JP6947710B2 - Surface stress sensor and its manufacturing method - Google Patents

Description

The present invention relates to a surface stress sensor, particularly a film-type surface stress sensor (MSS) having higher sensitivity than a piezoresistive cantilever type sensor, and a method for manufacturing the surface stress sensor.

As a technique used for a sensor that collects information corresponding to the five human senses, particularly a taste and smell sensor that a human senses by receiving a chemical substance, for example, there is a piezo resistance cantilever type sensor disclosed in Patent Document 1. ..
The piezoresistive cantilever type sensor disclosed in Patent Document 1 is a film type surface stress sensor, and uniaxially applies the surface stress applied to the flat member to four piezoresistive connecting portions arranged around the flat member. It is configured to be detected as a sexual stress. In the technique described in Patent Document 1, when a film-type surface stress sensor is mounted as various sensors, the flat member is fixed to a substrate such as a package via a spacer, so that the flat member can be applied. It has a structure that floats in the air to receive the applied surface stress.

JP-A-2015-45657

However, in a structure in which a flat member floats in a hollow manner as in the technique described in Patent Document 1, when the substrate for fixing the surface stress sensor is deformed due to, for example, a change in environmental temperature, the deformation of the substrate is deformed to the flat member. Is applied as stress.
Since the stress applied to the flat member due to the deformation of the substrate is larger than the surface stress applied to the flat member when a chemical substance is received, an offset is given to the output of the voltage or current due to the piezoresistive effect. It will be.
Therefore, in the technique described in Patent Document 1, the offset changes according to the temperature change, which causes a problem that the measurement accuracy as the surface stress sensor deteriorates.
The present invention has been made by focusing on a conventional unsolved problem, and an object of the present invention is to provide a surface stress sensor and a method for manufacturing the surface stress sensor, which can suppress deterioration of measurement accuracy. do.

In order to achieve the above object, the surface stress sensor according to one aspect of the present invention includes a membrane, a frame member, at least a pair of connecting portions, a flexible resistor, a supporting base material, and a package substrate. A gap is provided between the membrane and the support base material, and the support base material and the package substrate are arranged at positions where they overlap with at least a part of the membrane when viewed from the thickness direction. It is connected by the connecting portion, and is characterized in that the area of the connecting portion is smaller than the area of the membrane when viewed from the thickness direction of the membrane. The membrane bends due to the applied surface stress. The frame member surrounds the membrane with a gap when viewed from the thickness direction of the membrane. The connecting portion is arranged at a position sandwiching the membrane when viewed from the thickness direction to connect the membrane and the frame member. The flexible resistance is provided in at least one of the connecting portions, and the resistance value changes according to the bending caused in the connecting portion. The supporting base material is connected to the frame member and overlaps the membrane when viewed from the thickness direction. The package substrate is connected to the surface of the support substrate opposite to the surface facing the membrane.

Further, the method for manufacturing the surface stress sensor according to another aspect of the present invention includes a laminate forming step, a first ion injection step, a second ion injection step, a heat treatment step, a wiring layer forming step, and a removing step. It is characterized by including a package substrate arranging process and a connecting process . In the laminate forming step, a recess is formed on one surface of the support base material, and the detection base material is bonded to the support base material so as to cover the recess, so that the support base material and the detection base material are attached. This is a step of forming a laminated body in which a gap portion is provided between the two. The first ion implantation step is performed on a selected part of the surface of the detection base material opposite to the surface facing the support base material, which is outside the preset region including the center of the detection base material. This is the step of implanting the first ion. The second ion implantation step is a step of injecting the second ion into a selected region outside the region in which the first ion is implanted in the detection substrate. In the heat treatment step, the first ion and the laminated body injected with the second ion are heat-treated to form a flexible resistance region in the region injected with the first ion, and the second ion is injected. This is a step of forming a low resistance region in the region in which the ions of the above are injected. The wiring layer forming step is a step of forming a wiring layer electrically connected to the flexible resistor. The removal step is a membrane that bends due to the applied surface stress by removing a region other than the low resistance region and the flexible resistance region around a preset region including the center of the detection substrate. a step of forming a frame member surrounding the membrane with a gap when viewed from the thickness direction of the membrane. Additionally, the removal step, at least a pair of connecting portions for connecting the frame member and the membrane are arranged at positions sandwiching the membrane when viewed from the thickness direction, and depending on the deflection occurred to the connecting portion This is a step of forming a flexible resistor whose resistance value changes. The package substrate arranging step is a step of arranging the package substrate on the surface of the supporting base material opposite to the surface facing the membrane. The connecting step is performed at a position between the supporting base material and the package substrate so as to overlap at least a part of the membrane when viewed from the thickness direction, and is larger than the area of the membrane when viewed from the thickness direction of the membrane. This is a step of forming a small connecting portion to connect the supporting base material and the package substrate.
Here, the "preset region including the center of the detection base material" means a region that will later become a membrane. Further, the "low resistance region and the flexible resistance region" refer to a region that will later become a connecting portion.

Further, the method for manufacturing a surface stress sensor according to another aspect of the present invention includes a laminate forming step, a first ion implantation step, a second ion implantation step, a heat treatment step, and a hole forming step. It is characterized by. In addition to this, the method for manufacturing a surface stress sensor according to another aspect of the present invention includes a gap forming step, a hole sealing step, a wiring layer forming step, a removing step, a package substrate arranging step, and a connecting step. It is characterized in that it comprises, when. The laminate forming step is a step of laminating a sacrificial layer on a supporting base material and further laminating a detection base material on the sacrificial layer to form a laminated body. The first ion implantation step is performed on a selected portion of the surface of the detection base material opposite to the surface facing the support base material, which is outside the preset region including the center of the detection base material. This is the process of implanting one ion. The second ion implantation step is a step of injecting the second ion into a selected region outside the region in which the first ion is implanted in the detection substrate. In the heat treatment step, the first ion and the laminated body injected with the second ion are heat-treated to form a flexible resistance region in the region injected with the first ion, and the second ion is injected. This is a step of forming a low resistance region in the region in which the ions of the above are injected. The hole forming step is a step of forming a hole penetrating to the sacrificial layer in a preset region including the flexible resistance region of the detection base material and the center of the detection base material. The gap forming step was arranged between the support base material and the flexible resistance region of the detection base material and a preset region including the center of the detection base material by etching through the holes. This is a step of removing the sacrificial layer and providing a gap between the supporting base material and the detection base material. The hole sealing step is a step of forming an oxide film on the surface of the detection base material opposite to the surface facing the supporting base material to seal the holes. The wiring layer forming step is a step of forming a wiring layer electrically connected to the flexible resistor. The removal step is a membrane that bends due to the applied surface stress by removing a region other than the low resistance region and the flexible resistance region around a preset region including the center of the detection substrate. a step of forming a frame member surrounding the membrane with a gap when viewed from the thickness direction of the membrane. Additionally, the removal step, at least a pair of connecting portions for connecting the frame member and the membrane are arranged at positions sandwiching the membrane when viewed from the thickness direction, and depending on the deflection occurred to the connecting portion This is a step of forming a flexible resistor whose resistance value changes. The package substrate arranging step is a step of arranging the package substrate on the surface of the supporting base material opposite to the surface facing the membrane. The connecting step is performed at a position between the supporting base material and the package substrate so as to overlap at least a part of the membrane when viewed from the thickness direction, and is larger than the area of the membrane when viewed from the thickness direction of the membrane. This is a step of forming a small connecting portion to connect the supporting base material and the package substrate.

According to one aspect of the present invention, a surface stress sensor and a surface stress sensor capable of reducing the stress applied to the membrane due to the deformation of the substrate on which the surface stress sensor is fixed and suppressing the deterioration of measurement accuracy. It becomes possible to provide the manufacturing method of.

It is a side view which shows the structure of the surface stress sensor which concerns on 1st Embodiment of this invention. FIG. 1 is a view taken along the line II of FIG. FIG. 2 is a cross-sectional view taken along the line III-III of FIG. FIG. 2 is a sectional view taken along line IV-IV of FIG. It is a perspective view of the surface stress sensor. It is a figure which shows the laminate formation process. It is a figure which shows the 1st ion implantation process and the 2nd ion implantation process. It is a figure which shows the wiring layer formation process. It is a figure which shows the wiring layer formation process. It is a figure which shows the wiring layer formation process. It is a figure which shows the wiring layer formation process. It is a figure which shows the wiring layer formation process. It is a figure which shows the operation | action of the surface stress sensor which has the conventional structure. It is a figure which shows the operation | action of the surface stress sensor of 1st Embodiment. It is a side view which shows the structure of the surface stress sensor which concerns on 2nd Embodiment of this invention. It is a figure which shows the laminate formation process. It is a figure which shows the hole forming process. It is a figure which shows the gap formation process. It is a figure which shows the hole sealing process. It is sectional drawing which shows the structure of the surface stress sensor which concerns on 3rd Embodiment of this invention. It is a top view which shows the structure of the surface stress sensor which concerns on 3rd Embodiment of this invention. It is a figure which shows an example of the laminated body forming process of the surface stress sensor which concerns on 3rd Embodiment of this invention. It is a figure which shows an example of the 1st ion implantation process and the 2nd ion implantation process of the surface stress sensor which concerns on 3rd Embodiment of this invention. It is a figure which shows another example of the hole formation process of the surface stress sensor which concerns on 4th Embodiment of this invention. It is a figure which shows another example of the gap formation process of the surface stress sensor which concerns on 4th Embodiment of this invention. It is a figure which shows another example of the hole sealing process of the surface stress sensor which concerns on 4th Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings referred to in the following description, the same or similar parts are designated by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the plane dimensions, the ratio of the thickness, etc. are different from the actual ones. Therefore, the specific thickness and dimensions should be determined in consideration of the following explanation. In addition, it goes without saying that the drawings include parts having different dimensional relationships and ratios from each other.
Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention describes the materials of the constituent parts, their shapes, structures, and the like. The arrangement etc. is not specified as the following. The technical idea of the present invention can be modified in various ways within the technical scope specified by the claims stated in the claims. Further, the directions of "left and right" and "up and down" in the following description are merely definitions for convenience of explanation, and do not limit the technical idea of the present invention. Therefore, for example, if the paper surface is rotated 90 degrees, "left and right" and "up and down" are read interchangeably, and if the paper surface is rotated 180 degrees, "left" becomes "right" and "right" becomes "left". Of course it will be.

(First Embodiment)
Hereinafter, the first embodiment of the present invention will be described with reference to the drawings.
(composition)
The configuration of the first embodiment will be described with reference to FIGS. 1 to 5.
The surface stress sensor 1 shown in FIGS. 1 to 5 is used, for example, as a sensor for detecting a sense of taste or a sense of smell, and comprises a package substrate 2, a connecting portion 4, a supporting substrate 10, and a detecting substrate 20. Be prepared.

(Package board)
The package substrate 2 is formed of, for example, a metal, a polymer, a ceramic material, or the like, and is formed, for example, with a thickness on the order of millimeters.
(Connection part)
The connection portion 4 is arranged on one surface of the package substrate 2 (the upper surface in FIG. 1), and is formed by using, for example, an adhesive or solder.
In the first embodiment, as an example, a case where the shape of the connecting portion 4 is formed in a circular shape will be described.

(Supporting base material)
The support base material 10 is arranged on one surface of the package base material 2, and is attached to the package base material 2 via the connecting portion 4.
In the first embodiment, as an example, a case where the center of the support base material 10 overlaps with the position where the connecting portion 4 is arranged will be described.
The area of the support base material 10 (in FIG. 1, the area of the support base material 10 when the support base material 10 is viewed from above and below) is larger than the area of the connecting portion 4.

The thickness of the support base material 10 (in FIG. 1, the length of the support base material 10 in the vertical direction) is set to 80 [μm] or more. The thickness of the support base material 10 may be set within the range of 80 [μm] or more and 750 [μm] or less.
As the material for forming the support base material 10, for example, a material containing any one of silicon (Si: silicon), sapphire, gallium arsenide, glass, and quartz can be used. Further, the support base material 10 may have a BOX layer formed of an oxide film or the like formed on the surface thereof.
In the first embodiment, as an example, a case where silicon is used as a material for forming the support base material 10 will be described.
As a result, in the first embodiment, the coefficient of linear expansion of the supporting base material 10 is set to 5.0 × 10 ^-6 / ° C. or less.

The coefficient of linear expansion of the material that can be used as the material for forming the support base material 10 is described below.
^{The coefficient of linear expansion of silicon is 3.9 × 10 -6} / ° C or lower in an environment of room temperature or higher and 1000 ° C. or lower.
^{The coefficient of linear expansion of sapphire is 9.0 × 10 -6} / ° C or lower in an environment of 0 ° C. or higher and 1000 ° C. or lower.
The coefficient of linear expansion of gallium arsenide (GaAs) is 6.0 × 10 ⁻⁶ / ° C. or less in an environment of 0 K or more and 300 K or less.
^{The coefficient of linear expansion of glass (float glass) is 8.5 × 10 −6} / ° C. or less to 9.0 × 10 ⁻⁶ / ° C. or less in an environment of 0 ° C. or higher and 300 ° C. or lower.
^{The coefficient of linear expansion of quartz is 0.59 × 10 -6} / ° C or lower in an environment of 0 ° C. or higher and 300 ° C. or lower. The coefficient of linear expansion of quartz has a peak near 300 ° C.

(Detection base material)
The detection base material 20 is laminated on one surface (upper surface in FIG. 1) of the support base material 10, and the membrane 22, the frame member 24, and the connecting portion 26 are integrally formed. ing.
In the first embodiment, as an example, a case where silicon is used as a material for forming the detection base material 20 will be described.
Further, as the material for forming the detection base material 20, a material having a difference between the linear expansion coefficient of the support base material 10 and the linear expansion coefficient of the detection base material 20 of 1.2 × 10 ^-5 / ° C. or less is used. ..
In the first embodiment, a case where the material forming the detection base material 20 and the material forming the support base material 10 are the same material will be described.

(Membrane)
The membrane 22 is formed in a plate shape.
In the first embodiment, a case where the membrane 22 is formed in a disk shape will be described as an example.
The membrane 22 is an n-type semiconductor layer.
Receptors 30 are formed, for example, by coating on one surface of the membrane 22 (upper surface in FIG. 1).
The receptor 30 (receptor) is formed by using, for example, a polyethyleneimine (PEI) solution, and distortion occurs due to adsorption of gas molecules.
When gas molecules are adsorbed on the receptor 30 and strain is generated in the receptor 30, surface stress is applied to the membrane 22, and the membrane 22 bends. Therefore, when gas molecules are adsorbed on the receptor 30, the membrane 22 bends due to the applied surface stress.
The structure of the receptor 30 is not limited to the structure in which strain is generated by adsorbing gas molecules, and may be, for example, a structure in which strain is generated by magnetism. That is, the configuration of the receptor 30 may be appropriately changed according to the detection target of the surface stress sensor 1.

(Frame member)
The frame member 24 is formed in a grid shape and surrounds the membrane 22 with a gap when viewed from the thickness direction of the membrane 22.
The viewpoint viewed from the thickness direction of the membrane 22 is a viewpoint viewed from above the surface stress sensor 1 (in FIG. 1, a viewpoint viewed from the direction of arrow II).
When viewed from the thickness direction of the membrane 22, the center of the frame member 24 overlaps the center of the membrane 22.
Further, the frame member 24 is connected to the surface of the support base material 10 opposite to the surface facing the package substrate 2 (upper surface in FIG. 1) by using various joining techniques such as adhesion. ing.

In the first embodiment, as an example, when the shapes of the frame member 24 and the support base material 10 are viewed from the thickness direction of the membrane 22, the outer peripheral surface of the support base material 10 and the outer peripheral surface of the frame member 24 are flush with each other. The case where the shape is formed is described.
That is, the frame member 24 and the supporting base material 10 are quadrilaterals having the same shape when viewed from the thickness direction of the membrane 22. This is achieved, for example, by connecting the frame member 24 and the support base material 10 and then dicing the frame member 24 and the support base material 10. That is, when viewed from the thickness direction of the membrane 22, the center of the frame member 24 overlaps with the center of the supporting base material 10.

Therefore, the support base material 10 overlaps the membrane 22 and the frame member 24 when viewed from the thickness direction of the membrane 22.
Further, the connecting portion 4 is arranged at a position overlapping with at least a part of the membrane 22 when viewed from the thickness direction of the membrane 22.
Further, the area of the connecting portion 4 is smaller than the area of the membrane 22 when viewed from the thickness direction of the membrane 22.
Further, the package substrate 2 is connected to a surface (lower surface in FIG. 1) opposite to the surface of the support base material 10 facing the membrane 22.

(Connecting part)
The connecting portion 26 is formed in a band shape when viewed from the thickness direction of the membrane 22.
Further, the connecting portion 26 is arranged at a position overlapping the virtual straight lines VL1 and VL2 passing through the center of the membrane 22 when viewed from the thickness direction of the membrane 22, and connects the membrane 22 and the frame member 24. ing.
In the first embodiment, as an example, a case where the membrane 22 and the frame member 24 are connected by two pairs of four connecting portions 26a to 26d will be described.
The four connecting portions 26a to 26d are a pair of connecting portions 26a and 26b arranged at positions overlapping the straight line VL1 and a pair of connecting portions 26c arranged at positions overlapping the straight line VL2 orthogonal to the straight line VL1. And the connecting portion 26d.
That is, the pair of connecting portions 26a and 26b, and the pair of connecting portions 26c and connecting portions 26d are arranged at positions sandwiching the membrane 22 when viewed from the thickness direction of the membrane 22, and the membrane 22 and the frame member. 24 is connected.

In the first embodiment, as an example, a case where the width of the connecting portion 26a and the connecting portion 26b is narrower than the width of the connecting portion 26c and the connecting portion 26d will be described.
A gap 40 is provided between the membrane 22 and the four connecting portions 26a to 26d and the supporting base material 10.
When the surface stress sensor 1 is used in a solution, the void 40 may be filled with the solution.
The gap 40 functions as a space for preventing the membrane 22 from sticking to the support base 10 when the membrane 22 bends toward the support base 10 during processing of the detection base 20.
The four connecting portions 26a to 26d are provided with flexible resistors 50a to 50d, respectively.

(Flexible resistance)
The resistance value of each flexible resistor 50 changes according to the deflection that occurs in the connecting portion 26.
In the first embodiment, as an example, a case where the flexible resistor 50 is formed by the piezoresistive resistor will be described.
The piezoresistive effect is formed, for example, by injecting ions into the connecting portion 26, and has a resistance value that changes according to the bending caused in the connecting portion 26 due to the bending of the membrane 22.
The flexible resistor 50 is a p-type semiconductor layer.
The four flexible resistors 50a to 50d are, for example, as shown in FIG. 5, flexible resistors 50 adjacent to each other (connecting portion 26a and connecting portion 26c and connecting portion 26d, connecting portion 26b and connecting portion 26c, and The connecting portion 26d) is connected. As a result, the four flexible resistors 50a to 50d form the full Wheatstone bridge shown in FIG.

(Piezoresistive effect)
Hereinafter, the detailed configuration of the piezoresistive device will be described.
The resistance value (R) of the piezoresistive effect and the relative resistance change (ΔR / R) of the resistance value of the piezoresistive effect are given by the following equations (1) to (3).

In equations (1) to (3), ρ is the resistance of the piezoresistive effect, l is the length of the piezoresistive effect, w is the width of the piezoresistive effect, t is the thickness of the piezoresistive effect, and σ is induced by the piezoresistive effect. The stress to be generated, ε is the strain induced by the piezoresistive effect, and π is the piezoresistive constant.
Further, in equations (1) to (3), x corresponds to the longitudinal direction of the cantilever, y corresponds to the lateral direction of the cantilever, and z corresponds to the normal direction of the cantilever.
The relationship between strain and stress can be derived from the generalized Hooke's law.

In formulas (4) to (6), E is the Young's modulus of the cantilever and ν is the Poisson's ratio of the cantilever. Therefore, assuming that it is a plane stress (that is, σz = 0), the relative resistance change can be described by the following equation (7).

Here, in order to acquire a large signal and make the best use of the high piezo coefficient of silicon, the piezoresistive effect of forming the p-type semiconductor layer by being formed using single crystal Si (100) is examined. .. The piezoresistive coefficient is determined by the relationship represented by the following equations (8) and (9).

In equations (8) and (9), π11, π12 and π44 are the basic piezoresistive coefficients of the crystal. When the x-direction is the p-type Si (100) aligned with [110] and the y-direction is the p-type Si (100) aligned with [1-10], π11 is in units of 10-11 Pa-1. As +6.6. In addition to this, π12 is −1.1 in units of 10-11Pa-1, and π44 is +138.1 in units of 10-11Pa-1.
Therefore, the piezoresistive coefficient πx is calculated as 71.8 × 10-11Pa-1, and the piezoresistive coefficient πy is calculated as -66.3 × 10-11Pa-1. Further, E is 1.70 × 1011 Pa, and ν is 0.28. Then, πx >> (1 + 2ν) / E, πy >> -1 / E, and πx≈−πy≈π44 / 2, so the equation (7) is shown by the following equation (10). It is possible to approximate to.

したがって、ピエゾ抵抗の信号（すなわち、ΔＲ／Ｒ）は、主にσｘとσｙの差によって決まる。

Therefore, the piezoresistive signal (ie, ΔR / R) is mainly determined by the difference between σx and σy.

(Manufacturing method of surface stress sensor)
A method for manufacturing the surface stress sensor 1 will be described with reference to FIGS. 1 to 5 and FIGS. 6 to 12. 6 to 12 are cross-sectional views corresponding to the positions of the X-ray cross section of FIG.
The method for manufacturing the surface stress sensor 1 includes a laminate forming step, a first ion implantation step, a second ion implantation step, a heat treatment step, a wiring layer forming step, and a removing step.

(Laminate body forming process)
In the laminate forming step, first, as shown in FIG. 6A, a recess 62 (trench) is formed on one surface of the first silicon substrate 60, which is the material of the support base material 10, by using lithography and etching techniques. Form. The depth of the recess 62 is set to, for example, 7 [μm].
Next, the second silicon substrate 64, which is the material of the detection base material 20, is bonded to the first silicon substrate 60 on which the recess 62 is formed by using various bonding techniques such as adhesion, whereby FIG. 6 (b) ), The laminated body 66 (Cavity wafer) is formed.

As described above, by performing the laminate forming step, a gap 40 whose top, bottom, left and right are surrounded by silicon (first silicon substrate 60, second silicon substrate 64) is formed at a predetermined position of the laminate 66. Will be done.
As described above, in the laminate forming step, the recess 62 is formed on one surface of the support base material 10, and the detection base material 20 is attached to the support base material 10 so as to cover the recess 62, thereby supporting the support base material. A laminated body 66 having a gap 40 provided between the 10 and the detection base material 20 is formed.

(First ion implantation process)
In the first ion implantation step, first, as shown in FIG. 7, the upper surface of the second silicon substrate 64 is oxidized to form the first silicon oxide film 68a, and a photoresist pattern (not shown) is formed. The first ion is selectively implanted into the flexible resistance region 70.
As described above, in the first ion implantation step, among the surfaces of the detection base material 20 opposite to the surface facing the support base material 10, a selected region outside the preset region including the center of the detection base material 20 is selected. The first ion is implanted into the region of the portion (flexible resistance region 70).

(Second ion implantation process)
In the second ion implantation step, the photoresist used in the first ion implantation step was removed, and a photoresist pattern (not shown) different from that used in the first ion implantation step was formed, and FIG. 7 As shown inside, the second ion is implanted into the low resistance region 72.
As described above, in the second ion implantation step, the second ion is implanted into the selected region outside the region (flexible resistance region 70) in which the first ion is implanted in the detection substrate 20.

(Heat treatment process)
In the heat treatment step, the photoresist used in the second ion implantation step is removed, and further, the laminate 66 is heat-treated (annealed) for the purpose of activating the first ion and the second ion. After the laminate 66 is heat-treated, the first silicon oxide film 68a is removed.
As described above, in the heat treatment step, the laminated body 66 in which the first ion and the second ion are injected is heat-treated to form the flexible resistance region 70 in the region in which the first ion is injected, and the second A low resistance region 72 is formed in the region in which the ions of the above are injected.

(Wiring layer forming process)
In the wiring layer forming step, as shown in FIG. 8A, the silicon nitride film 74 and the second silicon oxide film 68b are laminated in order on the upper surface of the second silicon substrate 64. Then, as shown in FIG. 8B, holes 76 are formed in the second silicon oxide film 68b by ordinary lithography and oxide film etching.
Next, as shown in FIG. 9A, a laminated film 78 formed of Ti and TiN is formed on the second silicon oxide film 68b by sputtering, and heat treatment is performed. The laminated film 78 is a so-called barrier metal having a role of preventing a metal film such as Al from abnormally diffusing into Si, and by performing heat treatment, the interface between Si and Ti existing at the bottom of the hole 76 is silicide. It is possible to form a low resistance connection.
Further, as shown in FIG. 9B, a metal film 80 such as Al is laminated on the laminated film 78 by sputtering.

Next, the wiring layer 82 as shown in FIG. 10A is formed by patterning the metal film 80 using photolithography and etching techniques. Further, as shown in FIG. 10B, a third silicon oxide film 68c is laminated as an insulating layer.
After that, as shown in FIG. 11A, a photoresist that covers a region other than the membrane setting region 84, which is a preset region (a region that later becomes a membrane) including the flexible resistance region 70 and the center of the detection substrate. Pattern (not shown) is formed. Further, the second silicon oxide film 68b formed in the flexible resistance region 70 and the membrane setting region 84 is removed by an etching technique. Then, a photoresist pattern (not shown) that covers other than the membrane setting region 84 is formed, and the silicon nitride film 74 in the membrane setting region 84 is removed as shown in FIG. 11B.
Next, as shown in FIG. 12, a PAD 86 for obtaining an output from the flexible resistor 50 is formed by ordinary photolithography and etching techniques.
As described above, in the wiring layer forming step, the wiring layer 82 electrically connected to the flexible resistor 50 is formed.

(Removal process)
In the removing step, a part of the membrane setting region 84 is cut out by etching to pattern two pairs of four connecting portions 26a to 26d.
Therefore, in the removing step, the membrane 22 and the frame member are removed by removing the regions other than the low resistance region 72 and the flexible resistance region 70 (the region that later becomes the connecting portion 26) around the membrane setting region 84. 24, the connecting portion 26, and the flexible resistor 50 are formed.

(Operation / action)
The operation and operation of the first embodiment will be described with reference to FIGS. 1 to 12 with reference to FIGS. 13 and 14.
When the surface stress sensor 1 is used as, for example, a sensory sensor, the receptor 30 is arranged in an atmosphere of a gas containing an odor component, and the odor component contained in the gas is adsorbed on the receptor 30.
When gas molecules are adsorbed on the receptor 30 and strain is generated in the receptor 30, surface stress is applied to the membrane 22, and the membrane 22 bends.
The frame member 24 is formed in a grid shape and surrounds the membrane 22, and the connecting portion 26 connects the membrane 22 and the frame member 24 at both ends. Therefore, of the connecting portions 26, the end portion connected to the membrane 22 is a free end, and the end portion connected to the frame member 24 is a fixed end.

Therefore, when the membrane 22 bends, the connecting portion 26 bends according to the strain generated in the receptor 30. Then, the resistance value of the flexible resistor 50 changes according to the bending generated in the connecting portion 26, and the voltage change corresponding to the change in the resistance value is output from the PAD 86 and used for data detection in a computer or the like. ..
When the surface stress sensor 1 is used, the package substrate 2 may be deformed (shrinked, stretched, warped) due to, for example, a temperature change generated in the environment in which the surface stress sensor 1 is used.

In the structure of the surface stress sensor 100 having the conventional configuration, that is, in the structure in which the support base material 10 is formed in a cylindrical shape and the membrane 22 is floated in the air, for example, as shown in FIG. 13 (a). The following problems occur. That is, in the surface stress sensor 100 having the conventional configuration, as shown in FIG. 13B, when the package substrate 2 is deformed (shrinked), the support base material 10 is also deformed along with the deformation of the package substrate 2. .. Since the membrane 22 is floating in the air and only a space exists between the membrane 22 and the package substrate 2, the supporting base material 10 is allowed to be deformed, and the membrane 22 is greatly bent. Become. That is, the deformation of the package substrate 2 is applied to the membrane 22 as stress. As a result, an offset is given to the output of the voltage or current due to the flexible resistor 50, and the offset changes according to the temperature change, so that the accuracy of the surface stress sensor 1 deteriorates.

Therefore, in the surface stress sensor 100 having the conventional configuration, the membrane 22 is greatly deformed due to the change in the stress received from the deformed package substrate 2, and the characteristics of the surface stress sensor 100 are changed. Therefore, the characteristics of the surface stress sensor 100 change between the inspection and the mounting of the surface stress sensor 100, which makes it difficult to inspect and calibrate the surface stress sensor 100 at the time of shipment.

On the other hand, in the surface stress sensor 1 of the first embodiment, as shown in FIG. 14A, the supporting base material 10 exists between the membrane 22 and the package substrate 2. Further, since the support base material 10 is formed in a columnar shape, it has higher rigidity than a structure in which the support base material 10 is formed in a cylindrical shape like the surface stress sensor 100 having a conventional structure. doing.
Therefore, in the surface stress sensor 1 of the first embodiment, as shown in FIG. 14B, the support base material 10 has high rigidity even when the package substrate 2 is deformed (shrinked). Therefore, the deformation of the supporting base material 10 is suppressed, and the bending of the membrane 22 is suppressed.

Further, in the surface stress sensor 1 of the first embodiment, since the supporting base material 10 has high rigidity, it becomes insensitive to stress changes of the package substrate 2 due to temperature changes and the like, and highly accurate and stable sensing is possible. It becomes.
Further, in the case of the surface stress sensor 1 of the first embodiment, the supporting base material 10 becomes insensitive to stress changes of the package substrate 2 due to temperature changes and the like, and the configuration (strength, material, thickness, etc.) of the package substrate 2 becomes insensitive. ) Is not easily affected. Therefore, it can be used for a package substrate 2 having a wide variety of configurations.
Further, in the surface stress sensor 1 of the first embodiment, the center of the support base material 10 overlaps with the position where the connecting portion 4 is arranged. In addition to this, the area of the supporting base material 10 is larger than the area of the connecting portion 4.

Therefore, the stress generated by the deformation of the package substrate 2 transmitted to the support base material 10 via the connecting portion 4 is reduced as compared with the stress generated in the entire package base material 2, and thus the support base material is reduced. The deformation of the 10 is suppressed, and the bending of the membrane 22 is suppressed.
Therefore, in the configuration of the first embodiment, it is possible to reduce the stress applied to the membrane 22 due to the deformation of the package substrate 2 and suppress the deterioration of the measurement accuracy of the surface stress sensor 1.

In addition, in collecting IoT-related information that can be applied to technological development and business, the technology that senses information equivalent to the five human senses is compared with the visual, auditory, and tactile senses of the five senses. It can be applied to taste and smell sensors, which are not always common.
The above-mentioned first embodiment is an example of the present invention, and the present invention is not limited to the above-mentioned first embodiment, and even if it is an embodiment other than this embodiment, it relates to the present invention. As long as it does not deviate from the technical idea, various changes can be made according to the design and the like.

(Effect of the first embodiment)
The surface stress sensor 1 of the first embodiment can achieve the effects described below.
(1) The membrane 22 that bends due to the applied surface stress, the frame member 24 that surrounds the membrane 22, the connecting portion 26 that connects the membrane 22 and the frame member 24, and the bending that occurs in the connecting portion 26. A flexible resistor 50 having a variable resistance value is provided. Further, the support base material 10 which is connected to the frame member 24 and overlaps with the membrane 22 when viewed from the thickness direction of the membrane 22 is provided. In addition to this, a gap 40 is provided between the membrane 22 and the support base material 10.

Therefore, the support base material 10 has a structure having high rigidity, becomes insensitive to stress changes of the package substrate 2 due to temperature changes and the like, and enables highly accurate and stable sensing.
As a result, it is possible to provide the surface stress sensor 1 capable of reducing the stress applied to the membrane 22 due to the deformation of the package substrate 2 and suppressing the deterioration of the measurement accuracy.
Further, it is possible to prevent the surface stress sensor 1 manufactured by the semiconductor process from changing its characteristics before and after assembling into a package or the like. Further, since the rigidity of the surface stress sensor 1 itself can be improved, it is possible to prevent problems that occur during handling, such as damage during handling.

(2) The flexible resistance 50 is a piezoresistor having a resistance value that changes according to the bending caused in the connecting portion 26 due to the bending of the membrane 22.
As a result, it became possible to detect the relative resistance change of the resistance value of the piezoresistive effect by using the stress in the X direction and the Y direction induced by the piezoresistive effect, and the target molecule was adsorbed on the receptor 30. It is possible to determine whether or not.

(3) The membrane 22 and the frame member 24 are connected by two pairs of four connecting portions 26a to 26d, and flexible resistors 50 are provided in each of the four connecting portions 26a to 26d. The two flexible resistors 50 form a full Wheatstone bridge.
Since R1 and R3 have a large deflection in the X direction and R2 and R4 have a large deflection in the Y direction, the relative resistance changes are opposite in R1 and R2, and in R3 and R4, respectively. The voltage of the output terminal Vout that divides the applied voltage VB between R1 and R2 changes by exerting a synergistic effect of R1 and R2 whose increase and decrease are opposite. The same can be said for the division between R3 and R4. Since both Vout voltages change in opposite directions, the full Wheatstone bridge is advantageous in that as a result both Vout voltages are added together and all four piezoresistive changes contribute positively and increase sensitivity.

(4) The membrane 22 is an n-type semiconductor layer, and the flexibility resistor 50 is a p-type semiconductor layer.
As a result, the current flowing through the flexible resistor 50 does not flow through the membrane 22, and no noise is generated in the output voltage. Further, by using a p-type semiconductor for the flexible resistor 50, it is possible to realize higher sensitivity than using an n-type semiconductor.
(5) The material forming the detection base material 20 and the material forming the support base material 10 are the same material.
As a result, it is possible to reduce the difference between the deformation amount of the detection base material 20 and the deformation amount of the support base material 10 according to the deformation of the package substrate 2 due to the temperature change or the like, and the bending of the membrane 22 is suppressed. It becomes possible to do.

(6) The coefficient of linear expansion of the supporting base material 10 is 5.0 × 10 ^-6 / ° C. or less.
As a result, the rigidity of the support base material 10 can be improved, and the amount of deformation of the detection base material 20 with respect to the deformation of the package substrate 2 due to a temperature change or the like can be reduced.
(7) The thickness of the supporting base material 10 is 80 μm or more.
As a result, the rigidity of the support base material 10 can be improved, and the amount of deformation of the detection base material 20 with respect to the deformation of the package substrate 2 due to a temperature change or the like can be reduced.

(8) When viewed from the thickness direction of the membrane 22, the outer peripheral surface of the support base material 10 and the outer peripheral surface of the frame member 24 are flush with each other.
As a result, it becomes possible to separate the pieces using a dicing device used in ordinary semiconductor manufacturing.
(9) The supporting base material 10 is formed of a material containing any one of silicon, sapphire, gallium arsenide, glass, and quartz.
As a result, it becomes easy to secure the conductivity required for the surface stress sensor 1.

(10) A package substrate 2 connected to a surface of the support base material 10 opposite to the surface facing the membrane 22 is further provided.
As a result, the surface stress sensor 1 can be easily mounted on various sensors.
(11) The support base material 10 and the package base material 2 are connected by a connecting portion 4 arranged at a position overlapping with at least a part of the membrane 22 when viewed from the thickness direction of the membrane 22.
As a result, it is possible to connect the support base material 10 and the package base material 2 without using a bracket or the like, and it is possible to suppress the complexity of the configuration.

(12) The area of the connecting portion 4 is smaller than the area of the membrane 22 when viewed from the thickness direction of the membrane 22.
Therefore, the stress generated by the deformation of the package substrate 2 transmitted to the support base material 10 via the connecting portion 4 can be reduced from the stress generated by the entire package substrate 2.
As a result, it is possible to suppress the deformation of the supporting base material 10 and suppress the bending of the membrane 22.
Further, according to the method for manufacturing the surface stress sensor of the first embodiment, the effects described below can be obtained.

(13) A laminate forming step, a first ion implantation step, a second ion implantation step, a heat treatment step, a wiring layer forming step, and a removing step are provided. In the laminate forming step, a recess 62 is formed on one surface of the support base material 10, and further, the detection base material 20 is attached to the support base material 10 so as to cover the recess 62, thereby detecting the support base material 10. A laminated body 66 having a gap 40 provided between the base material 20 and the base material 20 is formed. In the first ion implantation step, in a part of the surface of the detection base material 20 opposite to the surface facing the support base material 10 and outside the preset region including the center of the detection base material 20. , Inject the first ion. In the second ion implantation step, the second ion is implanted into the selected region outside the region in which the first ion is implanted in the detection substrate 20. In the heat treatment step, the laminated body 66 in which the first ion and the second ion are injected is heat-treated to form a flexible resistance region 70 in the region in which the first ion is injected, and the second ion is formed. A low resistance region 72 is formed in the injected region. In the wiring layer forming step, the wiring layer 82 electrically connected to the flexible resistor 50 is formed. In the removing step, the membrane 22, the frame member 24, and the connecting portion are removed by removing the regions other than the low resistance region 72 and the flexible resistance region 70 around the preset region including the center of the detection base material 20. 26 and flexible resistor 50 are formed.

Therefore, the support base material 10 has a structure having high rigidity, becomes insensitive to stress changes of the package substrate 2 due to temperature changes and the like, and enables highly accurate and stable sensing.
As a result, it is possible to provide a method for manufacturing a surface stress sensor, which can reduce the stress applied to the membrane 22 due to the deformation of the package substrate 2 and suppress the deterioration of the measurement accuracy.
Further, it is possible to prevent the surface stress sensor 1 manufactured by the semiconductor process from changing its characteristics before and after assembling into a package or the like. Further, since the rigidity of the surface stress sensor 1 itself can be improved, it is possible to prevent problems that occur during handling, such as damage during handling.

(Modified example of the first embodiment)
(1) In the first embodiment, a gap portion 40 is formed between the membrane 22 and the support base material 10 by forming a recess 62 on one surface of the first silicon substrate 60 which is a material of the support base material 10. Formed, but not limited to this. That is, by forming a recess on the surface of the second silicon substrate 64, which is the material of the detection base material 20, facing the support base material 10, a gap 40 is formed between the membrane 22 and the support base material 10. May be good.
(2) In the first embodiment, the two pairs of the four connecting portions 26a to 26d are provided with the flexible resistors 50a to 50d, respectively, but the present invention is not limited to this. That is, a pair of two connecting portions 26 may be provided with a flexible resistor 50, respectively.

(3) In the first embodiment, all of the four connecting portions 26a to 26d are provided with the flexible resistor 50, but the present invention is not limited to this, and at least one connecting portion 26 can be used. It may be configured to be provided with a flexible resistor 50.
(4) In the first embodiment, the area of the connecting portion 4 is set to a value smaller than the area of the membrane 22 when viewed from the thickness direction of the membrane 22, but the value is not limited to this, and the connecting portion 4 is not limited to this. The area may be equal to or larger than the area of the membrane 22.
(5) In the first embodiment, the shape of the connecting portion 4 is circular, but the shape is not limited to this, and the shape of the connecting portion 4 may be, for example, a square. Further, a plurality of connecting portions 4 may be formed.

(6) In the first embodiment, the material forming the detection base material 20 and the material forming the support base material 10 are the same material, but the material is not limited to this, and the detection base material 20 is used. The material to be formed and the material to form the support base material 10 may be different materials.
In this case, the difference between the coefficient of linear expansion of the detection base material 20 and the coefficient of linear expansion of the support base material 10 is set to 1.2 × 10 ⁻⁵ / ° C. or less, so that the detection group corresponds to the deformation of the package substrate 2. It is possible to reduce the difference between the amount of deformation of the material 20 and the amount of deformation of the supporting base material 10. This makes it possible to suppress the bending of the membrane 22.

(7) In the first embodiment, the coefficient of linear expansion of the support base material 10 is 5.0 × 10 ^-6 / ° C. or less, but the present invention is not limited to this, and the linear expansion coefficient of the support base material 10 is not limited to this. , 1.0 × ^10-5 / ° C. or less.
Even in this case, the rigidity of the support base material 10 can be improved, and the amount of deformation of the detection base material 20 with respect to the deformation of the package substrate 2 due to a temperature change or the like can be reduced.

(Second Embodiment)
Hereinafter, the second embodiment of the present invention will be described with reference to the drawings.
(composition)
The configuration of the second embodiment will be described with reference to FIGS. 1 to 5 with reference to FIG.
In the configuration of the second embodiment, as shown in FIG. 15, the frame member 24 has a surface opposite to the surface of the support base material 10 facing the package substrate 2 via the connecting layer 90 (in FIG. 15, in FIG. 15). It is the same as the first embodiment described above except that it is connected to the upper surface).
The connection layer 90 is _{formed by using silicon dioxide (SiO 2} ) or the like.
Since other configurations are the same as those of the first embodiment described above, the description thereof will be omitted.

(Manufacturing method of surface stress sensor)
A method for manufacturing the surface stress sensor 1 will be described with reference to FIGS. 1 to 15 and FIGS. 16 to 19. The cross-sectional views of FIGS. 16 to 19 correspond to the cross-sectional views taken along line XX of FIG.
The method for manufacturing the surface stress sensor 1 includes a laminate forming step, a first ion injection step, a second ion injection step, a heat treatment step, a hole forming step, a void forming step, and a hole sealing step. It includes a wiring layer forming step and a removing step.

(Laminate body forming process)
In the laminate forming step, first, as shown in FIG. 16, the sacrificial layer 92 formed by using the silicon oxide film is laminated on the first silicon substrate 60 which is the material of the support base material 10. Further, the second silicon substrate 64, which is the material of the detection base material 20, is laminated on the sacrificial layer 92. As the sacrificial layer 92, a silicon nitride film or a metal film such as aluminum, titanium, copper, or tungsten may be used in addition to the silicon oxide film.
As described above, in the laminate forming step, the sacrificial layer 92 is laminated on the support base material 10, and the detection base material 20 is further laminated on the sacrificial layer 92 to form the laminate 66.

(First ion implantation process)
In the first ion injection step, as shown in FIG. 16, first, by oxidizing the second silicon substrate 64, the upper surface of the second silicon substrate 64 is oxidized to form the first silicon oxide film 68a. ..
Next, a photoresist pattern (not shown) is formed on the second silicon substrate 64 on which the first silicon oxide film 68a is formed, and the first is selectively selected with respect to the flexible resistance region 70. Inject the ions of.
As described above, in the first ion implantation step, among the surfaces of the detection base material 20 opposite to the surface facing the support base material 10, a selected region outside the preset region including the center of the detection base material 20 is selected. The first ion is implanted into the region of the portion (flexible resistance region 70).

(Second ion implantation process)
In the second ion implantation step, the photoresist used in the first ion implantation step is removed, and a photoresist pattern (not shown) different from that used in the first ion implantation step is formed, resulting in low resistance. The second ion is implanted into the region 72.
As described above, in the second ion implantation step, the second ion is implanted into the selected region outside the region (flexible resistance region 70) in which the first ion is implanted in the detection substrate 20.

(Heat treatment process)
In the heat treatment step, the photoresist used in the second ion implantation step is removed, and further, the laminate 66 is heat-treated (annealed) for the purpose of activating the first ion and the second ion. After the laminate 66 is heat-treated, the first silicon oxide film 68a is removed.
As described above, in the heat treatment step, the laminated body 66 in which the first ion and the second ion are injected is heat-treated to form the flexible resistance region 70 in the region in which the first ion is injected, and the second A low resistance region 72 is formed in the region in which the ions of the above are injected.

(Hole forming process)
In the hole forming step, a hole pattern (not shown) is formed on the upper surface of the second silicon substrate 64 by a general photolithography technique.
Next, dry etching is performed using the hole pattern as a mask to form holes 76 in the second silicon substrate 64 as shown in FIG. The diameter of the hole 76 is set to, for example, 0.28 [μm] so as to reach the sacrificial layer 92.
As described above, in the hole forming step, the hole 76 penetrating to the sacrificial layer 92 is formed in the region adjacent to the region where the flexible resistance region 70 and the low resistance region 72 of the detection base material 20 are formed.

(Void formation step)
In the gap forming step, only the sacrificial layer 92 is selectively etched by infiltrating the HF Vapor into the side of the first silicon substrate 60 through the hole 76, and as shown in FIG. 18, the first silicon substrate 60 and the first silicon substrate 60 are etched. (Ii) A gap 40 is formed between the silicon substrate 64 and the silicon substrate 64.
Here, the reason why the Wet etching of HF is not used is to avoid the occurrence of a problem (also referred to as stiction) in which the void 40 is crushed by the surface tension of pure water or the like during drying after the void 40 is formed. Because.
As described above, in the gap forming step, the sacrificial layer 92 arranged between the flexible resistance region 70 and the support base material 10 is removed by etching through the hole 76, and the support base material 10 and the detection group are removed. A gap 40 is provided between the material 20 and the material 20.

(Hole sealing process)
In the hole sealing step, as shown in FIG. 19, the hole 76 is sealed by the oxide film 94.
As a method for sealing the holes 76, for example, it is effective to combine thermal oxidation treatment and CVD, but when the diameter of the holes 76 is small, it is also possible to use only CVD.
As described above, in the hole sealing step, the oxide film 94 is formed on the surface of the detection base material 20 opposite to the surface facing the support base material 10, and the holes 76 are sealed.

(Wiring layer forming process)
Since the wiring layer forming step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
As described above, in the wiring layer forming step, the wiring layer 82 electrically connected to the flexible resistor 50 is formed.
(Removal process)
Since the removal step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
Therefore, in the removing step, the membrane 22, the frame member 24, and the membrane 22 and the frame member 24 are removed by removing the regions other than the low resistance region 72 and the flexible resistance region 70 around the preset region including the center of the detection base material 20. The connecting portion 26 and the flexible resistor 50 are formed.

(Operation / action)
Since the operation and operation of the second embodiment are the same as those of the first embodiment described above, the description thereof will be omitted.
The above-mentioned second embodiment is an example of the present invention, and the present invention is not limited to the above-mentioned second embodiment, and even if it is an embodiment other than this embodiment, it relates to the present invention. As long as it does not deviate from the technical idea, various changes can be made according to the design and the like.

(Effect of the second embodiment)
According to the method for manufacturing the surface stress sensor of the second embodiment, the effects described below can be obtained.
(1) Laminated body forming step, first ion injection step, second ion injection step, heat treatment step, hole forming step, void forming step, hole sealing step, wiring layer forming step, It has a removal step. In the laminate forming step, the sacrificial layer 92 is laminated on the support base material 10, and the detection base material 20 is further laminated on the sacrificial layer 92 to form the laminate 66. In the first ion implantation step, in a part of the surface of the detection base material 20 opposite to the surface facing the support base material 10 and outside the preset region including the center of the detection base material 20. , Inject the first ion. In the second ion implantation step, the second ion is implanted into the selected region outside the region in which the first ion is implanted in the detection substrate 20. In the heat treatment step, the laminated body 66 in which the first ion and the second ion are injected is heat-treated to form a flexible resistance region 70 in the region in which the first ion is injected, and the second ion is formed. A low resistance region 72 is formed in the injected region. In the hole forming step, a hole 76 penetrating to the sacrificial layer 92 is formed in a region adjacent to the region where the flexible resistance region 70 and the low resistance region 72 of the detection base material 20 are formed. In the gap forming step, the sacrificial layer 92 arranged between the flexible resistance region 70 and the support base material 10 is removed by etching through the holes 76, and the support base material 10 and the detection base material 20 are used. A gap 40 is provided between the two. In the hole sealing step, the oxide film 94 is formed on the surface of the detection base material 20 opposite to the surface facing the support base material 10, and the holes 76 are sealed. In the wiring layer forming step, the wiring layer 82 electrically connected to the flexible resistor 50 is formed. In the removing step, the membrane 22 and the frame member 24 are removed by removing the regions other than the low resistance region 72 and the flexible resistance region 70 around the preset membrane setting region 84 including the center of the detection base material 20. , The connecting portion 26 and the flexible resistor 50 are formed.

Therefore, the support base material 10 has a structure having high rigidity, becomes insensitive to stress changes of the package substrate 2 due to temperature changes and the like, and enables highly accurate and stable sensing.
As a result, it is possible to provide a method for manufacturing a surface stress sensor, which can reduce the stress applied to the membrane 22 due to the deformation of the package substrate 2 and suppress the deterioration of the measurement accuracy.
Further, it is possible to prevent the surface stress sensor 1 manufactured by the semiconductor process from changing its characteristics before and after assembling into a package or the like. Further, since the rigidity of the surface stress sensor 1 itself can be improved, it is possible to prevent problems that occur during handling, such as damage during handling.

(Third Embodiment)
Hereinafter, the third embodiment of the present invention will be described with reference to the drawings.
In the surface stress sensor 1 according to the first embodiment, a BOX (Buried Oxide) layer may be provided on the surface of the support base material 10 for the purpose of insulating the support base material 10 and the detection base material 20. The BOX layer is formed, for example, by thermally oxidizing a Si substrate. Since the thermal oxidation of Si induces stress in the Si crystal, the BOX layer may cause the membrane of the surface stress sensor to bend. The bending of the membrane due to the stress of the BOX layer becomes an offset in the surface stress sensor, and the improvement of the detection accuracy of the surface stress sensor is suppressed.
The surface stress sensor according to the third embodiment of the present invention can suppress a decrease in measurement accuracy of the surface stress sensor due to the BOX layer in a configuration in which the BOX layer is provided on the surface of the supporting base material.

(composition)
The configuration of the third embodiment will be described with reference to FIGS. 1 to 5 with reference to FIGS. 20 and 21. FIG. 20 is a cross-sectional view showing a cross section of the surface stress sensor 101 according to the third embodiment. FIG. 21 is a plan view of the surface stress sensor 101 shown in FIG. Note that in FIGS. 20 and 21, the wiring layer formed on the upper surface of the surface stress sensor 101 is not shown.

As shown in FIG. 20, the surface stress sensor 101 includes a connection layer 111 which is a BOX layer on the surface of the support base material 10, and a plurality of surface stress sensors 101 are provided on one support base material 10. (For example, two) sensor units are provided. That is, in the surface stress sensor 101, the support base material 10 is provided with a plurality of voids 40 (41, 42), and the membrane 122a on which the receptors 30a are provided on the voids 41 and 42 and the membrane 122a on the upper surface are received. A membrane 122b on which the body 30b is provided is provided, respectively. As a result, the surface stress sensor 101 is configured so that the receptor 30a and the receptor 30b can be formed of different materials to detect different types of gas. Further, in the surface stress sensor 101, the receptor 30a and the receptor 30b may be formed of the same material. The membranes 122a and 122b correspond to the membrane 22 of the first embodiment, the receptors 30a and 30b correspond to the receptor 30 of the first embodiment, and the voids 41 and 42 correspond to the voids 40 of the first embodiment. The description will be omitted in order to correspond to.

(Connection layer)
The surface stress sensor 101 is provided with a connecting layer 111 on the surface of the supporting base material 10 facing the detection base material 120, and a part of the connecting layer 111 is removed to form grooves 125 and 127. Two trenches serving as voids 40 (41, 42) are formed on the surface of the surface of the support base material 10 facing the detection base material 120. The connection layer 111 (111a, 111b, 111c) is formed so as to cover the surface of the support base material 10 and the surface of the trench on the surface of the support base material 10 after the trench formation facing the detection base material 120. The connection layers 111a, 111b and 111c will be described later.
The connection layer 111 may be provided on the surface of the surface of the support base material 10 facing the package substrate 2 (lower surface in FIG. 20).

(Groove)
As shown in FIG. 21, the groove portions 125 and 127 are provided at positions surrounding each of the rectangular gap portions 41 and 42 in a plan view, and penetrate the frame member 124 and the connection layer 111 of the detection base material 120. It is formed. The groove portions 125 and 127 are formed by removing a part of each of the frame member 124 and the connecting layer 111. The groove portions 125 and 127 have an annular shape corresponding to the outer shape of the gap portions 41 and 42 in a plan view. For example, the groove portions 125 and 127 are formed in a rectangular ring shape having a rectangular outer shape in a plan view. The groove portions 125 and 127 are provided, for example, in the outer regions of the flexible resistors 50a to 50d around the gap portions 41 and 42 in a plan view.

As shown in FIG. 20, the connection layer 111 is separated by the groove portion 125 into a connection layer 111b located inside the groove portion 125 (the region on the membrane 122a formation side) and a connection layer 111a located outside the groove portion 125 in a plan view. NS. Further, the connection layer 111 is separated by the groove portion 127 into a connection layer 111c located inside the groove portion 127 (the region on the membrane 122b formation side) and a connection layer 111a located outside the groove portion 125 in a plan view.
Similarly, the frame member 124 is separated by the groove portion 125 into a frame member 124b located inside the groove portion 125 and a frame member 124a located outside the groove portion 125 in a plan view. Further, the frame member 124 is separated by the groove portion 127 into a frame member 124c located inside the groove portion 127 and a frame member 124a located outside the groove portion 127 in a plan view.
Hereinafter, when the connection layers 111a, 111b and 111c are not distinguished, they are referred to as connection layers 111. When the frame members 124a, 124b and 124c are not distinguished, they are referred to as frame members 124.

The frame member 124b located inside the groove 125 is connected to the membrane 122a by four (two pairs) connecting portions 26. Further, the frame member 124c located inside the groove portion 127 is connected to the membrane 122b by four (two pairs) connecting portions 26.

That is, in the surface stress sensor 101, the connection layer 111b and the frame member 124b located inside the groove 125 are separated from the connection layer 111a and the frame member 124a located outside the groove 125 having a large area and easily generating stress. There is. Therefore, even when stress is generated in the connection layer 111a, the stress can be released to the groove portion 125, and the influence of the stress generated in the connection layer 111a on the membrane 122a can be reduced.

The same can be said for the periphery of the groove portion 127. That is, in the surface stress sensor 101, the connection layer 111c and the frame member 124c located inside the groove 127 are separated from the connection layer 111a and the frame member 124a located outside the groove 127 having a large area and easily generating stress. .. Therefore, even when stress is generated in the connection layer 111a, the stress can be released to the groove portion 127, and the influence of the stress generated in the connection layer 111a on the membrane 122b can be reduced.

Further, it is preferable that the grooves 125 and 127 are provided at positions closer to the membranes 122a and 122b. With this configuration, the area of the connecting layers 111b and 111c can be made smaller, and the stress received by the membranes 122a and 122b from the connecting layers 111b and 111c can be made smaller. Therefore, by providing the groove portions 125 and 127, the stress received by the membranes 122a and 122b can be reduced as compared with the case where the groove portions 125 and 127 are not provided, and the offset of the surface stress sensor 101 can be reduced.
From the viewpoint of the bondability between the detection base material 120 and the support base material 10, the groove portions 125 and 127 may be provided in a region outside of the outer peripheral portions of the gap portions 41 and 42 by several tens of μm (for example, 40 μm) or more. preferable.

As shown in FIG. 21, the groove portion 125 is provided so that the distances L1 to L4 between the groove portion 125 and the outer circumference of the gap portion 41 are equal at any position between the groove portion 125 and the outer circumference of the gap portion 41. It is more preferable to be formed. That is, it is more preferable that the groove portion 125 is formed so that all the distances L1, L2, L3, and L4 shown in FIG. 21 are equal. Further, it is more preferable that the distances L1'to L4'between the groove portion 127 and the outer circumference of the gap portion 42 are formed to be equal at any position between the groove portion 127 and the outer circumference of the gap portion 42. .. That is, it is more preferable that the groove portion 127 is formed so that all the distances L1', L2', L3', and L4'shown in FIG. 21 are equal.
With this configuration, the stress applied from the periphery of the membrane 122a can be substantially equalized from any direction, and the stress applied from the periphery of the membrane 122b can be substantially equalized from any direction. Therefore, the offset can be isotropically reduced in each sensor portion of the surface stress sensor 101.

Further, it is more preferable that the distances L1 to L4 between the groove portion 125 and the outer circumference of the gap portion 41 and the distances L1'to L4'between the groove portion 127 and the outer circumference of the gap portion 42 are all uniformly formed.
With this configuration, it is possible to reduce the variation in offset between the sensor portion having the membrane 122a and the sensor portion having the membrane 122b.

(Modification example)
A part of the groove may be formed in common in the plurality of adjacent grooves. That is, in FIG. 21, the groove located on the right side of the adjacent groove portion 125 and the groove located on the left side of the groove portion 127 may be integrally formed. With this configuration, since the groove portion 125 and the groove portion 127 are formed in close contact with each other, the membranes 122a and 122b can be arranged closer to each other, and the surface stress sensor 101 can be miniaturized.

Further, the planar shape of the gaps 41 and 42 is not limited to a rectangle, and may be a circular shape or a polygonal shape. In this case, it is preferable that the groove portions 125 and 127 have shapes corresponding to the planar shapes of the gap portions 41 and 42, respectively. With this configuration, the stress applied from the periphery of the membranes 122a and 122b can be equalized, and the offset of the surface stress sensor 101 can be isotropically reduced.

Further, a part or all of the connection layer 111a and the frame member 124a located outside the grooves 125 and 127 may be removed. This configuration is preferable because stress is not applied to the membranes 122a and 122b from the outside of the grooves 125 and 127.
Further, if the stress effect from the connection layer 111a on the connection layers 111b and 111c is small, the connection layer 111a and the connection layers 111b and 111c do not have to be completely separated from each other. For example, a connecting portion (not shown) connecting the connecting layer 111a and the connecting layer 111b may be thinly formed on the bottom surface of the groove portion 125 (the surface of the supporting base material 10).

(Manufacturing method of surface stress sensor)
A method of manufacturing the surface stress sensor 101 will be described with reference to FIGS. 1 to 12 and FIGS. 20 and 21 with reference to FIGS. 22 and 23. The cross-sectional views of FIGS. 22 and 23 show a cross section in the vicinity of the gap 41 of FIG. 20 (the left side of the gap 41).
The method for manufacturing the surface stress sensor 101 includes a laminate forming step, a first ion implantation step, a second ion implantation step, a heat treatment step, a groove forming step, a wiring layer forming step, and a removing step.

(Laminate body forming process)
In the laminate forming step, first, as shown in FIG. 22A, a plurality of recesses 62 (trenches) are formed on one surface of the first silicon substrate 60, which is the material of the support base material 10, by using lithography and etching techniques. ) Is formed. Note that FIG. 22A shows only the recess 62 which will later become the gap 41.
Next, the first silicon substrate 60 on which the plurality of recesses 62 are formed is thermally oxidized to form a thermal oxide film 61 on at least the concave portion 62 forming surface of the first silicon substrate 60.

Next, as shown in FIG. 22B, the second silicon substrate 64, which is the material of the detection base material 20, is adhered to the first silicon substrate 60 on which the thermal oxide film 61 is formed on the concave portion 62 forming surface. Etc., they are bonded using various joining techniques. At this time, the second silicon substrate 64 is arranged so as to cover the plurality of recesses 62 and bonded to the first silicon substrate 60. As a result, the laminated body 66 (Cavity wafer) is formed.

As described above, by performing the laminate forming step, the laminate 66 is surrounded by the thermal oxide film 61 formed on the second silicon substrate 64 and the first silicon substrate 60 at the predetermined positions on the upper, lower, left and right sides. The gap 41 is formed. A gap 42 (not shown) is formed at the same time.
As described above, in the laminate forming step, the support base material 10 in which the plurality of recesses 62 to be the gaps 41 and 42 are formed on one surface of the first silicon substrate 60 to be the support base material 10 and the recesses 62 are formed. A thermal oxide film 61 is formed on at least one surface. After that, the second silicon substrate 64 to be the detection base material 120 is attached to the support base material 10 so as to cover the plurality of recesses 62. As a result, the gaps 41 and 42 are provided between the first silicon substrate 60 and the second silicon substrate 64, and heat is generated between the support base material 10 and the detection base material 120 on the outer periphery of the gap portions 41 and 42. A laminated body 66 provided with an oxide film 61 is formed.

The entire surface of the first silicon substrate 60 may be thermally oxidized to form a thermal oxide film 61 on the entire front surface, back surface and side surface (upper surface, lower surface and left surface in FIG. 22) of the first silicon substrate 60. In this case, the surface stress sensor 101 in which the connection layers 111 are formed on both surfaces (upper surface and lower surface in FIG. 20) of the support base material 10 can be obtained by individualizing with a dicing blade at the end of the manufacturing process. ..

(First ion implantation process)
Since the first ion implantation step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
As described above, in the first ion implantation step, among the surfaces of the detection base material 120 opposite to the surface facing the support base material 10, a selected region outside the preset region including the center of the detection base material 120 is selected. The first ion is implanted into the region of the portion (flexible resistance region 70).

(Second ion implantation process)
Since the second ion implantation step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
As described above, in the second ion implantation step, the second ion is implanted into the selected region outside the region (flexible resistance region 70) in which the first ion is implanted in the detection substrate 120 (FIG. 23). (A)).

(Heat treatment process)
Since the heat treatment step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
As described above, in the heat treatment step, the laminated body 66 in which the first ion and the second ion are injected is heat-treated to form the flexible resistance region 70 in the region in which the first ion is injected, and the second A low resistance region 72 is formed in the region in which the ions of the above are injected (FIG. 23 (a)).

(Groove formation process)
As shown in FIG. 23B, in the groove forming step, the second silicon substrate 64 is penetrated in the outer region of the region where the flexible resistance region 70 and the low resistance region 72 of the laminated body 66 after the heat treatment are formed. A groove 64a having a thermal oxide film 61 as a bottom surface is formed. The groove 64a is formed by dry etching using a photoresist pattern (not shown) as a mask. The groove 64a is formed, for example, at a position surrounding each of the rectangular gaps 41 and 42 in a plan view, in a shape that follows the shape of the gaps 41 and 42. Subsequently, dry etching is performed using the pattern of the groove 64a as a mask to form a groove 61a that penetrates the thermal oxide film 61 and has the first silicon substrate 60 as the bottom surface, as shown in FIG. 23 (b). The groove portion 125 is formed by the groove 64a and the groove 61a. The groove portion 127 is also formed in the same manner.
As described above, in the groove forming step, the second silicon serving as the frame member 124 is at a position surrounding each of the gaps 41 and 42 outside the region where the flexible resistance region 70 and the low resistance region 72 are formed. The thermal oxide film 61 serving as the substrate 64 and the connection layer 111 is removed to form the groove portions 125 and 127 (FIG. 23 (a)).

(Wiring layer forming process)
Since the wiring layer forming step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
As described above, in the wiring layer forming step, the wiring layer 82 electrically connected to the flexible resistor 50 is formed.
(Removal process)
Since the removal step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
Therefore, in the removing step, the membranes 122a and 122b and the frame member are removed by removing the regions other than the low resistance region 72 and the flexible resistance region 70 around the preset region including the center of the detection base material 120. 124 (124a, 124b), connecting portion 26, flexible resistor is formed.

(Operation / action)
The operation and operation of the third embodiment, in addition to the same operation and operation as those of the first embodiment and the second embodiment described above, are performed by the groove portions 125 and 127 on the connection layer 111a located outside the groove portions 125 and 127. The resulting stress can be prevented from being transmitted to the membranes 122a and 122b.
The above-mentioned third embodiment is an example of the present invention, and the present invention is not limited to the above-mentioned third embodiment, and even if it is an embodiment other than this embodiment, it relates to the present invention. As long as it does not deviate from the technical idea, various changes can be made according to the design and the like.

(Effect of Third Embodiment)
The surface stress sensor 101 of the third embodiment can exhibit the effects described below in addition to the effects obtained by the surface stress sensor 1 of the first embodiment.
(1) In the surface stress sensor 101, the connection layer 111b and the frame member 124b located inside the groove 125 are separated from the connection layer 111a and the frame member 124a located outside the groove 125, which have a large area and are prone to stress. doing.
As a result, even when stress is generated in the connection layer 111a, the stress can be released to the groove portion 125, and the influence of the stress generated in the connection layer 111a on the membrane 122a can be reduced.

(2) The distances between the groove portions 125 and 127 and the outer circumferences of the gap portions 41 and 42 may be formed to be equal at any of the positions of the groove portion 125 and the gap portion 41 and the groove portion 127 and the gap portion 42, respectively. preferable.
As a result, the stress applied from the periphery of the membrane 122a and the stress applied from the periphery of the membrane 122b can be made substantially equal, and the offset of the surface stress sensor 101 can be isotropically reduced.
(3) A part of the grooves 125 and 127 may be formed in common (integrally). With this configuration, the membranes 122a and 122b can be arranged closer to each other, and the surface stress sensor 101 can be miniaturized.

Further, in the method of manufacturing the surface stress sensor of the third embodiment, in addition to the effects obtained by the method of manufacturing the surface stress sensor 1 of the first embodiment, the effects described below can be obtained.
(4) A laminate forming step, a first ion implantation step, a second ion implantation step, a heat treatment step, a groove forming step, a wiring layer forming step, and a removing step are provided. In the laminate forming step, a recess 62 is formed on one surface of the support base material 10, a thermal oxide film 61 is formed on at least the surface on which the recess 62 of the support base material 10 is formed, and then the recess 62 is formed in the support base material 10. By laminating the detection base material 120 so as to cover the space, a gap 40 is provided between the support base material 10 and the detection base material 120, and the support base material 10 and the detection group are provided on the outer periphery of the gap portions 41 and 42. A laminated body 66 having a thermal oxide film 61 provided between the material 120 and the material 120 is formed. In the first ion implantation step, in a part of the surface of the detection base material 120 opposite to the surface facing the support base material 10 and outside the preset region including the center of the detection base material 120. , Inject the first ion. In the second ion implantation step, the second ion is implanted into the selected region outside the region in which the first ion is implanted in the detection substrate 120. In the heat treatment step, the laminated body 66 in which the first ion and the second ion are injected is heat-treated to form a flexible resistance region 70 in the region in which the first ion is injected, and the second ion is formed. A low resistance region 72 is formed in the injected region. In the groove forming step, the detection base material 120 and the thermal oxide film 61 are formed in the regions outside the flexible resistance region 70 forming the flexible resistance 50a to 50d of the detection base material 120 and the region forming the low resistance region 72. Is removed to form grooves 125 and 127. In the wiring layer forming step, a wiring layer electrically connected to the flexible resistor is formed. In the removing step, the membranes 122a and 122b and the frame member 124 ( 124a, 124b.124c), the connecting portion 26 and the flexible resistor 50 are formed.

Therefore, in addition to the effect of the surface stress sensor 1 obtained by the manufacturing method of the first embodiment, the influence of the stress generated in the BOX layer (thermal oxide film) 111 on the membranes 122a and 122b is reduced by a simple process. , Highly accurate and stable sensing is possible.

(Fourth Embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.
(composition)
The surface stress sensor 101 according to the fourth embodiment has a structure in which a plurality of sensor portions are provided and grooves are provided on the outer periphery of the sensor portions as in the third embodiment, and the surface stress sensor 101 according to the second embodiment has a structure similar to that of the surface stress sensor 1 of the second embodiment. Similarly, the connecting layer 90 is provided on the supporting base material 10.
Since other configurations are the same as those of the second embodiment described above, the description thereof will be omitted.

(Manufacturing method of surface stress sensor)
A method of manufacturing the surface stress sensor 101 will be described with reference to FIGS. 1 to 19 and FIGS. 24 to 26. The cross-sectional views of FIGS. 24 to 26 correspond to the hole forming step, the gap forming step, and the hole sealing step (FIGS. 17 to 19) in the second embodiment.
The method for manufacturing the surface stress sensor 101 includes a laminate forming step, a first ion injection step, a second ion injection step, a heat treatment step, a hole forming step, a void forming step, and a hole sealing step. It includes a wiring layer forming step and a removing step.

(Laminate body forming process)
In the laminate forming step, the laminate 66 is formed by the same procedure (FIG. 16) as that of the second embodiment described above, and thus the description thereof will be omitted.
As described above, in the laminate forming step, the sacrificial layer 92 is laminated on the support base material 10, and the detection base material 120 is further laminated on the sacrificial layer 92 to form the laminate 66.

(First ion implantation process)
In the first ion implantation step, since the first ion is implanted by the same procedure as the second embodiment described above (FIG. 16), the description thereof will be omitted.
As described above, in the first ion implantation step, among the surfaces of the detection base material 120 opposite to the surface facing the support base material 10, a selected region outside the preset region including the center of the detection base material 120 is selected. The first ion is implanted into the region of the portion (flexible resistance region 70).

(Second ion implantation process)
In the second ion implantation step, since the second ion is implanted in the same procedure as the second embodiment described above (FIG. 16), the description thereof will be omitted.
As described above, in the second ion implantation step, the second ion is implanted into the selected region outside the region (flexible resistance region 70) in which the first ion is implanted in the detection base material 120.

(Heat treatment process)
In the heat treatment step, the heat treatment is performed by the same procedure (FIG. 16) as that of the second embodiment described above, and thus the description thereof will be omitted.
As described above, in the heat treatment step, the laminated body 66 in which the first ion and the second ion are injected is heat-treated to form the flexible resistance region 70 in the region in which the first ion is injected, and the second A low resistance region 72 is formed in the region in which the ions of the above are injected.

(Hole forming process)
In the hole forming step, a hole and groove pattern (not shown) is formed on the upper surface of the second silicon substrate 64 by a general photolithography technique. The hole pattern is formed in a region corresponding to the gap forming region of the second silicon substrate 64. The region corresponding to the gap forming region of the second silicon substrate 64 is a region adjacent to the region where the flexible resistance region 70 and the low resistance region 72 of the detection base material 120 are formed. Further, the groove pattern is formed in the region outside the gap forming region of the second silicon substrate 64. The region outside the gap forming region of the second silicon substrate 64 is the region outside the region where the flexible resistance region 70 and the low resistance region 72 of the detection base material 120 are formed.

Next, dry etching is performed using the hole pattern as a mask to form holes 76 and grooves 77 on the second silicon substrate 64, as shown in FIG. 24. The hole 76 is formed in a region corresponding to a gap forming region of the second silicon substrate 64. The groove 77 is formed in a region outside the gap forming region of the second silicon substrate 64 so as to surround the gap forming region. The diameter of the hole 76 and the width of the groove 77 are set to, for example, 0.28 [μm] so as to reach the sacrificial layer 92.
As described above, in the hole forming step, the region adjacent to the region where the flexible resistance region 70 and the low resistance region 72 of the detection base material 120 are formed, and the region where the flexible resistance region 70 and the low resistance region 72 are formed are formed. A hole 76 and a groove 77 penetrating to the sacrificial layer 92 are formed in the outer region.

(Void formation step)
In the gap forming step, only the sacrificial layer 92 is selectively etched by infiltrating the HF Vapor into the side of the first silicon substrate 60 through the holes 76 and the grooves 77, and as shown in FIG. 25, the first silicon substrate is formed. A gap 40 and a groove 93 are formed between the 60 and the second silicon substrate 64.
As described above, in the gap forming step, a part of the sacrificial layer 92 arranged between the flexible resistance region 70 and the supporting base material 10 is removed by etching through the hole 76, and the supporting base material 10 is removed. A gap 40 is provided between the detection base material 20 and the detection base material 20. Further, in the gap forming step, the sacrificial layer 92 in the region outside the region in which the flexible resistance region 70 and the low resistance region 72 are formed is removed by etching through the groove 77, and the groove 77 and the groove 93 are formed. The groove portion 125 is formed by etching. The groove portion 127 shown in FIG. 20 is formed by using the groove formed at a position (not shown).

(Hole sealing process)
In the hole sealing step, the holes 76 are sealed in the same procedure as in the second embodiment described above, and thus the description thereof will be omitted. In the hole sealing step, as shown in FIG. 26, the holes 76 and the grooves 77 are sealed by the oxide film 94.
As described above, in the hole sealing step, the oxide film 94 is formed on the surface of the detection base material 20 opposite to the surface facing the support base material 10, and the holes 76 and the grooves 77 are sealed.

(Wiring layer forming process)
Since the wiring layer forming step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
As described above, in the wiring layer forming step, the wiring layer electrically connected to the flexible resistor is formed.
(Removal process)
Since the removal step is performed in the same procedure as in the first embodiment described above, the description thereof will be omitted.
Therefore, in the removing step, the membranes 122a and 122b and the frame member are removed by removing the regions other than the low resistance region 72 and the flexible resistance region 70 around the preset region including the center of the detection base material 20. 124 (124a, 124b), connecting portion 26, flexible resistor is formed.

(Operation / action)
Since the operation and operation of the fourth embodiment are the same as those of the third embodiment described above, the description thereof will be omitted.
The above-mentioned fourth embodiment is an example of the present invention, and the present invention is not limited to the above-mentioned fourth embodiment, and even if it is an embodiment other than this embodiment, it relates to the present invention. As long as it does not deviate from the technical idea, various changes can be made according to the design and the like.
For example, in the hole forming step, the configuration in which the hole 76 is formed on the second silicon substrate 64 and the groove 77 is formed at the same time has been described, but the groove 77 may be formed in a step different from the step of forming the hole 76. .. In this case, the gap 40 and the groove 93 are also formed in a separate process. That is, the gap portion 40 may be formed after the hole 76 is formed, and the groove 93 may be formed after the groove 77 is formed in another step.

(Effect of Fourth Embodiment)
According to the method for manufacturing the surface stress sensor of the fourth embodiment, the effects described below can be obtained.
(1) Laminated body forming step, first ion injection step, second ion injection step, heat treatment step, hole forming step, void forming step, groove forming step, hole sealing step, wiring It includes a layer forming step and a removing step. In the laminate forming step, the sacrificial layer 92 is laminated on the support base material 10, and the detection base material 120 is further laminated on the sacrificial layer 92 to form the laminate 66. In the first ion implantation step, in a part of the surface of the detection base material 120 opposite to the surface facing the support base material 10 and outside the preset region including the center of the detection base material 120. , Inject the first ion. In the second ion implantation step, the second ion is implanted into the selected region outside the region in which the first ion is implanted in the detection substrate 120. In the heat treatment step, the laminated body 66 in which the first ion and the second ion are injected is heat-treated to form a flexible resistance region 70 in the region in which the first ion is injected, and the second ion is formed. A low resistance region 72 is formed in the injected region. In the hole forming step, a hole 76 penetrating to the sacrificial layer 92 is formed in a region adjacent to the region where the flexible resistance region 70 and the low resistance region 72 of the detection base material 120 are formed. Further, in the hole forming step, a groove 77 is formed in a region outside the region in which the flexible resistance region 70 and the low resistance region 72 are formed so as to penetrate to the sacrificial layer 92 and surround the preset region in a plan view. .. In the gap forming step, the sacrificial layer 92 arranged between the flexible resistance region 70 and the support base material 10 is removed by etching through the holes 76, and the support base material 10 and the detection base material 120 are used. A gap 40 is provided between the two. In the groove forming step, the sacrificial layer 92 exposed from the groove 77 is removed by etching through the groove 77 to form a groove portion penetrating the detection base material 120 (second silicon substrate 64) and the sacrificial layer 92. In the hole sealing step, an oxide film 94 is formed on the surface of the detection base material 120 opposite to the surface facing the support base material 10, and the holes 76 and the grooves 77 are sealed. In the wiring layer forming step, the wiring layer 82 electrically connected to the flexible resistor 50 is formed. In the removing step, the membranes 122a, 122b and the frame are removed by removing the regions other than the low resistance region 72 and the flexible resistance region 70 around the preset membrane setting region 84 including the center of the detection base material 120. The member 124 (124a, 124b), the connecting portion 26, and the flexible resistor 50 are formed.

Therefore, in addition to the effect of the surface stress sensor 1 obtained by the manufacturing method of the second embodiment, the influence of the stress generated in the BOX layer (thermal oxide film) 111 on the membranes 122a and 122b is reduced by a simple process. , Highly accurate and stable sensing is possible.

The surface stress sensor 1 of the embodiment and the surface stress sensor of the comparative example will be described with reference to the first embodiment and the second embodiment according to the examples described below.
(Example)
The surface stress sensor 1 of the embodiment has the same configuration as that described in the first embodiment, that is, the supporting base material is formed in a columnar shape, and the supporting base material 10 is formed between the membrane 22 and the package substrate 2. It has an existing configuration (see FIG. 14).
(Comparison example)
The surface stress sensor of the comparative example has a structure in which the supporting base material is formed in a cylindrical shape and the membrane is floated in the air (see FIG. 13).

(Performance evaluation)
For the surface stress sensor 1 of the example and the surface stress sensor of the comparative example, the performance by simulation is detected by detecting the change in the output in the state where the package substrate is stretched due to the temperature rise (10 [° C] rise), respectively. Evaluation was performed.
(Evaluation results)
As a result of detecting the change in the output in the state where the package substrate is stretched, the degree of the change in the output of the example is about 1/3 as compared with the comparative example.
As a result, the surface stress sensor 1 of the example can reduce the stress applied to the membrane due to the deformation of the package substrate to about 1/3 as compared with the surface stress sensor of the comparative example. confirmed.

1,101 ... Surface stress sensor, 2 ... Package substrate, 4 ... Connection part, 10 ... Support base material, 20,120 ... Detection base material, 22,122,122a, 122b, 122c ... Membrane, 24,124,124a, 124b, 124c ... Frame member, 26 ... Connecting part, 30, 30a, 30b ... Receptor, 40, 41, 42 ... Void part, 50 ... Flexible resistance, 60 ... First silicon substrate, 61a, 64a ... Groove, 62 ... recess, 64 ... second silicon substrate, 66 ... laminate, 68 ... silicon oxide film, 70 ... flexible resistance region, 72 ... low resistance region, 74 ... silicon nitride film, 76 ... hole, 77 ... groove, 78 ... Laminated film, 80 ... Metal film, 82 ... Wiring layer, 84 ... Membrane setting area, 86 ... PAD, 90 ... Connection layer, 92 ... Sacrificial layer, 93 ... Groove, 94 ... Oxide film, 100 ... Conventional configuration Surface stress sensors provided, 111, 111a, 111b, 111c ... connection layer, 125, 127 ... groove, VL1 ... virtual straight line passing through the center of the membrane, VL2 ... straight line orthogonal to VL1

Claims (16)

A membrane that bends due to the applied surface stress,
And the frame member surrounding the membrane with a gap when viewed from the thickness direction of the membrane,
At least a pair of connecting portions that are arranged at positions that sandwich the membrane when viewed from the thickness direction and connect the membrane and the frame member.
A flexible resistor provided in at least one of the connecting portions and whose resistance value changes according to the bending generated in the connecting portion.
A supporting base material that is connected to the frame member and overlaps the membrane when viewed from the thickness direction.
A package substrate connected to a surface of the support substrate opposite to the surface facing the membrane, and
With
A gap is provided between the membrane and the supporting base material, and a gap is provided .
The support base material and the package base material are connected by a connecting portion arranged at a position overlapping with at least a part of the membrane when viewed from the thickness direction.
A surface stress sensor in which the area of the connection portion is smaller than the area of the membrane when viewed from the thickness direction of the membrane. The flexible resistance is a piezoresistive effect.
The surface stress sensor according to claim 1, wherein the piezoresistive effect has a resistance value that changes according to the bending caused by the bending of the membrane. The membrane and the frame member are connected by two pairs of the four connecting portions.
The flexible resistor is provided in each of the four of the connecting portion,
The surface stress sensor according to claim 1 or 2, wherein the four flexible resistors form a full Wheatstone bridge. The membrane is an n-type semiconductor layer and has an n-type semiconductor layer.
The surface stress sensor according to any one of claims 1 to 3, wherein the flexible resistance is a p-type semiconductor layer. The membrane, the frame member, and the connecting portion form an integral detection base material.
The difference between the coefficient of linear expansion of the supporting substrate and the coefficient of linear expansion of the detected substrate is 1.2 × 10 ⁻⁵ / ° C. or less according to any one of claims 1 to 4. Described surface stress sensor. The surface stress sensor according to claim 5, wherein the coefficient of linear expansion of the supporting base material is 1.0 × ^{10-5 / ° C. or less.} The surface stress sensor according to claim 6, wherein the coefficient of linear expansion of the supporting base material is 5.0 × 10 ^{-6 / ° C. or less.} The surface stress sensor according to any one of claims 1 to 7, wherein the thickness of the supporting base material is 80 μm or more. The surface stress according to any one of claims 1 to 8, wherein the outer peripheral surface of the supporting base material and the outer peripheral surface of the frame member are flush with each other when viewed from the thickness direction of the membrane. Sensor. The surface stress sensor according to any one of claims 1 to 9, wherein the supporting base material is made of a material containing any of silicon, sapphire, gallium arsenide, glass, and quartz. A connecting layer provided between the supporting base material and the frame member,
The surface stress according to any one of claims 1 to 10 , further comprising a groove portion provided at a position surrounding the gap portion in a plan view and formed so as to penetrate the frame member and the connection layer. Sensor. By forming a recess on one surface of the support base material and further adhering the detection base material to the support base material so as to cover the recess, a gap portion is formed between the support base material and the detection base material. A laminate forming step of forming a laminate provided with
The part of the area outside of the selected than preset region including the center of the detector substrate of the surface of the supporting substrate opposite to the surface opposite of the detection substrate, injecting a first ion First ion implantation process and
A second ion implantation step of injecting a second ion into a selected region outside the region in which the first ion was implanted in the detection substrate, and a second ion implantation step.
By heat-treating the laminate into which the first ion and the second ion are injected, a flexible resistance region is formed in the region where the first ion is injected, and the second ion is injected. A heat treatment process to form a low resistance region in the region
A membrane that flexes due to applied surface stress by removing a region other than the low resistance region and the flexible resistance region around a preset region including the center of the detection substrate, the membrane. a frame member surrounding the membrane with a gap when viewed from the thickness direction, at least a pair of connecting portions which are arranged at positions sandwiching the membrane when viewed from the thickness direction connecting the frame member and the membrane, And a removal step of forming a flexible resistor whose resistance value changes according to the bending generated in the connecting portion.
A wiring layer forming step of forming a wiring layer electrically connected to the flexible resistor,
A package substrate arranging step of arranging the package substrate on the surface of the support substrate opposite to the surface facing the membrane, and
A connection portion between the supporting base material and the package substrate that overlaps at least a part of the membrane when viewed from the thickness direction is provided at a position where the connection portion is smaller than the area of the membrane when viewed from the thickness direction of the membrane. A connection step of forming and connecting the support base material and the package base material,
A method of manufacturing a surface stress sensor. In the laminate forming step, after forming a thermal oxide film on at least the surface of the support substrate on which the recess is formed, the detection substrate is bonded to form the laminate.
12. Claim 12 further comprising a groove forming step of removing the detection base material and the thermal oxide film to form a groove in the flexible resistance region and the region outside the low resistance region of the detection base material. The method for manufacturing a surface stress sensor described in 1. A laminate forming step of laminating a sacrificial layer on a support substrate and further laminating a detection substrate on the sacrificial layer to form a laminate.
Injecting a first ion in a part of the area outside of the selected than preset region including the center of the detector substrate of the surface of the supporting substrate opposite to the surface opposite of the detection substrate First ion implantation process and
A second ion implantation step of injecting a second ion into a selected region outside the region in which the first ion was implanted in the detection substrate, and a second ion implantation step.
By heat-treating the laminate into which the first ion and the second ion are injected, a flexible resistance region is formed in the region where the first ion is injected, and the second ion is injected. A heat treatment process to form a low resistance region in the region
A hole forming step of forming a hole penetrating to the sacrificial layer in a region adjacent to the flexible resistance region and the region forming the low resistance region of the detection base material.
By etching through the holes, the sacrificial layer arranged between the flexible resistance region and the support base material is removed, and a gap is provided between the support base material and the detection base material. Void formation process and
A hole sealing step of forming an oxide film on the surface of the detection base material opposite to the surface facing the support base material to seal the holes.
A membrane that flexes due to applied surface stress by removing a region other than the low resistance region and the flexible resistance region around a preset region including the center of the detection substrate, the membrane. a frame member surrounding the membrane with a gap when viewed from the thickness direction, at least a pair of connecting portions which are arranged at positions sandwiching the membrane when viewed from the thickness direction connecting the frame member and the membrane, And a removal step of forming a flexible resistor whose resistance value changes according to the bending generated in the connecting portion.
A wiring layer forming step of forming a wiring layer electrically connected to the flexible resistor,
A package substrate arranging step of arranging the package substrate on the surface of the support substrate opposite to the surface facing the membrane, and
A connection portion between the supporting base material and the package substrate that overlaps at least a part of the membrane when viewed from the thickness direction is provided at a position where the connection portion is smaller than the area of the membrane when viewed from the thickness direction of the membrane. A connection step of forming and connecting the support base material and the package base material,
A method of manufacturing a surface stress sensor. In the hole forming step, at the same time as forming the hole, the flexible resistance region and the region outside the region where the low resistance region is formed of the detection base material are penetrated to the sacrificial layer, and the holes are formed. The method for manufacturing a surface stress sensor according to claim 14 , wherein a groove surrounding a preset region is formed. In the region outside the flexible resistance region and the region forming the low resistance region of the detection base material, a groove is formed so as to penetrate to the sacrificial layer and surround the preset region in a plan view.
The surface according to claim 14 , further comprising a groove forming step of removing the sacrificial layer exposed from the groove by etching through the groove to form a groove portion penetrating the detection base material and the sacrificial layer. Manufacturing method of stress sensor.

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