JP2008221450A - Mems package and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a MEMS package, which prevents dust adhesion after a hollowing process, and preventing breakage or the like during a manufacturing process. <P>SOLUTION: The manufacturing method for the MEMS package having a MEMS element in a hollow structure includes: a process for preparing a MEMS board; a process for forming a sacrificial layer on the MEMS board; a process for forming the MEMS element connected to the MEMS board and extended over the sacrificial layer; a board jointing process for jointing a cover board for covering the MEMS element on the MEMS board; a hollowing process for hollowing the MEMS element by removing the sacrificial layer; and a sealing process for sealing a passage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a MEMS package in which a MEMS element is sealed and a MEMS package.

  In a MEMS (Micro Electro Mechanical Systems) element, a structure called a hollow structure or a free standing structure is generally used. In this structure, for example, the movable electrode is held on the substrate electrode with a gap of several tens of μm, and the MEMS element is enclosed in an airtight package for mechanical protection of the structure and prevention of adhesion of dust. There is a need to. For this reason, in the conventional MEMS element, after performing the hollowing process which forms a hollow structure, the airtight sealing process is performed (for example, refer nonpatent literature 1).

  However, since the hollow structure is stored while being exposed to the atmosphere from the hollowing process to the hermetic sealing process, there is a problem in that dust adheres to the hollow structure during this time and malfunction occurs.

On the other hand, after forming a metal sacrificial layer so as to cover the MEMS element, and further forming a cap layer so as to cover the metal sacrificial layer, the metal sacrificial layer is etched away through a passage formed in the cap layer to form a hollow structure. And a method for preventing dust from adhering to the hollow structure is performed (for example, see Patent Document 1).
JP 2001-237334 A A. Jourdain et al., "From Zero-to Second-Level Packaging of RF-MMEMS Devices", IEEE MEMS 2005, Technical Digest, 2005 pp.36-39

  However, in the method described in Patent Document 1, since the cap layer serving as a hermetic sealing lid is formed of a thin film, the mechanical strength is weak, and the cap layer is deformed during the manufacturing process. There was a problem that the hollow structure was destroyed.

  Moreover, since the thickness of the cap layer is limited, in order to increase the strength of the cap layer, it is necessary to relatively reduce the sealing area.

  Moreover, since the space | gap between a cap layer and a MEMS element is prescribed | regulated by the thickness of a sacrificial layer, it is very narrow. For this reason, the etching solution etc. which can be supplied at the time of etching of a sacrificial layer decreases, and there also existed a problem that the etching time of a sacrificial layer became long.

  Furthermore, the supply path for the etching solution or the like is sealed with solder, but since the gap in the cap layer is narrow, there is a problem in that the solder comes into contact with the MEMS element, causing malfunction of the MEMS element.

  Therefore, an object of the present invention is to provide a MEMS package manufacturing method and a MEMS package that prevent dust from being attached after the hollowing process and that do not break down during the manufacturing process.

  The present invention relates to a method of manufacturing a MEMS package having a hollow-structure MEMS element, a step of preparing a MEMS substrate, a step of forming a sacrificial layer on the MEMS substrate, and a sacrificial layer connected to the MEMS substrate. A step of forming a MEMS element extending above, a substrate bonding step of bonding a lid substrate on the MEMS substrate so as to cover the MEMS element, and a hollowing step of removing the sacrificial layer to form a hollow structure of the MEMS element And a sealing process for sealing the passage.

  The present invention also relates to a MEMS package having a hollow structure MEMS element, which is connected to the MEMS substrate and connected to the MEMS substrate, and is joined to the MEMS substrate so as to cover the MEMS element. The MEMS package includes a passage embedded in the MEMS substrate or the lid substrate with a sealing material.

  ADVANTAGE OF THE INVENTION According to this invention, while preventing adhesion of the dust after a hollowing process, the MEMS package which does not generate | occur | produce the destruction in a manufacturing process, etc. can be provided.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view of the manufacturing process of the MEMS package according to the first embodiment of the present invention, the whole being represented by 100. This manufacturing process includes the following steps 1-1 to 1-6.

  Step 1-1: As shown in FIG. 1A, first, a MEMS substrate 1 is prepared. The MEMS substrate 1 is made of, for example, a semiconductor material such as Si, Ge, or GaAs, glass, ceramic, or the like. The thickness of the MEMS substrate 1 is preferably about 10 μm to 1 mm, for example.

Next, a material to be a sacrificial layer is formed on the MEMS substrate 1 and patterned into a predetermined shape to form the sacrificial layer 2. The material of the sacrificial layer 2 needs to be selectively etched away with respect to other materials in the hollowing process described later, for example, a dielectric material such as SiO ₂ , porous silicon, polysilicon, photoresist, A metal material or the like mainly composed of Cu, Ni, Fe, Al, Cr, Ti or the like is used. The thickness of the sacrificial layer 2 defines the gap of the hollow structure and is determined by the use of the MEMS element 3. Generally, the range is from 100 nm to 500 μm. For the deposition of the sacrificial layer 2, plating, sputtering, vapor deposition, chemical vapor deposition, or the like can be used.

Step 1-2: As shown in FIG. 1B, a MEMS element material is deposited on the MEMS substrate 1 and the sacrificial layer 2 and patterned so that a part thereof overlaps the sacrificial layer 2. Element 3 is formed. The material and thickness of the MEMS element 3 are determined depending on the application. As the material, for example, a metal material mainly composed of polysilicon, SiO ₂ , SiN, Cu, Ni, Fe, Al, Cr, Ti, Au, W, or the like can be used, and the thickness is about 50 nm to 500 μm. It is.
Note that the MEMS element 3 and the sacrificial layer 2 need to be formed from different materials. For forming the MEMS element 3, a plating method, a sputtering method, a vapor deposition method, a chemical vapor deposition method, or the like is used.

Step 1-3: As shown in FIG. 1C, at least one hole is formed in the MEMS substrate 1 to form a passage 4 that serves as an etching agent supply passage in a subsequent hollowing step. For the formation of the passage 4, methods such as mechanical drilling, sand blasting, electric discharge machining, laser ablation, reactive ion etching, and wet etching can be used. The horizontal cross section of the passage 4 is circular or rectangular, and its cross-sectional dimension is preferably in the range of 10 μm square (or φ) to 1 mm square (or φ).
The passage may be formed before or after step 1-1 (FIG. 1A) or immediately before step 1-5 (FIG. 1E). Further, in steps 1-1 to 1-3 (FIGS. 1A to 1C), a hole is made halfway, and the remaining portion is removed by etching immediately before the hollowing step, or the MEMS substrate 1 May be thinned to penetrate the hole.

  Step 1-4: As shown in FIG. 1D, the lid substrate 5 is prepared. For the lid substrate 5, as with the MEMS substrate 1, for example, a semiconductor material such as Si, Ge, GaAs, glass, ceramic, or the like can be used. The thickness is preferably about 10 μm to 1 mm. The lid substrate 5 can be provided with a recess for containing the MEMS element 3. A method such as sand blasting, wet etching, reactive ion etching, or the like is used to form the recess.

  Subsequently, a substrate bonding step is performed in which the MEMS substrate 1 and the lid substrate 5 are bonded so as to include the MEMS element 3. For bonding, solder, resin, low-melting glass is used as an adhesive, or Au or other metal film formed on the bonding surface is alloyed at high temperature without using a bonding method or adhesive. For example, a direct bonding method in which the bonding surface is activated and bonding is performed only by heating and pressurization, and an anodic bonding method in which the Si substrate and the glass substrate are bonded by heating, pressing and applying a voltage are used.

Step 1-5: As shown in FIG. 1E, a hollowing step for selectively removing the sacrificial layer 2 is performed. The hollowing process is performed by introducing an etching agent (etching gas or etching solution) for selectively removing the sacrificial layer 2 into the cavity 6.
After the sacrificial layer 2 is selectively removed, a rinsing liquid and a gas are sufficiently flowed and dried. At this time, when the etching agent is a liquid, it is preferable to use freeze drying or a critical drying method in order to prevent the hollow structure from sticking (adhering) due to surface tension.

Step 1-6: As shown in FIG. 1 (f), the passage 4 is closed with a sealing material 7, and the inside of the package is hermetically sealed. As the sealant 7 can be used SiO _2, low melting point glass, solder, Au, Cu, metal such as Ni, resin, conductive paste or the like. The sealing material 7 may be completely filled in the passage 4 or may be partially filled to the extent that airtightness is ensured.
For filling the sealing material 7, an ink jet method, a molten metal discharge method, a filling plating method, an injection method using a dispenser, a method of sucking a sealing material melted at a high temperature into the cavity by a pressure difference between the inside and the outside of the cavity, and the like are used. be able to.
Alternatively, a substrate such as Si or glass may be used as the sealing material 7, and this may be covered on the passage 4 and adhered with an adhesive or solder, and hermetically sealed.

  Through the above steps, the MEMS package 100 according to the first embodiment shown in FIG. 1F is completed.

In the manufacturing method according to the first embodiment, since the hollowing process (FIG. 1 (e)) is performed after the substrate bonding process (FIG. 1 (d)), the dust adhesion after the hollowing process is prevented. A MEMS package free from the risk of defects is obtained.
In addition, a package structure with high mechanical strength that does not break in the manufacturing process and use environment can be obtained.
In addition, a relatively large area can be hermetically sealed as compared with the conventional thin film packaging manufacturing method. Further, it is not necessary to form a sacrificial layer that covers the entire MEMS element, which is necessary in the thin film packaging manufacturing method. Compared with packaging, the volume of the space for sealing the element is large, and a large amount of etching solution or etching gas is supplied during the sacrifice layer etching. Therefore, the time required for the sacrifice layer etching can be greatly reduced.

  In the MEMS package 100 completed through the above steps, the MEMS substrate 1 is provided with a passage 4 made of a through hole, and the passage is filled with a sealing material 7. A MEMS element 3 is provided on the MEMS substrate 1. The MEMS element 3 has a hollow structure in which a part thereof is supported by the MEMS substrate 1 and a part thereof is separated from the MEMS substrate 1.

The MEMS element 3 is, for example, a MEMS switch, and an electrostatic movable electrode of the switch can be configured by this hollow structure. In FIG. 1 (f), only the movable electrode of the MEMS element 3 is described, and other components such as the lower electrode, the electrostatic suction electrode, the wiring, and the pad are not described.
The MEMS element 3 may be directly formed on the MEMS substrate 1, or another substrate on which the MEMS element 3 is formed may be mounted on the MEMS substrate 1. A lid substrate 5 is bonded to the MEMS element 3 side of the MEMS substrate 1. A cavity 6 between the MEMS substrate 1 and the lid substrate 5 surrounds the MEMS element 3 so as to enclose the MEMS element 3, and as a result, the MEMS element 3 is hermetically sealed. The cavity 6 may be formed by forming a recess in the lid substrate 5, and when the lid substrate is a flat plate having no recess, the bonding surface between the lid substrate 5 and the MEMS substrate 1 has a thickness. You may comprise by inserting a spacer and an adhesive bond layer.

  With the configuration of the MEMS package 100 as described above, the MEMS element 3 having a hollow structure is protected against an external environment such as dust, humidity, corrosive gas, and physical contact with other components.

Embodiment 2. FIG.
FIG. 2 is a cross-sectional view of the manufacturing process of the MEMS package according to the second embodiment of the present invention, the whole being represented by 200. 2, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. This manufacturing process includes the following steps 2-1 to 2-6.

  Steps 2-1 to 2-2: As shown in FIGS. 2A to 2B, the same steps as steps 1-1 to 1-2 of the first embodiment are performed.

  Step 2-3: As shown in FIG. 2C, after preparing the lid substrate 5, at least one through hole is opened in the lid substrate 5 to form a passage 4.

Steps 2-4 to 2-6: As in the steps 1-4 to 1-6 of the first embodiment, first, the MEMS substrate 1 and the lid substrate 5 are bonded as shown in FIG.
Subsequently, as shown in FIG. 2E, an etching agent is supplied through the passage 4 formed in the lid substrate 5 to selectively remove the sacrificial image 2.
Finally, as shown in FIG. 2 (f), the passage 4 is filled with a sealing material 7 and sealed, whereby the MEMS package 200 is completed.

  In the MEMS package 200 according to the second embodiment, since it is not necessary to secure a region for the opening of the passage 4 in the MEMS substrate 1, the area of the MEMS package can be reduced.

Further, when the sealing material 7 is filled in the passage 4, there is a problem that the filling of the sealing material becomes difficult as the aspect ratio (through hole depth / through hole opening diameter) of the passage 4 increases. In order to avoid this, it is only necessary to make the substrate through which the through hole is made thinner. However, in the first embodiment, if the MEMS substrate 1 is made too thin, the warp of the substrate occurs and the operation of the MEMS element 3 is hindered. There's a problem.
On the other hand, in the MEMS package 200 according to the second embodiment, the thickness of the lid substrate 5 can be reduced and the filling process of the passage 4 can be facilitated without affecting the operation of the MEMS element 3. it can. Specifically, if the thickness of the lid substrate 5 is 250 μm, the depth of the passage 4 is 50 μm, and the diameter of the passage is 50 μm with respect to the thickness of the MEMS substrate 1 of 500 μm, the aspect ratio of the passage 4 becomes 1. Filling with the sealing material 7 becomes easy.

Embodiment 3 FIG.
FIG. 3 is a cross-sectional view of the manufacturing process of the MEMS package according to the third embodiment of the present invention, the whole being represented by 300. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. This manufacturing process includes the following steps 3-1 to 3-6.

  Step 3-1: As shown in FIG. 3A, the MEMS substrate 1 is prepared, and the sacrificial layer 2 and the etching stop film 21 are formed on the MEMS substrate 1. The etching stop film 21 is preferably formed of the same material as the sacrificial layer 2 and formed in the same patterning process.

  Step 3-2: As shown in FIG. 3B, the MEMS element 3 is formed on the MEMS substrate 1 and the sacrificial layer 2 in the same step as in the first embodiment.

Step 3-3: As shown in FIG. 3C, at least one hole is formed in the MEMS substrate 1 on the back surface side of the etching stop film 21 to form the passage 4. The upper part of the passage 4 is sealed with an etching stop film 21.
In such a process, by providing the etching stop film 21, even if the etching time varies, the finished shape of the passage 4 can be made substantially constant and the process margin can be increased.

  Step 3-4: As shown in FIG. 3D, a substrate bonding step for bonding the MEMS substrate 1 and the lid substrate 5 so as to enclose the MEMS element 3 is performed.

  Step 3-5: As shown in FIG. 3E, a hollowing step for selectively removing the etching stop film 21 and the sacrificial layer 2 is performed. The hollowing process is performed by introducing an etching agent (etching gas or etching solution) for selectively removing the etching stop film 21 and the sacrificial layer 2 into the cavity 6.

  Step 3-6: As shown in FIG. 3 (f), the passage 4 is closed with the sealing material 7, and the inside of the package is hermetically sealed. Through the above steps, the MEMS package 300 according to the third embodiment is completed.

  As described above, in the manufacturing method according to the third embodiment, since the passage 4 is formed below the etching stop film 21, the finished shape of the passage 4 can be made substantially constant even if the etching time varies. For this reason, the process margin of the etching process can be increased.

  In the third embodiment, the passage 4 and the etching stop layer 21 are provided on the MEMS substrate 1, but the same effect can be obtained even if provided on the lid substrate 5.

Embodiment 4 FIG.
FIG. 4 is a cross-sectional view of the manufacturing process of the MEMS package according to the fourth embodiment of the present invention, the whole being represented by 400. 4, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

  In the manufacturing method according to the fourth embodiment, after performing steps 2-1 to 2-2 (FIGS. 2A to 2B) of the second embodiment, the steps shown in FIG. I do.

  As shown in FIG. 4A, after the passage 4 is formed in the lid substrate 5, the solder base film 8 is formed on the inner wall of the passage 4. The solder base film 8 is formed by sequentially forming Cr, Ni, and Au by a sputtering method or a vapor deposition method using a stencil mask that is open only in the portion of the passage 4. Here, Cr is an adhesion strengthening layer with the material of the lid substrate 5, and Ni is a barrier layer. Au is a layer for improving wettability with solder. The thickness of each layer is, for example, 0.05 μm for Cr, 1 μm for Ni, and 0.05 μm for Au.

  Note that Ti or the like may be used for the adhesion reinforcing layer instead of Cr. In addition, instead of Ni, Fe, Ni, or an alloy containing Fe as a main component may be used for the barrier layer. Further, Ag, Pt, Pd or the like may be used for the solder wettability improving layer instead of Au. The film thickness of the adhesion reinforcing layer is preferably 0.001 to 0.2 μm, the barrier layer is preferably 0.1 to 20 μm, and the solder wettability improving layer is preferably 0.01 to 1 μm.

  Further, as a method for producing the solder base film 8, a solder base film may be formed on the entire surface of the lid substrate 5 by using a sputtering method, a vapor deposition method, or a combination thereof with a plating method without using a stencil mask.

  Anisotropic dry etching, such as ion milling, is used to remove the solder base film other than the inner wall of the passage 4. In addition, the solder base film on the surface of the lid substrate other than the inner wall of the passage 4 can also be removed by applying an adhesive tape to the surface of the lid substrate 5 on which the solder base film is formed and peeling it off. Alternatively, the solder underlayer on the surface of the lid substrate 5 other than the inner wall of the passage 4 may be removed by photolithography while the passage 4 is masked with a photoresist or the like.

  Subsequent to the step shown in FIG. 4A, a substrate bonding step of bonding the MEMS substrate 1 and the lid substrate 5 so as to enclose the MEMS element 3 is performed, and then the sacrificial layer 2 is selectively removed. A hollowing process is performed. After the sacrificial layer 2 is selectively removed, a rinsing liquid and a gas are sufficiently flowed and dried.

  Next, as shown in FIG. 4B, a sealing material 7 made of solder balls slightly larger than the diameter of the passage 4 is placed on the passage 4. For example, SnAgCu is used as the material for the solder balls.

Next, as shown in FIG.4 (c), this is installed in a vacuum chamber and the inside of a vacuum chamber is exhausted and it is set to 0.95 atmospheric pressure.
Subsequently, the MEMS package is heated to a melting point of SnAgCu (about 220 ° C.) or higher, for example, 250 ° C. to melt the SnAgCu balls.
Subsequently, the pressure inside the vacuum chamber is returned to 1 atm, and then the temperature of the MEMS package is cooled to near room temperature and then taken out from the vacuum chamber.
As a result, as shown in FIG. 4C, the sealing material 7 fills the passage 4 in a shape wetted by the solder base film 8 and seals it.

  As described above, the seal material 7 has very good wettability with the solder base film 8, and the seal material 7 is alloyed with Au and Ni of the solder base film 8 to obtain a strong joint. On the other hand, the wettability is small with respect to materials such as Si, glass and ceramic of the lid substrate 5. For this reason, the sealing material 7 has a surface tension that is in close contact with the inner wall of the passage 4 and is constrained inside the passage 4. A MEMS package with high airtightness can be obtained.

  Furthermore, since the distance between the lower surface of the passage 4 and the upper surface of the MEMS substrate 1 can be increased to 10 μm or more as compared with the conventional thin film packaging, the sealing material 7 extends on the MEMS substrate 1 or extends to the MEMS element 3. This can prevent the MEMS element 3 from malfunctioning.

  In addition, instead of SnAgCu, various solder materials such as SnPb, SnAg, SnIn, SnCu, SnBi may be used as the material of the sealing material 7.

  In the fourth embodiment, the passage 4 is provided in the lid substrate 5, but the same effect can be obtained by providing the passage 4 on the MEMS substrate 1 side as in the first embodiment.

  Further, as a method of closing the passage 4 with the sealing material 7, the method of melting the solder ball and filling the passage 4 is described, but a method of locally filling the inside of the passage 4 with plating or the like may be used. I do not care.

Embodiment 5. FIG.
FIG. 5: is sectional drawing of the manufacturing process of the MEMS package concerning Embodiment 5 of this invention which the whole is represented by 500. FIG. In FIG. 5, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

  In the manufacturing method according to the second embodiment, after performing steps 2-1 to 2-4 (FIGS. 2A to 2D) of the second embodiment, the steps shown in FIG. I do.

  In the step shown in FIG. 5A, the passage 4 is formed in the lid substrate 5 and the solder base film 8 is formed on the inner wall thereof, as in the fourth embodiment. Furthermore, a solder base film 81 is also formed in a region facing the opening of the passage 4 on the MEMS substrate 1.

  Before forming the solder base films 8 and 81, the solder base films 8 and 81 are formed by bonding the MEMS substrate 1 and the lid substrate 5 on which the passage 4 is formed, and then from the lid substrate 5 side, The solder underlayers 8 and 81 are simultaneously formed through a stencil mask by vapor deposition or sputtering. In this process, the solder base film 81 can be formed not only on the inner wall of the passage 4 but also on the MEMS substrate 1 facing the opening of the passage 4, and the solder base film 8 and the solder base film 81 are formed separately. The manufacturing process can be simplified as compared with the case of doing so.

  Subsequently, as shown in FIG. 5B, a hollowing process for selectively removing the sacrificial layer 2 is performed. The hollowing process is performed by introducing an etching agent for selectively removing the sacrificial layer 2 into the cavity 6.

  Subsequently, as shown in FIG. 5C, a sealing material 7 made of a solder ball slightly larger than the diameter of the passage 4 is placed on the passage 4 in the same process as in FIG. For example, SnAgCu is used as the material for the solder balls.

  Subsequently, as shown in FIG. 5D, the sealing material 7 is melted and the passage 4 is closed with the sealing material 7 in the same process as in FIG. 4C described above, and the inside of the package is hermetically sealed. In the method according to the fifth embodiment, as the amount of the sealing material 7, an amount larger than that for filling the passage 4 is supplied. As a result, as shown in FIG. 5D, the melted sealing material 7 protrudes from the passage 4 and also contacts the solder base film 81 on the MEMS substrate 1.

  As a result, the sealing material 7 is alloyed and bonded not only to the solder base film 8 on the inner wall of the passage 4 but also to the solder base film 81 on the MEMS substrate 1. Thereby, the hermetic sealing by the sealing material 7 is performed reliably, and the manufacturing margin of the amount of the sealing material 7 can be increased.

  Further, since the sealing material 7 has good wettability with the solder base film 81, it is difficult to spread outside the solder base film 81 due to surface tension. For this reason, it can prevent that the sealing material 7 spreads on the MEMS board | substrate 1, and causes the malfunction of the MEMS element 3. FIG.

  Moreover, since the sealing material 7 connects between the MEMS substrate 1 and the lid substrate 5 in the cavity 6, the mechanical strength of the package is improved. Through the above steps, the MEMS package 500 according to the fifth embodiment is completed.

It is sectional drawing of the manufacturing process of the MEMS package concerning Embodiment 1 of this invention. It is sectional drawing of the manufacturing process of the MEMS package concerning Embodiment 2 of this invention. It is sectional drawing of the manufacturing process of the MEMS package concerning Embodiment 3 of this invention. It is sectional drawing of the manufacturing process of the MEMS package concerning Embodiment 4 of this invention. It is sectional drawing of the manufacturing process of the MEMS package concerning Embodiment 5 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 MEMS substrate, 2 sacrificial layer, 3 MEMS element, 4 channel | path, 5 lid substrate, 6 cavity, 7 sealing material, 100 MEMS package.

Claims (9)

A method for manufacturing a MEMS package having a hollow MEMS element,
A step of preparing a MEMS substrate;
Forming a sacrificial layer on the MEMS substrate;
Forming a MEMS element connected to the MEMS substrate and extending over the sacrificial layer;
A substrate bonding step of bonding a lid substrate on the MEMS substrate so as to cover the MEMS element;
A hollowing step of removing the sacrificial layer to make the MEMS element have a hollow structure;
And a sealing step for sealing the passage. A substrate opening step for forming a passage through the MEMS substrate;
The method of manufacturing a MEMS package according to claim 1, wherein the hollowing step is a step of removing the sacrificial layer through the passage. The substrate opening step includes a step of forming a passage through the MEMS substrate until the etching stop film is exposed after forming an etching stop film made of the same material as the sacrificial layer on the MEMS substrate,
3. The method of manufacturing a MEMS package according to claim 2, wherein the hollowing step includes a step of removing the etching stop film and the sacrificial layer. A substrate opening step for forming a passage through the lid substrate in the lid substrate;
The method of manufacturing a MEMS package according to claim 1, wherein the hollowing step includes a step of removing the sacrificial layer through the passage. The substrate opening step includes a step of forming a solder base film on the inner wall of the passage,
5. The method of manufacturing a MEMS package according to claim 4, wherein the sealing step includes a step of melting and filling a solder ball disposed outside the passage. The substrate opening step includes a step of forming a solder underlayer on each of the inner wall of the passage and the MEMS substrate facing the passage;
The sealing step includes a step of filling and sealing the passage so that the solder balls disposed outside the passage are melted and connected to the solder base film on the MEMS substrate. Item 5. A method for manufacturing a MEMS package according to Item 4. A MEMS package having a hollow MEMS element,
A MEMS substrate;
A MEMS element connected to the MEMS substrate and having a hollow structure;
A lid substrate bonded on the MEMS substrate so as to cover the MEMS element;
A MEMS package comprising a passage embedded in the MEMS substrate or the lid substrate with a sealing material.   8. The MEMS package according to claim 7, wherein a solder base film is formed on an inner wall of the passage formed in the lid substrate, and the sealing material is embedded in contact with the solder base film.   A solder base film is formed on the inner wall of the passage formed on the lid substrate and on the MEMS substrate facing the passage, and the sealing material is placed in the passage so as to connect between the solder base films. The MEMS package according to claim 7, wherein the MEMS package is embedded.

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