JP2018151309A - Method for manufacturing pressure sensor, pressure sensor, pressure sensor module, electronic apparatus, and mobile body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pressure sensor, a pressure sensor, a pressure sensor module, an electronic apparatus, and a mobile body which can exhibit an excellent accuracy of pressure detection.SOLUTION: The method for manufacturing a pressure sensor includes the steps of: preparing a substrate with a diaphragm formation region; arranging, on the substrate, a guard ring, a sacrificial layer, and a lid part, the guard ring surrounding the diaphragm formation region, the sacrificial layer being in the guard ring, and the lid part facing the substrate across the sacrificial layer and having a lid part penetration hole; removing the sacrificial layer through the lid part penetration hole; arranging a first penetration hole overlapping with the lid part in the lid part and arranging a first sealing layer overlapping with the guard ring and having a second penetration hole; removing the lid part and the guard ring through the first and second penetration holes; arranging a second sealing layer sealing the first and second penetration holes on the first sealing layer; and forming a diaphragm in the diaphragm formation region.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a pressure sensor manufacturing method, a pressure sensor, a pressure sensor module, an electronic device, and a moving body.

  Conventionally, for example, a configuration described in Patent Document 1 is known as a pressure sensor. The pressure sensor of Patent Document 1 includes a substrate including a diaphragm that is bent and deformed by receiving pressure, a piezoresistive element formed on the diaphragm, and a pressure reference chamber disposed on the diaphragm, and is based on the bending of the diaphragm. The pressure is detected by utilizing the change in the resistance value of the piezoresistive element.

Japanese Patent Laying-Open No. 2015-175833

  However, in the pressure sensor of Patent Document 1, a guard ring (wiring portion) that forms a side wall portion of the pressure reference chamber, a covering layer that forms a ceiling portion of the pressure reference chamber, and a sealing layer that seals a through hole of the covering layer However, each of them is made of a metal material such as aluminum (a material having a higher coefficient of thermal expansion than materials of other portions). Therefore, due to these expansions, the internal stress of the diaphragm changes depending on the environmental temperature. As a result, even if the same pressure is applied, the measured value varies depending on the environmental temperature, and the pressure detection accuracy may be reduced.

  An object of the present invention is to provide a pressure sensor manufacturing method, a pressure sensor, a pressure sensor module, an electronic device, and a moving body that can exhibit excellent pressure detection accuracy.

  Such an object is achieved by the present invention described below.

The method of manufacturing a pressure sensor of the present invention includes a step of preparing a substrate having a diaphragm forming region,
On one surface side of the substrate, a guard ring surrounding the diaphragm forming region in plan view of the substrate, a sacrificial layer located in a space inside the guard ring, and facing the substrate through the sacrificial layer A step of disposing a lid portion having a lid portion through-hole facing the sacrificial layer;
Removing the sacrificial layer through the lid through hole;
A first through hole disposed on the opposite side of the lid portion from the substrate so as to overlap the lid portion in plan view of the substrate and a first through hole disposed so as to overlap the guard ring in plan view of the substrate. Disposing a first sealing layer having two through holes;
Removing the lid and the guard ring through the first through hole and the second through hole;
Disposing a second sealing layer for sealing the first through hole and the second through hole on the opposite side of the first sealing layer from the substrate;
Forming a diaphragm that bends and deforms by receiving pressure in the diaphragm forming region.
As described above, by removing the lid and the guard ring, it is possible to reduce the change due to the environmental temperature of the internal stress applied to the diaphragm. Therefore, a pressure sensor that can exhibit excellent pressure detection accuracy is obtained.

The method of manufacturing a pressure sensor of the present invention includes a step of preparing a substrate having a diaphragm forming region,
Placing a sacrificial layer on one surface side of the substrate so as to overlap the diaphragm forming region in plan view of the substrate;
A first region facing the substrate through the sacrificial layer and overlapping the diaphragm forming region in a plan view of the substrate; and a second region positioned outside the diaphragm forming region; Arranging a lid portion having a first lid portion through hole facing the sacrificial layer;
Removing the sacrificial layer through the first lid through hole;
A first through hole disposed on the opposite side of the lid portion from the substrate so as to overlap the first region in a plan view of the substrate and a second through region disposed in a plan view of the substrate. Disposing a first sealing layer having a second through hole,
Removing the lid through the first through hole and the second through hole;
Disposing a second sealing layer for sealing the first through hole and the second through hole on the opposite side of the first sealing layer from the substrate;
Forming a diaphragm that bends and deforms by receiving pressure in the diaphragm forming region.
In this way, by removing the lid, it is possible to reduce the change due to the environmental temperature of the internal stress applied to the diaphragm. Therefore, a pressure sensor that can exhibit excellent pressure detection accuracy is obtained.

In the pressure sensor manufacturing method of the present invention, the first sealing layer contains silicon,
The second sealing layer preferably contains silicon oxide.
Thereby, the first sealing layer and the second sealing layer can be easily formed by a semiconductor process.

In the pressure sensor manufacturing method of the present invention, after the step of disposing the second sealing layer,
It is preferable to include a step of disposing a third sealing layer on the opposite side of the second sealing layer from the substrate.
Thereby, even if the first and second through holes are not sealed by the second sealing layer, the first and second through holes can be more reliably sealed by the third sealing layer. .

In the pressure sensor manufacturing method of the present invention, it is preferable that the third sealing layer contains silicon.
Thereby, the third sealing layer can be easily formed by a semiconductor process.

In the pressure sensor manufacturing method of the present invention, it is preferable that the second sealing layer is blocked from the outside by the first sealing layer and the third sealing layer.
Thereby, a 2nd sealing layer can be protected from a water | moisture content etc., and the change of the internal stress of the sealing layer resulting from environmental humidity can be suppressed.

The pressure sensor of the present invention includes a substrate including a diaphragm that is bent and deformed by pressure reception;
A side wall portion disposed on one surface side of the substrate and surrounding the diaphragm in a plan view of the substrate;
A sealing layer that is disposed to face the diaphragm through a space surrounded by the side wall, and seals the space;
The sealing layer includes a first sealing layer having a through hole communicating with the space, and a second seal that is located on the opposite side of the diaphragm with respect to the first sealing layer and seals the through hole. A stop layer,
The through hole has a first through hole located inside the diaphragm and a second through hole located outside the diaphragm in plan view of the substrate.
Thereby, the change by the environmental temperature of the internal stress added to a diaphragm can be suppressed. Therefore, the pressure sensor can exhibit excellent pressure detection accuracy.

The pressure sensor module of the present invention includes the pressure sensor of the present invention,
And a package housing the pressure sensor.
Thereby, the effect of a pressure sensor can be enjoyed and a highly reliable pressure sensor module can be obtained.

The electronic device of the present invention includes the pressure sensor of the present invention.
Thereby, the effect of a pressure sensor can be enjoyed and a highly reliable electronic device can be obtained.

The moving body of the present invention has the pressure sensor of the present invention.
Thereby, the effect of a pressure sensor can be enjoyed and a reliable mobile body is obtained.

It is sectional drawing which shows the pressure sensor which concerns on 1st Embodiment of this invention. It is a top view which shows the sensor part which the pressure sensor shown in FIG. 1 has. It is a circuit diagram which shows the bridge circuit containing the sensor part shown in FIG. It is an expanded sectional view of the sealing layer which the pressure sensor shown in FIG. 1 has. It is a flowchart which shows the manufacturing process of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor which concerns on 2nd Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the pressure sensor which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the manufacturing process of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing for demonstrating the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing which shows the pressure sensor module which concerns on 4th Embodiment of this invention. It is a top view of the support substrate which the pressure sensor module shown in FIG. 26 has. It is a perspective view which shows the altimeter as an electronic device which concerns on 5th Embodiment of this invention. It is a front view which shows the navigation system as an electronic device which concerns on 6th Embodiment of this invention. It is a perspective view which shows the motor vehicle as a moving body which concerns on 7th Embodiment of this invention.

  Hereinafter, a pressure sensor manufacturing method, a pressure sensor, a pressure sensor module, an electronic device, and a moving body of the present invention will be described in detail based on embodiments shown in the accompanying drawings.

<First Embodiment>
First, the pressure sensor and the manufacturing method thereof according to the first embodiment of the present invention will be described.

  FIG. 1 is a cross-sectional view showing a pressure sensor according to a first embodiment of the present invention. FIG. 2 is a plan view showing a sensor unit included in the pressure sensor shown in FIG. FIG. 3 is a circuit diagram showing a bridge circuit including the sensor unit shown in FIG. FIG. 4 is an enlarged cross-sectional view of a sealing layer included in the pressure sensor shown in FIG. FIG. 5 is a flowchart showing manufacturing steps of the pressure sensor shown in FIG. 6 to 16 are cross-sectional views for explaining a method of manufacturing the pressure sensor shown in FIG. In the following description, the upper side in FIGS. 1, 4 and 6 to 16 is also referred to as “upper”, and the lower side is also referred to as “lower”.

  As shown in FIG. 1, the pressure sensor 1 includes a substrate 2 having a diaphragm 25 that is bent and deformed by receiving pressure, a pressure reference chamber S (cavity portion) disposed on the upper surface side of the diaphragm 25, and a pressure reference chamber together with the substrate 2. It has a surrounding structure 4 that forms S, and a sensor unit 5 that is disposed on the diaphragm 25.

  As shown in FIG. 1, the substrate 2 includes a first layer 21 made of silicon, a third layer 23 arranged on the upper side of the first layer 21, made of silicon, a first layer 21, and a third layer. It is comprised by the SOI substrate which has the 2nd layer 22 arrange | positioned between the layers 23 and comprised with the silicon oxide. That is, the substrate 2 includes silicon (Si). Thereby, it becomes the board | substrate 2 which is easy to handle on manufacture and can exhibit the outstanding processing dimensional accuracy.

  However, the substrate 2 is not limited to the SOI substrate, and for example, a single layer silicon substrate can be used. The substrate 2 may be a substrate (semiconductor substrate) made of a semiconductor material other than silicon, for example, germanium, gallium arsenide, phosphorus gallium arsenide, gallium nitride, silicon carbide, or the like.

  As shown in FIG. 1, the substrate 2 is provided with a diaphragm 25 that is thinner than the surrounding portion and bends and deforms by receiving pressure. The substrate 2 is formed with a bottomed recess 24 that opens downward, and a portion where the substrate 2 is thinned by the recess 24 is a diaphragm 25. The lower surface of the diaphragm 25 is a pressure receiving surface 251 that receives pressure. In the present embodiment, the planar view shape of the diaphragm 25 is substantially square, but the planar view shape of the diaphragm 25 is not particularly limited, and for example, a polygon such as a triangle or a pentagon, a circle, an ellipse, or the like. It may be. Further, in the case of a planar view shape having corners, the corners may be chamfered.

  Here, in this embodiment, the recess 24 is formed by dry etching using a silicon deep etching apparatus. Specifically, the steps of isotropic etching, protective film formation, and anisotropic etching are repeated from the lower surface side of the substrate 2 to dig the first layer 21 to form the recess 24. When this process is repeated and the etching reaches the second layer 22, the second layer 22 serves as an etching stopper and the etching is finished, and the recess 24 is obtained. According to such a forming method, since the inner wall side surface of the recess 24 is substantially perpendicular to the main surface of the substrate 2, the opening area of the recess 24 can be reduced. Therefore, a decrease in mechanical strength of the substrate 2 can be suppressed, and an increase in the size of the pressure sensor 1 can be suppressed.

  However, the method for forming the recess 24 is not limited to the above method, and may be formed by wet etching, for example. In the present embodiment, the second layer 22 remains on the lower surface side of the diaphragm 25. However, the second layer 22 may be removed. That is, the diaphragm 25 may be constituted by a single layer of the third layer 23. Thereby, the diaphragm 25 can be made thinner, and the diaphragm 25 which is more easily bent and deformed is obtained. Further, the recess 24 may be formed up to the middle of the first layer 21.

  The thickness of the diaphragm 25 is not particularly limited, and varies depending on the size of the diaphragm 25. For example, when the width of the diaphragm 25 is 100 μm or more and 300 μm or less, the thickness is preferably 1 μm or more and 10 μm or less. More preferably, it is 1 μm or more and 3 μm or less. With such a thickness, the diaphragm 25 can be obtained that is sufficiently thin and that is easily bent and deformed by receiving pressure while maintaining sufficient mechanical strength.

  Such a diaphragm 25 is provided with a sensor unit 5 that detects a pressure acting on the diaphragm 25. As shown in FIG. 2, the sensor unit 5 includes four piezoresistive elements 51, 52, 53, 54 provided on the diaphragm 25. The piezoresistive elements 51, 52, 53, and 54 are electrically connected to each other via a wiring 55, and constitute a bridge circuit 50 (Wheatstone bridge circuit) shown in FIG. The bridge circuit 50 is connected to a drive circuit that supplies (applies) a drive voltage AVDC. The bridge circuit 50 outputs a detection signal (voltage) corresponding to a change in resistance value of the piezoresistive elements 51, 52, 53, and 54 based on the deflection of the diaphragm 25. Therefore, the pressure received by the diaphragm 25 can be detected based on the output detection signal.

  In particular, the piezoresistive elements 51, 52, 53, and 54 are disposed on the outer edge portion of the diaphragm 25. When the diaphragm 25 is bent and deformed by pressure reception, a large stress is particularly applied to the outer edge portion of the diaphragm 25. Therefore, by arranging the piezoresistive elements 51, 52, 53, and 54 on the outer edge portion of the diaphragm 25, the detection signal described above is provided. The sensitivity of pressure detection is improved. The arrangement of the piezoresistive elements 51, 52, 53, and 54 is not particularly limited. For example, the piezoresistive elements 51, 52, 53, and 54 may be arranged across the outer edge of the diaphragm 25, or the diaphragm You may arrange | position in the center part of 25.

  The piezoresistive elements 51, 52, 53, 54 are configured, for example, by doping (diffusing or implanting) impurities such as phosphorus and boron into the third layer 23 of the substrate 2. The wiring 55 is configured by doping (diffusing or injecting) impurities such as phosphorus and boron into the third layer 23 of the substrate 2 at a higher concentration than the piezoresistive elements 51, 52, 53, and 54, for example. ing.

  The configuration of the sensor unit 5 is not particularly limited as long as the pressure received by the diaphragm 25 can be detected. For example, at least one piezoresistive element that does not constitute the bridge circuit 50 may be arranged on the diaphragm 25. Moreover, as a sensor part, you may use the electrostatic capacitance type which detects a pressure based on the change of an electrostatic capacitance other than a piezoresistive type like this embodiment.

As shown in FIG. 1, on the upper surface of the substrate 2, a first insulating film 31 made of a silicon oxide film (SiO ₂ film) and a second insulating film made of a silicon nitride film (SiN film) are formed. 32 are formed. The first insulating film 31 can reduce the interface state of the piezoresistive elements 51, 52, 53, and 54 and suppress the generation of noise. Further, the sensor part 5 can be protected from moisture and dust by the second insulating film 32 (silicon nitride film).

  The constituent material of the first insulating film 31 and the second insulating film 32 is not particularly limited as long as the above-described purpose can be exhibited. Further, instead of the first insulating film 31 and the second insulating film 32, for example, an insulating film made of a silicon oxynitride film (SiNO film) may be disposed. According to the silicon oxynitride film, the functions of both the first insulating film 31 and the second insulating film 32 described above can be exhibited. The first insulating film 31 and the second insulating film 32 may each have a frame shape so as not to overlap the diaphragm 25. Further, at least one of the first insulating film 31 and the second insulating film 32 may be omitted.

  Further, a third insulating film 33 made of a polysilicon film (p-Si film) is formed on the second insulating film 32. The third insulating film 33 has a frame shape surrounding the periphery of the diaphragm 25 so as not to overlap with the diaphragm 25. Note that the third insulating film 33 may be omitted.

  Further, as shown in FIG. 1, a pressure reference chamber S is provided on the upper side of the diaphragm 25. The pressure reference chamber S is formed by being surrounded by the substrate 2 and the surrounding structure 4. The pressure reference chamber S is a sealed space, and the pressure in the pressure reference chamber S becomes a reference value of the pressure detected by the pressure sensor 1. In particular, the pressure reference chamber S is preferably in a vacuum state (for example, 10 Pa or less). As a result, the pressure sensor 1 can be used as an “absolute pressure sensor” that detects pressure with reference to a vacuum, and the pressure sensor 1 is highly convenient. However, the pressure reference chamber S may not be in a vacuum state as long as it is maintained at a constant pressure.

  The surrounding structure 4 forms a pressure reference chamber S between itself and the substrate 2. As shown in FIG. 1, the surrounding structure 4 includes an interlayer insulating film 41 disposed on the substrate 2, a wiring layer 42 disposed on the interlayer insulating film 41, and the wiring layer 42 and the interlayer insulating film 41. The interlayer insulating film 43 disposed, the wiring layer 44 disposed on the interlayer insulating film 43, the surface protective film 45 disposed on the wiring layer 44 and the interlayer insulating film 43, and the surface protective film 45. And a terminal 47 disposed on the surface protective film 45.

  In such a surrounding structure 4, a frame-like side wall portion 40 surrounding the diaphragm 25 in plan view of the substrate 2 is mainly configured by the interlayer insulating films 41 and 43. A pressure reference chamber S is formed inside the side wall 40. The sealing layer 46 is disposed to face the diaphragm 25 with the pressure reference chamber S interposed therebetween, and seals the pressure reference chamber S.

The interlayer insulating films 41 and 43 each have a frame shape and are disposed so as to surround the diaphragm 25 in plan view. The interlayer insulating films 41 and 43 are not particularly limited. For example, an insulating film such as a silicon oxide film (SiO ₂ film) can be used. The wiring layer 42 includes a wiring portion 429 that is electrically connected to the wiring 55 of the sensor unit 5. In addition, the wiring layer 44 includes a wiring portion 449 that is electrically connected to the wiring portion 429. Although these wiring layers 42 and 44 are not specifically limited, For example, metal films, such as an aluminum film, can be used.

  The surface protective film 45 has a function of protecting the surrounding structure 4 from moisture, gas, dust, scratches, and the like. The surface protective film 45 is disposed on the interlayer insulating film 43 and the wiring layer 44. In addition, a plurality of terminals 47 that are electrically connected to the sensor unit 5 via the wiring units 429 and 449 are provided on the surface protective film 45. The surface protective film 45 is not particularly limited, and for example, a silicon oxide film, a silicon nitride film, a polyimide film, an epoxy resin film, or the like can be used.

  As shown in FIG. 1, the sealing layer 46 is located on the ceiling of the pressure reference chamber S and seals the pressure reference chamber S. The sealing layer 46 includes a first sealing layer 461 whose lower surface faces the pressure reference chamber S, a second sealing layer 462 laminated on the upper surface of the first sealing layer 461, and an upper surface of the second sealing layer 462. And a third sealing layer 463 laminated on the substrate. By making the sealing layer 46 have a laminated structure, the pressure reference chamber S can be hermetically sealed more reliably. The configuration of the sealing layer 46 is not particularly limited, and for example, between the first sealing layer 461 and the second sealing layer 462 or between the second sealing layer 462 and the third sealing layer 463. Another layer may be interposed between the layers to form a laminated structure of four or more layers. Further, the third sealing layer 463 may be omitted.

The first sealing layer 461 is configured to include silicon (Si), and in particular, in the present embodiment, is configured from silicon (Si). The second sealing layer 462 includes silicon oxide (SiO ₂ ). In particular, in the present embodiment, the second sealing layer 462 includes silicon oxide (SiO ₂ ). Further, the third sealing layer 463 is configured to include silicon (Si), and in particular, in this embodiment, is configured from silicon (Si). As will be described later in the manufacturing method, the first sealing layer 461, the second sealing layer 462, and the third sealing layer 463 can be formed by various film forming methods such as a sputtering method and a CVD method, respectively. it can.

  As described above, since each of the layers 461, 462, and 463 includes silicon (Si), the sealing layer 46 can be easily formed by a semiconductor process. Further, the first sealing layer 461 and the third sealing layer 463 made of the same material (silicon) and the second sealing layer 462 made of a different material (silicon oxide) are sandwiched between them. The thermal expansion coefficient of the sealing layer 46 can be averaged in the thickness direction, and the bending of the sealing layer 46 in the out-of-plane direction during the thermal expansion can be suppressed.

  In particular, the contact between the sealing layer 46 and the diaphragm 25 can be suppressed by suppressing the downward bending of the sealing layer 46. If the sealing layer 46 comes into contact with the diaphragm 25, the bending deformation of the diaphragm 25 is hindered, and the pressure detection accuracy may be reduced. Therefore, as described above, the pressure having excellent pressure detection accuracy is achieved by suppressing the bending of the sealing layer 46 in the out-of-plane direction during thermal expansion and suppressing the contact between the sealing layer 46 and the diaphragm 25. It becomes sensor 1. Further, as described above, since the substrate 2 is composed of an SOI substrate, the difference in coefficient of thermal expansion between the substrate 2 and the sealing layer 46 facing each other through the pressure reference chamber S can be reduced. Therefore, the internal stress generated by thermal expansion can be kept small. Furthermore, the change due to the environmental temperature of the internal stress applied to the diaphragm 25 can be suppressed. Therefore, for example, it is possible to effectively suppress a decrease in detection accuracy such that the detected pressure varies depending on the environmental temperature even when receiving the same pressure.

  Note that the constituent materials of the first sealing layer 461, the second sealing layer 462, and the third sealing layer 463 are not particularly limited. For example, each of the first sealing layer 461 and the third sealing layer 463 may include a material other than silicon (Si) (for example, a material inevitably mixed in manufacturing) or other than silicon. You may be comprised with the material of. Similarly, the second sealing layer 462 may include a material other than silicon oxide (for example, a material inevitably mixed in manufacturing), or may be configured of a material other than silicon oxide. .

  Further, as shown in FIG. 1, the first sealing layer 461 has a plurality of through holes 464. The first sealing layer 461 includes a first region 461A that overlaps the diaphragm 25 in a plan view of the substrate 2, and a second region 461B that is located outside the first region 461A and does not overlap the diaphragm 25. ,have. In addition, the plurality of through holes 464 include at least one first through hole 465 disposed in the first region 461A and at least one second through hole 466 disposed in the second region 461B. . In the present embodiment, a plurality of first through holes 465 are arranged in a matrix (matrix), and a plurality of second through holes 466 are arranged along the outer periphery of the first region 461A. However, the number and arrangement of the first through holes 465 and the second through holes 466 are not particularly limited.

  As will be described in detail in a manufacturing method to be described later, the plurality of through holes 464 are holes for release etching for removing the guard ring GR and the lid portion 444 that exist until the middle of manufacturing. As in the present embodiment, the plurality of through holes 464 include the first through holes 465 and the second through holes 466, so that the through holes 464 can be arranged over a wide range of the first sealing layer 461, and Therefore, the guard ring GR and the cover 444 can be removed more smoothly and reliably.

  Further, by arranging the plurality of through holes 464, the first sealing layer 461 can be easily deformed in the surface direction, and for example, the internal stress of the pressure sensor 1 can be absorbed and relaxed by the deformation. Therefore, the internal stress of the pressure sensor 1 is reduced and the internal stress is difficult to be transmitted to the diaphragm 25. Therefore, the pressure sensor 1 can exhibit excellent pressure detection accuracy.

  A second sealing layer 462 is disposed on the first sealing layer 461, and each through hole 464 is blocked by the second sealing layer 462. Thereby, the pressure reference chamber S is sealed.

  Moreover, the cross-sectional shape of each through-hole 464 is substantially circular. However, the cross-sectional shape of each through hole 464 is not particularly limited, and may be, for example, a polygon such as a triangle or a quadrangle, an ellipse, or an irregular shape.

  Further, as shown in FIG. 4, the through hole 464 has a tapered shape in which the cross-sectional area (diameter) gradually decreases from the pressure reference chamber S side toward the second sealing layer 462 side. Thus, by making the through hole 464 tapered, it is possible to secure a sufficient space in the through hole 464 and make the through hole 464 easier to deform, and to open the upper side of the through hole 464. Can be made sufficiently small. Therefore, the opening on the upper end side of the through hole 464 can be more reliably closed by the second sealing layer 462 while making the first sealing layer 461 easier to deform in the surface direction. The shape of the through hole 464 is not particularly limited. For example, in the present embodiment, the through hole 464 has a tapered shape in the entire axial direction, but is not limited thereto, and at least a part of the axial direction may have a tapered shape as described above. . Further, the through-hole 464 may be a straight shape that is not tapered and does not substantially change the cross-sectional area.

  As shown in FIG. 4, the diameter Rmax (width) of the opening on the lower end side of the through hole 464 is not particularly limited, but is preferably 500 mm or more and 2500 mm or less, and more preferably 1000 mm or more and 2000 mm or less. . As a result, the space in the through-hole 464 can be more reliably secured and the first sealing layer 461 can be more easily deformed. In addition, the through hole 464 can be prevented from becoming excessively large. For example, the mechanical strength of the first sealing layer 461 is excessively decreased, or the mechanical strength of the first sealing layer 461 is reduced. In order to ensure strength, the first sealing layer 461 can be prevented from becoming excessively thick.

  The diameter Rmin (width) of the opening on the upper end side of the through hole 464 is not particularly limited, but is preferably, for example, 100 to 1000 mm, and more preferably 200 to 800 mm. Accordingly, the through hole having a diameter large enough to perform etching for removing the guard ring GR and the lid portion 444 and having a diameter that can be more reliably closed by the second sealing layer 462. Hole 464 is formed.

  Further, in the through hole 464, the rate of change of the cross-sectional area (diameter) gradually decreases from the pressure reference chamber S side toward the second sealing layer 462 side. That is, the through hole 464 has an inner peripheral surface that is inclined more upward. In particular, in the present embodiment, the inner peripheral surface of the upper end portion is in a substantially vertical state. Therefore, it can be said that the through hole 464 has a funnel-shaped internal space. With such a configuration, the diameter of the through hole 464 can be gradually reduced from the lower side toward the upper side, so that the diameter Rmin can be controlled with high accuracy. Therefore, it becomes easy to adjust the diameter Rmin to the target value. That is, the diameter Rmin becomes too small to make it difficult to etch away the guard ring GR and the lid 444, or the diameter Rmin becomes too large to be sealed with the second sealing layer 462. It is possible to suppress the trapping. Therefore, the guard ring GR and the lid portion 444 can be more reliably removed through the through hole 464, and the through hole 464 can be blocked by the second sealing layer 462. The shape of the through hole 464 is not particularly limited, and for example, the rate of change of the cross-sectional area (diameter) may be constant toward the upper side.

  As shown in FIGS. 1 and 4, the first sealing layer 461 has a frame shape (annular shape) surrounding the lower end side opening of each through hole 464, and has a frame shape protruding toward the pressure reference chamber S side. Part 467. Therefore, even if the sealing layer 46 bends toward the diaphragm 25 and the sealing layer 46 comes into contact with the diaphragm 25, the protruding portion 467 comes into contact with priority. Therefore, the contact area between the sealing layer 46 and the diaphragm 25 can be reduced as compared with the case where the protruding portion 467 is not provided, and the occurrence of “sticking” in which the sealing layer 46 is stuck to the diaphragm 25 while being stuck. Can be effectively suppressed.

  Further, as shown in FIG. 4, the thickness T1 of the first sealing layer 461 is larger than the thickness T2 of the second sealing layer 462 and the thickness T3 of the third sealing layer 463. Since the plurality of through holes 464 are arranged in the first sealing layer 461, the mechanical strength is likely to be lower than that of the other layers (the second sealing layer 462 and the third sealing layer 463). Therefore, the first sealing layer 461 can be provided with sufficient mechanical strength by satisfying the relationship of T1> T2 and T1> T3.

  Specifically, the thickness T1 of the first sealing layer 461 is not particularly limited, but is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 7 μm or less. Thereby, excessive thickness increase of the 1st sealing layer 461 can be prevented, giving sufficient mechanical strength to the 1st sealing layer 461. Further, the through holes 464 having the diameters Rmax and Rmin as described above can be easily formed.

  The second sealing layer 462 is stacked on the first sealing layer 461 as described above. The second sealing layer 462 is a layer mainly for sealing the plurality of through holes 464 provided in the first sealing layer 461. The thickness T2 of the second sealing layer 462 is not particularly limited, but is preferably 1 μm or more and 5 μm or less, and more preferably 1.5 μm or more and 2.5 μm or less. Thereby, the through-hole 464 can be more reliably sealed by the second sealing layer 462 while preventing the second sealing layer 462 from being excessively thickened.

  A third sealing layer 463 is laminated on the second sealing layer 462 as described above. The third sealing layer 463 is mainly formed by sandwiching the second sealing layer 462 made of a different material between the first sealing layer 461 and the same material at the time of thermal expansion of the sealing layer 46. It is a layer for suppressing the bending to the out-of-plane direction. Thereby, especially the downward bending of the sealing layer 46 can be suppressed, and the contact with the sealing layer 46 and the diaphragm 25 can be suppressed.

  Here, if the second sealing layer 462 is exposed to the outside, the second sealing layer 462 may absorb moisture, and the internal stress of the sealing layer 46 may change due to environmental humidity. Thus, when the internal stress of the sealing layer 46 changes due to the environmental humidity, the internal stress of the diaphragm 25 also changes accordingly. Therefore, even if the same pressure is received, the measured value varies depending on the environmental humidity, and the pressure detection accuracy of the pressure sensor 1 may be reduced.

  Therefore, in the present embodiment, the second sealing layer 462 is covered with the third sealing layer 463, and the second sealing layer 462 is hermetically sealed from the outside of the pressure sensor 1. That is, the second sealing layer 462 is surrounded by the third sealing layer 463 to prevent the second sealing layer 462 from being exposed to the outside of the pressure sensor 1. Thereby, the 2nd sealing layer 462 can be protected from moisture, and the change of the internal stress of the sealing layer 46 by environmental humidity can be controlled.

  In the present embodiment, the side surface of the second sealing layer 462 is covered with the third sealing layer 463, but is not limited thereto, and may be covered with the first sealing layer 461. It may be covered with both the first sealing layer 461 and the third sealing layer 463. Further, for example, when used in an environment that is not easily affected by humidity, such as when humidity is constant, the second sealing layer 462 is sealed by the first sealing layer 461 and the third sealing layer 463. For example, the side surface of the second sealing layer 462 may be exposed to the outside.

  The thickness T3 of the third sealing layer 463 is not particularly limited, but is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.3 μm or more and 1.0 μm or less. Thereby, the thickness balance with the 1st sealing layer 461 can be taken, and the bending to the out-of-plane direction at the time of the thermal expansion of the sealing layer 46 can be suppressed more effectively. Moreover, generation | occurrence | production of the pinhole to the 3rd sealing layer 463 can be suppressed, and the 2nd sealing layer 462 can be more effectively protected from a water | moisture content. In addition, excessive thickness increase of the third sealing layer 463 can be prevented.

  The pressure sensor 1 has been described above. As described above, such a pressure sensor 1 is disposed on the substrate 2 including the diaphragm 25 that is bent and deformed by receiving pressure, and on the upper surface (one surface) side of the substrate 2, and surrounds the diaphragm 25 in a plan view of the substrate 2. It has a side wall portion 40 and a sealing layer 46 that is disposed to face the diaphragm 25 through the pressure reference chamber S (space) surrounded by the side wall portion 40 and seals the pressure reference chamber S. . The sealing layer 46 has a first sealing layer 461 having a through hole 464 that communicates with the pressure reference chamber S, and is positioned on the upper side (opposite the diaphragm 25) with respect to the first sealing layer 461. And a second sealing layer 462 that seals the hole 464. The through hole 464 includes a first through hole 465 positioned inside the diaphragm 25 and a second through hole 466 positioned outside the diaphragm 25 in a plan view of the substrate 2.

  Thus, by arranging the through hole 464 in the first sealing layer 461, the sealing layer 46 is easily deformed in the surface direction. Therefore, the internal stress of the pressure sensor 1 is relaxed by the sealing layer 46, and the internal stress is difficult to be transmitted to the diaphragm 25. Therefore, a change due to the environmental temperature of the internal stress applied to the diaphragm 25 can be suppressed to be small, and a decrease in pressure detection accuracy of the pressure sensor 1 can be effectively suppressed. Thereby, the pressure sensor 1 can exhibit excellent pressure detection accuracy. Furthermore, in the manufacturing process, the guard ring GR and the lid portion 444 made of a metal material such as aluminum can be more reliably removed through the first through hole 465 and the second through hole 466. Thereby, the internal stress of the pressure sensor 1 can be further reduced. In addition, changes due to the degree of thermal expansion of the guard ring GR and the lid portion 444 (that is, the environmental temperature) of the internal stress applied to the diaphragm 25 can be suppressed to a small level, and a decrease in pressure detection accuracy of the pressure sensor 1 can be suppressed. Can do.

  Next, a manufacturing method of the pressure sensor 1 will be described. As shown in FIG. 5, the manufacturing method of the pressure sensor 1 includes a preparation step for preparing the substrate 2, a sensor portion placement step for placing the sensor portion 5 on the substrate 2, and a diaphragm forming region 250 on the upper surface of the substrate 2. A sacrificial layer disposing step of disposing a surrounding guard ring GR, a sacrificial layer G located in a space inside the guard ring GR, and a lid portion 444 facing the substrate 2 via the sacrificial layer G; A sacrificial layer removing step of removing the sacrificial layer G through the lid portion through-hole 445 having a first sealing layer arrangement step of arranging a first sealing layer 461 having a through-hole 464 on the upper surface of the lid portion 444; A guard ring / lid removing step for removing the guard ring GR and the lid 444 through the through hole 464, and a second sealing layer arranging step for arranging the second sealing layer 462 on the upper surface of the first sealing layer 461. And on the second sealing layer 462 And it includes a third sealing layer arrangement step of placing the third sealing layer 463, and a diaphragm forming step of forming a diaphragm 25 on the substrate 2, to.

[Preparation process]
First, as shown in FIG. 6, a substrate 2 made of an SOI substrate in which a first layer 21, a second layer 22, and a third layer 23 are stacked is prepared. At this stage, the diaphragm 25 is not formed in the diaphragm formation region 250 of the substrate 2. Next, for example, the surface of the third layer 23 is thermally oxidized to form the first insulating film 31 made of a silicon oxide film on the upper surface of the substrate 2.

[Sensor part placement process]
Next, as shown in FIG. 7, the sensor unit 5 is formed by injecting impurities such as phosphorus and boron into the upper surface of the substrate 2. Next, the second insulating film 32 and the third insulating film 33 are formed on the upper surface of the first insulating film 31 by using a sputtering method, a CVD method, or the like.

[Sacrificial layer placement process]
Next, as shown in FIG. 8, an interlayer insulating film 41, a wiring layer 42, an interlayer insulating film 43 and a wiring layer 44, a surface protective film 45, and a terminal 47 are formed on the substrate 2 by sputtering, CVD, or the like. It forms in a predetermined pattern in order. As a result, the substrate 2 is disposed so as to overlap with the diaphragm 25 in a plan view, the sacrificial layer G composed of the interlayer insulating films 41 and 43, the guard ring GR surrounding the sacrificial layer G, and the sacrificial layer G. And a cover portion 444 that covers the opening of the guard ring GR. The guard ring GR is composed of a frame-shaped wiring portion 421 formed from the wiring layer 42 and a frame-shaped wiring portion 441 formed from the wiring layer 44. In addition, a guard ring through hole 442 is formed in the wiring portion 441. The lid portion 444 is integrally formed with the wiring portion 441, and a lid portion through hole 445 facing the sacrificial layer G is formed. In the present embodiment, the interlayer insulating films 41 and 43 are made of silicon oxide, and the wiring layers 42 and 44 are made of aluminum.

  Here, the structure of the guard ring GR will be described in detail. As shown in FIG. 9, the wiring part 421 is provided through the interlayer insulating film 41, provided on the interlayer insulating film 41 and the concave contact part 421 a connected to the third insulating film 33. And a flange portion 421b disposed around the periphery of 421a. The flange portion 421b has an inner portion 421b ′ positioned on the sacrificial layer G side with respect to the contact portion 421a, and an outer portion 421b ″ positioned on the opposite side. A concave contact portion 441a provided through the insulating film 43 and connected to the contact portion 421a of the wiring portion 421; a flange portion 441b provided on the interlayer insulating film 43 and disposed around the contact portion 441a; The flange portion 441b has an inner portion 441b ′ located on the sacrificial layer G side with respect to the contact portion 441a and an outer portion 441b ″ located on the opposite side. A guard ring through hole 442 is formed in each of the contact part 441a, the inner part 441b ′, and the outer part 441b ″. However, the guard ring through hole 442 has the contact part 441a, the inner part 441b ′, and the outer part 441b. It suffices if it is formed in at least one of "".

[Sacrificial layer removal process]
Next, with the guard ring through hole 442 sealed with the resist R, the substrate 2 is exposed to an etching solution such as buffered hydrofluoric acid. As a result, as shown in FIG. 10, the sacrificial layer G is removed by etching through the lid through hole 445. At this time, the guard ring GR functions as an etching stopper.

[First sealing layer arranging step]
Next, after removing the resist R, as shown in FIG. 11, a first sealing layer 461 having a plurality of through holes 464 is formed on the upper surfaces of the lid 444, the guard ring GR, and the surface protective film 45. . The film formation method of the first sealing layer 461 is not particularly limited, and various film formation methods (vapor phase growth method) such as a sputtering method and a CVD method can be used, for example. Here, the plurality of through holes 464 include a first through hole 465 disposed so as to overlap with the lid portion 444 in a plan view of the substrate 2, a second through hole 466 disposed so as to overlap with the guard ring GR, have. Further, the first through hole 465 communicates with the lid portion through hole 445, and the second through hole 466 communicates with the guard ring through hole 442.

  This step will be described in detail. When the first sealing layer 461 is grown on the lid 444 and the guard ring GR, the lid through hole 445 and the guard ring through hole 442 are abruptly closed at first. However, as the first sealing layer 461 becomes thicker, its momentum decreases, and the lid through-hole 445 and the guard ring through-hole 442 are hardly blocked from when the first sealing layer 461 exceeds a certain thickness. Therefore, tapered (funnel-shaped) through-holes 464 (first through-hole 465 and second through-hole 466) are formed in the first sealing layer 461. Further, a part of the first sealing layer 461 enters the lid part through hole 445 and the guard ring through hole 442, so that a frame-like protruding part 467 is formed. For this reason, it can be said that the lid portion 444 and the guard ring GR have a function as a base layer for forming the through hole 464 and the protruding portion 467 in the first sealing layer 461.

[Guard ring / lid removal process]
Next, the substrate 2 is exposed to an etching solution such as a mixed acid of phosphoric acid, acetic acid and nitric acid, for example, and the lid portion 444 and the guard ring GR are removed via the first through hole 465 and the second through hole 466. Thereby, the pressure reference chamber S is formed as shown in FIG. In particular, in the present embodiment, the lid 444 positioned immediately (directly below) the first through hole 465 can be efficiently removed by the etching solution supplied from the first through hole 465, and the second through hole With the etching solution supplied from 466, the guard ring GR positioned in the immediate vicinity (directly below) of the second through-hole 466 can be efficiently removed. Therefore, the lid 444 and the guard ring GR can be more reliably removed. In particular, in this embodiment, since the outer portion 441b ″ of the flange portion 441b is sandwiched between the first sealing layer 461 and the side wall portion 40, the etching solution hardly penetrates into the outer portion 441b ″, and the outer portion 441b ″. However, since the second through hole 466 is formed in the outer portion 441b ″, the outer portion 441b ″ can be more reliably removed. In the present embodiment, the lid portion 444 and the guard are removed. Although all of the ring GR is removed, the lid 444 and a part of the guard ring GR may remain.

[Second sealing layer arranging step]
Next, in a state where the pressure reference chamber S is in a vacuum state through the through hole 464, a second sealing layer 462 is formed on the upper surface of the first sealing layer 461, and the through hole 464 is sealed. The film formation method of the second sealing layer 462 is not particularly limited, and various film formation methods (vapor phase growth method) such as a sputtering method and a CVD method can be used, for example. Next, the second sealing layer 462 is patterned using a photolithography technique and an etching technique, and the outer edge of the second sealing layer 462 is placed inside the outer edge of the first sealing layer 461 as shown in FIG. Position. Note that as a patterning method of the second sealing layer 462, wet etching using an etchant such as buffered hydrofluoric acid is preferably used. Thereby, a large etching selection ratio between the second sealing layer 462 and the first sealing layer 461 can be secured, and only the second sealing layer 462 can be patterned substantially.

[Third sealing layer arranging step]
Next, as shown in FIG. 14, a third sealing layer 463 is formed on the top surfaces of the first sealing layer 461 and the second sealing layer 462. Thereby, the second sealing layer 462 is sealed by the first sealing layer 461 and the third sealing layer 463. The film formation method of the third sealing layer 463 is not particularly limited, and for example, various film formation methods (vapor phase growth method) such as a sputtering method and a CVD method can be used.

  Next, as shown in FIG. 15, the first sealing layer 461 and the third sealing layer 463 are simultaneously patterned by using a photolithography technique and an etching technique. Thereby, the sealing layer 46 is obtained. Note that by forming the first sealing layer 461 and the third sealing layer 463 with the same material, they can be simultaneously patterned. Therefore, the manufacturing process of the pressure sensor 1 can be reduced, and the manufacturing of the pressure sensor 1 becomes easier.

[Diaphragm formation process]
Next, as shown in FIG. 16, for example, the first layer 21 is etched by using a dry etching (particularly, silicon deep etching) method, and a recess 24 that opens to the lower surface is formed in the diaphragm formation region 250. Get 25. Thus, the pressure sensor 1 is obtained. In addition, the order of a diaphragm formation process is not specifically limited, For example, you may perform prior to a sensor part arrangement | positioning process, and may be performed between a sensor part arrangement | positioning process and a 3rd sealing layer arrangement | positioning process.

  The manufacturing method of the pressure sensor 1 has been described above. As described above, the manufacturing method of the pressure sensor 1 includes the step of preparing the substrate 2 having the diaphragm formation region 250 and the diaphragm formation region 250 in the plan view of the substrate 2 on the upper surface (one surface) side of the substrate 2. A surrounding guard ring GR, a sacrificial layer G located in a space inside the guard ring GR, a lid portion 444 having a lid portion through-hole 445 facing the substrate 2 through the sacrificial layer G and facing the sacrificial layer G; , The step of removing the sacrificial layer G through the lid portion through-hole 445, and the upper portion of the lid portion 444 (the side opposite to the substrate 2) so as to overlap the lid portion 444 in plan view of the substrate 2. A step of disposing a first sealing layer 461 having a first through hole 465 disposed and a second through hole 466 disposed so as to overlap the guard ring GR in plan view of the substrate 2; And the second through hole 4 A step of removing the lid portion 444 and the guard ring GR through the first sealing layer 461 and a first through hole 465 and a second through hole 466 on the upper side of the first sealing layer 461 (on the side opposite to the substrate 2). 2 includes the step of disposing the two sealing layers 462 and the step of forming the diaphragm 25 that is bent and deformed by pressure reception in the diaphragm formation region 250.

  According to such a manufacturing method, the lid 444 and the guard ring GR can be more reliably removed through the first through hole 465 and the second through hole 466. Therefore, the internal stress of the pressure sensor 1 can be further reduced. In addition, changes due to the degree of thermal expansion of the guard ring GR and the lid portion 444 (that is, the environmental temperature) of the internal stress applied to the diaphragm 25 can be suppressed to a small level, and a decrease in pressure detection accuracy of the pressure sensor 1 can be suppressed. Can do. Therefore, the pressure sensor 1 that can exhibit high pressure detection accuracy is obtained.

Further, as described above, the first sealing layer 461 includes silicon (Si), and the second sealing layer 462 includes silicon oxide (SiO ₂ ). Accordingly, the first sealing layer 461 and the second sealing layer 462 can be easily formed by a semiconductor process. In addition, since the substrate 2 is composed of an SOI substrate, the difference in coefficient of thermal expansion between the substrate 2 and the sealing layer 46 facing each other through the pressure reference chamber S can be reduced. Therefore, the internal stress generated by thermal expansion can be kept small. Furthermore, the change due to the environmental temperature of the internal stress applied to the diaphragm 25 can be suppressed. Therefore, for example, it is possible to effectively suppress a decrease in detection accuracy such that the detected pressure varies depending on the environmental temperature even when receiving the same pressure.

  In addition, as described above, in the method for manufacturing the pressure sensor 1, the third sealing layer is disposed on the upper side of the second sealing layer 462 (on the side opposite to the substrate 2) after the step of arranging the second sealing layer 462. 463 is included. Thereby, even if the through hole 464 is not sealed by the second sealing layer 462, the through hole 464 can be more reliably sealed by the third sealing layer 463. Therefore, the air tightness of the pressure reference chamber S can be ensured more reliably.

Further, as described above, the third sealing layer 463 includes silicon (Si). Thereby, the third sealing layer 463 can be easily formed by a semiconductor process. In particular, when the first sealing layer 461 includes silicon (Si) and the second sealing layer 462 includes silicon oxide (SiO ₂ ) as in the present embodiment, the first sealing layer 461 is included. Further, by sandwiching the second sealing layer 462 with the third sealing layer 463, the thermal expansion coefficient can be averaged in the thickness direction, and the bending of the sealing layer 46 in the out-of-plane direction during the thermal expansion can be performed. Can be suppressed.

Further, as described above, the second sealing layer 462 is blocked from the outside by the first sealing layer 461 and the third sealing layer 463. Thereby, the 2nd sealing layer 462 can be protected from moisture etc., and the change of the internal stress of sealing layer 46 resulting from environmental humidity can be controlled. Such an effect is particularly remarkable when the second sealing layer 462 contains silicon oxide (SiO ₂ ).

Second Embodiment
17 and 18 are cross-sectional views for explaining a method for manufacturing a pressure sensor according to the second embodiment of the present invention.

  The manufacturing method of the pressure sensor according to the present embodiment is substantially the same as the manufacturing method of the pressure sensor of the first embodiment described above except that the configuration of the guard ring is different.

  Hereinafter, the manufacturing method of the pressure sensor of the second embodiment will be described focusing on the differences from the first embodiment described above, and the description of the same matters will be omitted. In FIG. 17 and FIG. 18, the same reference numerals are given to the same configurations as those in the above-described embodiment.

  FIG. 17 is a cross-sectional view corresponding to FIG. 9 of the first embodiment described above. As shown in the figure, in the manufacturing method of the pressure sensor 1 of this embodiment, the configuration of the guard ring GR (wiring part 441) formed in the sacrificial layer arrangement step is different from that of the first embodiment described above. Yes. Specifically, the wiring part 441 is provided through the interlayer insulating film 43, is provided on the concave two contact parts 441a connected to the wiring part 421, and on the interlayer insulating film 43, and is connected to the contact part 441a. And a flange portion 441b disposed around the periphery. Further, the two contact portions 441a are concentrically arranged in a frame shape surrounding the pressure reference chamber S in a plan view of the substrate 2.

  Further, when the contact portion 441a located on the sacrificial layer G side is “contact portion 441a ′” and the contact portion 441a located outside is “contact portion 441a”, the contact portion 441a ′ is located inside the flange portion 421b. The contact portion 441a ″ is connected to the outer portion 421b ″ of the flange portion 421b. A guard ring through hole 442 is formed in each of the contact portions 441a ′ and 441a ″ and the flange portion 441b. In particular, in the flange portion 441b, the inner portion 441b ′ positioned on the sacrificial layer G side with respect to the contact portion 441a ′. A guard ring through hole 442 is formed in each of the outer portion 441b ″ located on the opposite side of the sacrificial layer G from the contact portion 441a ″ and the portion located between the contact portions 441a ′ and 441a ″. However, the arrangement of the guard ring through holes 442 is not particularly limited.

  For example, as in the first embodiment described above, if the contact portion 441a is to be connected to the contact portion 421a, the contact portion 441a may be hindered in the semiconductor process depending on the thickness of the interlayer insulating films 41 and 43. It will be deeper. Therefore, the step coverage (step coverage) of the sealing layer 46 formed on the contact portion 441a is deteriorated, and for example, the mechanical strength of the surrounding structure 4 and the airtightness of the pressure reference chamber S may be reduced. is there. On the other hand, in this embodiment, since the contact portion 441a is connected to the flange portion 421b, the step coverage of the sealing layer 46 is improved compared to the first embodiment, and the mechanical structure of the surrounding structure 4 is improved. It is possible to more reliably suppress the deterioration of the mechanical strength and the airtightness of the pressure reference chamber S.

  In the case of the present embodiment, when the [guard ring / lid removing step] is completed, the interlayer insulating film 43 surrounded by the wiring portion 421 and the wiring portion 441 is formed as shown in FIG. It separates from the side wall 40 and remains in the pressure reference chamber S as a movable piece X. However, the movable piece X has a frame shape and can hardly be displaced in the pressure reference chamber S. Therefore, the movable piece X hardly affects the pressure detection.

  According to the second embodiment as described above, the same effect as that of the first embodiment described above can be exhibited.

<Third Embodiment>
FIG. 19 is a cross-sectional view showing a pressure sensor according to the second embodiment of the present invention. FIG. 20 is a flowchart showing manufacturing steps of the pressure sensor shown in FIG. 21 to 25 are cross-sectional views for explaining a method of manufacturing the pressure sensor shown in FIG.

  The manufacturing method of the pressure sensor according to the present embodiment is substantially the same as the manufacturing method of the pressure sensor of the first embodiment described above except that the guard ring is omitted.

  Hereinafter, the manufacturing method of the pressure sensor according to the third embodiment will be described with a focus on differences from the first embodiment described above, and the description of the same matters will be omitted. In FIG. 19 to FIG. 25, the same reference numerals are given to the same components as those in the above-described embodiment.

  The pressure sensor 1 of this embodiment has a configuration shown in FIG. Depending on the thickness of the interlayer insulating layer 43, the interlayer insulating layer 43 may have a laminated structure of two or more layers. In that case, a wiring layer may be disposed between the layers.

  As shown in FIG. 20, the manufacturing method of such a pressure sensor 1 includes a preparation process for preparing the substrate 2, a sensor part arranging process for arranging the sensor unit 5 on the substrate 2, A sacrificial layer arranging step of arranging the sacrificial layer G so as to overlap the diaphragm forming region 250 in a plan view of 2, and a lid portion arranging step of arranging a lid portion 444 having a lid portion through-hole 445 on the sacrificial layer G; A sacrificial layer removing step for removing the sacrificial layer G through the lid through-hole 445, and a first sealing layer 461 having a first through-hole 465 and a second through-hole 466 on the upper surface of the lid 444 are arranged. A first sealing layer arranging step, a lid removing step of removing the lid 444 through the first through-hole 465 and the second through-hole 466, and a second sealing layer 462 on the upper surface of the first sealing layer 461. A second sealing layer arranging step to be arranged; and a second sealing layer 462 A third sealing layer arrangement step of placing the third sealing layer 463 on the upper surface, and includes a diaphragm forming step of forming a diaphragm 25 on the substrate 2, a. In addition, since a preparation process, a sensor part arrangement | positioning process, a 2nd sealing layer arrangement | positioning process, a 3rd sealing layer arrangement | positioning process, and a diaphragm formation process are the same as that of 1st Embodiment mentioned above, respectively, below, these processes are carried out. The description of is omitted.

[Sacrificial layer placement process]
Next, as shown in FIG. 21, an interlayer insulating film 41 is sequentially formed in a predetermined pattern on the substrate 2 by using a sputtering method, a CVD method, or the like. As a result, the sacrificial layer G disposed so as to overlap the diaphragm 25 in plan view of the substrate 2 is formed integrally with the interlayer insulating film 41.

[Lid placement process]
Next, as shown in FIG. 22, a wiring layer 42, an interlayer insulating film 43, a wiring layer 44, a surface protective film 45, and a terminal 47 are sequentially formed on the interlayer insulating film 41 using a sputtering method, a CVD method, or the like. Form with a pattern. In this step, a lid portion 444 that faces the substrate 2 with the sacrificial layer G interposed therebetween is formed on the sacrificial layer G by the wiring portion 421. The lid 444 has a first region 444A that overlaps the diaphragm forming region 250 in a plan view of the substrate 2 and a second region 444B that is positioned outside the diaphragm forming region 250. Furthermore, the lid portion 444 has a first lid portion through hole 445a formed in the first region 444A and a second lid portion through hole 445b formed in the second region 444B.

[Sacrificial layer removal process]
Next, the substrate 2 is exposed to an etching solution such as buffered hydrofluoric acid in a state where the second lid portion through-hole 445b is sealed with the resist R. Thereby, as shown in FIG. 23, the sacrificial layer G is removed by etching through the first lid portion through-hole 445a. Since there is no guard ring GR that functions as an etching stopper as in the first embodiment described above, it is necessary to pay attention to the control of the etching time accordingly.

[First sealing layer arranging step]
Next, after removing the resist R, as shown in FIG. 24, a first sealing layer 461 having a plurality of through holes 464 is formed on the top surfaces of the lid 444 and the surface protective film 45. The film formation method of the first sealing layer 461 is not particularly limited, and various film formation methods (vapor phase growth method) such as a sputtering method and a CVD method can be used, for example. The plurality of through holes 464 overlap with the first region 444A in a plan view of the substrate 2 and overlap with the first through hole 465 communicating with the first lid through hole 445a and the second region 444B. And a second through hole 466 communicating with the part through hole 445b.

[Lid removal process]
Next, the substrate 2 is exposed to an etching solution such as a mixed acid of phosphoric acid, acetic acid and nitric acid, and the lid portion 444 is removed via the first through hole 465 and the second through hole 466. Thereby, the pressure reference chamber S is formed as shown in FIG. In particular, in the present embodiment, the first region 444A located in the immediate vicinity (directly below) the first through hole 465 can be efficiently removed by the etching solution supplied from the first through hole 465, and the second through hole can be removed. With the etching solution supplied from the hole 466, the second region 444B located in the immediate vicinity (directly below) of the second through hole 466 can be efficiently removed. Therefore, in this step, the lid portion 444 can be removed more reliably. In particular, in the present embodiment, since the second region 444B is sandwiched between the first sealing layer 461 and the side wall portion 40, the etching solution hardly penetrates into the second region 444B, and the second region 444B is difficult to remove. . However, since the second through hole 466 is formed in the second region 444B, the second region 444B can be more reliably removed. In the present embodiment, all of the lid part 444 is removed, but a part of the lid part 444 may remain.

  The manufacturing method of the pressure sensor 1 has been described above. As described above, the manufacturing method of the pressure sensor 1 includes the step of preparing the substrate 2 having the diaphragm formation region 250, and the diaphragm formation region 250 in the plan view of the substrate 2 on the upper surface (one surface) side of the substrate 2. The step of disposing the sacrificial layer G so as to overlap, and the substrate 2 through the sacrificial layer G, and is positioned outside the first region 444A and the diaphragm forming region 250 that overlap the diaphragm forming region 250 in plan view of the substrate 2. A step of disposing a lid portion 444 having a second region 444B and having a first lid portion through hole 445a facing the sacrificial layer G in the first region 444A; and the sacrificial layer G via the first lid portion through hole 445a. In the plan view of the first through hole 465 and the substrate 2 disposed so as to overlap the first region 444A in a plan view of the substrate 2 on the upper side (opposite side of the substrate 2) of the lid portion 444. The step of disposing the first sealing layer 461 having the second through-hole 466 disposed so as to overlap the second region 444B, and the cover 444 is removed via the first through-hole 465 and the second through-hole 466. A step, a step of disposing a second sealing layer 462 for sealing the first through hole 465 and the second through hole 466 on the upper side of the first sealing layer 461 (on the side opposite to the substrate 2), and a diaphragm forming region 250 includes a step of forming the diaphragm 25 which is bent and deformed by receiving pressure.

  According to such a manufacturing method, the lid 444 can be more reliably removed through the first through hole 465 and the second through hole 466. Therefore, the internal stress of the pressure sensor 1 can be further reduced. Moreover, the change resulting from the degree of thermal expansion of the lid portion 444 (that is, the environmental temperature) of the internal stress applied to the diaphragm 25 can be suppressed to a small level, and the decrease in pressure detection accuracy of the pressure sensor 1 can be suppressed. Therefore, the pressure sensor 1 that can exhibit high pressure detection accuracy is obtained.

  According to the third embodiment as described above, the same effects as those of the first embodiment described above can be exhibited.

<Fourth embodiment>
Next, a pressure sensor module according to a fourth embodiment of the invention will be described.

  FIG. 26 is a sectional view showing a pressure sensor module according to the fourth embodiment of the present invention. FIG. 27 is a plan view of a support substrate included in the pressure sensor module shown in FIG.

  Hereinafter, the pressure sensor module according to the fourth embodiment will be described with a focus on differences from the above-described embodiments, and description of similar matters will be omitted.

  As shown in FIG. 26, the pressure sensor module 100 includes a package 110 having an internal space S1, a support substrate 120 arranged to be drawn out of the package 110 from the internal space S1, and a support substrate in the internal space S1. The circuit element 130 and the pressure sensor 1 supported by 120, and the filling portion 140 formed by filling the internal space S1 with a filler as described later. According to such a pressure sensor module 100, the pressure sensor 1 can be protected by the package 110 and the filling unit 140. In addition, as the pressure sensor 1, the thing of embodiment mentioned above can be used, for example.

  The package 110 includes a base 111 and a housing 112, and the base 111 and the housing 112 are joined to each other via an adhesive layer so as to sandwich the support substrate 120. The package 110 formed in this way has an opening 110a formed at the upper end portion thereof, and an internal space S1 communicating with the opening 110a.

  The constituent materials of the base 111 and the housing 112 are not particularly limited. For example, various ceramics such as oxide ceramics such as alumina, silica, titania and zirconia, and nitride ceramics such as silicon nitride, aluminum nitride and titanium nitride. Insulating materials such as various resin materials such as polyethylene, polyamide, polyimide, polycarbonate, acrylic resin, ABS resin, and epoxy resin can be used, and one or more of these can be used in combination. it can. Among these, it is particularly preferable to use various ceramics.

  Although the package 110 has been described above, the configuration of the package 110 is not particularly limited as long as the function can be exhibited.

  The support substrate 120 is sandwiched between the base 111 and the housing 112, and is arranged so as to be drawn out of the internal space S1 to the outside of the package 110. The support substrate 120 supports the circuit element 130 and the pressure sensor 1 and electrically connects the circuit element 130 and the pressure sensor 1. As shown in FIG. 27, such a support substrate 120 includes a flexible base material 121 and a plurality of wirings 129 arranged on the base material 121.

  The substrate 121 has a frame-like base portion 122 having an opening 122 a and a belt-like strip body 123 extending from the base portion 122. Then, the band body 123 extends outside the package 110 by being sandwiched between the base 111 and the housing 112 at the outer edge portion of the base portion 122. As such a substrate 121, for example, a commonly used flexible printed circuit board can be used. In addition, in this embodiment, although the base material 121 has flexibility, all or one part of the base material 121 may be hard.

  In a plan view of the substrate 121, the circuit element 130 and the pressure sensor 1 are located inside the opening 122a and arranged side by side. Further, the circuit element 130 and the pressure sensor 1 are respectively suspended from the base material 121 via the bonding wires BW and supported by the support substrate 120 in a state of floating from the support substrate 120. The circuit element 130 and the pressure sensor 1 are electrically connected via a bonding wire BW and a wiring 129, respectively. As described above, by supporting the circuit element 130 and the pressure sensor 1 in a floating state with respect to the support substrate 120, it becomes difficult for stress to be transmitted from the support substrate 120 to the circuit element 130 and the pressure sensor 1. Detection accuracy is improved.

  The circuit element 130 includes a drive circuit for supplying a voltage to the bridge circuit 50, a temperature compensation circuit for temperature compensation for the output from the bridge circuit 50, a pressure detection circuit for obtaining a pressure received from the output from the temperature compensation circuit, An output circuit for converting the output from the pressure detection circuit into a predetermined output format (CMOS, LV-PECL, LVDS, etc.) and the like is provided.

  The filling unit 140 is disposed in the internal space S <b> 1 so as to cover the circuit element 130 and the pressure sensor 1. The filling unit 140 protects the circuit element 130 and the pressure sensor 1 (dustproof and waterproof), and external stress (for example, drop impact) acting on the pressure sensor 1 is not easily transmitted to the circuit element 130 and the pressure sensor 1. Become.

  Moreover, the filling part 140 can be comprised with a liquid or a gel-like filler, and is comprised especially with a gel-like filler in the point which can suppress the excessive displacement of the circuit element 130 and the pressure sensor 1. Is preferred. According to such a filling unit 140, the circuit element 130 and the pressure sensor 1 can be effectively protected from moisture, and the pressure can be efficiently transmitted to the pressure sensor 1. The filler constituting the filling unit 140 is not particularly limited, and for example, silicone oil, fluorine-based oil, silicone gel, or the like can be used.

  The pressure sensor module 100 has been described above. Such a pressure sensor module 100 includes a pressure sensor 1 and a package 110 that houses the pressure sensor 1. Therefore, the pressure sensor 1 can be protected by the package 110. Moreover, the effect of the pressure sensor 1 mentioned above can be enjoyed and high reliability can be exhibited.

  In addition, as a structure of the pressure sensor module 100, it is not limited to the above-mentioned structure, For example, the filling part 140 may be abbreviate | omitted. In this embodiment, the pressure sensor 1 and the circuit element 130 are supported by the bonding wire BW while being suspended from the support substrate 120. For example, the pressure sensor 1 and the circuit element 130 are directly supported. It may be disposed on the substrate 120. Moreover, in this embodiment, although the pressure sensor 1 and the circuit element 130 are arrange | positioned side by side, the pressure sensor 1 and the circuit element 130 may be arrange | positioned along with the height direction, for example.

<Fifth Embodiment>
Next, an electronic apparatus according to a fifth embodiment of the invention will be described.

FIG. 28 is a perspective view showing an altimeter as an electronic apparatus according to the fifth embodiment of the present invention.
As shown in FIG. 28, an altimeter 200 as an electronic device can be attached to the wrist like a wristwatch. In addition, the pressure sensor 1 is mounted inside the altimeter 200, and the altitude from the current location above sea level, the atmospheric pressure at the current location, or the like can be displayed on the display unit 201. The display unit 201 can display various information such as the current time, the user's heart rate, and weather.

  An altimeter 200 as an example of such an electronic device has a pressure sensor 1. Therefore, the altimeter 200 can enjoy the effect of the pressure sensor 1 described above, and can exhibit high reliability.

<Sixth Embodiment>
Next, an electronic apparatus according to a sixth embodiment of the invention will be described.

  FIG. 29 is a front view showing a navigation system as an electronic apparatus according to the sixth embodiment of the present invention.

  As shown in FIG. 29, a navigation system 300 as an electronic device includes map information (not shown), position information acquisition means from a GPS (Global Positioning System), a gyro sensor, an acceleration sensor, vehicle speed data, Is provided with a self-contained navigation means, a pressure sensor 1, and a display 301 for displaying predetermined position information or course information.

  According to the navigation system 300, altitude information can be acquired in addition to the acquired position information. For example, when driving on an elevated road that shows approximately the same position as that of a general road, if the navigation system does not have altitude information, the navigation system determines whether the vehicle is traveling on an ordinary road or an elevated road. It was not possible to provide the user with general road information as priority information. Therefore, by installing the pressure sensor 1 in the navigation system 300 and acquiring altitude information by the pressure sensor 1, it is possible to detect an altitude change due to entering the elevated road from a general road, and in the traveling state of the elevated road Navigation information can be provided to the user.

  A navigation system 300 as an example of such an electronic device includes the pressure sensor 1. Therefore, the navigation system 300 can enjoy the effect of the pressure sensor 1 described above, and can exhibit high reliability.

  The electronic device of the present invention is not limited to the altimeter and the navigation system described above. For example, a personal computer, a digital still camera, a mobile phone, a smartphone, a tablet terminal, a watch (including a smart watch), a drone, a medical device ( For example, it is applied to electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasonic diagnostic devices, electronic endoscopes), various measuring instruments, instruments (for example, vehicles, aircraft, ship instruments), flight simulators, etc. be able to.

<Seventh embodiment>
Next, the moving body according to the seventh embodiment of the present invention will be described.

FIG. 30 is a perspective view showing an automobile as a moving body according to the seventh embodiment of the invention.
As shown in FIG. 30, an automobile 400 as a moving body has a vehicle body 401 and four wheels 402 (tires), and wheels 402 are driven by a power source (engine) (not shown) provided in the vehicle body 401. Is configured to rotate. Further, the automobile 400 has an electronic control unit (ECU) 403 mounted on the vehicle body 401, and the pressure sensor 1 is built in the electronic control unit 403. The electronic control unit 403 can grasp the moving state, the posture, and the like by the pressure sensor 1 detecting the acceleration, the inclination, and the like of the vehicle body 401, and can accurately control the wheels 402 and the like. Thereby, the automobile 400 can move safely and stably. The pressure sensor 1 may be mounted on a navigation system or the like provided in the automobile 400.

  An automobile 400 as an example of such a moving body has a pressure sensor 1. Therefore, the automobile 400 can enjoy the effect of the pressure sensor 1 described above, and can exhibit high reliability.

  As mentioned above, although the manufacturing method of the pressure sensor of the present invention, the pressure sensor, the pressure sensor module, the electronic device, and the moving body were explained based on each illustrated embodiment, the present invention is not limited to these, The configuration can be replaced with any configuration having a similar function. Moreover, other arbitrary structures and processes may be added. Moreover, you may combine each embodiment suitably.

  DESCRIPTION OF SYMBOLS 1 ... Pressure sensor, 2 ... Board | substrate, 4 ... Surrounding structure, 5 ... Sensor part, 21 ... 1st layer, 22 ... 2nd layer, 23 ... 3rd layer, 24 ... Recessed part, 25 ... Diaphragm, 250 ... Diaphragm formation 251 ... pressure-receiving surface, 31 ... first insulating film, 32 ... second insulating film, 33 ... third insulating film, 40 ... side wall portion, 41 ... interlayer insulating film, 42 ... wiring layer, 421 ... wiring portion, 421a ... contact part, 421b ... flange part, 421b '... inner part, 421b "... outer part, 429 ... wiring part, 43 ... interlayer insulating film, 44 ... wiring layer, 441 ... wiring part, 441a, 441a', 441a" ... Contact part, 441b ... Flange part, 441b '... Inner part, 441b "... Outer part, 442 ... Guard ring through hole, 444 ... Lid part, 444A ... First area, 444B ... Second area, 445 ... Lid part through hole 445a 1st lid part through-hole, 445b ... 2nd lid part through-hole, 449 ... Wiring part, 45 ... Surface protective film, 46 ... Sealing layer, 461 ... 1st sealing layer, 461A ... 1st area | region, 461B ... 1st 2 region, 462 ... 2nd sealing layer, 463 ... 3rd sealing layer, 464 ... through-hole, 465 ... 1st through-hole, 466 ... 2nd through-hole, 467 ... protrusion part, 47 ... terminal, 50 ... bridge | bridging Circuit, 51, 52, 53, 54 ... Piezoresistive element, 55 ... Wiring, 100 ... Pressure sensor module, 110 ... Package, 110a ... Opening, 111 ... Base, 112 ... Housing, 120 ... Support substrate, 121 ... Base material, 122 ... Base, 122a ... Opening, 123 ... Band, 129 ... Wiring, 130 ... Circuit element, 140 ... Filling unit, 200 ... Altimeter, 201 ... Display unit, 300 ... Navigation system, 301 ... Display unit, 400 ... Auto Car, 401 ... Car body, 402 ... Wheel, 403 ... Electronic control unit, AVDC ... Drive voltage, BW ... Bonding wire, G ... Sacrificial layer, GR ... Guard ring, R ... Resist, Rmax ... Diameter, Rmin ... Diameter, S ... Pressure reference chamber, S1 ... internal space, T1, T2, T3 ... thickness, X ... movable piece

Claims (10)

Preparing a substrate having a diaphragm forming region;
On one surface side of the substrate, a guard ring surrounding the diaphragm forming region in plan view of the substrate, a sacrificial layer located in a space inside the guard ring, and facing the substrate through the sacrificial layer A step of disposing a lid portion having a lid portion through-hole facing the sacrificial layer;
Removing the sacrificial layer through the lid through hole;
A first through hole disposed on the opposite side of the lid portion from the substrate so as to overlap the lid portion in plan view of the substrate and a first through hole disposed so as to overlap the guard ring in plan view of the substrate. Disposing a first sealing layer having two through holes;
Removing the lid and the guard ring through the first through hole and the second through hole;
Disposing a second sealing layer for sealing the first through hole and the second through hole on the opposite side of the first sealing layer from the substrate;
Forming a diaphragm that bends and deforms by receiving pressure in the diaphragm forming region, and a method for manufacturing a pressure sensor. Preparing a substrate having a diaphragm forming region;
Placing a sacrificial layer on one surface side of the substrate so as to overlap the diaphragm forming region in plan view of the substrate;
A first region facing the substrate through the sacrificial layer and overlapping the diaphragm forming region in a plan view of the substrate; and a second region positioned outside the diaphragm forming region; Arranging a lid portion having a first lid portion through hole facing the sacrificial layer;
Removing the sacrificial layer through the first lid through hole;
A first through hole disposed on the opposite side of the lid portion from the substrate so as to overlap the first region in a plan view of the substrate and a second through region disposed in a plan view of the substrate. Disposing a first sealing layer having a second through hole,
Removing the lid through the first through hole and the second through hole;
Disposing a second sealing layer for sealing the first through hole and the second through hole on the opposite side of the first sealing layer from the substrate;
Forming a diaphragm that bends and deforms by receiving pressure in the diaphragm forming region, and a method for manufacturing a pressure sensor. The first sealing layer includes silicon;
The pressure sensor manufacturing method according to claim 1, wherein the second sealing layer contains silicon oxide. After the step of disposing the second sealing layer,
The manufacturing method of the pressure sensor of any one of Claim 1 thru | or 3 including the process of arrange | positioning a 3rd sealing layer on the opposite side to the said board | substrate of a said 2nd sealing layer.   The method for manufacturing a pressure sensor according to claim 4, wherein the third sealing layer contains silicon.   The pressure sensor manufacturing method according to claim 4 or 5, wherein the second sealing layer is blocked from the outside by the first sealing layer and the third sealing layer. A substrate including a diaphragm that is bent and deformed by receiving pressure;
A side wall portion disposed on one surface side of the substrate and surrounding the diaphragm in a plan view of the substrate;
A sealing layer that is disposed to face the diaphragm through a space surrounded by the side wall, and seals the space;
The sealing layer includes a first sealing layer having a through hole communicating with the space, and a second seal that is located on the opposite side of the diaphragm with respect to the first sealing layer and seals the through hole. A stop layer,
The pressure sensor according to claim 1, wherein the through hole has a first through hole located inside the diaphragm and a second through hole located outside the diaphragm in a plan view of the substrate. A pressure sensor according to claim 7;
A pressure sensor module comprising: a package housing the pressure sensor.   An electronic apparatus comprising the pressure sensor according to claim 7.   A moving body comprising the pressure sensor according to claim 7.

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