阅读说明：本技术 一种用于氦离子显微镜成像质量校正的样品及其制作方法 (Sample for helium ion microscope imaging quality correction and manufacturing method thereof ) 是由 温晓镭 于 2021-03-05 设计创作，主要内容包括：本发明提供一种用于氦离子显微镜成像质量校正的样品及其制作方法,所述样品包括衬底、导电层和聚苯乙烯微球颗粒,衬底上覆盖导电层,聚苯乙烯微球颗粒分散固定在导电层上；或者包括块体导电材料和聚苯乙烯微球颗粒,聚苯乙烯微球颗粒分散固定在块体导电材料上。由于氦离子在聚苯乙烯材料中穿透能力强,平均穿透深度超过微球尺寸,故聚苯乙烯微球颗粒在氦离子照射下不易发生融化、变形等损伤,并且其边界清晰的球形几何形状可灵敏反映出离子束聚焦问题,有利于离子束聚焦成像质量的校正。同时提供了一种用于氦离子显微镜离子束聚焦成像质量校正的样品的制作方法,该方法步骤简单,工艺要求低,适用于大批量生产。(The invention provides a sample for helium ion microscope imaging quality correction and a manufacturing method thereof, wherein the sample comprises a substrate, a conducting layer and polystyrene microsphere particles, the conducting layer covers the substrate, and the polystyrene microsphere particles are dispersedly fixed on the conducting layer; or comprises a block conductive material and polystyrene microsphere particles, wherein the polystyrene microsphere particles are dispersedly fixed on the block conductive material. As helium ions have strong penetrating power in the polystyrene material, and the average penetrating depth exceeds the size of the microsphere, polystyrene microsphere particles are not easy to melt, deform and the like under the irradiation of the helium ions, and the spherical geometric shape with clear boundaries can sensitively reflect the focusing problem of the ion beam, thereby being beneficial to the correction of the focusing imaging quality of the ion beam. Meanwhile, the method for manufacturing the sample for correcting the ion beam focusing imaging quality of the helium ion microscope is simple in step, low in process requirement and suitable for mass production.)

1. A sample for imaging quality correction of a helium ion microscope is characterized by comprising a substrate, a conductive layer and polystyrene microsphere particles, wherein the conductive layer covers the substrate, and the polystyrene microsphere particles are dispersedly fixed on the conductive layer; or comprises a block conductive material and polystyrene microsphere particles, wherein the polystyrene microsphere particles are dispersedly fixed on the block conductive material.

2. The sample according to claim 1, wherein an adhesion layer is further arranged between the substrate and the conductive layer, the adhesion layer is made of titanium, chromium or nickel, and the thickness of the adhesion layer is 1-20 nm.

3. The sample according to claim 1, wherein the substrate is a silicon wafer, a quartz wafer, a glass wafer, a stainless steel wafer, a copper wafer, an aluminum alloy wafer, a molybdenum wafer, or a tungsten wafer.

4. The sample according to claim 1, wherein the conductive layer or the bulk conductive material is one or more of gold, silver, platinum, copper, aluminum, chromium, titanium, carbon, tungsten, molybdenum, stainless steel and iron.

5. The sample according to claim 1, wherein the polystyrene microsphere particles have a diameter of 10nm to 100 μm; preferably, the diameter of the polystyrene microsphere particle is 10 nm-1 μm; more preferably, the polystyrene microsphere particle diameter is 95 nm; preferably, the polystyrene microsphere particles are replaced by microsphere particles made of carboxyl-polystyrene, amino-polystyrene, macroporous cross-linked polystyrene, polyethylene, polyacrylic acid, polytetrafluoroethylene, gelatin, chitosan, polylactic acid, polybutadiene, polyisoprene, polydimethylsiloxane, polymethyl methacrylate, starch, albumin, silica, alumina or titanium oxide.

6. A method of making a sample according to any one of claims 1 to 5, comprising the steps of:

1) plating a conducting layer on a substrate with a clean and smooth surface, or grinding and leveling the surface of a block conducting material and cleaning;

2) and dispersing and fixing the polystyrene microsphere particles on the conductive layer or the bulk conductive material.

7. The method as claimed in claim 6, wherein the step 1) further comprises a step of cleaning the substrate before plating the conductive layer on the substrate with a clean and flat surface, wherein the cleaning step comprises immersing the substrate in an acetone solution for ultrasonic cleaning for 5-10min, then immersing the substrate in an isopropanol solution for ultrasonic cleaning for 5-10min, and drying the substrate with nitrogen after taking out to obtain the substrate with a clean and flat surface.

8. The method according to claim 6, wherein in the step 1), the surface of the bulk conductive material is cleaned by immersing the bulk conductive material in an acetone solution for ultrasonic cleaning for 5-10min, then immersing the bulk conductive material in an isopropanol solution for ultrasonic cleaning for 5-10min, and drying the bulk conductive material with nitrogen after being taken out.

9. The method of claim 6, wherein the method of plating the conductive layer on the substrate in step 1) is a physical plating method or an electroless plating method.

10. The method as claimed in claim 6, wherein the method for dispersing and fixing the polystyrene microsphere particles in step 2) is to drop, spin or apply a suspension containing the polystyrene microsphere particles to the surface of the conductive layer or the bulk conductive material by a pulling method.

Technical Field

The invention belongs to the technical field of nano imaging, and particularly relates to a sample for imaging quality correction of a helium ion microscope and a manufacturing method thereof.

Background

The helium ion microscope is a gas source ion microscope developed on the basis of a field ion microscope, adopts a focused high-energy helium ion beam to perform scanning imaging on the surface of a sample, has a high-resolution microscopic imaging function similar to a Scanning Electron Microscope (SEM), and has the resolution ratio of less than 0.5 nm.

Helium ion microscopes require a correction to the focusing quality of the ion beam before each use. Through trial focusing on the surface of a specific sample and adjusting the focusing focal length, astigmatism and parameters of an ion beam pair medium ion optical system, the ion beam spot with clear and symmetrical focusing is finally obtained, and the best imaging effect is achieved.

Helium ions have a greater mass than electrons and therefore have a greater penetration depth and micro-zone damage upon incidence on the sample surface. Gold nanoparticle samples commonly used for Scanning Electron Microscope (SEM) imaging quality calibration are very easily damaged under irradiation of focused high-energy helium ion beams, and can be melted, deformed and drifted in a very short time (from several seconds to tens of seconds), so that the adjustment of imaging parameters is influenced, and the correction of ion beam focusing imaging quality is not facilitated.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention provides a sample for imaging quality correction of a helium ion microscope and a manufacturing method thereof. The sample structure is not easy to be damaged by ion beam irradiation, and can sensitively reflect the focusing problems (such as defocusing, astigmatism and the like) of the ion beam, thereby guiding the parameter adjustment of the ion optical system and realizing the correction of the ion beam focusing imaging quality. The manufacturing method of the sample structure is simple and is suitable for mass production.

In order to achieve the purpose, the invention adopts the following technical scheme:

a sample for imaging quality correction of a helium ion microscope comprises a substrate, a conductive layer and polystyrene microsphere particles, wherein the conductive layer covers the substrate, and the polystyrene microsphere particles are dispersedly fixed on the conductive layer; or comprises a block conductive material and polystyrene microsphere particles, wherein the polystyrene microsphere particles are dispersedly fixed on the block conductive material.

Further, an adhesion layer is arranged between the substrate and the conducting layer, the adhesion layer is made of titanium, chromium or nickel, and the thickness of the adhesion layer is 1-20 nm.

Further, the substrate is a silicon wafer, a quartz sheet, a glass sheet, a stainless steel sheet, a copper sheet, an aluminum alloy sheet, a molybdenum sheet or a tungsten sheet. The substrate material can also be other hard bulk materials with flat surfaces.

Further, the conductive layer or the block conductive material is made of one or more of gold, silver, platinum, copper, aluminum, chromium, titanium, carbon, tungsten, molybdenum, stainless steel and iron. Or other materials that are electrically conductive and stable in nature and under vacuum conditions.

Further, the thickness of the conductive layer is 1 nm-1 mm. Preferably, the thickness of the conductive layer is 2 nm-500 nm; more preferably, the conductive layer is 95nm thick. The conductive block material with a flat surface can also be directly adopted.

Furthermore, the diameter of the polystyrene microsphere particle is 10 nm-100 μm. Preferably, the diameter of the polystyrene microsphere particle is 10 nm-1 μm; more preferably, the polystyrene microsphere particles are 95nm in diameter.

Further, the polystyrene microsphere particles are replaced by microsphere particles made of carboxyl-polystyrene, amino-polystyrene, macroporous cross-linked polystyrene, polyethylene, polyacrylic acid, polytetrafluoroethylene, gelatin, chitosan, polylactic acid, polybutadiene, polyisoprene, polydimethylsiloxane, polymethyl methacrylate, starch, albumin, silica, alumina or titanium oxide.

Further, the polystyrene microsphere particles are replaced by cubic, cylindrical, octahedral, dodecahedral or irregularly shaped nanoparticles.

The present invention also provides a method of making any of the samples described above, comprising the steps of:

1) plating a conducting layer on a substrate with a clean and smooth surface, or grinding and leveling the surface of a block conducting material and cleaning;

2) and dispersing and fixing the polystyrene microsphere particles on the conductive layer or the bulk conductive material.

Further, the step 1) further comprises a step of cleaning the substrate before plating the conducting layer on the substrate with a clean and flat surface, wherein the cleaning step is to immerse the substrate in an acetone solution for ultrasonic cleaning for 5-10min, then immerse the substrate in an isopropanol solution for ultrasonic cleaning for 5-10min, and blow-dry the substrate with nitrogen after taking out to obtain the substrate with a clean and flat surface. Or other conventional semiconductor process cleaning procedures.

Further, in the step 1), the cleaning method of the surface of the block conductive material is to immerse the block conductive material in an acetone solution for ultrasonic cleaning for 5-10min, then immerse the block conductive material in an isopropanol solution for ultrasonic cleaning for 5-10min, and blow-dry the block conductive material with nitrogen after being taken out. Or other conventional semiconductor process cleaning procedures.

Further, the method for plating the conducting layer on the substrate in the step 1) is a physical plating method or an chemical plating method. The physical coating method is vacuum thermal evaporation, electron beam evaporation, magnetron sputtering coating or ion beam sputtering coating. The chemical coating method is electroplating, electroforming, atomic layer deposition or plasma enhanced chemical vapor deposition.

Further, the method for plating the conductive layer on the substrate in the step 1) is electron beam evaporation.

Further, the step 1) further comprises plating an adhesion layer on the substrate with a clean and flat surface before plating the conductive layer on the substrate with a clean and flat surface. The method for plating the adhesion layer is a physical plating method or an chemical plating method. The physical coating method is vacuum thermal evaporation, electron beam evaporation, magnetron sputtering coating or ion beam sputtering coating. The chemical coating method is electroplating, electroforming, atomic layer deposition or plasma enhanced chemical vapor deposition.

Further, in the step (2), the method for dispersing and fixing the polystyrene microsphere particles is to drop-coat, spin-coat or apply a suspension containing the polystyrene microsphere particles by a pulling method on the surface of the conductive layer or the bulk conductive material.

The invention has the beneficial effects that:

a sample for helium ion microscope imaging quality correction is provided comprising a substrate, a conductive layer and polystyrene microspheroidal particles, or a bulk conductive material and polystyrene microspheroidal particles. The conductive layer or the conductive substrate can transfer positive charges brought by ion incidence, and the influence of charge accumulation on the collection of imaging signals is avoided. As helium ions have strong penetrating power in the polystyrene material, and the average penetrating depth exceeds the size of the polystyrene microsphere, polystyrene microsphere particles are not easy to melt, deform and the like under the irradiation of the helium ions, and the spherical geometry with clear boundaries can sensitively reflect the focusing problems (such as defocusing, astigmatism and the like) of ion beams, thereby being beneficial to the correction of the ion beam focusing imaging quality.

Meanwhile, the method for preparing the sample for the imaging quality correction of the helium ion microscope is simple in step, low in process requirement and suitable for mass production.

Drawings

FIGS. 1(a) and (b) are schematic structural illustrations of two samples of the present invention for helium ion microscope imaging quality correction;

FIG. 2 shows the imaging results of the polystyrene microspheres under 100K magnification in the presence of (a) clear focusing, (b) out-of-focus, and (c) astigmatism in a helium ion microscope;

FIG. 3 is a topographical image of polystyrene microsphere particles of the present invention before (a) irradiation and after (b) continuous irradiation for 2min with a focused high-energy helium ion beam of 30keV energy.

In the figure, 1-substrate, 2-conductive layer, 3-polystyrene microspheroidal particle, 4-bulk conductive substrate.

Detailed Description

In order to better explain the invention, the technical scheme in the embodiment of the invention is further described by combining the drawings in the embodiment.

Example 1

The Polystyrene microspheres used in this example were AGS130-1 Polystyrene latex particles from Agar Scientific Inc. which were Polystyrene in suspension, having an average diameter of about 95. + -.21 nm, and dispersed in pure water at a concentration of about 0.1% w/v.

The sample preparation method for helium ion microscope imaging quality correction is as follows:

1) preparing a silicon wafer substrate 1: a silicon wafer (manufactured by Suzhou Shajiu semiconductor Co., Ltd.) having a size of 10X 10mm and a thickness of 400 μm was immersed in an acetone solution, ultrasonically cleaned for 10min, then immersed in an isopropyl alcohol solution, ultrasonically cleaned for 10min, taken out, and then blow-dried with nitrogen gas to obtain a silicon wafer substrate 1.

2) Plating a titanium adhesion layer on a silicon wafer substrate 1: and (3) evaporating a titanium adhesion layer on the silicon wafer substrate 1 by using an electron beam evaporation coating machine (AdNaNotek, EBS-150) for enhancing the adhesive force between the gold film and the silicon wafer substrate 1. The thickness of the titanium adhesive layer is 5nm, the vacuum degree of evaporation is 5 multiplied by 10^-6Torr, the deposition rate was 0.5A/s.

3) Plating a gold film on the titanium adhesion layer: plating a gold film conductive layer 2 on the surface of the titanium adhesion layer by using an electron beam evaporation coating machine (AdNaNotek, EBS-150), wherein the thickness of the gold film is 95nm, and the evaporation vacuum degree is 5 multiplied by 10^-6Torr, the deposition rate was 1A/s.

4) Dispersing and fixing polystyrene microsphere particles 3 on a gold film: about 30mm on the surface of the gold film²And dripping 50 mu L of polystyrene microsphere particle suspension with the concentration of 0.1% w/v into the area, standing and drying for 0.5 hour at room temperature, and then purging for 1min by using nitrogen to prepare a sample for the imaging quality correction of the helium ion microscope. The method has simple steps and low process requirements, and is suitable for mass production.

The structure of the sample prepared in this example is shown in fig. 1(a), and includes a silicon wafer substrate 1, a titanium adhesion layer, a gold thin film conductive layer 2, and polystyrene microsphere particles 3; a silicon wafer substrate 1 supporting the whole structure is sequentially covered with a titanium adhesion layer and a gold thin film conducting layer 2, and polystyrene microsphere particles 3 are dispersedly fixed on the gold thin film conducting layer 2.

Sample performance testing for helium ion microscope imaging quality correction:

the polystyrene microsphere particles on the mass-corrected sample prepared in this example were scanned and imaged with a focused helium ion beam using a helium ion microscope (Zeiss, ORION Nanofab) (helium ion acceleration voltage 30kV, beam 2pA, number of scanned pixels 1024 × 1024, residence time 1 μ s). The gold thin film conducting layer can transfer positive charges brought by ion incidence, and the influence of charge accumulation on the collection of imaging signals is avoided. The ion beam focusing quality can be judged according to the imaging result: if the edge of the microspherical particle is fuzzy (as shown in fig. 2 (b)), the defocusing problem is shown, and the focusing focal length of the ion beam needs to be adjusted until the edge of the particle is clear; if the microspheroidal particle is elliptical in shape, stretched in a certain direction (as shown in fig. 2 (c)), the problem of astigmatism is illustrated, and the ion optical system astigmatism correction is required until the microspheroidal particle is perfectly circular. Therefore, the spherical polystyrene particles with clear boundaries can sensitively reflect the ion beam focusing problem, and are beneficial to correcting the focusing imaging quality. Fig. 2(a) shows the imaging result of the polystyrene microsphere particles with clear focus after ion beam focusing imaging quality correction: the image obtained under the magnification of 100K is clear and has no distortion, and the helium ion microscope after correction is proved to have good focusing state and higher imaging quality.

FIG. 3 shows the comparison of the morphology of polystyrene microsphere particles before (a) irradiation and after (b) continuous irradiation for 2min by a focused high-energy helium ion beam with an energy of 30keV under a helium ion microscope (Zeiss, ORION Nanofab), which shows that the morphology of the polystyrene microsphere particles is not changed greatly. Because helium ions have strong penetrating power in the polystyrene material, and the average penetrating depth exceeds the size of the polystyrene microsphere, the polystyrene microsphere particles are not easy to melt, deform and the like under the irradiation of the helium ions, and more sufficient operation time can be provided for the correction process of ion beam focusing imaging quality.

Example 2

The Polystyrene microspheres used in this example were from AGS130-1 Polystyrene latex particles suspension produced by Agar Scientific, with the microsphere particles being Polystyrene and having an average diameter of about 95. + -.21 nm, dispersed in purified water at a concentration of about 0.1% w/v.

The sample preparation method for helium ion microscope imaging quality correction is as follows:

1) preparation of a bulk conductive substrate 4: and (2) grinding and polishing the surface of a stainless steel sheet with the size of 10 multiplied by 10mm and the thickness of 1mm by using sand paper, washing the surface by using water, immersing the surface into an acetone solution, carrying out ultrasonic cleaning for 10min, immersing the surface into an isopropanol solution, carrying out ultrasonic cleaning for 10min, taking out the surface, and drying the surface by using nitrogen to obtain the block conductive substrate 4.

2) Dispersing and fixing polystyrene microsphere particles 3 on a bulk conductive substrate 4: about 30mm on the surface of the stainless steel sheet²Dripping 50 mu L of polystyrene microsphere particle suspension with the concentration of 0.1% w/v into the area, and carrying out room temperature treatmentAnd (3) standing and drying for 0.5 hour, and then purging with nitrogen for 1min to prepare a sample for imaging quality correction of the helium ion microscope. The method has simple steps and low process requirements, and is suitable for mass production.

The sample structure prepared in this example is shown in fig. 1(b), and comprises a bulk conductive substrate 4 and polystyrene microspheroidal particles 3; the polystyrene microsphere particles 3 are dispersed and fixed on a bulk conductive substrate 4 supporting the whole structure.

Sample performance testing for helium ion microscope imaging quality correction:

the polystyrene microsphere particles on the mass-corrected sample prepared in this example were scanned and imaged with a focused helium ion beam using a helium ion microscope (Zeiss, ORION Nanofab) (helium ion acceleration voltage 30kV, beam 2pA, number of scanned pixels 1024 × 1024, residence time 1 μ s). The bulk conductive substrate can transfer positive charges caused by ion incidence, and the influence of charge accumulation on the collection of imaging signals is avoided. The ion beam focusing quality can be judged according to the imaging result: if the edge of the microspherical particle is fuzzy (as shown in fig. 2 (b)), the defocusing problem is shown, and the focusing focal length of the ion beam needs to be adjusted until the edge of the particle is clear; if the microspheroidal particle is elliptical in shape, stretched in a certain direction (as shown in fig. 2 (c)), the problem of astigmatism is illustrated, and the ion optical system astigmatism correction is required until the microspheroidal particle is perfectly circular. Therefore, the spherical polystyrene particles with clear boundaries can sensitively reflect the ion beam focusing problem, and are beneficial to correcting the focusing imaging quality.

While the invention has been described with respect to a preferred embodiment, it will be understood by those skilled in the art that the foregoing and other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention. Those skilled in the art can make various changes, modifications and equivalent arrangements, which are equivalent to the embodiments of the present invention, without departing from the spirit and scope of the present invention, and which may be made by utilizing the techniques disclosed above; meanwhile, any changes, modifications and variations of the above-described embodiments, which are equivalent to those of the technical spirit of the present invention, are within the scope of the technical solution of the present invention.