JP2006189581A - Method for forming microstructure, and microstructure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a microstructure for easily forming a three-dimensional microstructure without requiring relative movement of a mask and a substrate. <P>SOLUTION: Since an exposure mask 300 having a first exposure light transmitting region r1 which transmits exposure light R from a light source and a second exposure light transmitting region r2 where the transmittance for the exposure light is lower than that of the first exposure transmitting region r1 is used, the distribution of exposure light quantity (light energy) can be controlled to continuously change without relatively moving a substrate 1 having a resist film 2 formed thereon and the exposure mask 300, and exposure with a depth corresponding to the distribution of the exposure light quantity (light energy) can be carried out between an exposure region d1 and an exposure region d2 of the resist layer 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fine structure forming method and a fine structure, and more particularly to a fine structure forming method and a fine structure capable of easily forming a three-dimensional fine structure.

  In recent years, research on a microfabrication technique for forming an extremely fine structure by applying a manufacturing technique of a semiconductor integrated circuit device has become active. Among them, the LIGA (Lithograph Galvanforming Unformation) method for forming a fine structure having a high aspect ratio by deep lithography using X-rays and electrolytic plating is particularly attracting attention. Patent Document 1 listed below discloses an example of a method for forming a fine structure based on the LIGA method.

  Specifically, when a microstructure having a three-dimensional structure is formed on a substrate, a lithography technique is applied to a material to be exposed formed on the substrate by using a mold corresponding to the shape of the microstructure. A fine structure having a three-dimensional structure made of a plating material is formed on the substrate by performing plating treatment by an electrolytic plating technique in a mold made of the material to be exposed and removing the mold.

According to the method for forming a fine structure disclosed in Patent Document 1 below, when forming a mold having a complicated shape, the X-ray mask is finally moved relative to the substrate. The X-ray energy distribution in a plane parallel to the plane of the material to be exposed as a mold is controlled so as to continuously change, and processing is performed at a depth corresponding to the X-ray energy distribution in each part of the material to be exposed. It is possible.
JP 2000-35500 A

  However, according to the mold forming method disclosed in Patent Document 1, a mechanism for moving the X-ray mask relative to the substrate is required. Therefore, an increase in cost in forming a fine structure cannot be avoided due to a complicated apparatus configuration and complicated positioning control between the X-ray mask and the substrate.

  Therefore, the present invention has been made to solve the above-described problems, and does not require relative movement between the mask and the substrate, and can be used to easily form a three-dimensional microstructure. It is to provide a forming method and a fine structure.

  In order to solve the above problems, in the method for forming a microstructure according to the present invention, a first region patterned with a light shielding material having a high absorption rate with respect to exposure light from a light source, and the first region A step of preparing an exposure mask comprising a second region patterned with a light-shielding material having a lower absorption rate, a step of forming a resist layer on the substrate, and using the exposure mask on the substrate By exposing the formed resist layer, the first exposure area reaching a first depth by exposure light transmitted through the first area, and the first exposure by exposure light transmitted through the second area. Forming a second exposure region reaching a second depth shallower than the region (d1), and removing the first exposure region and the second exposure region from the resist layer to form a microstructure. And the process of I have. Moreover, in the fine structure based on this invention, it forms using the formation method of the fine structure mentioned above.

  As described above, the resist layer is exposed using the exposure mask including the first region and the second region whose exposure light transmittance is lower than that of the first region, so that the microstructure is finally formed. The exposure light exposure amount (light energy) distribution in a plane parallel to the plane of the resist layer can be controlled to change continuously, and the exposure light exposure light amount (light energy) distribution in each part of the resist layer can be controlled. Depth exposure is possible. As a result, an apparatus for moving the substrate and the exposure mask relative to each other becomes unnecessary, and it is possible to avoid an increase in cost in forming the fine structure.

  According to the fine structure forming method and the fine structure according to the present invention, a three-dimensional fine structure can be easily formed without relative movement of the mask and the substrate.

  Hereinafter, a method for forming a fine structure according to an embodiment based on the present invention will be described with reference to the drawings. First, with reference to FIGS. 1 to 5, a method for manufacturing a mask used in the method for forming a microstructure in the present embodiment will be described. 1 to 5 are FIGS. 1 to 5 (cross-sectional views) showing a mask manufacturing process.

(Manufacturing method of mask)
First, referring to FIG. 1, a silicon nitride (SiN) film 102 having a thickness of about 2 μm is formed on a silicon (Si) substrate 101 by using a CVD (Chemical Vapor Deposition) method. Next, an alumina (Al ₂ O ₃ ) film 103 having a thickness of approximately 0.1 μm, a tungsten nitride (WN) film 104 having a thickness of approximately 3 μm, and an aluminum having a thickness of approximately 0.1 μm are formed on the silicon nitride film 102. The (Al) film 105 is sequentially formed by sputtering.

  Next, referring to FIG. 2, the alumina film 103, the tungsten nitride film 104, and the aluminum film 105 are patterned by etching using a photolithography technique, so that the surface of the silicon nitride film 102 is exposed. An opening region width W1) is formed. Thereafter, the back surface processing is performed on the silicon substrate 101 using an alkali etchant such as KOH to complete the first exposure mask 100. The first exposure mask 100 has a first transmission region h1 that transmits exposure light and a first light shielding region s1 that surrounds the first transmission region h1.

Next, referring to FIG. 3, a silicon nitride (SiN) film 202 having a thickness of about 2 μm is formed on the silicon (Si) substrate 201 by using the CVD method. Next, on the silicon nitride film 202, an alumina (Al ₂ O ₃ ) film 203 having a thickness of about 0.1 μm, a titanium (Ti) film 204 having a thickness of about 2 μm, and aluminum ( The Al) film 205 is sequentially formed by sputtering.

  Next, referring to FIG. 4, the alumina film 203, the titanium film 204, and the aluminum film 205 are patterned by etching using a photolithography technique, and an opening region h <b> 2 (opening where the surface of the silicon nitride film 202 is exposed) Region width W2: W1> W2)) is formed. Thereafter, the back surface processing is performed on the silicon substrate 201 using an alkali etchant such as KOH to complete the second exposure mask 200.

  The second exposure mask 200 includes a second transmission region h2 that transmits exposure light, and a second light shielding region s2 that surrounds the second transmission region h2 and has a lower absorptance than the first light shielding region r1. Become.

  Next, referring to FIG. 5, the aluminum film 205 side of the second exposure mask 200 is bonded to a predetermined position of the first exposure mask 100 on the back surface side of the silicon substrate 101. Thereby, the exposure mask 300 in this Embodiment is completed. In addition, in bonding of the 1st exposure mask 100 and the 2nd exposure mask 200, as shown in FIG. 5, the 1st transmission region h1 of the 1st exposure mask 100 and the 2nd transmission region h2 of the 2nd exposure mask 200 are shown. The first region r1 is formed by the path of the exposure light passing through the first region, and the second region is formed by the path of the exposure light passing through the first transmission region h1 of the first exposure mask 100 and the third transmission region h3 of the second exposure mask 200. The first exposure mask 100 and the second exposure mask 200 are positioned so that r2 is formed.

(Exposure step)
Next, a resist film exposure step using the exposure mask 300 having the above-described configuration will be described with reference to FIGS. 6 and 7 are first and second diagrams (cross-sectional views) showing a resist film exposure step.

  First, referring to FIG. 6, a resist film 2 is formed on a substrate 1. Thereafter, the exposure mask 300 is positioned with respect to the resist film 2. Next, the resist film 2 is irradiated and exposed to the exposure light R that has passed through the exposure mask 300 on the substrate 1. As the exposure light, various light sources can be used, but it is preferable that the light emitted from the light source does not spread, so synchrotron radiation (SR), laser light, electron beam light (EB), etc. It is preferable to use it. In the present embodiment, synchrotron radiation (SR) is used.

  Here, the exposure light that has passed through the exposure mask 300 can be divided into exposure light R1 that has passed through the first region r1 and exposure light R2 that has passed through the second region r2. Since the transmittance of the second region r2 is lower than the transmittance of the first region r1, there is an intensity distribution that the exposure amount (light energy) of the exposure light R2 is lower than the exposure amount (light energy) of the exposure light R1. It is formed.

  As a result, as shown in FIG. 6, the exposure region d1 of the resist film 2 exposed by the exposure light R1 that has passed through the first region r1 is exposed to a depth position (L1) that reaches the surface of the substrate 1. become. On the other hand, the exposure region d2 of the resist film 2 exposed by the exposure light R2 that has passed through the second region r2 is not exposed to the depth position (L1) reaching the surface of the substrate 1, and the intermediate depth of the resist film 2 is reached. The exposure is performed up to the position (L2). Next, as shown in FIG. 7, the resist film 2 is developed to remove the exposed regions d1 and d2, thereby completing a resist structure 3 having an opening 2a as a fine structure. . Thereby, a microstructure having a complicated shape can be obtained. Here, with reference to FIG. 8, at this stage, the substrate 1 is removed with an aqueous KOH solution to obtain a resist structure 3 as a fine structure made of only a resist layer. And can be used as a prototype test model for inkjet printer nozzles.

(Fine mold forming process)
Next, a process for forming a fine mold as a fine structure using the resist structure 3 will be described with reference to FIGS. FIGS. 9 and 10 are FIG. 1 (cross-sectional view) and FIG. 2 (perspective view) showing the formation process of the fine mold.

  First, referring to FIG. 9, plating 4 is applied to resist structure 3 by an electrolytic plating technique. Thereafter, referring to FIG. 10, substrate 1 is removed using an aqueous KOH solution, and resist film 2 is removed by ashing to complete fine mold 4 as a fine structure made of plating 4. The fine mold 4 in the present embodiment has a height (H) of about 80 μm, a thin diameter (D1) of about 3 to 5 μm, and a thick diameter (D2) of about 60 μm. .

(Action / Effect)
As described above, according to the fine structure forming method of the present embodiment, the first region r1 that transmits the exposure light R from the light source, and the second region r2 that has a lower exposure light transmittance than the first region r1. By using the exposure mask 300 comprising the exposure mask 300, the exposure light exposure amount (light energy) distribution is continuously changed without relatively moving the substrate 1 on which the resist film 2 is formed and the exposure mask 300. The exposure can be controlled and exposure between the exposure region d1 and the exposure region d2 of the resist layer 2 can be performed at a depth corresponding to the exposure light amount (light energy) distribution.

  In the above embodiment, the case of a mushroom mold is shown as an example of the cross-sectional shape of the fine mold 4, but it is possible to form a fine mold having various shapes such as a trapezoidal shape and a triangular shape. .

  Further, although the case where the second region r2 is provided so as to surround the first region r1 in the exposure mask 300 has been described, the arrangement relationship between the first region r1 and the second region r2 is to be obtained. The structure is appropriately changed according to the shape of the microstructure (resist structure, fine mold).

(Other forms of exposure mask)
As the configuration of the exposure mask 300, a configuration in which the first exposure mask 100 and the second exposure mask 200 are bonded is shown. However, the following exposure mask 400 and exposure mask 600 are used as other exposure masks. Is also possible. First, a method for manufacturing the exposure mask 400 will be described with reference to FIGS.

Referring to FIG. 11, a silicon nitride (SiN) film 402 having a thickness of about 2 μm is formed on a silicon (Si) substrate 401 having a thickness of about 1 mm by using a CVD method. Next, an alumina (Al ₂ O ₃ ) film 403 having a thickness of approximately 0.1 μm, a tungsten nitride (WN) film 404 having a thickness of approximately 3 μm, and an aluminum having a thickness of approximately 0.1 μm are formed on the silicon nitride film 402. An (Al) film 405 is sequentially formed by a sputtering method.

  Next, the alumina film 403, the tungsten nitride film 404, and the aluminum film 405 are patterned by photolithography and dry etching to form an opening region h1 (opening region width W1) from which the surface of the silicon nitride film 402 is exposed. To do.

Next, referring to FIG. 12, an alumina (Al ₂ O ₃ ) film 406 having a thickness of about 2 μm and a thickness of about 2 are formed on the patterned surfaces of the alumina film 403, the tungsten nitride film 404, and the aluminum film 405. A 0.0 μm titanium (Ti) film 407 and an aluminum (Al) film 408 having a thickness of about 0.1 μm are sequentially formed by a sputtering method.

  Next, referring to FIG. 13, the alumina film 406, the titanium film 407, and the aluminum (Al) film 408 are patterned by a photolithography technique and a dry etching method, so that the surface where the surface of the silicon nitride film 402 is exposed is exposed. Region h2 (opening region width W2: W1> W2) is formed.

  Next, referring to FIG. 14, the back surface processing is performed on the silicon substrate 401 using an alkali etchant such as KOH to complete the exposure mask 400 having the first region r1 and the second region r2. For the exposure light, the tungsten nitride film 404 constitutes a first absorber having a high absorption rate, and the titanium film 407 constitutes a second absorber having a low absorption rate.

  Next, referring to FIG. 15, a PMMA is applied on a silicon substrate to form a resist substrate 500. A gap of about 100 μm is formed with respect to the resist substrate 500, and the exposure mask 400 is set in the vertical direction. To SR light is exposed. When the resist substrate 500 is developed using a MiBK developer after performing appropriate light exposure, a resist structure 500A having different patterns in the thickness direction as shown in FIG. 16 is formed.

Next, a method for manufacturing the exposure mask 600 in another embodiment will be described. First, referring to FIG. 17, a silicon nitride (SiN) film 502 having a thickness of about 2 μm is formed on a silicon (Si) substrate 501 having a thickness of about 1 mm by using a CVD method. Next, an alumina (Al ₂ O ₃ ) film 503 having a thickness of approximately 0.1 μm, a tungsten nitride (WN) film 504 having a thickness of approximately 3 μm, and an aluminum having a thickness of approximately 0.1 μm are formed on the silicon nitride film 502. An (Al) film 505 is sequentially formed by a sputtering method.

  Next, the alumina film 503, the tungsten nitride film 504, and the aluminum film 505 are patterned by a photolithography technique and a dry etching method to form an opening region h1 (opening region width W1) from which the surface of the silicon nitride film 502 is exposed. To do.

Next, referring to FIG. 18, an alumina (Al ₂ O ₃ ) film 506 having a thickness of approximately 0.1 μm and a thickness of approximately ₂ are formed on the patterning surfaces of the alumina film 503, the tungsten nitride film 504, and the aluminum film 505. A 0.0 μm titanium (Ti) film 507 and an aluminum (Al) film 508 having a thickness of about 0.1 μm are sequentially formed by sputtering.

  Next, referring to FIG. 19, the alumina film 506, the titanium film 507, and the aluminum film 508 are patterned by the photolithography technique and the dry etching method, so that the surface of the silicon nitride film 502 is exposed. Opening region width W2: W1> W2) is formed. Thereafter, with reference to FIG. 20, an aluminum (Al) film 509 having a thickness of about 0.1 μm is formed on the alumina film 506, the titanium film 507, and the aluminum film 508 by a sputtering method.

  Next, referring to FIG. 21, an aluminum (Al) film 509 is patterned by a photolithography technique and a dry etching method, and an opening region h3 where the surface of the silicon nitride film 502 is exposed (opening region width W3: W1>). W2> W3).

  Next, referring to FIG. 22, the back surface of the silicon substrate 501 is processed using an alkali etchant such as KOH, and an exposure mask having a first region r1, a second region r2, and a third region r3. 600 is completed. Note that the tungsten nitride film 504 constitutes a first absorber having a high absorptance for exposure light, the titanium film 507 constitutes a second absorber having an intermediate absorptance, and the aluminum film 509 is low. A third absorber having an absorptance is constituted.

  Next, referring to FIG. 23, PMMA is applied on a silicon substrate to form a resist substrate 700. A gap of about 100 μm is formed with respect to the resist substrate 700, the exposure mask 600 is installed, and the vertical direction is set. To SR light is exposed. When the resist substrate 700 is developed using the MiBK developer after the appropriate amount of light exposure, a resist structure 700A having different patterns in the thickness direction as shown in FIG. 24 is formed.

  In the exposure masks 300 and 400, the first region r1 patterned with a light shielding material having a high absorptance with respect to the exposure light from the light source, and a lower absorptance than the first region (r1). 2 shows a configuration for forming a second region r2 patterned with a light shielding material. In the exposure mask 600, the first region patterned with a light shielding material having a high absorptance with respect to exposure light from a light source. r1, a second region r2 patterned with a light shielding material having a lower absorptance than the first region r1, and a second region r2 patterned with a light shielding material having a lower absorptance than the second region r2. Although the structure for forming the three regions r3 is shown, a plurality of regions set so as to gradually decrease the absorption rate from the inside toward the outside are sequentially provided, so that the resist structure described above can be provided. Thus, it is possible to form an opening that approximates a conical shape.

  Accordingly, the above-described embodiment disclosed herein is illustrative in all respects and does not serve as a basis for limited interpretation. The technical scope of the present invention is not interpreted only by the above-described embodiments, but is defined based on the description of the claims. Further, all modifications within the meaning and scope equivalent to the scope of the claims are included.

  With the fine structure forming method and the fine structure according to the present invention, a fine structure used for a nebulizer, an inkjet printer nozzle or the like can be obtained.

It is FIG. 1 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in embodiment based on this invention. It is FIG. 2 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in embodiment based on this invention. It is FIG. 3 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in embodiment based on this invention. It is FIG. 4 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in embodiment based on this invention. It is FIG. 5 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in embodiment based on this invention. It is FIG. 1 (sectional drawing) which shows the exposure step of the resist film in the formation method of the microstructure in embodiment based on this invention. It is FIG. 2 (sectional drawing) which shows the exposure step of the resist film in the formation method of the microstructure in embodiment based on this invention. It is a figure (sectional drawing) which shows the resist structure in the formation method of the fine structure in embodiment based on this invention. It is FIG. 1 (sectional drawing) which shows the formation process of the fine structure in embodiment based on this invention. It is FIG. 2 (perspective view) which shows the formation process of the fine structure in embodiment based on this invention. It is FIG. 1 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in other embodiment based on this invention. It is FIG. 2 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in other embodiment based on this invention. It is FIG. 3 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in other embodiment based on this invention. It is FIG. 4 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the microstructure in other embodiment based on this invention. It is a figure (sectional drawing) which shows the exposure step of the resist film in the formation method of the fine structure in other embodiment based on this invention. It is a figure (sectional drawing) which shows the resist structure in the formation method of the fine structure in other embodiment based on this invention. It is FIG. 1 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the fine structure in other embodiment based on this invention. It is FIG. 2 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the fine structure in other embodiment based on this invention. It is FIG. 3 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the fine structure in further another embodiment based on this invention. It is FIG. 4 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the fine structure in other embodiment based on this invention. It is FIG. 5 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the fine structure in other embodiment based on this invention. It is FIG. 6 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the fine structure in further another embodiment based on this invention. It is FIG. 7 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the fine structure in further another embodiment based on this invention. It is FIG. 8 (sectional drawing) which shows the manufacturing process of the mask used for the formation method of the fine structure in other embodiment based on this invention.

Explanation of symbols

1 substrate, 2 resist film, 2a mold, 3 microstructure, 100 first exposure mask, 101, 201, 401, 501 silicon (Si) substrate, 102, 202, 402, 502 silicon nitride (SiN) film, 103, 203, 403, 406, 503, 506 Alumina (Al ₂ O ₃ ) film, 104, 404, 504 Tungsten nitride (WN) film, 105, 405, 408, 505, 508, 509 Aluminum (Al) film, 200 2nd Exposure mask, 300, 400, 600 Exposure mask, 407, 507 Titanium (Ti) film, 500, 700 resist substrate, 500A, 700A resist structure, d1, d2 exposure area, h1 first transmission area (opening area), h2 Second transmission region (opening region), h3 third transmission region (opening region), r1 first region, r2 second region, r3 Third region, R, R1, R2 exposure light, s1, s2 light shielding region.

Claims (6)

An exposure comprising a first region patterned with a light shielding material having a high absorptance with respect to exposure light from a light source, and a second region patterned with a light shielding material having a lower absorptance than the first region. Preparing a mask; and
Forming a resist layer on the substrate;
A first exposure region that reaches a first depth by exposure light transmitted through the first region by exposing the resist layer formed on the substrate using the exposure mask; and the second Forming a second exposure region that reaches a second depth shallower than the first exposure region by exposure light transmitted through the region;
Removing the first exposure region and the second exposure region from the resist layer to form a microstructure;
A method for forming a fine structure.   The method for forming a fine structure according to claim 1, wherein a light source that forms the exposure light is any one of synchrotron radiation light, laser light, and electron beam light. The exposure mask has a first exposure mask and a second exposure mask superimposed on each other,
The first exposure mask has a first transmission region and a first light shielding region surrounding the first transmission region,
The second exposure mask has a second transmission region, and a second light shielding region surrounding the second transmission region and having a lower absorptance than the first light shielding region,
The first exposure light transmission region is formed by a path of exposure light passing through the first transmission region of the first exposure mask and the second transmission region of the second exposure mask;
3. The second exposure light transmission region is formed by a path of exposure light passing through the first transmission region of the first exposure mask and the second light shielding region of the second exposure mask. 4. Method for forming a fine structure.   The exposure mask includes the second transmission region and the second light shielding region surrounding the second transmission region on the first transmission region and the first light shielding region surrounding the first transmission region. The method for forming a fine structure according to claim 1, wherein the structure has a structure in which and are formed. The material used for the first light shielding region is a material selected from the group consisting of Ta, W, Pt, Au, and Ag.
The material used for the second light-shielding region is a material selected from the group consisting of Ti, Cr, Mn, Fe, Ni, Cu, Al, and Si. A method for forming a microstructure described in 1.   A fine structure formed by using the fine structure forming method according to claim 1.

Images