JP2018141670A - Laser-induced analysis device, sample plate to be used for the same, and laser-induced analysis method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique improves analysis sensitivity in analyzing a sample solidified by evaporation and drying from a liquid state by a Laser-Induced Plasma Spectroscopy.SOLUTION: A laser-induced analysis device 10 comprises: a sample plate 1 that has a concavity part where a low position part lower than other part is formed at a prescribed part of a bottom surface; a heating processing unit 2 that heats a liquid sample dripped at the concavity part to evaporate and dry the liquid sample; a light source 5 that irradiates the concavity part where a dried solidification sample obtained by evaporation and drying is held with laser light; and an analyzer 8 that acquires a light emission spectrum of light generated by the irradiation of the laser light.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for analyzing a sample solidified by evaporation to dryness from a liquid state by laser-induced plasma spectroscopy (LIPS).

  In a manufacturing process of a semiconductor substrate or the like, a cleaning process for removing contaminants or the like attached to the semiconductor substrate or the like is frequently performed. This cleaning process is often performed using various cleaning liquids such as deionized water and chemicals (so-called wet cleaning).

  In wet cleaning, in order to reduce the consumption of cleaning liquid (reduction of manufacturing costs) and reduce environmental burden, the cleaning liquid once used for cleaning is not discarded as it is, but is circulated through a circulation line in which a filter is inserted. May be used repeatedly. In such an embodiment, as the number of times the cleaning liquid is repeatedly used increases, impurities in the cleaning liquid (specifically, for example, various metals removed from the cleaning target of the cleaning device in the wiring process (for example, wiring) As the content of copper, etc.) used in the process gradually increases, the cleaning function of the cleaning liquid decreases and it becomes difficult to sufficiently clean the object to be cleaned. Therefore, when the cleaning liquid is used repeatedly, it is preferable to monitor the content of impurities in the cleaning liquid in real time.

  Patent Document 1 describes an apparatus for measuring the concentration of a contained substance in a liquid sample such as a cleaning liquid. Here, first, a liquid sample is dropped on a predetermined plate, and this is heated and evaporated to dryness. Then, the dry sample left on the plate is analyzed by laser-induced plasma spectroscopy to determine the amount of substance contained in the dry sample.

Here, “laser-induced plasma spectroscopy” will be described. In this analysis method, first, a sample to be analyzed (in the case of Patent Document 1, a dry sample) is irradiated (focused) with a short pulse of laser light. Then, high-temperature and high-density plasma (destructive plasma) is generated, and a substance (atom) on the sample surface is excited at a spot where the laser beam is condensed. Each excited substance undergoes a state transition while emitting light of a specific wavelength. Therefore, by acquiring the emission spectrum of the light generated at this time with a spectrograph and specifying the position (wavelength) and intensity of the peak appearing in the emission spectrum, the type and amount of the substance contained in the sample can be specified. Can do.
In addition, when specifying the substance contained in gas by this method, it may be called "Laser-Induced Breakdown Spectroscopy (LIBS)."

JP, 2006-95139, A

  Laser-induced plasma spectroscopy is a technique in which a short pulse of laser light is focused on a solid sample surface to generate a destructive plasma, thereby exciting the atoms present in the plasma and analyzing its intrinsic emission. . Therefore, in order to specify the amount of a substance contained in a liquid sample such as a cleaning liquid using this technique, as described above, the liquid sample is dropped on a predetermined sample plate and heated to evaporate to dryness. The process of solidifying is required.

  A sample plate generally used in the past is a thin plate-like member having a concave portion formed on one main surface, and a liquid sample is dropped into the concave portion. Here, if the amount of the liquid sample held in the concave portion is large, the time required for evaporation to dryness becomes long, so the amount is a very small amount of about 100 μL or less. The amount of dry sample obtained by evaporating and drying such a small amount of liquid sample is very small. Furthermore, since this small amount of dry sample is dispersed and deposited on the bottom surface of the concave portion of the sample plate, the concentration of laser light is reduced. There is only a very small amount of dry sample in the area corresponding to the light spot. For this reason, the intensity of the peak appearing in the emission spectrum is not sufficiently large, and it has been difficult to obtain sufficient analysis sensitivity.

  The present invention has been made in view of the above problems, and provides a technique capable of improving analysis sensitivity in analyzing a sample solidified by evaporation to dryness from a liquid state by laser-induced plasma spectroscopy. It is an object.

The present invention made to solve the above problems
A laser induced analyzer comprising:
A sample plate having a recess formed in a predetermined position on the bottom surface with a lower position part lower than other parts, and
A heat treatment section for heating and evaporating and drying the liquid sample dropped in the recess;
A light source that irradiates a laser beam to the low position portion of the concave portion in which the dried sample obtained by evaporation to dryness is held;
An analyzer for obtaining an emission spectrum of light generated by the laser light irradiation;
Is provided.

  When the solvent of the liquid sample dropped in the concave part of the sample plate is evaporated, the concentration of the solution gradually increases, and the remaining relatively high concentration solution gathers at the low position and evaporates to dryness there. . Therefore, the amount of precipitation of the dried sample per unit area is larger in the low position portion than in other portions. In this way, the analysis sensitivity can be improved by obtaining the emission spectrum by irradiating the laser beam aiming at the low position portion where the amount of the dried solid sample deposited is larger than the other portions.

Preferably,
The light source irradiates each of a plurality of different positions in the low position portion with laser light,
The analyzer acquires the emission spectrum obtained with each irradiation.

In the final stage of evaporation to dryness (ie, the stage in which the most concentrated trace solution remaining at the end evaporates to dryness), the last solution remaining in the recess forms droplets due to surface tension. Finally, it is evaporated to dryness. A portion (droplet dried portion) where the droplets are finally evaporated to dryness has a larger amount of deposited solid sample than other portions. Therefore, if the droplet dried portion can be irradiated with laser light, particularly high analysis sensitivity can be obtained.
If the low position portion is not provided, this droplet dried portion may exist in the entire region in the recess. Therefore, in order to irradiate the droplet dried portion with laser light with a high probability, Therefore, the laser beam must be irradiated evenly over the entire region, and the number of necessary irradiations is increased (and the time required for analysis is increased). On the other hand, according to the above-described configuration in which the low position portion is provided, the droplet dry portion is always present somewhere in the low position portion, so that the droplet dry portion is irradiated with laser light with high probability. In addition, it is not necessary to uniformly irradiate the entire region in the recess with the laser beam, and it is only necessary to irradiate each of a plurality of different positions in the low position portion. That is, it is possible to irradiate a laser beam with a high probability to the droplet dried portion with a small number of irradiations. This makes it possible to obtain high analysis sensitivity while keeping the time required for analysis short.
In addition, if it becomes possible to irradiate the dried portion of the droplet with laser light with high probability, it is also possible to obtain an analysis result with little variation regarding the sample. That is, even in the same sample, the peak intensity of the spectrum obtained differs greatly when the laser beam is irradiated on the dried portion of the droplet and when it is irradiated on the other portions. When each case is mixed, this becomes an analysis error. However, if it is possible to stably irradiate the dried portion of the droplet with laser light, the generation of such an analysis error is suppressed and analysis with little variation is performed. Results are obtained.

Preferably,
An integrated data acquisition unit for acquiring integrated data obtained by integrating a plurality of emission spectra obtained by laser light irradiation to the plurality of positions;
Is further provided.

  By acquiring integrated data obtained by integrating emission spectra obtained for a plurality of different positions in the low position portion, the influence of noise can be reduced and the S / N ratio can be increased.

Preferably,
An average data acquisition unit for acquiring average data obtained by averaging a plurality of emission spectra obtained by laser light irradiation to the plurality of positions;
Is further provided.

  By obtaining average data obtained by averaging the emission spectra obtained for each of a plurality of different positions in the low position portion, the influence of noise can be reduced and the S / N ratio can be increased.

Preferably,
In the laser induced analyzer,
The bottom surface of the recess is circular in plan view;
A groove is formed along the outer peripheral edge of the bottom surface.
In this sample plate, the bottom of the ring-shaped groove formed along the outer peripheral edge of the circular bottom forms the low position portion.

Alternatively, preferably
In the laser induced analyzer,
The bottom surface of the recess is circular in plan view;
The bottom surface has a shape inclined downward from the center toward the outer peripheral edge.
In this sample plate, the vicinity of the outer peripheral edge of the circular bottom constitutes the low position portion.

Alternatively, preferably
In the laser induced analyzer,
The bottom surface of the recess is circular in plan view;
The bottom surface has a shape inclined downward from the outer peripheral edge toward the center.
In this sample plate, the central portion of the circular bottom forms the low position portion.

Alternatively, preferably
In the laser induced analyzer,
The bottom surface of the recess is circular in plan view;
A recess having a circular shape in plan view is formed at the center of the bottom surface.
In this sample plate, the bottom of the recess formed in the center of the bottom surface constitutes the low position portion.

Alternatively, preferably
In the laser induced analyzer,
The bottom surface of the recess is circular in plan view;
A plurality of arc-shaped grooves in plan view are formed at intervals along the outer peripheral edge of the bottom surface.
In this sample plate, the bottom of each arc-shaped groove formed along the outer peripheral edge of the bottom surface constitutes the low position portion.

Or preferably,
In the laser induced analyzer,
The bottom surface of the recess is circular in plan view;
A plurality of circular recesses in a plan view are formed at intervals along the outer peripheral edge of the bottom surface.
In this sample plate, the bottom of each recess formed along the outer peripheral edge of the bottom surface constitutes the low position portion.

In any of the above sample plates, the amount of precipitation of the dried sample per unit area in the low position portion is greater than in other portions. Therefore, analysis sensitivity can be improved by aiming at this low position and irradiating laser light to obtain an emission spectrum.
Further, when each sample plate is provided, for example, while rotating the sample plate around an axis passing through the center of the bottom surface of the recess, intermittently from a light source fixedly arranged in a predetermined posture toward a low position portion ( By irradiating the laser beam (preferably at a constant interval), it is possible to irradiate the laser beam to a plurality of different positions in the low position portion. That is, it is possible to irradiate a plurality of different positions in the low position portion with laser light without providing a complicated mechanism.

The present invention is also directed to a sample plate used in a laser induced analyzer. That is, the sample plate is
It has a recessed part into which a liquid sample is dropped, and has a low position part lower than other parts at a predetermined place on the bottom surface of the recessed part.

  When a liquid sample is dropped into the recess of the sample plate and the solvent is evaporated, the concentration of the solution gradually increases, and the remaining relatively high concentration solution gathers at the lower position and evaporates to dryness there. To do. Therefore, the amount of precipitation of the dried sample per unit area is larger in the low position portion than in other portions. In this way, the analysis sensitivity can be improved by obtaining the emission spectrum by irradiating the laser beam aiming at the low position portion where the amount of the dried solid sample deposited is larger than the other portions.

The present invention is also directed to a laser induced analysis method.
That is, the laser induced analysis method is:
Dropping a liquid sample into the concave portion of the sample plate having a concave portion in which a lower position portion formed at a lower position than the other portions is formed at a predetermined position on the bottom surface;
Heating and evaporating and drying the liquid sample dropped in the recess;
Irradiating a laser beam to the low position portion of the concave portion in which the dried sample obtained by evaporation to dryness is held;
Obtaining an emission spectrum of light generated by the laser light irradiation;
Is provided.

  According to said invention, analysis sensitivity can be improved by irradiating a laser beam aiming at the low position part of a sample plate, and acquiring an emission spectrum.

The figure which shows the structure of a laser induction analysis apparatus typically. The top view and sectional drawing of a sample plate. The figure for demonstrating a mode that the liquid sample dripped at the sample plate evaporates to dryness. The figure for demonstrating the irradiation position of the laser beam with respect to a sample plate. The figure which shows a series of flows concerning an analysis. The top view and sectional drawing of the sample plate which concern on a 1st modification. The top view and sectional drawing of the sample plate which concern on a 2nd modification. The top view and sectional drawing of the sample plate which concern on a 3rd modification. The top view and sectional drawing of the sample plate which concern on a 4th modification. The top view and sectional drawing of the sample plate which concern on a 5th modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to embodiment described below, It cannot be overemphasized that various aspects are included in the range which does not deviate from the meaning of this invention.

<1. Device configuration>
The laser-induced analysis apparatus according to the embodiment is an apparatus for analyzing a sample solidified by evaporation to dryness from a liquid state by laser-induced plasma spectroscopy, and its configuration example is schematically shown in FIG.

  The laser-induced analysis apparatus 10 uses, for example, a cleaning liquid used for cleaning in a cleaning apparatus 20 that cleans a semiconductor substrate or the like using various cleaning liquids such as deionized water or chemicals. That is, for example, a predetermined amount of cleaning liquid is periodically collected from the cleaning device 20, and the collected cleaning liquid is dropped on the sample plate 1 as a liquid sample 91 (see FIG. 3). Then, the sample plate 1 is carried into the laser induced analyzer 10. The series of processes may be automatically performed by a mechanical mechanism or may be manually performed by an analyst.

  The laser-induced analysis apparatus 10 includes a heat treatment unit 2 that heats the liquid sample 91 held on the sample plate 1 and evaporates and dries it. Specifically, the heat processing part 2 is comprised by a heater, a hot plate, etc., for example.

  Further, the laser induced analyzer 10 includes a stage 3 on which a sample plate 1 holding a sample (dried sample) 92 (see FIG. 3) solidified by evaporation to dryness is placed, and the stage 3 is rotated vertically. And a drive mechanism 4 that rotates around the shaft 31. The sample plate 1 is placed at a predetermined position on the upper surface of the stage 3, and the predetermined position is the center of the sample plate 1 (more precisely, the center of the bottom surface 110 of the recess 11 described later). The position coincides with the rotation axis 31. The stage 3 is formed with a position restricting portion for positioning the sample plate 1 at the predetermined position (for example, an L-shaped protrusion 32 (see FIG. 4) that contacts the corner portion of the sample plate 1). It is also preferable.

  Furthermore, the laser induced analyzer 10 is a stage for a light source (laser device) 5 that emits laser light, an irradiation optical system 6 that guides the laser light emitted from the light source 5, and a laser light derived from the irradiation optical system 6. 3 and a lens 7 for condensing light at a predetermined position on the sample plate 1 placed at a predetermined position on the sample plate 1. As the light source 5, for example, a YAG laser can be used. Further, since the laser-induced analysis apparatus 10 is more stable as the height thereof is lower, the light source 5 is provided on the sample plate 1 on which the laser light emitted from the light source 5 is placed on the stage 3 as shown in the figure. It is preferable to be arranged in a position and posture so as to enter obliquely with respect to the surface.

  Further, the laser induced analyzer 10 includes an analyzer 8 that acquires an emission spectrum of light generated by laser light irradiation. The analyzer 8 includes, for example, a diffraction grating (spectral means) 81 that decomposes (splits) the light introduced through the fiber 80 and the like for each wavelength, and an imaging device that receives the split light and acquires an emission spectrum. 82.

  Further, the laser induced analyzer 10 includes a control unit (control circuit) 9 that controls each element included in the laser induced analyzer 10 and executes a series of operations. The control unit 9 implements a calculation unit 90 that performs calculation processing on the emission spectrum acquired by the analyzer 8. The calculation unit 90 integrates a plurality of emission spectra (to be described later) acquired by the analyzer 8 to acquire integration data, and an average that averages the plurality of emission spectra to acquire average data. A data acquisition unit 902. The control unit 9 is connected to the computer 30, and various data acquired by the laser induced analyzer 10 (emission spectrum acquired by the analyzer 8, integrated data acquired by the calculation unit 90, average data Data, etc.) is transmitted to the computer 30. The computer 30 displays the acquired various data on a display unit connected thereto. Further, the computer 30 transmits various information such as various input operations performed via the input unit connected thereto to the control unit 9, and the control unit 9 performs laser processing based on the information received from the computer 30. Each element of the induction analyzer 10 is controlled. The arithmetic unit 90 may be realized in the computer 30.

<2. Sample plate 1>
Next, the sample plate 1 used in the laser induced analyzer 10 will be described with reference to FIG. FIG. 2 shows a plan view of the sample plate 1 and a cross-sectional view of the sample plate 1 viewed from the KK direction.

  The sample plate 1 has a rectangular shape (for example, a rectangular shape having a side of about 2.5 cm) in plan view, and is formed of silicon. However, the sample plate 1 may have a shape other than a rectangle (for example, a circular shape or a polygonal shape) in plan view, or may be formed of a material other than silicon (however, a material that does not include a substance to be measured). May be.

  A circular recess 11 is formed on the upper surface of the sample plate 1 in plan view. The recess 11 is a shape portion for holding the liquid sample 91. The inner surface of the recess 11 is also preferably roughened by blasting or the like in order to increase its hydrophilicity.

  As the amount of the liquid sample 91 held on the sample plate 1 increases, the time required for the evaporation to dryness becomes longer. Therefore, the recess 11 of the sample plate 1 has a volume (specifically, about 30 μl to 100 μl) that can hold the minimum liquid sample 91 necessary for obtaining a reliable analysis result. Is preferred. Further, when the concave portion 11 becomes deep, the incident angle of the laser beam has to be made sufficiently small in order to allow the laser beam to reach the bottom surface thereof, and in that case, the arrangement position of the light source 5 is limited almost directly above the concave portion 11. (As a result, the device becomes tall and unstable). Therefore, the depth of the recess 11 is preferably about 0.1 mm or less. For example, if the diameter of the circular recess 11 in a plan view is about 2 cm, it is possible to secure a volume of 30 μl or more at a depth of about 0.1 mm. It has been found that the recess 11 can support a liquid sample of about 100 μl.

  On the bottom surface 110 of the recess 11, a lower position portion lower than the other locations is formed at the predetermined location. Specifically, a ring-shaped groove 12 is formed along the outer peripheral edge of the circular bottom surface 110 in plan view, and the bottom 120 of the groove 12 forms a low position portion.

  Both the bottom 120 of the groove 12 and the circular portion (center portion) 13 surrounded by the groove 12 are flat. However, as described above, the groove 12 and the central portion 13 may be roughened by blasting. The depth of the central portion 13 is preferably about several tens of μm, and the depth of the groove 12 (that is, the height difference between the central portion 13 and the groove 12) viewed from the central portion 13 is also several tens of μm (preferably 10 μm). ˜20 μm). The width of the groove 12 is preferably about 2 mm.

  FIG. 3 schematically shows how the liquid sample 91 dropped into the recess 11 of the sample plate 1 evaporates to dryness. As shown here, as the evaporation of the solvent of the liquid sample 91 proceeds by heating from the initial state where the liquid sample 91 is dropped into the recess 11 (P1), the concentration of the solution gradually increases. A dry sample 92 is deposited on the portion 13, and the remaining relatively high concentration liquid sample 91 is collected in the groove 12 (P2). When the solvent of the liquid sample 91 further evaporates from here, the liquid sample 91 in the groove 12 evaporates to dryness here (P3). Therefore, the precipitation amount of the dry sample 92 per unit area is larger at the bottom 120 of the groove 12 (that is, the lower position portion) than at the central portion 13.

  In the final stage of evaporation to dryness (that is, the stage in which the liquid sample 91 having the highest concentration remaining in the groove 12 is evaporated to dryness), the liquid sample 91 having the highest concentration remaining last is A droplet 910 is formed by surface tension (P3), and the droplet 910 is finally evaporated to dryness at any location in the groove 12 (P4). That is, when the liquid sample 91 is evaporated to dryness using the sample plate 1, the droplet dry portion A (that is, the droplet that is a portion where the amount of precipitation of the dried sample protrudes more than other portions). The dried portion A) will always be somewhere within the bottom 120 of the groove 12 (ie, the low position).

<3. Laser beam irradiation position>
Next, the irradiation position of the laser beam will be described with reference to FIG. FIG. 4 is a view for explaining the irradiation position of the laser beam on the sample plate 1.

  The laser beam is irradiated with the laser beam aiming at the bottom 120 (that is, the low position portion) of the groove 12 in the sample plate 1. Specifically, the light source 5 has a predetermined posture (that is, a laser beam emitted from the light source 5 is positioned at a low position of the concave portion 11 of the sample plate 1 placed at a predetermined position of the stage 3 (that is, the bottom of the groove 12). 120), and is fixedly arranged. Then, the drive mechanism 4 irradiates laser light intermittently (preferably at regular intervals) from the light source 5 while rotating the stage 3 around the rotation shaft 31. The rotation axis 31 of the stage 3 coincides with an axis passing through the center of the sample plate 1 placed at a predetermined position on the stage 3 (that is, the center of the bottom surface 110 of the recess 11). Therefore, when viewed from above the sample plate 1, the irradiation position of the laser light moves along the groove 12. That is, each of a plurality of different positions Qi (i = 1, 2,..., N) on the bottom 120 of the groove 12 is irradiated with laser light.

  When the drive mechanism 4 rotates the stage 3 at a constant speed and irradiates the laser beam n times from the light source 5 at a constant period, a plurality of positions Qi (i = i = a) arranged at equal intervals along the bottom 120 of the groove 12. Each of 1, 2,..., N) is irradiated with laser light. At this time, the interval between the adjacent irradiation positions Qi and Q (i + 1) can be adjusted by the rotational speed of the stage 3 and the irradiation period of the laser light. For example, when the diameter of the recess 11 is about 2 cm, if the laser beam is irradiated about 40 times while the stage 3 rotates once, the interval between the irradiation positions Qi and Q (i + 1) adjacent to each other when viewed from the center of the recess 11 Is as small as 1.6mm.

As described above, in the laser induced analyzer 10, the laser beam is irradiated aiming at the low position part. As described above, a large amount of dry sample is deposited on the low position part as compared with other parts. Therefore, the intensity of the peak appearing in the obtained emission spectrum is sufficiently large. That is, the analytical sensitivity is good.
Further, in the laser induced analyzer 10, there is a plurality of different positions Qi in the low position portion in the low position portion where there is a droplet dry portion A where the precipitation amount of the dry sample is large and protrudes at some position in the low position portion. Since each of (i = 1, 2,..., N) is irradiated with laser light, the emission spectrum can be acquired by irradiating the droplet dry portion A with laser light with high probability. Therefore, particularly high analysis sensitivity can be obtained, and an analysis result with little variation regarding the sample can be obtained.

<4. Process flow>
A series of flows relating to sample analysis will be described with reference to FIG. FIG. 5 is a diagram showing the series of flows.

  First, as described above, the cleaning liquid collected from the cleaning apparatus 20 is dropped on the sample plate 1 as a liquid sample 91 by a predetermined amount, and the sample plate 1 holding the liquid sample 91 is carried into the laser induced analyzer 10. (Step S1).

  The sample plate 1 carried into the laser induced analyzer 10 is heated in the heat processing unit 2. Then, the liquid sample 91 held on the sample plate 1 is evaporated to dryness, and a dried sample 92 is obtained (step S2).

  When the dried sample 92 is obtained, the sample plate 1 holding the dried sample 92 is placed at a predetermined position on the stage 3. Then, the drive mechanism 4 irradiates laser light intermittently from the light source 5 while rotating the stage 3 around the rotation shaft 31. Thereby, the laser is applied to each of a plurality of different positions Qi (i = 1, 2,..., N) in the low position portion of the recess 11 of the sample plate 1 on the stage 3 (that is, the bottom 120 of the groove 12). Light is irradiated (step S3).

  By irradiating (condensing) the laser light, high-temperature and high-density plasma is generated, and the substance (atom) on the surface of the dried sample 92 is excited at the spot where the laser light is condensed. Each excited substance undergoes a state transition while emitting light of a specific wavelength. The light generated at this time is introduced into the analyzer 8 through the fiber 80 or the like. In the analyzer 8, the introduced light is dispersed by the diffraction grating 81 and detected by the image sensor 82, whereby an emission spectrum is acquired (step S4). Here, since the laser light is sequentially irradiated to each of the plurality of positions Qi (i = 1, 2,..., N), the analyzer 8 acquires the emission spectrum obtained by each irradiation one after another. Will do.

  The plurality of emission spectra acquired by the analyzer 8 is sent to the control unit 9, and the integration data acquisition unit 901 integrates the plurality of emission spectra to acquire integration data (step S5). Alternatively, the average data acquisition unit 902 acquires the average data by averaging the plurality of emission spectra. However, both integrated data and average data may be acquired.

  The integrated data (or average data or both of them) acquired in step S5 is sent to the computer 30 together with a plurality of emission spectra. The user can specify the type and amount of the substance contained in the sample by specifying the position (wavelength) and intensity of the peak appearing in the integrated data using the computer 30. In other words, since each substance has a unique wavelength, the type of substance can be specified by specifying the wavelength, and the intensity of the peak is proportional to the amount of substance. The content can be specified.

As described above, when the liquid sample 91 is evaporated and dried using the sample plate 1, a larger amount of the dried sample 92 is deposited on the bottom 120 of the groove 12, which is the lower position portion, than the other portions. The laser-induced analysis apparatus 10 irradiates the laser beam aiming at the low position portion. Therefore, the intensity of the peak appearing in the obtained emission spectrum is sufficiently large. That is, the analytical sensitivity is good.
Further, when the liquid sample 91 is evaporated and dried using the sample plate 1, the droplet dried portion A always exists at some position in the low position portion. Therefore, the liquid droplets are obtained with high probability by irradiating the laser beam with each of a plurality of different positions Qi (i = 1, 2,..., N) in the low position portion to acquire the emission spectrum. The emission spectrum of the dried portion A can be obtained, whereby a particularly high analysis sensitivity can be obtained and an analysis result with little variation regarding the sample can be obtained.

  Further, by acquiring integrated data obtained by integrating the emission spectra obtained for each of the plurality of positions Qi (i = 1, 2,..., N) (or average data obtained by averaging the emission spectra), It is possible to reduce the influence of noise and increase the S / N ratio, thereby improving the analysis accuracy. Further, by obtaining such integrated data or average data, it is possible to suppress variation in the detected concentration of the substance.

<5. Sample plate modification>
The shape of the bottom surface 110 of the concave portion 11 formed in the sample plate 1 is not limited to that illustrated above. FIGS. 6 to 10 show plan views of sample plates 1a, 1b, 1c, 1d, and 1e according to different shapes and cross-sectional views of the sample plates viewed from the KK direction.

  In the sample plate (sample plate according to the first modification) 1a shown in FIG. 6, the bottom surface 110a of the recess 11a has a circular shape in plan view, and a cone that inclines downward from the center toward the outer peripheral edge. It has a shape, and the vicinity of the outer peripheral edge constitutes the low position portion.

  In the sample plate 1b shown in FIG. 7 (sample plate according to the second modification), the bottom surface 110b of the recess 11b has a circular shape in plan view and tilts downward from the outer periphery to the center. The center portion (the portion including the center and the vicinity thereof) constitutes the low position portion.

  In the sample plate 1c shown in FIG. 8 (sample plate according to the third modification), the bottom surface 110c of the recess 11c has a circular shape in plan view, and a recess 14 having a circular shape in plan view is formed at the center thereof. The bottom 140 of the recess 14 constitutes the low position portion.

  In the sample plate 1d shown in FIG. 9 (sample plate according to the fourth modification), the bottom surface 110d of the recess 11d has a circular shape in a plan view, and has a groove (arc-shaped) in a plan view along the outer peripheral edge. A plurality of grooves 15 are formed at intervals. Here, the bottom 150 of each arcuate groove 15 forms a low position portion.

  In the sample plate (sample plate according to the fifth modification) 1e shown in FIG. 10, the bottom surface 110e of the recess 11e has a circular shape in a plan view, and the recess 16 has a circular shape in a plan view along its outer periphery. Are formed at intervals. Here, the bottom 160 of each recess 16 constitutes a low position portion.

  In any of the above sample plates 1a, 1b, 1c, 1d, and 1e, the solvent of the liquid sample dropped in the recesses 11a, 11b, 11c, 11d, and 11e is evaporated as in the sample plate 1 described above. Then, the concentration of the solution gradually increases, and the remaining relatively high concentration solution gathers at the low position and evaporates to dryness there. Therefore, the amount of precipitation of the dried sample per unit area is larger in the low position portion than in other portions. Further, the droplet dry portion A always exists somewhere in the low position portion. In addition, when the low position portion is formed of a plurality of regions separated from each other like the sample plates 1d and 1e according to the fourth and fifth modified examples, there is a droplet drying portion A in each region. Become.

  When each of the sample plates 1a, 1b, 1c, 1d, and 1e described above is used in the laser induced analyzer 10, the laser light is emitted from the low position portion ( That is, the laser beam is irradiated aiming at a low position portion where the amount of deposited solid sample is larger than other portions. Specifically, the light source 5 is configured such that the laser beam emitted from the light source 5 has the concave portions 11a, 11b, 11c, 11d, and 11e of the sample plates 1a, 1b, 1c, 1d, and 1e placed at predetermined positions of the stage 3. It is fixedly arranged in such a posture as to irradiate the low position portion of the. The drive mechanism 4 rotates the stage 3 around the rotation axis 31 (that is, the axis passing through the centers of the bottom surfaces 110a, 110b, 110c, 110d, and 110e of the recesses 11a, 11b, 11c, 11d, and 11e) Laser light is irradiated from the light source 5 intermittently (preferably at regular intervals). As a result, as shown in each figure, each of a plurality of different positions Qi (i = 1, 2,..., N) in the low position portion of each sample plate 1a, 1b, 1c, 1d, 1e. Laser light is irradiated. In addition, when the low position portion is formed from a plurality of regions separated from each other as in the sample plates 1d and 1e according to the fourth and fifth modifications, a plurality of laser light irradiation positions assigned to each region are provided. There may be one (FIG. 9) and one (FIG. 10).

  As described above, the analysis sensitivity is improved by obtaining the emission spectrum by irradiating the laser beam aiming at the low position portion. In addition, by aiming at each of a plurality of different positions Qi (i = 1, 2,..., N) in the low position portion and irradiating laser light to obtain an emission spectrum, droplet drying is performed with high probability. The emission spectrum of the solid part A can be acquired, and particularly high analysis sensitivity can be obtained, and analysis results with little variation regarding the sample can be obtained.

  Of the above-described modifications, for example, in the sample plate 1b according to the second modification, the amount of the dried sample deposited per unit area increases as the distance from the center of the bottom surface 110b of the recess 11b approaches. In addition, there is a high possibility that the droplet dry portion A exists at or near the center. Therefore, when this sample plate 1b is used, a configuration may be adopted in which laser light is irradiated only from the light source 5 to the center of the sample plate 1b on the stage 3.

<6. Other variations>
In the laser induced analyzer 10 according to the above embodiment, the drive mechanism 4 for moving the stage 3 is provided. Instead of (or in addition to) the drive mechanism 4 for moving the light source 5 is provided. Also good. That is, any configuration can be used as long as the sample plate 1 on the stage 3 and the light source 5 are moved relative to each other so that the irradiation position of the laser beam can be moved within the low position portion of the sample plate 1. There may be.

  In the laser induced analyzer 10 according to the above embodiment, a chamber that can accommodate the stage 3 and form a sealed space therein may be provided. In addition, an exhaust unit that exhausts the inside of the chamber may be further provided, and the emission spectrum may be acquired by irradiating the dry sample 92 with laser light after reducing the pressure in the chamber. In addition, a gas supply unit that supplies a predetermined gas (for example, helium gas or nitrogen gas) is provided in the chamber, the interior of the chamber is replaced with a predetermined gas atmosphere, and then an emission spectrum is obtained by laser irradiation. It is good also as composition to do. According to these configurations, it is possible to reduce noise (background noise) in the emission spectrum.

  In the above-described embodiment, the integrated data and / or average data are obtained from the plurality of emission spectra in step S5. However, it is not always necessary to obtain these data. For example, a substance in which the largest peak is detected at a predetermined wavelength among the plurality of emission spectra may be selected, and the content of the substance or the like may be specified from the single emission spectrum.

  In each of the above embodiments, the recess 11 formed in the sample plate 1 may have a shape other than a rectangle (for example, a circular shape or a polygonal shape) in plan view. The same applies to the sample plates 1a, 1b, 1c, 1d, and 1e.

1, 1a, 1b, 1c, 1d, 1e ... Sample plate 11, 11a, 11b, 11c, 11d, 11e ... Recess 110, 110a, 110b, 110c, 110d, 110e ... Bottom 12 ... Groove 13 ... Central part 14 ... Indentation DESCRIPTION OF SYMBOLS 15 ... Arc-shaped groove 16 ... Depression 2 ... Heat processing part 3 ... Stage 4 ... Drive mechanism 5 ... Light source 6 ... Irradiation optical system 7 ... Lens 8 ... Analyzer 81 ... Diffraction grating 82 ... Imaging element 9 ... Control part 90 ... Calculation part 901: Integrated data acquisition unit 902 ... Average data acquisition unit 91 ... Liquid sample 910 ... Droplet 92 ... Drying sample A ... Droplet drying portion 10 ... Laser induced analyzer 20 ... Cleaning device 30 ... Computer

Claims (12)

A sample plate having a recess formed in a predetermined position on the bottom surface with a lower position part lower than other parts, and
A heat treatment section for heating and evaporating and drying the liquid sample dropped in the recess;
A light source that irradiates a laser beam to the low position portion of the concave portion in which the dried sample obtained by evaporation to dryness is held;
An analyzer for obtaining an emission spectrum of light generated by the laser light irradiation;
A laser induced analyzer. The laser induced analyzer according to claim 1,
The light source irradiates each of a plurality of different positions in the low position portion with laser light,
The analyzer obtains an emission spectrum obtained with each irradiation;
Laser induced analyzer. The laser induced analyzer according to claim 2,
An integrated data acquisition unit for acquiring integrated data obtained by integrating a plurality of emission spectra obtained by laser light irradiation to the plurality of positions;
A laser induced analyzer. The laser induced analyzer according to claim 2 or 3,
An average data acquisition unit for acquiring average data obtained by averaging a plurality of emission spectra obtained by laser light irradiation to the plurality of positions;
A laser induced analyzer. The laser induced analyzer according to any one of claims 1 to 4,
The bottom surface of the recess is circular in plan view;
A groove is formed along the outer peripheral edge of the bottom surface,
Laser induced analyzer. The laser induced analyzer according to any one of claims 1 to 4,
The bottom surface of the recess is circular in plan view;
The bottom surface has a shape inclined downward from the center toward the outer peripheral edge,
Laser induced analyzer. The laser induced analyzer according to any one of claims 1 to 4,
The bottom surface of the recess is circular in plan view;
The bottom surface has a shape that is inclined downward from the outer peripheral edge toward the center.
Laser induced analyzer. The laser induced analyzer according to any one of claims 1 to 4,
The bottom surface of the recess is circular in plan view;
In the center of the bottom surface, a circular recess in plan view is formed,
Laser induced analyzer. The laser induced analyzer according to any one of claims 1 to 4,
The bottom surface of the recess is circular in plan view;
Along the outer peripheral edge of the bottom surface, a plurality of arc-shaped grooves in plan view are formed at intervals.
Laser induced analyzer. The laser induced analyzer according to any one of claims 1 to 4,
The bottom surface of the recess is circular in plan view;
A plurality of depressions having a circular shape in plan view are formed at intervals along the outer peripheral edge of the bottom surface.
Laser induced analyzer. A sample plate used in a laser induced analyzer,
Having a recess into which a liquid sample is dropped, and having a low position lower than other locations at a predetermined location on the bottom surface of the recess,
Sample plate. Dropping a liquid sample into the concave portion of the sample plate having a concave portion in which a lower position portion formed at a lower position than the other portions is formed at a predetermined position on the bottom surface;
Heating and evaporating and drying the liquid sample dropped in the recess;
Irradiating a laser beam to the low position portion of the concave portion in which the dried sample obtained by evaporation to dryness is held;
Obtaining an emission spectrum of light generated by the laser light irradiation;
A laser induced analysis method.

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