JPS5998524A - Inspecting apparatus of transparent material - Google Patents

Abstract

PURPOSE:To inspect a defect, detect heterogeneous light, improve inspection sensitivity and thereby defect a minor damage by detecting disturbance of deflected light due to the defect of mask through irradiation of glass mask with the deflected light. CONSTITUTION:A general light 9 emitted from a laser source 4 changes to the deflected light 10 when it transmits through the first deflecting plate 5. Then, it enters the glass mask 1 at a right angle and transmits to the upper direction. The deflected light 10. When the deflected light 10 transmits the damage-free area of glass mask 1, it transmits only in the direct vibrating direction. Since the light is shielded by the second deflecting plate 6, a light sensor 8 does not detect the light in such amount larger than the specified one. The deflected light 10 contains the light 11 in the other vibrating direction when it transmits the flaw 2 of glass mask 1. This light 11 transmits without any shielding by the second deflecting plate 6, and then transmits the slit plate 7 and is detected by the light sensor 8.

Description

[Detailed description of the invention] The present invention relates to a transparent body inspection device.

Generally, photolithography (photographic processing), which is essential for manufacturing semiconductor devices, requires a process of selectively exposing a photoresist film applied to a wafer. This photo-sensitization process uses a glass mask made by forming an opaque film made of chromium or the like in the desired pattern on the surface of a transparent glass plate, and exposes the wafer with a photoresist film on it to expose it to light. It is done well.

If such a glass mask has defects (scratches, foreign matter, dirt, etc.), the photoresist film will be exposed to a pattern different from the desired pattern, causing defects. Since this mask is used repeatedly for photosensitive processing on hundreds of wafers, this poses a serious problem in the manufacture of semiconductor devices. Therefore, an inspection of the mask is performed. In particular, scratches on transparent objects cannot be removed even by cleaning the glass mask, and more rigorous inspection is required.

2. Description of the Related Art Conventionally, as this type of a flaw inspection apparatus for transparent bodies, an apparatus as shown in FIG. 1, for example, has been proposed.

This device is designed to inspect flaws 2 by making parallel light rays incident on the end face of a glass mask 1 and detecting the light that is diffusely reflected at the flaws 2 on the mask.

However, in many of these devices for inspecting defects on transparent materials, the end surface of the glass mask is glass-like, and parallel light rays are diffusely reflected at the end surface, reducing the amount of incident light, making it difficult to detect defects. It had the disadvantage of poor sensitivity.

The object of the present invention is to overcome the drawbacks of the prior art.

It is an object of the present invention to provide a transparent body inspection device that has particularly good flaw detection sensitivity.

Hereinafter, five embodiments of the present invention will be explained according to embodiments shown in the drawings.

FIGS. 2 and 3 are longitudinal sectional views showing an embodiment of a transparent body inspection apparatus according to the present invention.

In this embodiment, a glass mask 1 as a transparent body to be inspected for defects is supported almost horizontally, and a laser light source 4 is provided below the mask 1 so as to irradiate a light beam perpendicularly to the mask surface. ing.

A polarizing plate (polaroid plate) 5 is interposed between the laser light source 4 and the back surface of the mask 1, and this polarizing plate 5 polarizes general light (light whose vibration direction is not limited) from the laser light source 4. Only light in a limited vibration direction (polarized light) is allowed to pass through. A second polarizing plate 6 is provided above the glass mask 1, and this polarizing plate 6 is configured to block the polarized light produced by the first polarizing plate 5. A slit plate 7 is provided directly above the second polarizing plate 6, and a light receiver 8 is provided directly above the slit plate 7 so as to be able to detect the light transmitted through the slit plate 7.

Although not shown, the support mechanism for the glass mask and optical systems such as a laser light source and a polarizing plate are configured so that the glass mask 1 is irradiated with light relatively scanned in the X and Y directions.

Next, the flaw detection function will be explained in particular.

When the general light 9 from the laser light source 4 passes through the first polarizing plate 5, it becomes polarized light 10, which enters the glass mask 1 at right angles and is transmitted upward.

As shown in FIG. 2, when the polarized light 10 is transmitted through an undamaged portion of the glass mask 1, it is transmitted only in the same vibration direction. Since this polarized light 10 is blocked by the second polarizing plate 6, the light receiver 8 does not detect an amount of light exceeding a predetermined value. Thereby, it is inspected that there are no scratches at the scanning point on the glass mask 1.

As shown in FIG. 3, when the polarized light 10 passes through the scratches 2 on the glass mask 1, it includes light 11 in another vibration direction (returns to general light). A portion of this light 11 passes unobstructed through the second polarizing plate 6, passes through the slit plate 7, and is detected by the light receiver 8.

Through this detection, it is determined that the glass mask 10 has a flaw at the scanning point. Note that this phenomenon partially occurs even when foreign matter, dirt, etc. other than the scratches are attached to the glass mask.

According to this embodiment, defects are inspected by irradiating the glass mask with polarized light and detecting disturbances in the polarized light due to defects in the mask, so there is no need to detect foreign light and the inspection sensitivity is low. Even extremely high scratches, especially minute scratches, can be detected. therefore.

It is possible to prevent defective glass masks from being sent to the photosensitive processing process, improve the yield of wafers, and improve the productivity and quality of semiconductor devices.

Note that since the slit plate increases the S/N ratio of the light receiver, it can be omitted. Additionally, if the light source is a device that can emit polarized light, the first polarizing plate can be omitted, and if the receiver can accurately detect changes in the vibration direction, the second polarizing plate can also be omitted. can do.

The present invention is not limited to inspecting defects in glass masks;
It can be applied to all devices that inspect defects in transparent bodies in all fields, such as plate glass and lenses.

As described above, according to the present invention, it is possible to accurately inspect scratches on a transparent body.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a conventional example. FIGS. 2 and 3 are longitudinal sectional views showing the principle of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Glass mask, 2... Scratch, 4... Laser light source, 5... First polarizing plate, 6... Second polarizing plate, 7...
・Slit plate, 8... Light receiver.

Claims (1)

[Claims] 1. A transparent body inspection device that inspects defects by irradiating the transparent body with polarized light and detecting disturbances due to defects that may exist in the transparent body from the polarized light transmitted through the transparent body.