JPH0629853B2 - Light scattering image information analyzer - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an apparatus for analyzing a fine structure or composition in an object by utilizing light scattering or fluorescence.

[Prior Art] Generally, for example, a microscope is used when minutely observing a crystal or the like. For such a microscope,
There are ordinary optical microscopes, polarization microscopes, phase contrast microscopes, electron microscopes, and scanning electron microscopes. The basic operation of such a microscope is to irradiate the sample observation surface with light or an electron beam, and to capture the relative hue or difference in light and darkness at each part of the observation surface as a pattern. That is, the relative difference in the transmittance or reflectance of light or electron beam or the secondary electron emission efficiency due to the difference in the structure or composition on the sample observation surface is to be examined. Therefore, it can be said that it is a simple method for comprehensively grasping the observation surface.

However, for example, when trying to observe the array of a specific element in a certain cross section in a crystal sample or a lattice defect, etc. as a pattern, information from other elements (eg, element array, lattice defect, etc.) is overlaid in a conventional microscope. It is also observed that the same information cannot be obtained from the same kind of element due to the influence of the irradiation angle of light or electron beam, the orientation of the crystal, etc. It was difficult to properly observe and grasp.

Further, the transmission microscope requires the sample to be in a thin state, and the reflection type requires the observation surface to be exposed on the surface, which is not necessarily the best one.

FIG. 3 shows a light-scattering image information analysis apparatus previously proposed by the present inventors in order to eliminate such a defect (Japanese Patent Laid-Open No. 54-1).
(See No. 09488).

This apparatus irradiates a sample with light that can pass through the sample, and uses scattered light or fluorescent light generated inside the sample by the irradiation light as an information source for observation. In the figure, 11 is a laser light source, 12 is a moving table to which a mirror 13 and an optical system 14 are fixed, 15 is a moving rail, and 16 is a moving rail.
Is a sample mounting table, and 17 is a sample. Reference numeral 18 denotes an observation optical system that defines an observation optical axis that is substantially perpendicular to the beam optical axis L. Also, 19
Is an information acquisition means for converting the scattered light generated inside the sample 17 into information for observation, and the figure illustrates a photosensitive material such as a photographic dry plate. It may be an image sensor or the like.

In the figure, the beam L from the light source 11 has its optical path determined by the mirror 13, the polarization direction is also determined if necessary, is narrowed down by the optical system 14, and is incident on the sample 17 from the side.
The incident beam L passes through the sample 17 and is scattered in the process. If the sample 17 is a crystal, the scattered light will be affected by the crystal structure in the beam transmitting portion. For example, fluctuation of refractive index, mixture of colloidal particles,
As a result of lattice defects, non-uniform orientation of crystals, etc., scattering that is not seen in homogeneous crystals is exhibited. Therefore, the crystal structure in the sample 17 can be known by observing the scattered light with the observation optical system. As the observation method, the photosensitive material 19 may be exposed as shown in the drawing, or may be photoelectrically converted by a photoelectric detector or an image pickup device (not shown) and electrically processed to be displayed as a pattern on the display device.

Here, in order to obtain the information on the cut surface inside the sample 17 as an image, the beam L must be horizontally scanned by the movable table 12 which holds the mirror 13 and the optical system 14 and is movable in the arrow A direction. I have to. Further, in this case, it is desirable to dispose an elongated slit in the same direction as the beam in front of the surface of the photosensitive material and move the slit in synchronization with scanning of the beam for recording.

Even when the beam L itself is not scanned, the beam L needs to be relatively scanned with respect to the sample 17 by moving the sample mounting table 16 in the direction of arrow B in the drawing. In this case, the photosensitive material 19 must be horizontally moved, for example, in the direction of arrow C in the figure in synchronization with the movement of the sample mounting table 16 while taking the image magnification into consideration.

As described above, in the conventional light scattering image information analysis device, when observing a predetermined surface of the object to be inspected, it is necessary to scan the light beam or the object to be inspected, and a scanning mechanism for that is provided. I had to. Furthermore, when observing scattered light with a photoelectric detector, it is essential to perform image processing in synchronization with these scans, and in-situ observation and direct observation cannot be performed.

[Object of the Invention] An object of the present invention is to solve the above-mentioned problems in the conventional system.
In a light-scattering image information analysis device for observing the desired cross section based on scattered light or fluorescent light inside the object to be inspected by this light flux by transmitting a light flux to a desired cross section of the object to be inspected, the light beam is slit-shaped. Based on the concept of focusing and irradiating an object to be inspected as a line beam and transmitting the light beam to the entire surface of the desired cross section at the same time, scanning of the light beam or the object to be inspected is unnecessary, and in-situ of the desired cross section without image processing. It is to enable observation and direct observation.

[Examples] Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 shows a light scattering image information analysis apparatus according to an embodiment of the present invention. 1 is a laser light source, 2 is a mirror, 3 is an optical system, and 4 is a sample to be observed. Reference numeral 5 is an observation optical system, and 6 is a photosensitive material.

FIG. 2 shows the internal structure of the optical system 3. Reference numeral 31 is a cylindrical lens (cylindrical lens), and 32 is a spherical lens.

The present invention will be described in detail with reference to FIGS. 1 and 2.
In FIG. 1, the optical path of the beam from the light source 1 is determined by the mirror 2 and the polarization direction is determined as necessary.
Incident on. As shown in FIG. 2, the optical system 3 is composed of a cylindrical lens and a spherical lens, and the incident beam is focused by these lenses in a slit shape in a direction parallel to the cross section to be observed, and a line beam L is formed as a sample 4 Is incident horizontally from the left side of the drawing. As a result, the line beam L is transmitted through the sample 4, but is scattered in the process, and the beam L of the scattered light is upward in the drawing.
The light substantially perpendicular to the optical axis of is incident on the observation optical system 5 and becomes observable. In this way, by using a light beam as a line beam, it is possible to simultaneously irradiate the entire desired cross section of the sample 4 with one light beam, and it is necessary to scan the laser beam L, the sample 4, the photosensitive material 6, and the like. Instead, scattered light from the sample can be simultaneously observed over the entire surface for in-situ observation or direct observation.

In particular, since the slit-shaped line beam L is formed by the optical system 3 using the cylindrical lens and the spherical lens and is made incident on the sample 4, it is very thinly focused (several 10 μm).
A line beam L can be used, which enables observation with high positional accuracy. Further, since there is no laser or sample scanning drive system, the entire desired cross section can be observed within the time taken by the TV camera to capture one screen (approximately 1/30 second in this embodiment).

Further, in the above-mentioned embodiment, only 90 ° scattering is described, but a scattered image can be obtained at other angles. The light scattering intensity is as follows:
Forward scattering is larger than 90 ° scattering. Therefore, a light scattering image information analysis device using forward scattering is also conceivable. FIG. 4 is a layout diagram when observing a plate-like defect by forward scattering. 41 is a cylindrical lens and 42 is a spherical lens.

The present invention seeks to obtain information inside an object by observing scattered light. With visible light, it is effective for observing defects such as organisms and transparent crystals, but it can also be used as infrared light to observe the inside of semiconductor crystals.
In this case, the semiconductor crystal has a large absorption of light by conduction electrons, and the infrared light has a problem that the light receiving sensitivity of the image pickup tube is deteriorated. However, the present invention is performed by using a strong light flux that transmits them. If carried out, defects in the semiconductor crystal can be observed. In the above, the case where scattered light having the same wavelength as the irradiation light is observed has been described.
According to the apparatus of the present invention, it is needless to say that the crystal arrangement, lattice defect, etc. of the object can be observed based on the fluorescence generated from the object.

[Effects of the Invention] As described above, according to the present invention, since the light beam to be applied to the sample is focused in a slit shape, it is not necessary to scan the light beam or the object to be inspected, or without further image processing. In-situ observation and direct observation are possible.
Further, since the laser and the scanning of the sample are not required, the apparatus can be made simpler, and real-time observation, that is, observation that requires almost no time for measurement, is possible. Furthermore, since the cylindrical lens and the spherical lens are used, the slit-shaped line beam can be narrowed down very thin, and observation with high positional accuracy becomes possible.

And in particular, ultrashort pulsed laser light, for example, a few pico (1
Even a laser with a pulse width of 0 ^-12 ) seconds can capture a scattered light image or a fluorescence image from an object to be inspected, and therefore can observe the cross-sectional state of the object to be inspected at a certain moment. Has a remarkable effect. That is, it is also effective for observing a cross section at a certain moment of an object to be inspected whose position or state changes with time. For example, the movement of fine particles contained in a predetermined cross section in a fluid moving at high speed can be detected. It is also possible to perform observation in time series.

The effect of being able to observe such a wide area in real time makes it possible to comprehensively evaluate the object to be inspected by comparing it with a transmission image observed in real time.

Furthermore, the present invention also has a remarkable effect that a person skilled in the art cannot expect, such that stacking faults and plane defects such as twins can be effectively observed by using a thin slit-shaped light beam. In other words, defects can be observed with both thin slit-like light flux and point-like light flux with a small diameter, but in the case of point-like light flux, the anisotropy of scattered light from a planar defect is small and scattered in a wide range of directions, and observation from a wide range is possible. Therefore, it cannot be recognized that the defect is planar.

On the other hand, as in the present invention, in the case of a thin slit-shaped light beam, the anisotropy is large in the slit direction component,
Since strong scattered light is generated from a planar defect only in a specific direction, it can be accurately recognized that the defect is a planar defect. In other words, the characteristics of the defect can be known more accurately by observing with a light beam with a large cross section, but since the light beam needs to be incident within the depth of focus of the observation optical system, a thin slit light beam is optimal. .

[Brief description of drawings]

FIG. 1 is a block diagram of a light scattering image information analysis apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of an optical system that linearly focuses light from a light source, and FIG. 3 is conventional light scattering. FIG. 4 is a configuration diagram of the image information analysis apparatus, and FIG. 4 is an arrangement diagram when observing a plate-like defect by forward scattering. 1,11: Laser light source, 3,14: Optical system, L: Line beam, 31,41: Cylindrical lens, 32,42: Spherical lens, 4,17: Sample, 5,18: Observation optical system, 6,19 : Information acquisition means (photosensitive material or image pickup tube).

Claims (1)

[Claims] 1. An irradiation optical system having a focusing optical system composed of a cylindrical lens and a spherical lens for irradiating an object to be inspected with a slit-like light beam passing through the object to be inspected, and the slit-like light beam. Scattering light or fluorescent light in the object to be inspected by an observation optical system for observing the scattered light or fluorescence from a direction intersecting a plane including the optical axis of the light flux and the longitudinal axis of the slit. Image information analysis device.