JPH06170187A - Production of micro-filter - Google Patents

Abstract

PURPOSE:To simply and inexpensively produce a micro-filter consisting of a filter membrane having filter pores and a support structure. CONSTITUTION:A step forming a resist film 5 on a conductive substrate 6, a step exposing the resist film 5 to synchrotron radiation 1 through an X-ray mask 10 and eliminating a part of the resist film 5 to form a resist structure 25 and a step forming a mold on the basis of the resist structure 25 formed by exposure are provided. The X-ray mask 10 consists of a total absorber layer 4 sufficiently absorbing synchrotron radiation and a partial absorber layer 3 partially absorbing synchrotron radiation 1 to attenuate the same and the partial absorber layer 3 has the through holes corresponding to filter pares.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microfilter manufacturing method, and more particularly to a microfilter manufacturing method having a supporting structure.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing an example of a conventional microfilter. With reference to FIG. 4, this microfilter is composed of a filter membrane 37 having filter holes 38 and a support element 39.

Conventionally, a microfilter having such a structure has been manufactured through the following manufacturing steps, as disclosed in, for example, JP-A-63-200803.

First, a die for forming the supporting element and the filter membrane is manufactured by X-ray lithography and electroforming. A resin whose solubility is changed by high-energy radiation is injected into this mold, and the mold is demolded to form a film having a supporting element. The film is then partially exposed to high energy radiation through a mask. By removing the part where the solubility is increased by this irradiation,
Filter pores are formed in the membrane.

Thus, microfilters have been manufactured which consist of a filter membrane having filter pores and a support element.

[0006]

However, in the above-described manufacturing method, first, a mold having a supporting element is used to form a film having a supporting element, and then the high-energy radiation is irradiated again. Then, the filter pores were formed in the membrane. That is, the step of forming the support element and the step of forming the filter hole are separate.

Therefore, this conventional manufacturing method has problems that it is complicated and the manufacturing cost is high.

An object of the present invention is to solve the above-mentioned problems and to provide a method for easily producing a microfilter comprising a filter membrane having filter holes and a supporting structure at a low cost.

[0009]

The manufacturing method of the present invention comprises:
A method of manufacturing a microfilter comprising a filter film having filter holes and a supporting structure, the method comprising the steps of forming a resist film on a conductive substrate and exposing the resist film to synchrotron radiation through a mask. The mask includes a step of forming a resist structure by removing a part of the film and a step of making a mold based on the resist structure formed by exposure, and the mask is configured to sufficiently emit synchrotron radiation. It is characterized by comprising a total absorber layer that absorbs and a partial absorber layer that absorbs and attenuates a part of the synchrotron radiation, and the partial absorber layer has through holes corresponding to the filter holes.

Preferably, a part of the resist film which is removed by exposure is changed by changing the spectral range of the synchrotron radiation used for the exposure and changing the X-ray energy and the X-ray dose transmitted through the partial absorber layer. It is good to make the depth of the variable.

[0011]

In the manufacturing method according to the present invention, the resist film formed on a certain conductive substrate is irradiated with synchrotron radiation through a mask. This mask is composed of a total absorber layer that sufficiently absorbs the synchrotron radiation and a partial absorber layer that absorbs and attenuates part of the synchrotron radiation. Therefore, a resist structure having different heights can be obtained depending on the range exposed through the entire absorber layer and the range exposed through the partial absorber layer. That is, for example, when a positive resist film is used,
The areas exposed through the entire absorber layer form a resist corresponding to the support structure, while the areas exposed through the partial absorber layer form a resist corresponding to the filter film.

Further, the partial absorber layer is provided with a through hole. Therefore, a hole corresponding to the filter hole is formed in the portion of the resist film exposed through the through hole.

As described above, according to the manufacturing method of the present invention, the formation of the resist corresponding to the support structure and the formation of the resist corresponding to the filter film having the filter holes can be simultaneously performed.

Further, in the present invention, the spectral range of the synchrotron radiation to be irradiated is changed during the exposure.
When the peak wavelength of the spectrum becomes short, the X-ray energy and the X-ray dose transmitted through the partial absorber layer increase, and the resist film is deeply exposed. On the other hand, conversely, if the peak wavelength of the spectrum becomes a long wavelength, X that passes through the partial absorber layer
The linear energy and the amount of X are reduced, and the resist film is shallowly exposed. Therefore, by utilizing this characteristic,
The resist corresponding to the filter film formed by the area exposed through the partial absorber layer can be formed in an arbitrary thickness.

[0015]

FIG. 1 is a sectional view showing an exposure process in manufacturing a microfilter according to an embodiment of the present invention.

Referring to FIG. 1, a positive resist film 5 is applied and formed on a conductive substrate 6. The positive resist film 5 is irradiated with the synchrotron radiation light 1 through the X-ray mask 10.

The X-ray mask 10 comprises a mask support film 2 having sufficient transparency for the synchrotron radiation 1 used, a total absorber layer 4 for forming a resist corresponding to the support element, and a filter. And a partial absorber layer 3 for forming a resist corresponding to the film. Further, the partial absorber layer 3 is provided with a through hole 11. The absorber layer 4 absorbs all the synchrotron radiation 1. On the other hand, the partial absorber layer 4 absorbs and attenuates part of the synchrotron radiation light 1.

The synchrotron radiation 1 for irradiation
Changes the peak wavelength, thereby changing the X-ray energy and X-ray dose transmitted through the partial absorber layer 3,
The exposed depth of the resist is determined. Therefore,
The wavelength of the synchrotron radiation 1 is set so that the resist can be exposed to a desired depth.

FIG. 2 shows a resist structure 25 formed by exposing the synchrotron radiation 1 shown in FIG. 1 and then developing it to remove the portion irradiated with the synchrotron radiation 1. FIG.

Referring to FIG. 2, this resist structure 25
Is formed on the conductive substrate 6 and includes a supporting element corresponding portion 24 and a filter membrane corresponding portion 23 having a filter hole corresponding portion 21.

The support element corresponding portion 24 is a range where the synchrotron radiation 1 is irradiated through the whole absorber layer 4 of the X-ray mask 10, and the synchrotron radiation 1 is absorbed by the whole absorber layer 4. As a result, the resist remains without being removed and is higher than the other portions. The height of the support element corresponding portion 24 can be arbitrarily set by controlling the film thickness of the positive resist film formed on the conductive substrate 6. Further, the interval between the support element corresponding portions 24 can be set arbitrarily according to the shape of the X-ray mask 10.

On the other hand, the filter membrane corresponding portion 23
Is a range irradiated with the synchrotron radiation 1 through the partial absorber layer 3 of the X-ray mask 10. Since the synchrotron radiation 1 was partially absorbed by the partial absorber layer 3,
The resist has been removed to a predetermined depth. The depth to be deleted can be arbitrarily set by changing the spectral range of the synchrotron radiation 1 as described above. The control of the spectral range of the synchrotron radiation 1 is preferably performed by changing the magnetic field of the electron storage ring which is the generation source. In this way, the filter film corresponding portion 2 having a desired film thickness
3 is formed.

Further, the filter hole corresponding portion 21 provided in the filter film corresponding portion 23 is irradiated with the synchrotron radiation 1 through the through hole 11 provided in the partial absorber layer 3 of the X-ray mask 10. It is a range. Synchrotron radiation 1 is directly applied to the positive resist film 5,
The holes are formed by completely removing the resist.

Next, the resist structure 25 shown in FIG.
Then, the conductive substrate 6 is used as an electrode in the plating bath so as to be higher than the supporting element corresponding portion 24. Then, the conductive substrate 6 and the resist structure 25
After removing, the remaining plated portion becomes the mold. In this way, the mold is manufactured.

FIG. 3 is a sectional view showing a microfilter manufactured according to an embodiment of the present invention.

Referring to FIG. 3, this microfilter is composed of a filter membrane 7 having filter holes 8 and a support element 9.

The microfilter thus constructed can be manufactured by molding resin or ceramics or the like into the mold manufactured as described above.

Although the positive resist film is used in the above-mentioned embodiments, the present invention can be applied to the case where the negative resist film is used.

[0029]

As described above, according to the method of the present invention, a microfilter comprising a filter membrane having filter pores and a supporting structure can be easily manufactured at low cost.

Further, according to the method of the present invention, the distance between the support structures, the height of the support structures and the thickness of the filter membrane can be set arbitrarily. Therefore, it is possible to manufacture a microfilter that is sufficiently adapted to the characteristics required by the application and has optimum characteristics such as passage resistance or mechanical strength.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a microfilter according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a resist structure formed by the manufacturing process of FIG.

FIG. 3 is a cross-sectional view showing a microfilter manufactured according to an embodiment of the present invention.

FIG. 4 is a sectional view showing an example of a conventional microfilter.

[Explanation of symbols]

 1 synchrotron radiation 2 mask support film 3 partial absorber layer 4 total absorber layer 5 positive resist film 6 conductive substrate 7 filter film 8 filter hole 9 support element 10 X-ray mask 11 through hole 25 resist structure In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A method of manufacturing a microfilter comprising a filter film having filter holes and a support structure, the method comprising forming a resist film on a conductive substrate, and synchronizing the resist film with a mask. A step of forming a resist structure by exposing a part of the resist film to tron radiation, and a step of producing a mold based on the resist structure formed by the exposure. The mask comprises a total absorber layer that sufficiently absorbs the synchrotron radiation, and a partial absorber layer that absorbs and attenuates a portion of the synchrotron radiation, the partial absorber layer Has a through hole corresponding to the filter hole. 2. The resist removed by the exposure by changing the spectral range of the synchrotron radiation used for the exposure, and changing the X-ray energy and the X-ray dose transmitted through the partial absorber layer. The method for producing a microfilter according to claim 1, wherein the depth of a part of the membrane is variable.