DE102008002157A1 - Sensor element to spectroscopically measure infrared radiation, comprises substrate, membrane formed on substrate upper side, cavity formed below the membrane in the substrate, thermopile structure, filtering device, and thermopile cells - Google Patents

Abstract

The sensor element comprises a substrate (1), a membrane formed on an upper side of the substrate, a cavity formed below the membrane in the substrate, a thermopile structure with lateral thermopile pairs, which have a first thermal shank made of a first semiconductor material and a second thermal shank made of a second semiconductor material, a filtering device provided for wavelength selective transmission of the infrared radiation over an adhesive layer on the membrane, and thermopile cells. Seebeck coefficients of the semiconductor materials are different. The sensor element comprises a substrate (1), a membrane formed on an upper side of the substrate, a cavity formed below the membrane in the substrate, a thermopile structure with lateral thermopile pairs, which have a first thermal shank made of a first semiconductor material and a second thermal shank made of a second semiconductor material, a filtering device provided for wavelength selective transmission of the infrared radiation over an adhesive layer on the membrane, and thermopile cells. Seebeck coefficients of the semiconductor materials are different. The first and second semiconductor materials have dopings of the same type of charge carrier (p, n). The first and second thermal shanks are directly contacted with one another in a contact surface. Both of the thermal shanks are p-doped or n-doped. A first insulating intermediate layer (2) covers the substrate outside of the cavity and extends itself over the cavity. A second insulating intermediate layer (4) is formed on a first semiconductor layer (3) of the first thermal shank, and a second semiconductor layer of the second thermal shank is formed on the second insulating intermediate layer. A contact opening (5), in which the contact surface is formed between the thermal shanks, is formed in the second insulating intermediate layer. The first thermal shank is structured in the first semiconductor layer. The second insulating intermediate layer covers the first insulating intermediate layer and the structured first semiconductor layer. The second semiconductor layer, in which the second thermal shank is formed, is applied on the second insulating intermediate layer. The second thermal shank is contacted with the first thermal shank over the contact surface formed in the contact opening. A third insulating intermediate layer covers the second semiconductor layer. An absorber layer is applied and structured on the third insulating intermediate layer for absorbing the incident infrared radiation. A structured metal layer is applied for contacting the first and/or the second semiconductor layers. The lateral thermopile pairs are arranged next to each other or on the membrane, where each thermopile pair is formed from the first thermal shank and the second thermal shank over the first thermal shank and contacted with the first thermal shank. The thermopile pairs are separated by trenches, which are formed in the membrane and subsequently filled with a closing layer. Access holes are formed in some trenches for etching the cavity below the membrane. A cap substrate is fastened in vacuum-tight connections on the coated and the structured substrate. A further cavity is formed in the cap substrate, so that the membrane is arranged between the cavity of the cap substrate and the cavity formed in the substrate. One of the semiconductor materials is lowly doped and the other semiconductor material is highly doped. The combination of the both semiconductor materials of the both semiconductor layers is obtained from n-silicon and n +>-silicon, p-silicon and p +>-silicon, n-germanium and n +>-germanium and n-silicon and n +>-silicon-germanium. Each of the thermopile cells has the cavity formed in the substrate and the membrane formed above the cavity with thermopile pairs. The thermopile cells are laterally formed next to each other and are mutually contacted. An independent claim is included for a method for producing a sensor element.

Description

State of the art

The The invention relates to a sensor element for measuring infrared radiation, in particular as an IR sensor or spectroscopic sensor or as Part of an infrared sensor or spectroscopic sensor used and a method for its production.

Micromechanical Sensor elements for the detection of infrared (IR) radiation are in particular used in infrared cameras as well as in spectroscopic sensors. Such spectroscopic sensors are used in particular for detection a gas concentration, z. B. of carbon dioxide, in the ambient air, where complementary optical filters for the selection of a relevant Wavelength range can be used.

The Micromechanical sensors can be used in particular as thermopile sensors be formed, the at least one thermopile pair of two interconnected thermo legs made of materials with different Seebeck coefficients have. The hot contact point the thermo leg is facing the thermal insulation the further substrate material is generally formed on a membrane and is heated by incident IR radiation, e.g. B. by an applied on the membrane absorber material, for. B. one Ru-containing resistor paste, leaving out of the heat forming electrical voltage on the intensity of the incident IR radiation can be closed.

When Material systems or material pairs of the Thermopile sensors in particular silicon and aluminum, or p-silicon and n-silicon as well as other material systems used. The one for the sensitivity the thermopile sensors relevant Seebeck coefficient S results as the difference of the Seebeck coefficients of materials S1 and S2 the two thermo legs. Typical values for thermopile pairs (Thermocouples) made of silicon and aluminum are at S = -280.3 μV / K. Although aluminum allows a good electrical contact to the second thermal partner silicon, it causes due to its high thermal conductivity but also a heat dissipation from the membrane and thus a reduction of the membrane temperature in the area of hot thermal contacts. Furthermore are due the relatively low melting temperature of aluminum of 660 ° C the processes following the application of the aluminum layer limited to lower process temperatures. Also results when used in a CMOS process technology due to possible Cross-contamination is a limitation of the following Process steps.

typical Values of thermopile pairs of p-type silicon and n-type silicon are in the range of S = -360 μV / K. The disadvantage with this material pairing is the formation of space charge zones at direct contacting of the differently doped silicon regions corresponding to bipolar pn diodes. In a series connection of thermo legs to increase the measurement signal comes it thus forcibly leads to a series connection of pn-diodes, always are alternately switched in the forward and reverse direction and thus have a high internal resistance. Therefore, the two thermo legs generally via a metallization level as auxiliary level electrically contacted, so that in turn an additional Metallization layer with the appropriate effort and the disadvantages mentioned is required during processing.

The formation of the membrane can be done differently and is z. In Review of micromachined thermopiles for infrared detection, Graf, Arndt, Sauer, Gerlach 2007, Meas. Sci. Technol. Forthcoming article June 2007 in particular volume micromechanical or surface micromechanical production methods can be used.

Disclosure of the invention

Of the Invention is based on the idea, the thermopile sensor under Use of two semiconductor materials with a doping of same charge carrier type and different concentration form the doping, the two thermo legs directly be contacted with each other. Under a load carrier type According to the invention, the type or the sign understood the doping, d. H. p-doping or n-doping.

The Thermopile pairs (thermocouples) can be produced in particular by stacking the two semiconductor layers of the thermo legs or be formed at least partially overlapping with an insulating intermediate layer, which at contact points or Contact surfaces is open. This becomes process-technically advantageously realized by first the first Semiconductor layer is deposited, voteilhafterweise on one formed on the substrate first insulating intermediate layer, Subsequently, a second insulating intermediate layer on the structured Semiconductor layer formed and patterned with the contact openings and subsequently depositing the second semiconductor layer becomes.

The structuring of the semiconductor and insulating layers may in this case take place in such a way that a series connection of a plurality of thermopile pairs is formed. This allows high Seebeck coefficients, z. B. about 200 μV / K, and achieve correspondingly high thermoelectric voltages.

By doing according to the invention neither for the formation of the thermo leg even still used for their contacting a metal layer is, in particular, therefore not aluminum or another low Melting metal, enter the process mentioned above Disadvantages of the restriction to low process temperatures and a possible cross-contamination not on. As according to the invention semiconductor materials used with a doping of the same charge carrier type become, thus also the education of pn transitions avoided. Thus, the series connection of several pairs Thermopile to achieve a high signal unproblematic.

According to the invention also the absorber material can be applied in a manner that is not accessible to metallized substrates, z. B. in epitaxy systems.

The Forming the cavern below the membrane can be particularly surface micromechanical through the insulating intermediate layers and semiconductor layers through, d. H. under formation of access openings or Ätzzugängen through the semiconductor layers and insulating layers to the bulk material of the substrate, to etch the cavern. These access openings can also be used according to the invention as access trenches for the lateral structuring or separation of the individual pairs of thermopile be used.

According to the invention the completion of the thermopile measuring structure upwards for a through Wafer bonding done with a suitable cap substrate. alternative However, for this purpose, a suitable layer above the measuring structure or Thermopile structure are formed, although less thermal insulation of the thermopile structure reaches the top is the time-consuming and costly step of manufacturing and However, the Aufbondens the additional cap wafer omitted can.

The Production according to the invention of the thermopile structures is inexpensive and allows a high packing density, whereby also several Thermopile cells from in each case a multiplicity combined by Thermopile pairs and contacted together.

Brief description of the drawings

It demonstrate:

1 to 13 Process steps for producing a sensor according to the invention according to different embodiments:

1 to 3 Process steps for producing a sensor according to a first embodiment with cap chip;

4 one of 2 outgoing process variant for the production of a sensor with thin-film cap;

5 to 12 another process variant with starting point in 1 for producing a sensor with a thin-film cap;

13 a capped sensor according to one embodiment;

14 a plan view of a sensor according to the invention with a plurality of pairs Thermopile according to an embodiment;

15 the arrangement of several thermopile cells according to an embodiment in a plan view.

Description of the embodiments

For the production of the sensor element according to the invention is according to 1 on a substrate 1 from z. B. doped silicon, a first insulating intermediate view 2 deposited. The first intermediate layer 2 can a single layer, for. B. SiO2 layer, or even a layer stack, z. B. of oxide / nitride / oxide, in particular silicon oxide / silicon nitride / silicon oxide. On the first intermediate layer 2 becomes a first semiconductor layer 3 from a first semiconductor material with Seebeck coefficients S1, preferably of silicon first doping, deposited and structured to form the first thermo leg. In this case, a plurality of regions separated from each other by free spaces are formed in the first semiconductor layer 3a educated. This structuring as well as the subsequent structuring are carried out by the usual process engineering means such as masking, etching, etc.

On the structured semiconductor layer 3 subsequently becomes an insulating second intermediate layer 4 , in particular an oxide, for. As SiO 2, deposited and structured such that in the second intermediate layer 4 above each area 3a at least one first contact opening 5 is trained.

The following is according to 2 a second semiconductor layer 6 from a second semiconductor material with Seebeck coefficients 82 on the second intermediate layer 4 isolated and structured. In this case, the second semiconductor layer fills 6 also the first contact openings 5 and contacts the first semiconductor layer 3 in contact areas 37 ; Advantageously, in the second semiconductor layer 6 again laterally separated areas 6a designed so that each one area 6a with an underlying area 5a as a thermopile pair 32 is formed, in particular, a series connection of a plurality of thermopile pairs 32 can be formed.

The semiconductor materials of the first semiconductor layer 3 and the second semiconductor layer 6 have different Seebeck coefficients S1 and S2 and are doped with the same doping or the same charge carrier type, ie both p-doped or n-doped, but with different carrier concentration.

The following is according to 3 a third insulating intermediate layer 7 , preferably as an oxide, for. B. SiO2 deposited, thus the structured second semiconductor layer 6 and the exposed portions of the second insulating interlayer 4 covered. The following is an auxiliary layer 8th deposited as an absorber layer and structured such that they are in a central region above the thermopile pairs 32 is trained. The auxiliary layer 8th may be a single layer or even a layer stack of several intermediate layers. Due to the method according to the invention can, for. As well as a highly doped epitaxial silicon layer as an auxiliary layer 8th be used. The insulating intermediate layers 4 and 7 are structured in such a way that laterally outside a contacting region 3c the first semiconductor layer 3 , If necessary, also a corresponding region of the second semiconductor layer 6 , is exposed, on which subsequently a first metallization 10 is deposited as a bond pad metallization for contacting and structured.

In lateral middle part becomes according to 3 in the substrate 1 a cavern 9 below the absorber material 8th formed so that above the cavern 9 the intermediate layers 2 . 4 and 7 and semiconductor layers 3 . 6 as well as the absorber 8th a membrane 33 form the free-bearing and thus bulk material of the substrate 1 thermally largely isolated. The cavern 9 In this case, it can be formed in a manner known per se, ie, as described above, volume micromechanical (bulky micromechanical) or surface micromechanical.

The following is a cap substrate 12 or cap chip, in which by etching, z. B. KOH etching, from one side a cavern 12a is formed on the top of the substrate 1 , ie z. B. on the third intermediate layer 7 , by means of vacuum-tight seal glass intermediate layers 11 attached, leaving the membrane 33 together with the absorber 8th between the caverns 9 and 12a arranged.

The cap chip 12 is transparent in the relevant spectral range of the IR radiation to be detected; the absorber material of the absorber layer 8th absorbs incident IR radiation and heats up and the entire membrane 33 corresponding. Thus shows 3 a sensor element 35 on which, if appropriate, a wavelength-selective filter is to be attached.

4 shows a process variant of an embodiment with starting point in 2 , This is from 2 starting from the insulating third intermediate layer 7 deposited and structured such that at least one second contact opening 13 or several contact openings 13 in the third intermediate layer 7 be formed. The following is on the third intermediate layer 7 a third semiconductor layer 14 deposited in the contact opening 13 the second semiconductor layer 6 contacted. The third semiconductor layer 14 In particular, it may be epitaxially deposited silicon. Thereafter, the production of z. B. thin-film caps by further processing possible.

5 shows one too 4 alternative process variant with starting point in 1 , Here, the second semiconductor layer becomes 6 applied, preferably as epitaxial silicon. The following is according to 6 the third intermediate layer 7 , preferably as an oxide, applied and structured such that a first trench opening 15 and a second trench opening 16 be formed; the second trench openings 16 are wider here than the first trench openings 15 ,

The following is according to 7 the second semiconductor layer 6 using the third intermediate layer 7 structured as an etching mask. In particular, plasma etching or another etching method that allows the formation of substantially vertical trenches can be used here. According to 7 become the trench openings 15 and 16 vertically down through the second semiconductor layer 6 to the second intermediate layer 4 educated.

According to 8th subsequently becomes an auxiliary layer 29 as passivation on the walls of the trench openings 15 and 16 educated. The formation of this auxiliary layer 29 can in particular by thermal oxidation of the silicon material of the second semiconductor layer 6 , Or by Aufbrin conditions of a PECVD oxide layer done. (Plasma enhanced chemical vapor deposition oxide layer) This makes the narrower first trench openings 15 filled and on the walls of the wider second trench openings 16 formed a sidewall protection.

According to 9 subsequently perforation openings 17 at the bottom of the trench openings 16 formed by the insulating intermediate layers 4 and 2 into the bulk material of the substrate 1 run. This is done by a directional etching step for etching oxide, e.g. B. by a plasma etching process.

The following is according to 10 the trench opening 16 as access to the etching of the cavern 18 in the substrate 1 used. This etching process can be achieved in particular by a silicon-selectively etching gas, for. B. by CIF3 etching. The intermediate layer 2 and the auxiliary layer 29 serve as protection of non-corrosive structures.

According to 11 subsequently the second trench openings 16 by applying a sealing layer 19 , preferably a PECVD oxide layer 19 , locked. This results in a hermetically sealed packaging of the membrane produced 34 in the cavern 18 ,

According to 12 subsequently become the third intermediate layer 7 and the sealing layer 19 structured and thereby the second contact opening 13 formed on the metallization layer 10 is precipitated with appropriate structuring, which serves as an optical reflector and as an electrical contact layer for bond pads.

Subsequently, in this embodiment, directly an optical filter 21 with a suitable transparent in the IR range and having a suitable refractive index adhesive 20 be adhered, the filter 21 in a manner known per se allows a wavelength-selective transmission of IR radiation. 12 thus shows a sensor element 36 with thin-film cap and without the use of a cap chip

13 shows another process variant with starting point in 11 , From 11 starting from the first layer of the closure 19 and the underlying third intermediate layer 7 structured in such a way that in turn - accordingly 12 - second contact openings 13 be formed, whereupon a metallization layer 10 As an optical reflector and electrical contact layer is deposited and patterned, so that bond pads 22 , The following is the cap substrate 12 or cap chip bonded, z. B. again by means of seal glass compounds, where appropriate 3 the cavern 12a is formed above the measuring structure, so that a self-supporting membrane 33a results. On the top of the cap chip 12 becomes the optical filter 21 with an optically suitable adhesive 20 attached.

The sensor element 37 of the 13 with the cap substrate 12 allows a better thermal insulation than the sensor element 35 out 12 in which the directly on top of the membrane 34 large area mounted optical filters 21 contributes to the lateral heat conduction. Because in 12 however, the additional formation of the cap substrate 12 and the additional process step of attaching the cap substrate 12 omitted, the sensor element 36 out 12 be made cheaper.

14 shows a plan view of a portion of the sensor designs of the second and third embodiment, wherein the features are only partially drawn for clarity. Lateral outside are already the bond pads 22 educated. The perforation holes 25 correspond to the trench openings 16 and serve the formation of the cavern 18 , where in 14 the etching front 24 in the silicon material of the substrate 1 after the CIF3 etching is drawn. It can thus in this training, a cruciform cavern 18 be formed from above the absorber area 23 is provided. The individual thermo legs 26 thus extend laterally from the edge above the cavern 18 to the middle region of the membrane on which the absorber 23 is provided. By rice circuit a variety of thermal legs 26 Thus, a high measurement signal can be achieved. The areas 27 represent heat sinks.

In 15 is accordingly the formation of several thermopile cells 30 with intermediate webs 28 as stabilizing elements in the substrate 1 shown; 15 is here in particular for the training form according to process variant 2 , ie according to 4 to 12 , relevant.

According to the invention thus direct contact surfaces 37 between the two thermo legs or the semiconductor regions of the first semiconductor layer 3 and the second semiconductor layer 6 be formed.

The semiconductor materials of the first semiconductor layer 3 and second semiconductor layer 6 are doped with the same doping or the same charge carrier type, ie both p-doped or n-doped, with different carrier concentration. Advantageous combinations are in particular n-silicon and n ⁺ -silicon, or p-silicon and p ⁺ -silicon, n-germanium and n ⁺ -germanium, ie a semiconductor material with a simple doping in a semiconductor layer and a correspondingly highly doped semiconductor material in the other semiconductor layer. Furthermore, however, combinations such. As n-silicon and n ⁺ -SiGe advantageous.

Although the Seebeck coefficients S1 and S2 of the two semiconductor materials initially do not differ as much as in conventional combinations, ie the difference is relatively small; OF INVENTION However, according to the direct contacting, a large number of thermopile pairs can be formed so that overall high Seebeck coefficients S of z. B. 200 μv / K can be produced.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - Review of micromachined thermopiles for infrared detection, Graf, Arndt, Sauer, Gerlach 2007, Meas. Sci. Technol. Forthcoming article June 2007 [0006]

Claims (22)

Sensor element for measuring infrared radiation, in particular for spectroscopic measurements, wherein the sensor element ( 35 . 36 . 37 ) at least: a substrate ( 1 ), one on top of the substrate ( 1 ) formed membrane ( 33 . 33a . 34 ) and one below the membrane ( 33 . 33a . 34 ) in the substrate ( 1 ) trained cavern ( 9 . 18 ), a thermopile structure ( 30 . 32 ) with at least one thermopile pair ( 32 ), which has a first thermo leg ( 3a . 26 ) of a first semiconductor material and a second thermo leg ( 6a . 26 ) of a second semiconductor material, wherein the Seebeck coefficients (S1, S2) of the first semiconductor material and the second semiconductor material are different, characterized in that the first semiconductor material of the first thermo leg ( 3a ) and the second semiconductor material of the second thermo leg ( 6a ) Have dopants of the same charge carrier type (p, n), and the first thermo leg ( 3a ) and the second thermo leg ( 6a ) of a thermopile pair ( 32 ) directly in at least one contact surface ( 37 ) are contacted with each other. Sensor element according to claim 1, characterized in that the two thermo legs ( 3a . 6a ) of a thermopile pair ( 32 ) are either both p-doped or both are n-doped. Sensor element according to claim 1 or 2, characterized in that on a first semiconductor layer ( 3 ) of the first thermo leg ( 3a ) an insulating intermediate layer ( 4 ), and on the insulating intermediate layer ( 4 ) a second semiconductor layer ( 6 ) of the second thermo leg ( 6a ) is formed, wherein in the insulating intermediate layer ( 4 ) at least one contact opening ( 5 ) is formed, in which the at least one contact surface ( 37 ) between the first thermo leg ( 3a ) and the second thermo leg ( 6a ) is trained. Sensor element according to claim 3, characterized in that the membrane comprises: a first insulating intermediate layer ( 2 ), which is the substrate ( 1 ) outside the cavern ( 9 . 18 ) and over the cavern ( 9 . 18 ), a first semiconductor layer ( 3 ), in which the first thermo legs ( 3a ), an insulating second intermediate layer ( 4 ), which is the first insulating intermediate layer ( 2 ) and the structured first semiconductor layer ( 3 ) and in the contact openings ( 5 ), one on the second insulating intermediate layer ( 4 ) applied second semiconductor layer ( 6 ), in which the second thermo leg ( 6a ) are formed, wherein the second thermal leg over in the contact openings ( 5 ) formed contact surfaces ( 37 ) with the first thermo legs ( 3a ), and an insulating third intermediate layer ( 7 ), which the second semiconductor layer ( 6 ) covered. Sensor element according to claim 4, characterized in that on the third intermediate layer ( 7 ) an absorber layer ( 8th ) is applied and structured to absorb the incident IR radiation. Sensor element according to claim 4 or 5, characterized in that a structured metal layer ( 10 ) for contacting the first and / or second semiconductor layer ( 3 . 6 ) is applied. Sensor element according to one of the preceding claims, characterized in that the thermopile structure ( 30 . 32 ) several lateral side by side in or on the membrane ( 33 . 33a . 34 ) arranged thermopile pairs ( 32 ), each thermopile pair ( 32 ) from a first thermo leg ( 3a ) and one above the first thermo leg ( 3a ) and contacted with this second thermo leg ( 6a ) is trained. Sensor element according to claim 7, characterized in that the laterally adjacent thermopile pairs ( 32 ) through in the membrane ( 33 . 33a . 34 ) and subsequently with a sealing layer ( 19 ) filled trenches ( 15 . 16 ) are separated. Sensor element according to claim 8, characterized in that at least in some trenches ( 16 ) Access holes ( 25 ) for etching the cavern ( 9 . 18 ) below the membrane ( 33 . 33a . 34 ) are formed. Sensor element according to one of the preceding claims, characterized in that on the coated and structured substrate ( 1 ) a cap substrate ( 12 ) in vacuum-tight joints ( 11 ), wherein in the cap substrate ( 12 ) a cavern ( 12a ) is designed such that the membrane ( 33 . 33a ) between the cavern ( 12a ) of the cap substrate ( 12 ) and in the substrate ( 1 ) cavern ( 9 . 18 ) is arranged. Sensor element according to one of claims 1 to 9, characterized in that a filter device ( 21 ) for the wavelength-selective transmission of the IR radiation via an adhesive layer ( 20 ) on the membrane ( 34 ) is attached. Sensor element according to one of the preceding claims, characterized in that one of both semiconductor materials are low doped and the other of the two semiconductor materials is heavily doped. Sensor element according to one of the preceding claims, characterized in that the combination of the two semiconductor materials of the two semiconductor layers ( 3 . 6 ) is taken from the following group: n-type silicon and n ⁺ type silicon, p-type silicon and p ⁺ type silicon, n-germanium and n ⁺ type germanium, n-type silicon and n ⁺ -SiGe. Sensor element according to one of the preceding claims, characterized in that it comprises a plurality of thermopile cells ( 30 ), each thermopile cell ( 30 ) one each in the substrate ( 1 ) trained cavern ( 9 . 18 ) and a membrane formed above the cavern ( 33 . 33a . 34 ) with several thermopile pairs ( 32 ), wherein the thermopile cells ( 30 ) are laterally formed side by side and contacted together. Method for producing a sensor element, comprising at least the following steps: applying or forming at least one first insulating intermediate layer ( 2 ) on a substrate ( 1 ), Applying and structuring a first semiconductor layer ( 3 ) of a first semiconductor material on the at least one insulating intermediate layer ( 2 ), wherein in the first semiconductor layer ( 3 ) several first thermo legs ( 3a ), applying and structuring at least one second insulating intermediate layer ( 4 ) on the first semiconductor layer ( 3 ), Applying and structuring a second semiconductor layer ( 6 ) of a second semiconductor material on the at least one second iso lierenden interlayer ( 4 ) and structuring a plurality of second thermo legs ( 6a ) in the second semiconductor layer ( 6 ), where several thermopile pairs ( 32 ) each of a first thermo leg ( 3a ) and a second thermo leg ( 6a ) are formed, each in at least one contact surface ( 37 ) contact directly, forming a cavern ( 9 . 18 ) in the substrate ( 1 ) and one above the cavern ( 9 . 18 ) arranged membrane ( 33 . 33a . 34 ) in which a thermopile structure ( 30 . 32 ) of several pairs of thermopiles ( 32 ) each having a first and second thermo leg ( 3a . 6a ) and their contact surfaces ( 37 ), wherein the first semiconductor material and the second semiconductor material have different Seebeck coefficients (S1, S2) and are doped with the same charge carrier type (n, p). Method according to claim 15, characterized in that in the second insulating intermediate layer ( 4 ) above the first thermo leg ( 3a ) Contact openings ( 5 ), and the second thermal legs ( 6a ) above the first thermo leg ( 3a ) are formed such that the contact surfaces ( 37 ) in the contact openings ( 5 ) be formed. A method according to claim 15 or 16, characterized in that an absorber layer ( 8th ) is applied from an infrared radiation absorbing material on the membrane or as part of the membrane. Method according to one of claims 15 to 17, characterized in that above the second semiconductor layer ( 6 ) an insulating third intermediate layer ( 7 ) and on the insulating third intermediate layer ( 7 ) in the area of membrane ( 33 . 33a ) an absorber layer ( 8th ) and a cap substrate ( 12 ) on the coated substrate ( 1 ) is attached vacuum-tight in such a way that the membrane ( 33 . 33a ) between the cavern ( 9 . 18 ) of the substrate and one in the cap substrate ( 12 ) cavern ( 12a ) is arranged. Method according to one of claims 15 to 17, characterized in that the second semiconductor layer ( 6 ) on the structured second intermediate layer ( 4 ), hereinafter the insulating third intermediate layer ( 7 ) on the second semiconductor layer ( 6 ), then trenches or trench openings through the intermediate layers and semiconductor layers to the substrate ( 1 ), subsequently the cavern ( 9 . 18 ) in the substrate ( 1 ) through at least some of the trenches ( 16 ) is silicon-selectively etched, subsequently the trenches ( 16 ) are closed. A method according to claim 19, characterized in that prior to the etching of the cavern ( 9 . 18 ) a part of the trenches ( 15 ) and only through the other part of the trenches ( 16 ) is etched through. Method according to claim 19 or 20, characterized in that the closed trenches ( 15 . 16 ) subsequently lateral separations of the thermopile pairs ( 32 ) form. Method according to one of claims 15 to 21, characterized in that a plurality of thermopile cells ( 30 ), each one in the substrate ( 1 ) trained cavern ( 9 . 18 ) and a membrane formed above the cavern ( 33 . 33a . 34 ) with several thermopile pairs ( 32 ) has laterally formed side by side and contacted together.