JP4608993B2 - Micro electromechanical element, method for manufacturing the same, and electronic apparatus - Google Patents

Description

The present invention is infinitesimal electromechanical device and a manufacturing method thereof, and an electronic apparatus including a micro-electromechanical device.

  Microstructures, and microelectromechanical elements using electrostatic drive, so-called MEMS (Micro Electro Mechanical Systems) elements, have been developed. 20A and 20B are typical examples of general micro electromechanical elements. The microelectromechanical element 1 supports a substrate side electrode (hereinafter referred to as a lower electrode) 3 formed on a substrate 2, a beam 5 arranged in parallel to face the lower electrode 3, and one end of the beam 5. And a support portion 6. The beam 5 and the lower electrode 3 are electrically insulated by a space 4 therebetween. The beam 5 is formed in a cantilever structure in which one end thereof is supported by the substrate 2 via a support portion 6 integral therewith.

  As the substrate 2, for example, a substrate in which an insulating film is formed on a semiconductor substrate such as silicon (Si) or gallium arsenide (GaAs), or an insulating substrate such as a quartz substrate or a glass substrate is used. The lower electrode 3 is formed of a polycrystalline silicon film doped with impurities, a metal film (polycrystalline W, Cr), or the like. The beam 3 is a driving side electrode (hereinafter referred to as an upper electrode) 8 made of an insulating film (not shown) such as a silicon nitride film (SiN film) and an Al film having a thickness of about 100 nm formed on the upper surface thereof. It consists of.

  In this micro electromechanical element 1, the beam 5 is displaced by an electrostatic force generated between the lower electrode 3 and the lower electrode 3 according to the potential applied to the lower electrode 3 and the upper electrode 8, and for example, as shown in FIG. Are displaced in a parallel state (solid line) and an inclined state (broken line).

FIGS. 21A and 21B are other typical examples of general microelectromechanical elements. The microelectromechanical element 11 includes a lower electrode 3 formed on the substrate 2 and a beam 12 arranged so as to straddle the lower electrode 3 in a bridge shape. The beam 12 and the lower electrode 3 are electrically insulated by a space 14 therebetween. The beam 12 is formed in a double-supported beam structure in which both ends thereof are supported by the substrate 2 via support portions 13 [13A, 13B] integral therewith. The beam 12 is formed of a two-layer film of an insulating film (not shown) and the upper electrode 15 as described above.
In this microelectromechanical element 11, it is displaced by an electrostatic force generated between the beam 12 and the lower electrode 3 according to the potential applied to the lower electrode 3 and the upper electrode 15, for example, as shown by the solid line and the broken line in FIG. 21B. The beam 12 is displaced in a parallel state and a recessed state with respect to the lower electrode 3.

  On the other hand, the micro electro mechanical element as described above is easily affected by the external environment such as temperature, atmospheric pressure, and micro particles. For this reason, it is often desirable to spatially seal the beam that is the movable structure portion. There are also many microstructures that require a sealed structure or a divided structure, such as a fluid flow path.

  At present, several methods for obtaining a sealed structure in a microelectromechanical element have been proposed. FIG. 18 illustrates one method. This method is a method of directly covering the microelectromechanical element by bonding or the like. That is, as shown in FIG. 18, a micro electromechanical element 25 is formed by forming a beam 24 having a lower electrode 23 and an upper electrode on a substrate 22 by using a semiconductor process first. Here, the sacrificial layer is removed to form the hollow structure of the beam 24. After the process of removing the sacrificial layer is completed, a cup-shaped lid 26 made of glass or the like is disposed on the substrate 22 so as to cover the entire microelectromechanical element 25, and the lid 26 and the substrate 22 are joined. A sealed structure is obtained. As the bonding, in addition to the direct bonding between the Si substrate 22 and the lid 26 of another material, for example, adhesion by reflow of the metal layer 27 is performed.

  Further, as a method for obtaining a sealed structure using a semiconductor process, a method shown in FIG. 19 is conceivable. First, as shown in FIG. 19A, the lower electrode 23 on the substrate 22 is formed, the beam 24 is formed through the sacrificial layer 28, and the sacrificial layer 29 covering the entire microelectromechanical element 25 is formed. Next, a sealing layer 31 is deposited so as to cover the sacrificial layer 29, and a sacrificial layer hole 30 is formed in a part of the upper surface of the sealing layer 31. The sacrificial layers 29 and 28 are removed by selective etching through the hole 30. By removing the sacrificial layers 29 and 28, a space 32 is formed below the sealing layer 31. Next, as shown in FIG. 19B, the hole 30 is sealed with a sealing material 33 by some method (shown by a chain line). In this way, a sealed structure in which the microelectromechanical element 25 is sealed is obtained. Several techniques have been proposed as a method for sealing the punched holes 30. For example, a method using an organic polymer resin having poor leakage is disclosed in Patent Document 1 (manufacturing method of a fine structure).

JP 2002-365153 A.

  By the way, in the sealing method in which the lid body 26 and the substrate 22 in FIG. 18 described above are directly sealed as a method for sealing the microelectromechanical element, the combinations of materials that can be bonded are limited, and the difference in stress after the bonding, etc. There are concerns such as deformation and destruction by In addition, it is not always an appropriate method for sealing a finer space.

As a method of sealing a finer space, the sealing method of FIG. 19 is suitable. However, the problem with this method is sealing the hole 30 after the sacrificial layer is removed. For example, when sealing is performed using a sputtering method, a CVD (chemical vapor deposition) method, or the like, in a normal method, as shown in FIG. 19B, the sealing material 33 passes through the hole 30 and is deposited in the internal space. The Therefore, if the punched hole 30 is large, sealing becomes extremely difficult. Even when the hole 30 is small, the degree of sealing is often a problem. Furthermore, this method is difficult to apply when a beam 24, a circuit, or the like is present below the punch hole 30.

  Further, when the volume of the internal space 32 to be sealed is large, there is a concern that the sacrificial layers 29 and 28 cannot be sufficiently removed if the sacrifice hole 30 is small. In order to solve this, it is conceivable to form a large number of small holes 30, but when there are a large number of holes 30, all of them must be sealed, resulting in yield problems. .

  In view of the above, a novel technique that can easily form a sealed space using a semiconductor process in a microstructure, an electrostatically driven microelectromechanical element, or the like is desired.

In view of the above points, intended to provide an electronic apparatus including infinitesimal electromechanical device and a manufacturing method thereof which is adapted to sealing structure can be easily formed, and a microelectromechanical device with semiconductor process is there.

A microelectromechanical device according to the present invention is formed on a substrate, and includes an electrostatically driven microelectromechanical device body formed of a lower electrode and a beam facing the lower electrode with a space in between, and a substrate. After removing the sacrificial layer that is formed and surrounds the microelectromechanical element body and is supported on the outer side of the outer wall part on the substrate and higher than the microelectromechanical element body, and formed in the manufacturing process An upper film that falls downward due to the tensile stress of the film itself, tightly contacts the upper surface of the outer wall part and hermetically seals the space surrounded by the outer wall part, and is formed by the upper film and the outer wall part The micro electromechanical element body is sealed in a sealed space.

In the present invention, the upper film can be formed of a film having a tensile stress in the uniaxial direction and can be supported on the substrate at both ends in the uniaxial direction .
In the present invention, the upper film can be formed of a film having a tensile stress in the biaxial direction, and can be supported on the substrate at four end portions in the biaxial direction .

In the present invention, a reflow material layer can be interposed between the upper film and the upper surface of the outer wall portion.
In the present invention, the upper film can be formed of a film having a tensile stress in a room temperature atmosphere.
In this invention, it can be set as the structure which has the coating film formed covering the area | region from the upper surface of an upper film to the side surface of the full width of an outer wall part in the direction orthogonal to a uniaxial direction.

The method for manufacturing a microelectromechanical element according to the present invention forms a lower electrode, which will later become an electrostatically driven microelectromechanical element body, and a beam facing the lower electrode with a sacrificial layer interposed therebetween on a substrate. A step of enclosing the microelectromechanical element body and forming an outer wall part higher than the microelectromechanical element body, and a step of forming a sacrificial layer so as to cover the outer wall part including the inside and outside of the outer wall part Have Furthermore, a process of forming an upper film having a tensile stress supported on the substrate surface including the upper surface of the sacrificial layer covering the outer wall part and including the upper surface of the outer wall part, and removing each sacrificial layer A step of lowering the upper film downward due to the tensile stress of the upper film and closely contacting the upper surface of the outer wall part to hermetically seal the space surrounded by the outer wall part. The micro electromechanical element body is sealed in the formed sealed space.

In the present invention, using a membrane having one axial tensile stress in the upper layer, can it to support the substrate surface upper layer at both ends of the one axial direction.
In the present invention, using a membrane having two axial tensile stress in the upper layer, can it to support the substrate surface upper layer at four ends of the two axial directions.

In the present invention, the sacrificial layer covering the outer wall portion is formed by the first sacrificial layer and the second sacrificial layer having different etching characteristics, and the first sacrificial layer is formed between the lower electrode and the beam. After forming the second sacrificial layer outside the outer wall with the same etching characteristics, and etching away the sacrificial layer between the first sacrificial layer and the lower electrode and the beam, The second sacrificial layer can be removed by etching, and the upper film can be lowered by the tensile stress of the upper film to be in close contact with the upper surface of the outer wall portion.

In the present invention, the upper film is formed of a film having a tensile stress in a room temperature atmosphere, the sacrificial layer is removed in a temperature atmosphere higher than room temperature, and the upper film is not lowered downward in a state where the sacrificial layer is removed. After removing the sacrificial layer , a tensile stress can be generated in the upper film in a room temperature atmosphere, and the upper film can be lowered to adhere to the upper surface of the outer wall portion.

In the present invention, the upper film is formed of a two-layer film of a film having a compressive stress and a film having a tensile stress, and after removing the sacrificial layer, the film having the upper compressive stress in the upper film is removed to have a tensile stress. The stress of the upper film only of the film can be released, and the upper film of only the film having the tensile stress can be lowered to be in close contact with the upper surface of the outer wall portion.

In the present invention, before forming the sacrificial layer, the step of forming the reflow material layer on the upper surface of the outer wall and the sacrificial layer are removed, and the upper film is lowered to contact the reflow material layer on the upper surface of the outer wall. Then, a step of reflowing the reflow material layer can be provided.
In the present invention, after the step of bringing the upper film into close contact with the upper surface of the outer wall portion, a coating film covering the region from the upper surface of the upper film to the full width side surface of the outer wall portion is formed in a direction perpendicular to the uniaxial direction. It is possible to have a process of performing.

Electronic device according to the present invention, any of the micro-electromechanical device described above, Ru formed comprises.
The electronic apparatus according to the present invention includes a filter that limits the band of a transmission signal and / or a reception signal, and can be configured as a communication device using any of the above-described micro electromechanical elements as a filter.

According to the micro-electromechanical device according to the present invention, by utilizing its own pull-clad stress of the upper film, the upper layer is in close contact with the upper surface of the outer periphery wall section surrounding the automatically lowered by micro-electromechanical device body . The microelectromechanical element body is sealed by the close contact of the upper film with the upper surface of the outer wall portion. That is, a micro electro mechanical element having a sealed micro electro mechanical element body can be easily realized by using a semiconductor process.

According to the method for manufacturing a microelectromechanical element according to the present invention, the sacrificial layer is formed so as to cover the outer wall including the inner and outer sides of the outer wall surrounding the microelectromechanical element body , and includes the upper surface of the sacrificial layer. After forming the upper film having a tensile stress that reaches the substrate surface outside the surrounding wall , by removing the sacrificial layer, the upper film is automatically lowered by its own tensile stress to remove the sacrificial layer. Adhere to the top surface of The microelectromechanical element main body is hermetically sealed by the close contact of the upper film with the upper surface of the outer wall portion, and a micro structure having a sealed structure can be manufactured. In the present invention, such a microstructure can be easily manufactured using a semiconductor process.

Furthermore, according to the micro-electromechanical device and a manufacturing method thereof of the present invention, by using a membrane having one axial tensile stress in the upper part film, after removing the sacrificial layer, the upper layer is tensile in one axial direction It is automatically lowered and closely contacts the upper surface of the outer wall.
By using a film having a tensile stress in the biaxial direction as the upper film, after removing the sacrificial layer, the upper film is pulled in the biaxial direction and automatically falls and closely contacts the upper surface of the outer wall portion. In this case, since the upper film is pulled and lowered in the biaxial direction, the sealing degree can be increased.

By forming the first and second sacrificial layers having different etching characteristics as the sacrificial layer and removing the two sacrificial layers in stages, the remaining sacrificial layer inside the sealed structure is avoided, resulting from the sacrificial layer remaining. It is possible to reduce the malfunction of the microelectromechanical element main body and improve the yield.
When the upper film is formed of a film having a tensile stress in a room temperature atmosphere and the sacrificial layer is removed in a high temperature atmosphere, the upper film is not lowered, and a tensile stress is generated in the upper film in the subsequent room temperature atmosphere to remove the upper film. By lowering and adhering to the upper surface of the surrounding wall portion, the sacrificial layer in the sealed structure can be surely removed, the malfunction of the microelectromechanical element main body due to the remaining sacrificial layer can be reduced, and the yield can be improved. it can.

By forming the upper film with a two-layer film of a film having compressive stress and a film having tensile stress, even if the sacrificial layer is removed, the two-layer film does not drop because the stress is balanced. Thereafter, by removing the film having a compressive stress, the stress of Mino upper layer of a film having a tensile stress is released, automatically upper layer is lowered to contact the upper surface of the outer periphery wall section. Also in this case, the sacrificial layer in the sealed structure can be surely removed, the malfunction of the microelectromechanical element body due to the remaining sacrificial layer can be reduced, and the yield can be improved.

Before the sacrificial layer is formed, a reflow material layer is formed on the upper surface of the outer wall portion, and after the upper film is brought into contact with the outer wall portion, the upper film is brought into close contact with the upper surface of the outer wall portion by reflow treatment. The degree of sealing can be further improved.
After the sacrificial layer is removed and the upper film is brought into close contact with the upper surface of the outer wall portion, a coating film that covers the region from the upper surface of the upper film to the side surface of the entire width of the outer wall portion in a direction perpendicular to the uniaxial direction. By forming, the degree of sealing can be further improved.

According to the electronic apparatus of the present invention, by providing a microelectromechanical device good sealing level infinitesimal electromechanical device body is closed above, it is possible to improve the reliability of this type of electronic equipment. For example, a communication device with improved reliability can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

The present invention provides a dense closed is required microelectromechanical device (so-called MEMS device), using a membrane having a high tensile stress, is to automatically form a sealed structure.

  FIG. 1 shows an embodiment of a microelectromechanical element (so-called MEMS element) according to the present invention. The microelectromechanical element 41 according to the present embodiment has a microelectromechanical element body 46 composed of a lower electrode 43 and a beam 45 opposed to the lower electrode 43 across a space 44 on a substrate 42, An outer wall portion 48 is formed so as to surround the microelectromechanical element body 46, and an upper film 49 lowered due to film characteristics, that is, tensile stress, is in close contact with the upper surface of the outer wall portion 48. The outer wall 48 and the upper film 49 are hermetically sealed. The upper film 49 is formed so that the central region covers the region surrounded by the outer wall portion 48, and is fixed to the substrate 42 as support portions 49A and 49B whose both ends are fixed points. The micro electro mechanical element main body 46 is disposed in a sealed space formed by the outer wall portion 48 and the upper film 49.

  The outer wall 48 and the upper film 49 are made of a material that can be used in a semiconductor process. As described above, the substrate 42 may be a substrate in which an insulating film is formed on a semiconductor substrate such as silicon (Si) or gallium arsenide (GaAs), or an insulating substrate such as a quartz substrate or a glass substrate. The lower electrode 43 is formed of a polycrystalline silicon film doped with impurities, a metal film (polycrystalline W, Cr), or the like. The beam 45 includes a silicon nitride film (SiN film), a silicon oxide film (SiO2 film), other insulating films (not shown), and an upper electrode (not shown) formed on the upper surface thereof.

  According to the microelectromechanical element 41 according to the present embodiment, the microelectromechanical element body is configured to automatically descend and closely contact the upper surface of the outer wall portion by the tensile stress of the upper film itself. It is enclosed in the enclosed space by the outer wall and the upper membrane. As a result, the micro electromechanical element main body can be easily sealed using a semiconductor process, and the above-described concern about the conventional sealed structure can be solved.

  Next, each embodiment of the microelectromechanical element according to the present invention will be described together with its manufacturing method.

2 to 3 show the microelectromechanical element according to the first embodiment. In the present embodiment, an upper film having a strong tensile stress is formed on a sacrificial layer, and the sacrificial layer is removed to automatically obtain a microelectromechanical element having a sealed structure.
First, as shown in FIG. 2A, the lower electrode 43 is formed in the formation region of the microelectromechanical element main body on the substrate 42, and the required height H1, ie, surrounding the formation region outside the formation region, that is, A surrounding wall portion 48 higher than the height position of the beam to be formed later is formed. Further, the first sacrificial layer 51 is selectively formed so as to cover the lower electrode 43, and a beam 45 extending from the upper surface of the sacrificial layer 51 to the surface of the substrate 42 is formed. The beam 45 is formed by an insulating film and an upper electrode thereon. The sacrificial layer 51 is selectively formed in the outer wall portion 48 and outside the outer wall portion 48 at the same time, and the sacrificial layer 51 having a pair of openings 53A and 53B is formed outside the outer wall portion 48 with the outer wall portion 48 interposed therebetween. Is done. The thickness H2 of the first sacrificial layer 51 is set to a thickness lower than the height H1 of the outer wall portion 48.

  Next, as shown in FIG. 2B, the second sacrificial layer 54 is formed so as to be higher than the upper surface of the outer wall portion 48. That is, the height H 3 from the upper surface of the second sacrificial layer 54 to the surface of the substrate 42 is higher than the height H 1 of the outer wall portion 48. The second sacrificial layer 54 is patterned by selective etching. The second sacrificial layer 54 is formed in a region including the outer wall portion 48, the outer wall portion 48, and a part of the outer wall portion 48. Here, the etching depth of the second sacrificial layer 54 may be a depth that is lower than the height H1 of the outer wall portion 48 outside the outer wall portion 48, and is particularly accurate with respect to the etching depth. There is no need to etch. The first and second sacrificial layers 51 and 54 are made of the same material or a material that can be removed by the same process. The upper surface of the second sacrificial layer 54 is formed on a flat surface by a process such as CMP (Chemical Mechanical Polishing).

  Next, as shown in FIG. 2C, an upper film 49 having a strong tensile stress is deposited on the first and second sacrificial layers 51 and 54 and including the openings 53A and 53B. Patterning is performed with a width covering 48. Portions corresponding to the openings 53A and 53B of the upper film 49 become support portions 49A and 49B fixed to the substrate 42. As the upper film 49 having a strong tensile stress, for example, a silicon nitride film (SiN film) formed by a low pressure CVD method can be used.

Next, as shown in FIG. 3D, the first and second sacrificial layers 51 and 54 are removed. For example, when the sacrificial layers 51 and 54 are formed of a polysilicon film, they are removed by etching using an XeF ₂ etching gas. As a result, a micro electromechanical element main body 46 is formed by the lower electrode 43 and the beam 45 opposed across the space 44. When the sacrificial layers 51 and 54 are completely removed, the upper film 49 having a strong tensile stress is also released at the same time. At this time, the upper film 49 is pulled in both directions by the stress F1.

  As shown in FIG. 3E, due to the tensile stress F1 of the upper film 49 itself, the upper film 49 shifts downward (falls) and automatically adheres to the upper surface of the outer wall portion 48. A sealed space 55 is formed by the portion 48 and the upper film 49. That is, the target micro electro mechanical element 411 in which the micro electro mechanical element body 46 is sealed in the sealed space 55 is obtained.

  4A and 4B show the result of analyzing the shape before and after the upper film 49 is released by simulation. Before removing the sacrificial layer shown in FIG. 4A (before releasing), the shape of the upper film 49 is a shape along the sacrificial layer. For example, the height d1 of each step is 500 nm and the height d2 is 300 nm. Then, as shown in FIG. 4B, after removing the sacrificial layer (after release), tensile stress acts on the entire upper film 49, and the upper film 49 is lowered by itself, for example, the upper surface has a height d3 = 300 nm. I understand that

  According to the first embodiment, after the sacrificial layers 51 and 54 are removed, the upper film 49 is covered with the outer wall 48 surrounding the microelectromechanical element main body 46 by its own tensile stress F1, and is hollow. It is possible to realize a micro electro mechanical element having a sealed structure including the micro electro mechanical element body 46 having a structure inside. A micro-electromechanical element that requires high-sealing packaging or a desirable micro-electromechanical element can be easily realized using a semiconductor process.

  FIG. 5 schematically shows the configuration of the outer wall portion 48 and the upper film 49 when a film having a tensile stress F1 in the uniaxial direction is used as the upper film 49 of the first embodiment.

FIG. 6 shows a microelectromechanical element according to the second embodiment. In the present embodiment, a micro electromechanical element in which the upper film having a strong tensile stress is subjected to stress in two axial directions to increase the hermeticity is obtained.
The microelectromechanical element 412 according to the second embodiment has the same basic structure as the structure of the first embodiment. In particular, as shown in the schematic diagram of FIG. 48 has a central region 49E that covers the region surrounded by 48 and support portions 49A, 49B, and 49C, 49D that are fixed points in the biaxial direction, so that the tensile stresses F2, F3 act in the biaxial direction. It is formed in a simple film structure. The other configuration is the same as that of the first embodiment, and thus redundant description is omitted.

  According to the second embodiment, by having the upper film 49 having tensile stress in the biaxial direction, the adhesion between the outer wall portion 48 and the upper film 49 is further improved, and the internal sealing degree is further improved. be able to. And the micro electro mechanical element 412 of this Embodiment can raise a sealing degree more about the sealing structure which contains the micro electro mechanical element 46 of a hollow structure inside. However, since the footprint (so-called occupied area) of this structure increases, it is desirable to use it together with the first embodiment in accordance with the application and requirements.

  7 and 8 show a microelectromechanical element according to a third embodiment. In the present embodiment, a microelectromechanical element having a sealed structure that does not cause an internal sacrificial layer residue is obtained by a plurality of stages of sacrificial layer removal processes. The basic structure according to the third embodiment is the same as the structure of the first embodiment or the second embodiment.

First, as shown in FIG. 7A, after the lower electrode 43, the surrounding wall 48, the first sacrificial layer 51, and the microelectromechanical element 45 are formed on the substrate 42 in the same manner as described above, a plurality of etching characteristics are different. Forming a sacrificial layer. In this example, two sacrificial layers, a third sacrificial layer 57 that can be removed in the same process as the first sacrificial layer 51 removing process, and a fourth sacrificial layer 58 that is not removed in the removing process of the third sacrificial layer 57 are provided. It is formed so as to be higher than the upper surface of the outer wall portion 48. The third sacrificial layer 57 is formed from inside the outer wall portion 48 to a part of the outer side of the outer wall portion 48, and the fourth sacrificial layer 58 is formed outside the third sacrificial layer 57, patterned, and patterned. The second sacrificial layer 54 of the first embodiment is formed in substantially the same shape. A pair of openings 53 </ b> A and 53 </ b> B are formed in the sacrificial layer positioned outside the outer wall portion 48 so that the substrate 42 faces the outer wall portion 48. The third and fourth sacrificial layers 57 and 58 are formed under the same conditions as the second sacrificial layer 54 of the first embodiment described above.
In this example, the fourth sacrificial layer 58 is formed outside the outer wall portion 48, and in the third sacrificial layer 47 is formed on all remaining portions. The first sacrificial layer 51 and the third sacrificial layer 57 are formed of the same material or a material that can be removed by the same etching.
Next, an upper film 49 having a high tensile stress is deposited on the third and fourth sacrificial layers 57 and 58 including the openings 53A and 53B, and the upper film 49 is patterned in a pattern in which the outer wall portion 48 is covered. To do.

  Next, as shown in FIG. 7B, the first and third sacrificial layers 51 and 57 are removed in the same removal step. In this removal step, the fourth sacrificial layer 58 remains without being removed. Due to the presence of the fourth sacrificial layer 58, sealing by the upper film 48 is not performed, and the first and third sacrificial layers 51 and 57 are surely removed. By removing the sacrificial layers 51 and 57, the microelectromechanical element body 46 is formed by the beam 45 facing the lower electrode 43 and the space 44 therebetween.

  Next, as shown in FIG. 8C, the fourth sacrificial layer 58 is removed using a required etching gas. When the fourth sacrificial layer 58 is removed, the upper film 49 having a strong tensile stress is also released simultaneously. For example, when the upper film 49 has a uniaxial stress, the upper film 49 is pulled in both directions by the stress F1.

  Then, as shown in FIG. 8D, the upper film 49 is shifted downward (lowered) by the tensile stress F1 of the upper film 49 itself, and automatically adheres to the upper surface of the outer wall portion 48, and the outer wall A sealed space 55 is formed by the portion 48 and the upper film 49. That is, the target micro electro mechanical element 413 in which the micro electro mechanical element body 46 is sealed in the sealed space 55 is obtained.

According to the third embodiment, after the sacrificial layers 51, 57, and 58 are removed, the upper film 49 is covered with the surrounding wall 48 that surrounds the microelectromechanical element body 46 by its own tensile stress F1. Thus, the micro electro mechanical element 413 having a sealed structure including the micro electro mechanical element body 46 having a hollow structure inside can be realized. A micro-electromechanical element that requires high-sealing packaging or a desirable micro-electromechanical element can be easily realized using a semiconductor process.
Further, the third and fourth sacrificial layers 57 and 58 having different etching characteristics are formed as the sacrificial layers, and the first and second sacrificial layers 57 and 58 are removed stepwise. Compared with the embodiment, the sacrificial layer in the sealed structure can be removed more reliably. Therefore, it is possible to reduce the malfunction of the microelectromechanical element body 46 due to the etching residue of the sacrificial layer, and to improve the yield.

  9 and 10 show a microelectromechanical element according to a fourth embodiment. In this embodiment, when the sacrificial layer is removed, the upper film is not lowered, and thereafter the film characteristics of the upper film are changed to obtain a microelectromechanical element having a sealed structure. The basic structure of this embodiment is the same as the structure of the first embodiment or the second embodiment.

  First, as shown in FIG. 9A, the lower electrode 43, the outer wall portion 48, the first sacrificial layer 51, the openings 53A and 53B, and the beam 45 are formed on the substrate 42, for example, as in FIG. 2A described above. A second sacrificial layer 54 is formed. Next, the upper film 61 that does not have a tensile stress in the film formation state and generates a tensile stress by changing the thermal environment (that is, the temperature atmosphere) is formed in the second sacrificial layer 54, the first sacrificial layer 51, and the opening. 53A and 53B are deposited, and the upper film 61 is patterned in such a pattern that the outer wall portion 48 is covered. As the upper film 61, for example, a silicon nitride film (SiN) having no stress in film formation at a high temperature (for example, 700 ° C.) and having a tensile stress at a low temperature (for example, 300 to 400 ° C.) or room temperature after film formation. Film) or the like. In this example, a material having no tensile stress at a high temperature and having a tensile stress at room temperature is used as the upper film 61.

  Next, as shown in FIG. 9B, the first and second sacrificial layers 51 and 54 are etched away under a high temperature atmosphere. At this time, since the upper film 61 does not have a tensile stress, even if the sacrificial layers 51 and 54 are completely removed, the upper film 49 is not lowered by the stress. By removing the sacrificial layers 51 and 57, the microelectromechanical element body 46 is formed by the beam 45 opposed to the lower electrode 43 with the space 44 interposed therebetween.

  Next, as shown in FIG. 10C, the thermal environment is changed after sacrificial removal. That is, the atmosphere is returned to room temperature. By returning to room temperature, a tensile stress, for example, a uniaxial tensile stress F1 is generated in the upper film 61.

  Then, as shown in FIG. 10D, due to the tensile stress F1 generated in the upper film 61, the upper film 61 is shifted downward (lowered), and is automatically brought into close contact with the upper surface of the outer wall part 48, and the outer wall part. A sealed space 55 is formed by 48 and the upper film 61. That is, the target micro electro mechanical element 414 in which the micro electro mechanical element body 46 is sealed in the sealed space 55 is obtained.

According to the fourth embodiment, after the sacrificial layers 51 and 54 are removed, the upper film is formed on the outer wall 48 surrounding the microelectromechanical element body 46 by the tensile stress F1 generated in the upper film 49 by changing the thermal environment. Thus, the micro electro mechanical element 414 having a sealed structure including the micro electro mechanical element body 46 having a hollow structure inside can be realized. A micro-electromechanical element that requires high-sealing packaging or a desirable micro-electromechanical element can be easily realized using a semiconductor process.
Further, as the upper film, by using the upper film 61 having no tensile stress when the sacrificial layers 51 and 54 are removed and having a tensile stress in a room temperature atmosphere after the sacrificial layer is removed, the first and second embodiments are used. The sacrificial layer in the sealed structure can be reliably removed as compared with the form. Therefore, it is possible to reduce the malfunction of the microelectromechanical element body 46 due to the etching residue of the sacrificial layer, and to improve the yield.

  FIG. 11 shows a microelectromechanical element according to the fifth embodiment. In this embodiment, a microelectromechanical element having a sealed structure is formed by forming a film having a tensile stress and a film having a compressive stress as an upper film, and finally removing the film having a compressive stress. It is what I did. The basic structure according to the fifth embodiment is the same as the structure of the first embodiment or the second embodiment.

  First, as shown in FIG. 11A, for example, the lower electrode 43, the outer wall portion 48, the first sacrificial layer 51, the openings 53A and 53B, and the beam 45 are formed on the substrate 42 as in FIG. 2A described above. A second sacrificial layer 54 is formed. Next, a two-layer film 64 obtained by laminating a film 62 having a strong tensile stress and a film 63 having a strong compressive stress thereon is formed in the second sacrificial layer 54, the first sacrificial layer 51, and the openings 53A and 53B. The two-layer film 64 is patterned in such a pattern that the outer wall portion 48 is covered. The film 62 having a tensile stress becomes an upper film finally used for sealing. As the film 62 having tensile stress, for example, a silicon nitride film (SiN film) can be used. As the film 63 having compressive stress, for example, a titanium nitride film (TiN film) can be used. In this case, both the films 62 and 63 have a tensile stress and a compressive stress that are strong enough to cancel each other's stress.

  Next, as shown in FIG. 11, the first and second sacrificial layers 51 and 54 are removed by etching. At this time, in the film 62 having a tensile stress, the stress in the tensile direction is offset by the stress of the film 63 having a compressive stress, and thus the two-layer film 64 does not fall. By removing the sacrificial layers 51 and 54, the microelectromechanical element main body 46 is formed in the outer wall portion 48 by the lower electrode 43 and the beam 45 facing each other with the space 44 interposed therebetween.

  Next, as shown in FIG. 11C, only the film 63 having compressive stress formed on the upper side of the two-layer film 64 is removed. After this step, the film having the tensile stress, that is, the upper film 62 is released (lowered) when the stress is released, and automatically adheres to the upper surface of the outer wall part 48, and the outer wall part 48 and the upper film A sealed space 55 is formed at 62. That is, the target micro electro mechanical element 415 in which the micro electro mechanical element body 46 is sealed in the sealed space 55 is obtained.

According to the fifth embodiment, after removing the sacrificial layers 51 and 54, the film 63 having compressive stress in the upper layer is removed, and the stress of the film 62 having tensile stress serving as the upper film is released, thereby The upper membrane 61 is covered with an outer wall 48 that surrounds the microelectromechanical element main body 46, and a microelectromechanical element 414 having a sealed structure including the microelectromechanical element main body 46 having a hollow structure inside can be realized. . A micro-electromechanical element that requires high-sealing packaging or a desirable micro-electromechanical element can be easily realized using a semiconductor process.
Furthermore, the sacrificial layer in the sealed structure can be reliably removed as compared with the first and second embodiments. Therefore, it is possible to reduce the malfunction of the microelectromechanical element body 46 due to the etching residue of the sacrificial layer, and to improve the yield.

  FIG. 12 shows a microelectromechanical element according to the sixth embodiment. In the present embodiment, a reflowable material layer is finally formed at a position where it is in close contact with the upper film and is reflowed to obtain a microelectromechanical element having a sealed structure with a high sealing degree. The basic structure according to the sixth embodiment is the same as the structure of the first and second embodiments.

  First, as shown in FIG. 12A, for example, the lower electrode 43, the outer wall portion 48, the first sacrificial layer 51, the openings 53A and 53B, and the beam 45 are formed on the substrate 42 as in FIG. 2A described above. A second sacrificial layer 54 and an upper film 49 are formed. In this example, in particular, a reflow material layer 66 that can be reflowed is formed on the upper surface of the outer wall portion 48. As the reflow material layer 66, for example, a metal film made of chromium (Cr), gold (Au), or the like can be used. The reflow material layer 66 can be formed, for example, in a step before the second sacrificial layer 45 is formed.

  Next, as shown in FIG. 12B, the sacrificial layers 51 and 54 are removed by etching. By removing the sacrificial layer, the stress of the upper film 48 is released, and the upper film 49 is automatically shifted downward (lowered) by the tensile stress F1 of the upper film 48 itself, and is formed on the upper surface of the outer wall 48. Contact on the reflow material layer 66.

  Next, as shown in FIG. 12, a reflow process is performed to reflow the reflow material layer 66 on the outer wall portion 48. By this reflow process, the adhesion between the outer wall portion 48 and the upper film 49 is improved. In this way, the desired micro electro mechanical element 416 in which the micro electro mechanical element body 46 is sealed in the sealed space 55 formed by the outer wall portion 48 and the upper film 49 is obtained.

According to the sixth embodiment, as in the above-described embodiment, after the sacrificial layers 51 and 54 are removed, the stress of the upper film 49 is released, so that the outer wall that surrounds the microelectromechanical element main body 46. The upper membrane 61 is covered with the portion 48, and the micro electro mechanical element 416 having a sealed structure including the micro electro mechanical element body 46 having a hollow structure inside can be realized. A micro-electromechanical element that requires high-sealing packaging or a desirable micro-electromechanical element can be easily realized using a semiconductor process.
Furthermore, in the present embodiment, the reflow material layer 66 is formed between the upper film 49 and the outer wall portion 48, thereby improving the confidentiality in the sealed structure as compared with the first and second embodiments. Can do. Therefore, defects due to insufficient sealing performance can be reduced and yield can be improved.

  FIG. 13 shows a microelectromechanical element according to the seventh embodiment. In the present embodiment, after the stress of the upper film is released, another film is newly formed to obtain a microelectromechanical element having a highly sealed structure. The basic structure of the present embodiment is the same as that of the first embodiment.

  First, as shown in FIG. 13A, the steps up to the step of removing the sacrificial layers 51 and 54 shown in FIG. 3D are performed. The stress of the upper film 49 is released, the upper film 49 is lowered by its own tensile stress, and the upper film 49 is in close contact with the upper surface of the outer wall portion 48.

Next, as shown in FIGS. 13B and 13C, a required coating film 67 is formed so as to extend from the upper surface of the upper film 49 to the side surface of the upper film 49 and further from the step 68 to the side surface of the outer wall portion 48. The covering film 67 is desirably a film sufficiently formed in the step 68, and can be formed of, for example, a SiN film, a SiO ₂ film, or the like by a CVD method. By this coating film 67, the close contact portion is completely sealed. In this way, the desired micro electro mechanical element 417 in which the micro electro mechanical element body 46 is sealed in the sealed space 55 formed by the outer wall portion 48 and the upper film 49 is obtained.

According to the seventh embodiment, as in the above-described embodiment, the outer wall surrounding the microelectromechanical element body 46 is released by releasing the stress of the upper film 49 after removing the sacrificial layers 51 and 54. The upper membrane 61 is covered with the portion 48, and the microelectromechanical element 417 having a sealed structure including the hollow microelectromechanical element body 46 therein can be realized. A micro-electromechanical element that requires high-sealing packaging or a desirable micro-electromechanical element can be easily realized using a semiconductor process.
Furthermore, in this embodiment, by forming the coating film 67 from the upper surface of the upper film 49 to the side surface of the outer wall portion 48, the confidentiality in the sealed structure is improved as compared with the first and second embodiments. Can be improved. Therefore, defects due to insufficient sealing performance can be reduced and yield can be improved.

FIG. 14 shows a microstructure according to a reference example . The present embodiment is a microstructure having a plurality of sealed spaces. The basic structure of the sealed structure of this reference example is the same as the structure of the first and second embodiments.
In this reference example , as shown in FIG. 14A, a plurality of side wall portions 73 and an outermost wall portion 79 that partition a minute space are formed on a substrate 72. A first sacrificial layer 51 having a height H2 lower than the height H1 of the side wall portion 73 is formed on the substrate 72, and a second sacrificial layer 75 having a height H3 from the surface of the substrate 72 higher than the side wall portion 73 is formed. Is formed so as to cover the plurality of side wall portions 73 and the outermost wall portion 79. For example, a pair of openings 76A and 76B facing the surface of the substrate 72 are formed outside the first sacrificial layer 74. Next, an upper film 77 having a strong tensile stress is formed so as to reach the openings 76A and 76B from the upper surface of the second sacrificial layer 75.

  Next, as shown in FIG. 14B, the first and second sacrificial layers 74 and 75 are removed by etching. By removing the sacrificial layers 74 and 75, the stress of the upper film 77 is released, and the upper film 77 is lowered by its own tensile stress, and is in close contact with the upper surfaces of the adjacent side wall 73 and outermost wall 79. Each micro space 78 is sealed. That is, a plurality of independent sealed spaces 78 are formed. In this manner, the space between the side wall portion 73 and the outermost wall portion 79 is sealed with the upper film 77, and the microstructure 71 having a plurality of sealed spaces 78 that are divided independently is obtained.

The outermost wall 79 may be formed in a structure surrounding the same periphery as the outer wall 48 shown in FIG. 5 or may be formed in a structure extending in one direction.
When the outermost wall 79 is structured to surround the periphery, each minute space 78 whose upper portion is sealed with the upper film 77 becomes a completely sealed space. In this case, the micro structure 71 is configured as a micro electro mechanical element by incorporating the above-described micro electro mechanical element body 46 in each micro space 78 as indicated by a chain line.
When the outermost wall portion 79 has a structure extending to one side, a sealed space is opened in one direction. In this case, for example, it can be configured as a microstructure having a sealed space that does not have a movable structure inside, such as a flow path.

  In this micro structure 71, when the micro space 78 is used as a space having no movable structure in the micro space 78, the sacrificial layer is divided into first and second sacrificial layers 74 and 75 as shown in FIG. There is no need to form it, and a single sacrificial layer may be used. That is, a minute structure having a sealed structure is formed by the steps of forming the side wall portion 73 and the outermost wall portion 79, then forming the sacrificial layer, then planarizing the upper surface of the sacrificial layer, then forming the upper film 7, and then removing the sacrificial layer. A structure can be manufactured.

According to this reference example , a plurality of sealed spaces 78 can be formed simultaneously. In addition, since the close contact portion between the upper film 77, the side wall portion 73, and the outermost wall portion 79 is increased, it is desirable to use the sixth embodiment shown in FIG.

  In FIG. 14, a microstructure having a plurality of sealed spaces 78 is configured. However, the microstructure can also be configured as a microstructure having one sealed space 78.

In each of the embodiments, the microelectromechanical element main body 46 is a beam having a cantilever structure (see FIG. 20 ), but a beam having a both-cantilever structure (see FIG. 21 ). Can be applied.

As described above, according to the embodiment of the present invention, the upper film having a strong tensile stress is formed on the upper surface of the sacrificial layer, and the sealed space is automatically formed by the own tensile stress after the sacrificial layer is removed . it is possible to realize a fine small electromechanical device. This requires a high degree of sealing packaging or in infinitesimal electromechanical device not desirable, which can be easily manufactured by using a semiconductor process.
The problem of the degree of sealing, which has been a concern with the conventional sealing structure, can also be solved by using the third to seventh embodiments.
When it is necessary to form a large number of sealed spaces at the same time, this can be easily realized by using the eighth embodiment.

Infinitesimal electromechanical device of the present invention, for example a high frequency filter, an intermediate frequency filter, filters and the like frequency filter according to acoustic resonance, the ink jet printer head and comprising a printer, a gyro sensor, an infrared sensor, a pressure sensor, an acceleration sensor, an angular velocity sensor It can be applied to various sensors such as. Also, the microelectromechanical element beam can be used as a light reflecting film, and can be applied to an optical microelectromechanical element such as an optical switch utilizing the light reflection direction or a GLV (registered trademark) element utilizing diffracted light. Is possible. At this time, the upper film is formed of a light transmissive film.

The present invention can be configured to various electronic devices having a fine small electromechanical device that is applied to each above-described device.

  The ink jet printer head uses a micro electromechanical element as an actuator (driving source), an ink chamber having a nozzle is disposed thereon, and has an ink flow path leading to the ink chamber and an ink supply unit. In such an ink jet printer head, the present invention can be applied to at least the formation of the ink flow path.

FIGS. 15 and 16 are embodiments applied to filters such as a high frequency filter and an intermediate frequency filter, respectively. Each figure is a schematic diagram.
In the filter 81 shown in FIG. 15, an input electrode 83 and an output electrode 84 constituted by lower electrodes are formed on a substrate 82, and a beam (vibration electrode) having a required resonance frequency with a space 85 interposed between the input / output electrodes 83 and 84. ) 86 is formed to constitute the filter body 87. Further, an outer wall 88 having the same configuration as described above and an upper film 89 in close contact with the upper surface of the outer wall 88 are formed on the substrate 82 so as to seal the filter main body 87.

  In the filter 81, a signal is input to the input electrode 83, and a DC bias voltage is applied to the beam 89. When a signal having a target frequency is input to the input electrode 83, the beam 89 resonates with an electrostatic force generated between the beam 89 and the input electrode 83, and a signal having a target frequency is output from the output electrode 84. When a signal of another frequency is input, the beam 89 does not resonate and no signal is output from the output electrode 84.

  In the filter 91 shown in FIG. 16, an output electrode 92 serving as a lower electrode and a wiring layer 93 are formed on a substrate 82, and a beam 95 serving as a vibrating electrode having a required resonance frequency is formed between the output electrode 92 with a space 94 interposed therebetween. A filter body 96 is configured. Further, an outer wall 88 having the same configuration as described above and an upper film 89 in close contact with the upper surface of the outer wall 88 are formed on the substrate 82 so as to seal the filter body 96.

  The filter 91 is an electrostatic force generated between the beam 95 and the output electrode 92 when a signal having a target frequency is input to the beam 95 with a DC bias voltage applied between the beam 95 and the ground. Resonance occurs, and a signal having a target frequency is output from the output electrode 92. When a signal of another frequency is input, the beam 95 does not resonate and no signal is output from the output electrode 92.

  The present invention provides a communication device provided with the filter 81 or 91 of the above-described embodiment, such as a mobile phone, a wireless LAN, a wireless transceiver, a TV tuner, a radio tuner, or the like that communicates using electromagnetic waves. I can do this.

Next, a configuration example of a communication apparatus to which the above-described filter according to the embodiment of the present invention is applied will be described with reference to FIG.
First, the configuration of the transmission system will be described. I-channel transmission data and Q-channel transmission data are supplied to digital / analog converters (DACs) 201I and 201Q, respectively, and converted into analog signals. The converted signal of each channel is supplied to band pass filters 202I and 202Q to remove signal components other than the band of the transmission signal, and the outputs of the band pass filters 202I and 202Q are supplied to the modulator 210. Supply.

  The modulator 210 supplies the frequency signals corresponding to the transmission frequency supplied from the PLL (phase-locked loop) circuit 203 for transmission to the mixers 212I and 212Q via the buffer amplifiers 211I and 211Q for each channel. The signals are mixed and modulated, and both mixed signals are added by an adder 214 to form a single transmission signal. In this case, the signal phase of the frequency signal supplied to the mixer 212I is shifted by 90 ° by the phase shifter 213 so that the I channel signal and the Q channel signal are orthogonally modulated.

  The output of the adder 214 is supplied to the power amplifier 204 via the buffer amplifier 215 and amplified so as to have a predetermined transmission power. The signal amplified by the power amplifier 204 is supplied to the antenna 207 via the transmission / reception switch 205 and the high frequency filter 206, and is wirelessly transmitted from the antenna 207. The high frequency filter 206 is a band pass filter that removes signal components other than the frequency band transmitted and received by the communication apparatus.

  As a configuration of the reception system, a signal received by the antenna 207 is supplied to the high frequency unit 220 via the high frequency filter 206 and the transmission / reception switch 205. In the high frequency unit 220, the received signal is amplified by a low noise amplifier (LNA) 221 and then supplied to the band pass filter 222 to remove signal components other than the received frequency band, and the removed signal is buffer amplifier 223. To the mixer 224. Then, the frequency signals supplied from the channel selection PLL circuit 251 are mixed, a signal of a predetermined transmission channel is used as an intermediate frequency signal, and the intermediate frequency signal is supplied to the intermediate frequency circuit 230 via the buffer amplifier 225.

  The intermediate frequency circuit 230 supplies the supplied intermediate frequency signal to the band-pass filter 232 via the buffer amplifier 225, removes signal components other than the band of the intermediate frequency signal, and automatically removes the removed signal. The signal is supplied to an adjustment circuit (AGC circuit) 233 to obtain a signal with a substantially constant gain. The intermediate frequency signal whose gain has been adjusted by the automatic gain adjustment circuit 233 is supplied to the demodulator 240 via the buffer amplifier 234.

  The demodulator 240 supplies the supplied intermediate frequency signal to the mixers 242I and 242Q via the buffer amplifier 241, mixes the frequency signal supplied from the intermediate frequency PLL circuit 252 and receives the received I channel signal. The component and the Q channel signal component are demodulated. In this case, the I-signal mixer 242I is supplied with a frequency signal whose signal phase is shifted by 90 ° by the phase shifter 243, and the quadrature-modulated I-channel signal component and Q-channel signal component. Is demodulated.

  The demodulated I channel and Q channel signals are supplied to band pass filters 253I and 253Q via buffer amplifiers 244I and 244Q, respectively, to remove and remove signal components other than I channel and Q channel signals. The obtained signals are supplied to analog / digital converters (ADC) 254I and 254Q, sampled and converted into digital data, and I-channel received data and Q-channel received data are obtained.

  In the configuration described so far, it is possible to limit the band by applying the filter of the configuration of this example as a part or all of each band-pass filter 202I, 202Q, 206, 222, 232, 253I, 253Q. is there. In the example of FIG. 17, each filter is configured as a band-pass filter. However, a low-pass filter that passes only a frequency band lower than a predetermined frequency, or a frequency band that is higher than a predetermined frequency is used. It is also possible to configure as a high-pass filter that passes, and apply the filter of the configuration of this example to these filters. In the example of FIG. 17, the communication device performs wireless transmission and reception. However, the communication device may be applied to a filter included in the communication device that performs transmission and reception via a wired transmission path, and only transmission processing is performed. The filter having the configuration of the above-described embodiment may be applied to a filter included in a communication device that performs or a communication device that performs only reception processing.

It is a block diagram which shows embodiment of the micro electro mechanical element which concerns on this invention. FIGS. 1A to 1C are manufacturing process diagrams (part 1) for a micro electro mechanical device according to a first embodiment; FIGS. FIGS. D to E are manufacturing process diagrams (part 2) of the micro electro mechanical device according to the first embodiment. FIGS. A and B are perspective views of an upper film for explaining the present invention. It is a schematic diagram of the micro electromechanical element which concerns on 1st Embodiment. It is a schematic diagram of the micro electro mechanical element which concerns on 2nd Embodiment. FIGS. 9A to 9B are manufacturing process diagrams (part 1) for a micro electro mechanical device according to a third embodiment. FIGS. C to D are manufacturing process diagrams (part 2) of the microelectromechanical device according to the third embodiment. FIGS. 9A to 9B are manufacturing process diagrams (part 1) for a micro electro mechanical device according to a fourth embodiment. FIGS. C to D are manufacturing process diagrams (part 2) of the microelectromechanical device according to the fourth embodiment. AC is a manufacturing process diagram of the microelectromechanical element according to the fifth embodiment. AC is a manufacturing process diagram of the microelectromechanical element according to the sixth embodiment. FIGS. 9A to 9B are manufacturing process diagrams of a micro electro mechanical device according to a seventh embodiment. FIGS. C is a cross-sectional view taken along the line AA in FIG. 13B. It is a manufacturing-process figure of the microstructure which concerns on AB reference example . It is a lineblock diagram showing one embodiment of a filter concerning the present invention. It is a block diagram which shows other embodiment of the filter which concerns on this invention. It is a circuit diagram which shows embodiment of the communication apparatus which concerns on this invention. It is a block diagram which shows an example of the conventional microelectromechanical element of the sealing structure. It is a manufacturing process figure which shows the other example of the micro electromechanical element of the conventional sealed structure AB. A is a perspective view showing a typical example of an electrostatic drive type micro-electromechanical element. B is a cross-sectional view thereof. A is a perspective view showing another typical example of an electrostatic drive type micro electromechanical element. FIG. B is a cross-sectional view thereof.

  41 [411 to 417]... Micro electromechanical element, 42... Substrate, 43.. Lower electrode, 44 .. space, 45. 49 .. Upper membrane, 49 [49A to 49D] ... Upper membrane support, 49E ... Central region of upper membrane, 51, 54, 57, 58 ... Sacrificial layer, 55 ... Sealed space, ... Reflow material layer, 71 .. Micro structure, 72 .. Substrate, 73 .. Side wall portion, 74, 75 .. Sacrificial layer, 77 .. Upper film, 78 .. Micro space, 79 .. Outermost wall portion

Claims (16)

An electrostatically driven micro-electromechanical element body formed on a substrate and comprising a lower electrode and a beam opposed to the lower electrode across a space;
An outer wall formed on the substrate, surrounding the microelectromechanical element body, and higher than the microelectromechanical element body;
The sacrificial layer supported on the outside of the surrounding wall portion on the substrate and removed from the sacrificial layer formed in the manufacturing process is then lowered by the tensile stress of the film itself and is in close contact with the upper surface of the surrounding wall portion. An upper film that hermetically seals the space surrounded by the part,
A microelectromechanical element in which the microelectromechanical element body is sealed in a sealed space formed by the upper film and the outer wall portion . The microelectromechanical element according to claim 1, wherein the upper film is formed of a film having a tensile stress in a uniaxial direction, and is supported by the substrate at both ends in the uniaxial direction . The microelectromechanical element according to claim 1, wherein the upper film is formed of a film having a tensile stress in the biaxial direction, and is supported on the substrate at four ends in the biaxial direction . The microelectromechanical element according to claim 2 , wherein a reflow material layer is interposed between the upper film and the upper surface of the outer wall portion. 4. The microelectromechanical element according to claim 2, wherein the upper film is formed of a film having a tensile stress in a room temperature atmosphere . The microelectromechanical element according to claim 2, further comprising a coating film formed in a direction orthogonal to the one axial direction so as to cover a region from the upper surface of the upper film to the side surface of the full width of the outer wall portion . On the substrate, a lower electrode that will later become an electrostatically driven micro-electromechanical element body and a beam facing the lower electrode with a sacrificial layer interposed therebetween are formed, surrounding the micro-electromechanical element body, and Forming a surrounding wall portion higher than the microelectromechanical element body;
Forming a sacrificial layer so as to cover the outer wall part including the inside and outside of the outer wall part ;
Forming an upper film having a tensile stress supported on the surface of the substrate including the upper surface of the sacrificial layer covering the outer wall and reaching the outer surface of the outer wall ;
Removing each of the sacrificial layers , lowering the upper film downward by the tensile stress of the upper film, and bringing the upper film into close contact with the upper surface of the outer wall part to hermetically seal the space surrounded by the outer wall part ; Have
A method of manufacturing a microelectromechanical element, wherein the microelectromechanical element body is sealed in a sealed space formed by the upper film and the outer wall portion . There use a film having a uniaxial direction tensile stress in the upper layer,
The method of manufacturing a micro electro mechanical element according to claim 7, wherein the upper film is supported on the substrate surface at both ends in the uniaxial direction . There use a film having a two-axis direction of the tensile stress in the upper layer,
The method of manufacturing a microelectromechanical element according to claim 7, wherein the upper film is supported on the surface of the substrate by four ends in the biaxial direction . Forming a sacrificial layer covering the outer wall portion with a first sacrificial layer and a second sacrificial layer having different etching characteristics;
Forming the first sacrificial layer in the outer wall having the same etching characteristics as the sacrificial layer between the lower electrode and the beam;
Forming the second sacrificial layer outside the outer wall,
After the sacrificial layer between the first sacrificial layer and the lower electrode and the beam is etched away, the second sacrificial layer is etched away, and the upper film is moved downward by the tensile stress of the upper film. The method for manufacturing a microelectromechanical element according to claim 8 or 9 , wherein the microelectromechanical element is lowered and brought into close contact with the upper surface of the outer wall portion . The upper film is formed of a film having a tensile stress in a room temperature atmosphere,
The sacrificial layer is removed in a temperature atmosphere higher than room temperature, and the upper film is not lowered downward in the state where the sacrificial layer is removed,
10. The microelectric device according to claim 8 , wherein after the sacrificial layer is removed, a tensile stress is generated in the upper film in a room temperature atmosphere, and the upper film is lowered to be in close contact with the upper surface of the outer wall portion. A method for manufacturing a mechanical element. The upper film is formed of a two-layer film of a film having a compressive stress and a film having a tensile stress,
After the formation of the sacrificial layer, the upper layer of the upper film is removed from the film having compressive stress to release the stress of the upper film only of the film having the tensile stress,
The method of manufacturing a microelectromechanical element according to claim 8 or 9, wherein an upper film including only the film having a tensile stress is lowered to be in close contact with the upper surface of the outer wall portion. Before formation of the sacrificial layer, forming a reflow material layer on the upper surface of the outer periphery wall section,
10. The method according to claim 8 , further comprising a step of removing the sacrificial layer , lowering the upper film downward and bringing the upper film into contact with a reflow material layer on an upper surface of the outer wall portion, and then reflowing the reflow material layer. A method for manufacturing a microelectromechanical element. After the step of bringing the upper film into close contact with the upper surface of the outer wall portion, a coating film covering the region from the upper surface of the upper film to the side surface of the full width of the outer wall portion is formed in a direction orthogonal to the one axial direction. The method for producing a micro electro mechanical element according to claim 8 , further comprising a step. An electronic apparatus comprising the microelectromechanical element according to claim 1 . A filter for limiting the bandwidth of the transmission signal and / or the reception signal;
As said filter, the filter by the micro electro mechanical element in any one of Claims 1 thru | or 6 is used,
16. The electronic device according to claim 15 , configured as a communication device .

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