阅读说明：本技术 高通量极紫外多层膜光栅光谱仪 (High-flux extreme ultraviolet multilayer film grating spectrometer ) 是由 杨笑微 翁祖谦 于 2021-09-03 设计创作，主要内容包括：本发明涉及一种高通量极紫外多层膜光栅光谱仪,包括狭缝、多层膜光栅、探测器、信号处理系统和真空腔体；被测样品、狭缝和作为分光元件的多层膜光栅置于真空腔体内,入射光打到被测样品上产生的极紫外信号通过狭缝入射至多层膜光栅上,从多层膜光栅上衍射出来的信号通过与真空腔体密封连接的探测器探测,探测器探测信号送信号处理系统处理,获得被测样品的极紫外吸收谱数据。采用了多层膜光栅作为分光元件,可以使得光谱仪中光栅的工作角度从掠入射变为近正入射,大幅提高了对光子的利用效率。本发明结构紧凑,并且在需要同等光通量时,相比现有技术,本发明使用小尺寸光栅基底的成本更低。(The invention relates to a high-flux extreme ultraviolet multilayer film grating spectrometer, which comprises a slit, a multilayer film grating, a detector, a signal processing system and a vacuum cavity, wherein the slit is arranged on the multilayer film grating; the sample to be detected, the slit and the multilayer film grating serving as the light splitting element are arranged in the vacuum cavity, an extreme ultraviolet signal generated by incident light hitting the sample to be detected is incident on the multilayer film grating through the slit, the signal diffracted from the multilayer film grating is detected through a detector hermetically connected with the vacuum cavity, and the detection signal of the detector is sent to a signal processing system for processing to obtain extreme ultraviolet absorption spectrum data of the sample to be detected. The multilayer film grating is used as a light splitting element, so that the working angle of the grating in the spectrometer is changed from grazing incidence to near normal incidence, and the utilization efficiency of photons is greatly improved. The invention has compact structure, and compared with the prior art, the invention has lower cost of using the small-size grating substrate when the same luminous flux is needed.)

1. A high-flux extreme ultraviolet multilayer film grating spectrometer is characterized by comprising a slit, a multilayer film grating, a detector, a signal processing system and a vacuum cavity; the sample to be detected, the slit and the multilayer film grating serving as the light splitting element are arranged in the vacuum cavity, an extreme ultraviolet signal generated by incident light hitting the sample to be detected is incident on the multilayer film grating through the slit, the signal diffracted from the multilayer film grating is detected through a detector hermetically connected with the vacuum cavity, and the detection signal of the detector is sent to a signal processing system for processing to obtain extreme ultraviolet absorption spectrum data of the sample to be detected.

2. The high-throughput euv multilayer film grating spectrometer according to claim 1, wherein the multilayer film grating has a grating line density that varies with the surface of the optical element perpendicular to the grating line direction, and a multilayer film period thickness that varies in the normal direction of the optical element.

3. The high-throughput extreme ultraviolet multilayer film grating spectrometer according to claim 2, wherein the multilayer film grating is a blazed type grating.

4. The high-throughput extreme ultraviolet multilayer film grating spectrometer according to claim 2 or 3, wherein the multilayer film grating base surface is a spherical surface or a cylindrical surface; according to the radiation energy of incident light, a substrate material with small thermal deformation and thermal radiation damage or a common grating substrate material is selected.

5. The high-flux extreme ultraviolet multilayer film grating spectrometer according to claim 4, wherein the incident angle α of the multilayer film grating is an included angle between light emitted from the slit and a normal of the multilayer film grating, the range of the incident angle α is 0-20 degrees, and the incident angle α is near normal incidence.

6. The high-throughput extreme ultraviolet multilayer film grating spectrometer of claim 5, wherein the detector is a line detector or an area detector.

7. The high-throughput euv multilayer grating spectrometer of claim 6, wherein the effective photosensitive size of the detector determines the wavelength range of a single acquisition.

8. The high-flux extreme ultraviolet multilayer film grating spectrometer according to any one of claims 1, 2, 3, 5 and 6, wherein a filter membrane for removing background signals is added on the surface of the detector to enhance the signal-to-noise ratio of spectral lines.

Technical Field

The invention relates to a spectrometer technology, in particular to a high-flux extreme ultraviolet multilayer film grating spectrometer.

Background

X-ray absorption near-edge spectroscopy (XANES) is an important technical means for detecting the electronic structure of transition metal complexes, and plays a key role in the elucidation of the structures and functions of metalloproteins, coordination compounds, semiconductors and catalysts. The energy of the X-ray (photon energy >100eV) corresponds to the K and L absorption edges of the first row transition metal elements, and the extreme ultraviolet near edge absorption spectrum (photon energy 50-100eV) extends this characterization technique to the M absorption edge of the first row transition metal elements, corresponding to the transition of electrons from 3p to 3 d. The M-edge near-edge absorption spectrum can be applied to the research of inorganic chemistry, biological inorganic chemistry and metal organic chemistry.

However, the existing euv spectrometer is generally a grazing incidence grating spectrometer, which has a small stereo acceptance angle and low photon utilization efficiency. This is because the optical constants of the material in the extreme ultraviolet energy range are close to but less than 1, and the diffraction efficiency of the grating is extremely low under the condition of near normal incidence, and the grating can only work under grazing incidence geometry (the incident light is close to the surface of the optical element). The solid acceptance angle of an optical system is generally defined as A × cos α/r₁ ²Where A is the effective area of the optical element, α is the angle of incidence, r₁Is the incident arm length (sample to grating distance). When the incident angle is large, the acceptance angle is small. Typical methods of increasing the acceptance angle include increasing the size of the grating and shortening the length of the incident arm, however the mass of the grating surface decreases with increasing size and the length of the incident arm is limited by the size required for the sample environment.

Disclosure of Invention

Aiming at the problem that the existing extreme ultraviolet spectrometer is low in photon collection rate, a high-flux extreme ultraviolet multilayer film grating spectrometer is provided.

The technical scheme of the invention is as follows: a high-flux extreme ultraviolet multilayer film grating spectrometer comprises a slit, a multilayer film grating, a detector, a signal processing system and a vacuum cavity; the sample to be detected, the slit and the multilayer film grating serving as the light splitting element are arranged in the vacuum cavity, an extreme ultraviolet signal generated by incident light hitting the sample to be detected is incident on the multilayer film grating through the slit, the signal diffracted from the multilayer film grating is detected through a detector hermetically connected with the vacuum cavity, and the detection signal of the detector is sent to a signal processing system for processing to obtain extreme ultraviolet absorption spectrum data of the sample to be detected.

Preferably, the grating linear density of the multilayer film grating is changed along the direction perpendicular to the grating lines on the surface of the optical element, and the period thickness of the multilayer film is changed along the normal direction of the optical element.

Preferably, the multilayer film grating is a blazed grating.

Preferably, the surface shape of the multilayer film grating substrate is a spherical surface or a cylindrical surface; according to the radiation energy of incident light, a substrate material with small thermal deformation and thermal radiation damage or a common grating substrate material is selected.

Preferably, the incident angle α of the multilayer film grating is an included angle between light emitted from the slit and a normal of the multilayer film grating, and the range of the incident angle α is 0-20 degrees and is near normal incidence.

Preferably, the detector is a line detector or an area detector.

Preferably, the effective photosensitive size of the detector determines the wavelength range of a single acquisition.

Preferably, a filter membrane for removing background signals is added on the surface of the detector to enhance the signal-to-noise ratio of spectral lines.

The invention has the beneficial effects that: the high-flux extreme ultraviolet multilayer film grating spectrometer improves photon collection efficiency; a compact mechanical structure; under the condition of the same required luminous flux, the used multilayer film grating has short length and reduces the cost.

Drawings

FIG. 1 is a schematic structural diagram of a high-flux extreme ultraviolet multilayer film grating spectrometer of the present invention;

FIG. 2 is a schematic diagram of a multi-layer film grating structure in the high-flux extreme ultraviolet multi-layer film grating spectrometer of the present invention;

FIG. 3 is a thickness chart of the Al/Zr non-periodic multi-layer film in the multi-layer film grating of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

The high-flux extreme ultraviolet multilayer film grating spectrometer as shown in fig. 1 is structurally schematic, and comprises a slit 2, a multilayer film grating 3, a detector 4, a signal processing system 5 and a vacuum cavity 6. The sample 1 to be detected, the slit 2 and the multilayer film grating 3 serving as the light splitting element are arranged in the vacuum cavity 6, incident light is irradiated on the sample 1 to be detected to generate an extreme ultraviolet signal and is incident on the multilayer film grating through the slit 2, the signal diffracted from the multilayer film grating 3 is detected through the detector 4 hermetically connected with the vacuum cavity 6, and the detection signal of the detector 4 is sent to the signal processing system 5 to be processed, so that extreme ultraviolet absorption spectrum data of the sample 1 to be detected are obtained.

The grating linear density of the multilayer film grating 3 changes along the direction (w direction in fig. 1) perpendicular to the grating lines of the surface of the optical element, and the multilayer film period thickness of the multilayer film grating 3 changes along the normal direction of the optical element (the peak width of the spectral response curve can be widened by the change of the multilayer film period thickness, and the spectral response curve can be smoother by reasonable design). The base surface shape of the multilayer film grating 3 can be a spherical surface or a cylindrical surface; when the incident light radiation energy is high, diamond with small thermal deformation and thermal radiation damage can be selected as a substrate material, and when the incident light radiation energy is low, the substrate material can be selected from common grating processing materials such as silicon, quartz, BK7 and the like; the grating type is a blazed grating; the multilayer film structure of the multilayer film grating 3 is a non-periodically varying multilayer film structure.

Referring to fig. 2, the multilayer grating structure is schematically shown, the grating line density of the multilayer grating varies with the direction perpendicular to the grating lines along the surface of the optical element, and the line density a (x) of the variable pitch grating is defined as a (x) a₀+a₁x+a₂x²+a₃x³+., wherein a₀Is the linear density of the grating center point, x is the width of the grating surface in the direction perpendicular to the grating lines, x is 0 as the grating center, a₁、a₂、a₃Is the linear density variation coefficient of the grating.

The specific optimization case is as follows: the optimized energy point is 52.7eV, the working energy range is 50-70eV, the length of the incident arm is 320mm, the total length of the incident arm and the emergent arm is 1450mm, the working order is-1 order (outer order), and the included angle between the emergent light and the detector is70 degrees, and the parameters of the multilayer film variable-pitch grating are as follows: a is₀＝2500l/mm,a₁＝0.65l/mm²,a₂＝0.045l/mm³The base curvature radius R is 502mm, the blaze angle is 1.5 degrees, the incident arm is 320mm, and the exit arm 1130 mm. The multilayer film structure is selected from Al/Zr multilayer film, and the specific structure is SiC (2nm)/[ Al/SiC (0.5nm)/Zr/SiC (0.5nm)]₄₀The periodic thickness of the/substrate, Al/Zr multilayer film from top to bottom is shown in FIG. 3 below.

As shown in fig. 1, an incident angle α of the multilayer film grating 3 is an included angle between light emitted through the slit 2 and a normal of the multilayer film grating, and the incident angle α is in a range of 0 to 20 degrees and is near normal incidence. The included angle between the light diffracted from the multilayer film grating 3 and the normal of the multilayer film grating is beta, the incident angle of the diffracted light to the detector 4 is gamma, and the incident angle gamma can be changed within 0-90 degrees. The positions and angles of the slit 2 and the multilayer film grating 3 are not changed during detection, and when the detection energy range is larger, the position of the detector 4 needs to be changed.

The detector 4 is a line detector or an area detector; the effective photosensitive size of the detector 4 determines the wavelength range of single acquisition; a layer of filter membrane can be added on the surface of the detector 4 to remove background signals such as visible light and the like, so that the signal-to-noise ratio of spectral lines is enhanced.

When the extreme ultraviolet absorption spectrum is measured, a sample is attached to an ultrathin substrate, such as an SiN substrate, incident light is irradiated on the sample to generate an extreme ultraviolet signal, the extreme ultraviolet light is irradiated on a multilayer film grating through a slit at a near-normal incident angle (0-20 degrees), a signal diffracted from the grating enters a detector, and the signal processing system receives data. And then, the sample is changed into an independent substrate at the same position, data when the sample to be detected does not exist is obtained, and the difference value of the two groups of data is calculated, so that the extreme ultraviolet absorption spectrum data of the sample can be obtained.

The extreme ultraviolet grating spectrometer adopts the multilayer film grating as the light splitting element, the diffraction efficiency of the multilayer film grating is equal to that of the common single-layer film grating, and the working angle of the grating is changed from grazing incidence to near normal incidence, so that the utilization efficiency of photons is greatly improved.

The extreme ultraviolet grating spectrometer of the invention has compact mechanical structure: since the incident light and the diffracted light are in opposite directions, the overall length of the spectrometer is only dependent on the longer of the incident arm and the exit arm, rather than adding the two. When the sample is preceded by a light source generating device, the space required by the whole system can be further compressed.

When the extreme ultraviolet grating spectrometer needs the same luminous flux, compared with the cost required by lengthening the grating substrate under the requirement of maintaining the surface quality of the grating in the prior art, the extreme ultraviolet grating spectrometer has lower cost for using the small-size grating substrate.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.