CN109243663B

CN109243663B - Adjustable waveguide system for X-ray nanoscale focusing

Info

Publication number: CN109243663B
Application number: CN201811077998.XA
Authority: CN
Inventors: 王维维
Original assignee: Ma'anshan Jinwag Machinery Technology Co Ltd
Current assignee: Shenzhen Konida Medical Equipment Co ltd
Priority date: 2018-09-16
Filing date: 2018-09-16
Publication date: 2020-10-02
Anticipated expiration: 2038-09-16
Also published as: CN109243663A

Abstract

The invention relates to the ionizing radiation processing technology, in particular to an X-ray focusing device applying diffraction, refraction or reflection, in particular to an adjustable waveguide system for focusing X-rays at a nanometer level, which comprises an adjustable housing matrix which is composed of a first housing matrix and a second housing matrix and can move relatively, wherein a multilayer thin film waveguide structure with the same structure is fixed in the first housing matrix and the second housing matrix, compared with the prior art, the adjustable shell substrate is integrally arranged in the temperature-adjustable cavity, the adjustable shell substrate can adjust and focus X-rays by using the two waveguide structures, the problem that the focusing effect cannot reach the expectation due to the fact that the traditional focusing device cannot overcome the difference between the error in the manufacturing process and the parameter determined in the analog calculation process after production and forming is solved, and a novel thought is provided for further improving the X-ray waveguide focusing performance.

Description

Adjustable waveguide system for X-ray nanoscale focusing

Technical Field

The invention relates to a processing device of particles or ionizing radiation, such as the field of focusing or slowing, in particular to an X-ray focusing device applying diffraction, refraction or reflection, and particularly relates to an adjustable waveguide system for nano-scale focusing of X-rays and a preparation method thereof.

Background

The performance and the interrelation of the nano-scale biological structures are the key points of research in the life science field, in which the function and clustering effect of biological molecules have been greatly advanced, but the three-dimensional imaging of the nano-scale biological structures is slowly developed, mainly due to the limitation of the three-dimensional imaging technology. The analysis methods used for imaging nanoscale structures today are mainly scanning electron microscopy, transmission electron microscopy and fluorescence. The first two analysis methods can well show a two-dimensional biological structure, but can cause irreversible damage to an original experimental sample, so that in the research of the biological structure, a fluorescence analysis method is utilized to calibrate the sample by utilizing an isotope. However, due to the specificity of the fluorescence analysis method, the application range is limited. On the basis, the academia finds that the X-ray imaging method can effectively solve the problems. The X-ray imaging method not only can not cause irreversible damage to the sample, but also has strong X-ray penetrating power, and can carry out three-dimensional imaging on different samples under corresponding conditions, so that the application of the X-ray imaging method is wide.

In an X-ray imaging system, a waveguide as an important component has the functions of coupling and filtering X-rays, and an X-ray source with better coupling is formed for detecting a sample. As early as 1974, Spiller and Segmueler successfully fabricated the first X-ray resonance coupled waveguide (E. Spiller, A. Segmueler, Applied Physics Letter, 24(1974), 60-61). But the experimental results are not ideal due to the secondary waveThe coupled light emitted from the light guide is strongly influenced by the surface reflected light and the transmitted light, so that the coupling effect is reduced. In order to obtain strong coupling light, a carbon film is prepared on a germanium substrate by a front end coupling method of T, Salditt, and the other side is fixed by another piece of germanium to protect the carbon film. Thus, the use of germanium substrates on both sides can effectively block reflected light (T, Salditt, S.P. Krueger, C. Fuhse and C. Baehtz, Physical Review Letters, 100 (2008), 184801-1-4), the spot size of the near field is 25 nm at 19.5 keV, and the transmittance is only 2.5E^-5. The reason is that there is a large loss of X-rays in the waveguide structure and thus the transmission is low. Therefore, increasing the transmittance of the waveguide and the resolution of the light spot become important for the research of the waveguide performance, and for this reason, some researchers found that the effective optimization of the waveguide structure can improve the waveguide performance.

For example, the waveguide is formed using a thin film structure. T. saliditt on a germanium substrate, a molybdenum/carbon/molybdenum three-layer film was prepared, reducing the spot size to 15 nm at 19.5 keV, increasing the transmission to 0.081 (t. saliditt, s.p. Krueger, c. Fuhse and c. Baehtz, Physical Review Letters, 100 (2008), 184801-1-4). I.r. Prudnikov has a two-period multilayer film as a spacer layer, in which an air gap is formed as a conductive layer. After the X-ray is coupled into the waveguide, the bragg effect generated by the multilayer film structure can effectively reduce the loss during X-ray transmission, and the strongest emergent light can be obtained by optimizing the size of the air gap and the multilayer film structure (i.r. Prudnikov, applied crystallography, 38(2005), 595-602). The results show that the loss of X-rays can be effectively reduced by utilizing the thin film structure, and the waveguide performance can be effectively improved.

Recently, a fixed structure of a multilayer film waveguide structure double array is proposed, a gap with a fixed distance is etched on the multilayer film waveguide structure, two fixed waveguide structures are formed in front of and behind the gap, the gap distance is the length of a first-stage or second-stage focal length of a first waveguide structure, namely, a second waveguide structure is arranged at a first-stage or second-stage focal position of the first waveguide structure, the design idea is that after the energy of an X-ray is determined, according to a calculation method (C, Fuhse, T, Salditt, Physica B, 357 (2005) 57-60) of X-ray transmission in a single channel, a relational formula of a propagation constant (propagation constant) beta and a conduction layer (guiding layer) thickness d is obtained by solving a Helmholtz equation of the X-ray at a waveguide inlet, and then the Taylor formula is used for expansion, a relation between a small thickness and a small propagation constant can be obtained, the thickness of each conducting layer is determined, the length of the first waveguide structure is preset according to requirements, the focus position of each stage is determined by using a Fraunhofer diffraction effect equation, after the calculation, a multilayer film sample is prepared by utilizing a direct current magnetron sputtering technology, then the distance of the primary or secondary focal distance is etched on the multilayer film sample by using Ion Etching (Reactive Ion Etching), the structure can effectively improve the signal-to-noise ratio of the focus and focus X rays in a near field, however, in practical manufacturing, the thickness of a conducting layer of a multilayer film sample prepared by using a direct-current magnetron sputtering technology is often different from the expected thickness, and meanwhile, an etched fixed gap is often not accurately positioned on the distance of the focus, the small error of the optical element in the nanometer scale often causes the focusing effect to be different from the expected effect, and the focusing effect of the finished product is not ideal.

Therefore, on the basis of the prior art, an adjustable waveguide system for X-ray nanoscale focusing is designed, which is not affected by errors in the manufacturing process, and can make up the difference between the waveguide structure and parameters determined in the simulation calculation after molding, so that the focusing effect can reach or even exceed the expectation.

Disclosure of Invention

The invention aims to solve the defects of the prior art, provides an adjustable waveguide system for X-ray nanoscale focusing and a preparation method thereof, and improves the focusing performance of the conventional waveguide.

In order to achieve the above purpose, an adjustable waveguide system for nanoscale focusing of X-rays is designed, the nanoscale focusing is that the maximum diameter of a focused X-ray spot profile is below 45nm, the waveguide system comprises an adjustable housing base body formed by a first housing base body and a second housing base body, the first housing base body and the second housing base body can move relatively, a multilayer film waveguide structure with the same structure is fixed in the first housing base body and the second housing base body, the multilayer films are formed by alternately arranging two materials, one of the two materials is a conducting material which enables X-rays to pass through, the other material is a transition metal material which is used as a spacer layer of the conducting material, the conducting material is a carbon film, the spacer layer is a transition metal element, and the outermost layer of the multilayer film is a spacer layer material, the material of interval layer and housing base member fixed connection, housing base member's material is silicon or germanium, the whole setting of housing base member with adjustable is in the adjustable cavity of temperature, the temperature control range of the adjustable cavity of temperature is 30 degrees centigrade-800 degrees centigrade.

The transition metal element is molybdenum or nickel.

The material of the shell substrate is the same as that of the spacing layer.

And when the first shell substrate and the second shell substrate can move relatively, the distance between the two waveguide structures is adjusted, and the distance adjustment range is smaller than the primary focal distance of the multilayer thin film waveguide structure and larger than the secondary focal distance of the multilayer thin film waveguide structure.

The invention also relates to a preparation method of the adjustable waveguide system for the nanoscale focusing of the X rays, which comprises the following steps: etching a first shell matrix and a second shell matrix which are matched in shape by utilizing a photoetching technology, preparing a multilayer thin film waveguide structure sample by utilizing a direct current magnetron sputtering technology, plating an electron beam resisting film on a multilayer film waveguide structure sample, etching a gap to be etched by an ion beam at the middle position of the multilayer film waveguide structure sample of the electron beam resisting film by using the electron beam, etching two multilayer film waveguide structures with the same structure by using the ion beam, fixing the two multilayer film waveguide structures in a first shell matrix and a second shell matrix by using high-temperature adhesion, the first shell base body and the second shell base body are matched to form a structure capable of relatively moving when being driven and are arranged in the temperature adjustable cavity, and connecting the first shell base body and the second shell base body with a driving mechanism outside the temperature-adjustable cavity.

The photoetching technology is extreme ultraviolet photoetching technology, the coating machine used by the direct current magnetron sputtering technology is a high vacuum coating machine, the background vacuum degree is below 5 multiplied by 10 < -5 > Pa, the working air pressure is 0.3 to 0.8Pa, the power of the spacer layer material target is 25 to 150W, and the power of the conducting material target is 100-.

Compared with the prior art, the invention has the advantages that:

1) the invention breaks through the conventional thought of the traditional design and provides a novel adjustable waveguide system, the traditional design thought is limited to firstly carrying out simulation calculation, corresponding manufacturing is carried out after the parameters of the waveguide are determined, the manufactured waveguide system is limited by the set parameters of a finished product and cannot be adjusted, actually, the set parameters and the expected parameters of the finished product of the waveguide structure often have difference, so that the focusing effect cannot be expected, especially in a nanometer focusing structure, the effect difference caused by small difference is large, and the invention can adjust to make up the difference brought in the manufacturing process after the finished product is finished, and especially can reach or even exceed the expected effect;

2) aiming at the characteristics of the carbon film, the temperature adjusting device is innovatively used for carrying out micro adjustment on the thickness of the carbon film, usually, the thickness of the obtained carbon film is too thin due to the performance loss of a coating machine during direct-current magnetron sputtering, through tests, when the carbon film is heated to a certain temperature, the focusing performance loss caused by the thickness error of the carbon film can be effectively compensated, through simulation calculation, the carbon film cannot be completely thickened to an expected level due to the actual thickness expansion near the temperature according to the thermal expansion coefficient of the carbon film, and the technical effect which is beyond the expected effect and even exceeds the expected effect is often presented in the actual effect;

3) the distance between the two waveguide arrays is adjusted by using the driving mechanism, and no matter where the emergent focus position of the first waveguide structure is actually, the driving mechanism can be used for carrying out adaptive adjustment so as to accurately position the second waveguide structure to the focus position;

4) the two multilayer thin film waveguide structures are formed by etching the same multilayer thin film waveguide sample, and the structures are completely the same, namely the structures are the same in thickness and length, the expansion consistency is achieved during temperature adjustment, and the coupling effect of the two waveguide structures cannot be changed.

Drawings

Fig. 1 is a schematic view of a waveguide system according to the present invention, in which the waveguide distance is adjusted to the longest distance.

Fig. 2 is a schematic view of a waveguide structure when the waveguide distance is adjusted to the shortest distance according to the present invention.

In the figure: 1. the temperature-adjustable cavity comprises a temperature-adjustable cavity body 2, a driving mechanism 3 of a first shell substrate, a first shell substrate 4, a spacing layer 5 of a multilayer thin-film waveguide structure fixed in the first shell substrate, a conducting layer 6 of the multilayer thin-film waveguide structure fixed in the first shell substrate, a driving mechanism 7 of a second shell substrate, a second shell substrate 8, a spacing layer 9 of the multilayer thin-film waveguide structure fixed in the second shell substrate, a conducting layer L of the multilayer thin-film waveguide structure fixed in the second shell substrate, and a distance between the two waveguide structures.

Detailed Description

The principles of the multilayer thin film waveguide structure and method will be readily apparent to those skilled in the art from the following description, taken in conjunction with the accompanying drawings, wherein the detailed description is directed to only the improved and comparative aspects of the prior art, it should be noted that the structures shown in the drawings are merely schematic in nature, and for example, the number of layers of the film in the drawings is not an actual number, as mentioned in the background art, the number of thin film layers is generally the base number, the middle layer is a conducting layer, and the conducting layer and the spacer layer are located at two sides, and so on, and at present, 3 to 15 layers are mentioned in the prior art, and in the embodiment, a waveguide structure of 15 layers is explained, and in fact, the basic waveguide principle is the same no matter what the waveguide structure is several layers, and the adjustable structure of the present invention can be applied.

As shown in fig. 1, the waveguide system includes an adjustable housing base body composed of a first housing base body 3 and a second housing base body 7, the first housing base body and the second housing base body can move relatively, a multilayer thin film waveguide structure with the same structure is fixed in both the first housing base body and the second housing base body, the multilayer thin films are alternately arranged, one of the two materials is a conducting

material

5 and 9 which allows X-rays to pass through, the other material is a transition metal material which is used as

spacing layers

4 and 8 of the conducting material, the conducting material is a carbon thin film, the spacing layer is a transition metal element, the outermost layer of the multilayer thin film is a spacing layer material which is fixedly connected with the housing base body, the housing base body is made of silicon or germanium, the adjustable housing base body is integrally arranged in a temperature adjustable cavity 1, the temperature adjusting range of the temperature adjustable cavity is 30-800 ℃.

The transition metal element is molybdenum or nickel.

The material of the housing base body can also be the same as that of the spacing layer so as to reduce the peeling of the housing base body and the spacing layer which can be caused by the stress change of different materials during temperature adjustment, however, the housing base body and the spacing layer are fixed by a high-temperature bonding technology, the bonding temperature is far higher than the upper temperature adjustment limit of the temperature adjustable cavity, and the peeling cannot be generated even if the materials are different, and the method is only taken as a preferable mode.

And when the first shell substrate 3 and the second shell substrate 7 can move relatively, adjusting the distance L between the two waveguide structures, wherein the range of the distance adjustment is smaller than the primary focal distance of the multilayer thin film waveguide structure and larger than the secondary focal distance of the multilayer thin film waveguide structure.

As shown in fig. 2, when the distance L between two waveguide structures is adjusted to be the shortest distance, the distance L should be at least smaller than the first-stage focal point distance of the waveguide structures, each stage focal point distance is determined by the phase and propagation constant of the waveguide and the length of the waveguide, and changing the thicknesses of different conducting film layers can affect the phase of the emitted X-ray, which are well-known principles and will not be described again.

The preparation method comprises the following steps: the first housing base body and the second housing base body which are matched in shape and shown in fig. 2 are etched by utilizing a photoetching technology, the photoetching technology is a known prior art, corresponding pattern definition is carried out on an etched object by using a photomask for exposure, a pattern below 10 nanometers can be etched by utilizing an extreme ultraviolet photoetching technology at present, and details are not repeated here.

The multilayer film waveguide structure sample is prepared by using a direct current magnetron sputtering technology, and through process optimization, the background vacuum degree of a high vacuum coating machine is at least below 5 multiplied by 10 < -5 > Pa, the working air pressure is 0.3 to 0.8Pa, the power of a spacer layer material target is 25 to 150W, and the power of a conducting material target is 100-150W.

The first process is to use the same coating parameters to expect to manufacture two same waveguide structures, but even though the parameters are the same, the finished product still has slight difference, then the conception of dividing the same waveguide structure into two parts is used to successfully obtain two same waveguide structures with negligible difference, the concrete mode is to coat a layer of electron beam resisting film on the multilayer film waveguide structure sample, etch the gap to be etched by the ion beam at the middle position of the multilayer film waveguide structure sample of the electron beam resisting film by using the electron beam, etch the two multilayer film waveguide structures with the same structure by using the ion beam, finally fix the two multilayer film waveguide structures in the first housing basal body 3 and the second housing basal body 7 by using the adhesion mode, namely, the matching structure shown in figure 2 is formed, and finally, the first housing basal body is matched with the second housing basal body, the structure which can move relatively when being driven is formed and arranged in the temperature-adjustable cavity, the first shell base body and the second shell base body are respectively connected with the driving mechanisms 2 and 6 outside the temperature-adjustable cavity, the driving mode can be screw rod driving or direct pushing, and the specific driving mode is not limited particularly. The compensation effect of the adjusting mode of the invention on the process error is compared through the following specific waveguide structures.

The designed waveguide structure takes a carbon thin film layer as a central film layer, the thickness is kept at 8.0 nm, the phase change is determined to be 0, a spacing layer deposited on two sides is a molybdenum thin film layer with the thickness of 52.4 nm, 7.6 nm carbon films, 53.8 nm molybdenum films, 6.2 nm carbon films, 56.0 nm molybdenum films, 4.0 nm carbon films and 50.0 nm molybdenum films are sequentially deposited on two sides, the length of each waveguide structure in the X-ray incidence direction is 280 microns, the first-order focus distance is 225 microns (in the prior art, a fixed interval between two waveguide structures is expected to be etched by etching), based on the design, the expected X-ray transmittance is more than 0.02, the spot size is less than 40 nm, the focus signal-to-noise ratio is at least more than 40, however, the actual transmittance is only 0.0169, the spot size is only 47 nm, the focus signal-to-noise ratio is also only 32.95, and after the fixed two waveguide structures are etched and separated, by using the adjustable system, the size of a light spot can be focused to 45nm and the signal-to-noise ratio is also improved to 35.64 only by finely adjusting the distance between the two waveguide structures at 30 ℃, the X-ray transmittance can be obviously influenced when the temperature is adjusted, the actual transmittance can be improved to 0.0192 at 400 ℃, and can reach 0.026 at 800 ℃, which reaches or even exceeds the expectation, and meanwhile, the focusing effect and the signal-to-noise ratio of the light spot are also improved.

It is to be understood that the specific embodiments described herein are for purposes of illustration only and not for purposes of limitation, and that various equivalent modifications as would be obvious to one skilled in the art are intended to be included within the scope of the present invention.

Claims

1. An adjustable waveguide system for X-ray nanoscale focusing, wherein the nanoscale focusing is that the maximum diameter of a focused X-ray spot profile is below 45 nanometers, and the adjustable waveguide system is characterized in that: the waveguide system comprises an adjustable housing base body formed by a first housing base body (3) and a second housing base body (7), wherein the first housing base body and the second housing base body can move relatively so as to adjust the distance (L) between the two waveguide structures when the first housing base body and the second housing base body move relatively, the first housing base body and the second housing base body are both fixed with multilayer film waveguide structures with the same structure, the multilayer films are formed by alternately arranging two materials, one of the two materials is a conducting material (5,9) which enables X-rays to pass through, the other material is a spacer layer (4,8) of the conducting material, the conducting material is a carbon film, the spacer layer material is a transition metal element, the outermost layer of the multilayer film is a spacer layer material, and the outermost layer material of the two multilayer film waveguide structures is respectively and fixedly connected with the first housing base body and the second housing base body, the material of first shell base member is silicon or germanium, second shell base member material is silicon or germanium, adjustable shell base member is whole to be set up in adjustable cavity of temperature (1), the temperature control range of the adjustable cavity of temperature is 30 degrees centigrade-800 degrees centigrade.

2. The tunable nanometer X-ray focusing waveguide system of claim 1, wherein: the transition metal element is molybdenum.

3. The tunable nanometer X-ray focusing waveguide system of claim 1, wherein: the transition metal element is nickel.

4. The tunable nanometer X-ray focusing waveguide system of claim 1, wherein: the materials of the first shell base body and the second shell base body are made of transition metal element materials which are the same as the materials of the spacing layers fixedly connected with each other, and silicon or germanium is replaced by the transition metal element materials which are molybdenum or nickel.

5. The tunable nanometer X-ray focusing waveguide system of any one of claims 2 to 4, wherein: when the first shell base body and the second shell base body move relatively to adjust the distance (L) between the two waveguide structures, the range of distance adjustment can be smaller than the primary focal distance of the multilayer thin film waveguide structure when the distance is adjusted and can be larger than the secondary focal distance of the multilayer thin film waveguide structure when the distance is adjusted.