JPH068917U - Optical microscope for three-dimensional image observation of surface micro-defects / adhesions - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the optical microscope without using a special inspection device and enable stereoscopic image observation of surface micro-defects and deposits at low cost. [Constitution] In a catoptric microscope for refracting light from a light source at a right angle in a mirror portion, irradiating a sample through an objective lens, and making reflected light incident on an eyepiece for observation, before refraction at a right angle, and / or , 3D image observation characterized in that a slit is provided later, the light from the light source is limited to the end part, the sample is irradiated with a condenser lens at a certain angle, and further the auxiliary light is irradiated from below the sample. For optical microscope.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical microscope capable of stereoscopically observing surface microscopic defects and microscopic deposits on a photomask substrate or the like.

[0002]

[Prior art]

 Conventionally, as a device for observing surface micro-defects and micro-adhesions such as photomask substrates, a device for detecting the scattered light by scanning a laser spot on a reticle to determine the presence or absence of foreign matter and its size (JP-A-58-62544), a device for irradiating a light beam from one of the light-transmissive plate-like objects, detecting scattered light generated from the foreign matter adhering to the plate-like object, and detecting the presence or absence of the foreign matter ( JP-A-59-186324), using an X-ray, coating an organic film having a minimum film thickness that almost absorbs light in a specific wavelength range outside the wavelength range of the X-ray to scatter foreign matters. A method of inspecting light (Japanese Patent Laid-Open No. 63-2 89814), and a foreign substance inspecting apparatus (Japanese Patent Laid-Open No. 2-189449) in which irradiation is performed with an irradiation light and a light-receiving angle so as to cause a specific phase shift through a dustproof film. Issue gazette) etc. There.

In addition, as for the observation of minute defects and adhering substances on the photomask substrate by an optical microscope, as shown in FIG. 7, illumination light was directly applied from directly above the sample.

[0004]

[Issues to be solved by the device]

 However, the invention disclosed in the conventional example is only a foreign matter inspection device using a special device, and the device is complicated when the foreign matter is found when using an optical microscope because of its complicated structure and cost. It was necessary to replace it and it was not possible to easily inspect for foreign matter.

Further, in the observation with an optical microscope, since the illumination light is directly applied from directly above the sample such as an adhered substance, uneven foreign matter is uniformly illuminated from directly above, and it is difficult for the unevenness to be bright or dark. When the shape of the image is unclear and it is difficult to judge whether it is convex (adhered matter) or concave (defect), and if it is necessary to distinguish between irregularities such as foreign matter, look at the microscope and pick up the observation object with a needle to make a distinction. At that time, the surface of the photomask substrate may be damaged.

Therefore, it has been desired to develop an optical microscope that improves the optical microscope and enables three-dimensional image observation of surface microscopic defects and deposits at low cost without using a special inspection device.

It is an object of the present invention to solve the above-mentioned drawbacks and to provide a stereoscopic image observation of surface micro-defects and deposits at a low cost by improving an optical microscope.

[0008]

[Means for Solving the Problems]

 Therefore, as a result of earnest research to solve the above-mentioned problems, the inventor of the present invention has found that the light from the light source is refracted at right angles by the mirror part, irradiates the sample through the objective lens, and the reflected light is incident on the eyepiece lens. In a reflection optical system microscope for observing, if the light from the light source is limited by the slit before and / or after being refracted at a right angle, and if the sample is irradiated with a condenser lens at a certain angle, The present invention has been completed based on the knowledge that the problems can be solved and stereoscopic images can be observed with an optical microscope.

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a view showing the concept of the present invention. In an optical reflection microscope, an incident light 1 is reflected by a slit 3 (and / or 4) provided before and / or after being refracted at a right angle by a mirror unit 2. Part is blocked and is limited to light at the top or bottom. The incident light 1 limited to the end is refracted from the vicinity of the end of the condenser lens 5, and is irradiated onto the sample at a constant angle θ from one direction.

At this time, the slit may be provided only in the front part 3 of the mirror part to limit the incident light, or may be provided only in the position 4 after refraction of the mirror part, and further, in the mirror part. It is possible to limit the incident light by arranging both slits before and after refraction so as to be synchronized with each other. When the mirror is a half mirror and the reflected light from the sample is incident on the mirror section 2 again, the slit may be provided only on the front section 3 of the mirror section.

The irradiation angle θ to the sample can be freely adjusted by adjusting the transmission holes of the slits 3 or 4 or by the condenser lens 5.

When the present invention is used in an optical microscope, as will be described later, it is incorporated in the optical microscope as a stereoscopic observation jig 8 (see FIG. 6) in which a mirror portion and a slit portion are integrated. This allows a stereoscopic image to be easily observed with an optical microscope.

Since most of the incident illumination light is cut by the slit, the auxiliary light is emitted from the lower portion of the sample to compensate for the insufficient light amount. The amount of auxiliary light can be adjusted by adjusting the aperture of the condenser diaphragm of the auxiliary light source.

FIG. 2 shows an optical path diagram in which the present invention is applied to an optical reflection microscope, in which the mirror section 2 and the slit 3 are incorporated in the optical reflection microscope as a detachable stereoscopic observation jig 8. .

The slit provided in the stereoscopic observation jig 8 has, for example, a transmission hole 9 having a shape shown in FIGS. 3 and 4, and is configured to transmit only a part of the incident light end portion. In addition, as shown in Fig. 5, a rectangular transmission hole is provided in the large slit portion, and the movable slit is freely moved in the stereoscopic observation jig to prepare the transmission hole and the slit. It is also possible to adjust the amount of transmitted light.

Depending on the slit shape, the sample may be irradiated with incident light having a certain angle such as the side direction in the case of the shape shown in FIG. 3 or the one-circumferential direction in the case of FIG. It can be appropriately determined depending on the shape of the slit.

When the slit shown in FIG. 5 is used for a stereoscopic observation jig, first, the transmission hole is fully opened to irradiate the foreign matter onto the foreign matter from directly above, and the focus is determined by the condenser lens. Then, the slit is moved so that only the transmitted light at the end is transmitted and the sample is irradiated at an angle from one direction, or at the stage where the focus is set, the sample is replaced by the slit shown in FIGS. 3 and 4. Irradiation can be performed at an angle from one direction.

[0018]

[Effect of the present invention]

 According to the present invention, by giving a contrast by shading to a microscope observation image and making the image three-dimensional, a micro defect on the photomask substrate, which was difficult in the conventional optical microscope observation, is a defect (concave). It is possible to accurately and easily identify whether there is a deposit (convex) or not without scratching the surface of the substrate. In addition, since it is possible to observe the three-dimensional shape of the deposit and how damage is introduced in the defect, it is possible to accurately and easily classify and identify the defect and deposit in the investigation of the cause of the defect and deposit generation. Further, since the auxiliary light is used, the sample can be clearly observed. Further, since the incident light can be limited by the movable slit in the stereoscopic observation jig, it is possible to inexpensively obtain the stereoscopic optical microscope by making a simple improvement to the conventional optical microscope.

[Brief description of drawings]

FIG. 1 is a diagram showing the concept of the present invention.

FIG. 2 is an optical path diagram using the present invention in an optical reflection microscope.

FIG. 3 is a plan view of a slit.

FIG. 4 is a plan view of a slit.

FIG. 5 is a plan view of a slit.

FIG. 6 is an optical path diagram of a stereoscopic observation jig incorporating a slit and a mirror section.

FIG. 7 is a conventional optical path diagram.

[Explanation of symbols]

 1 Incident light 2 Mirror 3, 4 Slit 5 Lens 6 Sample 7 Auxiliary light 8 Stereoscopic observation jig 9 Light transmitting hole 10 Eyepiece 11 Objective lens 12 Light source

Claims (3)

[Scope of utility model registration request] 1. The light of a light source is refracted at right angles by a mirror part,
In a catadioptric microscope that irradiates a sample through an objective lens and allows reflected light to enter an eyepiece for observation, a slit is provided before and / or after refraction at a right angle to limit light from a light source, and An optical microscope for observing a stereoscopic image, characterized in that a sample is irradiated at a constant angle with a condenser lens. 2. The light of the light source is refracted at right angles by the mirror part,
In a catoptric optical microscope that irradiates a sample through an objective lens and allows reflected light to enter an eyepiece for observation, a slit is provided before and / or after refraction at a right angle, and light from a light source is limited to an end portion. An optical microscope for observing a stereoscopic image, characterized in that the sample is irradiated with a condenser lens at a constant angle, and further auxiliary light is irradiated from below the sample. 3. An optical microscope for observing a stereoscopic image according to claim 1, wherein the mirror portion and the movable slit are incorporated as a jig for stereoscopic observation.