Foreign substance inspection apparatus, exposure apparatus, and method for manufacturing an article

Abstract

To suppress accuracy deterioration in foreign matter inspection.SOLUTION: A foreign matter inspection device for detecting the presence / absence of foreign matter in an inspection region of an inspected article comprises: a light receiving part receiving scattered light from foreign matter generated by irradiating the foreign matter with light from a light source; and a determination part determining whether a signal indicating an amount of light received by the light receiving part falls within a permissible value, and determines that the inspection region includes foreign matter if the signal is out of the permissible value. The determination part changes the permissible value on the basis of illumination condition in which the inspection region is illuminated with light from the light source.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a foreign matter inspection apparatus, an exposure apparatus, and an article manufacturing method. [Background technology]

[0002] Semiconductor devices and liquid crystal display devices are manufactured using a lithography process in which a fine pattern on an original is transferred onto a glass substrate. In the exposure equipment used in this lithography process, if there is foreign matter, such as dust or dirt, on the original, the exposure performance will be reduced, resulting in poor resolution. Therefore, a foreign matter inspection device is installed in the exposure equipment and used to inspect the original for foreign matter.

[0003] In recent exposure devices, as originals have become larger, they may bend under their own weight, resulting in a deterioration in imaging performance. To address this issue, efforts have been made to reduce bending by creating an airtight chamber by sealing the upper side of the original with flat glass (hereinafter referred to as a deflection compensation member) and adjusting the pressure in the airtight chamber. Foreign matter adhering to this deflection compensation member may also degrade exposure performance. Patent Document 1 discloses a foreign matter inspection device that inspects the original and the deflection compensation member for foreign matter. Patent Document 1 discloses a device that can determine which side has foreign matter attached by driving the original and the deflection compensation member separately. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-258880 Summary of the Invention [Problem to be solved by the invention]

[0005] In general, a foreign particle inspection system detects scattered light emitted from a foreign particle using a light-receiving unit and can determine the size of the foreign particle based on the detected amount of received light. From the results, it can be determined whether the foreign particle is large enough to tolerate a deterioration in exposure performance. However, as the illumination conditions for the light irradiated onto the foreign particle for foreign particle inspection change, the relationship between the size of the foreign particle and the amount of scattered light received from the foreign particle changes. Therefore, changing the illumination conditions may reduce the accuracy of foreign particle inspection.

[0006] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a foreign matter inspection device that is advantageous in suppressing a decrease in accuracy in foreign matter inspection. [Means for solving the problem]

[0007] In order to achieve the above object, one aspect of the present invention provides a foreign matter inspection apparatus that is provided in an exposure apparatus that performs an exposure process in which a pattern of an original is exposed onto a substrate, and that detects the presence or absence of foreign matter in an inspection area of ​​an object to be inspected, and that includes a light receiving unit that receives scattered light from the foreign matter generated by illuminating the foreign matter with light from a light source, and a determination unit that determines whether a signal indicating the amount of light received by the light receiving unit is outside an allowable value, and that determines the presence of foreign matter in the inspection area if the signal is outside the allowable value, wherein the light source is a light source used in the exposure process, and the determination unit: In the exposure process, at least one of the driving speed of an original stage that holds the original and the air pressure in an airtight chamber between the original and a deflection correction member that corrects deflection of the original. The tolerance is changed based on the above. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a foreign matter inspection device that is advantageous in suppressing a decrease in precision in foreign matter inspection. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a foreign matter inspection device mounted on an exposure apparatus. [Figure 2] 10 is a graph showing the relationship between foreign matter and uneven illuminance. [Figure 3]10 is a graph showing the relationship between the size of a foreign substance and the signal intensity. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same components, and redundant explanations will be omitted.

[0011] First Embodiment First, the configuration of a foreign particle inspection apparatus according to this embodiment will be described. FIG. 1 is a diagram showing a portion of the configuration of an exposure apparatus 100 and is a diagram for explaining a foreign particle inspection apparatus 20 according to this embodiment. The foreign particle inspection apparatus 20 is an apparatus that can inspect the presence or absence of foreign particles (dust, dirt, scratches, defects, etc.) attached to an original 7 on which a pattern is formed, a pellicle that is a film protecting the patterned surface of the original 7, and a deflection compensation member. A detailed description of the deflection compensation member will be given later. Below, an example will be described in which the foreign particle inspection apparatus 20 is mounted on an exposure apparatus and inspects the presence or absence of foreign particles attached to a deflection compensation member (inspection target). However, if a deflection compensation member 6 is not provided, foreign particles attached to the original 7 may also be inspected. That is, foreign particles attached to at least one of the original 7 and the deflection compensation member 6 may be inspected depending on whether the deflection compensation member 6 is provided. In this embodiment, the surface on which the original 7 is placed is defined as the XY plane, and the direction perpendicular to the XY plane is defined as the Z direction.

[0012] As shown in FIG. 1, exposure apparatus 100 has an illumination optical system 1, a deflection correction member 6, an original stage 8 that holds an original 7 on which an exposure pattern is drawn, a projection optical system 9, and a foreign substance inspection device 20. Light from a light source is emitted onto original 7 via illumination optical system 1, and the pattern formed on original 7 is transferred onto a substrate coated with a photosensitive material via projection optical system 9. Exposure apparatus 100 can be a so-called step-and-scan exposure apparatus that performs the above transfer while driving original stage 8 and the substrate in the Y direction in synchronization. However, exposure apparatus 100 is not limited to this, and may also be a step-and-repeat exposure apparatus.

[0013] The deflection compensation member 6 is disposed on the upper surface side of the original 7, and can adjust the air pressure in the airtight chamber 5 (sealed space) between the deflection compensation member 6 and the original 7. This makes it possible to compensate for deflection of the original 7 due to its own weight (self-weight deflection).

[0014] If foreign matter is attached to the deflection compensation member 6 or the original 7, poor exposure resolution may occur in the exposure process of the exposure apparatus 100. This is because part of the illumination light 23 that is emitted from the light source onto the pattern surface of the original is blocked by the foreign matter, causing uneven illuminance.

[0015] Figure 2 is a diagram showing the relationship between foreign particles and illuminance unevenness. As shown in Figure 2, if a foreign particle 21 with a diameter φ is present on the inspection surface of the deflection compensation member 6 at a distance H from the pattern surface (bottom surface) of the original 7 during exposure (during foreign particle inspection), part of the illumination light 23 that is irradiated onto the pattern surface from the exposure light source is blocked by the foreign particle. The size of the foreign particle that causes poor resolution is determined from the relationship between the illuminance unevenness ΔI caused by light blocking due to the foreign particle and the size φ of the foreign particle. The relationship between illuminance unevenness ΔI and poor resolution can be determined before inspection based on the results of actual measurements and simulations.

[0016] Here, as shown in Figure 2, the numerical aperture of the illumination system is 14 (NA_ill), the numerical aperture of the projection system is 17 (NA_po), the size of the foreign particle is φ, the magnification of the projection system is β, and the optical distance from the pattern surface to the inspection surface is H. The optical distance H is a value calculated from the relationship between the thicknesses of the original 7 and the deflection compensation member 6, the refractive index n of the gas between the original 7 and the deflection compensation member 6, and the distance between the original 7 and the deflection compensation member 6. The illuminance unevenness ΔI (unit: %) is determined using the above parameters by the following formula (1): ΔI=φ 2 ×100 / {(NA_ill / NA_po)×(2×NA_po / β)×H} 2 ...Equation (1)

[0017] The numerical aperture 14 of the illumination system, the numerical aperture 17 of the projection system, the magnification β of the projection system, and the optical distance H from the pattern surface of the original 7 to the inspection surface, all of which are used in equation (1), are hereinafter referred to as illumination conditions. The exposure conditions, which will be explained below, are also one type of illumination condition.

[0018] Returning to the explanation of FIG. 1, a foreign matter inspection device 20 is disposed near the deflection compensation member 6 to inspect for foreign matter adhering to the upper surface of the deflection compensation member 6. The foreign matter inspection device 20 has a light receiving unit 2 including a light receiving element 3 and a lens 4, a photoelectric conversion unit 21, and a determination unit 22. The foreign matter inspection device 20 may have its own light source for foreign matter inspection, but the following describes an example in which the exposure light source of an exposure device is used as the light source for foreign matter inspection. Also, the following describes an example in which foreign matter inspection is performed in parallel with an exposure process in which the substrate is exposed to light, but the exposure process and foreign matter inspection may be performed at different times.

[0019] The following describes how the foreign matter inspection device 20 performs foreign matter inspection. Light emitted from the light source illuminates the inspection area of ​​the deflection compensation member 6 and illuminates any foreign matter on the inspection area. At this time, scattered light generated from the foreign matter is received (detected) by the light receiving element 3 via the lens 4 configured in the light receiving unit 2.

[0020] The photoelectric conversion unit 21 converts the light received by the light receiving unit 2 into an electrical signal. The signal generated by the photoelectric conversion unit 21 is input to the determination unit 22. The electrical signal is a voltage representing the intensity of the signal and a pixel representing the light receiving region of the light receiving element 3.

[0021] The determination unit 22 determines whether the input signal (i.e., the signal indicating the amount of light received by the light receiving unit 2) is within the tolerance, and if it is within the tolerance, determines that a foreign object is present in the inspection area. Specifically, it can determine from the input signal which area in the inspection area the foreign object is located in and how large it is. Here, the relationship between signal strength and foreign object size can be recorded in the determination unit 22 as an actual measurement result or a simulation before foreign object inspection.

[0022] When the determination unit 22 detects a foreign object, the exposure process can be interrupted and automatically transitioned to the process of removing the foreign object. Alternatively, the exposure process being executed may be continued, and the process of removing the foreign object may be executed at the timing of transporting the exposed substrate to the next process. Further, when the determination unit 22 detects a foreign object, the user may be notified that the foreign object is on the inspection area.

[0023] FIG. 2 is a graph showing the relationship between the size of a foreign object and the signal intensity input to the determination unit 22. As shown in FIG. 2, the relationship between the size of the foreign object and the signal intensity differs depending on the illumination conditions. When the illumination conditions are the same, the size of the foreign object and the signal intensity correspond one-to-one. For example, when performing foreign object inspection under illumination condition 1, by setting the signal intensity A corresponding to the size φ of the foreign object as the upper limit of the allowable value (that is, setting the allowable value to 0 or more and A or less), when the size of the foreign object is φ or more, the foreign object can be detected.

[0024] However, when the illumination condition is changed from illumination condition 1 to illumination condition 2, the signal intensity corresponding to the size φ of the foreign object becomes signal intensity B (B > A). At this time, if the upper limit of the allowable value of the signal intensity remains A, even when the size of the foreign object is from φ(-) to φ, it will be determined as a foreign object. As a result, there is a possibility of reducing productivity. <​​​​As such, there is a risk that correct foreign substance inspection will not be possible when the illumination conditions are changed. Therefore, in this embodiment, a foreign substance inspection device 20 is provided that can change the tolerance value of the signal indicating the amount of light received by the light receiving unit 2 when the illumination conditions are changed. In the example of Figure 2, when the illumination condition is changed from illumination condition 1 to illumination condition 2, the upper limit of the tolerance value of the signal strength is changed from A to B, and when the illumination condition is changed from illumination condition 1 to illumination condition 3, the upper limit of the tolerance value of the signal strength is changed from A to C.

[0027] Furthermore, in this embodiment, the exposure light source of the exposure apparatus is used as the light source for foreign substance inspection, so it is necessary to appropriately set exposure conditions such as the exposure amount of the light source, the driving speed of the original stage, and the air pressure in the airtight chamber between the original 7 and the deflection compensation member 6 in accordance with changes in the exposure process. This exposure condition is one of the illumination conditions described above, and is a parameter that can be appropriately changed when using the exposure light source of the exposure apparatus as the light source for foreign substance inspection.

[0028] The determination unit 22 can change the range of the allowable value based on pre-recorded actual measurement results or simulation results, or can predict the upper limit of the allowable value from pre-recorded actual measurement results or simulation results.

[0029] Furthermore, as explained above, when the illumination conditions change, the signal intensity input to the determination unit 22 changes. The foreign substance inspection conditions of the foreign substance inspection device 20 may be changed in response to this change. As foreign substance inspection conditions, the accumulation time and output amplification value of the light receiving unit may be set so that the output intensity corresponding to at least the upper limit of the tolerance for the size of the foreign substance falls within the dynamic range of the output intensity of the light receiving unit. Furthermore, the acquisition cycle of the output signal from the light receiving unit may be set so that the entire inspection area on the deflection compensation member 6 is inspected correctly without overlap by driving the original stage 8. When the foreign substance inspection conditions are changed, the tolerance value may also be changed according to the foreign substance inspection conditions.

[0030] In the above description, the tolerance is set to a value greater than or equal to 0 and less than or equal to an arbitrary numerical value, but this is not limiting. For example, when foreign substance inspection is performed based on the inverse of the signal strength shown in FIG. 3 (i.e., when the signal strength decreases as the foreign substance size increases), the tolerance may be set to a range greater than an arbitrary numerical value. In this embodiment, the change in the tolerance is a change in the upper or lower limit of the tolerance. Furthermore, multiple tolerances may be set, and the presence of a foreign substance may be detected at the first tolerance and production may be stopped at the second tolerance.

[0031] In this embodiment, it is assumed that an exposure light source is used during exposure processing to inspect for foreign particles on the deflection compensation member 6 by a foreign particle inspection device 20 arranged near the deflection compensation member 6, but this is not limiting. Foreign particle inspection may also be performed using an inspection light source separate from the exposure light source.

[0032] As described above, in this embodiment, the determination unit 22 can change the tolerance of the signal indicating the amount of light received by the light receiving unit 2 based on the illumination conditions under which the light emitted from the light source illuminates the inspection area. This makes it possible to prevent a decrease in accuracy in foreign substance inspection.

[0033] <Embodiments of manufacturing methods of articles> The article manufacturing method according to the embodiment of the present invention is suitable for manufacturing articles such as flat panel displays (FPDs), semiconductor devices, sensors, and optical elements. The article manufacturing method of this embodiment includes a step of detecting foreign matter on the original 7 or the deflection compensation member 6 (foreign matter inspection step) and a step of removing foreign matter detected in the foreign matter inspection step (foreign matter removal step). As described in the first embodiment, the foreign matter inspection step can change the tolerance of the signal intensity (the intensity of the signal indicating the amount of light received by the light receiving unit 2) based on the illumination conditions under which the light emitted from the light source illuminates the inspection area. Furthermore, this manufacturing method also includes a step of forming a latent image pattern on a photosensitive agent applied to a substrate by exposure using the above-mentioned exposure apparatus to obtain an exposed substrate (exposure step), and a step of developing the exposed substrate on which the latent image pattern has been formed to obtain a developed substrate (development step). Furthermore, this manufacturing method also includes other well-known processes (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing an article according to the present embodiment is advantageous over conventional methods in at least one of the performance, quality, productivity, and production costs of the article.

[0034] Although the preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0035] 2 Light receiving section 6 Deflection compensation member (corresponding to the object to be inspected) 7 Master (corresponding to the object to be inspected) 20 Foreign body inspection equipment 22 Judgment section

Claims

1. A foreign matter inspection device that is provided in an exposure device that performs an exposure process of exposing a pattern of an original onto a substrate, and that detects the presence or absence of foreign matter in an inspection area of ​​an object to be inspected, a light receiving unit that receives scattered light from the foreign matter generated by illuminating the foreign matter with light from the light source; a determination unit that determines whether a signal indicating the amount of light received by the light receiving unit is outside a tolerance, and determines that a foreign substance is present in the inspection area if the signal is outside the tolerance; the light source is a light source used in the exposure process, a determination unit that changes the tolerance based on at least one of the driving speed of an original stage that holds the original during the exposure process and the air pressure in an airtight chamber between the original and a deflection correction member that corrects deflection of the original.

2. 2. The foreign matter inspection apparatus according to claim 1, wherein the determination unit determines whether or not a foreign matter is present in the inspection area in parallel with the exposure process.

3. A foreign matter inspection device as described in claim 1 or 2, characterized in that the judgment unit changes the tolerance value based on at least one condition of the numerical aperture of the illumination system, the numerical aperture of the projection system, the magnification of the projection system, and the optical distance from the pattern surface of the original to the inspection surface.

4. A foreign matter inspection device as described in any one of claims 1 to 3, characterized in that the judgment unit changes the tolerance value based on the exposure amount of the light source.

5. 5. The foreign matter inspection apparatus according to claim 1, wherein the foreign matter inspection apparatus detects foreign matter in an inspection area on the original.

6. 5. The foreign matter inspection device according to claim 1, wherein the foreign matter inspection device detects foreign matter in an inspection area on a deflection compensation member that compensates for deflection of the original.

7. An exposure apparatus that exposes a pattern of an original onto a substrate, 7. An exposure apparatus comprising the foreign matter inspection device according to claim 1, which inspects for foreign matter on at least one of an original placed in the exposure apparatus and a deflection correction member that corrects deflection of the original.

8. an exposure step of exposing a substrate using the exposure apparatus according to claim 7 to obtain an exposed substrate; a developing step of developing the exposed substrate to obtain a developed substrate, A method for manufacturing an article, comprising manufacturing an article from the developed substrate.

9. a foreign matter inspection step of inspecting for foreign matters on at least one of the original and a deflection correction member that corrects deflection of the original in parallel with the exposure step; The method for manufacturing an article according to claim 8, further comprising a foreign matter removing step of removing the foreign matter.

Images