DE102014000243A1 - MEMS sensor for difficult environments and media - Google Patents

Abstract

The invention relates to a typically CMOS processed micromechanical sensor (3) made of silicon, with a sensor cell and at least one micromechanical functional element which, with its CMOS surface, can be in direct contact with an aggressive medium. The micromechanical sensor (3) has at least one first region (A) on the CMOS processed surface, which comprises the sensor cell and which can be used for direct contact with the medium. It is essential that this first area (A) has no metallization and is therefore not susceptible to corrosion. Furthermore, the sensor according to the invention has a second region (B), which likewise has no metallization. It is the function of the second area (B), together with a first seal or molding compound (77), to seal the passage of the medium into a third area (C) of the micromechanical sensor and thus to prevent it. The bond system and all circuit components requiring metallization are located in a third area (C). The second area (B) is always on the processed surface between the third area (C) and the first area (A) so that the third area (C) is not touched by the first area (A) on the processed surface.

Description

introduction

In many applications, the measurement of pressures in difficult environments is of particular importance. This results in the problem that the pressure sensors must be supplied with the media pressure. For this purpose, the pressure sensors should be brought as close as possible to the pressure chamber to prevent distortions of the measurement result. Direct contact between the sensor membrane and the medium to be measured is desirable.

In the prior art, various solutions are known for this purpose. As an example, the US8049290B2 to call, in which the medium is supplied via the back of a plastic housing. The Indian US8049290B2 shown sensor (reference numeral 2 of the US8049290B2 ) consists of three parts: A middle MEMS chip, which has the actual piezoresistive sensor structures on its upper side, ie the sensor surface opposite the access opening, a glass cap bonded thereto which typically forms the typically evacuated reference cavity with the middle chip and one lower chip, the so-called constraint wafer, with a hole that extends through this lower chip and typically into the middle area. Such a sensor is without Constraint Wafer example from the US20030167851A1 known. The sensor of US20030167851A1 However, in a conventional method typically is still provided with a pierced bottom plate made of glass, the said constraint wafer, which increases the area moment of inertia of the micromechanical pressure sensor and thus increases its torsional stiffness. This glass component is in the US8049290B2 with access hole in addition to the US20030167851A1 located. The sensor package (reference numeral 2 of the US8049290B2 ) is in the US8049290B2 glued to a leadframe (reference numeral 3 of the US8049290B2 ). So that the leadframe does not corrode, the molding compound covers (reference numeral 5 of the US8049290B2 ) in the region of the access opening (reference numeral 21 of the US8049290B2 ) also the leadframe (reference number 3 of the US8049290B2 ). The main disadvantage of this very expensive technique is that on the one hand a complex glass cap (reference numeral 54 of the US20030167851A1 ) And on the other hand a very expensive etching step for etching through the substrate (reference numeral 38 of the US20030167851A1 ) for forming the membrane (reference numeral 40 of the US20030167851A1 ) requires. The pressure may be in the construction of the US8049290B2 from the back the membrane (reference numeral 40 of the US20030167851A1 ), but not the electronic components located on the other side of the diaphragm, the front. On the front are also the bonding wires (reference numeral 6 of the US8049290B2 ). These are thus as well as the bond pads of the pressure sensor (reference numeral 2 of the US8049290B2 ) and the evaluation circuit (reference numeral 10 of the US8049290B2 ) protected against corrosion by the medium whose pressure is to be measured. A disadvantage of such a solution for measuring the pressure in aggressive media, moreover, is that the extent of such a sensor is so large that it can not be integrated into an M5 screw. Also occurring mechanical stresses between a potting compound, the sensor element and the sensor housing must be intercepted so that there is no change in the measurement signal. All this is particularly critical in integration into a screw for exemplary use in an oil pan of a motor vehicle. For this purpose, it is useful, almost necessary if the respective pressure-sensitive element can be installed in a screw, which in turn can be very easily installed in a tank, a pipe or the like for measuring the pressure of a medium in the pipe. Such a sensor system is for example from the DE3021088A1 known. This sensor, which measures the pressure during combustion in the cylinder chamber, is only suitable for measuring high pressures. The revelation DE3021088A1 leaves completely open as to how the electrodes mentioned in the disclosure are protected from corrosion. For the co-integration of an amplifier, the proposed materials plastic / ceramic are completely unsuitable because it is not a semiconductor material.

Also from the DE10360941A1 For example, a screw is known as the outer shape of a sensor system. The problem of corrosion of the lines and possibly also of the sensor elements is solved in this disclosure so that the one measuring device (reference numeral 6 of the DE10360941A1 ) on a membrane, or "material weakening" (reference numeral 23 of the DE10360941A1 ) is attached. In this case, this membrane (reference number 23 of the DE10360941A1 ) together with the main body (reference numeral 2 of the DE10360941A1 ), ie the screw body. However, this very good solution leads to the fact that the measuring device (reference numerals 6 of the DE10360941A1 ) is no longer in direct contact with the medium to be measured, but the pressure in the medium must be transmitted only by the material weakening and the fastening means of the measuring device. This design is unsuitable for MEMS systems.

In the Revelation DE102004002089A1 discloses a pressure sensor system in the form of a screw, which is also the measurement of the Internal pressure to serve in the cylinders of an internal combustion engine. The sensor element (reference numeral 21 of the DE102004002089A1 ) is not specified. In the DE102004002089A1 is not explained in detail how the line system of the sensor system (reference numeral 21 of the DE102004002089A1 ) is protected against corrosion in this extreme environment. In addition, the sensor element (reference numeral 21 of the DE102004002089A1 ) is mounted with the surface normal parallel to the axis of the sensor system, resulting in an enlargement of the bore, as the lines typically have to be fed from the sides. Therefore, the screw and the screw head in the DE102004002089A1 logically larger than the shaft drawn. This enlarged bore leads to a weakening of the pressure chamber.

Also from the DE2008046515A1 and the DE102009048702A1 Similar screw solutions are known which, however, also do not allow the direct contact of a micromechanical pressure sensor with an aggressive medium.

However, especially for the measurement of aggressive liquids, such as engine oil, micromechanical pressure sensors are becoming increasingly popular because they can be produced inexpensively in large quantities and have a whole series of further advantages known from the prior art. For this purpose, the micromechanical pressure sensors, which are typically made of silicon, must be brought into the most direct possible contact with the pressure of the medium to be measured in a suitable measuring device. However, it is now a generally accepted view that the respective medium, in particular engine oils and other vehicle consumables assume a more or less undefined composition over the lifetime of the respective product. Therefore, there is currently a widespread belief among those skilled in the art that the electrical structures of the pressure sensors, typically made in CMOS or similar semiconductor technology, should be spatially separated as far as possible from the typically aggressive medium in the art. In particular, the medium should not come into direct contact with the processed upper side of the respective MEMS pressure sensor, ie typically the CMOS components. This paradigm leads to the known various disadvantages. In particular, in the case of a simultaneous temperature measurement, this leads to problems with the reaction rate of the system, since the heat capacity is increased significantly and the temperature sensor usually has to be placed further from the medium.

All but one of the solutions have in common that they only incompletely solve the problem of protecting a micromechanical pressure sensor.

Only in the US8049290B2 named housing solves this problem when it is installed in a screw. However, the micromechanical sensor used there is relatively complex and therefore expensive.

The WO2011083161A2 discloses surface micromechanical technology and associated pressure sensors without, however, naming the structural features necessary to ensure reliable corrosion protection for the metallization. The WO2011083161A2 discloses various ways to realize pressure sensors by means of transistors. Here, the gates can act as electrostatic shields, which prevent the diffusion of protons into the piezoresistive resistors, the transistors.

A suitable, compact and less expensive solution which reliably prevents the corrosion of the bonding system and permits direct contact of the medium with the top surface of the micromechanical sensor on which the active structures of the micromechanical pressure sensor are located is not known from the prior art known. However, another significant problem arises due to the space requirement of the sensors and the associated evaluation circuit.

Object of the invention

It is the object of the invention to provide a micromechanical pressure sensor which allows system integration into an M5 screw, is robust to aggressive media and precludes damage to the bonding system by mechanical stresses, in particular by a potting compound. In particular, it should be possible for the active structures of the micromechanical pressure sensor on the upper side of the micromechanical sensor with precisely this surface to be brought into direct chemical and thermal contact with the medium. For this purpose, the essential structural features of the micromechanical pressure sensor are disclosed, which makes it possible to prevent corrosion of the metal system of the micromechanical pressure sensor in the intended sensor system, which is also disclosed. This object is achieved with a device according to claim 1.

Description of the invention.

The invention is based on the finding that silicon, SiN and SiO _{2 are} typically resistant to the common aggressive media can be viewed. Only the diffusion of protons from acids into the p-resistors of the piezoresistive sensor cell counteracts this. Furthermore, it is crucial to realize that metal railways represent a significant risk. Small typically existing manufacturing defects in the passivation of microelectronic circuits can allow an aggressive medium access to the metal tracks and thus cause unwanted corrosion of the conductor metal. In the US8049290B2 This was achieved by covering the leadframe with molding compound and restricting access to the back. As stated above, this design results in significant cost increases, apart from the increase in chip area.

In order to bring the front of a micromechanical pressure sensor in contact with the aggressive medium, which is not possible in the prior art, it is therefore essential that the area of the sensor surface, which comes into direct contact with the aggressive medium, for a no Having materials that could be corroded, and that on the other hand, the field-driven diffusion of ions, and especially the diffusion of protons from an acid is stopped by a suitable construction. In addition, the parts of such a pressure sensor containing metal, so in particular the bond pads and the bonding system, must be reliably protected from access of the medium. Opposite in the WO2011083161A2 mentioned features are therefore very special, design changes necessary.

In particular, it has been recognized within the scope of the invention that it is necessary for at least one region to be provided on the CMOS-processed surface of the micromechanical pressure sensor which has no metal. From the WO2011083161A (eg page 15 lines 7 to 11 of the WO2011083161A Although it is known that the metal on the surface of the sensor must be minimized in order to avoid thermal hysteresis. What protection against aggressive media must look like remains completely open.

This disclosure takes advantage of the priorities and disclosure of the applications DE102013007619.6 . DE102013016638.1 . DE102013016634.9 and DE102013016637.3 if applicable and extends its content. In this respect, the disclosure of these applications is also part of this disclosure.

The invention is based on the 1 to 23 the example of a pressure sensor measuring system with a screw thread and the associated sensor, which is claimed here explained. Other configurations and designs are of course possible. It shows

1 a schematic cross-section, not to scale, through a device comprising the micromechanical sensor according to the invention along the screw axis;

2 a schematic cross-section, not to scale, through a device comprising the micromechanical sensor according to the invention, along the screw axis, with a view of the sensor or pressure sensor and the evaluation circuit;

3 the schematic not to scale side view of the device comprising the micromechanical sensor according to the invention (corresponds to 1 )

4 the schematic not to scale side view of the device comprising the micromechanical sensor according to the invention (corresponds to 2 )

5 a simplified, schematic and not to scale cross section through a pressure sensor according to the invention,

6a a simplified, schematic and not to scale cross section through a pressure sensor according to the invention, said trenches for connection to a seal,

6b a simplified, schematic and not to scale supervision of a pressure sensor according to the invention, said trenches for connection to a seal,

7 a schematic not to scale cross-section through a device comprising the micromechanical sensor according to the invention, along the screw axis with a view of a pressure sensor according to the invention and the evaluation circuit, the pressure sensor according to the invention has a wedge shape to improve the seal,

8th shows the exemplary pressure sensors according to the invention in wedge shape in a schematic not to scale supervision in the wafer composite,

9 a schematic not to scale cross section through a device comprising the micromechanical sensor according to the invention, along the screw axis with a view of the exemplary pressure sensor according to the invention and on the evaluation circuit, wherein instead of a thread, a fit is attached to the outside,

10 a schematic not to scale cross section through a device comprising the micromechanical sensor according to the invention, along the screw axis with a view of the exemplary pressure sensor according to the invention and the evaluation circuit, instead of a thread, a fit is mounted outside and the device is installed in the opening of a wall and the sensor area (first area A) of the pressure sensor according to the invention is surrounded by a medium to be measured,

11 - 21 an exemplary manufacturing method for a sensor system comprising the micromechanical sensor according to the invention,

11 a support which serves as the basis for the system comprising the micromechanical sensor according to the invention,

12 the carrier off 11 after attaching the second seal by Ummolden,

13 the carrier off 12 after application of the adhesive for the evaluation circuit and the sensor according to the invention,

14 the carrier off 13 after the application (die bond) of the evaluation circuit,

15 the carrier off 14 after the application (die bond) of the sensor according to the invention,

16 the carrier off 15 after bonding the evaluation circuit on the plug side,

17 the carrier off 16 after establishing the electrical connections between sensor according to the invention and evaluation circuit by bonding,

18 the sensor system after assembly of carrier 17 and sensor housing,

19 the sensor system off 18 after the introduction of the gel,

20 the sensor system off 19 supplemented by a sealing ring,

21 the sensor system off 20 closed with the first seal,

22 a schematic, not to scale cross section through a pressure sensor according to the invention similar 5 wherein this has sealing regions on both sides of a micromechanical functional element,

23 a schematic, not to scale supervision on the exemplary pressure sensor according to the invention accordingly 22 .

24 a schematic cross section through an exemplary housing for the exemplary pressure sensor of the films 22 and 23 ,

It is of particular advantage if the sensor system can be designed in the form of an M5 or M10 screw. This is in 1 not shown to scale. The screw is threaded ( 1 ) and a screw head ( 32 ) Mistake. It will be clear to a person skilled in the art that threads in this sense can also be understood as meaning similar machine elements which can lead to a connection between a hole in a workpiece and the pressure sensor system. Such machine elements can also be, for example, interference fits and bayonet locks, a slip fit for and glued, welded or soldered joints a bolt outer surface for a bolt connection and a wedge outer surface for a spline connection, etc.

The further description refers to a screw with a thread. In the claims, however, is spoken by a machine element for connection to an opening.

When talking about an axis of the machine element for connection to the connection with an opening, so it is meant a line along which the sensor housing is moved during assembly to a designated place of use. For example, a screw is screwed into an opening along the screw thread axis. In this case, the screw moves along this said axis of the machine element for connection to the connection with an opening (threaded axis) into the mounting opening. If it is a fit, the sensor housing may be moved into the mounting hole without rotation.

For the purpose of better understanding only one screw is treated here. Those skilled in the art will be aware of the modifications required for the use of other fastening techniques.

The screw can of course be chosen longer if necessary. The position of the screw head ( 32 ) can on the longitudinal axis of the screw ( 37 ) are chosen differently. Of the Screw head ( 32 ) is, for example, with a circumferential groove ( 31 ) provided with a sealing ring ( 30 ). As a result, the pressure sensor housing pressure-tight, for example, be attached by a simple M5 or M10 bore to a pressure hull.

The screw is with a longitudinal bore ( 2 ) provided sufficient width. The diameter of the pressure sensor housing and bore diameter must be selected appropriately.

The pressure sensor housing ( 100 ) is also typically provided internally with two circumferential grooves. The first groove ( 10 ) provides a mechanical connection between the first seal ( 11 ) on the media side and the pressure sensor housing ( 100 ). The second groove ( 33 ) fixes the second seal ( 34 ) to the closure of the sensor housing ( 100 ) on the electrical contact side. This allows the electronics through the medium to be measured ( 73 . 10 ) can not be pushed out under pressure.

The core of the device is a carrier ( 18 ), for example, a board (PCB), the actual micromechanical sensor ( 3 ), for example a MEMS pressure sensor, and the evaluation circuit (IC) ( 21 ) wearing. Instead of a PCB, which typically consists of a composite material, of course, the use of an MID lead frame is conceivable. Also, other insulating organic or inorganic substrates can be used. Such may, for example, consist of a ceramic or a glass carrier or a mono- or polycrystalline wide-bandgag material such as sapphire. The use of conductive or semiconductive materials as a carrier material is also conceivable. However, these must be coated on at least one side insulating. If in the following and in the claims of "carrier" is spoken, therefore, such constructions, such. As those outlined, included, the equal or close to the function of a PCB. In addition, the said carrier ( 18 ) different tracks ( 36 ) and conductive islands ( 19 ) and ( 17 ), which are used for fastening the evaluation circuit ( 21 ) and the micromechanical sensor ( 3 ), for example a MEMS pressure sensor. For the production of such metal islands, various methods are known from the prior art, which are not further described here, since they are obvious to the person skilled in the art.

The micromechanical pressure sensor ( 3 ) is typically with an adhesive ( 16 ) on the mounting surface ( 17 ) for the micromechanical pressure sensor ( 3 ) mounted on the support ( 18 ) is located.

Likewise, the evaluation circuit ( 21 ) with a similar or identical adhesive ( 20 ) on an analogous mounting surface ( 19 ) for the evaluation circuit ( 21 ) on the support ( 18 ), z. As a PCB, attached.

The micromechanical pressure sensor ( 3 is on the media side so from a first seal ( 11 ) that no medium at the interface between micromechanical pressure sensor ( 3 ) and first seal ( 11 ) as well as first seal ( 11 ) and sensor housing ( 100 ) can pass through. The material of the first seal ( 11 ) fills the first groove ( 10 ) of the sensor housing ( 100 ) so that this groove ( 10 ) is preferably also filled with the material of the first seal. As a result, the media pressure is not able, the first seal ( 10 ) into the interior of the sensor housing.

The micromechanical pressure sensor ( 3 ) penetrates this first seal ( 11 ) in such a way that on the one hand the actual measuring cell (first area A 5 ) far enough from the first seal ( 11 ) is removed and is not covered by their material. The measuring cell of the pressure sensor consists for example of the evacuated pressure sensor cavity ( 71 ), the piezo resistors ( 50 . 51 . 52 . 53 ) and essential parts of the supply lines ( 6 . 9 ). The first seal ( 11 ) encloses the micromechanical pressure sensor ( 3 ) in a second area (second area B 5 ) in which the micromechanical pressure sensor ( 3 ) preferably no metallizations or functional elements, in particular on the surface of the micromechanical pressure sensor ( 6 ), which are micromechanical in nature or made of materials that can be corroded or influenced by the medium to be measured. This second area (B) is in the WO2011083161A2 not disclosed, which only speaks of the fact that the leads of the piezo-resistive resistors should be carried out in silicon if possible (page 15 lines 7 to 11 of WO2011083161A2 ) and / or the bonding pads to a maximum distance from the piezo-sensitive sensor elements to remove (page 20 lines 16 to 21 of WO2011083161A2 ). The WO2011083161A in particular, does not disclose that such a metal-free second region (B) must lie between the micromechanical functional elements for pressure measurement in the first region (A) and the bonding system in a third region (C) which serves for the sealing. In this case, the medium, for example, the oil of an internal combustion engine, in particular in contaminated form, so for example, with a significantly different pH, and the influence or corrosion caused by the impurities. In the case of oil of an internal combustion engine as a medium such impurities may be, for example, acids, etc., which are formed by the combustion in the combustion chamber of the engine.

The micromechanical pressure sensor has an intermediate oxide ( 5 . 5 ), the piezo-resistive resistors ( 50 . 51 . 52 . 53 ) and again with a protective layer, for example made of poly-silicon ( 4 . 5 ) is covered. Poly-silicon is referred to below and here polycrystalline silicon. This layer ( 4 ) also covers the membrane ( 7 . 5 ) of the pressure measuring cell ( 8th ). As a result, the pressure measuring cell located in the aggressive medium ( 8th ) protected from the medium to be measured.

It is conceivable, instead of or in addition to this layer ( 4 . 5 ) to use other layers such as SiN. Also, a sufficiently thick version of the oxide ( 5 . 5 ) already provide sufficient protection for the respective application. In this case, the layer ( 4 . 5 ) possibly even omitted. SiN offers the advantage of reducing the diffusion of hydrogen.

On the other side of the first seal ( 11 ) are the contacts ( 13 ) of the micromechanical pressure sensor (third area C, 5 ) free. The first seal ( 11 ) is thus located only in an intermediate area (second area B 5 ) between contacts ( 13 ) (third area C 5 ) and sensor measuring cell ( 8th . 7 ) (first area A 5 ).

In order to be able to contact the micromechanical pressure sensor, the intermediate oxide layer ( 5 ) in the area of contacts ( 13 ) (third area C 5 ) open. These openings ( 13 ) are bonded to the bond pad metal ( 14 ) to make bondability.

Bonding wires ( 15 ) connect the evaluation circuit ( 21 ) with the micromechanical pressure sensor ( 3 ). The bonding can for example be done so that the bond ball ( 22 ) on the evaluation circuit ( 21 ) and the wedge bond on the contact surface ( 14 ) of the micromechanical pressure sensor ( 3 ).

For simplicity, the circuits of the evaluation circuit ( 21 ) only simplified ( 24 ). Also the evaluation circuit ( 21 ) is characterized by an oxide and a passivation ( 25 ) protected. The evaluation circuit ( 21 ) has suitable bond areas ( 26 . 23 ) to allow electrical connection.

The Bond Ball ( 22 ) of the bonding wire ( 15 ) is deposited on such a bond pad ( 23 ) of the evaluation circuit ( 21 ) discontinued.

The connection of the evaluation circuit ( 21 ) to the outside by another bond wire ( 28 ) between evaluation circuit ( 21 ) and conductor track ( 36 ) on the support ( 18 ) produced. In the example, the associated wedge-bond ( 29 ) on the track ( 36 ) and the bond ball ( 27 ) on the evaluation circuit ( 21 ).

The interior of the sensor housing ( 100 ) is on the side facing away from the media by another seal ( 34 ) sealed. This extends in this example as already the first seal ( 11 ) on the media side into a second circumferential groove ( 33 ) into it.

This seal ( 34 ) is passed through the PCB ( 18 ) and the wiring ( 19 ). The external parts of the wiring ( 36 ) of the PCB ( 35 ) can be gold plated and used as a plug ( 36 ) be used.

The interior of the sensor housing ( 100 ) is preferably with a gel ( 12 ) in order to minimize the mechanical influences and the evaluation circuit ( 21 ) and to protect the bond system.

2 also shows a cross section through the sensor screw. Now, however, the carrier ( 18 ), the evaluation circuit ( 21 ) and the micromechanical pressure sensor ( 3 ) shown in supervision.

The external board connector consists in this example of four lines ( 38 . 39 . 40 . 41 ). These may be, for example, a positive voltage supply, a ground connection and two data lines - for example clock and bidirectional data or RX and TX lines.

These four lines ( 38 . 39 . 40 . 41 ) are equipped with four bonding wires ( 42 . 43 . 44 . 45 ) with the evaluation circuit ( 21 ) connected. The evaluation circuit ( 21 ) is with an adhesive ( 20 ) on the mounting surface ( 19 ), the part of the printed circuit ( 18 ).

On the side facing the medium is the evaluation circuit ( 21 ) with four bond wires ( 46 . 47 . 48 . 49 ) with the micromechanical pressure sensor ( 3 ), an exemplary pressure sensor. These four connections represent, for example, a ground connection, the power supply and the two outputs of a Wheatstone bridge.

This Wheatstone bridge consists in this example of the piezoresistive resistors ( 50 . 51 . 52 . 53 ), which are connected to this Wheatstone bridge.

The resistors ( 50 . 51 . 52 . 53 ) are, as usual in piezoresistive pressure sensors, suitable over a pressure sensor membrane ( 7 ).

The micromechanical pressure sensor ( 3 ) is with glue ( 16 ) on the mounting surface ( 17 ), the part of the carrier ( 18 ).

In 2 it can be seen that the first seal ( 11 ) again the sensor cell ( 8th ), here a pressure sensor cell, and the bonding surfaces of the micromechanical pressure sensor ( 3 ).

3 and 4 show the sensor housing ( 100 ) from the page in the views that the 1 and 2 correspond.

5 shows in a simplified, not to scale cross section through the micromechanical pressure sensor ( 3 ). Next shows 5 In particular, section B is greatly shortened and the vertical dimensions of the layers are increased while the thickness of the sensor (FIG. 4 ) is shown in reduced size. It is therefore only an illustration of the essential features for a person skilled in the art.

In this example (see 5 ) is a pressure sensor in Buried Cavity technology. This is done in a handle wafer ( 62 ) coated with an oxide layer ( 60 ), a recess ( 57 ) etched photolithographically. After cleaning, a device wafer ( 61 ) bonded to the handle wafer and thinned by mechanical and chemical polishing until the thickness of the device wafer material over the thus formed cavity ( 71 ), ie the membrane ( 7 ) corresponding to the target membrane thickness.

Processes for the production of such sensors are for example in the WO2011083161A2 described.

The cross section shows the piezoresistive p-resistors ( 53 ) and ( 50 ). These are generated via highly doped p + semiconductor regions ( 6 . 9 . 57 . 58 . 59 ) connected.

It is particularly advantageous and the essential inventive idea of this disclosure if in the area of the first seal (second area B) and in the area of the sensor cell (first area A) only those doped areas for connecting the sensor measuring cell (FIG. 8th ) to be used. This has thermo-mechanical advantages and advantages of corrosion protection, since silicon is considerably more resistant to many corrosive substances.

The pressure measuring cell ( 8th ) is with a thin oxide ( 56 ) of typically 2 nm to 40 nm. In the field of piezoresistive resistors ( 53 ) and ( 50 ) are preferably at least partially each by a poly-silicon shield ( 55 ) and ( 54 ), the respective piezoresistive resistance ( 53 ) and ( 50 ) protects. The construction is typically characterized by another oxide ( 5 ) at least partially covered. It is known that it is advantageous to use the membrane ( 7 ) from the covering by this oxide ( 5 ) or to make the oxide diluted in this area. This is in 5 however not so drawn for the sake of simplicity.

The sensor cell is so far with poly-silicon ( 4 ) that access of aggressive chemicals is not possible. This feature of full-area coverage of the sensor cell with poly-silicon ( 4 ) is in the US8049290B2 and the WO2011083161A2 so not disclosed and represents a difference according to the invention to the prior art. The WO2011083161A2 discloses only the local coverage of the piezo-resistors with a first poly-silicon structure, which the poly-silicon shields ( 54 . 55 ) corresponds. This cover ( 4 ) with the same thermal expansion coefficient as the membrane, in addition suppresses ion diffusion driven by an electric field.

As already described above, the use of other materials for this layer ( 4 ) conceivable. Also a combination of different corrosion protection layers is conceivable. An important function of the layer stack used is, for example, the protection against the penetration of protons, for example from moisture, which otherwise can lead to a drift of the piezoresistive resistors.

At the other end are the p + feeders ( 9 ) through contacts ( 14 ) so accessible that bonding is possible. (third area C, 5 )

As a rule, a compensation of the temperature range of the pressure measuring cell is required. Therefore, a temperature measurement in the immediate vicinity of the pressure measuring cell makes sense. For this purpose, in the case of a piezoresistive pressure sensor, it is advantageous to use a structure similar to the resistance structures, which are used as piezoresistive resistors of the Whaetstone bridge of the pressure sensor according to the invention, for the temperature measurement. In the simplest case, such a piezoresistive resistor is additionally in the range A (see 6 ) with the difference that it is placed as far as possible from all edges including the membrane in order to exclude mechanical stress as an influencing factor. An embodiment of the system according to the invention can thus also be distinguished by an additional temperature sensor or an additional temperature sensor cell, which is typically arranged in the region A. Thus, such a sensor system, as a special feature of the sensor system according to the invention, at least two sensors and / or at least two sensor cells on which either at least one of the sensors is a temperature sensor or at least one sensor cell is a temperature sensor cell and either at least one sensor ( 3 ) is a pressure sensor or at least one sensor cell ( 8th ) is a pressure sensor cell.

Since the temperature sensor cell is preferably placed in region A, in which no metal should be used, it is necessary to connect this temperature sensor cell, as in the above-described connection of the pressure sensor cell, preferably by highly doped p + semiconductor lines and this as in the pressure measuring cell up to to carry the area C, where the electrical connection or the electrical connection with the evaluation circuit via bonding pads, so a metal system, can take place. In this case, this temperature sensor cell, which is typically a piezoresistive resistor, should be placed in a separate tray. For example, it is conceivable the sensor ( 3 ) in a p-doped substrate and place the resistors in n-wells. The resistors would then be p-doped resistors. The leads of all resistors incl. The measuring resistors of the pressure cell would then run in the respective p-well as highly doped p + lines. Of course, when using an n-type substrate, it makes sense to use inverse line types (p-well, n-resistors, n + feeders). For the leads of the temperature sensor cell, it would be useful to run these leads as Kelvin wiring. This requires two lines at each resistor connection, one of which would be used to supply the electrical current to the respective contact and the other to measure the potential. Thus, a total of four such highly doped semiconductor lines for connecting a temperature sensor cell are required. This design has the advantage that leakage currents of the p + feed lines into the n-well do not falsify the measurement result. It is particularly advantageous if a temperature measuring resistor matches the resistances of a piezoresistive measuring bridge of the pressure sensor cell and how this is monolithically integrated.

It should also be mentioned that a co-integration of the sensor cell, for example the pressure cell, and the evaluation circuit on a crystal is possible.

Suitable pressure measuring cells are, for example, MOS tunnel diodes, piezoresistive systems, for example with Wheatstone bridges and capacitive systems.

Also, both bulk micromachining and surface micromechanics technologies are applicable.

Essentially, however, the construction boils down to the fact that the evaluation circuit ( 21 ) is made very narrow, that is, in a length to width ratio of preferably more than 2: 1 or more than 5: 1 or more than 10: 1. The bond connections are expediently only on the connector side and on the opposite, the medium to be measured facing side.

The same applies to the micromechanical pressure sensor ( 3 ) also this is preferably carried out very narrow. The micromechanical pressure sensor ( 3 ) so far from the first seal ( 11 ) stand out, as he is fat. The micromechanical pressure sensor ( 3 ) should be as wide as it is thick. If this is complied with, typically only one cube protrudes from the first seal ( 11 ) (first area A, 5 ). This cube already has special mechanical stability.

For reasons of mechanical decoupling, it may be useful to leave this optimal cube shape and the micromechanical pressure sensor ( 3 ) further from the seal ( 11 ) when it is wide and / or thick.

The length of the area (second area B, 5 ), in which the micromechanical pressure sensor ( 3 ) Contact with the first seal ( 11 ) depends, among other things, on the properties of the first seal ( 11 ) and the other system components, the requirements and the necessary contact surface for secure sealing.

If necessary, the micromechanical pressure sensor ( 3 ) in the second region (B), the contact surface between micromechanical pressure sensor ( 3 ) and first seal ( 11 ), with notches ( 67 . 68 . 6 ) to interlock between micromechanical pressure sensor ( 3 ) and first seal ( 11 ) to force. These indentations can be produced by photolithographic etching of the top and bottom, for example by KOH and / or DRIE etching. Of course you must not interrupt the lines. In this respect, the indentations ( 67 ) on the connection side of the micromechanical pressure sensor ( 3 ) to certain areas of the micromechanical pressure sensor ( 3 ) and an area for wiring ( 69 ). The side surfaces can be notched if this z. B. are separated with a laser from the wafer and the separating cut provides these notches. However, a much easier option is in the 7 and 8th shown. The micromechanical pressure sensor ( 3 ) has two longitudinal edges ( 63 ), which are not parallel to the symmetry axis ( 64 ) of the micromechanical pressure sensor ( 3 ) are. Here is a wedge shape used. The pressure on the media side causes the pressure sensor ( 3 ) in the seal ( 11 ) pressed. The compound seal ( 11 ) - micromechanical pressure sensor ( 3 ) is additionally sealed. 8th shows an exemplary wafer dressing of such micromechanical pressure sensors ( 3 ). These are covered by saw trenches ( 65 . 66 ) separated from each other. With the chosen arrangement, a fast cutting of the structures by means of laser is possible.

Finally, the micromechanical pressure sensor ( 3 ) far enough from the material of the first seal ( 11 ) (third region C, 5 ) to release the bonds with certainty.

The dimensions of the sensor are thus preferably at least 2: 1: 1, better 5: 1: 1 or 10: 1: 1 (length L to width w to thickness d, 1 and 2 ) In some cases, however, the sensor must be thinned out for better separation by means of a laser before separating the wafer composite. This is a degradation from the optimal approach described above. Among other things, for this reason, of course, other thickness ratios are conceivable. Therefore, the dimensions of the sensor surface are at least 2: 1, better at 5: 1 or 10: 1, (length L to width w, 2 ) wherein the thickness d may differ. The dimensions include the thinnest width w and the largest length L.

The micromechanical pressure sensor ( 3 ) and the evaluation circuit ( 21 ) are in a row with the long side parallel to the thread axis ( 37 ) assembled.

9 show the 1 with a press fit ( 70 ) instead of with a thread. Instead of a press fit, a sliding fit ( 70 ) are used, which is then glued into the mounting hole.

10 shows the sensor system 9 schematically after installation in the wall ( 72 ) of a pipe, a boiler or other device for measuring the medium ( 73 ). The sensor system seals the opening to the extent that within the scope of the respective operating conditions and the respective specification no medium ( 73 ) or only an undetectable amount of the medium ( 73 ) or only an amount below a predetermined or predeterminable limit amount per unit of time or in total can escape or exit.

Finally, it should be noted that a stepped seal receptacle ( 62 ), as in 6 drawn, makes sense to simplify the assembly.

An exemplary manufacturing method is based on the 11 to 21 explained.

The manufacturing process starts with a partially metallised carrier ( 18 ), which is in 11 is shown. The carrier ( 18 ) already comprises the first line section provided as a plug component ( 38 ), the second line section provided as a plug component ( 39 ), the third line section provided as a plug component ( 40 ), the fourth line section provided as a plug component ( 41 ). These are located in one area ( 35 ) of the carrier, which can later be used as a plug. In this area, the line sections should be provided with a coating (plating), which optimize the properties of the connector. Gold is suitable for this purpose, for example. In addition, located on the carrier ( 18 ) already the mounting surface ( 19 ) for the evaluation circuit and the mounting surface ( 17 ) for the sensor. It is advantageous if the carrier ( 18 ) an axis of symmetry ( 37 ) having. This should later be aligned with the axis of the machine element.

12 shows the wearer after Um-Molden (encapsulation with a thermoset or thermoplastic) with the further seal ( 34 ). The seal is already shaped so that it fits into the later housing. It is of course also possible to produce the final outer shape, for example by a cutting process after encapsulation. Possibly. the carrier ( 18 ) in the area of the further seal ( 34 ) are provided with an adhesion layer to provide a firm connection between another seal ( 34 ) and supports ( 18 ).

After attaching the further seal ( 34 ) glue ( 20 . 16 ) each on the mounting surfaces for the evaluation circuit ( 19 ) and for the sensor ( 17 ) ( 13 ).

Then, for example, on the adhesive ( 20 ) on the corresponding mounting surface of the evaluation circuit ( 19 ) the evaluation circuit ( 21 ) and glued on it. ( 14 )

Next, for example, on the adhesive ( 16 ) on the corresponding mounting surface of the sensor ( 17 ) the sensor ( 21 ) and glued on it. ( 15 ) The sensor in this example has a bevelled longitudinal edge ( 63 ), a sensor cell with piezoresistive resistors ( 50 . 51 . 52 . 53 . 54 ) and a membrane and a longitudinal axis ( 64 ), preferably with the symmetry axis of the carrier ( 37 ) is brought into overlap.

In this example, then, the bonding of the first to fourth bond wires ( 42 . 43 . 44 45 ) for the electrical connection of the evaluation circuit ( 21 ) with the first to fourth, provided as a plug component line region of a first to fourth line ( 38 . 39 . 40 . 41 ). This is in 16 shown.

The electrical connection between the micromechanical pressure sensor ( 3 ) and evaluation circuit ( 21 ) again by means of bonding. The bonding in this example comprises a fifth to eighth bond wire ( 46 . 47 . 48 . 49 ). 17 shows these more bonds.

In 18 the carrier prepared in this way ( 18 ) now with the sensor housing ( 100 ) combined to the sensor system. The exemplary sensor housing has screw head ( 32 ), the second groove ( 33 ) for sealing the further seal ( 34 ), the groove for later receiving a sealing ring ( 31 ), a cavity ( 2 ) and a thread ( 1 ) on. It may be advantageous to use the connection between groove ( 33 ) and further seal ( 34 ) by gluing. In this example, the second groove ( 33 ) carried out so that the carrier from the left into the sensor housing ( 100 ) can be pushed.

In 19 this construction will be off 18 with a gel ( 12 ) filled. This filling can be done, for example, by means of a cannula or several cannulas which are placed between the carrier ( 18 ) and sensor housing ( 100 ) fit.

It is advantageous if in this case the gravitational field of the earth is utilized so that the screw head points downwards. The filling takes place only so far that the third area (C) of the sensor is covered with the gel. This protects the bond system.

In 20 we the sealing ring ( 30 ) added. Of course, this can alternatively only after the introduction of the first seal ( 11 ) respectively.

In 21 is the sensor system with a first seal ( 11 ) locked. This is preferably done by potting with a mass that must not mix with the gel and does not sink into it. Through a stepped seal holder ( 62 ) in the sensor housing ( 100 ) the sensor system is sealed.

The 22 and 23 do not show to scale an exemplary pressure sensor according to the invention. 22 shows the not to scale cross section during 23 the not to scale supervision shows. In contrast to 6b are the first area A, the second area (B) and the third area (C) now not consecutively, so quasi sequential, as in 6b Rather, the second area (B) completely encloses the first area (C). Since this second area (B) is used for sealing and the first area (A) is supposed to have direct contact with the aggressive medium, this is also necessary. The third area (C) in this example also completely includes the first area (A) and the second area (B). However, this is not absolutely necessary. In this example, however, the sensor still has a fourth region (D), which is arranged between the first region (A) and the second region (B) and, on the one hand, completely covers the first region (A) and, on the other hand, of the second Area (B) is also completely included. This fourth area (D) is optional. Its function is easiest with the help of 24 explain. The 24 shows a cross section through an exemplary housing ( 80 ). The cross-section of the sensor ( 3 ) out 22 is without further reference numerals on a mounting surface ( 17 ) applied. Bonding wires ( 79 ) connect the sensor ( 3 ) with a connection ( 76 ) electrically. This ensemble, which is shown here in simplified form, is filled with molding material ( 77 ) overmoulded. This leaves an access opening ( 78 ) free for the medium to be measured. Because molding compound typically consists of thermosets with fillers, it has other mechanical properties than the material of the sensor, typically silicon. A particularly critical feature is the swelling of the molding compound by moisture. This means that the molding compound sometimes times more and less forces on the sensor ( 3 ) exercises. Therefore, it makes sense to use the Moldmassengrenze a minimum distance to the actual sensor cell ( 8th ), here a pressure sensor cell, to maintain. At the same time, this distance can be used to set up a tool that touches the sensor in the fourth area (D) and here the space between this tool and the surface of the sensor ( 3 ) so that no molding compound can reach the first area (A). Preferably, the tool should in this case be shaped such that, in the area of the sensor cell, the sensor surface of the sensor ( 3 ) not touched.

It has been shown that it is advantageous if the width of the fourth region is in each case at least 100 μm, better 150 μm, even better 200 μm. Otherwise, it is advantageous if the fourth region (D) is designed like the second region (B) and in particular has no metal lines.

MLPQ

(Micro Leadframe Package Quad)

MLPM

(Micro Leadframe Package Micro)

MLPD

(Micro Leadframe Package Dual)

DRMLF

(Dual Row Micro Leadframe Package)

DFN

(Dual Flat No-lead Package)

TDFN

(Thin Dual Flat No-lead Package)

UTDFN

(Ultra Thin Dual Flat No-lead Package)

XDFN

(eXtreme thin Dual Flat No-lead Package)

QFN

(Quad Flat No-lead Package)

QFN-TEP

(Quad Flat No-lead package with Top Exposed Pad)

TQFN

(Thin Quad Flat No-lead Package)

VQFN

(Very Thin Quad Flat No Leads Package)

DHVQFN

(Dual in-line compatible thermal enhanced very thin quad flat package with no leads)

The in the 23 still marked high p doped lines ( 81 ) connect the pads ( 14 ) on the one hand with the resistors of the Wheatstone bridge, so the sensor cell ( 8th ), which also includes the membrane. The sensor cell ( 8th ) lies completely in the first area (A). The sensor cell is included completely made of silicon and SiO ₂ as well as the used passivation. In addition, the exemplary micromechanical sensor ( 3 ) via a thermally sensitive component ( 75 ) for the temperature measurement. It is typically a resistor or a diode, and a resistor that is compatible to make the piezoresistors of the Wheatstone bridge is simpler and therefore preferred to manufacture. The resistor is over four p + -doped, so highly p-doped areas with four bond pads ( 14 ) are electrically connected in Kelvin wiring. This has the advantage that the voltage drop is independent of parasitic effects directly on the thermally sensitive device ( 75 ) can be measured. The execution of a resistance preferably corresponds exactly to the design used for the Wheatstone bridges. In the third area (C), the lines are preferably used as metal lines ( 74 ). An attempt is typically made to use the high-impedance, high-p-doped lines ( 81 ) with respect to the respective connections as symmetrical as possible. This method is particularly suitable for use in enclosures of the QFN (Quad Flat No Leads Package) standard. These housings are also known under the following names, among others:

MLPQ

(Micro Leadframe Package Quad)

MLPM

(Micro Leadframe Package Micro)

MLPD

(Micro Leadframe Package Dual)

DRMLF

(Dual Row Micro Leadframe Package)

DFN

(Dual Flat No-Lead Package)

TDFN

(Thin Dual Flat No-lead Package)

UTDFN

(Ultra Thin Dual Flat No-Lead Package)

XDFN

(eXtreme thin Dual Flat No-Lead Package)

QFN

(Quad Flat No-lead Package)

QFN TEP

Quad Flat No-lead Package with Top Exposed Pad

TQFN

(Thin Quad Flat No-Lead Package)

VQFN

(Very Thin Quad Flat No Leads Package)

DHVQFN

(Dual in-line compatible thermal enhanced very thin quad flat package with no leads)

With QFN housings within the meaning of this disclosure, therefore, of course, all the aforementioned variants are included.

It makes sense, if the housing ( 80 ) an area of first mold mass covering ( 83 ) of the sensor ( 3 ) which at least partially overlaps a third region (C) of the sensor and it has a region of reduced second mold mass coverage ( 82 ) of the sensor ( 3 ) which at least partially overlaps a second region (B) of the sensor. In this case, the thickness of the second molding compound covering is at least 5% and / or 10% and / or 25% and / or 50% and / or 75% or 90% compared to the thickness of the first molding compound covering ( 83 ) decreased. It is therefore an area of reduced thickness of the molding compound over the second area (B). This has the purpose of mechanical stress entry into the stress-sensitive areas (first area (A)) of the sensor ( 3 ) in this area, in particular when moisture is introduced into the molding compound.

In the area of the first Moldmassenbedeckung ( 83 ), which is further removed from the stress sensitive parts due to the construction, the thickness is also typically chosen to be minimal. However, here is typically the connection of the media-carrying container, z. As the sticking of a tube possible.

On the other hand, the bonding system requires adequate corrosion protection. Therefore, it makes sense that here the height of the bonding wires is crucial for the housing thickness. The housing ( 80 ) can therefore a range of enlarged third Moldmassenbedeckung ( 84 ) of the sensor ( 3 ) which at least partially overlaps a third region (C) of the sensor and in which the thickness of the third molding composition is at least 5% and / or 10% and / or 25% and / or 50% and / or 75% or 90 % compared to the thickness of the first molding compound covering ( 83 ) is enlarged.

Part of the bond system ( 79 ) is typically not located above the sensor ( 3 ). The housing should also be used in a standard handling system for the production test of microelectronic circuits without sensor function and access opening ( 78 ) can be tested. It therefore makes sense if, in addition to the already mentioned mold mass ranges, an area of increased housing thickness ( 85 ) of the sensor ( 3 ) having the bonding system ( 79 ) and in which the thickness of the enlarged housing thickness by at least 5% and / or 10% and / or 25% and / or 50% and / or 75% or 90% compared to the thickness of the housing in the region of the first Moldmassenbedeckung 83 ) is enlarged.

LIST OF REFERENCE NUMBERS

1

Thread or machine element for connection to an opening

2

cavity

3

Micromechanical sensor, typically made of silicon or other semiconductor material, here for example a pressure sensor

4

Poly-silicon layer or SiN layer for protection against chemicals

5

Oxide (typically silicon dioxide)

6

first lead on the sensor, typically of highly doped semiconductor material. For example, it may be p + doped silicon in an n-well.

7

micromechanical sensor membrane, typically made of silicon or the respective semiconductor material used

8th

Micromechanical sensor cell, in particular pressure sensor cell (as a whole)

9

second lead on the sensor, typically of highly doped semiconductor material. For example, it may be p + doped silicon in an n-well.

10

first groove of the sensor housing

11

first seal

12

gel

13

Contacts of the micromechanical sensor ( 3 )

14

Bonding of the bonding wire ( 15 ) on the contact ( 13 ) of the micromechanical sensor ( 3 )

15

bonding wire

16

Adhesive for fixing the micromechanical sensor ( 3 ) on the mounting surface ( 17 )

17

Mounting surface for the micromechanical sensor ( 3 )

18

Support for the evaluation circuit ( 21 ) and the micromechanical sensor ( 3 ) as well as the wiring ( 36 ) which may also be another carrier, in particular a printed circuit or a wafer piece or a ceramic carrier or a glass plate or a leadframe or a metal plate with insulation or a crystalline, polycrystalline or amorphous carrier or an organic or inorganic carrier or a Composite carrier, wherein electrical wiring is on the carrier or other carrier.

19

Mounting surface for the evaluation circuit ( 21 )

20

Glue for the mechanical connection of the evaluation circuit ( 21 ) with the mounting surface ( 19 )

21

Evaluation circuit, typically monolithically integrated

22

Bond ball for connecting the evaluation circuit ( 21 ) with the micromechanical sensor ( 3 ) by means of a bonding wire ( 15 ) via the bond pad ( 23 )

23

Bond pad (connection surface) of the evaluation circuit ( 21 ) for connecting the evaluation circuit ( 21 ) with the micromechanical sensor ( 3 ) by means of a bonding wire ( 15 )

24

simplified (symbolic) drawn evaluation circuit within the evaluation circuit ( 21 )

25

Simplified (symbolic) passivation within the evaluation circuit ( 21 )

26

further bond pad (connection area) of the evaluation circuit ( 21 ) for connecting the evaluation circuit ( 21 ) with a connector area ( 36 ) by means of a bonding wire ( 28 )) and a conductor track ( 36 )

27

Bond ball for connecting the evaluation circuit ( 21 ) with a connector area ( 36 ) by means of a bonding wire ( 28 ) and a conductor track ( 36 )

28

another bond wire for connecting the evaluation circuit ( 21 ) with a connector area ( 36 ) via a conductor track ( 36 )

29

Wedge-Bond for connecting the evaluation circuit ( 21 ) with a connector area ( 36 ) via a conductor track ( 36 )

30

Seal or sealing ring

31

Groove for receiving the sealing ring or the seal ( 30 )

32

screw head

33

second groove for sealing the second seal ( 34 )

34

another seal

35

Area of the carrier ( 18 ) intended for use as a plug component.

36

Range of wiring ( 19 ) intended for use as a plug component.

37

Thread axis or axis of a machine element for connection to an opening

38

first, provided as a plug component line region of a first line

39

second, provided as a plug component line region of a second line

40

third, provided as a plug component line region of a third line

41

fourth, provided as a plug component line portion of a fourth line

42

first bond wire for connection of the evaluation circuit ( 21 ) with a fourth line ( 41 )

43

second bond wire for connection of the evaluation circuit ( 21 ) with a third line ( 40 )

44

third bond wire for connection of the evaluation circuit ( 21 ) with a second line ( 39 )

45

fourth bond wire for connection of the evaluation circuit ( 21 ) with a first line ( 38 )

46

fifth bond wire for connection of the micromechanical pressure sensor ( 3 ) or pressure sensor with the evaluation circuit ( 21 )

47

sixth bond wire for connection of the micromechanical pressure sensor ( 3 ) or pressure sensor with the evaluation circuit ( 21 )

48

seventh bonding wire for connection of the micromechanical pressure sensor ( 3 ) or pressure sensor with the evaluation circuit ( 21 )

49

Eighth bond wire for connection of the micromechanical pressure sensor ( 3 ) or pressure sensor with the evaluation circuit ( 21 )

50

first piezo-resistive resistor of a Wheatstone bridge

51

second piezo-resistive resistor of a Wheatstone bridge

52

third piezo-resistive resistor of a Wheatstone bridge

53

Fourth piezo-resistive resistor of a Wheatstone bridge

54

Poly-silicon shield of the first piezo-resistive resistor of a Wheatstone bridge

55

Poly-silicon shield of the fourth piezo-resistive resistor of a Wheatstone bridge

56

Oxide that covers the pressure cell. Typically, it is a very thin oxide thinner than 200 nm.

57

third lead or third lead portion on the sensor, typically of highly doped semiconductor material. For example, it may be p + doped silicon in an n-well.

58

fourth lead or fourth lead portion on the sensor, typically of highly doped semiconductor material. For example, it may be p + doped silicon in an n-well.

59

fifth lead or fifth lead portion on the sensor, typically of highly doped semiconductor material. For example, it may be p + doped silicon in an n-well.

60

buried oxide of a buried cavity wafer, also called CSOI wafer

61

Device wafer of a buried cavity wafer, also called CSOI wafer

62

stepped seal holder for better installation

63

Longitudinal edge of the micromechanical sensor ( 3 )

64

Longitudinal axis, in particular symmetry axis of the micromechanical sensor ( 3 ) or pressure sensor

65

linear saw trench transversely to the sensor axis on the wafer

66

Non-linear saw trench longitudinally on the wafer

67

Indentations on the connection side of the sensor to improve the mechanical connection between the micromechanical sensor ( 3 ) and the seal ( 11 ). The indentations are located in the second region (B) of the micromechanical sensor (FIG. 3 )

68

Indentations on the underside of the sensor to improve the mechanical connection between the micromechanical sensor ( 3 ) and the seal ( 11 ). The indentations are located in the second region (B) of the micromechanical sensor (FIG. 3 )

69

Area on the wiring side of the micromechanical sensor ( 3 ) in the second region B of the micromechanical sensor ( 3 ), which does not have a notch ( 67 ) to allow electrical connection.

70

Press fit or sliding fit depending on the application and mounting method

71

buried cavity

72

Wall of a container or pipe or other machine element that allows the escape of a medium ( 73 ) from one predefined room area to another.

73

Medium that should be measured.

74

metal lead

75

thermally sensitive component for temperature measurement. It is typically a resistor or a diode, and a resistor that is compatible to make the piezoresistors of the Wheatstone bridge is simpler and therefore preferred to manufacture. The resistor is over four p + -doped, so highly p-doped areas with four bond pads ( 14 ) electrically connected. The execution of a resistance preferably corresponds exactly to the design used for the Wheatstone bridges.

76

Connection of the housing ( 80 ). These connections are typically painted after soldering onto the leads of a PCB, whereby during the painting process the access opening (FIG. 78 ) is not painted. It is obvious that she Seal the connection must be made so that the sides of the housing ( 80 ) and possibly also its back can not be reached by the medium to be measured.

77

Molding compound of the housing ( 80 )

78

Access opening for the medium to the micromechanical functional element, here a pressure sensor membrane.

79

Bond wires

80

exemplary housing

81

high p-doped supply lines. These leads are for better clarity in the 23 provided only once with a reference numeral. However, the hatching is always the same. The sensor in 23 has eight such lines.

82

Area of second Moldmassen Cover. It is an area of reduced thickness of the molding compound over the second area (B). This has the purpose of mechanical stress entry into the stress-sensitive areas (first area (A)) of the sensor ( 3 ) in this area.

83

Area of first Moldmassen Cover. It is a region of normal thickness of the molding compound over the third region (C). This has the purpose of mechanical stress entry into the stress-sensitive areas (first area (A)) of the sensor ( 3 ) in this area.

84

Area of third Moldmassenbedeckung. It is an area of increased thickness of the molding compound over the third area (C). This has the purpose of bonding wires ( 79 ) to protect against corrosion.

85

Range of increased case thickness over the bond system ( 79 ) of the sensor ( 3 ). The purpose of this is to enable the mechanical guidance in standard QFN handling systems for the production test. The thickness is typically oriented to the thickness for pure electronic circuits without sensor function and without access opening (FIG. 78 ). The thickness is also at least so high that the protection of the bonding wires is secured in this area.

100

sensor housing

A

first sensor area of the sensor measuring cell. Here the actual measurement data are recorded. This first region typically has no materials that can be corroded by the medium. The surfaces are electrically insulating and chemically inert to the medium or biologically inactive and neutral in the case of medical sensors in contact with body fluids. Furthermore, typically only materials are used which have similar thermal expansion coefficients as the base material of the sensor.

B

second sensor area for sealing. Here, the seal between the medium and the interior of the sensor housing happens. Since partial penetration of the medium can not be precluded, this second region, like the first region (A), typically does not contain any material that can be corroded by the medium. The surfaces are also electrically insulating and chemically inert to the medium or, in the case of medical sensors in contact with body fluids, biologically inactive and neutral. Furthermore, here also typically only materials are used which have similar coefficients of thermal expansion as the base material of the sensor. In addition, however, this second area must have a good adhesion with the seal ( 11 ) exhibit.

C

third sensor area for electrical connection. Even a partial penetration of the medium should be excluded here. This third region may therefore comprise the materials, such as the metal of the bond pads, which may be corroded by the medium. The surfaces are electrically insulating except for the bonding connection areas. The areas for electrical connection are of course excluded. A restriction with regard to the coefficients of thermal expansion no longer applies here.

w

Width of the micromechanical sensor ( 3 )

L

Length of the micromechanical sensor ( 3 )

d

Thickness of the micromechanical sensor ( 3 )

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

• US 8049290 B2 [0002, 0002, 0002, 0002, 0002, 0002, 0002, 0002, 0002, 0002, 0002, 0002, 0002, 0002, 0008, 0012, 0081]
• US 20030167851 A1 [0002, 0002, 0002, 0002, 0002, 0002, 0002]
• DE 3021088 A1 [0002, 0002]
• DE 10360941 A1 [0003, 0003, 0003, 0003, 0003, 0003]
• DE 102004002089 A1 [0004, 0004, 0004, 0004, 0004, 0004]
• DE 2008046515 A1 [0005]
• DE 102009048702 A1 [0005]
• WO 2011083161 A2 [0009, 0009, 0013, 0054, 0054, 0054, 0077, 0081, 0081]
• WO 2011083161 A [0014, 0014, 0054]
• DE 102013007619 A [0015]
• DE 102013016638 [0015]
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• DE 102013016637 [0015]

Claims (16)

micromechanical sensor ( 3 ) made of silicon, with the evaluation circuit ( 21 ) can form a unit, and - with at least one sensor cell ( 8th ) and - and at least one functional element ( 7 ) that is intended or can be used to be in direct contact with a medium, characterized in that - the micromechanical sensor ( 3 ) on the processed surface at least a first region (A), which is characterized in that it • at least one sensor cell ( 8th ) and • the first region (A) at least one sensor measuring cell ( 8th ) and • the first region (A) is or can be used for direct contact with a medium, and • the first region (A) - has no metallization and / or - electrical connections in doped one in this first region (A) Semiconductor material and / or polycrystalline semiconductor material are executed and - that the micromechanical sensor ( 3 ) has on its processed surface at least a second region (B), characterized in that it is the function of the second region (B), together with a first seal ( 11 ) or molding compound ( 77 ) to seal the passage of the medium in a third region (C) of the micromechanical sensor and thus to prevent. It has no metallization in this second region (B) and / or in this second region (B) electrical connections are made in doped semiconductor material or polycrystalline semiconductor material. The micromechanical sensor ( 3 ) has a third region (C) on its processed surface, which is characterized in that • the third region (C) has at least one metallic electrical contact of the micromechanical sensor ( 3 ), and • the second region (B) is always on the processed surface between the third region (C) and the first region (A), and • the third region (C) of the first region (A) on the processed surface is not touched. micromechanical sensor ( 3 ) according to one or more of the preceding claims, characterized in that - it is a pressure sensor or - at least one sensor cell ( 8th ), which is a pressure sensor cell. Micromechanical sensor ( 3 ) according to claim 2, characterized in that - it additionally comprises a temperature sensor in or - has a temperature sensor cell. Micromechanical sensor ( 3 ) according to claim 3, characterized in that - at least one said temperature sensor cell is a monolithically integrated into the substrate of the sensor resistor. Micromechanical sensor ( 3 ) according to claim 3, characterized in that - at least one said temperature sensor cell is a monolithically integrated into the substrate of the sensor pn diode. Micromechanical sensor ( 3 ) according to one or more of claims 3 to 5, characterized in that - at least one said temperature sensor and / or at least one said temperature sensor cell is connected via lines which consist of highly doped semiconductor material and / or polycrystalline silicon. Micromechanical sensor ( 3 ) according to one or more of claims 3 to 6, characterized in that - at least one said temperature sensor is connected via a Kelvin wiring. Micromechanical sensor ( 3 ) according to one or more of the preceding claims, characterized in that - the aspect ratio L / w of the micromechanical sensor ( 3 ) is greater than 2: 1. Micromechanical sensor ( 3 ) according to one or more of the preceding claims, characterized in that - the sensor system comprises a sensor cell ( 8th ) with a buried cavity ( 71 ) having. Micromechanical sensor ( 3 ) According to one of the preceding claims, characterized in that - the sensor cell ( 8th ) at least partially with a poly-silicon layer ( 4 ) or SiN layer ( 4 ), which serves as protection of the sensor cell ( 8th ) against aggressive media and ion diffusion. Micromechanical sensor ( 3 ) according to one of the preceding claims, characterized in that - the micromechanical sensor ( 3 ) has a fourth region (D) characterized in that It is the function of the fourth area (D) during the manufacture of a housing ( 78 ) together with a tool or tool part to seal the passage of the molding compound into the first region (A) of the micromechanical sensor and thus to prevent and / or - the function of the fourth region (D) is micromechanical functional elements, in particular a pressure sensor membrane, in the first region (A) of the micromechanical sensor ( 3 ), mechanically from the molding compound ( 77 ) of a housing ( 78 ) and • the micromechanical sensor ( 3 ) - in this fourth region (D) has no metallization and / or - in this fourth region (D) electrical connections in doped semiconductor material or polycrystalline semiconductor material are executed and • the fourth region (D) always on the processed surface between the second Area (B) and the first area (A) is located. Micromechanical sensor ( 3 ) according to one of the preceding claims, characterized in that - the micromechanical sensor ( 3 ) has a second region (B), which is additionally characterized in that • at least one longitudinal edge ( 63 ) of the micromechanical sensor ( 3 ) not parallel to a longitudinal axis ( 64 ) of the micromechanical sensor ( 3 ) or • the micromechanical sensor ( 3 ) Notches ( 68 ) on the underside of the micromechanical sensor ( 3 ) or notches ( 67 ) on the connection side of the micromechanical sensor ( 3 ), which improves the mechanical connection between the micromechanical sensor ( 3 ) and the first seal ( 11 ) can serve or serve. Housing for a micromechanical sensor ( 3 ) according to one of the preceding claims, characterized in that it has an access opening ( 78 ), the access of a medium to the surface of the sensor ( 3 ) • allows in said first area (A) and • allows in said optional fourth area (D) and • does not allow in said second area (B) and • does not allow in said third area (C). Housing for a micromechanical sensor ( 3 ) according to claim 13, characterized in that • there is a region of first mold mass covering ( 83 ) of the sensor ( 3 ) which at least partially intersects a third region (C) of the sensor and • there is a region of reduced second mold mass coverage ( 82 ) of the sensor ( 3 ) which at least partially overlaps a second region (B) of the sensor, and • the thickness of the second molding composition is at least 5% and / or 10% and / or 25% and / or 50% and / or 75% or 90% relative to the thickness of the first molding compound covering ( 83 ) is reduced. Housing for a micromechanical sensor ( 3 ) according to claim 13 and / or 14, characterized in that • an area of first mold mass covering ( 83 ) of the sensor ( 3 ) which at least partially overlaps a third region (C) of the sensor and there is a region of increased third molding compound coverage ( 84 ) of the sensor ( 3 ) which at least partially overlaps a third region (C) of the sensor and • the thickness of the third molding composition is at least 5% and / or 10% and / or 25% and / or 50% and / or 75% or 90% relative to the thickness of the first molding compound covering ( 83 ) is enlarged. Housing for a micromechanical sensor ( 3 ) according to claim 13 to 15, characterized in that: • there is a region of first mold mass covering ( 83 ) of the sensor ( 3 ) that at least partially intersects a third region (C) of the sensor and that there is an area of increased package thickness ( 85 ) of the sensor ( 3 ) having the bonding system ( 79 ) and / or • the thickness of the enlarged housing thickness by at least 5% and / or 10% and / or 25% and / or 50% and / or 75% or 90% with respect to the thickness of the housing in the region of the first mold mass coverage ( 83 ) is enlarged.

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