JP4595571B2 - Micro Raman spectroscopy apparatus and micro Raman spectroscopy measurement method - Google Patents

Description

  The present invention relates to a microscopic Raman spectroscopic device and a microscopic Raman spectroscopic measurement method that enable measurement of, for example, right-angle scattered light.

  Raman spectroscopic measurement (Raman scattering measurement) irradiates a sample with a light beam from a laser light source, and the spectrum of Raman scattered light generated from the part irradiated with the light beam varies depending on the chemical species and molecules present in the sample. This is a method for analyzing the distribution of two-dimensional physical properties on the sample surface. At present, it is widely known that such a Raman spectroscopic measurement method enables precise analysis of a molecular / crystal structure. For example, industrially, it is known to be a very effective means for discussion of crystallinity of polysilicon, quality control of strained Si having high mobility, and analysis of stress generated by device fabrication. Yes.

  In recent years, attempts to use Raman scattering as a main measuring device for the structure analysis means of organic molecules have become active after the first stagnation period. As a result of the growing expectation for Raman scattering measurement, the spread of microscopic Raman spectrometers that combine microscopes and Raman spectrometers is a new measurement method that greatly draws on the usefulness of Raman scattering. It is in progress.

Using a microscopic Raman spectrometer not only dramatically increases the detection sensitivity of the Raman signal, but also enables the measurement region to be narrowed down to about 1 μm in diameter in the horizontal direction, and uses the mechanism of a confocal microscope. By doing so, the depth resolution can be increased to about 2 μm. Therefore, it is possible to measure a minute space.
With recent developments in laser and CCD detector fabrication techniques, Raman spectroscopes have versatility as general-purpose analyzers and are cheaper than infrared spectrographs. As a result, not only in the field of research and development, but also as an in-line device at the manufacturing site is being examined, the range of use is being expanded.

Under these circumstances, due to recent device miniaturization, cases where measurement is difficult without a microscopic Raman spectroscope have increased, and many techniques relating to the design of microscopic Raman spectrometers have been proposed (for example, , See Patent Documents 1 to 4).
JP 2000-55809 A Japanese Patent Laid-Open No. 11-190695 Japanese Patent Laid-Open No. 9-119865 Japanese Patent Application Laid-Open No. 5-223637

However, all of these technologies are simply a combination of a spectroscope and a laser in a general-purpose microscope, and the measurement sample (specimen) is irradiated with laser light and is 180 ° different from the incident direction. The configuration is such that the scattered light scattered in the direction is detected (observed) in an optical arrangement generally called “backscattering”.
In general, when the light scattering intensity I is expressed using a Raman tensor R having incident light polarization E ₁ , scattered light polarization component Es, and a tensor component proportional to the polarization tensor,
I∝ | E ₁ , R, Es |
It becomes. Here, the Raman tensor R has already been obtained by each crystal system and active vibration.

In order to observe (measure) a desired active vibration in a crystal system to be measured, it is necessary to select a polarization component of incident light and scattered light and perform measurement using an optical system that generates scattered light intensity. Therefore, a general Raman scattering measuring device (Raman spectroscopic device) using a camera lens uses not only backscattering but also a right angle scattering arrangement in which incident light and scattered light are perpendicular to each other, thereby causing an inherent structure. Observing the proper atomic / molecular vibrations.
In addition, for a specific measurement object (sample), it may be necessary to use a forward scattering arrangement in which incident light and scattered light are in the same direction.

  However, since a conventional microscopic Raman spectroscopic device (microscopic Raman scattering device) is simply a combination of an optical microscope and a Raman detection system having a spectroscope / laser as described above, the optical axis is one. It can be adjusted only in dimension. Therefore, it is impossible to perform the measurement in the right angle scattering arrangement of the optical distance generated when the incident light and the Raman scattered light are separated by a microscope, and it is impossible in principle to perform the right angle reflection measurement.

As described above, the reason why the conventional microscopic Raman spectroscopic apparatus cannot perform the measurement in the right angle scattering configuration is that the mechanical configuration becomes complicated and the optical axis alignment becomes very difficult. Is mentioned.
That is, in a general Raman spectroscopic device, when measurement is performed in a right angle scattering arrangement, the distance between the camera lens (condensing lens) and the sample is about 10 to 20 cm, so there are a plurality of camera lenses. However, they do not physically interfere with each other. However, in the microscopic Raman spectroscopic apparatus, the distance between the objective lens and the sample is about 1 mm. These interfered physically, and it was difficult to dispose at the above distance with respect to the sample.

In addition, when measuring with a right angle scattering arrangement with a microscopic Raman spectroscopic device, it is necessary to adjust the focus of the sample three-dimensionally at the nanometer level, and focus adjustment in the right angle scattering measurement with a conventional Raman device is required. Compared to the mm level, a system in which the focus adjustment capability is greatly improved is required.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a micro-Raman spectroscopic device and a micro-Raman spectroscopic measurement method that enable measurement of, for example, right-angle scattered light.

In order to achieve the above object, a microscopic Raman spectroscopic device of the present invention irradiates a sample with excitation laser light for exciting Raman scattered light via a first optical system, and applies Raman scattered light from the sample to the first. A microscopic Raman spectroscopic device for performing spectroscopic spectroscopy using a spectroscope through two optical systems,
An incident-side objective lens that condenses the excitation laser light is provided in the first optical system,
An exit-side objective lens for condensing the Raman scattered light is provided in the second optical system;
A first optical axis of the excitation laser light passing between the entrance-side objective lens and the sample; and a second optical axis of the Raman scattered light passing between the sample and the exit-side objective lens; The angle formed by is adjusted to a predetermined angle.
The predetermined angle may be a substantially right angle.

  According to this microscopic Raman spectroscope, since the exit-side objective lens for condensing the Raman scattered light is provided separately from the entrance-side objective lens for condensing the excitation laser beam, it is not backscattering as in the prior art. For example, by setting the predetermined angle to a substantially right angle, measurement in a right angle scattering arrangement in which incident light and scattered light are at right angles, that is, measurement of right angle scattered light becomes possible.

The microscopic Raman spectroscopic apparatus includes a sample stage on which the sample is arranged. The sample stage serves as a surface on which the sample is arranged with respect to the first optical axis and the second optical axis. Each having a stage surface having an angle of approximately 45 °, and a mechanism for moving the stage surface along the first optical axis and a mechanism for moving the stage surface along the second optical axis. Is preferred.
In this way, by moving the sample stage along the first optical axis, the excitation laser beam can be focused on the sample, and the sample stage can be moved to the first optical axis and the first optical axis. By moving along each of the two optical axes, the second optical axis can be focused on the sample.

Further, the micro Raman spectroscopic apparatus includes a sample stage on which the sample is arranged, and the sample stage forms an angle of approximately 45 ° with respect to the first optical axis and the second optical axis, respectively. A Z stage having a first stage surface and moving along the first optical axis in a state where the angle of the first stage surface is maintained; and a vertical direction of the Z stage on the first stage surface of the Z stage And an XY stage that has a second stage surface parallel to the first stage surface and that arranges the sample on the second stage surface. .
In this way, it is possible to perform focusing on the excitation laser light by moving the Z stage, and further, by combining the movement of the Z stage and the movement of the XY stage, the second movement with respect to the sample is performed. It is also possible to focus on the optical axis.

In the microscopic Raman spectroscopic device, the incident-side objective lens has the first optical axis on the side surface of the sample-side end so that the diameter gradually decreases toward the sample side. An inclined surface having an angle of less than 45 ° is formed with respect to the exit-side objective lens, so that the diameter gradually decreases toward the sample side on the side surface of the end portion on the sample side. An inclined surface having an angle of less than 45 ° with respect to the second optical axis is formed, and the incident-side objective lens and the exit-side objective lens are arranged with their inclined surfaces facing each other. preferable.
In this way, even if the entrance-side objective lens and the exit-side objective lens are arranged so that the first optical axis and the second optical axis are substantially perpendicular, the respective inclined surfaces are made to face each other. Therefore, it is avoided that the entrance-side objective lens and the exit-side objective lens physically interfere with each other.

Further, in the microscopic Raman spectroscopic device, an optical axis alignment laser light source that irradiates a laser beam for optical axis alignment to the arrangement position of the sample through the second optical axis via the emission side objective lens. It is preferable to provide.
According to this configuration, the first laser beam, which is the optical axis of the excitation laser light, is irradiated by irradiating the sample arrangement location with the excitation laser beam and irradiating the sample arrangement location with the laser beam for optical axis alignment. The optical axis can be aligned with the second optical axis of the Raman scattered light that is the optical axis of the laser light for optical axis alignment.

In this microscopic Raman spectroscopic apparatus, it is preferable that the wavelength of the laser beam for aligning the optical axis is different from the wavelength of the excitation laser beam for exciting the Raman scattered light.
In this way, when the laser beam for excitation and the laser beam for aligning the optical axis are simultaneously irradiated on the sample arrangement location, the laser light has different wavelengths, for example, the colors are different, and thus It becomes possible to visually confirm the focal position and the overlapping state thereof.

Further, in the microscopic Raman spectroscopic apparatus, the irradiation position of the excitation laser light at the sample arrangement position and the optical axis alignment on the side opposite to the sample arrangement position on the first optical axis. It is preferable that an observation unit for observing the irradiation position of the laser beam for use is provided.
In this way, by observing the arrangement location of the sample visually or with a CCD camera or the like from the observation unit, for example, the first optical axis that is the optical axis of the excitation laser beam and the laser beam for optical axis alignment It becomes possible to easily align the second optical axis of the Raman scattered light that becomes the optical axis.

Further, in the microscopic Raman spectroscopic device, the irradiation position of the excitation laser light at the sample placement location and the optical axis alignment on the second optical axis on the side opposite to the sample placement location. An observation unit for observing the irradiation position of the laser beam for use may be provided.
Even in this case, by observing the arrangement position of the sample visually or with a CCD camera or the like from the observation unit, the first optical axis that is the optical axis of the excitation laser beam and the light of the laser beam for optical axis alignment It becomes possible to easily align the second optical axis of the Raman scattered light serving as the axis.

Further, in the microscopic Raman spectroscopic device, the incident-side objective lens passes through the first optical axis on the first optical axis on the side opposite to the sample with respect to the incident-side objective lens. A third optical system for introducing Raman scattered light from the collected sample into the spectroscope is preferably connected.
In this case, the sample is irradiated with the excitation laser light through the incident-side objective lens, and the scattered light scattered in a direction different from the incident direction by 180 ° is guided again to the third optical system through the incident-side objective lens. Thus, measurement (observation) by backscattering is also possible.

The microscopic Raman spectroscopic measurement method of the present invention irradiates a sample with excitation laser light for exciting Raman scattered light via a first optical system, and applies Raman scattered light from the sample to a second optical system. A microscopic Raman spectroscopic measurement method in which spectroscopy is performed with a spectroscope,
A step of condensing the excitation laser light with an incident-side objective lens provided in the first optical system and irradiating the sample;
A step of condensing the Raman scattered light excited by the sample with an exit-side objective lens provided in the second optical system and introducing it into the spectrometer.
A first optical axis of the excitation laser light passing between the entrance-side objective lens and the sample; and a second optical axis of the Raman scattered light passing between the sample and the exit-side objective lens; Is characterized in that the angle formed by is adjusted to a predetermined angle.
The predetermined angle may be a substantially right angle.

  According to this microscopic Raman spectroscopic measurement method, excitation laser light is collected by an incident-side objective lens provided in the first optical system and irradiated onto a sample, and Raman scattered light excited by the sample is converted into second Since the light is collected by the exit-side objective lens provided in the optical system and introduced into the spectroscope, the incident light and the scattered light are not generated by backscattering as in the prior art, for example, by setting the predetermined angle to a substantially right angle. It becomes possible to perform measurement in a right angle scattering arrangement in which and are perpendicular, that is, measurement of right angle scattered light.

Further, the micro Raman spectroscopic measurement method includes an optical axis alignment step of aligning the first optical axis and the second optical axis with respect to a predetermined position on the sample stage where the sample is arranged, The optical axis alignment step includes: condensing the excitation laser light at a predetermined position on the sample stage via the incident-side objective lens and adjusting the focal position; and optical axis alignment laser light. And a step of condensing at a predetermined position on the sample stage via the emission side objective lens and adjusting the focal position to the focal position of the excitation laser light.
The first optical axis, which is the optical axis of the excitation laser light, is checked by, for example, visual observation or a CCD camera to confirm that the focal position of the laser light for optical axis alignment matches the focal position of the excitation laser light. The second optical axis of the Raman scattered light that becomes the optical axis of the laser beam for optical axis alignment can be easily aligned.

Hereinafter, the micro Raman spectroscopic apparatus and micro Raman spectroscopic measurement method of the present invention will be described in detail.
FIG. 1 is a diagram showing an embodiment of a microscopic Raman spectroscopic apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a microscopic Raman spectroscopic apparatus. The microscopic Raman spectroscopic device 1 includes an excitation laser light source 2 that emits excitation laser light, and a first optical system 3 that introduces the excitation laser light emitted from the excitation laser light source 2 into a sample. The second optical system 5 for introducing Raman scattered light from the sample into the spectroscope 4 is provided. The sample is arranged on the sample stage 6.

  The first optical system 3 optically connected to the excitation laser light source 2 includes a neutral density filter 7, three semi-transmissive mirrors 8, 9, and 10, and an incident-side objective lens 11. As described above, the optical path for introducing the excitation laser beam emitted from the excitation laser light source 2 into the sample on the sample stage 6 is configured. With this configuration, the first optical system 3 forms an optical path of excitation laser light that passes between the incident-side objective lens 11 and the sample, that is, the first optical axis. ing.

  The second optical system 5 that is optically connected to the sample includes an exit-side objective lens 12, three semi-transmissive mirrors 13, 14, 15, a filter 16, and a condenser lens 17. As described above, the optical path for introducing the Raman scattered light from the sample into the spectroscope 4 is configured. With this configuration, the second optical system 5 forms an optical path of Raman scattered light that passes between the sample and the exit-side objective lens 12, that is, the second optical axis. Yes.

The neutral density filter 7 in the first optical system 3 is provided particularly when the intensity of the excitation laser light emitted from the excitation laser light source 2 is strong. By reducing the intensity of the excitation laser light, Adjustment is made so that laser light of an appropriate intensity is irradiated onto the sample.
The semi-transparent mirror 8 following the neutral density filter 7 is arranged so as to bend the optical path of the excitation laser light that has passed through the neutral density filter 7, that is, the first optical axis at a right angle. An observation port 18 is connected to the opposite side. As for the semi-transmissive mirror 8, as will be described later, when actual measurement (observation) is performed on the sample, a reflective mirror is used instead of the semi-transmissive mirror 8 and the sample passes through the neutral density filter 7. The excitation laser beam may be totally reflected.

  The observation port (observation unit) 18 is a window for an observer to observe visually or with a device such as a CCD camera. The optical path of the observation port 18 passes through the semi-transmissive mirror 8 and coincides with the first optical axis. Therefore, the observation port 18 is arranged on the first optical axis. ing. Based on such a configuration, the observation port 18 is provided with the excitation laser light irradiation position at the sample placed on the sample stage 6 or the place where the sample is placed, and a laser beam for optical axis alignment described later. The irradiation position can be observed.

  The semi-transmissive mirror 9 following the semi-transmissive mirror 8 allows the excitation laser that has passed through the semi-transmissive mirror 8 to pass therethrough and propagates in the first optical axis. Further, the semi-transmission mirror 9 returns from the sample to the first optical axis when measurement (observation) is performed by backscattering with the microscopic Raman spectroscopic apparatus 1 of the present embodiment as will be described later. In order to introduce the Raman scattered light into the spectroscope 4, it is reflected and introduced into the third optical system 19. Therefore, in the case of measuring only the right-angle scattered light component (hereinafter referred to as right-angle scattered light) of the Raman scattered light without performing measurement (observation) by backscattering, the arrangement of the semi-transmissive mirror 9 is changed. It may be omitted.

  The third optical system 19 includes the semi-transmissive mirror 9, the reflective mirror 20, and the semi-transmissive mirror 14 in the second optical system 5, and returns from the sample to the first optical axis. The Raman scattered light is introduced into the second optical system 5 by being reflected by the semi-transmissive mirror 9, the reflecting mirror 19, and the semi-transmissive mirror 14 in this order, and is then introduced into the spectroscope 4.

  The semi-transmissive mirror 10 following the semi-transmissive mirror 9 allows the excitation laser that has passed through the semi-transmissive mirror 9 to pass through as it is and propagates in the first optical axis. The transflective mirror 10 is optically connected to a white light source 21 such as a halogen lamp provided in a direction orthogonal to the first optical axis. White light emitted from the white light source 21 Is reflected in the first optical axis and propagated through the first optical axis to irradiate the sample on the sample stage 6 with white light.

  The incident-side objective lens 11 condenses the excitation laser beam that has passed through the first optical axis, and further the white light, and irradiates the sample on the sample stage 6 or the location of the sample. The entrance-side objective lens 11 is arranged with a distance of about 1 mm on the tip side with respect to the sample or the place where the sample is placed, and as shown in FIG. And a substantially cylindrical holding member 11b for holding it.

  The lens body 11a is held and fixed at the distal end of the holding member 11b, and is disposed in the first optical system 3 so that its optical axis coincides with the first optical axis. The holding member 11b is formed of a metal having high rigidity and stability, such as stainless steel, and the inclined surface 11c is formed so that the tip gradually decreases in diameter toward the tip side, that is, the sample side. Is. The inclined surface 11c is formed so as to form an angle of less than 45 °, for example, about 35 to 40 ° with respect to the first optical axis, that is, the optical axis of the lens body 11a corresponding to the first optical axis. . Here, as a method of forming the inclined surface 11c, the entire tip portion is squeezed so as to be narrowed as it goes to the tip, and the thickness of the holding member 11b also becomes thinner as it goes to the tip. It is preferable to use a technique such as In the example shown in FIG. 2, the inclined surface 11 c is formed over the entire circumference at the tip of the holding member 11 b formed in a substantially cylindrical shape. For example, when the holding member is formed in a rectangular tube shape, etc. Only one of the surfaces may be a slope.

Further, the exit-side objective lens 12 in the second optical system 5 is also formed in the same configuration as the entrance-side objective lens 11 shown in FIG. 2, and includes a lens body 12a and a holding member 12b. A slope 11c is formed at the tip of 12b.
As shown in FIG. 3, the entrance-side objective lens 11 and the exit-side objective lens 12 are arranged such that their distal ends (lens main bodies 11a, 12a side) face the sample stage 6 on which the specimen is placed. It is a thing.

  That is, the entrance-side objective lens 11 and the exit-side objective lens 12 are composed of a first optical axis serving as an optical path of excitation laser light passing between the entrance-side objective lens 11 and the sample, and the sample and the exit-side objective lens. The second optical axis, which is the optical path of the Raman scattered light passing between the two, is adjusted to be a predetermined angle, that is, a substantially right angle in the present embodiment. Here, the term “substantially perpendicular” means that a relatively wide range of about 80 to 100 ° is allowed. That is, since the right-angle scattered light excited from the sample is emitted radially over a relatively wide range, the right-angle scattered light has the second optical axis in the range of about 80 to 100 °. This is because the light enters the exit-side objective lens 12 through the light.

  As shown in FIG. 1, the semi-transmissive mirror 13 following the exit-side objective lens 12 allows the right-angle scattered light collected by the exit-side objective lens 12 to pass through as it is and propagates in the second optical axis. . The semi-transmissive mirror 13 is optically connected to a white light source 22 made of a halogen lamp or the like provided in a direction orthogonal to the second optical axis. The white light emitted from the white light source 22 is , And is introduced into the second optical axis and propagated therethrough so that the sample on the sample stage 6 is irradiated with white light.

  The semi-transmissive mirror 14 following the semi-transmissive mirror 13 allows the right-angle scattered light that has passed through the semi-transmissive mirror 13 to pass through as it is and propagates in the second optical axis. In addition, the semi-transmission mirror 14 returns the first optical axis from the sample when the measurement (observation) by backscattering is performed by the microscopic Raman spectroscopic apparatus 1 of the present embodiment, as will be described later. In order to introduce the Raman scattered light that has passed through the third optical system 19 into the spectroscope 4, it is reflected and introduced into the second optical system 5 (second optical axis). Therefore, when performing measurement (observation) by this backscattering, a reflecting mirror may be used instead of the semi-transmissive mirror 14. Further, in the case of measuring only the right-angle scattered light component (hereinafter, referred to as right-angle scattered light) of the Raman scattered light without performing measurement (observation) by backscattering, the arrangement of the semi-transmissive mirror 14 is changed. It may be omitted.

  The semi-transmissive mirror 15 following the semi-transmissive mirror 14 transmits the right-angle scattered light that has passed through the semi-transmissive mirror 14 as it is, and propagates it in the second optical axis. The semi-transparent mirror 15 has an optical axis for aligning the second optical axis with respect to the sample on the surface that transmits the right-angle scattered light, that is, the surface opposite to the surface on the spectroscope 4 side. The optical path for alignment, that is, the fourth optical system 23 is optically connected. The fourth optical system 23 is a part of the second optical system 5 by having an optical axis that is optically connected to the second optical axis, and includes a semi-transmissive mirror 24. It is. An optical axis alignment laser light source 25 that emits an optical axis alignment laser beam and an observation port 26 are optically connected to the semi-transmissive mirror 24, respectively.

  The laser light source 25 for optical axis alignment is optically connected to the reflecting surface side of the semi-transparent mirror 24, and aligns the optical axis in order to align the second optical axis with respect to the sample or its location as will be described later. For emitting (irradiating) a laser beam for use. The wavelength of the laser beam for aligning the optical axis is preferably different from the wavelength of the excitation laser beam. By changing the wavelength in this way, and in particular, by making these laser beams exhibit different colors, the alignment of the focal positions (spots) of these laser beams can be visually observed during optical axis alignment as will be described later. It becomes easy to confirm.

  The observation port (observation unit) 26 is optically connected to the side opposite to the reflection surface of the semi-transmissive mirror 24, and the observer can visually observe the same as the observation port (observation unit) 18. Or it is a window for observing with apparatuses, such as a CCD camera. The optical path of the observation port 26 reaches the semi-transmissive mirror 15 through the semi-transmissive mirror 24, and is reflected in a right angle direction so as to coincide with the second optical axis. The observation port 26 is disposed on the second optical axis. Under such a configuration, similarly to the observation port 18, the observation port 26 irradiates the sample placed on the sample stage 6 or the irradiation position of the laser beam for optical axis alignment at the place where the sample is placed. In addition, the irradiation position of the excitation laser beam can be observed.

The filter 16 following the semi-transmissive mirror 15 removes Rayleigh light having the same wavelength as the excitation laser light, thereby selectively transmitting Raman light whose intensity is 4 to 5 orders of magnitude smaller than the Rayleigh light. It is. As long as the Rayleigh light is removed and the Raman light is selectively transmitted in this way, a known removal device may be used instead of the filter 16.
The condensing lens 17 condenses the Raman light transmitted through the filter 16 and introduces it into the spectroscope 4, and the spectroscope 4 decomposes the introduced Raman light into wavelength components to obtain a Raman spectrum. Is.

  As shown in FIG. 3, the sample stage 6 for arranging a sample is configured to include a Z stage 27 and an XY stage 28, and a sample such as a crystal thin film is formed on the XY stage 28. S is arranged. The Z stage 27 has a first stage surface 27a that forms an angle of approximately 45 ° (for example, a range of 40 to 50 °) with respect to the first optical axis and the second optical axis, respectively. The XY stage 28 is provided on one stage surface 27a. Further, the Z stage 27 is arranged along the first optical axis, that is, to the optical axis of the incident-side objective lens 11 with the Z stage 27 maintained at the angle of the first stage surface 27a. 3 is provided with a known moving mechanism (not shown) for moving (up and down) in the direction of arrow Z in FIG. 3, thereby adjusting the focus of the excitation laser beam introduced through the first optical axis. Can be done.

The XY stage 28 is provided on the first stage surface 27a of the Z stage 27 so as to be movable in the vertical and horizontal directions, that is, the arrow X and Y directions shown in FIG. The second stage surface 28a is parallel to the stage surface 27a, and the sample S is arranged on the second stage surface 28a. Here, the X direction is a direction along (toward) the moving direction (first optical axis direction) of the Z stage 27 on the first stage surface 27a of the Z stage 27, and the Y direction is In the first stage surface 27 a, the direction is perpendicular to the X direction, that is, the direction perpendicular to the moving direction of the Z stage 27. Based on such a configuration, the sample stage 6 combines the movement of the Z stage 27 and the movement of the XY stage 28 in the X direction, so that the arrangement location of the sample S on the second stage surface 28a is changed to the second stage surface 28a. It can be moved along the optical axis.
The XY stage 28 is provided with a moving mechanism that is different from the moving mechanism for moving the Z stage 27, so that, independently of the movement of the Z stage 27, the XY stage 28 is independent on the first stage surface 27 a. In FIG. 7, the movement in the X direction and the Y direction is possible.

Next, one embodiment of the micro Raman spectroscopic measurement method of the present invention will be described based on the method of using the micro Raman spectroscopic apparatus 1 having such a configuration.
First, the case of measuring right-angle scattered light will be described. When measuring right-angle scattered light in this manner, the semi-transmissive mirror 9 and the semi-transmissive mirror 14 are removed from the respective optical paths (optical axes), and the first optical system 3 and the second optical system 5 The optical connection with the third optical system 19 is cut off. Prior to the actual measurement (observation) of the sample S, as the optical axis alignment step, the first optical axis and the first optical axis are aligned with respect to a predetermined position on the sample stage 6 where the sample S is arranged. The process of aligning with the optical axis 2 is performed. In this optical axis alignment step, for example, a single crystal silicon thin film or the like is arranged as a sample for optical axis alignment on the second stage surface 28a of the XY stage 28 where the sample of the sample stage 6 is arranged. deep.

  In this optical axis alignment step, first, the excitation laser light is condensed on a predetermined position on the sample stage 6, here the sample, via the incident-side objective lens 11, and the focal position is adjusted. . At this time, the white light source 21 is turned on to irradiate the sample with white light so that the irradiation position of the excitation laser beam on the sample can be viewed from the observation port 18. Then, the excitation laser beam is focused by visually recognizing the irradiation position of the excitation laser beam on the sample as a spot.

  Specifically, it is confirmed whether the spot diameter of the excitation laser beam is in focus by visual observation or observation with a CCD camera or the like. At this time, when the focus is not achieved, the focus is adjusted by moving the Z stage 27 of the sample stage 6. Since the Z stage 27 moves along the first optical axis as described above, the focus of the excitation laser light introduced through the first optical axis can be adjusted. At this time, since the observation port 18 is provided on the first optical axis, the center position of the spot is not deviated from the observation port 18 and the spot at a certain position is continuously viewed. Therefore, focus adjustment can be easily performed.

  Simultaneously with or before and after such focus adjustment, this focus, that is, the center of the spot, is adjusted to an appropriate preset position by adjusting the angle of the semi-transparent mirror 8 or the sample stage 6, for example. . However, since this is normally adjusted in the apparatus in advance, it may be omitted in that case.

  Next, while continuing the irradiation of the excitation laser beam, the laser beam for optical axis alignment is condensed on a predetermined position on the sample stage 6, that is, on the sample, via the exit-side objective lens 12, The focal position is adjusted to the focal position of the excitation laser beam. At this time, the white light source 22 is turned on to irradiate the sample with white light so that the irradiation position of the optical axis alignment laser light on the sample can be viewed from the observation port 26. Then, the optical axis alignment between the first optical axis and the second optical axis is performed by visually recognizing the irradiation position on the sample of the laser beam for optical axis alignment as a spot.

  That is, the position (angle) of the exit-side objective lens 12 is finely adjusted to adjust the position of the optical axis alignment laser beam spot, and this is superposed on the excitation laser beam spot, whereby the first optical axis. And the second optical axis are aligned. At this time, the laser beam for alignment of the optical axis and the laser beam for excitation have different wavelengths, and these laser beams have different colors. It can be easily confirmed. Here, the confirmation work by visual observation or the like can be performed by visually recognizing from the observation port 18 or the observation port 26.

Note that if the optical axis cannot be satisfactorily adjusted by fine adjustment of the position of the emission-side objective lens 12, it is possible that the optical path of the excitation laser beam is largely deviated from normal. Therefore, in that case, the angle of the semi-transmissive mirror 8 is adjusted. Then, it is confirmed by moving the Z stage 27 whether the excitation laser beam and the optical axis alignment laser beam are in a gaussian diffusion state at the center object. The angle of the transmission mirror 8 is adjusted again.
The optical axis alignment between the first optical axis and the second optical axis is basically performed by adjusting the position (angle) of the exit-side objective lens 12 as described above. Fine adjustment of the optical axis alignment may be performed by finely moving the Z stage 27 and the XY stage 28 of the sample stage 6.

After optical axis alignment is performed in this manner, the sample is removed from the sample stage 6 and the sample S to be measured is placed on a predetermined position, that is, on the second stage surface 28 a of the XY stage 28. At this time, for example, when the Z stage 27 of the sample stage 6 is moved and the sample and the sample S are exchanged, after the exchange, the Z stage 27 is returned to the original position, and the focusing is performed again by the method described above. I do.
Further, when it is desired to select the measurement position in the sample S in particular, the XY stage 28 is appropriately moved in the X direction and the Y direction while the Z stage 27 is fixed, so that the excitation laser light is focused at the focal position. Align a spot with the measurement position. Such adjustment can be performed by visual observation from the observation port 18 or by photographing with a CCD camera.

After performing focusing in this way and further selecting the measurement position in the sample S, the semi-transparent mirror 8 is replaced with a reflecting mirror as necessary, and then the excitation laser light 2 is emitted from the excitation laser light source 2. Let it emit. Then, the excitation laser light passes through the first optical system 3 and reaches the incident-side objective lens 11, where it is condensed and then irradiates the sample S. Then, the sample S is excited to generate Raman scattered light.
Of the Raman scattered light, particularly right-angle scattered light is collected by the exit-side objective lens 12 having the second optical axis positioned substantially perpendicular to the first optical axis, and further passes through the second optical system 19. Then, it is introduced into the spectroscope 4, where it is decomposed into wavelength components and measured as a Raman spectrum.

  Further, in this microscopic Raman spectroscopic device 1, not only the measurement of the right-angle scattered light but also the scattering by the direction different from the incident direction of the excitation laser beam by 180 ° by using the third optical system 19 described above. Measurement (observation) by backscattering for measuring scattered light can also be performed. When performing measurement (observation) by backscattering in this way, the optical path (light) is first connected to optically connect the first optical system 3 and the second optical system 5 to the third optical system 19. The semi-transparent mirror 9 and the semi-transparent mirror 14 removed from the axis are returned to the positions shown in FIG. 1, and their optical axes are aligned with the optical axes in the corresponding optical system. In addition, about the semi-transmissive mirror 14, it is preferable to replace this with a reflective mirror.

Further, although the sample stage 6 can be used as it is, the stage surface on which the sample S is arranged is particularly exchanged to one that is orthogonal to the first optical axis and directly faces the incident-side objective lens 11. preferable.
When the sample S is arranged on such a sample stage, focusing is performed in the same manner as in the prior art, and then excitation laser light is emitted from the excitation laser light source 2 to perform backscattering measurement. Do.

  When the excitation laser light is emitted in this way, the laser light irradiates the sample S through the incident-side objective lens 11 and excites the irradiated portion to generate Raman scattered light. Of this Raman scattered light, particularly scattered light scattered in a direction 180 ° different from the incident direction passes through the incident-side objective lens 11 again to reach the semi-transmissive mirror 9, where it is reflected to the third optical system 19. Led. Then, the light is reflected by the reflecting mirror 20 and further reflected by the semi-transmissive mirror 14 (or reflecting mirror) to be introduced into the spectroscope 4 through the second optical system 5, where it is decomposed into wavelength components and Raman spectrum. As measured.

  In such a micro Raman spectroscopic measurement method using the micro Raman spectroscopic device 1, the excitation laser light is condensed by the incident side objective lens 11 provided in the first optical system 3 and irradiated onto the sample S. Since the Raman scattered light excited by the sample S is collected by the exit-side objective lens 12 provided in the second optical system 5 and introduced into the spectrometer 4, incident light is not used instead of backscattering as in the prior art. And a measurement in a right angle scattering arrangement in which the scattered light is at right angles, that is, a measurement of a right angle scattered light can be performed.

  In addition, since the inclined surfaces 11c and 12c are provided at the distal ends of the entrance-side objective lens 11 and the exit-side objective lens 12, respectively, the entrance-side objective lens 11 and the exit-side objective lens 12 are connected to the first optical axis. Even if it arrange | positions so that a 2nd optical axis may become a substantially right angle, it can avoid interfering physically mutually by making each inclined surface 11c and 12c oppose. Therefore, in the past, it was very difficult to set the distance between the objective lens and the sample to about 1 mm, but the present invention avoids this and enables the measurement of the right-angle scattered light as described above. Can do.

In addition to the excitation laser light source 2, an optical axis alignment laser light source 25 that emits an optical axis alignment laser beam is provided. By irradiating the arrangement position of the sample S with the laser beam for axis alignment, the first optical axis that is the optical axis of the excitation laser beam and the Raman scattered light that becomes the optical axis of the laser beam for optical axis alignment ( The second optical axis of the (right-angle scattered light) can be easily aligned.
Accordingly, by providing such an optical axis alignment mechanism, the optical axis alignment and focus adjustment can be performed by adjusting the sample stage 6 while observing with the observation ports 18 and 26 by visual observation or the like. Even in the case of performing the measurement by the right angle scattering arrangement, it is possible to adjust the focus on the sample three-dimensionally at the nanometer level, for example.

  In addition, since the optical axis can be adjusted and the focus can be adjusted while observing by visual observation from the observation ports 18 and 26 as described above, these operations can be performed relatively easily. That is, in the past, even in general Raman spectroscopic devices, for example, a high level of skill is required especially for optical axis alignment, and the actual situation is that optical axis alignment is performed depending on intuition based on skill, In the present invention, the optical axis alignment laser light source 25 is provided as described above, although the accuracy is much higher than that of a general Raman spectroscope, so that light can be easily and easily emitted without requiring a high level of skill. Operations such as axis alignment can be performed.

In particular, the following excellent effects can be obtained by making it possible to perform the right angle scattering measurement with this microscopic Raman spectroscope.
(1) Changing the crystal structure generated in the sub-μm region from the current incomplete measurement to a complete measuring means by applying the right angle scattering measurement by the microscopic Raman spectroscopic device to the fine region and detailed observation of the crystal structure. Therefore, it is possible to establish a method for completely observing the control of the crystal structure generated in a device manufactured at a level of μm or less.

Specifically, in devices currently under development on the order of μm to sub-μm, it is possible to make various measurements as shown below, and it has been estimated from the measurement of large samples using a conventional Raman spectrometer. This can be done at the sub-μm level.
・ Crystal structure and orientation of dielectrics used in FeRAM ・ Crystal structure and orientation of dielectrics used as actuators ・ Crystal structure and orientation of ceramics used as SAW devices ・ Polysilicon produced by high or low temperature growth・ Identification and orientation of crystal structure and crystal defects ・ Difference in crystal structure between individual particles produced by powder catalyst ・ Molecular structure of polymers used in organic transistors and organic EL devices

(2) By measuring right angle scattered light (right angle reflection measurement), which has a shorter light penetration distance into the sample S than backscattering measurement, it is (1 / √2) times higher than current backscattering measurement. Measurement of a sample having a small thickness is possible.
That is, assuming that the penetration distance of light necessary for exciting the sample S to excite the sample S is constant, as shown in FIG. 4, in the case of backscattering measurement, the excitation laser beam L1 for the sample S is used. Is incident straight, and Raman scattered light R1 is emitted in the direction opposite to the incident direction. At this time, let the penetration distance of the light be d1.
On the other hand, in the case of measuring the right-angle scattered light, the excitation laser light L2 is incident on the sample S at an angle of 45 °, and the Raman scattered light R2 is emitted in a direction perpendicular to the incident direction. At this time, if the penetration distance of the light is d2, d1 = d2 because the penetration distance of the light for exciting the sample S by the excitation laser light is constant as described above.
However, since d2 does not indicate the distance from the surface of the sample S, that is, the depth, when the actual thickness (depth) d3 required for the measurement in the sample S is calculated from this d2, d3 = ( 1 / √2) d2, which is (1 / √2) times the thickness (d1) in the case of backscattering measurement as described above.

In this way, if a sample having a thinner thickness than before can be measured, a new perspective for science and technology can be opened.
For example, it is possible to shorten the laser light penetration distance by shortening the wavelength of the laser light, but this can be used for a measurement object with a light emission phenomenon that is often seen in organic matter. Can not. Therefore, the molecular structure in the actual thin film state (sub-μm to 10 nm level) is (1 / √2) times higher than that of a functional organic thin film that cannot be observed in the past due to a light emitting phenomenon such as an organic laminated thin film. Identification with high depth resolution is possible.

(3) Since a large Raman signal can be obtained with the large solid angle by using the emission-side objective lens 12, a similar Raman signal can be obtained even in the same time as the Raman measurement in normal backscattering. . Therefore, observation can be performed in a measurement time that is two orders of magnitude shorter than that of normal scattering measurement using a normal Raman spectroscopic device, thereby improving the measurement throughput by two orders of magnitude. Therefore, the microscopic Raman spectroscopic device of the present invention is also applicable to the following substances that can obtain only a Raman signal smaller than the noise level of the CCD element that detects the Raman signal in the measurement of the right angle scattered light using a general Raman spectroscopic device. According to the above, observation is possible by measuring the right-angle scattered light. As a result, it becomes possible to perform a spectroscopically complete crystal structure analysis.
-Fine particles used in various catalysts-Organic substances with small Raman active ingredients

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment, the exit-side objective lens 12 is arranged so that its optical axis (second optical axis) is substantially perpendicular to the optical axis (first optical axis) of the incident-side objective lens 11. However, as shown in FIG. 5, the optical axis (second optical axis) of the exit-side objective lens 12 is arranged on the side opposite to the entrance-side objective lens 11 with the sample S interposed therebetween, and these first optical axis and The angle formed by matching the second optical axis may be approximately 180 °.

  By arranging the exit-side objective lens 12 in this manner, the microscopic Raman spectroscopic device of the present invention can also perform forward reflection measurement (scattering angle 180 °). When performing this forward reflection measurement, as the sample stage 30 holding the sample, the optical axis (first optical axis) of the incident-side objective lens 11 and the optical axis (second optical axis) of the emission-side objective lens 12 are used. It is preferable to use a through hole 31 formed on the optical axis connecting the optical axis).

It is a schematic block diagram which shows typically one Embodiment of the micro Raman spectroscopy apparatus of this invention. It is a schematic block diagram of an entrance side objective lens or an exit side objective lens. It is a schematic block diagram of each objective lens and a sample stage. It is a comparison figure of a right-angle-scattered light measurement and a backscattering measurement. It is explanatory drawing of arrangement | positioning of the output side objective lens in the case of performing a front reflection measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Microscopic Raman spectroscopy apparatus, 2 ... Excitation laser light source, 3 ... 1st optical system, 4 ... Spectroscope, 5 ... 2nd optical system, 6 ... Sample stage, 11 ... Incident side objective lens, 11c ... Slope , 12 ... exit-side objective lens, 12c ... slope, 18 ... observation port (observation part), 19 ... third optical system, 25 ... optical axis alignment laser light source, 26 ... observation port (observation part), 27 ... Z Stage, 27a ... first stage surface, 28 ... XY stage, 28a ... second stage surface

Claims (10)

The excitation laser light for exciting the Raman scattered light, Raman microspectroscopy that through the first optical system is irradiated to the sample, the Raman scattered light from the sample, which spectroscope through the second optical system A device,
An incident-side objective lens that condenses the excitation laser light that has passed through the first optical system ;
An exit-side objective lens that collects the Raman scattered light and makes it incident on the second optical system ;
A sample stage having a stage surface for placing the sample;
Including
Said first optical axis is the optical axis of the excitation laser beam passing between the incident-side objective lens and the sample, the optical axis of the Raman scattered light passing between the sample and the emission side objective lens The angle formed by the second optical axis is substantially a right angle ,
The sample stage includes a mechanism for moving the stage surface along the first optical axis, and a mechanism for moving the stage surface along the second optical axis. Spectrometer. 2. The micro-Raman according to claim 1 , wherein the stage surface forms an angle of about 45 degrees with respect to the first optical axis and forms an angle of about 45 degrees with respect to the second optical axis. Spectrometer. The sample stage has a first stage surface that forms an angle of approximately 45 ° with respect to the first optical axis and the second optical axis, respectively, and maintains the angle of the first stage surface. A Z stage that moves along the first optical axis, and a second stage that is movable in the vertical and horizontal directions on the first stage surface of the Z stage, and is parallel to the first stage surface. Raman spectroscopic apparatus according to claim 1, characterized in that it comprises an XY stage, the placing the sample with a stage surface on the second stage surface. The incident-side objective lens has an inclined surface that forms an angle of less than 45 ° with respect to the first optical axis so that the diameter gradually decreases toward the sample side on the side surface of the end portion on the sample side. Is formed,
The exit-side objective lens has an inclined surface having an angle of less than 45 ° with respect to the second optical axis so that the diameter gradually decreases toward the sample side on the side surface of the end portion on the sample side. Is formed,
The microscopic Raman spectroscopic apparatus according to any one of claims 1 to 3 , wherein the incident-side objective lens and the emission-side objective lens are arranged with their inclined surfaces facing each other. 2. An optical axis alignment laser light source that irradiates a laser beam for optical axis alignment at a position where the sample is disposed through the second optical axis via the emission-side objective lens. The micro Raman spectroscopic apparatus according to any one of to 4 . 6. The micro Raman spectroscopic apparatus according to claim 5 , wherein a wavelength of the laser beam for aligning the optical axis is different from a wavelength of the excitation laser beam for exciting the Raman scattered light. The irradiation position of the excitation laser beam and the irradiation position of the laser beam for aligning the optical axis are observed on the first optical axis on the opposite side of the sample from the arrangement position of the sample. The microscopic Raman spectroscopic apparatus according to claim 5 , further comprising an observation unit for performing the operation. The irradiation position of the excitation laser beam and the irradiation position of the laser beam for aligning the optical axis are observed on the second optical axis on the side opposite to the arrangement position of the sample. The microscopic Raman spectroscopic apparatus according to any one of claims 5 to 7 , further comprising an observation unit for performing the operation. Raman scattering from the sample collected by the incident-side objective lens through the first optical axis on the first optical axis on the side opposite to the sample with respect to the incident-side objective lens light, Raman spectroscopy apparatus according to any one of claims 1 to 8, a third optical system to be introduced into the spectroscope is characterized in that it is connected. The excitation laser light for exciting the Raman scattered light, Raman microspectroscopy that through the first optical system is irradiated to the sample, the Raman scattered light from the sample, which spectroscope through the second optical system A measuring method,
A step of condensing the excitation laser light with an incident-side objective lens provided in the first optical system and irradiating the sample;
Raman scattered light excited by the sample, the second emission-side objective lens provided in the optical system and focused to have a, a step of introducing into the spectrometer,
Furthermore, the first optical axis of the excitation laser beam passing between the incident-side objective lens and the sample, and the second light of the Raman scattered light passing between the sample and the emission-side objective lens The angle formed by the axis is adjusted to a predetermined angle, and the first optical axis and the second optical axis are aligned with a predetermined position on the sample stage where the sample is placed. With an alignment process,
The optical axis alignment step is a step of focusing the excitation laser light through the incident-side objective lens on a predetermined position on the sample stage to adjust the focal position thereof;
A step of condensing the laser beam for optical axis alignment at a predetermined position on the sample stage through the emission-side objective lens, and adjusting the focal position to the focal position of the excitation laser beam. Characteristic micro-Raman spectroscopy measurement method.

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