JP3714756B2 - Surface inspection method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection method and apparatus for inspecting deformation of a film of a flat film member such as a pellicle attached to a reticle or a mask.
[0002]
[Prior art]
With recent miniaturization of semiconductor devices, a pellicle is affixed to a reticle or mask to prevent dust from adhering to the reticle or mask. If the pellicle film is pasted, bent, or distorted and the flat state is poor, the pellicle film will come into contact with the wafer exposure device or case during storage or handling, and the pellicle film will be scratched. There are things to do. If scratches occur on the pellicle film, the scratches may be transferred to the wafer during wafer exposure, causing pattern abnormalities on the wafer.
[0003]
[Problems to be solved by the invention]
For this reason, it is necessary to inspect the deformation of the pellicle film in the inspection after sticking the pellicle or in the periodic inspection after using the reticle or the like.
The conventional inspection of the deformation state of the pellicle film has only been performed by using a high-intensity light source and confirming that a person observes the swelling state and wrinkle state of the pellicle film from the vertical and horizontal directions by visual inspection. With this method, an abnormal swelling of the pellicle film could not be sufficiently confirmed.
[0004]
Further, in the inspection, there were variations due to individual differences, and it was impossible to reliably detect the delicate swelling and wrinkle state of the pellicle film. If the pellicle film has swelling or wrinkles, the pellicle film may come into contact with the case or the device during storage or handling, resulting in scratches. For this reason, at the time of wafer exposure, scratches and wrinkles are transferred to the wafer, resulting in problems such as pattern deformation.
[0005]
An object of the present invention is to solve the above-described problems, and enables inspection of surface state abnormalities such as swelling and wrinkles of a pellicle film, and is applied to a wafer due to abnormal deformation of the pellicle film. It is an object of the present invention to provide a surface inspection method and apparatus capable of preventing abnormal transfer of patterns.
Another object of the present invention is to provide a surface inspection method and apparatus that can inspect abnormalities in the surface state of a film-like member, not limited to a pellicle film.
[0006]
[Means for Solving the Problems]
According to the surface inspection method of the present invention, the step of disposing an inspection reference member above the film member in which the flat film member is disposed above the flat plate member and the surface of the film member is reflected. A step of comparing the first reflected image of the inspection reference member with the second reflected image of the inspection reference member that has been transmitted through the film-like member and reflected by the surface of the plate-like member. Is.
[0007]
In this surface inspection method, by using the inspection reference member and comparing the first reflection image and the second reflection image, the abnormal state of the surface of the flat film-like member can be reliably and Can be easily inspected. Even if a visual inspection is performed, individual differences can be reduced.
Preferably, the following features can be included.
[0008]
The inspection reference member is a straight bar-shaped member.
The first reflected image and the second reflected image are compared in a common plane.
It is compared whether the first reflected image and the second reflected image are parallel to each other.
The shape of the first reflected image is determined with reference to the second reflected image.
The distance between the first reflected image and the second reflected image is measured at a plurality of positions.
[0009]
The first reflected image and the second reflected image are visually compared.
The first reflected image and the second reflected image are compared with a measuring instrument.
The plate-like member is one of a reticle and a mask, and the film-like member is a pellicle film.
Alternatively, the plate-like member is a flat support member having a reflective surface, and the film-like member is a substrate of a display device.
[0010]
Further, the present surface is an inspection device for inspecting the surface of the flat film-like member arranged above the flat plate-like member, and can be arranged above the film-like member. A reference member, a first reflection image of the inspection reference member reflected on the surface of the film-like member, and a second reflection of the inspection reference member transmitted through the film-like member and reflected on the surface of the plate-like member And measuring means capable of measuring an image, wherein the surface of the film-like member is inspected by comparing the first reflected image and the second reflected image. A surface inspection apparatus is provided.
[0011]
This surface inspection apparatus is suitable for carrying out the above inspection method.
Preferably, the inspection reference member is a straight bar-shaped member.
Preferably, the measuring means is a CCD measuring device.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram illustrating the principle of the present invention. In FIG. 1, a reticle 1 is shown. The reticle 1 serves as a prototype of a mask used for exposing a semiconductor wafer. The present invention can be applied not only to the reticle 1 but also to a mask. A pellicle 2 is attached to the reticle 1 (or mask).
[0013]
FIG. 3 is a sectional view through the reticle 1 and pellicle 2 of FIG. 1 and 3, a mask pattern is formed on the surface 3 of the reticle 1 with chromium or the like. The pellicle 2 includes a rectangular frame 4 and a film 5 supported by the frame 4, and the bottom of the frame 4 is the surface of the reticle 1 so that a gap is formed between the film 5 and the surface 3 of the reticle 1. 3 is adhered. The film 5 protects the mask pattern on the surface 3 of the reticle 1 and prevents foreign matter from adhering to the mask pattern of the reticle 1. The film 5 has a high transmittance (99% or more) in the wavelength band of light used in wafer exposure, but has a reflectance of several tens of percent in visible light. That is, visible light is reflected by the surface 6 of the film 5 of the pellicle 2.
[0014]
In the present invention, an inspection reference member 7 is used to inspect the flatness of the film 5 of the pellicle 2. The inspection reference member 7 is preferably a straight bar-like member having high linearity. The inspection reference member 7 is preferably disposed above the pellicle 2 in a plane parallel to the surface 3 of the reticle 1 and supported by a support member (not shown). Here, upward refers to the direction of viewing the pellicle 2 from the reticle 1 in the relationship between the reticle 1 and the pellicle 2.
[0015]
The surface 3 of the reticle 1 and the surface 6 of the film 5 of the pellicle 2 each act as a mirror surface, and on the inspection plane 8, a first reflected image 9 of the inspection reference member 7 reflected by the surface 6 of the film 5 of the pellicle 2; A second reflected image 10 of the inspection reference member 7 that is transmitted through the film 5 of the pellicle 2 and reflected by the surface 3 of the reticle 1 is formed. Therefore, in the present invention, the flatness of the film 5 of the pellicle 2 is inspected by comparing the first reflection image 9 and the second reflection image 10 on the inspection plane 8.
[0016]
In one embodiment, the first reflected image 9 and the second reflected image 10 are visually compared. In this case, the eye of the inspector is positioned on the inspection plane 8. In another aspect, the first reflected image 9 and the second reflected image 10 are compared by measuring the interval between the first reflected image 9 and the second reflected image 10 using a measuring instrument. The comparison compares whether the first reflected image 9 and the second reflected image 10 are parallel to each other.
[0017]
FIG. 2 is a diagram showing a comparison between the first reflected image 9 and the second reflected image 10. The reticle 1 and the film 5 of the pellicle 2 are parallel to each other. If the film 5 of the pellicle 2 is not swollen or distorted, the first reflected image 9 and the second reflected image 10 are both linear. And parallel to each other. If the film 5 of the pellicle 2 is swollen, curved, or distorted, the first reflected image 9 does not become a straight line as shown by the broken line 9a, but becomes a curved line, which is an inspection plane. In FIG. 8, the inspector's eyes inspect with the second reflected image 10 as a reference, so that an abnormality can be detected.
[0018]
In the conventional visual inspection, the film 5 of the pellicle 2 swells when the surface 6 of the film 5 of the pellicle 2 is viewed from directly above the film 5 or viewed from an angle parallel to the film 5. , I was inspecting for distortion, but there were considerable individual differences in the test results. According to the present invention, the inspection is performed while comparing the two adjacent first and second reflected images 9 and 10, so that a reliable inspection can be performed and there is no individual difference in the inspection result.
[0019]
When the first reflected image 9 and the second reflected image 10 are compared by measuring the distance between the images 9 and 10 with a measuring instrument, the first reflected image 9 and the second reflected image 10 are compared with the second reflected image 9 with the measuring instrument. Are measured at a plurality of points (for example, measured values L ₁ , L ₂ , L ₃ ). If the first reflection image 9 and the second reflection image 10 are parallel to each other, variations in the measurement values L ₁ , L ₂ , and L ₃ are small. If the film 5 of the pellicle 2 is swollen, curved, or distorted, a large (or small) measurement value L ₄ is measured, and variations in the measurement values L ₁ , L ₂ , and L ₄ are large. Become. Thereby, it can be detected that the film 5 of the pellicle 2 is not normal.
[0020]
FIG. 4 is a view showing an embodiment of the surface inspection apparatus according to the present invention. This surface inspection apparatus is configured in accordance with the above-described inspection principle. In this surface inspection apparatus, the inspection reference member 7, the first reflected image 9 of the inspection reference member 7 reflected by the surface 6 of the film 5 of the pellicle 2, and the surface 3 of the reticle 1 through the film 5 of the pellicle 2 are transmitted. And a measuring means 11 capable of measuring the second reflected image 10 of the inspection reference member 7 reflected by.
[0021]
Comparing the first reflected image 9 and the second reflected image 10 is performed as described above. The reticle 1 to which the pellicle 2 is attached is supported by a holder 12 having a support surface inclined with respect to the horizontal. Further, the lighting device 12 is turned on in a state where the surroundings are relatively dark including the lighting device 12 so that the first reflected image 9 and the second reflected image 10 are clearly projected. The same applies to visual inspection. In addition, as long as the position of the illuminating device 12 is a position which does not inhibit inspection, it may be installed anywhere.
[0022]
Preferably, the inspection as described above is performed on the entire surface of the film 5 of the pellicle 2. For this reason, the length of the inspection reference member 7 is preferably longer than the film 5 of the pellicle 2. The distance between the first reflection image 9 and the second reflection image 10 is continuously measured while relatively moving one of the inspection plane 8 (measurement means 11) and the holder 12 in the direction of the arrow A. . If the length of the inspection reference member 7 is shorter than the film 5 of the pellicle 2, the first reflection is performed while moving one of the inspection plane 8 (measurement means 11) and the holder 12 in the direction of arrow A and the direction perpendicular thereto. The distance between the image 9 and the second reflected image 10 is measured.
[0023]
The measuring means 11 is preferably composed of a CCD measuring device for line scanning or point scanning. With line scanning, image distortion due to scratches on the surface 6 of the film 5 of the pellicle 2 can also be detected. However, the measuring means 11 is not limited to the CCD measuring apparatus, and any means can be used as long as it can measure the interval between the reflected images 9 and 10. For example, other measuring devices such as a laser measuring device can be used.
[0024]
FIG. 5 is a diagram showing a modification of FIG. In this example, a measuring means 11 comprising a CCD measuring device is arranged directly at the position of the reflection plane 8 and receives the first and second reflected images 9 and 10 directly by the measuring means 11. Other features are the same as in the previous embodiment.
FIG. 6 is a diagram showing another embodiment. In the above example, the example in which the deformation of the film 5 of the pellicle 2 attached to the reticle 1 is inspected has been described. However, the present invention is not limited to such an example, and can be used for other applications in which the reticle 1 is another plate-shaped member 21 and the film 5 of the pellicle 2 is another film-shaped member 22. For example, the film-like member 22 is a glass substrate of a liquid crystal display device or a plasma display device, and the plate-like member 21 can be a reflecting plate having a reflecting surface arranged in parallel with the film-like member 22. The film member 22 is disposed above the plate member 21, and the inspection reference member 7 is disposed above the plate member 21.
[0025]
Also in this case, the first reflected image 9 of the inspection reference member 7 reflected on the surface of the film-like member 22 and the second reflection of the inspection reference member 7 that has passed through the film-like member 22 and reflected on the surface of the plate-like member 21. The reflected image 10 is compared. For comparison between the first reflected image 9 and the second reflected image 10, any of the visual method and the method using the measuring means 11 described above can be adopted.
[0026]
【The invention's effect】
As described above, according to the present invention, there is an effect that the state of the film of the pellicle can be surely inspected at the time of shipment or periodic inspection. As a result, the reticle with the pellicle can be stored in a stable state, and the pellicle film is not damaged, the semiconductor chip defects can be reduced, the progress of the wafer process can be accelerated, and the high yield can be achieved. The place that contributes to the short turn is big. Furthermore, according to the present invention, the surface of other film-like members such as a glass substrate of a liquid crystal display device or a plasma display device can be inspected.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the principle of the present invention.
FIG. 2 is a diagram showing a relationship between a reflection image on a pellicle and a reflection image on a film of a reticle.
FIG. 3 is a cross-sectional view through the reticle and pellicle of FIG.
FIG. 4 is a diagram showing an embodiment of the present invention.
5 is a diagram showing a modification of the apparatus of FIG.
FIG. 6 is a diagram showing another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reticle 2 ... Pellicle 3 ... Reticle surface 4 ... Pellicle frame 5 ... Pellicle film 6 ... Membrane surface 7 ... Inspection reference member 8 ... Inspection plane 9 ... First reflection image 10 ... Second reflection image 11 ... Measuring means 12 ... Holder

Claims (13)

  A step of disposing an inspection reference member above the film member in which the flat film member is disposed above the flat plate member; and a first of the inspection reference member reflected on the surface of the film member A surface inspection method comprising a step of comparing the reflected image with a second reflected image of the inspection reference member that is transmitted through the film-like member and reflected by the surface of the plate-like member.   The surface inspection method according to claim 1, wherein the inspection reference member is a straight bar-shaped member.   The surface inspection method according to claim 2, wherein the first reflected image and the second reflected image are compared in a common inspection plane.   4. The surface inspection method according to claim 3, wherein whether or not the first reflected image and the second reflected image are parallel to each other is compared.   The surface inspection method according to claim 4, wherein the shape of the first reflected image is determined based on the second reflected image.   The surface inspection method according to claim 4, wherein the distance between the first reflected image and the second reflected image is measured at a plurality of positions.   The surface inspection method according to claim 1, wherein the first reflected image and the second reflected image are visually compared.   The surface inspection method according to claim 1, wherein the first reflected image and the second reflected image are compared with a measuring instrument.   9. The surface inspection method according to claim 1, wherein the plate-like member is one of a reticle and a mask, and the film-like member is a pellicle film.   The surface inspection method according to claim 1, wherein the plate-like member is a flat support member having a reflective surface, and the film-like member is a substrate of a display device.   An inspection apparatus for inspecting the surface of a flat film-shaped member disposed above a flat plate-shaped member, wherein the inspection reference member can be disposed above the film-shaped member, and the film-shaped member Measuring a first reflected image of the inspection reference member reflected by the surface of the member and a second reflected image of the inspection reference member reflected by the surface of the plate-like member through the film-like member A surface inspection apparatus characterized in that the surface of the film-like member is inspected by comparing the first reflected image and the second reflected image. The surface inspection apparatus according to claim 11, wherein the inspection reference member is a straight bar-shaped member. The surface inspection apparatus according to claim 11, wherein the measuring means is a CCD measuring apparatus .

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