WO2016020240A1

WO2016020240A1 - Sensor for detecting at least one chemical species and method for production thereof

Info

Publication number: WO2016020240A1
Application number: PCT/EP2015/067373
Authority: WO
Inventors: Frederik ANTE
Original assignee: Robert Bosch Gmbh
Priority date: 2014-08-06
Filing date: 2015-07-29
Publication date: 2016-02-11
Also published as: DE102014215492A1

Abstract

The invention relates to a sensor (100) for detecting at least one chemical species (102), wherein the sensor (100) has a capacitative structure (104), an electrically insulating insulation layer (106) and a self-assembly monolayer (108). The capacitative structure (104) is designed to represent a capacity of the structure (104) in an electrical capacity signal (110). The insulation layer (106) is disposed on the structure (104). The self-assembly monolayer (108) is disposed on the insulation layer (106). The monolayer (108) is formed from molecules (112) bonded by means of a stable bond to the insulation layer (106) at a first end (114) and designed for entering into a bond with the species (102) at an opposite second end (116).

Description

Description title

Sensor for detecting at least one chemical species and method for its production

State of the art

The present invention relates to a sensor for detecting at least one chemical species, to a fluid for forming a self-assembling monolayer, and to a method for manufacturing a sensor.

In order to be able to image a concentration of a chemical species in an electrical signal, for example, a resistive approach can be selected. In this case, an electrical resistance of a conductor changes as the concentration of the species changes.

Disclosure of the invention

Against this background, a sensor for detecting at least one chemical species, a fluid for forming a self-assembling monolayer and a method for producing a sensor according to the main claims are presented with the approach presented here. Advantageous embodiments emerge from the respective subclaims and the following description.

A concentration of a chemical species can be imaged in an electrical signal by a capacitive approach. It is exploited that molecules and / or atoms of the species can form bonds with a sensor surface and thus a resulting charge shift at the Sensor surface is changed an electric field of the sensor surface. This change in the electric field can be detected by an electrical circuit and mapped in an electrical signal. Advantageously, the sensor surface with the adhering molecules and / or atoms has a very small distance from the electrical circuit. In particular, a self-assembling monolayer can

Sensor surface can be used, since a thickness of the monolayer is very small and is determined by a molecular length of the molecules of the monolayer.

There is provided a sensor for detecting at least one chemical species, the sensor comprising: a capacitive structure configured to map a capacitance of the structure in an electrical capacitance signal; an electrically insulating insulating layer disposed on the structure; and a self-assembling monolayer disposed on the insulating layer, wherein the monolayer is composed of molecules attached at a first end by means of a stable chemical or covalent bonding with the monolayer

Insulating layer are connected and are formed at an opposite second end to enter into a connection with the species. In the present case, a sequence of layers of a sensor element can be understood as a sensor (which can also be referred to as a sensor structure). Each layer may be an integral part of the sensor or sensor element. A chemical species may be a chemical element or a chemical compound with this element. The species can be present as a single atom. The species can be part of a molecule. A capacitive structure may be configured to map a change in capacitance in the capacitance signal. The capacitive structure may be configured to provide the capacitance signal using a supply voltage. An insulating layer may be electrically non-conductive. The insulating layer can have a uniform layer thickness exhibit. The insulating layer may be firmly connected to the structure. The molecules of the monolayer may be oriented transversely to a surface of the insulating layer. The second ends may point away from the insulating layer. In particular, the species can be at least one bindable

Have connection point for docking at the second end of the monolayer. In the present case, a stable compound can be understood to mean a chemical bond which does not substantially separate at room temperature (that is to say in a range from 10 to 40 ° C.) without the supply of external energy. In the present case, a bond can be understood as meaning a chemical compound, in particular a covalent bond.

Furthermore, a fluid for forming a self-assembling monolayer is disclosed, which can be arranged on the insulating layer, wherein the monolayer is composed of molecules which at a first end by means of a stable

Connection with the insulating layer are connectable and on a

opposite second end are adapted to enter into a connection with the species.

A fluid may be a liquid or a gas. The fluid may have the molecules of the monolayer in an unbound state.

Furthermore, a method for producing a sensor according to the approach presented here is presented, wherein the method comprises the following steps:

Providing a capacitive structure configured to map a capacitance of the structure in an electrical capacitance signal;

Forming an electrically insulating insulating layer on the structure; and

Depositing molecules on the insulating layer to form a self-assembling monolayer, wherein the molecules are connected at a first end by a stable connection to the insulating layer and are formed at an opposite second end to connect to at least one species. The attachment can be carried out using a fluid according to the here

presented approach. The training can be done by yourself

Use of a reactive species in an environment of the structure done. For example, the formation may be done using oxygen. The capacitive structure may include a source contact, a drain contact, a semiconductor material, and a gate electrode. The capacitance signal may be a current flow between the source contact and the drain contact

represent. The capacitive structure may be formed as a transistor. In particular, the capacitive structure may be implemented as a CM OS structure. Transistors are known as reliable components. The production of transistors is inexpensive using semiconductor technology possible.

The gate electrode may be disposed adjacent to the insulating layer. Then, a material of the gate electrode may be used as the starting material of the insulating layer. In particular, the insulating layer can be formed without applying another layer.

The semiconductor material may be disposed adjacent to the insulating layer. As a result, the capacitance can be detected with particularly high sensitivity since the monolayer has a particularly small distance from the capacitive structure.

The sensor may include an electrode for influencing the capacitance of the capacitive structure. By way of example, an operating point of the capacitive structure can be set by means of an additional electrode. For example, the operating point can be moved to a particularly sensitive region of a characteristic curve. A material of the electrode may serve as the starting material of the insulating layer.

The electrode may be disposed between the insulating layer and the capacitive structure. The electrode may be electrically separated from the capacitive structure by a further insulating layer or a dielectric. The insulating layer may comprise a metal oxide of an adjacent metal surface. The insulating layer may be made of metal of the metal surface. In particular, the insulating layer can be made by oxidizing the metal surface. Thereby, the insulating layer can be produced inexpensively.

The sensor may comprise a further capacitive structure, which is arranged in a series circuit to the first capacitive structure and also influenced by the monolayer. The further capacitive structure may be designed to map a further capacitance of the further structure in a further electrical capacitance signal. In particular, the further capacitance signal may change opposite to the capacitance signal of the first capacitive structure as the concentration of the species changes. As a result, a difference between the capacitance signals can be evaluated as a sensor signal.

The approach presented here will be explained in more detail below with reference to the accompanying drawings. Show it:

1 is a cross-sectional view of a schematic sensor for detecting at least one chemical species according to an embodiment of the present invention;

FIG. 2 shows a representation of a self-organizing monolayer; FIG.

3 is an illustration of a transistor having a sensor according to an embodiment of the present invention;

Fig. 4 is an illustration of a transistor according to another

Embodiment of the present invention;

5 is an illustration of a buried gate transistor according to an embodiment of the present invention; 6 shows an illustration of a transistor with a further electrode according to an exemplary embodiment of the present invention;

7 is an illustration of a series connection of capacitors with a sensor according to an embodiment of the present invention; and

8 is a flowchart of a method of manufacturing a sensor according to an embodiment of the present invention.

In the following description of favorable embodiments of the present invention are for the in the various figures

represented and similar elements acting the same or similar

Reference numeral used, wherein a repeated description of these elements is omitted.

1 shows a cross-sectional view of a schematic sensor 100 for detecting at least one chemical species 102. The sensor 100 has a capacitive structure 104, an electrically insulating layer 106 (SAM) and a self-assembling monolayer 108. The capacitive structure 104 is adapted to a capacitance of the structure 104 in an electrical

Capacitance signal 110 map. The insulating layer 106 is disposed on the structure 104. The self-assembling monolayer 108 is disposed on the insulating layer 106. The monolayer 108 is constructed of molecules 112 connected at a first end 114 via a stable connection to the insulating layer 106 and formed at an opposite second end 116 for connection to the species 102.

The molecules 112 of the monolayer 108 have an electric dipole moment, which depends on the electron distribution in the molecule. When a molecule or atom of the chemical species 102 attaches to a second end 116 of a molecule 112 of the monolayer 108, the

Electron distribution and thus the dipole moment. The dipole moment directly affects the charge on the electrode and thus the capacitance of the capacitive structure 104. Since the insulating layer 106 has a very small thickness, in the range of a few nanometers, a distance between the monolayer 108 and the capacitive structure 104 is very small. The insulating layer 106 may be referred to as a dielectric 106. Also, the monolayer 108 is very thin due to its thickness defined by the length of the molecules 112. Together are the insulating layer

106 and the monolayer 108 less than ten nanometers thick. The presented here sensor 100 is thus much thinner than previously known

Superstructures. Thus, a change in the dipole moment of the monolayer 108 results in a very large change in the capacitance of the capacitive layer 104. This in turn results in a large change in the capacitance signal 110. The structure 100 presented here therefore knows about previously known structures due to the very small layer thicknesses of the insulation layer 106 and the monolayer 108 have a significantly increased sensitivity to the chemical species 102.

2 shows a representation of a self-organizing monolayer 108. The monolayer 108 substantially corresponds to the monolayer in FIG. 1. The monolayer 108 may be referred to as a self-assembling monolayer (SAM). As in FIG. 1, the monolayer 108 is part of a sensor 100 made of a capacitive structure 104 and an insulating layer 106. Here, only an external metallic layer is present

200 of the capacitive structure 104. The metallic layer 200 is here made of aluminum (AI). The insulating layer 106 here consists of oxidized aluminum, as of alumina (AIO _x ). The alumina 106 is formed by natural oxidation of the aluminum. To secure electrical isolation

ensure the aluminum of the metallic layer 200 can be converted into the alumina 106 by a controlled oxidation process.

In order to be able to adhere to the aluminum oxide 106, the molecules 112 of the monolayer 108 have at the first end 114 first molecule group A 202. At the second end 116, the molecules 112 of the monolayer 108 have a (reaction-active) group 204 tuned to the chemical species 102

or second molecule group B 204. In this

In the exemplary embodiment, the group 204 at the second end 116 of the molecules 112 is designed to connect to a further molecule group C, respectively. The two groups 202, 204 are above a Connection chain 206 connected to each other. Im here shown

In the exemplary embodiment, the two groups 202, 204 are connected to one another via an alkyl chain 206. The alkyl chain 206 connects the anchor group 202 and the reactive group 204. The molecules 112 form a dense turf of molecules 112, figuratively speaking. The molecules 112 are

not connected to each other. Since in each case only the anchor group 202 can connect to the insulating layer 106, the molecules 112 arrange themselves

independently in the order described here, when the insulating layer 106 is dipped or introduced into a fluid from the molecules 112. In this case, substantially the entire surface of the insulation layer 106 is covered by anchor groups 202.

If, as described in the exemplary embodiment illustrated here, a molecule or a substance C 102 forms a compound with the second end 116 or the group 204 of a molecule 112, this results in a new molecule 208 that has changed in relation to the molecule 112

Has dipole moment. This dipole moment directly influences the capacitance of the capacitive structure 104. FIG. 2 shows further details of the sensitive surface of the dielectric 106 and

SAM 108 and the associated physical mechanism. The surface of the sensor 100 is here exposed to the gaseous substance C 102. Group B 204 of SAM 108 is designed to react with substance C 102. As a result, the electric dipole moment along the stack 100 of dielectric 106 and SAM 108 and thus the charge distribution on the changes

Gate electrode 200 of the transistor 104, if the device or the transistor is incorporated in a suitable circuit.

The dielectric 106 on this structure 200 may be deposited extra or it may be a natural oxide layer 106 such as, for example

Copper or aluminum, which can then be amplified by an oxygen plasma treatment to a few nanometers.

The SAM 108 forms a closed monolayer on the structure 200 and is chemically designed such that the SAM 108 with the anchor group A 202 on the Oxid 106 and then only a specific gas molecule 102 or atom 102 can interact with the group B 204 of SAM 108. As a result of this interaction, the electric dipole moment of the stack 100 of SAM 108 and dielectric 106 changes, as a result of which the electrical charge on the structure 200 or electrode 200 changes. Depending on the technical

Embodiment is thereby changed, for example, the threshold voltage of a transistor or only the capacity of an evaluation circuit. From these changes, conclusions can be drawn on the gas concentration. The approach presented here can be easily integrated into existing semiconductor processes, since the use of plasmas and the deposition of metals are already known in manufacturing.

A very cost-effective extension of existing ASICs to gas-sensitive structures 100 is possible. Metals 200 are deposited very favorably.

Additional costs arise only through the specially synthesized SAM 108.

The approach presented here can also be used with standard CMOS processes, but it is also a flexible adaptation to newer ones

Semiconductor technologies such as organic semiconductors, oxide semiconductors (ZnO, IGZO), graphene, nanowires made of silicon, carbon nanotubes, MoS ₂ layers, for example.

The selectivity of the SAM 108 is almost infinitely adjustable by organic chemistry. The SAM 108 consists, for example, of an alkyl chain 112 having an anchor group A 202 and a group B 204. The anchor group A 202 is thereby adapted to the surface of the dielectric 106 in the process so that the SAM 108 can form stable bonds with the oxide 106. The group B 204 is set to the substance to be detected 102. For physical reasons, the plasma grown oxide 106 is only a few nanometers thick. The typical length of a SAM 108 is also a few nanometers, so that the total thickness of the stack 100 of dielectric 106 and SAM 108 is about four to six nanometers. This capacity is about 200 times larger than

Capacities with a one micron thick polymer between

Metal electrodes, with the same area. This can change capacity much better resolved and the sensitivity of the gas sensor can be increased. Alternatively, the active sensor area can also be reduced by a factor of 200, which, however, reduces the resolution.

The selectivity of the active sensor surface leads to a significantly reduced probability of failure due to, for example, corrosion or the like.

A SAM 108 can be applied either from a solution or from the gas phase. For example, the SAM 108 consists of an alkyl chain 206 with the groups A 202 and B 204 at the ends 114, 116. Only the group A 202 can interact with the oxide surface 106 so that a monolayer 108 inevitably forms and the process thereafter automatically stops. For surfaces of AlOx, armature groups 202 are typically used on side A, and for surfaces of Si0 _2, silane anchor groups 202 on side A are typically used. Group 204 on side B is specifically synthesized and adapted depending on the sensor requirement.

The gate electrode 200 of the transistor is either charged directly or a reference electrode, not shown here, is used to charge the gate 200 once.

3 shows an illustration of a transistor 300 with a sensor 100 according to an embodiment of the present invention. Here, the capacitive structure 104 includes a source contact 302, a drain contact 304

Semiconductor material 306 and a gate electrode 308 on. The gate electrode 308 is electrically isolated from the semiconductor material 306, the source contact 302, and the drain contact 304 by a dielectric 310. Between the source contact 302 and the drain contact 304, an electrical potential can be applied. In the semiconductor material 306 between the source contact 302 and the

Drain contact 304, a channel region 312 is formed. Charge carriers of the semiconductor material 306 located in the channel region 312 are movable. Depending on how strong an electric field emanating from the gate electrode 308 is over the dielectric, the electrical conductivity of the

Channel region 312 influenced by adding or removing charges. When the electrical potential is applied, the conductivity of the

Channel region 312 imaged in a current flow between the source contact 302 and the drain contact 304. The current flow serves as a measure of the charge on the gate electrode 308. With a suitable interconnection of the sensor 100, a charge can be "stored" on the gate electrode 308. For example, by another reference electrode (not shown) reacts the monolayer with a species, For example, the charge distribution on the gate electrode 308 may be affected, thereby changing the charge at the interface

Gate / Dielectric / channel and the current in channel 312 changes.

The gate electrode 308 is disposed adjacent to the insulating layer 106. Insulating layer 106 and monolayer 108 enclose gate electrode 308 on all exposed sides.

In other words, FIG. 3 shows a chemical sensor 300 having active structures 100 of self-assembled monolayers 108.

In contrast to physical parameters, such as temperature and

In the case of chemical parameters, in particular gases, acceleration is the sensor in direct contact with the medium. This results in significantly higher requirements in terms of resistance or corrosion to the sensors. Gas sensors can be based on a resistive principle, which results in a change in resistance due to deposits of gas atoms. This is realized, for example, with metal oxide semiconductors, organic phthalocyanine or conductive polymers. Other approaches include amperometric, potentiometric or thermal approaches. But because of the ease of measurement, capacitive measurements are far more interesting, especially with regard to simple miniaturization. In a conventional sensor, a polymer is sandwiched as a dielectric between two in a planar structure

Metal plates, wherein the upper metal plate is porous, so that a gas molecule and / or gas atom can diffuse through this layer and can change the capacity of the system. The capacity is determined by the area and the distance of the metal plates, ie a thickness of the polymer. Typical thicknesses are about 1 μηη. A self-assembling monolayer or SAM (self-assembled monolayer) can be used in combination with electronic components. For example, a specially synthesized SAM may be used in the field of organic electronics to terminate the surface of an oxide such as Si0 ₂ , ITO, or AlOx, ie, to bind the unsaturated OH groups while significantly increasing the dielectric breakdown strength. The SAM lowers surface energy and subsequent undisturbed growth of one, e.g. B. organic semiconductor allows. For example, an Al gate electrode may be disposed on a substrate. This is oxidized to affect the resulting

Alumina a SAM, here can attach an alkyl chain with anchor group. Other surfaces require different anchor groups. An organic semiconductor is deposited on the SAM and then the source and drain contacts of the transistor are structured.

The approach presented here introduces the use of a SAM 108 in transistors 300.

When using a SAM as a dielectric in transistors, the SAM is arranged between gate and semiconductor. These SAMs have only one special anchor group. Therefore, they do not react with other molecules / atoms after attachment.

By the approach presented here, various substances, in particular gases, such as C0 ₂ , NO can be detected by means of simple and already known transistor structures 104. In the approach presented here, a known electronic component 104, such as a transistor 300 comprising a gate 308, a dielectric 310, a semiconductor 306, a source 302 and a drain 304, is formed by at least one additional dielectric layer 106 and a SAM 108 having two anchor groups (English Self-assembeld monolayer), and depending on the variant, an additional metal electrode extended. These additional components are not used for the functionality of the transistor but are used for the detection of the substance / gas. By the approach presented here, a cost-effective integration of another capacitive structure 100 in a transistor 300 or an electrical circuit can be presented. This further capacitive structure 100 consists of an electrically conductive structure, a dielectric 106 and a SAM 108.

Depending on the embodiment of a transistor 300, this structure is already present as part of the transistor 300, it is additionally applied.

In one embodiment, the transistor 300 is implemented in CMOS technology. In this case, an oxide 106 and a SAM 108 are additionally patterned on the gate electrode 308. The surface of the SAM 108 is open to the medium 102, for example a gas 102.

The approach presented here is not limited to CMOS technology, but can also be easily integrated with alternative transistor technologies, such as thin-film transistors. This type of transistor does not require a silicon wafer as substrate, but can be structured on almost any surface. Only one conductive electrode is needed as the gate 308, an insulator 310, a semiconductor 306, for example an organic semiconductor, graphene, MoS2, IGZO or ZnO and further conductive contacts as source contact 302 and drain contact 304

Order of the individual layers can be varied. Gate 308, source 302 and drain 304 are typically made of a metal such as Al, Cu, Au or Ag.

4 shows an illustration of a transistor 300 according to another embodiment of the present invention. The transistor 300 is not implemented as a CMOS process, but in thin-film technology. In this case, the source contact 302 and the drain contact 304 are on a substrate 500

arranged. The substrate 500 may be, for example, glass or a foil.

Between the source contact 302 and the drain contact 304 is a

Gap for the channel region 312. In the gap and above the source contact 302 and the drain contact 304, the semiconductor material 306 has been deposited. On the semiconductor material 306, in turn, the dielectric 310 is arranged. On the dielectric 310 is as in the figure 3 the Gate electrode 308 arranged. The gate electrode is enclosed on all exposed sides by the insulating layer 106 and the monolayer 108. The insulating layer 106 and the monolayer 108 form the sensor 100 with the capacitive structure 104.

FIG. 4 shows further transistor forms in thin-film technology. In these cases, the transistor gate electrode 308 is over the semiconductor 306, similar to the CMOS structure in Figure 3. Here, no additional electrode is needed. Only one dielectric 106 and the SAM 108 supplements the

Transistor structure 104. The detection of the substance C is now analogous to the CMOS transistor in which a change in the conductivity of the semiconductor 306 is detected. 5 shows a transistor 300 in top-gate, bottom-contact design, but it is also an execution as a top-gate, top-contact possible (not shown).

FIG. 5 shows an illustration of a transistor 300 with a buried one

Gate electrode 308 according to an embodiment of the present invention

Invention. As in FIG. 3, the transistor 300 has a source contact 302, a drain contact 304, a semiconductor material 306, a gate electrode 308 and a dielectric 310. Here, the semiconductor material 306 is disposed adjacent to the insulating layer 106. As in FIG. 4, the transistor 300 is implemented using thin-film technology. Here, the gate electrode 308 is disposed directly on the substrate 500. The gate electrode 308 is enclosed by the dielectric 310 and electrically isolated from the semiconductor material 306. The semiconductor material 306 has a planar surface on which the source contact 302 and the drain contact 304 are disposed. Of the

Source contact 302 under drain contact 304, as well as that between the

Source contact 302 and the drain contact 304 exposed semiconductor material 306 are covered by the insulating layer 106. The monolayer 108 is on the

Insulating layer 106 is arranged.

In one embodiment, the monolayer 108 is thicker in the region between the source contact 302 and the drain contact 304 than above

Source contact 302 and the drain contact 304. In FIG. 5, the dielectric 106 and the SAM 108 are patterned directly on the semiconductor 306. As a result, the change in the dipole moment acts directly on the semiconductor 306 of the transistor 306. Depending on the change, the charge in the channel 312 is increased or decreased, so that the current in the transistor 302 changes. In this design, it is advantageous if the semiconductor 306 is very thin. Much less than 20 nm are good. In one embodiment, the semiconductor 306 is implemented as a nanowire. Likewise, the semiconductor 306 may be implemented as CNT or a 2D material, such as graphene. Thus, a significant influence is exerted on the "transistor channel" 312 at the interface between the dielectric 310 and the semiconductor 306.

In this case, the dielectric 106 and the SAM 108 were applied directly to the semiconductor 306.

FIG. 6 shows an illustration of a transistor 300 with a further electrode 800 according to an embodiment of the present invention. Of the

Transistor 300 essentially corresponds to the transistor in FIG

In contrast, in the region between the source contact 302 and the drain contact 304, the further electrode 800 is arranged. Thus, the further electrode 800 is disposed between the insulating layer 106 and the capacitive structure 104. The further electrode 800 is electrically insulated by another dielectric 802 from the source contact 302, the semiconductor material 306 and the drain contact 304. The further electrode 800 is connected via the source contact 302 and the drain contact 304. The insulating layer 106 of the sensor 100 presented here completely encloses the further electrode 800 together with the monolayer 108. The further electrode 800 is designed to influence the capacitance of the capacitive structure 104.

FIG. 6 shows a thin-film transistor 300 in the bottom-gate, top-contact variant. That is, the gate electrode 308 is on one

Carrier substrate 500 and the source / drain contacts 302, 304 are located on the semiconductor 306. If now additionally a further dielectric 802 and a further electrode 800 are deposited on the semiconductor 306, it is a transistor 300 in a double-gate structure , in which through the upper Electrode 800 can selectively affect the threshold voltage of the transistor 300.

In the approach presented here, a dielectric 106 and a SAM 108 are additionally deposited on this further electrode 800. When this electronic component of the transistor 300 with double-gate and dielectric 106 and SAM 108 is exposed to the substance C, it comes with a suitable nature of the SAM 108 to a reaction, whereby the electrical dipole moment of the SAM 108 is changed, as shown in FIG 2. In this embodiment, the threshold voltage of the transistor 300 is now changed and conclusions about the concentration of the substance C can be drawn.

In other words, Fig. 6 shows a transistor 300 in thin-film technology consisting of any substrate 500, a gate electrode 308, a

Semiconductor 306, a source contact 302, and a drain contact 304.

In addition, a dielectric 802 is applied to the contacts 302, 304 and the semiconductor 306 for electrical isolation. Furthermore, an additional electrode 800 is applied to the dielectric 802. This further electrode 800 is coated with an oxide 106 and a Sam 108.

Alternatively, a version as a bottom-gate, bottom-contact variant would be conceivable, which is not shown here. 7 shows a representation of a series circuit 1000 of capacitances 1002,

1004 with a sensor 100 according to an embodiment of the present invention. The first capacitance 1002 may be referred to as the first capacitive structure 104. The second capacitance 1004 may be referred to as a second capacitive structure. The two capacitors 1002, 1004 are arranged side by side. The capacities 1002, 1004 consist of three

Electrodes 1006, 1008, 1010. The first electrode 1006 and the second electrode 1008 form the first capacitance 1002. The second electrode 1008 and the third electrode 1010 constitute the second capacitance 1004. The capacitances 1002, 1004 are thus connected in series with one another. The electrodes 1006, 1008, 1010 are each electrically insulated from each other by an insulating layer 310 isolated. The series circuit 1000 is arranged on a substrate 500. The substrate 500 is passivated. The first electrode 1006, the second electrode 1008, and the third electrode 1010 are disposed directly on the substrate 500. The second electrode 1008 has a recess for the first electrode 1006 and the third electrode 1010, respectively. The second electrode 1008 is completely enclosed by the insulating layer 106. On the insulating layer 106, the monolayer 108 is arranged and thus forms the sensor 100. A change in the dipole moment at the monolayer 108 affects the first capacitance 1002 and the second capacitance 1004.

In operation, the first electrode 1006 is set to a voltage potential, thereby accumulating a charge Q + at the interface to the electrode / dielectric 310. The third electrode 1010 is set at an opposite voltage potential, thereby enriching a charge Q- at the interface Electrode 010 / Dielectric 310. On the second electrode

1008 in the region of the first capacitance 1002, a charge I Q- will set. Due to the negative charge Q- at the third electrode 1010, the second electrode 1008 in the region of the second capacitance 1004 has a positive charge Q +. In the second electrode 1008, therefore, a charge separation takes place. When molecules of the species to be sensed come into contact with the monolayer 108, the capacitances of the first capacitance 1002 and the second capacitance 1004 are influenced by the change in the dipole moment in the monolayer 108. This influence can be detected by a first voltage signal of the first capacitor 1002 and / or a second voltage signal of the second capacitor 1004. In general, the signs of charge could also be reversed.

In Fig. 7 is a simplified embodiment based on two

Plate capacitors 1002, 1004 in a series circuit 1000 described. This assembly consists of a total of three electrodes 1006, 1008, 1010, wherein the first electrodes 1006 and the third electrode 1010 are electrically isolated from the upper electrode 1008 by any dielectric 310. The third electrode 1008 is terminated to the fabric C with a thin dielectric 106 and a SAM 108. As in previous ones

Embodiments described, it comes in a reaction of the substance C. with the SAM 108 to a change of the dipole moment at the stack 100 of the SAM 108 and the dielectric 106. As a result, a portion of the electrical charge from the interfaces to the first electrode 1006 and the third

Electrode 1010 "deducted", so that the charge on the first electrode 1006 and the third electrode 1010 changes. This capacity change can be measured and gives an indication of the concentration of the substance C.

In other words, FIG. 7 shows a series circuit 1000 of several capacitances 1002, 1004. The variable dipole moment "over" the second one

Electrode 1008 affects the stored charge on first electrode 1006 and third electrode 1010.

8 shows a flowchart of a method 1100 for producing a sensor according to an embodiment of the present invention. The

Method 1100 includes providing step 1102, forming step 1104, and attaching step 1106. In step 1102 of providing, a capacitive structure is provided. The capacitive structure is adapted to a capacitance of the structure in an electrical

Map capacity signal. In step 1104 of forming, an electrically insulating insulating layer is formed on the structure. In step 1106 of annealing, molecules are attached to the insulating layer to form a

form self-organizing monolayer. The molecules are submerged

Use of a fluid 1108 attached to form the self-assembling monolayer. The molecules form a stable connection with the insulating layer at a first end. At an opposite second end, the molecules are configured to associate with at least one species. The approach presented here can be obtained by grinding in combination with Focused Ion

Beam installations or high-resolution cuts and EDX or

Auger spectroscopy to determine the chemical composition of the SAM can be detected. The approach presented here can be at all

Sensors in the field of gas detection, such as C02 or NO are used. The embodiments described and shown in the figures are chosen only by way of example. Different embodiments may be combined together or in relation to individual features. Also, an embodiment can be supplemented by features of another embodiment.

Furthermore, the method steps presented here can be repeated as well as executed in a sequence other than that described.

If an exemplary embodiment comprises an "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

Claims

claims

A sensor (100) for detecting at least one chemical species (102), the sensor (100) comprising: a capacitive structure (104) adapted to receive a capacitance of the structure (104) in an electrical capacitance signal (110); an electrically insulating insulating layer (106) disposed on the structure (104); and a self-assembling monolayer (108) disposed on the insulating layer (106), wherein the monolayer (108) is constructed of molecules (112) attached to a first end (114) by a stable connection to the insulating layer (106). are connected and formed at an opposite second end (116) to connect to the species (102).

The sensor (100) of claim 1, wherein the capacitive structure (104) includes a source contact (302), a drain contact (304)

Semiconductor material (306) and a gate electrode (308), wherein the capacitance signal (110) represents a current flow between the source contact (302) and the drain contact (304).

The sensor (100) of claim 2, wherein the gate electrode (308) is disposed adjacent to the insulating layer (106).

The sensor (100) of claim 2, wherein the semiconductor material (306) is disposed adjacent to the insulating layer (106). Sensor (100) according to one of the preceding claims, comprising an electrode (800) for influencing the capacitance of the capacitive structure (104).

A sensor (100) according to claim 5, wherein the electrode (800) is disposed between the insulating layer (106) and the capacitive structure (104).

A sensor (100) according to any one of the preceding claims, wherein the insulating layer (106) is a metal oxide of an adjacent one

Metal surface (200) includes.

A sensor (100) according to any one of the preceding claims, wherein the insulating layer (106) comprises a dielectric (106).

Sensor (100) having a further capacitive structure (1004) which is arranged in a series circuit to the capacitive structure (104, 1002) and influenced by the monolayer (108), wherein the further capacitive structure (1004) is adapted to a further capacity of the further structure (1004) in a further electrical

Map capacity signal.

A method (1100) of manufacturing a sensor (100) according to any one of the preceding claims, wherein the method (1100) comprises the steps of:

Providing (1102) a capacitive structure (104) thereto

is configured to map a capacitance of the structure (104) in an electrical capacitance signal (110);

Forming (1104) an electrically insulating insulating layer (106) on the structure (104); and

Attaching (1106) molecules (112) to the insulating layer (106) to form a self-assembling monolayer (108), the molecules (112) being stabilized at a first end (114) Connection to the insulating layer (106) are connected and at an opposite second end (116) are adapted to connect to at least one species (102).