JPS61284642A - Sample cooler for spectroscopic measurement - Google Patents

Abstract

PURPOSE:To decrease the influence of the multiple reflected light to be exerted to the analytical result of a spectroscope by inclining at least either of plate bodies mounted to an incident optical window and exit optical window relative to an optical axis. CONSTITUTION:The plate bodies 4, 4 inclined at a prescribed angle relative to the optical axes shown by respective arrows of solid lines are mounted to the incident optical window 2 and exit optical window 3 of a cooler A. The multiple reflected light deviates largely from the optical axis as shown by the arrow of an alternate long and short dash line in the cooler A constituted in the above-mentioned manner, by which the influence of the multiple reflected light to be exerted to the analytical result of the spectroscope is decreased. The measurement error and the variance of the measured value are thereby decreased.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a sample cooling device for spectrometry that cools a sample when analyzing different elements contained in a single crystal such as silicon by spectrometry. It's also.

Conventional technology In general, spectrometry is a measurement method in which the elements contained in the sample are analyzed by shining light onto the sample and analyzing the transmitted or reflected light using a spectrometer. It is widely used for qualitative or quantitative analysis. As such spectroscopic measurement methods, there are two known methods: one in which the sample is measured at room temperature, and the other in which the sample is cooled. The latter method of spectrometry is a method in which the sample is cooled to an extremely low temperature for measurement, and compared to the former measurement method, a more complex spectrum can be obtained, which makes it possible to obtain various analytical results. This is a measurement method that can provide excellent measurement accuracy in both qualitative and quantitative analysis.

BACKGROUND ART Conventionally, in the above-mentioned spectrometry method in which a sample is cooled and measured, a sample cooling device A for spectrometry as shown in FIG. 5 has been provided as a device for cooling the sample.

This spectroscopic measurement sample cooling device A has a side peripheral surface 1a of a container 1.
An input optical window 2 is formed in the input optical window 2, an output optical window 3 is formed on the side circumferential surface 1a of the container 1 opposite to the input optical window 2, and each of the input optical window 2 and the output optical window 3 has a light-transmitting property. A refrigerant tank 6 is connected to the inside of the top plate portion 1b of the container 1 via a pipe 5 projecting to the outside of the container 1. The refrigerant tank 6 has a bottom plate 6a.
A trap is provided on the bottom surface of the holder so that the sample 7 can be fixed.

In addition, liquid helium is fed into the refrigerant tank 6 from outside the container 1 through a pipe 5, thereby lowering the atmospheric temperature inside the container 1 and cooling the sample 7. ing.

The spectroscopic measurement sample cooling device A configured as described above cools the sample to an extremely low temperature during spectroscopic measurement of the sample. However, the transmitted light can be emitted from the exit optical window 3 to the outside of the container 1. The emitted light is then analyzed by a spectrometer (not shown).

[Problem that the invention seeks to solve]

By the way, in the conventional sample cooling device for spectrometry mentioned above, the plates attached to the input optical window and the output optical window are perpendicular to the optical axis, so that the dotted line in FIG. As shown by the arrow, the light that has passed through the sample is reflected on the surface of the plate attached to the output optical window, and the reflected light is further reflected on the surface of the plate attached to the input optical window. Light exits the container through an exit optical window.

Such light C (hereinafter referred to as multiple reflected light) is the light (hereinafter referred to as light on the optical axis) that passes through the sample and exits from the exit optical window to the outside of the container, as shown by the solid arrow in the figure. ), which caused the problem of increased measurement errors and variations in measured values.

Note that although the path of the light ray indicated by the dashed line in the figure is inclined with respect to the optical axis for convenience of explanation, it is actually coaxial with the optical axis.

[Means for solving problems]

In this invention, the above problem is solved by tilting at least one of the plate attached to the entrance optical window and the plate attached to the output optical window with respect to the optical axis.

[Effect]

The light reflected on the surface of the plate is tilted with respect to the optical axis according to the inclination angle set on the plate, and this causes the multiple reflection light to deviate greatly from the optical axis, causing multiple reflections to affect the analysis results of the spectrometer. The influence of light is reduced.

〔Example〕

FIG. 7 is a diagram showing an embodiment of the present invention.

In this figure, reference numeral A denotes a sample cooling device for spectrometry, and its components are the same as those of the conventional sample cooling device for spectrometry.

In this spectroscopic measurement sample cooling device fA, the plates 4.4 are attached to the entrance optical window 2 and the exit optical window 3 at a predetermined angle with respect to the optical axis indicated by the solid arrow in the figure. ing.

In the spectroscopic sample cooling device A configured as described above, the multiple reflected light deviates significantly from the optical axis as shown by the dashed-dotted arrow in the figure, thereby causing the spectrometer (not shown) to deviate from the optical axis.
The influence of multiple reflected light on the analysis results can be reduced, and measurement errors and variations in measured values can be reduced.

Further, in the above embodiment, the inclination angle of the plates 4, 4 with respect to the optical axis (hereinafter referred to as the plate inclination angle) is even larger,
By allowing the multiple reflected light to fall on the inner wall surface of the container 1 other than the exit optical window 3, measurement errors and variations in measured values can be further reduced. That is, the plate inclination angle (hereinafter referred to as critical angle) at which the multiple reflected light hits the edge 3a of the output optical window 3 is α, the aperture diameter of the input optical window 2 and the output optical window 3 is set, and the input optical window 2 and the exit optical window 3, the critical angle α is given by the following equation.

TAN・α=D/2 L ・・・・・・・・・ α
) Therefore, by making the plate inclination angle larger than the above-mentioned critical angle α, the multiple reflected light will not be emitted from the exit optical window 3 to the outside of the container 1, and the multiple reflected light will be the result of analysis by a spectrometer. It is possible to completely eliminate the impact on

Hereinafter, in the above example, the results of spectroscopic measurement of a sample while changing the plate inclination angle will be explained. In this spectroscopic measurement, the concentration of oxygen contained in the silicon single crystal (sample) K was measured by infrared spectroscopy.

In the sample cooling device for spectrometry using spectrometry pressure, the aperture diameter of the entrance optical window 2 and the exit optical window 3 is 13mm.
The distance between the entrance optical window 2 and the exit optical window 3 was set at 700 square meters. By substituting these values into equation 1, the critical angle α=qM of the plate inclination angle can be obtained. In this spectroscopic measurement,
A sample cooling device KA for spectrometry with a plate inclination angle of 3°, which is smaller than the critical angle, and a plate inclination angle r larger than the critical angle.
A sample cooling device for spectrometry [A and
The silicon single crystal was cooled to 20°K, and the silicon single crystal was irradiated with infrared light, and the magnitude of light absorption by oxygen was measured at a wave number of 34 cm.
Calibration determined in advance + i [Therefore, oxygen concentration (acid': A
number of atoms/cd) was determined. Table 1 shows the results of repeated measurements performed five times on each of the three types of silicon single crystals. In addition, Table 2 shows the results of spectroscopic measurements of the same three types of silicon single crystals as described above using a conventional sample cooling device for spectroscopic measurements. It is shown in Table 3 for reference. Table I
As shown in K, in the measurement results when using sample cooling device A for spectrometry with a plate inclination angle of 50, the average value of dispersion is ±0.2/X/01? /i has a smaller value than the conventional one. Moreover, the median value for each sample was close to the measurement result at room temperature.

In the measurement results when using the sample cooling device 1liiA for spectrometry with one plate inclination angle r, the average variation was ±0.0 g x 101 f/di, and the measurement results at room temperature. It became a smaller value.

Moreover, the median value for each sample was almost the same value as the measurement result at room temperature.

As explained above, in the above embodiment, the plate body 4,
By tilting the plate 4 with respect to the optical axis, measurement errors and variations in measured values can be reduced. Furthermore, if the plate inclination angle is made larger than the critical angle, the measurement results are almost the same as those at room temperature. The same measurement results can be obtained, and measurement results with less variation than the measurement results at room temperature can be obtained.

FIG. 1 is a diagram showing still another embodiment of the present invention.

In this embodiment, only one of the plates 4.4 is inclined with respect to the optical axis, and the same effect as the above embodiment can be obtained. In addition, in this example, the critical angle α is
For equation 1, TAN・2α=D/2L ・・・・・・・・・ (
2) Given by K.

FIG. 3 is a diagram showing still another embodiment of the present invention.

In this embodiment, each of the plates 4, 4 is inclined in a V-shape with respect to the optical axis, and the same effect as the above embodiment can be obtained. In addition, in this example, the critical angle α
For equation 1, TAN・3α=D/2L...
...... It is given by (3).

The above is an example in which light is applied to a sample and the transmitted light is detected in spectroscopic measurements, but as shown in FIG. By tilting at least one of them with respect to the optical axis, the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

In this invention, at least one of the light-transmitting plate attached to the input optical window and the light-transmitting plate attached to the output optical window is tilted with respect to the optical axis. Accordingly, it is possible to obtain measurement results with small measurement errors and small variations in measurement values. Then, the angle of inclination of at least one of the plate attached to the input optical window and the plate attached to the output optical window with respect to the optical axis is adjusted so that the angle of inclination between the plate attached to the input optical window and the plate attached to the output optical window is If the light is set so that the light that is sequentially reflected once by the plate attached to the plate attached to the input optical window and the plate attached to the input optical window hits the inner peripheral surface of the container other than the output optical window, the sample can be kept at room temperature K ``C1u1.
It is possible to obtain the effect that the variation is smaller than that of the method of measuring at room temperature, and that it is possible to obtain measurement results that are almost the same as the method of measuring at room temperature.

[Brief explanation of drawings]

FIG. 7, FIG. 1, FIG. 3, and FIG. 9 are views showing an embodiment of the present invention, respectively, and are sectional views similar to FIG. 6,
3 and 6 are views showing an example of a conventional sample cooling device for spectrometry, in which FIG. 3 is a side sectional view thereof, and FIG. 6 is a sectional view taken along the line ■-■ in FIG. S. It is. l...Container, 2...Incidence optical window, 3.
...Emission optical window, 4...Plate body, 7...
···sample.

Claims (2)

[Claims] (1) A container for cooling a sample is provided with an entrance optical window and an exit optical window, each of which is equipped with a light-transmitting plate, so that the sample enters the container through the entrance optical window, and In a sample cooling device for spectrometry, the light passing through the cooled sample or the light reflected on the surface of the sample is emitted from the exit optical window to the outside of the container, in which the light is attached to the entrance optical window. 1. A sample cooling device for spectrometry, characterized in that at least one of the plate body mounted on the output optical window and the plate body attached to the exit optical window is tilted with respect to the optical axis. (2) At least one of the plate attached to the input optical window and the plate attached to the output optical window is connected to the input optical window, and the plate attached to the output optical window and the input optical The first aspect of the present invention is characterized in that the angle of inclination with respect to the optical axis is defined so that the light that has been reflected once by the plate attached to the window hits the inner circumferential surface of the container other than the exit optical window. A sample cooling device for spectroscopic measurements as described in .