WO2012161317A1 - Method of manufacturing base substance disposed with fine hole, and base substance disposed with fine hole - Google Patents

Abstract

Provided is a method of manufacturing a base substance having a fine hole, including: forming a first modification portion and a second modification portion, which have etch selectivity, by performing scanning of a focus of a first laser beam having the time width of not more than picosecond order, inside the base substance; forming a first remodification portion, in which a modification state of a first part of the first modification portion is denatured, and a second remodification portion, in which a modification state of a first part of the second modification portion is denatured, by performing scanning of a focus of a second laser beam having the time width of not more than picosecond order so that the first part of the first modification portion and the first part of the second modification portion overlap with each other; enhancing the etching resistance of the first remodification portion and the second remodification portion by heating the first remodification portion and the second remodification portion; and forming a fine hole in the base substance by removing the first modification portion and the second modification portion other than the first remodification portion and the second remodification portion with etching.

Description

Manufacturing method of substrate having micropores, and substrate having micropores

The present invention relates to a method for producing a substrate having micropores, and a substrate having micropores. This application claims priority based on Japanese Patent Application No. 2011-117153 filed in Japan on May 25, 2011, the contents of which are incorporated herein by reference.

As a method for forming a fine structure on a substrate (working material), the following method can be given as a conventional method.
As the first method, there is a fine structure forming method using a photolithography technique. First, a mask is formed on the surface of the material, and then a wet structure or dry etching is performed to form a fine structure on the substrate surface (see Patent Document 1).

Further, as a second method, a laser having a pulse width of picosecond order or less is focused on the substrate, a structurally modified portion is formed in the focused portion, and then a high aspect trench by wet etching with hydrofluoric acid or the like, A method of forming a microscopic hole or a structure branched or bent in the lateral direction is known (see Patent Document 2).

However, in the first photolithography described above, fine holes with a hole diameter of several hundred nanometers (nm units) are formed inside a processing material such as quartz glass, and a fine structure is formed in the fine holes. Is generally difficult.

Further, according to the method of combining the pulse laser and the wet etching described in the second, it is possible to form a fine hole in the substrate, but the hole diameter is on the order of microns (μm unit) of at least several microns. The main processing method is to form micropores, and it is difficult to form micropores with a nano-order pore diameter (to achieve a nano-order processing width).

JP 2006-111525 A JP 2005-219105 A

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a substrate having micropores having a pore size of the order of nanometers, and to provide the substrate.

The substrate manufacturing method (also referred to as “first manufacturing method”) according to the first aspect of the present invention is a method for manufacturing a substrate having micropores, and has a time width within the picosecond order within the substrate. By scanning the focal point of the first laser beam, the first modified portion and the second modified portion having etching selectivity are formed, and the first portion of the first modified portion and the second modified portion are formed. The modified state of the first portion of the first modified portion by scanning the focal point of the second laser light having a time width of picosecond order or less inside the base so as to overlap each first portion. Forming a first re-reformation part modified and a second re-reformation part modified in the reformed state of the first part of the second reforming part, the first re-modification part and the second re-reformation part The first re-reformer and the second re-reformer by heating the mass part The etching resistance of the first reforming part and the second reforming part other than the first re-modification part and the second re-modification part are removed by etching, and micropores are formed in the substrate. Form.

In the first manufacturing method, using the first laser beam, a first modified portion and a second modified portion having a nano-order pore diameter are formed in a region including a region in which micropores are formed in the substrate. Forming and using the second laser light, a first re-modification part and a second re-modification in which the reformed state is modified in each first part of the first reforming part and the second reforming part Forming part. The formed first re-modification part and second re-modification part become regions that are difficult to be etched by increasing the etching resistance by heat treatment. After increasing the etching resistance of the first re-modified part and the second re-modified part by the heat treatment, the first re-modified part and the second re-modified part among the first modified part and the second modified part. By preferentially etching the portion excluding the modified portion, it is possible to form micropores having a pore size in the nano order in the substrate.

The substrate manufacturing method (also referred to as “second manufacturing method”) of the second aspect of the present invention is a method for manufacturing a substrate having micropores, and has a time width within the picosecond order within the substrate. The focal point of the second laser beam is scanned to form a structurally altered portion with reduced etching resistance of the substrate, and within the base of the picosecond order or less so as to partially overlap the structurally altered portion. By scanning the focal point of the first laser beam having a time width, a third modified portion and a fourth modified portion having etching selectivity are formed in a region that does not overlap the structurally altered portion in the scanned region. Forming a third re-modification portion and a fourth re-modification portion in which the etching resistance of the structural alteration portion is changed in a region overlapping the structural alteration portion in the scanned region, Three re-reformers, the fourth By heating the material portion and the structurally modified portion, the etching resistance of the third re-modified portion, the fourth re-modified portion and the structurally-modified portion is increased, and the third re-modified portion, By removing the third modified portion and the fourth modified portion other than the four re-modified portions and the structurally modified portion by etching, micropores are formed in the substrate.

The second manufacturing method uses the second laser beam to form the structurally altered portion in a region adjacent to the region in the substrate where the micropores are formed, and partially overlaps the structurally altered portion. As described above, the focal point (condensing area) of the first laser beam is scanned in the base to form the third modified part and the fourth modified part in a region adjacent to the structurally altered part, A third re-modification part and a fourth re-modification part having different etching resistance are formed in the first part of the structurally altered part. The formed third re-formation part and the fourth re-reformation part, and the structural alteration part left without the formation of the third re-reformation part and the fourth re-reformation part are performed by heat treatment. The etching resistance is increased, and the region becomes difficult to be etched. After increasing the etching resistance of the third re-modified part, the fourth re-modified part and the structurally altered part by the heat treatment, from the third re-modified part, the fourth re-modified part and the structurally altered part In addition, by preferentially or selectively etching the third modified portion and the fourth modified portion, it is possible to form micropores having a minor axis in the nano order in the substrate. Further, the major diameter of the fine pores formed by forming the structurally altered portion and increasing the etching resistance of the third re-modified portion, the fourth re-modified portion and the structurally altered portion. Can be made smaller, and it is easy to form the major axis so as to have a nano-order length.

In the method for manufacturing a substrate according to the first aspect and the second aspect of the present invention, the polarization direction of the first laser beam and the polarization direction of the second laser beam may be different from each other. preferable.
In the first manufacturing method (first aspect), by using laser beams having different polarization directions, the modified state in each first part of the first modified part and the second modified part Thus, the first re-modification part and the second re-modification part with improved etching resistance are more easily formed. Further, the etching resistance of the first re-modified part and the second re-modified part can be further enhanced by the subsequent heat treatment. As a result, in the etching process, the unmodified first modified portion and the second modified portion are preferentially or selectively over the first remodified portion, the second remodified portion, and the non-modified portion. Etching can be performed more easily.
In the second manufacturing method (second embodiment), by using laser beams having different polarization directions, the third re-formation part and the fourth re-reformation part formed over the structurally altered part. The etching resistance is made higher than the etching resistance of the third modified portion and the fourth modified portion formed adjacent to the structurally altered portion, so that these modified portions are more easily formed. Further, the etching resistance of the third re-modified part and the fourth re-modified part can be further enhanced by the subsequent heat treatment. As a result, in the etching process, the third modified part and the fourth modified part are given priority over the third re-modified part and the fourth re-modified part, the structurally altered part, and the non-modified part. The selective etching can be performed more easily.

In the method for manufacturing a substrate according to the first aspect and the second aspect of the present invention, an angle formed between the scanning direction of the first laser light and the polarization direction of the first laser light is greater than 88 ° and 90 °. It is preferable that the angle is not more than °.
By adjusting the range of the angle to be larger than 88 ° and not larger than 90 °, it can be easily formed so that the diameter of the modified portion becomes a nano-order length.

In the method for manufacturing a substrate according to the first aspect of the present invention, the first re-modification part and the second re-modification part are arranged along the longitudinal direction of the first reforming part and the second reforming part. It is preferable to form.
According to this manufacturing method, the re-reformer (first re-reformer and second re-reformer) formed in the longitudinal direction of the reformer (first reformer and second reformer) The etching resistance can be increased by a subsequent heat treatment to make the region difficult to be etched. That is, the first portion of the modified portion formed by the first laser beam is actually etched by rewriting the second portion with the second laser beam over the longitudinal direction of the modified portion. The area of the reforming part can be narrowed. As a result, the diameter of the fine holes finally formed by the etching can be reduced in the longitudinal direction of the modified portion.

In the method for manufacturing a substrate according to the second aspect of the present invention, the third re-modification part and the fourth re-modification part are provided along the longitudinal direction of the third reforming part and the fourth reforming part. It is preferable to form.
According to this manufacturing method, when forming the modified portion (the third modified portion and the fourth modified portion) with the first laser light, the focal point (condensed area) of the first laser light is partially The modified portion is formed by scanning over the structurally modified portion formed in advance by the second laser beam, and the reformed portion (third reformed portion is formed along the longitudinal direction of the modified portion. And a fourth re-modification part). That is, the region where the modified portion is formed can be narrowed in the longitudinal direction.
As a result, the hole diameter of the fine holes finally formed by etching can be reduced in the longitudinal direction of the modified portion.

In the substrate manufacturing method according to the first aspect and the second aspect of the present invention, an angle formed between the scanning direction of the second laser light and the polarization direction of the second laser light is 0 ° or more and 88 ° or less. It is preferable.
By setting the angle range to 0 ° or more and 88 ° or less, periodic components that may be included in the re-modification part can be formed to intersect with the scanning direction of the second laser light. That is, it is possible to form a periodic component that may be included in the re-reformation part so as to intersect the longitudinal direction of the reforming part.
By forming the re-modification part so that the periodic component intersects the longitudinal direction of the modification part, the etching resistance of the re-modification part can be more easily increased. As a result, in etching, the difference in etching rate between the modified portion, the re-modified portion, and the structurally altered portion can be increased, and fine holes having a smaller hole diameter can be formed.

In the method for manufacturing a substrate according to the first aspect and the second aspect of the present invention, it is preferable that the irradiation intensity of the first laser light is less than a processing upper limit threshold and is equal to or higher than a processing lower limit threshold.
By setting the irradiation intensity within the above range, the modified portion can be more easily formed so as to have a nano-order pore diameter. As a result, micropores having a nano-order pore diameter can be more easily formed in the substrate.

In the substrate manufacturing method according to the first and second embodiments of the present invention, the heating temperature is preferably not more than a temperature at which the viscosity of the substrate material reaches 10 ^11.7 [poise].
When the re-modified part and the structurally altered part are heated at a temperature in this range, the etching resistance of the re-modified part and the structurally altered part is easily increased. As a result, micropores having a nano-order pore diameter are formed in the substrate.

The substrate according to the third aspect of the present invention is a substrate manufactured by the method for manufacturing a substrate according to the first aspect or the second aspect, wherein the micropore having an opening on the surface of the substrate has a shape of the opening. Is oval and the minor axis of the opening is 1 μm or less.
By forming the short diameter of the opening portion of the fine holes so as to have a nano-order or sub-micron order length, it is possible to restrict fine particles having a size of 1 μm or more from entering the fine holes. By utilizing this, when the micropore of the present invention is applied to, for example, a microfluidic chip, microorganisms or microparticles having a size of about 1 to 20 μm contained in the fluid can be captured at the opening of the micropore. .

According to the method for producing a substrate having micropores of the present invention, a substrate in which micropores having a nano-order pore diameter are formed inside the substrate can be produced.

According to the substrate of the present invention, fine particles can be adsorbed at the opening (the first end portion of the micropore) of the micropore that opens (exposes) the surface of the substrate. That is, when a suction device is installed at the second end of the fine hole penetrating the inside of the substrate and a fluid containing fine particles larger than the fine hole diameter is sucked into the fine hole from the first end, Since fine particles larger than the pore diameter cannot enter the fine holes, the fine particles are captured at the first end of the fine holes. In the substrate of the present invention, the major axis of the opening at the first end of the micropore can be made smaller than before, and the major axis can be nano-order or sub-micron order. When fine particles are adsorbed at the first end portion, the probability that a single fine particle can be adsorbed can be increased. In other words, since the aperture has a small diameter, there is little risk of simultaneously capturing a plurality of fine particles in the opening. Therefore, experiments such as measurement and observation can be easily performed on the captured fine particles.

The perspective view which shows an example of the manufacturing method of the base | substrate which concerns on this invention. The perspective view which shows an example of the manufacturing method of the base | substrate which concerns on this invention. The perspective view which shows an example of the manufacturing method of the base | substrate which concerns on this invention. The perspective view which shows an example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in an example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in an example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in an example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in an example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. The perspective view which shows another example of the manufacturing method of the base | substrate which concerns on this invention. The perspective view which shows an example of the laser irradiation method S. FIG. The schematic diagram which shows the relationship between the laser irradiation intensity | strength and the modified part (oxygen deficient part) formed. The schematic diagram which shows the relationship between the laser irradiation intensity | strength and the modified part (oxygen deficient part) formed. The perspective view which shows another example of the manufacturing method of the base | substrate which concerns on this invention. The perspective view which shows another example of the manufacturing method of the base | substrate which concerns on this invention. The perspective view which shows another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. Sectional drawing of a base | substrate in another example of the manufacturing method of the base | substrate which concerns on this invention. The perspective view which shows an example of the base | substrate which concerns on this invention. FIG. 17 is a cross-sectional view of the substrate shown in FIG. 16. Sectional drawing which shows a mode that microparticles | fine-particles were trapped in the 1st end part of a micropore in an example of the base | substrate which concerns on this invention. Sectional drawing which shows arrangement | positioning of the flow path which a micropore communicates (connects) in an example of the base | substrate which concerns on this invention. Sectional drawing which shows a mode that the electrode which can be used for an electrophysiological measurement is arrange | positioned in an example of the base | substrate which concerns on this invention. The perspective view which shows a mode that microparticles | fine-particles were trapped in the 1st end part of a micropore in another example of the base | substrate which concerns on this invention. The perspective view which shows a mode that several microparticles | fine-particles were trapped in the 1st end part of a micropore in the base | substrate of a comparative example. The figure which shows the heat processing temperature characteristic of a modification part in the manufacturing method of the base | substrate which concerns on this invention.

Hereinafter, based on a preferred embodiment, the present invention will be described with reference to the drawings.

<Manufacturing method of substrate having fine holes>
(1) Manufacturing method of substrate of first aspect (first manufacturing method)
According to the present invention, “a manufacturing method of a substrate having microscopic holes (first manufacturing method)” is performed by scanning the focal point of a first laser beam having a time width of picosecond order or less inside the substrate and performing etching. Step A for forming the first modified portion and the second modified portion having selectivity, and the inside of the substrate so as to overlap with the first portions of the first modified portion and the second modified portion. Scanning the focal point of the second laser beam having a time width of picosecond order or less to form the first re-modification part and the second re-modification part in which the modified state in each of the first parts is modified B, the step C for increasing the etching resistance of the first re-reformer and the second re-reformer by heating the first re-reformer and the second re-reformer, and the first The first reforming part excluding one re-modification part and the second re-modification part; Serial to the second reforming unit is removed by etching, and a step D of forming micropores in said substrate.

In the present invention, the “first modified portion” and the “second modified portion” refer to portions where the substrate has been modified as follows. In other words, the “first modified part” has a stronger interference wave between the plasmon generated during irradiation or the electron plasma wave and the incident light in the region where the first laser beam is focused on the substrate (the focused part). In general, it is a portion that can be selectively etched by the etching process in step D, and can be formed with fine holes after etching. The “second modified portion” is a portion where the influence of the interference wave is weaker than that of the first modified portion in the region where the first laser beam is focused and irradiated on the substrate (the focused portion). In particular, it is a portion that is relatively difficult to be etched by the etching process of step D.

In the present invention, the “first re-modification part” is a part in which the first modification part is modified by the irradiation of the second laser light and the etching resistance is higher than that of the first modification part. The “second re-modified part” is a part in which the second modified part is modified by the irradiation of the second laser light and the etching resistance is higher than that of the second modified part. These re-modified portions are further improved in etching resistance by the heat treatment, and can be recovered to almost the same etching resistance as the non-modified portions (portions not receiving the laser irradiation). On the other hand, even when the first modified part and the second modified part are subjected to the heat treatment, the first modified part and the second modified part do not recover to the etching resistance equivalent to those of the re-modified part.
Therefore, in step D, the first modified portion or the second modified portion is selectively etched and removed from the substrate, so that the region where the first modified portion or the second modified portion is formed is finely formed. Holes can be formed. In this etching, the first re-modified part and the second re-modified part can be left without being etched by using the difference in etching resistance.

In step D, by using an etching method, etching conditions, and an etchant suitable for the purpose, either the first modified portion or the second modified portion can be selectively or preferentially etched. In some cases, there is a possibility that both the first modified portion and the second modified portion can be etched at the same time, but usually only one of the modified portions is selectively or preferentially etched.
Hereinafter, each step of the “method for producing a substrate having fine holes (first production method)” according to the present invention will be described more specifically.

When forming the first reforming part in step A, a second reforming part having almost the same long diameter as the first reforming part can be formed adjacent to the first reforming part. As will be described later, the second modified portion is likely to be formed when the irradiation intensity of the first laser light is set in the vicinity of the processing upper limit threshold or higher than the processing upper limit threshold.
The first reforming part and the second reforming part formed adjacent to the first reforming part are each composed of a first part and a second part excluding the first part. After Step A, in Step B, the first portion of the second modified portion is also formed by the second laser beam in the same manner as the first portion of the first modified portion (which may include a periodic component). And the history of reforming of the first part in the second reforming part is erased, and the first part of the second reforming part and the re-reforming part It is formed so as to overlap or be in contact with (a reforming portion or a periodic reforming group that can include a periodic component).
Therefore, similarly to the first modified part, the history of the first part constituting the second modified part is erased and the first part constituting the second modified part is left after etching. Can do. Here, by changing conditions such as the composition of the etchant or the etching time, the second modified portion may be preferentially or selectively etched while leaving the first modified portion. Even in this case, since the modified portion (the second portion) in which the diameter of the second modified portion that becomes the micropore is made smaller can be formed, the micropore formed by etching the second modified portion Can be made smaller than when the periodic structure is not formed. That is, even when the second modified portion is etched, nano-order micropores having a smaller pore diameter can be formed with a fine periodic structure.

In the etching process of step C, it is easier to etch the first modified portion than to etch the second modified portion. For this reason, it is desirable to etch the first modified portion.
In the following embodiments, the present invention will be described based on a method of etching the first modified portion. However, the second modified portion can be similarly etched by changing the etching conditions. . The shape or size of the micropores formed when the second modified portion is etched and the shape or size of the periodic structure are the shapes of the micropores formed when the first modified portion is etched or Similar to size and shape or size of periodic structure. This is because the first reforming part and the second reforming part are formed adjacent to each other in a shape or size similar to each other.

[Step A in the first production method]
In step A, a first modified portion having a nano-order pore diameter is formed in a region including a region to be a micropore in the base material using a first laser beam having a time width of picosecond order or less. FIG. 1 is a schematic view showing a state in which the first laser light L is irradiated from the upper surface of the base material 4 constituting the base.
The first modified portion 1 having etching selectivity is formed in the substrate 4 by scanning the focal point (condensing region) of the first laser light L in the direction of the arrow U. The first modified portion 1 is formed in a region including a region that becomes the microhole 3 after the etching in the process D. The first end portion 1 a and the second end portion 1 b of the first reforming portion 1 are exposed on the side surface of the substrate 4.

In the present invention, the “first modified portion” means “a portion that has low etching resistance (high etching selectivity) and is selectively or preferentially removed by etching”.

In the example shown in FIG. 1, the polarization direction E1 of the first laser light L is orthogonal to the scanning direction U. That is, the angle formed by the scanning direction U and the polarization direction E1 is 90 °. In the present invention, the angle formed by the scanning direction U of the first laser light L and the polarization direction E1 of the first laser light L is preferably greater than 88 ° and 90 ° or less, and is 88.5 °. More preferably, it is 90 ° or less, more preferably 89 ° or more and 90 ° or less, and particularly preferably 90 °.
Moreover, it is preferable that the laser irradiation intensity of the first laser light L is less than the processing upper limit threshold and in the vicinity of the processing upper limit threshold, or more than the processing lower limit threshold and less than the processing upper limit threshold. The description of “processing lower limit threshold” and “processing upper limit threshold” will be described later.

By irradiating the first laser beam L set in this way, the diameter (short axis) of the polarization direction E1 among the hole diameters of the first modified portion 1 to be formed is nano-order (about 1 nm to 900 nm) or It can be formed more easily so as to be in the sub-micro order (about 0.9 μm to 1 μm). On the other hand, among the hole diameters of the first modified portion 1 to be formed, the diameter (major axis) in the propagation direction Z of the first laser light L is usually about 0.5 μm to 5 μm.

When the first reforming portion 1 is formed as described above, a second reforming portion having substantially the same shape as the first reforming portion 1 is formed adjacent to both sides thereof. In FIG. 1, the second reformer is formed on the back side and the front side of the first reformer 1 so as to be parallel to the first reformer 1. In addition, in order to make a figure legible, the 2nd modification part is not drawn. In the subsequent process B, when the first portion of the first modified portion 1 is overwritten by the irradiation of the second laser beam, the first portion of the second modified portion is also overwritten in the same manner.

[Step B in First Production Method]
In step B, the focal point of the second laser beam M having a time width of picosecond order or less is scanned so as to overlap with at least the first part of the first reforming unit 1, and the modified state in the first part is denatured. The first re-modified part 2 thus formed is formed. FIG. 2 is a schematic diagram showing a state in which the second laser light M is irradiated from the upper surface of the base material 4 that forms the base. By scanning the focus (condensing area) of the second laser beam M in the direction of the arrow K, the first portion of the first reforming unit 1 is denatured and converted to the first re-modifying unit 2. That is, the first part of the first reforming unit 1 is overwritten by the first re-modifying unit 2. The 1st re-modification part 2 may have etching selectivity and does not need to have it. Usually, the etching resistance of the first re-modified part 2 is higher than the etching resistance of the first modified part 1 (that is, the etching rate of the first re-modified part 2 is higher than that of the first modified part 1). Is slower than speed). The reason for this is that when the first re-modification part 2 is formed, it is necessary to overwrite the first reforming part 1, so that the non-reformable region of the base material 4 is more directly modified than when the first re-modification part 2 is formed. This is because the degree of reforming of the first re-reforming unit 2 becomes small.

The region where the focal point of the second laser beam M is scanned may include a region deviated from the region overlapping with the first modified portion 1. Since the deviated region is also modified by the irradiation with the second laser beam M, the structurally altered portion 7 with reduced etching resistance can be formed in the region. The structurally altered portion 7 may be modified so strongly that it has etching selectivity, or may be modified so weakly that it has almost no etching selectivity. By appropriately setting the laser irradiation intensity and the laser irradiation conditions, either modification can be achieved.

In step B, the polarization direction E2 of the second laser light M is preferably different from the polarization direction E1 of the first laser light L in step A. That is, in the present invention, it is preferable that the polarization direction E1 of the first laser light L and the polarization direction E2 of the second laser light M are different from each other. By using laser beams having different polarization directions, the modified state of the first portion of the first modified portion 1 can be modified, and the first re-modified portion 2 can be formed more easily.

Further, as shown in FIG. 2, it is preferable to form the first re-modification part 2 along the longitudinal direction of the first modification part 1. Here, the longitudinal direction of the first reforming unit 1 is a direction (scanning direction K) connecting the first end 1a and the second end 1b of the first reforming unit 1. The etching resistance of the first re-modification part 2 formed so as to overlap in the longitudinal direction of the first reforming part 1 is increased by the heat treatment in the subsequent step C, so that the first re-modification part 2 is hardly etched or substantially It can be set as the area | region which is not etched chemically. That is, the first portion of the first modified portion 1 formed by the first laser light L is transferred to the first re-modified portion 2 using the second laser light M over the longitudinal direction of the first modified portion 1. By rewriting, the region of the first modified portion 1 that is actually etched can be narrowed. As a result, the hole diameter of the fine hole 3 finally formed by etching can be reduced over the longitudinal direction of the first modified portion 1.

At this time, the angle formed by the scanning direction K of the second laser light M and the polarization direction E2 of the second laser light M is preferably 0 ° or more and 88 ° or less.
By adjusting to the angle formed by the above range, the periodic component that can be included in the first re-modification part 2 and the structural alteration part 7 can be formed to intersect the scanning direction K of the second laser light M. That is, the periodic components that can be included in the first re-modification part 2 and the structural alteration part 7 can be formed so as to intersect the longitudinal direction of the first modification part 1. When the first re-modification part 2 and the structurally altered part 7 are formed so that the periodic component intersects the longitudinal direction of the first reforming part 1, in the heat treatment in the subsequent step C, the first The etching resistance of the re-modified part 2 and the structurally altered part 7 can be increased more easily. As a result, in the etching in the process D, it becomes possible to increase the difference in etching rate between the first modified portion 1, the first re-modified portion 2 and the structurally modified portion 7, and a smaller size hole diameter. It is possible to form the fine holes 3 having.

When the irradiation intensity of the second laser beam M is set to be equal to or higher than the processing upper limit threshold, in the first re-modification part 2 and the structural alteration part 7, the region where the degree of modification is relatively strong and the degree of modification are relatively weak. The regions can be formed in a self-forming manner in parallel and alternately with a period. Each of these two regions is defined as a “periodic component” that constitutes the period. A direction in which the periodicity is observed, which is a direction orthogonal to the direction in which these periodic components extend, is defined as a “periodic direction of the periodic component”. When the angle formed between the scanning direction K of the second laser beam M and the polarization direction E2 is set to 0 ° or more and 88 ° or less, the periodic component has a period of the periodic component when formed so as to intersect the scanning direction K. The direction coincides with the scanning direction K.

A specific example of this is the structurally altered portion 7 shown in FIG. The first re-modification part 2 corresponds to a part formed by overwriting the part where the first reforming part 1 was formed with the structurally altered part 7, but in FIG. (This is to make it easy to see the periodic component 6 of the structurally altered portion 7).

In the example of FIG. 8, the angle formed between the scanning direction K of the second laser beam M and the polarization direction E2 is set to 0 °, the laser irradiation intensity is set to a processing upper limit threshold value or more, and the second laser beam M Is scanned along the longitudinal direction of the first reforming unit 1 so that at least the first portion overlaps at least the first portion of the first reforming unit 1. When irradiated under this condition, the structurally altered portion 7 including the periodic component 6 can be formed along the longitudinal direction of the first modified portion 1. At this time, the extending direction of each periodic component 6 intersects (orthogonally) the longitudinal direction of the first reforming unit 1. Each region illustrated by a broken line as the periodic component 6 is a region where the degree of reforming is relatively strong. The periodic direction in which the period of the periodic component 6 is observed coincides with the scanning direction K. The interval (separation distance) between the periodic components 6 can be in the nano order. The degree of modification of the periodic component 6 can be modified so strongly as to have etching selectivity by controlling the irradiation intensity or irradiation time of the laser and the number of pulses, or the degree of not having etching selectivity. It is also possible to modify it weakly. Therefore, when the structurally modified portion 7 is strongly modified to have etching selectivity, the etching selectivity remains even after the heat treatment in the step C, and the periodic component 6 is obtained by the etching treatment in the step D. It is also possible to form a periodic structure corresponding to this arrangement along the longitudinal direction of the fine holes 3.

The angle formed by the scanning direction K of the second laser beam M and the polarization direction E2 is preferably 0 ° or more and 88 ° or less, more preferably 0 ° or more and 15 ° or less, and 0 ° The angle is more preferably 10 ° or less, particularly preferably 0 ° or more and 5 ° or less, and most preferably 0 °. That is, it is preferable that the angle formed is smaller (closer to 0 °). The smaller the angle formed by the scanning direction K of the second laser beam M and the polarization direction E2, the smaller the laser required for overwriting the first re-modification unit 2 on the first portion of the first modification unit 1. Irradiation intensity becomes small and the 1st re-modification part 2 can be formed efficiently.

2 and FIGS. 5A to 5D show the case where the propagation direction Z of the second laser light M is perpendicular to the upper surface of the substrate 4, but it is not necessarily perpendicular. You may irradiate the 2nd laser M so that it may become a desired incident angle with respect to the said upper surface.

In general, the laser transmittance of the modified part is different from the laser transmittance of the unmodified part, so it is normal to control the focal position of the laser beam that has passed through the modified part. Have difficulty. However, the second laser beam M for forming the first re-modified part 2 and the structurally altered part 7 can be irradiated through the first modified part 1 formed in the process A. That is, since the first reforming unit 1 does not make it difficult to control the irradiated second laser light M, the first reforming unit 2 can be formed to overlap the first reforming unit 1. it can. The reason why the first modified portion 1 does not affect the incident second laser light M is unclear, but it is considered that the width of the first modified portion 1 is nano-order.

Moreover, as shown in FIG. 2, you may form the 1st re-modification part 2 and the structural alteration part 7 by condensing and irradiating the 2nd laser beam M using a lens.
As the lens, for example, a refractive objective lens or a refractive lens can be used. In addition, for example, it is possible to irradiate with a Fresnel, a reflection type, an oil immersion type, or a water immersion type. Further, for example, if a cylindrical lens is used, it is possible to irradiate a laser beam over a wide area of the glass substrate 4 at a time. Furthermore, for example, if a conical lens is used, the laser beam L can be irradiated at once in a wide range in the vertical direction of the glass substrate 4.

The following various conditions are mentioned as a specific example of the laser irradiation conditions which form "the 1st re-modification part 2 or the 1st re-modification part 2 and the structural alteration part 7". For example, a titanium sapphire laser (laser using a crystal in which sapphire is doped with titanium as a laser medium) or a pulse laser having a pulse time width of 1 fs or more and less than 10 picoseconds can be used. As the laser light to be irradiated, for example, a wavelength of 800 nm and a repetition frequency of 200 kHz are used, and the laser light M is condensed and irradiated at a laser scanning speed of 1 mm / second. These values of wavelength, repetition frequency, and scanning speed are examples, and the present invention is not limited to this, and can be arbitrarily changed.
In the present specification and claims, the “pulse time width of the order of picoseconds or less” is preferably a pulse time width of 1 fs or more and less than 1 nanosecond, and preferably a pulse time width of 1 fs or more and less than 10 picoseconds. More preferably, the pulse time width is 1 fs or more and less than 3 picoseconds, more preferably 1 fs or more and less than 2 picoseconds.
When the pulse time width is on the order of picoseconds or less, the electron temperature and ion temperature of the base material in the light condensing portion are heated in a non-equilibrium state, and processing in a so-called non-thermal process proceeds. And the thermal diffusion length is suppressed to the limit. Furthermore, since non-linear processing starting from multiphoton absorption becomes dominant, the shape obtained after processing can be changed from nanoscale to micro-order micropores.
On the other hand, in the case of using a pulse laser exceeding the picosecond order, for example, a laser beam having a pulse time width of 10 picoseconds or more, thermal processing in which the electron temperature and ion temperature of the base material in the condensing part are in an equilibrium state. Becomes dominant. In thermal processing, the thermal diffusion length increases, making it difficult to perform nano to micro-order scale processing. In this way, the reaction mechanism is completely different at the boundary of the pulse time width of about 1 to 10 picoseconds.

[Step C in the first production method]
In step C, the “first re-reformer 2 or the first re-reformer 2 or the first structural reformer 7” is heated to heat the “first re-reformer 2 or first re-reformer 2. A process of increasing the etching resistance of the part 2 and the structurally altered part 7 "(a process of making the etching difficult) is performed. As a method of heating the “first re-modification part 2, or the first re-modification part 2 and the structural alteration part 7” formed inside the base material 4, the whole base material 4 is heated by an electric furnace or an infrared lamp. The heating may be performed, the first re-modification part 2 and its periphery are limited, or the first re-modification part 2 and the structural alteration part 7 and its periphery are limited, and a laser irradiation device for heating is used. It may be used and heated.

Before the heat treatment, the degree of modification (easy to be etched) of the first re-modification part 2 formed by overwriting the first modification part 1 is higher than the degree of modification of the first modification part 1. Is also small. That is, the etching resistance of the first re-modified part 2 adjacent to the first modified part 1 is higher than the etching resistance of the first modified part 1. When the base material 4 on which the first reforming unit 1 and the first re-modification unit 2 are formed is heat-treated, the degree of reforming of the first reforming unit 1 and the first re-modification unit 2 is both ( (Respectively) and the etching resistance increases (respectively). By performing the heat treatment for a predetermined time, the etching resistance of the first re-modified part 2 is increased to the same level as the etching resistance of the non-modified part of the base material 4 and the etching resistance of the first modified part 1 is increased. Can be made sufficiently lower than the etching resistance of the non-modified portion of the substrate 4. As a result, in the etching process of the subsequent process D, the first re-modified part 2 is not selectively etched, but the first modified part 1 remaining without being overwritten is selectively or preferentially etched. Can be removed.

Specifically, for example, when the glass substrate 4 is used, the first modified portion 1 is in a state where the degree of oxygen deficiency is very large (etching resistance is very low) before the heat treatment, One re-modified part 2 is in a state where the degree of oxygen deficiency is relatively small (low etching resistance), and the non-modified part is in a normal glass state (normal etching resistance). By heat-treating the glass substrate 4, rearrangement of oxygen atoms constituting the glass occurs, the degree of oxygen deficiency in the first reforming portion 1 is slightly eliminated, and the degree of oxygen deficiency is large ( The etching resistance is low), the degree of oxygen deficiency in the first re-modified part 2 is almost eliminated (etching resistance is equal to normal), and the non-modified part remains unchanged. As a result, in the etching process in the subsequent process D, the first modified portion 1 excluding the first re-modified portion 2 can be selectively or preferentially etched and removed.

When the structurally altered portion 7 is formed, the etching resistance of the structurally altered portion 7 is also increased by the heat treatment in the step C, similarly to the first modified portion 1 and the first re-modified portion 2. When the degree of modification of the structurally modified portion 7 is increased to the same extent as that of the first modified portion 1 in the previous step B, the etching selectivity of the structurally modified portion 7 can remain even after the heat treatment. On the other hand, when the degree of modification of the structurally altered portion 7 is sufficiently weaker than that of the first modified portion 1 in the previous step B, the etching resistance of the structurally altered portion 7 is not modified by the heat treatment. It is increased to the same level as the etching resistance of the part.

FIG. 3 shows the base material 4 after the heat treatment. In the base material 4 after the heat treatment, the etching resistance of the first re-modified part 2 and the structurally altered part 7 is almost equal to the etching resistance of the base material 4. For this reason, although the 1st re-modification part 2 and the structural alteration part 7 are not illustrated, this is because the physical properties (transparency, It does not necessarily mean that the hardness, etc.) is completely consistent with the unmodified part.

The heating temperature in the step C is not particularly limited as long as the base material is silicon, sapphire, glass, or quartz as long as at least the etching resistance of the first re-modified part 2 can be increased. In particular, in the case of glass, quartz having an amorphous structure, or when the amorphous structure is formed by irradiating a crystalline base material with a laser, the viscosity (viscosity) of the material of the base material 4 constituting the base body of the present invention is high. It is preferable that the temperature be 10 ^14.5 [poise] or higher and 10 ^11.7 [poise] or lower.
If the 1st re-modification part 2 and the structural alteration part 7 are heated in the temperature of this range, the etching tolerance of the 1st re-modification part 2 and the structural alteration part 7 will increase easily.
Even if the temperature is less than 10 ^14.5 [poise], the etching resistance of the first re-modified part 2 can be increased by adjusting the heating time. On the other hand, if heating is performed at a temperature equal to or higher than 10 ^11.7 [poise], the etching resistance of the first modified portion 1 is also increased, and it is difficult to form micropores.

“Strain point” is a term commonly used in the glass industry, a temperature at which the internal stress of glass disappears in a few hours, and corresponds to a viscosity of about 10 ^14.5 dPa · s. Say. For example, the “strain point” can be obtained by a method defined in JIS R3103-02: 2001. The “softening point” is a term generally used in the glass industry, and is a temperature at which glass starts to soften and deform significantly due to its own weight, and corresponds to a viscosity of about 10 ^7.6 dPa · s. Temperature For example, the “softening point” can be obtained by the method defined in JIS R3103-1: 2001.

More specifically, for example, when the base material 4 made of quartz is used, the temperature of the heat treatment is preferably 800 to 1200 ° C. from the viewpoint of sufficiently increasing the etching resistance of the first re-modified part 2. 850 to 1150 ° C is more preferable, and 850 to 1100 ° C is more preferable. At this time, the heat treatment time is preferably 1 to 10 hours, more preferably 2 to 10 hours, and further preferably 2 to 8 hours. The heat treatment time mentioned here is set at a heating rate of 50 ° C./min. The temperature is raised from room temperature (20 ° C.), and after reaching the heating temperature, the heating temperature is maintained for 60 minutes. This is the total time required for cooling to (20 ° C.).
Within the above range, it is easier to sufficiently enhance the etching resistance of the first re-modified part 2 and the structurally altered part 7 while maintaining the etching selectivity of the first modified part 1.

[Step D in First Production Method]
In step D, the first modified portion 1 except for the first re-modified portion 2 is removed by etching to form micropores 3 in the substrate 4 constituting the substrate. In the base material 4 after the heat treatment, a sufficient difference can be provided between the etching resistance of the first re-modified part 2 and the etching resistance of the structurally modified part 7 and the etching resistance of the modified part 1. The first modified portion 1 can be etched selectively or preferentially. As a result, as shown in FIG. 4, a substrate 10 is obtained in which the micropores 3 having the first end portion 3 a and the second end portion 3 b are formed on the side surface of the substrate 4.
In the above example, the first re-modified part 2 and the structurally altered part 7 are hardly etched. However, when a high-concentration etchant is used or when the etching time is longer than usual, the first re-modified part 2 and the structurally altered part 7 are not etched. There is a possibility that the modified portion 2 or the structurally altered portion 7 is partially etched. Furthermore, depending on the processing conditions, the etching resistance of the first re-modified part 2 and the structurally modified part 7 may be partially close to that of the first modified part 1.

As an etching method, wet etching is preferable. Since the first modified portion 1 has low etching resistance, it can be selectively or preferentially etched.
This etching utilizes the phenomenon that the first modified portion 1 is etched much faster than the unmodified portion (non-modified portion) of the substrate 4, and as a result, the first modification is performed. The fine holes 3 corresponding to the shape of the mass part 1 can be formed.

The etching solution is not particularly limited, and when the substrate 4 is made of glass, for example, a solution containing hydrofluoric acid (HF) as a main component, or a hydrofluoric acid-based mixed acid obtained by adding an appropriate amount of nitric acid or the like to hydrofluoric acid may be used. it can. Further, a basic etchant such as KOH or other chemicals can be used depending on the material of the substrate 4.
As a result of the etching in the step D, the micropores 3 having a nano-order pore diameter can be formed in the substrate 4.

It is possible to reduce or increase the size difference between the first modified portion 1 and the fine hole 3 by adjusting the processing time of the wet etching. For example, it is theoretically possible to reduce the short diameter (shortest diameter) of the micropores 3 to several nanometers to several tens of nanometers by shortening the treatment time. On the contrary, by increasing the processing time, the minor diameter of the fine hole 3 can be made larger.

As the etching in the process D, dry etching is also applicable. Examples of the isotropic dry etching method include various dry etching methods such as barrel type plasma etching, parallel plate type plasma etching, and downflow type chemical dry etching. Examples of the anisotropic dry etching method include a method using reactive ion etching (hereinafter referred to as RIE) such as parallel plate RIE, magnetron RIE, ICP RIE, and NLD RIE. In addition to RIE, for example, etching using a neutral particle beam can be used. When the anisotropic dry etching method is used, a process close to isotropic etching can be performed by shortening the mean free path of ions by a method such as increasing the process pressure. Processing by other dry etching methods is also possible.

5A to 5D show cross sections perpendicular to the longitudinal direction of the first modified portion 1 of the base material 4 in the steps A to D of the first aspect described above. 5A corresponds to the sectional view of the substrate 4 shown in FIG. 1, FIG. 5B corresponds to the sectional view of the substrate 4 shown in FIG. 2, and FIG. 5C corresponds to the sectional view of the substrate 4 shown in FIG. 5D corresponds to a cross-sectional view of the substrate 4 shown in FIG. An arrow Z indicates the propagation direction of the first laser beam L or the second laser beam M. In order to show that the structurally modified portion 7 and the first re-modified portion 2 in FIGS. 5C and 5D can be indistinguishable from the region not irradiated with laser (non-modified portion) with respect to etching resistance or the like, a dotted line is shown. It is drawn by. FIGS. 5A to 5D show an example of manufacturing the substrate 10 by forming the fine holes 3 in the substrate 4 according to the first embodiment of the manufacturing method of the present invention.

By adjusting the laser irradiation intensity in step A or step B, as shown in the cross-sectional views of FIGS. 6A to 6D and FIGS. 7A to 7D, the first reforming part 1, the first re-modification part 2, the structure The altered portion 7 and the fine holes 3 can also be formed in the base material 4. Note that the cross-sectional views of FIGS. 6A to 6D and FIGS. 7A to 7D correspond to the cross-sectional views of FIGS. 5A to 5D.

In FIG. 6B, although the focal point (condensing area) of the second laser beam M is overlaid on the first modified portion 1 and scanned (the scanned area is an area indicated by an ellipse in the figure). ), There is a portion 1z (1) that is not converted into the first re-modification part 2 and remains as the first reforming part 1. This is because the laser irradiation intensity at the peripheral portion of the condensing region of the second laser light M is weak, and the first modified portion 1 has not been modified to be changed to the first re-modified portion 2. . Since the portion 1z (1) can be etched in the process D through the process C, the hole diameter of the micro hole 3 can be larger than that in FIG. 5D.

In FIG. 7B, since the focal point (condensing area) of the second laser beam M is limitedly scanned only to the central portion of the first reforming unit 1, the reforming unit 1p (1) and the reforming unit 1q (1) ) Remains. Since the modified part 1p (1) and the modified part 1q (1) can be etched in the process D through the process C, as shown in FIG. 7D, the two fine holes 3p ( 3) and the substrate 10 formed by arranging the fine holes 3q (3) vertically can be formed.

It should be noted that the major diameter of the micropores can be reduced by appropriately adjusting the processing conditions of the process B and the process C, and the major axis can be set to a nano-order length (length in nm).

[Laser irradiation intensity]
In the present specification and claims, the “processing upper limit threshold (processing appropriate value)” means the interaction between the base material and the laser light at the focal point (condensing area) of the laser light irradiated into the base material. It means the lower limit of the laser irradiation intensity at which interference between the generated electron plasma wave and the incident laser beam occurs, and the striped modified portion can be formed on the substrate in a self-forming manner due to the interference.
In the present specification and claims, the “processing lower limit threshold (threshold value)” means a modified portion obtained by modifying the base material at the focal point (condensing area) of the laser light irradiated into the base material. The lower limit of the irradiation intensity of the laser that can reduce the etching resistance of the modified portion to such an extent that it can be selectively and preferentially etched by the subsequent etching process. The region irradiated with the laser with the laser irradiation intensity lower than the processing lower limit threshold is hardly selectively or preferentially etched in the subsequent etching process. For this reason, in order to form a modified portion that becomes a fine hole after etching, it is preferable to set the laser irradiation intensity to be equal to or higher than a processing lower limit threshold value.

The machining upper limit threshold and the machining lower limit threshold are generally determined by the wavelength of the laser beam, the material (material) of the substrate that is the target of laser irradiation, and the laser irradiation conditions. However, when the relative directions of the polarization direction of the laser beam and the scanning direction are different, the processing upper limit threshold and the processing lower limit threshold may be slightly different. For example, the processing upper limit threshold and the processing lower limit threshold may differ between when the scanning direction is perpendicular to the polarization direction and when the scanning direction is parallel to the polarization direction. Therefore, the processing upper limit threshold and the processing lower limit threshold when the relative relationship between the polarization direction of the laser light and the scanning direction is changed in the wavelength of the laser light to be used and the base material to be used are examined in advance. It is preferable.

[Laser irradiation method for forming a single modified portion]
In step A, the irradiation intensity of the laser when irradiating the first laser beam L is preferably set to be equal to or higher than the processing lower limit threshold and lower than the processing upper limit threshold, and is set to be lower than the processing upper limit threshold and near the processing upper limit threshold. Is more preferable.
With the above setting, the minor diameter of the fine hole 3 formed after etching the first modified portion 1 can be more easily formed so as to have a nano-order length.

In Step A, the irradiation intensity of the laser light L is set to be equal to or higher than the processing lower limit threshold and lower than the processing upper limit threshold, or lower than the processing upper limit threshold and near the processing upper limit threshold, and the polarization direction E1 of the first laser light L It is preferable that the (electric field direction) be substantially perpendicular to the scanning direction U. That is, it is preferable to set the angle formed by the polarization direction E1 of the first laser light L and the scanning direction U of the focal point to be greater than 88 ° and 90 ° or less. Such a laser irradiation method is hereinafter referred to as a laser irradiation method S.

The laser irradiation method S will be described with reference to FIG. The propagation direction of the first laser light L is an arrow Z, and the polarization direction (electric field direction) of the first laser light L is an arrow E1. In the laser irradiation method S, the irradiation region of the first laser light L is configured by a propagation direction Z of the first laser light L and a direction perpendicular to the polarization direction E1 of the first laser light L. It is in the plane 4a.

According to the laser irradiation method S, a single modified portion 1 (oxygen-deficient portion in quartz or glass) can be formed along the region scanned with the focus (condensing region) of the laser light (FIG. 10A). ). Since the etching resistance of the modified portion 1 formed in this way is extremely weak, a single fine hole 3 can be formed by performing the etching (FIG. 4). This has been found by the inventors' diligent study.

Further, according to the laser irradiation method S, the modified portion 1 having a nano-order pore diameter can be formed in the substrate 4. For example, the modified portion 1 having a substantially elliptical (substantially rectangular) cross section with a minor axis of about 20 nm and a major axis of about 0.2 μm to 5 μm is obtained. For example, when the scanning direction U is substantially perpendicular to the propagation direction Z of the laser light L, the substantially elliptical shape has a major axis in the direction along the laser propagation direction Z, and the laser polarization direction E1. The direction along is the short axis. Depending on the state of laser irradiation, the cross section of the modified portion 1 to be formed may have a shape close to a rectangle.

The method of scanning the focal point of the first laser beam L when forming the modified portion 1 using the laser irradiation method S is not particularly limited, but the modified portion 1 that can be formed by one continuous scanning has a polarization direction. It is limited to a one-dimensional direction substantially perpendicular to (arrow E1 direction) and a two-dimensional direction (plane 4a) in the propagation direction of laser light L (arrow Z direction). The reforming part can be formed to have an arbitrary shape within the two-dimensional direction.

In FIG. 9, the propagation direction Z of the first laser light L is shown as being perpendicular to the upper surface of the substrate 4, but is not necessarily perpendicular. You may irradiate the 1st laser L so that it may become a desired incident angle with respect to the said upper surface.
Forming the modified portion 1 having an arbitrary shape in the three-dimensional direction in the substrate 4 is performed by appropriately changing the laser polarization direction (arrow E1 direction) and appropriately adjusting the focus scanning direction. be able to.

Moreover, as shown in FIG. 9, you may form the modification part 1 by condensing and irradiating the 1st laser beam L using a lens.
As the lens, for example, a refractive objective lens or a refractive lens can be used, but it is also possible to irradiate by, for example, a Fresnel, reflective, oil immersion or water immersion method. Further, for example, if a cylindrical lens is used, it is possible to irradiate a wide area of the base material 4 with a laser at a time. For example, if a conical lens is used, the laser beam L can be irradiated at once in a wide range in the vertical direction of the substrate 4. However, when a cylindrical lens is used, the polarization of the laser light L needs to be horizontal with respect to the direction in which the lens has a curvature.

Specific examples of the laser irradiation condition S include the following various conditions. For example, in the case of using a titanium sapphire laser (laser using a crystal in which sapphire is doped with titanium as a laser medium), the laser beam to be irradiated uses, for example, a wavelength of 800 nm, a repetition frequency of 200 kHz, and a laser scanning speed of 1 mm / second. The laser beam L is condensed and irradiated. These values of wavelength, repetition frequency, and scanning speed are examples, and the present invention is not limited to this, and can be arbitrarily changed.

As a lens used for condensing, for example, N.I. A. It is preferable to use an objective lens of <0.7. As an irradiation condition for forming finer fine holes 3, it is preferable to irradiate in the vicinity of the processing upper limit threshold or less than the processing upper limit threshold and in the vicinity of the processing upper limit threshold.
Specifically, for example, when the pulse time width is 300 fs, the repetition frequency is 200 kHz, and the scanning speed is about 1 mm / s, the irradiation intensity is about 550 kW / cm ² at a pulse energy of about 80 nJ / pulse or less. It is preferable to irradiate with a laser fluence per pulse of about 2.7 J / cm ² at the irradiation intensity.
On the other hand, if the irradiation intensity is equal to or higher than the processing upper limit threshold value or the laser fluence per pulse corresponding to the processing upper limit threshold value, a plurality of modified portions 1 having periodicity may be formed. Also, if the pulse time width is shortened, the scanning speed is slowed, or the repetition frequency is increased, the optimum laser irradiation intensity or laser fluence per pulse becomes smaller, and conversely the pulse time width. If the length is increased, the scanning speed is increased, or the repetition frequency is decreased, the optimum irradiation intensity or the laser fluence per pulse tends to increase. Furthermore, N.I. Processing is possible even if A. ≧ 0.7, but since the spot size is smaller and the laser fluence per pulse is larger, laser irradiation with a smaller pulse energy is required. Laser fluence refers to the amount of energy per unit area and is expressed in J / cm ² or W / cm ² .

[Laser irradiation method for self-forming a plurality of modified portions having periodicity]
When the laser beam L having a pulse time width of the picosecond order or less is set to the processing upper limit threshold value or more and focused and irradiated, the interference between the electron plasma wave and the incident light occurs in the focused region, and the laser polarization direction E1 A plurality of reforming sections 1 arranged in a row can be formed in a self-forming manner with periodicity (see FIG. 11).

When scanning with the laser light set to the above conditions, the periodicity formed by subsequent laser irradiation (following laser pulse) is applied to the modified part with periodicity formed by the first laser irradiation (first laser pulse). Since the accompanying reforming portions can be continuously connected, a plurality of reforming portions 1, 1 ′, 1 ″ arranged at a predetermined interval in the polarization direction E1 can be formed. The longitudinal direction of “1” is substantially perpendicular to the polarization direction E1. Further, among the plurality of reforming portions 1, 1 ′, 1 ″ formed in parallel, the reforming degree of the reforming portion 1 ′ formed in the center is higher than that of the reforming portions 1, 1 ″. There is a tendency to become larger than the degree of modification (see FIG. 11).

The etching resistance of the plurality of modified portions formed is weak. For example, in the case of quartz (glass), the oxygen-deficient layer and the oxygen-enriched layer are periodically arranged (FIG. 10B), and the etching resistance of the oxygen-deficient portion is weak. (Periodically arranged micropores) can be formed.

As specific examples of the laser irradiation conditions when the plurality of modified portions having periodicity are formed in a self-forming manner, the following various conditions can be given. For example, in the case of using a titanium sapphire laser (laser using a crystal in which sapphire is doped with titanium as a laser medium), the laser beam to be irradiated uses, for example, a wavelength of 800 nm, a repetition frequency of 200 kHz, and a laser scanning speed of 1 mm / second. The laser beam L is condensed and irradiated. These values of wavelength, repetition frequency, and scanning speed are examples, and the present invention is not limited to this, and can be arbitrarily changed.

As a lens used for condensing, for example, N.I. A. It is preferable to use an objective lens of <0.7. As an irradiation condition for forming a plurality of finer microholes 3, it is preferable to irradiate at or above the processing upper limit threshold and in the vicinity of the processing upper limit threshold.
Specifically, for example, when the pulse time width is 300 fs, the repetition frequency is 200 kHz, and the scanning speed is about 1 mm / s, the irradiation intensity is about 600 kW / cm ² or more with the pulse energy of about 90 nJ / pulse or more. It is preferable to irradiate under the irradiation conditions of the laser fluence per pulse of about 3 J / cm ² or more. N. A. Machining is possible even when set to ≧ 0.7, but when the pulse energy is the same, the spot size is smaller and the laser fluence per pulse is larger, so a smaller pulse energy is set. Laser irradiation is required.
The period (separation distance (interval)) of the plurality of modified portions 1 formed can be changed by changing the wavelength of laser light or pulse energy. In general, the longer the wavelength of laser light, or the larger the pulse energy of laser light, the greater the period.

The laser irradiation method (laser irradiation method S) for forming a single modified portion and the laser irradiation method for forming a plurality of modified portions having periodicity in a self-forming manner are the modified portion in step A. However, it may be applied when forming the re-modified part or the re-modified part and the structurally altered part in Step B. Further, the pulse energy at the time of laser irradiation in the process B is preferably a pulse energy that can realize the laser irradiation method S in the process A, and more preferably slightly less than the pulse energy of the laser irradiation method S. It is preferable to irradiate with a small pulse energy. Further, in step B, it is possible to irradiate a plurality of positions in the substrate by shifting the focus height of the laser beam M to be scanned.

In the present specification, the case where the polarization of the laser beam used in the present invention is linear polarization has been described in detail. It can be easily imagined that the same modified portion, re-modified portion, and structurally altered portion can be formed even when the polarization of the laser light used in the present invention has some elliptical polarization component.

(2) Manufacturing method of substrate of second aspect (second manufacturing method)
According to the present invention, a “method for manufacturing a substrate having microscopic holes (second manufacturing method)” scans the focal point of a second laser beam having a time width of picosecond order or less inside the substrate. Forming a structurally altered portion with reduced etching resistance of the substrate; and a first laser beam having a time width of picosecond order or less inside the substrate so as to partially overlap the structurally altered portion. By scanning the focal point, a third modified portion and a fourth modified portion having etching selectivity are formed in a region that does not overlap with the structurally altered portion in the scanned region, and the scanned region Step β of forming a third re-modification part and a fourth re-modification part in which etching resistance of the structural change part is changed in a region overlapping with the structural change part, the third re-modification part, The fourth re-modification part and the structural change A step γ for increasing the etching resistance of the third re-modification part, the fourth re-modification part and the structural alteration part by heating the material part, and the third re-modification part, the fourth re-modification part. And a step δ of forming micropores in the substrate by removing the third modified portion and the fourth modified portion other than the material portion and the structurally modified portion by etching.

[Step α in Second Production Method]
In step α, a structurally altered portion with reduced etching resistance is formed in the substrate using the second laser beam. FIG. 12 is a view showing a state in which the second laser light M is irradiated from the upper surface of the base material 4 constituting the base body. By scanning the focal point (condensing area) of the second laser beam M in the direction of the arrow K, the structurally altered portion 7 with reduced etching resistance is formed in the base material 4. The structurally altered portion 7 is formed adjacent to the region where the third modified portion 1 is formed in step β. In the example of FIG. 12, the first end 7 a and the second end 7 b of the structurally altered portion 7 are exposed on the side surface of the substrate 4. The structurally altered portion 7 may be strongly modified to the extent that it has etching selectivity, or may be weakly modified to the extent that it has little etching selectivity. Either level can be achieved by appropriately setting the laser irradiation intensity and the laser irradiation conditions.

In the present invention, the “third modified portion” means “a portion that has low etching resistance and is selectively or preferentially removed by etching”. The “structurally altered portion” means “a portion whose etching resistance is low but is not necessarily selectively or preferentially removed by etching”.

In step α, the polarization direction E2 of the second laser light M is preferably different from the polarization direction E1 of the first laser light L in step β. In other words, in the present invention, the polarization direction E2 of the second laser light M and the polarization direction E1 of the first laser light L are preferably different from each other. By using laser beams having different polarization directions, the third re-modification part 2 in which the modified state is modified in at least the first part of the structurally modified part 7 and its etching resistance is changed in step β is easy. Formed. At this time, the etching resistance of the third re-modified part 2 is more easily increased than the etching resistance of the structurally altered part 7.

Further, as shown in FIG. 12, it is preferable to form the structurally altered portion 7 along the longitudinal direction of the third modified portion 1 to be formed in the step β. Here, the longitudinal direction of the third reforming unit 1 is a direction (scanning direction K) connecting the first end 1a and the second end 1b of the third reforming unit 1 (FIG. 13). Thereby, the 3rd re-modification part 2 can be formed along the longitudinal direction of the 3rd modification part 1 in process (beta).

At this time, the angle formed by the scanning direction K of the second laser light M and the polarization direction E2 of the second laser light M is preferably 0 ° or more and 88 ° or less.
By adjusting the angle within the above range, the periodic component that can be included in the structurally altered portion 7 and the third re-modifying portion 2 formed in the step β is made to intersect the scanning direction K of the second laser light M. Can be formed. That is, the periodic components that can be included in the structurally altered portion 7 and the third re-modification portion 2 can be formed so as to intersect with the longitudinal direction of the third reformed portion 1 formed in the step β. When the structurally modified portion 7 and the third re-modified portion 2 are formed so that the periodic component intersects the longitudinal direction of the third modified portion 1, the structurally modified portion is formed in the heat treatment in the subsequent step γ. The etching resistance of 7 and the third re-modified part 2 is easily increased. As a result, in the etching in the process δ, the difference in etching rate between the third modified portion 1, the structurally altered portion 7 and the third re-modified portion 2 can be increased, and the pore size has a smaller size. Fine holes 3 can be formed.

When the irradiation intensity of the second laser beam M is set to be equal to or higher than the processing upper limit threshold, in the structurally altered portion 7 and the third re-modification portion 2, a region having a relatively strong degree of modification and a degree of modification are relatively weak. The regions can be formed in a self-forming manner in parallel and alternately with periods. Each of these two regions is defined as a “periodic component” that constitutes the period. A direction in which the periodicity is observed, which is a direction orthogonal to the direction in which these periodic components extend, is defined as a “periodic direction of the periodic component”. When the angle formed between the scanning direction K of the second laser beam M and the polarization direction E2 is not less than 0 ° and not more than 88 °, when the periodic component is formed to intersect the scanning direction K, the period of the periodic component The direction coincides with the polarization direction E2. This is the same as the first manufacturing method described in FIG.

The angle formed by the scanning direction K of the second laser beam M and the polarization direction E2 is preferably 0 ° or more and 88 ° or less, more preferably 0 ° or more and 15 ° or less, and 0 ° The angle is more preferably 10 ° or less, particularly preferably 0 ° or more and 5 ° or less, and most preferably 0 °. That is, it is preferable that the angle formed is smaller (closer to 0 °). The smaller the angle formed by the scanning direction K of the second laser beam M and the polarization direction E2, the smaller the laser irradiation intensity required to form the structurally altered portion 7, and the more efficiently the structurally altered portion 7 is formed. Can be formed. That is, the etching resistance of the structurally altered portion 7 tends to decrease as the angle formed by the scanning direction K of the second laser beam M and the polarization direction E2 is smaller.

In FIG. 12, the propagation direction Z of the second laser light M is shown as being perpendicular to the upper surface of the substrate 4, but is not necessarily perpendicular. You may irradiate the 2nd laser M so that it may become a desired incident angle with respect to the said upper surface. In addition, as shown in FIG. 12, the structurally altered portion 7 may be formed by condensing and irradiating the second laser light M using a lens. These methods are the same as the first manufacturing method described above.
Specific examples of the type of second laser beam M, its wavelength, repetition frequency, scanning speed, and the like are the same as the conditions exemplified in the first manufacturing method described above.

[Step β in the second production method]
In step β, a third modified portion having a nano-order pore diameter is formed in a region including a region to be a micropore in the substrate using a first laser beam having a time width of picosecond order or less. FIG. 13 is a schematic diagram showing a state in which the first laser light L is irradiated from the upper surface of the base material 4 constituting the base. By scanning the focal point (condensing area) of the first laser beam L in the direction of the arrow U, the third modified portion 1 having etching selectivity is formed in the substrate 4. The third modified portion 1 is formed in a region including a region where the fine hole 3 is formed after the etching in the step δ. The first end portion 1 a and the second end portion 1 b of the third reforming portion 1 are exposed on the side surface of the base material 4.

When irradiating the first laser beam L, the focal point (condensed area) of the first laser beam L is scanned so as to partially overlap with the structurally altered portion 7 formed in the step α, and among the scanned areas The third modified portion 1 having etching selectivity is formed in a region that does not overlap with the structurally altered portion 7, and the etching resistance of the structurally altered portion 7 is formed in a region that overlaps the structurally altered portion 7 in the scanned region. The third re-modification part 2 in which is changed is formed. That is, the focal point of the first laser beam L is scanned along the longitudinal direction of the structurally altered portion 7, and at least the first portion of the structurally altered portion 7 is overlapped in the longitudinal direction to form the third re-modified portion 2. .

The third re-modification part 2 is difficult to be etched by increasing the etching resistance of the third re-modification part 2 formed by being overlapped in the longitudinal direction of the third modification part 1 by heat treatment in the subsequent step γ. It can be a region that is not substantially etched. Thereby, the area of the third modified portion 1 that is actually etched can be made smaller than the area scanned with the focal point (condensing area) of the first laser beam L. As a result, the diameter of the finally formed fine hole 3 can be reduced in the longitudinal direction of the third modified portion 1.

In the example shown in FIG. 13, the polarization direction E1 of the first laser light L is orthogonal to the scanning direction U. That is, the angle formed by the scanning direction U and the polarization direction E1 is 90 °. In the present invention, the angle formed by the scanning direction U of the first laser beam L and the polarization direction E1 of the first laser beam L is preferably greater than 88 ° and not greater than 90 °, and not less than 88.5 ° and not greater than 90 °. More preferably, it is 89 ° or less, more preferably 89 ° or more and 90 ° or less, and particularly preferably 90 °.
Moreover, it is preferable that the irradiation intensity of the first laser light L is less than the processing upper limit threshold and near the processing upper limit threshold, or more than the processing lower limit threshold and less than the processing upper limit threshold. The description of “processing lower limit threshold (threshold)” and “processing upper limit threshold (processing appropriate value)” is the same as “laser irradiation intensity” described in the first manufacturing method.

By irradiating the first laser beam L set in this way, the diameter (short axis) of the polarization direction E1 among the hole diameters of the third modified portion 1 to be formed is nano-order (about 1 nm to 900 nm) or It can be formed more easily so as to be in the sub-micro order (about 0.9 μm to 1 μm). On the other hand, among the hole diameters of the third modified portion 1 to be formed, the diameter (major axis) in the propagation direction Z of the first laser light L can be usually formed to a length of about 0.01 μm to 1.5 μm. When the size (range) of the focal point (condensing region) of the first laser beam L is the same, the larger the third re-modification part 2 formed in the structural alteration part 7 is, the larger the third reforming part 1 becomes. The hole diameter (for example, the diameter in the propagation direction Z) can be reduced.

In FIG. 13, the propagation direction Z of the first laser light L is shown as being perpendicular to the upper surface of the substrate 4, but it is not necessarily perpendicular. You may irradiate the 1st laser L so that it may become a desired incident angle with respect to the said upper surface. Moreover, as shown in FIG. 13, you may form the 3rd modification part 1 and the 3rd re-modification part 2 by condensing and irradiating the 1st laser beam L using a lens. These methods are the same as the first manufacturing method described above.

Specific examples of the type, wavelength, repetition frequency, scanning speed, etc. of the first laser beam include the same conditions as those exemplified in the first manufacturing method. In addition, the above-described “laser irradiation method for forming a single modified portion” and “laser irradiation method for forming a plurality of modified portions having periodicity in a self-forming manner” are also described in the second manufacturing method. Applicable in

When the third modified portion 1 is formed as described above, by setting the irradiation intensity of the laser beam of the first laser light L to be equal to or higher than the processing upper limit threshold, the third modified portion 1 is adjacent to both sides thereof. A fourth reforming portion having substantially the same shape as that can be formed. In this case, in FIG. 13, the fourth reforming part is formed on the back side and the front side of the third reforming part 1 so as to be parallel to the third reforming part 1. In addition, in order to make a figure legible, the 4th modification part is not drawn in FIG. When the fourth reforming portion is formed, the portion that overlaps the structurally altered portion 7 is similar to the third re-reforming portion 2 described above, and the fourth re-forming portion having the same properties as the third re-reforming portion 2 is formed. A reforming section can be formed.

In general, the laser transmittance of the modified portion with reduced etching resistance is different from the laser transmittance of the unmodified non-modified portion. It may be difficult to control the focal position. For this reason, the first laser light L is not transmitted through the region where the structurally altered portion 7 is formed, but is irradiated from the front of the structurally altered portion 7 toward the structurally altered portion 7 when viewed from the laser irradiation side. It is preferable. That is, avoiding positioning the structurally altered portion 7 between the irradiation port of the first laser light L and its focal point, the focal point is positioned closer to the irradiation port than the structurally altered portion 7. It is preferable to scan.

[Step γ in Second Production Method]
In step γ, by heating the “third re-modification part 2 and the structural alteration part 7 or the third re-modification part 2”, the “third re-modification part 2 and the structural alteration part 7 or A process for increasing the etching resistance of the third re-modified part 2 ”is performed. As a method of heating the “third re-modification part 2 and the structural alteration part 7 or the third re-modification part 2” formed inside the base material 4, the entire base material 4 is heated by an electric furnace or an infrared lamp. The third re-modification part 2 and the structural alteration part 7 and their periphery may be limited, or the third re-modification part 2 and its periphery may be limited, and a laser irradiation device for heating may be used. It may be used and heated.

Before the heat treatment, the degree of modification of the third re-modified part 2 formed by modifying the structurally modified part 7 by irradiation with the first laser beam L is higher than the degree of modification of the third modified part 1. Is also small. That is, the etching resistance of the third re-modified part 2 adjacent to the third modified part 1 is higher than the etching resistance of the third modified part 1. When the base material 4 on which the third reforming part 1 and the third re-modification part 2 are formed is heat-treated, the degree of reforming of the third reforming part 1 and the third re-modification part 2 is both ( (Respectively) and the etching resistance increases (respectively). By performing the heat treatment for a predetermined time, the etching resistance of the third re-modified part 2 is increased to the same level as the etching resistance of the non-modified part of the base material 4 and the etching resistance of the third modified part 1 is increased. Can be made sufficiently lower than the etching resistance of the non-modified portion of the substrate 4. As a result, in the subsequent etching process of step δ, the third modified portion 1 can be selectively or preferentially etched and removed without selectively etching the third re-modified portion 2.

Specifically, for example, when the base material 4 made of synthetic quartz is used, the third modified portion 1 is in a state where the degree of oxygen deficiency is very large (etching resistance is very low) before the heat treatment, The third re-modified part 2 is in a state where the degree of oxygen deficiency is relatively small (low etching resistance), and the non-modified part is in a normal quartz glass state (normal etching resistance). By heat-treating the synthetic quartz (glass) base material 4, the rearrangement of oxygen atoms constituting the synthetic quartz (glass) occurs, and the degree of oxygen deficiency in the third modified portion 1 is slightly eliminated. Thus, the degree of oxygen deficiency is large (etching resistance is low), the degree of oxygen deficiency of the third re-modified part 2 is almost eliminated (etching resistance is equal to normal), and the non-modified part is It does not change. As a result, in the etching process in the subsequent step δ, the modified portion 1 excluding the third re-modified portion 2 can be selectively or preferentially etched and removed.
Here, in the quartz (glass) base material, the “degree of oxygen deficiency” means “the ratio of oxygen atoms that existed before laser irradiation is missing”.

The structurally altered part 7 left when the third re-reformed part 2 is formed is subjected to the heat treatment in the step γ in the same manner as the third modified part 1 and the third re-reformed part 2. The etching resistance of 7 is also increased. When the degree of modification of the structurally modified portion 7 is increased to the same extent as that of the third modified portion 1 in the previous step α, the etching selectivity of the structurally modified portion 7 can remain even after the heat treatment. On the other hand, when the degree of modification of the structurally altered portion 7 is sufficiently weaker than that of the third modified portion 1 in the previous step α, the etching resistance of the structurally altered portion 7 is not modified by the heat treatment. It is increased to the same level as the etching resistance of the part.

FIG. 3 shows an example of the base material 4 after the heat treatment in the first manufacturing method, but an example of the base material 4 after the heat treatment in the second manufacturing method is also the same as the state shown in FIG. is there. That is, when the base material 4 of FIG. 13 is heat-treated, the state shown in FIG. 3 is obtained. In the case of the example shown in FIG. 3, the etching resistance of the third re-modified part 2 and the structurally altered part 7 in the base material 4 after the heat treatment is almost equal to the etching resistance of the base material 4. For this reason, although the 3rd re-modification part 2 and the structural alteration part 7 are not illustrated in FIG. 3, this is because the physical characteristics of the third re-modification part 2 and the structural alteration part 7 after the heat treatment ( It does not necessarily mean that the transparency, hardness, etc.) are completely consistent with the unmodified part.

The explanation of the heating temperature and the heat treatment time in the step γ is the same as the explanation of the heating temperature and the heat treatment time in the step C of the first production method.

[Step δ in Second Production Method]
In step δ, the third modified portion 1 other than the third re-modified portion 2 and the structurally modified portion 7 is removed by etching to form the fine holes 3 in the base material 4 constituting the substrate. In the base material 4 after the heat treatment, there should be a sufficient difference between the etching resistance of the third re-modified part 2 and the etching resistance of the structurally modified part 7 and the etching resistance of the third modified part 1. Therefore, the third modified portion 1 can be etched selectively or preferentially. As a result, as shown in FIG. 4, the base body 10 is obtained in which the micropores 3 having the first end portion 3 a and the second end portion 3 b are formed on the side surface of the substrate 4. FIG. 4 shows an example of the base material 4 after the etching process in the first manufacturing method, but an example of the base material 4 after the etching process in the second manufacturing method is the same as the state shown in FIG. is there.
In the above example, the third re-modified part 2 and the structurally altered part 7 are hardly etched. However, when a high-concentration etchant is used, or when the etching time is longer than usual, the third re-modified part 2 and the structurally altered part 7 are not etched. There is a possibility that the modified portion 2 or the structurally altered portion 7 is partially etched.

The description of the etching method, the etching solution, the processing time of the wet etching, and the etching degree of the fine holes 3 are the same as the description of the step D in the manufacturing method of the first aspect described above.

14A to 14D show cross sections orthogonal to the longitudinal direction of the third modified portion 1 of the base material 4 in steps α to δ of the second manufacturing method described above. 14A corresponds to the cross-sectional view of the base material 4 in FIG. 12, FIG. 14B corresponds to the cross-sectional view of the base material 4 in FIG. 13, and FIG. 14C shows the base material that has undergone step γ after step β in FIG. 14D corresponds to a cross-sectional view of the substrate 4 that has undergone the process δ after the process γ. An arrow Z indicates the propagation direction of the first laser beam L or the second laser beam M. 14A to 14D show an example of manufacturing the substrate 10 by forming the micropores 3 in the base material 4 by the second manufacturing method according to the present invention.

By adjusting the laser irradiation intensity in step α or step β, as shown in the cross-sectional views of FIGS. 15A to 15D, the third modified portion 1, the third re-modified portion 2, the structurally modified portion 7, and The fine holes 3 can also be formed in the substrate 4. Note that the cross-sectional views of FIGS. 15A to 15D correspond to the cross-sectional views of FIGS. 14A to 14D.

In FIG. 15B, not only the third re-modification part 2 but also the fourth modification part 1 z (1) in the region where the focal point (condensing area) of the first laser beam L is superimposed on the structural alteration part 7 and scanned. Is forming.
The reason why the fourth modified portion 1z (1) having low etching resistance is formed is that the irradiation intensity of the first laser beam L is high or the irradiation intensity of the second laser beam M is low, so the structurally altered portion. This is because 7 has been strongly modified. Since the fourth modified portion 1z (1) can be etched in the process δ through the process γ, the hole diameter of the micro hole 3 in FIG. 15D may be larger than that in FIG. 14D.
In addition, if the processing conditions of the process α and the process γ are appropriately adjusted, it is possible to reduce the long diameter of the micropores, and the long diameter can be formed to a nano-order length (length in nm).

<Usage example of substrate with fine pores>
FIG. 16 is a perspective view of the base 30 according to the present invention. 17 and 18 are schematic views showing a cross section taken along line AA of FIG.

The substrate 30 is an example of a substrate having micropores manufactured by the above-described substrate manufacturing method. The base body 30 can be used, for example, for capturing fine particles T. The base 30 is supplied with a fluid Q containing fine particles T, the first flow path 22 constituting a space in the base 24, the second flow path 23 capable of making the inside negative pressure, and the first flow path At least a fine hole 21 that communicates (connects) 22 and the second flow path 23 is provided. The first flow path 22 and the second flow path 23 can be formed by a well-known method such as photolithography when the fine holes 21 are formed.

The fine holes 21 communicate with the outside of the base material 24 through the second flow path 23. The side surface 22a of the first flow path 22 is formed with an opening (adsorption part S) that exposes the first end 21a of the fine hole 21, and at least a part of the upper surface 22c of the first flow path 22 or at least a part of the lower surface 22b is It is constituted by a transparent member 25 so that the fine particles T trapped in the adsorbing part S can be optically observed, and at least a part constituting the micropore 21 in the base material 24 is a single part. It is a member.

In the base body 30, the base material 24 in which the fine holes 21 are formed is a single member.
Examples of the material of the single member include silicon, glass, quartz, and sapphire. These materials are preferable because they are excellent in workability of the fine holes 21. Among these, it is preferable that the material is amorphous so that it is not easily affected by processing anisotropy due to crystal orientation.
Further, in order to observe the fine particles trapped in the opening S by an optical device such as a microscope, the material transmits visible light (wavelength: 0.36 μm to 0.83 μm), glass, quartz, sapphire, etc. It is more preferable to use

Further, the material of the single member transmits light having at least a part of light having a wavelength of 0.1 μm to 10 μm (transparent to light having at least a part of wavelength). Is preferred.
Specifically, it is preferable to transmit light in at least a part of a general wavelength region (0.1 μm to 10 μm) used as a processing laser beam. By transmitting such laser light, the modified portion can be formed by irradiating the member with laser as described above.
More preferably, the material is a material that transmits light in a visible light region (about 0.36 μm to about 0.83 μm). By using a material that transmits light in the visible light region, the captured fine particles T can be easily observed through an optical observation device through the single member.
In the present invention, “transparent” refers to all states in which light is incident on the member and transmitted light is obtained from the member.
In FIG. 16, the single member which comprises the base material 24 is a transparent glass substrate.

The fluid Q is a liquid or a gas, and examples thereof include blood, a cell culture solution, a beverage liquid, and river water. Air is also included in the fluid Q.
The fine particles T captured by the substrate 30 are not particularly limited as long as they can be contained in the fluid Q, and are preferably fine particles that can flow through the flow path. For example, the particle | grains comprised by microorganisms, a cell, an organic substance, the particle | grains comprised by an inorganic substance, etc. are mentioned. Examples of the microorganism include bacteria, fungi, sputum, large viruses and the like. Examples of the cells include cells capable of suspension culture such as red blood cells and white blood cells. Examples of the particles composed of the organic substance include particles composed of a polymer such as a resin or polysaccharide, activated carbon particles, and the like. Examples of the particles composed of the inorganic substance include metal particles such as silica particles and gold colloid particles.

The particles composed of the organic substance and the particles composed of the inorganic substance may be functional particles having antibody molecules or the like bound to the surface or inside thereof.
The shape of the particles composed of the organic substance and the shape of the particles composed of the inorganic substance are not particularly limited. For example, particles having any three-dimensional shape such as a sphere, a cube, a rectangular parallelepiped, a polyhedron, a donut-shaped solid, and a string-shaped solid are included in the fine particles.
The size of the particles composed of the organic substance and the particles composed of the inorganic substance is particularly limited as long as it is larger than the opening diameter (short diameter) of the first end of the micropores constituting the adsorption part. Not.
That is, it is not necessary to have a size that passes through the fine holes.

As shown in FIGS. 17 and 18, the micropore 21 communicates the first flow path 22 and the second flow path 23. The first end portion 21a (first opening portion 21a) of the micro hole 21 is exposed (opened) to the side surface 22a of the first flow path 22 to form the adsorbing portion S. The second end 21 b (second opening 21 b) of the micro hole 21 is exposed on the side surface of the second flow path 23.

The fine hole 21 is a through-hole formed in the single glass substrate 24 and having no seam or bonding surface. Naturally, there is no seam or bonding surface in the adsorbing portion S at the end of the fine hole. Here, the “adsorption portion S” refers to a region on the side surface 22a of the first flow path 22 where the fine particles T are in contact with or close to each other.

The shape or size of the hole in the side surface 22a of the first flow path 22 of the first end portion 21a of the fine hole 21 constituting the suction portion S is the same as the shape or size of the diameter of the fine hole described above.
That is, the shape of the opening of the fine hole 21 may be any of a rectangle, a triangle, an ellipse, or a circle. If the short diameter (shortest diameter) of the opening of the micropore 21 is in the range of 0.02 μm to 5 μm, the microparticles T such as microorganisms or cells can be trapped in the adsorbing portion S. For microorganisms smaller in size than cells, the minor axis is preferably in the range of 0.02 to 0.8 μm.
That is, the short diameter of the opening of the fine hole 21 may be set to such an extent that the fine particles T cannot pass through the fine suction hole 21. For example, when trapping red blood cells (6 to 8 μm), the minor axis may be about 1 μm, and when trapping Bacillus natto (B. subtilis; 0.7 to 2 μm), the minor axis is 0. What is necessary is just to be about 2 μm.

The range of the minor axis is preferably 0.02 μm to 2 μm.
If it is less than the lower limit (that is, 0.02 μm) of the above range, the suction force of the suction portion S may be too weak to trap the fine particles T. If the upper limit of the above range (ie, 2 μm) is exceeded, the fine particles T may pass through the fine holes 21 and may not be trapped.
On the other hand, the length (size) of the long diameter (longest diameter) of the hole may be appropriately adjusted depending on the size of the fine particles T to be trapped, and may be in the range of 0.01 μm to 1.5 μm, for example.

17 and 18, the fine hole 21 is formed to be substantially perpendicular to the side surface 22 a of the first flow path 22. However, it is not necessarily required to be substantially vertical, and the fine holes 21 can be formed at an arbitrary angle with respect to the side surface 22a in the single glass substrate 24 in accordance with the design of the base 30.
A plurality of fine holes 21 may be formed in the base body 30. Since each adsorption hole S is provided for each fine hole 21, a plurality of fine particles T can be trapped.

The lower surface 22 b of the first flow path 22 is constituted by a glass substrate 24. An upper surface 22c of the first flow path 22 facing the lower surface 22b is configured by a member 25 such as plastic or glass. From the upper surface 22c or the lower surface 22b, the fine particles T trapped in the adsorption portion S can be observed by an optical observation device such as a microscope.

The lower surface 23 b of the second flow path 23 is configured by a glass substrate 24, and the upper surface 23 c of the second flow path 23 is configured by a member 25. That is, the second flow path 23 is a semi-sealed space.
On the upstream side of the second flow path 23, the second end portion 21b of the fine hole 21 is exposed and opened. A decompression device such as a syringe or a pump that can decompress the inside of the second channel 23 is provided on the downstream side of the second channel 23 (not shown). Therefore, a part of the fluid Q that flows (circulates) from the upstream side F1 of the first flow path 22 to the downstream side F2 of the first flow path 22 decompresses the inside of the second flow path 23, so that the micropore 21 Is drawn into the second flow path 23 side. At this time, the fine particles T contained in the fluid Q can be attracted to and trapped on the adsorption portion S constituted by the first end portion 21a of the fine hole 21 (FIG. 18).

Further, as shown in FIG. 19, a part of the side surface 22 a of the first flow path 22 may be constituted by a member 25. The flow rate of the fluid Q in the first flow path 22 can be adjusted as appropriate by adjusting the thickness of the member 25.
For example, the diameter of the first flow path 22 can be increased by stacking a plurality of members 25. Furthermore, it is also possible to arrange the downstream side of the second flow path 23 on the upper surface of the base body 30 by using the height (thickness) of the stacked members 25.

The material of the member 25 is not particularly limited. For example, a resin substrate such as PDMS or PMMA, or a glass substrate can be used.
In addition, as a member which comprises the upper surface 23c of the 2nd flow path 23, the member which permeate | transmits the light beam (for example, visible light) of an observation apparatus may be sufficient, and the member which does not permeate | transmit. In the case of aiming only at capturing fine particles, the member need not necessarily be a member that transmits the light beam of the observation apparatus. Any member that transmits the light beam of the observation device is preferable because observation by an optical method from the upper surface is possible.

When performing electrophysiological measurement of the trapped cells (fine particles) T, for example, as shown in FIG. 20, electrodes 26 and 27 can be disposed in the first flow path 22 and the second flow path 23, respectively. Alternatively, electrophysiological measurement can be performed using an external electrode electrically connected to a trapped cell via an extracellular buffer or intracellular fluid. Since the adsorption part S is composed of a single glass substrate 24, it is possible to form a highly resistant seal against the cell membrane of the cell T. Therefore, when performing electrophysiological measurement of cells, a conventionally known patch clamp method can be applied. At this time, the diameter of the hole constituted by the first end portion 21a of the fine hole 21 constituting the suction portion S is made smaller than the diameter of the hole of the conventional patch pipette or the like (about 2 to 4 μm). Electrophysiological measurement with higher accuracy can be performed.
In addition, the electrodes 26 and 27 may be disposed in another flow path that communicates with the first flow path 22 and the second flow path 23.

As described above, the first end portion 21a of the fine hole 21 is formed by opening the first flow path 22 into which the fluid Q containing the fine particles T flows by sucking the fine hole 21 from the outside of the base material 4. The fine particles T can be adsorbed and captured on the adsorption part S. Since the adsorption | suction part S is comprised with the single member, there is no joint and there is substantially no level | step difference. For this reason, the trapped fine particles T can be sufficiently adhered to the adsorbing portion S, the trap state can be stabilized, and the state can be continued. Therefore, observation of the fine particles T is easy. Furthermore, when the fine particles T are microorganisms or cells, the electrophysiological measurement can be performed with high accuracy.

FIG. 21 shows a state in which the fine holes 1 in the substrate 10 according to the present invention capture the fine particles T. By sucking the fluid Q from the second opening 1 b of the micropore 1, the fine particles T contained in the fluid Q are captured by the adsorption portion S configured by the first opening 1 a of the micropore 1. .
Thus, since the micropore formed in the base | substrate concerning this invention forms the re-modification part 2 in the manufacturing process, and has improved the etching tolerance of the re-modification part 2 by heat processing, it is etched. The diameter of the opening of the fine hole 3 to be formed later can be reduced. For this reason, in the adsorption | suction part S comprised by the said opening part, there is no possibility of capture | acquiring several microparticles | fine-particles T, and it can capture only the single microparticles | fine-particles T.

On the other hand, the substrate 100 different from the present invention is formed after etching because the re-modified part 2 is not formed in the manufacturing process and the etching resistance of the re-modified part 2 is not increased by heat treatment. The diameter of the opening of the fine hole 103 is large. Since the opening is large, a plurality of fine particles T are adsorbed (FIG. 22). In this case, when observed from one direction (for example, the upper surface of the substrate 100), the fine particles T may be observed to overlap each other, and there is a problem that observation and experimental operations are difficult to perform.

According to the substrate of the present invention, fine particles can be adsorbed at the opening of the micropores (first end portion of the micropores) opened on the surface of the substrate. When a suction device is installed at the second end of the micropore and a fluid containing microparticles larger than the pore size of the micropore is sucked into the inside from the first end of the micropore, the microparticles larger than the pore size of the micropore are Since it does not enter the micropore, the microparticles are captured at the first end of the micropore.
The pore diameter of the first end portion (opening portion) of the micropore in the substrate of the present invention can be a nano-order (nm unit) or sub-micron order (unit less than μm) size. By adsorbing the fine particles at the first end, the single fine particles are easily adsorbed. That is, there is little possibility that a plurality of fine particles are simultaneously captured at the first end portion. Therefore, experiments such as measurement and observation are easily performed on the captured fine particles.

FIG. 23 is a graph showing the relationship between the major axis of the elliptical cross section and the heat treatment temperature characteristics when the cross section of the modified portion is elliptical in the substrate manufacturing method according to the present invention. In the graph of FIG. 23, the horizontal axis represents the heat treatment temperature, and the vertical axis represents the ratio of the major axis before and after the heat treatment (Db / Da). Here, Da is the major axis before heat treatment, and Db is the major axis after heat treatment. This graph shows experimental results. In the graph of FIG. 23, the solid line shows the case where the heat treatment temperature holding time is 5 minutes, and the two-dot chain line shows the case where the heat treatment temperature holding time is 30 minutes. Here, glass is used as the base material (base material), and the rate of temperature rise is about 50 ° C./min.

The major axis was constant at temperatures below the strain point, and showed a tendency to decrease at temperatures above the strain point.
In the present invention, by using a glass substrate (base material) and performing a heat treatment at a temperature equal to or higher than the strain point, the re-modification part, It is possible to eliminate or denature the structurally altered portion or the first portion of the modified portion.

That is, the time required for the step C or the step γ can be shortened by setting the temperature condition of the heating in the step C or the step γ described above to a temperature higher than the strain point. Therefore, the method for manufacturing a substrate according to the present invention is suitable in the case of manufacturing a large number of substrates.

The fine holes formed by the conventional method are formed in the removed region by etching away the entire modified portion. In contrast, the micropores manufactured by the method of the present invention described above eliminate or denature the first part of the re-modified part, the structurally modified part, or the modified part, and selectively select the remaining part. By etching away, it is formed in the removed region.

Therefore, according to the substrate manufacturing method according to the present invention, compared with the conventional method in which heat treatment is not performed on the re-modified part, the structurally modified part, or the modified part, after the modification by laser light. The area to be removed by etching can be reduced, and the opening (opening area) of the micropores formed in the substrate (base material) or the inner hole diameter can be reduced. That is, according to the above-described method of the present invention, it is possible to process the opening of the fine hole to be smaller than the processing limit by laser light irradiation and etching. That is, the method of the present invention can provide a substrate having a fine hole with an opening smaller than the processing limit by laser light irradiation and etching. Specifically, as described above, if the minor diameter of the opening of the micropores opened on the surface of the substrate is 1 μm or less, the cell has the ability to trap not only cells but also microorganisms smaller in size than the cells. A substrate is provided having micropores that can have

A substrate having micropores and a method for producing the substrate according to the present invention include a microfluidic device for trapping fine particles such as microorganisms or cells contained in water or air and performing various observations, analyzes, and measurements. Can be widely used in the production and use of

DESCRIPTION OF SYMBOLS 1 ... 1st (3rd) reforming part, 1a ... 1st end part (1st opening part) of 1st (3rd) reforming part, 1b ... 2nd of 1st (3rd) reforming part End (second opening), 2... First (third) re-modification part, 3... Micropore, 3 a... First end of micropore (first opening), 3 b. Second end (second opening), 4 ... base material, 6 ... periodic component, 7 ... structurally altered part, Q ... fluid, T ... fine particle (microorganism or cell), S ... adsorbing part, 21 ... micropore , 21a: first end portion (first opening portion) of the fine hole, 21b ... second end portion (second opening portion) of the fine hole, 22 ... first flow path, 22a ... side face of the first flow path, 22b ... lower surface of first flow path, 22c ... upper surface of first flow path, 23 ... second flow path, 23b ... lower surface of second flow path, 23c ... upper surface of second flow path, 24 ... base material, 25 ... member, 26 ... Electrode, 27 ... Electrode, 30 ... Substrate, U, K ... Laser L: first laser light, M: second laser light, E1, E2: polarization direction of laser light (electric field direction), Z: propagation direction of laser light, 100: substrate having fine holes, 103 ... fine hole, 103a ... first end part (first opening part) of fine hole, 103b ... second end part (second opening part) of fine hole, 104 ... substrate.

Claims (10)

A method of manufacturing a substrate having micropores,
By scanning the focal point of the first laser beam having a time width of picosecond order or less inside the substrate, the first modified portion and the second modified portion having etching selectivity are formed,
By scanning the focal point of the second laser light having a time width of picosecond order or less inside the base so as to overlap the first part of the first modified part and the first part of the second modified part, Forming a first re-modification part in which the reformed state of the first part of the first reforming part is modified and a second re-modification part in which the reformed state of the first part of the second reforming part is modified; ,
By heating the first re-modified part and the second re-modified part, the etching resistance of the first re-modified part and the second re-modified part is increased,
The first modified portion and the second modified portion other than the first remodified portion and the second remodified portion are removed by etching to form micropores in the substrate. A method for producing a substrate having micropores. A method of manufacturing a substrate having micropores,
In the inside of the substrate, the focal point of the second laser light having a time width of picosecond order or less is scanned to form a structurally altered portion with reduced etching resistance of the substrate,
By scanning the focal point of the first laser beam having a time width of picosecond order or less inside the base so as to partially overlap with the structurally altered portion, the structurally altered portion and the overlapping portion of the scanned region are overlapped. The third modified portion and the fourth modified portion having etching selectivity are formed in a region that should not be formed, and the etching resistance of the structurally modified portion is changed to a region that overlaps the structurally modified portion in the scanned region. Forming the third and fourth re-reformation parts,
By heating the third re-modified part, the fourth re-modified part, and the structurally altered part, the etching resistance of the third re-modified part, the fourth re-modified part, and the structurally altered part is improved. To raise
By removing the third modified portion and the fourth modified portion other than the third remodified portion, the fourth remodified portion, and the structurally altered portion by etching, micropores are formed in the substrate. A method for producing a substrate having micropores, wherein A method for producing a substrate having micropores according to claim 1 or 2,
A method of manufacturing a substrate having a microscopic hole, wherein the polarization direction of the first laser light and the polarization direction of the second laser light are different from each other. A method for producing a substrate having micropores according to any one of claims 1 to 3,
The method for producing a substrate having a microscopic hole, wherein an angle formed between the scanning direction of the first laser beam and the polarization direction of the first laser beam is greater than 88 ° and equal to or less than 90 °. A method for producing a substrate having micropores according to claim 1,
Production of a substrate having micropores, wherein the first re-modification part and the second re-modification part are formed along the longitudinal direction of the first reforming part and the second reforming part Method. A method for producing a substrate having micropores according to claim 2,
Production of a substrate having micropores, characterized in that the third re-modification part and the fourth re-modification part are formed along the longitudinal direction of the third reforming part and the fourth reforming part. Method. A method for producing a substrate having micropores according to claim 5 or 6,
The method for producing a substrate having fine holes, characterized in that an angle formed between the scanning direction of the second laser beam and the polarization direction of the second laser beam is 0 ° or more and 88 ° or less. A method for producing a substrate having micropores according to any one of claims 1 to 7,
A method for producing a substrate having micropores, wherein the irradiation intensity of the first laser light is less than a processing upper limit threshold and is equal to or higher than a processing lower limit threshold. A method for producing a substrate having micropores according to any one of claims 1 to 8,
The method for producing a substrate having micropores, wherein the heating temperature is equal to or lower than a temperature at which a viscosity of the material of the substrate reaches 10 ^11.7 [poise]. A substrate manufactured by the manufacturing method according to any one of claims 1 to 9,
The substrate having a micropore, wherein the micropore having an opening on the surface of the substrate has an elliptical shape and the minor axis of the opening is 1 μm or less.

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