JP5417851B2 - MEMS device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a MEMS device and a manufacturing method thereof, and more particularly, to a structure and a manufacturing process suitable for increasing the reliability and performance of a MEMS device.

  MEMS (Micro Electro Mechanical Systems) is one of micro structure forming technologies, and refers to a technology for producing a fine electromechanical system such as a micron order or a product thereof. Since semiconductor chips are made by stacking thin films of silicon, oxide film, metal, etc. on a silicon substrate to make an electronic circuit, the circuit structure is usually composed of a planar pattern. That is, when semiconductor manufacturing technology is used, silicon is cut out as in machining to form micron-sized leaf springs, mirrors, rotating shafts, and the like, so that the MEMS structure has a three-dimensional structure.

  In a MEMS device having a MEMS structure as described above, a device structure can be configured compactly by providing a wiring structure portion formed by laminating a wiring and an insulating film together with the MEMS structure on a substrate. In addition, it is possible to achieve integration with other components such as a semiconductor circuit. Usually, the MEMS structure is disposed inside a cavity formed by removing a part of the wiring structure by etching or the like. The hollow portion may be left open upward, or may be accompanied by a lid composed of a covering layer that covers the hollow portion in order to seal the MEMS structure.

In some cases, a conductor wall (guard ring) made of a conductor provided in the wiring structure portion is provided so as to surround the periphery of the MEMS structure in a planar manner. Such a configuration is disclosed in the following Patent Documents 1 to 4. By providing such a conductor wall, it is possible to prevent the etching solution from entering the wiring structure portion in the release process by etching for forming the cavity portion around the MEMS structure.
JP 2006-224220 A JP 2007-35290 A JP 2008-115354 A JP 2008-221535 A

  By the way, as a design example of the conventional MEMS device, the structure shown in FIGS. 12 to 14 can be considered. Here, FIG. 12 is a schematic plan view of the MEMS device, FIG. 13 is a schematic longitudinal sectional view taken along line XIII-XIII in FIG. 12, and FIG. 14 is a schematic longitudinal sectional view taken along line XIV-XIV in FIG. . In this structure, the MEMS structure 3 including the fixed electrode 3a and the movable electrode 3b is formed on the insulating film 2a and the base layer 2b on the substrate 1, and the connection wirings 3c and 3d conductively connected thereto are connected to the conductive walls. 4, gaps 4 a and 4 b are formed in the conductive wall 4, and the connection wirings 3 c and 3 d are drawn out through the gaps 4 a and 4 b. The covering layer 5 is provided with an opening 5a communicating with the cavity 3C, and the opening 5a is closed by forming a sealing layer 6 thereon.

  However, if the gaps 4a and 4b are provided in a part of the conductor wall 4 as described above, the etching solution penetrates and remains through the gaps 4a and 4b during the etching for forming the cavity 3C. There is a risk that the reliability of the device may be lowered, such as corrosion of the wiring in the surrounding wiring structure. That is, since an insulating film having no etching resistance is disposed in the gaps 4a and 4b, the etching in the gaps 4a and 4b proceeds, and the etching solution oozes out from this portion to the surroundings. The wiring in the wiring structure portion may corrode and cause electrical problems. And since it is necessary to suppress the etching time in order to avoid such a decrease in reliability, the release (release) of the MEMS structure is incomplete due to insufficient etching amount, resulting in a device failure, etc. There is also a problem that the process margin of the manufacturing process is lowered and the product yield is lowered.

  On the other hand, when the conductor wall is configured so as to completely surround the MEMS structure in a plane, the etching range is limited to the inside of the conductor wall 4, so that problems such as a decrease in reliability do not occur. As described in Patent Document 2, it is necessary to configure the connection wirings 4a and 4b so as to pass below the conductor wall 4, which complicates the hierarchical structure on the substrate and increases the number of manufacturing steps. There is a problem of increasing.

  Furthermore, in any of the above structures, the parasitic capacitance between the MEMS structure 3 and the conductor wall 4 and the parasitic capacitance between the substrate 1 and the conductor wall 4 are increased. A point is also conceivable.

  Therefore, the present invention solves the above-mentioned problems, and the problem is that in a MEMS device, a structure capable of improving the reliability and performance while suppressing the complexity of the structure and the increase in the number of manufacturing steps, and the manufacturing thereof. It is to provide a method.

  In view of such circumstances, the MEMS device of the present invention has a substrate, a wiring structure formed on the substrate, in which wiring and an insulating film are laminated, and a periphery surrounded by the wiring structure. And a MEMS structure formed on the substrate in the cavity, wherein at least the MEMS is disposed around the MEMS structure as a part of the wiring structure. And a conductive wall configured to surround the planar structure in a height range in which the structure is formed, and a connection wiring for conductively connecting the MEMS structure and the conductive wall.

  According to the present invention, the wiring structure portion is provided with the conductor wall that surrounds the periphery of the MEMS structure at least in the height range where the MEMS structure is formed, and the MEMS structure is connected to the conductor wall via the connection wiring. By conductively connecting the body, by providing a conductor wall around the MEMS structure, the margin of the cavity forming process can be increased to increase the reliability of the MEMS device, and between the MEMS structure and the conductor wall. The parasitic capacitance between the conductor wall and the substrate can be reduced, so that the performance of the MEMS device can be improved. Further, since it is not necessary to ensure insulation between the conductor wall and the connection wiring as in the prior art, it is not necessary to draw out the connection wiring by bypassing the conductor wall. The surrounding structure can be configured easily, and the complexity of the structure and the increase in manufacturing man-hours can be suppressed.

  In the present invention, the conductor wall can be configured to completely surround the MEMS structure in a planar manner, which increases the reliability of the MEMS device and increases the process margin of the etching process for forming a cavity during manufacture. Although it is the most preferable aspect in ensuring, it does not necessarily need to be configured in this way. For example, although the conductor wall is configured to surround the MEMS structure in a plane, a gap may be provided in the conductor wall. In addition, a connection wiring (for example, a second connection wiring described later) that is conductively connected to a MEMS structure different from the connection wiring may be drawn out through the gap.

  In one aspect of the present invention, the connection wiring is disposed on the inner side of the conductor wall, and is connected to the inner connection wiring portion that conductively connects the MEMS structure and the conductor wall, and is further drawn out from the conductor wall. And an outer connection wiring portion. According to this, the MEMS structure and the conductor wall are conductively connected by the inner connection wiring disposed inside the conductor wall, and the conductor wall is connected to the appropriate structure in the outer wiring structure portion by the outer connection wiring, for example, In addition, it can be conductively connected to semiconductor circuits, various electronic elements, terminals, and the like.

  In one aspect of the present invention, a second insulating material that is insulated from the conductor wall, passes through the substrate side of the conductor wall or the inside of the substrate, and is drawn out of the conductor wall from the MEMS structure. Connection wiring is further provided. For example, in a MEMS structure such as a MEMS vibrator (resonator), a MEMS switch, a MEMS actuator, or the like, it is necessary to connect two or more connection wires that are insulated from each other. A second connection wiring different from one connection wiring (that is, a first connection wiring described later) constituted by the connection wiring is required. The second connection wiring must be insulated from the conductor wall, and is therefore configured to pass away from the conductor wall while being separated from the conductor wall.

  As a configuration having the above-described second connection wiring, the MEMS structure is insulated from the first structure portion disposed on the substrate side and the first structure portion. A second structure portion disposed on a side opposite to the substrate (for example, a side closer to the conductor wall than the first structure portion), and the first structure portion is electrically connected to the second connection wiring. In some cases, the second structure portion is conductively connected to the inner connection wiring. In this case, since the second structure portion disposed on the side opposite to the substrate is conductively connected to the inner connection wiring, the second structure portion and the conductor wall are conductively connected. And parasitic capacitance between the conductor walls can be reduced. Further, since the first structure portion arranged on the substrate side is conductively connected to the second connection wiring that passes below the conductor wall, the connection configuration of the MEMS structure to the connection wiring can be easily configured. .

  As a configuration having the above-described second connection wiring, the MEMS structure is insulated from the first structure portion disposed on the substrate side and the first structure portion. A second structure portion disposed on a side opposite to the substrate (for example, a side closer to the conductor wall than the first structure portion), and the first structure portion is conductively connected to the inner connection wiring, The second structure portion may be conductively connected to the second connection wiring. In this case, the parasitic capacitance between the conductor wall and the substrate can be reduced by setting the second connection wiring to the substrate potential.

  In another aspect of the present invention, the semiconductor device further includes a conductive coating layer that is spaced apart from the MEMS structure and covers the cavity from above and has an opening that communicates with the cavity. Conductive connection is made with the conductor wall. According to this, since the coating layer covering the upper part of the MEMS structure is conductively connected to the conductor wall, both the upper side and the lateral side of the MEMS structure are covered with the integral conductor. It is possible to reduce the influence of the field.

  In this case, it is preferable that the connection portion between the covering layer and the conductor wall is configured to surround the periphery of the MEMS structure in a plane. In this way, since the MEMS structure is entirely surrounded by the integrated conductor on the substrate, the influence of the external electromagnetic field can be further reduced, and the influence on the reliability by the etching process can be further reduced.

  In another aspect of the present invention, the MEMS structure includes a fixed electrode fixed on the substrate, and a movable electrode including a movable part facing the fixed electrode via a gap, and the fixed structure The movable part operates in such a manner that the gap is increased or decreased by an electrostatic force between the electrode and the movable electrode. Such a configuration corresponds to a specific structure of many MEMS devices such as a MEMS switch and a MEMS actuator. In this case, in particular, the MEMS structure may be a MEMS vibrator constituting a vibrator in which the movable part vibrates. The fixed electrode corresponds to the first structure portion, and the movable electrode corresponds to the second structure portion.

  Next, a method for manufacturing a MEMS device according to the present invention includes a step of forming a MEMS structure on a substrate, a step of forming a wiring structure portion formed by laminating a wiring and an insulating film on the substrate, and the MEMS structure. A step of deleting at least a part of the wiring structure formed on the body and forming a cavity around the MEMS structure, the manufacturing method of the MEMS device comprising: In at least one of the step of forming and the step of forming the wiring structure part, as a part of the wiring structure part, the periphery of the MEMS structure is planarized at least in the height range where the MEMS structure is formed A conductive wall that is configured to surround the conductive wall, and a connection wiring that is disposed inside the conductive wall and that conductively connects the MEMS structure and the conductive wall. The features.

  In the present invention, the conductive wall and the connection wiring may be formed of the same material simultaneously with the MEMS structure, or may be formed of the same material simultaneously with the wiring of the wiring structure portion. In any case, the conductor wall, the inner connection wiring, and the outer connection wiring can be formed without increasing the number of manufacturing steps.

  In one aspect of the present invention, the conductor wall is formed of the same material as a conductor included in the MEMS structure at the same time as the MEMS structure in a height range in which the MEMS structure is formed, and the MEMS. The wiring material is formed of the same material as the wiring simultaneously with the step of forming the wiring structure portion in a range exceeding the height range where the structure is formed. According to this, the conductor wall is formed of the same material at the same time as the conductor of the MEMS structure in the height range where the MEMS structure is formed, and is formed of the same material at the same time as the wiring in the range exceeding the height range. Thus, the conductor wall can be formed up to a high layer level on the substrate without increasing the number of manufacturing steps.

  The connection wiring is preferably formed of the same material as the conductor included in the MEMS structure. In this case, by simultaneously forming the conductor of the MEMS structure and each of the connection wirings with the same material, problems such as conductive connectivity and pattern deviation between the MEMS structure and these connection wirings can be avoided. it can.

  In another aspect of the present invention, in the step of forming the wiring structure portion, the MEMS structure is covered from above while being separated from the MEMS structure, and is integrally connected to the conductor wall, and the MEMS structure A conductive covering layer having an opening for enabling a step of forming a cavity around the body is formed of the same material as the wiring. According to this, since the formation process of the coating layer is simultaneously performed in the process of forming the wiring of the wiring structure portion, there is no need to provide a separate formation process of the coating layer, thereby reducing the number of manufacturing steps and the manufacturing cost. Can be achieved.

  According to the MEMS device and the manufacturing method thereof of the present invention, it is possible to improve the reliability and performance of the MEMS device while avoiding the complicated structure of the MEMS device and the increase in the number of manufacturing steps. obtain.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
First, the structure of the MEMS device according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic plan view of the MEMS device of the present embodiment, and FIG. 2 is a schematic longitudinal sectional view of the same embodiment. Note that the MEMS device depicted in the drawings and described below is based on the premise that a MEMS vibrator is configured, but the present invention is not limited to the MEMS vibrator as described later.

  As shown in FIG. 1, the present embodiment is a MEMS device in which a substrate (wafer) 10 made of a semiconductor such as single crystal silicon is used as a base, and a MEMS structure 20 is formed on the substrate 10. However, the substrate 10 for simply configuring the MEMS device is not limited to a semiconductor, and a substrate made of various materials such as glass, ceramics, and resin can be used.

  An insulating film 11 made of silicon oxide or the like is formed on the surface of the substrate 10 as necessary, and insulation from the substrate 10 is ensured. However, when the substrate 10 is made of a highly insulating material such as glass, ceramics, resin, or a low-doping semiconductor, or when a substrate having an insulating film formed on the surface (for example, an SOI substrate) is used. The insulating film 11 is not necessary.

  In addition, an underlayer 12 having resistance to etching in a release process described later is formed on the surface of the substrate 10. In the case of using a general silicon-based semiconductor manufacturing technique, the underlayer 12 is composed of a silicon nitride film formed by a CVD method or the like. This underlayer 12 is preferably formed in a limited range within the release process.

  In the present embodiment, the second connection wiring 24 is formed on the insulating film 11. The second connection wiring 24 is made of a metal such as aluminum or copper, a semiconductor (polysilicon layer) provided with conductivity by doping or the like.

  On the substrate 10, a lower layer pattern made of a conductor is formed by predetermined patterning, and the first structure portion 21 that can function as a fixed electrode is formed by this lower layer pattern. The first structure portion 21 is conductively connected to the second connection wiring 24 through the opening 12 a formed in the base layer 12. Further, an upper layer pattern is formed on the first structure portion 21, and the second structure portion 22 that faces the first structure portion 21 with a gap and functions as a movable electrode by the upper layer pattern, The first connection wiring 25 and the annular pattern portion 26 that are integrated with each other are formed. The first structure portion (fixed electrode) 21 and the second structure portion (movable electrode) 22 constitute a MEMS structure 20 disposed on the base layer 12.

  On the substrate 10, a wiring structure 30 is formed in which the wirings 14 and 16 and the insulating films 13, 15 and 17 are alternately stacked. Since the wiring structure portion 30 only needs to be formed by laminating the wiring and the insulating film, the wiring structure and the insulating film may be formed by only one layer each, and one or more of them are formed. It may be. The wiring structure portion 30 is configured to surround the MEMS structure 20 in a planar manner. In the illustrated example, the wiring structure 30 surrounds the MEMS structure 20 so as to completely surround the MEMS structure 20, and a cavity 20 </ b> C in which the wiring structure 30 does not exist is formed around the MEMS structure 20.

  The wiring structure portion 30 includes a conductor wall 31 disposed around the MEMS structure 20 or the cavity portion 20C. The conductor wall 31 includes an annular pattern portion 26 configured as a part of the upper layer pattern, an annular wall portion 14X configured of a part of the wiring 14 connected on the annular pattern portion 26, and the annular wall portion. And an annular wall portion 16X constituted by a part of the wiring 16 connected on the 14X.

  In the present specification, the term “annular” is defined as a structure configured to surround a certain object in a planar manner. Therefore, as long as it is a form that forms a figure closed in a planar manner, it does not need to be an annular shape, and may have an arbitrary planar shape such as a rectangular frame shape.

  The annular wall portion 14X is formed integrally with the annular pattern portion 14U disposed on the insulating film 15 and the annular pattern portion 14U, and is electrically connected to the annular pattern portion 26 through the insulating film 13. The annular through-hole 14L. The annular wall portion 16X is formed integrally with the annular pattern portion 16U disposed on the insulating film 17 and the annular pattern portion 16U, and is electrically connected to the annular pattern portion 14U through the insulating film 15. It is comprised from the cyclic | annular penetration part 16L connected. The annular pattern portion 26, the annular wall portion 14X, and the annular wall portion 16X are each configured in an annular shape, and each connecting portion between them is also configured in an annular shape, thereby surrounding the MEMS structure 20 in a plane. An integral conductor wall 31 is formed.

  In the illustrated example, the conductor wall 31 is exposed on the inner side surface of the cavity 20C, and the insulating films 13, 15, 17 and the later-described sacrificial layer of the wiring structure 30 are not present inside the conductor wall 31. The Thereby, the influence on the MEMS structure due to impurities contained in the insulating films 13, 15, 17 and the sacrificial layer can be reduced. However, in the present invention, the insulating films 13, 15, 17 and the sacrificial layer may remain somewhat inside the conductor wall 31.

  In the present embodiment, the movable part 22a of the second structure part 22 projects from both sides of the first structure part 21, and the movable part 22a is disposed above the first structure part 21 (opposite the substrate). Has been. The second structure portion 22 is integrally connected to the first structure portion 21 on both sides by connecting portions 22b that avoid the first structure portion 21 in plan view. The movable portion 22a is configured to operate by electrostatic force by applying a potential difference between the first structure portion 21 and the second structure portion 22. Since the illustrated example is a configuration example of the MEMS vibrator, the movable portion 22a vibrates up and down by applying an AC signal between the two structural portions. In addition, the movable portion 22a is disposed so as to overlap the first structure portion 21 in the entire width direction, and the first structure portion 21 is seen from the edge in the width direction of the movable portion 22a when viewed in a plan view. Each is formed so as to project on both sides.

  The second connection wiring 24 drawn out from the first structure portion 21 follows a path that is avoided in a plane so as not to overlap the second structure portion 22 in a plane, and passes below the conductor wall 31 to be planar. As seen, the conductor wall 31 is pulled out. Depending on the device configuration, the second connection wiring 24 is grounded to the substrate 10, connected to a semiconductor circuit or electronic element (not shown), or conductively connected to a connection terminal portion formed on the surface of the MEMS device. Or Further, the second connection wiring 24 is connected to the wiring 14 via the wiring pattern part of the wiring structure part 30, if necessary, through the impurity region provided in the surface layer part of the substrate 10, or the like. It is connected to a semiconductor circuit or an electronic element or a connection terminal portion.

  Further, the first connection wiring 25 drawn from the second structure portion 22 includes an inner connection wiring 25a disposed inside the conductor wall 31 in plan view and an outer connection disposed outside the conductor wall 31. Wiring 25b. The inner connection wiring 25a conductively connects the second structure portion 22 of the MEMS structure 20 and the conductor wall 31, and the outer connection wiring 25b is led out from the conductor wall 31. The same semiconductor circuit or electronic element as described above, Alternatively, it is conductively connected to a connection terminal portion or the like.

  In the present embodiment, the outer connection wiring 25 b is connected to a semiconductor circuit formed on the substrate 10 through one wiring pattern of the wiring 14, in the illustrated example, to the electronic element 40 therein. In the illustrated example, the electronic element 40 includes impurity regions 41 and 42 formed in the surface layer portion of the substrate 10, a channel region 43 formed between these impurity regions 41 and 42, and the channel region 43. And a gate electrode 45 disposed opposite to the channel region 43 with the gate insulating film 44 interposed therebetween. The gate insulating film 44 can be formed of the same material simultaneously with the sacrificial layer described later, and the gate electrode 45 can be formed of the same material simultaneously with the lower layer pattern or the upper layer pattern.

  In the present embodiment, the surface of the base layer 12 constitutes the bottom surface of the cavity 20C, and the first connection wiring 25 is formed on the bottom surface. That is, the first connection wiring 25 is provided in the same height range as the MEMS structure 20, and is formed in the same layer as the first structure portion 21 and the annular pattern portion 26 in the illustrated example. The first connection wiring 25 intersects with the conductor wall 31, and a portion inside the conductor wall 31 from the intersection is an inner connection wiring portion 25 a and a portion outside the intersection is an outer connection wiring portion 25 b. However, unlike the illustrated example in which the inner connection wiring portion 25a and the outer connection wiring portion 25b are both conductively connected to the conductor wall 31 at the intersection, the inner connection wiring portion 25a and the outer connection wiring portion 25b are connected to the conductor wall 31. Each of the other parts may be conductively connected.

  A protective film 18 is formed on the insulating film 17, and the protective film 18 has an opening 18a for exposing the cavity 20C. The protective film 18 is preferably composed of a silicon nitride film, but may be composed of other inorganic films or organic resins. Note that the MEMS device may not include the protective film 18.

  In the present embodiment, the inner connection wiring portion 25 a that is conductively connected to the second structure portion 22 of the MEMS structure 20 is conductively connected to the conductor wall 31, and the outer connection wiring portion 25 b is drawn from the conductor wall 31. Therefore, the second structural portion 22 can be conductively connected to the outside circuit, terminal, or the like via the conductor wall 31. In this case, since there is no need to bypass the conductor wall 31 from the MEMS structure 20 as in the prior art and to draw out the wiring, the hierarchical structure around the MEMS structure 20 can be easily configured. It is possible to reduce the size, the number of manufacturing steps, and the manufacturing cost.

  Further, since the second structure portion 22 is conductively connected to the conductor wall 31 by the inner connection wiring portion 25a, the parasitic capacitance between the MEMS structure 20 and the conductor wall 31 can be reduced. In particular, since the second structure portion 22 disposed on the conductor wall 31 side (the side opposite to the substrate 10) from the first structure portion 21 is conductively connected to the conductor wall 31, the parasitic capacitance can be reduced more effectively. Enhanced. Thereby, for example, in the MEMS vibrator, the floor level can be reduced and the filter characteristics can be improved (insertion loss can be reduced), so that the performance of the MEMS device can be improved.

  Further, in the present embodiment, in the MEMS structure 20, the first structure portion 21 configured by the lower layer pattern is conductively connected to the second connection wiring 24 that passes below the conductor wall 31 and configured by the upper layer pattern. Since the second structure portion 22 is conductively connected to the first connection wiring 25 connected to the conductor wall 31, the upper and lower arrangement of the MEMS structure 20, the first connection wiring 25, and the second connection wiring 24 are used. Therefore, the peripheral structure of the MEMS structure 20 can be configured more easily.

  In the present embodiment, the MEMS structure 20 is configured so that the conductor wall 31 completely surrounds the plane, and the entire inner surface of the conductor wall 31 faces the cavity 20C, that is, inside the conductor wall 31. The insulating film and other materials are configured not to remain. As a result, the MEMS structure 20 can be prevented from being contaminated due to the movement of impurities or the generation of gas due to the insulating film or other materials. However, the present invention is not limited to such an embodiment, and an insulating film or other material may be present on the inner surface of the conductor wall 31.

  In the present embodiment, the second structure portion 22 is conductively connected to the semiconductor circuit or the electronic element 40 via the first connection wiring 25, but the first structure portion 21 is connected to the second connection. It may be conductively connected to the semiconductor circuit or the electronic element 40 via the wiring 24, or both the first structure portion 21 and the second structure portion 22 are conductively connected to the semiconductor circuit or the electronic element, respectively. May be. Further, one of the first structure portion 21 and the second structure portion 22 may be conductively connected to the substrate 10 or a ground potential. These connection modes are appropriately set according to the configuration, operation principle, usage method, and the like of the MEMS device.

  Further, the first connection wiring 25 and the second connection wiring 24 are connected to the semiconductor circuit via any conductor such as an appropriate wiring pattern portion of the wirings 14 and 16 or an impurity region provided in the surface layer portion of the substrate 10. Alternatively, it may be connected to an electronic element, a connection terminal, the substrate 10 or the like.

[Second Embodiment]
Next, a MEMS device according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a schematic plan view of the MEMS device of the present embodiment, and FIG. 4 is a schematic longitudinal sectional view of the same embodiment. In the present embodiment, portions corresponding to the respective portions of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the present embodiment, the first structure portion 21 of the MEMS structure 20 is conductively connected to the first connection wiring 25, and the second structure portion 22 is conductively connected to the second connection wiring 24. Although different from the first embodiment, other configurations such as the substrate, the insulating film 11, the underlayer 12, the MEMS structure 20, the cavity 20C, the wiring structure 30, and the conductor wall 31 are described in the first embodiment. It is the same.

  Also in the present embodiment, the first connection wiring 25 and the annular pattern portion 26 are integrally formed, and thereby the first structure portion 21 is conductively connected to the conductor wall 31. The second structure portion 21 is conductively connected to the second connection wiring 24 through the opening 12 b provided in the base layer 12, and the second connection wiring is connected to the semiconductor circuit via a part of the wiring pattern of the wiring 14. Alternatively, the electronic element 40 is conductively connected.

  In the present embodiment, since the first structure portion 21 is conductively connected to the conductor wall 31, the parasitic capacitance between the MEMS structure 20 and the conductor wall 31 can be reduced as in the first embodiment. The performance of the MEMS device can be improved. Here, the first structure portion 21 that is conductively connected to the conductor wall 31 is disposed on the substrate 10 side (the side opposite to the conductor wall 31) from the second structure portion 22, but the parasitic capacitance reduction effect itself. Is obtained. Further, when the first structure portion 21 is set at the potential of the substrate 10 (for example, when both are set at the ground potential), the parasitic capacitance between the conductor wall 31 and the substrate 10 can also be reduced.

  Also in this embodiment, the variations of the respective parts described in the first embodiment can be similarly configured.

[Third Embodiment]
Next, a MEMS device according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a schematic plan view of the MEMS device of the present embodiment, and FIG. 6 is a schematic longitudinal sectional view of the same embodiment. Also in this embodiment, parts corresponding to the parts of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the present embodiment, the configuration of the MEMS structure 20 is the same as that of the first embodiment except that the structure is different from that of the first embodiment. Therefore, the description of the same points as in the first embodiment is omitted. In addition, the present embodiment can be configured in the same manner as the second embodiment with respect to points other than the structure of the MEMS structure 20.

  In the present embodiment, the MEMS structure 20 includes a first structure portion 21 and a second structure portion having a movable portion 22 a that protrudes from one side of the first structure portion 21 to the upper side of the first structure portion 21. 22 is provided. Then, the second connection wiring 24 that is conductively connected to the first structure portion 21 is drawn to the opposite side to the second structure portion 22. In addition, the first connection wiring 25 that is conductively connected to the second structure portion 22 is drawn to the opposite side to the first structure portion 21. In addition, the movable portion 22a is disposed so as to overlap the first structure portion 21 in the entire width direction, and the first structure portion 21 is seen from the edge in the width direction of the movable portion 22a when viewed in a plan view. Each is formed so as to project on both sides.

  In the MEMS structure 20 configured as described above, since the basic structure including the first structure portion 21 and the second structure portion 22 can be easily configured, the size of the MEMS device can be reduced.

[Fourth Embodiment]
Next, a MEMS device according to a fourth embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a schematic plan view of the MEMS device of the present embodiment, and FIG. 8 is a schematic longitudinal sectional view of the same embodiment. In the present embodiment, portions corresponding to the respective portions of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the present embodiment, the basic structure including the insulating film 11, the base layer 12, the MEMS structure 20, and the wiring structure portion 30 on the substrate 10 is configured in the same manner as in the first embodiment. Moreover, these basic structures can also be comprised similarly to the said 3rd Embodiment. Therefore, description of the basic structure is omitted in the following description.

  In the present embodiment, a coating layer 16Y that covers the MEMS structure 20 from above is formed on the upper portion of the cavity 20C that is surrounded by the conductor wall 31 in a plan view. The covering layer 16 </ b> Y is configured by a part of the wiring 16 included in the wiring structure unit 30. The covering layer 16Y is formed with one or a plurality of openings 16a communicating with the cavity 20C. The opening 16a of the covering layer 16Y is closed by a sealing layer 19 formed on the covering layer 16Y. The covering layer 16Y and the sealing layer 19 constitute a lid for sealing the MEMS structure 20 by sealing the cavity 20C. Thus, since the cavity part 20C is sealed with the lid body, the MEMS structure 20 can be sealed, so that contamination and malfunction of the MEMS structure 20 can be prevented. Moreover, since the cavity 20C can be depressurized (vacuum) or filled with an inert gas or the like, the performance of the MEMS device can be ensured or improved.

  In the present embodiment, the conductor wall 31 includes an annular pattern portion 26 similar to the first embodiment, an annular wall portion 14X constituted by a part of the wiring 14, and an annular wall portion 16X constituted by a part of the wiring 16. However, the upper portion of the conductor wall 31 is connected to the coating layer 16 </ b> Y constituted by a part of the wiring 16. In particular, since the connecting portion of the covering layer 16Y and the conductor wall 31 is provided over the entire circumference surrounding the MEMS structure 20 in a plane, the MEMS structure 20 is substantially surrounded by the conductor on the substrate 10. Will be. Therefore, the influence of the external electromagnetic field on the MEMS structure 20 can be almost blocked. From such a viewpoint, the effect of electromagnetic shielding can be further enhanced by forming the sealing layer 19 from a conductor.

  In this embodiment, since the cavity 20C is sealed, if an insulating film or other material remains in the cavity 20C, it is caused by movement of impurities or generation of gas due to the insulating film or other material with respect to the MEMS structure 20. The effect of contamination will increase. However, in the illustrated example, the MEMS structure 20 is configured such that the conductor wall 31 completely surrounds the plane, and the entire inner surface of the conductor wall 31 faces the cavity 20C, that is, the inside of the conductor wall 31. Therefore, the MEMS film 20 can be prevented from being contaminated. However, the present invention is not limited to such an embodiment, and an insulating film or other material may be present on the inner surface of the conductor wall 31.

[Fifth Embodiment]
Next, a MEMS device according to a fifth embodiment of the invention will be described with reference to FIGS. FIG. 9 is a schematic plan view of the MEMS device of the present embodiment, and FIG. 10 is a schematic longitudinal sectional view of the same embodiment. In the present embodiment, portions corresponding to the respective portions of the second embodiment are given the same reference numerals, and descriptions thereof are omitted.

  In the present embodiment, the basic structure including the insulating film 11, the base layer 12, the MEMS structure 20, and the wiring structure portion 30 on the substrate 10 is configured in the same manner as in the second embodiment. Moreover, these basic structures can also be comprised similarly to the said 3rd Embodiment. Therefore, description of the basic structure is omitted in the following description.

  Further, in the present embodiment, the structure of the lid body including the covering layer 16Y and the sealing layer 19 and the relationship between the lid body and the conductor wall 14 are the same as those in the fourth embodiment. Therefore, the effect of sealing the MEMS structure 20 by providing the lid and the electromagnetic shielding effect can be obtained as in the fourth embodiment.

[Sixth Embodiment]
Next, an embodiment of a method for manufacturing a MEMS device according to the present invention will be described with reference to FIG. FIG. 11 is a schematic process cross-sectional view (a) to (d) of a main process of a method for manufacturing a MEMS device. In addition, although this embodiment presupposes the case where the MEMS device of the said 4th Embodiment is manufactured, a part of process is similarly replaced also about said 1st Embodiment thru | or 3rd Embodiment or 5th Embodiment. Or can be easily realized by omitting.

  In this embodiment, as shown in FIG. 11A, for example, an insulating film 11 made of silicon oxide or the like is formed on a substrate 10 made of, for example, a silicon substrate by a thermal oxidation method, a CVD method, or the like. The second connection wiring 24 is formed with a conductor pattern such as aluminum or copper by sputtering or photolithography. Thereafter, the base layer 12 made of silicon nitride or the like is formed by CVD or sputtering. The underlayer 12 functions as an etching stop layer in a release process described later. However, the opening 12 a communicating with the second connection wiring 24 is formed in the base layer 12.

  Thereafter, as a lower layer pattern, a first conductor 21 is formed by forming a film with a conductive material, for example, conductive polysilicon by a CVD method or the like, and patterning with a photolithography method or the like. The first structure portion 21 is formed in a region including the opening 12a on the base layer 12, and is conductively connected to the second connection wiring 24 through the opening 12a. However, when the basic structure of the second embodiment is manufactured, the first structure portion 21 is formed in a region avoiding the opening 12b (see FIG. 4), and a first connection wiring 25 and an annular pattern portion 26, which will be described later, are formed. And conductively connected.

  Next, a sacrificial layer 23 is formed on the first structure portion 21. In the illustrated example, the sacrificial layer 23 is formed so as to cover the entire first structure portion 21. In this case, the sacrificial layer 23 can be formed by film formation by a CVD method, a sputtering method, or the like, but may be formed by surface oxidation of the first structure portion 21. For example, when the first structure portion 21 is composed of a silicon layer, a silicon thermal oxide film formed by a thermal oxidation method can be used as the sacrificial layer 23.

  Next, an upper layer pattern made of a conductive material such as conductive polysilicon is formed on the sacrificial layer 23. Then, the second structure portion 22, the first connection wiring 25, and the annular pattern portion 26 are formed by this upper layer pattern. In the present embodiment, the second structure portion 22 is configured as an integral pattern so as to be conductively connected to the first connection wiring 25 and the annular pattern portion 26. However, when the basic structure of the second embodiment is manufactured, the second structure portion 22 is formed in a region including the opening 12b (see FIG. 4) and is conductively connected to the second connection wiring 24.

  In this embodiment, the first structure portion 21 is formed by the lower layer pattern, and the second structure portion 22, the first connection wiring 25, and the annular pattern portion 26 are formed by the upper layer pattern. Alternatively, the first structure portion 21, the first connection wiring 25, and the annular pattern portion 26 may be formed with a lower layer pattern, and the second structure portion 22 may be formed with an upper layer pattern. The former is preferable when manufacturing the basic structure of the first embodiment as in this embodiment, and the latter is preferable when manufacturing the basic structure of the second embodiment. In any case, the second structure portion 22 is provided with a movable portion 22 a formed on the sacrificial layer 23.

  As the conductor constituting the lower layer pattern and the upper layer pattern, it is preferable to use silicon provided with conductivity as described above. For example, polycrystalline silicon or amorphous silicon into which an n-type dopant such as phosphorus is introduced as an impurity. The dopant is not limited to the n-type dopant, and a p-type dopant such as boron can also be used. Such a material can be easily formed by a CVD method, a sputtering method, or the like. However, the material may be any material as long as it is a conductive material having a degree of conductivity necessary for the operation of the MEMS structure 20, and may be, for example, a metal such as aluminum.

  Thereafter, the MEMS structure 20 having the first structure portion 21 and the second structure portion 22, the first connection wiring 25 and the annular pattern portion 26, and the base layer 12 are configured with a conductor pattern such as aluminum or copper. A wiring structure portion 30 is provided in which the wirings 14 and 16 and the insulating films 13, 15 and 17 made of an interlayer insulating film such as silicon oxide are alternately stacked.

  Here, annular openings are provided in the insulating films 13 and 15 so as to surround the MEMS structure 20, and the wirings 14 and 16 are formed in a region including the openings, thereby being arranged in these annular openings. The annular wall portions 14X and 16X are formed by the annular through portions 14L and 16L and the annular pattern portions 14U and 16U disposed on the insulating films 13, 15, and 17, respectively. A conductor wall 31 is formed by the annular pattern portion 26 and the annular wall portions 14X and 16X.

  Further, when the wiring 16 is formed, a coating layer 16 </ b> Y is formed on the insulating film 15 on the MEMS structure 20. The covering layer 16Y has the opening 16a as described above. The opening 16a is also formed at the same time as the wiring 16 is patterned. Since the insulating films 13 and 15 stacked on the MEMS structure 20 reflect the thickness of the MEMS structure 20 so as to protrude slightly upward as illustrated, the coating layer 16Y also protrudes upward. The curved surface is formed. The insulating film 17 is patterned so that the region including the opening 16a of the coating layer 16Y is exposed. Thereafter, as shown in FIG. 11B, a protective film 18 made of silicon nitride, organic resin, or the like is formed on the uppermost portion, and an opening 18a that exposes a region including the opening 16a of the covering layer 16Y also on the protective film 18 is formed. Is provided.

  Next, in the state shown in FIG. 11B, the sacrificial layer 23 and the insulating films 13 and 15 are etched through the opening 16a of the coating layer 16Y using an etchant such as buffered hydrofluoric acid mainly containing hydrofluoric acid. A release process is performed, and a cavity 20C is formed around the MEMS structure 20 as shown in FIG.

  In the present embodiment, the lower ground of the MEMS structure 20 is formed by the underlayer 12 having resistance to the etching, and the periphery of the MEMS structure 20 is surrounded by the conductor wall 31 having resistance to the etching. Even if sufficient time is taken, there is no possibility that the etching range extends downward from the base surface or around the conductor wall 31. Accordingly, the etching can be sufficiently performed so that the sacrificial layer 23 does not remain in the narrow portion such as the opposing region of the first structure portion 21 and the second structure portion 22, so that a sufficient margin for the release process is ensured. can do. That is, the MEMS structure 20 can be reliably released (released), and erosion along the boundary surface of the insulating film on the outer side of the conductor wall 31 due to the penetration of the etching solution into the periphery, Corrosion can be avoided. Therefore, by stabilizing the characteristics of the MEMS device and improving reproducibility, it is possible to improve characteristic accuracy and yield, and to improve device reliability.

  In particular, in this embodiment, the covering layer 16Y is integrally connected to the conductor wall 31, and the covering layer 16Y and the conductor wall 31 are connected over the entire circumference, so that the entire height range on the base surface is increased. Since the etching range can be defined over the range, the above effect can be further enhanced.

  In the MEMS structure 20 configured as described above, the movable portion 22a provided in the second structure portion 22 is disposed to face the first structure portion 21 with a gap. Accordingly, the movable portion 22a is brought into a movable state. Therefore, when an AC signal is applied between the first structure portion 21 that is a fixed electrode and the second structure portion 22 that is a movable electrode, the movable portion 22a is caused by an electrostatic force. Vibrates in the vertical direction in the figure in a manner to increase or decrease the gap.

  Further, in the present embodiment, as described above, the coating layer 16Y has a curved surface curved so as to be convex upward, so that the coating layer 16Y can be prevented from being deformed in the vertical direction during the release step or thereafter. The rigidity can be increased, and the possibility that the covering layer 16Y is depressed due to the manufacturing conditions or the like (this causes a defect of the MEMS device) can be reduced.

  Next, as shown in FIG. 11 (d), a sealing layer 19 is formed on the covering layer 16Y, and the cavity 20C is sealed by closing the opening 16a. As a result, the MEMS structure 20 is sealed. The sealing layer 19 is preferably formed by a vapor phase method such as vapor deposition, sputtering, or CVD. In this case, without providing a separate step, the cavity 20C may be sealed in the same reduced pressure state (vacuum state) as when the vapor phase method is applied, or in a state in which an inert gas or the like is sealed. it can. The sealing layer 19 can also be formed by applying an organic resin or the like on the coating layer 16Y.

  In the present embodiment, the conductor wall 31 is formed of the same material at the same time as the first structure portion 21 or the second structure portion 22 of the MEMS structure 20 in the height range in which the MEMS structure 20 is formed. In the range exceeding the height range in which the structure 20 is formed, since the same material is formed at the same time as the wirings 14 and 16 of the wiring structure portion 30, the conductor wall 31 is increased to a high layer level on the substrate without increasing the number of manufacturing steps. Can be formed.

  However, when the conductor wall 31 may have a lower structure than the illustrated example, the conductor wall 31 is the same as the wirings 14 and 16 of the wiring structure portion 30 in the height range where the MEMS structure 20 is formed. It can be formed of a material.

  In the present embodiment, since the coating layer 16Y is formed in the same process as the wiring 16 of the wiring structure portion 30, an increase in the number of manufacturing steps can be suppressed in this respect.

  In addition, the manufacturing method of the MEMS device of this invention is not limited only to the above-mentioned illustration example, Of course, various changes can be added within the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, a MEMS device having a cantilever-shaped operation unit structure has been described as an example of the MEMS device. However, as the MEMS device of the present invention, both support units are connected to both sides of the movable unit. It may have a cantilever-like moving part structure, or may have a moving part structure in which three or more support parts are connected around the movable part.

  In the above embodiment, the MEMS vibrator has been described as an example. However, the present invention has a movable part that is operatively supported by a support part, for example, a MEMS actuator, a MEMS switch, a MEMS sensor (acceleration). The present invention can be widely applied to various MEMS devices such as a sensor and a pressure sensor) or those having a three-dimensional structure on a substrate.

1 is a schematic plan view of a MEMS device according to a first embodiment. The schematic longitudinal cross-sectional view of the MEMS device of 1st Embodiment. The schematic plan view of the MEMS device of 2nd Embodiment. The schematic longitudinal cross-sectional view of the MEMS device of 2nd Embodiment. The schematic plan view of the MEMS device of 3rd Embodiment. The schematic longitudinal cross-sectional view of the MEMS device of 3rd Embodiment. The schematic plan view of the MEMS device of 4th Embodiment. The schematic longitudinal cross-sectional view of the MEMS device of 4th Embodiment. The schematic plan view of the MEMS device of 5th Embodiment. The schematic longitudinal cross-sectional view of the MEMS device of 5th Embodiment. Schematic process sectional drawing (a)-(d) which shows the manufacturing method of the MEMS device of 6th Embodiment typically. The schematic plan view of the MEMS device of a comparative example. The schematic longitudinal cross-sectional view of the MEMS device of a comparative example. Schematic longitudinal sectional view of another cross-sectional position of the MEMS device of the comparative example

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 11 ... Insulating film, 12 ... Underlayer, 13, 15, 17 ... Insulating film, 14, 16 ... Wiring, 14X, 16X ... Annular wall part, 14L, 16L ... Annular penetration part, 14U, 16U ... Annular Pattern part, 16Y ... coating layer, 16a ... opening, 18 ... protective film, 19 ... sealing layer, 20 ... MEMS structure, 21 ... first structure part, 22 ... second structure part, 22a ... movable part, 23 ... Sacrificial layer, 24 ... Second connection wiring, 25 ... First connection wiring, 25a ... Inner connection wiring, 25b ... Outer connection wiring, 26 ... Ring pattern part, 30 ... Wiring structure part, 31 ... Conductor wall, 40 ... Electronic element

Claims (10)

A substrate, a wiring structure formed on the substrate, in which wiring and an insulating film are laminated, a cavity surrounded by the wiring structure in a planar manner, and the cavity in the cavity on the substrate A MEMS structure comprising: a fixed electrode formed; and a movable electrode facing the fixed electrode with a gap between the MEMS structure,
As a part of the wiring structure part, a conductor wall configured to surround the periphery of the MEMS structure planarly at least in a height range in which the MEMS structure is formed;
A first connection wiring for conductively connecting the movable electrode and the conductor wall;
A second connection wiring conductively connected to the fixed electrode;
A MEMS device comprising: The first connection wiring is disposed inside the conductor wall, and includes an inner connection wiring portion that conductively connects the MEMS structure and the conductor wall, and an outer connection wiring portion that is further drawn outward from the conductor wall. The MEMS device according to claim 1, comprising: The said 2nd connection wiring is insulated from the said conductor wall, and passes below the said conductor wall or the inside of the said board | substrate, and is withdraw | derived to the outer side of the said conductor wall. The described MEMS device.   It further comprises a conductive covering layer that is spaced apart from the MEMS structure to cover the cavity from above and has an opening that communicates with the cavity, and the covering layer is configured integrally with the conductor wall. The MEMS device according to any one of claims 1 to 3, wherein: 5. The device according to claim 1, wherein at least one of the first connection wiring and the second connection wiring is made of the same material as the conductor included in the MEMS structure. 6. MEMS device. The MEMS device according to claim 1, wherein the conductor wall is made of the same material as the MEMS structure in a height range in which the MEMS structure is formed. Forming a MEMS structure including a fixed electrode and a movable electrode facing the fixed electrode with a gap on the substrate; and forming a wiring structure formed by stacking a wiring and an insulating film on the substrate. And a step of deleting at least part of the wiring structure formed on the MEMS structure to form a cavity around the MEMS structure, and a method for manufacturing a MEMS device,
  In at least one of the step of forming the MEMS structure and the step of forming the wiring structure part, at least the MEMS structure is formed around the MEMS structure as a part of the wiring structure part. A conductor wall configured to surround in a plane in a height range, a first connection wiring disposed inside the conductor wall and conductively connecting the movable electrode and the conductor wall; and the fixed electrode and the conductive wall A method of manufacturing a MEMS device, comprising: forming a second connection wiring to be connected. The conductor wall is formed of the same material as a conductor included in the MEMS structure at the same time as the MEMS structure in a height range in which the MEMS structure is formed, and a height range in which the MEMS structure is formed. The method for manufacturing a MEMS device according to claim 7, wherein the wiring device is formed of the same material as that of the wiring at the same time as the step of forming the wiring structure portion. 9. The MEMS device according to claim 7, wherein at least one of the first connection wiring and the second connection wiring is formed of the same material simultaneously with a conductor included in the MEMS structure. Manufacturing method. In the step of forming the wiring structure portion, the MEMS structure body is separated from the MEMS structure body to cover the MEMS structure body from above, and is integrally connected to the conductor wall, and a cavity is formed around the MEMS structure body. 10. The method of manufacturing a MEMS device according to claim 7, wherein a conductive coating layer having an opening for enabling a process is formed of the same material simultaneously with the wiring. 11. .

Images