JP2010194683A - Method of manufacturing microstructure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively and efficiently manufacture a high definition microstructure. <P>SOLUTION: A method of manufacturing a microstructure includes the preparation step of preparing a substrate with a corner section having an apex part and a side part; and the formation step of forming the microstructure with a wall 21a comprised of a circumferential edge portion by etching the apex part 15 while leaving the circumferential edge portion of the apex part 15. The formation step includes a coating treatment of forming a coating film continuously coating the apex part 15 and the side part 17; an etching treatment in which a protruded portion 34 is obtained by etching the coating film 33 until the apex part 15 is exposed, and by allowing a part of the coating film 33 covering the side part 17 to protrude beyond a bottom surface 15a of an etching recess formed by the etching; a second coating treatment of forming a second coating film 35 continuously coating the bottom surface 15a and the protruded portion 34; and a second etching treatment in which a film pattern 36 is obtained by etching the second coating film 35 until the bottom surface 15a is exposed, and by holding a part of the second coating film 35 coating the protruded portion 34, and the bottom surface 15a is etched using the film pattern 36 as a mask. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In recent years, MEMS (Micro Electro Mechanical Systems) have attracted attention. The MEMS is obtained by integrating mechanical element parts, actuators, sensors, electronic circuits, and the like on the same chip. Specific examples of MEMS include a head of an inkjet printer, a DMD (Digital Mirror Device) used for a pressure sensor, a gyroscope, a projector, and the like.

  A technique for forming a structure with a high aspect ratio (for example, Patent Document 1) is extremely important in manufacturing a fine structure included in a mechanical element part or the like of MEMS. Patent Document 1 relates to a processing method generally called a Bosch process. The Bosch process is a method of alternately performing an anisotropic etching process such as dry etching and a deposition process for depositing a passivation film made of a polymer thin film.

  Sidewalls exposed in the recesses formed by the etching process are protected by a passivation film formed by the deposition process. Then, the recess is deepened by performing the etching process again in a state where the side wall is protected by the passivation film. The passivation film suppresses side etching to a minimum level, and a high aspect ratio structure can be formed satisfactorily.

US Pat. No. 5,501,893

  Although it is considered that high-precision processing can be performed using the technique of Patent Document 1, there is a point that should be improved from the viewpoint of efficiently manufacturing a high-definition fine structure at low cost.

  In the technique of Patent Document 1, before performing the first etching process, a mask pattern is formed on the periphery of the recess formed by the etching process. A passivation film is formed on the mask pattern by a deposition process. This mask pattern is formed thick so that it can withstand a plurality of etching processes.

  Such a mask pattern is formed by using a photolithography method, a resist technique or the like cultivated in the semiconductor field or the like. As an exposure method used in the photolithography method, a stepper method for transferring a pattern formed on a photomask in a reduced size and an aligner method for transferring at a normal magnification are known. In general, the stepper method can form a mask pattern with higher resolution than the aligner method.

  When the aligner method is applied to the technique of Patent Document 1, the line width that can be formed by the aligner method is about 2 to 3 μm, and it is difficult to form a high-definition mask pattern. In order to manufacture a fine structure having a minimum dimension in the surface direction of 2 to 3 μm or less, the current situation is that a stepper method must be adopted. However, using a high-resolution exposure technique such as a stepper method has disadvantages such as an increase in apparatus cost and an increase in the number of processes per wafer. In particular, as described above, the mask pattern If the stepper method is used to form a thick film, the transferred image is blurred due to aberrations and the resolution is lowered. If the resolution is improved by adjusting the depth of focus, the number of man-hours increases and the production efficiency decreases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method capable of efficiently producing a high-definition fine structure at low cost.

  The fine structure manufacturing method of the present invention includes a preparatory step of preparing a base having a corner including a top and sides, etching the top leaving the peripheral edge of the top, and a wall formed of the peripheral edge Forming a fine structure including a portion, wherein the forming step forms a coating film for continuously covering the top portion and the side portion, and the top portion is exposed. Etching the coating film until etching is performed by etching the coating film and the top of the exposed portion under the condition that the etching rate for the substrate is higher than the etching rate for the coating film. An etching process for projecting the coating film covering the side portion from the bottom surface of the etched recess to form a projecting portion, and continuously covering the bottom surface of the etching recess and the projecting portion Forming a second coating film and coating the peripheral edge portion with the second coating film; and etching the second coating film until the bottom surface of the etching recess is exposed to form the protrusion. The second coating film covering the film is held to form a film pattern, and the bottom surface of the etching recess is etched using the film pattern as a mask so that the part covered with the film pattern is at least part of the peripheral edge And a second etching process held as

  In this way, in the etching process, the coating film is selectively held along the side portions of the corners, and the sidewall-shaped protrusions are formed with high positional accuracy. In the second etching process, when the second coating film is etched until the top is exposed, the portion of the second coating film that covers the side surface of the protruding portion is selectively retained, and the sidewall-like film pattern is located at a high position. Formed with precision. In the film pattern, the distance (thickness) between the surface that contacts the side surface of the protruding portion and the back surface is determined according to the film formation amount in the second coating process. However, it is possible to manage with high accuracy. When the bottom surface of the etching recess is etched using the film pattern as a mask, the peripheral portion can be left with a highly accurate line width (thickness), and a high-definition fine structure can be manufactured. As described above, according to the present invention, it is possible to form a wall portion having a size smaller than that of the corner portion without using a photolithography method in the forming step. Therefore, the necessity of using an exposure technique having a resolution comparable to the dimension of the wall portion is reduced, and a high-definition fine structure can be efficiently manufactured at a low cost.

In addition, the base body forms a step with the top portion and has a bottom portion that is continuous with the side portion. In the forming step, the top portion and the bottom portion are etched together using the film pattern as a mask. You can also.
In this way, the number of steps is reduced as compared with the case where the bottom is etched independently of the top, and the fine structure can be efficiently manufactured at low cost.

  Further, based on the difference in etching rate between the two regions determined by the area ratio of the two regions sandwiching the wall portion in the fine structure, a step between the top portion and the bottom portion of the base body before the forming step Can also be set.

  In general, when etching is performed collectively on two partitioned regions, the etching rate is relatively high in a relatively large area. If it does as mentioned above, the level difference after a formation process can be adjusted by adjusting the level difference between the top part and bottom part before a formation process. Therefore, the step between the two regions can be adjusted independently of the area ratio of the two regions sandwiching the wall portion, and the step can be set to a desired value.

  Further, in the forming step, a first process for forming a third coating film that continuously covers the bottom surface of the etching recess and the protrusion after the second etching process, and the third coating film Etching and etching the bottom surface of the etching recess using the projection as a mask to hold the portion covered by the projection as at least a part of the peripheral edge, thereby performing bottom processing of the etching recess It is preferable to perform the step-up process for increasing the step between the upper surface of the peripheral portion and the peripheral surface at least once.

  In this way, a high aspect ratio wall can be formed. Therefore, it becomes possible to manufacture microstructures having various shapes, and it is possible to manufacture microstructures useful in various devices including MEMS.

  In addition, the step difference process is performed a plurality of times, and the ratio of the thickness of the third coating film formed in the first process to the thickness of the third coating film etched in the second process is The shape of the wall portion can also be controlled by managing the steps by a plurality of steps.

  The thickness of the third coating film and the thickness at which the third coating film is etched in the second treatment can be managed with high accuracy as usual. Therefore, the shape of the wall portion can be controlled with high accuracy, and a fine structure useful in various devices can be manufactured.

In addition, it is preferable that the step difference process is performed a plurality of times and the second coating film is formed thicker than the third coating film.
In this way, the durability of the film pattern in the second process is higher than that of the third coating film, and the film pattern can be satisfactorily maintained over a plurality of steps of increasing the level. Therefore, it is easy to increase the number of times of the step-up process, and the step between the bottom surface of the etching recess and the top surface of the peripheral portion can be easily set to a desired value.

The minimum thickness of the wall portion is preferably 0.5 μm or more and 2 μm or less.
In this way, it is possible to manufacture a finer structure with higher definition than the exposure technique using the equal-magnification optical system at lower cost and more efficiently than the exposure technique using the reduction optical system.

The substrate is preferably made of silicon.
In this way, it becomes possible to apply semiconductor technology with respect to silicon etching conditions and the like, and a fine structure can be manufactured satisfactorily. Further, it is possible to manufacture a fine structure made of silicon, and it becomes easy to mix with a semiconductor device or the like manufactured using silicon as a base material.

The example of the microstructure which concerns on this invention is shown, (a) is a perspective view, (b) is sectional drawing. (A)-(d) is sectional process drawing which shows the manufacturing method of 1st Embodiment. (A)-(e) is sectional process drawing which continues from FIG.2 (d). (A)-(d) is sectional process drawing which continues from FIG.3 (e). (A)-(c) is sectional process drawing which continues from FIG.4 (d). The example of the microstructure which concerns on this invention is shown, (a) is a top view, (b) is sectional drawing. (A)-(c) is sectional process drawing which shows the manufacturing method of 2nd Embodiment. (A)-(c) is sectional process drawing which continues from FIG.7 (c). (A)-(c) is sectional process drawing which continues from FIG.8 (c). (A)-(c) is a figure which shows the manufacturing method of the modification 1 schematically. In Modification 2, (a) is a substrate, and (b) and (c) are diagrams showing a fine structure. In Modification 3, (a) is a substrate, and (b) and (c) are diagrams showing a fine structure. In Modification 4, (a) is a base, and (b) and (c) are diagrams showing a fine structure. In Modification 5, (a) is a substrate, and (b) and (c) are diagrams showing a fine structure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings used for explanation, in order to show characteristic parts in an easy-to-understand manner, dimensions and scales of structures in the drawings may be different from actual structures. In addition, in the embodiment, the same components are illustrated with the same reference numerals, and detailed description thereof may be omitted.

[First Embodiment]
Fig.1 (a) is a perspective view which shows schematic structure of the microstructure 1 obtained by the manufacturing method of 1st Embodiment, FIG.1 (b) is a B1-B1 'line | wire cross-section in FIG.1 (a). FIG. As shown in FIG. 1A, the microstructure 1 of the present embodiment has a substantially box-shaped outer shape and includes a substantially frame-shaped outer wall portion 11. The inside of the outer wall portion 11 is a concave portion 12, and a substantially frame-like wall portion 2 is provided inside the concave portion 12. The fine structure 1 is manufactured using a substrate made of silicon as a base material, and the wall portion 2 is formed by applying the present invention.

  Hereinafter, the XYZ orthogonal coordinate system shown in FIG. 2 is set, and the positional relationship of the components of the fine structure 1 will be described based on this. In this XYZ orthogonal coordinate system, the directions perpendicular to each other in the plane including the opening of the recess 12 are defined as the X direction and the Y direction, and the normal direction of the surface including the opening of the recess 12 is defined as the Z direction. The Z direction is a direction in which anisotropic etching proceeds in the manufacturing method described later. Here, the planar shape of the fine structure 1 is substantially rectangular, the short side direction is the X direction, and the long side direction is the Y direction.

  As shown in FIG. 1B, the microstructure 1 has a bottom plate portion 13. As for the baseplate part 13, the surface direction is substantially orthogonal to the Z direction. The outer wall portion 11 is integrated with the peripheral portion in the surface direction of the bottom plate portion 13 and extends from the peripheral portion in the Z direction.

  The wall portion 2 of the present embodiment includes a first wall portion 21 and a second wall portion 22. The first wall portion 21 is located closer to the outer wall portion 11 than the second wall portion 22 and is integrated with the second wall portion 22. The first wall portion 21 and the second wall portion 22 are integrated with the bottom plate portion 13 and extend from the bottom plate portion 13 in the Z direction. The end face in the Z direction of the wall portion 2 protrudes in the Z direction from the second wall portion 22 in the first wall portion 21.

  The first wall portion 21 and the second wall portion 22 each include an extending portion extending in the X direction and an extending portion extending in the Y direction in a plan view. The dimension of the extending portion in the direction substantially orthogonal to the extending direction, that is, the thickness b <b> 1 of the extending portion is substantially uniform at the first wall portion 21. Further, also in the second wall portion 22, the thickness b2 of the extending portion is substantially uniform. The wall thickness b1 of the first wall portion 21 is, for example, about 0.5 μm to 2.0 μm. The wall thickness b <b> 2 of the second wall portion 22 is substantially the same as that of the first wall portion 21, but is thicker than the first wall portion 21. Moreover, the dimension (height) in the Z direction of the first wall portion 21 is, for example, about several tens of μm. The height of the second wall portion 22 can be controlled by the height of the first wall portion 21 and a step h1 described later.

  The region 12a surrounded by the wall portion 2 in the bottom plate portion 13 has a short side dimension of, for example, about 2 to 10 μm. The region 12 a is partitioned by the wall portion 2 from the region 12 b between the wall portion 2 and the outer wall portion 11 in the bottom plate portion 13. The area of the region 12a is smaller than the area of the region 12b in a plane substantially orthogonal to the Z direction. The surface 13a of the bottom plate portion 13 exposed in the region 12a is substantially flush with the surface 13b of the bottom plate portion 13 exposed in the region 12b.

  Next, a first embodiment of a method for manufacturing a microstructure according to the present invention will be described based on the configuration of the microstructure 1. 2 (a) to (d), FIGS. 3 (a) to (e), FIGS. 4 (a) to (d), and FIGS. 5 (a) to (c) schematically illustrate the manufacturing method of the first embodiment. FIG. 3 (a) to 3 (e) and FIGS. 4 (a) to 4 (d) show an enlarged main part.

  In order to manufacture the fine structure 1, first, a base having a corner is prepared (preparation step). The base is, for example, a substrate in which convex portions, concave portions, and through holes are formed. When a convex part is formed, the peripheral part of the surface which protruded in the convex part becomes a corner | angular part. When a recess or a through hole is formed, the peripheral portion of the opening of the recess or the through hole becomes a corner. As a method for forming convex portions, concave portions, and through holes, a method of patterning a substrate using etching, a method of performing laser processing or cutting processing on the substrate partially, and a substrate having protrusions or through holes are bonded to the substrate Methods and the like. The formation method may be appropriately selected according to the dimensions of the recesses, the processing accuracy required for the recesses, and the like.

  In the first embodiment, as shown in FIG. 2A, the substrate 10 having the recesses 14 is formed by patterning a substrate made of silicon using etching. Specifically, a resist pattern 31 having an opening is formed on the substrate, and the substrate is etched using the resist pattern 31 as a mask. The portion covered with the resist pattern 31 becomes the top 15. A portion that overlaps the opening of the resist pattern 31 in the Z direction is the bottom 16. The inner wall of the recess 14 between the top portion 15 and the bottom portion 16 becomes the side portion 17. Thereby, the corner | angular part 18 containing the top part 15 and the side part 17 is formed. The side portion 17 is a portion corresponding to the first wall portion 21 of the microstructure 1. The step h1 between the top portion 15 and the bottom portion 16 is set based on the ratio of the area of the region 12b to the area of the region 12a shown in FIG.

  The etching method used for forming the recess 14 can be appropriately selected according to the shape and dimensions of the recess 14. Here, the recess 14 is formed by using a step-up process (Bosch process) described later. The level difference process is a process of alternately performing a first process (passivation process) and a second process (etching process). For example, the recess 14 is formed by repeating the process of performing the first process for about 3 seconds and then performing the second process for about 5 seconds a plurality of times.

  Next, as shown in FIG. 2B, after the resist pattern 31 is peeled off, a resist pattern 32 is formed so as to cover the periphery of the substrate 10. The portion covered with the resist pattern 32 is a portion that becomes the outer wall portion 11.

  Next, the substrate 10 on which the resist pattern 32 is formed is placed in a processing chamber of an etching apparatus (not shown). This etching apparatus is an apparatus capable of performing reactive ion etching (RIE) by, for example, an inductively coupled plasma (ICP) method. In the processing chamber, it is possible to switch and supply an etching gas and a passivation film forming gas.

Next, as shown in FIG. 2C, a coating film 33 that continuously covers the top portion 15, the side portion 17, and the bottom portion 16 is formed (coating treatment). Here, was circulated C ₄ F ₈ plasma in a processing chamber, comprising on the resist pattern 32 collectively throughout one surface of the substrate 10 by forming a tetrafluoroethylene (depositing), coated A film 33 is formed. For example, by managing the process time of the coating process, the film formation amount of tetrafluoroethylene can be managed, and the film thickness of the coating film 33 can be controlled.

Next, as shown in FIG. 2D, the portion covering the top 15 and the portion covering the bottom 16 in the coating film 33 are removed to expose the top 15 and the bottom 16. Here, the coating film 33 is etched back on the entire one surface of the substrate 10 including the resist pattern 32 by etching using SF ₆ plasma. Thereby, the coating film 33 of the part which coat | covers the side part 17 is selectively hold | maintained.

  Next, as shown in FIG. 3A, the exposed top part 15 and bottom part 16 are collectively etched under the condition that the etching rate for the substrate 10 is higher than the etching rate for the coating film 33. Here, after the coating film 33 is etched back, the top portion 15 and the bottom portion 16 are etched by continuing the etching back as it is.

  Thereby, as shown in FIG. 3B, the top portion 15 is etched, and the top portion 15 is concave with respect to the end portion in the Z direction in the coating film 33 of the portion covering the side portion 17 of the portion covering the side portion 17. One etching recess (etching recess) is formed. Similarly, the bottom 16 is etched to form a second etching recess (etching recess). In the covering film 33 that covers the side portion 17, the end portion in the Z direction protrudes further to the Z direction side than the bottom surface 15 a of the first etching recess to become the protruding portion 34 (etching process). The step h2 between the bottom surface 15a of the first etching recess and the top surface of the protrusion 34 can be controlled by the etching rate of the substrate 10, the etching rate of the coating film 33, and the etching time (process time) in the etching process. The desired value can be obtained. As the thickness of the coating film 33 is increased, the durability of the protrusion 34 is increased, and the value of the step h2 can be increased.

  Next, as shown in FIG. 3C, a second coating film 35 that continuously covers the bottom surface 15a of the first etching recess and the protrusion 34 is formed (second coating process). Here, in the same manner as the above-described coating process, the second coating film 35 is formed by forming a film of ethylene tetrafluoride on the entire surface of the substrate 10 including the resist pattern 32. The film thickness of the second coating film 35 can be controlled with high accuracy by managing the process time for performing the second coating process. Here, the process time is set to about 30 seconds.

  Next, as shown in FIG. 3D, portions of the second coating film 35 that cover the bottom surfaces 15a and 16a are removed to expose the bottom surfaces 15a and 16a. Here, as in the etching process described above, the second coating film 35 is etched back on the entire one surface of the substrate 10 including the resist pattern 32. As a result, the portion of the second coating film 35 covering the surface (side surface) in the direction substantially orthogonal to the Z direction in the protruding portion 34 is selectively held, and the film pattern 36 is obtained. The step between the end surface (upper surface) on the Z direction side of the film pattern 36 and the bottom surface 15a ideally substantially coincides with the step h2 between the bottom surface 15a and the upper surface of the protruding portion 34.

  Next, as shown in FIG. 3E, the bottom surfaces 15a and 16a are collectively etched using the coating film 33 and the film pattern 36 as a mask. Here, after the second coating film 35 is etched back, the bottom surfaces 15a and 16a are etched by continuing the etch back as it is (for example, the process time is about 20 seconds).

  The bottom surface 15b of the first etching recess after etching has a larger step with respect to the top surface of the film pattern 36 than the bottom surface 15a before etching. The side portion of the first etching recess after etching is protected from etching by the film pattern 36 and becomes a wall portion 21a. The bottom surface 16b of the second etching recess after etching has a larger step with respect to the top surface of the film pattern 36 than the bottom surface 16a before etching. The side portion of the second etching recess after etching is protected from etching by the film pattern 36 and becomes a wall portion 22a. The wall portion 21 a is a part of the first wall portion 21, and the wall portion 22 a is a part of the second wall portion 22.

  The thickness b1 of the wall portion 21a is determined by the thickness of the film pattern 36 in a direction substantially orthogonal to the etching direction (Z direction). The thickness b2 of the wall 22a is determined by the total thickness of the thickness of the coating film 33 and the thickness of the film pattern 36 in a direction substantially orthogonal to the etching direction. As described above, the film thickness of the coating film 33 and the second coating film 35 can be controlled by the film formation amount of the film forming material (tetrafluoroethylene). That is, the thickness b1 can be controlled by managing the process time of the coating process. The wall thickness b2 can be controlled by managing the process time of the second coating process. The durability of the film pattern 36 as a mask is determined by the dimension (step difference h2) of the film pattern 36 in a direction parallel to the etching direction, and can be controlled by managing the etching amount in the etching process.

  Next, in the present embodiment, a plurality of steps for increasing the level difference are performed. In order to perform the level difference process, first, as shown in FIG. 4A, the entire surface of the base 10 on which the walls 21a and 22b are formed is formed with tetrafluoroethylene in the same manner as the coating process. A third coating film 37 is formed (first treatment). The process time for the first process is, for example, about 3 seconds.

  Next, as shown in FIG. 4B, portions of the third coating film 37 that cover the bottom surfaces 15b and 16b are removed to expose the bottom surfaces 15b and 16b. Similar to the etching process, the third coating film 37 is etched back on the entire one surface of the substrate 10 including the resist pattern 32. Thereby, the 3rd coating film 37 of the part which covers the side surface of wall part 21a, 22b is selectively hold | maintained.

Next, as shown in FIG. 4C, the bottom surfaces 15b and 16b are collectively etched using the protrusion 34 and the film pattern 36 as a mask. Here, after etching back the third coating film 37, the bottom surfaces 15b and 16b are etched by continuing the etch back as it is (second process). The process time for the second process is, for example, about 5 seconds. Since the wall portions 21a and 22a formed before the second treatment are protected by the third coating film 37, side etching is prevented and etching can proceed with high anisotropy. This
The step between the bottom surface 15c of the first etching recess after etching and the top surface of the wall portion 21a and the step between the bottom surface 16c of the second etching recess after etching and the top surface of the wall portion 22a become large.

  In the present embodiment, the steps 15c and 16c are etched by performing the step difference process again to form the bottom surfaces 15d and 16d as shown in FIG. The film thickness of the third coating film 37 formed by the first process can be made thinner than the coating film 33 and the second coating film 35 within a range that can withstand one second process. Here, the thickness amount by which the third coating film 37 in the portion covering the wall portions 21a and 22a in the second process is thinned, and the thickness amount by which the wall portions 21a and 22a are thickened in the first process. Balance. For example, the ratio between the process time of the first process and the process time of the second process may be adjusted. Here, the process time of the first process is set to about 3 seconds, the process of the second process is set to about 5 seconds, and the amount of thinning and the amount of thickening are balanced.

  By the way, the bottom area of the second etching recess is larger than the bottom area of the first etching recess. Thereby, the etching rate of the bottom surface of the second etching recess becomes higher than the etching rate of the first etching recess. The cause of this phenomenon is that the smaller the area to be etched, the larger the ratio of the amount of plasma incident on the side wall to the total amount of plasma for etching, and the smaller the amount of plasma actually used for etching. It is conceivable that the reaction product that has reacted with silicon is less likely to be exhausted from the inside of the hole. Due to this phenomenon, the total thickness h3 obtained by etching the bottom surface of the first etching recess becomes larger than the total thickness h4 obtained by etching the bottom surface of the second etching recess.

  When the steps are increased a plurality of times, as shown in FIG. 5A, the step h5 between the bottom surface 15e of the first etching recess and the bottom surface 16e of the second etching recess becomes the step shown in FIG. It becomes smaller than h1. When the step-up process is further repeated, the step h6 between the bottom surface 15f of the first etching recess and the bottom surface 16f of the second etching recess becomes smaller than the step h5 as shown in FIG. 5B. By repeating the step-up process as described above, as shown in FIG. 5C, the first wall portion 21 made of the wall portion 21a and the second wall portion 22 made of the wall portion 22a are formed. In addition, by adjusting the value of the level difference h1 of the recess 14, the bottom surface of the first etching recess and the bottom surface of the second etching recess are made substantially flush. The bottom surface of the first etching recess becomes the surface 13 b of the bottom plate portion 13, and the bottom surface of the second etching recess becomes the surface 13 a of the bottom plate portion 13. Further, since the amount to be thinned and the amount to be thickened are balanced, the first wall portion 21 and the second wall portion 22 that are substantially perpendicular to the bottom plate portion 13 can be formed. By removing the resist pattern 32, the coating film 33, the film pattern 36, and the third coating film 37, the microstructure 1 shown in FIG. 1B is obtained.

  In the manufacturing method of the first embodiment as described above, the thickness b1 of the first wall portion 21 and the thickness of the second wall portion 22 are controlled by managing the film formation amount in the coating processing and the second coating processing. It is possible to control the thickness b2. Accordingly, the fine structure 1 can be manufactured without performing etching using a resist pattern having a line width substantially equal to the thickness b1, b2, and the cost and manufacturing efficiency can be increased by using a high-resolution exposure technique. A decrease can be avoided.

Further, by adjusting the value of the level difference h2 between the bottom surface 15a of the first etching recess and the protrusion 34, the durability of the film pattern 36 as a mask can be ensured. Therefore, the film pattern 36 can be made to function well as a mask for a desired number of steps of increasing the height, and the bottom surface of the first etching recess and the bottom surface of the second etching recess can be etched by a desired thickness. . Therefore, the height of the first wall portion 21 and the height of the second wall portion 22 relative to the surfaces 13a and 13b of the bottom plate portion 13 can be set to desired values, the aspect ratio of the first wall portion 21 and the second wall portion. The aspect ratio of 22 can be set to a desired value.
As described above, according to the present invention, a fine structure including a wall portion finer than the line width of the resist pattern can be efficiently manufactured at low cost.

[Second Embodiment]
Next, a second embodiment of the microstructure manufacturing method according to the present invention will be described. Fig.6 (a) is a top view which shows schematic structure of the fine structure 4 obtained by the manufacturing method of 2nd Embodiment, FIG.6 (b) is a B2-B2 'arrow cross section in Fig.6 (a). FIG.
As shown in FIG. 6A, the microstructure 4 of the present embodiment includes a plurality of substantially cylindrical wall portions 5. The plurality of wall portions 5 are formed by applying the present invention, and are arranged in an array here.

  As shown in FIG. 6B, the fine structure 4 has a structure in which a first substrate 41 and a second substrate 42 are bonded to each other. The first substrate 41 is obtained by forming a through hole 43 in a substrate made of silicon. The second substrate 42 is formed using a substrate made of silicon as a base material. A recess 44 having an inner diameter larger than that of the through hole 43 is formed on one surface 42 a of the second substrate 42. One surface 42 a of the second substrate 42 is bonded to the first substrate 41 so that the recess 44 communicates with the through hole 43. A cavity is formed inside the microstructure 4 by the recess 44.

  A wall portion 5 is formed on the other surface 42 b of the second substrate 42. The wall part 5 includes a first wall part 51 and a second wall part 52. The second wall 52 is located in a region surrounded by the first wall 51, and the height from the other surface 42 b is lower than the first wall 51. A region surrounded by the first wall portion 51 and a region surrounded by the second wall portion 52 are through holes 53 communicating with the recess 44. The thickness of the first wall portion 51 is about 0.5 to 1 micron, and the diameter of the through hole 53 is about 2 to 10 μm.

  When the microstructure 4 is used, for example, a liquid material can be arranged in a minute region. For example, in a state where the wall portion 5 is aligned with the minute region, the liquid material is supplied into the concave portion 44 through the through hole 43, and the liquid material is discharged from the wall portion 5 to the minute region through the through hole 53. Thereby, for example, a drug solution containing a gene can be injected into a minute region such as a cell.

Next, a second embodiment of the microstructure manufacturing method according to the present invention will be described based on the configuration of the microstructure 4. FIGS. 7A to 7C, FIGS. 8A to 8C, and FIGS. 9A to 9C are cross-sectional process diagrams schematically showing the manufacturing method of the second embodiment.
In this embodiment, after the base 40 is formed in the steps shown in FIGS. 7A to 7C and FIG. 8A, the microstructure 4 is manufactured using the base 40.

  In order to manufacture the base body 40, a substrate 45 made of silicon is prepared, and a recess 44 is formed on one surface 42a of the substrate 45 as shown in FIG. The method for forming the recess 44 is appropriately selected from various methods such as wet etching, dry etching, step-up processing described in the first embodiment, cutting processing, laser processing, and the like according to the size and accuracy of the recess 44 to be formed. Can be used. Here, the concave portion 44 is formed by using the step height increasing process described in the first embodiment. Here, the recess 44 is formed by repeating the process of performing the second process for about 5 seconds after performing the first process for about 3 seconds a plurality of times.

Next, as shown in FIG. 7B, a silicon oxide film 46 is formed using the CVD method or the like so as to cover the bottom surface of the recess 44.
Next, as shown in FIG. 7C, the first substrate 41 provided with the through hole 43 is bonded to the side where the recess 44 is provided on the substrate 45 on which the silicon oxide film 46 is formed. About the formation method of the through-hole 43, similarly to the recessed part 44, it can select suitably.

  Next, as shown in FIG. 8A, after forming a resist pattern 61 on the back side of one surface 42 a of the substrate 45, the substrate 45 is etched using the resist pattern 61 as a mask to form a recess 47. Here, the recessed part 47 is formed by performing the process similar to a high level | step difference process. Thereby, the part including the back surface with respect to the one surface 42 a becomes the top 55. The portion including the bottom surface of the recess 47 becomes the bottom 56. Further, the portion including the side surface of the recess 47 becomes the side portion 47. A corner portion 58 is configured including the top portion 55 and the side portion 57, and the base body 40 having the corner portion 58 is obtained.

Next, as shown in FIG. 8B, a coating film 63 is formed in a lump so as to cover the top portion 55, the bottom portion 56, and the side portion 57 of the substrate 40 (coating treatment). As the covering process, the same technique as in the first embodiment can be used.
Next, as shown in FIG. 8C, the entire surface of the coating film 63 is etched back to remove the portion of the coating film 63 that covers the top 55 and the bottom 56, and then the etch back is continued to form the top 55 and bottom. 56 is etched. As a result, a first etching recess that is concave in the etching direction is formed in the portion of the coating film 63 covering the side portion 57. The portion of the coating film 63 that covers the side portion 57 protrudes from the bottom surface 55a of the first etching recess in the etching direction to become a protrusion 64. Similarly, the bottom 56 is etched to form a second etching recess including the bottom 56a. (Etching process). As the etching process, the same technique as in the first embodiment can be used.

Next, as shown in FIG. 9A, a second coating film 65 is formed on the entire surface of the substrate 45 so as to cover the bottom surfaces 55a and 56b and the protrusion 64 (second coating process). As the second covering process, the same technique as in the first embodiment can be used.
Next, as shown in FIG. 9B, the entire surface of the second coating film 65 is etched back, and the portion of the second coating film 65 covering the bottom surfaces 55a and 56a is removed. As a result, the portion of the second coating film 65 that covers the side surface of the protrusion 64 is selectively held, and the film pattern 66 is obtained. And etching back is continued and the bottom surfaces 55a and 56a are etched, and the 1st wall part 51 and a part of 2nd wall part 52 are formed.
Next, as shown in FIG. 9C, the step is deepened by penetrating the bottom surface 56 a of the second etching recess by performing a plurality of steps of increasing the level. Thereby, the bottom surface of the first etching recess becomes the other surface 42b, and the first wall portion 51 and the second wall portion 52 are obtained. Further, the fine structure 4 shown in FIGS. 6A and 6B is obtained by removing the covering film 63 including the projecting portion 64, the film pattern 66, the silicon oxide film 46, and the like. Note that the fine structure 4 can be used while holding a part of the coating film 63, the film pattern 66, and the silicon oxide film 46, or a protective film can be formed by thermal oxidation after the removal.

  According to the manufacturing method of the second embodiment as described above, the wall portion 5 having a finer structure than the resist pattern 61 as in the first embodiment can be formed without using another resist pattern. . Therefore, a technique having a lower resolution than the wall thickness of the wall portion 5 can be used as an exposure technique used for forming the wall portion 5, and the microstructure 4 can be manufactured efficiently at low cost.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the first embodiment, the value of the step h1 is set so that the surface 13a and the surface 13b of the bottom plate portion 13 are substantially flush, but the value of the step h1 is adjusted according to the form of the bottom plate portion. It is also possible to do. For example, the surface 13a can be recessed rather than the surface 13b by making the level | step difference of the recessed part 14 larger than the level | step difference h1. In short, the region surrounded by the wall portion may be a through hole penetrating the substrate. As described above, the height of the surface can be controlled independently in the two regions sandwiching the wall portion, and the present invention can be applied to fine structures having various shapes.

  The minimum wall thickness can be 0.5 μm or less depending on the degree of side etching of the side portions in the second etching process. For example, if the number of steps for increasing the level difference is increased and the process time of the second process is shortened, the amount of side etch in one second process decreases, so the minimum wall thickness is set to about 0.2 μm. Is also possible. In this case, the processing time of the first processing may be appropriately shortened according to the shape of the wall portion. Of course, it is possible to make the minimum thickness of the wall portion larger than 2 μm by making the thickness of the second coating film thicker than those of the first and second embodiments.

  Moreover, it is also possible to form the 1st wall part and 2nd wall part which were inclined with respect to the baseplate part 13, and the formation method is demonstrated in the modification 1 later. Various modifications can be made to the structure of the substrate, and specific examples will be described later in modified examples 2 to 5.

  10 (a) to 10 (c) are diagrams schematically showing Modification 1 of the method for manufacturing a microstructure according to the present invention. In the first modification, first, the base 10 is subjected to the same coating process, etching process, second coating process, and second etching process as in the first embodiment. Next, a plurality of high-level steps are performed. In the first modification, the amount by which the third coating film 37 is thickened in the first process is larger than the amount by which the third coating film 37 is thinned by the second process.

  As a result, as shown in FIG. 10A, the maximum film thickness of the third coating film 37 is increased each time the step difference process is repeated. Therefore, the bottom surface 16g of the portion exposed in the course of the second process is reduced in the direction substantially orthogonal to the etching direction every time the step-up process is repeated, and microscopically, the stepped wall portions 21a and 22a. Is formed. Then, when the step is increased a plurality of times and deepened to a predetermined depth, as shown in FIG. 10B, the first wall portion having a substantially tapered shape whose inner size is reduced toward the bottom plate portion 13. 21B and the 2nd wall part 22B are formed. Further, by removing the resist pattern 32, the coating film 33, the film pattern 36, and the third coating film 37, a fine structure 1B as shown in FIG. 10C is obtained.

  In addition, it is also possible to form the substantially reverse taper-shaped 1st wall part and 2nd wall part which an internal dimension expands as it goes to the baseplate part 13. As shown in FIG. For example, by adjusting the process time of the second process so that the side etch amount in the second process is larger than that in the first embodiment, the first wall part and the second wall part having a reverse taper shape are formed. Can do.

  FIG. 11A is a perspective view showing a base body 10C used for manufacturing the microstructure 1C of the second modification, FIG. 11B is a perspective view showing the microstructure 1C, and FIG. 11C is FIG. It is a B3-B3 'line arrow directional cross-sectional view.

  As shown in FIG. 11A, the base body 10C has island-shaped convex portions that protrude from the substrate surface on the substrate. The portion including the top surface of the convex portion is the top portion 15C, the portion including the substrate surface is the bottom portion 16C, and the portion including the side surface of the convex portion is the side portion 17C. Such a substrate can be obtained by bonding a convex portion to the substrate, patterning the substrate while leaving the convex portion, or the like.

  When the substrate 10C is subjected to the covering process, the etching process, the second covering process, and the second etching process, and then performing a high step process, as in the first embodiment, FIG. 11B and FIG. 1C) is obtained. The fine structure 1 </ b> C includes a frame-shaped first wall portion 21 </ b> C composed of a peripheral portion of the top portion 15 </ b> C. A portion surrounded by the first wall 21C is a recess 23C. Further, a portion of the bottom portion 16C that is continuous with the wall portion 17C is a second wall portion 22C.

  12A is a perspective view showing a base body 10D used for manufacturing the microstructure 1D of the third modification, FIG. 12B is a perspective view showing the microstructure 1D, and FIG. 12C is FIG. It is a B4-B4 'line arrow directional cross-sectional view.

  As shown in FIG. 12A, the base 10D has a structure in which a through hole 16D is provided in the center of the substrate. A portion including one surface of the substrate is a top portion 15D. A portion including the side surface exposed inside the through-hole 16D is a side portion 17D.

  When the substrate 10D is subjected to the coating process, the etching process, the second coating process, and the second etching process, and then subjected to the step-up process, as in the first embodiment, FIG. 12B and FIG. A fine structure 1D as shown in FIG. The fine structure 1D includes a frame-shaped first wall portion 2D including a peripheral portion of the top portion 15C surrounding the through hole 16D. As described above, when a base that does not include the bottom is used, a wall that does not include the second wall can be formed.

  FIG. 13A is a perspective view showing a base body 10E used for manufacturing the microstructure 1E of the modified example 4, FIG. 13B is a perspective view showing the microstructure 1E, and FIG. 13C is FIG. It is a B5-B5 'arrow directional cross-sectional view.

  As shown in FIG. 13A, the base body 10E has a structure in which a concave portion is provided on one surface of the substrate, and an island-shaped convex portion is provided in the concave portion. In other words, the substrate has a structure in which a closed annular groove is provided. A portion including the substrate surface outside the groove portion and a portion including the top surface of the convex portion are the top portion 15E. A portion including the bottom surface of the groove portion is a bottom portion 16E. A portion including the side surface exposed in the groove portion is a side portion 17E.

  When the base 10E is subjected to the coating process, the etching process, the second coating process, and the second etching process, and then subjected to the step-up process, as in the first embodiment, FIG. 13B and FIG. A microstructure 1E as shown in FIG. The fine structure 1E includes a first wall portion 21E composed of a peripheral portion of an island-shaped convex portion, and a first wall portion 21E composed of a peripheral portion of the top portion 15E outside the groove portion. A second wall portion 22E is formed between the two first wall portions 21E formed with the groove portion interposed therebetween.

  FIG. 14A is a perspective view showing a base body 10F used for manufacturing the microstructure 1E of the modified example 5, FIG. 14B is a perspective view showing the microstructure 1F, and FIG. 14C is FIG. It is a B6-B6 'line arrow directional cross-sectional view.

  As shown in FIG. 14A, the base body 10F has a structure in which a plurality of concave portions are periodically arranged on one surface of the substrate. Each of the plurality of recesses has a substantially square outline in plan view. The plurality of recesses are arranged at substantially the same interval as one side of the contour in each of the X direction and the Y direction. When attention is paid to the rows of concave portions arranged in the X direction, the positions of the concave portions are shifted by substantially the same distance as one side of the contour in two adjacent rows. In other words, the convex portion between the concave portions in one of the two adjacent rows is substantially coincident with the concave portion in the other row in the X direction. Further, even if attention is paid to the row of the concave portions arranged in the Y direction, the positional relationship is similarly obtained, and the plural concave portions are arranged in a so-called zigzag pattern. A portion including the top surface of the convex portion between the concave portions is a top portion 15F. A portion including the bottom surface of the concave portion is a bottom portion 16F. The portion including the side surface exposed in the recess is the side portion 17F.

  When the base 10F is subjected to the coating process, the etching process, the second coating process, and the second etching process, and then subjected to the step-up process, as in the first embodiment, FIG. A fine structure 1F as shown in FIG. The fine structure 1F includes a first wall portion 21F composed of a peripheral portion of the top portion 15F and a second wall portion 22F composed of a peripheral portion of the bottom portion 16F. Here, the level difference process is performed until the bottom portion 16F penetrates, and the portion surrounded by the first wall portion 21F is the through hole 23F. A portion surrounded by the second wall portion 22F is a through hole 24F. When the microstructure 1F is observed from the direction corresponding to the back surface side of the top surface 15F of the base 10F, the microstructure 1F has a structure in which the through holes 23F and 24F are arranged in an array. That is, the first wall portion 21F and the second wall portion 22F have a lattice-like structure extending vertically and horizontally between the through holes 23F and 24F.

  In addition, when forming a corner part by a convex part, a concave part, or a through hole, any of a polygonal shape, a circular shape, an elliptical shape, or a shape obtained by combining a part of these shapes is adopted as the planar shape of the convex part etc. You can also

  1, 1B, 1C, 1D, 1E, 1F, 4 ... microstructure, 2, 5 ... wall, 10, 10B, 10C, 10D, 10E, 10F, 40 ... substrate, 15, 15B, 15C, 15D, 15E, 15F, 55 ... top, 16, 16B, 16C, 16E, 16F, 56 ... bottom, 17, 17B, 17C, 17D, 17E, 17F, 57 ... side, 18 , 58 ... corners, 33, 63 ... coating films, 34, 64 ... projections, 35, 65 ... second coating films, 36, 66 ... film patterns, 37 ..Third coating film

Claims (8)

A preparation step of preparing a substrate having a corner including a top portion and a side portion;
Etching the top part leaving the peripheral part of the top part, forming a microstructure including a wall part composed of the peripheral part, and
The forming step includes a coating process for forming a coating film that continuously covers the top portion and the side portion;
The coating film is etched until the top portion is exposed, and the coating film and the top portion of the exposed portion are etched under a condition that an etching rate with respect to the base is higher than an etching rate with respect to the coating film. Etching treatment to project the covering film of the portion covering the side portion from the bottom surface of the etching recess formed by etching, and to form a projecting portion,
Forming a second coating film that continuously covers the bottom surface of the etching recess and the protrusion, and coating the peripheral edge portion with the second coating film;
The second coating film is etched until the bottom surface of the etching recess is exposed to hold the second coating film at a portion covering the protruding portion to form a film pattern, and the etching recess using the film pattern as a mask. And a second etching process for holding a portion covered with the film pattern as at least a part of the peripheral edge by etching the bottom surface of the substrate. The base body forms a step with the top portion and has a bottom portion continuous with the side portion,
2. The method for manufacturing a microstructure according to claim 1, wherein in the forming step, the top portion and the bottom portion are collectively etched using the film pattern as a mask.   In the forming step, the top portion and the bottom portion of the base body before the forming step are based on a difference in etching rate between the two regions determined by an area ratio of the two regions sandwiching the wall portion in the microstructure. The method for manufacturing a microstructure according to claim 2, wherein a step is set.   In the forming step, a first process for forming a third coating film that continuously covers the bottom surface of the etching recess and the protrusion after the second etching process, and the third coating film are etched. And performing a second process of etching the bottom surface of the etching recess using the protrusion as a mask and holding the portion covered by the protrusion as at least a part of the peripheral edge, and performing the bottom processing of the etching recess and the peripheral edge. The method for producing a fine structure according to any one of claims 1 to 3, wherein the height difference process for increasing the level difference with the top surface of the part is performed at least once.   The height difference process is performed a plurality of times, and the ratio between the thickness of the third coating film formed in the first process and the thickness at which the third coating film is etched in the second process is calculated a plurality of times. 5. The method of manufacturing a microstructure according to claim 4, wherein the shape of the wall portion is controlled by managing the height difference in a step.   The method for manufacturing a microstructure according to claim 4 or 5, wherein the step-up process is performed a plurality of times and the second coating film is formed thicker than the third coating film.   The method for manufacturing a microstructure according to any one of claims 1 to 6, wherein the minimum thickness of the wall portion is set to 0.5 µm or more and 2 µm or less.   The method for manufacturing a microstructure according to any one of claims 1 to 7, wherein the substrate is made of silicon.

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