JP2006330080A - Method for controlling cross-sectional shape of photosensitive resin pattern, electroforming die using the same, microchemical chip, dna chip, and mems product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for obtaining a desired cross-sectional shape as a cross-sectional shape of a fine groove pattern composed of a photosensitive resin material. <P>SOLUTION: In a method for forming a photosensitive resin pattern by using positive or negative photosensitive resins which are decomposed or hardened with light irradiation, and for forming the groove pattern composed of these photosensitive resins on a substrate with exposure and development, wherein the pattern is to be used for a flow channel of a microchemical chip, a chip for DNA analysis, a resist for chemical etching, and a resist for dry etching and so on, the cross-sectional shape of the photosensitive resin groove pattern is controlled to have a desired value by using proximity exposure as an exposing method, and exposure-developing by selecting a distance 7 between a photomask 3 and the substrate 9 with the photosensitive resin 8 applied thereto or by changing the distance 7 between the substrate and the photomask over time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a groove pattern is formed with a photosensitive resin by exposure and development using a photomask of a photosensitive resin. It belongs to the technical field of so-called photoprocesses used for dry etching resists and the like.

  The current microchemical chip forms a fine groove pattern on the substrate, introduces a small amount of multiple reactive species involved in the chemical reaction into the groove pattern, and chemically synthesizes, separates, and extracts within the groove pattern. A chip having a fine groove pattern of μm size in a substrate, which can perform chemical analysis and the like. When these microchemical chips are connected, not only single chemical synthesis, separation, extraction and chemical analysis, but also multistage chemical synthesis and analysis processes can be realized in a small continuous microchemical chip. . Such a microchemical chip is also called a microchemical system or μ-TAS (micro-Total Analysis System).

  Microchemical chips can also be applied to DNA analysis and protein synthesis in the bio field, which is called a DNA analysis chip. The DNA analysis chip is used for injecting a DNA fragment sample into a fine groove pattern and measuring the length of the DNA by electrophoresis or analyzing the concentration of the DNA. The DNA analysis chip is also applied to DNA analysis of genetically modified crops such as corn. In recent years, it has become possible to determine whether a genetically modified plant is not a plant by using a DNA analysis chip.

  Further, when a catalyst such as palladium is applied to the inner wall of these fine groove patterns, the reaction at the interface between the groove inner wall and the reactive species is promoted, so that it can be used as a high-speed reaction channel in a minute space, a so-called microreactor. As described above, the application of the groove pattern to the chemical field and the bio field is expanding year by year, and for this reason, establishment of a technique for forming a finer groove pattern is required.

  Currently, fine groove patterns are made by dry etching such as glass and quartz. This glass or quartz groove pattern forming process is to form a resist pattern for dry etching using a photo process, and to etch quartz or glass with CF4 gas or the like using this resist pattern. Therefore, there is a drawback that the microchemical chip and the DNA analysis chip are very expensive.

  For this reason, a microchemical chip using a polymer resin material as a substrate has recently been put into practical use. Microchemical chip manufacturing methods using this polymer resin material include a method of forming a groove pattern by pressing a die produced by electroforming against the polymer resin material, and forming a groove pattern directly using a photosensitive resin material. There are ways to do it. In the electroforming method, a groove pattern made of a photoresist is first formed on a glass substrate, and then a conductive thin film called a seed layer is formed on the front surface of the pattern by vapor deposition. A mold is manufactured by casting an electroplating layer inside. This so-called technique is called an electroforming technique. In this technique, the shape of the cross section of the groove wall in forming the photoresist groove pattern is important.

  FIG. 1 shows a cross section in which resin molding is performed by pressing against a polymer resin material 2 with an electroforming mold 1. As the polymer resin material, a thermoplastic resin material or a photosensitive resin material is usually used. FIG. 1A shows an example in which the side wall of the electroformed mold section is vertical. A feature of the vertical cross-sectional mold is that the cross-sectional area of the flow path of the microchemical chip is large, but on the other hand, it is difficult to release the electroformed mold from the polymer resin material. This is because the electroformed mold is pressed against a polymer resin material such as a thermoplastic resin at a temperature equal to or higher than the Tg (glass transition temperature) of the resin material, and then the mold is released after the molding is completed. At the stage, the mold release stress works only in the shearing direction on the groove wall surface. FIG.1 (b) has shown the case where the inclination angle was provided in the cross section of the electroforming metal mold | die. In the cross section having this inclination angle, in the mold release after the molding of the polymer resin material, the release stress acts also in the direction perpendicular to the groove wall surface. It becomes easy. In order to obtain an inclined cross section as shown in FIG. 1B, the photoresist pattern for manufacturing the electroformed mold must be inclined as described above. Thus, in the manufacture of an electroforming mold, it is very important to control the cross-sectional shape of the fine groove pattern for depositing electroplating.

In forming a fine groove pattern such as a microchemical chip, the cross-sectional shape of the inner wall of the groove pattern is very important as shown in the above example of an electroforming mold. In addition to electroforming molds, there is a method in which a fine groove pattern is formed directly from a photosensitive polymer resin material, and this fine groove pattern is used as a microchemical chip as it is. Shape is equally important. Since this method does not require an intermediate step such as the production of an electroforming mold, it has a feature that a microchemical chip or the like can be manufactured at a low cost.
In this direct groove pattern forming method using a photosensitive polymer resin material, a photomask is first created, and then the photomask is applied to a substrate coated with a photosensitive resin material or a substrate made of a photosensitive resin material. By irradiating with light such as ultraviolet rays, the photosensitive resin material is photocured or photodecomposed to form a fine groove pattern, which is used as it is for a microchemical chip, etc. is there. At this time, there are two methods for arranging the photomask: a contact exposure method in which exposure is performed by bringing the photomask into contact with the substrate, and a proximity exposure method in which the mask is brought close to a certain distance on the substrate. In the contact mask exposure method, since the photomask is brought into direct contact with the substrate, there is a drawback that resin and foreign matters are likely to adhere to the mask, while the same pattern shape as the mask shape can be easily obtained. The proximity exposure method has no problem of foreign matter adhesion, but the boundary between the light transmitting portion and the light blocking portion of the mask may be less sharp than the contact mask exposure method due to scattered light or diffracted light. , Etc.

In a method for forming a fine groove pattern directly from a photosensitive resin material, a method for obtaining a desired cross-sectional shape of a groove pattern is disclosed in Patent Document 1 below.
In this Patent Document 1, a fine deformed pattern composed of a part that can transmit light and a part that cannot transmit light is arranged at the boundary between the light transmitting part and the light blocking part of the photomask. As a result, the amount of light transmitted through the irregular pattern forming portion at the boundary portion is reduced, so that the curing or decomposition of the photosensitive resin material is delayed. This makes it possible to obtain an inclined cross section on the wall surface of the photosensitive resin material located at the boundary.

  Further, in Patent Document 2, after a photoresist made of a photosensitive resin material is applied on a substrate, the photoresist pre-baking temperature is partially changed and heated, and then a photomask is placed and exposed to light reaction. The cross-sectional shape of the fine groove pattern made of the polymer photosensitive resin is made uneven.

  In any of the above two patent documents, it is very difficult to control the cross-sectional shape of a fine pattern made of a polymer resin material to a desired shape. That is, in Patent Document 1, it is necessary to confirm the relationship between the deformed pattern at the boundary and the cross-sectional shape by experiment, and determine the shape of the deformed pattern through trial and error. Moreover, in patent document 2, it is very difficult to change partially in the range of the photosensitive resin to which the pre-baking temperature is applied, from the viewpoint of the heat conduction relationship and the fine heating technique, and in the formation of the fine groove pattern, There are problems such as being nearly impossible.

In microchemical chips and DNA analysis chips, it is very important to control not only the slanted cross-sectional shape of the fine pattern made of a photosensitive resin material, but also the cross-sectional shape of the fine groove pattern, which is required in the electroforming mold manufacturing method. It is. In the fine groove pattern that becomes the reaction field of the reactive species, it is necessary to design a cross-sectional shape in accordance with the reduction of the moving friction coefficient of the fluid to be injected, the securing of the area of the reaction field, the ease of applying the reaction catalyst, and the like. Moreover, in the display and lighting fixture using LED, selection of the angle of a reflecting mirror is important for obtaining the maximum reflectance in a certain direction.
The present invention provides a method for controlling the cross-sectional shape of a fine groove pattern made of a polymer photosensitive resin, which is different from the invention described in the above patent document.
JP 2001-133957 A JP2002-343705

The problem to be solved by the present invention is to provide a method for obtaining a cross-sectional shape of a fine groove pattern made of a photosensitive resin material into a desired cross-sectional shape. As described above, a microchemical chip and a DNA analysis chip require a cross-sectional shape design corresponding to a decrease in the coefficient of moving friction of the fluid to be injected, securing a reaction field area, and ease of applying a reaction catalyst. Yes.
The desired cross-sectional shape includes an inclination, a circular shape (pan bottom), a step (step shape), a reverse taper (overhang shape), and a pipe line. The present invention provides an industrial and simple method for obtaining these desired cross-sectional shapes using a proximity exposure system with a single photomask.

The effects of the invention are as follows.
1) The cross-sectional shape of the wall surface of the fine groove pattern made of a photosensitive resin material can be controlled to a desired shape by one photo process.
2) The desired cross-sectional shape of the sidewall of the fine groove pattern can be obtained by an industrial and inexpensive process.
3) Since the groove (pipe) having a shape in which the upper part of the pattern is closed can be formed by a single photo process, the step of closing the upper part of the groove such as lamination, which has been performed in a separate process, can be omitted after the conventional groove pattern formation. .
4) The performance of separation, extraction, reaction rate, analysis, analysis, etc., such as a microchemical chip and a DNA analysis chip can be improved.
5) The reflecting mirror shape of the LED can be processed into an optimum shape for obtaining the maximum reflectance.
6) Others It is possible to optimize the cross-sectional structure of processing in MEMS (Micro Electro Mechanical System).

  The best embodiment will be described with reference to FIG. FIG. 2 shows a cross section of an exposure portion in which a photodecomposition type positive photosensitive resin 8 is applied on a substrate 9 and a photomask 3 is disposed immediately above the substrate 9 and exposed by proximity exposure. . In the proximity exposure method, the exposure between the photomask 3 and the positive photosensitive resin on the substrate, that is, the proximity exposure gap 7 is usually performed in the range of 0 to 800 μm. Among them, the proximity exposure gap 0 is called a contact exposure method. A method in which the photomask is moved away from the photosensitive resin surface and focused using a lens for exposure is called a projection exposure method. As described above, the advantage of the proximity exposure method is that it is possible to prevent resin adhesion to the mask and foreign matter adhesion.

  The inventors have found that by appropriately selecting and setting an exposure gap in this proximity exposure system, the cross section of the groove pattern made of a photosensitive resin can be set to a desired inclination angle. That is, for example, ultraviolet rays 6 entering from the light transmitting portion 4 of the photomask are irradiated to the positive photosensitive resin to photodecompose the positive photosensitive resin. At this time, between the photomask and the positive photosensitive resin. Thus, light diffraction and scattering occur, and the amount of light continuously decreases at the boundary between the light transmission part 4 and the light blocking part 5 as compared with the light transmission part. As a result, it has been found that the boundary between the light transmitting portion 4 and the light blocking portion 5 becomes a groove pattern cross section 10 having an inclined structure developed on the surface side of the photosensitive resin. FIG. 3 shows a cross section of a groove pattern of a photosensitive resin obtained by developing after completion of exposure. The inclination angle 11 of the groove pattern cross section 10 shown in FIG. 3 can be changed by selecting the proximity gap. FIG. 4 shows a relationship diagram between the proximity gap 11 and the inclination angle 11.

  As shown in FIG. 4, the exposure gap and the inclination angle of the groove pattern cross section are in a completely inverse relationship. Therefore, it is possible to obtain a desired inclination angle of the groove pattern cross section by selecting an exposure gap in proximity exposure. As described above, for example, in the manufacture of a mold for electroforming, the cross-sectional shape of the electroforming mold formed by electroplating such as nickel becomes an inclined cross section by inclining the cross-sectional shape of the groove pattern. Therefore, mold release after resin processing by an electroforming mold becomes easy.

  Further, by continuously changing the exposure gap in time, it is possible to obtain not only a linear inclined section shown in FIG. 4 but also a curved section or a section formed by a straight line and a curved line. Furthermore, when a photo-curing negative type is used for the photosensitive resin, it is possible to obtain a reverse tapered cross-sectional shape or a tubular pattern in which the upper part of the groove pattern is closed, that is, a closed conduit. These will be described in the embodiment step by step below.

Example 1 will be described with reference to FIG. FIG. 3 shows a cross section in which exposure is performed with a photomask fixed to a certain gap 7 in the proximity exposure method. In Example 1, the exposure gap was fixed to 150, 300, and 600 μm, respectively, and an exposure experiment was performed using g-rays having a wavelength of 436 nanometers. As the photosensitive resin, PMMA (polymethyl methacrylate), which is a photodegradable positive resist, was used. The thickness of the photosensitive resin was 30 μm. FIG. 5 shows a cross-sectional photograph of a groove pattern obtained by exposure and development under these conditions, using an electron microscope. The pattern is a long groove-shaped pattern developed toward the surface of the photosensitive resin having a certain width and depth.
As shown in FIG. 5, as a result of the experiment, it was found that groove pattern cross sections having inclination angles of 82 °, 78 °, and 62 ° were obtained at exposure gaps of 150, 300, and 600 μm, respectively. It can be seen that, under these three exposure gap conditions, the exposure gap and the tilt angle are in an inversely proportional relationship.

FIG. 6 shows the experimental results obtained by further changing the exposure gap to determine the relationship between the exposure gap and the tilt angle. FIG. 6 shows the results of experiments conducted by changing the pattern width of the opening (light transmitting portion) of the photomask to three types of 10, 30, and 60 μm. As shown in FIG. 6, the exposure gap and the tilt angle are in a completely inverse relationship. In addition, it can be seen that the inclination angle is determined solely by the exposure gap in proximity exposure, regardless of the pattern width of the opening of the photomask.
As described above, by using a positive photosensitive resin and changing the exposure gap in proximity exposure, the inclination angle of the cross section of the fine groove pattern obtained by exposure and development can be controlled to a desired value. It is.

  A second embodiment will be described with reference to FIG. FIG. 7 shows an embodiment in which the groove pattern cross section is curved using PMMA which is a positive photosensitive resin similar to that in the first embodiment. For exposure, g-line with a wavelength of 436 nm was used as in Example 1. Similar to the first embodiment, the curved groove pattern shape is obtained by continuously moving the photomask in proximity exposure upward from the substrate side after a certain exposure time has elapsed. For example, when the exposure gap is continuously moved to 600 μm along the movement profile of the photomask within an exposure time of 5 minutes, the cross section shown in FIG. 7 is obtained. FIG. 8 shows an exposure profile. The movement of the photomask is performed using, for example, a linear motor that is programmed and input the profile shown in FIG. In the profile of FIG. 8, the exposure is long in the center of the groove pattern, and the exposure in the groove width direction is performed along the profile. Therefore, the cross section of the groove pattern obtained by exposure and development has a curved shape as shown in FIG.

  A third embodiment will be described with reference to FIG. FIG. 9 shows an example in which the groove pattern cross section is discontinuous using PMMA, which is the same positive photosensitive resin as in Example 2. For exposure, g-line with a wavelength of 436 nm was used as in Example 1. This groove pattern shape is obtained by moving the photomask in proximity exposure linearly upward from the substrate side after a certain exposure time and holding it. For example, the exposure gap is held at 0 μm (contact exposure) for 3 minutes, and then the mask is moved to 600 μm and exposed for 3 minutes. FIG. 10 shows the movement profile of the photomask at this time. The photomask is moved by using, for example, a linear motor that is programmed and inputted with the profile shown in FIG. In the profile of FIG. 10, the exposure time is long in the center of the groove pattern and short in the groove wall direction. Therefore, the cross section of the groove pattern obtained by exposure and development has the shape shown in FIG.

  A fourth embodiment will be described with reference to FIG. In Example 4, PMMA, which is the same positive photosensitive resin as in Example 2, was used. The cross section of the groove pattern was shaped to swell inside the groove opposite to that in Example 2. For exposure, g-line having a wavelength of 436 was used as in Example 1. This groove pattern shape is obtained by continuously moving the photomask in proximity exposure upward from the substrate side. FIG. 12 shows the movement profile of the photomask at this time. The movement of the photomask is performed using, for example, a linear motor that is programmed and input the profile shown in FIG. In the profile of FIG. 12, the exposure time is long in the center of the groove pattern and continuously shortens in the groove wall direction. Therefore, the cross section of the groove pattern obtained by exposure and development has the shape shown in FIG. There are two methods for moving the photomask: a method of moving the photomask with respect to the substrate to which the photomask is fixed, and a method of moving the substrate with the photomask fixed, but either method may be used.

  Example 4 will be described with reference to FIG. FIG. 13 shows an embodiment in which a negative photosensitive resin (photo-curing type) PMMA different from that in Embodiment 4 is used and the cross section of the groove pattern is overhanged. For exposure, i-line having a wavelength of 365 nm was used. This groove pattern shape can be obtained by exposing the photomask 3 in proximity exposure to a fixed position. For example, as in Example 1, a photomask is fixed at a position 600 μm from the substrate and exposed for 6 minutes. As a result, the light passing through the mask circulates also inside the mask pattern due to light diffraction, so that the groove pattern obtained by exposure and development has a shape overhanging toward the opening as shown in FIG. .

  Example 6 will be described with reference to FIG. FIG. 14 shows a cross section of the groove pattern in which the upper part of the groove pattern is closed. This shape can be obtained by using a negative photosensitive resin as in Example 4 and fixing the exposure mask to the upper part of Example 5 and exposing. When a liquid styrene monomer is blended with PMMA and a solvent-free type photosensitive resin is used for the photosensitive resin, the photosensitive resin in the central portion of the groove that is not photocured by development after exposure flows and is removed. The In this example, the groove wall is linear, but when the mask is moved continuously in time by proximity exposure, it is the same as the groove wall shape of Examples 2, 3, and 4, and the upper part is closed. It is possible to obtain a groove pattern.

  The industrial application field of the present invention is a microchemical chip, a DNA chip, a MEMS, and the like, and provides a groove pattern forming method that can be performed using a conventional photo process. Also included are microchemical chips, DNA chips, MEMS, etc., manufactured using them. In the present invention, only the groove pattern has been described, but it goes without saying that the present invention can also be applied to the formation of a convex pattern.

Cross section of electroforming mold Proximity exposure method (cross section) Cross section of groove pattern (Example 1) Relationship between inclination angle of groove pattern and proximity exposure gap Groove pattern shape (SEM photo) Relationship between inclination angle of groove pattern and proximity exposure gap (data) Groove pattern cross section (Example 2) Photomask movement profile Cross section of groove pattern (Example 3) Photomask movement profile Cross section of groove pattern (Example 4) FIG. 12 Photomask Movement Profile (Example 4) Cross section of groove pattern (Example 5) Cross section of groove pattern (Example 6)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electroforming mold 2 Positive type photosensitive resin 3 Photomask 4 Light transmission part 5 Light blocking part 6 Ultraviolet light 7 Proximity exposure gap 8 Negative photosensitive resin 9 Substrate 10 Groove pattern cross section

Claims (6)

  In a method of forming a groove pattern made of these photosensitive resins on a substrate by exposure and development using a positive or negative photosensitive resin that decomposes or cures by light irradiation, proximity exposure is used as an exposure method. A groove made of a photosensitive resin, characterized in that the cross-sectional shape of the groove pattern is controlled by setting a gap between a photomask and a photosensitive resin-coated substrate, or a photomask and a photosensitive resin substrate. Pattern formation method.   The cross section of a groove pattern made of a photosensitive resin according to claim 1, wherein an optimum gap between the photomask and the substrate in proximity exposure is set in advance, exposure is performed in the set constant gap, and development is performed thereafter. A method for forming a groove pattern for producing an electroforming mold, wherein the shape is controlled.   2. A cross-sectional shape of a groove pattern made of a photosensitive resin, wherein an optimum gap between a photomask and a substrate in proximity exposure is set in advance, exposure is performed in the set constant gap, and development is performed thereafter. Electroformed mold manufactured using a groove pattern with controlled   2. A cross section of a groove pattern made of a photosensitive resin, wherein an optimum gap between a photomask and a substrate in proximity exposure is set in advance, exposure is performed in the set constant gap, and development is performed thereafter. Microfabricated products such as microchemical chips, DNA chips, and MEMS with controlled shapes.   In a method of forming a groove pattern made of these photosensitive resins on a substrate by exposure and development using a positive or negative photosensitive resin that decomposes or cures by light irradiation, proximity exposure is used as an exposure method. Exposure is performed while temporally changing a gap between a substrate coated with a photomask and a photosensitive resin, or between a photomask and a substrate made of a photosensitive resin, and the cross-sectional shape of the groove pattern is controlled. , Method for forming photosensitive resin groove pattern. In a method of using a positive or negative photosensitive resin that decomposes or cures by light irradiation and forms a groove pattern made of these photosensitive resins by exposure and development, proximity exposure is used as an exposure method, and a photomask Microchemicals manufactured using a method that controls the cross-sectional shape of the groove pattern by performing exposure while changing the gap between the photosensitive resin-coated substrate or the photomask and the photosensitive resin substrate over time. Microfabricated products such as chips, DNA chips, and MEMS.

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