WO2020133533A1 - X射线吸收光栅制作方法及其x射线吸收光栅 - Google Patents

X射线吸收光栅制作方法及其x射线吸收光栅 Download PDF

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WO2020133533A1
WO2020133533A1 PCT/CN2018/125862 CN2018125862W WO2020133533A1 WO 2020133533 A1 WO2020133533 A1 WO 2020133533A1 CN 2018125862 W CN2018125862 W CN 2018125862W WO 2020133533 A1 WO2020133533 A1 WO 2020133533A1
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grating
substrate
metal nanoparticles
ray absorption
groove
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French (fr)
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李冀
雷耀虎
黄建衡
刘鑫
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Shenzhen University
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Shenzhen University
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—HANDLING OF PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/02—Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diaphragms, collimators

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  • the invention relates to an X-ray absorption grating, in particular to an X-ray absorption grating manufacturing method.
  • Absorption grating is an indispensable key device in X-ray grating differential phase contrast imaging technology. In this technology, it can be divided into source grating and analysis grating.
  • F. Pfeiffer et al. introduced the Lau effect into the X-ray phase contrast imaging technology.
  • the source grating was used to modulate the incoherent X-rays emitted by the ordinary X-ray tube into partial coherence (within a grating period) to satisfy phase contrast imaging.
  • partial coherence within a grating period
  • X-ray flux is fully utilized.
  • an analysis grating is usually placed at the self-imaging position to sample the phase information.
  • the period of the analysis grating is small, the aspect ratio is large, and the production is very difficult.
  • LIGA Lithography, Electroplating, and Molding
  • the technology of applying micro-casting technology and nano-imprint technology to the production of gratings appeared.
  • the micro-casting technology needs to go through a high-temperature process in the process of modifying the surface of the grating microstructure, and in the metal filling process, A special filling furnace is required, with a certain breakage rate.
  • nanoimprint technology can obtain small-period analysis gratings, the production area is very limited.
  • the analysis grating has a small period and a large aspect ratio, which makes it difficult to produce.
  • LIGA Lithography, Electroplating, and Molding
  • the technology of applying micro-casting technology and nano-imprint technology to the production of gratings appeared.
  • the micro-casting technology needs to go through a high-temperature process in the process of modifying the surface of the grating microstructure, and in the metal filling process, A special filling furnace is required, with a certain breakage rate.
  • nanoimprint technology can obtain small-period analysis gratings, the production area is very limited.
  • the technical problem to be solved by the present invention is to provide an X-ray absorption grating manufacturing method with simple manufacturing method, low threshold, and low cost, which is convenient for operation and implementation in ordinary laboratories in view of the defects of the prior art.
  • the technical problem to be further solved by the present invention is to provide an X-ray absorption grating which is equivalent to a grating filled with melt or electroplated metal, but low in cost, and easy to operate and realize in an ordinary laboratory.
  • An X-ray absorption grating manufacturing method includes the following steps:
  • Configure metal nanoparticle suspension select metal nanoparticles, add a volatile solvent, and add a surfactant. After dispersion, prepare a uniformly dispersed metal nanoparticle suspension; where volatile solvent: the volume of the surfactant The ratio is (200:1)-(20:1), the metal nanoparticles use X-ray strong absorption metal; the particle size of the metal nanoparticles is less than half of the groove width or half of the aperture;
  • Post-treatment cleaning the metal nanoparticles on the surface of the substrate to obtain an X-ray absorption grating.
  • the grating pattern is a mask plate to copy the grating pattern to the surface of the substrate covered with photoresist, and the grating pattern is developed and fixed Cured on the substrate surface.
  • the substrate is selected from a silicon substrate, a germanium substrate, a plastic substrate or a diamond substrate, and deep reactive ion etching is used to etch the grating pattern along the surface of the substrate Internal etching, etching the grating groove or grating hole, the grating groove or grating hole corresponds to the grating pattern;
  • the substrate is selected from a crystal-oriented (110) silicon substrate, and a film layer is used to cover the area that does not need to be etched, and the grating groove is etched by the etching rate of different crystal planes by KOH solution or TMAH Grating hole, the grating groove or grating hole corresponds to the grating pattern;
  • the substrate is selected from an N-type or P-type (100) silicon substrate, a transparent conductive layer is formed on the back of the silicon substrate, an electric field is applied on both sides of the silicon substrate, and the silicon substrate The etching is performed to etch the grating groove or the grating hole, and the grating groove or the grating hole corresponds to the grating pattern.
  • the surfactant is selected from OP10, CO520, polyvinyl alcohol, NMP, CTAB, DMSO, or DMF, and the cleaning is ultrasonic cleaning or Shake clean.
  • the surfactant is selected from OP10 (alkylphenol polyoxyethylene ether) and CO520 (alkylphenol ethoxylate).
  • X-ray strong absorption metal is selected from bismuth, tungsten, gold or lead.
  • the vacuum degree of the vacuum is higher than 0.1 atmosphere.
  • the close arrangement of the metal nanoparticles refers to a metal nanoparticle with a maximum gap of less than 10 times the average particle diameter of the metal nanoparticles.
  • the detection refers to observing the distribution of metal nanoparticles in the grating microstructure by electron microscopy; or using an optical microscope to view the substrate surface, if the substrate surface If it is not covered with metal nanoparticles, it will continue to fill. If the surface of the substrate is covered with metal nanoparticles, it will no longer be filled.
  • An X-ray absorption grating includes a substrate, the substrate is provided with a grating groove or a grating hole, the grating groove or the grating hole forms a grating groove array or a grating hole array, and the grating groove or the grating hole is filled with X-ray strong absorption Metal nanoparticles; in the X-ray absorption grating, it is preferred that the X-ray absorption grating is a one-dimensional structure or a two-dimensional structure, and an anti-lodging strip provided in the vertical direction of the grating groove or the grating hole of the one-dimensional structure band.
  • the grating period is from 0.5 ⁇ m to 50 ⁇ m, and the ratio of the width of the grating hole or the diameter of the grating hole to the width of the grating sidewall is 5:1-0.2:1.
  • the manufacturing method of the X-ray absorption grating of the invention is simple, the threshold is low, the cost is low, and it is convenient to operate and realize in an ordinary laboratory.
  • the present invention makes the metal nano particles into a suspension, which can disperse the metal nano particles to avoid the formation of clumps between particles.
  • the adhesion between the suspension surface and the grating microstructure surface is relatively increased, and under a negative pressure, the suspension is spread on the substrate surface, Including into the grating groove or grating hole of the grating microstructure, the suspension then carries the metal nanoparticles to the bottom of the grating groove or grating hole of the grating microstructure, because there is air in the grating hole or grating groove, and the metal nanoparticles overcome the surface tension It is very difficult to reach the grating hole or the grating groove.
  • the present invention solves the problem of difficulty in filling metal particles directly.
  • the invention can densely fill metal nanoparticles inside the grating microstructure, avoiding the high-temperature process of micro-casting in the prior art, improving the yield, and can realize the production of absorption grating on the grating microstructure of large area.
  • the X-ray absorption grating of the present invention densely arranges metal nanoparticles in the microstructure of the grating. Although the absorption of X-rays is slightly weaker than that of the bulk structure (formed by molten metal) of the same substance, it can still form a sufficient absorption contrast. Therefore, compared with the prior art, metal nanoparticle-filled X-ray absorption gratings have unique advantages in the low-cost production of X-ray large-area absorption gratings.
  • FIG. 1 is a side SEM photograph of an absorption grating filled with a tungsten nanoparticle with a period of 42 ⁇ m and a depth of 150 ⁇ m in Example 1-1 of the present invention
  • Figure 2 is a SEM photograph of bismuth metal filled on a silicon substrate with a period of 42 microns and a depth of 150 microns using micro-casting technology;
  • FIG. 3 is a contrast diagram of the contrast between the tungsten nanopowder of Example 1-1 of the present invention and the absorption grating filled with molten bismuth using micro-casting technology;
  • Example 4 is a side SEM photograph of an absorption grating with a period of 5.6 microns and a depth of 50 microns in Example 1-2 of the present invention
  • FIG. 5 is a side SEM photograph of an absorption grating with a period of 24 ⁇ m and a depth of 130 ⁇ m according to Examples 1-3 of the present invention.
  • FIG. 6 is a side SEM photograph of an absorption grating with a period of 24 ⁇ m and a depth of 130 ⁇ m according to Examples 1-4 of the present invention.
  • FIG. 8 is a schematic structural view of an unfilled X-ray absorption grating according to Embodiment 2 of the present invention.
  • Example 9 is a schematic diagram of the structure of the filled X-ray absorption grating of Example 2 of the present invention.
  • FIG. 10 is a schematic structural view of the X-ray absorption grating according to Embodiment 2 of the present invention.
  • Example 11 is a schematic structural diagram of another implementation manner of an X-ray absorption grating according to Example 2 of the present invention.
  • Embodiment 1 A method for manufacturing an X-ray absorption grating, including the following steps:
  • the grating pattern is to copy the grating pattern to the surface of the substrate covered with photoresist by using a reticle, and then to solidify the grating pattern on the surface of the substrate through development and fixing.
  • the copying and curing of the raster pattern can be carried out by using the existing conventional technology, which will not be repeated here.
  • the raster graphics can be designed according to actual needs, and can be a one-dimensional structure or a two-dimensional structure.
  • the one-dimensional structure can use stripes, and the two-dimensional structure can be a criss-cross strip, or a four-sided enclosing structure with criss-cross arrangement
  • the unit composition can also be a combination of a strip and a four-sided enclosed structural unit.
  • the four-sided enclosing structural unit may be a curved structure connected end to end, such as a circle, an ellipse, etc., or a polygon, such as a triangle, a quadrangle, a hexagon, etc., preferably a circle and an ellipse.
  • the first is: the substrate is selected from a silicon substrate, a germanium substrate, a plastic substrate or a diamond substrate, and deep reactive ion etching is used to etch inward along the grating pattern on the surface of the substrate to etch a grating groove or a grating hole, the grating
  • the slot or grating hole corresponds to the grating pattern.
  • Deep reactive ion etching is a technique to achieve anisotropic etching of substrates. In a plasma environment, ions bombard bare substrates under the action of an electric field.
  • SF 6 is generally used to form
  • the vertical sidewall structure of the grating groove or grating hole needs to be covered with a passivation layer on the surface of the sidewall of the grating groove or grating hole after etching for a period of time (usually a few seconds) to prevent the sidewall from being excessively corroded. Then continue to etch and reciprocate. After several cycles, a microstructure of grating groove or grating hole with a certain aspect ratio is formed.
  • the aspect ratio refers to the ratio of depth to width (diameter).
  • DRIE deep reactive ion etching
  • the second is: when the substrate is selected from the crystal (110) silicon substrate, the area that does not need to be etched is covered with a film layer, and the grating groove or the grating hole is etched by the etching rate of different crystal planes by KOH solution or TMAH.
  • the grating groove or grating hole corresponds to the grating pattern.
  • the anisotropic etching of the silicon substrate is an important technology of silicon micromachining, which is mainly realized by the difference of the etching rate of each crystal plane of silicon by the etching solution. Cover the desired mask on the surface of (110) silicon and place it in KOH or TMAH with a concentration of 10-50%, so that the downward etching rate is tens or even several hundred times.
  • the grating groove or grating hole microstructure with a certain aspect ratio can be obtained.
  • the specific parameter selection of the anisotropic etching of the silicon substrate can be selected according to the size and physical characteristics of the specific etched object, which will not be repeated here.
  • the third type is: when the substrate is an N-type or P-type (100) crystal silicon substrate, a transparent conductive layer is coated on the back surface, an electric field is applied on both sides of the substrate, and the substrate is subjected to photo-assisted electrochemical etching. Select the substrate with crystal orientation (100), and cover the mask with one side of the substrate, and the other side with the aluminum electrode. The side with the mask first faces the KOH solution.
  • the tip of the inverted pyramid needs to be etched, and then the The corrosive agent is replaced by an aqueous solution of HF, under the assistance of a certain light, under the guidance of the tip to the cavity, a certain voltage is applied, and the corrosion can be started downward.
  • the grating groove or grating hole can be etched, and the grating groove or grating hole corresponds to the grating pattern.
  • Photo-assisted electrochemical etching is a prior art, and its specific parameter selection can be selected according to the size and physical characteristics of the specific etching object, which will not be repeated here.
  • the strips correspond to the grating grooves formed after etching
  • the circular, elliptical or square holes correspond to the grating holes formed after etching.
  • the grating microstructure may also be a combination of grating grooves and grating holes.
  • the present invention needs to etch a grating groove and a grating hole with a certain aspect ratio, and generally requires an aspect ratio ⁇ 200, preferably an aspect ratio ⁇ 100, and most preferably an aspect ratio ⁇ 50.
  • the present invention is suitable for gratings with various aspect ratios, such as absorption gratings with an aspect ratio ⁇ 3, absorption gratings with a high aspect ratio >3, and absorption gratings with an ultra-high aspect ratio with an aspect ratio >50.
  • B. Cleaning and drying Use organic solvents, water, and surfactant to clean the grating microstructure, and then dry; the surfactant can be selected in this step, as long as it can infiltrate the substrate surface, and dissolve and adsorb , Emulsification, solubilization and other surfactants to achieve cleaning purposes are applicable to the present invention.
  • the cleaning is ultrasonic cleaning or shaking cleaning.
  • the organic solvent is preferably a volatile organic solvent, and can be selected from: low-carbon chain alkanes, olefins, alcohols, esters, ethers or ketones, for example: methanol, ethanol, acetone, ethyl acetate, tetrachloromethane, petroleum ether, chloroform, ether, etc. .
  • C. Configure metal nanoparticle suspension select metal nanoparticles, add a volatile solvent, and add a surfactant. After dispersion, prepare a uniformly dispersed metal nanoparticle suspension; where volatile solvent: the volume of the surfactant The ratio is (200:1)-(20:1), the metal nanoparticles use X-ray strong absorption metal; the particle size of the metal nanoparticles is less than half of the groove width or half of the pore diameter; the volatile organic solvent described in this step can Options: Low-carbon chain alkanes, alkenes, alcohols, esters, ethers, ketones, such as methanol, ethanol, acetone, ethyl acetate, tetrachloromethane, petroleum ether, chloroform, ether, etc. A variety of surfactants can be selected in this step, as long as they can produce a wetting effect on the surface of the substrate and reduce the surface tension.
  • the vacuum degree is higher than 0.1 atm.
  • the configured suspension was added to the vessel without passing the grating microstructure surface. In this way, under the action of negative pressure and capillary force, the suspension quickly enters the interior of the grating microstructure and expels the gas. After the suspension enters the inside of the grating microstructure, stop the vacuum, deflate the vacuum furnace, then take out the vessel and put it into the ultrasonic cleaning machine. After a period of time, the nanoparticles will settle uniformly and finally be closely arranged inside the grating microstructure. .
  • the close arrangement of the metal nanoparticles means that the maximum value of the gap between the metal nanoparticles is less than 10 times the average particle size.
  • the nanoparticles can also be settled without the aid of an ultrasonic cleaner. After being taken out of the vacuum furnace, the nanoparticles in the suspension are allowed to settle freely and eventually fill the grating microstructure. For gratings with a relatively small period (such as a 5.6-micron grating structure), after filling in a vacuum state, it is necessary to press external force such as centrifugal force to press the metal nanoparticles into the grating microstructure.
  • Post-treatment cleaning the metal nanoparticles on the surface of the substrate. After the filling is completed, the surface of the substrate is covered with metal nanoparticle powder, which is quickly cleaned off with low-power ultrasound.
  • Embodiment 1-1 a method for manufacturing an X-ray absorption grating, including the following steps:
  • A. Microstructure of grating select 5 inch silicon substrate, first copy the grating pattern on the mask to the silicon substrate covered with photoresist.
  • the grating pattern is a stripe array with a period of 42 microns and a duty cycle of 1 /4, the grating pattern is cured on the silicon substrate through development and fixing.
  • the substrate in this embodiment is a silicon substrate, and it can also be directly replaced with a germanium substrate, a diamond substrate, or a plastic substrate, without affecting the experimental results.
  • the surface of the silicon substrate was etched inwards to produce a grating groove structure with a depth of 150 ⁇ m and an aspect ratio of 3.57.
  • tungsten nanoparticles with an average particle size of 50nm can be selected, ethanol is added, and surfactant OP10 is added. With the aid of 750W ultrasound, the nanoparticles are dispersed by ultrasound for 7 minutes Tungsten particles. After dispersion, a uniformly dispersed metal tungsten nanoparticle suspension is prepared; wherein the volume ratio of ethanol: surfactant is 50:1;
  • Pre-filling and settling Put the cleaned silicon substrate into the vessel and put it into the vacuum furnace together to start evacuation. The vacuum degree is 0.2 atm. After 30 minutes, add the completed suspension to the In this vessel, the surface of the silicon substrate is covered. After the suspension enters the grating microstructure, stop the vacuum, deflate the vacuum furnace, and then take out the vessel and put it in the ultrasonic cleaning machine, ultrasonic for 8 minutes, so that the nanoparticles settle down evenly, and finally closely arranged in the grating microstructure internal.
  • Post-treatment cleaning the tungsten nanoparticles on the substrate surface. After filling, if the surface of the substrate is covered with a layer of tungsten nanoparticle powder, use 300W power ultrasound for 5 seconds to remove excess tungsten metal nanoparticles remaining on the surface. Finally, the absorption grating shown in Fig. 1 is obtained.
  • Fig. 1 using an absorption grating filled with tungsten nanoparticles, the base period of the absorption grating is 42 microns, the duty cycle is 1/4, and the depth is 150 microns. It can be seen that the tungsten nanoparticles are filled in the grating grooves of this scale Dense.
  • Example 1-1 Compare the grating of Example 1-1 with the absorption grating filled with molten bismuth used in the conventional micro-casting technique.
  • Comparative example the same silicon-based micrograting structure is filled with molten bismuth to obtain the absorption grating shown in FIG. 2. It can be seen from FIG. 2: using the same silicon substrate as in Example 1-1, using micro-casting technology to fill the bismuth into the grating groove, the gray part in the figure is bismuth, the darker part is silicon, because it is bismuth The bulk is denser than tungsten nanoparticles.
  • the focal spot size of the micro-focal spot source is 7 ⁇ m
  • the X-ray flat panel detector is placed at a distance of 1 m from the micro-focal spot source
  • the grating is placed at the X-ray exit of the micro-focal spot source, that is, through the distance Enlarge the raster.
  • the high voltage of the microfocus spot source is set to 40kV
  • the current is set to 80 ⁇ A
  • the exposure time is set to 3s.
  • the absorption effect of the absorption grating made of the two metal materials shown in Fig. 1 and Fig. 2 on X-rays is compared. Value, plot the contrast of the respective grating, and obtain the curve of FIG. 3.
  • FIG. 3 It can be seen from FIG. 3 that the broken line and the solid line are respectively obtained based on the gratings shown in FIG. 1 (absorption grating filled with tungsten powder) and FIG. 2 (absorption grating filled with molten bismuth). It can be seen from the comparison that the contrast formed by the absorption gratings made by the two materials is almost the same, and it also shows the effectiveness of the method of the present invention in the production of absorption gratings.
  • Embodiment 1-2 a method for manufacturing an X-ray absorption grating, including the following steps:
  • the substrate is selected from N-type 5-inch crystal orientation (100) silicon substrate, and one side of the silicon substrate is covered with a 300 nm thick Si 3 N 4 film, and then the photomask is used to place the mask on the mask plate.
  • grating pattern (striped array) onto the silicon substrate covered with a photoresist, through the developing and fixing the cured grating pattern on a silicon substrate on a Si 3 N 4 film, etching away the exposed Si 3 N 4 film.
  • the grating pattern here is a stripe array with a period of 5.6 microns and a duty cycle of 1/2.
  • the other side of the silicon substrate is also made a grid-shaped electrode by photolithography technology, and the surface is protected and placed in a 20% KOH solution. After the inverted pyramid-shaped tip structure is etched, the light is used to assist electricity
  • the chemical etching technique uses HF to etch the silicon substrate inwards to form a grating groove structure with a depth of 50 microns and an aspect ratio of 8.92.
  • Configure metal nanoparticle suspension select tungsten nanoparticles with an average particle size of 50nm, add ethanol, and add a surfactant to prepare a uniformly dispersed metal tungsten nanoparticle suspension after dispersion; of which ethanol: surface active
  • the volume ratio of the agent is 10:1;
  • D. Filling and settling Put the cleaned silicon substrate into the vessel, put it into the vacuum furnace together, and start to evacuate. The vacuum degree is 0.3 atm. After 30 minutes, add the configured suspension to the In the vessel, cover the surface of the silicon substrate. After the suspension enters the grating microstructure, the vacuum is stopped and the vacuum furnace is vented. After this operation, the gas in the tank can be removed, so that the grating tank is completely occupied by the suspension. Then remove the vessel and place it in a centrifuge, rotating at 200 rpm to help the tungsten nanoparticles enter the bottom of the grating groove.
  • step E Repeated centrifugal sedimentation: Once filling and centrifugal sedimentation are difficult to fill, the centrifugal filling step needs to be repeated. For inspection, use an optical microscope to view the surface of the substrate. If the surface of the silicon substrate is not covered with metal nanoparticles, repeat step D to continue filling until the metal nanoparticles fill the grating groove or grating hole of the grating microstructure;
  • Post-treatment cleaning the bismuth nanoparticles on the surface of the silicon substrate. After the filling is completed, if the surface of the silicon substrate is covered with a layer of tungsten nanoparticle powder, use 300W ultrasonic power for 5 seconds to remove excess tungsten nanoparticles remaining on the surface. Finally, an absorption grating with a period of 5.6 microns is obtained.
  • Embodiment 1-3 a method for manufacturing an X-ray absorption grating, including the following steps:
  • A. Microstructure of grating N-type 5-inch (100) crystal-oriented silicon substrate is selected.
  • the grating pattern on the mask plate is first copied to the silicon substrate covered with photoresist.
  • the grating pattern (circular shape) is developed and fixed.
  • Array cured on a silicon substrate.
  • step D Repeated filling and sedimentation: Observe the distribution of particles in the grating microstructure by electron microscopy. The filling of the upper part of the grating groove is uneven. Repeat step D to continue filling until the metal nanoparticles fill the grating groove or grating hole of the grating microstructure;
  • Post-treatment cleaning the bismuth nanoparticles on the surface of the substrate. After the filling is completed, the substrate surface is covered with a layer of bismuth nanoparticle powder, which is quickly cleaned off with low-power ultrasound, and finally a grating as shown in FIG. 5 is obtained.
  • the period of the absorption grating is 24 microns, the duty ratio is 1/3, the depth is 130 microns, and the aspect ratio is 5.4. Since the groove width of the absorption grating is much larger than the particle size, a dense filling of bismuth particles is formed, and the entire groove is substantially filled.
  • Example 1-4 A. Grating microstructure: N-type 5-inch (100) crystal-oriented silicon substrate is selected, and the grating pattern (strip array) on the mask plate is first copied onto the silicon substrate covered with photoresist , The grating pattern is cured on the silicon substrate through development and fixing.
  • tungsten nanoparticles with an average particle size of 50 nm can be selected, ethanol is added, and surfactant is added. After dispersion, a uniformly dispersed metal nanoparticle suspension is prepared. ; Where the volume ratio of ethanol: surfactant is 100:1;
  • D. Filling and settling Put the cleaned silicon substrate into the vessel, put it into the vacuum furnace together, and start to evacuate. The vacuum degree is 0.35 atm. After a period of time, the configured suspension was added to the vessel to cover the surface of the silicon substrate. After the suspension enters the inside of the grating microstructure, stop the vacuum, deflate the vacuum furnace, then take out the vessel and put it into the ultrasonic cleaning machine. After a period of time, the nanoparticles will settle uniformly and finally be closely arranged inside the grating microstructure. .
  • step D Repeated filling and sedimentation: Observe the distribution of particles in the grating microstructure by electron microscopy. The grating microstructure is not covered with tungsten nanoparticles. Repeat step D to continue filling until the metal nanoparticles fill the grating groove of the grating microstructure or Grating hole
  • Post-treatment cleaning the tungsten nanoparticles on the substrate surface. After the filling is completed, the surface of the substrate is covered with tungsten nanoparticle powder, which is quickly cleaned off with low-power ultrasound, and finally an absorption grating as shown in FIG. 6 is obtained.
  • the absorption grating filled with tungsten nanoparticles has the same substrate as shown in Fig. 5, with a 24 ⁇ m duty cycle of 1/3 and a depth of 130 ⁇ m.
  • the tungsten nanopowder is densely packed .
  • FIG. 7 is a more microscopic SEM image of FIG. 6, from which it can be seen that the uniformity of filling and the density of the filled particles.
  • Example 1-5 The tungsten powder and bismuth powder in the above examples can be directly replaced with gold powder or lead powder. Other steps and experimental conditions remain unchanged, and can also be used for the production of X-ray absorption gratings, and the obtained absorption gratings The contrast ratio of the absorption grating obtained by melt filling the existing micro-casting technology is comparable.
  • an X-ray absorption grating includes a substrate 1, the substrate 1 is provided with a grating groove 2a or a grating hole 2b, and the grating groove 2a or the grating hole 2b forms a grating groove array or In the grating hole array, the part of the groove width or aperture removed in one period is the grating side wall 5, and the grating groove 2a or the grating hole 2b is filled with nano-particles 3 of X-ray strongly absorbing metal.
  • the substrate 1 is selected from a silicon substrate, a germanium substrate, a plastic substrate or a diamond substrate.
  • the above substrate 1 can be used in the present invention. According to different needs, substrates 1 of different materials are selected.
  • the substrate 1 is an etched grating groove 2a or a grating hole 2b, preferably having an aspect ratio ⁇ 100, and most preferably having an aspect ratio ⁇ 50.
  • etching method see the content of Example 1.
  • the X-ray strongly absorbing metal is selected from bismuth, tungsten, gold or lead, and the particle size of the metal nanoparticles 3 is less than half of the groove width of the grating groove 2a or half the aperture diameter of the grating hole 2b.
  • the close arrangement of the metal nanoparticles 3 fills the grating grooves 2a or the grating holes 2b, and the close arrangement refers to the average particle diameter of the metal nanoparticles 3 with the maximum gap between the metal nanoparticles 3 being less than 10 times.
  • the ratio of the width of the grating groove 2a or the diameter of the grating hole 2b to the width of the grating side wall 5 is 5:1-0.2:1 According to different design sizes and parameters of the grating, corresponding to different ratios, any value within this range is applicable to the present invention .
  • FIG. 8-10 it is a one-dimensional grating microstructure, which is to arrange a plurality of grating grooves 2a in sequence, the spacing between the grating grooves 2a is determined according to the grating design, and a one-dimensional grating microstructure is to arrange a plurality of rows of grating grooves in sequence 2a, the grating grooves 2a are arranged to form an array, and the array arrangement is a rectangular array.
  • the grating period from 0.5 ⁇ m to 50 ⁇ m is suitable for the present invention.
  • the anti-lodging strip 4 provided in the vertical direction of the one-dimensional grating groove 2a to reinforce the structure.
  • the present invention may also be a grating hole 2b structure as shown in FIG.
  • the grating holes 2b are arranged to form an array, and the array is arranged in a rectangular array.
  • the two-dimensional grating microstructure may be grating grooves 2a arranged in a crisscross pattern, grating holes 2b arranged in a crisscross pattern, or a combination of grating grooves 2a or grating holes 2b.

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Abstract

一种X射线吸收光栅制作方法及X射线吸收光栅，制作方法包括步骤：在基底(1)上制作光栅槽(2a)或光栅孔(2b)，形成光栅槽阵列或光栅孔阵列；有机溶剂、水、表面活性剂清洗基底(1)；金属纳米颗粒(3)加入挥发性溶剂和表面活性剂，制得悬浊液；真空下，将金属纳米颗粒悬浊液填充至光栅微结构中，且金属纳米颗粒(3)沉降填满光栅槽(2a)或光栅孔(2b)；检测，如填充不均匀或者光栅微结构内没有布满金属纳米颗粒(3)，继续填充；清洗基底表面的金属纳米颗粒(3)。吸收光栅包括基底(1)，基底上(2)设有光栅槽阵列或光栅孔阵列，光栅槽(2a)或光栅孔(2b)填满金属纳米颗粒(3)。与熔融金属材料制成的光栅性能相差无几，且制作方法简单、门槛低、成本低廉，便于在普通实验室操作及实现。

Description

X射线吸收光栅制作方法及其X射线吸收光栅 技术领域
本发明涉及一种X射线吸收光栅，尤其涉及一种X射线吸收光栅制作方法。
 背景技术
吸收光栅是X射线光栅微分相衬成像技术中必不可少的关键器件，在该技术中，其可分为源光栅与分析光栅。2006年F. Pfeiffer等人将Lau效应引入X射线相衬成像技术中，使用源光栅将普通X射线管发出的非相干X射线调制为部分相干（在一个光栅周期内），在满足相衬成像对相干性要求的同时，充分利用了X射线通量。另一方面，为分辨物体引起的相位光栅自成像条纹的剪切量，通常在自成像位置放置分析光栅来对相位信息取样。
 一般地，分析光栅的周期小、深宽比大，制作难度很大。目前，LIGA（Lithography, Electroplating, and Molding）仍是制作吸收光栅的主流技术，能够制作大面积、高深宽比的分析光栅。但其技术壁垒高，无法在普通实验室内实现。随后，出现了将微铸造技术、纳米压印技术等应用在光栅制作中的技术，但微铸造技术在对光栅微结构表面改性的环节上，需要经过高温过程，且在金属填充环节上，需要专用填充炉，有一定的破损率。纳米压印技术虽然能够得到小周期的分析光栅，但制作面积十分受限。
 技术问题
一般地，分析光栅的周期小、深宽比大，制作难度很大。目前，LIGA（Lithography, Electroplating, and Molding）仍是制作吸收光栅的主流技术，能够制作大面积、高深宽比的分析光栅。但其技术壁垒高，无法在普通实验室内实现。随后，出现了将微铸造技术、纳米压印技术等应用在光栅制作中的技术，但微铸造技术在对光栅微结构表面改性的环节上，需要经过高温过程，且在金属填充环节上，需要专用填充炉，有一定的破损率。纳米压印技术虽然能够得到小周期的分析光栅，但制作面积十分受限。
 技术解决方案
本发明要解决的技术问题在于，针对现有技术的缺陷，提供一种制作方法简单、门槛低、成本低廉，便于在普通实验室操作及实现的X射线吸收光栅制作方法。
本发明进一步要解决的技术问题在于，提供一种与熔体或电镀金属填充的光栅相当、但成本低廉、便于在普通实验室操作及实现的X射线吸收光栅。
本发明解决其技术问题所采用的技术方案是：
一种X射线吸收光栅制作方法，包括以下步骤：
A、光栅微结构制作：根据光栅图形在基底上制作光栅槽或光栅孔，光栅槽或光栅孔形成光栅槽阵列或光栅孔阵列；
B、清洗干燥：采用有机溶剂、水、表面活性剂清洗光栅微结构，然后干燥；
C、配置金属纳米颗粒悬浊液：选用金属纳米颗粒，加入挥发性溶剂，并加入表面活性剂，分散后制得均匀分散的金属纳米颗粒悬浊液；其中挥发性溶剂：表面活性剂的体积比为(200:1)-(20:1)，金属纳米颗粒选用X射线强吸收金属；金属纳米颗粒的粒径小于槽宽的一半或孔径的一半；
D、预填充及其沉降：真空下，将金属纳米颗粒悬浊液填充至光栅微结构的光栅槽或光栅孔中，并使得金属纳米颗粒沉降填满光栅微结构的光栅槽或光栅孔；
E、重复填充及沉降：检测，如填充不均匀或者光栅微结构内没有布满金属纳米颗粒，继续填充至金属纳米颗粒填满光栅微结构的光栅槽或光栅孔；
F、后处理：清洗基底表面的金属纳米颗粒，得到X射线吸收光栅。
进一步地，所述的X射线吸收光栅制作方法中，优选所述步骤A中，所述光栅图形是采用掩模板将光栅图形复制到覆盖有光刻胶的基底表面，通过显影、定影将光栅图形固化在基底表面。
进一步地，所述的X射线吸收光栅制作方法中，优选所述步骤A中，所述基底选用硅基底、锗基底、塑料基底或金刚石基底，采用深反应离子刻蚀沿基底表面的光栅图形向内刻蚀，刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应；
或者，所述步骤A中，所述基底选用晶向（110）硅基底，在不需刻蚀的区域使用膜层覆盖，通过KOH溶液或TMAH对不同晶面的腐蚀速率刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应；
或者，所述步骤A中，所述基底选用N型或P型（100）晶向的硅基底，在硅基底背面涂覆形成一层透明导电层，在硅基底的两面施加电场，对硅基底进行刻蚀，刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应。
进一步地，所述的X射线吸收光栅制作方法中，优选所述步骤B中，所述表面活性剂选用OP10、CO520、聚乙烯醇、NMP、CTAB、DMSO或DMF，所述清洗为超声清洗或振荡清洗。
进一步地，所述的X射线吸收光栅制作方法中，优选所述步骤C中，所述表面活性剂选用OP10（烷基酚聚氧乙烯醚）、CO520（烷基酚乙氧化物），所述X射线强吸收金属选用铋、钨、金或铅。
进一步地，所述的X射线吸收光栅制作方法中，优选所述步骤D中，所述真空的真空度高于0.1个大气压。
进一步地，所述的X射线吸收光栅制作方法中，优选所述步骤D中，所述金属纳米颗粒的紧密排列指金属纳米颗粒之间的空隙最大值小于10倍的金属纳米颗粒平均粒径。
进一步地，所述的X射线吸收光栅制作方法中，优选所述步骤E中，检测是指电镜抽样观察金属纳米颗粒在光栅微结构内的分布情况；或者使用光学显微镜查看基底表面，如果基底表面没有布满金属纳米颗粒，则继续填充，如果基底表面布满金属纳米颗粒则不再填充。
一种X射线吸收光栅，包括基底，所述基底是设有光栅槽或光栅孔，光栅槽或光栅孔形成光栅槽阵列或光栅孔阵列，所述光栅槽或光栅孔中填充有X射线强吸收金属的纳米颗粒；所述的X射线吸收光栅中，优选所述X射线吸收光栅为一维结构或二维结构，在一维结构的光栅槽或光栅孔的垂直方向上设置的防倒伏的条带。
进一步地，所述的X射线吸收光栅中，优选所述光栅周期从0.5μm至50μm，所述光栅孔宽度或光栅孔直径与光栅侧壁的宽度比为5:1-0.2:1。
 有益效果
本发明的X射线吸收光栅制作方法简单、门槛低、成本低廉，便于在普通实验室操作及实现。以对X射线强吸收的纳米金属颗粒作为吸收物质，以获得的光栅微结构为基底，本发明将金属纳米颗粒制成悬浊液，可以对金属纳米颗粒进行分散，以避免颗粒间抱团形成更大直径颗粒，进而阻碍顺利进入光栅微结构内部的光栅槽或光栅孔中，保持纳米颗粒分散的特性，对填充十分有利。而且，考虑采用表面活性剂与光栅微结构表面的浸润性，相对增加悬浊液表面与光栅微结构表面之间的附着力，在负压下，使悬浊液在基底表面上全面铺开，包括进入光栅微结构的光栅槽或光栅孔中，悬浊液进而携带金属纳米颗粒到达光栅微结构的光栅槽或光栅孔底部，由于光栅孔或光栅槽内有空气，且金属纳米颗粒克服表面张力到达光栅孔或光栅槽内是很困难的事情，本发明就相应解决了直接填充金属颗粒时，难以填充的问题。
本发明能将金属纳米颗粒致密地填入光栅微结构内部，避免了现有技术中微铸造高温过程，提高了成品率，且能够在大面积的光栅微结构上实现吸收光栅的制作。
本发明的X射线吸收光栅，在光栅微结构中致密排列金属纳米颗粒，对X射线的吸收虽然比相同物质的体状结构（熔融金属形成）吸收稍弱，但仍然能够形成足够的吸收对比度。因此，相对于现有技术，金属纳米颗粒填充的X射线吸收光栅，在X射线大面积吸收光栅的低成本制作方面具有独特的优势。
 附图说明
下面将结合附图及实施例对本发明作进一步说明，附图中：
图1是本发明实施例1-1使用钨纳米颗粒填充周期42微米、深度150微米的吸收光栅的侧面SEM照片；
图2是使用微铸造技术在周期42微米、深度150微米的硅基底上熔融填充金属铋的SEM照片；
图3是本发明实施例1-1的钨纳米粉与使用微铸造技术熔融铋填充所得吸收光栅的对比度对比图；
图4是本发明实施例1-2的周期5.6微米、深度50微米的吸收光栅侧面SEM照片；
图5是本发明实施例1-3的周期24微米，深度130微米的吸收光栅的侧面SEM照片；
图6是本发明实施例1-4的周期24微米，深度130微米的吸收光栅的侧面SEM照片；
图7是本发明实施例1-4光栅微结构内的钨纳米颗粒填充SEM照片；
图8是本发明实施例2的未填充X射线吸收光栅结构示意图；
图9是本发明实施例2的填充的X射线吸收光栅结构示意图；
图10是本发明实施例2的X射线吸收光栅俯视结构示意图；
图11是本发明实施例2的X射线吸收光栅另一种实施方式结构示意图。
 本发明的最佳实施方式
为了对本发明的技术特征、目的和效果有更加清楚的理解，现对照附图详细说明本发明的具体实施方式。
实施例1、一种X射线吸收光栅制作方法，包括以下步骤：
A、光栅微结构制作：根据光栅图形在基底上制作光栅槽或光栅孔；
所述光栅图形是采用掩模版将光栅图形复制到覆盖有光刻胶的基底表面，通过显影、定影将光栅图形固化在基底表面。光栅图形复制和固化可以采用现有常规技术进行，在此不再赘述。光栅图形可以根据实际需要设计，可以是一维结构，也可以是二维结构，一维结构可以采用条带，二维结构可以是纵横交错的条带，也可以是纵横交错排列的四边合围结构单元组成，也可以是条带和四边合围结构单元的组合。四边合围结构单元可以是首尾相接的曲线结构，例如圆、椭圆等，也可以是多边形，例如三角形、四边形、六边形等，优选圆和椭圆。
制作光栅槽或光栅孔结构有几种技术方案：
第一种为：所述基底选用硅基底、锗基底、塑料基底或金刚石基底，采用深反应离子刻蚀沿基底表面的光栅图形向内刻蚀，刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应。深反应离子刻蚀（DRIE）是一项实现基底各向异性腐蚀的技术，在等离子体环境中，离子在电场的作用下轰击裸露出的基底，对于基底而言，一般使用SF 6，为形成光栅槽或光栅孔的垂直侧壁结构，需要在刻蚀一段时间后（一般为几秒），覆盖一层钝化层在光栅槽或光栅孔的侧壁表面以防止侧壁被过度腐蚀，然后再继续刻蚀，以此往复，经历若干这样的循环后，便形成了具有一定深宽比的光栅槽或光栅孔微结构，深宽比是指深度与宽度（直径）之比。深反应离子刻蚀（DRIE）具体参数选择可以根据具体刻蚀对象的尺寸、物理特性进行选择，在此不再赘述。
第二种为：基底选用晶向（110）硅基底时，在不需刻蚀的区域使用膜层覆盖，通过KOH溶液或TMAH对不同晶面的腐蚀速率刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应。硅基底的各项异性腐蚀是硅微机械加工的重要技术，其主要利用腐蚀液对硅的各个晶面腐蚀速率的差别来实现的。将所需掩膜覆盖在（110）硅的表面上，并将其放入浓度10%-50%的KOH或TMAH中，这样，向下腐蚀速率是向侧壁腐蚀速率的几十、甚至几百倍。经过一段时间后，即可得到一定深宽比的光栅槽或光栅孔微结构。硅基底的各项异性腐蚀的具体参数选择可以根据具体刻蚀对象的尺寸、物理特性进行选择，在此不再赘述。
第三种为：基底选用N型或P型（100）晶向的硅基底时，在背面涂覆形成一层透明导电层，在基底的两面施加电场，对基底进行光助电化学刻蚀。选用晶向（100）的基底，并将掩膜覆盖在基底的一面，在另一面覆盖上铝电极，将有掩膜的一面首先面向KOH溶液，需要刻蚀出倒金字塔状的尖端，然后将腐蚀剂换为HF的水溶液，在一定光照的辅助下，在尖端对空穴的引导下，施加一定的电压，即可开始向下腐蚀。经过一段时间腐蚀，即可刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应。光助电化学刻蚀为现有技术，其具体参数选择可以根据具体刻蚀对象的尺寸、物理特性进行选择，在此不再赘述。
根据光栅图形，条带对应刻蚀后形成的光栅槽，圆、椭圆或方孔对应刻蚀后形成的光栅孔，光栅微结构也可以是光栅槽和光栅孔的结合。本发明需要刻蚀出具有一定深宽比的光栅槽和光栅孔，一般要求深宽比＜200，优选深宽比＜100，最优选深宽比＜50。本发明适合各种深宽比的光栅，例如深宽比＜3的吸收光栅、深宽比＞3的高深宽比的吸收光栅，深宽比＞50的超高深宽比的吸收光栅。
B、清洗干燥：采用有机溶剂、水、表面活性剂清洗光栅微结构，然后干燥；本步骤中所述表面活性剂可以选择多种，只需能对基底表面产生浸润作用，并且通过溶解、吸附、乳化、增溶等作用实现清洁目的的表面活性剂，都适用本发明。优选OP10、CO520、聚乙烯醇、NMP、CTAB、DMSO或DMF，所述清洗为超声清洗或振荡清洗。有机溶剂优选挥发性有机溶剂，可以选择：低碳链的烷烃、烯烃、醇、酯、醚或酮，例如：甲醇、乙醇、丙酮、乙酸乙酯、四氯甲烷，石油醚、氯仿、乙醚等。
具体例如：使用有机溶剂丙酮在超声下清洗15分钟，再使用纯水超声清洗15分钟，最后使用挥发性溶剂和表面活性剂OP10或挥发性溶剂与表面活性剂CO520的混合溶液进行超声清洗15分钟，使用烘箱烘干基底。
C、配置金属纳米颗粒悬浊液：选用金属纳米颗粒，加入挥发性溶剂，并加入表面活性剂，分散后制得均匀分散的金属纳米颗粒悬浊液；其中挥发性溶剂：表面活性剂的体积比为(200:1)-(20:1)，金属纳米颗粒选用X射线强吸收金属；金属纳米颗粒的粒径小于槽宽的一半或孔径的一半；本步骤中所述挥发性有机溶剂可以选择：低碳链的烷烃、烯烃、醇、酯、醚、酮，例如：甲醇、乙醇、丙酮、乙酸乙酯、四氯甲烷，石油醚、氯仿、乙醚等。本步骤中所述表面活性剂可以选择多种，只需能对基底表面产生浸润作用，降低表面张力的表面活性剂都适用本发明。
D、填充及其沉降：真空下，将金属纳米颗粒悬浊液填充至光栅微结构的光栅槽或光栅孔中，并使得金属纳米颗粒沉降填满光栅微结构的光栅槽或光栅孔；
具体为：将清洗后的基底放入一个合适的器皿中，一并放入真空炉内，开始抽真空，真空度高于0.1个大气压。一段时间后，将配置完成的悬浊液加入到该器皿中，没过光栅微结构表面。这样，在负压与毛细力的作用下，悬浊液很快进入到光栅微结构内部，将气体排出。待悬浊液进入光栅微结构内部后，停止抽真空，对真空炉放气，然后取出器皿并放入超声清洗机内，超声一段时间使得纳米颗粒均匀沉降，并最终紧密排列在光栅微结构内部。所述金属纳米颗粒的紧密排列指金属纳米颗粒之间的空隙最大值小于10倍的平均粒径。
对于小面积的光栅，也可不用超声清洗机辅助沉降纳米颗粒，自真空炉内取出后，使悬浊液中的纳米颗粒自由沉降，并最终充满光栅微结构。对于周期较小的光栅（如5.6微米的光栅结构），在真空状态下填充后，需要借助外力如离心力将金属纳米颗粒压入光栅微结构内部。
E、重复填充及沉降：检测，如填充不均匀或者光栅微结构内没有布满金属纳米颗粒，继续填充至金属纳米颗粒填满光栅微结构的光栅槽或光栅孔；检测是指电镜抽样观察粒子在光栅微结构内的分布情况；或者使用光学显微镜查看基底表面，如果基底表面没有布满金属纳米颗粒，则继续填充，如果基底表面布满金属纳米颗粒则不再填充。
F、后处理：清洗基底表面的金属纳米颗粒。填充结束后，基底表面覆盖有金属纳米颗粒粉末，用小功率超声快速清洗掉。
以下通过具体实施例进行详细说明：
实施例1-1，一种X射线吸收光栅制作方法，包括以下步骤：
A、光栅微结构：选用5英寸硅基底，先将掩膜版上的光栅图形复制到覆盖有光刻胶的硅基底上，光栅图形为条带阵列，周期为42微米，占空比为1/4，通过显影、定影将光栅图形固化在硅基底上。本实施例的基底选用硅基底，还可以直接替换为锗基底、金刚石基底或塑料基底，并不影响实验结果。
利用DRIE（深反应离子刻蚀）技术在硅基底表面向内刻蚀，制作了深度为150μm的光栅槽结构，深宽比为3.57。
B、清洗干燥：使用丙酮将硅基底在超声下清洗15分钟，再使用纯水超声清洗15分钟，最后使用乙醇和表面活性剂OP10或乙醇与表面活性剂CO520的混合溶液进行超声清洗15分钟，使用烘箱烘干硅基底。
C、配置金属纳米颗粒悬浊液：考虑成本及安全性，可选用平均粒径为50nm的钨纳米颗粒，加入乙醇，并加入表面活性剂 OP10，在750W超声的辅助下，超声7分钟分散纳米钨颗粒。分散后制得均匀分散的金属钨纳米颗粒悬浊液；其中乙醇：表面活性剂的体积比为50:1；
D、预填充及其沉降：将清洗后的硅基底放入器皿中，一并放入真空炉内，开始抽真空，真空度为0.2大气压，30分钟后，将配置完成的悬浊液加入到该器皿中，覆盖硅基底表面。待悬浊液进入光栅微结构内部后，停止抽真空，对真空炉放气，然后取出器皿并放入超声清洗机内，超声8分钟，使得纳米颗粒均匀沉降，并最终紧密排列在光栅微结构内部。
E、重复填充及沉降：电镜抽样观察金属纳米颗粒在光栅微结构内的分布情况，发现光栅微结构内没有布满钨纳米颗粒，配制相同的悬浊液，将预填充过的基底置于真空环境中，悬浊液没过基底表面。真空下或大气环境下，经过8小时静置沉降或超声沉降后，即可获得较为致密填充的基底；
F、后处理：清洗基底表面的钨纳米颗粒。填充结束后，若基底表面覆盖了一层钨纳米颗粒粉末，使用300W功率的超声，超声5秒时间，去除表面残留的多余的钨金属纳米颗粒。最后得到如图1所示的吸收光栅。
从图1可以看出：使用钨纳米颗粒填充的吸收光栅，吸收光栅的基底周期为42微米，占空比为1/4，深度150微米，可见，钨纳米颗粒在该尺度的光栅槽中填充致密。
将实施例1-1的光栅与传统的微铸造技术所使用的熔融铋填充的吸收光栅做对比。
对比例：在相同的硅基微光栅结构内填充熔融铋，得到如图2所示的吸收光栅。从图2可以看出：利用与实施例1-1相同的硅基底，使用微铸造技术将熔融铋填充进光栅槽中，图中灰色部分为铋，较暗的部分为硅，由于是铋的块体，填充比钨纳米颗粒填充更为致密。
使用X射线投影成像方法测试，微焦斑源焦斑大小为7μm，距离微焦斑源1m的距离放置X射线平板探测器，将光栅放置在微焦斑源的X射线出口处，即通过距离对光栅放大。微焦斑源的高压设为40kV，电流设为80μA，曝光时间设为3s，对比了图1和图2两种金属材料制作的吸收光栅对X射线的吸收效果，依据X射线探测器的像素值，描绘出各自光栅的对比度，得到图3的曲线。从图3可以看出：其中虚线、实线是分别基于图1（填充钨粉的吸收光栅）和图2（填充熔融铋的吸收光栅）所示光栅分别获得的。对比可知，两种材料制作的吸收光栅形成的对比度相差无几，也显示出以本发明方法在吸收光栅制作方面的有效性。
实施例1-2，一种X射线吸收光栅制作方法，包括以下步骤：
A、光栅微结构制作：基底选用N型5英寸晶向（100）的硅基底，在硅基底的一面覆盖一层300nm厚的Si 3N 4薄膜，再利用光刻技术将掩膜版上的光栅图形（条带阵列）复制到覆盖有光刻胶的硅基底上，通过显影、定影将光栅图形固化在硅基底上的Si 3N 4薄膜上，刻蚀掉裸露的Si 3N 4薄膜。这里的光栅图形为条带阵列，周期为5.6微米，占空比为1/2。将硅基底的另一面同样以光刻技术制作一层栅格状电极，将该面保护后放入配置好的20%的KOH溶液中，待腐蚀出倒金字塔状尖端结构后，利用光助电化学刻蚀技术，借助HF向内腐蚀硅基底，形成深度为50微米的光栅槽结构，深宽比为8.92。
B、清洗干燥：使用丙酮在超声下清洗15分钟，再使用纯水超声清洗15分钟，最后使用乙醇与表面活性剂CO520的混合溶液进行超声清洗15分钟，使用烘箱烘干硅基底。
C、配置金属纳米颗粒悬浊液：选用平均粒径为50nm的钨纳米颗粒，加入乙醇，并加入表面活性剂，分散后制得均匀分散的金属钨纳米颗粒悬浊液；其中乙醇：表面活性剂的体积比为10:1；
D、填充及其沉降：将清洗后的硅基底放入器皿中，一并放入真空炉内，开始抽真空，真空度为0.3大气压，30分钟后，将配置完成的悬浊液加入到该器皿中，覆盖硅基底表面。待悬浊液进入光栅微结构内部后，停止抽真空，对真空炉放气，经过该操作，可排除槽内的气体，使光栅槽内完全被悬浊液占据。然后取出器皿并放入一离心机内，以200转/分钟的转速旋转，帮助钨纳米粒子进入光栅槽内底部。
E、重复离心沉降：一次填充与离心沉降难以填满，需要重复进行离心填充步骤。检测，使用光学显微镜查看基底表面，硅基底表面没有布满金属纳米颗粒，则重复步骤D，继续填充至金属纳米颗粒填满光栅微结构的光栅槽或光栅孔；
F、后处理：清洗硅基底表面的铋纳米颗粒。填充结束后，若硅基底表面覆盖了一层钨纳米颗粒粉末，使用300W功率的超声，超声5秒时间，去除表面残留的多余的钨纳米颗粒。最后得到周期5.6微米的吸收光栅。
    从图4可以看出：吸收光栅的周期为5.6微米，占空比0.5，为2.8微米，深度为50微米，从SEM照片中可直接看出钨的颗粒（图中灰色颗粒部分）已填充至硅基底光栅槽的底部，基本实现了致密填充，部分填充不足的地方，其间隙也小于10倍的金属钨纳米颗粒的平均粒径，可以用于作为吸收光栅。
实施例1-3，一种X射线吸收光栅制作方法，包括以下步骤：
A、光栅微结构：选用N型5英寸（100）晶向硅基底，先将掩膜版上的光栅图形复制到覆盖有光刻胶的硅基底上，通过显影、定影将光栅图形（圆形阵列）固化在硅基底上。
B、清洗干燥：使用丙酮在超声下清洗15分钟，再使用纯水超声清洗15分钟，最后使用乙醇和表面活性剂OP10或乙醇与表面活性剂CO520的混合溶液进行超声清洗15分钟，使用烘箱烘干硅基底。
C、配置金属纳米颗粒悬浊液：考虑成本及安全性，可选用平均粒径为50nm的铋纳米颗粒，加入乙醇，并加入表面活性剂，分散后制得均匀分散的金属铋纳米颗粒悬浊液；其中乙醇：表面活性剂的体积比为30:1；
D、填充及其沉降：将清洗后的硅基底放入器皿中，一并放入真空炉内，开始抽真空，真空度为0.25大气压。一段时间后，将配置完成的悬浊液加入到该器皿中，覆盖硅基底表面。待悬浊液进入光栅微结构内部后，停止抽真空，对真空炉放气，然后取出器皿并放入超声清洗机内，超声一段时间使得铋纳米颗粒均匀沉降，并最终紧密排列在光栅微结构内部。
E、重复填充及沉降：电镜抽样观察粒子在光栅微结构内的分布情况，光栅槽上部填充不均匀，重复步骤D，继续填充至金属纳米颗粒填满光栅微结构的光栅槽或光栅孔；
F、后处理：清洗基底表面的铋纳米颗粒。填充结束后，基底表面覆盖了一层铋纳米颗粒粉末，用小功率超声快速清洗掉，最后得到如图5所示光栅。
    从图5可以看出：吸收光栅的周期为24微米，占空比为1/3，深度为130微米，深宽比为5.4。由于吸收光栅的槽宽远大于颗粒粒径，形成了铋颗粒的致密填充，且基本上充满了整个槽。
实施例1-4，A、光栅微结构：选用N型5英寸（100）晶向硅基底，先将掩膜版上的光栅图形（条带阵列）复制到覆盖有光刻胶的硅基底上，通过显影、定影将光栅图形固化在硅基底上。
B、清洗干燥：使用丙酮在超声下清洗15分钟，再使用纯水超声清洗15分钟，最后使用乙醇和表面活性剂OP10或乙醇与表面活性剂CO520的混合溶液进行超声清洗15分钟，使用烘箱烘干硅基底。
C、配置金属纳米颗粒悬浊液：考虑成本及安全性，可选用平均粒径为50nm的钨纳米颗粒，加入乙醇，并加入表面活性剂，分散后制得均匀分散的金属纳米颗粒悬浊液；其中乙醇：表面活性剂的体积比为100:1；
D、填充及其沉降：将清洗后的硅基底放入器皿中，一并放入真空炉内，开始抽真空，真空度为0.35大气压。一段时间后，将配置完成的悬浊液加入到该器皿中，覆盖硅基底表面。待悬浊液进入光栅微结构内部后，停止抽真空，对真空炉放气，然后取出器皿并放入超声清洗机内，超声一段时间使得纳米颗粒均匀沉降，并最终紧密排列在光栅微结构内部。
E、重复填充及沉降：电镜抽样观察粒子在光栅微结构内的分布情况，光栅微结构内没有布满钨纳米颗粒，重复步骤D，继续填充至金属纳米颗粒填满光栅微结构的光栅槽或光栅孔；
F、后处理：清洗基底表面的钨纳米颗粒。填充结束后，基底表面覆盖有钨纳米颗粒粉末，用小功率超声快速清洗掉，最后得到如图6所示吸收光栅。
从图6可以看出：使用钨纳米颗粒填充的吸收光栅，吸收光栅的基底与图5所展示的相同，为24微米，占空比为1/3，深度130微米，钨纳米粉的填充致密。
图7是图6更为微观的SEM图，从图7可以看出填充的均匀性与填充颗粒的致密性。
实施例1-5，上述实施例中的钨粉和铋粉，可以直接替换为金粉或铅粉，其他步骤和实验条件不变，同样能用于X射线吸收光栅的制作，且得到的吸收光栅的对比度与现有的微铸造技术熔体填充所得吸收光栅的对比度相当。
实施例2，如图8-11所示，一种X射线吸收光栅，包括基底1，所述基底1是设有光栅槽2a或光栅孔2b，光栅槽2a或光栅孔2b形成光栅槽阵列或光栅孔阵列，在一个周期内除去槽宽或孔径的部分为光栅侧壁5，所述光栅槽2a或光栅孔2b中填充有X射线强吸收金属的纳米颗粒3。
所述基底1选用硅基底、锗基底、塑料基底或金刚石基底，上述基底1都可以用于本发明，根据不同需要，选用不同材料的基底1。
基底1是刻蚀光栅槽2a或光栅孔2b，优选深宽比＜100，最优选深宽比＜50。具体刻蚀方法见实施例1的内容。
所述X射线强吸收金属选用铋、钨、金或铅，金属纳米颗粒3的粒径小于光栅槽2a槽宽的一半或光栅孔2b孔径的一半。优选金属纳米颗粒3的紧密排列填充满光栅槽2a或光栅孔2b，紧密排列指金属纳米颗粒3之间的空隙最大值小于10倍的金属纳米颗粒3的平均粒径。
所述光栅槽2a宽度或光栅孔2b直径与光栅侧壁5的宽度比为5:1-0.2:1根据不同设计尺寸和参数的光栅，对应有不同比例，该范围内任何数值都适用本发明。
如图8-10所示是一维的光栅微结构，是顺序排列多个光栅槽2a，光栅槽2a之间的间距根据光栅设计确定，一维的光栅微结构是顺序排列多排的光栅槽2a，光栅槽2a排列形成阵列，阵列排布方式为矩形阵列。光栅周期从0.5μm至50μm都适用本发明。如图10所示，在一维结构的光栅槽2a的垂直方向上设置的防倒伏的条带4，以强化结构。
除了上述光栅槽2a结构，本发明还可以是如图11的光栅孔2b结构。光栅孔2b排列形成阵列，阵列排布方式为矩形阵列。
二维的光栅微结构可以是纵横交错排列的光栅槽2a，也可以是纵横交错排列的光栅孔2b，也可以是光栅槽2a或光栅孔2b的组合。

Claims (10)

  1. 一种X射线吸收光栅制作方法，其特征在于，包括以下步骤：
    A、光栅微结构制作：根据光栅图形在基底上制作光栅槽或光栅孔，光栅槽或光栅孔排列形成光栅槽阵列或光栅孔阵列；
    B、清洗干燥：采用有机溶剂、水、表面活性剂清洗光栅微结构，然后干燥；
    C、配置金属纳米颗粒悬浊液：选用金属纳米颗粒，加入挥发性溶剂，并加入表面活性剂，分散后制得均匀分散的金属纳米颗粒悬浊液；其中挥发性溶剂：表面活性剂的体积比为(200:1)-(20:1)，金属纳米颗粒选用X射线强吸收金属；金属纳米颗粒的粒径小于槽宽的一半或孔径的一半；
    D、预填充及其沉降：真空下，将金属纳米颗粒悬浊液填充至光栅微结构的光栅槽或光栅孔中，并使得金属纳米颗粒沉降填满光栅微结构的光栅槽或光栅孔；
    E、重复填充及沉降：检测，如填充不均匀或者光栅微结构内没有布满金属纳米颗粒，继续填充至金属纳米颗粒填满光栅微结构的光栅槽或光栅孔；
    F、后处理：清洗基底表面的金属纳米颗粒，得到X射线吸收光栅。
  2. 根据权利要求1所述的X射线吸收光栅制作方法，其特征在于，所述步骤A中，所述光栅图形是采用掩模版将光栅图形复制到覆盖有光刻胶的基底表面，通过显影、定影将光栅图形固化在基底表面。
  3. 根据权利要求1所述的X射线吸收光栅制作方法，其特征在于，所述步骤A中，所述基底选用硅基底、锗基底、塑料基底或金刚石基底，采用深反应离子刻蚀沿基底表面的光栅图形向内刻蚀，刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应；
    或者，所述步骤A中，所述基底选用晶向（110）硅基，在不需刻蚀的区域使用膜层覆盖，通过KOH溶液或TMAH对不同晶面的腐蚀速率刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应；
    或者，所述步骤A中，所述基底选用N型或P型（100）晶向的硅基底，在硅基底背面涂覆形成一层透明导电层，在硅基底的两面施加电场，对硅基底进行刻蚀，刻蚀出光栅槽或光栅孔，所述光栅槽或光栅孔与光栅图形对应。
  4. 根据权利要求1所述的X射线吸收光栅制作方法，其特征在于，所述步骤B中，所述表面活性剂选用OP10、CO520、聚乙烯醇、NMP、CTAB、DMSO或DMF，所述清洗为超声清洗或振荡清洗。
  5. 根据权利要求1所述的X射线吸收光栅制作方法，其特征在于，所述步骤C中，所述表面活性剂选用OP10、CO520，所述X射线强吸收金属选用铋、钨、金或铅。
  6. 根据权利要求1所述的X射线吸收光栅制作方法，其特征在于，所述步骤D中，所述真空的真空度高于0.1大气压。
  7. 根据权利要求1所述的X射线吸收光栅制作方法，其特征在于，所述步骤D中，所述金属纳米颗粒的紧密排列指金属纳米颗粒之间的空隙最大值小于10倍的金属纳米颗粒平均粒径。
  8. 根据权利要求1所述的X射线吸收光栅制作方法，其特征在于，所述步骤E中， 检测是指电镜抽样观察金属纳米颗粒在光栅微结构内的分布情况；或者使用光学显微镜查看基底表面，如果基底表面没有布满金属纳米颗粒，则继续填充，如果基底表面布满金属纳米颗粒则不再填充。
  9. 一种X射线吸收光栅，包括基底，其特征在于，所述基底设有光栅槽或光栅孔，光栅槽或光栅孔排列形成光栅槽阵列或光栅孔阵列，所述光栅槽或光栅孔中填充有X射线强吸收金属的纳米颗粒。
  10. 根据权利要求9所述的X射线吸收光栅，其特征在于，所述光栅周期从0.5μm至50μm，所述光栅槽宽度或光栅孔直径与光栅侧壁的宽度比为5:1-0.2:1。
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