JP2008235192A - Manufacturing method of microgrid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a microgrid having a pore part of a desired pore size at a desired location. <P>SOLUTION: This is the manufacturing method of a microgrid 1 which is used for a test piece support at the time of observation by an electron microscope and has a grid mesh 10 and a thin film 20 having a pore installed on the grid mesh. The manufacturing method comprises a process of arranging a liquid drop 50 consisting of a liquid 50a on a substrate 30 by injecting a prescribed amount of liquid 50a at the prescribed location on the substrate 30 by using a liquid drop injection method, a process of arranging a thin-film material 20a between the liquid drops 50 arranged on the substrate 30, a process in which the thin film material 20a and the liquid drops 50 are dried and the liquid drops 50 are removed by evaporation, and the thin film 20 having pore parts 21 at the location corresponding to these is formed, a process to separate the thin film 20 from the substrate 30, and a process to install the thin film separated from the substrate 30 on the grid mesh 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a microgrid.

  In general, electron microscopes having higher resolution than optical microscopes are used in a wide range of fields such as physics, chemistry, engineering, medicine, and biology. In particular, in the engineering field, semiconductor devices are being highly integrated and miniaturized, and an electron microscope is used as a means for analyzing the operation and failure of such semiconductors. An electron microscope irradiates a sample with an electron beam and obtains an image from electrons transmitted through the sample or reflected from the sample surface. The transmission electron microscope can observe the structure of the sample using the transmitted electrons. These are broadly classified into scanning electron microscopes that can observe the surface shape and the like of a sample using reflected electrons.

  When observing using such an electron microscope, it is extremely important to support the sample so that it does not move (drift). Specifically, since observation using an electron microscope is generally performed with high resolution and high magnification, that is, a narrow observation range (field of view), if the sample moves, a great deal of effort is required to keep the sample within the observation range. Is required and workability is reduced.

  The drift of the sample as described above is caused by the stage holding the sample being distorted due to thermal reasons or the like, causing a slight inclination, the sample being thermally unstable by the electron beam, or the sample by the electron beam. Occurs due to charge (charge-up) or the like. In order to prevent such sample drift, it is effective to use a microgrid.

  A microgrid is a thin film having holes, which is attached to a ring-shaped metal ring having a net-like (mesh) part, so that the sample can be supported (held) by the holes. . About the manufacturing method, what is described in the nonpatent literature 1 is known.

In order to manufacture a microgrid by the method described in Non-Patent Document 1, first, the slide glass subjected to water repellency treatment is cooled to a temperature slightly below the dew point temperature. Next, the slide glass is left in the atmosphere, and water vapor in the atmosphere is condensed (condensed) on the slide glass, and water droplets are arranged on the slide glass. Next, the thin film material solution is spread and spread between the water droplets on the slide glass, after which the solvent is volatilized and the water droplets are evaporated to form a thin film. Then, a hole corresponding to the portion where the water droplet was disposed is formed in this thin film. Next, this thin film is peeled off from the slide glass in water, and the thin film is stuck on the grid mesh by scooping up with the grid mesh.
Edited by Kentaro Asakura and Yasuhisa Hirohata, “Ultra Microtome Q & A for Electron Microscope Researchers”, Agne Jofusha, September 1999, p. 90-91

  However, in the above method, since water droplets are arranged on the slide glass by condensing water vapor, as described in Non-Patent Document 1 that it is easy to create around June, temperature and humidity There is a problem that the microgrid cannot be manufactured because the constraining conditions are severe and no condensation occurs depending on the conditions. Moreover, skill is required to appropriately set conditions such as temperature, and it is difficult for beginners to manufacture a good microgrid by the above method.

  In addition, since water droplets are distributed by condensation in the above method, the size and position of the water droplets are random, and therefore the hole formed according to the water droplets has a random pore size and arrangement. There is. In this way, if the hole diameter and position of the hole are random, it is impossible to observe because the hole suitable for sample support is not formed, and even if it is formed, it takes a lot of labor to find this And the like.

  The present invention has been made in view of the above-mentioned problems of the prior art, and provides a manufacturing method capable of easily manufacturing a microgrid having a hole having a desired hole diameter at a desired position. Objective.

The production method of the present invention is a method for producing a microgrid, which is used for supporting a sample during observation with an electron microscope, and includes a grid mesh and a thin film having a hole provided on the grid mesh. And
A step of discharging a predetermined discharge amount of liquid to a predetermined position with respect to the substrate by using a droplet discharge method, and disposing the droplet made of the liquid on the substrate; Disposing a thin film material between droplets, drying the thin film material and the droplets, removing the droplets by evaporation, and forming a thin film having a hole at a position corresponding to the droplets And a step of peeling the thin film from the substrate, and a step of providing the thin film peeled off from the substrate on a grid mesh.

  In this way, since the droplets are placed on the substrate by the droplet discharge method, the restriction conditions such as temperature and humidity when placing the droplets are much higher than the method of placing the water droplets due to condensation. To be relaxed. Accordingly, the microgrid can be manufactured under ordinary conditions without being restricted by a skilled person without being largely restricted by temperature, humidity, and the like.

  Further, since the liquid is discharged at a predetermined position with respect to the substrate at a predetermined discharge amount, a droplet having a desired size can be arranged at a desired position on the substrate. In addition, when the thin film material and the droplet are dried after the thin film material is disposed between the droplets and the droplets are evaporated, the thin film material is not disposed in the droplet portion. A thin film having a hole having a hole diameter corresponding to the size of the droplet is formed. Here, since the position and the hole diameter of the droplet are set as desired, the formed thin film has a hole having a desired hole diameter at a desired position. Therefore, it is possible to manufacture a microgrid in which a hole having a hole diameter suitable for the sample is formed at a position suitable for observation.

The electron microscope is a transmission electron microscope, and the thin film is preferably formed of a material that does not transmit an electron beam.
In this way, a microgrid that can be used in a transmission electron microscope can be manufactured.

The thin film is preferably formed by curing a resin material.
In this way, the thin film material can be disposed, for example, by flowing and spreading the resin material solution between the droplets on the substrate, and the thin film material (resin material) can be easily cured by drying. . Therefore, these steps can be performed by a simple method, and a microgrid can be manufactured efficiently.

The liquid discharged by the droplet discharge method is preferably water.
In this way, water is a well-known substance, is inexpensive and easy to use, and therefore can be easily applied to the droplet discharge method.

In addition, it is preferable that the liquid discharged by the droplet discharge method is a mixture of water and an additive, and the additive makes the saturated vapor pressure of the mixture lower than the saturated vapor pressure of water.
In this way, the saturated vapor pressure of the liquid (mixture) is made lower than the saturated vapor pressure of water by the additive, so that the drying time of the droplets can be made longer than the drying time of the water droplets. Therefore, it is possible to reduce the change in the volume of the droplets due to drying during the time until the thin film material is disposed, and thus it is possible to form a hole having a desired hole diameter. Further, for example, when a minute droplet is arranged, it is prevented that the droplet evaporates and is removed during the time until the thin film material is disposed, and therefore, a hole corresponding to the minute droplet, that is, A hole having a minute hole diameter can be formed. In addition, since the restriction on the time from when the droplet is placed to when the thin film material is placed is relaxed, workability can be improved.

Further, the step of discharging the liquid may include a step of discharging the liquid with a first discharge amount and a step of discharging the liquid with a second discharge amount different from the first discharge amount.
According to this configuration, the droplet corresponding to the first discharge amount and the droplet corresponding to the second discharge amount are arranged on the substrate, and the sizes thereof are different from each other corresponding to each discharge amount. It will be a thing. Therefore, it is possible to form a microgrid having holes having different hole diameters corresponding to these droplets. Further, since the different hole diameters can be set to desired hole diameters, for example, when different samples are observed simultaneously, a microgrid having a hole diameter suitable for each sample can be manufactured.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, using an example in which the present invention is applied to a method for manufacturing a microgrid for a transmission electron microscope. It should be noted that the technical scope of the present invention is not limited to the following embodiments, and appropriate modifications can be made without departing from the spirit of the present invention. In the drawings used for the following description, the scale of each member is appropriately changed in order to make each member a recognizable size.

First, prior to the description of the manufacturing method of the present invention, the configuration of the microgrid 1 obtained by the manufacturing method of the present invention will be described with reference to FIG.
Fig.1 (a) is a top view which shows the structure of the microgrid 1, FIG.1 (b) is XX arrow sectional drawing of Fig.1 (a). As shown in FIG. 1B, the microgrid includes a metal grid (grid mesh) 10 and a plastic thin film (thin film) 20 attached on the metal grid 10. The size of the microgrid 1 is, for example, about 3 mm in diameter and about 25 μm in thickness.

  The metal grid 10 is made of copper (Cu), platinum (Pt), molybdenum (Mo), stainless steel (SUS), or the like. As shown in FIG. 1A, linear bone portions are arranged vertically and horizontally. The mesh portion 11 and the outer frame portion 12 are provided. Such metal grids 10 are commercially available in various sizes and materials, and commercially available products can be used depending on the sample. Further, as shown in FIG. 1A, the plastic thin film 20 has a large number of hole portions 21 arranged vertically and horizontally, and the size of the hole portions 21 is set to a predetermined hole diameter corresponding to the sample. Is.

  When the sample is observed using the microgrid 1 described above, the sample can be prevented from drifting (moving) by being held (supported) by fitting the sample into the hole 21. ing.

  Next, an embodiment of a method for manufacturing the microgrid 1 according to the present invention will be described using the method for manufacturing the microgrid 1 as an example.

[First Embodiment]
FIG. 2 is a diagram for explaining the first embodiment of the present invention. First, the glass slide (substrate) is washed thoroughly with water, and then subjected to water repellency treatment (liquid repellency treatment). Examples of the water repellent treatment include the following methods. First, the slide glass is washed thoroughly with water, then washed with an organic solvent such as tetrachloromethane (CCl ₄ ), and dried by heating. Then, the slide glass is immersed in a 0.03% aqueous solution of a cationic surfactant for about 10 to 30 minutes, and then the slide glass is thoroughly washed with water.

  Next, as shown in FIG. 2A, a predetermined discharge amount (for example, 800 nl to 1 pl) at a predetermined position from the inkjet head 40 to the slide glass 30 using the inkjet method (droplet discharge method). Then, the liquid 50 a is discharged, and the droplet 50 is placed on the slide glass 30. At this time, since the slide glass 30 is subjected to the liquid repellency treatment, the droplets 50 are prevented from spreading on the slide glass 30. As described above, since the liquid 50a is ejected by the ink jet method and the droplet 50 is arranged on the slide glass 30, the restriction condition such as temperature and humidity when the droplet 50 is arranged arranges the water droplet due to dew condensation. Compared to the method, it is greatly relaxed. Further, since the liquid 50 is discharged at a predetermined discharge position with a predetermined discharge amount, the droplet 50 on the slide glass 30 is disposed at a desired position and has a desired size.

  In the present embodiment, water is used as the liquid 50a to be discharged. When water is discharged in this way, water is a substance whose liquid properties are well known, is inexpensive and easy to use, and can therefore be easily applied to the droplet discharge method.

  Next, as shown in FIG. 2 (b), a plastic dilute solution (thin film material) 20 a is poured and spread between the water droplets 50 on the slide glass 30 on which the water droplets (droplets) 50 are arranged. In the case of the microgrid 1 for a transmission electron microscope as in this embodiment, it is necessary that a thin film (plastic thin film) to be described later does not transmit an electron beam. Then, as in the conventional case, a triaole solution (resin material) dissolved in ethyl acetate is used. Thus, by using a triahole solution (resin material) as the thin film material 20a, the thin film material 20a can be disposed on the slide glass 30 by a simple method such as spreading and spreading.

  Next, as shown in FIG. 2C, a drying process is performed on the surface of the slide glass 30 where the water droplet 50 is disposed, and the water droplet 50 is evaporated and removed, and the solvent of the plastic dilute solution 20a is evaporated to remove the plastic film 20. Form. At this time, since the plastic dilute solution 20a is not disposed in the portion where the water droplet 50 is disposed, the hole portion 21 having a hole diameter corresponding to the size of the water droplet 50 is provided at the position where the water droplet 50 is disposed. It is formed. Further, since the water droplet 50 is disposed at a desired position and has a desired size, the hole 21 is formed at a desired position and has a desired hole diameter. Moreover, since the triahole solution (resin material) is used as the thin film material 20a, the plastic thin film 20 can be formed by curing the resin material by drying. Thus, the plastic thin film 20 provided with the hole 21 is formed.

  Next, the slide glass 30 on which the plastic thin film 20 is formed is immersed in an aqueous solution of an emulsifier (trade name Perex OTP, manufactured by Kao Corporation) such as dialkylsulfosuccinic acid for about 3 to 10 minutes, and then washed with water. Then, it is slowly inserted into a petri dish filled with water at an angle of 20 ° or less. By doing so, the plastic thin film 20 is lifted by buoyancy and peeled off from the slide glass 30 as shown in FIG. And as shown in FIG.2 (e), the plastic thin film 20 which floated is scooped up on the metal grid 10, and is affixed on the said metal grid. The metal grid 10 is commercially available as described above, and a metal grid 10 having a size and material corresponding to the sample is prepared.

  Next, the plastic thin film 20 is dried by heating with an electric heater, and the plastic thin film 20 is sufficiently cured, thereby increasing the strength and fixing the plastic thin film 20 to the metal grid 10, as shown in FIG. 2 (f). A microgrid 1 is manufactured.

  As described above, according to the manufacturing method of the present embodiment, the constraints such as the temperature and humidity when the water droplet 50 is formed and arranged are greatly relaxed. Both can produce the microgrid 1. In addition, since the droplet 50 having a desired size is arranged at a desired position on the slide glass 30 by using the ink jet method, the microgrid 1 having the hole 21 having a desired hole diameter at the desired position. Can be manufactured. Since water is used as the liquid 50a and a triahole solution (resin material) is used as the thin film material 20a, the plastic thin film 20 can be easily formed. Therefore, the microgrid 1 can be manufactured efficiently.

  Since the microgrid 1 formed by the manufacturing method as described above has a hole 21 having a hole diameter suitable for the sample formed at a desired position, the sample can be reliably supported in the hole 21 and the sample is Drifting (moving) is prevented. Therefore, it becomes easy to fit the sample within the observation range. In addition, since the sample can be satisfactorily arranged in any hole, the trouble of searching for a position suitable for the sample arrangement can be saved. Thus, when the microgrid 1 according to the present invention is used, the sample can be efficiently observed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the first embodiment, water is used as the liquid 50a to be discharged. In the second embodiment, a liquid (mixture) 50a obtained by adding glycerin (additive) to water at a concentration of 0.1% by weight is used. Here, the saturated vapor pressure of this mixture (liquid) 50a can be made lower than the saturated vapor pressure of water by adding glycerin to water. By using such a liquid 50a, the droplet 50 formed by discharging it has a longer drying time than water.

  As the additive, in addition to the glycerin, polyalcohols such as ethylene glycol, diethylene glycol, propylene glycol, and hexanediol can be used. Further, the amount of these additives can be selected so that the concentration is 0.01 to several tens of weight% depending on the type of additive.

  According to the manufacturing method of the present embodiment, the drying time of the droplet 50 is set longer than that of water. Therefore, the droplet 50 does not reach the time from the placement of the droplet 50 until the plastic dilute solution 20a is spread and spread. Reduction in volume due to evaporation is mitigated. Therefore, the hole 21 having a desired hole diameter can be formed. Further, for example, even when a minute droplet 50 is disposed, the evaporation of the droplet 50 and the removal thereof are reduced, so that the hole portion 21 having a minute hole diameter can be formed. In addition, since the restriction on the time from the placement of the droplet 50 until the plastic dilute solution 20a is poured and spread is relaxed, workability can be improved.

[Third Embodiment]
FIG. 3 is a diagram for explaining the outline of the third embodiment of the present invention. In this embodiment, first, as shown in FIG. 3A, liquids 51a and 52a are ejected by an ink jet method onto the slide glass 30 that has been thoroughly washed with water, thereby arranging the liquid droplets 51 and 52. Here, in the first embodiment and the second embodiment, the liquid 50a (see FIG. 2) is ejected at a constant ejection amount. However, in the present embodiment, the liquid 51a is ejected at the first ejection amount and the droplet 51 is ejected. And the liquid 52a is ejected at a second ejection amount different from the first ejection amount to dispose the droplets 52. Since the first discharge amount and the second discharge amount are different from each other, the droplet 51 and the droplet 52 are droplets having different sizes.

  Next, as shown in FIG. 3 (b), the plastic dilute solution 20a is spread and spread between the droplets 51 and 52 on the slide glass 30, and the slide glass 30 is dried as shown in FIG. 3 (c). And the droplets 51 and 52 are removed by evaporation, and the plastic film 20 is formed by evaporating the solvent of the plastic dilute solution 20a. At this time, a hole 22 having a hole diameter corresponding to the droplet 51 is formed at the position where the droplet 51 is disposed, and the position corresponding to the droplet 52 is disposed at the position where the droplet 52 is disposed. A hole 23 having a hole diameter is formed. Here, since the droplet 51 and the droplet 52 are droplets of different sizes, the hole 22 and the hole 23 are formed in different sizes (hole diameters) corresponding to the respective sizes. The

  Thereafter, in the same manner as in the first embodiment, as shown in FIG. 3D, the microgrid 1 including the hole 22 and the hole 23 having different hole diameters is manufactured. Since the microgrid 1 manufactured in this way includes a hole 22 having a desired hole diameter and a hole 23 having a different desired hole diameter, for example, two different types of samples are observed simultaneously. Even in this case, each sample is supported (held) without drifting (moving) by forming the holes 22 and 23 having a diameter suitable for each sample. Therefore, observation can be performed efficiently.

  As described above, in the method of manufacturing the microgrid 1 according to the present invention, the constraints such as the temperature and humidity when the droplets 50 are arranged are remarkably relaxed. If not, the microgrid 1 can be manufactured. In addition, since a predetermined discharge amount of liquid is discharged to a predetermined position, the microgrid 1 having a hole size of a desired size at a desired position can be manufactured.

  In the first embodiment, the holes 21 are aligned in the vertical and horizontal directions. However, they may be arranged in a radial pattern or a zigzag pattern, for example. Further, the arrangement interval of the holes may be changed. In the third embodiment, the hole portions 22 and 23 having two types of hole diameters are formed. However, three or more types of holes may be formed. For example, hole portions in which the hole diameters are systematically changed may be formed. In this case, even if the hole diameter suitable for the sample is not known in advance, it is possible to find the hole diameter suitable for the sample by arranging the sample in a plurality of hole diameters, and perform observation effectively. be able to.

  Further, when the plastic thin film 20 is pasted on the metal grid (grid mesh) 10, an adhesive such as mesh cement (trade name) is applied on the metal grid 10 in advance, and the metal grid 10 and the plastic thin film are then applied. 20 may be in close contact with each other, or carbon may be vapor-deposited on the plastic thin film 20 to be reinforced to enhance durability against electron beam irradiation.

(A), (b) is a figure which shows the structure of the microgrid based on this invention. (A)-(f) is a figure explaining the manufacturing method of this invention. (A)-(d) is a figure explaining another manufacturing method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Micro grid, 10 ... Metal grid (grid mesh), 20 ... Plastic thin film (thin film), 20a ... Thin film material, 21, 22, 23 ... Hole, 30 ... Slide glass (substrate), 40 ... inkjet head, 50, 51, 52 ... droplet, 50a, 51a, 52a ... liquid

Claims (6)

A method for producing a microgrid comprising a grid mesh and a thin film having a hole provided on the grid mesh, which is used for supporting a sample during observation with an electron microscope,
A step of discharging a predetermined discharge amount of liquid to a predetermined position with respect to the substrate by using a droplet discharge method, and disposing the droplet made of the liquid on the substrate; Disposing a thin film material between droplets, drying the thin film material and the droplets, removing the droplets by evaporation, and forming a thin film having a hole at a position corresponding to the droplets And a step of peeling the thin film from the substrate, and a step of providing the thin film peeled from the substrate on a grid mesh.   The method of manufacturing a microgrid according to claim 1, wherein the electron microscope is a transmission electron microscope, and the thin film is formed of a material that does not transmit an electron beam.   The method for manufacturing a microgrid according to claim 2, wherein the thin film is formed by curing a resin material.   The method for manufacturing a microgrid according to claim 1, wherein the liquid discharged by the droplet discharge method is water.   The liquid discharged by the droplet discharge method is composed of a mixture of water and an additive, and the additive makes the saturated vapor pressure of the mixture lower than the saturated vapor pressure of water. The manufacturing method of the microgrid as described in any one of claim | item 1 -3.   The step of discharging the liquid includes a step of discharging the liquid with a first discharge amount, and a step of discharging the liquid with a second discharge amount different from the first discharge amount. 6. The method for producing a microgrid according to any one of 5 above.

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