JP5139032B2 - Fine structure and manufacturing method thereof - Google Patents

Description

  The present invention relates to a fine structure formed on a substrate in a state where a fine structure including a movable part constituting a MEMS or the like is sealed, and a method for manufacturing the same.

  In recent years, MEMS (Micro Electro Mechanical System) components (MEMS devices) have been developed by utilizing micromachine technology that performs three-dimensional microfabrication by etching based on thin film formation technology and photolithography technology. Has been. Some MEMS elements include fine structures such as a micro switch having a fine fixed electrode and a movable structure, a variable capacitor, a resonator, and an acceleration sensor (see Patent Documents 1 and 2). A basic structure of the microstructure having such a structure is shown in FIG.

  Conventional microstructures include a substrate 701, a fixed electrode 702 fixedly formed on the substrate 701, a support structure 703 formed on the substrate 701, and a support structure 703. And a movable electrode 704 disposed on the substrate 701 so as to be supported by the unit. In this microstructure, for example, an actuator that constitutes a MEMS element such as a microswitch or a variable capacitor is formed by applying a voltage between the fixed electrode 702 and the movable electrode 704 and displacing the movable electrode 704 by electrostatic attraction. Can be used as In addition, the displacement of the movable electrode 704 due to the force applied to the movable electrode 704 from the outside is electrically detected as a change in the electrical capacitance between the movable electrode 704 and the fixed electrode 702, so that an acceleration sensor or the like can be used. It can also be used as a sensor.

JP 2000-294104 A Japanese Patent Laid-Open No. 11-250792 Harrie A. C. Tilmans, "RF-MEMS: Materials and technology, integration and packaging", Proc. MRS2003, vol.738, Fall Meeting, Boston, pp.B6.6.1-B6.6.12, Dec. 1-5, 2003. N. Sato, H. Ishii, S. Shigematu, H. Morimura, T. Kamei, K. Kudiu, M. Yano, K. Machida, H. Kyuragi, "A sealing technique for stacking MEMS on LSI using spin-coating film transfer and hot pressing ", Jpa.J.Appl.Phys., Vol.42, Part 1, No.4B, pp.2462-2467, Apr. 2003.

  By the way, in the fine structure as described above, there is a problem that the movable structure is easily damaged. For example, in a process such as dicing that divides a wafer into chips, a high-pressure water flow is supplied to cool a cutting portion or prevent scattering of cutting chips, but this high-pressure water flow facilitates the formation of a fine movable structure. It will be damaged. For this reason, a protection technique for preventing breakage is required in the mounting process and actual use of the MEMS element. As a protection technique, a technique of protecting a mechanically fragile structure by fixing a cap made of glass on a substrate and sealing a fine structure such as a metal wiring with the cap is proposed (Non-Non-Patent Document) Patent Document 1). Since glass is an insulating member having relatively high rigidity, it is suitable for sealing a predetermined region (space) without distortion.

  However, when such a method is used, there is a problem that the cost of the MEMS is increased because a special mounting process is added, and the cap increases the size of the MEMS. In addition, when a cap made of glass is used, there is a problem that mounting is restricted, such as flip chip mounting, chip stacking using Si through-via wiring technology, and the like becomes difficult.

  As described above, in the prior art, it is difficult to ensure the mechanical and electrical reliability of the fine structure when a high-performance fine structure including a movable structure is to be realized. In addition, in order to avoid this problem, when a technology for protecting and sealing the space in which the movable structure is arranged with a glass cap or the like is used, there is a problem that the fine structure is enlarged and mounting is restricted. It was. Therefore, in the prior art, it has been difficult to put into practical use a microstructure having a movable structure.

  The present invention has been made to solve the above-described problems, and a fine structure including a fine movable structure can be used without increasing the size of a device or restricting mounting. An object is to enable formation with high reliability.

A fine structure according to the present invention includes a substrate, a support frame formed on the substrate and surrounding a predetermined region, a wiring support portion formed in a region surrounded by the support frame on the substrate, and a wiring A wiring supported by the supporting portion and surrounded by a supporting frame on the substrate is arranged away from the surface of the substrate, and a movable electrode separated from the substrate. The movable structure disposed in the region surrounded by the upper support frame and the fixed electrode disposed in the region surrounded by the support frame on the substrate, including the fixed electrode disposed opposite to the upper portion of the movable electrode. An electrode structure, and a fixed electrode structure and a sealing film that is supported by the support frame and seals a region surrounded by the support frame . The sealing film is added to the fixed electrode structure and the support frame. It is supported by a wiring structure comprising a wiring support part and wiring .

In the fine structure, the fixed electrode structure may be formed at the same height as the support frame. Further, in the fine structure, wiring to the inductor, those constituting at least one of the transformers, and transmission lines. Also, the movable structure and the fixed electrode structures, variable capacitance constitute switches, resonators, and at least one of an acceleration sensor. The substrate includes a semiconductor integrated circuit including an active element and a multilayer wiring, and the movable electrode and the fixed electrode are electrically connected to the semiconductor integrated circuit.

In addition, the manufacturing method of the microstructure according to the present invention includes a support frame that surrounds a predetermined region on the substrate with the metal film formed by laminating a metal film using a sacrificial film on the substrate, and surrounding the substrate with the support frame. Wiring support parts arranged in the areas that are separated, supported by the wiring support parts, arranged in areas surrounded by the support frame, supported by a part of the wiring, and arranged in areas surrounded by the support frames A step of forming a movable structure including a movable electrode and a fixed electrode structure including a fixed electrode disposed in a region surrounded by the support frame and disposed opposite to the upper portion of the movable electrode; The sacrificial film is removed, the wiring is disposed away from the surface of the substrate, the movable electrode is disposed away from the upper portion of the substrate, and the fixed electrode is disposed away from the movable electrode. a step, after removing the sacrificial layer, the support frame, the fixed electrode structure, and a wiring support Paste the sealing film in contact with the upper surface of the wiring structure consisting of wire and the support frame, the fixed electrode structures, and seals the region enclosed in the support frame is supported by the wiring structure sealing film And at least a step of forming the formed state.

  As described above, according to the present invention, the fixed electrode is oriented and arranged on the movable electrode, and the sealing film is supported by the fixed electrode structure including the fixed electrode and the support frame. An excellent effect is obtained that a fine structure including a movable structure can be formed with higher reliability without incurring an increase in the size of the apparatus or restrictions on mounting.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
First, Embodiment 1 according to the present invention will be described with reference to FIGS. 1 (a) and 1 (b). FIG. 1A is a perspective view showing the structure of the microstructure in this embodiment, and FIG. 1B is a cross-sectional view. The microstructure includes a substrate 101, a support frame 102 disposed so as to surround a predetermined region (movable structure forming region) of the substrate 101, and a movable part formed on the substrate 101 inside the support frame 102. The support part 103, the movable structure 104 including the beam 104a and the movable electrode 104b supported by the movable part support part 103, the fixed electrode support part 105a, and a part (end part) are supported by the fixed electrode support part 105a. And a fixed electrode 105b disposed on the movable electrode 104b. The fixed electrode support 105a and the fixed electrode 105b constitute a fixed electrode structure 105.

  The fixed electrode 105b is disposed on the substrate 101 so as to be spaced above the movable electrode 104b, and the fixed electrode 105b and the movable electrode 104b are disposed to face each other. In the microstructure of this embodiment configured as described above, an electrostatic attractive force is generated by applying a voltage between the movable electrode 104b and the fixed electrode 105b, and the beam 104a is deformed to displace the movable electrode 104b. By doing so, for example, a function as a variable capacitor is expressed.

  Here, the movable electrode 104b and the fixed electrode 105b are distinguished by the ease of displacement with respect to the substrate when a force such as electrostatic attractive force or vibration is applied to each electrode, in other words, the spring constant, The one having a smaller spring constant and being easily displaced is referred to as a movable electrode (movable structure), and the one having a large spring constant and less likely to be displaced is referred to as a fixed electrode (fixed electrode structure). In this embodiment, the spring constant of the movable structure is reduced by including the beam 104a having flexibility. In the movable structure, the spring constant may be reduced by providing the movable electrode portion with flexibility without providing a beam. For example, the movable electrode may be formed to a thickness that can be deformed (flexible) with respect to the generated electrostatic attractive force, and the fixed electrode may be formed to be thicker than this. Moreover, the movable electrode should just be formed so that it can be deform | transformed more easily compared with a fixed electrode by setting it as the state narrowly formed or formed longer.

  In addition, the microstructure in the present embodiment is supported by the fixed electrode structure 105 including the fixed electrode support portion 105a and the fixed electrode 105b and the support frame 102, and the space inside the support frame 102 (movable portion forming space). ) Is provided. Here, on the substrate 101, the fixed electrode 105 b (fixed electrode structure 105) is formed at the same height as the support frame 102. Note that the fixed electrode structure 105 and the support frame 102 do not have to be formed at the same height, as long as the sealing film 106 can be supported by the fixed electrode structure 105 and the support frame 102. These heights may be different. However, the state in which these are the same height is a state that can be more easily manufactured as described later, and is advantageous in manufacturing.

  The substrate 101 may be, for example, a silicon substrate having an insulating layer such as a silicon oxide film on its surface, an insulating substrate such as glass, or an SOI (Silicon On Insulator) substrate having a buried insulating layer. The surface of the region (movable part forming region) surrounded by the support frame 102 only needs to be made of an insulating material. An integrated circuit connected to the movable structure 104 via the movable portion support portion 103 and connected to the fixed electrode 105b via the fixed electrode support portion 105a may be formed on the substrate 101.

  For example, a semiconductor integrated circuit composed of an active element or a multilayer circuit structure is formed on a silicon substrate, and a support frame 102, a movable portion support portion 103, a movable structure 104, and the like are formed thereon via an interlayer insulating layer. The movable portion supporting portion 103 only needs to be connected to the semiconductor integrated circuit through a through hole formed in the interlayer insulating layer. An integrated circuit may be provided in another region of the substrate 101. Moreover, the movable part support part 103, the movable structure 104, the fixed electrode support part 105a, and the fixed electrode 105b should just be comprised from metal materials, such as Au, Cu, and Al.

  The sealing film 106 is made of an insulating material such as an organic resin, has the same shape as the region surrounded by the support frame 102, and the fixed electrode structure 105 including the fixed electrode support part 105 a and the fixed electrode 105 b and the support frame. 102. The film thickness of the sealing film 106 may be, for example, 1 μm or more and 100 μm or less. The strength for protecting the movable structure 104 is obtained by setting the thickness of the sealing film 106 to 1 μm or more, and the productivity is improved by setting the thickness to 100 μm or less.

  In this embodiment, since the formation region (space) of the movable structure 104 is surrounded by the support frame 102 and sealed by the sealing film 106, the movable structure 104 is shielded from the external environment. In addition, it is possible to prevent damage to the movable structure and change in characteristics due to adhesion of foreign matters and external mechanical impact in the mounting process.

  In addition, the sealing film 106 is supported at its peripheral portion by the support frame 102, and the inner region is also supported and reinforced by the movable structure 104 including the beam 104a and the movable electrode 104b. For this reason, the strength required for the sealing film 106 is reduced, and the sealing film 106 can be thinned. As a result, the fine structure can be made thinner, and, for example, more chips can be stacked and mounted.

  In addition, if the upper surface (a part) of the fixed electrode 105b is bonded to the inner surface of the sealing film 106, the fixed electrode 105b is mechanically coupled by the sealing film 106, and the strength is increased. It is in a more enhanced state. As a result, a fine structure in which the sealing film 106 and the like have sufficient resistance against the water flow in the mounting process and vibration during actual use can be obtained. For example, the sealing film 106 can be made of resin. If the sealing film 106 is made of a resin film, it can be easily formed by an STP method or the like, as will be described later. In addition, if the resin film is used, the sealing film 106 having a thickness of about 1 μm can be easily formed, and can be formed thinner than when glass or the like is used. It becomes easier. Further, if the inner side surface of the sealing film 106 is bonded to the fixed electrode 105b, the sealing film 106 can be prevented from being bent (swelled) outward with respect to the movable structure forming space.

  By the way, in order to increase the driving force of the actuator using the fine structure as described above and the detection sensitivity of the sensor, a fixed electrode and a movable electrode having a larger area are used. However, when the area of the fixed electrode is increased, the parasitic capacitance between the fixed electrode and the substrate also increases, which is a problem in a fine structure such as MEMS. An increase in parasitic capacitance causes a decrease in signal response speed, a decrease in detection sensitivity, and the like, and becomes a problem particularly when the fine structure is integrated with an LSI constituting a signal processing circuit or the like. In an LSI, a low resistance substrate is used for stable operation of the circuit, and in addition, since there are a large number of wirings on the substrate, it is an environment in which a large parasitic capacitance is likely to occur between the fixed electrode and the LSI. .

  On the other hand, according to the microstructure of the present embodiment, since the fixed electrode 105b is formed away from the substrate 101, the distance between the fixed electrode 105b and the substrate 101 increases, and the fixed electrode 105b is fixed. A space with a relative dielectric constant of approximately 1 is formed between the electrode 105b and the substrate 101. For this reason, in the microstructure of this embodiment, the parasitic capacitance between the fixed electrode 105b and the substrate 101 can be significantly reduced. In addition, since the movable electrode 104b is also arranged at a position separated from the substrate 101, the capacitance between the movable electrode 104b and the substrate 101 can be reduced. For example, by making the distance between the movable electrode 104b and the substrate 101 larger than the distance between the movable electrode 104b and the fixed electrode 105b, the influence of the parasitic capacitance on the characteristics of the movable structure 104 can be reduced. It becomes like this.

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view schematically showing the structure of the microstructure in the present embodiment. The microstructure includes a substrate 201, a support frame 202 arranged so as to surround a predetermined region (movable structure forming region) of the substrate 201, and a wiring support formed on the substrate 201 inside the support frame 202. A section 203 and a wiring 204 supported by the wiring support section 203. In addition, the movable structure 205 including the beam 205a and the movable electrode 205b connected (supported) to the movable portion connection portion 204a of the wiring 204, the fixed electrode support portion 206a formed on the substrate 201, and a part ( A fixed electrode 206b disposed on the movable electrode 205b with the end) supported by the fixed electrode support 206a. The fixed electrode support 206a and the fixed electrode 206b constitute a fixed electrode structure 206.

  The movable structure 205 is supported on the substrate 201 so as to be separated by being connected to the movable portion connection portion 204 a of the wiring 204. The movable structure 205 is supported by a part of the wiring 204. The fixed electrode 206b is disposed above the movable electrode 205b on the substrate 201, and the fixed electrode 206b and the movable electrode 205b are disposed to face each other. In the microstructure of the present embodiment configured as described above, an electrostatic attractive force is generated by applying a voltage between the movable electrode 205b and the fixed electrode 206b, and the beam 205a is deformed to displace the movable electrode 205b. By doing so, for example, a function as a variable capacitor is expressed.

  Further, in the present embodiment, the wiring 204 is supported on the wiring support portion 203, so that the wiring 204 is disposed apart from the substrate 101 in a region other than the wiring support portion 203. In other words, a space is formed between the wiring 204 and the substrate 201. As described above, in the present embodiment, in addition to the movable electrode and the fixed electrode, the wiring 204 that can form, for example, an inductor, a transformer, a transmission line, and the like is separated from the substrate 201 in the region surrounded by the support frame 202. Prepared in state.

  In addition, the microstructure in the present embodiment is supported by a wiring structure including the wiring support portion 203 and the wiring 204 in addition to the fixed electrode structure 206 and the support frame 202, and the space inside the support frame 202 (movable) A sealing film 207 for sealing a part forming space). Here, on the substrate 201, the fixed electrode structure 206 and the wiring structure are formed at the same height as the support frame 202. Note that the fixed electrode structure 206 and the wiring structure and the support frame 202 do not have to be formed at the same height, and the sealing film is formed between the fixed electrode structure 206 and the wiring structure and the support frame 202. As long as 207 can be supported, these heights may be different. However, the state in which these are the same height is a state that can be more easily manufactured as described later, and is advantageous in manufacturing.

  In this embodiment mode, the same as described above, and the substrate 201 includes, for example, a silicon substrate having an insulating layer such as a silicon oxide film on the surface, an insulating substrate such as glass, and a buried insulating layer. Any SOI (Silicon On Insulator) substrate may be used. Further, an integrated circuit may be formed on the substrate 201. Moreover, the wiring support part 203, the wiring 204, the movable structure 205, and the fixed electrode structure 206 should just be comprised from metal materials, such as Au, Cu, and Al.

  The sealing film 207 is made of an insulating material such as an organic resin, and has the same shape as the region surrounded by the support frame 202. The film thickness of the sealing film 207 may be, for example, 1 μm or more and 100 μm or less. The strength for protecting the wiring 204 is obtained by setting the thickness of the sealing film 207 to 1 μm or more, and the productivity is improved by setting the thickness to 100 μm or less.

  In this embodiment mode, since the formation region (space) of the wiring 204 is surrounded by the support frame 202 and sealed by the sealing film 106, the wiring 204, the movable structure 205, and the fixed electrode structure 206 are formed. Since it is cut off from the external environment, it is possible to prevent damage to internal structures and changes in characteristics due to adhesion of foreign matters and mechanical shocks from the outside in the mounting process.

  Further, the peripheral portion of the sealing film 207 is supported by the support frame 202, and the inner region is also supported and reinforced by the wiring 204 and the fixed electrode structure 206 supported by the wiring support portion 203. . For this reason, the strength required for the sealing film 207 is reduced, and the sealing film 207 can be thinned. As a result, the fine structure can be made thinner, and, for example, more chips can be stacked and mounted.

  In addition, if the upper surface (part) of the wiring 204 and the fixed electrode 206b is formed by bonding to the inner surface of the sealing film 207, the wiring 204 and the fixed electrode 206b are mechanically coupled by the sealing film 207. And the strength is further enhanced. As a result, a fine structure in which the sealing film 207 and the like have sufficient resistance against the water flow in the mounting process and vibration during actual use can be obtained. For example, the sealing film 207 can be made of resin. If the sealing film 207 is made of a resin film, it can be easily formed by an STP method or the like, as will be described later. In addition, when the resin film is used, the sealing film 207 having a film thickness of about 1 μm can be easily formed, and can be formed thinner than when glass or the like is used. It becomes easier. Further, if the inner side surface of the sealing film 207 is bonded to the fixed electrode 206b, the sealing film 207 can be prevented from being bent (swelled) outward with respect to the movable structure forming space.

  Moreover, since the fixed electrode 206b is formed away from the substrate 201 as in the above-described embodiment, the parasitic capacitance between the fixed electrode 206b and the substrate 201 can be significantly reduced. Further, since the movable electrode 205b is also arranged at a position separated from the substrate 201, a state in which the problem of parasitic capacitance with respect to the movable electrode 205b is suppressed is obtained as in the above-described embodiment.

[Embodiment 3]
Next, Embodiment 3 of the present invention will be described with reference to FIG. FIG. 3 is a perspective view showing the structure of the microstructure in the present embodiment. This fine structure includes a substrate 301 and a support frame 302 arranged so as to surround a predetermined region (movable structure forming region) of the substrate 301. In addition, the microstructure includes a switch 303, a variable capacitor 304, a transmission line 305, and an inductor 306 on a substrate 301 inside the support frame 302. The switch 303 and the variable edges 304 are elements of the movable structure and the fixed electrode structure described in the first embodiment or the second embodiment.

  In addition, in the present embodiment, the support electrode 302, the fixed electrode structure constituting the switch 303, the fixed electrode structure constituting the variable capacitor 303, the wiring structure constituting the transmission line 305, And a sealing film 310 supported by the wiring structure constituting the inductor 306. An integrated circuit that is electrically connected to elements on the substrate 301 surrounded by the support frame 302, such as the switch 303, the variable capacitance element 303, the transmission line 305, and the inductor 306, is formed on the substrate 301. Yes. In addition, as an element formed of the movable structure exemplified in the first and second embodiments, for example, a resonator using vibration due to displacement of the movable portion, an acceleration sensor due to displacement of the movable portion corresponding to acceleration, or the like Needless to say, the element may be disposed in a region surrounded by the support frame 302 as in the case of the switch 303 and the variable capacitor 303.

  Next, a method for manufacturing the microstructure in the above-described embodiment will be described with reference to FIGS. First, as shown in FIG. 4A, an interlayer insulating layer 401a made of, for example, a silicon oxide film is formed on a substrate 401 made of, for example, silicon. The substrate 401 may include a semiconductor integrated circuit composed of a plurality of transistors, resistors, capacitors, wirings, and the like. For example, a contact hole for electrically connecting to the wiring of the integrated circuit may include an interlayer insulating layer. You may form in the predetermined location of 401a. Note that FIGS. 4 to 6 show a partial region that is a portion of the minimum unit fine structure of the substrate 401, and a plurality of fine structures having the same configuration is formed in a region not illustrated of the substrate 401. Is formed.

  When such a substrate 401 is prepared, the first seed layer 402 is formed on the interlayer insulating layer 401a. The first seed layer 402 may be formed, for example, by first depositing titanium and then depositing gold thereon by sputtering or vapor deposition. The thickness of titanium may be about 0.1 μm, and the thickness of gold may be about 0.1 μm.

  Next, on the first seed layer 402, a first metal pattern 403a to be a part of a support frame, a second metal pattern 403b to be a wiring support part, and a third metal pattern 403c to be a fixed electrode support part are formed. State. The formation of these metal patterns will be briefly described. First, a photosensitive resist material is applied on the first seed layer 402 to form a photosensitive resist film, and exposure is performed using a mask having a desired pattern. By doing so, it is set as the state by which the resist pattern provided with the opening part in the desired location was formed. The film thickness of the photosensitive resist (resist pattern) may be about 15 μm.

  Next, a gold pattern is formed by plating on the first seed layer 402 exposed in the opening of the resist pattern, and then the resist pattern is removed. The plating film may be formed to a thickness of about 10 μm. As a result, a state in which the first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c are formed on the first seed layer 402 is obtained.

  Next, the first seed layer 402 is removed by etching using the first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c as a mask, and as shown in FIG. The first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c are electrically separated from each other. For example, gold on the upper layer of the first seed layer 402 may be wet-etched with an etching solution including iodine, ammonium iodide, water, and ethanol. The titanium under the first seed layer 402 exposed by this etching may be wet etched with a hydrogen fluoride aqueous solution.

  Next, as shown in FIG. 4C, the lower sacrificial layer 404 is formed so as to cover the separated first seed layer 402 and the first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c. Is formed. As the lower sacrificial layer 404, for example, a base resin such as polyamide, polyamic acid, polybenzoxazole (or a precursor thereof) added with a positive photosensitive agent may be used. The lower sacrificial layer 404 can be formed by spin coating these materials. As a positive photosensitive resin based on polybenzoxazole, for example, “CRC8300” manufactured by Sumitomo Bakelite Co., Ltd. is available.

  Next, as shown in FIG. 4D, the first metal pattern 403a, the second metal pattern 403b, and the lower sacrificial layer 404 above the third metal pattern 403c are removed, and the first metal pattern 403a, second metal pattern 403a, second metal pattern 403a, second metal pattern 403c are removed. The upper surfaces of the metal pattern 403b and the third metal pattern 403c are exposed. By patterning the lower sacrificial layer 404 having photosensitivity by a known lithography technique, the upper surfaces of the first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c can be exposed. When patterning the lower sacrificial layer 404, pre-baking at 120 ° C. is performed for about 4 minutes as pre-processing, and heat processing at about 310 ° C. is performed after patterning, so that the resin film is thermally cured.

  Next, as shown in FIG. 4E, the second seed layer 405 is formed on the exposed upper surfaces of the first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c and the upper surface of the lower sacrificial layer 404. It is assumed that it is formed. The second seed layer 405 may be formed in the same manner as the first seed layer 402, and the thickness of titanium may be about 0.1 μm and the thickness of gold may be about 0.1 μm.

  Next, as shown in FIG. 4F, a fourth metal pattern 406 serving as a movable structure is formed on the second seed layer 405. This may be formed in the same manner as the first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c. The film thickness of the resist pattern is about 2 μm, and the plating film is formed to a thickness of about 1 μm. do it.

  Next, the second seed layer 405 is removed by etching using the fourth metal pattern 406 as a mask, so that the second metal layer 406 is electrically separated corresponding to the fourth metal pattern 406 as shown in FIG. This formation may be performed similarly to the separation of the first seed layer 402.

  Next, as shown in FIG. 5H, an opening 407a, an opening 407b, and an opening 407c from which the upper surfaces of the first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c are exposed, The upper sacrificial layer 407 having an opening 407d from which a part of the front surface of the fourth metal pattern 406 is exposed is formed. In forming the upper sacrificial layer 407, the same resin material as that of the lower sacrificial layer 404 may be applied and patterned so as to cover the separated second seed layer 405 and fourth metal pattern 406.

  Next, as shown in FIG. 5I, the third seed layer 408 is formed on the upper sacrificial layer 407 including the inside of each opening. The third seed layer 408 may be formed in the same manner as the first seed layer 402 and the second seed layer 405.

  Next, as shown in FIG. 5 (j), a fifth metal pattern 409a serving as a part of the support frame, a sixth metal pattern 409b serving as a wiring, and a seventh metal pattern 409c serving as a fixed electrode are formed. And These formations are the same as those of the first metal pattern 403a, the second metal pattern 403b, the third metal pattern 403c, etc., and a resist pattern with a film thickness of 30 μm is used, and the film thickness of the plating film is about 20 μm. Just do it.

  Next, as shown in FIG. 5 (k), after the fifth metal pattern 409a, the sixth metal pattern 409b, and the seventh metal pattern 409c are formed, the third seed layer 408 is electrically formed corresponding to these. Separated. This separation may be performed similarly to the case of the first seed layer 402.

  Next, the lower sacrificial layer 404 and the upper sacrificial layer 407 are removed. As shown in FIG. 6L, first, the first seed layer 402 and the first metal pattern 403a are formed on the interlayer insulating layer 401a. , A support frame made of the third seed layer 408 and the fifth metal pattern 409a is formed. This support frame corresponds to the support frame 202 shown in FIG.

  In addition, a wiring support portion including the first seed layer 402 and the second metal pattern 403b is formed on the interlayer insulating layer 401a. This wiring support part corresponds to the wiring support part 203 shown in FIG. In addition, the fixed electrode support portion including the first seed layer 402 and the third metal pattern 403c is formed on the interlayer insulating layer 401a. This fixed electrode support portion corresponds to the fixed electrode support portion 206a shown in FIG.

  In addition, a wiring made of the third seed layer 408 and the sixth metal pattern 409b is formed on the wiring support portion. This wiring corresponds to the wiring 204 shown in FIG. In addition, a movable structure including the fourth metal pattern 406 and the second seed layer 405 is formed in a state of being connected to a part of the lower surface of the wiring. This movable structure corresponds to the movable structure 205 shown in FIG. In addition, a fixed electrode made of the third seed layer 408 and the seventh metal pattern 409c is formed on the fixed electrode support portion. This fixed electrode corresponds to the fixed electrode 206b shown in FIG.

  Here, the first metal pattern 403a, the second metal pattern 403b, and the third metal pattern 403c formed at the same time are formed at the same height (film thickness), and the fifth metal pattern 409a and the sixth metal pattern formed at the same time are formed. The metal pattern 409b and the seventh metal pattern 409c are formed at the same height. Each separated seed layer has the same film thickness. Therefore, the support frame, the wiring structure, and the fixed electrode structure formed by stacking these layers are in a state of being formed at the same height.

  Note that the lower sacrificial layer 404 and the upper sacrificial layer 407 may be removed by heating to 250 to 300 ° C. in an ozone atmosphere, for example. By bringing the upper sacrificial layer 407 and the lower sacrificial layer 404 into contact with such ozone, they can be removed by ashing.

  Next, as shown in FIG. 6M, a sealing film 410 having a thickness of about 10 μm is attached to the upper surfaces of the fifth metal pattern 409a, the sixth metal pattern 409b, and the seventh metal pattern 409c. And the internal space of the support frame is sealed.

  Hereinafter, an example of forming the sealing film 410 will be briefly described. The sealing film 410 may be formed by a well-known STP method (see Non-Patent Document 2). First, a sheet film is prepared in which a photosensitive resin film made of a photosensitive organic resin material and having a thickness of about 10 μm is applied and formed in advance. The photosensitive resin film becomes a sealing film. Next, the photosensitive resin film forming surface of the sheet film is thermocompression bonded to the upper surfaces of the fifth metal pattern 409a, the sixth metal pattern 409b, and the seventh metal pattern 409c. Next, the sheet film is peeled off from the photosensitive resin film, and heat treatment is performed on the photosensitive resin film at 100 ° C. for about 1 hour.

  Accordingly, a state in which the photosensitive resin film is attached to the upper surfaces of the fifth metal pattern 409a, the sixth metal pattern 409b, and the seventh metal pattern 409c is obtained. Needless to say, the photosensitive resin film may be formed not only by the STP method but also by other methods. Next, the photosensitive resin film is patterned by a well-known photolithography technique, the photosensitive resin film is processed into a planar shape of the fifth metal pattern 409a (support frame), and this is heated at a temperature condition of about 300 ° C. It only has to be cured.

  After the sealing film 410 is formed as described above, the support sealed in the sealing film 410 as described above, for example, by cutting (dicing) the substrate 401 into chips of a predetermined size. A plurality of chips each having a microstructure including a movable structure, a fixed electrode structure, and a wiring structure are formed in the frame. In this dicing, as is well known, a high-pressure water flow is supplied, but since the sealing film is formed in a state supported by the wiring structure together with the support frame, foreign matter adheres to the wiring structure. And damage to the wiring structure can be prevented.

  By the way, in the above description, the fifth metal pattern 409a serving as a support frame, the sixth metal pattern 409b serving as a wiring (wiring structure), and the seventh metal pattern 409c serving as a fixed electrode (fixed electrode structure) are formed as an interlayer insulating layer. Although formed so that it may become the same height on 401a (board | substrate 401), it does not restrict to this. These may be formed at different heights. However, when the portion to be the wiring structure disposed inside is formed higher than the support frame, it is preferable that the difference in height (step) is smaller than the thickness of the fixed electrode.

  When the step is larger than the thickness of the fixed electrode or the wiring, when the photosensitive resin film (sealing film 410) is bonded by the STP method as described above, the fixed electrode and the wiring are embedded in the resin film. Thus, the parasitic capacitance on the side of the fixed electrode and the wiring is increased. Further, in such a state, the resin film may enter the substrate side from the side of the wiring, and a part of the wiring structure may be damaged due to the entered resin film. In order to suppress such a state, the step is preferably smaller than the thickness of the fixed electrode and the wiring.

  In addition, when the support frame is formed higher than the portion to be the wiring structure disposed inside, it is preferable that the difference in height (step) is smaller than the thickness of the resin film to be attached. In this case, when the photosensitive resin film is bonded by the STP method as described above, the upper end portion of the support frame is embedded in the resin film. May penetrate through the resin film and cannot be sealed with the resin film. In order to suppress such a state, the step is preferably smaller than the thickness of the sealing film.

  In addition, although the manufacturing method of the fine structure demonstrated using FIG. 2 was demonstrated above, it cannot be overemphasized that the fine structure demonstrated using FIG. 1, FIG. 3 can also be manufactured by the same method.

It is the perspective view (a) and sectional drawing (b) which show the structure of the fine structure in Embodiment 1 of this invention. It is sectional drawing which shows typically the structure of the fine structure in Embodiment 2 of this invention. It is a perspective view which shows the structure of the fine structure in Embodiment 3 of this invention. It is process drawing which shows the example of the manufacturing method of the fine structure in embodiment of this invention. It is process drawing which shows the example of the manufacturing method of the fine structure in embodiment of this invention. It is process drawing which shows the example of the manufacturing method of the fine structure in embodiment of this invention. It is sectional drawing which shows the structure of the conventional fine structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Board | substrate, 102 ... Support frame, 103 ... Movable part support part, 104 ... Movable structure, 104a ... Beam, 104b ... Movable electrode, 105 ... Fixed electrode structure, 105a ... Fixed electrode support part, 105b ... Fixed electrode, 106: Sealing film.

Claims (6)

A substrate,
A support frame formed on the substrate and surrounding a predetermined area;
A wiring support portion formed in a region surrounded by the support frame on the substrate;
The wiring supported by the wiring support part and disposed at a distance from the surface of the substrate in a region surrounded by the support frame on the substrate;
A movable structure including a movable electrode spaced apart from the substrate , supported by a part of the wiring, and disposed in a region surrounded by the support frame on the substrate;
A fixed electrode structure disposed in a region surrounded by the support frame on the substrate, the fixed electrode disposed opposite to the upper portion of the movable electrode;
And at least a sealing film that is supported by the fixed electrode structure and the support frame and seals a region surrounded by the support frame ,
The microstructure is supported by a wiring structure including the wiring support portion and the wiring in addition to the fixed electrode structure and the support frame . The microstructure according to claim 1,
The microstructure is characterized in that the fixed electrode structure is formed at the same height as the support frame. The microstructure according to claim 1 or 2 ,
The microstructure is characterized in that the wiring constitutes at least one of an inductor, a transformer, and a transmission line. In the microstructure according to any one of claims 1 to 3 ,
The movable structure and the fixed electrode structure constitute at least one of a variable capacitor, a switch, a resonator, and an acceleration sensor. In the microstructure according to any one of claims 1 to 4 ,
The microstructure includes a semiconductor integrated circuit including an active element and a multilayer wiring, and the movable electrode and the fixed electrode are electrically connected to the semiconductor integrated circuit. A support frame that surrounds a predetermined region on the substrate by the metal film formed by laminating a metal film using a sacrificial film on the substrate, a wiring support portion disposed in a region surrounded by the support frame, A movable structure supported by the wiring support portion and disposed in a region surrounded by the support frame, a movable structure supported by a part of the wiring, and disposed in a region surrounded by the support frame and provided with a movable electrode And a step of forming a fixed electrode structure including a fixed electrode disposed in a region surrounded by the body and the support frame and disposed above the movable electrode; and
The sacrificial film is removed, the wiring is disposed away from the surface of the substrate, the movable electrode is disposed away from the upper portion of the substrate, and the fixed electrode is spaced apart from and opposed to the movable electrode. A step of placing the device;
After removing the sacrificial film, the support frame, the fixed electrode structure , and a sealing film that contacts the upper surface of the wiring structure including the wiring support portion and the wiring are pasted, and the support frame , the fixed electrode And a step of forming a sealing film that seals a region supported by the wiring structure and surrounded by the support frame. Method.

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