JP2010228018A - 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.
A method of manufacturing an electronic device includes a substrate, a functional element, and a cavity in which the functional element is disposed. The functional element includes a fixed electrode, And a step of preparing a pre-adjustment electronic device having a movable electrode 72 having a movable plate 722, and the element surrounding structure 8 having a coating layer 331 having a plurality of pores 332 communicating with the cavity 5. A natural frequency measurement step for measuring the natural frequency of the plate 722 and a natural frequency adjustment for adjusting the natural frequency of the movable plate 722 by depositing the weight material 9 on the movable plate 722 through the pores 332. 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. The functional element includes: a fixed electrode provided on the substrate; and a movable electrode including a movable part disposed to face the fixed electrode with a gap therebetween. A pre-adjustment electronic device preparation step of preparing a pre-adjustment electronic device having a coating layer having a plurality of apertures communicating with the cavity;
A natural frequency measuring step for measuring the natural frequency of the movable part;
Based on the measurement result in the natural frequency measurement step, the natural frequency of the movable part is adjusted by depositing a weight material on the movable part of the functional element through the opening of the covering layer. The natural frequency adjustment process to
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. In the method of manufacturing an electronic device, the functional element includes a fixed electrode provided on the substrate, and a movable electrode including a movable part disposed to face the fixed electrode with a gap therebetween.
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 movable part;
Based on the measurement result in the natural frequency measurement step, the natural frequency of the movable part is adjusted by depositing a weight material on the movable part of the functional element through the opening of the covering layer. The natural frequency adjustment process to
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 forming step, the functional element is formed such that a natural frequency of the movable portion is higher than a predetermined value.
This improves the yield of the electronic device.
In the electronic device manufacturing method of the present invention, in the natural frequency adjusting step, the weight material can be selectively deposited on a plurality of regions having different distances from the connecting portion on the movable portion. Is preferred.
As a result, the natural frequency of the movable part can be adjusted with high accuracy and efficiency.

In the electronic device manufacturing method of the present invention, in the natural frequency adjusting step, a part of the plurality of openings is closed, and the weight is placed on the movable part via the openings that are not closed. It is preferred to deposit the material.
Thereby, it is possible to reliably prevent the weight material from being deposited on a portion other than the movable portion. Therefore, it is possible to prevent the fixed electrode and the movable part, and other wirings exposed in the cavity from being electrically connected (short-circuited) via the weight material.

In the electronic device manufacturing method of the present invention, the plurality of apertures include a plurality of weight material passage apertures that are included in the movable portion and have different separation distances from the coupling portion in plan view of the substrate. Included,
In the natural frequency adjusting step, at least one of the plurality of weight material passage openings is closed, and the weight material passage opening is closed on the movable portion via the other weight material passage opening. It is preferred to deposit weight material.
Thereby, the natural frequency of the movable part can be adjusted more easily.

In the method for manufacturing an electronic device according to the aspect of the 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 densities is deposited on the movable portion.
As a result, the natural frequency of the movable part can be adjusted with high accuracy and efficiency.
In the electronic device manufacturing method of the present invention, in the natural frequency adjusting step, the weight material having a lower density among the plurality of types of weight materials may be deposited in a region on the connection portion side of the movable portion. preferable.
As a result, the natural frequency of the movable part can be adjusted with high accuracy and efficiency.

In the electronic device manufacturing method of the present invention, the fixed electrode has a protruding portion that protrudes from the movable portion in a plan view of the substrate,
Each of the plurality of openings is preferably formed so as to avoid a boundary portion between the movable portion and the protruding portion in plan view of the substrate.
As a result, the weight material can be reliably deposited on the movable part and can be prevented from being deposited on the fixed electrode, so that the fixed electrode and the movable part can be fixed or electrically connected by the weight material. Can be prevented. 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 an average hole diameter of the plurality of holes is 0.5 μm to 2 μm.
Accordingly, it is possible to prevent the weight material from being clogged in each opening before the frequency is adjusted, and thus the frequency cannot be 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 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. It is sectional drawing which shows the manufacturing method of the electronic device which concerns on 4th Embodiment of this invention. It is sectional drawing which shows the manufacturing method of the electronic device which concerns on 4th 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 a connecting portion 723 that connects the two. The movable plate 722 is cantilevered by the support portion 721 via the connecting portion 723. 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), and a current flows between the fixed electrode 71 and the movable plate 722. Flows, 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 such a configuration (a method for manufacturing the electronic device of 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 movable plate, and a movable plate of the functional element through the pores of the coating layer It has a natural frequency adjusting step for adjusting the natural frequency of the movable plate by depositing a weight material thereon, and a sealing step for forming a sealing layer for sealing the pores of the coating layer. .
As described above, since the electronic device manufacturing method of the present invention includes the natural frequency adjusting step of adjusting the natural frequency of the movable plate 722, the electronic device 1 after manufacture can be surely provided with a desired frequency. The characteristics can be exhibited. Therefore, for example, when mass producing electronic devices, 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 (capacitor or the like) 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 polycrystalline (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 (planar shape) to form a photoresist film 210.

Next, as shown in FIG. 2C, the polycrystalline silicon film 200 is etched using the patterned photoresist film 210 as a mask, and then 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. Then, the polycrystalline (or amorphous) silicon film 230 formed 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 (planar shape) 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 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 of the movable plate 722 is higher 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 movable plate 722 is adjusted to a predetermined value from the beginning, the natural frequency may be included due to the limit of the formation accuracy. However, there are also a movable plate 722 having a natural frequency equal to or lower than a predetermined value and a movable plate 722 higher than a predetermined value. Among these, for the movable plate 722 having a natural frequency equal to or higher than a predetermined value, it is possible to adjust the natural frequency to a predetermined value in a subsequent natural frequency adjusting step, but the natural frequency is equal to or lower than the predetermined value. The movable plate 722 cannot be adjusted. This is because the natural frequency adjustment step can be adjusted only in the direction of lowering the natural frequency of the movable plate 722.
On the other hand, if the movable plate 722 is formed in advance so that the natural frequency becomes equal to or higher than a predetermined value in consideration of the forming accuracy, it is possible to prevent the generation of the movable plate 722 whose natural frequency is lower than the predetermined value. it can. Therefore, the natural frequency of the movable plate 722 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 (wiring forming 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 materials including one or more kinds of film materials, and is subjected to a photoresist patterning and etching process so as not to seal the pores 332 of the coating layer 331. , Forming an opening. 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. Thereby, the cavity 5 in which the functional element 7 is disposed is formed, and the fixed electrode 71 and the movable plate 722 are separated from each other, and the functional element 7 can be driven.

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 movable plate 722 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 as the protective film, the inside of the cavity 5 may be cleaned as necessary.

[Natural frequency measurement process]
Next, the natural frequency (resonance frequency) of the movable plate 722 is measured. The measurement method is not particularly limited. For example, the fixed electrode 71 is grounded, the movable plate 722 is connected to a network analyzer (not shown), an alternating voltage is applied from the network analyzer to the movable plate 722, and 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 movable plate 722, whereby the natural frequency of the movable plate 722 is set. You may measure.

[Natural frequency adjustment process]
In this natural frequency adjusting step, the weight material 9 is deposited on the movable plate 722 via the pores 332 by sputtering, and the mass and the moment of inertia of the movable plate 722 are increased to thereby increase the natural frequency of the movable plate 722. (Resonance frequency) is changed in a decreasing direction, and 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 apparatus 1, the electronic apparatus 1 that exhibits a desired frequency characteristic can be manufactured easily and reliably.

Hereinafter, a method for adjusting the natural frequency of the movable plate 722 will be described in detail. 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 include a plurality of weight material passing pores 332 a to 332 c included in the movable plate 722 in a plan view of the semiconductor substrate 100 (FIG. 5). As will be described later, the weight material 9 is deposited on the movable plate 722 by a sputtering method through a plurality of weight material passing pores 332a to 332c.

  As shown in FIG. 5, the fixed electrode 71 has a protruding portion 711 protruding (exposed) from the movable plate 722 to the upper side, the lower side, and the right side in FIG. 5. Then, in plan view of the semiconductor substrate 100, a plurality of weight material passage pores 332a to 332c are formed so as to avoid the boundary portion between the movable plate 722 and the protruding portion 711 (that is, the edge portion of the movable plate 722). Has been. Thereby, the weight material 9 can be reliably deposited on the movable plate 722 and can be prevented from being deposited at a position where the fixed electrode 71 and the movable plate 722 are short-circuited or fixed. Therefore, it is possible to prevent the fixed electrode 71 and the movable plate 722 from being fixed or electrically connected by the weight material 9. Therefore, it is possible to manufacture the electronic device 1 that can exhibit desired frequency characteristics and is excellent in reliability.

  The separation distance D between the adjacent pores 332 varies depending on the shape and size of the movable plate 722, the shape and size of the pore 332, and the like, but is preferably about 1 μm to 20 μm. As a result, an appropriate number of pores 332 can be arranged and formed above the movable plate 722 in the plan view of the semiconductor substrate 100 (FIG. 5). Therefore, when the weight material 9 is deposited on the movable plate 722 by the sputtering method, the weight material deposition amount per unit time with respect to the movable plate 722 becomes an appropriate amount (not too much but not too small), and the natural vibration of the movable plate 722 is obtained. The number can be adjusted with high accuracy and efficiency (rapidly).

  The opening shape (cross-sectional shape) of each pore 332 is substantially circular. The opening diameter of each pore 332 is not particularly limited, but is preferably about 0.5 μm to 2 μm. By setting the opening diameter of each pore 332 in the above range, when the weight material 9 is deposited on the movable plate 722 by the sputtering method, the weight material 9 is clogged in each of the weight material passing pores 332a to 332c. Can be prevented. Further, the amount of the weight material 9 that passes through each of the weight material passing pores 332a to 332c per unit time becomes an appropriate amount (not too much but not too small), and the natural frequency of the movable plate 722 is adjusted with high accuracy. And can be performed efficiently.

Next, a method for adjusting the natural frequency of the movable plate 722 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 to 332c. Thus, by covering the pores 332 other than the weight material passing pores 332 a to 332 c with the mask 400, it is possible to reliably prevent the weight material 9 from being deposited on a portion other than the movable plate 722. Therefore, it is possible to prevent the fixed electrode 71, the movable plate 722, and other wirings exposed in the cavity 5 from being electrically connected (short-circuited) via the weight material.

  Next, as shown in FIG. 6B, the weight material 9 is deposited (film formation) through the weight material passing pores 332a to 332c by sputtering. As a result, the mass and moment of inertia of the movable plate 722 can be increased and the natural frequency of the movable plate 722 can be lowered. Therefore, the weight material 9 is deposited until the natural frequency of the movable plate 722 reaches a predetermined value. Continue. In this way, the natural frequency of the movable plate 722 can be adjusted to a predetermined value.

  The step of depositing the weight material 9 on the movable plate 722 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 movable plate 722 every time between them, whereby the natural frequency of the movable plate 722 can be gradually adjusted to a predetermined value. . Therefore, the natural frequency of the movable plate 722 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 (a natural frequency change amount per unit time) between the sputtering processing time and the natural frequency change of the movable plate 722 is obtained in advance through experiments or the like, and is measured in the natural frequency measurement step. The sputtering processing time required to adjust the natural frequency of the movable plate 722 to the predetermined value is obtained from the deviation between the natural frequency of the movable plate 722 and the predetermined value, and the sputtering process is performed according to the determined processing time. You may go. In this case, the natural frequency of the movable plate 722 can be adjusted to a predetermined value by performing the process of depositing the weight material 9 on the movable plate 722 only once. Therefore, the natural frequency of the movable plate 722 can be adjusted quickly.

Further, the method of depositing the weight material 9 on the movable plate 722 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 (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, W, Ti, Cu, 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.
7 and 8 are cross-sectional views illustrating a method for manufacturing an electronic device according to the second embodiment of the present invention.
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 the present embodiment, the natural frequency adjustment process includes a temporary adjustment process and a main adjustment process.
In the temporary adjustment step, when there is a large difference (difference) between the natural frequency of the movable plate 722 measured in the natural frequency measurement step and a predetermined value, the natural frequency of the movable plate 722 is efficiently reduced to a predetermined value. It is a process for reducing well. 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 process is a process of finishing the temporary adjustment process and reducing the natural frequency of the movable plate 722 near the predetermined value to a predetermined value with high accuracy. 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 movable plate 722 is adjusted with high accuracy and efficiency (reduction in processing time and reduction in the amount of weight material used) ( Can be 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 332c. Next, as shown in FIG. 7B, the weight material 9 is deposited on the movable plate 722 through the weight material passing pores 332 c. Here, since the weight material passing pores 332c are located closer to the free end of the movable plate 722 than the weight material passing pores 332a and 332b, the weight material passing pores 332a and 332b are interposed. Compared with the case where the weight material 9 is deposited, the natural frequency of the movable plate 722 can be efficiently reduced with a small amount of deposition. This is because even if the mass of the movable plate 722 increases by the same amount due to the weight material 9, the moment of inertia of the movable plate 722 is greater when the weight material 9 is located on the free end side than when it is located on the fixed end side. This is because the increase amount is large.
By performing such a temporary adjustment step once or a plurality of times as in the first embodiment described above, the natural frequency of the movable plate 722 is set near a predetermined value.

[Main adjustment process]
In this step, first, as shown in FIG. 8A, a mask 420 is disposed so as to cover the pores 332 other than the weight material passing pores 332a. Next, as shown in FIG. 8B, the weight material 9 is deposited on the movable plate 722 through the weight material passing pores 332 a. Here, since the weight material passing pores 332a are located closer to the fixed end of the movable plate 722 than the weight material passing pores 332b and 332c, the weight material passing pores 332b and 332c are interposed therebetween. Compared with the case where the weight material 9 is deposited, the natural frequency of the movable plate 722 can be reduced more minutely. As described above, even if the mass of the movable plate 722 is increased by the same amount due to the weight material 9, the movable plate 722 is located on the fixed end side rather than the movable plate 722 on the free end side. This is because the increase in the inertia moment of 722 is small.

By performing this adjustment process once or a plurality of times as in the first embodiment described above, the natural frequency of the movable plate 722 is adjusted to a predetermined value.
As described above, in the natural frequency adjustment process of the present embodiment, the provisional adjustment process in which importance is placed on speed performance and reduction in the usage amount of the weight material 9 and the main adjustment process in which importance is placed on accuracy are provided, that is, movable. Since the weight material 9 is selectively deposited on a plurality of regions having different separation distances from the connecting portion 723 on the plate 722, the natural frequency of the movable plate 722 can be adjusted with high accuracy and efficiency. it can.

Further, since the weight material passing pores 332a to 332c are formed so as to have different distances from the connecting portion 723 in plan view of the semiconductor substrate 100, the weight material passing pores 332a to 332c are formed. The temporary adjustment step and the main adjustment step as described above can be performed only by selecting the weight material passing pores to be closed (the weight material passing pores to be opened) from among them. Thereby, the natural frequency of the movable plate 722 can be adjusted more easily.
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. 9 is a cross-sectional view illustrating a method for manufacturing an electronic device according to a third embodiment of the present invention.
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.
In the present embodiment, a first weight material 91 and a second weight material 92 having a density lower than that of the first weight material 91 are used as the weight material 9 deposited on the movable plate 722. For example, the density value of the Ti, W and AL are, ^{respectively, 4507kg / m 3, 19250kg / m} 3 and 2700 kg / ^{m 3,} in the case of using W as the first weight material 91, second weight It is effective to use AL or Ti as the material 92.

  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 movable plate 722 when there is a large difference between the natural frequency of the movable plate 722 measured in the natural frequency measurement step and a predetermined value. This is a process for efficiently reducing the number to near 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 reducing the natural frequency of the movable plate 722 near the predetermined value to the predetermined value with high accuracy using the second weight material 92. is there. 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 movable plate 722 is adjusted with high accuracy and efficiency (reduction of 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. 9A, a mask 430 is disposed so as to cover the pores 332 other than the weight material passing pores 332a to 332c. Next, as shown in FIG. 9B, a first weight material 91 is deposited on the movable plate 722 via the weight material passing pores 332 a to 332 c. Since the first weight material 91 has a density higher than that of the second weight material 92, the natural frequency of the movable plate 722 can be efficiently reduced with a smaller amount of deposition than when the second weight material 92 is deposited. Can be reduced. By performing such a temporary adjustment step once or a plurality of times as in the first embodiment described above, the natural frequency of the movable plate 722 is set near a predetermined value.

[Main adjustment process]
In this step, as shown in FIG. 9C, the second weight material 92 is deposited on the movable plate 722 via the weight material passing pores 332a to 332c. Since the second weight material 92 is smaller than the density of the first weight material 91, the natural frequency of the movable plate 722 is reduced more minutely than in the temporary adjustment process in which the first weight material 91 is deposited. Can be made. By performing this adjustment process once or a plurality of times as in the first embodiment described above, the natural frequency of the movable plate 722 is adjusted to a predetermined value.

As described above, in the natural frequency adjustment process of the present embodiment, the weight material selected from a plurality of types of weight materials having different densities is deposited on the movable plate 722. Therefore, the movable plate 722 can be efficiently and efficiently used. The natural frequency can be adjusted.
In this embodiment, two types of weight materials 91 and 92 having different densities 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 third embodiment as described above, the same effect as that of the first embodiment can be exhibited.

<Fourth embodiment>
Next, a fourth embodiment of the electronic device manufacturing method of the present invention will be described.
10 and 11 are cross-sectional views illustrating a method for manufacturing an electronic device according to the fourth embodiment of the present invention.
Hereinafter, a method for manufacturing an electronic device according to the fourth embodiment will be described focusing on differences from the above-described embodiments, and description of similar matters will be omitted.

The method for manufacturing an electronic device according to the fourth 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 the present embodiment, a first weight material 91 and a second weight material 92 having a density lower than that of the first weight material 91 are used as the weight material 9 deposited on the movable plate 722.

  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 movable plate 722 when there is a large difference between the natural frequency of the movable plate 722 measured in the natural frequency measurement step and a predetermined value. This is a process for efficiently reducing the number to near 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 reducing the natural frequency of the movable plate 722 near the predetermined value to the predetermined value with high accuracy using the second weight material 92. is there. 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 movable plate 722 is adjusted with high accuracy and efficiency (reduction of 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. 10A, a mask 440 is disposed so as to cover the pores 332 other than the weight material passing pores 332c. Next, as shown in FIG. 10B, a first weight material 91 is deposited on the movable plate 722 through the weight material passing pores 332c. Thereby, compared with the case where the first weight material 91 is deposited on the movable plate 722 via the weight material passing pores 332a and 332b, the natural frequency of the movable plate 722 can be efficiently reduced with a small amount of deposition. Can be reduced. Further, since the first weight material 91 has a density higher than that of the second weight material 92, the natural vibration of the movable plate 722 can be efficiently performed with a small amount of deposition as compared with the case where the second weight material is deposited. The number can be reduced. By performing such a temporary adjustment step once or a plurality of times as in the first embodiment described above, the natural frequency of the movable plate 722 is set near a predetermined value.

[Main adjustment process]
In this step, first, as shown in FIG. 11A, a mask 450 is disposed so as to cover the pores 332 other than the weight material passing pores 332a. Next, as shown in FIG. 11B, a second weight material 92 is deposited on the movable plate 722 through the weight material passing pores 332a. As a result, the natural frequency of the movable plate 722 can be reduced more minutely compared to the case where the second weight material 92 is deposited on the movable plate 722 via the weight material passing pores 332b and 332c. it can. In addition, since the second weight material 92 is smaller than the density of the first weight material 91, the natural frequency of the movable plate 722 is smaller than that of the temporary adjustment process in which the first weight material 91 is deposited. Can be reduced. By performing this adjustment process once or a plurality of times as in the first embodiment described above, the natural frequency of the movable plate 722 is adjusted to a predetermined value.

As described above, in the natural frequency adjustment process of the present embodiment, the movable plate 722 has a smaller weight material among the plurality of types of weight materials 9 (the first weight material 91 and the second weight material 92). Since it is configured to accumulate in the upper fixed end side (connecting portion 723 side) region, the natural frequency of the movable plate 722 can be adjusted with high accuracy and efficiency.
In this embodiment, two types of weight materials 91 and 92 having different densities 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 fourth 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.

  DESCRIPTION OF SYMBOLS 1 ... Electronic device 100 ... Semiconductor substrate 110 ... Silicon oxide film 120 ... Silicon nitride film 200, 230 ... Polycrystalline silicon film 210, 240 ... Photoresist film 220 ... Sacrificial layer 300, 320 ... Interlayer Insulating films 301 and 321... Openings 310 and 330... Wiring layer 331 .. Covering layer 332... Fine pores 332 a to 332 c. , 410, 420, 430, 440, 450... Mask 5... Cavity 6 .. substrate 61... Semiconductor substrate 62 .. insulating film 63... Silicon nitride film 7. Protruding part 72 ... Movable electrode 721 ... Support part 722 ... Movable plate 723 ... Connecting part 8 ... Element surrounding structure 81, 83 ... Interlayer insulation Films 82 and 84 .. Wiring layer 841... Cover layer 85... Surface protective film 86... Sealing layer 9... Weight material 91... First weight material 92.

Claims (11)

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, and a movable electrode having a movable portion disposed opposite to the fixed electrode with a gap between the fixed electrode, and the element surrounding structure has a plurality of openings communicating with the cavity portion. A pre-adjustment electronic device preparation step of preparing a pre-adjustment electronic device having a coating layer;
A natural frequency measuring step for measuring the natural frequency of the movable part;
Based on the measurement result in the natural frequency measurement step, the natural frequency of the movable part is adjusted by depositing a weight material on the movable part of the functional element through the opening of the covering layer. The natural frequency adjustment process to
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 In a method for manufacturing an electronic device, comprising: a fixed electrode provided on the upper surface; and a movable electrode provided with a movable portion disposed opposite to the fixed electrode with a gap therebetween.
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 movable part;
Based on the measurement result in the natural frequency measurement step, the natural frequency of the movable part is adjusted by depositing a weight material on the movable part of the functional element through the opening of the covering layer. The natural frequency adjustment process to
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 movable portion is higher than a predetermined value.   4. The weight material can be selectively deposited in a plurality of regions having different distances from the connecting portion on the movable portion in the natural frequency adjusting step. 5. Method for manufacturing the electronic device.   5. The natural frequency adjustment step of closing a part of the plurality of openings and depositing the weight material on the movable part through the openings that are not closed. The manufacturing method of the electronic device in any one. The plurality of openings include a plurality of weight material passage openings that are included in the movable part and have different separation distances from the coupling part in a plan view of the substrate,
In the natural frequency adjusting step, at least one of the plurality of weight material passage openings is closed, and the weight material passage opening is closed on the movable portion via the other weight material passage opening. 6. The method of manufacturing an electronic device according to claim 1, wherein a weight material is deposited.   The electronic device manufacturing method 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 densities is deposited on the movable portion. Method.   The electronic device manufacturing method according to claim 7, wherein in the natural frequency adjusting step, a weight material having a smaller density among the plurality of types of weight materials is deposited in a region of the movable portion on the connection portion side. The fixed electrode has a protruding portion protruding from the movable portion in a plan view of the substrate,
9. The electronic device according to claim 1, wherein each of the plurality of apertures is formed so as to avoid a boundary portion between the movable portion and the protruding portion in a plan view of the substrate. 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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