JPS63193041A - Apparatus for inspecting foreign matter - Google Patents

Abstract

PURPOSE:To inspect the entire surface in a support frame without applying masking, by mounting a means receiving the direct reflected beam from a foreign matter adhesion preventing film obtained when laser beam is allowed to irradiate said film and making it possible to confirm the shape and position of the foreign matter adhesion preventing film equipped with a frame. CONSTITUTION:A reticle 1 converted with a foreign matter adhesion preventing film 3 is fixed to a specimen stage moving in an X-direction through a support frame 2 and the laser beam from a laser beam source 8 is formed into a spot image on the surface of the reticle 1 and scanning is performed with the rotation of a polygon mirror 5. A foreign matter detection system consists of fibers 6, 6' and photoelectric detectors 7, 7' detecting the scattering beam due to the foreign matter on the reticle 1 and a zero order optical detection system is constituted of fiber 6'', a photoelectric detector 7'' detecting the zero-order beam directly reflected from the film 3 and the frame 2. It is discriminated whether laser beam is reflected from the film or the frame and foreign matter is inspected from the outputs of the detection systems, 6, 6', 7, 7'.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an apparatus for detecting foreign matter such as minute dust attached to an object to be inspected by using a scattering phenomenon of laser light or the like.
For example, when detecting foreign matter adhering to the pattern surface and back surface of an LSI photomask or reticle, even if a foreign matter adhesion prevention film is attached to the surface of the photomask or reticle through a support frame. , relates to a foreign matter inspection device that enables foreign matter detection.

[Prior art] In recent years, pit memory, IM bit DRAM, etc.
BACKGROUND ART High integration and miniaturization of ICs are progressing. As a result, tolerances for foreign matter adhering to wafers, photomasks, reticles, etc., which cause a decrease in the yield of IC manufacturing, are becoming stricter year by year. In particular, when a step-and-repeat reduction projection exposure device is used to repeatedly print a circuit pattern on a reticle onto eight surfaces of a wafer, the number of foreign particles is doubled by the number of steps and printed onto the entire surface of the wafer, reducing the yield of IC manufacturing. significantly decreases.

Therefore, recently, a foreign matter adhesion prevention film is attached to the reticle to prevent foreign matter from adhering to the reticle surface.

The foreign matter adhesion prevention film is generally a thin film of nitrocellulose, and is referred to as a so-called pellicle film. This thin film then covers the surface of the reticle via a support frame (pellicle frame). Even if the foreign matter adhesion prevention film is installed, it is possible that foreign matter has adhered to the reticle surface or the foreign matter adhesion prevention film before that, so it is necessary to check whether foreign matter is still attached to the reticle surface or the foreign matter adhesion prevention film. It is common practice to test whether

Conventionally, when inspecting a reticle with such a foreign object adhesion prevention film attached, the light scattered from the support frame cannot be distinguished from the signal light from the foreign object, so the support frame is also determined to be a foreign object. There was a problem. Therefore,
The method used was to electrically mask the support frame.

[Problems to be Solved by the Invention] However, various errors occur, such as a reticle outline error, a pattern position error with respect to the reticle outline, a support frame bonding error, a support frame outline error, and a reticle alignment error. Considering this fact, it is necessary to perform extra masking on the shape of the support frame attached to the reticle.

That is, there is a drawback that the inner peripheral portion of the support frame of the foreign matter adhesion prevention film, which should originally be inspected for foreign matter, cannot be inspected.

In addition, when inspecting a reticle that has a support frame with a foreign matter adhesion prevention film attached that has a different shape from the support frame with a foreign matter adhesion prevention film that has been masked as described above, it is necessary to change the electrical masking part. The problem was that it was necessary.

The present invention eliminates the above-mentioned drawbacks of the conventional example in a foreign matter inspection device that is applied to an object to be inspected, such as a reticle, to which a foreign matter adhesion prevention film is attached via a support frame. It is an object of the present invention to enable inspection of the entire area within the support frame, and to similarly enable inspection of the entire area within the support frame even if the shape of the support frame changes.

[Means and effects for solving the problems] In order to achieve the above object, the foreign matter inspection apparatus according to the present invention includes an optical system that irradiates a light beam onto the surface of an object to be inspected, and a a first photoelectric detector that receives scattered light generated from the object to be inspected and outputs a photoelectric signal; and a direct reflected light of the beam reflected by a foreign matter adhesion prevention film attached to the object to be inspected via a support frame. A second photoelectric detector receives light to automatically detect the shape and attachment position of the framed foreign matter adhesion prevention film, and the first photoelectric detector and the second photoelectric detector detect the above-mentioned object to be inspected. Or means for detecting foreign matter adhering to the foreign matter adhesion prevention film.

As a result, when detecting foreign objects by irradiating a light beam onto an object to be inspected such as a reticle, the light beam is currently irradiated on the foreign object adhesion prevention film based on the photoelectric output of the second photoelectric detector. It can be determined whether the irradiation is done on the support frame or on the support frame.

Therefore, if the output of the first photoelectric detector is taken when the light beam is irradiating the foreign matter adhesion prevention film instead of the support frame, a foreign matter inspection signal only within the support frame can be obtained without masking. Become.

Note that if a movable sample stage is provided, the object to be inspected is placed on it, and the inspection is performed by scanning the light beam while moving the sample stage, the entire surface of the object to be inspected can be easily inspected.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a foreign matter inspection device according to an embodiment of the present invention. The figure shows the apparatus of this embodiment, including a reticle to which a support frame with a foreign matter adhesion prevention film is attached, as well as a light beam irradiation optical system, a foreign matter signal detection system, a detection system for the position and shape of the support frame with a foreign matter adhesion prevention film, etc. The main components are shown as seen diagonally from above.

In the figure, a reticle 1 is fixed to a sample stage (not shown) while being covered with a foreign matter adhesion prevention film 3 via a support frame 2. This sample stage moves in the X direction for inspection.

On the other hand, the laser beam emitted from the laser light source 8 is reflected by the rotating polygon mirror 5, and is imaged as a laser spot on the surface of the reticle 1 via the imaging lens 4. Then, the surface of the reticle 1 is scanned as the polygon mirror 5 rotates.

The movement of the sample stage in the X direction is performed simultaneously with the scanning of the laser spot, and thereby the entire surface of the reticle is inspected for foreign matter.

6.6' is a fiber, 7.7' is a photoelectric detector,
These constitute a foreign object detection system. The foreign object detection system detects foreign objects by detecting laser scattered light scattered by foreign objects on the reticle. Along with this foreign matter inspection, the zero-order light directly reflected by the foreign matter adhesion prevention film 3 and the support frame 2 is
It is detected by a detection system consisting of a fiber 6' and a photoelectric detector 7''.Based on the outputs of the detection systems 6'' and 7#, it is determined whether the light beam is reflected by the foreign matter adhesion prevention film 3 or the support frame 2. becomes distinguishable. Therefore, the foreign matter detection system 6.6' when the light beam is reflected by the foreign matter adhesion prevention 1lI3
, 7.7', the entire surface of the support frame 2 can be inspected.

That is, conventionally, the foreign object detection system 6.6', f.

In step 7', since the light scattered by the support frame 2 was also determined to be a foreign object, it was necessary to electrically mask the support frame 2 part. Furthermore, in order to account for variations in the bonding position of the support frame 2 with respect to the reticle 1, extra masking must be applied to the frame shape, making it impossible to inspect the inner periphery of the support frame 2 for foreign matter. Therefore, in this embodiment, the shape and position of the support frame 2 can be recognized by detecting the reflected light from the foreign matter adhesion prevention film 3, and there is no need to mask the shape of the support frame 2 as required in the past. It is now possible to inspect the entire interior of the support frame 2.

[Effects of the Invention] As explained above, the foreign matter inspection device according to the present invention is equipped with a means for receiving light directly reflected from the foreign matter adhesion prevention film of a light beam such as a laser beam. The shape and position of the support frame of the membrane can be recognized, and even when the attachment position of the support frame varies or when inspecting objects with support frames of different shapes, the entire surface inside the support frame can be recognized. It has the effect of allowing inspection.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a foreign matter inspection device according to an embodiment of the present invention. 1 Reticle, 2: Support frame, 3: Foreign matter adhesion prevention film (pellicle film), 4: Imaging lens, 5: Polygon mirror, 6: Line-shaped fiber for receiving foreign matter signal on reticle surface, F: Linear fiber for receiving foreign matter signal on reticle surface. Foreign object signal photoelectric detector, 6': Line fiber for receiving foreign object signal on the pellicle surface, 7': Foreign object signal photoelectric detector on the pellicle surface, 6'':
Line-shaped fiber for receiving reflected light from foreign matter adhesion prevention film, 7″: Photoelectric detector for reflected light from foreign matter adhesion prevention film, 8: Laser light source.

Claims (1)

[Claims] 1. An optical system that irradiates a light beam onto the surface of an object to be inspected; and a first system that receives scattered light on the object to be inspected of the light beam irradiated from the optical system and outputs a photoelectric signal. In order to detect the shape and attachment position of the foreign matter adhesion prevention film pasted on the object to be inspected via a support frame, a photoelectric detector is used to detect the direct reflected light of the light beam reflected by the foreign matter adhesion prevention film. a second photoelectric detector that receives light and outputs a photoelectric signal; and a second photoelectric detector that receives light and outputs a photoelectric signal; What is claimed is: 1. A foreign object inspection device comprising: means for detecting foreign objects. 2. The foreign matter inspection device according to claim 1, wherein the object to be inspected is placed on a movable sample stage.