TWI894487B - Foreign matter inspection device, exposure device, and manufacturing method of article - Google Patents

Abstract

A foreign body inspection device detects the presence of foreign matter in an inspection area of an object to be inspected, comprising: 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 within an allowable value, and determines that a foreign matter is present in the inspection area if the signal is outside the allowable value; the determination unit changes the allowable value according to the lighting conditions under which the light from the light source illuminates the inspection area.

Description

Foreign matter inspection device, exposure device, and manufacturing method of article

This invention relates to a foreign matter detection device, an exposure device, and a method for manufacturing the same.

Semiconductor devices and liquid crystal displays are manufactured using a photolithography process that transfers a fine pattern from an original plate onto a glass substrate. If foreign matter, such as dust or dirt, is present on the original plate, the exposure performance of the exposure equipment used in this process can be reduced, potentially resulting in poor resolution. Therefore, foreign matter detection equipment is installed in the exposure equipment to inspect the original plate for foreign matter.

In recent years, as the size of original plates increases, exposure equipment has been experiencing warping due to their own weight, potentially reducing imaging performance. Therefore, a method has been proposed to create an airtight chamber by blocking the upper side of the original plate with a flat glass plate (hereinafter referred to as a warp correction member). By adjusting the pressure within the airtight chamber, the warp is reduced. If foreign matter adheres to the warp correction member, exposure performance may also be reduced. Patent Document 1 discloses a foreign matter detection device that inspects both the original plate and the warp correction member for foreign matter. Patent Document 1 discloses that by independently driving the original plate and the warp correction member, it is possible to determine to which side the foreign matter is attached.

[Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2011-258880

Foreign object detection devices generally detect scattered light from light irradiating a foreign object using a light-receiving unit and determine the size of the foreign object based on the amount of light received. This result allows the determination of whether the foreign object is large enough to tolerate degradation of exposure performance. However, as the lighting conditions associated with the light irradiating the foreign object for foreign object detection change, the relationship between the size of the foreign object and the amount of scattered light received from the foreign object changes. Therefore, changing the lighting conditions can reduce the accuracy of foreign object detection.

Therefore, an object of the present invention is to provide a foreign matter detection device that is advantageous in suppressing a decrease in accuracy during foreign matter detection.

To achieve the aforementioned objectives, a foreign object detection device, as one embodiment of the present invention, is provided for detecting the presence of foreign matter in an inspection area of an object to be inspected. The device comprises: 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 within an allowable value. If the signal is outside the allowable value, the device determines that a foreign matter is present in the inspection area. The determination unit changes the allowable value based on the lighting conditions under which the light from the light source illuminates the inspection area.

Further features of the present invention will become clear from the following embodiments (with reference to the accompanying drawings).

2: Light-receiving part

6: Deflection correction component (corresponding to the object being inspected)

7: Original (corresponding to the inspected object)

20: Foreign object detection device

22: Judgment Department

[Figure 1] is a schematic diagram illustrating the structure of the foreign matter detection device mounted on the exposure device.

[Figure 2] is a graph showing the relationship between foreign matter and uneven illumination.

[Figure 3] is a graph showing the relationship between foreign body size and signal strength.

The preferred embodiments of the present invention are described below in detail with reference to the accompanying drawings. In the drawings, identical components are denoted by the same reference symbols, and repeated descriptions are omitted.

<First Implementation Method>

First, the structure of the foreign matter inspection device of this embodiment will be described. Figure 1 illustrates a portion of the structure of an exposure device 100 and is used to illustrate the foreign matter inspection device 20 of this embodiment. The foreign matter inspection device 20 can inspect the original plate 7 (on which a pattern is formed), the pellicle (film) protecting the patterned surface of the original plate 7, and the warp correction member for the presence of foreign matter (dust, ash, scratches, defects, etc.). A detailed description of the warp correction member will be provided later. While the following describes an example in which the foreign matter inspection device 20 is mounted on the exposure apparatus and inspects the presence of foreign matter attached to the warp correction member (the object to be inspected), inspection of foreign matter attached to the original plate 7 is also possible even when the warp correction member 6 is not installed. Specifically, inspection of foreign matter attached to at least one of the original plate 7 and the warp correction member 6 can be performed based on the presence or absence of the warp correction member 6. In this embodiment, the surface on which the original plate 7 is mounted is defined as the XY plane, and the direction perpendicular to the XY plane is defined as the Z direction.

As shown in Figure 1, exposure apparatus 100 includes an illumination optical system 1, a deflection correction member 6, a plate stage 8 that holds a plate 7 bearing an exposure pattern, a projection optical system 9, and a foreign matter detection device 20. Light from a light source is illuminated by the illumination optical system 1 onto the plate 7, and the pattern formed on the plate 7 is transferred to a substrate coated with a photosensitive material via the projection optical system 9. Exposure apparatus 100 can be a so-called step-and-scan exposure apparatus, which performs this transfer while synchronously driving the plate stage 8 and substrate in the Y direction. Exposure apparatus 100 is not limited to this and can also be a step-and-repeat exposure apparatus.

The deflection correction member 6 is located on the upper surface of the master plate 7 and is capable of adjusting the air pressure within the airtight chamber 5 (enclosed space) between the deflection correction member 6 and the master plate 7. This corrects the deflection caused by the weight of the master plate 7 (self-weight deflection).

If foreign matter adheres to the deflection correction member 6 or the original plate 7, there is a risk of poor exposure analysis during the exposure process in the exposure device 100. This is because a portion of the illumination light 23 irradiated from the light source onto the pattern surface of the original plate is blocked by the foreign matter, resulting in uneven illumination.

FIG2 is a diagram showing the relationship between foreign matter and uneven illumination. As shown in FIG2, during exposure (foreign matter inspection), there is a diameter of 0.01 mm on the inspection surface of the deflection correction member 6 at a distance H from the pattern surface (lower surface) of the original plate 7. In the case of a foreign object 21, part of the illumination light 23 irradiated from the exposure light source to the pattern surface is blocked by the foreign object. The relationship between illumination unevenness ΔI and poor resolution can be determined before inspection based on actual measurement and simulation results.

Here, as shown in FIG2, it is assumed that the numerical aperture of the illumination system is 14 (NA_ill), the numerical aperture of the projection system is 17 (NA_po), and the size of the foreign body is , the projection system magnification β, and the optical distance H from the pattern surface to the inspection surface. Optical distance H is calculated based on the relationship between the thickness of the original plate 7 and the deflection correction member 6, the refractive index n of the gas between the original plate 7 and the deflection correction member 6, and the distance between the original plate 7 and the deflection correction member 6. Illumination unevenness ΔI (unit: %) is determined using the above parameters using the following equation (1).

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 plate 7 to the inspection surface used in formula (1) are hereinafter referred to as illumination conditions. In addition, the exposure conditions described below are also one of the illumination conditions.

Returning to the description of Figure 1 , a foreign object detection device 20 is positioned near the deflection correction member 6 for detecting foreign objects attached to the upper surface of the deflection correction member 6 . The foreign object detection device 20 includes a light receiving unit 2 comprising a light receiving element 3 and a lens 4 , a photoelectric conversion unit 21 , and a determination unit 22 Foreign Object Detection Although the device 20 may also include a separate light source for foreign object detection, the following description uses the exposure light source of an exposure device as the light source for foreign object detection. Furthermore, while the following description uses an example in which foreign object detection is performed concurrently with the exposure process of exposing the substrate, the exposure process and foreign object detection may also be performed at different times.

The following describes how the foreign object detection device 20 performs foreign object detection. Light emitted from the light source illuminates the inspection area of the deflection correction member 6, thereby illuminating any foreign objects within the inspection area. At this time, scattered light from the foreign object passes through the lens 4 included in the light receiving unit 2 and is received (detected) by the light receiving element 3.

The photoelectric converter 21 converts the light received by the light receiving unit 2 into an electrical signal. The signal generated by the photoelectric converter 21 is input to the determination unit 22. The electrical signal is a voltage representing the intensity of the signal and a pixel in the light receiving area of the light receiving element 3.

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 an allowable value. If so, it determines that a foreign object is present in the inspection area. Specifically, the input signal can be used to determine the area within the inspection area and the size of the foreign object. The relationship between signal intensity and foreign object size can be recorded in the determination unit 22 based on actual measurement results or simulations before the foreign object inspection.

If the determination unit 22 detects a foreign object, the exposure process can be interrupted and the process automatically shifted to the foreign object removal process. Alternatively, the exposure process can be continued, and the foreign object removal process can be executed while the exposed substrate is being transported to the next process. Furthermore, if the determination unit 22 detects a foreign object, it can notify the user that a foreign object is present in the inspection area.

FIG2 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 FIG2, the relationship between the size of a foreign object and the signal intensity varies depending on the lighting conditions. Under the same lighting conditions, the size of the foreign object and the signal intensity have a one-to-one correspondence. For example, when performing foreign object inspection under lighting condition 1, by comparing the foreign object size to the signal intensity, the foreign object size is determined to be 1:1. The signal strength A is set as the upper limit of the allowable value (i.e., the allowable value is set to be greater than 0 and less than A), so that when the size of the foreign object is In the above cases, foreign objects can be detected.

However, when the lighting condition is changed from lighting condition 1 to lighting condition 2, the size of the foreign object The signal strength becomes signal strength B (B>A). At this time, when the upper limit of the allowable value of signal strength is still A, when the size of the foreign body is (-)to Even if the size is smaller than , it will be judged as a foreign object. This may reduce productivity.

In addition, when the lighting condition is changed from lighting condition 1 to lighting condition 3, the size of the foreign object The signal strength becomes C (C<A). At this time, when the upper limit of the allowable value of the signal strength is still A, the size of the foreign object is to Even if the size is (+), it will not be identified as a foreign object. Therefore, there is a risk of continuing production with poor resolution.

As described above, there is a risk that accurate foreign object detection may become impossible due to changes in lighting conditions. Therefore, this embodiment provides a foreign object detection device 20 that can change the permissible value of the signal representing the amount of light received by the light receiving unit 2 as lighting conditions change. In the example of Figure 2 , when the lighting conditions change from lighting condition 1 to lighting condition 2, the upper limit of the permissible signal intensity is changed from A to B. When the lighting conditions change from lighting condition 1 to lighting condition 3, the upper limit of the permissible signal intensity is changed from A to C.

Furthermore, in this embodiment, the exposure light source of the exposure device is used as the light source for foreign matter detection. Therefore, exposure conditions such as the light source exposure dose, the drive speed of the plate stage, and the air pressure in the airtight chamber between the plate 7 and the deflection correction member 6 must be appropriately set according to changes in the exposure process. This exposure condition is one of the lighting conditions described above; it is a parameter that can be adjusted as appropriate when using the exposure light source of the exposure device as the light source for foreign matter detection.

The determination unit 22 may change the range of the allowable value based on pre-recorded actual measurement results or simulation results. Alternatively, the upper limit of the allowable value may be predicted based on pre-recorded actual measurement results or simulation results.

As described above, when lighting conditions change, the signal intensity input to the determination unit 22 also changes. The foreign object detection conditions of the foreign object detection device 20 may also be changed in response to these changes. As foreign object detection conditions, the integration time and output amplification value of the light receiving unit may be set so that an output intensity at least equivalent to the upper limit of the permissible value for the foreign object size falls within the dynamic range of the light receiving unit's output intensity. Furthermore, the cycle for acquiring the light receiving unit's output signal may be set to accurately inspect the entire inspection area on the deflection correction member 6 without repetition by driving the master stage 8. If the foreign object detection conditions are changed, the permissible value may also be changed in accordance with the foreign object detection conditions.

Furthermore, while the above description describes an example where the tolerance value is set above 0 and below an arbitrary value, this is not limiting. For example, when performing foreign object detection based on the inverse of the signal strength as shown in Figure 3 (i.e., when the signal strength decreases as the foreign object size increases), the tolerance value can be set to a range greater than the arbitrary value. In this embodiment, the change in the tolerance value refers to a change in the upper or lower limit of the tolerance value. Furthermore, multiple tolerance values can be set, and a foreign object can be detected at the first tolerance value and production can be stopped at the second tolerance value.

In this embodiment, while the exposure light source is used during the exposure process, and the foreign matter detection device 20 disposed near the deflection correction member 6 is used to detect foreign matter, this is not limiting. Foreign matter detection may also be performed using a light source for inspection that is separate from the exposure light source.

As described above, in this embodiment, the determination unit 22 can change the permissible value of the signal representing the amount of light received by the light receiving unit 2 based on the lighting conditions under which the inspection area is illuminated by light emitted from the light source. This can suppress a decrease in accuracy in foreign matter detection.

<Implementation of the manufacturing method of the article>

The manufacturing method of an article according to an embodiment of the present invention is suitable for manufacturing articles such as flat panel displays (FPDs), semiconductor devices, sensors, and optical components. The manufacturing method of this embodiment includes a process for detecting foreign matter on the original plate 7 or the deflection correction member 6 (a foreign matter detection process); and a process for removing foreign matter detected during the foreign matter detection process (a foreign matter removal process). Furthermore, as described in the first embodiment, the foreign matter detection process can change the permissible value of the signal intensity (the intensity of the signal indicating the amount of light received by the light receiving unit 2) based on the lighting conditions under which the inspection area is illuminated by light emitted from the light source. Furthermore, the manufacturing method includes: forming a latent pattern on a photosensitive agent applied to a substrate by exposure using the aforementioned exposure apparatus to obtain an exposed substrate (exposure process); and developing the exposed substrate on which the latent pattern is formed by this process to obtain a developed substrate (development process). Furthermore, the manufacturing method includes other well-known processes (oxidation, film formation, evaporation, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method of this embodiment is advantageous over conventional methods in at least one of the following aspects: article performance, quality, productivity, and production cost.

While the above describes preferred embodiments of the present invention, the present invention is not limited to these embodiments and various modifications and alterations are possible within the scope of its gist.

According to the present invention, a foreign matter detection device can be provided that is advantageous in suppressing a decrease in accuracy during foreign matter detection.

Claims (9)

A foreign matter detection device, provided in an exposure device that performs an exposure process for exposing a pattern on an original plate onto a substrate, detects the presence of foreign matter in an inspection area of an object to be inspected. The device comprises: 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. If the signal is outside the allowable value, the device determines that a foreign matter is present in the inspection area. The light source is the light source used in the exposure process. The determination unit changes the allowable value based on the lighting conditions under which the light from the light source illuminates the inspection area. As in claim 1, the foreign matter inspection device, wherein the determination unit determines whether there is a foreign matter in the inspection area in parallel with the exposure process. As in claim 1, the foreign body inspection device, wherein the aforementioned lighting condition is at least one 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. As in claim 1, the foreign matter inspection device, wherein the aforementioned lighting condition is at least one of the exposure amount of the aforementioned light source, the driving speed of the original plate stage that holds the aforementioned original plate, and the air pressure of the airtight chamber between the original plate and the deflection correction member that corrects the deflection of the original plate. As claimed in claim 1, the foreign matter detection device detects foreign matter in the inspection area on the original plate. As claimed in claim 1, the foreign matter detection device detects foreign matter in an inspection area on a deflection correction member for correcting deflection of the original plate. An exposure apparatus for exposing a pattern on a master plate onto a substrate includes the foreign matter detection apparatus of claim 1. The foreign matter detection apparatus detects foreign matter present in at least one of a master plate disposed in the exposure apparatus and a deflection correction member for correcting deflection of the master plate. A method for manufacturing an article, comprising: an exposure process of exposing a substrate using the exposure apparatus of claim 7 to obtain an exposed substrate; a development process of developing the exposed substrate to obtain a developed substrate; and manufacturing an article from the developed substrate. The method for manufacturing an article as claimed in claim 8 further comprises: A foreign matter detection step for detecting foreign matter present in at least one of the original plate and a deflection correction member for correcting deflection of the original plate, in parallel with the exposure step; and A foreign matter removal step for removing the foreign matter.