JP2018130769A - Electronic device and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electronic device which houses an MEMS element including a hermetic seal having high airtightness.SOLUTION: In an electronic device, an element part is housed in a housing space formed by a first major surface of an element substrate and a lid part joined to the first major surface. The electronic device has: a recessed part including an opening on the second major surface side opposite to the first major surface of the element substrate; and a membrane part formed by a bottom part of the recessed part and the first major surface. The membrane part includes a sealing hole on the first major surface side. A first major surface side first surface of the membrane part includes a first metal film or a first metal oxide film. A part of the first metal film or the first metal oxide film extends to the first major surface located at the outer side of the first surface.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electronic device and a method for manufacturing the electronic device.

  2. Description of the Related Art In recent years, electronic devices that are integrated in a small size by micromachining of MEMS (Micro Electro Mechanical Systems) are known. In order to accurately operate an element formed by MEMS, for example, a vibrator, a sensor, or an actuator, the element is accommodated in a so-called hermetically sealed space in which the element is accommodated in a cavity maintained in a predetermined environment. (Patent Document 1).

JP 2008-114354 A

  In the electronic device disclosed in Patent Document 1, as a means for hermetically sealing the cavity, the electronic apparatus includes a first coating layer having a through hole facing the cavity, and the second coating layer in a reduced pressure state, for example, by a CVD method. By forming so as to cover the first covering layer, the functional element is hermetically sealed with the cavity portion in a reduced pressure state.

  However, in the electronic device disclosed in Patent Document 1, it is necessary to form a plurality of coating layers of at least a first coating layer and a second coating layer on a substrate on which a functional element is formed, Furthermore, when the second coating layer is used as a part of the wiring layer, a predetermined electrical insulating layer or the like must be formed. Therefore, many production steps have to be performed by forming many coating layers.

  Therefore, in order to improve the process efficiency, a method of housing an electronic component by bonding a lid to a case often used for forming an electronic component package (accommodating container) is also applied to a MEMS element, while being highly airtight. There is a need to obtain an electronic device with a hermetic seal that can comprise:

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 In the electronic device of this application example, the element portion is housed in a housing space formed by the first main surface of the element substrate and a lid portion bonded to the first main surface. An electronic device comprising: a concave portion having an opening on a second main surface side opposite to the first main surface of the element substrate; a bottom portion of the concave portion and the first main surface. A membrane portion, wherein the membrane portion includes a sealing hole on the first main surface side, and the first surface on the first main surface side of the membrane portion is a first metal. A film or a first metal oxide film, and a part of the first metal film or the first metal oxide film extends to the first main surface outside the first surface. It is characterized by that.

  In the electronic device of this application example, the sealing hole for hermetically sealing the accommodation space in which the element portion is accommodated has a first main surface of the element substrate and a second main surface opposite to the first main surface. It is formed in the membrane part which is a thin part formed by the bottom part of the recessed part formed toward the 1st main surface from the surface.

  Here, the membrane is a name generally used to indicate an object that is as thin as the thickness corresponding to the area.

  The housing space in which the element portion is housed is preferably maintained in a state in which gas molecules that hinder the movement of the element portion, for example, vibration and peristalsis, are removed, that is, in a vacuum state, and is accommodated through a sealing hole. After the gas is extracted from the space, so-called hermetic sealing is performed to close the sealing hole. As a result, the membrane portion is loaded with a differential force between the vacuum state of the housing space and the external environment of the electronic device, for example, under atmospheric pressure, and the membrane portion is deformed to bend toward the housing space where the pressure is low. Occur.

  According to the electronic device of this application example, the first metal film or the first metal oxide film is provided on the first main surface side of the membrane portion against the bending deformation, so that the first metal film or The first metal oxide film serves as a reinforcing part against the bending deformation of the membrane part, and is caused by the bending deformation of the membrane part due to the difference in pressure between the vacuum state of the housing space and the external environment of the electronic device, for example, under atmospheric pressure. Thus, an electronic device having a long-term stable performance can be obtained.

  Application Example 2 In the application example described above, the first metal film or the first metal oxide film extends to the first main surface outside the first surface. And

  The maximum stress due to the bending deformation of the membrane portion due to the difference in pressure between the vacuum state of the housing space and the external environment of the electronic device, for example, under atmospheric pressure, is the outer edge of the membrane portion, that is, the first surface and the first surface. Occurs at the boundary between the main surface.

  Therefore, according to the application example described above, the first metal film or the first metal oxide film extends to the first main surface outside the first surface, so that the maximum stress generating portion, that is, the bending is generated. It is possible to reinforce an area where damage due to deformation is most likely to occur.

  Application Example 3 In the application example described above, a sealing member that covers the sealing hole of the membrane portion is disposed at the bottom of the concave portion.

  The bending deformation of the membrane portion toward the accommodation space due to the difference in pressure between the vacuum state of the accommodation space and the external environment of the electronic device, for example, under atmospheric pressure, acts in the direction of expanding the sealing hole. Damage to the surface due to internal stress is likely to occur.

  According to the application example described above, the sealing member acts to counter the expansion of the sealing hole, can prevent damage due to internal stress on the surface of the sealing hole, and maintain high airtightness. it can.

  Application Example 4 In the application example described above, the sealing member is a second metal film or a second metal oxide film.

  According to the above application example, by using a metal or metal oxide film having excellent ductility for the sealing member, the sealing member made of the metal or the metal oxide film is damaged with respect to the expansion of the sealing hole. It can be stretched and high airtightness can be maintained.

  Application Example 5 In the application example described above, the second metal film extends from the conductive film.

  According to the above application example, the sealing member can be disposed simultaneously with the formation of the conductive film formed on the second main surface, and high productivity can be obtained.

  Application Example 6 An electronic device manufacturing method according to this application example includes a substrate preparation step of preparing an SOI substrate on which an element portion is formed, and a first main side on the side on which the element portion of the SOI substrate is formed. A first film forming step of forming a first metal film or a first metal oxide film on at least a part of the surface, and a first region in the region where the first metal film or the first metal oxide film is formed. A first concave portion forming step for forming a concave portion, a lid portion joining step for joining a lid portion constituting an accommodation space for the element portion to the first main surface, and the first main surface of the SOI substrate. The second concave portion forming the membrane portion provided with the sealing hole is formed by removing the bottom of the first concave portion from the second main surface side opposite to the first main surface and using the first concave portion as a sealing hole. 2 in which the recess is formed and the housing space is a predetermined space environment, and the sealing hole is hermetically sealed. Characterized in that it comprises a step.

  In the electronic device of this application example, the sealing hole for hermetically sealing the accommodation space in which the element portion is accommodated has a first main surface of the element substrate and a second main surface opposite to the first main surface. This is a method of forming a membrane portion which is a thin portion formed by a bottom portion of a concave portion formed from the surface toward the first main surface.

  The housing space in which the element portion is housed is preferably maintained in a state in which gas molecules that obstruct the movement of the element portion, for example, vibration and peristalsis, are removed, that is, in a vacuum state. After the gas is extracted from the space, so-called hermetic sealing is performed to close the sealing hole. Therefore, the membrane portion is loaded with a differential force between the vacuum state of the housing space and the external environment of the electronic device, for example, under atmospheric pressure. As a result, the membrane portion is bent and deformed so as to be pushed toward the accommodating space where the pressure is small.

  According to the manufacturing method of the electronic device of this application example, the first metal film or the first metal oxide film is provided on the first main surface side of the membrane portion with respect to the bending deformation. The metal film or the first metal oxide film serves as a reinforcing part against the bending deformation of the membrane part, and the membrane part is damaged due to the difference in pressure between the vacuum state of the housing space and the external environment of the electronic device, for example, under atmospheric pressure. Thus, an electronic device having stable performance over a long period of time can be obtained.

  Application Example 7 In the application example described above, the sealing step includes a conductive film forming step of forming a conductive film on the second main surface side.

  According to the above application example, the sealing member can be disposed simultaneously with the formation of the conductive film formed on the second main surface, and high productivity can be obtained.

FIG. 2 is a plan external view of the electronic device according to the first embodiment excluding a lid. Sectional drawing of the AA 'part cross section shown in FIG. The external view which shows one form of the film-forming form of the metal film by the partial expanded view of the C section shown in FIG. The external view which shows one form of the film-forming form of the metal film by the partial expanded view of the C section shown in FIG. The external view which shows one form of the film-forming form of the metal film by the partial expanded view of the C section shown in FIG. The partial expanded sectional view explaining the effect | action of a metal film. The partial expanded sectional view explaining the effect | action of a metal film. The fragmentary sectional view which shows the electronic device which concerns on 2nd Embodiment. The fragmentary sectional view which shows the modification of the electronic device which concerns on 1st Embodiment. 9 is a flowchart showing a method for manufacturing an electronic device according to a third embodiment. Sectional drawing which shows the manufacturing process of the electronic device which concerns on 3rd Embodiment. Sectional drawing which shows the manufacturing process of the electronic device which concerns on 3rd Embodiment. Sectional drawing which shows the manufacturing process of the electronic device which concerns on 3rd Embodiment. Sectional drawing which shows the manufacturing process of the electronic device which concerns on 3rd Embodiment. Sectional drawing which shows the manufacturing process of the electronic device which concerns on 3rd Embodiment. Sectional drawing which shows the manufacturing process of the electronic device which concerns on 3rd Embodiment. 10 is a flowchart showing a method for manufacturing an electronic device according to a fourth embodiment. Sectional drawing which shows the manufacturing process of the electronic device which concerns on 4th Embodiment. Sectional drawing which shows the manufacturing process of the electronic device which concerns on 4th Embodiment.

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

(First embodiment)
An electronic device according to the first embodiment is shown in FIGS. FIG. 1 is a plan external view of the electronic device 100 according to this embodiment in which the lid 20 is omitted, and FIG. 2 is a cross-sectional view taken along the line AA ′ shown in FIG.

  As shown in FIG. 2, the electronic device 100 according to the first embodiment is a so-called SOI (Silicon on Insulator) substrate in which a silicon oxide layer is inserted between a silicon substrate layer of single crystal silicon and a silicon layer, or An element substrate 10 formed as a substrate material M (not shown) as a semiconductor substrate such as a silicon substrate mainly composed of single crystal silicon; a lid portion 20 bonded to the first main surface 10a of the element substrate 10; It has.

  The lid 20 has a lid cavity 20 a on the side facing the first main surface 10 a of the element substrate 10, and is joined to the element substrate 10, thereby being part of the internal space S (hereinafter referred to as cavity S). Parts. The material of the lid 20 is not particularly limited, but glass is preferably used.

The element substrate 10 includes an element formation layer 11 in which a silicon oxide (SiO ₂ ) layer and a silicon (Si) layer of an SOI substrate are stacked, and a base 12 of the silicon (Si) layer. The element substrate 10 is formed with an element portion 11a formed by a so-called MEMS (Micro Electro Mechanical System). A base cavity 12a is formed in a base portion 12 of a formation region of the element portion 11a. The lid part cavity 20a of the part 20 constitutes a cavity S as an accommodation space for the element part 11a.

  A through hole 11 c having an opening toward the cavity S is formed in at least one portion of the outer portion 11 b of the element forming layer 11. As shown in FIG. 1, the through-hole 11c is a through-hole having a rectangular planar shape in this example, and is formed at one location. The through-hole 11c is provided as a so-called sealing hole that hermetically seals a cavity S described later. Therefore, hereinafter, the through hole 11c is referred to as a sealing hole 11c. In the electronic device 100 according to the present embodiment, one sealing hole 11c is illustrated as an example, but the present invention is not limited thereto, and a plurality of sealing holes 11c may be formed.

  The base 12 at the position where the sealing hole 11c is formed is located on the first main surface 10a side of the element formation layer 11 from the second main surface 10b opposite to the first main surface 10a of the element substrate 10. A recess 12b having an opening is formed on the second main surface 10b side that reaches the second surface 11d opposite to the first surface 11d. That is, the second surface 11d becomes the bottom of the recess 12b.

  In the first main surface 10a, as shown in the partial perspective view B of the sealing hole 11c portion shown in FIG. 2, the region of the concave portion 12b overlapping with the concave portion planar shape P in a plan view (in the arrow direction from the Z-axis direction) In other words, the first surface 11e opposite to the second surface 11d of the element forming layer 11 is formed. A part of the element forming layer 11 constituted by the first surface 11e and the second surface 11d in the arrangement region of the recess 12b formed in the base 12 is formed as the thin portion 11f. The thin-walled portion 11f is so-called that the thickness of the element forming layer 11 is very small relative to the size of the concave planar shape P that becomes the outer edge of the thin-walled portion 11f, that is, the area of the first surface 11e and the second surface 11d It is a membrane part. In the following description, the thin portion 11f is referred to as a membrane portion 11f.

  On the first surface 11e of the membrane part 11f, a metal film 30 as a first metal film or a first metal oxide film is formed except at least a part where the sealing hole 11c is formed. The material of the metal film 30 is not particularly limited, but excellent in ductility, for example, copper (Cu), gold (Au), aluminum (Al), or the like is preferably used. A metal oxide film may also be used. Alternatively, a metal film and a metal oxide film may be laminated.

  FIG. 3 to FIG. 5 which are partial enlarged views of the part C shown in FIG. The metal film 30 shown in FIG. 3 is the form illustrated in the electronic device 100 according to the present embodiment shown in FIG. 1, and the inner peripheral portion 30a in the first surface 11e of the membrane portion 11f outside the sealing hole 11c. The outer peripheral portion 30b is disposed so as to extend beyond the outer edge of the membrane portion 11f, that is, beyond the concave plane shape P of the concave portion 12b to reach the first main surface 10a.

  In the form of the metal film 30A shown in FIG. 4, the inner peripheral portion 30Aa is disposed in the first surface 11e of the membrane portion 11f outside the sealing hole 11c, and a part of the outer peripheral portion 30Ab is the outer edge of the membrane portion 11f. That is, it extends beyond the concave plane shape P of the concave portion 12b. In addition, the metal film 30B illustrated in FIG. 5 illustrates a circular donut shape, whereas the metal film 30A illustrated in FIG. 4 illustrates a rectangular frame shape. In the form of the metal film 30B, the inner peripheral part 30Ba is arranged in the first surface 11e of the membrane part 11f outside the sealing hole 11c, and a part of the outer peripheral part 30Bb is the outer edge of the membrane part 11f, that is, the recess 12b. It extends beyond the concave plane shape P.

  As illustrated in the metal films 30, 30A, and 30B shown in FIGS. 3 to 5 described above, the metal film 30 includes a first surface 11e and a first main surface 10a that is continuous with the first surface 11e. It is preferable that at least a part is formed straddling. In particular, as shown in FIG. 3, the first surface 11e and the first main surface 10a connected to the first surface 11e are formed over the entire region of the recess planar shape P. More preferred.

  As shown in FIG. 2, the sealing hole 11c provided in the membrane part 11f is formed as a second metal film or a second metal oxide film so as to cover the sealing hole 11c on the second surface 11d of the membrane part 11f. A sealing member 40 is formed. The sealing member 40 is formed by depositing a metal or metal oxide by sputtering or CVD. By forming the sealing member 40 as the second metal film or the second metal oxide film by the CVD method, the sealing member 40 is formed under the specification environment of the cavity S, for example, in a vacuum environment of 10 Pa or less. The sealing hole 11c is closed on the second surface 11d side. Thereby, the electronic device 100 in which the element portion 11a is accommodated in the hermetically sealed cavity S is obtained. The sealing member 40 is not limited to a metal film or a metal oxide film. For example, an inorganic material such as synthetic resin or glass may be used, but it is preferable to apply a material excellent in ductility.

  6 and 7 are enlarged schematic cross-sectional views of the membrane portion 11f of the AA ′ portion shown in FIG. 1 for explaining the operation of the metal film 30 described above. FIG. 6 shows a pressure state applied to the membrane part 11f. As shown in FIG. 6, the first surface 11e of the membrane portion 11f is loaded with the internal pressure ρs of the cavity S, and the pressure in the environment where the electronic device 100 is disposed on the second surface 11d, For example, in the case of indoor installation equipment, an external pressure ρr corresponding to atmospheric pressure is applied.

As described above, since the inside of the cavity S is maintained in a vacuum state,
ρr> ρs
This relationship is normally applied to the membrane part 11f. In other words, as shown in FIG. 7, the membrane portion 11f is loaded with a differential pressure (ρr−ρs) as an external pressure.

  Then, the membrane portion 11f is bent toward the cavity S side as shown in the figure by the differential pressure (ρr−ρs) shown in FIG. 7, and the membrane portion 11f ′ is deformed after being deformed. In the membrane portion 11f ′ after the bending deformation, an internal stress that gradually increases from the sealing hole 11c toward the illustrated arrow portion D corresponding to the concave planar shape P that is the outer edge portion is generated.

  The membrane part 11f is an element formation layer including the silicon oxide layer of the SOI substrate as described above, and the silicon oxide layer is a layer with poor ductility. Therefore, due to the internal stress generated in the membrane portion 11f ′ after the bending deformation, the membrane portion 11f is damaged, particularly at the illustrated arrow portion D corresponding to the concave planar shape P which is the outer edge portion of the membrane portion 11f where the internal stress is the largest. There was a risk of damage.

  Therefore, as shown in FIGS. 3 to 5, by forming the metal film 30 on the first surface 11 e of the membrane portion 11 f so as to straddle the concave planar shape P that is at least a part of the outer edge portion of the membrane portion 11 f. The metal film 30 serves as a reinforcing part against the bending deformation of the membrane part 11f, and the membrane part 11f can be prevented from being damaged.

  Further, as shown in FIG. 7, the membrane portion 11f is deformed in a direction in which the sealing hole 11c expands due to the bending deformation of the membrane portion 11f, thereby generating internal stress. Thereby, there exists a possibility that damage may arise from the inner peripheral surface of the sealing hole 11c. Since the sealing member 40 is formed on the second surface 11d so as to close the sealing hole 11c, the sealing member 40 acts to suppress the expansion of the sealing hole 11c. The member acts as a reinforcing member. Therefore, it is preferable that the sealing member 40 is formed of a metal film or a metal oxide film having excellent ductility.

  As described above, the metal film 30 and the sealing member 40 are provided with the membrane against the bending deformation of the membrane part 11f caused by the pressure difference (ρr−ρs) applied to the membrane part 11f as an external pressure. The portion 11f can be reinforced and damage to the membrane portion 11f can be prevented.

  Further, in the form of the metal film 30 shown in FIG. 3, the metal film 30 is formed so as to cover the entire area of the concave plane shape P which is the outer edge part of the membrane part 11f, whereby the membrane in the D part region shown in FIG. Even if breakage occurs in a portion where the possibility of breakage of the portion 11f is high, the hermetic sealing of the breakage portion is maintained inside the cavity S by the excellent ductility of the metal film 30.

  As described above, in the electronic device 100 according to the first embodiment, the membrane portion 11f in which the sealing hole 11c for hermetically sealing the cavity S is formed has the internal pressure ρs of the cavity S and the outside of the electronic device 100. Against the bending deformation caused by the pressure difference between the external pressure ρr and the first surface 11e on the cavity S side of the membrane part 11f, at least partly straddles the concave planar shape P which is the outer edge part of the membrane part 11f. Thus, the metal film 30 formed up to the first main surface 10a functions as a reinforcing portion of the membrane portion 11f. Thereby, damage to the membrane part 11f can be prevented, and the airtight environment of the cavity S can be stably maintained.

(Second Embodiment)
FIG. 8 shows a partial cross-sectional view of an electronic device 200 according to the second embodiment. The electronic device 200 according to the second embodiment is different in the form of the sealing member 40 provided in the electronic device 100 according to the first embodiment, and the other components are the same. Therefore, in the description of the electronic device 200 according to the second embodiment, the same components as those of the electronic device 100 according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The electronic device 200 according to the second embodiment shown in FIG. 8 is formed with a sealing member 50a as a second metal film or a second metal oxide film that hermetically seals the sealing hole 11c provided in the membrane portion 11f. Is done. The sealing member 50 a is formed by extending the wiring film 50 formed on the second main surface 10 b side of the element substrate 10 to the recess 12 b of the base 12.

The wiring film 50 is formed by laminating an insulating film 51 having electrical insulation with the base 12 and a conductive film 52 having electrical conductivity using a metal or the like from the second main surface 10b. The The insulating film 51 is preferably formed of silicon oxide (SiO ₂ ) by a CVD method. For example, gold (Au), copper (Cu), aluminum (Al), or the like is preferably formed as the conductive film 52 by a sputtering method.

  When the insulating film 51 is formed, the gas (for example, air) inside the cavity S is evacuated through the sealing hole 11c by the CVD method performed in a vacuum environment. Then, the insulating film 51 is also formed in the recess 12b, so that the first sealing member 51a is formed on the second surface 11d of the membrane portion 11f, and at the same time, the second sealing hole 11c. The opening of the surface 11d is closed and the cavity S is hermetically sealed.

  Further, the conductive film 52 is formed by being laminated on the insulating film 51, so that the first sealing member 51 a extending from the insulating film 51 is formed on the second surface 11 d of the membrane portion 11 f from the conductive film 52. A sealing member 50a as a second metal film or a second metal oxide film in which the extending second sealing member 52a is laminated is formed.

  In the electronic device 200 according to the second embodiment, a metal film 30 is formed on the first surface 11e on the cavity S side in the membrane portion 11f, and a sealing hole 11c is formed on the second surface 11d. A sealing member 50a is provided on the entire second surface 11d including the opening on the second surface 11d side. Therefore, in addition to the metal film 30, the sealing member in addition to the metal film 30 causes the membrane portion 11 f to be deformed by a differential pressure between the internal pressure ρs of the cavity S and the external pressure ρr outside the electronic device 100 as shown in FIG. 50a acts as a reinforcing part, and the bending deformation of the membrane part 11f can be further suppressed.

(Modification)
FIG. 9 is a sectional view showing a modification of the membrane portion 11f of the electronic device 100 according to the first embodiment shown in FIG. The electronic device 300 according to the modified example is different in the form of the membrane portion 11f of the electronic device 100 according to the first embodiment and the other configurations are the same. The description is omitted.

  In the electronic device 300 illustrated in FIG. 9, a recess 312 a having an opening is formed on the second main surface 310 a side of the element substrate 310. The recess 312 a of this example has a bottom 312 b in the base 312. The first base surface 312c bonded to the element formation layer 311 corresponding to the region of the bottom 312b and the bottom 312b constitute a thin portion 312d. Hereinafter, the thin portion 312d is referred to as a second membrane portion 312d.

  A region of the element formation layer 311 bonded to the second membrane portion 312d is configured as a first membrane portion 311a, and the element substrate 310 is constituted by the first membrane portion 311a and the second membrane portion 312d. The membrane portion 310b is formed on the surface. A first membrane portion 311a extending from the first surface 311b of the membrane portion 310b on the first main surface 310c side of the element substrate 310 to the bottom portion 312b of the recess 312a as the second surface of the membrane portion 310b; A through hole sealing hole 310d penetrating through the second membrane portion 312d is formed. The sealing hole 310d is sealed by the sealing member 40, and the cavity S is hermetically sealed.

  On the first surface 311b of the membrane portion 310b, a metal film 30 as a first metal film or a first metal oxide film is formed except at least the formation portion of the sealing hole 310d. And at least a part of the outside of the metal film 30 extends to the first main surface 310c.

  The membrane part 310b included in the electronic device 300 includes a first membrane part 311a formed of a part of the element forming layer 311 and a second membrane part 312d formed of a part of the base 312 and has higher strength. A membrane can be obtained. Therefore, it is possible to reduce the bending deformation of the membrane portion 310b that is caused when the differential pressure (ρr−ρs) is applied to the membrane portion 310b as an external pressure. Furthermore, the metal film 30 and the sealing member 40 can reinforce the membrane portion 310b and prevent damage due to the bending deformation of the membrane portion 310b.

(Third embodiment)
FIG. 10 is a flowchart showing a method for manufacturing an electronic device according to the third embodiment. The flowchart shown in FIG. 10 shows a process for manufacturing the electronic device 100 according to the first embodiment. FIGS. 11 to 16 are cross-sectional views showing the manufacturing steps of the electronic device according to the third embodiment.

(Board preparation process)
First, as a substrate preparation step (S1), an element substrate 10 on which an element portion 11a is formed as shown in FIG. 11 is prepared using an SOI substrate as a substrate material M (not shown). In the element substrate 10, an element portion 11 a is formed in the element formation layer 11, and a base cavity 12 a is formed in the base portion 12 in the formation region of the element portion 11 a.

(First film forming step)
A first film formation step (S2) is performed on the element substrate 10 prepared in the substrate preparation step (S1). In the first film forming step (S2), as shown in FIG. 12, the first planar shape having a frame shape is formed so as to surround the first recessed portion forming portion formed in the first recessed portion forming step described later. A metal film 30 as the metal film or the first metal oxide film is formed. For the metal film 30, a metal having excellent ductility, for example, copper (Cu), gold (Au), aluminum (Al), or the like is preferably used. The metal film 30 is formed into a predetermined shape using a resist mask patterned on the first main surface 10a by sputtering or by photolithography.

(First recess forming step)
The metal film 30 is formed by the first film formation step (S2), and the process proceeds to the first recess formation step (S3). In the first recess forming step (S3), as shown in FIG. 13, the first recess 10c is formed in the formation region of the metal film 30 from the first main surface 10a side of the element substrate 10. In the method for manufacturing the electronic device 100 according to the present embodiment, the first recess 10c is formed at one place.

  The first concave portion 10c can be formed by performing etching from an opening of a resist mask patterned on the first main surface 10a by, for example, a photolithography method. The first recess 10c is etched to remove at least the element forming layer 11 in the region of the first recess 10c in order to form a hole penetrating the element forming layer 11 by a second recess forming process described later. The In addition, the 1st recessed part 10c may be formed to the base 12 so that it may show in figure.

(Lid joining process)
In the lid bonding step (S4), the lid 20 is bonded to the first main surface 10a of the element substrate 10. In this example, the lid portion 20 is exemplified by a case where a glass lid portion is used. However, the lid portion 20 is not limited thereto, and may be ceramics, metal, or the like.

  As shown in FIG. 14, the lid 20 has a lid cavity 20 a on one side, and the lid 20 is arranged so that the lid cavity 20 a faces the element substrate 10 and bonded to the element substrate 10. By doing so, a cavity S for accommodating the element portion 11a is constituted by the lid portion cavity 20a and the base portion cavity 12a of the base portion 12.

  The lid 20 and the element substrate 10 are joined by joining a bonding surface 20b of the lid 20 to the element substrate 10 and a first main surface 10a of the element substrate 10 with, for example, borosilicate glass on the lid 20. And a method of anodically bonding the element substrate 10 mainly composed of silicon and the bonding surface 20b, or a low melting point glass powder between the bonding surface 20b and the first main surface 10a of the element substrate 10. For example, a fusion bonding method is preferably used. As shown in FIG. 14, the lid part joining step (S4) in which the lid part 20 is joined to the element substrate 10 is performed, and the process proceeds to the second recess forming step.

(Second recess forming step)
In the second recess forming step (S5), as shown in FIG. 15, the removal region E of the base 12 having a planar shape including the region of the first recess 10c in plan view (Z-axis direction arrow view) (FIG. 15). The silicon forming the base portion 12 of the dot hatching portion shown in FIG. 3 is removed by etching until reaching the element formation layer 11 to form a concave portion 12b as a second concave portion.

  By forming the recess 12 b, the first recess 10 c is formed in the sealing hole 11 c that penetrates the element forming layer 11. Moreover, the membrane part 11f formed with the element formation layer 11 is formed by forming the recessed part 12b. In the manufacturing method of the electronic device according to the present embodiment, it is exemplified that the recess 12b is formed on the metal film 30 as shown in FIG. That is, the planar shape of the recess 12 b in plan view is formed inside the outer planar shape of the metal film 30. In other words, in the first film formation step (S2), the metal film 30 is formed so as to exceed the formation region of the designed recess 12b in plan view.

(Sealing process)
Next, a sealing step (S6) for maintaining the space environment of the cavity S in a predetermined environment is performed. In the sealing step (S6), the internal space of the cavity S is formed through the sealing hole 11c formed by the above-described second recess forming step (S4) and communicating the cavity S with the outside. A gas, for example, air, is evacuated to seal the sealing hole 11c.

  As shown in FIG. 16, in the sealing step (S6), a desired space environment of the cavity S is brought into a vacuum state, the sealing member 40 is formed from the recess 12b side so as to cover the sealing hole 11c, and the cavity is formed. S is hermetically sealed, and the electronic device 100 according to the first embodiment is obtained. Specifically, the sealing member 40 is made of a metal film, and the cavity S is evacuated by a sputtering method performed in a vacuum chamber, and is applied to the second surface 11d on the concave portion 12b side of the membrane portion 11f by a photolithography method or the like. The cavity S is hermetically sealed by forming a film in a predetermined shape using a patterned resist mask.

  In the sealing step (S6), when the sealing hole 11c is hermetically sealed by the sealing member 40 and the electronic device 100 is taken out from the vacuum chamber, the vacuum chamber is moved from the vacuum state (for example, 10 pa) to the atmospheric pressure (101325 pa at a stroke). ) State, the differential pressure (ρr−ρs) is shockedly applied to the membrane portion 11f described in FIG.

  The metal film 30 formed from the first surface 11e of the membrane portion 11f to the first main surface 10a with respect to the differential pressure (ρr−ρs) that is shockedly applied to the membrane portion 11f is a membrane. It becomes a reinforcement member with respect to the bending deformation of the portion 11f, and the membrane portion 11f can be prevented from being damaged.

(Fourth embodiment)
FIG. 17 is a flowchart showing a method for manufacturing an electronic device as the fourth embodiment. The flowchart shown in FIG. 17 shows a process for manufacturing the electronic device 200 according to the second embodiment. The electronic device manufacturing method according to the fourth embodiment is different in the sealing step (S6) in the electronic device manufacturing method according to the third embodiment. Therefore, the description of the substrate preparation step (S1) to the second recess formation step (S5), which are the same manufacturing method as that of the third embodiment, is omitted, and the same components are denoted by the same reference numerals and description thereof is omitted.

(Sealing process)
The sealing step (S60) in the method for manufacturing the electronic device 200 as the fourth embodiment includes a conductive film forming step (S61) shown in FIGS.

(Conductive film formation process)
In the conductive film forming step (S61), first, as shown in FIG. 18, the second main surface 10b of the element substrate 10 (see FIG. 15) on which the membrane portion 11f is formed by the second concave portion forming step (S5) is formed. An insulating film 51 is formed by the CVD method. The CVD method is a method of forming a coating produced by a scientific reaction on the surface of an object to be processed placed in a vacuum chamber. In the conductive film forming step (S61) according to the present embodiment, for example, silicon oxide (SiO ₂ ) is generated as the insulating film 51 and is formed on the surface of the second main surface 10b. At this time, the insulating film 51 is formed so as to cover the concave portion 12b of the base portion 12 and the second surface 11d of the membrane portion 11f.

  Since the insulating film 51 is formed by the CVD method as described above, the cavity S is maintained in a vacuum state and the insulating film 51 is formed. Then, a part of the insulating film 51 formed on the surface of the second surface 11d of the membrane portion 11f is formed so as to cover the sealing hole 11c, and a first sealing member 51a as a sealing member is formed.

  Next, as shown in FIG. 19, a desired pattern (not shown) of the conductive film 52 is formed on the surface of the insulating film 51 by sputtering a conductive material such as gold (Au), copper (Cu), or aluminum (Al). Formed and laminated. At this time, a part of the conductive film 52 is laminated so as to cover at least the first sealing member 51a, and a second sealing member 52a as a second-layer laminated member is formed. The first sealing member 51a of the insulating layer formed in advance and the second sealing member 52a of the conductive layer laminated on the first sealing member 51a constitute the sealing member 50a, and the electronic device 200 is can get.

  As described above, the first sealing of the insulating layer is performed by the conductive film forming step (S61) of forming the insulating film 51 and the conductive film 52 laminated on the insulating film 51 as the manufacturing method of the sealing step (S60). The sealing member 50a can be formed by the member 51a and the second sealing member 52a of the conductive layer laminated on the first sealing member 51a.

  According to the method for manufacturing the electronic device 200 described above, the metal film 30 is formed on the first surface 11e on the cavity S side in the membrane portion 11f, and the sealing hole 11c is formed on the second surface 11d. A sealing member 50a is provided on the entire second surface 11d including the opening on the second surface 11d side. Therefore, in addition to the metal film 30, the sealing member in addition to the metal film 30 causes the membrane portion 11 f to be deformed by a differential pressure between the internal pressure ρs of the cavity S as shown in FIG. 7 and the external pressure ρr outside the electronic device 100. 50a acts as a reinforcing part, and the bending deformation of the membrane part 11f can be further suppressed.

  DESCRIPTION OF SYMBOLS 10 ... Element substrate, 11 ... Element formation layer, 12 ... Base part, 20 ... Lid part, 30 ... Metal film, 40 ... Sealing member, 100 ... Electronic device.

Claims (7)

An electronic device in which an element portion is housed in a housing space constituted by a first main surface of an element substrate and a lid portion joined to the first main surface,
A concave portion having an opening on the second main surface side opposite to the first main surface of the element substrate; and a membrane portion constituted by a bottom portion of the concave portion and the first main surface. ,
The membrane portion includes a sealing hole on the first main surface side,
The first surface on the first main surface side of the membrane portion includes a first metal film or a first metal oxide film,
A part of the first metal film or the first metal oxide film extends to the first main surface outside the first surface;
An electronic device characterized by that. The first metal film or the first metal oxide film extends to the first main surface outside the first surface;
The electronic device according to claim 1. A sealing member that covers the sealing hole of the membrane portion is disposed at the bottom of the recess.
The electronic device according to claim 1, wherein the electronic device is an electronic device.   The electronic device according to claim 3, wherein the sealing member is a second metal film or a second metal oxide film.   The electronic device according to claim 4, wherein the second metal film is extended from the conductive film. A substrate preparation step of preparing an SOI substrate on which an element portion is formed;
A first film forming step of forming a first metal film or a first metal oxide film on at least a part of a first main surface of the SOI substrate on which the element portion is formed;
A first recess forming step of forming a first recess in a formation region of the first metal film or the first metal oxide film;
A lid joining step for joining a lid constituting a housing space for the element part to the first main surface;
A membrane portion provided with the sealing hole, wherein the bottom of the first recess is removed from the second main surface opposite to the first main surface of the SOI substrate, and the first recess is used as a sealing hole; A second recess forming step for forming a second recess to be configured;
A sealing step in which the housing space is a predetermined space environment, and the sealing hole is hermetically sealed.
The manufacturing method of the electronic device characterized by the above-mentioned. The sealing step includes a conductive film forming step of forming a conductive film on the second main surface side.
The method of manufacturing an electronic device according to claim 6.

Images