JP2010228019A - Manufacturing method of electronic device - Google Patents

Abstract

An object of the present invention is to provide a method of manufacturing an electronic device which can obtain desired frequency characteristics and improve yield.
SOLUTION: A substrate 6, a functional element 7, and a cavity 5 in which the functional element 7 is arranged have an element surrounding structure 8. The functional element 7 includes a fixed electrode 71, a movable plate 722, and a connecting portion 723. A method of manufacturing an electronic device 1 having a movable electrode 72 having a vibration system 724 made of the element surrounding structure 8, wherein the element surrounding structure 8 has a coating layer 331 having a plurality of pores 332 communicating with the cavity 5. The step of preparing an electronic device, the step of measuring the natural frequency of the vibration system 724, and the deposition of the weight material 9 on the connecting portion 723 through the pores 332 make it possible to generate the natural vibration of the vibration system 724. A natural frequency adjusting step for adjusting the number, and a sealing step for sealing the pores 332.
[Selection] Figure 6

Description

  The present invention relates to an electronic device manufacturing method.

  2. Description of the Related Art In recent years, electronic devices such as sensors, resonators, and communication devices that use MEMS (Micro Electro Mechanical System) technology and have a MEMS element on a semiconductor substrate have attracted attention. Such an electronic device includes a substrate, a functional element (MEMS element) formed on the substrate, and an element surrounding structure that is provided on the substrate and defines a cavity in which the functional element is disposed. An electronic device is known (for example, Patent Document 1).

  In the electronic device of Patent Document 1, a functional element forming step for forming a functional element on a substrate, and an insulating film and a covering layer having an opening are stacked in this order on the functional element, and then the opening of the covering layer is formed. The insulating film on the functional element is removed by supplying an etching solution through the cavity to form a cavity, and finally a sealing layer that seals the opening of the covering layer is formed to form a structure around the element. And the element surrounding structure process.

  Here, in the electronic device of Patent Document 1, it is important that the functional element has a desired frequency characteristic. In order for the functional element to exhibit the desired frequency characteristics, the shape, size, formation position, etc. of the movable plate of the functional element must be set in particular, but the shape, size, formation position of the movable plate, etc. It is difficult to set such as predetermined because a high level forming technique is required. Therefore, in the electronic device of Patent Document 1, it is difficult to obtain a desired frequency characteristic, and as a result, there is a problem that the yield is lowered.

JP 2008-212435 A

  An object of the present invention is to provide a method of manufacturing an electronic device that can obtain desired frequency characteristics and improve yield.

Such an object is achieved by the present invention described below.
According to another aspect of the present invention, there is provided a method of manufacturing an electronic device comprising: a substrate; a functional element formed on the substrate; and an element surrounding structure provided on the substrate and defining a cavity in which the functional element is disposed. And the functional element includes: a fixed electrode provided on the substrate; a movable part disposed opposite to the fixed electrode with a gap; a support part that supports the movable part; and the movable part and the support part And a movable electrode that constitutes a vibration system by the movable part and the coupling part, and the element surrounding structure has a plurality of openings that communicate with the cavity part. A pre-adjustment electronic device preparation step of preparing a pre-adjustment electronic device having a coating layer in which holes are formed;
A natural frequency measuring step for measuring the natural frequency of the vibration system;
Based on the measurement result in the natural frequency measurement step, the natural frequency of the vibration system is adjusted by depositing a weight material on the connecting portion of the functional element through the opening of the coating layer. Natural frequency adjustment process;
A sealing step of sealing the plurality of apertures of the coating layer.
Thereby, since the natural frequency of the movable part with which a functional element is provided can be adjusted in the middle of manufacture, the electronic device which can exhibit a desired frequency characteristic can be provided. In addition, the yield during mass production is improved.

According to another aspect of the present invention, there is provided a method of manufacturing an electronic device comprising: a substrate; a functional element formed on the substrate; and an element surrounding structure provided on the substrate and defining a cavity in which the functional element is disposed. And the functional element includes a fixed electrode provided on the substrate, a movable part disposed opposite to the fixed electrode with a gap, a support part for supporting the movable part, and the movable part and the support part. In a method for manufacturing an electronic device, including an elastically deformable coupling portion that couples a movable electrode and a movable electrode that constitutes a vibration system by the movable portion and the coupling portion.
A functional element forming step of forming a sacrificial layer located between the fixed electrode and the movable part together with the functional element;
An insulating film forming step of forming an insulating film on the functional element;
A coating layer forming step of forming a coating layer having a plurality of openings on the insulating film;
The cavity is formed by removing the insulating film on the functional element through the opening of the covering layer, and the fixed electrode and the movable part are separated by removing the sacrificial layer. Release process
A natural frequency measuring step for measuring the natural frequency of the vibration system;
Based on the measurement result in the natural frequency measurement step, the natural frequency of the vibration system is adjusted by depositing a weight material on the connecting portion of the functional element through the opening of the coating layer. Natural frequency adjustment process;
And a sealing step of sealing the plurality of apertures of the covering layer to form the element surrounding structure.
Thereby, since the natural frequency of the movable part with which a functional element is provided can be adjusted in the middle of manufacture, the electronic device which can exhibit a desired frequency characteristic can be provided. In addition, the yield during mass production is improved.

In the electronic device manufacturing method of the present invention, it is preferable that in the functional element formation step, the functional element is formed so that a natural frequency of the vibration system is lower than a predetermined value.
This improves the yield of the electronic device.
In the electronic device manufacturing method according to the aspect of the invention, in the natural frequency adjusting step, a part of the plurality of holes is sealed, and the connection portion is connected to the connection part through the unsealed holes. It is preferred to deposit weight material.
Accordingly, it is possible to prevent the fixed electrode and the movable portion from being fixed or electrically connected by the weight material. Therefore, it is possible to manufacture an electronic device that can exhibit desired frequency characteristics and is excellent in reliability.

In the electronic device manufacturing method of the present invention, it is preferable that the weight material is deposited at a boundary portion between the support portion and the connection portion in the natural frequency adjusting step.
This makes it easier to deposit (adhere) the weight material on the connecting portion. Moreover, since the weight material adheres across the connecting portion and the support portion when deposited in this way, the natural frequency of the vibration system can be efficiently increased with a small amount of deposition.

In the electronic device manufacturing method of the present invention, the plurality of openings include at least one weight material passage opening formed to face a boundary portion between the support portion and the connection portion,
In the natural frequency adjusting step, it is preferable that the weight material is deposited on a boundary portion between the support portion and the connecting portion through a weight material passage opening.
Thereby, the weight material can be deposited relatively easily on the boundary portion between the connecting portion and the support portion.

In the method for manufacturing an electronic device according to the present invention, it is preferable that in the natural frequency adjusting step, at least one weight material selected from a plurality of types of weight materials having different Young's moduli is deposited on the connection portion.
As a result, the natural frequency of the vibration system can be adjusted (adjusted to a predetermined value) with high accuracy and efficiency (reduction of processing time and reduction in the amount of weight material used).

In the electronic device manufacturing method of the present invention, it is preferable that an average hole diameter of the plurality of holes is 0.5 μm to 2 μm.
Thereby, it is possible to prevent the frequency material from becoming unable to be adjusted because the weight material is clogged in each opening before the frequency is adjusted. In addition, the amount of weight material that passes through each aperture per unit time is an appropriate amount (not too much but not too small), so that the natural frequency of the movable part can be adjusted with high accuracy and efficiency. Can do.

In the electronic device manufacturing method of the present invention, it is preferable that the plurality of apertures are formed in a matrix, and a distance between adjacent apertures is 1 μm to 20 μm.
As a result, an appropriate number of openings included in the movable part can be formed in plan view of the substrate, so that the amount of weight material deposited on the movable part per unit time is an appropriate amount (not too much but not too small). Therefore, the natural frequency of the movable part can be adjusted with high accuracy and efficiency.

It is sectional drawing which shows the electronic device manufactured by the manufacturing method of the electronic device which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the electronic device shown in FIG. It is sectional drawing which shows the manufacturing method of the electronic device shown in FIG. It is sectional drawing which shows the manufacturing method of the electronic device shown in FIG. It is an enlarged plan view of the coating layer with which the electronic device shown in FIG. 1 is provided. It is sectional drawing which shows the manufacturing method of the electronic device shown in FIG. It is sectional drawing which shows the manufacturing method of the electronic device which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the electronic device which concerns on 3rd Embodiment of this invention.

Hereinafter, an electronic device of the present invention will be described in detail based on each embodiment shown in the accompanying drawings.
<First Embodiment>
FIG. 1 is a cross-sectional view showing an electronic device manufactured by the method for manufacturing an electronic device according to the first embodiment of the present invention, and FIGS. 2, 3, and 4 respectively show the method for manufacturing the electronic device shown in FIG. FIG. 5 is an enlarged plan view of a coating layer included in the electronic device shown in FIG. 1, and FIG. 6 is a sectional view showing a method for manufacturing the electronic device shown in FIG. In the following, for convenience of explanation, the upper side of FIGS. 1 to 6 is referred to as “upper”, the lower side is referred to as “lower”, the right side is referred to as “right”, and the left side is referred to as “left”.
The electronic device 1 shown in FIG. 1 includes a substrate 6, a functional element 7, an element surrounding structure 8, and a semiconductor circuit (not shown). Each of these parts will be described in turn below.

The substrate 6 is a plate member having a substantially square or substantially rectangular shape in plan view. Such a substrate 6 is configured by laminating an insulating film 62 and a silicon nitride film 63 in this order on a semiconductor substrate 61 made of a semiconductor.
The functional element 7 includes a fixed electrode 71 formed on the substrate 6 and a movable electrode 72.
The movable electrode 72 includes a support portion 721 formed on the silicon nitride film 63 of the substrate 6, a movable plate (movable portion) 722 disposed opposite to the fixed electrode 71 with a gap, and the fixed electrode 71 and the movable plate 722. And an elastically deformable connecting portion 723 that connects the two. In addition, the movable plate 722 is cantilevered by the support portion 721 via the connecting portion 723. Further, the movable plate 722 and the connecting portion 723 constitute a vibration system 724. When a high frequency having a frequency equivalent to the natural frequency of the movable plate 722 is applied between the movable plate 722 and the fixed electrode 71, the movable plate 722 vibrates (resonates) while elastically deforming the connecting portion 723, and the fixed electrode. A current flows between 71 and the movable plate 722, and the current is output (detected) from the fixed electrode 71.

The element surrounding structure 8 is formed so as to define the cavity 5 in which the functional element 7 is disposed. Such an element surrounding structure 8 includes an interlayer insulating film 81 formed on the substrate 6 so as to surround the functional element 7, a wiring layer 82 formed on the interlayer insulating film 81, the wiring layer 82, and the interlayer insulation. An interlayer insulating film 83 formed on the film 81, a wiring layer 84 formed on the interlayer insulating film 83 and having a coating layer 841 having a plurality of pores (openings), the wiring layer 84, and the interlayer insulating film 83, a surface protective film 85 formed on 83, and a sealing layer 86 provided on coating layer 841.
In the element surrounding structure 8 having such a configuration, an opening (not shown) partially missing is formed. Electrode wirings (not shown) are connected to the fixed electrode 71 and the movable electrode 72 of the functional element 7, respectively, and these wirings are drawn to the outside of the element surrounding structure 8 through the opening.

A semiconductor circuit (not shown) is formed on and above the semiconductor substrate 61. This semiconductor circuit has circuit elements such as active elements such as MOS transistors, capacitors, inductors, resistors, diodes, wirings (including the electrode wirings and wiring layers 82 and 84) formed as necessary. .
Hereinafter, a method for manufacturing the electronic device 1 having the above configuration (a method for manufacturing the present invention) will be described.

The electronic device manufacturing method of the present invention includes a functional element forming step of forming a sacrificial layer located between the fixed electrode and the movable plate together with the functional element, an insulating film forming step of forming an insulating film on the functional element, insulation A coating layer forming step of forming a coating layer having a plurality of pores (openings) on the film, and forming a cavity by removing the insulating film on the functional element through the pores of the coating layer A release step of separating the fixed electrode and the movable plate by removing the sacrificial layer, a natural frequency measurement step of measuring the natural frequency of the vibration system, and a connecting portion of the functional element through the pores of the coating layer A natural frequency adjusting step for adjusting the natural frequency of the vibration system and a sealing layer for sealing the pores of the coating layer are formed by depositing a weight material on the sealing material to form a structure surrounding the element. Process.
As described above, the electronic device manufacturing method according to the present invention includes the natural frequency adjustment step of adjusting the natural frequency of the vibration system 724 of the functional element 7, and thus can exhibit desired frequency characteristics. The electronic device 1 can be manufactured easily and reliably. For example, when the electronic device 1 is mass-produced, the yield is improved. Hereinafter, each process will be described sequentially.

[Functional element formation process]
As shown in FIG. 2A, a semiconductor substrate 100 made of a semiconductor such as a silicon substrate is prepared. Note that a ceramic substrate, a glass substrate, a sapphire substrate, a diamond substrate, a synthetic resin substrate, or the like may be used instead of the semiconductor substrate 100. Next, a silicon oxide film (insulating film) 110 is formed by thermally oxidizing the surface (upper surface) of the prepared semiconductor substrate 100. Further, a silicon nitride film 120 is formed on the silicon oxide film 110 by sputtering, CVD, or the like. Form. Thereby, the substrate 6 is obtained.

  The silicon oxide film 110 functions as an element isolation film when a semiconductor circuit is formed on the semiconductor substrate 100 and above. Further, the silicon nitride film 120 has durability against etching performed in a release process performed later, and functions as a so-called etching stop layer. Note that the silicon nitride film 120 is formed by patterning so as to be limited to a range including a planar range in which the functional element 7 is formed and a range of a part of elements (capacitors) in the semiconductor circuit. As a result, the semiconductor substrate 100 and a semiconductor circuit formed thereon are not obstructed.

  Next, as shown in FIG. 2B, a polycrystalline (or amorphous) silicon film 200 for forming the fixed electrode 71 is formed on the silicon nitride film 120 by sputtering, CVD, or the like. The (or amorphous) silicon film 200 is doped with impurity ions such as phosphorus ions to impart conductivity. Then, a photoresist is applied on the polycrystalline (or amorphous) silicon film 200 and patterned into the shape of the fixed electrode 71 (a shape in plan view) to form a photoresist film 210.

Next, as shown in FIG. 2C, after the polycrystalline (or amorphous) silicon film 200 is etched using the patterned photoresist film 210 as a mask, the photoresist film 210 is removed. Thereby, the fixed electrode 71 is formed.
Next, as shown in FIG. 2D, a sacrificial layer 220 made of a silicon oxide film, PSG (phosphorus doped glass), or the like is formed so as to cover the fixed electrode 71 by a thermal oxidation method, a sputtering method, a CVD method, or the like. .

Next, as shown in FIG. 2E, a polycrystalline (or amorphous) silicon film 230 for forming the movable electrode 72 is formed on the silicon nitride film 120 and the sacrificial layer 220 by sputtering, CVD, or the like. The formed polycrystalline (or amorphous) silicon film 230 is doped with impurity ions such as phosphorus ions to impart conductivity. Then, a photoresist is applied on the polycrystalline (or amorphous) silicon film 230 and patterned into the shape of the movable electrode 72 (a shape in plan view) to form a photoresist film 240.
Next, as shown in FIG. 2F, after the polycrystalline (or amorphous) silicon film 230 is etched using the photoresist film 240 as a mask, the photoresist film 240 is removed. Thereby, the movable electrode 72 is formed (the support part 721, the movable plate 722, and the connection part 723 (vibration system 724) are integrally formed).

As described above, the functional element 7 is formed together with the sacrificial layer 220 on the substrate 6. In this step, the functional element 7 is formed so that the natural frequency (resonance frequency) of the vibration system 724 is lower than a predetermined value (target value). Thereby, the yield of the electronic device 1 is improved. Specifically, for example, when the electronic device 1 is mass-produced, if the natural frequency of the vibration system 724 is adjusted to a predetermined value from the beginning, the natural frequency may be included due to the limit of formation accuracy. However, there are also a vibration system 724 having a natural frequency equal to or lower than a predetermined value and a vibration system 724 having a predetermined frequency equal to or higher than a predetermined value. Among these, for the vibration system 724 whose natural frequency is equal to or lower than a predetermined value, the natural frequency can be adjusted to a predetermined value in the subsequent natural frequency adjusting step, but the natural frequency is equal to or higher than the predetermined value. The vibration system 724 cannot be adjusted. This is because the natural frequency adjustment step can be adjusted only in the direction of increasing the natural frequency of the vibration system 724.
On the other hand, if the vibration system 724 is formed in advance so that the natural frequency is equal to or higher than a predetermined value in consideration of formation accuracy, the generation of the vibration system 724 having the natural frequency equal to or lower than the predetermined value can be prevented. it can. Therefore, the natural frequency of the vibration system 724 can be adjusted to a predetermined value at the manufacturing stage for all the electronic devices 1. As a result, the yield of the electronic device 1 is improved.

[Insulating film formation process]
As shown in FIG. 3A, an interlayer insulating film 300 made of a silicon oxide film or the like is formed on the silicon nitride film 120 and the functional element 7 by a sputtering method, a CVD method, or the like. In addition, an annular opening 301 surrounding the functional element 7 in a plan view of the semiconductor substrate 100 is formed in the interlayer insulating film 300 by a patterning process (for example, a patterning process using a photoresist as described above). Note that the opening 301 may not have an annular shape in plan view of the semiconductor substrate 100, and a part of the opening 301 may be missing.

  Next, as shown in FIG. 3B, a wiring layer 310 is formed by forming a layer made of, for example, aluminum on the interlayer insulating film 300 by a sputtering method, a CVD method or the like and then performing a patterning process. The wiring layer 310 has an annular shape in plan view of the semiconductor substrate 100 so as to correspond to the opening 301. Further, a part of the wiring layer 310 is electrically connected to a wiring (for example, a wiring constituting a part of a semiconductor circuit (not shown)) formed on and above the semiconductor substrate 100 through the opening 301. Note that the wiring layer 310 is formed so as to exist only in a portion surrounding the functional element 7, but in general, a part of the wiring layer constituting a part of a semiconductor circuit (not shown) is formed in the wiring layer 310. Is configured.

Next, as shown in FIG. 3C, an interlayer insulating film 320 made of a silicon oxide film or the like is formed on the interlayer insulating film 300 and the wiring layer 310 by a sputtering method, a CVD method, or the like. In addition, an annular opening 321 that surrounds the functional element 7 in a plan view of the semiconductor substrate 100 is formed in the interlayer insulating film 320 by a patterning process or the like. Note that, like the opening 301, the opening 321 may not have an annular shape in plan view of the semiconductor substrate 100, and a part thereof may be missing.
Such a laminated structure of the interlayer insulating film and the wiring layer is formed by a normal CMOS process, and the number of laminated layers is appropriately set as necessary. In other words, more wiring layers may be stacked via an interlayer insulating film as necessary.

[Coating layer forming step]
As shown in FIG. 4A, after a layer made of, for example, aluminum is formed on the interlayer insulating film 320 by sputtering, CVD, or the like, a wiring layer 330 is formed by patterning. A part of the wiring layer 330 is electrically connected to the wiring layer 310 through the opening 321. A part of the wiring layer 330 is located above the functional element 7 and constitutes a covering layer 331 in which a plurality of pores 332 are formed. Such a wiring layer 330 is generally constituted by a part of a wiring layer constituting a part of a semiconductor circuit (not shown), similarly to the wiring layer 310 described above.

  Next, as shown in FIG. 4B, a surface protective film 340 made of, for example, a silicon nitride film, a resist, or other resin material is formed on the wiring layer 330 and the interlayer insulating film 320 by sputtering, CVD, or the like. The surface protective film 340 is composed of a plurality of film layers containing one or more kinds of materials, and is formed so as not to seal the pores 332 of the coating layer 331. The constituent material of the surface protective film 340 is formed of a material having resistance for protecting the element from moisture, dust, scratches, and the like, such as a silicon oxide film, a silicon nitride film, a polyimide film, and an epoxy resin film.

[Release process]
As shown in FIG. 4C, the interlayer insulating film on the functional element 7 passes through the plurality of pores 332 formed in the covering layer 331 after performing a protective film forming process such as a photoresist for release etching. 300 and 320 are removed, and the sacrificial layer 220 between the fixed electrode 71 and the movable plate 722 is removed. Thus, the cavity 5 in which the functional element 7 is disposed is formed, the fixed electrode 71 and the movable plate 722 are separated from each other, and the functional element 7 can be driven (the vibration system 724 can vibrate). Become.

The interlayer insulating films 300 and 320 and the sacrificial layer 220 can be removed by, for example, wet etching that supplies hydrofluoric acid, buffered hydrofluoric acid, or the like as an etchant from the plurality of pores 332 or fluorine gas as an etching gas from the plurality of pores 332. The dry etching can be performed by supplying a hydrofluoric acid gas or the like.
Thereby, the electronic device before adjustment before the natural frequency of the vibration system 724 is adjusted is obtained. That is, it can be said that the pre-adjustment electronic device preparation step is configured by the functional element formation step, the insulating film formation step, the coating layer formation step, and the release step.
In addition, after removing the interlayer insulating films 300 and 320 and the sacrificial layer 220 and the resist film, the inside of the cavity 5 may be cleaned as necessary.

[Natural frequency measurement process]
Next, the natural frequency (resonance frequency) of the vibration system 724 is measured. The measurement method is not particularly limited. For example, the fixed electrode 71 is grounded, the movable electrode 72 is connected to a network analyzer (not shown), and an alternating voltage is applied from the network analyzer to the movable electrode 72. Increase the frequency gradually. At this time, the current value output from the fixed electrode 71 is detected, and the frequency of the alternating voltage when the current value reaches the peak is set as the natural frequency of the vibration system 724, whereby the natural frequency of the vibration system 724 is set. You may measure.

[Natural frequency adjustment process]
In this natural frequency adjustment step, the weight material 9 is sputtered to the connecting portion 723 (boundary portion of the connecting portion 723 and the support portion 721) via the pores 332 (weight material passing pores 332a and 332b described later). By accumulating and increasing the spring constant of the connecting portion 723, the natural frequency (resonance frequency) of the vibration system 724 is changed in the increasing direction, and is adjusted to a predetermined value (target value). Thereby, since the frequency characteristic of the functional element 7 can be adjusted during the manufacture of the electronic device 1, the electronic device 1 that can exhibit the desired frequency characteristic can be manufactured easily and reliably.

Hereinafter, a method for adjusting the natural frequency of the vibration system 724 will be specifically described. Prior to that, the plurality of pores 332 formed in the coating layer 331 will be described.
FIG. 5 is a plan view of the coating layer 331 when viewed from above the apparatus. As shown in the figure, the coating layer 331 has a plurality of pores 332 penetrating in the thickness direction in a matrix. The plurality of pores 332 are formed such that the row direction (the vertical direction in FIG. 5) coincides with the width direction of the connecting portion 723 (the extending direction of the boundary portion between the connecting portion 723 and the support portion 721). Yes.

  Such a plurality of pores 332 include a plurality of weight material passage pores 332 a and 332 b located on the boundary portion between the connecting portion 723 and the support portion 721. As will be described later, the weight material 9 is deposited on the connecting portion 723 through the weight material passing pores 332a and 332b. In addition, it does not specifically limit as the number of the pores for weight material passage, One may be sufficient and three or more may be sufficient.

  The distance D between adjacent weight material passing pores 332a and 332b varies depending on the shape and size of the weight material passing pores 332a and 332b, but is preferably about 1 μm to 20 μm. Thereby, an appropriate number of pores for passing through the weight material located on the boundary portion between the connecting portion 723 and the support portion 721 can be formed. Therefore, when the weight material 9 is deposited on the connecting portion 723 by the sputtering method, the weight material deposition amount per unit time with respect to the connecting portion 723 becomes an appropriate amount (not too much but not too small), and the natural frequency of the vibration system 724. Can be adjusted with high accuracy and efficiency (rapidly).

  The opening shape (cross-sectional shape) of each pore 332 is substantially circular. Moreover, the opening diameter of each of the weight material passing pores 332a and 332b is not particularly limited, but is preferably about 0.5 μm to 2 μm. By setting the opening diameter of each weight material passing pore 332a, 332b within the above range, when the weight material 9 is deposited on the connecting portion 723 by the sputtering method, the weight material passing pore 332a, 332b has a weight. It is possible to prevent the material 9 from being clogged. In addition, the amount of the weight material 9 that passes through each of the weight material passing pores 332a and 322b per unit time becomes an appropriate amount (not too much but not too small), and the natural frequency of the vibration system 724 can be adjusted with high accuracy. And can be performed efficiently.

Next, a method for adjusting the natural frequency of the vibration system 724 will be specifically described with reference to FIG. 6 is a cross-sectional view taken along line AA in FIG.
As shown in FIG. 6A, the mask 400 is disposed so as to cover the pores 332 other than the weight material passing pores 332a and 332b. Thus, by covering the pores 332 other than the weight material passing pores 332a and 332b with the mask 400, it is ensured that the weight material 9 is deposited on a portion other than the boundary portion between the connecting portion 723 and the support portion 721. Can be prevented. Therefore, for example, it is possible to prevent the fixed electrode 71 and the movable plate 722 and other wirings exposed in the cavity 5 from being electrically connected (short-circuited) via the weight material 9.

  Next, as shown in FIG. 6B, the weight material 9 is deposited on the boundary portion between the connecting portion 723 and the support portion 721 through the weight material passing pores 332 a and 332 b by the sputtering method. Thereby, since the weight material 9 adheres across the connection part 723 and the support part 721, the spring constant of the connection part 723 becomes high, and the natural frequency of the vibration system 724 becomes high. In this way, the natural frequency of the vibration system 724 is changed in the direction of increasing and adjusted to a predetermined value.

As in the present embodiment, the weight material 9 is deposited on the boundary portion between the connecting portion 723 and the support portion 721, so that the weight material 9 is easily deposited (fixed) on the connecting portion 723. Moreover, since the weight material 9 adheres across the connecting portion 723 and the support portion 721 when deposited in this way, for example, when the weight material 9 is deposited on the center of the left surface of the connecting portion 723 in FIG. In comparison, the natural frequency of the vibration system 724 can be increased efficiently with a small amount of deposition.
In this embodiment, since the weight material passing pores 332a and 332b are positioned so as to face the boundary portion between the connecting portion 723 and the support portion 721 (that is, directly above), the connecting portion 723 is provided. The weight material 9 can be deposited relatively easily on the boundary portion between the support portion 721 and the support portion 721.

  The step of depositing the weight material 9 at the boundary portion between the connecting portion 723 and the support portion 721 may be performed only once, but is preferably performed a plurality of times. Furthermore, when performing a plurality of times, it is preferable to measure the natural frequency of the vibration system 724 every time between them, whereby the natural frequency of the vibration system 724 can be gradually adjusted to a predetermined value. . Therefore, the natural frequency of the vibration system 724 can be adjusted carefully and with high accuracy. The measurement of the natural frequency can be performed in the same manner as the above-described natural frequency measurement process.

  Note that, for example, a correlation between the sputtering processing time and the natural frequency change of the vibration system 724 (the natural frequency change amount per unit time) is obtained in advance through experiments or the like, and is measured in the natural frequency measurement step. From the amount of deviation between the natural frequency of the vibration system 724 and the predetermined value, the sputtering processing time required to adjust the natural frequency of the vibration system 724 to the predetermined value is obtained, and the sputtering process is performed according to the determined processing time. You may go. In this case, the natural frequency of the vibration system 724 can be adjusted to a predetermined value by performing the process of depositing the weight material 9 at the boundary portion between the connecting portion 723 and the support portion 721 only once. Therefore, the natural frequency of the vibration system 724 can be adjusted quickly.

Further, the method for depositing the weight material 9 at the boundary portion between the connecting portion 723 and the support portion 721 is not limited to the sputtering method, and for example, a CVD method, a vapor deposition method, and other various film forming methods can be used. However, it is preferable to use the sputtering method because of the straightness of the weight material 9 (target) and the ability to use a mask.
The weight material 9 is not particularly limited. For example, various materials such as AL, W, Ni, Cu, Co, Mo, Ti, Au, Si, Ge, and alloys containing at least one of these materials (for example, Stainless steel), and oxides and nitrides of these metals.

[Sealing process]
Finally, as shown in FIG. 6C, a sealing layer 350 made of a silicon oxide film, a silicon nitride film, a metal film such as AL, Cu, W, Ti, TiN, or the like is formed on the coating layer 331 by a sputtering method. The pores 332 are sealed by the CVD method or the like.
The electronic device 1 having a desired frequency characteristic can be manufactured by the processes as described above. Note that circuit elements such as active elements such as MOS transistors, capacitors, inductors, resistors, diodes, wirings, and the like included in the semiconductor circuit included in the electronic device 1 are used during the above-described appropriate steps (for example, functional element formation step, insulating film formation). Process, covering layer forming step, sealing layer forming step). For example, an isolation film between circuit elements is formed together with the silicon oxide film 110, a gate electrode, a capacitor electrode, a wiring, etc. are formed together with the fixed electrode 71 and the movable electrode 72, and a gate is formed together with the sacrificial layer 220 and the interlayer insulating films 300 and 320. An insulating film, a capacitive dielectric layer, an interlayer insulating film can be formed, and in-circuit wiring can be formed together with the wiring layers 310 and 330.

<Second Embodiment>
Next, a second embodiment of the electronic device manufacturing method of the present invention will be described.
FIG. 7 is a cross-sectional view illustrating a method for manufacturing an electronic device according to the second embodiment of the present invention. In the following, for convenience of explanation, the upper side of FIG. 7 is referred to as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”.

Hereinafter, the manufacturing method of the electronic device according to the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.
The method for manufacturing an electronic device according to the second embodiment of the present invention is the same as that of the first embodiment described above except that the natural frequency adjustment step is different. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment mentioned above.

In this embodiment, as the weight material 9 deposited on the boundary portion between the connecting portion 723 and the support portion 721, a first weight material 91 and a second weight material 92 having a Young's modulus lower than that of the first weight material 91 are used. And are used.
In the present embodiment, the natural frequency adjustment step includes a temporary adjustment step and a main adjustment step. The temporary adjustment step uses the first weight material 91 and the natural vibration of the vibration system 724 when there is a large difference between the natural frequency of the vibration system 724 measured in the natural frequency measurement step and the predetermined value. This is a process for efficiently increasing the number up to a predetermined value. That is, the temporary adjustment process is a process in which speed is more important than accuracy and the usage amount of the weight material 9 is reduced.

On the other hand, this adjustment step is a step of finishing the temporary adjustment step and increasing the natural frequency of the vibration system 724 near the predetermined value to the predetermined value with high accuracy using the second weight material 92. . That is, this adjustment process is a process in which importance is attached to the adjustment accuracy of the natural frequency rather than speed and the reduction in the amount of weight material 9 used.
Since the natural frequency adjustment step includes the temporary adjustment step and the main adjustment step, the natural frequency of the vibration system 724 is adjusted with high accuracy and efficiency (reduction in processing time and reduction in the amount of use of the weight material 9). (Adjusted to a predetermined value). Hereinafter, the temporary adjustment process and the main adjustment process will be sequentially described.

[Temporary adjustment process]
In this step, first, as shown in FIG. 7A, a mask 410 is disposed so as to cover the pores 332 other than the weight material passing pores 332a and 332b. Next, as shown in FIG. 7B, the first weight material 91 is deposited on the boundary portion between the connecting portion 723 and the support portion 721 through the weight material passing pores 332 a and 332 b. Since the first weight material 91 has a higher Young's modulus than the second weight material 92, the natural frequency of the vibration system 724 is increased with a small amount of deposition as compared with the case where the second weight material 92 is deposited. Can be increased. By performing such a temporary adjustment process once or a plurality of times as in the first embodiment described above, the natural frequency of the vibration system 724 is set to a predetermined value.

[Main adjustment process]
In this step, as shown in FIG. 7C, the second weight material 92 is deposited on the boundary portion between the connecting portion 723 and the support portion 721 through the weight material passing pores 332a and 332b. Since the second weight material 92 has a Young's modulus lower than that of the first weight material 91, the natural frequency of the vibration system 724 can be made smaller than that of the temporary adjustment process in which the first weight material 91 is deposited. Can be increased. By performing this adjustment process once or a plurality of times as in the first embodiment described above, the natural frequency of the vibration system 724 is adjusted to a predetermined value.

As described above, in the natural frequency adjusting process according to the present embodiment, the weight material selected from a plurality of types of weight materials having different Young's moduli is deposited on the connection portion 723 (the boundary portion between the connection portion 723 and the support portion 721). Therefore, the natural frequency of the vibration system 724 can be adjusted with high accuracy and efficiency.
In this embodiment, two types of weight materials 91 and 92 having different Young's moduli are used as the weight material 9, but the type of weight material is not limited to this and may be three or more types. .
According to the second embodiment as described above, the same effect as that of the first embodiment can be exhibited.

<Third Embodiment>
Next, a third embodiment of the method for manufacturing an electronic device according to the present invention will be described.
FIG. 8 is a cross-sectional view illustrating a method for manufacturing an electronic device according to a third embodiment of the present invention. In the following, for convenience of explanation, the upper side in FIG. 8 is referred to as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”.

Hereinafter, the manufacturing method of the electronic device according to the third embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.
The method for manufacturing an electronic device according to the third embodiment of the present invention is the same as that of the first embodiment described above except that the natural frequency adjustment step is different. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment mentioned above.

  As shown in FIG. 8, in this embodiment, when the weight material 9 is deposited on the connecting portion 723 by the sputtering method, the pre-adjustment electronic device is inclined with respect to the moving direction (arrow direction) of the weight material 9. It is a feature. Thereby, the weight material 9 that has passed through the weight material passing pores 332a and 332b can be received by the surface 723a on the support portion 721 side of the connecting portion 723, and the weight material 9 is easily deposited on the surface 723a. can do. Whether the weight material 9 is deposited on the surface 723a of the connecting portion 723 by adjusting the inclination of the electronic device before adjustment (see FIG. 8A), at the boundary portion between the connecting portion 723 and the support portion 721. It is possible to appropriately select whether to deposit (see FIG. 8B).

Here, in the case where the same amount (mass) of the weight material 9 is deposited on the surface 723a of the connecting portion 723 and the case where the weight material 9 is deposited on the boundary portion between the connecting portion 723 and the support portion 721, the latter is more The natural frequency of the vibration system 724 can be increased.
Therefore, for example, the natural frequency adjustment step is provided with the temporary adjustment step and the main adjustment step as described in the second embodiment, and in the temporary adjustment step, the weight material 9 is connected to the connecting portion 723 and the support portion 721. In this adjustment process, the pre-adjustment electrical device is tilted so that the weight material 9 is deposited on the surface 723a of the connecting portion 723, so that the high-accuracy and The natural frequency of the vibration system 724 can be adjusted efficiently (adjusted to a predetermined value) efficiently (shortening the processing time and reducing the usage amount of the weight material 9).

In the case of this embodiment, considering that the pre-adjustment electronic device is tilted, the weight material passes through the pore 332 on the left side in FIG. 8 immediately above the boundary between the connecting portion 723 and the support portion 721. The pores 332a and 332b for use are preferably selected.
According to the third embodiment as described above, the same effect as that of the first embodiment can be exhibited.

  As mentioned above, although the manufacturing method of the electronic device of this invention was demonstrated based on each embodiment of illustration, this invention is not limited to these, The structure of each part is the thing of arbitrary structures which have the same function Can be substituted. Moreover, other arbitrary structures and processes may be added. In addition, the electronic device manufacturing method of the present invention may be a combination of any two or more configurations (features) of the above embodiments.

  Further, in the above-described embodiment, the case where the weight material deposition position is on the boundary part between the connection part and the support part or on the support part side surface of the connection part has been described. If the spring constant of a connection part can be raised, it will not specifically limit, For example, the side surface of the width direction of a connection part may be sufficient. In this case, since the width of the connecting portion is substantially increased, the spring constant is increased accordingly.

  DESCRIPTION OF SYMBOLS 1 ... Electronic device 100 ... Semiconductor substrate 110 ... Silicon oxide film 120 ... Silicon nitride film 200, 230 ... Polycrystalline (or amorphous) silicon film 210, 240 ... Photoresist film 220 ... Sacrificial layer 300, 320... Interlayer insulating film 301, 321... Opening 310, 330... Wiring layer 331 .. Covering layer 332... Fine pore 332 a, 332 b. Sealing layer 400, 410 ... Mask 5 ... Cavity 6 ... Substrate 61 ... Semiconductor substrate 62 ... Insulating film 63 ... Nitride film 7 ... Functional element 71 ... Fixed electrode 72 ... Movable electrode 721 ... Supporting part 722 ... Movable plate 723 ... Connecting part 723a ... Surface 724 ... Vibration system 8 ... Element surrounding structure 81, 83 ... Interlayer insulating film 82, 84 …… Wiring layer 841 …… Coating layer 85 …… Surface protection film 86 …… Sealing layer 9 …… Weight material 91 …… First weight material 92 …… Second weight material

Claims (9)

A substrate, a functional element formed on the substrate, and an element surrounding structure that is provided on the substrate and defines a cavity in which the functional element is disposed, and the functional element includes the substrate A fixed electrode provided on the movable electrode, a movable part disposed opposite to the fixed electrode with a gap, a support part that supports the movable part, and an elastically deformable connection part that connects the movable part and the support part A movable electrode that constitutes a vibration system by the movable part and the coupling part, and the element surrounding structure has a coating layer in which a plurality of openings communicating with the cavity part are formed A pre-adjustment electronic device preparation step of preparing a pre-electronic device;
A natural frequency measuring step for measuring the natural frequency of the vibration system;
Based on the measurement result in the natural frequency measurement step, the natural frequency of the vibration system is adjusted by depositing a weight material on the connecting portion of the functional element through the opening of the coating layer. Natural frequency adjustment process;
And a sealing step for sealing the plurality of openings in the covering layer. A substrate, a functional element formed on the substrate, and an element surrounding structure that is provided on the substrate and defines a cavity in which the functional element is disposed, and the functional element includes the substrate A fixed electrode provided on the movable electrode, a movable part disposed opposite to the fixed electrode with a gap, a support part that supports the movable part, and an elastically deformable connection part that connects the movable part and the support part In a method of manufacturing an electronic device having a movable electrode that constitutes a vibration system by the movable part and the connecting part,
A functional element forming step of forming a sacrificial layer located between the fixed electrode and the movable part together with the functional element;
An insulating film forming step of forming an insulating film on the functional element;
A coating layer forming step of forming a coating layer having a plurality of openings on the insulating film;
The cavity is formed by removing the insulating film on the functional element through the opening of the covering layer, and the fixed electrode and the movable part are separated by removing the sacrificial layer. Release process
A natural frequency measuring step for measuring the natural frequency of the vibration system;
Based on the measurement result in the natural frequency measurement step, the natural frequency of the vibration system is adjusted by depositing a weight material on the connecting portion of the functional element through the opening of the coating layer. Natural frequency adjustment process;
And a sealing step of sealing the plurality of apertures of the covering layer to form the element surrounding structure.   3. The method of manufacturing an electronic device according to claim 1, wherein in the functional element formation step, the functional element is formed such that a natural frequency of the vibration system is lower than a predetermined value.   In the natural frequency adjustment step, a part of the plurality of openings is sealed, and the weight material is deposited on the connection portion through the unsealed openings. The manufacturing method of the electronic device in any one of.   5. The method of manufacturing an electronic device according to claim 1, wherein, in the natural frequency adjusting step, the weight material is deposited at a boundary portion between the support portion and the connecting portion. The plurality of openings include at least one weight material passage opening formed so as to face a boundary portion between the support portion and the connecting portion;
6. The method of manufacturing an electronic device according to claim 5, wherein, in the natural frequency adjusting step, the weight material is deposited at a boundary portion between the support portion and the connecting portion through a weight material passage opening.   The electronic device according to claim 1, wherein in the natural frequency adjusting step, at least one weight material selected from a plurality of types of weight materials having different Young's moduli from each other is deposited on the connecting portion. Production method.   The method for manufacturing an electronic device according to claim 1, wherein an average opening diameter of the plurality of openings is 0.5 μm to 2 μm.   The method for manufacturing an electronic device according to claim 1, wherein the plurality of apertures are formed in a matrix, and a distance between adjacent apertures is 1 μm to 20 μm.

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