JP2019082360A - Pressure sensor, pressure sensor module, electronic apparatus, and moving body - Google Patents

Abstract

To provide a pressure sensor, pressure sensor module, electronic apparatus, and moving body in which the residual stress is difficult to transfer to a diaphragm and that have a high atmospheric pressure detection characteristic.SOLUTION: The pressure sensor includes: a substrate having a diaphragm deflected by pressure reception; a side wall part including a first metal part that is connected to one surface side of the substrate and is disposed so as to surround the diaphragm in the plan view of the substrate; and an encapsulation layer that is disposed so as to face the diaphragm via a space surrounded by the side wall part, and encapsulates the space. In the plan view of the substrate, the clearance between the outer edge of the diaphragm and the connection part of the first metal part to the substrate is 30 μm or more and 60 μm or less.SELECTED DRAWING: Figure 1

Description

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

  DESCRIPTION OF RELATED ART Conventionally, the structure described in patent document 1 is known as a pressure sensor. The pressure sensor of Patent Document 1 has a substrate having a diaphragm that is bent and deformed by pressure reception, and a surrounding structure disposed on the substrate, and a pressure reference chamber is formed therebetween. In addition, the surrounding structure has a frame-like side wall surrounding the pressure reference chamber, and a sealing layer sealing the opening of the wall.

JP, 2015-184100, A

  However, in the pressure sensor described in Patent Document 1, since the side wall portion is close to the diaphragm, residual stress of the surrounding structure is easily transmitted to the diaphragm. Therefore, the diaphragm may be bent by a force other than the air pressure to be detected, and the detection accuracy of the air pressure may be reduced. In addition, since the residual stress changes (opens) with time, it is also difficult to correct the residual stress.

  An object of the present invention is to provide a pressure sensor, a pressure sensor module, an electronic device, and a movable body, which have excellent pressure detection characteristics, in which residual stress is not easily transmitted to the diaphragm.

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

The pressure sensor according to the present invention comprises a substrate having a diaphragm that deforms in a flexible manner upon receiving pressure;
A side wall portion including a first metal portion connected to one side of the substrate and disposed to surround the diaphragm in plan view of the substrate;
A sealing layer disposed opposite to the diaphragm via a space surrounded by the side wall and sealing the space;
In a plan view of the substrate, a separation distance between an outer edge of the diaphragm and a connection portion of the first metal portion to the substrate is 30 μm to 60 μm.
As a result, it is difficult for the residual stress to be transmitted to the diaphragm, and the pressure sensor has excellent pressure detection characteristics.

In the pressure sensor of the present invention, the first metal portion preferably contains aluminum.
Thereby, the first metal portion can be easily formed.

In the pressure sensor of the present invention, the first metal portion is preferably embedded in the side wall portion.
Thereby, the thermal expansion of the first metal portion can be suppressed, and the change in internal stress due to the thermal expansion of the first metal portion can be effectively reduced. Therefore, it is possible to suppress the change of the internal stress applied to the diaphragm due to the environmental temperature, and to provide a pressure sensor which can exhibit excellent pressure detection accuracy.

In the pressure sensor according to the present invention, the pressure sensor further includes a second metal portion which is located between the side wall portion and the sealing layer and which is disposed so as to surround the diaphragm in plan view of the substrate.
It is preferable that the inner peripheral end of the second metal portion is located inside the diaphragm in a plan view of the substrate.
Thereby, the sealing layer can be supported from the lower side by the second metal portion, and bending of the sealing layer to the diaphragm side can be effectively suppressed.

In the pressure sensor according to the present invention, preferably, the second metal portion is connected to the first metal portion.
Thus, the first metal portion and the second metal portion can be integrally formed, and the configuration of the pressure sensor can be simplified.

In the pressure sensor of the present invention, the sealing layer is a first sealing layer having a through hole facing the space;
And a second sealing layer located on the opposite side to the space with respect to the first sealing layer and sealing the through hole,
Each of the first sealing layer and the second sealing layer preferably contains silicon.
Thus, the sacrificial layer filling the space can be easily removed in the middle of the production through the through hole, and the space can be easily hermetically sealed by the second sealing layer. In addition, the sealing layer can be easily formed by a semiconductor process.

In the pressure sensor of the present invention, the sealing layer has a third sealing layer located on the opposite side to the space with respect to the second sealing layer,
The third sealing layer preferably contains silicon.
Thereby, the space can be more reliably sealed by the sealing layer. In addition, the third sealing layer can be easily formed by a semiconductor process.

In the pressure sensor of the present invention, a sensor unit provided on the diaphragm;
An insulating layer disposed between the substrate and the sidewall portion;
The first metal portion is preferably connected to the substrate through the insulating layer.
Thus, the sensor portion and the first metal portion can be insulated with a relatively simple configuration.

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

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

The moving body of the present invention is characterized by having the pressure sensor of the present invention.
As a result, the effect of the pressure sensor of the present invention can be enjoyed, and a highly reliable moving body can be obtained.

It is a sectional view showing a pressure sensor concerning a 1st embodiment of the present invention. It is a top view which shows the sensor part which the pressure sensor shown in FIG. 1 has. It is a figure which shows the bridged circuit containing the sensor part shown in FIG. It is an expanded sectional view which shows the sealing layer which the pressure sensor shown in FIG. 1 has. It is a top view which shows the metal layer which the pressure sensor shown in FIG. 1 has. It is a graph which shows the relationship between separation distance D and residual stress P1 and P2. It is an expanded sectional view of the metal 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 a sectional view showing a pressure sensor concerning a 2nd embodiment of the present invention. It is sectional drawing which shows the pressure sensor module which concerns on 3rd Embodiment of this invention. It is a top view of the support substrate which the pressure sensor module shown in FIG. 21 has. It is a perspective view which shows the altimeter as an electronic device which concerns on 4th Embodiment of this invention. It is a front view which shows the navigation system as an electronic device concerning a 5th embodiment of the present invention. It is a perspective view showing the car as a mobile concerning a 6th embodiment of the present invention.

  Hereinafter, a pressure sensor, a pressure sensor module, an electronic device, and a moving body according to the present invention will be described in detail based on embodiments shown in the attached drawings.

First Embodiment
First, a pressure sensor according to a 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 diagram showing a bridge circuit including the sensor unit shown in FIG. FIG. 4 is an enlarged sectional view showing a sealing layer of the pressure sensor shown in FIG. FIG. 5 is a plan view showing a metal layer which the pressure sensor shown in FIG. 1 has. FIG. 6 is a graph showing the relationship between the separation distance D and the residual stress P1, P2. FIG. 7 is an enlarged sectional view of a metal layer of the pressure sensor shown in FIG. FIG. 8 is a flow chart showing a manufacturing process of the pressure sensor shown in FIG. 9 to 19 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, 7 and 9 to 19 is also referred to as “upper” and the lower side as “lower”. Moreover, the planar view of a board | substrate, ie, the planar view seen from the up-down direction in FIG. 1, is also only called "planar view."

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

  As shown in FIG. 1, the substrate 2 is provided with a first layer 21 made of silicon and a third layer 23 made of silicon, which is disposed on the upper side of the first layer 21, a first layer 21 and a third layer. And a second layer 22 disposed between the layers 23 and made of silicon oxide, and configured of an SOI substrate. As a result, the substrate 2 can be easily handled in manufacturing and can exhibit excellent processing dimensional accuracy. The substrate 2 is not limited to the SOI substrate, and for example, a single-layer silicon substrate can also be used. The substrate 2 may be a substrate (semiconductor substrate) made of a semiconductor material other than silicon, such as germanium, gallium arsenide, gallium arsenide phosphide, gallium nitride, silicon carbide or the like.

  The substrate 2 is formed with a diaphragm 25 which is thinner than the peripheral portion and which is bent and deformed by pressure reception. A bottomed recess 24 is formed in the substrate 2 so as to open 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 receiving pressure. In the present embodiment, the plan view shape of the diaphragm 25 is substantially square, but the plan view shape of the diaphragm 25 is not particularly limited. For example, the four corners may be chamfered, or a circle or a triangle It may be a quadrilateral other than a square, a pentagon or more polygon, or the like.

  The recess 24 is formed by dry etching (Bosch process) using a silicon deep etching apparatus. Specifically, the recess 24 is formed by duplicating the first layer 21 by repeating the steps of isotropic etching, protective film formation and anisotropic etching from the lower surface side of the substrate 2. This process is repeated, and when the etching reaches the second layer 22, the second layer 22 becomes an etching stopper, and the etching is completed, whereby the recess 24 is obtained. According to such a formation method, the inner wall side surface of the recess 24 is substantially perpendicular to the main surface of the substrate 2, so the opening area of the recess 24 can be reduced. Therefore, the decrease in mechanical strength of the substrate 2 can be suppressed, and the increase in size of the pressure sensor 1 can also be suppressed.

  However, the method for forming the recess 24 is not limited to the above method, and may be formed by, for example, dry etching or wet etching other than the above. Further, although the second layer 22 is left on the lower surface side of the diaphragm 25 in the present embodiment, the second layer 22 may be removed. That is, the diaphragm 25 may be formed of a single layer of the third layer 23. As a result, the diaphragm 25 can be made thinner, and the diaphragm 25 which is more likely to be bent and deformed can be obtained. In addition, the recess 24 may be formed in the middle of the first layer 21.

  The width W of the diaphragm 25 is not particularly limited, but is preferably 100 μm to 500 μm, and more preferably 100 μm to 300 μm. As a result, the diaphragm 25 can be made sufficiently flexible while suppressing excessive enlargement. The thickness T of the diaphragm 25 is not particularly limited, and varies depending on the width W of the diaphragm 25. However, as described above, when the width W of the diaphragm 25 is 100 μm to 500 μm, for example, 1 μm or more It is preferable that it is 10 micrometers or less, and it is more preferable that they are 1 micrometer or more and 3 micrometers or less. As a result, it is possible to obtain the diaphragm 25 which is sufficiently thin and easily deformed by pressure reception while maintaining sufficient mechanical strength.

  The diaphragm 25 is provided with a sensor unit 5 capable of detecting the 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, 54 are electrically connected to each other through the wiring 55, and constitute a bridge circuit 50 (a Wheatstone bridge circuit) shown in FIG. The bridge circuit 50 is connected to a drive circuit for supplying (applying) a drive voltage AVDC. Then, the bridge circuit 50 outputs a detection signal (voltage) according to a change in resistance value of the piezoresistive elements 51, 52, 53, 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, 54 are arranged at the outer edge of the diaphragm 25. When the diaphragm 25 is bent and deformed due to pressure reception, a large stress is particularly applied to the outer edge of the diaphragm 25. Therefore, arranging the piezoresistive elements 51, 52, 53, 54 at the outer edge enlarges the aforementioned detection signal. Can improve the sensitivity of pressure detection. The arrangement of the piezoresistive elements 51, 52, 53, 54 is not particularly limited. For example, the piezoresistive elements 51, 52, 53, 54 may be disposed across the outer edge of the diaphragm 25, or the diaphragm It may be arranged at the center of 25.

  The piezoresistive elements 51, 52, 53, 54 are configured, for example, by doping (diffusing or injecting) an impurity such as phosphorus, boron, or arsenic into the third layer 23 of the substrate 2. The wiring 55 is formed by doping (diffusing or injecting) an impurity such as phosphorus, boron, or arsenic at a higher concentration than that of the piezoresistive elements 51, 52, 53, 54 in the third layer 23 of the substrate 2, for example. It is configured.

  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 disposed on the diaphragm 25. Further, as the sensor unit 5, in addition to the piezoresistive type as in the present embodiment, a capacitive type that detects a pressure based on a change in electrostatic capacity may be used.

In addition, as shown in FIG. 1, a first insulating film 31 made of a silicon oxide film (SiO ₂ film) is formed on the upper surface of the substrate 2. The interface state of the piezoresistive elements 51, 52, 53 and 54 can be reduced by the first insulating film 31 to suppress the generation of noise.

  A second insulating film 32 formed of a silicon nitride film (SiN film) is formed on the first insulating film 31. The second insulating film 32 has a frame shape surrounding the periphery of the diaphragm 25 so as not to overlap with the diaphragm 25. A third insulating film 33 made of polysilicon (p-Si) is formed on the first insulating film 31 and the second insulating film 32. The sensor unit 5 can be protected from moisture, gas or the like by the second and third insulating films 32 and 33. In the present embodiment, the second insulating film 32 is disposed so as not to overlap with the diaphragm 25, and the third insulating film 33 is disposed so as to overlap with the diaphragm 25. The third insulating film 33 can be formed thinner than the second insulating film 32, and the substantial thickness of the diaphragm 25 (the thickness of the film formed on the diaphragm 25 to the thickness of the diaphragm 25) can be formed. Thickness) can be made thinner. Hereinafter, a stacked body of the first, second, and third insulating films 31, 32, and 33 is also referred to as the insulating film 30.

  Note that at least one of the first insulating film 31, the second insulating film 32, and the third insulating film 33 may be omitted or may be made of different materials. For example, instead of the third insulating film 33, a conductive film having conductivity (for example, a film obtained by doping polysilicon with an impurity) is provided, and this conductive film is used as a reference potential (ground). By applying the drive voltage of (1), the conductive film can function as a shield layer that protects the sensor unit 5 from the disturbance. Therefore, the sensor unit 5 is not easily affected by the disturbance, and the pressure detection accuracy of the pressure sensor 1 can be further enhanced.

  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 is a reference value of the pressure detected by the pressure sensor 1. In particular, the pressure reference chamber S is preferably in a reduced pressure state, particularly in a vacuum state or a state closer to the vacuum state (for example, 10 Pa or less). The pressure reference chamber S may not be in a vacuum state as long as it is maintained at a constant pressure.

  The pressure reference chamber S has a tapered shape whose cross-sectional area gradually increases from the substrate 2 side toward the sealing layer 46 side. That is, the cross-sectional area on the substrate 2 side is smaller than the area on the sealing layer 46 side. In addition, the rate of change of the area of the pressure reference chamber S gradually decreases from the substrate 2 side toward the sealing layer 46 side. However, the shape of the pressure reference chamber S is not particularly limited. For example, the cross-sectional area may be substantially constant from the substrate 2 side toward the sealing layer 46 side.

  The surrounding structure 4 forms a pressure reference chamber S with the substrate 2. Such a 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 an interlayer disposed on the wiring layer 42 and the interlayer insulating film 41. Insulating film 43, interconnection layer 44 disposed on interlayer insulation film 43, surface protection film 45 disposed on interconnection layer 44 and interlayer insulation film 43, and disposed on interconnection layer 44 and surface protection film 45 And the terminal 47 disposed on the surface protective film 45.

Each of the interlayer insulating films 41 and 43 has a frame shape, and is arranged to surround the diaphragm 25 in a plan view. The interlayer insulating films 41 and 43 constitute a sidewall 4A. Further, a space (pressure reference chamber S) is formed inside the side wall portion 4A. The constituent material of the interlayer insulating films 41 and 43 is not particularly limited, and, for example, silicon oxide (SiO ₂ ) or the like can be used.

  The wiring layer 42 includes a frame-shaped guard ring 421 disposed so as to surround the pressure reference chamber S, and a wiring portion 429 connected to the wiring 55 of the sensor unit 5. Further, the wiring layer 44 has a frame-shaped guard ring 441 disposed so as to surround the pressure reference chamber S, and a wiring portion 449 connected to the wiring 55. The constituent material of the wiring layers 42 and 44 is not particularly limited, and includes, for example, various metals such as nickel, gold, platinum, silver, copper, manganese, aluminum, magnesium, titanium, or at least one of them. Alloy etc. are mentioned. Among these, as a constituent material of the wiring layers 42 and 44, aluminum is preferable, and in the present embodiment, aluminum is used. Thereby, the wiring layers 42 and 44 can be easily formed in a semiconductor process such as a manufacturing method described later.

  The metal layer 48 is configured by the guard rings 421 and 441 of the wiring layers 42 and 44 as described above. The metal layer 48 will be described in detail later.

  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. The constituent material of the surface protective film 45 is not particularly limited, and, for example, silicon-based materials such as silicon oxide and silicon nitride, and various resin materials such as polyimide and epoxy resin can be used.

  Further, on the surface protective film 45, a plurality of terminals 47 electrically connected to the sensor unit 5 via the wiring portions 429 and 449 are provided. The constituent material of the terminal 47 is not particularly limited, and, for example, the same material as the wiring layers 42 and 44 described above can be used.

  The sealing layer 46 is located on the ceiling of the pressure reference chamber S, and is disposed to face the diaphragm 25 via a pressure reference chamber S (space) formed inside the side wall 4A. The sealing layer 46 seals the pressure reference chamber S.

  As shown in FIG. 1, the sealing layer 46 includes a first sealing layer 461 whose lower surface faces the pressure reference chamber S, a second sealing layer 462 stacked on the upper surface of the first sealing layer 461, and And a third sealing layer 463 stacked on the top surface of the second sealing layer 462. As described above, by forming the sealing layer 46 in a laminated structure, the pressure reference chamber S can be hermetically sealed more reliably.

The first sealing layer 461 contains silicon (Si), and is particularly made of silicon (Si) in the present embodiment. Further, the second sealing layer 462 contains silicon oxide (SiO ₂ ), and in particular, in the present embodiment, it is made of silicon oxide (SiO ₂ ). The third sealing layer 463 contains silicon (Si), and in the present embodiment, it is made of silicon (Si). The first sealing layer 461, the second sealing layer 462, and the third sealing layer 463 are respectively formed by various film forming methods such as a sputtering method and a CVD method, as will be described in a manufacturing method to be described later. be able to.

As described above, since the sealing layers 461, 462, and 463 each contain silicon (Si), the sealing layer 46 can be easily formed by a semiconductor process as described in the manufacturing method to be described later. . Furthermore, by sandwiching the second sealing layer 462 made of a material (SiO ₂ ) different from the first sealing layer 461 and the third sealing layer 463 made of the same material (silicon), The thermal expansion coefficient of the sealing layer 46 can be averaged in the thickness direction. Therefore, the bending to the out-of-plane direction at the time of the thermal expansion of the sealing layer 46 can be suppressed.

  In particular, by suppressing the downward deflection of the sealing layer 46, the contact between the sealing layer 46 and the diaphragm 25 can be suppressed. When the sealing layer 46 comes into contact with the diaphragm 25, the bending deformation of the diaphragm 25 due to pressure reception is inhibited, and the pressure detection accuracy is lowered. Therefore, as described above, a pressure having excellent pressure detection accuracy is suppressed by suppressing the deflection in the out-of-plane direction during thermal expansion of the sealing layer 46 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 formed of the SOI substrate, the sealing layers 461, 462, and 463 contain silicon (Si), respectively, so that the substrates facing each other via the pressure reference chamber S are The difference between the thermal expansion coefficients of the second and the sealing layers 46 can be reduced. Therefore, the thermal expansion applied to the diaphragm 25 can be suppressed small, and the change of the thermal stress due to the environmental temperature can be suppressed. Therefore, the output drift due to the environmental temperature is suppressed, and the pressure sensor 1 having excellent temperature characteristics is obtained.

  As shown in FIG. 1, a plurality of through holes 461 a are formed in the first sealing layer 461. The plurality of through holes 461a are used as release etching holes for removing the sacrificial layer G filling the pressure reference chamber S halfway through the manufacturing, as described in the manufacturing method described later. The plurality of such through holes 461 a are sealed by the second sealing layer 462 disposed on the first sealing layer 461.

  The cross-sectional shape of each through hole 461a is substantially circular. However, the cross-sectional shape of each through hole 461a 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 461 a has a tapered shape in which the cross sectional area (diameter) gradually decreases from the pressure reference chamber S side to the second sealing layer 462 side. By tapering the through hole 461a, the space in the through hole 461a is sufficiently secured to facilitate removal of the sacrificial layer G, and the opening on the upper side of the through hole 461a can be sufficiently reduced. The hole 461 a can be more reliably closed by the second sealing layer 462. The shape of the through hole 461a is not particularly limited, and may be a shape other than the above-described tapered shape, for example, a straight shape, a reverse tapered shape, or the like.

  The diameter Rmax (width) of the lower end side opening of the through hole 461a is not particularly limited, but for example, it is preferably 0.6 μm or more and 1.2 μm or less, and more preferably 0.8 μm or more and 1.0 μm or less preferable. On the other hand, the diameter Rmin (width) of the upper end side opening of the through hole 461a is not particularly limited, but for example, it is preferably 100 Å or more and 900 Å or less, and more preferably 300 Å or more and 700 Å or less. As a result, the through-hole 461 a is large enough to remove the sacrificial layer G and can be more reliably blocked by the second sealing layer 462. In addition, the through hole 461 a can be prevented from becoming excessively large, for example, the mechanical strength of the first sealing layer 461 is excessively reduced, or the first sealing layer 461 is not Excessive thickening of the first sealing layer 461 can be suppressed in order to secure mechanical strength.

  Further, in the through hole 461a, the rate of change of the cross sectional area (diameter) gradually decreases from the pressure reference chamber S side to the second sealing layer 462 side. That is, the inclination of the inner peripheral surface is tight toward the upper side, and the inner peripheral surface stands substantially vertically at the upper end portion. Therefore, it can be said that the through hole 461a has a funnel-shaped internal space. With such a configuration, the diameter of the through hole 461a can be gradually reduced from the lower side to the upper side, so the diameter Rmin can be controlled with high accuracy. Therefore, the diameter Rmin can be easily adjusted to the target value. That is, the diameter Rmin becomes too small, which makes it difficult to remove the sacrificial layer G, and conversely, the diameter Rmin becomes too large, and it becomes difficult to seal the through hole 461a with the second sealing layer 462 It is possible to suppress rips. The shape of the through hole 461a is not particularly limited. For example, the rate of change of the cross sectional area (diameter) may be constant upward.

  Further, the first sealing layer 461 has a frame shape (annular shape) surrounding the lower end side opening of each through hole 461a, and has a frame shaped projecting portion 461b protruding to the pressure reference chamber S side. Therefore, even if the sealing layer 46 is bent toward the diaphragm 25 and the sealing layer 46 contacts the diaphragm 25, the protrusion 461 b contacts preferentially. Therefore, the contact area between the sealing layer 46 and the diaphragm 25 can be reduced as compared with the case where the projecting portion 461 b is not present, and the occurrence of “sticking” that the sealing layer 46 sticks to the diaphragm 25 in contact Can be effectively suppressed. However, the protrusion 461 b may be omitted.

  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 461 a are disposed in the first sealing layer 461, the mechanical strength is likely to be lower than the other layers (the second sealing layer 462 and the third sealing layer 463). Thus, by satisfying the relationship of T1> T2 and T3, the first sealing layer 461 can have sufficient mechanical strength.

  Specifically, the thickness T1 of the first sealing layer 461 is not particularly limited, but is preferably, for example, 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 7 μm or less. Thereby, it is possible to prevent the first sealing layer 461 from being excessively thickened while giving the first sealing layer 461 sufficient mechanical strength. Further, the through holes 461a having the diameters Rmax and Rmin as described above can be formed more easily.

  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 461 a formed in the first sealing layer 461. The thickness T2 of such a second sealing layer 462 is not particularly limited, but is preferably, for example, 1 μm to 5 μm, and more preferably 1.5 μm to 2.5 μm. Thus, the through hole 461a can be more reliably sealed by the second sealing layer 462 while preventing the second sealing layer 462 from being excessively thickened.

  The third sealing layer 463 is stacked on the second sealing layer 462 as described above. At the time of thermal expansion of the sealing layer 46, the third sealing layer 463 mainly sandwiches the second sealing layer 462 made of a different material between the first sealing layer 461 and the same material. It is a layer for suppressing the deflection to the out-of-plane direction. Thereby, in particular, the downward bending of the sealing layer 46 can be suppressed, and the contact between the sealing layer 46 and the diaphragm 25 can be suppressed. In addition, if the second sealing layer 462 can not close the through hole 461 a due to a deposition defect of the second sealing layer 462 or the like, the third sealing layer 463 may close the through hole 461 a. You can also. Thereby, the pressure reference chamber S can be sealed more reliably.

  Here, if the second sealing layer 462 made of silicon oxide is exposed to the outside, the second sealing layer 462 may adsorb moisture, and the internal stress of the sealing layer 46 may change due to environmental humidity. There is. When the internal stress of the sealing layer 46 is changed due to the environmental humidity, it is transmitted to the diaphragm 25 and the internal stress of the diaphragm 25 is also changed. Therefore, the drift of the output resulting from environmental humidity arises, and there exists a possibility that the pressure detection precision of the pressure sensor 1 may fall.

  So, in this embodiment, the 2nd sealing layer 462 is covered with the 3rd sealing layer 463, and the 2nd sealing layer 462 is airtightly sealed from the outside of the pressure sensor 1. FIG. That is, the third sealing layer 463 covers the surface of the second sealing layer 462 which may be exposed to the outside, thereby preventing the second sealing layer 462 from being exposed to the outside. Thus, the second sealing layer 462 can be protected from moisture, and changes in internal stress of the sealing layer 46 due to environmental humidity can be suppressed.

  Although the side surface of the second sealing layer 462 is covered by the third sealing layer 463 in the present embodiment, the present invention is not limited to this, and the second sealing layer 462 may be covered by the first sealing layer 461. It may be covered by both the first sealing layer 461 and the third sealing layer 463. Also, for example, when used in an environment that is less susceptible to the influence of humidity, such as when the humidity is constant, the second sealing layer 462 may not be sealed by the third sealing layer 463, The 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 to 10 μm, and more preferably 0.3 μm to 1.0 μm. 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. Further, the generation of pinholes in the third sealing layer 463 can be suppressed, and the second sealing layer 462 can be sealed more reliably between the third sealing layer 461 and the first sealing layer 461. Therefore, the second sealing layer 462 can be protected from moisture more effectively. In addition, excessive thickening of the third sealing layer 463 can be prevented.

  The sealing layer 46 has been described above, but the configuration of the sealing layer 46 is not particularly limited. For example, the first and third sealing layers 461 and 463 may each contain a material other than silicon (eg, a material which inevitably mixes in manufacturing), and do not contain silicon. It is also good. Similarly, the second sealing layer 462 may contain a material other than silicon oxide (for example, a material which inevitably mixes in manufacturing), and may not contain silicon oxide. In addition, for example, another layer may be interposed 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. That is, the sealing layer 46 may have a laminated structure of four or more layers. In addition, the third sealing layer 463 may be omitted. In addition, the first sealing layer 461 may not have the through hole 461a, and in this case, the second sealing layer 462 and the third sealing layer 463 may be omitted.

  Next, the metal layer 48 will be described. As shown in FIG. 1, the metal layer 48 is located between the first metal portion 481 provided on the side wall 4A, the side wall 4A and the sealing layer 46, and is connected to the first metal portion 481. And a second metal portion 482. As shown in FIG. 5, each of the first and second metal parts 481 and 482 has a frame shape. Each of the first metal portion 481 and the second metal portion 482 may have a frame shape in which a part in the circumferential direction is lost. That is, "frame-like" is a meaning that includes a frame-like shape which is continuous in the circumferential direction and has an annular shape, as well as having a defect portion in a part of the circumferential direction.

  As shown in FIG. 1, the second metal portion 482 has an outer edge portion 482 ′ ′ sandwiched between the side wall portion 4A and the sealing layer 46 and an inner edge portion 482 ′ facing the pressure reference chamber S. Further, the inner peripheral end 482a of the second metal portion 482 is located inside the diaphragm 25 (overlaps with the diaphragm 25) in a plan view of the substrate 2. Thereby, the second metal portion 482 is formed. Thus, the sealing layer 46 can be supported from below, and deflection of the sealing layer 46 to the diaphragm 25 side can be effectively suppressed, and the second metal portion 482 blocks the through hole 461a. In order not to be, it is located in the outside of the field in which penetration hole 461a was formed.

  However, the position of the inner circumferential end 482 a is not particularly limited, and may be located outside the diaphragm 25 in plan view of the substrate 2, for example. Thereby, the volume of the second metal portion 482 can be reduced. The metal portion such as the second metal portion 482 has a thermal expansion coefficient greater than that of the surrounding portion. Therefore, by reducing the volume of the second metal portion 482, the generation of thermal stress caused by the thermal expansion of the second metal portion 482 can be suppressed. As a result, the thermal stress transmitted to the diaphragm 25 is also reduced, and excellent temperature characteristics can be exhibited. Further, the inner peripheral end 482 a may overlap with the outer edge of the diaphragm 25 in a plan view of the substrate 2. Further, the inner circumferential end 482 a may include a portion located inside the diaphragm 25 and a portion located outside the diaphragm 25.

  On the other hand, as shown in FIG. 1, the first metal portion 481 is connected to the second metal portion 482 at its upper end and connected (directly or indirectly connected) to the substrate 2 at its lower end. In the present embodiment, the first metal portion 481 is connected to the substrate 2 via the insulating film 30. As described above, by interposing the insulating film 30 between the first metal portion 481 and the substrate 2, the sensor portion 5 and the first metal portion 481 can be easily insulated. Such a first metal portion 481 has a function as an etching stopper at the time of removing the sacrificial layer G filling the pressure reference chamber S halfway through the manufacturing, as will be described also in the manufacturing method described later. Note that "the first metal portion 481 is connected to the substrate 2" means other than the case where the first metal portion 481 is directly connected to the substrate 2 without passing other members, This also includes the case of being indirectly connected to the substrate 2 via a member (in the present embodiment, the insulating film 30).

  In addition, the first metal portion 481 is embedded in the side wall portion 4A. That is, side wall portions 4A are provided on the outer peripheral side and the inner peripheral side (that is, between the pressure reference chamber S) of the first metal portion 481, respectively. Thus, thermal expansion of the first metal portion 481 can be suppressed by surrounding the first metal portion 481 with the side wall portion 4A. Therefore, the change of the thermal stress resulting from the thermal expansion of the first metal portion 481 can be effectively reduced. Therefore, a change in thermal stress applied to the diaphragm 25 due to the environmental temperature can be suppressed, and the pressure sensor 1 having excellent temperature characteristics can be obtained. However, for example, the side wall portion 4A on the inner peripheral side of the first metal portion 481 may be omitted, and the inner periphery of the first metal portion 481 may face the pressure reference chamber S.

  In addition, as shown in FIG. 1, a plan view of the connection portion of the first metal portion 481 with the substrate 2, specifically, the inner peripheral end 481 a of the lower end of the first metal portion 481 and the outer edge 25 a of the diaphragm 25. The separation distance D in the range of 30 μm to 60 μm. As a result, the residual stress of the metal layer 48 is less likely to be transmitted to the diaphragm 25. Therefore, the pressure sensor 1 can exhibit excellent pressure detection accuracy. In particular, the said residual stress changes with environmental temperature. Therefore, it becomes difficult for such residual stress to be transmitted to the diaphragm 25, thereby providing the pressure sensor 1 having excellent temperature characteristics. The residual stress also changes with time (generally, it releases and decreases with time). Therefore, the residual stress is less likely to be transmitted to the diaphragm 25, whereby the pressure sensor 1 can be stably detected with time. In addition, although it is preferable that the separation distance D satisfy | fills the said range by the perimeter of the 1st metal part 481, only a part of circumferential direction may satisfy | fill the said range. In this case, the above range is preferably satisfied by 50% or more in the circumferential direction, more preferably 70% or more, and the above range is further preferably satisfied by 90% or more. .

  Next, the above-described effects will be described in detail based on simulation results. FIG. 6 is a graph plotting the residual stress P1 applied to the center of the diaphragm 25 and the residual stress P2 applied to the outer edge of the diaphragm 25 when the separation distance D is changed. As apparent from this graph, the residual stresses P1 and P2 are both suppressed low in the range of the separation distance D in the range of 30 μm to 60 μm. From this result, it is understood that the residual stress of the first metal portion 481 is hardly transmitted to the diaphragm 25 by setting the separation distance D to 30 μm or more and 60 μm or less, and the pressure sensor 1 having excellent pressure detection characteristics is obtained. In this simulation, the residual stress is measured when the temperature of the pressure sensor 1 is changed by −200 ° C. (for example, when 225 ° C. to 25 ° C.). Further, in this simulation, conditions other than the separation distance D such as the separation distance D1 between the through hole 461a and the inner peripheral end 482a of the second metal portion 482 and the width W of the diaphragm 25 are equal. Further, the separation distance D1 of the pressure sensor used in the simulation is 5 μm, and the width W is 200 μm. However, the inventors have confirmed that there is no large difference in simulation results (the tendency of residual stress to change) even when the separation distance D1 and the width W are changed.

  If the separation distance D is less than 30 μm, the distance between the metal layer 48 and the diaphragm 25 becomes too short, and the residual stress of the metal layer 48 is easily transmitted to the diaphragm 25 so that both residual stresses P1 and P2 It is thought that it will grow. On the other hand, when the separation distance D exceeds 60 μm, the metal layer 48 can be moved away from the diaphragm 25. Therefore, although the residual stress of the metal layer 48 is hardly transmitted to the diaphragm 25, the volume of the second metal portion 482 increases. As a result, the residual stress itself of the metal layer 48 is increased. Then, it is considered that the increase of the residual stress is more than the difficulty of transmitting the residual stress to the diaphragm 25, and as a result, the residual stresses P1 and P2 become large. Thus, the separation distance D is not preferable if it is too close or too far, and it is necessary to set the appropriate distance as described above.

  The separation distance D may be in the range of 30 μm to 60 μm. Among them, the distance D is preferably 35 μm to 50 μm, and more preferably 40 μm to 45 μm. As a result, as is also apparent from FIG. 6, in particular, the residual stress P2 becomes smaller, and the above-described effect becomes more remarkable.

  Next, the configuration of the metal layer 48 will be described in detail. As described above, the metal layer 48 includes the guard ring 421 of the wiring layer 42 and the guard ring 441 of the wiring layer 44. As shown in FIG. 7, the guard ring 421 is provided through the interlayer insulating film 41 and is provided on the concave contact portion 421 a connected to the third insulating film 33 and on the interlayer insulating film 41. And a flange portion 421b disposed around the circumference 421a. Further, the flange portion 421b has an inner portion 421b 'positioned on the pressure reference chamber S side with respect to the contact portion 421a, and an outer portion 421b "positioned on the opposite side. And a concave contact portion 441a provided through the interlayer insulating film 43 and connected to the contact portion 421a of the guard ring 421, and a flange portion provided on the interlayer insulating film 43 and disposed around the contact portion 441a. The flange portion 441b has an inner portion 441b ′ located closer to the pressure reference chamber S than the contact portion 441a, and an outer portion 441b ′ ′ located opposite to the contact portion 441a. There is. In the metal layer 48 having such a configuration, it can be said that the first metal portion 481 is constituted by the guard ring 421 and the second metal portion 482 is constituted by the guard ring 441.

  The peripheral structure 4 has been described above, but the configuration of the peripheral structure 4 is not particularly limited. For example, in the present embodiment, two interlayer insulating films and two wiring layers are provided, but the number thereof is not particularly limited.

  The pressure sensor 1 has been described above. As described above, such a pressure sensor 1 is connected to the substrate 2 having the diaphragm 25 that is bent and deformed by pressure and the upper surface (one surface) side of the substrate 2 and surrounds the diaphragm 25 in plan view of the substrate 2 Is disposed opposite to the diaphragm 25 via the pressure reference chamber S (space) surrounded by the side wall portion 4A including the first metal portion 481 arranged as described above, and the pressure reference chamber S is sealed. And the sealing layer 46 which stops. The distance D between the outer edge 25a of the diaphragm 25 and the inner peripheral end 481a of the connection portion between the first metal portion 481 and the substrate 2 in the plan view of the substrate 2 is 30 μm to 60 μm. As a result, the residual stress of the first metal portion 481 is less likely to be transmitted to the diaphragm 25. Therefore, the pressure sensor 1 can exhibit excellent pressure detection accuracy. In particular, the residual stress changes with the environmental temperature. Therefore, it becomes difficult for the residual stress to be transmitted to the diaphragm 25, resulting in the pressure sensor 1 having excellent temperature characteristics. In addition, the residual stress changes with time (generally, it releases and decreases with time). Therefore, such residual stress is less likely to be transmitted to the diaphragm 25, whereby the pressure sensor 1 can be stably detected with time.

  In addition, as described above, the first metal portion 481 contains aluminum. Thereby, the first metal portion 481 can be easily formed.

  Further, as described above, the first metal portion 481 is embedded in the side wall portion 4A. Thus, the thermal expansion of the first metal portion 481 can be suppressed, and the change in thermal stress due to the thermal expansion of the first metal portion 481 can be effectively reduced. Therefore, a change in thermal stress applied to the diaphragm 25 due to the environmental temperature can be suppressed, and the pressure sensor 1 can exhibit excellent pressure detection accuracy.

  Further, as described above, the pressure sensor 1 has the second metal portion 482 located between the side wall portion 4A and the sealing layer 46 and disposed so as to surround the diaphragm 25 in plan view of the substrate 2. doing. The inner peripheral end 482 a of the second metal portion 482 is located inside the diaphragm 25 in a plan view of the substrate 2. As a result, the sealing layer 46 can be supported from below by the second metal portion 482, and deflection of the sealing layer 46 toward the diaphragm 25 can be effectively suppressed.

  Further, as described above, the second metal portion 482 is connected to the first metal portion 481. Thereby, the first metal portion 481 and the second metal portion 482 can be integrally formed, and the configuration of the pressure sensor 1 becomes simple.

  Further, as described above, the sealing layer 46 is opposite to the pressure sealing chamber S with respect to the first sealing layer 461 having the through hole 461 a facing the pressure reference chamber S and the first sealing layer 461. And a second sealing layer 462 for sealing the through hole 461a. Each of the first sealing layer 461 and the second sealing layer 462 contains silicon (Si). As a result, the sacrificial layer G filling the pressure reference chamber S can be easily removed halfway through the through hole 461a, and the second sealing layer 462 allows the pressure reference chamber S to be easily hermetically sealed. It can stop. In addition, the sealing layer 46 can be easily formed by a semiconductor process. In addition, as described above, when the substrate 2 is made of a silicon material such as an SOI substrate, the difference in thermal expansion coefficient between the substrate 2 and the sealing layer 46 facing each other via the pressure reference chamber S is reduced. Can. Therefore, the thermal stress generated by thermal expansion can be suppressed small.

  In addition, as described above, the sealing layer 46 has the third sealing layer 463 located on the opposite side of the pressure reference chamber S with respect to the second sealing layer 462. The third sealing layer 463 contains silicon. Thereby, the pressure reference chamber S can be airtightly sealed by the sealing layer 46 more reliably. In addition, the third sealing layer 463 can be easily formed by a semiconductor process.

  In addition, as described above, the pressure sensor 1 includes the sensor unit 5 provided on the diaphragm 25 and the insulating film 30 (insulating layer) disposed between the substrate 2 and the side wall 4A. ing. The first metal portion 481 is connected to the substrate 2 via the insulating film 30. Thereby, sensor part 5 and the 1st metal part 481 can be insulated by comparatively easy composition.

  Next, a method of manufacturing the pressure sensor 1 will be described. In the method of manufacturing the pressure sensor 1, as shown in FIG. 8, a preparing step of preparing the substrate 2, a sensor portion arranging step of arranging the sensor portion 5 on the substrate 2, a sacrificial layer G and a sacrificial layer G on the upper surface side of the substrate 2. A sacrificial layer disposing step of disposing sidewall portions 4A located around the sacrificial layer G, and a metal layer disposing a metal layer 480 having a through hole 445 facing the substrate 2 via the sacrificial layer G and facing the sacrificial layer G Disposing step, sacrificial layer removing step of removing the sacrificial layer G through the through hole 445, and first sealing layer disposing step of disposing the first sealing layer 461 having the through hole 461a above the metal layer 480 And a second sealing layer disposing step of disposing a second sealing layer 462 on the upper side of the first sealing layer 461, and a metal layer removing step of removing a part of the metal layer 480 via the through holes 461a. The third sealing layer 463 is disposed above the second sealing layer 462 A sealing layer arrangement step, and includes a diaphragm forming step of forming a diaphragm 25 on the substrate 2, a.

[Preparation process]
First, as shown in FIG. 9, 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 forming region 250 of the substrate 2. Next, for example, the surface of the third layer 23 is thermally oxidized to form a 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. 10, the sensor unit 5 is formed by implanting an impurity such as phosphorus or boron on 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 using a sputtering method, a CVD method, or the like.

[Sacrificial layer placement process, metal layer placement process]
Next, as shown in FIG. 11, the interlayer insulating film 41, the wiring layer 42, the interlayer insulating film 43 and the wiring layer 44, the surface protective film 45 and the terminal 47 are formed on the substrate 2 by sputtering, CVD or the like. It forms in a predetermined pattern in order. Thereby, a frame-shaped sidewall portion overlapping the diaphragm forming region 250 in plan view of the substrate 2 and located around the sacrificial layer G and the sacrificial layer G formed of the interlayer insulating films 41 and 43 and surrounding the sacrificial layer G 4A and a metal layer 480 are obtained. In addition, the metal layer 480 is formed of the wiring layer 44 and the metal layer 48 formed of the guard ring 421 formed of the wiring layer 42 and the guard ring 441 formed of the wiring layer 44, and via the sacrificial layer G. And a cover layer 444 facing the substrate 2. Further, the covering layer 444 is integrally formed with the guard ring 441 and has a plurality of through holes 445 facing the sacrificial layer G. Further, the side wall portion 4A and the sacrificial layer G are spatially separated by the metal layer 48. 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.

[Sacrificial layer removal process]
Next, the substrate 2 is exposed to an etching solution such as buffered hydrofluoric acid. Thereby, as shown in FIG. 12, the sacrificial layer G is etched away via the through holes 445. At this time, the metal layer 48 functions as an etching stopper, and unintentional removal of the side wall portion 4A located outside the metal layer 48 is suppressed. In the present embodiment, a part of the sacrificial layer G is not removed but remains as the sidewall portion 4A. As a result, the first metal portion 481 of the metal layer 48 is embedded in the side wall 4A. Here, since the wet etching in this step is isotropic etching, the sacrificial layer G is removed more on the covering layer 444 side than on the substrate 2 side. Therefore, the formed space has a tapered shape in which the area gradually increases from the substrate 2 side to the covering layer 444 side. In the present step, all of the sacrificial layer G may be removed.

[First sealing layer placement step]
Next, as shown in FIG. 13, a first sealing layer 461 having a through hole 461 a is formed on the upper surface of the metal layer 480 and the surface protective film 45. It does not specifically limit as a film-forming method of the 1st sealing layer 461, For example, various film-forming methods (vapor phase growth method), such as sputtering method and CVD method, can be used.

  Here, to describe this process in detail, when the first sealing layer 461 is grown on the metal layer 480, the through hole 445 is rapidly closed at first, but the first sealing layer 461 As the thickness of the first sealing layer 461 increases, the through hole 445 is hardly clogged when the first sealing layer 461 exceeds a certain thickness. Therefore, the through holes 461a can be formed easily and more reliably. In addition, a part of the first sealing layer 461 enters the through hole 445 to form a frame-like protrusion 461 b. From such a thing, it can be said that the coating layer 444 has a function as a base layer for forming the through hole 461a and the projecting portion 461b in the first sealing layer 461.

[Metal layer 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 covering layer 444 included in the metal layer 480 is removed through the through holes 461a. Thereby, as shown in FIG. 14, the pressure reference chamber S is formed, and the metal layer 48 is obtained from the remaining portion of the metal layer 480. Since the covering layer 444 is located in the vicinity of the through hole 461a, the covering layer 444 is etched away preferentially over the other portions (guard rings 421 and 441) of the metal layer 480. Therefore, in the present step, the covering layer 444 can be removed while leaving the metal layer 48 (guard rings 421 and 441).

[Second sealing layer placement step]
Next, with the pressure reference chamber S in a vacuum state through the through hole 461a, as shown in FIG. 15, the second sealing layer 462 is formed on the upper surface of the first sealing layer 461, and the through hole is formed. Seal the 461a. It does not specifically limit as a film-forming method of the 2nd sealing layer 462, For example, various film-forming methods (vapor-phase growth method), such as sputtering method and CVD method, can be used.

  Next, as shown in FIG. 16, the second sealing layer 462 is patterned using a photolithographic technique and an etching technique so that the outer edge of the second sealing layer 462 is inside the outer edge of the first sealing layer 461. Position. Note that, as a method of patterning the second sealing layer 462, wet etching using an etching solution such as buffered hydrofluoric acid is preferably used. Accordingly, a large etching selectivity between the second sealing layer 462 and the first sealing layer 461 can be secured, and substantially only the second sealing layer 462 can be patterned.

[Third sealing layer placement step]
Next, as illustrated in FIG. 17, the third sealing layer 463 is formed on the top surfaces of the first sealing layer 461 and the second sealing layer 462. Thus, the second sealing layer 462 is sealed by the first sealing layer 461 and the third sealing layer 463. It does not specifically limit as a film-forming method of the 3rd sealing layer 463, For example, various film-forming methods (vapor-phase growth method), such as sputtering method and CVD method, can be used.

  Next, as shown in FIG. 18, the first sealing layer 461 and the third sealing layer 463 are simultaneously patterned using a photolithography technique and an etching technique. Thereby, the sealing layer 46 is obtained. Note that when the first sealing layer 461 and the third sealing layer 463 are made of the same material, they can be patterned simultaneously. 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. 19, the first layer 21 is etched using, for example, a dry etching (in particular, silicon deep etching) method to form a recess 24 opened on the lower surface in the diaphragm forming region 250 to form a diaphragm Get 25 Thus, the pressure sensor 1 is obtained. The order of the diaphragm forming process is not particularly limited. For example, the order may be performed prior to the sensor unit arranging process or may be performed between the sensor unit arranging process and the third sealing layer arranging process.

Second Embodiment
Next, a pressure sensor according to a second embodiment of the present invention will be described.

  FIG. 20 is a cross-sectional view showing a pressure sensor according to a second embodiment of the present invention.

  The pressure sensor 1 according to the present embodiment is substantially the same as the pressure sensor 1 according to the first embodiment described above except that the configuration of the metal layer 48 is different.

  Hereinafter, the pressure sensor 1 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 addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above.

  FIG. 20 is a cross-sectional view corresponding to FIG. 7 of the first embodiment described above, and shows a cross section of the metal layer 48. As shown in the figure, in the present embodiment, the guard ring 441 is provided through the interlayer insulating film 43 and is provided on the two concave contact portions 441 a connected to the guard ring 421 and the interlayer insulating film 43. And a flange portion 441b provided around the contact portion 441a. 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. When the contact portion 441a located inside is referred to as "contact portion 441a '" and the contact portion 441a located outside is referred to as "contact portion 441a", the contact portion 441a' is an inner portion 421b 'of the flange portion 421b. The contact portion 441a ′ ′ is connected to the outer portion 421b ′ ′ of the flange portion 421b.

  For example, as in the first embodiment described above, when the contact portion 441a is to be connected to the contact portion 421a, depending on the thickness of the interlayer insulating films 41 and 43, the extent to which the contact portion 441a interferes with the subsequent film formation. May get deeper. Therefore, the step coverage (step coverage) of the sealing layer 46 formed on the contact portion 441a may be deteriorated, and for example, the mechanical strength of the surrounding structure 4 or the airtightness of the pressure reference chamber S may be deteriorated. is there. On the other hand, in the present embodiment, since the contact portion 441a is connected to the flange portion 421b, the step coverage of the sealing layer 46 becomes better as compared with the first embodiment, and the machine of the surrounding structure 4 It is possible to more reliably suppress the reduction of the target strength and the airtightness of the pressure reference chamber S.

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

Third Embodiment
Next, a pressure sensor module according to a third embodiment of the present invention will be described.

  FIG. 21 is a cross-sectional view showing a pressure sensor module according to a third embodiment of the present invention. FIG. 22 is a plan view of a support substrate of the pressure sensor module shown in FIG.

  Hereinafter, the pressure sensor module of the third embodiment will be described focusing on differences from the above-described embodiment, and the description of the same matters will be omitted.

  As shown in FIG. 21, the pressure sensor module 100 includes a package 110 having an internal space S1, a support substrate 120 drawn out from the interior of the internal space S1 to the outside of the package 110, and a support substrate in the internal space S1. It has the circuit element 130 and the pressure sensor 1 supported by 120, and the filling part 140 formed by filling the internal space S1 with a filling material to be 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 has a base 111 and a housing 112, and the base 111 and the housing 112 are bonded to each other via an adhesive layer so as to sandwich the support substrate 120. The package 110 thus formed has an opening 110a formed at the upper end 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 And insulating materials such as polyethylene, polyamide, polyimide, polycarbonate, acrylic resin, ABS resin, various resin materials such as epoxy resin, etc., and one or two or more of them may be used in combination. it can. Among these, it is particularly preferable to use various ceramics.

  The package 110 has been described above, but 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 drawn out from the inside space S1 to the outside of the package 110 and disposed. Further, 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. Such a support substrate 120 has a flexible base material 121 and a plurality of wirings 129 disposed on the base material 121, as shown in FIG.

  The base material 121 has a frame-like base 122 having an opening 122 a and a band-like band 123 extending from the base 122. Then, the outer peripheral portion of the base portion 122 is sandwiched between the base 111 and the housing 112, and the band 123 extends to the outside of the package 110. As such a base material 121, for example, a flexible printed circuit board generally used can be used. In addition, although the base material 121 has flexibility in this embodiment, 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 by the base material 121 via the bonding wire BW and supported by the support substrate 120 in a floating state from the support substrate 120. The circuit element 130 and the pressure sensor 1 are electrically connected to each other through the bonding wire BW and the 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, and the pressure of the pressure sensor 1 Detection accuracy is improved.

  Circuit element 130 includes a drive circuit for supplying a voltage to bridge circuit 50, a temperature compensation circuit for temperature compensating the output from bridge circuit 50, and a pressure detection circuit for obtaining the pressure received from the output from the temperature compensation circuit. And an output circuit which converts the output from the pressure detection circuit into a predetermined output format (CMOS, LV-PECL, LVDS, etc.) and outputs the converted signal.

  The filling unit 140 is disposed in the internal space S1 so as to cover the circuit element 130 and the pressure sensor 1. The circuit element 130 and the pressure sensor 1 are protected (dust-proof and waterproof) by such a filling portion 140, and external stress (for example, drop impact) applied to the pressure sensor 1 is hard to be transmitted to the circuit element 130 and the pressure sensor 1 Become.

  Moreover, the filling part 140 can be comprised with a liquid or gel-like filler, and since it can suppress the excessive displacement of the circuit element 130 and the pressure sensor 1, it comprises especially with a gel-like filler. 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 pressure can be efficiently transmitted to the pressure sensor 1. It does not specifically limit as a filler which comprises such a filling part 140, For example, a silicone oil, a fluorine-type oil, a silicone gel etc. can be used.

  The pressure sensor module 100 has been described above. Such a pressure sensor module 100 has a pressure sensor 1 and a package 110 containing 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. Further, in the present embodiment, the pressure sensor 1 and the circuit element 130 are supported by the bonding wire BW in a state of being suspended from the support substrate 120. However, for example, the pressure sensor 1 and the circuit element 130 directly support It may be disposed on the substrate 120. Further, in the present embodiment, the pressure sensor 1 and the circuit element 130 are arranged side by side, but for example, the pressure sensor 1 and the circuit element 130 may be arranged side by side in the height direction.

Fourth Embodiment
Next, an electronic device according to a fourth embodiment of the present invention will be described.

  FIG. 23 is a perspective view showing an altimeter as an electronic device according to a fourth embodiment of the present invention.

  As shown in FIG. 23, the altimeter 200 as an electronic device can be worn on the wrist like a watch. The pressure sensor 1 is mounted inside the altimeter 200, and the display unit 201 can display the altitude from the sea level of the current location, the pressure of the current location, and the like. The display unit 201 can display various information such as the current time, the heart rate of the user, the weather, and the like.

  The altimeter 200 which is an example of such an electronic device has a pressure sensor 1. Therefore, the altimeter 200 can receive the effect of the pressure sensor 1 described above, and can exhibit high reliability.

Fifth Embodiment
Next, an electronic device according to a fifth embodiment of the present invention will be described.

  FIG. 24 is a front view showing a navigation system as an electronic device according to a fifth embodiment of the present invention.

  As shown in FIG. 24, the navigation system 300 as an electronic device includes map information (not shown), position information acquisition means from GPS (Global Positioning System), a gyro sensor, an acceleration sensor, and vehicle speed data. And a pressure sensor 1 and a display unit 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 traveling on an elevated road showing substantially the same position on a general road and position information, if there is no altitude information, it is judged by the navigation system whether it is traveling on an elevated road or not. It was not possible to provide information on general roads to users as priority information. Therefore, by mounting 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 caused by entering from the general road to the elevated road, and 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 a pressure sensor 1. Therefore, the navigation system 300 can receive 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 navigation system described above, and, for example, personal computers, digital still cameras, mobile phones, smartphones, tablet terminals, watches (including smart watches), drone, medical devices ( For example, it applies to an electronic thermometer, a blood pressure meter, a blood glucose meter, an electrocardiogram measuring device, an ultrasonic diagnostic device, an electronic endoscope), various measuring devices, instruments (for example, instruments of vehicles, aircraft, ships), flight simulators, etc. be able to.

Sixth Embodiment
Next, a mobile unit according to a sixth embodiment of the present invention will be described.

  FIG. 25 is a perspective view showing a car as a mobile unit according to a sixth embodiment of the present invention.

  As shown in FIG. 25, an automobile 400 as a moving body has a car body 401 and four wheels 402 (tires), and the wheels 402 are provided by a power source (engine) (not shown) provided on the car body 401. Is configured to rotate. In addition, the automobile 400 has an electronic control unit (ECU: electronic control unit) 403 mounted on a vehicle body 401, and the pressure sensor 1 is built in the electronic control unit 403. The electronic control unit 403 detects the acceleration, inclination, and the like of the vehicle body 401, thereby grasping the movement state, the posture, and the like, and can appropriately control the wheels 402 and the like. Thus, 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 mobile includes a pressure sensor 1. Therefore, the automobile 400 can receive the effects of the pressure sensor 1 described above and can exhibit high reliability.

  The pressure sensor, the pressure sensor module, the electronic device, and the moving body according to the present invention have been described above based on the illustrated embodiments, but the present invention is not limited to these embodiments. Can be replaced by any configuration having In addition, any other components or steps may be added. Also, the embodiments may be combined as appropriate.

  DESCRIPTION OF SYMBOLS 1 ... pressure sensor, 2 ... substrate, 21 ... 1st layer, 22 ... 2nd layer, 23 ... 3rd layer, 24 ... crevice, 25 ... diaphragm, 25a ... outer edge, 250 ... diaphragm formation area, 251 ... pressure receiving surface, DESCRIPTION OF SYMBOLS 30 ... Insulating film, 31 ... 1st insulating film, 32 ... 2nd insulating film, 33 ... 3rd insulating film, 4 ... Surrounding structure, 4A ... Side wall part, 41 ... Interlayer insulating film, 42 ... Wiring layer, 421 ... Guard ring, 421 a: contact portion, 421 b: flange portion, 421 b ′: inner portion, 421 b ′ ′: outer portion, 429: wiring portion, 43: interlayer insulating film, 44: wiring layer, 441: guard ring, 441 a, 441 a ′ 441a ′ ′ contact portion 441b flange portion 441b ′ inner portion 441b ′ ′ outer portion 444 cover layer 445 through hole 449 interconnection portion 45 surface protective film 46 sealing layer , 461 First sealing layer 461a through hole 461b projecting portion 462 second sealing layer 463 third sealing layer 47 terminal 48 metal layer 480 metal layer 481 first Metal part, 481a ... inner peripheral end, 482 ... second metal part, 482 '... outer edge part, 482 "... inner edge part, 482a ... inner peripheral end, 5 ... sensor part, 50 ... bridge circuit, 51, 52, 53, 54: Piezoresistive element, 55: wiring, 100: pressure sensor module, 110: package, 110a: opening, 111: base, 112: housing, 120: supporting substrate, 121: base material, 122: base, 122a: opening, DESCRIPTION OF SYMBOLS 123 ... Band body, 129 ... Wiring, 130 ... Circuit element, 140 ... Filling part, 200 ... Altimeter, 201 ... Display part, 300 ... Navigation system, 301 ... Display part, 400 ... Car, 401 ... Car , 402: wheel, 403: electronic control unit, AVDC: driving voltage, BW: bonding wire, D, D1: separation distance, G: sacrificial layer, Rmax, Rmin, diameter, S: pressure reference chamber, S1: internal space, T, T1, T2, T3 ... thickness, W ... width

Claims (11)

A substrate having a diaphragm which is deformed by pressure reception;
A side wall portion including a first metal portion connected to one side of the substrate and disposed to surround the diaphragm in plan view of the substrate;
A sealing layer disposed opposite to the diaphragm via a space surrounded by the side wall and sealing the space;
A pressure sensor, wherein a distance between an outer edge of the diaphragm and a connection portion of the first metal portion with the substrate is 30 μm or more and 60 μm or less in plan view of the substrate.   The pressure sensor according to claim 1, wherein the first metal portion contains aluminum.   The pressure sensor according to claim 1, wherein the first metal portion is embedded in the side wall portion. And a second metal portion disposed between the side wall portion and the sealing layer and disposed to surround the diaphragm in a plan view of the substrate.
The pressure sensor according to any one of claims 1 to 3, wherein an inner peripheral end of the second metal portion is located inside the diaphragm in a plan view of the substrate.   The pressure sensor according to claim 4, wherein the second metal portion is connected to the first metal portion. The sealing layer is a first sealing layer having a through hole facing the space;
And a second sealing layer located on the opposite side to the space with respect to the first sealing layer and sealing the through hole,
The pressure sensor according to any one of claims 1 to 5, wherein the first sealing layer and the second sealing layer each contain silicon. The sealing layer has a third sealing layer opposite to the space with respect to the second sealing layer,
The pressure sensor according to claim 6, wherein the third sealing layer contains silicon. A sensor unit provided on the diaphragm;
An insulating layer disposed between the substrate and the sidewall portion;
The pressure sensor according to any one of claims 1 to 7, wherein the first metal portion is connected to the substrate via the insulating layer. A pressure sensor according to any one of claims 1 to 8;
And a package containing the pressure sensor.   An electronic device comprising the pressure sensor according to any one of claims 1 to 8.   A moving body comprising the pressure sensor according to any one of claims 1 to 8.

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