DE102009046692A1 - Pressure e.g. absolute pressure, measuring device for industrial measurement engineering, has disks covering recess, and semiconductor pressure sensor attached on disks and comprising membrane carrier and measuring membrane - Google Patents

Abstract

The device has a socket (3) mounted on a base of a housing (1), and a carrier (5) projecting over the socket. The carrier has a front side that is turned towards the socket and comprises a cup-shaped recess (9). Disks (11, 11') cover the recess and comprise an insulator, and a semiconductor pressure sensor (13) is attached on the disks. The sensor has a membrane carrier (15) and a measuring membrane (17), where the carrier and the sensor comprise same thickness and are made of silicon. The socket is made of metal or ceramic, and the disks are made of glass.

Description

The invention relates to a pressure-measuring device with a mounted on a base in a housing semiconductor pressure sensor.

Pressure measuring devices are used to detect pressures, in particular of absolute pressures, relative pressures and differential pressures, and are used in industrial measurement technology.

In pressure measurement, so-called semiconductor pressure sensors are often used. Semiconductor sensors are now regularly based on silicon, z. B. using silicon-on-insulator (SOI) technology. They are designed as a pressure sensor chip, which typically has a carrier and a measuring diaphragm arranged on a carrier. In measuring mode, a first pressure is supplied to a first side of the measuring diaphragm.

For detecting differential pressures, a second pressure is supplied to a second side of the measuring diaphragm opposite the first side. The existing pressure difference between the first and the second pressure causes a dependent of the differential pressure to be measured deflection of the measuring diaphragm.

For detecting relative pressures of the second side of the measuring membrane is a reference pressure, for. B. an ambient pressure fed. The existing pressure difference between the first pressure and the reference pressure causes a dependent of the relative pressure to be measured deflection of the measuring diaphragm.

For the detection of absolute pressures, a closed evacuated chamber is regularly provided under the measuring diaphragm on its second side remote from the first side. Thus, the first pressure acting on the first side of the measuring diaphragm causes a deflection of the measuring diaphragm which is dependent on the absolute pressure to be measured.

The resulting deflection of the measuring membrane is in all three cases arranged on the measuring membrane sensor elements, for. As piezoresistive resistors detected and converted into an electrical output signal that is then available for further processing and / or evaluation.

Semiconductor pressure sensors are very sensitive and are therefore used in a housing, via which the supply of the respective pressures, the output of the measurement result and the installation of the pressure measuring device takes place at the measuring location.

In this case, the semiconductor pressure sensor is mounted, for example, on a socket located in the housing in such a way that a side facing away from the base first side of the measuring membrane has in a first housing located in the measuring chamber to which the first pressure is supplied. In differential or relative pressure sensors, the second pressure or the reference pressure of the second side of the measuring diaphragm is additionally supplied via a bore extending in the interior of the base, which opens into a second measuring chamber enclosed by the measuring diaphragm carrier under the measuring diaphragm. For absolute pressure measuring devices, the chamber located under the measuring diaphragm is closed and evacuated. The supply of the first and the second pressure takes place for example via integrated into the housing or upstream of this filled with a pressure-transmitting liquid diaphragm seal. The reference pressure is supplied, for example, via a reference pressure supply integrated in the housing.

The base is for example a cylindrical extension piece or a pedestal, which is formed as an integral part of the housing or as a separate housing-mounted component.

In order to ensure sufficiently high mechanical stability, the housing and socket are made of a mechanically stable material, in particular of metal.

Socket and semiconductor pressure sensor inevitably consist of different materials that have very different physical properties, esp. Different thermal expansion coefficients. Due to the mechanical connection between the base and the semiconductor pressure sensor, therefore, mechanical stresses can occur which have an effect on the transmission behavior of the measuring diaphragm and thus impair the achievable measuring accuracy and its reproducibility. This applies esp. For temperature-dependent voltages. If adhesions are used for the mechanical connections, then changes in the properties of the bond dependent on the moisture in the area of the bond can also lead to tensions.

In order to reduce the occurring voltages, an intermediate piece, which consists of the same material as the semiconductor pressure sensor, is usually inserted between the base and the semiconductor pressure sensor. However, even then occur due to the different thermal expansion coefficients of base and adapter caused, esp. Temperature-dependent, mechanical stresses that affect the transmission behavior of the measuring diaphragm.

In the DE-34 36 440 A1 and in the DE-10 2007 053 859 A1 solutions to this problem are described that allow a reduction in the adverse effects of mechanical stresses. They each include a semiconductor pressure sensor mounted on a carrier of a semiconductor. The carrier is in turn applied directly to a metal base in the housing. In this case, the base each has a significantly smaller outer diameter than the carrier. To reduce mechanical stresses on the base facing the underside of the carrier, an annular circumferential groove or a circumferential specially shaped recess is provided which serves to absorb caused by the connection between the base and carrier mechanical stresses and to avoid their repercussion on the measuring diaphragm. In addition, in the DE 34 36 440 A1 also described on the semiconductor pressure sensor facing end side of the carrier to provide a shallow recess.

However, these solutions have the disadvantage that the semiconductor pressure sensor is not completely electrically isolated from the socket because the carrier is made of a semiconductor and is inserted directly between the socket and the semiconductor pressure sensor. This involves the risk that electrical interference from the environment via the housing, the base and the carrier can be transferred to the semiconductor pressure sensor and can lead to a change in the measurement characteristics of the semiconductor pressure sensor. To avoid this, is in the DE 34 36 440 A1 described to insert the base over an insulating Glaseinschmelzung in the housing. For this, however, it is necessary to produce the base of a suitable material for these Glaseinschmelzungen.

In the DE 31 28 188 A1 and the DE 30 47 619 A1 are pressure sensing devices described in which the semiconductor pressure sensor is applied to an insulating glass plate, which is supported by a metallic base. Due to the different physical properties of the semiconductor used for the semiconductor pressure sensor and the glass, esp. Their elasticity modules, it is also necessary here for the base to use very expensive special materials with very precisely adapted to the semiconductor physical properties to repercussions to avoid the semiconductor pressure sensor.

It is an object of the invention to provide a pressure measuring device with a mounted on a base semiconductor pressure sensor in which the semiconductor pressure sensor is electrically isolated from the base and protected from mechanical stresses.

• – einem Gehäuse
• – einem auf einem Boden des Gehäuses montiertem Sockel,
• – einem auf dem Sockel montierten außenseitlich über den Sockel hinausragenden Träger aus einem Halbleiter,
• – der auf dessen vom Sockel abgewandten ersten Stirnseite eine topfförmige Ausnehmung aufweist,
• – einer auf der ersten Stirnseite des Trägers aufgebrachten die Ausnehmung überdeckenden Scheibe aus einem elektrischen Isolator, und
• – einem auf der Scheibe aufgebrachten Halbleiter-Drucksensor mit
• – einem Membranträger und einer Messmembran.

For this purpose, the invention consists in a pressure-measuring device, with

• - a housing
• A pedestal mounted on a bottom of the housing,
• A support of a semiconductor mounted on the base and projecting beyond the socket on the outside,
• - Which has a cup-shaped recess on its first end face facing away from the base,
• - An applied on the first end side of the carrier, the recess overlapping disc of an electrical insulator, and
• - A mounted on the disc semiconductor pressure sensor with
• - A membrane carrier and a measuring membrane.

According to a first embodiment of the invention, an outer circumferential groove is provided in an outer edge of the bottom of the cup-shaped recess of the carrier.

According to a second development, an outer circumferential groove is provided on an outer edge projecting beyond the base of a second end face of the carrier facing the base of the first end face facing the base.

According to a preferred embodiment, the carrier and the semiconductor pressure sensor have the same thickness, and the carrier and the semiconductor pressure sensor consist of the same semiconductor, esp. Of silicon.

According to a further embodiment, there is a mechanically fixed connection between the base and the carrier, in particular an adhesive bond or a solder connection.

According to a further embodiment, the base made of metal or ceramic.

According to a development, the disk consists of glass and is connected to the carrier and the semiconductor pressure sensor in each case via an anodic bonding.

• – in der Scheibe, im Träger, und im Sockel jeweils eine mittig angeordnete parallel zu deren Längsachse verlaufende durchgängige Bohrung vorgesehen ist, und
• – die Bohrungen zusammen eine Druckzufuhrleitung bilden, die in einer unter der Messmembran eingeschlossenen Druckmesskammer mündet.

Furthermore, the invention comprises a pressure-measuring device according to the invention for detecting differential pressures or relative pressures, in which

• - In the disc, in the carrier, and in the base in each case a centrally disposed parallel to the longitudinal axis extending through bore is provided, and
• - The holes together form a pressure supply line, which opens into a trapped under the measuring diaphragm pressure measuring chamber.

Furthermore, the invention comprises a pressure measuring device according to the invention for detecting absolute pressures, in which a pressure measuring chamber enclosed under the measuring diaphragm is completely closed and evacuated outwards through the disk.

A significant advantage of the pressure-measuring device according to the invention is that the semiconductor pressure sensor is protected by the carrier and the recess from mechanical stresses. Mechanical stresses caused by the connection between the base and the carrier have virtually no effect on the transmission behavior and the measuring properties of the measuring diaphragm. This applies both to stresses that arise due to the different thermal expansion coefficients of base and carrier, as well as for stresses that arise through changes in the connection between base and carrier, such. B. moisture-modified properties of a bond. Accordingly, the achievable measurement accuracy is ensured with a high long-term stability and high reproducibility.

At the same time, the disk effects an electrical insulation of the semiconductor pressure sensor relative to the base. Since the disc according to the invention is sandwiched between the semiconductor pressure sensor and the preferably made of the same semiconductor carrier, adverse effects of the different physical properties of the insulator, which consists of the disc, and the semiconductor of the semiconductor pressure sensor are largely avoided. The high symmetry of this construction, a substantial absence of voltage of the system is achieved, which is additionally supported by the effected by the recess in the carrier decoupling of this system relative to the base. If, for example, glass is used as the insulator, this design offers the further advantage that the semiconductor pressure sensor, glass pane and carrier can now be connected to one another without regard to the material of the base by anodic bonding.

The invention and its advantages will now be explained in more detail with reference to the figures of the drawing, in which two embodiments are shown. Identical elements are provided in the figures with the same reference numerals.

1 shows a section through an absolute pressure measuring device according to the invention; and

2 shows a section through a differential pressure or relative pressure measuring device according to the invention.

1 and 2 each show a section through an embodiment of a pressure-measuring device according to the invention. At the in 1 illustrated variant is a pressure-measuring device for measuring absolute pressures, while the in 2 shown variant for measuring relative or differential pressures is used. Since the two pressure-measuring devices are substantially identical, they are initially described together. Subsequently, the differences caused by the different measuring tasks will be briefly explained.

Both variants comprise a housing only partially shown here 1 on the bottom of which is a pedestal 3 is mounted. The housing 1 consists for example of a metal, for. B. a stainless steel. The base 3 For example, can also be made of this metal or ceramic. Ceramic offers the advantage that it has a coefficient of thermal expansion which is closer to the coefficient of thermal expansion of semiconductors customarily used for the production of semiconductor pressure sensors.

For capturing absolute pressures is suitable as a pedestal 3 For example, a cylindrical extension or a pedestal, as an integral part of the housing 1 or as a separate one in the case 1 fastened component can be formed. For the detection of differential or relative pressures is preferably - as in 2 shown - a tubular base 3 ' used that through the bottom of the case 1 leads through, and there is glazed or soldered.

On the pedestal 3 . 3 ' is each a carrier 5 assembled. Between the pedestal 3 . 3 ' and the carrier 5 there is a mechanically strong connection 7 , z. As an adhesive, esp. An epoxy resin bond, or a solder joint.

The carrier 5 has a larger footprint than the pedestal 3 so that it is on all sides outside over the pedestal 3 . 3 ' protrudes.

He is essentially disc-shaped and points to the base 3 . 3 ' remote from the first end face a cup-shaped recess 9 on. On this first front side of the carrier 5 is a slice 11 applied to the recess 9 covered.

The central element of the pressure-measuring device forms a semiconductor pressure sensor 13 the one on the carrier 5 opposite end face of the disc 11 is applied. The semiconductor pressure sensor 13 is a pressure sensor chip on a semiconductor basis, esp. Silicon-based, and has a membrane carrier 15 and one of the membrane carrier 15 carried measuring diaphragm 17 on.

Preferably, the carrier is made 5 and the semiconductor pressure sensor 13 from the same semiconductor, esp. from silicon.

carrier 5 , Disc 11 and semiconductor pressure sensor 13 preferably have the same shape base surfaces and are arranged coaxially one above the other.

The disc 11 consists of an insulator, z. As glass, silica or sapphire.

About the disc 11 Consequently, there is a high-quality electrical isolation of the semiconductor pressure sensor 13 opposite the carrier 5 , the pedestal 3 . 3 ' and the housing 1 ,

Glass offers the advantage that it can be connected to semiconductors, in particular by anodic bonding, simply and inexpensively. carrier 5 , Disc 11 and semiconductor pressure sensor 13 are preferably interconnected in an individual batch process via anodic bonds. Alternatively, the connections achieved by anodic bonding between carriers 5 and disc 11 and between disc 11 and semiconductor pressure sensor 13 also be generated in individual processes. In that case, one in the 1 and 2 dashed disk 11 ' used, which has a larger footprint than the carrier 5 and the semiconductor pressure sensor 13 , The disc 11 ' has a protruding outer edge over which the electrical voltage required for anodic bonding in individual processes can be applied. Silicon dioxide and sapphire disks and methods for bonding them to semiconductor wafers are known from the silicon-on-insulator technology.

The carrier 5 causes esp. Due to the disc 11 respectively. 11 ' facing recess 9 a mechanical decoupling with respect to the semiconductor pressure sensor 13 , Esp. are affected by the temperature or environmental influences, such. B. Moisture in the compound 7 , resulting mechanical stresses due to the recess 9 in the carrier 5 collected. This protection of the semiconductor pressure sensor 13 is additionally through the disc 11 respectively. 11 ' supported.

The quality of this decoupling can be further improved by the pot-shaped recess in an outer edge of the bottom 9 of the carrier 5 an outside circumferential additional groove 19 is provided. Preferably, moreover, also on an outer over the base 3 . 3 ' protruding free edge of a pedestal 3 . 3 ' facing the first end opposite the second end face of the carrier 5 an outside circumferential groove 21 intended.

The basic geometry of the arrangement preferably follows that through the base of the membrane carrier 15 given geometry. In a membrane carrier 15 with disc-shaped bearing surface are the disc 11 respectively. 11 ' , the carrier 5 and its recess 9 corresponding circular disk-shaped, and the grooves 19 and 21 are ring-shaped. Indicates the bearing surface of the membrane carrier 15 on the other hand, the shape of a rectangular frame on, so are the disc 11 respectively. 11 ' , the carrier 5 and its recess 9 corresponding rectangular shaped, and the grooves 19 and 21 have the shape of a rectangular frame.

To achieve the most symmetrical arrangement, have the carrier 5 and the semiconductor pressure sensor 13 preferably the same thickness d.

At the in 1 shown pressure measuring device for detecting absolute pressures is located under the diaphragm 17 one from the membrane carrier 15 enclosed pressure measuring chamber 23 going out through the measuring membrane 17 , their membrane carrier 15 and the disc 11 respectively. 11 ' completely completed and evacuated. This causes an external on the measuring diaphragm 17 acting pressure to be measured p due to the evacuation of the pressure measuring chamber 23 an absolute pressure dependent deflection of the measuring diaphragm 17 based on on the measuring membrane 17 arranged sensor elements 25 , such as As piezoresistive resistors, detected, and is converted into an electrical output signal. The output signal is then transferred to the sensor elements 25 connected connecting cables 27 for further processing and / or evaluation.

In contrast to this is the pressure measuring chamber 23 the in 2 illustrated pressure-measuring device for detecting relative or differential pressures via a pressure supply line, a second pressure p _R supplied. In a relative pressure measurement, the pressure p _{R is} a reference pressure to which the pressure to be measured p is to be related. In a differential pressure measurement, the pressure p _{R is} a second pressure and it is the difference between the outside of the measuring diaphragm 17 acting pressure p and the inside of the measuring diaphragm 17 acting second pressure measured.

The supply of this second pressure p _R is preferably carried out in the disc 11 respectively. 11 ' , in the vehicle 5 , and in the pedestal 3 ' each centrally disposed parallel to the longitudinal axis extending through holes 29 . 31 . 33 , which together form the pressure feed line, which in the under the measuring diaphragm 17 enclosed pressure measuring chamber 23 empties.

Correspondingly, the pressure difference existing between the pressure p and the second pressure p _R causes a deflection of the measuring diaphragm which is dependent on the differential pressure to be measured or on the relative pressure to be measured 17 that over on the measuring diaphragm 17 arranged sensor elements 25 is measurable.

LIST OF REFERENCE NUMBERS

1

casing

3, 3 '

base

5

carrier

7

connection

9

recess

11, 11 '

disc

13

Semiconductor pressure sensor

15

membrane support

17

measuring membrane

19

groove

21

groove

23

Pressure measuring chamber

25

sensor element

27

connecting cable

29

drilling

31

drilling

33

drilling

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3436440 A1 [0014, 0014, 0015]
• DE 102007053859 A1 [0014]
• DE 3128188 A1 [0016]
• DE 3047619 A1 [0016]

Claims (10)

Pressure measuring device, with - a housing ( 1 ), - one on a bottom of the housing ( 1 ) mounted base ( 3 . 3 ' ), - one on the base ( 3 . 3 ' ) mounted on the outside of the base ( 3 . 3 ' ) ( 5 ) from a semiconductor, - the one on the base ( 3 . 3 ' ) facing away from the first end face a cup-shaped recess ( 9 ), - one on the first end face of the carrier ( 5 ) applied the recess ( 9 ) covering disc ( 11 . 11 ' ) from an insulator, and - one on the disc ( 11 . 11 ' ) applied semiconductor pressure sensor ( 13 ) with - a membrane carrier ( 15 ) and a measuring membrane ( 17 ). Pressure-measuring device according to claim 1, wherein in an outer edge of the bottom of the cup-shaped recess ( 9 ) of the carrier ( 5 ) an outer circumferential groove ( 19 ) is provided. Pressure measuring device according to claim 1, wherein on an outer over the base ( 3 . 3 ' ) protruding exposed edge of the base ( 3 . 3 ' ) facing the first end opposite the second end face of the carrier ( 5 ) an outer circumferential groove ( 21 ) is provided. Pressure measuring device according to claim 1, in which the carrier ( 5 ) and the semiconductor pressure sensor ( 13 ) have the same thickness (d). Pressure measuring device according to claim 1, in which the carrier ( 5 ) and the semiconductor pressure sensor ( 13 ) consist of the same semiconductor, esp. Of silicon. Pressure measuring device according to claim 1, wherein between the base ( 3 . 3 ' ) and the carrier ( 5 ) a mechanically strong connection ( 7 ), esp. A bond or a solder joint exists. Pressure measuring device according to claim 1, wherein the base ( 3 . 3 ' ) consists of metal or ceramic. Pressure measuring device according to claim 1, wherein the disc ( 11 . 11 ' ) consists of glass and with the carrier ( 5 ) and the semiconductor pressure sensor ( 13 ) is connected in each case via an anodic bonding. Pressure measuring device according to one of claims 1 to 8, for detecting differential pressures or relative pressures, in which - in the disc ( 11 . 11 ' ), in the carrier ( 5 ), and in the base ( 3 ' ) each have a centrally disposed parallel to the longitudinal axis extending through bore ( 29 . 31 . 33 ), and - the holes ( 29 . 31 . 33 ) together form a pressure feed line which is located in a below the measuring diaphragm ( 17 ) enclosed pressure measuring chamber ( 23 ) opens. Pressure-measuring device according to one of claims 1 to 8, for the detection of absolute pressures, in which a below measuring diaphragm ( 17 ) enclosed pressure measuring chamber ( 23 ) out through the disc ( 11 . 11 ' ) is completely completed and evacuated.

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