WO2017102580A1

WO2017102580A1 - Micromechanical solid-electrolyte sensor apparatus

Info

Publication number: WO2017102580A1
Application number: PCT/EP2016/080400
Authority: WO
Inventors: Timothy John SCHULTZ; Rainer Ginzel; Christoph Hermes; Zach Byars; Christian Doering
Original assignee: Robert Bosch Gmbh
Priority date: 2015-12-15
Filing date: 2016-12-09
Publication date: 2017-06-22
Also published as: DE102015225176A1

Abstract

A solid-electrolyte sensor apparatus (110) for detecting at least one property of a gas and a method for measuring a property of a gas in a measurement gas chamber are proposed. The solid-electrolyte sensor apparatus (110) comprises: – at least one carrier substrate (112); – at least one layer structure (118) that has at least one first porous electrode (120), at least one second porous electrode (122) and a solid-electrolyte layer (124) embedded between the first porous electrode (120) and the second porous electrode (122) along a layer thickness direction (z). The at least one layer structure (118) in this case is arranged in a first region (210) of the at least one carrier substrate (112). The first region (210) is surrounded by a second region (220) with reference to a first plane (x, y) perpendicular to the layer thickness direction (z). There is an insulating region (230) provided at least in sections between the first region (210) and the second region (220). The thermal conductivity in the insulating region (230) is lower than the thermal conductivity in the second region (220).

Description

Description title

Micromechanical solid electrolyte sensor device prior art

From the prior art are sensor devices, in particular

Oxygen sensors and nitrogen oxide sensors, based on a

Solid state electrolyte known. For example, these are used as so-called lambda sensors in the automotive sector, in particular for detecting an air ratio of an air-fuel mixture. Alternatively, such sensors are used as nitrogen oxide sensors. Such sensor devices are currently typically manufactured by screen printing and / or thick film technology. As examples are so-called

Lambda jump probes to call. However, so-called broadband lambda probes can also be mentioned here.

DE 10 2012 201304 A1 discloses a micromechanical solid electrolyte sensor device and a corresponding production method. The micromechanical solid-state electrolyte sensor device has a micromechanical carrier substrate having a front side and a rear side, a first porous electrode and a second porous electrode and a solid electrolyte embedded between the first porous electrode and a second porous electrode.

In order to use a sensor as a lambda probe or as a nitrogen oxide sensor, for example, an operating temperature of more than 300 ° C, sometimes even more than 500 ° C may be required. In principle, a mobility of ions through a solid electrolyte through the Temperature of the sensor or the solid electrolyte can be controlled. For example, this is from Menzel et al., Origin of the Ultra-Nonlinear Switching Kinetics in Oxide-Based Resitive Switches, Adv. Funct. Mater., Vol. 21, pages 4487-4492, 2011.

Disclosure of the invention

It has been found that sensor devices can be provided with heating elements for achieving and maintaining the operating temperature. To detect at least one property of a gas is to achieve this

Operating temperature in both sensor devices, which are manufactured in conventional thick-film technology as well as in sensor devices, which are manufactured in micromechanical construction, a high power to heat up to the high operating temperature and to maintain the high operating temperature needed. Also, long heating times may be necessary. Also, large quantities of precious metals are required due to the design of the micromechanical sensor to remove the heating elements, e.g. from platinum alloys. Because the heating power P of a heating element or a

Heated conductor results according to the relation P = U ² / R, with U as the applied voltage and R as the electrical resistance of the heating element. The resistance R is given by the relation R = P * AH / I. Here, p is the specific electrical resistance, AH is the cross-sectional area of the heating conductor and I its length. Platinum may be required as a material to withstand great heat and, for example, aggressive fumes over life. Since the length I is usually predetermined and the material must be adapted to the ambient conditions, essentially the cross section AH can be changed to generate the required heating power. Length I multiplied by the cross section AH results in the volume of material that is required for a desired heat output.

Micromechanical solid electrolyte sensor devices already have some advantages over conventional solid electrolyte sensor devices. In particular, these offer approaches to miniaturize the sensor devices, for example by means of a production

microsystem semiconductor processes takes place. In many cases, a semiconductor material, for example silicon, serves as substrate for a

Thin-film membrane made of an oxygen-ion-conducting functional ceramic. Due to the miniaturization, the area to be heated can be reduced, which reduces the heating power. The heating up times can also be shortened.

Nevertheless, a comparatively high power, for example an electric power, is required even for microsystem-technologically produced sensors .

bring the sensor to operating temperature or to keep the operating temperature.

The high heating power in the range of several watts up to 50 watts is required on the one hand to the solid electrolyte membrane on the

To bring operating temperature. However, it has been shown that heating the solid electrolyte membrane drains a large proportion of the heating power into the surrounding areas, where the large amount of heat is not needed at all. This applies both to thick-film technology and to micromechanically produced sensors. The heat flow is simplified according to the following equation (1): dQ / dt = λ · (A / d) · ΔΤ (1) where dQ / dt is the heat output flowing out of the system per unit time, its unit is watt. Here, only the heat flow is considered, but not radiant heat, λ represents the specific thermal conductivity, which is material-dependent, their unit is Watt per milli-Kelvin (W / mK). A corresponds to the area through which the heat flows, d corresponds to the thickness of the body from wall to wall and ΔΤ corresponds to the temperature difference between the two

Measuring points. In the case of the sensor, for example, ΔΤ corresponds to

Temperature difference between a first temperature Tl, e.g. at the location of the heater and a second temperature T2, e.g. on an outside of the sensor, ΔΤ = Tl - T2. In the case of a planar sensor with a heater arranged in the plane of the surface, the surface A corresponds, for example, to the surface which appears as the surface

Wall surface results when the sensor is cut around the heater, the thickness d is the distance in the area from the location where the first temperature Tl is determined and the location where the second temperature T2 is determined.

The temperature difference and thus the heat flow can be very large. This results from the high operating temperature of more than 300 ° C and temperatures that can be approximately at room temperature (25 ° C) on an outside of the sensor.

There may therefore be a need to provide a sensor for detecting at least one property of a gas having the operating temperature _.

low power consumption reached and stops and reaches the operating temperature as quickly as possible. Basically, these properties are desirable both in conventional thick-film sensors as well as in microsystem sensors.

Advantages of the invention

Accordingly, in the context of the present invention, a

in particular micromechanical, solid electrolyte sensor device and a method for measuring a property of a gas, in particular a

Oxygen content and / or an air ratio, proposed, which at least partially circumvent or solve the disadvantages and limitations mentioned above. These are shown in the independent claims.

According to a first aspect of the invention, a solid electrolyte sensor device is proposed for detecting at least one property of a gas. The solid-state electrolyte sensor device may be micromechanically formed, for example. The solid electrolyte sensor device comprises at least one carrier substrate. The carrier substrate may be e.g. be formed as a semiconductor substrate. The solid-state electrolyte sensor device further comprises at least one layer structure including at least a first porous electrode, at least one second porous electrode, and a layer sandwiched between the first porous electrode and the second porous electrode along a layer thickness direction

Solid electrolyte layer has. The at least one layer structure is arranged in a first region of the at least one carrier substrate. In this case, the first area is perpendicular to the first plane

Layer thickness direction surrounded by a second area. In this case, at least in sections, an insulating region is provided between the first region and the second region. The insulating region is, for example, arranged transversely or perpendicular to the layer thickness direction between the first and second region. The thermal conductivity in the insulating region is less than the thermal conductivity in the second region. Here, in the layer thickness direction, a direction perpendicular to

Layer layer of the layer structure or in particular the

Solid electrolyte layer understood. It is assumed that the "

Layer structure, in particular the solid electrolyte layer, in the

Layer thickness direction (e.g., a z direction in a Cartesian)

Coordinate system) has a smaller extension than in the planar plane of extension of the layer structure (for example the x-y plane of the Cartesian coordinate system).

In this context, the term thermal conductivity is to be understood as meaning the thermal conductivity which, when averaging over the

Cross section (e.g., parallel to the layer thickness direction between the first region and the second region). In other words, the specific thermal conductivity values along a cross-sectional area are weighted according to their proportion in the cross-section, thus resulting in the heat conductivity relevant for the cross-section. The heated layer structure has along the layer thickness direction e.g. a first thickness in the first area. The

Carrier substrate or the semiconductor substrate have along the

Layer thickness direction in the second region on a second thickness. The

Thermal conductivity can now be determined by the weighted averaging of the specific thermal conductivities along the thicker of the two thicknesses or along the total thickness of the two thicknesses, when along the thickness of the two thicknesses

Layer thickness direction offset from each other are determined.

It is essential to the invention that in the insulating region the thermal conductivity is lower than in the second region, which is e.g. can adjoin the insulating region, for example, can directly adjoin, so that a heat flow from inner regions is reduced to the outside.

Thereby, according to the above-mentioned equation (1), the heat flow from the first area to the second area can be reduced by decreasing the term for the (average) thermal conductivity λ. The heating power can be reduced so advantageous, since the registered heating power is relatively considered to a greater extent in the heating of the layer arrangement and to maintain the operating temperature is used. In other words, the loss of heating power can be significantly reduced. Also, the time that is required to heat the sensor or the layer arrangement from a quiescent temperature to the operating temperature can be significantly shortened. Another advantage is that the heating elements can be made smaller, for example in their cross section AH, which basically a lot of in particular for _

a production required precious metals can be reduced. The sensor device can be made more compact and cheaper. The insulating region acts in the manner of a thermal insulating layer, for example, in

Can be arranged substantially parallel to the layer thickness direction.

Under a "solid electrolyte sensor device" is generally a

Sensor device to understand which at least one

Solid electrolyte used, so at least one solid material which is adapted to conduct ions, for example, oxygen ions. The

Solid-state electrolyte sensor device may in particular be designed to detect at least one property of a gas. The property of the gas can in this case in particular be an oxygen content and / or an air ratio and / or a proportion of a component in the gas, in particular one

Oxygen compound in the gas, in particular a NOx component be. The micromechanically produced solid-state electrolyte

Sensor device may be configured to qualitatively and alternatively or additionally also quantitatively detect the property of the gas. The

Solid-state electrolyte sensor device may be in particular an oxygen sensor or a nitrogen oxide sensor. However, other solid electrolyte sensor devices are conceivable in principle. Such sensors can be used in particular in exhaust systems. However, other applications are also conceivable.

In the context of the present invention, a "solid-state electrolyte" is a solid having electrolytic properties, ie ion-conducting

Properties, to understand. In particular, it may be a ceramic solid electrolyte. In particular, the solid electrolyte may comprise zirconia, preferably yttria-stabilized zirconia. Other materials are also conceivable.

The term "micromechanical" in the context of the present invention is generally to be understood as meaning the property of a three-dimensional structure which has dimensions in the micrometer range, i. in the range below 1 mm. For example, these may be widths of caverns, layer thicknesses of membranes or similar characteristic dimensions which may be present in this

Area lie. Compared to conventional sensor devices, which are usually manufactured in thick film technology using screen printing For example, micromechanical sensor devices are produced, at least in large part, using microsystem technology. These can be, for example, photolithographic processes known from semiconductor technology, as well as etching steps for structuring surfaces.

A "carrier substrate" here is to be understood as meaning a substrate which is suitable for forming a layer arrangement therefrom or for arranging the layer arrangement in it The carrier substrate may have, for example, an areal extent in a plane and have a thickness, for example substantially It may be, for example, a ceramic carrier substrate or a semiconductor carrier substrate or a semiconductor substrate.

Under a "semiconductor substrate" in the context of the present invention is basically an arbitrarily shaped semiconductor to understand. For example, the semiconductor substrate may be a disk-shaped or plate-shaped

Be semiconductor substrate. The semiconductor substrate may be formed in particular as a chip. The semiconductor substrate may further comprise at least one

Comprising semiconductor material selected from the group consisting of:

Silicon; a silicon compound, in particular silicon carbide; one

Gallium compound, in particular gallium arsenide. However, further materials are conceivable in principle.

Under a "layer structure" in the context of the present invention is basically any sequence of one or more layers to understand. For example, the layers can be arranged one above the other. The layers can cover or cover themselves completely or partially. For example, the layers may be arranged next to one another. However, the first electrode, the solid electrolyte layer and the second electrode along the layer thickness direction (z) are arranged, so one above the other. The layers may, for example, each have a thickness of 100 nm to 500 μηη. Other dimensions are possible in each case. The layer structure may further comprise layers of different materials. The layer structure may comprise several layers of the same material. Each layer alone may be unstructured or may also have a structure in a layer plane. Other embodiments are conceivable in principle. _Λ

An "electrode" in the context of the present invention generally means an element for the exchange of ions or electrons between the element and a solid electrolyte. In particular, by means of the electrode can be introduced by means of ions in the solid electrolyte, for example oxygen ions, which is also referred to as "incorporation" of the ions, and / or ions are discharged from the solid electrolyte and, for example, converted into a gas, for example oxygen gas, this process can also be referred to as "expansion" of the ions. The electrodes may thus be, in particular, electrical contacts for the electrical and / or ionic contacting of a solid electrolyte.

In the context of the present invention, a "porosity" is to be understood as meaning a ratio of void volume to total volume of a substance or mixture of substances as a dimensionless measured variable. This measure can be specified in particular in percent. For example, the first porous electrode and / or the second porous electrode may comprise an electrically conductive electrode material having a porosity of at least 3%, preferably at least 5%, more preferably at least 10%, most preferably at least 20% or even at least 40%. When adjusting the porosity, it may be desirable that at least partially

Continuous conductivity of the first porous electrode and / or the second porous electrode is present, preferably by a formation of isolated islands is at least largely reduced.

The porous, electrically conductive electrode material may comprise at least one ceramic compound, in particular composite materials made of ceramic

Materials with a metallic matrix, include. The porous, electrically conductive electrode material can in this case at least one metal, in particular

Platinum, palladium, gold, or copper, or have a metallic alloy. Furthermore, nitrogen-doped graphene can be used. In particular, nitrogen-doped graphene can be used due to a catalytic effect. Basically, however, every material is electrically conductive

Properties can be used. The porous, electrically conductive electrode material may further comprise at least one ceramic material, preferably selected from the group consisting of: alumina, zirconia. Other materials are basically usable.

The first porous electrode and the second porous electrode may have pores such that gas passage through the first porous electrode and / or the second porous electrode is possible. Thus, for example, a gas passage through the electrodes can take place, wherein the gas, for example oxygen O2, can be converted into ions, eg oxygen ions O ^{2 "} , at an interface between the electrode and the solid electrolyte, and wherein the ions enter a lattice of the solid electrolyte Conversely, ions, for example oxygen ions O ^{2 "} , can also be converted into gas, for example oxygen O ² , at the interface. The first porous electrode and / or the second porous electrode may be electrically contactable. The terms "first" and "second" porous electrode are as pure

To look at labels without indicating an order or ranking and, for example, without precluding the possibility that several types of first porous electrodes and several types of second porous

Electrodes or in each case exactly one type can be provided. For example, additional porous electrodes, for example one or more third porous electrodes, may be present in the layer structure.

The first porous electrode and the second porous electrode may be electrically contactable. For example, on the semiconductor substrate at least one electrode contact for a first porous electrode and at least one

Electrode contact may be provided for a second porous electrode. The first porous electrode and the second porous electrode can be, for example, by wire bonding and / or by means of at least one flip-clip method

be contactable. Other embodiments are conceivable in principle.

According to a second aspect of the invention, a method for measuring a property of a gas in a measurement gas space is proposed. In this case, the method comprises a use of, in particular

micromechanical solid electrolyte sensor device. In this case, the second porous electrode is exposed to the gas from the sample gas space.

In this case, furthermore, the first porous electrode is charged with a reference gas, for example air or oxygen or with air, the one having known oxygen concentration. The method further comprises detecting at least one electrical signal on an electrode, the electrode being selected from the group consisting of: the first porous electrode and the second porous electrode. By using the solid-state electrolyte sensor device according to the invention, advantageously, the heating power for setting or maintaining the operating temperature can be reduced. In addition, can advantageously shorten the heating time.

In principle, alternatively, the first electrode may also be charged with the gas from the measurement gas space and the second electrode with the reference gas or the gas from the reference gas space.

The method steps may preferably be carried out in the predetermined order; another order is conceivable. One or even several method steps can be performed simultaneously or overlapping in time. Furthermore, one, several or all of

Procedural steps can be carried out easily or repeatedly. The method may additionally comprise further method steps.

The method may further comprise detecting at least one electrical signal at the first porous electrode and / or at the second porous electrode.

In particular, at least one chemical property of a gas and / or a physical property of the gas can be detected.

In particular, in the method, an oxygen content and / or a

Partial oxygen pressure and / or a proportion of at least one component of the gas, in particular a proportion of an oxygen compound in the gas, in particular a NOx component, are detected. Accordingly, the method can serve, for example, for detecting an air ratio. However, other properties can be detected alternatively or additionally.

The "measuring space" may in particular be a gas space in a motor vehicle, for example an exhaust gas tract in a vehicle

Internal combustion engine. _ "

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The "reference gas" may in particular be at least one gas with at least one known composition, for example air, in particular ambient air.

The at least one "electrical signal" at the first porous electrode and / or at the second porous electrode may, for example, be a voltage between the first porous electrode and the second porous electrode. Alternatively or additionally, however, one or more currents may also be detected at or through the first porous and / or the second porous electrode. In particular, a jump signal can be detected, that is, a voltage signal at a passage of an air ratio λ = 1. However, other measurements are conceivable in principle.

Preferred developments of the invention, which individually or in

Combination are feasible, are shown in the dependent claims.

A development of the solid electrolyte sensor device provides that the insulating region comprises at least one material which has a lower specific thermal conductivity than the material in the second region.

In other words, the layer structure in the first region may be of the

Carrier substrate or the semiconductor substrate in the second region in the insulating region, e.g. by an insulating material, in particular by a dielectric

Insulation material, be isolated. In particular, the insulating material may have a low specific thermal conductivity or a low thermal conductivity relative to the thermal conductivity of the second region to a

To avoid heat transfer. Also material mixtures are possible. Also, in the insulating region, a layering of different materials is possible, which in the weighted average have a lower specific thermal conductivity than the material in the second region, in particular as the material of the second region directly adjacent to the insulating region.

In this way, can advantageously by reducing the specific thermal conductivity λ in the isolation region according to the above

Equation (1), the transfer of thermal power in the second range can be reduced. Since this heat transfer in the second region corresponds to an undesirable heat loss, which is now reduced, the advantageous Heating power can be reduced and the warm-up time for the to be heated

Solid electrolyte membrane or solid electrolyte layer decreases.

In an embodiment, it is provided that the insulating region comprises at least one material selected from the group consisting of: silicon, porous

Silicon, a silicon compound, in particular silicon nitride, in particular silicon dioxide; an aluminum compound, in particular aluminum oxide, in particular aluminum nitride; an insulating plastic, in particular polyimide. With regard to a carrier substrate or semiconductor substrate in the second region can be selected by this choice of material, the heat transfer and thus the

Heat loss from the first area in the second area can be significantly reduced.

Thus, e.g. Silicon, which is e.g. can be used as a material of the semiconductor substrate in the second region, a thermal conductivity at

Room temperature of about 140 to 150 W / mK on. On the other hand, porous silicon can be made to have a specific thermal conductivity of less than 5 W / mK, preferably less than 2 W / mK. Silicon nitride can be made to have a specific thermal conductivity of less than 35 W / mK or less than 25W / mK.

A further embodiment provides that a cavern is formed in the insulating area. Thereby, e.g. the side walls of the cavern may be formed by the outer walls of the first area facing the second area and / or by the outer walls of the second area facing the first area. In this case, the side walls of the cavern, for example, extend substantially parallel to the layer thickness direction.

Under a "cavern" is generally understood in the context of the present invention, in principle, a free and / or open cavity designed. The cavern and / or the further cavern may have a cuboid shape. Other embodiments are conceivable in principle.

This advantageously a particularly low heat loss performance is realized. In a consideration without radiant heat transfer, the cavern formed in the insulating region acts with its "filling" of air or the ambient gas or even vacuum as a material layer with a particularly low specific Thermal conductivity. Air, for example, has a specific thermal conductivity at room temperature of less than 0.03 W / mK - so it is negligible compared to a solid-state thermal conductivity. The cavern thus acts as a first approximation as a reduction of the area A from the equation (1) over which the first area is in contact with the second area. Thus, even if the insulating region in a direction perpendicular to the layer thickness direction is formed only very narrow, for example, only 50nm to lOOOnm, so decreases in

Insulation advantageous advantageous the (average) thermal conductivity through the arrangement of the cavern, so that the heat loss performance is greatly reduced.

A development provides that a layer is arranged on the semiconductor substrate, wherein the layer extends from the first region to the second region. The layer may be e.g. be formed in their adjacent to the cavern sections as a membrane.

In the context of the present invention, a "membrane" is generally to be understood as meaning a layer or layer sequence whose lateral extent exceeds the thickness of the layer or layer sequence by at least a factor of 10, preferably by at least a factor of 100. The membrane may be formed in the present case by the layer structure, but in addition one or more further layers may be contained in the membrane.

A heat transfer can advantageously be further reduced by a thickness of the layer is reduced or is made very small. This again results from equation (1). Because the layer thickness affects in cross-section between the first and the second area the passage area A for the

Heat conduction. Ideally, the membrane is the only mechanical and thus thermally conductive connection between the first area and the second area. It can e.g. Bridging the cavern in the insulation area and thus representing the only thermal bridge. The smaller the thickness of the layer or membrane, the lower the passage area A. In this way, the, e.g. micromechanical solid electrolyte sensor device in particular be divided into at least one "hot region" in the first region and at least one "cold region" in the second region. The hot ones

Regions and the cold regions may be connected to each other through the membrane. The membrane may in particular have a small thickness, For example, in the range of 0.1 to 100 μηη, and continue to have a thermally insulating function, so that only a minimal heat transfer from the hot region to the cold region can take place.

A further development provides that the cavern along the

Layer thickness direction (z) regards the carrier substrate, e.g. when

Semiconductor substrate formed completely penetrates. This will be the

Passage area A for heat from the first area to the second area advantageously particularly greatly reduced or is thereby the (averaged)

Thermal conductivity between the first region and the second region in the insulating region is particularly reduced.

Accordingly, a cavity which completely penetrates the carrier substrate or the semiconductor substrate is to be understood as meaning a cavity which surrounds the carrier substrate or semiconductor substrate from a front side of the carrier substrate or semiconductor substrate to a rear side of the carrier substrate

Carrier substrate or the semiconductor substrate completely penetrated.

In this way, the passage area A for heat is maximally reduced. The first area may still be selectively connected to the second area in the insulating area by sections in which the cavern does not completely penetrate the carrier substrate or the semiconductor substrate. Alternatively or additionally, the first region may be connected to the second region by means of the layer or the membrane. In both cases, the heat transfer and thus the heat loss performance by reducing the passage area A and / or due to the low specific thermal conductivity of the

Connection points greatly reduced.

A further development provides that the cavern is at least partially filled with a material which has a lower specific thermal conductivity than the material in the second region. The cavern is in particular at least partially filled with a material selected from the group consisting of: silicon, porous silicon, a silicon compound, in particular silicon nitride, in particular silicon dioxide; one

Aluminum compound, in particular aluminum oxide, in particular

aluminum; Polyimide. As a result, heat dissipation from the first region to the second region can advantageously be reduced by the insulating region. At the same time a high mechanical stability of the solid electrolyte sensor device is advantageously ensured, since the cavern is filled with a solid. In this way, for example, thermal stresses in the insulating region over a large cross-sectional area (cross section parallel to the layer thickness direction) can be reduced. The cavern can be filled with the insulating material after its production, for example by an etching process. Alternatively or additionally, it can be provided that the layer at least one

Includes material having a lower specific thermal conductivity than the material in the second region, wherein the layer comprises at least one material selected from the group consisting of: silicon, porous silicon, a silicon compound, in particular silicon nitride, in particular silicon dioxide; an aluminum compound, in particular

Alumina, in particular aluminum nitride; a thermally insulating plastic, e.g. Polyimide.

This advantageously causes a heat transfer from the first region to the second region by means of the layer or the membrane

Layer according to the equation (1) not only because of the low

Passage area A is reduced. Rather, it is also the specific one

Thermal conductivity λ of the layer material less than that of the material in the second region. As a result, a particularly low heat transfer can be ensured. If the layer is e.g. because of a completely through the

Due to the proposed choice of material for the layer, loss heat transfer from the first region to the second region can be almost completely prevented by means of the proposed material selection for the layer. A heat loss is then essentially only caused by radiant heat, but no more or only greatly reduced by heat conduction.

A further development provides that the micromechanical solid electrolyte sensor device has at least one further cavern. In this case, the further cavern can be arranged, for example, in the first region. In this case, the further cavern defines at least one further membrane formed by the layer structure. This has the advantageous effect that the layer structure is particularly well thermally isolated from the environment. The further membrane is connected, for example, only at its edge regions with the carrier substrate or the semiconductor substrate. In another embodiment, the further cavern may be formed such that it does not completely penetrate the carrier substrate or the semiconductor substrate. In both cases, the heating power or the heating energy to be introduced, which is necessary to bring the solid electrolyte layer to the operating temperature can be advantageously further reduced. Because the thermal mass, which is heated, is significantly reduced. It consists of the layer structure and the material of the carrier substrate or the semiconductor substrate which is thermally conductively connected to the layer structure along the layer thickness direction below or above the further membrane. Further advantageous thereby the heating time is reduced, whereby the

Sensor device reaches the operating temperature faster and thus can be used faster.

The further cavern may be formed, for example, like the cavern. It can e.g. the carrier substrate or the semiconductor substrate completely

penetrate. For example, the cavern and / or the further cavern may be wholly or partially formed as a continuous window from the front to the back, for example as a rectangular window. However, other forms are possible.

The layer structure can on the carrier substrate or on the

Semiconductor substrate may be applied, that the first porous electrode covers at least one surface of the further cavern and the second porous electrode is disposed on a side facing away from the semiconductor substrate side of the layer structure. The solid electrolyte layer may define the further cavity at a front side of the semiconductor substrate.

In a further development it is provided that the membrane in a cross section parallel to the layer thickness direction (z) has at least one profile, wherein the profile is selected from the group consisting of: at least one

Rectangular profile, at least one T-profile, at least one double T-beam profile. In the context of the present invention, the "profile" of the second membrane is understood to mean a cross section through the membrane transversely to an extension direction of the membrane or substantially parallel to the layer thickness direction. In this case, the cross section has a cross-sectional shape.

The rectangular profile has a rectangular cross-sectional shape.

A single T-profile, in addition to the rectangular cross-sectional shape, has a rectangular bar extending substantially perpendicular to the rectangular cross-sectional shape.

A profile with a plurality of T-profiles or T-profile sections has a plurality of additional elements substantially perpendicular to the rectangular one

Cross-sectional shape arranged rectangular bars on. In other words, a profile having a plurality of T-profiles may in particular have a portion which extends along the direction of extent of the

Diaphragm extends and have a plurality of webs, which at a distance from one another, in particular at a regular distance from each other, align transversely, in particular perpendicular, to the section.

A double-T-beam profile may be formed as a T-profile, wherein at the end facing away from the rectangular cross-sectional shape of the beam perpendicular thereto another beam is arranged. For example, this further beam may be substantially parallel to the rectangular cross-sectional shape.

In the case of a plurality of double-T-beam profiles, the further beams can be connected to one another in such a way that a further rectangular cross-sectional shape substantially parallel to the rectangular cross-sectional shape and essentially continuous is formed. In other words, a profile which has a large number of double-T-beam profiles can be divided, in particular, into an upper part and a lower part, which run parallel to one another in the direction of extension of the membrane or which run parallel to the xy- Level. In this case, the first part and the second part can be arranged at a defined distance from one another, so that as a result a gap is formed between them in the layer thickness direction (z direction). Within the gap here several webs be arranged, which are transversely, in particular perpendicular, to the

Align the extension direction of the diaphragm. The webs can be arranged in this case in particular parallel to each other.

Because the membrane has a profile, it is advantageously mechanically stabilized against tensile stresses or compressive stresses parallel to its surface due to an increased area moment of inertia. such

Stress can occur, for example, if the first region is at least partially connected only by means of the membrane with the second region. The membrane spans over the insulation area like a bridge

Isolation. Since the first region has a considerably higher heating temperature than the second region, it expands and compresses the membrane. On contraction as a result of cooling, the membrane is placed under tension (always viewed in a plane substantially perpendicular to the layer thickness direction) ). The formation of a profile on the membrane can mechanically stabilize the membrane and prevent the formation of cracks.

In other words, during operation of a, for example micromechanical, solid-state electrolyte sensor device, heating of the hot region may generally occur, for example, and the membrane may undesirably deform excessively. The deformation can be reduced by the profiles as already described or described below.

A further development provides that the membrane comprises a membrane front side and a membrane rear side, the membrane rear side being directed towards the cavern, the membrane rear side having a multiplicity of indentations open to the cavern.

The term "indentation" in the context of the present invention basically refers to an open cavity. Preferably, it can be a cavity projecting into the membrane.

A further development provides that the indentations have a cross section selected from the group consisting of: a circle; a polygon, in particular a triangle, in particular a hexagon, wherein the Indentations are arranged in particular in the form of a regular structure.

In this case, the indentations can be arranged on the rear side of the membrane, in particular in the form of a regular structure, which has juxtaposed recesses arranged next to one another.

These refinements advantageously achieve a particularly large mechanical stabilization. At the same time, the passage area A is for a

Heat transfer from the first region to the second region across the membrane advantageously still given by the parallel in cross section to the

Layer thickness direction Thinnest point of the membrane, ie the areas with the indentations. Thus, with high mechanical stability of the heat loss is greatly reduced.

A further development provides that the membrane has a thickness in the range from 100 nm to 500 μm, preferably from 500 nm to 100 μm.

As a result, the passage area A is advantageously particularly greatly reduced for heat transfer through the membrane. At the same time, this thickness is sufficient to make the membrane mechanically stable over the desired one

To design operating life of the sensor device.

The membrane may further be arranged to at least substantially reduce heat transfer from the layer structure to further regions of the semiconductor substrate. This can be done as shown above e.g. be effected by a suitable choice of material and / or by a structuring or profiling of the membrane.

A further development provides that the, for example micromechanically produced, solid-state electrolyte sensor device is an oxygen sensor or a nitrogen oxide sensor.

A development provides that the micromechanical solid electrolyte sensor device comprises at least one heating element, wherein the heating element is arranged in the first region. The at least one heating element may be configured to heat the solid electrolyte layer of the layer structure. Characterized in that the heating element is arranged in the first region, an unnecessary heating of the second region is advantageously avoided. In this way, the heating power can be reduced and / or the heating element can be made smaller.

The heating element can in particular at least one electrical

Include heating resistor element. The heating element can be arranged between the further membrane and the membrane in a direction perpendicular to the layer thickness direction.

The electrode-solid electrolyte-electrode structure may be arranged in particular in a direction transverse to the layer thickness direction. In other words, the heating element, for example, at least partially enclose the layer structure. The heating element is then arranged so viewed in a radial direction in the x-y plane of the other membrane outside the other membrane.

This can advantageously a particularly effective heating of the

Layer arrangement can be ensured.

Alternatively or additionally, the electrode-solid electrolyte-electrode structure can be arranged in a direction along the layer thickness direction between the heating element or the heating elements.

A further development provides that the heating element can be electrically contacted by a supply line penetrating the layer. As a result, the layer which can be formed as a membrane can be advantageously used for two purposes in a particularly simple manner: on the one hand, it can thermally decouple the first region from the second region. Second, it serves as a carrier for the electrical leads to the heating element and thus stabilizes the leads mechanically. Because it can, as stated above, between the first area and the second area in the insulation to strong mechanical

Voltages come, eg thermal stresses. To prevent damage to the electrical leads to the heating element, these can be advantageously embedded in the mechanically stabilized membrane. Brief description of the figures

Further optional details and features of the invention will become apparent from the following description of preferred embodiments, which are shown schematically in the figures.

Show it:

1A is a schematic sectional view of a

Solid electrolyte sensor device;

Figure 1B is a schematic sectional view of another

Solid electrolyte sensor device;

Figures 2.1.1 to 2.4.2 representations of differently formed membranes of a solid electrolyte sensor device in

Sectional view along an extension direction of the membrane (2.1.1, 2.2.1, 2.3.1, 2.4.1) and in a vertical sectional view (2.1.2, 2.2.2, 2.3.2) or in a view of the bottom of the Membrane (2.4.2).

Description of the embodiments

FIG. 1A shows a cross section in an x-z plane of the drawn Cartesian coordinate system through a solid electrolyte sensor device 110 for detecting at least one property of a gas. The solid electrolyte sensor device 110 may be e.g. be made in conventional thick-film technology, so for example with

Screen printing process. However, it can also be produced micromechanically, ie, for example, using photolithographic processes from microsystems technology. The solid-state electrolyte sensor device 110 in this case comprises a carrier substrate 112. This may be formed, for example, in the case of a micromechanical sensor device 110, for example as a semiconductor substrate 113; in thick-film technology, it may be a ceramic carrier substrate. The carrier substrate 112, when formed as a semiconductor substrate 113, may comprise at least one semiconductor material selected from the group consisting of: silicon; a silicon compound, in particular silicon carbide; a gallium compound, in particular gallium arsenide. The semiconductor substrate 113 may be formed in particular as a chip.

The solid-state electrolyte sensor device 110 further comprises at least one layer structure 118, which comprises at least one first porous electrode 120, at least one second porous electrode 122, and one along a first porous electrode 120

Layer thickness direction (z) between the first porous electrode 120 and the second porous electrode 122 embedded solid electrolyte layer 124 has. The at least one layer structure 118 is arranged in a first region 210 of the at least one carrier substrate 112. In this case, the first region 210 is surrounded by a second region 220 with respect to a first plane (the x-y plane) perpendicular to the layer thickness direction (z).

The first porous electrode 120 may in this case face a measuring gas space, e.g. an exhaust gas, wherein the sensor device 110 should detect at least one property of a gas present in the sample gas space. The second porous electrode 122 may in this case face a reference gas space, in which e.g. a defined oxygen concentration is present.

Alternatively, the first electrode 120 may face the reference gas space and the second electrode 122 may face the sample gas space.

In the drawn Cartesian coordinate system corresponds to the

Layer thickness direction (z) so the z-direction while the surface

Extension of the layer structure 118 in the direction of the layer thickness

vertical x-y plane extends. In the cross-section of FIG. 1A, only the x-z plane is shown. The y-direction extends into the image plane.

In this case, at least in sections, an insulating region 230 is provided between the first region 210 and the second region 220. It is the

Thermal conductivity in the insulating region 230 less than the thermal conductivity in the second region 220. In the illustrated embodiment, this can

For example, be effected by the use of a material in the insulating region 230, the specific thermal conductivity λ is less than that ".

For example, the first region 210 and the second region 220 may be formed at least partially from the same material and may, for example, be formed of the same thermal conductivity λ of the second region 220 surrounding the insulating region 230. B. silicon include.

The solid electrolyte sensor device 110 may further comprise at least one heating element 140, which is arranged in the first region 210.

This heating element 140 is configured to heat the layer arrangement 118 and, in particular, the solid electrolyte membrane 124. The heating element 140 can at least partially surround the layer arrangement 118 in the first plane (x-y plane) viewed radially on the outside.

When the heating element 140 is heated, it heats beside the

Layer arrangement 118 by heat conduction also the second region 220. The heat flow into the second region 220 is indicated by arrows with the

The heat discharge Q per time into the second region 220 results from Equation (1) above: The heated first region 210 projects beyond a passage area A, of which only a one-dimensional line can be seen in the sectional drawing shown. The second region 220 is thermally conductive over the isolation region 230. A width d of the isolation region 230 is the third parameter from equation (1) that affects the unwanted heat dissipation from the first region 210 into the second region 220 Width d and / or the

Passage area A and / or the (averaged) thermal conductivity in isolation region 230 may reduce heat dissipation, i. the heat flow from the first region 210 into the second region 220, can be purposefully reduced.

FIG. 1B shows a further embodiment of a solid electrolyte sensor device 110, which is micromechanically formed or manufactured here. The same reference numerals as in FIG. 1A identify elements having the same functions.

As in FIG. 1A, the solid electrolyte sensor device 110 illustrated in FIG. 1B comprises at least one layer structure 118 with at least one first porous electrode 120, at least one second porous electrode 122 and one in the layer thickness direction (z) between the first porous electrode 120 and the second porous electrode 122 embedded solid electrolyte layer 124th

The first porous 120 electrode may be facing a measuring gas space and the second porous electrode 122 a reference gas space. Alternatively, the first electrode 120 may face the reference gas space and the second electrode 122 may face the sample gas space.

In this case, the carrier substrate 112 can have a front side 114 (in the figure above) along the layer thickness direction (z) and a rear side 116 (in the figure below).

The layer structure 118 may be arranged at least partially on or in the front side 114 of the carrier substrate 112 formed as a semiconductor substrate 113. The layer structure 118 and a heating element 140 surrounding the layer structure 118 at least in sections are arranged in the first region 210.

Viewed from the first region 210 radially outwards in the x-y plane, the insulating region 230, which in turn adjoins the second region 220, adjoins the first region 210.

The micromechanical solid electrolyte sensor device 110 comprises at least one layer 126 or insulating layer 126 which is located on the

Front side 114 of the semiconductor substrate 113 may be arranged. The layer 126 may be thermally insulating with respect to the semiconductor substrate 113, that is, it may have a lower specific thermal conductivity λ than the second region 220. It may be e.g. be formed of a material comprising at least one insulating material selected from the group consisting of: porous silicon, a silicon compound, in particular silicon nitride or silicon dioxide; an aluminum compound, in particular aluminum oxide or aluminum nitride; an insulating plastic,

in particular polyimide. The insulating layer 126 may in particular be designed to insulate the layer structure 118 from the semiconductor substrate 113.

Furthermore, the micromechanical solid-state electrolyte sensor device 10 O comprises at least one cavern 130, which in the insulating region 230 is arranged. The cavern 130 may be formed, for example, as a rectangular window and the first area 210 partially or completely surrounded (in the xy plane considered). The cavern 130 may completely penetrate the semiconductor substrate 113. The cavern 130 defines at least one membrane 134, which thus at least partially in the insulating region

230 is arranged. The membrane 134 bridges the cavern 130 in the isolation region 230 and connects the first region 210 to the second region 220. in the insulating region 230, at least in the sections in which the cavity 130 is arranged, constitute the only connection between the first region 210 and the second region 220. A heat conduction can then take place only through the layer 126. Here is the

Heat transfer by radiation not considered. Thus, the

Heat transfer surface A in the insulating region 230 significantly reduced - because this area A is only the cross-sectional area of the membrane 134. Alternatively or additionally, because of the low specific thermal conductivity of gases

(averaged) thermal conductivity in the insulating region 230 with respect to

Thermal conductivity in the second region 220 significantly reduced.

The membrane 134 may be configured to at least substantially reduce heat transfer from the layer structure 118 to further regions of the semiconductor substrate 113. The membrane 134 may have a thickness in the range from 100 nm to 500 μm, preferably from 500 nm to 100 μm.

The layer structure 118 may be applied to the semiconductor substrate 113 such that the first porous electrode 120 covers at least one surface 136 of another cavity 128. The further cavern 128 is arranged in the first region 210. The further cavern 128 may in principle be designed similar to the cavern 130. The further cavern 134 may be e.g. the

Semiconductor substrate 113 as the cavern 130 also in the layer thickness direction (z) considered completely penetrate. The further cavity 134 may define at least one further membrane 132 formed by the layer structure 118. This further membrane 132 may be given by the layer structure 118.

The second porous electrode 122 may be arranged on a side 138 of the layer structure 118 facing away from the semiconductor substrate 113. The

Solid electrolyte layer 124 may define the further cavity 128 at the front side 114 of the semiconductor substrate 113. The heating element 140 can be arranged in the xy plane between the further diaphragm 132 and the diaphragm 134, in particular on the front side 114 of the semiconductor substrate 113. The heating element 140 may

in particular, be configured to heat the solid state electrolyte layer 124 of the layer structure 118. The heating element can be electrically contacted by a feed line 142 penetrating the layer 126 or embedded in the layer 126. The (micromechanical) solid electrolyte sensor device 110 may further comprise at least one electrical contact 144.

FIGS. 2.1.1 to 2.4.2 respectively show exemplary embodiments of the membrane 134 in the insulating region 230 of the solid-state electrolyte sensor device 110 according to the invention from FIG. 1B. The membrane 134 is shown in FIGS. 2.1.1, 2.2.1, 2.3.1 and 2.4.1, each in a sectional view in the x-z plane. It is thus shown a detail which represents the insulating region 230 and in the figure to the left and right thereof the adjoining second region 220 and the first region 210, respectively.

In FIGS. 2.1.2, 2.2.2 and 2.3.2, the membrane 134 is in a cross-sectional view, in particular perpendicular, to the sectional view from FIGS. 2.2.1, 2.2.1, 2.3.1 and 2.4.1, ie represented in a section in the yz plane, corresponding to the indicated section lines from Figures 2.1.1, 2.2.1 and 2.3.1.

In Figure 2.4.2, a back side 148 of the membrane 134 is shown, that is one

Supervision on the x-y plane.

The membrane 134 may be transverse, in particular perpendicular, to its

Extension direction 146 in the illustrated section (here corresponds to the

Extension direction so the x-direction) have at least one profile 150. For example, the membrane 134, as shown in Figures 2.1.1 and 2.1.2, have a rectangular profile 152.

Alternatively, the membrane 134, as shown in Figures 2.2.1 and 2.2.2, for example, have at least one T-profile 154. In particular, the membrane 134 may have a plurality of T-profiles 154. Alternatively, as shown in FIGS. 2.3.1 and 2.3.2, the membrane 134 may have a profile 150 comprising at least one double T-beam profile 156. In particular, the membrane 134 may include a plurality of dual T-beam profiles 156, thereby providing a membrane 134 having two mutually substantially parallel, continuous layers spaced apart along the layer thickness direction (z). In the gap between the two layers, the beams extending perpendicular to the layer extension are formed in the manner of webs.

In a further exemplary embodiment, as shown in FIGS. 2.4.1 and 2.4.2, the rear side 148 of the membrane 134 can have a multiplicity of indentations 158 that are open to the cavern 130. The membrane 134 may include a membrane front 160 and a membrane rear 162 and back 148, respectively, of the membrane. The membrane rear side 162 may be directed toward the cavity 134. The membrane rear side 162 may have the indentations 158. The indentations 158 can, as is apparent in particular from FIG. 2.4.2, have a rectangular cross-section 164. In this case, the indentations 158 can, in particular, be arranged in the form of a regular structure 166, as further shown in FIG. 2.4.2. Through the formation of the profiles or the formation of the structure with the

Indentations 158, the area moment of inertia of the membrane 134 increases significantly without significantly more heat can flow through the membrane 134 from the first region 210 into the second region 220.

Claims

claims

1. Solid-state electrolyte sensor device (110) for detecting at least one property of a gas, wherein the solid-state electrolyte sensor device (110) is in particular micromechanically formed, the solid-state electrolyte sensor device (110) comprising:

• at least one carrier substrate (112), in particular as a semiconductor substrate (113) formed;

At least one layer structure comprising at least one first porous electrode, at least one second porous electrode and one along a layer thickness direction between the first porous electrode and the second porous electrode embedded solid electrolyte layer (124);

wherein the at least one layer structure (118) is arranged in a first region (210) of the at least one carrier substrate (112), wherein the first region (210) is perpendicular to the layer thickness direction (z) of a first plane (x, y) surrounded by the second area (220),

wherein an insulating region (230) is provided at least in sections between the first region (210) and the second region (220), the thermal conductivity in the insulating region (230) being less than the thermal conductivity in the second region (220).

2. Solid-state electrolyte sensor device (110) according to the preceding claim,

wherein the insulating region (230) comprises at least one material having a lower specific thermal conductivity than the material in the second region (220).

3. Solid-state electrolyte sensor device (110) according to one of

previous claims, wherein the insulating region (230) comprises at least one material selected from the group consisting of: silicon, porous silicon, a

Silicon compound, in particular silicon nitride, in particular

silica; an aluminum compound, in particular aluminum oxide, in particular aluminum nitride; an insulating plastic,

in particular polyimide.

Solid state electrolyte sensor device (110) according to one of

previous claims,

wherein a cavern (130) is formed in the insulating region,

wherein in particular the side walls of the cavern (130) through the second region (220) facing the outer walls (212) of the first

Area (210) and through the first area (210) facing

Outer walls (222) of the second region (220) are formed,

wherein the side walls of the cavern in particular extend substantially parallel to the layer thickness direction.

The solid state electrolyte sensor device (110) of claim 4, wherein a layer (126) is disposed on the support substrate (112), the layer (126) extending from the first region (210) to the second region (220).

wherein the layer (126) is formed as a membrane (134), in particular in its sections adjacent to the cavern (130).

Solid-state electrolyte sensor device (110) according to one of claims 4 or 5,

wherein the cavern (130) completely penetrates the carrier substrate (112), in particular the semiconductor substrate (113), viewed along the layer thickness direction (z).

A solid state electrolyte sensor device (110) according to any one of claims 4 to 6,

wherein the cavern (130) is at least partially filled with a material which has a lower specific thermal conductivity than the material in the second region (220),

wherein the cavern is in particular at least partially filled with a material selected from the group consisting of: silicon, porous Silicon, a silicon compound, in particular silicon nitride, in particular silicon dioxide; an aluminum compound, in particular aluminum oxide, in particular aluminum nitride; an insulating plastic, in particular polyimide;

and or

wherein the layer (126) comprises at least one material which has a lower specific thermal conductivity than the material in the second region (220),

wherein the layer (126) comprises in particular at least one material selected from the group consisting of: silicon, porous silicon, a silicon compound, in particular silicon nitride, in particular silicon dioxide; an aluminum compound, in particular aluminum oxide, in particular aluminum nitride; an insulating plastic,

in particular polyimide.

Solid state electrolyte sensor device (110) according to one of

preceding claims, wherein the solid electrolyte sensor device (110) has at least one further cavern (128), wherein the further cavern (128) is arranged in particular in the first region (210),

wherein the further cavern (128) at least one through the

Layer structure (118) defined further membrane (132) defined.

Solid state electrolyte sensor device (110) according to one of

preceding claims, wherein the membrane (134) in a

Cross-section parallel to the layer thickness direction (z) has at least one profile (150), wherein the profile (150) is selected from the group consisting of: at least one rectangular profile (152), at least one T-profile (154), at least one double -T-beam profile (156).

Solid state electrolyte sensor device (110) according to one of

preceding claims, wherein the membrane (134) has a

The membrane front (160) and a membrane rear side (162), wherein the membrane rear side (162) is directed to the cavern (130), wherein the membrane rear side (162) has a plurality of cavities (130) open recesses (158).

11. Solid state electrolyte sensor device (110) according to the preceding claim, wherein the indentations (158) have a cross section (164) selected from the group consisting of: a circle; a polygon, in particular a triangle, in particular a hexagon, wherein the recesses (158) are arranged in particular in the form of a regular structure (166).

12. Solid-state electrolyte sensor device (110) according to one of

preceding claims, wherein the membrane (134) has a thickness in the range of 100 nm to 500 μηη.

13. Solid-state electrolyte sensor device (110) according to one of

previous claims,

wherein the solid electrolyte sensor device (110) comprises at least one heating element (140),

wherein the heating element (140) is arranged in the first region (210), wherein the at least one heating element (140) is arranged in particular to heat the solid electrolyte layer (124) of the layer structure (118).

14. Solid-state electrolyte sensor device (110) according to the preceding claim, wherein the heating element (140) is electrically contactable by a feed line (142) penetrating the insulation layer (126).

15. A method for measuring a property of a gas in a

Sample gas space, comprising a use of the solid electrolyte sensor device (110) according to one of the preceding claims,

- Wherein the second porous electrode (122) with the gas from the

Measuring gas space is acted upon and

- wherein the first porous electrode (120) is acted upon by a reference gas,

wherein the method further comprises detecting at least one electrical signal on an electrode selected from the group consisting of: the first porous electrode (120) and the second porous electrode (122).