WO2015146154A1

WO2015146154A1 - Force detection device

Info

Publication number: WO2015146154A1
Application number: PCT/JP2015/001670
Authority: WO
Inventors: 水野　健太朗; 理恵田口; 橋本　昭二; 喜恵大平; 勝間田　卓; 浩平山口
Original assignee: 株式会社デンソー
Priority date: 2014-03-26
Filing date: 2015-03-24
Publication date: 2015-10-01

Abstract

This force detection device is provided with a substrate (2) and a force transmission block (4), and the substrate includes high-sensitivity mesa-type gages (14, 18), low-sensitivity mesa-type gages (12, 16), and mesa-type leads (22a, 24a, 26a, 28a). The force transmission block is in contact with the top surfaces of the high-sensitivity mesa-type gages, and the top surfaces of the low-sensitivity mesa-type gages, and is not in contact with at least a part of the top surfaces of the mesa-type leads. Alternatively, the force transmission block is in contact with merely the top surfaces of the high-sensitivity mesa-type gages, and is not in contact with the low-sensitivity mesa-type gages. The force detection device is provided with a substrate (204) and a force transmission block (204), and the substrate has mesa-type gages (212, 214, 216, 218), sealing section (230) in contact with the force transmission block, and a supporting column (220) in contact with the force transmission block.

Description

Force detector

Cross-reference of related applications

This application is Japanese Patent Application No. 2014-121824 filed on June 12, 2014, Japanese Patent Application No. 2014-63198 filed on March 26, 2014, and filed on March 9, 2015. Which is based on Japanese Patent Application No. 2015-45682, which is incorporated herein by reference.

The present disclosure relates to a force detection device that uses a piezoresistance effect.

A force detection device using the piezoresistance effect has been developed, and an example thereof is disclosed in Patent Document 1. This type of force detection device includes a substrate and a force transmission block. A mesa gauge that forms a bridge circuit is formed on the main surface of the substrate. For example, a mesa gauge constituting a bridge circuit is arranged corresponding to a rectangular side, and a high-sensitivity mesa gauge and a compressive stress that extend in a direction in which the electrical resistance value changes relatively relative to the compressive stress. In contrast, a low-sensitivity mesa gauge that extends in a direction in which the electrical resistance value changes relatively small is included. Further, a mesa lead extending from a connection portion where the high sensitivity mesa gauge and the low sensitivity mesa gauge are connected is formed on the main surface of the substrate.

The force transmission block is provided to cover the high-sensitivity mesa gauge, low-sensitivity mesa gauge, and mesa-type lead provided on the main surface of the substrate. It contacts the top surface of the mold gauge and the top surface of the mesa lead. When the force transmission block presses the high-sensitivity mesa gauge, the compressive stress applied to the high-sensitivity mesa gauge increases, and the electrical resistance value of the high-sensitivity mesa gauge changes due to the piezoresistance effect. The force applied to the force transmission block is detected from the change in the electrical resistance value.

A force detection device using the piezoresistance effect has been developed. This type of force detection device includes a substrate and a force transmission block. A mesa gauge that forms a bridge circuit is formed on the main surface of the substrate. The force transmission block contacts the top surface of the mesa gauge. When the force transmission block presses the mesa gauge, the compressive stress applied to the mesa gauge increases, and the electric resistance of the mesa gauge changes due to the piezoresistance effect. The force applied to the force transmission block is detected from the change in electrical resistance.

Patent Document 2 and Patent Document 3 disclose sealed force detection devices. The sealed-type force detection device is characterized in that the force transmission block is joined to the main surface of the substrate around the mesa gauge.

Japanese Published Patent Publication No. 2001-304997 Japanese Published Patent Publication No. 2004-132911 Japanese Published Patent Publication No. 2006-058266

The inventors of the present application have found the following regarding the force detection device.

In this type of force detection device, improvement in sensor sensitivity is desired. An object of the present disclosure is to provide a technique for improving the sensor sensitivity of a force detection device.

Furthermore, the inventors of the present application have found the following regarding the force detection device.

When miniaturization of the sealed force detection device is advanced, the pressure receiving area of the force transmission block is reduced, and the compressive stress applied to the mesa gauge is reduced. As a result, the sensor sensitivity of the force detection device decreases. An object of the present disclosure is to provide a sealed force detection device with high sensor sensitivity.

According to the force detection device according to the first aspect of the present disclosure, the force detection device includes a substrate and a force transmission block. The substrate includes a high sensitivity mesa gauge, a low sensitivity mesa gauge, and a mesa lead. The high-sensitivity mesa gauge is provided on the main surface of the substrate, extends in a first direction in which the electrical resistance value changes relatively greatly with respect to compressive stress, and has a top surface. The low-sensitivity mesa gauge is provided on the main surface of the substrate, extends in the second direction in which the electric resistance value changes relatively small with respect to the compressive stress, and has a top surface. The mesa lead is provided on the main surface of the substrate, and extends in the third direction from a connection portion where the high sensitivity mesa gauge and the low sensitivity mesa gauge are connected, and has a top surface. The force transmission block contacts the top surface of the high sensitivity mesa gauge and the top surface of the low sensitivity mesa gauge. The force transmission block does not contact at least a part of the top surface of the mesa-type lead.

According to the force detection device according to another aspect of the present disclosure, the force detection device includes a substrate and a force transmission block, the substrate is provided on the main surface, and the electrical resistance value is relative to the compressive stress. A high-sensitivity mesa gauge having a top surface, and a main surface, and a second direction in which the electrical resistance value changes relatively small against compressive stress. A low-sensitivity mesa gauge that has a top surface and a main surface, and extends in the third direction from the connection between the high-sensitivity mesa gauge and the low-sensitivity mesa gauge. A mesa-type lead having The force transmission block is in contact with only the top surface of the high-sensitivity mesa gauge and is not in contact with the low-sensitivity mesa gauge.

According to the force detection device of the above embodiment, since the force transmission block is not in contact with at least a part of the top surface of the mesa lead, the force received by the force transmission block is efficiently transmitted to the high sensitivity mesa gauge. Is done. Thereby, the sensor sensitivity of a force detection apparatus improves.

According to the force detection device according to the second aspect of the present disclosure, the force detection device includes a substrate and a force transmission block. The substrate has a mesa gauge, a sealing portion, and a support. The mesa gauge is formed on the main surface of the substrate and is in contact with the force transmission block to form a bridge circuit. The sealing portion is formed on the main surface of the substrate, and makes a round around the mesa gauge and contacts the force transmission block. The support column is formed on the main surface of the substrate, is disposed inside the mesa gauge, and contacts the force transmission block.

According to the force detection device of the above embodiment, a sealing space is formed between the substrate and the force transmission block. When the force applied to the force transmission block is increased, the force transmission block is curved toward the substrate side in the sealed space. At this time, a portion where the force transmission block is bent and displaced becomes a force point, a support column becomes a fulcrum, and a lever relationship where the mesa gauge acts as an action point is established. For this reason, since a large compressive stress is applied to the mesa-type gauge serving as the action point, the sensor sensitivity of the force detection device is improved.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the attached drawings
FIG. 1 shows a force detection device of an embodiment, and is a diagram schematically showing a cross-sectional view corresponding to line II in FIG. FIG. 2 shows the force detection device of the embodiment, and is a diagram schematically showing a cross-sectional view corresponding to the line II-II in FIG. FIG. 3 shows the force detection device of the embodiment, schematically showing a plan view of the substrate, and showing a range in contact with the force transmission block by a broken line, FIG. 4 shows the force detection device of the embodiment, and is a diagram schematically showing an explanatory diagram for explaining the positional relationship between the pressing portion of the force transmission block and the mesa gauge of the substrate, FIG. 5 shows a force detection device of a modified example, and is a diagram schematically showing an explanatory diagram for explaining the positional relationship between the pressing portion of the force transmission block and the mesa gauge of the substrate, FIG. 6 shows a force detection device of a comparative example, and is a diagram schematically showing an explanatory diagram for explaining the positional relationship between the pressing portion of the force transmission block and the mesa gauge of the substrate, FIG. 7 is a diagram schematically showing an enlarged view for explaining the state of the high-sensitivity mesa gauge when the force transmission block receives pressure, showing a force detection device of a comparative example. FIG. 8 shows a modified force detection device, and is a diagram schematically showing an explanatory diagram for explaining the positional relationship between the pressing portion of the force transmission block and the mesa gauge of the substrate, FIG. 9 shows a force detection device of a modified example, and is a diagram schematically showing an explanatory diagram for explaining the positional relationship between the pressing portion of the force transmission block and the mesa gauge of the substrate, FIG. 10 shows a modified force detection device, and is a diagram schematically showing an explanatory diagram for explaining the positional relationship between the pressing portion of the force transmission block and the mesa gauge of the substrate, FIG. 11 is a force detector of the example, and is a diagram schematically showing a cross-sectional view corresponding to the line XI-XI in FIG. FIG. 12 is a force detection device of an example, and is a diagram schematically showing a plan view of a substrate, FIG. 13 is a force detection device of an example, is an enlarged cross-sectional view of the main part in the vicinity of the sealed space, and is a diagram illustrating a diagram for explaining the operation of the insulator, FIG. 14 is a force detection device of a modification, and is a diagram schematically showing a cross-sectional view corresponding to FIG. FIG. 15 is a force detection device of a modification, and schematically shows a cross-sectional view corresponding to FIG.

The technical features disclosed in this specification will be summarized below. The items described below have technical usefulness independently.
(First embodiment)
One embodiment of the force detection device disclosed in the present specification is a sensor that detects various pressures. In one example, the detection target may be atmospheric pressure or hydraulic pressure. The force detection device may include a substrate and a force transmission block. The material of the substrate is preferably one that exhibits a piezoresistance effect in which the electrical resistance changes according to the compressive stress. For example, examples of the substrate include a semiconductor substrate and an SOI substrate. The substrate may include a high sensitivity mesa gauge, a low sensitivity mesa gauge, and a mesa lead. The high sensitivity mesa gauge is provided on the main surface of the substrate and has a top surface. The high-sensitivity mesa gauge extends in the first direction in which the electrical resistance value changes relatively greatly with respect to the compressive stress. The low-sensitivity mesa type gauge is provided on the main surface of the substrate and has a top surface. The low-sensitivity mesa type gauge extends in the second direction in which the electric resistance value changes relatively small with respect to the compressive stress. The first direction and the second direction have a crossing relationship. Typically, the high-sensitivity mesa gauge and the low-sensitivity mesa gauge may constitute a bridge circuit. In this case, a pair of high-sensitivity mesa type gauges are arranged corresponding to a pair of opposite sides of the rectangle, and a pair of low-sensitivity mesa type gauges are arranged corresponding to the other pair of opposite sides of the rectangle. Good. Here, “relative” means a contrast between a high-sensitivity mesa gauge and a low-sensitivity mesa gauge. In other words, the electric resistance value of the high-sensitivity mesa gauge changes more greatly with respect to the compressive stress than the low-sensitivity mesa gauge. The mesa lead is provided on the main surface of the substrate and has a top surface. The mesa lead extends in the third direction from a connection portion where the high sensitivity mesa gauge and the low sensitivity mesa gauge are connected. The third direction may have a relationship that intersects both the first direction and the second direction, or may have a relationship parallel to either the first direction or the second direction. The force transmission block contacts the top surface of the high sensitivity mesa gauge and the top surface of the low sensitivity mesa gauge. The force transmission block does not contact at least a part of the top surface of the mesa-type lead. That is, the force transmission block is non-contact with at least a part of the top surface of the mesa lead. Desirably, the force transmission block does not contact the top surface of the mesa lead.

In the force detection device of the above embodiment, the area where the force transmission block and the top surface of the high-sensitivity mesa gauge are in contact may be larger than the area where the force transmission block and the top surface of the low-sensitivity mesa gauge are in contact. In this force detection device, the area that the force transmission block contacts is different between the high-sensitivity mesa gauge and the low-sensitivity mesa gauge, so that most of the force received by the force transmission block is transmitted to the high-sensitivity mesa gauge. be able to. Thereby, since the compressive stress added to a high sensitivity mesa type gauge increases, the sensor sensitivity of a force detector improves. In order to improve the sensor sensitivity of the force detection device, a configuration in which the force transmission block contacts only the top surface of the high-sensitivity mesa gauge can be considered. However, in the force detection device having such a configuration, since the force transmission block is not supported by the low-sensitivity mesa gauge, the high-sensitivity mesa gauge is deformed in one piece when the force transmission block bends toward the substrate side. However, the linearity between the compressive stress and the electric resistance value is deteriorated. When the force transmission block is in contact with both the top surface of the high-sensitivity mesa gauge and the top surface of the low-sensitivity mesa gauge, the deflection of the force transmission block is suppressed, and the single deformation of the high-sensitivity mesa gauge is suppressed. And the linearity between the electrical resistance values is good. In the force detection device of the above embodiment, both sensor sensitivity and linearity are good.

In the force detection device of the above-described embodiment, the force transmission block may have a plurality of portions formed apart from each other along the second direction. In this case, each of the plurality of portions may be in contact with the top surface of the low-sensitivity mesa gauge. In the force detection device of this embodiment, the deflection of the force transmission block is suppressed, and both sensor sensitivity and linearity are good.

The low-sensitivity mesa type gauge may have a central region extending near the center along the second direction and a peripheral region extending from the connecting portion to the central region along the second direction. Furthermore, in the force detection device in which each of the plurality of portions of the force transmission block is in contact with the top surface of the low-sensitivity mesa gauge, the area where the plurality of portions and the top surface of the central region are in contact is the area where the plurality of portions and the top surface of the peripheral region are in contact May be larger. In the force detection device of this embodiment, it is possible to effectively suppress the deflection of the force transmission block while suppressing the contact area between the force transmission block and the low sensitivity mesa gauge. Thereby, in the force detection apparatus of this embodiment, sensor sensitivity and linearity are further improved.

The low-sensitivity mesa type gauge may have a central region extending near the center along the second direction and a peripheral region extending from the connecting portion to the central region along the second direction. Further, in the force detection device in which each of the plurality of parts of the force transmission block is in contact with the top surface of the low-sensitivity mesa gauge, the plurality of parts arranged corresponding to the central area are arranged corresponding to the peripheral area. Compared to, the intervals may be formed more densely. In the force detection device of this embodiment, it is possible to effectively suppress the deflection of the force transmission block while suppressing the contact area between the force transmission block and the low sensitivity mesa gauge. Thereby, in the force detection apparatus of this embodiment, both sensor sensitivity and linearity are further improved.
(First embodiment)
As shown in FIGS. 1 to 3, the force detection device 1 is, for example, a semiconductor pressure sensor that detects the internal pressure of a pressure vessel, and includes a semiconductor substrate 2 and a force transmission block 4.

As shown in FIGS. 1 and 2, the semiconductor substrate 2 is n-type single crystal silicon, and its main surface 2S is a (110) crystal plane. A plurality of grooves 11 are formed in the main surface 2S of the semiconductor substrate 2. The plurality of grooves 11 define the detection unit 10 on the main surface 2S of the semiconductor substrate 2.

As shown in FIG. 3, the detection unit 10 has mesa type gauges 12, 14, 16, and 18 constituting a bridge circuit. As shown in FIGS. 1 and 2, the mesa gauges 12, 14, 16, and 18 project in a mesa shape from the bottom surface of the groove 11, and the height thereof is about 0.5 to 5 μm. The top surfaces of the mesa gauges 12, 14, 16, 18 are located on the same plane as the main surface 2 S of the semiconductor substrate 2 around the groove 11. That is, the mesa gauges 12, 14, 16, and 18 are formed as a remaining portion in which the plurality of grooves 11 are formed in the main surface 2S of the semiconductor substrate 2 by using, for example, a dry etching technique.

As shown in FIG. 3, the mesa gauges 12, 14, 16, 18 of the detection unit 10 are arranged corresponding to the sides of the square. The mesa gauges 14 and 18 constituting a pair of opposing sides are referred to as a first high sensitivity mesa gauge 14 and a second high sensitivity mesa gauge 18, respectively. The mesa-type gauges 12 and 16 constituting the other pair of opposing sides are referred to as a first low-sensitivity mesa gauge 12 and a second low-sensitivity mesa-type gauge 16, respectively.

The first high sensitivity mesa gauge 14 and the second high sensitivity mesa gauge 18 extend along the <110> direction of the semiconductor substrate 2. The first high-sensitivity mesa gauge 14 and the second high-sensitivity mesa gauge 18 that extend in the <110> direction of the semiconductor substrate 2 are characterized in that the electrical resistance value changes greatly according to the compressive stress, and the piezoresistance effect Have

The first low-sensitivity mesa gauge 12 and the second low-sensitivity mesa gauge 16 extend along the <100> direction of the semiconductor substrate 2. The first low-sensitivity mesa gauge 12 and the second low-sensitivity mesa gauge 16 that extend in the <100> direction of the semiconductor substrate 2 are characterized in that their electrical resistance values hardly change according to compressive stress, and the piezoresistance effect Is substantially absent.

As shown in FIGS. 1 and 2,

gauge portions

12 a, 14 a, 16 a, and 18 a into which p-type impurities are introduced are formed on the surfaces of the mesa-type gauges 12, 14, 16, and 18. The impurity concentration of the

gauge portions

12a, 14a, 16a, and 18a is about 1 × 10 ¹⁸ to 1 × 10 ²¹ cm ⁻³ . The

gauge portions

12a, 14a, 16a, and 18a are substantially insulated from the n-type semiconductor substrate 2 by pn junctions.

As shown in FIG. 3, the semiconductor substrate 2 has

wiring portions

22, 24, 26, and 28 in which p-type impurities are introduced into the main surface 2 S. The impurity concentration of the

wiring portions

22, 24, ^26, and ²⁸ is about 1 × 10 ¹⁸ to 1 × 10 ²¹ cm ⁻³ . The

wiring parts

22, 24, 26, 28 electrically connect the detection part 10 and the

electrodes

32, 34, 36, 38. The

electrodes

32, 34, 36, and 38 are provided on the main surface 2 S of the semiconductor substrate 2 and are disposed outside the range covered with the force transmission block 4.

One end of the first wiring part 22 is connected to the first connection part 13 to which the gauge part 12a of the first low-sensitivity mesa gauge 12 and the gauge part 14a of the first high-sensitivity mesa gauge 14 are connected. Is connected to the first electrode 32. The first wiring part 22 has a first mesa lead 22 a on the first connection part 13 side of the mesa gauges 12 and 14. The first mesa type lead 22a protrudes in a mesa shape from the bottom surface of the groove 11 and is formed in the same process as the mesa type gauges 12, 14, 16, and 18.

The second wiring part 24 has one end connected to the second connection part 15 to which the gauge part 14a of the first high sensitivity mesa gauge 14 and the gauge part 16a of the second low sensitivity mesa gauge 16 are connected, and the other end. Is connected to the second electrode 34. The second wiring part 24 has a second mesa type lead 24 a on the second connection part 15 side of the mesa type gauges 14 and 16. The second mesa type lead 24 a protrudes in a mesa shape from the bottom surface of the groove 11 and is formed in the same process as the mesa type gauges 12, 14, 16, 18.

One end of the third wiring part 26 is connected to the third connection part 17 to which the gauge part 16a of the second low-sensitivity mesa gauge 16 and the gauge part 18a of the second high-sensitivity mesa gauge 18 are connected. Is connected to the third electrode 36. The third wiring portion 26 has a third mesa lead 26 a on the third connection portion 17 side of the mesa gauges 16 and 18. The third mesa type lead 26 a protrudes in a mesa shape from the bottom surface of the groove 11 and is formed in the same process as the mesa type gauges 12, 14, 16, 18.

The fourth wiring portion 28 has one end connected to the fourth connection portion 19 to which the gauge portion 18a of the second high sensitivity mesa gauge 18 and the gauge portion 12a of the first low sensitivity mesa gauge 12 are connected, and the other end. Is connected to the fourth electrode 38. The fourth wiring portion 26 has a fourth mesa lead 28 a on the fourth connecting portion 19 side of the mesa gauges 12 and 18. The fourth mesa type lead 28a protrudes in a mesa shape from the bottom surface of the groove 11, and is formed in the same process as the mesa type gauges 12, 14, 16, and 18.

As shown in FIGS. 1 and 2, the force transmission block 4 has a rectangular parallelepiped shape and includes a silicon layer 4a and a silicon oxide layer 4b. The semiconductor substrate 2 and the force transmission block 4 are bonded using a room temperature single phase bonding technique. Specifically, the main surface 2S of the semiconductor substrate 2 and the surface of the silicon oxide layer 4b of the force transmission block 4 are activated using argon ions, and then the main surface 2S of the semiconductor substrate 2 and the force are applied in an ultrahigh vacuum. The surfaces of the silicon oxide layer 4b of the transmission block 4 are brought into contact with each other to join them together.

1 and 2, a part of the silicon oxide layer 4b of the force transmission block 4 is removed, and a groove 4c is formed on the surface of the force transmission block 4 on the semiconductor substrate 2 side. By forming the groove 4c, the silicon oxide layer 4b of the force transmission block 4 is partitioned into a sealing portion 40a and a pressing portion 40b. In addition, by forming such a groove 4 c, a sealed space 6 separated from the outside is formed between the semiconductor substrate 2 and the force transmission block 4.

The sealing portion 40a of the force transmission block 4 is bonded to the main surface 2S of the semiconductor substrate 2 so as to make a round around the mesa gauges 12, 14, 16, and 18. A portion of the semiconductor substrate 2 where the sealing portion 40 a is joined is referred to as a sealing portion 20. The sealing portion 20 of the semiconductor substrate 2 and the sealing portion 40a of the force transmission block 4 are joined in an airtight manner.

FIG. 4 shows the positional relationship between the pressing portion 40b of the force transmission block 4 and the mesa gauges 12, 14, 16, and 18. The pressing portion 40 b has a point-symmetric form and is joined to a part of the top surface of the mesa gauges 12, 14, 16, 18. The pressing portion 40b is joined to most of the top surfaces of the high-sensitivity mesa gauges 14 and 18. The pressing portion 40b does not contact the top surfaces of the both ends of the high-sensitivity mesa gauges 14 and 18 (the top surfaces of the portions close to the

connection portions

13, 15, 17, and 19). The pressing portion 40 b is joined to most of the top surfaces of the low sensitivity mesa type gauges 12 and 16. The pressing portion 40b does not contact the top surfaces of the both ends of the low-sensitivity mesa gauges 12 and 16 (the top surfaces of the portions close to the

connection portions

13, 15, 17, and 19). The pressing portion 40b does not contact the top surfaces of the mesa-type leads 22a, 24a, 26a, and 28a and the top surfaces of the

connection portions

13, 15, 17, and 19.

Next, the operation of the force detection device 1 will be described. First, the force detection device 1 is used by connecting a constant current source to the first electrode 32, grounding the third electrode 36, and connecting a voltage measuring device between the second electrode 34 and the fourth electrode 38. In the force detection device 1, when the container internal pressure applied to the force transmission block 4 changes, the compressive stress applied to the

gauge portions

12 a, 14 a, 16 a, 18 a of the mesa type gauges 12, 14, 16, 18 via the force transmission block 4 is also increased. Change. The electrical resistance values of the

gauge portions

14a and 18a of the high-sensitivity mesa-type gauges 14 and 18 in which the piezoresistance effect appears change in proportion to the compressive stress. For this reason, the potential difference between the second electrode 34 and the fourth electrode 38 is proportional to the compressive stress applied to the

gauge portions

14a and 18a. Thereby, the container internal pressure added to the force transmission block 4 is detected from the voltage change measured with a voltage measuring device.

In the force detection device 1, the pressing portion 40b of the force transmission block 4 is not in contact with the top surfaces of the mesa-type leads 22a, 24a, 26a, and 28a. For this reason, the container internal pressure applied to the force transmission block 4 is efficiently transmitted to the high-sensitivity mesa gauges 14 and 18. Thereby, the sensor sensitivity of the force detection device 1 is improved.

In this type of force detection device 1, the voltage drop due to the parasitic resistance values of the mesa-type leads 22a, 24a, 26a, and 28a deteriorates the sensor sensitivity. Therefore, in the force detection device 1, the width of the mesa type leads 22a, 24a, 26a, 28a (parallel to the main surface 2S of the semiconductor substrate 2 and in the longitudinal direction of the mesa type leads 22a, 24a, 26a, 28a). The width of the mesa gauges 12, 14, 16, 18 is parallel to the main surface 2S of the semiconductor substrate 2 and the longitudinal direction of the mesa gauges 12, 14, 16, 18 It is desirable that the width is greater than As a result, the parasitic resistance values of the mesa-type leads 22a, 24a, 26a, and 28a can be reduced, so that the sensor sensitivity of the force detection device 1 is improved.

In the configuration where the force transmission block is also in contact with the top surface of the mesa type lead as in the conventional force detection device, if the width of the mesa type lead is increased, the container internal pressure applied to the force transmission block is also transmitted to the mesa type lead. Therefore, the compressive stress applied to the high sensitivity mesa gauge is reduced. As described above, in the conventional force detection device, even if the width of the mesa lead is increased to reduce the parasitic resistance value, it is difficult to improve the sensor sensitivity because the compressive stress applied to the high sensitivity mesa gauge is reduced. . On the other hand, in the force detection device 1 of the present embodiment, the force transmission block 4 does not contact the top surfaces of the mesa leads 22a, 24a, 26a, 28a, so the width of the mesa leads 22a, 24a, 26a, 28a is increased. However, the compressive stress applied to the high-sensitivity mesa gauges 14 and 18 does not decrease. Thereby, in the force detection device 1 of the present embodiment, the sensor sensitivity is effectively improved when the width of the mesa type leads 22a, 24a, 26a, 28a is increased.

Hereinafter, the force detection devices of the modified example and the comparative example will be described. The components common to the force detection device 1 of the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

In the modified force detection device shown in FIG. 5, the pressing portion 40 b of the force transmission block is configured with different layouts between the high-sensitivity mesa gauges 14 and 18 and the low-sensitivity mesa gauges 12 and 16. The pressing portion 40b is in contact with most of the top surfaces of the high-sensitivity mesa gauges 14 and 18, and the contact area between the pressing portion 40b and the high-sensitivity mesa gauges 14 and 18 is relatively large. The occupied area of the portion in contact with the pressing portion 40b in the total area of the top surfaces of the high sensitivity mesa gauges 14 and 18 is relatively large. The pressing portion 40b is selectively in contact with the top surface near the center of the low-sensitivity mesa gauges 12 and 16, and the contact area between the pressing portion 40b and the low-sensitivity mesa gauges 12 and 16 is relatively small. The occupied area of the portion in contact with the pressing portion 40b in the total area of the top surfaces of the low-sensitivity mesa gauges 12 and 16 is relatively small. As described above, in the force detection device of the modified example, the area with which the pressing portion 40 b contacts is different between the high sensitivity mesa gauges 14 and 18 and the low sensitivity mesa gauges 12 and 16. For this reason, the container internal pressure applied to the force transmission block is efficiently transmitted to the high-sensitivity mesa gauges 14 and 18. Thereby, in the force detector of this modification, sensor sensitivity improves.

Here, in order to explain other characteristics of the modified force detection device, a comparative force detection device will be described. In the force detection device of the comparative example shown in FIG. 6, the pressing portion 40 b of the force transmission block contacts only the pair of high-sensitivity mesa gauges 14 and 18. When such a configuration is adopted, the container internal pressure applied to the force transmission block is efficiently transmitted to the high-sensitivity mesa gauges 14 and 18.

However, as shown in FIG. 7, when the container internal pressure is applied to the force transmission block 4, it bends toward the semiconductor substrate 2 so that the center point of the region surrounded by the mesa gauge is a convex top. . Due to the bending of the force transmission block 4, the high-sensitivity mesa type gauges 14 and 18 are deformed inward and the linearity between the compressive stress and the electric resistance value is deteriorated.

In the modified force detection device shown in FIG. 5, the pressing portion 40 b of the force transmission block is also in contact with part of the top surfaces of the low-sensitivity mesa gauges 12 and 16. Thereby, the bending of a force transmission block is suppressed and the single deformation of the high sensitivity mesa type | mold gauges 14 and 18 is suppressed. Therefore, in the force detection device of this modification, the linearity between the compressive stress and the electric resistance value is good. Thus, in the force detection device of this modification, both sensor sensitivity and linearity can be achieved.

In the force detection device of the modification shown in FIG. 8, the pressing portion 40 b of the force transmission block has a plurality of portions 40 c that are formed apart from each other along the longitudinal direction of the low-sensitivity mesa gauges 12 and 16. . Each of the plurality of portions 40 c is in contact with the top surfaces of the low-sensitivity mesa gauges 12 and 16. The plurality of portions 40 c are arranged at equal intervals along the longitudinal direction of the low sensitivity mesa type gauges 12 and 16. In the force detection device of this modification, the deflection of the force transmission block 4 is suppressed, and the linearity between the compressive stress and the electric resistance value is improved.

Next, a modified example of the force detection device of FIGS. 9 and 10 will be described. In order to understand the characteristics of the force detection devices of these modified examples, as shown in FIGS. 9 and 10, the low-sensitivity mesa gauges 12 and 16 are divided into three regions along the longitudinal direction. (For clarity of illustration, only the region corresponding to the first low-sensitivity mesa gauge 12 is shown, but the second low-sensitivity mesa gauge 16 is the same). The low-sensitivity mesa gauges 12 and 16 have a central region 12A and a pair of peripheral regions 12B. The center region 12A extends near the center along the longitudinal direction. Each of the pair of peripheral regions 12B extends from the connecting

portions

13, 15, 17, 19 of the mesa gauge to the central region 12A along the longitudinal direction. The central region 12A and the pair of peripheral regions 12B have the same length in the longitudinal direction. That is, when the low-sensitivity mesa gauges 12 and 16 are equally divided into three along the longitudinal direction, the central region 12A is disposed near the center, and the peripheral region 12B is disposed near the periphery. .

In the modified force detection device shown in FIG. 9, when the central region 12A and the peripheral region 12B are compared, the area where the top surface of the central region 12A and the plurality of portions 40c are in contact with each other is such that the top surface of one peripheral region 12B and the plurality of portions are in contact with each other. It is larger than the contact area of 40c. In other words, the occupied area of the portion in contact with the plurality of portions 40c in the total area of the top surface of the central region 12A is larger than the occupied area of the portion in contact with the plurality of portions 40c in the total area of the top surface of one peripheral region 12B. large. As described above, the force transmission block bends so that the center point of the force transmission block becomes a convex top when the container internal pressure is applied. Since the central region 12A of the low-sensitivity mesa gauges 12 and 16 is close to the center point thereof, the contact of the force transmission block with a large area can be effectively suppressed by this portion. That is, it is possible to effectively suppress the deflection of the force transmission block while suppressing an increase in the contact area between the force transmission block and the low-sensitivity mesa gauges 12 and 16. Thereby, the force detection device of this modification can achieve both sensor sensitivity and linearity. Note that the plurality of portions 40c corresponding to the peripheral region 12B may not be formed according to the required characteristics. Such an example corresponds to the force detection device of the modification shown in FIG. Accordingly, the force detection device of the modification shown in FIG. 5 can also effectively suppress the deflection of the force transmission block while suppressing an increase in the contact area between the force transmission block and the low-sensitivity mesa gauges 12 and 16. The sensor sensitivity and linearity can both be achieved.

In the modified force detection device shown in FIG. 10, when the central region 12A and the peripheral region 12B are compared, the plurality of portions 40c arranged corresponding to the central region 40c are plural arranged corresponding to the peripheral region 12B. Compared with the portion 40c, the intervals are formed more densely. Also in the force detection device of this modification, the occupied area of the portion in contact with the plurality of portions 40c in the total area of the top surface of the central region 12A is the portion in contact with the plurality of portions 40c in the total area of the top surface of one peripheral region 12B. A relationship larger than the occupied area of the can be obtained. For this reason, even in the force detection device of this modification, the deflection of the force transmission block can be effectively suppressed, and both sensitivity and linearity can be achieved.
(Second Embodiment)
One embodiment of the force detection device disclosed in the present specification is a sensor that detects atmospheric pressure, and in one example, combustion pressure may be a detection target. The force detection device may include a substrate and a force transmission block. The material of the substrate is preferably one that exhibits a piezoresistance effect in which the electrical resistance changes according to the compressive stress. For example, the substrate includes a semiconductor substrate and an SOI substrate. The board | substrate may have a mesa type gauge, a sealing part, and a support | pillar. The mesa gauge is formed on the main surface of the substrate, is in contact with the force transmission block, and may constitute a bridge circuit. The mesa type gauge has a mesa shape and may be in contact with the force transmission block at its top surface. The sealing portion is formed on the main surface of the substrate, and may be in contact with the force transmission block around the mesa gauge. The support column is formed on the main surface of the substrate, is disposed inside the mesa gauge, and may be in contact with the force transmission block. The support column has a mesa shape and may be in contact with the force transmission block at its top surface. It is desirable that the rigidity of the column is higher than that of the mesa gauge.

In the above embodiment, a sealed space that is airtightly separated from the outside by the substrate and the force transmission block may be configured. The sealing space is disposed between the mesa gauge and the sealing portion, and may have a thickness that allows the force transmission block to bend.

In the force transmission block of the above embodiment, a groove may be formed on the surface on the substrate side. The groove may be disposed between a portion in contact with the mesa gauge and a portion in contact with the sealing portion. This groove constitutes a sealing space.

In the above embodiment, the force transmission block may have a silicon layer and a silicon oxide layer. The silicon oxide layer may cover a part of the surface of the silicon layer on the substrate side. In this case, the groove may be formed in an uncovered region of the silicon oxide layer. By processing the silicon oxide layer of the force transmission block, a groove for forming a sealed space can be easily formed.

(Second embodiment)
As shown in FIGS. 11 and 12, the force detection device 201 is a semiconductor pressure sensor that detects a combustion pressure of an internal combustion engine, for example, and includes a semiconductor substrate 202 and a force transmission block 204.

The semiconductor substrate 202 is n-type single crystal silicon, and its main surface 202S is a (110) crystal plane. A plurality of grooves 211 are formed in the main surface 202 S of the semiconductor substrate 202. The plurality of grooves 211 define the detection unit 210, the support column 220, and the sealing unit 230 on the main surface 202 S of the semiconductor substrate 202.

As shown in FIG. 12, the detection unit 210 has mesa type gauges 212, 214, 216, and 218 that constitute a bridge circuit. The mesa type gauges 212, 214, 216, and 218 protrude in a mesa shape from the bottom surface of the groove 211, and the height thereof is about 0.5 to 5 μm. The top surfaces of the mesa gauges 212, 214, 216, 218 are located on the same plane as the main surface 202 S of the semiconductor substrate 202 around the groove 211. In other words, the mesa type gauges 212, 214, 216, and 218 are formed as a remaining portion in which a plurality of grooves 211 are formed in the main surface 202S of the semiconductor substrate 202 by using, for example, a dry etching technique.

As shown in FIG. 12, in the detection unit 210, the first mesa gauge 212 and the third mesa gauge 216 constitute a pair of opposing sides of a rectangle, and the second mesa gauge 214 and the fourth mesa gauge. 218 constitutes a pair of opposing sides of a rectangle. The first mesa gauge 212 and the third mesa gauge 216 extend along the <110> direction of the semiconductor substrate 202. In the first mesa gauge 212 and the third mesa gauge 216 extending in the <110> direction of the semiconductor substrate 202, a piezoresistance effect in which the electrical resistance changes according to the compressive stress appears. The second mesa gauge 214 and the fourth mesa gauge 218 extend along the <100> direction of the semiconductor substrate 202. The second mesa gauge 214 and the fourth mesa gauge 218 extending in the <100> direction of the semiconductor substrate 202 do not substantially exhibit a piezoresistance effect.

As shown in FIGS. 11 and 12,

gauge portions

212a, 214a, 216a, and 218a into which p-type impurities are introduced are formed on the surfaces of the mesa-type gauges 212, 214, 216, and 218. The impurity concentration of the

gauge portions

212a, 214a, 216a, 218a is about 1 × 10 ¹⁸ to 1 × 10 ²¹ cm ⁻³ . The

gauge portions

212a, 214a, 216a, and 218a are substantially insulated from the n-type semiconductor substrate 202 by pn junctions.

11 and 12, the support column 220 is disposed inside the mesa type gauges 212, 214, 216, and 218. The column 220 protrudes from the bottom surface of the groove 211 in a mesa shape, and its height is about 0.5 to 5 μm. The top surface of the support column 220 is located on the same plane as the main surface 202 S of the semiconductor substrate 202 around the groove 211. In other words, the support column 220 is formed as a remaining portion in which a plurality of grooves 211 are formed in the main surface 202S of the semiconductor substrate 202 by using, for example, a dry etching technique. The support column 220 has a shape similar to the rectangle of the mesa gauges 212, 214, 216, and 218 when viewed in plan. The side length of the column 220 is larger than the width of the mesa gauges 212, 214, 216 and 218 (width in the direction perpendicular to the longitudinal direction). Thereby, the rigidity of the column 220 is higher than the rigidity of the mesa gauges 212, 214, 216, and 218.

As shown in FIG. 12, the semiconductor substrate 202 has

wiring portions

232, 234, 236, and 238 in which p-type impurities are introduced into the main surface 202S. The impurity concentration of the

wiring portions

232, 234, 236, and 238 is approximately 1 × 10 ¹⁸ to 1 × 10 ²¹ cm ⁻³ . One end of the first wiring part 232 is connected to the connection part of the first gauge part 212 a and the second gauge part 214 a, and the other end is connected to the first electrode 242. The second wiring part 234 has one end connected to the connection part of the second gauge part 214 a and the third gauge part 216 a and the other end connected to the second electrode 244. The third wiring part 236 has one end connected to the connection part between the third gauge part 216 a and the fourth gauge part 218 a and the other end connected to the third electrode 246. One end of the fourth wiring part 238 is connected to the connection part between the fourth gauge part 218 a and the first gauge part 212 a, and the other end is connected to the fourth electrode 248. Each of the

electrodes

242, 244, 246, and 248 is provided on the main surface 202S of the semiconductor substrate 202, and is disposed outside the range covered with the force transmission block 204.

As shown in FIG. 11, the force transmission block 204 has a rectangular parallelepiped shape, and includes a silicon layer 204a and a silicon oxide layer 204b. The silicon oxide layer 204b covers a part of the surface of the silicon layer 204a on the semiconductor substrate 202 side. The force transmission block 204 is joined to the main surface 202S of the semiconductor substrate 202 so as to make a round around the mesa gauges 212, 214, 216, and 218. A portion of the semiconductor substrate 202 where the force transmission block 204 is joined is referred to as a sealing portion 230. The sealing portion 230 of the semiconductor substrate 202 and the force transmission block 204 are hermetically bonded. The force transmission block 204 is also joined to the top surfaces of the mesa gauges 212, 214, 216, and 218 and the top surface of the support column 220. The semiconductor substrate 202 and the force transmission block 204 are bonded using a room temperature single phase bonding technique. Specifically, after activating the main surface 202S of the semiconductor substrate 202 and the surface of the silicon oxide layer 204b of the force transmission block 204 using argon ions, the force is applied to the main surface 202S of the semiconductor substrate 202 in an ultrahigh vacuum. The surfaces of the silicon oxide layer 204b of the transmission block 204 are brought into contact with each other to join them together.

As shown in FIG. 11, a part of the silicon oxide layer 204b of the force transmission block 204 is removed, and a groove 204c is formed on the surface of the force transmission block 204 on the semiconductor substrate 202 side. The groove 204c is disposed so as to face the region between the mesa type gauges 212, 214, 216, 218 and the sealing portion 230 of the semiconductor substrate 202, and the mesa type when the force detection device 201 is viewed in plan view. Go around the

gauges

212, 214, 216 and 218. By forming such a groove 204 c, a sealed space 206 separated from the outside is formed between the semiconductor substrate 202 and the force transmission block 204.

Next, the operation of the force detection device 201 will be described. First, the force detection device 201 is used by connecting a constant current source to the first electrode 242, grounding the third electrode 246, and connecting a voltage measuring device between the second electrode 244 and the fourth electrode 248. In the force detection device 201, when the combustion pressure applied to the force transmission block 204 changes, the compressive stress applied to the

gauge portions

212a, 214a, 216a, 218a of the mesa type gauges 212, 214, 216, 218 via the force transmission block 204 is also increased. Change. The electrical resistance of the

gauge portions

212a and 216a where the piezoresistance effect appears changes in proportion to the compressive stress. Therefore, the potential difference between the second electrode 244 and the fourth electrode 248 is proportional to the compressive stress applied to the

gauge portions

212a and 216a. Thereby, the combustion pressure applied to the force transmission block 204 is detected from the voltage change measured by the voltage measuring device.

As shown in FIG. 13, in the sealing-type force detection device 201, a sealing space 206 is formed between the semiconductor substrate 202 and the force transmission block 204. The sealing space 206 is separated from the outside by an airtight connection between the sealing portion 230 of the semiconductor substrate 202 and the force transmission block 204. For this reason, the sealed force detection device 201 has a configuration in which the pressure difference between the atmospheric pressure inside the sealed space 206 and the combustion pressure increases as the combustion pressure increases. Accordingly, the total combustion pressure applied to the pressure receiving area of the force transmission block 204 (corresponding to the area between the mesa gauges 212, 214, 216, 218 and the sealing portion 230 when the force detection device 201 is viewed in plan). The force F 2, which causes the force transmission block 204 to bend toward the sealing space 206 side. At this time, a portion where the force transmission block 204 is bent and displaced becomes a force point, the support column 220 becomes a fulcrum, and a lever relationship where the mesa gauge 212 acts as an action point is established. When the distance between the fulcrum of the column 220 and the action point of the mesa gauge 212 is L1, and the distance between the fulcrum of the column 220 and the force point of the displaced portion is L2, the force F1 applied to the action point is ideal. If the effect of the insulator is exhibited, it is expressed by the following formula 1.

Thus, since the sealing type force detection device 201 of the present embodiment has a configuration in which the insulator relationship is established, the force F1 obtained by amplifying the force F2 applied to the force transmission block 204 is expressed as a mesa gauge. 212, 216. Thereby, the sensor sensitivity of the force detection device 201 is greatly improved.

As shown in Formula 1, in order to improve the sensor sensitivity of the force detection device 201, it is desirable that L2 / L1 is large, and it is desirable that L2 / L1 is 2 or more.

As shown in FIG. 14, the groove 204c constituting the sealing space 206 may be formed by processing both the silicon oxide layer 204b and the silicon layer 204a. In order to exert the lever effect, the force transmission block 204 at a position corresponding to the sealing space 206 must be curved. As shown in FIG. 14, when the silicon layer 204a at a position corresponding to the sealing space 206 is formed thin, the silicon layer 204a at that portion is well curved, so that the insulator effect is satisfactorily exhibited. .

As shown in FIG. 15, the groove 204 c constituting the sealing space 206 may be formed by processing the main surface 202 S of the semiconductor substrate 202. The groove 204c can be formed in the same process as the process of forming the mesa gauges 212, 214, 216, 218 and the support column 220 by using a dry etching technique.

The

semiconductor substrates

2 and 202 correspond to an example of the substrate of the present disclosure.

Although specific examples of the present disclosure have been described in detail above, these are merely examples, and do not limit the embodiments, configurations, and aspects according to the present disclosure. Techniques related to the present disclosure include various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

Claims

A substrate (2) and a force transmission block (4);
The substrate (2)
A high-sensitivity mesa gauge (14, 18) provided on the main surface (2S), extending in a first direction in which the electrical resistance value changes relatively greatly with respect to compressive stress, and having a top surface;
A low-sensitivity mesa gauge (12, 16) provided on the main surface (2S), extending in a second direction in which the electrical resistance value changes relatively small against compressive stress, and having a top surface; ,
It is provided on the main surface (2S) and extends in a third direction from a connecting portion where the high sensitivity mesa gauge (14, 18) and the low sensitivity mesa gauge (12, 16) are connected. A mesa-type lead (22a, 24a, 26a, 28a) having a surface,
The force transmission block (4) is in contact with the top surface of the high-sensitivity mesa gauge (14, 18) and the top surface of the low-sensitivity mesa gauge (12, 16), and the mesa lead (22a, 24a, 26a, 28a) A force detection device that is non-contact with at least part of the top surface.
The force detection device according to claim 1, wherein the force transmission block (4) is non-contact on a top surface of the mesa lead (22a, 24a, 26a, 28a).
The area where the force transmission block (4) and the top surface of the high-sensitivity mesa gauge (14, 18) contact each other is the surface area of the force transmission block (4) and the top surface of the low-sensitivity mesa gauge (12, 16). The force detection device according to claim 1, wherein the force detection device is larger than a contact area.
The force transmission block (4) has a plurality of portions (40c) formed apart from each other along the second direction,
The force detection device according to any one of claims 1 to 3, wherein each of the plurality of portions (40c) is in contact with a top surface of the low-sensitivity mesa gauge (12, 16).
The low-sensitivity mesa type gauges (12, 16) extend along the second direction near the center (12A), and extend from the connecting portion along the second direction to the center region (12A). A peripheral area (12B),
The area where the plurality of portions (40c) and the top surface of the central region (12A) are in contact is larger than the area where the plurality of portions (40c) and the top surface of the peripheral region (12B) are in contact with each other. Force detection device.
The low-sensitivity mesa type gauges (12, 16) extend along the second direction near the center (12A), and extend from the connecting portion along the second direction to the center region (12A). A peripheral area (12B),
The plurality of portions (40c) arranged corresponding to the central region (12A) are formed at a closer interval than the plurality of portions (40c) arranged corresponding to the peripheral region (12B). The force detection device according to claim 4, wherein
A substrate (2) and a force transmission block (4);
The substrate (2)
A high-sensitivity mesa gauge (14, 18) provided on the main surface (2S), extending in a first direction in which the electrical resistance value changes relatively greatly with respect to compressive stress, and having a top surface;
A low-sensitivity mesa gauge (12, 16) provided on the main surface (2S), extending in a second direction in which the electrical resistance value changes relatively small against compressive stress, and having a top surface; ,
It is provided on the main surface (2S) and extends in a third direction from a connecting portion where the high sensitivity mesa gauge (14, 18) and the low sensitivity mesa gauge (12, 16) are connected. A mesa-type lead (22a, 24a, 26a, 28a) having a surface,
The force transmission block (4) is in contact with only the top surface of the high-sensitivity mesa gauge (14, 18) and is not in contact with the low-sensitivity mesa gauge (12, 16).
A substrate (202) and a force transmission block (204);
The substrate (202)
A mesa gauge (212, 214, 216, 218) that is formed on the main surface (202S), is in contact with the force transmission block (204), and forms a bridge circuit;
A sealing portion (230) formed on the main surface (202S) and in contact with the force transmission block (204) around the periphery of the mesa gauge (212, 214, 216, 218);
A pillar (220) formed on the main surface (202S), disposed inside the mesa gauge (212, 214, 216, 218) and in contact with the force transmission block (204); A force sensing device.
The force transmission block (204) has a groove (204c) formed on the surface on the substrate (202) side,
The force detection device according to claim 8, wherein the groove (204c) is disposed between a portion in contact with the mesa gauge (212, 214, 216, 218) and a portion in contact with the sealing portion.
The force transmission block (204)
A silicon layer (204a);
A silicon oxide layer (204b) covering a part of the surface of the silicon layer (204a) on the substrate (202) side, and the groove (204c) is an uncovered region of the silicon oxide layer (204b). The force detection device according to claim 9, which is configured as follows.