DE102015203040A1 - Arrangement of an electric compass - Google Patents

Abstract

Arrangement (100) for an electric compass, comprising: - a first wafer (10) having a first electronic evaluation circuit and a second electronic evaluation circuit; A micromechanical detection device (20) for detecting acceleration; - Wherein the first wafer (10) and the micromechanical detection device (20) are arranged in layers; and - a Hall element (40) which is arranged on a defined surface of the micromechanical detection device (20), wherein a signal of the micromechanical detection device (20) can be evaluated by means of the first electronic evaluation circuit and wherein by means of the second electronic evaluation circuit a signal of the Hall element (40) is evaluable.

Description

The invention relates to an arrangement for an electric compass and a method for producing an arrangement for an electric compass.

State of the art

For the purpose of determining an orientation in space, for example, electric compasses are used in mobile phones. These typically include a triaxial MEMS (micro-electromechanical systems) accelerometer and a triaxial magnetic field sensor. A particularly small installation space can be realized in such an electric compass, for example, by integrating the MEMS elements of the two sensors together with their electronic evaluation circuits (ASICs) into a housing (English package).

It is also known that materials with high electron mobility and low charge carrier density can be used advantageously as magnetic field sensors via the Hall effect. Here, III-V semiconductors offer useful properties, allowing indium antimony (InSb) with a mobility of approximately 80,000 cm ² / V / s over silicon with a mobility of approximately 1,000 m ² / V / s, Hall sensors produce with significantly increased sensitivity.

Such sensors are known with InSb as a magnetic field-sensitive layer, but also with other III-V semiconductor combinations, such. Gallium arsenide (GaAs) or indium arsenide (InAs).

In addition, graphene in the magnetic field sensitive layer can provide even higher electron mobility of about 100,000 cm ² / V / sec.

Also known are MEMS acceleration sensors, in which a movable spring-mass system is enclosed in a vacuum. This is usually realized by a cap on a structured silicon chip or wafer.

Disclosure of the invention

It is an object of the invention to provide an improved arrangement for an electric compass.

• – einen ersten Wafer mit einer ersten elektronischen Auswerteschaltung und einer zweiten elektronischen Auswerteschaltung;
• – eine mikromechanische Erfassungseinrichtung zum Erfassen von Beschleunigung;
• – wobei der erste Wafer und die mikromechanische Erfassungseinrichtung geschichtet angeordnet sind; und
• – ein Hall-Element, das auf einer definierten Oberfläche der mikromechanischen Erfassungseinrichtung angeordnet ist, wobei mittels der ersten elektronischen Auswerteschaltung ein Signal der mikromechanischen Erfassungseinrichtung auswertbar ist und wobei mittels der zweiten elektronischen Auswerteschaltung ein Signal des Hall-Elements auswertbar ist.

According to a first aspect, the object is achieved with an arrangement for an electric compass, comprising:

• A first wafer with a first electronic evaluation circuit and a second electronic evaluation circuit;
• A micromechanical detection device for detecting acceleration;
• - Wherein the first wafer and the micromechanical detection device are arranged in layers; and
• A Hall element which is arranged on a defined surface of the micromechanical detection device, wherein a signal of the micromechanical detection device can be evaluated by means of the first electronic evaluation circuit and wherein a signal of the Hall element can be evaluated by means of the second electronic evaluation circuit.

• – Bereitstellen einer ersten elektronischen Auswerteschaltung auf einem ersten Wafer;
• – Bereitstellen einer zweiten elektronischen Auswerteschaltung auf dem ersten Wafer;
• – Bereitstellen einer mikromechanischen Erfassungsrichtung zum Erfassen von Beschleunigung; und
• – Abscheiden eines Hall-Elements auf eine definierte Oberfläche der mikromechanischen Erfassungseinrichtung, wobei der erste Wafer, die mikromechanische Erfassungseinrichtung und das Hall-Element geschichtet angeordnet werden.

According to a second aspect, the object is achieved with a method for producing an arrangement for an electric compass, comprising the steps:

• - Providing a first electronic evaluation circuit on a first wafer;
• - Providing a second electronic evaluation circuit on the first wafer;
• - Providing a micromechanical detection direction for detecting acceleration; and
• - depositing a Hall element on a defined surface of the micromechanical detection device, wherein the first wafer, the micromechanical detection device and the Hall element are arranged in layers.

In this way, the magnetic field-sensitive layer is deposited in a production of the arrangement on a substantially heat-insensitive surface of the micromechanical detection direction. As a result, the magnetic-field-sensitive layer for the Hall element can be deposited with a high temperature, which advantageously supports a high quality of the Hall element and thereby high sensitivity for the electric compass. Furthermore, a hybrid construction of an electric compass can be advantageously avoided in this way, because no additional separate chip is required. As a result, a flat structure of electronic devices (for example, smartphones) is supported by an electric compass.

Advantageous developments of the arrangement and the method are the subject of dependent claims.

An advantageous development of the arrangement is characterized in that the Hall element is arranged on an upper side or on an underside of a cap wafer of the micromechanical detection device. This supports a variable arrangement of the Hall element.

A further advantageous development of the arrangement is characterized in that the Hall element is arranged on an upper side or on a lower side of an acceleration MEMS element of the micromechanical detection device. Also in this way a great design freedom for the electric compass is advantageously supported.

A further advantageous development of the arrangement is characterized in that the Hall element has a III-V semiconductor layer. In this way, the magneto-sensitive layer is provided in a form in which it can advantageously be deposited at high temperatures and thus in high quality.

A further advantageous development of the arrangement is characterized in that the Hall element has graphene. As a result, an alternative magneto-sensitive layer is provided for the Hall element.

An advantageous development of the arrangement is characterized in that metal and bonding wires are provided for electrical contacting of the Hall element. In this way, an electrical contact for the Hall element with other elements of the electric compass is possible.

A further advantageous development of the arrangement is characterized in that metal and plated-through holes are provided for electrical contacting of the Hall element. In this way, an electrical contact can be provided within the electrical arrangement.

A further advantageous development of the arrangement is characterized in that it further comprises a second wafer, which is arranged layered with the first wafer and with the micromechanical detection device, wherein the second electronic evaluation circuit is arranged on the second wafer. In this way, an alternative structure of the arrangement is realized, which provides a separate design and arrangement of the two evaluation circuits on different wafers or chips.

The invention will be described below with further features and advantages with reference to three figures in detail. All features, regardless of their representation in the description and in the figures and regardless of their relationship in the claims form the subject of the invention. The figures are particularly intended to illustrate the principles essential to the invention and are not necessarily to scale.

In the figures shows:

1 a cross-sectional view through a basic structure of an arrangement for an electric compass;

2 a detailed view of 1 ; and

3 a basic sequence of an embodiment of the method according to the invention.

Description of embodiments

The present invention advantageously makes it possible to produce electrical compasses based on III-V semiconductor Hall sensors or graphene Hall sensors that can be integrated into smaller packaging units.

Electric compasses (not shown) known in the prior art may have a hybrid structure in which, for example, an InSb Hall sensor chip, an associated evaluation ASIC, an acceleration sensor MEMS element and an associated evaluation ASIC are stacked on top of one another. This results disadvantageously in a high housing, which does not meet requirements for modern smartphones (height of the housing for the evaluation ASIC and the acceleration sensor MEMS element ("first-level package") should be, for example, less than 0.85 mm ) or a use of heavily thinned chips, which, however, can disadvantageously lead to worse sensor characteristics in the acceleration sensor.

It is therefore proposed to arrange a Hall element on the chip of the acceleration sensor. This can be carried out, for example, on or under the cap wafer or on or under a wafer with micromechanically movable structures.

1 shows a cross-sectional view through a basic structure of a layered arrangement 100 for an electric compass (not shown). A first electronic evaluation circuit or an acceleration ASIC is provided on a first wafer 10 , Below the first wafer 10 is a micromechanical detection device 20 arranged a cap wafer 21 and an acceleration MEMS wafer 22 comprising micromechanically movable structures. The two wafers 21 . 22 For example, they are firmly connected by bonding. Below the micromechanical detection direction 20 is a second electronic evaluation circuit in the form of a magnetic field ASIC on a second wafer 30 provided, preferably for the evaluation of electrical signals of a magnetic field-sensitive layer (not shown in FIG 1 ).

2 shows a preferred embodiment of an inventive arrangement 100 for an electric compass. You can see that on the cap wafer 21 a magnetic field-sensitive Hall element 40 is arranged. The Hall element 40 may for example be formed from a III-V semiconductor layer or alternatively graphene. Due to the aforementioned heat insensitivity of the cap wafer 21 remains the cap wafer 21 largely undisturbed. The first electronic evaluation circuit (not shown) on the first wafer 10 is for an evaluation of electrical signals of the micromechanical detection device 20 intended. The second electronic evaluation circuit (not shown) on the first wafer 10 is for an evaluation of electrical signals of the Hall element 40 intended.

In an embodiment of the arrangement not shown in FIGS 100 is under the cap wafer 21 a second wafer 30 arranged, due to the deposition of the Hall element on the cap wafer 21 also the second wafer 30 remains largely undisturbed.

The first electronic evaluation circuit and the second electronic evaluation circuit can thus advantageously either together on the first wafer 10 or separated from each other on the first wafer 10 and the second wafer 30 be formed or arranged. Here is a layer arrangement of the first wafer 10 , the micromechanical detection device 20 and the second wafer 30 any.

Advantageous is the said Hall layer or the Hall element 40 on each surface of the micromechanical detection device 20 Deposable, that is on a top or bottom of the cap wafer 21 or on top or bottom of the acceleration MEMS element 22 , In this way, a high design freedom for the arrangement 100 supported.

Because the wafers 21 . 22 the acceleration sensor are not as sensitive to temperature as the electronic evaluation circuits of the wafer 10 . 30 For example, it is possible to deposit III-V semiconductors or graphene on them at higher temperatures. Higher temperatures advantageously mean a high-quality crystal growth, so that a high electron mobility and thus a high sensor sensitivity can be achieved.

By means of a metal 50 and vias 23 (through silicon via, TSV) can be an electrical contacting of the Hall element 40 with the second electronic evaluation circuit (not shown in FIG 2 ) to be provided. Furthermore, by means of a bonding wire 60 Bond pads or a direct electrical contacting of the Hall element 40 to other elements of the electric compass. Insulation layers between the cap wafer 21 , the III-V semiconductor layer and the metal 50 as well as a cover layer are in 2 not shown for reasons of clarity.

Since, as a result, only two or three chips (MEMS acceleration / Hall sensor and one or two ASICs) are required for an electric compass, the housing or package can be made very small in this way.

The method of manufacturing the assembly 100 is performed as explained below:
First, a deposition of the Hall element occurs 40 or the Hall layer on the cap wafer 21 , then a structuring of the Hall element 40 and making the connections (insulation and metal layers and their structuring).

Thereafter, a formation of the vias occurs 23 in the cap wafer 21 , Alternatively, bonding wires can also be used 60 on the cap wafer 21 be provided. This is followed by structuring of the cap wafer 21 , Finally, the acceleration sensor MEMS wafer is manufactured 20 and a bonding of both wafers 10 . 20 , Finally, packaging of this construction is done with at least one of the wafers 10 . 30 ,

As possible alternatives of the manufacturing process, it is also conceivable, the Hall element 40 on the bottom of the cap wafer 21 deposit. Furthermore, the Hall element 40 also on the top of the acceleration sensor MEMS wafer 22 be deposited in addition to the micromechanically movable structures. Furthermore, the Hall element 40 also on the bottom of the accelerometer MEMS wafer 22 deposited and connecting the Hall element 40 over the vias 23 to the bonding wires 60 be performed. Furthermore, it is also conceivable that the Hall element 40 on the underside of the accelerometer MEMS wafer 22 is arranged and then a flip-chip contact to the second electronic evaluation circuit of the second wafer 30 is carried out.

If the hall element 40 on the accelerometer MEMS wafer 22 can be arranged, the cap wafer 21 also consist of an ASIC. If this ASIC combines the magnetic field and acceleration evaluation, a single-chip structure would also be feasible.

The following materials are for the Hall layer or for the Hall element 40 conceivable: Ternary III-V compound semiconductors, such as InGaAs, InAsSb, GaInSb or GaInP. Further, II-VI compound semiconductors such as CdTe, ZnS, and graphene are also possible.

As a deposition method for the Hall layer or for the Hall element 40 are eligible: electrochemical ADL (atomic layer deposition), MBE (molecular beam epitaxy), sputtering. For example, MBE, PECVD (plasma enhanced chemical vapor deposition) and CVD are suitable for graphene.

3 shows in principle a sequence of an embodiment of the method according to the invention.

In one step 300 becomes a first electronic evaluation circuit on a first wafer 10 provided.

In one step 310 becomes a second electronic evaluation circuit on the first wafer 10 provided.

In one step 320 provision is made of a micromechanical detection device for detecting acceleration.

In one step 330 becomes a reverb element 40 on a defined, any surface of the micromechanical detection device 20 deposited, the first wafer 10 , the micromechanical detection direction 20 and the Hall element 40 be arranged layered.

In summary, the present invention proposes an arrangement for an electric compass and a method for producing such an arrangement. By arranging the Hall layer on a defined surface of the electromechanical detection device is supported that the temperature-sensitive electronic evaluation circuits remain largely unaffected and a simple and flat structure of the entire arrangement is supported.

Although the invention has been described above with reference to specific embodiments, it is by no means limited thereto. The person skilled in the art will thus initially also implement embodiments which are not disclosed or only partially disclosed, without departing from the essence of the invention.

Claims (12)

Arrangement ( 100 ) for an electric compass, comprising: - a first wafer ( 10 ) with a first electronic evaluation circuit and a second electronic evaluation circuit; A micromechanical detection device ( 20 ) for detecting acceleration; Where the first wafer ( 10 ) and the micromechanical detection device ( 20 ) are layered; and a Hall element ( 40 ), which on a defined surface of the micromechanical detection device ( 20 ), wherein by means of the first electronic evaluation circuit, a signal of the micromechanical detection device ( 20 ) is evaluable and wherein by means of the second electronic evaluation circuit, a signal of the Hall element ( 40 ) is evaluable. Arrangement ( 100 ) according to claim 1, characterized in that the Hall element ( 40 ) on an upper side or on an underside of a cap wafer ( 21 ) of the micromechanical detection device ( 20 ) is arranged. Arrangement ( 100 ) according to claim 1, characterized in that the Hall element ( 40 ) on an upper side or on an underside of an acceleration MEMS element ( 22 ) of the micromechanical detection device ( 20 ) is arranged. Arrangement ( 100 ) according to one of claims 1 to 3, characterized in that the Hall element ( 40 ) has a III-V semiconductor layer. Arrangement ( 100 ) according to one of claims 1 to 3, characterized in that the Hall element ( 40 ) Graphs. Arrangement ( 100 ) according to one of the preceding claims, characterized in that for electrical contacting of the Hall element ( 40 ) Metal ( 50 ) and bonding wires ( 60 ) are provided. Arrangement ( 100 ) according to one of claims 1 to 5, characterized in that for electrical contacting of the Hall element ( 40 ) Metal ( 50 ) and vias ( 23 ) are provided. Arrangement ( 100 ) according to one of the preceding claims, further comprising a second wafer ( 30 ) associated with the first wafer ( 10 ) and with the micromechanical detection device ( 20 ), wherein the second electronic evaluation circuit on the second wafer ( 30 ) is arranged. Electric compass having an arrangement ( 100 ) according to any one of the preceding claims. Method for producing an arrangement ( 100 ) for an electric compass, comprising the steps: - providing a first electronic evaluation circuit on a first wafer ( 10 ); Providing a second electronic evaluation circuit on the first wafer ( 10 ); Providing a micromechanical detection direction ( 20 ) for detecting acceleration; and - depositing a Hall element ( 40 ) on a defined surface of the detection device ( 20 ), the first wafer ( 10 ), the micromechanical detection device ( 20 ) and the Hall element ( 40 ) are arranged layered. Method according to claim 10, wherein the Hall element ( 40 ) on a cap wafer ( 21 ) or on an acceleration MEMS wafer ( 22 ) of the micromechanical detection device ( 20 ) is deposited. The method of claim 10 or 11, further comprising the steps of: - providing a second wafer ( 30 ) associated with the first wafer ( 10 ) and the micromechanical detection device ( 20 ), wherein the second electronic evaluation circuit on the second wafer ( 30 ) is arranged.

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