JPH03217843A - Foreign matter inspecting device - Google Patents

Abstract

PURPOSE:To allow the exact measurement of the height of a pellicle frame by providing an independent detector separate from a detector which receives the scattered light from foreign matter in the upper part of the pellicle frame and detecting the light scattered by the frame. CONSTITUTION:Only the scattered light 8 from a reflecting point 11 or the foreign matter is detected at the position of x+ or -alpha when a substrate 1 is irradiated with a polarized laser beam 5 while the position of the substrate 1 is moved in, for example, an X- or Y-axis direction. On the other hand, the scattered light from the reflecting point 11 falls onto the ceiling corner edge part of the pellicle frame 2 at the position x and, therefore, the scattered light 12 is generated again in this position and a part of the scattered light is detected by a photodetector 9. A part thereof is detected by a photodetector 13 above the frame 2. The height of the frame 2 is, therefore, determined by h=tantheta if the x value is read. The x position on the X axis of Y axis scattered by the photodetector 13 is detected and inputted to a CPU 15 from the above- mentioned reason. The quantity corresponding to the size (h) obtd. by the CPU 15 is sent to a position adjusting mechanism 16 and the surface of the pellicle film 3 is moved to the position of the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for detecting the height of a frame in a state where a foreign matter adhesion prevention means in which a pellicle is formed on the frame is attached to a substrate.

[Conventional technology]

A conventional foreign matter inspection device was constructed as shown in FIGS. 1 and 2. That is, when the polarized laser beam 5 emitted from the laser oscillator 4 is irradiated obliquely from above onto a foreign object 6 existing on the substrate 1 of a reticle or mask, scattering 7 occurs from the foreign object 6. Therefore, by detecting a part of the scattered light 8 of the scattered light 7 with the light receiver 9, the presence of the foreign object 6 can be known. In the foreign matter inspection, it is necessary to target not only the foreign matter on the surface of the substrate 1 but also the foreign matter 10 on the pellicle film 3. Usually, the optical paths of the polarized laser 5 and the scattered light 8 are often set at fixed positions.
Therefore, when inspecting foreign matter 10, it is necessary to adjust the position in the Z-axis direction by the amount of deviation in the height of pellicle frame 2, that is, the height from the surface of substrate 1 to pellicle film 3. Up until now, the height has been determined by manually inputting a fixed value from the pellicle catalog specifications, etc., when setting conditions before starting an inspection. As equipment becomes more sensitive, the beam diameter of the polarized laser beam 5 is becoming smaller, and its depth of focus is also becoming narrower.Also, if it is possible to observe foreign objects with a high-magnification microscope, the depth of focus is becoming narrower. Therefore, an accurate value is particularly required for the height of the pellicle frame 2 mentioned above.

However, the height of the pellicle frame 2 varies widely from the nominal value, and the thickness of the adhesive used when attaching it to the substrate 1 cannot be ignored compared to the depth of focus. It also has a large impact on Furthermore, it is not practical to measure each item one by one and input the numerical values.

[Problem to be solved by the invention]

An object of the present invention is to eliminate the drawbacks of the above-mentioned conventional techniques, and to accurately measure the actual height of the frame each time an inspection is performed with a simple configuration, and to quickly align the polarized laser beam and each focal point of the microscope. The goal is to provide equipment.

[Means to solve the problem]

In order to achieve the above objective, an independent detector separate from the detector that receives the scattered light from the foreign object is installed directly above the pellicle frame, and the light scattered by the frame is detected and the height of the frame is adjusted. By accurately measuring the height and driving the position adjustment mechanism in the Z-axis direction by an amount corresponding to this height, the focus position can be adjusted to the foreign object on the pellicle surface.

[Effect]

If the detector only receives the scattered light from the foreign object, it will simultaneously receive the scattered light from the frame as well as the scattered light from the foreign object, making it difficult to accurately distinguish only the scattered light from the frame. According to the technical means of the present invention, only the scattered light from the frame can be captured, so the height of the frame can be accurately measured.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. When the polarized laser beam 5 emitted from the laser oscillator 4 is irradiated onto the surface of the substrate 1, it is reflected at the reflection point 11 to generate scattered light 8, which is detected by the light receiver 9. If there is a foreign object at the reflection point 11, the intensity of the scattered light will change depending on the size of the foreign object.
You can know the size of foreign objects.

Now, if the polarized laser beam 5 is irradiated onto the substrate 1 while moving the position of the substrate 1 in the X or Y axis direction,
At the position α or X-α, only the scattered light 8 from the reflection point 11 or from the foreign object is detected. On the other hand, at exactly the position X, the scattered light from the reflection point l1 hits the ceiling corner/edge of the pellicle frame 2, so it again generates scattered light 12, and a part of the scattered light 12 is transmitted to the light receiver 9. A portion of the light is detected by a light receiver 13 provided directly above the pellicle frame 2. The position where this scattered light 12 occurs or
Since it is determined within a narrow range, it can be captured quite accurately. Therefore, if the X dimension is read in the X-axis or Y-axis direction using a means that can read coordinates in detail, such as with an encoder, the height of the pellicle 2 can be determined as h=x-tanθ. Here, θ is the fixed arrangement of the laser oscillator 4 and the light receiver 9 and the reflection point 11 on the surface of the substrate 1.
can be easily determined from the respective positional relationships.

From the above, the X position on the X-axis or Y-axis where the scattered light is detected by the light receiver 13 is accurately detected, and the amplifier 14
A signal is obtained and input to the CPU 15. and CPU1
In 5. x-tanθ is calculated, and a signal is sent to the Z-axis position adjustment mechanism 16 to move the amount corresponding to the dimension h obtained thereby, and the surface of the pellicle film 3 is moved perpendicularly to the position of the surface of the substrate 1. let As a result, the foreign matter 10 adhering to the pellicle film 3 can be precisely moved to the height of the reflection point 11, and the polarized laser beam 5 can be properly focused at a height. Foreign matter 10 can be detected accurately.

〔Effect of the invention〕

According to the present invention, it is possible to accurately measure the height of the pellicle frame, that is, the height from the substrate surface to the pellicle film surface, and it is possible to focus on foreign objects on the pellicle film, thereby improving foreign object detection performance. In addition to improving image quality, it is also possible to eliminate blurring of images during microscopic observation. Furthermore, the configuration can be simplified.

[Brief explanation of drawings]

1 and 2 are schematic diagrams showing the principle of foreign matter inspection by a foreign matter inspection device, and FIG. 3 is a diagram illustrating the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Pellicle frame, 3... Pellicle film, 4... Laser oscillator, 5... Polarized laser beam, 6,
10... Foreign matter, 7,8.12... Scattered light, 9,13
...Receiver, 11...Reflection point, 14...Amplifier,
15...CPU, 16...Position adjustment mechanism.

Claims (1)

[Claims] 1. In a foreign matter inspection device that detects foreign matter by scanning a substrate made of a pellicle frame material with a light beam and photoelectrically detecting scattered light from the focal position of the light beam, the light beam focus on the substrate is one or more detection means for photoelectrically detecting the primary scattered light reflected at the pellicle frame; one or more detection means separate from the detection means for photoelectric detection at the upper part of the frame, and detecting the pellicle frame and the focus of the beam using the signal photoelectrically detected at the upper part of the pellicle frame. The height of the pellicle frame is determined based on the angle between the focus position and the primary scattered light detector, and an amount corresponding to the height is moved in the height direction. A foreign matter inspection apparatus characterized in that the position adjustment is performed so that the focal position of the light beam can be aligned on the pellicle film.