JPH04301600A - Multi-layered membrane reflecting mirror for soft x-ray - Google Patents

Abstract

PURPOSE:To enable highly sensitive spectrochemical analysis of a material to be conducted by forming a protective layer having a normal, differing from a multi-layered membrane normal, on a surface of a multi-layer membrane which has Bragg diffraction effect. CONSTITUTION:A multi-layered membrane reflecting mirror 1 is constituted of a base plate part 2, a multi-layered membrane part 3, a protective membrane part 4, and the multi-layered membrance part 3 consists of an alternative lamination of heavy element layers 5 and light element layers 6. The protective membrane part 4 has a normal differing from the multi- layered membrane normal. Radiation beam is projected in from a radiation beam source 7 and Bragg reflection X-ray 9 is taken out by the multi-layered membrane part 3 of the multi-layered membrane reflecting mirror 1 and then is projected out by angle theta1 from a surface of the multi-layered membrane. On the other hand, since radiation beam is projected into the protective membrane surface by angle theta2, total reflection X-ray 10 is projected out from a surface of the protective membrane, by an angle theta2. There appears angle difference of theta1-theta2 between the Bragg reflection X-ray 9 and the total reflection X-ray and therefore, by setting a detector 11 at a position where the Bragg X-ray is detected, the total reflection X-ray can be excluded. Noise caused by the total reflection X-ray, disappears and measurement with high S/N ratio can be conducted and thereby spectrochemical analysis of a material can be conducted with very high sensitivity.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a soft X-ray spectroscopy element required for a device that analyzes light elements among various inorganic and organic materials such as semiconductor materials with high sensitivity, including their chemical state, chemical composition, and impurity concentration. be.

0002

2. Description of the Related Art Hitherto, a multilayer reflector is known in which each layer of the multilayer film is parallel to a substrate, and the surface of the multilayer film is also parallel to the substrate. When spectroscopic analysis is performed using this multilayer reflector and synchrotron radiation as a radiation source, the intensity of the synchrotron radiation is more than three orders of magnitude higher than that of conventional X-rays. The reflection efficiency is several to hundreds of times higher in the soft X-ray region than other spectroscopic elements such as crystals and diffraction gratings, so the sensitivity is higher than when performing spectroscopic analysis using ordinary X-rays. analysis was possible.

0003

[Problem to be solved by the invention] However, spectroscopic elements such as multilayer mirrors, crystals, and diffraction gratings are
In addition to X-rays, there are always extremely strong X-rays that are reflected on the surface of the spectroscopic element and are called total internal reflection X-rays. For this reason, when a conventional multilayer reflector, in which each layer of the multilayer film is parallel to the substrate and the surface of the multilayer film is also parallel to the substrate, is used for spectroscopy of continuous X-rays such as synchrotron radiation, the multilayer film becomes In addition to the Bragg reflected X-rays separated by the periodic structure, total reflected X-rays are emitted from the surface of the multilayer mirror at the same angle as the incident angle. Since the Bragg reflection is also reflected at the same angle as the incident angle, both of them are incident on the detector for detecting the Bragg reflection There was a problem in that the X-rays became noise and lowered the signal-to-noise ratio of the signal to be measured, making it difficult to perform analysis with as high a sensitivity as expected. For reference, FIG. 1 shows an example of an X-ray profile when synchrotron radiation is spectrally analyzed using a multilayer reflector. In this case, total internal reflection X-rays occur in a region with higher energy than the Bragg X-rays to be extracted. This totally reflected X-ray becomes noise and lowers the SN ratio.

The present invention was proposed to solve the above-mentioned problems, and its purpose is to prevent totally reflected X-rays, which are unnecessary for spectroscopic analysis and reduce analysis accuracy, from entering the X-ray detector. An object of the present invention is to provide a multilayer reflective mirror.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a multilayer film reflecting mirror characterized by having a structure in which an uppermost layer that is not parallel to the plane of the multilayer film is added to the outermost surface of the multilayer film. That is.

[0006]

[Operation] When continuous X-rays such as synchrotron radiation are incident on a multilayer film reflector, the Bragg reflected X-rays generated due to the multilayer film structure are caused by the incident radiation being emitted at the same angle as the multilayer film surface. go. On the other hand, the totally reflected X-rays are emitted at the same angle of incidence with respect to the surface of the protective layer formed on the top layer of the multilayer film. Since the protective layer formed on the top layer of the multilayer film is not parallel to the multilayer film surface, the X-rays reflected from each surface will be emitted in different directions. That is, total reflection X-rays and Bragg reflection X-rays are separated, and only this Bragg X-ray can be extracted. Being able to extract only the Bragg reflected X-rays has the effect that when performing spectroscopic analysis of materials using synchrotron radiation, noise due to total internal reflection X-rays is eliminated, making it possible to perform measurements with a high signal-to-noise ratio, making highly sensitive material spectroscopic analysis possible. It happens.

[0007]

[Example] Next, an example of the present invention will be described. Note that the embodiments are merely illustrative, and it goes without saying that various changes and improvements can be made without departing from the concept of the present invention.

FIG. 2 shows an example of the multilayer reflective mirror of the present invention. The present multilayer film reflecting mirror 1 is composed of a substrate section 2, a multilayer film section 3, and a protective film section 4. Note that, in the multilayer film portion 3, heavy element layers 5 and light element layers 6 are alternately laminated. This multilayer film reflecting mirror was manufactured using a sputtering method. First, two targets of tungsten and carbon are sputtered in an argon gas atmosphere, and a multilayer film structure is formed by alternately exposing a silicon substrate to sputtered particles of tungsten and carbon generated from the targets. The density of sputtered particles has a distribution as shown in FIG. 3, and the amount of deposited particles differs depending on the position on the target. For this reason, the multilayer film structure is formed by exposing the substrate to a part where the amount of deposited sputtered particles is constant (center part in FIG. 3), and the protective film part 4 is formed by exposing the substrate to a part where the amount of deposited carbon sputtered particles varies, e.g. ,
A multilayer film is formed by exposing the part A in FIG. in this case,
A protective film having a sloped thickness can be formed on the multilayer film portion 3. FIG. 4 shows an optical system for performing spectroscopy using the multilayer film reflecting mirror of the present invention produced in this manner and synchrotron radiation. This optical system consists of a synchrotron radiation source 7, an input synchrotron radiation 8, and an output Bragg X.
It is composed of a line reflection 9, an emitted total reflection X-ray 10, a detector 11 that captures the emitted X-ray, and a detector input signal recording section 12.

From the synchrotron radiation 6 incident on the multilayer film reflector 1, the multilayer portion of the multilayer film reflector 1 calculates the difference λ between the periodic length D of the multilayer film and the incident angle θ1 of the synchrotron radiation with respect to the multilayer film surface.
Bragg reflection X-rays with a wavelength λ determined by =2Dsinθ1 are extracted. This X-ray is emitted from the surface of the multilayer film at an angle of θ1. On the other hand, since the synchrotron radiation is incident on the protective film surface of the multilayer film at an angle of approximately θ2, the totally reflected X-rays exit from the surface of the protective film at an angle of approximately θ2. Therefore, approximately an angular difference of θ1-θ2 occurs between the Bragg reflection X-ray and the total reflection X-ray. Therefore, if the detector 9 is installed at a position where Bragg X-rays are detected, total internal reflection X-rays can be removed.

FIG. 5 shows the Bragg X-ray profile obtained at this time. It is clear that total internal reflection X-rays are removed when compared with the case where spectroscopy is performed using a multilayer film reflector that does not include the top layer that is not parallel to the plane of the multilayer film on the top surface of the multilayer film as shown in Figure 1. be.

Although an example has been described here, the shape of the protective film added to the top layer of the multilayer film reflecting mirror may be any shape as long as it has a surface other than parallel to the laminated surface of the multilayer film. For this reason, it goes without saying that protective films with various shapes other than parallel to the laminated surface, such as uneven shapes, chevron shapes, saw blade shapes, and various curved shapes, are all effective.

0012

Effects of the Invention As described above, by using the multilayer reflector of the present invention, it is possible to separate total internal reflection X-rays and Bragg This has the effect of eliminating noise due to reflected X-rays, enabling measurements with a high signal-to-noise ratio, and enabling material spectroscopic analysis with high sensitivity.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an X-ray profile when synchrotron radiation is spectrally analyzed by a multilayer reflector.

FIG. 2 is a diagram illustrating the configuration of a multilayer film reflecting mirror of the present invention.

FIG. 3 is a diagram illustrating the density distribution of sputtered particles.

FIG. 4 is a diagram illustrating an optical system for performing spectroscopy using the multilayer film reflecting mirror and synchrotron radiation of the present invention.

FIG. 5 is a diagram showing a Bragg X-ray profile obtained with the multilayer reflecting mirror of the present invention.

[Explanation of symbols]

1 Multilayer reflective mirror 2　Base part 3 Multilayer film part 4 Protective film part 5 Heavy element layer 6 Light element layer 7. Synchrotron radiation source 8 Incident synchrotron radiation 9 Outgoing Bragg X-ray reflection 10 Outgoing total internal reflection X-rays 11 Detector 12 Detector input signal recording section

Claims (1)

[Claims] 1. A soft X-ray multilayer film reflecting mirror, characterized in that a protective layer having a normal different from the normal to the multilayer film surface is formed on the surface of a multilayer film having a Bragg diffraction effect.