JPH053538B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an infrared absorption spectrum measuring device that measures an infrared absorption spectrum by a reflection method.

[Background of the invention]

A cross-sectional view of an example of a conventional infrared absorption spectrum measuring device using a reflection method is shown in FIGS. 1a and 1b. In FIG. 1a, infrared light 2 from an infrared light source 1 is reflected by a concave mirror 3 and irradiated onto an analysis sample S on a sample fixing table 4, and the reflected light from the sample S is reflected by a plane mirror 5. The light is then reflected by a concave mirror 6, condensed, enters a detector 7, and is detected. The sample fixing table 4 and the plane mirror 5 can be rotated in the direction of the arrow about the intersection point 0 of the sample fixing table 4 and the plane mirror 5 while being opened at a fixed angle of, for example, 100 degrees. Even if the incident angle of the infrared light 2 applied to the sample S is changed, the reflected light reflected by the sample S and reflected by the plane mirror 5 and the concave mirror 6 always passes through a fixed optical path and is focused on the detector 7. In the case of a general analysis sample, the measurement is normally performed at an angle of incidence of the infrared light 2 irradiated onto the sample S at around 50 degrees.

However, in the case of analysis samples of thin films such as semiconductors, the thickness of the sample is thin, so in order to measure with high sensitivity and accuracy, the incident angle of the infrared light 2 irradiated onto the sample S must be adjusted as shown in Figure 1b. Furthermore, it is necessary to increase the angle to, for example, about 70 degrees or more. However, in this case, as shown by the broken line, if the sample fixing table 4 and the plane mirror 5 are rotated in the direction of the arrow around the intersection 0 to make the incident angle 70 degrees or more, the sample S will come off the sample fixing table 4. must be set in the correct position, which makes measurement impossible. Furthermore, even if the incident angle is, for example, 70 degrees or less and the sample S does not come off the sample fixing table 4, the fixing position of the sample S must be moved to the irradiation position of the infrared light 2, and the infrared light The light collection performance at the irradiation position 2 deteriorates, and the light collection position and light collection performance at the detector 7 also deteriorate.

In this way, the conventional infrared absorption spectrum measurement device using the reflection method requires complicated adjustments within the measurement sample chamber R, and it is difficult to widen the variable range of the incident angle of the infrared light, including a large angle. difficult,
In addition, the intensity of the infrared light irradiating the sample surface and the reflected light entering the detector 7 decreases due to attenuation on the optical path, light convergence, etc., so various analytical tests cannot be performed with high sensitivity and accuracy. It was hot.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and provide an infrared absorption spectrum measuring device using reflected light that can easily measure an analytical sample with high sensitivity and accuracy over a wide variable range of incident angles, including a wide range of incident angles. There is something to do.

[Summary of the invention]

In the measurement of infrared absorption spectra by the reflection method, the present invention requires a large incident angle of infrared light irradiated onto the sample in order to measure the analytical sample with high sensitivity and accuracy, especially including samples such as thin films. There is,
Although it is convenient to widen the variable range,
This is difficult to do with the conventional method of moving the sample, so in order to improve this problem, an optical fiber is used to freely change the incident angle of the infrared light without moving the sample. In addition to providing a mechanism to freely change the angle of incidence on the sample, a focusing system such as an off-axis ellipsoidal mirror is provided to collect the reflected light from the sample. This is an infrared absorption spectrum measurement device that detects by feeding the light into a detector.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a sectional view showing an embodiment of an infrared absorption spectrum measuring device according to the present invention. In FIG. 2, the same reference numerals or symbols as in FIGS. 1a and 1b indicate the same or corresponding parts, and 8 is an optical fiber through which infrared light 2 from an infrared light source passes and irradiates the sample S; Reference numeral 9 denotes an off-axis ellipsoidal mirror constituting a condensing system that condenses reflected light from the sample S and sends it to the detector 7.

With this configuration, the infrared light 2 from the infrared light source passes through the optical fiber 8 and directly irradiates the analysis sample S at an incident angle of, for example, 80 degrees. This analysis sample S is approximately one point of the off-axis elliptical mirror 9 that forms the condensing system for the reflected light.
At one focal position, the reflected light from the analysis sample S is focused by this off-axis elliptical mirror 9, and is focused on the detector 7 located at the other focal position. Furthermore, when the analysis sample S is irradiated with infrared light 2 at an incident angle of 30 degrees, for example, the reflected light is similarly focused by the off-axis elliptical mirror 9 of the focusing system and focused on the detector 7. be illuminated. In this way, the angle of incidence of the infrared light 2 irradiated onto the analysis sample S can be freely changed by rotating and moving the optical fiber 8, and a wide angle of incidence of, for example, 70 degrees or more, which is particularly effective for thin film analysis, can be changed. The light can be easily collected by, for example, an off-axis ellipsoidal mirror forming a condensing system, and can be detected by the detector 7.

Next, FIG. 3 is a perspective view showing an embodiment of a mechanism for varying the incident angle of the infrared light 2 by moving the optical fiber 8 shown in FIG. In Figure 3, 10
1 is a fiber moving jig that holds an optical fiber 8;
Reference numeral 1 denotes a driving motor connected to the moving jig 10 to drive the moving jig to move the optical fiber, and 12 a condenser lens attached to the tip of the optical fiber 8.

With this configuration, the optical fiber 8 connected to the infrared light source 1 is fixedly held on the moving jig 10, and by rotationally driving the moving jig 10 with the drive motor 10, the optical fiber 8 connected to the infrared light source 1 is fixedly held, and the moving jig 10 and the sample stage 10 are rotated together with the moving jig 10. As a result, the infrared light 2 passing through the optical fiber 8 is rotated around the irradiation position of the sample S, which is held horizontally above, by an angle equal to the rotation angle of the drive motor 10. The same position on the sample S is always irradiated at the same angle of incidence. At this time, the emitted infrared light is condensed by the condenser lens 12 attached to the tip of the optical fiber 8, so that it is not attenuated due to diffusion. Further, the rotational movement angle of the optical fiber 8 is, for example, in a range of 90 degrees from horizontal to vertical.

Note that the mechanism for moving the fiber 8 in the above embodiment is not limited to the mechanism shown in FIG. 3, and the condensing system for reflected light is not limited to the off-axis elliptical mirror shown in FIG. .

As described above, according to this embodiment, the angle of incidence of infrared light on the sample can be varied over a wide range including a wide angle of incidence by moving the optical fiber with a simple mechanism, and the angle of incidence of infrared light on the sample can be varied over a wide range, including a wide angle of incidence. The light can be focused by a condensing system such as an ellipsoidal mirror and guided to a detector, making it possible to easily detect various analytical samples, including thin films, with high sensitivity and precision at all times.

〔Effect of the invention〕

According to the present invention, there is no need for complicated adjustments such as a complicated optical reflection system in the sample chamber, and a wide range of incident angles, including a wide range of incidence angles, can be used depending on the analysis sample, including thin films. Infrared absorption spectra can be measured with high precision.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the structure of a conventional infrared absorption spectrum measuring device during normal operation and when measurement is not possible, and FIG. 2 is a cross-sectional view of the structure of an embodiment of the infrared absorption spectrum measuring device of the present invention. , FIG. 3 is a perspective view showing an embodiment of the optical fiber moving mechanism of FIG. 2. 1... Infrared light source, 2... Infrared light, 7... Detector, 8
...Optical fiber, 9...Ellipsoidal mirror (condensing system), 10...
Fiber moving jig, 11... drive motor, 12...
Condensing lens, 13... Sample stage, S... Sample.

Claims (1)

[Scope of Claims] 1. An infrared light source, a sample stage that holds an analysis sample, an optical fiber that transmits infrared light from the light source and irradiates the sample, and an optical fiber that allows the infrared light from the light source to pass through and irradiate the sample; an infrared absorption spectrum consisting of a mechanism that varies the incident angle of infrared light irradiated to the specimen, a condensing system that condenses the reflected light from the sample, and a detector that detects the condensed reflected light. measuring device. 2. The infrared absorption spectrum measuring device according to claim 1, wherein the condensing system comprises an ellipsoidal mirror. 3. The infrared absorption spectrum measuring device according to claim 1, wherein a condensing lens is added to the tip of the optical fiber.