Pressure sensing element and pressure sensor

Abstract

To facilitate downsizing a pressure sensor while achieving both detection sensitivity and output linearity.SOLUTION: Provided is a pressure sensing element 1 formed using a semiconductor substrate, comprising a frame 12, a diaphragm 11 supported by the frame 12, and a piezoelectric resistor 13 arranged on the diaphragm 11, the diaphragm 11 including a beam part 113 protruding from an edge of the diaphragm 11 in a direction toward the middle part of the diaphragm 11 and a single groove part 111 formed in a range from an outer frame part 112 and beam part 113 and including the middle part of the diaphragm 11.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a pressure sensing element and a pressure sensor. [Background technology]

[0002] In recent years, pressure sensors formed using MEMS (Micro Electro Mechanical Systems) technology have been used in various devices such as blood pressure monitors, CPAP (Continuous Positive Airway Pressure) devices, TPMS (Tire Pressure Monitoring Systems), and MAP (Manifold Air Pressure) sensors. Such pressure sensors are formed by etching a part of a pressure sensing element made of a semiconductor substrate from the back surface to form a diaphragm, and providing a piezoresistor on the diaphragm that detects the distortion of the diaphragm as a change in resistance. This makes it possible to measure pressure by detecting the change in electrical resistance of the piezoresistor due to distortion of the diaphragm when pressure is applied.

[0003] In such pressure sensors, it is important to improve the detection sensitivity in order to be able to detect minute changes in pressure, and it is also important to improve the linearity of the output in order to reduce detection errors. Therefore, in order to provide a pressure sensor with excellent detection sensitivity and output linearity, a sensor is known in which the surface of a diaphragm is removed by etching or other processing, leaving only a portion, thereby forming a groove portion on the diaphragm where the surface has been removed and the film thickness is thin, and a roughly cross-shaped beam portion where the surface has not been removed and the film thickness is thicker than the groove portion (see, for example, Patent Document 1).

[0004] Similarly, with the aim of providing a pressure sensor with excellent detection sensitivity and output linearity, in addition to the groove and beam portions, a boss is formed in the center of the diaphragm, leaving a rectangular or circular portion where the surface is not removed, and the beam portion is formed to connect such boss to a frame around the diaphragm (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 9,764,947 [Patent Document 2] U.S. Patent No. 8,381,596 Summary of the Invention [Problem to be solved by the invention]

[0006] In order to make such pressure sensors suitable for a variety of applications, it is important to reduce their size; however, there is a natural limit to the precision with which the diaphragm surface can be processed when producing the pressure sensing element, and excessively fine or complex processing is either impossible or, even if possible, results in increased costs. In this regard, the pressure sensor described in Patent Document 1 has a configuration in which the beams are formed in a substantially cross shape on the diaphragm as described above, but the thinness of the beams that can be formed on the surface of the diaphragm is limited due to the above-mentioned processing accuracy problem. Therefore, when the pressure sensor is made smaller, the beams inevitably become thicker relative to the grooves, and the ratio of the area of ​​the grooves to the area of ​​the diaphragm becomes smaller. This is also true of the pressure sensor described in Patent Document 2, in which bosses are formed on the diaphragm in addition to the grooves and beams.

[0007] Furthermore, when the ratio of the area of ​​the groove to the area of ​​the diaphragm becomes small, the effect of improving the detection sensitivity and linearity of the output by forming beams, grooves, and a boss on the diaphragm in the invention described in Patent Document 2 becomes small. Therefore, with conventional pressure sensors, it has been difficult to achieve both detection sensitivity and linearity of the output while further reducing the size.

[0008] An object of the present invention is to facilitate miniaturization of a pressure sensor while achieving both detection sensitivity and output linearity. [Means for solving the problem]

[0009] In order to solve the above problem, the invention described in claim 1 comprises: A pressure sensing element formed using a semiconductor substrate, The piezoelectric element includes a frame, a diaphragm supported by the frame, and a piezoresistor disposed on the diaphragm, The diaphragm is It has a roughly square shape in plan view with four rounded corners. The diaphragm Four protruding from the edge toward the center of the diaphragm Four The beam and a single groove portion formed in a range including the edge portion and the beam portion of the diaphragm and a center portion of the diaphragm; Equipped with the semiconductor substrate includes an active layer and a support layer which are layers formed of a semiconductor, and an insulating layer which is a layer formed of an insulator between the active layer and the support layer; The beam portion and the groove portion of the diaphragm are formed in the active layer. 、 The four beam portions are formed so as to gradually narrow in width toward a center portion which is a center position of the shape of the diaphragm in a plan view, The diaphragm includes an outer frame portion formed around an edge of the diaphragm, the piezoresistor is disposed at a connection between the beam portion and the outer frame portion, The corners of the beam portion and the outer frame portion are rounded. It is characterized by:

[0015] Claim 2 The invention described in is a pressure sensor, Claim 1 The pressure sensing element according to claim 1,

[0016] Claim 3 The invention described in claim 2 The pressure sensor according to claim 1, a substrate on which the pressure sensing element is mounted; a nozzle for introducing a fluid whose pressure is to be sensed into the pressure sensing element; The present invention is characterized by comprising: Effect of the Invention

[0017] According to the present invention, it is possible to easily reduce the size of a pressure sensor while achieving both detection sensitivity and output linearity. [Brief description of the drawings]

[0018] [Figure 1] 1 is a schematic diagram illustrating a configuration of a pressure sensor according to an embodiment. [Diagram 2] FIG. 2 is a plan view of a pressure sensing element of the pressure sensor according to the embodiment, as viewed from the top side. [Diagram 3] FIG. 2 is a plan view of a pressure sensing element of the pressure sensor according to the embodiment, viewed from the bottom side. [Figure 4] FIG. 3 is a cross-sectional view taken along line iv-iv in FIG. 2. [Diagram 5] 11 is a plan view of a pressure sensing element of the pressure sensor according to Modification 1, as viewed from the top side. FIG. [Figure 6] 1 is a plan view of a pressure sensing element of a pressure sensor in accordance with a first embodiment, as viewed from the top side. [Figure 7] FIG. 11 is a plan view of a pressure sensing element of a pressure sensor in accordance with a second embodiment, as viewed from the top side. [Figure 8] 1 is a plan view of a pressure sensing element of a pressure sensor according to Comparative Example 1, viewed from the top side. [Figure 9] 11 is a plan view of a pressure sensing element of a pressure sensor according to Comparative Example 2, viewed from the top side. FIG. [Figure 10]13 is a plan view of a pressure sensing element of a pressure sensor according to Comparative Example 3 and Comparative Example 4, viewed from the top side. FIG. [Figure 11] FIG. 2 is a diagram showing a circuit configuration of a pressure sensor according to an example and a comparative example. [Figure 12] 10 is a graph showing the results of sensitivity tests performed on pressure sensors according to an example and a comparative example. [Figure 13] 11 is a graph showing the results of an output linearity test performed on the pressure sensors according to the example and the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described with reference to Figures 1 to 5. However, the technical scope of the present invention is not limited to the illustrated examples, and various modifications can be made to the embodiment described below without departing from the spirit of the present invention.

[0020] [Configuration of the first embodiment] The pressure sensor 100 according to the embodiment includes a pressure sensing element 1, a circuit portion 2, a substrate 3, and a nozzle 4, as shown in FIG.

[0021] [1 Pressure sensing element] 2 and 3, the pressure sensing element 1 is a semiconductor chip formed in a substantially square shape in plan view using a semiconductor substrate. In the present embodiment, the side of the pressure sensing element 1 on which the diaphragm 11 is formed is defined as the upper surface, and the opposite side is defined as the lower surface.

[0022] As shown in FIG. 4, the pressure sensing element 1 is composed of three layers: an active layer 1a which is a silicon (Si) layer formed on the upper surface side, a support layer 1c which is a silicon (Si) layer formed on the lower surface side, and an insulating layer 1b which is made of silicon dioxide (SiO2) between the active layer 1a and the support layer 1c.

[0023] As shown in Figures 3 and 4, the pressure sensing element 1 has a hollow central portion on the underside, with the upper surface of this portion forming the diaphragm 11, and the portion of the underside around the diaphragm 11 where no hollow is formed forming the frame 12. As shown in FIG. 2, the diaphragm 11 of the pressure sensing element 1 is provided with piezoresistors 13 at four locations.

[0024] [(1) Diaphragm] 3 and 4, the central portion of the lower surface of the pressure sensing element 1 is removed by etching or the like in a substantially square shape in plan view so that only the active layer 1a remains. As a result, a diaphragm 11 is formed on the upper surface of the pressure sensing element 1, which is the portion where the active layer 1a remains in a thin film form. As shown in Figures 2 and 3, the diaphragm 11 is formed in a roughly square shape in a planar view in the area excluding the edges of the pressure sensing element 1, and is equipped with a groove portion 111 which is a thin portion, and an outer frame portion 112 and a beam portion 113 which are thicker than the groove portion 111.

[0025] [A Groove] 4, the groove portion 111 is a portion obtained by removing a part of the upper surface side of the diaphragm 11 by etching or the like to an extent that does not penetrate the active layer 1a, and is formed integrally with the outer frame portion 112 and the beam portion 113. Also, the groove portion 111 is formed to be thinner than the outer frame portion 112 and the beam portion 113. As shown in Figures 2 and 3, groove portion 111 is a single groove formed over the entire surface of the range from outer frame portion 112 and beam portion 113 to the central portion of diaphragm 11, and the entire surface of groove portion 111 is formed with a uniform thickness.

[0026] [A Outer frame] 2 and 3, groove portion 111 is formed to leave a gap from the boundary between diaphragm 11 and frame 12, leaving the edge portion of diaphragm 11. In other words, groove portion 111 is not formed at the edge portion of diaphragm 11, and outer frame portion 112, which is a portion that is thicker than groove portion 111 and is arranged so as to go around the edge portion of diaphragm 11, is provided.

[0027] [U Beam section] As shown in Figures 2 and 3, near the center of each side of the diaphragm 11, which is formed in an approximately square shape, there are four beam portions 113, which are thicker than the groove portions 111 and are arranged so as to protrude from the edge of the diaphragm 11 toward the center of the diaphragm 11. As described above, the four beam portions 113 are partitioned by forming grooves 111 in the active layer 1a by etching or the like, and are formed into shapes that protrude toward the center of the diaphragm 11. Moreover, the four beam portions 113 are formed independently of each other without intersecting near the center of the diaphragm 11, as shown in Figures 2 and 3. As shown in FIGS. 2 and 3, each of the beam portions 113 is formed so that its width in a plan view gradually narrows toward the center of the diaphragm 11.

[0028] The central portion of diaphragm 11 refers to a portion near the center of gravity of the shape of diaphragm 11 in a plan view. The edge portion of diaphragm 11 refers to a portion of diaphragm 11 near the boundary with the surrounding frame 12, etc., and in the case where outer frame portion 112 is formed on diaphragm 11 so as to go around the boundary with frame 12, etc., this corresponds to the portion where outer frame portion 112 is formed.

[0029] [(2) Frame] 3 and 4, only the central portion of the lower surface of the pressure sensing element 1 has been removed by etching or the like in a substantially square shape in plan view, and the three layers of the active layer 1a, the support layer 1c, and the insulating layer 1b remain at the edge of the pressure sensing element 1, which is formed to be thicker than the diaphragm 11. This portion is the frame 12.

[0030] [(3) Piezoresistance] The pressure sensing element 1 includes a piezoresistor 13 disposed on a diaphragm 11, as shown in FIG. The piezoresistors 13 are provided near the end of each beam portion 113 on the edge side of the diaphragm 11, specifically at a position overlapping with the connection between each beam portion 113 and the outer frame portion 112, one for each beam portion 113, for a total of four. The piezoresistor 13 does not necessarily have to be entirely located on the diaphragm 11, and may have a portion located on the frame 12 as shown in Fig. 2. Even in this case, as long as the other portion is located on the diaphragm 11, in the present invention, the piezoresistor 13 is considered to be located on the diaphragm 11. However, it is preferable that at least the center of the piezoresistor 13 is located on the diaphragm 11.

[0031] The piezoresistors 13 are formed on the diaphragm 11 by, for example, diffusion or ion implantation, and are configured so that when the diaphragm 11 is deflected by pressure, its electrical resistivity changes in proportion to the stress generated according to the amount of deflection of the diaphragm 11. As will be described later, the four piezoresistors 13 are connected by the circuit section 2 so as to form a Wheatstone bridge.

[0032] [2 Circuit section] As shown in FIG. 1, the circuit unit 2 includes an ASIC (Application Specific Integrated Circuit) 21 and a wire 22. The circuit section 2 connects four piezoresistors 13 to form a Wheatstone bridge, and measures pressure from an output potential difference caused by the electrical resistivity of the piezoresistors 13, which is proportional to the stress generated according to the amount of deflection of the diaphragm, by applying a voltage to the piezoresistors 13. In addition, the ASIC 21 performs various adjustments such as calibration of the sensor output and change of the drive voltage range. Incidentally, since the configuration of the circuit portion in such a pressure sensor is a well-known technique, a detailed description thereof will be omitted.

[0033] [3 boards] As shown in FIG. 1, the substrate 3 is a plate-like member on one surface of which the pressure sensing element 1 and the circuit section 2 are fixed, and together with a nozzle 4 (described later), forms the outer case of the pressure sensor 100. 1, the pressure sensing element 1 is connected at its underside to a substrate 3, and a cavity is formed which is surrounded by a diaphragm 11 and a frame 12 of the pressure sensing element 1 and the substrate 3. In addition, a through hole 31 is provided in the substrate 3 directly below the pressure sensing element 1 so that the underside of the pressure sensing element 1 comes into contact with the atmosphere through the cavity. As a result, a pressure difference occurs between the upper and lower sides of the diaphragm 11 in accordance with the pressure of the fluid to be detected that is present on the upper side of the diaphragm 11, and the diaphragm 11 bends.

[0034] [4 nozzles] As shown in FIG. 1, the nozzle 4 is provided so as to cover the pressure sensing element 1 and the circuit portion 2 disposed on the substrate 3, and has an intake port 41 for taking in a fluid whose pressure is to be sensed by the pressure sensing element 1. The substrate 3 and the nozzle 4 form a space connected to the outside via the inlet 41 and inside which a pressure sensing element is disposed, and the pressure of the fluid introduced into the space through the inlet 41 is sensed by the pressure sensing element 1.

[0035] [Effects of the second embodiment] The pressure sensor 100 according to this embodiment includes a diaphragm 11 of a pressure sensing element 1, which includes a groove portion 111 that is a thin portion, and a plurality of beam portions 113 that are thicker than the groove portion 111.

[0036] When the diaphragm formed in the pressure sensing element of a pressure sensor is planar, there is a trade-off between detection sensitivity and output linearity; the thinner the diaphragm, the more easily it deforms, improving detection sensitivity while tending to decrease output linearity. In contrast, according to the present embodiment, the groove portion 111 is formed continuously over an area including the central portion of the upper surface of the diaphragm 11, thereby making it thin and improving sensitivity, while the beam portion 113, which is the thicker portion where the groove portion 111 is not formed, is left protruding from the edge of the diaphragm, thereby preventing a decrease in the linearity of the output.

[0037] In addition, in this case, compared to the case where the beams are formed in a substantially cross shape on the diaphragm of the pressure sensing element, as in the pressure sensor described in Patent Document 1, the beams 113 are formed separately and are not formed in the center of the diaphragm, so that it is possible to suppress a reduction in the area of ​​the grooves, which are the parts in the diaphragm where the thickness becomes thinner. This effect can be further enhanced by forming the beams 113 so that their width gradually narrows toward the center of the diaphragm 11.

[0038] Incidentally, even in the case where the beams are formed in a roughly cross shape on the diaphragm of the pressure sensing element as in the pressure sensor described in Patent Document 1, it is possible to suppress the reduction in the groove area by forming the beams thin, but as the pressure sensing element is miniaturized, the limit of processing precision is reached at a certain point in time, and the beams become thicker relative to the grooves, resulting in a smaller ratio of the groove area to the diaphragm area. This point remains the same in the pressure sensor described in Patent Document 2, in which a boss is formed in addition to the grooves and beams, since there is a similar limit to miniaturizing the boss. In contrast, according to the present embodiment, a groove portion 111 is formed continuously over an area including the central portion of the upper surface of the diaphragm 11, and since the shape of the groove portion 111 is simpler than in the pressure sensors described in Patent Documents 1 and 2, even when the pressure sensing element 1 is miniaturized, a reduction in the area of ​​the groove portion 111 in the diaphragm 11 caused by limitations in processing accuracy can be suppressed.

[0039] Moreover, according to the pressure sensor 100 of this embodiment, the piezoresistor 13 of the pressure sensing element 1 is disposed near the end of each beam 113 on the edge side of the diaphragm 11, specifically, at a position overlapping with the connection between the beam 113 and the outer frame 112. This allows the piezoresistor 13 to be disposed in a portion of the diaphragm 11 that is easily deformed, thereby improving sensitivity.

[0040] Furthermore, in the pressure sensor 100 according to this embodiment, no groove 111 is formed on the edge of the diaphragm 11 of the pressure sensing element 1, and an outer frame 112 is provided so as to go around the edge of the diaphragm 11. As a result, the piezoresistor 13 arranged near the end of the beam 113 on the edge side of the diaphragm 11 is arranged at a position away from the frame 12 by the outer frame 112, and therefore is arranged at a position that is less susceptible to the influence of the frame 12 on the deformation of the diaphragm 11, thereby improving sensitivity.

[0041] [Third Modification] In the above embodiment, the central portion of the underside of the pressure sensing element 1 is removed by etching or the like into an approximately square shape when viewed in plan, and the diaphragm 11 is formed into an approximately square shape when viewed in plan. However, the shape of the diaphragm is not limited to this. For example, as in the pressure sensing element 1A according to the first modification shown in FIG. 5, the central portion of the lower surface of the pressure sensing element 1A may be removed by etching or the like to have a generally circular shape in plan view, and the diaphragm 11A may be formed to have a generally circular shape in plan view. In this case, the shape of groove 111A on diaphragm 11A may be formed to match the overall shape of diaphragm 11A so that the portion not facing beam 113A forms an arc.

[0042] The layer structure of the pressure sensing element is not limited to the above three-layer structure. For example, it may be a single-layer structure of silicon without a SiO2 layer as an insulating layer, and the support layer may be made of a material such as glass.

[0043] As for the components of the pressure sensor 100 other than the pressure sensing element 1 (the circuit section 2, the substrate 3, and the nozzle 4), any components may be used as long as they can function as a pressure sensor, and various modifications may be made thereto. For example, in the above description, the atmosphere is introduced into the cavity on the lower side of the diaphragm 11 of the pressure sensing element 1 so that the lower side of the pressure sensing element 1 comes into contact with the atmosphere, and then the fluid whose pressure is to be measured is introduced into the upper side, but the cavity surrounded by the diaphragm 11 and frame 12 of the pressure sensing element 1 and the substrate 3 may be made into a low vacuum without providing the through-hole 31 in the substrate 3. Also, conversely to the above, the space on the upper side of the diaphragm 11 of the pressure sensing element 1 may be filled with the atmosphere or made into a low vacuum, and then the fluid whose pressure is to be measured may be introduced into the cavity on the lower side. EXAMPLES

[0044] Next, the results of tests on sensitivity and output linearity performed on the pressure sensors according to the examples of the present invention and the comparative examples will be described.

[0045] [Configurations of the first embodiment and comparative example] Pressure sensors according to the following examples and comparative examples were prepared.

[0046] [1 Example 1] [(1) Configuration of pressure sensing element: Pressure sensing element 1B shown in Figure 6] Layer structure: 3 layers: active layer (Si) 5.0μm, support layer (Si) 625μm, and insulating layer (SiO2) between them Pressure sensing element size: Approximate square shape with each side measuring 1.0 mm in plan view Diaphragm size: Approximate square shape with 0.426mm sides in plan view (each corner is rounded) Diaphragm thickness: Beam and outer frame 5.0μm, groove 3.5μm (groove depth 1.5μm) Piezoresistor size: Approximate square with each side measuring 60 μm in plan view Beam shape: As shown in Figure 6, the width gradually narrows from the base to the tip, and the protruding length from the outer frame is 0.085 mm (the distance between opposing beams is 0.25 mm). Outer frame: Width 0.003 mm, formed around the edge of the diaphragm Diaphragm area (Sd): 0.212mm 2 ·Groove area (St): 0.132mm 2 St / Sd=0.62 [(2) Circuit configuration] As shown in Figure 11. In this case, each piezoresistor (Rn) changes depending on the pressure (stress) received by the diaphragm, and Vout is output according to the following formula according to the pressure. Vout=(V+)-(V-) =[R4 / (R1+R4)xVDD]-[R2 / (R2+R3)xVDD]

[0047] [2 Example 2] As shown in FIG. 7, the protruding length of the beam is 0.135 mm (the distance between opposing beams is 0.15 mm). In this case, the diaphragm area (Sd): 0.212 mm 2 , Groove area (St): 0.118mm 2 , St / Sd=0.56. The other configurations are the same as those in the first embodiment.

[0048] [3 Comparative Example 1] As shown in Fig. 8, the beam is connected to the center of the diaphragm. In this case, the diaphragm area (Sd): 0.212 mm 2 , Groove area (St): 0.049mm 2 , St / Sd=0.23. The other configurations are the same as those in the first embodiment.

[0049] [4 Comparative Example 2] 9, the pressure sensing element 1E does not have a groove near the center of the diaphragm, but has a boss 114 that is approximately a square with sides of 0.12 mm and four rounded corners and has the same thickness (5.0 μm) as the beam and outer frame. In this case, the diaphragm area (Sd): 0.212 mm 2 , Groove area (St): 0.118mm 2 , St / Sd=0.56. The other configurations are the same as those in the first embodiment.

[0050] [5 Comparative Example 3] As shown in Fig. 10, the pressure sensing element 1F has no groove in the diaphragm and the thickness of the entire diaphragm is 3.5 μm. In this case, the diaphragm area (Sd): 0.212 mm 2 , Groove area (St): 0mm 2 , St / Sd=0. Other configurations are the same as those in the first embodiment.

[0051] [6 Comparative Example 4] As shown in Fig. 10, the pressure sensing element 1F has no groove in the diaphragm and the thickness of the entire diaphragm is 5.0 μm. In this case, the diaphragm area (Sd): 0.212 mm 2 , Groove area (St): 0mm 2 , St / Sd=0. Other configurations are the same as those in the first embodiment.

[0052] [Second test method] For the pressure sensors according to the above-mentioned Examples and Comparative Examples, the span voltage (mV) and output linearity (%FS) were calculated under the following conditions. Temperature: Normal temperature (25°C) Power supply voltage: 3.3V Applied pressure: 0 to 10 kPa (applied from the bottom of the pressure sensing element (support layer side)) Span voltage: Output when 10kPa is applied Output linearity: Worst value

[0053] [Third test results] The test results are shown in FIG. 12 and FIG.

[0054] [Fourth Evaluation] From a comparison between Examples 1 and 2 and Comparative Examples 3 and 4, it is clear that by forming grooves on the diaphragm while leaving beams, it is possible to achieve both sensitivity and output linearity. That is, in comparison with Comparative Example 3 in which the thickness of the entire diaphragm is 3.5 μm, Examples 1 and 2 have a greatly improved output linearity at the expense of a slight drop in the span voltage. Also, in comparison with Comparative Example 4 in which the thickness of the entire diaphragm is 5.0 μm, Example 1 has a slightly improved output linearity and a greatly improved sensitivity, and Example 2 also has almost the same output linearity and a greatly improved sensitivity.

[0055] Furthermore, by comparing Examples 1 and 2 with Comparative Example 1, it can be seen that, compared to the case where the beam portions, which are the parts of the diaphragm where no grooves are formed, are formed in an approximately cross shape, sensitivity and output linearity can be improved by forming the beam portions independently without reaching the center of the diaphragm, and by forming the groove portions continuously within a range that includes the center of the diaphragm.

[0056] Furthermore, a comparison between Example 1 and Comparative Example 2 reveals that, if the size of the beam portion is the same, the sensitivity and output linearity can be improved by forming a groove including the central portion of the diaphragm without leaving a thick portion in the central portion of the diaphragm.

[0057] Furthermore, when comparing Example 2 and Comparative Example 2, even when the groove areas are the same, Example 2 has almost the same output linearity and improved sensitivity compared to Comparative Example 2, which can be said to be preferable. Note that while both sensitivity and output linearity are important elements in a pressure sensor, output linearity can be corrected to some extent in the ASIC, so it is sensitivity that is more necessary to be improved by the configuration of the pressure sensing element.

[0058] Furthermore, from the viewpoint of ease of miniaturization, Example 2 can be said to be more preferable than Comparative Example 2. That is, in Comparative Example 2, the groove needs to be formed in an annular shape leaving the center of the diaphragm, and therefore the smaller the pressure sensing element is, the more difficult it becomes to form the groove as designed and to make boss 114, which is the thick central part, the expected size. In contrast, according to Example 2, the groove is formed continuously in an area including the center of the diaphragm and has a much simpler shape, so that it is easy to make the groove area as designed even when the pressure sensing element is miniaturized. [Explanation of symbols]

[0059] 100 Pressure Sensor 1, 1A, 1B, 1C, 1D, 1E, 1F Pressure sensing element 11, 11A, 11B, 11C, 11D, 11E, 11F Diaphragm 111, 111A, 111B, 111C, 111D, 111E, 111F Groove 112, 112A, 112B Outer frame 113, 113A, 113B, 113C, 113D Beam section 12, 12A, 12B Frame 13 Piezoresistance

Claims

1. A pressure sensing element formed using a semiconductor substrate, The piezoelectric element includes a frame, a diaphragm supported by the frame, and a piezoresistor disposed on the diaphragm, The diaphragm is The shape is generally square in plan view with four rounded corners. four beam portions protruding from four edges of the diaphragm toward a center of the diaphragm; a single groove portion formed in a range including the edge portion and the beam portion of the diaphragm and a center portion of the diaphragm; Equipped with the semiconductor substrate includes an active layer and a support layer which are layers formed of a semiconductor, and an insulating layer which is a layer formed of an insulator between the active layer and the support layer; the beam portion and the groove portion of the diaphragm are formed in the active layer, The four beam portions are formed so as to gradually narrow in width toward a center portion which is a center position of the shape of the diaphragm in a plan view, The diaphragm includes an outer frame portion formed around an edge of the diaphragm, the piezoresistor is disposed at a connection between the beam portion and the outer frame portion, The pressure sensing element is characterized in that the corners of the beam portion and the outer frame portion are rounded.

2. A pressure sensor comprising the pressure sensing element according to claim 1.

3. a substrate on which the pressure sensing element is mounted; a nozzle for introducing a fluid whose pressure is to be sensed into the pressure sensing element; The pressure sensor according to claim 2 , further comprising:

Images