JP2000304690A - Optical measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make stably and accurately formable a gap determinable by the depth of a recess between optical parts and a sample by providing the recess at a part in contact with the sample of a prism and simply placing the optical parts on the sample. SOLUTION: A prism 121 made of silicon is brought into contact with the surface of a sample 111, incidence light 131 is applied at an angle of 45 degrees in an oblique lower direction, and emission light 132 is optically analyzed, thus analyzing the sample. On the upper surface where the prism 121 touches the sample 111, a recess 122 with a depth of 5 μm is provided while leaving a periphery of 1 mm. When measurement light enters a gap of 5 μm between the bottom surface of the recess and the surface of a sample, multiple reflection occurs and the interaction between light and the sample increases, and measurement sensitivity improves. The depth of the recess can be selected within a range of several μm to several hundreds of μm. Further, any incidence and emission angle of the prism can be measured and light preferably enters at an angle of 60-80 deg. form the sample surface to improve the sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical measuring device for irradiating a sample with light and examining the characteristics of the light after interacting with the sample to examine the optical characteristics of the sample.

[0002]

2. Description of the Related Art As an example of an optical measuring device for examining optical characteristics of a sample by irradiating the sample with light and examining the characteristics of the light after interacting with the sample, a Fourier transform red light widely used is widely used. The prior art of the external absorption measuring device will be described.

In the Fourier-transform infrared absorption measuring apparatus, a plate-like optical component made of a material having a high refractive index such as germanium, which is called a prism, is brought into contact with a sample surface in order to improve the measurement sensitivity, and the prism is tilted in an oblique direction. In general, a so-called ATR method has been used, in which measurement light is incident on the contact surface, and sensitivity is improved by multiple reflection of the incident light on the contact surface. However, since the ATR method cannot be applied to the surface analysis of a substance having a high refractive index such as a semiconductor, the range of application has been greatly limited.

On the other hand, in recent years, the air gap (air)
-Gap) The ATR method has been devised. This air-gap
The ATR method is described in API Conference Proceedings 1998 (AIP conference).
ence processesings 1998) 58
It is described on page 1-585. A spacer is interposed between the Ge prism and the sample, a gap of about 5 microns is provided between the prism and the sample, and high sensitivity measurement is realized using the cavity effect due to the gap. are doing.

[0005]

However, in the above-mentioned conventional method, it takes time and effort to fix an optical component called a prism and a sample with a spacer interposed therebetween, and the sample surface may be erroneously damaged or the sample surface may be damaged by the spacer. There was an operational problem such as contaminating. Also, depending on how the measuring light is applied, the light may accidentally hit the spacer,
There was a problem that the absorption characteristics of the spacer appeared as noise in the measured spectrum.

An object of the present invention is to provide an optical measuring device having a prism portion which does not cause the above-described problems.

[0007]

The point of the present invention is to provide a recess having a depth of several microns to several hundreds microns in a portion of an optical component (prism) in contact with a sample. By providing the above-mentioned depression in the part of the prism that comes into contact with the sample, just by placing the optical component on the sample, the gap determined by the depth of the depression between the optical component and the sample can be stably and accurately determined. Can be formed. In addition, by devising the structure of the depression, the in-plane distribution of the interval can be kept uniform, and accurate and stable measurement can be performed.

Further, according to the present invention, since it is not necessary to use a spacer, the setting of the sample is simplified, and there is no contamination of the sample surface by the spacer.

In this case, high precision processing can be performed by using the photolithography technique and the selective wet etching technique utilizing the crystal orientation to form the dent. In addition, inexpensive materials such as Si and glass can be used for the material of the optical component, and the price of the optical component can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 3A, a prism 121 made of silicon is brought into contact with the surface of a sample 111,
The sample is analyzed by inputting the incident light 131 at an obliquely downward angle of 45 degrees and optically analyzing the output light 132. Here, the thickness of the prism 121 is 3 mm, the length of the upper side is 36 mm, the length of the lower side is 30 mm, and the width is 10 mm. The surface on which the measurement light is incident and the surface on which the measurement light is emitted were cut obliquely at 45 degrees.

The prism 121 of this embodiment is shown in FIG.
As shown in FIG. 7, a recess 122 having a depth of 5 μm was provided on the upper surface where the prism 121 was in contact with the sample 111, leaving a circumference of 1 mm. 5 between the bottom of this cavity and the surface of the sample
As the measurement light enters the micron gap, multiple reflections occur, increasing the interaction of the light with the sample. Thereby, the measurement sensitivity can be greatly improved.

The procedure for measuring the infrared absorption of the sample surface by this method is as follows. First, a prism is arranged as shown in FIG. 1A on a reference having gold deposited on a silicon wafer surface by 1 μm, and an infrared absorption spectrum is measured. The measurement of the infrared absorption spectrum is performed by placing a sample in which a prism is in contact with a measurement chamber of a commercially available Fourier transform infrared absorption measurement apparatus, fixing the sample, injecting measurement light at a 45-degree angle using a mirror, and emitting light. Is incident on the Mach-Tender interferometer of the apparatus using a mirror, so that measurement can be performed in the same manner as a normal measurement. Next, a prism is arranged on the sample to be measured as shown in FIG. 1A, and an infrared absorption spectrum is measured. By subtracting the infrared spectrum of the reference from the infrared spectrum of the sample, an infrared absorption spectrum due to the sample surface can be obtained.

In this embodiment, the prism is made of silicon, but if there is no large absorption in the wavelength region to be measured,
Any solid material can be used as the prism constituent material. Further, in the present embodiment, the depth of the depression is set to 5 microns, but the depth can be selected in a range of several microns to several hundred microns. Further, in this embodiment, the incident angle and the outgoing angle of the prism are set to 45 degrees, but any angle can be measured. In general, in order to improve the sensitivity, it is better to enter the sample at an angle of 60 to 80 degrees from the sample surface, and it is necessary to process the incident surface perpendicular to the incident light. , 10 to 30 degrees.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, not only the sample 211 is arranged on the upper surface of the prism 221 made of silicon, but also the sample 212 is arranged on the lower surface. Thereby, the measurement sensitivity can be almost doubled. The prism 221 was provided with an upper depression 222 and a lower depression 223 having a depth of 5 microns. Incident surface of incident light 231, outgoing light 2
The outgoing surfaces of the 32 were both set at 45 degrees.

In this embodiment, the prism is made of silicon. However, if there is no large absorption in the wavelength region to be measured,
Any solid material can be used as the prism constituent material. Further, in this embodiment, the depth of the depression is set to 5 microns, but the depth can be selected from a range of several microns to several hundreds of microns. Further, in this embodiment, the incident angle and the outgoing angle of the prism are set to 45 degrees, but any angle can be measured. In general, in order to improve the sensitivity, it is better to enter the sample at an angle of 60 to 80 degrees from the sample surface, and it is necessary to process the incident surface perpendicular to the incident light. , 10 to 30 degrees.

Next, a third embodiment of the present invention will be described with reference to FIG. As shown in FIG. 9A, a prism 321 made of silicon is brought into contact with the surface of a sample 311, and incident light 331 is incident obliquely at an angle of 45 degrees, and emitted light 3 is emitted.
The sample is analyzed by optically analyzing 32. Here, the thickness of the prism 321 is 3 mm, the length of the upper side is 36 mm, the length of the lower side is 30 mm, and the width is 10 mm. The surface on which the measuring light is incident and the surface on which the measuring light is emitted were cut obliquely at 45 degrees. As shown in FIG. 6B, the top surface where the prism 321 contacts the sample 311
A 5 micron deep recess 322 was provided, leaving a bridge of mm and the central portion.

In this embodiment, two bridging portions having a width of 1 mm are provided, and as a result, the hollow region is divided into three portions. By providing this bridging structure, the warpage of the sample can be prevented, and the distance between the sample surface and the bottom surface of the sample recess can be stably kept constant. When the measurement light enters the gap of 5 microns between the bottom of the depression and the surface of the sample, multiple reflections occur, and the interaction between the light and the sample increases, thereby greatly improving the measurement sensitivity.

In this embodiment, the prism is made of silicon. However, if there is no large absorption in the wavelength region to be measured,
Any solid material can be used as the prism constituent material. Further, in this embodiment, the depth of the depression is set to 5 microns, but the depth can be selected from a range of several microns to several hundreds of microns. Further, in this embodiment, the incident angle and the outgoing angle of the prism are set to 45 degrees, but any angle can be measured. In general, in order to improve the sensitivity, it is better to enter the sample at an angle of 60 to 80 degrees from the sample surface, and it is necessary to process the incident surface perpendicular to the incident light. , 10 to 30 degrees.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, not only the sample 411 is arranged on the upper surface of the prism 421 made of silicon, but also the sample 412 is arranged on the lower surface. Thereby, the measurement sensitivity can be doubled. Prism 42
1 has three upper dents 422 and three lower dents 423 having a depth of 5 microns. Both the incident surface of the incident light 431 and the outgoing surface of the outgoing light 432 were set to 45 degrees.

In this embodiment, the prism is made of silicon. However, if there is no large absorption in the wavelength region to be measured,
Any solid material can be used as the prism constituent material. Further, in this embodiment, the depth of the depression is set to 5 microns, but the depth can be selected from a range of several microns to several hundreds of microns. Further, in this embodiment, the incident angle and the outgoing angle of the prism are set to 45 degrees, but any angle can be measured. In general, in order to improve the sensitivity, it is better to enter the sample at an angle of 60 to 80 degrees from the sample surface, and it is necessary to process the incident surface perpendicular to the incident light. , 10 to 30 degrees.

Next, a fifth embodiment of the present invention will be described with reference to FIG. A prism 521 having a flat surface made of silicon and in contact with the sample and having a curved surface on the opposite side is brought into contact with the surface of the sample 511, and the incident light 531 is obliquely lowered.
The sample is analyzed by optically analyzing the outgoing light 532 that enters at an angle of 5 degrees. A recess 522 having a depth of 5 μm was provided on the upper surface where the prism was in contact with the sample, leaving a circumference of 1 mm. When the measurement light enters the gap of 5 microns between the bottom of the depression and the surface of the sample, multiple reflections occur, and the interaction between the light and the sample increases, thereby greatly improving the measurement sensitivity.

In this embodiment, the prism is made of silicon, but if there is no large absorption in the wavelength region to be measured,
Any solid material can be used as the prism constituent material. Further, in this embodiment, the depth of the depression is set to 5 microns, but the depth can be selected within a range of several microns to several hundred microns. Furthermore, in this embodiment, the incident angle and the outgoing angle of the prism are set to 45 degrees, but any angle can be measured. Generally, in order to improve sensitivity, it is desirable that the light is incident at an angle of 60 to 80 degrees from the sample surface.

Next, a sixth embodiment of the present invention will be described with reference to FIG. The sample is analyzed by bringing the prism 621 made of silicon into contact with the surface of the sample 611, entering the incident light 631 at an obliquely downward angle of 45 degrees, and optically analyzing the emitted light 632. Here prism 12
The thickness of 1 is 3 mm, the length of the upper side is 36 mm, the length of the lower side is 30 mm, and the width is 10 mm. The surface on which the measuring light is incident and the surface on which the measuring light is emitted were cut obliquely at 45 degrees. In addition, a recess 622 having a depth of 5 μm was provided on the upper surface where the prism 621 was in contact with the sample 611, leaving a circumference of 1 mm.

When the measuring light enters the gap of 5 μm between the bottom surface of the depression and the sample surface, multiple reflections occur,
By increasing the interaction between light and the sample, the measurement sensitivity can be greatly improved.

Normally, in the measuring room of the optical measuring device, the light source 6
The structure is such that the light from 41 goes straight and enters the analyzer 642. The light from the light source 641 is reflected by the mirror 651 and is incident on the sample at an angle of 45 degrees.
Next, the emitted light is guided to the analyzer 642 using the mirror 652, so that optical measurement becomes possible.

In this embodiment, the incident and exit angles of 45 degrees are used. However, by changing the arrangement of the mirror and the sample, measurement at any incident and exit angles is possible.

[0027]

According to the present invention, the gap determined by the depth of the recess between the optical component and the sample can be stably and accurately obtained by placing the optical component on the sample or simply placing the sample on the optical component. Can be kept. In addition, by devising the structure of the depression, the in-plane distribution of the interval can be kept uniform, and accurate and stable measurement can be performed. Furthermore, since there is no need to use a spacer, sample setting is simplified, and there are no problems such as sample contamination by the spacer and mixing of erroneous signals.
Measurement speed and stability can be improved.

The formation of the dents can be performed with high precision by using a selective wet etching technique utilizing the photolithography technique and the crystal orientation, thereby facilitating mass production. Further, inexpensive materials such as Si and glass can be used for the material of the optical component, and the cost of the optical component can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view and a perspective view of a main part of an optical measuring device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of an optical measuring device according to a second embodiment of the present invention.

FIG. 3 is a sectional view and a perspective view of a main part of an optical measuring device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a main part of an optical measuring apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a main part of an optical measuring device according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a main part of an optical measuring device according to a sixth embodiment of the present invention.

[Explanation of symbols]

111: sample, 121: prism, 122: prism depression, 131: incident light, 132: outgoing light.

Claims (8)

[Claims] An optical measuring device for examining optical characteristics of a sample by bringing an optical component into contact with a portion of the sample to be irradiated with light, irradiating the sample with light, and examining characteristics of light after interacting with the sample. In the above optical component,
An optical measurement device having a depression structure in a part of a contact surface with a sample surface. 2. An optical measuring device for examining optical characteristics of a sample by bringing an optical component into contact with a portion of the sample to be irradiated with light, irradiating the sample with light, and examining characteristics of light after interacting with the sample. An optical measurement device according to claim 1, wherein the interaction between light and the sample is amplified by utilizing multiple reflection by a cavity formed between the sample and an optical component having a concave structure arranged like a sample. 3. The optical component according to claim 1, wherein the optical component has a structure capable of contacting a plurality of samples, and has a concave structure on a part of each contact surface with the sample. Optical measuring device. 4. The optical measuring apparatus according to claim 1, wherein the optical component has a concave structure except for a peripheral portion forming a contact surface with the sample. 5. The optical measuring device according to claim 1, wherein the optical component has a plurality of recessed structures on a contact surface with the sample. 6. An optical measuring apparatus according to claim 1, wherein the optical component has a curved surface on a surface opposite to a contact surface with the sample. 7. An optical measuring apparatus according to claim 1, wherein the bottom surface of the concave portion of the optical component is parallel to the sample surface. 8. An optical measuring device according to claim 1, wherein the optical absorption characteristic of the sample is measured.