JP2006300886A - Microscopic optical analysis system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microscopic optical analysis system hardly generating thermal drift of a visual field of an optical microscope even if brightness of illumination light is raised, and detecting and identifying surely even fine foreign matters or the like. <P>SOLUTION: This microscopic optical analysis system 1 has: the optical microscope 13 for enlarging and observing a sample; an infrared spectroscopic analysis part 20 for performing infrared spectroscopic analysis on an observation field of the optical microscope 13 as an optical analysis part; and an illumination mechanism 28 for illuminating the observation field in the optical microscope 13. The illumination mechanism 28 has: a light guide part 32 having an illumination light irradiation part for irradiating out illumination light LB toward the observation field to the first end side, wherein the second end side is extended to the outside of the optical microscope; and a light source 23 for supplying the illumination light to the second end side of the light guide part 32. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microscopic optical analysis system.

JP-A-6-347399 JP 2001-215193 A

  In a semiconductor wafer and an integrated circuit using the same, there is an increasing demand for a microscopic optical analysis system that performs an optical analysis of a micro area while observing a micro area on a sample surface with a microscope. Examples thereof include a microscopic Fourier transform infrared spectrophotometer (so-called microscopic FT-IR: Patent Document 1), a microphotoluminescence spectrophotometer, and a microscopic Raman spectrophotometer (Patent Document 2).

  In the conventional microscopic optical analysis system described above, the observation field of view by the optical microscope is illuminated by a light source such as a halogen lamp built in the optical microscope to observe and analyze the foreign matter. The built-in halogen lamp of around 100 W that is normally used has a problem that the light intensity is not so high and the field of view cannot be sufficiently bright at a high magnification, making it difficult to detect minute foreign matters. If a foreign substance or the like cannot be accurately detected in the field of view of the microscope, it cannot be irradiated with the measurement probe, and the spectroscopic analysis cannot be performed accurately.

  In this case, in order to increase the light quantity of the light source, it is considered that it is easier to identify minute foreign matters by replacing with a high-intensity type lamp with high output. However, if the light source is built in the optical microscope as in the past, there is a problem that the field of view of the microscope is likely to cause thermal drift due to the heat generated by the light source. That is, when a temperature change occurs in the apparatus, there is a problem that the stage and the like are extended by heat generated from the light source during measurement, and the irradiation position of the probe is slightly shifted. In particular, in the case of a small foreign matter, the foreign matter may be removed from the irradiation spot of the probe, and data may not be obtained during measurement. In this case, if the magnification is reduced, the amount of illumination light in the entire field of view increases, so that a small foreign object may be detected somehow. However, if the probe is switched from that state to high magnification, the foreign matter moves due to the thermal drift described above, and the probe cannot be reliably irradiated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a microscopic optical analysis system that is unlikely to cause thermal drift in the field of view of an optical microscope even when the brightness of illumination light is increased, and that can reliably detect and identify minute foreign matters.

Means for Solving the Problems and Effects of the Invention

In order to solve the above problems, the microscopic optical analysis system of the present invention is:
An optical microscope for magnifying the sample,
An optical analyzer that performs optical analysis on the observation field of the optical microscope;
With an illumination mechanism for illuminating the observation field within the optical microscope,
The illumination mechanism has an illumination light projecting portion for projecting illumination light toward the observation visual field on the first end portion side, a light guide portion whose second end side extends out of the optical microscope, and a first guide of the light guide portion. And a light source for supplying illumination light to the two ends.

  According to the microscopic optical analysis system of the present invention, the illumination mechanism for illuminating the observation field in the optical microscope has the illumination light projecting unit that illuminates the illumination light toward the observation field on the first end side. In addition, the second end side has a light guide portion extending from the observation visual field to the outside of the optical microscope, and a light source for supplying illumination light is provided on the second end side of the light guide portion. In other words, a light source that generates a large amount of heat is placed outside the optical microscope, and the illumination light is guided to the observation field by a light guide. Therefore, even if the luminance of the illumination light is increased, the observation field caused by the heat generated by the light source This makes it possible to perform microanalysis on a wafer more reliably.

  The light guide part can be constituted by an optical fiber. Even if the light source is relatively far away (for example, 50 cm or more and 3 m or less from the observation field of the optical microscope), the optical fiber can be guided to the observation field without greatly reducing the illumination light. In addition, by utilizing the flexibility unique to optical fibers, it can be flexibly placed inside or around the device in an arbitrarily deformed state, making the system more compact and preventing interference with surrounding objects around the system, etc. It contributes effectively.

  The light source unit can be configured to include a light source disposed to face the end of the light guide portion and a reflecting mirror disposed on the opposite side of the light guide facing the end of the light guide portion. . Thereby, the direct light beam from the light source is guided to the light guide in a state where it is overlapped with the light beam reflected by the reflecting mirror, and the amount of light applied to the microscope field can be further increased. This effect becomes even more prominent by providing a condensing part that condenses the illumination light from the light source toward the end of the light guide part.

  A normal halogen lamp can be used as the lamp used for the light source. By adopting the present invention, even when using a high-power halogen lamp that generates a large amount of heat, thermal drift in the observation field is unlikely to occur, and the amount of illumination light in the observation field can be increased. Easy. On the other hand, it is more desirable to use a metal halide lamp as the lamp used for the light source because the amount of light can be increased as compared with the halogen lamp even with the same power consumption.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a microscopic Fourier transform infrared spectrophotometer system (hereinafter referred to as microscopic FT-IR system) as an embodiment of the microscopic optical analysis system of the present invention. The microscopic FT-IR system 1 includes an optical microscope 13 for magnifying and observing a sample, an infrared spectroscopic analysis unit 20 as an optical analysis unit that performs infrared spectroscopic analysis on the observation field of the optical microscope 13, And an illumination mechanism 28 for illuminating the observation field within the optical microscope. The illumination mechanism 28 has a light guide portion 32 that illuminates the illumination light LB toward the observation visual field on the first end portion side, and a light guide portion 32 whose second end side extends out of the optical microscope, and the light The light source 23 which supplies illumination light to the 2nd end side of the guide part 32 is comprised.

  The main part of the microscopic FT-IR system 1 is disclosed in Japanese Patent Application Laid-Open No. 3-14845. Reference numeral 101 denotes a sample placed on a light-transmitting sample stage (not shown). Reference numeral 102 denotes a condensing mirror for condensing the light beam from the visible light source 23 or the infrared light source 24 and irradiating the sample 101 with it. Reference numeral 105 denotes a first movable mirror that can move in the direction of a double-headed arrow 106. When the first movable mirror 105 is at a position indicated by a solid line, visible light is present, and when the first movable mirror 105 is at a position indicated by a virtual line, Each of the infrared rays is directed toward the condenser mirror 102.

  Reference numeral 107 denotes an objective mirror that transmits the transmitted light from the sample 101 side. Further, in the infrared spectroscopic analysis unit 20, reference numeral 108 denotes a first beam splitter installed behind the objective mirror 107, which is composed of, for example, a half mirror. Reference numerals I and II denote two branched light paths (hereinafter referred to as a first branched light path I and a second branched light path II) formed behind the first beam splitter 108. A knife-edge mask 109 is provided at the image point of the objective mirror 107 in the first branch optical path I, and a second movable mirror 111 movable in the direction of a double-headed arrow 110 is provided behind the mask 109. When the second movable mirror 111 is at the position indicated by the solid line, the light beam that has traveled along the first branch optical path I is directed toward the second beam splitter 115 described later, and is at the position indicated by the phantom line. The light beam travels through the fixed mirror 112 toward the infrared detector 113. Then, nothing is provided at the image point of the objective mirror 107 in the second branch optical path II, and a fixed mirror 114 is provided in the vicinity of this image point.

  Reference numeral 115 denotes a second beam splitter, which couples the light beams that have passed through the two branch optical paths I and II. For example, the second beam splitter 115 includes a half mirror, and a CCD camera 116 and a monitor 117 are disposed behind the second beam splitter 115. Is provided. The condensing mirror 102 and the objective mirror 107 constitute an optical system of the microscope 13, respectively, and a transmission magnified observation image by the visible light source 23 is detected by the CCD camera 116, and the image is observed by the monitor 117, and red in a desired visual field By switching to the external light source 24, infrared spectroscopic analysis can be performed from the input waveform of the infrared detector 113.

  FIG. 1 shows a measurement or observation mode based on a so-called transmission method in which the light emitted from the visible light source 23 or the infrared light source 24 is transmitted through the sample 101. By appropriately switching the movable mirror, it is possible to switch to the so-called reflection method measurement or observation mode in which the light beam irradiated from the light source 23 or 24 is reflected on the sample 101. That is, the microscopic FT-IR system 1 can take measurement and observation modes in the transmission method and the reflection method, respectively.

  Next, the illumination mechanism 28 on the visible light source side 23 side has a light source in a light source unit 30 placed outside the optical microscope 13, and the illumination light from the light source is optically transmitted by an optical fiber 32 that forms a light guide. It is guided into the microscope 13. The illumination mechanism 128 on the infrared light source 24 side has almost the same configuration as the illumination mechanism 28 on the visible light source side 23 except for the light source type.

  As shown in FIG. 2, the light source unit 30 includes a light source 23 disposed to face the end of the optical fiber 32 (light guide portion), and a side opposite to the end of the optical fiber 32 of the light source 23. And a reflecting mirror 24 arranged. Further, a condensing unit 25 made of a metal plate or the like that condenses the illumination light from the light source 23 toward the end (on the second end side) of the optical fiber 32 is also provided. In the present embodiment, the periphery of the optical fiber 32 is covered with a bellows-like flexible tube, and the second end portion on the light source side is connected to the light collecting unit 25 of the light source unit 30 via the joint portion 32s. On the other hand, a connector 32p is provided on the first end side of the optical fiber 32 serving as an illumination light projecting portion, and is connected to the lens case 17 attached to the optical microscope 13 in FIG. 1 via the connector 32p. The illumination light emitted from the end of the optical fiber 32 in the connector 32p is converted into a parallel beam through the lens 16 in the lens case 17, and illuminates the observation field of the sample 101 in FIG.

  In FIG. 2, the visible light source 23 is constituted by a metal halide lamp. A metal halide lamp is a glass tube in which an electrode, a rare gas (such as Ar) for starting the lamp, mercury that serves as a buffer gas, and a metal halide that emits desired light are enclosed. The metal halide is evaporated by the heat generated by the hot electrode, and a thermionic current is generated by glow discharge between the electrodes. Visible excitation light having a wavelength specific to the type of metal halide can be obtained by colliding the thermal electron stream with constituent atoms of the evaporated metal halide and exciting it. Various metal halides such as sodium iodide, thallium iodide, indium iodide and scandium iodide are used in combination as appropriate, and various emission light colors can be obtained depending on the type and encapsulation ratio of the metal halide. Obtainable. A lighting circuit for discharge control (well-known) is required, but it has higher luminous efficiency than halogen lamps, and can produce a larger amount of emitted light with the same power consumption. Thus, it becomes possible to detect / identify fine foreign matters more reliably. In the light source unit 30, a lighting circuit 23d for the metal halide lamp is provided.

  The infrared light source 24 used on the illumination mechanism 128 side in FIG. 1 can be configured by a general infrared lamp.

  According to the microscopic FT-IR system 1, the light source unit 30 is provided outside the optical microscope 13, and the illumination light from the light source incorporated therein is guided to the optical microscope 13 through the optical fiber 32, and the observation field of view of the sample 101 is increased. Illuminated. As a result, even if the brightness of the illumination light is increased, thermal drift in the viewing field due to the heat generated by the light source is less likely to occur, and furthermore, a higher-intensity metal halide lamp is used as the light source. If the probe is irradiated with infrared light for the probe, the type of foreign matter can be easily identified by spectral analysis of the scattered light.

  The application target of the present invention is not limited to a microscopic Fourier transform infrared spectrophotometer, but can be similarly applied to a microphotoluminescence spectrophotometer and a microscopic Raman spectrophotometer.

The schematic diagram which shows the whole structure of the microscopic FT-IR system which is an example of the microscopic optical analysis system of this invention. The figure which shows the structural example of an illumination mechanism.

Explanation of symbols

1 Microscopic FT-IR system (microscopic optical analysis system)
13 Optical microscope 20 Infrared spectroscopic analysis unit (optical analysis unit)
23 Visible light source 28 Illumination mechanism 32 Optical fiber (light guide part)

Claims (5)

An optical microscope for magnifying the sample,
An optical analyzer for performing optical analysis on the observation field of the optical microscope;
An illumination mechanism for illuminating the observation field in the optical microscope,
The illumination mechanism has an illumination light projecting portion for projecting illumination light toward the observation visual field on the first end portion side, and a light guide portion whose second end side extends out of the optical microscope, and the light guide And a light source that supplies the illumination light to the second end side of the unit. The microscopic optical analysis system according to claim 1, wherein the light guide portion is configured by an optical fiber. The light source unit includes the light source disposed to face the end of the light guide portion, and a reflecting mirror disposed on the opposite side of the light source facing the end of the light guide portion. The microscopic optical analysis system according to claim 1 or 2. The microscopic optical analysis system according to claim 3, further comprising a condensing unit that condenses illumination light from the light source toward an end of the light guide unit. The microscopic optical analysis system according to any one of claims 1 to 4, wherein the light source is a metal halide lamp.

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