JP2006075919A - Method of manufacturing suction preventive structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a general-purpose good suction preventive structure by easily forming micro projecting parts of uniform height and shape in an optional position. <P>SOLUTION: In a micro component having a mechanism allowing the contact or separation of a movable part 10 and a fixed part 14 (or two movable parts) facing each other, by the displacement of the movable part, the suction preventive structure 16 is manufactured using pressure impression and an etching process. As an embodiment, at least a surface part of at least one of contacting members is formed of a glass material, and pressure is applied to the surface part to form a stress remaining part. Wet etching is then applied to form the micro projecting parts using the difference of etching rates of the stress remaining part and other parts, and the micro projecting parts function as the suction preventive structure. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an adsorption preventing structure in various micro parts, and more specifically, a method for producing an adsorption preventing structure by forming fine convex portions on a contact surface using a pressure application / etching process. It is about.

  In recent years, research and development of various microparts has been advanced in order to meet various demands such as higher density, higher accuracy, and higher speed in electronic devices and optical devices. Some of them include a mechanism in which the movable portion and the fixed portion or the movable portions can be contacted and separated by the displacement of the movable portion. Since such a contact / separation mechanism has a minute structure, the occurrence of problems due to stiction (sticking) is a problem. Therefore, some anti-adsorption measures are taken.

  For example, Patent Document 1 discloses a structure in which convex portions having a diameter of about 10 μm and a height of about 1 to 50 nm are arranged in an array as an anti-adsorption structure used for an optical switching element. Such an adsorption preventing structure with fine convex portions is the most common and versatile. Here, fine convex portions are formed by laser processing.

  Further, Patent Document 2 discloses a sticker that is attached to the spring part of a MEMS (micro electromechanical system) element, and prevents the adsorption by increasing the spring constant when the amount of deformation of the spring increases. A structure has been proposed. However, this structure is not versatile due to restrictions on the structure of the element, for example, no other structure can be made at the position of the stopper.

  Furthermore, Patent Document 3 discloses a structure in which an airflow is introduced from a through hole and this force prevents the vibration part of the micromirror from sticking. However, this structure is complicated and lacks versatility because it is necessary to form a through-hole and take air into the through-hole.

  For these reasons, the anti-adsorption structure with fine protrusions is versatile and preferable, but an appropriate manufacturing method has not yet been developed. Conventionally, as a method of forming fine convex portions, there are a sand blasting method, a dry processing method, a wet processing method and the like in addition to the laser processing method described in Patent Document 1.

However, in the laser processing method, since the instability of laser output affects the shape of the convex portion, it is difficult to make the sizes of the convex portions uniform. In the sand blasting method, the energy of individual particles varies depending on the particle size of the particles used, so that the height and size of the convex portions are not uniform, and cracks may occur. The dry processing method is expensive because the processing process is complicated. The wet processing method is a process in which SiF ₆ ^2- generated by HF etching combines with K ⁺ and NH ₄ ⁺ in the liquid and precipitates on the surface in a granular form, which acts as a mask. Cannot be controlled, so neither the size nor the location of the protrusions can be controlled.
JP 2001-318325 A JP 2002-326197 A JP 2000-314846 A

  The problem to be solved by the present invention is that a fine convex portion having a uniform height or shape can be easily formed at an arbitrary position, thereby making it possible to produce a good versatile anti-adsorption structure. That is.

  The present invention is a method for producing an anti-adsorption structure in a micro component having a mechanism in which a movable part and a fixed part or movable parts facing each other can be contacted and separated by displacement of the movable part, At least one surface part of at least one of the members to be contacted is made of a glass-based material, a stress residual part is formed by applying pressure to the surface part, and then wet etching is performed, whereby the stress residual part and the other part are formed. This is a method for producing an anti-adsorption structure characterized in that a fine convex portion is formed using the difference in etching rate with the anti-adsorption structure.

  Here, the application of the pressure may be performed at room temperature, but if a pressure is applied while heating a member on which a fine convex portion is to be formed or in a heated state, no crack occurs during the pressure application. Moreover, since a high convex part is obtained as a result, it is preferable. The portion where the fine convex part of the contact surface should be formed may be a glass-based substrate itself, or a member formed by forming a glass-based thin film on a substrate made of any material or a thin film, and pressure on the glass-based material. Apply.

  The pressure may be applied by an arbitrary method such as pressing of a mold provided with fine convex portions, pressing or scanning of an indenter, blasting, or polishing using fine particles. In this specification, the mold has a hardness sufficient to apply pressure to a glass-based material, and a predetermined pattern is formed on the surface in advance in order to obtain a desired convex portion. Say. Also, the indenter means a shape that has a sufficient hardness to apply pressure to a glass-based material and has a shape that allows pressure to be applied to its tip.

  The method for producing an adsorption preventing structure according to the present invention is suitable for micro components because the convex portions are formed corresponding to the state of pressure application when etched, and the convex portions and their positions are highly flexible. A good anti-adsorption structure can be realized. Further, since a fine structure of about several tens of μm can be manufactured by a maskless and simple process, an adsorption preventing structure can be formed at low cost. Furthermore, if the portion where the fine protrusions are to be formed is a glass-based thin film, the contacting member is not limited to a glass-based material, and therefore can be applied to substrates and thin films made of various materials.

  In the case of a method in which pressure is applied by indenter scanning, blasting, polishing using fine particles, etc., a mold is not necessary, and it is suitable for low-cost production of a small variety of products.

  In the method for producing an adsorption preventing structure according to the present invention, first, stress is applied to a necessary portion of the surface of a substrate made of a glass-based material or the surface of a thin film made of a glass-based material provided on the substrate. Form. Here, it is preferable to apply the pressure while heating the substrate or in a heated state. This is because if the pressure is applied in a heated state, cracks are not generated during the application of the pressure, and the convex portions that can be formed can be made higher than when not heated. The size and height of the protrusions vary depending on the use conditions, but if a heating pressure application method is used, for example, the size is several μm to several hundreds μm, and the height is several tens to several tens of μm. A convex part can be freely produced in the range to the extent.

  The method of applying pressure may be arbitrary, and is selected from a die pressing method, an indenter pressing / scanning method, a blasting method, a polishing method using fine particles, etc., depending on the state of the fine protrusions to be finally formed. To do. The degree of pressure application is also controlled according to the size of the convex portion to be finally formed. The surface to which pressure is applied is hardly deformed and remains flat. However, if a slight dent is formed, it is also effective to perform a pretreatment such as light polishing to make the surface flat.

  Thereafter, wet etching is performed. At this time, the residual stress portion is difficult to be etched because the etching rate is lower than the other portions, and as a result, remains as a convex portion. In this way, fine convex portions appear corresponding to the portions to which pressure is applied. At least one surface of the contact surface between the movable portion and the fixed portion of the mechanism in which the movable portion and the fixed portion or the movable portions facing each other of the micro parts can be contacted and separated by displacement of the movable portion, Alternatively, by forming a fine convex portion on at least one of the contact surfaces between the movable portions, it is possible to prevent the movable portion and the fixed portion or the movable portions from being attracted to each other.

  In the method of forming a thin film on a substrate, fine projections can be formed on the thin film itself, or the fine projections can be formed on the substrate by using the thin film to which pressure is applied as a mask. You can also.

  FIG. 1 is an explanatory diagram illustrating an example of a main part of a micro component having an adsorption preventing structure. This is an example of a cantilever cantilever structure in which the movable portion 10 is supported by the support column portion 12 at the base end and is disposed so as to face the fixed portion (substrate) 14 at an interval. Due to the operation of the driving mechanism, the distal end of the movable portion 10 comes into contact with the fixed portion 14 from the separated state shown in A to the contact state shown in B. When the operation of the drive mechanism stops, the separated state shown in A is restored by the restoring force of the movable portion 10. Here, in order to smoothly return from the contact state shown in B to the separated state shown in A, the adsorption preventing structure 16 composed of a number of fine convex portions is formed only on the contact surface on the fixed portion side.

  FIG. 2 is an explanatory view showing another example of the main part of the micro component having the adsorption preventing structure. This is an example of a double-supported structure in which the movable unit 20 is supported by the support column unit 22 at both ends thereof and is disposed so as to face the fixed unit (substrate) 24 with a space therebetween. The same applies to the diaphragm in which the movable part is supported in the periphery. Due to the operation of the drive mechanism, the center portion of the movable portion 20 comes into contact with the fixed portion 24 from the separated state shown in A to the contact state shown in B. When the operation of the drive mechanism stops, the separated state shown in A is restored by the restoring force of the movable portion 20. In this case as well, the anti-adsorption structure 26 composed of a large number of fine convex portions is formed on the contact surface on the fixed portion side so that the contact state shown in B smoothly returns to the separated state shown in A.

  The driving mechanism of the movable part may be arbitrary, and for example, driving by magnetic force, driving by electrostatic force, driving by resistance heating, driving by piezo effect, etc. can be used. In the above example, the fine convex portion is formed only on the fixed portion side as the adsorption preventing structure, but it may be formed only on the movable portion side, or may be formed on both the fixed portion side and the movable portion side. Also good.

  The fine protrusions formed here are typically dome-shaped as shown in FIG. For example, the protrusion 30 has a semicircular or semi-elliptical longitudinal cross section as shown in A, and a large number of circular protrusions 30 as viewed from above are arranged in a two-dimensional array to form an adsorption preventing structure. To do. The size, height, number, arrangement pitch, arrangement method, and the like of the protrusions to be formed may be changed as appropriate according to the usage state of the microparts and the required performance of the anti-adsorption structure.

Next, an example of a procedure for producing a fine convex portion will be described. FIG. 4 is a process diagram showing a typical example.
(A) The surface portion of the glass-based substrate 40 on which fine convex portions are to be formed is pressed by a mold 44 in which a large number of fine convex portions 42 are arranged. As the substrate, for example, aluminosilicate glass is used, and the mold material is a cemented carbide such as WC or SiC, or quartz. Here, a mold having a convex portion with a rounded tip is used. It is preferable to heat the glass substrate at the time of pressing.
(B) By applying pressure by pressing the mold, a residual stress portion 46 is formed in the vicinity of the surface of the glass-based substrate 40.
(C) When wet etching is performed thereafter, the stress remaining portion has an etching rate smaller than that of the other portions. Therefore, by utilizing the difference, the fine convex portion 48 corresponding to the position and size of the stress remaining portion is used. Is formed. Etching is performed, for example, at an HF concentration of about 10 ppm to 10%, and the temperature of the etching solution is about room temperature to about 80 ° C.

  This method is effective for optical micro components that transmit and block light and switch optical paths, etc., because an adsorption preventing structure consisting of fine convex portions can be directly produced on the surface of a glass-based substrate. Incidentally, a general technique such as matte etching has an adverse effect on optical properties such as cloudiness, but the method of the present invention does not have such a concern.

  The fine protrusions to be formed can be controlled by the shape of the tip of the mold to which the pressing force is applied, the pressing force, the degree of etching, and the like. For example, a dome shape as shown in FIG. 5A, a trapezoidal shape as shown in B, a triangular shape as shown in C, and the like can be selected and realized as a shape suitable as an anti-adsorption structure for micro parts. . Further, the planar shape of the convex portion can be various shapes such as a rectangle, a triangle, other polygons, and an ellipse in addition to a circle as shown in FIG.

Another procedure for producing fine convex portions will be described. FIG. 6 is a process diagram thereof.
(A) A glass-based thin film 51 is formed in advance on the surface of the substrate 50. And the surface part of the glass-type thin film 51 which should form a fine convex part is pressed with the metal mold | die 54 in which many fine convex parts 52 are provided. As the thin film, for example, aluminosilicate glass is used, and the mold is made of a cemented carbide such as WC or SiC, or quartz. The substrate may be any material such as a semiconductor or metal. It is preferable to heat the glass-based thin film when pressing the mold.
(B) By applying a pressure by pressing the mold, a residual stress portion 56 is formed near the surface of the glass-based thin film 51.
(C) When wet etching is performed thereafter, the stress remaining portion has a lower etching rate than the other portions. Therefore, by utilizing the difference, the fine convex portion 58 corresponding to the position and size of the stress remaining portion is obtained. Is formed on the glass-based thin film 51.

  When it is sufficient to finally form an adsorption preventing structure composed of fine convex portions on the glass-based thin film, the process is completed in the step (c). When etching is continued, the glass-based thin film functions as a mask and can be etched until it reaches the substrate as shown in FIG. Thus, the glass-based thin film material 51a can be left only at the top of the convex portion 58. When further etching is performed, etching can be performed until the glass-based thin film material is completely removed as shown in FIG. Thereby, the glass-based thin film can be completely removed, and the protrusions 58 can be formed on the base 50. Note that the etching solution in this case has an etching ability for both the glass-based thin film 51 and the substrate 50.

  If the substrate is a semiconductor or metal, even if pressure is applied, there will be no difference in the etching rate and fine protrusions will not be obtained, but this can be achieved by using the method of adding a glass-based thin film as described above. It becomes. That is, the above-described method using a glass-based thin film can be applied to various micro parts because the material of the substrate is not limited.

A description will be given of still another procedure for producing fine convex portions. FIG. 7 is a process diagram thereof. When the method shown in FIG. 7 is applied, it can also be applied to micro parts that require an electrical contact mechanism.
(A) An electrode layer 70 made of an electrode material (for example, ITO or SnO ₂ ) is formed on the surface of the substrate 60, and a glass-based thin film 61 is further formed. And the surface part of the glass-type thin film 61 which should form a fine convex part is pressed with the metal mold | die 64 in which many fine convex parts 62 are arranged. As the glass-based thin film, for example, aluminosilicate glass is used, and the mold is made of a cemented carbide such as WC or SiC, or quartz. The base body 60 may be any semiconductor or metal. It is preferable to heat the glass-based thin film during pressing.
(B) By applying a pressure by pressing the mold, a stress residual portion 66 is formed near the surface of the glass-based thin film 61.
(C) After that, when wet etching is performed, the stress remaining portion has a lower etching rate than the other portions. Therefore, by utilizing the difference, the position and size of the stress remaining portion are applied to the glass-based thin film 61. The fine convex part 72 according to this is formed.
(D) If the etching is further continued, the glass-based thin film functions as a mask, and the electrode layer 70 can be etched. As a result, the glass-based thin film can be completely removed, and the fine protrusions 68 can be formed on the surface of the electrode layer 70.

  An example of a procedure for manufacturing a micro component having the above-described adsorption prevention structure will be described. FIG. 8 is an explanatory diagram showing a procedure for manufacturing a micro component as shown in FIG. 2, and is an example applied to the manufacture of a capacitively coupled electrostatic switch.

  First, as shown in FIG. 8A, a glass-based thin film 81 is formed on the surface of a silicon substrate 80 on which a predetermined electronic circuit is manufactured, and pressure is applied to a number of locations on the surface of the glass-based thin film 81. This glass-based thin film is preferably composed of, for example, aluminosilicate glass. Thereafter, portions other than the formed glass-based thin film are appropriately masked, the silicon substrate is immersed in an etching solution containing hydrofluoric acid, and the glass-based thin film to which pressure is applied is etched, so that a large number of fine protrusions are formed. Forming part. This fine convex part becomes an adsorption | suction prevention structure (refer the code | symbol 82 of FIG.8 (b)).

  In this hydrofluoric acid etching, if etching is performed so as to leave a glass-based thin film, the remaining glass-based thin film also functions as an insulating layer. Moreover, after forming another insulating layer as required, this glass-based thin film may be formed, and pressure application and etching may be performed.

  Thereafter, the above-described masking is removed, and a copper sacrificial layer 83 is formed by vapor deposition as shown in FIG. And the scaffold of the Ni-P layer used as a movable part is formed. For this purpose, the copper to be the scaffold is removed by a patterning method using a mixed etching solution of cupric ammonium chloride and ammonia.

  Subsequently, as shown in FIG. 8C, a Ni—P layer 84 to be a movable portion is formed by an electroless plating method so as to cover the copper sacrificial layer 83. Finally, only the copper sacrificial layer 83 is removed using the above-described mixed etching solution. In this way, as shown in FIG. 8D, the portion where the copper sacrificial layer was present becomes the space 85, and the Ni-P layer 84 can be made a movable portion having a dual-support structure. In this way, a micro component having the movable part of the Ni-P layer 84 and having the adsorption preventing structure 82 formed on the surface of the glass-based thin film 81 facing it is completed.

  In each of the above embodiments, pressure is applied by pressing the mold. This method is advantageous in that the size and height of the convex portions can be made uniform and the position can be defined. The pressure may be applied by a method of scanning an indenter (such as a carbide tool, a cutter or a razor blade). In this indenter scanning method, linear protrusions can be formed, so that parallel stripe-like protrusions, lattice stripe-like protrusions, and the like can be formed. The pressure application may be performed by a blast method. The blast method is a technique of spraying particles at a high speed, but it does not require energy to roughen the surface for applying pressure. Empirically, the height of the protrusions formed after etching is almost constant if a certain level of pressure is applied. Therefore, when the blast method is used, the height is not uniform. Gives a nearly constant fine projection.

Explanatory drawing which shows an example of the principal part of the micro component provided with the adsorption | suction prevention structure. Explanatory drawing which shows the other example of the principal part of the micro component provided with the adsorption | suction prevention structure. Explanatory drawing which shows the typical example of a convex part shape. Process drawing which shows an example of the preparation procedures of the adsorption | suction prevention structure which concerns on this invention. Sectional drawing which shows the other example of a convex part shape. Process drawing which shows the other example of the preparation procedures of the adsorption | suction prevention structure which concerns on this invention. Process drawing which shows the further another example of the preparation procedure of the adsorption | suction prevention structure which concerns on this invention. Process drawing which shows an example of the production procedure of the micro component shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 Movable part 12,22 Support | pillar part 14,24 Fixed part 16,26 Adsorption prevention structure 40 Substrate 44 Mold 46 Stress residual part 48 Convex part

Claims (7)

A method for producing an anti-adsorption structure in a micro component having a mechanism in which a movable part and a fixed part or movable parts facing each other can be contacted and separated by displacement of the movable part,
At least one surface part of at least one of the contacting members is made of a glass-based material, a stress residual part is formed by applying pressure to the surface part, and then wet etching is performed, whereby the stress residual part and the other part are applied. A method for producing an anti-adsorption structure, characterized in that a fine convex portion is formed by utilizing a difference in etching rate from a portion to form an anti-adsorption structure.   The method for producing an adsorption preventing structure according to claim 1, wherein the pressure is applied while the surface portion is heated or in a heated state.   The method for producing an adsorption preventing structure according to claim 1 or 2, wherein the pressure is applied to a glass-based thin film formed on a surface of the fixing portion.   The method for producing an adsorption preventing structure according to any one of claims 1 to 3, wherein the pressure is applied by pressing a mold provided with a fine convex portion.   The method for producing an adsorption preventing structure according to any one of claims 1 to 3, wherein the pressure is applied by pressing or scanning an indenter.   The method for producing an adsorption preventing structure according to claim 1, wherein the pressure is applied by a blast method. The method for producing an adsorption preventing structure according to any one of claims 1 to 3, wherein the pressure is applied by polishing using fine particles.

Images