Optical microscope device and testing apparatus comprising same
View Patent ↗The present invention allows observation or capturing of a high-contrast image of a sample for which sufficient contrast cannot be obtained in bright-field observation, such as a wafer having a pattern with a small pattern height. According to the present invention, a sample is illuminated through an objective lens used for capturing an image, and an imaging optics are provided with an aperture filter so that an image is captured while light of bright-field observation components is significantly attenuated.
1. An optical microscope device for observing or capturing a magnified image of a sample, the device comprising: an illumination light source; an illumination optics adapted to guide a light beam from the illumination light source to the sample; an imaging optics adapted to collect a light beam from the sample and form an image of the sample; a first aperture filter arranged on a system stop plane of the imaging optics, the first aperture filter being adapted to attenuate a specular reflection component; an image sensor arranged on an image plane of the imaging optics, the image sensor being adapted to convert an optical image into an electric signal; and a second aperture filter arranged in the illumination optics on a plane that is conjugate to the plane on which the first aperture filter is arranged; wherein one of the first or second aperture filter has a circular aperture with a coherence factor that is less than 1 (a<1), and the other has an annular aperture.
2. The optical microscope device according to claim 1 , wherein the first aperture filter has a circular aperture with a coherence factor that is less than 1 (σ<1), and the second aperture filter has an annular aperture.
3. The optical microscope device according to claim 1 , wherein the second aperture filter has a circular aperture with a coherence factor that is less than 1 (σ<1), and the first aperture filter has an annular aperture.
4. The optical microscope device according to claim 1 , wherein
the annular aperture is formed as a space interposed between a first non-light-transmissive, disc-shaped member and a second non-light-transmissive member, the second member being arranged on an outer side of the aperture and defining an extension of the aperture, and
a support member that extends from the second member in a manner supporting the first member is arranged in parallel with or at a right angle to a pattern formed on a sample plane.
5. The optical microscope device according to claim 4 , wherein the support member includes four support members that support the first member from four directions.
6. The optical microscope device according to claim 1 , wherein a relationship between transmission characteristics of the first and second aperture filters is decided so that an average brightness of an optical image formed by the imaging optics is located in a linear region of photoelectric conversion characteristics of the image sensor.
7. The optical microscope device according to claim 1 , wherein a light beam, from the illumination optics, is caused to irradiate the sample through an objective lens of the imaging optics.