) are light intensity ratios, all the aforementioned "light intensity" values ​​measured by the sensor can also be sensor readings that are linearly related to the "light intensity" value, and do not have to be limited to light intensity values ​​in the physical sense.

[0107] Furthermore, in the present embodiment, a stray light B measurement system is also disclosed. The stray light B measurement system in the present embodiment includes the stray light B measurement device and the data processing module described above. The data processing module is communicatively connected to the first sensor 61 and the second sensor 62 to obtain the reflected light intensity of the reflected light C generated by the first sensor 61 according to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, and obtain the intensity ratio of the stray light B forming the first dark spot in the measuring light A based on the ratio of the reflected light intensity after the first dark spot light intensity is removed to the first transmitted light intensity.

[0108] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A stray light measuring device, characterized in that: The measuring device comprises a light source for providing measuring light, and the measuring device also comprises, in sequence, along the optical axis of the measuring light: A movably arranged mask stage, wherein a first mark and a second mark are arranged on the mask stage, the area of ​​the first mark is smaller than the area of ​​the second mark, and a light-transmitting area is formed around the first mark and the second mark; An objective lens and a movably arranged workpiece stage, wherein the objective lens is used to image the first mark irradiated by the measuring light onto the workpiece stage to form a first dark spot, and is used to image the second mark irradiated by the measuring light onto the workpiece stage to form a second dark spot, wherein at least one first sensor and at least one second sensor are arranged on the workpiece stage, wherein the reflectivity of the first sensor is greater than the reflectivity of the second sensor, and the photosensitive surface area of ​​the first sensor is smaller than the photosensitive surface area of ​​the second sensor; Among them, the first sensor is used to measure a first dark spot light intensity of the first dark spot, a second dark spot light intensity of the second dark spot, and a first transmitted light intensity of the measuring light passing through the light-transmitting area, and the second sensor is used to measure a third dark spot light intensity of the second dark spot and a second transmitted light intensity of the measuring light passing through the light-transmitting area, and the first sensor generates reflected light with equal light intensity when measuring the first dark spot light intensity and the second dark spot light intensity; and, according to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, the reflected light intensity of the reflected light generated by the first sensor is obtained, and based on the ratio of the first dark spot light intensity to the first transmitted light intensity after the reflected light intensity is eliminated, the intensity ratio of the stray light forming the first dark spot in the measuring light is obtained.

2. The stray light measuring device according to claim 1, characterized in that: The reflected light intensity is obtained by calculating the following formula: And, the intensity ratio of the stray light is calculated according to the following formula: Wherein, Straylight represents: the light intensity ratio of the stray light; Grid reflection Indicates: reflected light intensity; Grid pad Indicates: the intensity of the first dark spot; Grid point Indicates: the second dark spot intensity; ESS point Indicates: the intensity of the third dark spot; Grid blank Indicates: first transmitted light intensity; ESS blank Indicates: Second transmitted light intensity.

3. The stray light measuring device according to claim 1, characterized in that: The first sensor is a transmission image sensor, and the second sensor is a point energy sensor.

4. The stray light measuring device according to claim 1, characterized in that: The first mark and the second mark are in a circular, rectangular or triangular shape.

5. The stray light measuring device according to claim 1, characterized in that: When measuring the first dark spot intensity, the first sensor is located at the center of the first dark spot, and when measuring the second dark spot intensity and measuring the third dark spot intensity, both the first sensor and the second sensor are located at the center of the second dark spot.

6. The stray light measuring device according to claim 1, characterized in that: The imaged areas of the first mark and the second mark are both larger than the area of ​​the photosensitive surface of the first sensor, and the imaged area of ​​the second mark is larger than the area of ​​the photosensitive surface of the second sensor.

7. A stray light measurement method, characterized in that: include: Providing a stray light measuring device according to any one of claims 1 to 6, turning on a light source so that measuring light is irradiated onto a mask stage, and causing an objective lens to image the first mark irradiated by the measuring light onto a workpiece stage to form a first dark spot, and to image the second mark irradiated by the measuring light onto the workpiece stage to form a second dark spot; Move the workpiece stage and / or the mask stage so that the first sensor measures a first dark spot light intensity of the first dark spot, a second dark spot light intensity of the second dark spot, and a first transmitted light intensity of the measuring light passing through the light-transmitting area, and the second sensor measures a third dark spot light intensity of the second dark spot and a second transmitted light intensity of the measuring light passing through the light-transmitting area; According to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, the reflected light intensity of the reflected light generated by the first sensor is obtained, and based on the ratio of the reflected light intensity to the first transmitted light intensity after the first dark spot light intensity is removed, the intensity ratio of the stray light forming the first dark spot in the measuring light is obtained.

8. A stray light measurement method as claimed in claim 7, characterized in that: The reflected light intensity is obtained by calculation according to the following formula: And, the intensity ratio of the stray light is calculated according to the following formula: Wherein, Straylight represents: the light intensity ratio of the stray light; Grid reflection Indicates: reflected light intensity; Grid pad Indicates: the intensity of the first dark spot; Grid point Indicates: the second dark spot intensity; ESS point Indicates: the intensity of the third dark spot; Grid blank Indicates: first transmitted light intensity; ESS blank Indicates: Second transmitted light intensity.

9. The stray light measurement method according to claim 7, characterized in that: The first sensor and the second sensor are each one, and the method for obtaining the first dark spot light intensity, the second dark spot light intensity, the third dark spot light intensity, the first transmitted light intensity, and the second transmitted light intensity includes: Moving the workpiece stage and / or the mask stage so that the first sensor is located at the center of the first dark spot, and using the first sensor to measure the light intensity at the position of the first dark spot to obtain the light intensity of the first dark spot; Moving the workpiece stage and / or the mask stage so that the first sensor is located under the light-transmitting area, and using the first sensor to measure the light intensity of the light-transmitting area to obtain the first transmitted light intensity; Moving the workpiece stage and / or the mask stage so that the second sensor is located at the center of the second dark spot, and using the second sensor to measure the light intensity at the second dark spot position to obtain the third dark spot light intensity; Moving the workpiece stage and / or the mask stage so that the second sensor is located under the light-transmitting area, and using the second sensor to measure the light intensity of the light-transmitting area to obtain the second transmitted light intensity; The workpiece stage and / or the mask stage are moved so that the first sensor is located at the center of the first dark spot, and the light intensity at the second dark spot position is measured by using the first sensor to obtain the second dark spot light intensity.

10. The stray light measurement method according to claim 7, characterized in that: The number of the first sensor and the number of the second sensor are two each, and the method for obtaining the first dark spot light intensity, the second dark spot light intensity, the third dark spot light intensity, the first transmitted light intensity, and the second transmitted light intensity includes: Move the workpiece stage and / or the mask stage so that one of the first sensors is located at the center of the first dark spot and measures the light intensity at the first dark spot to obtain the first dark spot light intensity, and another first sensor is located at the light-transmitting area and measures the light intensity at the light-transmitting area to obtain the first transmitted light intensity; Move the workpiece stage and / or the mask stage so that one of the second sensors is located at the center of the second dark spot and measures the light intensity at the second dark spot to obtain the third dark spot light intensity, and another second sensor is located under the light-transmitting area and measures the light intensity of the light-transmitting area to obtain the second transmitted light intensity; The workpiece stage and / or the mask stage are moved so that the first sensor is located at the center of the second dark spot, and the light intensity at the first dark spot position is measured to obtain the light intensity of the second dark spot.

11. A stray light measurement system, characterized in that: The stray light measurement system includes the stray light measurement device according to any one of claims 1 to 6 and a data processing module, wherein the data processing module is communicatively connected to the first sensor and the second sensor to obtain the reflected light intensity of the reflected light generated by the first sensor according to the ratio of the third dark spot light intensity to the second transmitted light intensity, the second dark spot light intensity and the first transmitted light intensity, and obtain the intensity ratio of the stray light forming the first dark spot in the measuring light based on the ratio of the reflected light intensity to the first transmitted light intensity after the first dark spot light intensity is removed.

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