WO2018007558A2

WO2018007558A2 - Radiation dectector and production thereof

Info

Publication number: WO2018007558A2
Application number: PCT/EP2017/067023
Authority: WO
Inventors: Dirk Weiler; Kai-Marcel MUCKENSTURM; Frank Hochschulz
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2016-07-07
Filing date: 2017-07-06
Publication date: 2018-01-11
Also published as: DE102016212423B4; WO2018007558A3; DE102016212423A1

Abstract

A radiation detector 1 comprises a substrate 2 and a membrane 3, and at least one spacer 4, for holding the membrane 3 at a distance from the substrate 2, for electrically contacting the membrane 3, and for thermally insulating the membrane 3 relative to the substrate 2. The at least one spacer 4 is subdivided into a first portion 4a and a second portion 4b in a direction between the substrate 2 and the membrane 3, the length of each of which bridges less than a distance between the substrate 2 and the membrane 3, wherein the first and second portions 4a, 4b are laterally offset relative to each other and interconnected by a lateral element 5, such that the first and second portions 4a, 4b are electrically connected in series by the lateral element 5, and wherein the lateral element 5 contributes to a thermal resistance of the at least one spacer 4 less than, or to the same extent as, a sum of the thermal resistances of the first and second portions 4a, 4b. Alternatively, the at least one spacer 14 can have an electrically and thermally conductive layer 8, which in a sectional area perpendicular to the substrate 2 extends in a loop through the at least one spacer 14, such that an electrical path through the at least one spacer 14, by way of which the membrane 3 is contacted, is longer than a distance between the substrate 2 and the membrane 3. Another possible alternative is for the radiation detector 1 to comprise a substrate 2 with a cavity and a membrane 3, wherein the cavity extends in the substrate 2 in a direction away from the membrane 3, wherein at least one spacer 4, 14 is designed for holding the membrane 3 at a distance from the substrate 2, for electrically contacting the membrane 3, and for thermally insulating the membrane 3 relative to the substrate 2, said at least one spacer 4, 14 extending into the cavity. Alternatively or additionally, the spacer 4, 14, 14n has a side wall roughening obtained by scallops, in order to reduce phonon transport by surface scattering effects and by the resulting path extension. The invention further relates to methods for producing radiation detectors 1 of this type.

Description

Radiation detector and manufacture

Description The present invention relates to a radiation detector and its manufacture, e.g. a bolometer and its manufacture, and in particular on realization forms of nanotube microbolometers.

Uncooled resistance microbolometer arrays, also referred to below as microbolometers, can be used to detect far-infrared radiation (7.5 μm-14.5 μm). These microbolometers are one possible realization of so-called infrared focal plane arrays (IRFPA).

Known microbolometers include a membrane which is suspended by two metal contacts by means of thin webs above the substrate in a vacuum and thus thermally insulated. Basically, the membrane consists of an absorber and a sensor layer. In order to ensure the lowest possible reflection of the incident infrared radiation, the layer resistance of the absorber layer is adapted to the characteristic impedance of air (approximately 377 ohms / sq). Furthermore, located below the membrane, a metal layer, which is referred to as a reflector, on the substrate. Light, in particular infrared light or far infrared light, which is incident on the bolometer, more precisely the absorber, is in part transmitted through the absorber and the sensor layer. By means of the metal layer or the reflector, the partially transmitted light or the transmitted radiation is reflected back and can then be absorbed by the upper absorber layer. The cavity between the absorber layer and the (lower) reflector forms an optical (Fabry-Perot) resonator. The distance between absorber layer and (Fabry-Perot) resonator is advantageously chosen such that the optical path (nd) is an odd multiple of one quarter of the main wavelength λ to be detected in order to fulfill the resonator condition (GI.1). The optical path is composed of the sum of the layer thicknesses weighted with the refractive indices of the media within the cavity (Eq. nd = (2k + V> - (£ = 0, 1, 2 ...) (GI.1)

4

nd = _j n _i d _i (GI.2) In a body with a temperature of z. B. 300 K would be the maximum of the spectral radiance at about λ = 10 μηι. This results in an optical path of nd = 2.5 μηι (k = 0). Fig. 1 outlines the basic structure of a microbolometer. This comprises a substrate 2 and a membrane 3 which is spaced apart from the substrate 2 by metal contacts 17 at a distance d. The membrane 3 comprises a sensor layer 3 b facing the substrate 2 and an absorber layer 3 c facing away from the substrate 2. The upper side of the substrate 2 has a metallization 2m, which acts as a reflector for incident light. Due to the absorption of the incident insignificant infrared or far-infrared radiation, the thermally insulated membrane 3 heats up, which results in a change in the electrical resistance of the sensor layer 3b. The temperature change of the membrane 3 is dependent on the thermal insulation by means of the webs or metal contacts 17 and the energy of the absorbed radiation and is usually several orders of magnitude smaller than the change of the radiator temperature. The change in resistance of the sensor layer 3b can then be determined with the aid of an integrated read-out circuit (abbreviated to RO IC).

A key performance indicator for microbolometers is the Noise Equivalent Temperature Difference (NETD). This factor is defined as the temperature change of an object, which generates a change of the measuring signal, which corresponds to the noise of the system and thus is a measure of the sensitivity of the sensor (Eq. 3).

F is the f-number, A the absorber area, ε the emission coefficient, L the radiance and T the temperature of the object,

the square of the total noise voltage, g _th the thermal conductance and U _bias d \ e bias voltage. It can be seen from Eq. 3 that the NETD, inter alia, is significantly influenced by the thermal insulation of the membrane or the corresponding thermal conductance g _th . in the In general, the membrane is thermally poorly isolated from the substrate, since the suspension is done by metal contacts. The resulting thermal conductance in this case is not sufficiently small to achieve a good or satisfactory performance (NETD <100 mK), since the contacts are made via tubes with thick metal coatings. For reasons of process and stability, these metal coatings must be thick or have a minimum thickness and thus conduct the heat generated in the membrane relatively well.

In conventional microbolometers shown in FIG. 2, an improvement of the thermal insulation or reduction of the thermal conductance is realized by additional connecting elements (webs 4s) between the suspended membrane and the metal contacts k.

For example, Weiler (Weiler, Dirk, et al.) Teaches "pixel-pitch uncooled amorphous silicon TEC-IGA VGA IRFPA with massively parallel sigma-delta ADC readout." SPIE Defense, Security, and Sensing. International Society for Optics and Photonics, 201 1) an array consisting of such microbolometers. In this case, a microbolometer contains an absorber, which is held by two webs, so that the absorber is in a vacuum other than contact with the webs.

The thermal conductance of the webs g _st ege can be determined by Eq. 4

where Aj is the thermal conductivity of the individual web materials, b _st e _g and d _st eg the width and thickness of the individual web materials and l _st e _g the length of the webs. The factor 2 results because two webs 4s are present. Thus, in order to achieve a good thermal insulation, the cross-sectional area of the webs 4s should be as small as possible and the webs 4s consist of materials which have a low thermal conductivity. With regard to the thermal insulation, the proportion of metal contacts 4 k is usually negligible compared to that of the webs 4s. Furthermore, the thermal insulation is influenced by the heat radiation to the environment. However, since the infrared detectors are operated in a vacuum, the influence is also usually very low, so that overall the thermal conductivity of the webs 4s dominates. The development of microbolometers is moving towards smaller and smaller pixel sizes for high-resolution IRFPAs. At the same time, the demands on performance increase. Currently microbolometer arrays are common with 17 μηι pixel pitch. However, according to the invention, this should be reducible to a pixel pitch of approximately 12 μηι. Scaling the pixel pitch from 17 μηι to 2 μηι means halving the absorber area.

In general, a reduction in the pixel pitch due to the reduction of the absorber surface has a massive influence on the performance of the microbolometer. The effective absorber surface is limited due to the required area for the realization of the webs. Depending on the design and structure of the webs or target value of the thermal conductance, the claimed area of the webs can be different in size. The absorber surface, however, has the same effect on the performance as the thermal conductance. If the pixel area is now reduced by a certain factor, theoretically the entire microbolometer could be scaled accordingly so that the ratios of the individual areas (lands, contacts, absorber area) and distances to each other are always the same. The loss of performance would then u. a. determined by the scaling factor. However, this scaling with a fixed factor for all components is practically impossible, since such scaling limits the limits of lithography. Typically, a stepper lithography with a resolution of 0.35 μm is used for the production of microbolometer arrays. Frequently, structure sizes at the limit of this resolution are already used in current but also in older microbolometer generations (17 μηι, 25 μηη, 35 μηι), such. B. at the web widths and distances. Furthermore, the contact holes and upper contact surfaces can not be scaled arbitrarily small for process and stability reasons, so that a limit also exists here. In summary, the smaller the bolometers are, the land areas take up more and more space at a fixed thermal conductance relative to the pixel size. As a result, the effective absorber surface is additionally reduced and the performance is consequently greatly reduced.

In Li (Li, Chuan, et al., Recent development of ultra small pixel uncooled focal plane arrays at DRS, Defense and Security Symposium, International Society for Optics and Photonics, 2007), the absorber layer is screened over the entire pixel area. Such an arrangement is also called two-layer or Umbrella design, since the complete outer surface is available for the absorber. The disadvantage, however, is that the webs and the sensor layer continue to be in one plane. the. The thermal insulation is therefore limited by the free, available, pixel area. Furthermore, the resonator condition in the region of the suspension of the absorber is not met, which has a negative effect on the absorption. Also in Nikiaus (Nikiaus, Frank, Christian Vieider, and Henrik Jakobsen, MEMS-based uncooled infrared bolometer arrays: a review, Photonics Asia, 2007, International Society for Optics and Photonics, 2007), bolometers are discussed, one embodiment being a conventional bridge. Design includes and another an umbrella design that resembles the design described in Li.

In WO 2016/005 505 A2 a large area for the absorber is available. According to the invention, however, the thermal conductivity should be further reduced. Thus, with a scaling of the pixel pitch, the desired performance of the microbolometer thus achieved should be achieved.

The approach of WO 2016/005505 A2 is based on the realization of the thermal insulation and simultaneous electrical contacting of electromagnetic radiation detectors (especially infrared detectors) with the aid of sufficiently long and thinly coated hollow tubes, which are also referred to as nanotubes. These are shown in cross section in FIG. 3 and can be produced using technologies and processes from microsystem technology. The thermal conductivity of the contacts is compared to the webs, due to the thick metal coating so far very large and therefore does not contribute to the insulation. However, if the outer walls of the round contacts are coated sufficiently thinly with a suitable metal layer, this results in a thermal conductance which is comparable to that of the webs or may even be significantly smaller. The thermal conductance of the contact tubes (see equation 5) (described here as nanotube contacts or nanotubes) can be determined analogously to Eq. Calculate 4, where circular rings form the respective cross-sectional areas.

The term η _ι2 -π _, ι = d is equivalent to the thickness of the individual materials / layers within the contacts. Similar to the lands, the spacers are long and made of thin materials which have low thermal conductivity. In addition, the basic radius r _{2.2 of} the contacts 4k should also be chosen as small as possible. In other words, the total diameter D of the contacts, ie r _{N, 2} , should be as small as possible.

As described, the membrane supported by the spacers consists of a member which changes its electrical properties upon application of heat and an absorber layer. The temperature-sensitive element consists of either an electrical resistance, a capacitance, an inductance or a pn-junction (diode).

In addition to thermal insulation, the second function of the spacers is to electrically contact this element. In general, the nanotubes consist of an electrically conductive layer. In order to protect this conductive layer in the etching process of the sacrificial layer optionally further protective layers can also be deposited with the atomic layer coating. These protective layers must be electrically and thermally insulating and stable with respect to the etching medium of the sacrificial layer. The thicknesses of all layers of the nanotubes are in a range of 0, 1 nm - 1 μηι. The object of the invention is to provide a radiation detector and a manufacturing method, so that the manufacturability with the same electrical conductivity and high thermal isolation from the substrate or a better ratio between electrical and thermal conductivity of the membrane suspension can be achieved with a comparable manufacturing effort, or that of occupied space of the radiation detector with the same electrical conductivity and high thermal isolation from the substrate or vice versa, a better ratio between electrical and thermal conductivity of the membrane suspension at the same occupied space of the radiation detector can be achieved. Alternatively or additionally, the thermal resistance of the membrane suspension should be increased or the thermal conductance should be reduced by adapting the microstructure of the membrane suspension.

The object is achieved by a radiation detector according to one of the independent claims or according to a method for producing a radiation detector according to one of the independent claims.

Advantageous developments are in the dependent claims. According to one aspect of the present invention, the manufacturability of the spacers is improved by dividing the spacer into two sections. As a result, the spacer can be extended in its maximum length between the membrane and the substrate. Usually, the maximum length of nanotubes - as a possible embodiment of spacers - for process reasons limited because z. B. only reliably in a limited depth, ie a limited length, can be deposited in openings, for example, to define spacer walls. The fact that a spacer is divided into two sections, both the first and the second section can be generated in the respective process-technical maximum realizable length. These are additionally connected via a laterally extending element. The latter could be used as an example to even further increase the thermal resistance. In an advantageous development of this embodiment is a cross section of an electrically conductive material of the first and second portion is less than or equal to 7 μηι ² or less than or equal than 3 μηι ² or smaller or equal than 0.8 μηι. ²

Advantageously, the distance between the laterally extending element and the membrane according to the resonator condition according to Eq. 1, whereby the element can serve as a back mirror by also being arranged laterally between the membrane and the substrate. This distance can be, for example, between 1 μηι and 2.5 μηι, while the distance of the element 5 to the substrate can be greater than 2.5 μηι. Alternatively, the laterally extending element may be located more than 25% of the distance, advantageously more than 30%, and more preferably more than 45% of both the substrate and the membrane. The laterally extending element may be arranged substantially centrally between the substrate and the membrane. This has the advantage that both the first section and the second section of the spacer can be formed in a maximum length, which is technically possible. In this case, the laterally extending element is not necessarily used as a rear-view mirror. The electrical path from the membrane to the substrate is thus maximized, thereby increasing the thermal resistance.

In an advantageous development, the laterally extending element is designed as a reflector for incident electromagnetic radiation, in particular light or infrared light. In this case, the reflective part of the laterally extending element under the Membrane be formed so that light incident through the membrane is reflected back to the membrane. Thus, the light can be picked up again by the membrane, in particular the absorption layer of the membrane. A radiation detector, as described in this first aspect of the invention and also the developments can be produced by the first and the second portion are respectively produced by means of ALD in openings of a first and / or second sacrificial layer. ALD allows thin metal layers. Through the sacrificial layers, a certain shape can be achieved or specified. The openings can be made by etching a hole in each of the first and second sacrificial layers. Advantageously, the etching is done by means of a DRIE process, wherein as a DRIE process in particular a Bosch and / or gyro process can be used.

Advantageously, a process to produce a radiation detector as described above may be accomplished in the following steps.

1 . Structuring a first sacrificial layer so that it has a hole;

2. depositing a first layer of conductive material in the hole and on the first sacrificial layer to form a first conductive layer;

3. structuring the first layer of conductive material such that it forms a first portion of a spacer in the hole and a laterally extending element on the first sacrificial layer;

4. creating a second sacrificial layer on the first sacrificial layer;

5. patterning the second sacrificial layer so that it has a hole; 6. applying and patterning a second layer of conductive material such that it forms in the hole in the second sacrificial layer a second portion of a spacer electrically connected in series with the first portion via the laterally extending element; 7. Remove the first and second sacrificial layers. According to a second aspect, a radiation detector is improved with respect to the thermal insulation of the membrane from the substrate in that a spacer has an electrically and thermally conductive layer which extends in a cutting surface perpendicular to the substrate in a loop through the spacer. Thus, an electrical path through the at least one spacer, over which the membrane is advantageously electrically contacted to the substrate, is longer than a distance between substrate and membrane, for example, due to manufacturing limitations, as mentioned above, or for other reasons, such as the desire for a quarter wavelength distance between the membrane and a reflector is limited. Due to the loop-shaped configuration of the spacer or of the electrically and thermally conductive layer of the spacer, the electrical path and thus also the thermal path between membrane and substrate can be extended beyond the mere membrane / substrate distance. Thus, the thermal resistance increases with the same space, which is determined by the distance on the one hand and the lateral extent of the membrane and its suspension on the other. As explained in the Explanatory Notes to Equation 3, the thermal insulation (corresponds to a thermal resistance) of the membrane is a significant factor for the so-called Noise Equivalent Temperature Difference (NETD). This defines the temperature change of an object, which generates a change of the measurement signal, which corresponds to the noise of the system. Thus, this is a measure of the sensitivity of the sensor. By extending the electrical and thus thermal path so an increased sensitivity of the sensor can be achieved.

Such an at least one spacer for holding the membrane with an electrically and thermally conductive, loop-shaped layer passing through it can be produced by ALD and a sacrificial layer method, wherein a first and at least one second sacrificial layer can be deposited, with which the shape of the loop-shaped electrically and thermally conductive layer can be produced. It is therefore possible to specify a shape through sacrificial layers into which an electrically and thermally conductive, advantageously loop-shaped layer can then be deposited by means of ALD. In a further process step, the respective sacrificial layer or all sacrificial layers can then be removed by etching and advantageously the electrically and thermally conductive layer, the membrane and the substrate remain. The at least one spacer may be formed in a preferred embodiment of the second embodiment of a series of laterally spaced columns. These are advantageously connected in pairs at their upper or lower ends. Upper or lower end means in this context, the end remote from the substrate or the substrate facing the end. At least two columns can be connected to each other via a laterally extending element at its lower end. A structure with two columns each, which are connected to each other via a respective laterally extending element at its lower end end, can be repeated, wherein the individual pairs of columns, which are connected to each other at its lower end by a laterally extending element, respectively their upper end can be connected to each other. Thus, an electrical path may form through a series of pairs of two pillars which are electrically connected in series. In this way, the electrical path can be extended and thus the thermal resistance can be increased almost arbitrarily.

The at least one spacer could also be formed as a column, in the wall of which the electrically and thermally conductive layer is arranged folded. In this refinement, the folded arrangement of the electrically and thermally conductive layer on the wall of the column makes it possible to achieve a long electrical path in a very space-saving manner. Space saving in this context means that for the electrically and thermally conductive path forming the spacer, in a plan view (ie in the direction of the normal of the substrate) on the radiation detector little surface is needed to form the spacer. Due to the folded structure of the electrically and thermally conductive layer, the individual layers of the layers can be very close to each other. The individual layers may preferably be arranged so that the column which forms the spacer is composed of a plurality of coaxial, cylindrical layers located one inside the other. Since the individual layers can be electrically connected to each other at their ends of the cylinder, a very long electrical path can be achieved. The coaxial axis of the column is referred to as the axis of the radiation detector.

At least two different structures with a folded electrically and thermally conductive layer on the edge of the column are conceivable. In the first structure, the folded, electrically and thermally conductive layer may be disposed in the wall of the column so that the electric path can be formed in the sectional area on one side of the axis of the column. The cut surface is the already described cut surface, which is formed perpendicular to the substrate. The cut surface can thus be clamped on at least one side by the normal of the substrate and the other side of the cut surface can be parallel to the surface of the substrate. This development has the advantage that the complete circumference of the column or of the electrically and thermally conductive layer which forms the column can be used for the electrical path. Thus, an electric current flowing from the membrane to the substrate may pass over the entire circumference of the pillar from the contact facing the membrane to the contact facing the substrate. The column can therefore be constructed symmetrically. Since the entire circumference of the wall of the column can be used for the electrically conductive path in this structure, the electrically and thermally conductive layer is damaged in sections, which extend over a circumferential segment in a specific region of the electrically and thermally conductive layer extends, not to a failure of the electrical conductivity from one to the other end of the column. The electrically conductive path can still form over the remaining circumference of the wall of the column, so that the damage remains without influence on the electrical conductivity.

In an alternative structure of the development, in which the spacers are formed as a column, in the wall of which the electrically and thermally conductive layer may be folded, the electrically and thermally conductive layer in a cross section of the column (the cross section in plan view) may preferably form at least three rings. Interspaces between the preferably at least three rings belong to cavities, which are preferably at least partially open at an end facing away from the substrate. This development has the advantage that the sacrificial layer, which can form the intermediate spaces between the at least three rings, can be well etched away. In particular, compared to the first structure, there may be a relatively large amount of space to introduce etching medium between the rings into the interstices. Thus, the sacrificial layer in the interstices can be removed reliably and quickly by etching, since the etching medium can easily and reliably reach the complete cavity in sufficient quantity. Why this is easier with this training, will be explained or apparent below. In both structures, an occupancy of the inner walls of the column may be provided with a sacrificial layer during manufacture. The inner walls of the column can each be formed by individual layers of the electrically and thermally conductive layer. The sacrificial layer should be removed or removed before delivery or before release. In the first structure, a single layer of the electrically and thermally conductive layer in the hole bottom may preferably be removed by ion etching. Thus, before the next layer of the electrically and thermally conductive layer is deposited, in the sectional area the connection in the pot-shaped hole bottom can be interrupted. This happens in particular in the second and the further, second layer of the electrically and thermally conductive layer in the hole bottom. Thus, upon completion of the radiation detector, etching medium may be introduced through the axis of the spacer between the upper and middle layers of the spacer to etch away the sacrificial layer located there. The distance through the axis of the multi-layer spacer is relatively wide. This makes it difficult to transport etching medium to the hole bottom and also to distribute it further in order to remove the complete sacrificial layer between the outer and middle layer of the electrically and thermally conductive layer.

For this reason, in the second structure, the symmetry can be broken. Compared to the first structure, etching medium can be introduced directly between the outer and the middle layer of the electrically and thermally conductive layer in order to etch away the sacrificial layer located there. Through an opening which is attached to the end of the column facing away from the substrate, etching medium can easily be introduced into the outer of the two intermediate spaces, or etching medium can also be introduced into the inner space between the inner layer of the electrically and thermally conductive layer and middle layer of the electrically and thermally conductive layer, which was also covered in the manufacturing process with a sacrificial layer introduced. Thus, therefore, reliable, easy and fast etching medium can be introduced into the two spaces mentioned.

Furthermore, this geometry (with broken symmetry) also simplifies the final complete removal of the etching medium, so that the etching medium can not reach the environment during operation. Both developments of the second aspect may be generated in a multi-stage sacrificial layer method in a manner similar to that above with respect to the first aspect. In a further aspect, which in principle can also be combined with the previously enumerated embodiments, in the case of a radiation detector, a substrate is provided with a depression which extends on the membrane-facing side of the substrate in the substrate in a direction away from the membrane. The radiation detector comprises a spacer for holding the membrane, which extends into the recess in the substrate. An advantage of this aspect is that an additional path can be formed which extends at least partially into the substrate. At the same distance between substrate and membrane, the length of the spacer increases, which can thus form a greater thermal insulation. The electrical path from the membrane to electrically contact the substrate is maintained and the thermal resistance of the spacer increases. The substrate may include an integrated readout circuit having circuit elements thereof formed on a side of the substrate remote from the diaphragm. In this case, a metallization layer for contacting the circuit elements with one another may be arranged at a height between the membrane-facing side of the substrate and the bottom of the recess of the substrate. This can make the electrical connection between the circuit elements. In other words, the biden of the recess may be lower than one of the wiring planes of the substrate.

Thus, the distance between the contacting of the substrate, which is advantageously connected to the integrated read-out circuit, can extend the distance of the depression in the substrate. Thus, without increasing the membrane / substrate spacing and thus increasing the volume trapped therewith, the thermal resistance of the spacer can be increased, thereby improving the sensitivity of the detector.

In an advantageous development, the side of the substrate facing the membrane can also be metallized at least on the surfaces which are located directly below the membrane. As a result, incident electromagnetic radiation, in particular light or infrared light, can be reflected back onto the membrane. Thus, with incident electromagnetic radiation, in particular light or infrared light, the temperature change of the absorber of the membrane increase. Advantageously located the metallization, which acts as a reflector, substantially in the advantageous distance already explained (see equation 1).

In one aspect or a further development, which can be combined with all previously mentioned embodiments or developments, at least one spacer can be designed such that it has a wall roughness or wall waviness. This may have an amplitude (w) greater than 30 nm. As a result, phonon transport can be reduced by surface scattering effects and / or the resulting path lengthening. This can be achieved, for example, by scallops. The amplitude of the scallops can be greater than 30 nm. Scallops can be microscopic, arched structures. Due to this structure, the resulting thermal conductance can also be reduced by a resulting path extension of the spacers. The resulting path lengthening by the amplitude of the scallop bulge of the at least one spacer may be more than 5%, or 10% or 20%. The scallops or wall roughness and / or wall waviness can be generated by advantageously etching holes in a sacrificial layer for the deposition of spacers so that they have a wall roughness or wall waviness. Are now the walls of the holes metallized in the sacrificial or layers, z. B. when depositing the electrically and thermally conductive layer, so the said scallops form. These can reduce phonon transport through surface scattering effects. In principle, however, the phonon transport can also be achieved by structures or surface configurations other than scallops, provided that it is ensured that the shape or structure of the surface is lengthened and / or that phonon transport is reduced. The special structure of the holes can be achieved by z. B. in a Bosch process, the etching time of a single etching process is significantly increased. As in a chemical etching, such. B. in a Bosch process, the etching takes place in all directions, that is undirected, then forms the desired arcuate structure. Alternatively, for example, processes are also conceivable in which etching can first be carried out, for example by ion etching in a single etching step to a certain depth in the direction of the normal of the hole or substrate to be etched, and then an undirected, ie uniform, etching in all directions , In this way, a mixture of ion etching and chemical etching, which happen alternately, can produce the desired arcuate structure. In an advantageous development, which can be combined with all embodiments, an etching protection layer can be deposited on the at least one spacer or the individual layers of the electrically and thermally conductive layer or the electrically and thermally conductive layer during the production of the radiation detector. By means of this etching protection layer, it can be achieved that during ion etching and / or chemical etching the metallization is not damaged, but only the first, second or third sacrificial layer is etched away.

Advantageously, the wall thickness of the electrically and thermally conductive layer of the at least one spacer is between 0.1 nm and 1 μm, or between 1 nm and 0.5 μm, or particularly advantageously between 10 nm and 100 nm.

The radiation detector may be a bolometer. In an advantageous embodiment, a plurality of radiation detectors can be combined to form an array, so that, as in the case of a CCD camera, an image which is composed of an array of pixels can be recorded. Of course, according to the invention, however, an infrared light image can be detected / recorded.

Preferred embodiments of the present invention will be explained in more detail below with reference to the drawings.

Fig. 1 shows a schematic drawing of a conventional radiation detector in a sectional plane in which at least one side of the cutting plane is defined by the normal of the substrate;

FIG. 2 shows a SEM image of a conventional 25 μm pixel-pitch microbolometer array with a contacting of the membrane via webs; FIG.

Fig. 3 shows a schematic cross section in the horizontal of a nanotube contact consisting of two materials for contacting the membrane and a conventional spacer;

4a-4d show side sectional views of a radiation detector in various successive stages during the fabrication of a radiation detector according to an embodiment wherein the spacer is divided into first and second sections; Figures 5a-5f show side sectional views of a radiation detector at various successive stages during manufacture of a radiation detector according to an embodiment wherein the spacer is formed from a series of pillars to form a looped electrical path in a sectional plane perpendicular to the substrate;

FIGS. 6a-6g show a further development of FIG. 5, also in side sectional views of a radiation detector in various successive stages during the manufacture of a radiation detector according to an alternative embodiment in which the spacer is formed from a series of columns to form a loop forming an electrical path extending in a sectional plane perpendicular to the substrate, the membrane being at a height above the substrate which is less than a maximum extension of the spacer away from the substrate;

7a-7j show side sectional views of a radiation detector at various successive stages during its manufacture according to an embodiment in which an electrically and thermally conductive layer forming the electrically conductive path is arranged in the wall of the spacer, here with a symmetrical structure;

8a-8d show side sectional views of a radiation detector in various successive stages during its manufacture according to an alternative embodiment, in which in the wall of the spacer, an electrically and thermally conductive layer, which forms the electrically conductive path, folded, here with a structure that is not equal to the circumference of the spacer to facilitate sacrificial material removal;

Figures 9a-9e show side sectional views of a radiation detector in various successive stages during its manufacture in which the electrical path between the membrane and substrate is extended by the spacer, which is part of the electrical path, extending into a depression in the substrate; FIGS. 10a-10d show side sectional views of a radiation detector at various successive stages during its manufacture wherein the thermal resistance of the spacer is increased by scallops which ensure an arcuate shape of the electrically and thermally conductive layer of the spacer to promote phonon transport through surface scattering effects as well as through diffusion reduce resulting path lengthening.

In the following, with reference to the figures, embodiments for the production of special nanotube microbolometers will be described. The process flow is shown in a simple form. One aspect here is the arrangement or production of the nanotubes in order to further improve the thermal insulation. In all variants, the sketched protective oxide can be omitted under the sensor layer. An absorber may also be located on the sensor layer (separated by an insulating layer). In addition, the electrically conductive layer in the nanotubes may be surrounded by further protective layers. The embodiments illustrated below can be combined with each other, with the raised reflector or other structures.

Fig. 1 shows a structure of a conventional radiation detector, in particular infrared detector or bolometer. It explains basic ways of functioning. The conventional radiation detector 1 shows a substrate 2 which includes a read-out circuit 6 (English: Read Out Integrated Circuit, ROIC for short). A membrane 3 is located at a distance d from the substrate 2 at a distance d. The membrane 3 is held by a metal contact 17 at a distance d from the substrate 2. On the substrate 2, in the direction of the membrane 3, that is to say the membrane 3, there is a metallization 2m, which acts as a reflector for incident light or incident electromagnetic radiation. The membrane 3 is composed of a sensor layer 3b, which faces the substrate 2, and an absorber layer, which is located on the side of the membrane 3 facing away from the substrate. The thermal insulation of the membrane 3 and thus of the sensor layer 3b and the absorber layer essentially passes through the metal contacts 17. Furthermore, the thermal insulation of the membrane can be further improved by webs 4s, which are connected to the metal contacts 4k. In Fig. 1, a vertical section in the xz plane is shown by the radiation detector. A plan view (in the xy plane) is shown in FIG. In this case, one sees the metal contacts 4k, which are contacted by the two webs 4s and thus electrically connect the metal contacts 4k to the membrane 3. It is obvious that the width of the lands 4s substantially determines the thermal resistance from the membrane to the metal contacts 4k (see Eq. For the determination of the thermal resistance and the thermal conductance of the webs 4s g _S t e _ec flow, the width b _S T _EG and the thickness dsteg (ie the cross-section of the web in the direction orthogonal to the flow direction of current) of the webs 4swesentlich a. The webs 4s consist essentially of metal, so that the specific conductance λ, can not be significantly influenced.

A cross section through a nanotube, which is shown in the xy plane in FIG. 3, and which serves to suspend the membrane or the spacing of the membrane 3 from the substrate 2, has already been described in WO 2016/005505 A2. The spacers 4, take the thermal insulation of the membrane 3 from the substrate 2 with simultaneous electrical contacting of the electromagnetic radiation detectors. The spacers are as z. B. sufficiently long and thin coated hollow tubes (therefore called nanotubes) is formed. These can be produced using technologies and processes from microsystems technology. The thermal conductance of the spacers (nanotubes) is very small compared to the webs due to the thicker metal coating of the webs and can thus contribute significantly to thermal insulation. This is achieved by covering the walls of the spacers, which are shown as examples by way of example in this embodiment, sufficiently thinly coated with a metal layer, resulting in a very low thermal conductance. This can be according to Eq. 5 calculate. In Fig. 3, the radii η, -ι, r _{1 2} and r ₂ , i and r _2.2 are shown. However, spacers are also conceivable that consist of more than two layers. As in Eq. 5, the cross-section or effective cross-sectional area of the individual layers (shown in the xy direction in FIG. 3) is essential for the thermal conductance of the entire spacer. Effective cross-sectional area is the contiguous area in cross section, which consists of a specific material.

However, in terms of process technology, limits are reached here which limit the effective cross-section of the spacers downwards, because at some point no stable nanotubes can be produced any more. The electrical path, which can form between the membrane and the substrate, but should have a lower thermal conductivity.

Exemplary embodiments of nanotube microbolometer embodiments in which the spacer, also referred to as thermal via, is adapted by adapting the geometry or microscopic structure of the nanotube microbolometer are described below. Stands holder improved in its thermal insulation and / or made easier to produce.

The nanotubes described below can be produced for example by means of a sacrificial layer process. First, a hole is etched into the sacrificial layer and subsequently coated. For the etching of the hole, for example, the so-called Bosch process can be used, as it is thereby possible to produce steep edge angles at high aspect ratios. The layers can be deposited by means of atomic layer coating, so that even at the aforementioned steep edge angles, the etched holes are covered. Furthermore, the deposited layers can be structured according to the manufacturing process. In addition, the sacrificial layer can be removed so that the manufactured nanotubes are free.

1. Multi-level nanotube bolometer

In the embodiment of a radiation detector, which is also referred to as a multi-level nanotube bolometer shown in Fig. 4a-d, this is done by the spacer 4 along its length, ie along the direction between the membrane 3 and substrate 2, in sections is divided, so that run with their respective length in the direction between the membrane 3 and substrate 2. A laterally extending element 5 is located in the electrical path between the membrane 3, which is composed preferably of an optional protective layer 3a and a sensor layer 3b, and a metallization 2m of the substrate 2. The laterally extending element 5 is located between the first section 4a and the second portion 4b of the spacer 4. The first and second portions 4a, 4b of the spacer 4 are laterally offset from each other and connected to each other via the laterally extending element 5. Der Abstandsteil 4 ist über einen Abstand von der Abstandhalter 4 bzw. Thus, the first and the second portion 4a, 4b and the laterally extending element 5 are connected electrically, but also thermally in series. In this case, the end of the second section 4b facing away from the substrate 2 can be electrically connected to the membrane 3 electrically via a second layer 25 of an electrically and thermally conductive layer, ie a layer 25 which is located in the membrane plane and, for example, as another Web may be formed, in addition to the laterally extending element, or as a frame around the actual membrane. The first section 4a of the spacer 4 can be electrically connected to the metallization 2m of the substrate 2. In terms of process technology, such a radiation detector 1 can be produced in a multi-stage sacrificial layer method. (see Fig. 4a-d), which includes, for example, the following steps or stages.

The starting point may consist of a substrate 2 on which a metallization 2m is located, as shown in FIG. 4a. a) In a first process step, a first sacrificial layer 9 can then be applied to the substrate 2 (or the ROIC 6, in particular to the metallization 2m of the substrate 2). b) In a second process step, the sacrificial layer 9 is structured. In the example of FIG. 4b, it is shown that a hole 7 is etched into the first sacrificial layer 9. This may preferably be done by a DRIE (eg, a Bosch or Gyro) method. Alternatively, ion etching is also conceivable in order to be able to etch in the direction of the normal, ie in the z-direction of the substrate 2, as far as possible. In this case, the etching in the direction of the normal or the z-direction can be terminated automatically by the metallization 2m of the substrate 2. Thereafter, a first layer 15 of an electrically conductive material is deposited on the first sacrificial layer 9 and in the hole 7. For this purpose, for example, atomic layer deposition or ALD or alternatively other methods, such as CVD, used. Subsequently, the first layer 15 of the electrically and thermally conductive layer can be patterned so that the laterally extending element is formed or remains on the surface of the first sacrificial layer 9 and the electrically conductive material remaining in the hole 7 forms a first section of the later completed spacer 4 forms. c) A second sacrificial layer 10 is then applied, that is, for example, deposited on the entire structure or over the entire surface. Subsequently, the membrane 3, which is composed of the optional protective layer 3a and the sensor layer 3b, such as semiconductor material, can be deposited and patterned on the second sacrificial layer 10. Either before or after the deposition of the membrane 3, a further hole 7b can be etched or otherwise structured in the sacrificial layer 10. The structuring process can be limited in the z direction downwards in the direction of the substrate 2 by the laterally extending element 5 or use the material of the latter as an etching stop. d) As the following process step, a second layer 25 of electrically conductive material is applied (deposited, for example, by ALD). This is done, for example, over the entire surface in order to form a further section of the spacer 4 in the hole 7b, as well as to form a lateral section 25 at the level of the membrane 3, which connects the said section to the sensor layer of the membrane 3. Accordingly, a so-called nanotube forms in the hole 7b in the second sacrificial layer 10, which forms the second section 4b of the spacer 4. Subsequently, the applied or deposited electrically conductive material is structured. This can be done by leaving a (narrow) path of electrically and thermally conductive material between the membrane 3 and the second portion 4b of the spacer 4 on the previously fabricated assembly.

In other words, in this embodiment, a plurality of nanotubes in different planes can be structured one above the other and electrically connected to one another, so that contact between the sensor layer and ROIC is made possible.

The advantage is that the thermal insulation can be further improved by the additional nanotubes, without affecting the absorber surface. According to Eq. 4, the resulting thermal conductivity is significantly influenced by the length of the nanotube.

However, the etch angle of the Bosch process used limits the sacrificial layer thickness, since the diameter of the hole bottom becomes significantly narrower with increasing etching depth and thus impairs the mechanical stability of the manufactured nanotubes. By the arrangement described here, effective nanotube lengths can be achieved, which are not possible due to the described problems with the structuring of a single nanotube.

The bonding layer between the nanotubes can also be used as a reflector. The process sequence shown in FIGS. 4a to 4d outlines, by way of example, a realization with two nanotubes. In principle, the process can be extended to any number of nanotubes (limited by the overall stress of the wafer after deposition of the individual sacrificial layers and mechanical stability of the later free-standing structure).

The following method steps are shown in FIGS. 4a to 4d: Deposition of the first sacrificial layer on a substrate (ROIC)

Patterning of the sacrificial layer (e.g., by the Bosch process), deposition (e.g., by atomic layer deposition), and patterning of an electrically conductive layer

Deposition of the second sacrificial layer, deposition and structuring of a protective oxide and a sensor layer

Structuring the second sacrificial layer (e.g., by the Bosch process), depositing and patterning an electrically conductive layer

The particular advantage of this method is the following. In practice, the etching depth in the Bosch process is limited to a sacrificial layer, since a Bosch process has an etching angle and thus the diameter of the perforated bottom 7 becomes narrower as the etching depth increases. This impairs or limits the mechanical stability of the manufactured nanotubes. However, by dividing the spacer 4 into a first and a second section 4a, 4b, a spacer 4 can be obtained which has a longer effective (nanotube) length than through Actually, the procedural conditions appear to be possible at first. In addition, the electrical resistance can be increased by the laterally extending element 5. In this case, the contacts of the laterally extending element 5 with the first portion 4a and second portion 4b may be located at opposite ends of the laterally extending element 5. Thus, a long path can be achieved, which further reduces the thermal conductance.

Accordingly, a radiation detector with a substrate 2 and a membrane 3 has been described, which has at least one spacer 4 for a) holding the membrane 3 spaced from the substrate 2, b) electrical contacting of the membrane 3 with, for example, a contact or Connection or even an evaluation circuit on or in the substrate and c) thermal insulation of the membrane 3 with respect to the substrate 2 has. In a direction between substrate 2 and membrane 3, ie in the vertical direction in the figures, the at least one spacer 4 is divided into a first section 4a and a second section 4b, the length of each of which bridged less than a distance between the substrate 2 and diaphragm 3. In the example shown, there were two, but of course there may be more. The first and second sections 4a, 4b are laterally offset from one another and are connected via a laterally extending element 5. The first and second sections 4a, 4b are electrically connected in series across the laterally extending element 5, ie, extending therebetween, for example, connecting the upper end of one section to the lower (substrate facing) end of the other section. The laterally extending element 5 contributes less or equal to a thermal resistance of the at least one spacer 4 than a sum of the thermal resistances of the first and second sections 4a, 4b, ie the spacer sections are each of the type as already described above , which are designed not only to allow the electrical conduction between the membrane and substrate, but also to reduce the thermal conduction as possible. A cross-section of electrically conductive material 8 of the first and second sections (4a, 4b) is for example less than or equal to 7 μηι ² or less than or equal to 3 μηι ² or less than or equal to 0.8 μηι ² chosen to a suitable thermal resistance behavior to achieve, of course, other values are also conceivable. The laterally extending element 5 is, for example, arranged centrally or the membrane-to-substrate distance is divided evenly under the sections, so that in the case of two sections the element 5 is arranged substantially centrally between substrate 2 and membrane 3. However, it is also possible that the element 5 is arranged, for example, more than 25% of the distance or more than 30% of the distance or more than 45% of the distance away from both the substrate 2 and the membrane 3. Although not shown, it is possible for the laterally extending element 5 to be designed as a reflector 5a for incident electromagnetic radiation and for this purpose to extend between the membrane and the substrate, both in the layer thickness direction and laterally.

2. Vertical Meander Nanotube Bolometer In Fig. 5, another embodiment is shown. In this case, the thermal conductance can be reduced by using a laterally extending element 5 between a first and a second sacrificial layer 9, 10 in the process, in order to achieve a turn of the spacer 4. A possible process with the example, individual process steps for generating such a radiation detector in a so-called vertical meander nanotube execution may include the process steps a) to f) (as in Fig. 5 a - 5f). First, the radiation detector is placed in the final product (but before the preferably complete etching away of the sacrificial layers 9, 10), as shown in Fig. 5f. On the metallization 2m of a substrate 2, there may be a first sacrificial layer 9 over which a second sacrificial layer 10 may be located. On the second sacrificial layer 10 may be a membrane 3, which may be composed of an optional protective layer 3a and a sensor layer 3b. The membrane 3, in particular its sensor layer 3b, can thus be contacted with a second layer 25 of an electrically and thermally conductive layer. In this case, the electrical contact between the membrane 3 and the metallization 2m can be produced by a continuous spacer section 14d, hereinafter also referred to as column, which penetrate through the first sacrificial layer 9 and the second sacrificial layer 10 up to the metallization 2m can. Between the continuous spacer section 14d, which extends from the upper side of the second sacrificial layer 10 to the metallization 2m of the substrate 2, and the membrane 3, further spacer sections or columns 14z are arranged in the electrical path starting from the membrane 3. However, these extend only through the second sacrificial layer 10 as far as a laterally extending element 5. In the electrical flow direction, a spacer section 14z extends from the top of the second sacrificial layer 10 to the laterally extending element 5 and a further spacer 14z from the laterally extending section Element 5 to the top of the second sacrificial layer 10. In this case, the electrical contact between the two mentioned spacers 14z is interrupted at the top of the second sacrificial layer 10. The electrical connection or the electrical path of the spacer takes place only via the laterally extending element 5 between the sacrificial layers at a height between the membrane and the substrate. One end of a structure as just described, consisting of two spacer sections 14z and a lateral element 5 is connected to the membrane 3 and the other end to the continuous spacer section 14d, which extends from the top of the second sacrificial layer 10 to the Metallization extends 2m. As can be seen in FIG. 5 f, any number of such just-described pair structures could be arranged next to each other, so that the electrical and thus also the thermal path lengthened. The individual structures consisting of two spacer sections 14z and a lateral element 5 can be connected to one another at the top. So there can be a series circuit. Thus, an electrical path can form from the diaphragm 3 to the continuous spacer portion 14d, which is directly connected to the metallization 2m. The electrical path should be long and, if possible, through all the structures described. Doors, each containing a laterally extending element 5 and two spacer portion 14z, a radiation detector 1 go.

In terms of process technology, such a structure can be produced as follows: a) If not yet present, applying a metallization 2m to the substrate 2. Subsequently, applying a first sacrificial layer 9 and applying a first layer 15 of an electrically and thermally conductive layer 8 to the first sacrificial layer 9. The electrically and thermally conductive layer 8 may be made of metal. In this case, the application of the first sacrificial layer 9 by deposition

done (eg by CVD or similar methods). The application of the first layer 15 can be done by deposition, in particular by ALD. b) structuring the first layer 15 of the electrically and thermally conductive layer 8. From this first layer 15, the at least one laterally extending element 5 can be formed. This in turn can form a lower turn for the vertical meander. The vertical meander or many juxtaposed vertical meanders form the spacer 4. c) application (for example by deposition) of the second sacrificial layer 10 and application (for example by deposition) and structuring of the membrane 3. This can be an optional protection and sensor layer 3a, 3b. The sensor layer 3b may consist of a semiconductor material. d) Attachment (for example by etching) of holes 7. This can be done for example by means of the Bosch or gyro process. The walls of the holes 7 can be coated later. This can be done, for example, by atomic algae deposition (ALD). In this case, a hole 7 can be etched through the first and second sacrificial layers 9, 10 to the metallization 2m of the substrate 2 and in each case two holes 7, which are each a laterally extending element 5 terminated. e) deposition of a second layer 25 of the electrically and thermally conductive layer 8, preferably by means of ALD. This can serve to electrically connect the membrane 3 with the metallization 2m of the substrate 2. f) structuring of the second layer 25 of the electrically and thermally conductive

This allows a meandering path to form over the spacer sections 14z and the laterally extending element or elements 5. This is preferably as long as possible. In this case, an electrical path from the membrane 3 through the described structures having in each case a laterally extending element 5 and two spacers 14 go. The two spacers 14z are ended downwardly in the direction of the substrate 2 by the laterally extending element 5. As a result, the structures described can be electrically connected in series up to the spacer 14d which extends from the top side of the second sacrificial layer 10 to the metallization 2m. By means of this continuous spacer 14d, therefore, an electrical connection to the metallization 2m is achieved. The structures described can form from the membrane 3 from meandering form from the top of the second sacrificial layer 10 in the direction of the boundary between the first and second sacrificial layer 9, 10. Overall, a loop-shaped electrical path up to the metallization 2m can be achieved.

In other words, in this embodiment, a plurality of nanotubes can be arranged in a vertical meander. This requires 2n + 1 nanotubes, with the first nanotube making contact with the ROIC and the last nanotube making contact with the sensor layer. A step for this is the division of the sacrificial layer into two parts, wherein after the first part in some areas an electrically conductive layer is generated, which is used for a turn of the meander. A possible process sequence is outlined below (without restricting the general public to an example of three nanotubes):

Deposition of the first part of the sacrificial layer and of an electrically conductive layer (eg metal),

• structuring of the electrically conductive layer so that the lower turn for the vertical meander is created,

Deposition of the second part of the sacrificial layer as well as deposition and structuring of a protective and the sensor layer,

• Etching of holes whose walls later by means of atomic layer deposition be coated, for example by means of the BOSCH process,

Atomic layer deposition of an electrically conductive layer, and

• structuring of an electrically conductive layer. 3. Vertical meander nanotube bolometer with sunken membrane

The embodiment shown in FIG. 6 is relatively similar to the embodiment shown in FIG. 5. However, the diaphragm 3 is located between the first sacrificial layer 9 and the second sacrificial layer 10 to be closer to the substrate thereafter than a location of maximum distance of the spacer. Furthermore, in the present case, the electrical path of the spacer has only one loop which, in contrast to FIG. 5, points towards the substrate or is open. The end product before etching is shown in FIG. 6 g). A first laterally extending element 5 between the first sacrificial layer 9 and the second sacrificial layer 10 contacts the membrane 3 electrically. In order to be able to contact this laterally extending element 5 to the outside, a first spacer section 14e can be provided, which can penetrate through the second sacrificial layer 10 as far as an upper, second, laterally extending element 5. A further, continuous spacer section 14d is provided which leads from the outwardly facing surface of the second sacrificial layer 10, ie from the upper element 5, to the metallization 2m of the substrate 2. Between these two spacer sections 14e, 14d there could be further structures, each consisting of two spacer sections 14z and in each case one further laterally extending element 5, which could likewise be arranged in the height between the first and the second sacrificial layer 9, 10 , For example, two further holes 7 could be realized by the second sacrificial layer 10, which are then lined with conductive material to form further spacer sections 14z. In this way, the spacer of a laterally extending elements 5, such as webs, mechanical, electrically and thermally switched into rich spacer cuts 14 have. In other words, the spacer may communicate with interposed portions via the spacer portion 14e, which is directly connected to the diaphragm 3 via a laterally extending member 5, and the spacer portion 14d, which leads from the surface of the second sacrificial layer 10 to the metallization 2m 14z again with intermediate therebetween laterally extending elements. In this way, the electrical path and thus the thermal resistance can be increased or increased or the thermal conductance of the electrical path can be reduced. In terms of process technology, such a structure can be produced as shown in FIGS. 6 a) -f): a) If not yet present, a sacrificial layer 9 can be applied to a metallization 2m of a substrate 2. This can be deposited. Here, the substrate 2, as in the other embodiments, an integrated readout circuit 6 (Engl .: Read Out Integrated Circuit, short: ROIC) included. b) Application or Deposition of the Membrane 3. This can be done by applying, in particular depositing, for example, first an optional protective oxide 3b and then a sensor layer 3a to the optional protective oxide 3b (as in FIG. 5, except that in FIG In the embodiment illustrated here, the membrane 3 can be deposited on the first sacrificial layer 9 instead of on the second sacrificial layer 10). The sensor layer 3a may comprise semiconductor material. c) application (for example by deposition) and structuring of a first

Layer 15 of an electrically and thermally conductive layer 8. Thus, the laterally extending elements 5 can be formed from the electrical first layer 15 of the electrically and thermally conductive layer 8, which can contact at least the membrane 3 and / or which the turns can form for the optionally present in each case two spacer sections 14z, which are to penetrate only the second sacrificial layer 10. For depositing the electrically and thermally conductive layer 8 ALD can be used. d) application and / or deposition of the second sacrificial layer 10 on the previously produced arrangement. e) structuring of the second sacrificial layer 10. This can include etching of holes 7, for example by means of DRIE (preferably the Bosch process) or by means of ion etching. In this case, a hole 7 penetrate both through the first and second sacrificial layer 9, 10 and another hole 7 can only penetrate through the second sacrificial layer 10 to the lateral element 5, which electrically contacts the membrane 3. f) application, in particular deposition, and structuring of the second layer 25 of the electrically and thermally conductive layer 8. This can be done by means of lithography and / or ion etching. Thus, an electrical path can form from the membrane 3 to the metallization 2m. If multiple loops are formed over laterally extending elements 5, each contacted by two spacer sections 14z, the electrical path can be structured as follows. It can pass from the laterally extending element 5, which contacts the membrane 3, via the directly connected stand-holder section 14e to the spacer section 14d, which passes through the first and second sacrificial layers 9, 10 to the metallization 2m of the substrate 2. In between, he can electrically connect the individual structures, which in each case consist of a laterally extending element 5 and two spacer sections 14, in series. Such a structure is shown in Fig. 6g. Compared with the embodiment shown in FIG. 5f, the advantage of this embodiment in FIGS. 6f and 6g is that the reflector, which is located in FIG. 5f, for example under the diaphragm 3, ie between the diaphragm 3 and the metallization 2m, is omitted can. Namely, the metallization 2m under the diaphragm 3 of the embodiment shown in Figs. 6a-6g can function as a reflector for incident electromagnetic radiation, in particular light or infrared light. The individual structures, in particular the holes 7, can also be produced in step e). Their preparation can be carried out as the production of the structures which have been described in Fig. 5a -5f.

In other words, this embodiment is based on the previously described embodiment 2. Vertical meander nanotube bolometer. In this case, the membrane is in the first plane. 2n + 2 nanotubes are required to allow electrical contact between ROIC and the sensor layer.

One advantage is that the raised reflector can be omitted, since the lower metal can also act as a reflective layer. The distance between the membrane and the lower metal layer can be selected over the thickness of the first sacrificial layer so that the resonator condition is fulfilled. The length of the first nanotube (defined by the thickness of the two sacrificial layers) can therefore be independent of the resonator condition. be selected. The process sequence shown in FIGS. 6a to 6f shows the realization with two nanotubes in a corresponding sequence of the figures:

(Fig. 6a) Deposition of the first sacrificial layer on a substrate (ROIC). (Fig. 6b) Deposition and patterning of a protective oxide and a

sensor layer

• (Fig. 6c) deposition and patterning of an electrically conductive layer

(Figure 6d) Deposition of the second sacrificial layer. (Figure 6e) Structuring of the second sacrificial layer

• (Fig. 6f) deposition and patterning of an electrically conductive layer

With reference to FIGS. 5 and 6, radiation detectors with a substrate 2 and a membrane 3 have been described which comprise at least one spacer 14 for holding the membrane 3 spaced from the substrate 2, for making electrical contact with the membrane 3 with a contact located on the substrate and thermal insulation of the membrane 3 with respect to the substrate 2 have. The at least one spacer 14 in this case has an electrically and thermally conductive layer 8, which extends in a cutting surface perpendicular to the substrate 2 in a loop shape through the at least one spacer 14. The cut surface can run bent, but also be a plane, namely the cutting plane of the figures shown. An electrical path through the at least one spacer 14 in the cut surface, ie the path resulting from the intersection of said cut surface with the layer 8, via which the membrane 3 is contacted with a contact or a circuit on or in the substrate, is longer than a distance between substrate 2 and membrane 3 (as an effect of the loop-shaped formation). The at least one spacer 14 is formed from a series of laterally spaced pillars or sections 14, which are connected in pairs at their upper ends or lower ends in order to form a loop together with this element. At least two columns are connected in this way via a laterally extending element 5 at its upper or lower end. The laterally extending element 5 could for example be between 10% and 50% or between 20 and 40% or be arranged between 25 and 30% of the distance between the membrane 3 and substrate 2 from the substrate 2 away. Since the laterally extending element may be arranged relatively close to the substrate 2 in this aspect, the electrical path formed by the individual pillars may be relatively long. Thus, a high thermal resistance of a single column, or by a column, a laterally extending element 5 and another connected to the laterally extending element 5 column (thus also the entire structure) can result. It would be possible for a laterally extending element 5, which connects two upper or two lower ends of sections or columns of the spacer 14, to extend at least partially under the membrane 3 in order to form a reflector. It would also be possible for a laterally extending element 5, which connects two upper or two lower ends of sections or columns of the spacer 14, to be equidistant from, or farther from, the substrate 2, as compared to FIG the membrane 3. The laterally extending elements 5, over which the electrical path leads from the membrane 3 to the substrate 2 through the spacer 14, can or may (in the case of several in the sense of their cumulative resistance) also here For example, less contribute to a thermal resistance of the spacer 14 than a sum of the thermal resistances of the spacer sections 14 z columns, that is, the spacer portions 14z are each of the type as already described, which are designed, not just the electrical line between membrane 3 and substrate 2 to allow, but also to reduce the thermal conductivity as possible. A cross section of the electrically conductive material 8 of the individual section or columns is for example less than or equal to 7 μηι ² or less than or equal to 3 μηι ² or less than or equal to 0.8 μηι ² chosen to achieve a suitable thermal resistance behavior, Of course, other values are also conceivable.

For all embodiments described so far is that the laterally extending element 5 may be formed as a web. Its length may be at least 2 times its width or more than 5, 10 or 20 times the width. This has the advantage that the smaller its width and the greater its length, the greater the thermal resistance of a laterally extending element 5. Thus, when the contacting is formed, for example, by the pillars, spacer sections 14z and or spacers 4, 14, 14e at opposite ends of the ridge, the full length of the ridge or laterally extending element 5 can be used as a thermal resistor. 4. Concentric vertical meander nanotube bolometer with unbroken symmetry (Figures 7a to 7j)

5. Concentric Vertical Meander Nanotube Bolometer with Broken Symmetry (Figures 8a to 8d)

FIGS. 7a-7j and 8a-d show so-called concentric vertical meander nanotube radiation detectors. These differ from the embodiments shown in FIGS. 5a-5f and 6a-6g. a. in that the individual layers of an electrically and thermally conductive layer 8 are at least partially arranged in one another so that a loop-shaped, substantially coaxial structure can form, in which the electrical path from the membrane 3 to the metallization 2m of the In this case, the spacer 14 may in turn be formed in a columnar shape, wherein on the wall of the column 45, the individual layers of the electrically and thermally conductive layer 8 are arranged so spaced that a long electrically conductive path from the membrane 3 to the metallization 2m of the substrate 2 can be achieved with a small area requirement in the plan view (xy plane) or laterally, again considered in the above-mentioned sectional area perpendicular to the substrate. Since the individual layers 15, 25, 35 of the electrically and thermally conductive layer 8 on the wall of the column 45, which forms the spacer 14, coaxially about the axis z of an etched into the first sacrificial layer 9 hole 7 may be arranged, an electric Path can be formed, which can multiply substantially from the outwardly facing surface (in the plan view in the axial direction of the spacer 4) of the first sacrificial layer 9 to the metallization 2m of the substrate 2 go. Thus, the path which is formed by the first sacrificial layer 9 can be used several times for the electrical path.

At least two different embodiments can be formed: On the one hand such a radiation detector 1 with unbroken symmetry (see Fig. 7) and on the other hand a radiation detector 1 with a broken symmetry (see Fig. 8). In the embodiments illustrated in FIGS. 7 and 8, the inner walls of the electrically and thermally conductive layer 8 can be lined with a sacrificial layer 10, 11 during manufacture, so that then the respective next layer of the electrically and thermally conductive layer 8 is deposited can be. This can in principle be repeated several times. Thus, by repeatedly repeating the deposition of an opaque ferschicht 10, 1 1 and subsequent deposition of an electrically and thermally conductive layer 8 a loop-shaped structure can be achieved, which in a narrow space in plan view (ie in the xy plane) several times the distance from the metallization 2m to the opposite surface of the first sacrificial layer. 9 can cross. This can lengthen the electrical path and thus lead to an increased thermal resistance or a low thermal conductance. In terms of process, the structure shown in FIG. 7j can be generated in a multi-stage process. This can be done in the steps illustrated in FIGS. 7a to 7j, and described below: a) if necessary, application of a first sacrificial layer 9. This can be done in particular by deposition. In this case, the first sacrificial layer 9 can be deposited on a substrate 2, in particular on a metallization 2m of a substrate 2. b) Placing holes in the first sacrificial layer 9. This can be done by etching or otherwise creating a hole 7 for each spacer 4 or each column. For example, this is done by means of a DRIE process (in particular the Bosch process) or by means of ion etching. In this case, the hole 7 may be formed approximately perpendicularly through the first sacrificial layer 9. c) deposition of the first layer 15 of the electrically and thermally conductive layer 8, for example by means of atomic layer deposition (English: Atomic Layer Deposition, short: ALD) and subsequent structuring. By structuring it can be achieved that the deposited first layer 15 of the electrically and thermally conductive layer 8 is essentially formed only in the hole 7. Subsequently, a second sacrificial layer 10 can be deposited, for example by means of ALD. This can be done over the complete structure. Thus, both the first sacrificial layer 9 and the inside of the first layer 15 of the electrically and thermally conductive layer 8 in the hole 7 may be covered. d) chemical mechanical polishing. It can be achieved that on the surface, in particular in the direction of the normal of the substrate 2 (ie in the z direction), above the first sacrificial layer 9 no second sacrificial layer 10th or remains of the first layer of the electrically and thermally conductive layer 15 are located or they are removed.

Deposition of a second layer 25 of the electrically and thermally conductive layer 8. This can be done on the first sacrificial layer 9 and within the second sacrificial layer 10 in the hole 7, so that a gap 45zwa between the first layer 15 and the second layer 25 of the electrically and thermally conductive layer 8 can form.

Structuring of the second layer 25 of the electrically and thermally conductive layer 8. This can be done for example by means of lithography and / or reactive ion etching. It can thus be achieved that the second layer 25 of the electrically and thermally conductive layer 8 is formed substantially only so far outside the hole 7, that the first layer 15 of the electrically and thermally conductive layer 8 can be electrically contacted.

Deposition of a further second layer 11 of the sacrificial layer. This can be done by ALD or Chemical Vapor Deposition (CVD). Subsequently, an application or deposition and structuring of an optional protective layer 3a and a sensor layer 3b, which can form the membrane 3, can take place. The sensor layer 3b may comprise semiconductor material.

Subsequently, z. B. (ion) etching can be made within the spacer 14. As a result, the further second layer 1 1 of the sacrificial layer is removed in the hole bottom. In this case, the second electrically and thermally conductive layer 25 can be removed in the hole bottom. However, the second sacrificial layer 10 may be retained (in this etching process). This can later prevent a later deposited third layer 35 of the electrically and thermally conductive layer 8 can contact the metallization 2m of the substrate 2 electrically directly.

Deposition of a further second layer 35 of the electrically and thermally conductive layer 8. This can contact the membrane 3, in particular the sensor layer 3b, electrically and thermally. This can be deposited within the second further sacrificial layer 1 1 in the pot and the second layer of the electrically and thermally conductive layer 25 can be electrically directly within the ge Contact etched hole 7. Thus, both a gap 45zwi between the third layer 35 of the electrically and thermally conductive layer 8 and the second layer 25 of the electrically and thermally conductive layer 8 as well as a gap 45zwa between the second layer 25 of the electrically and thermally conductive layer 8 and the first layer 15 of the electrically and thermally conductive layer 8 may be present. The individual layers 15, 25, 35 of the electrically and thermally conductive layer 8 may be formed substantially cylindrical. The second and third layers 25, 35 of the electrically and thermally conductive layer 8 can now be electrically connected to one another by a common pot bottom on the side of the hole 7 facing the metallization 2m. On the opposite side, which faces outward, the second and third layer 25, 35 electrically insulated and electrically conductive layer 8 can be electrically isolated, so not directly electrically connected to each other. However, the second layer 25 of the electrically and thermally conductive layer 8 and the first layer 15 of the electrically and thermally conductive layer 8 may be electrically connected directly on the side facing outward. However, the first layer 15 of the electrically and thermally conductive layer 8 and the second layer 25 of the electrically and thermally conductive layer 8 can be electrically insulated on the side facing the metallization 2m, ie, not directly electrically connected to one another. j) structuring of the third layer 35 of the electrically and thermally conductive layer 8. In the described arrangement, only a narrow path between the membrane 3 and the spacer 14 can remain, which can be traversed by electric current. The path should therefore be narrow, since the narrower the path, the thermal resistance according to Eq. 1 is larger. This can reduce the thermal conductance of this path. However, the minimum width of the path can be limited downwards, as this should have a mechanical stability.

Finally, this step can also take place before step j) or during step j), an ion etching takes place in the perforated bottom. In this way, the third layer 35 of the electrically and thermally conductive layer 8 can be removed in the hole bottom. This serves to be introduced through the hole bottom in the intermediate layer 45zwa between the first layer 15 of the electrically and thermally conductive layer 8 and the second layer 25 of the electrically and thermally conductive layer 8 etching medium to the second sacrificial layer 10 final etch away. The further, second sacrificial layer 1 1 can be etched away without such a hole, since process technology automatically an opening between the other, second layer 35 of the electrically and thermally conductive layer 8 and the second layer 25 of the electrically and thermally conductive layer 8, which at least after etching away the first sacrificial layer 9 is accessible from the outside.

In the embodiment illustrated in FIGS. 7a-7j (see the description in step j)), therefore, a relatively small opening is available in the perforated bottom 7 in order to etch away the third sacrificial layer 11. This can be improved in the embodiment illustrated in FIGS. 8a-8d.

A radiation detector 1 is described in FIGS. 8a-8d in a so-called concentric vertical meander-shaped nanotube embodiment with a broken symmetry. In this case, the steps a) to e) of the embodiment shown in FIGS. 8a-8d do not differ from the steps already described in FIGS. 7a-7e. The embodiment shown in FIGS. 8a-8d differs from the step f) in the structuring of the second layer 25 of the electrically and thermally conductive layer 8. The manufacturing process of the embodiment shown in FIGS. 8a-8d thus becomes described from the starting product shown in Fig. 7 e). This production process may include the following additional (manufacturing) steps: a) structuring of the second layer 25 of the electrically and thermally conductive layers

Layer 8. For example, this can be done by means of lithography and / or reactive ion etching. In this step, the cylindrical structure is broken. Thus, it is only etched in a part of the nanotube or spacer 45. The structuring may be done so that the second layer 25 of the electrically and thermally conductive layer 8 in a portion of the spacer 14 can be etched away. Thus, from the outside, ie from above the entire arrangement and above the first sacrificial layer 9, access to the second sacrificial layer 10 can exist between the first layer 15 and the second layer 25 of the electrically and thermally conductive layer 8 to form a gap 45zwa. The opening to this intermediate space 45zwa may be formed so large that liquid, in particular etching medium, easily in the described gap 45zwa between the first and the second layer 15, 25 can get. Thus, in a final step, the second sacrificial layer 10 can be easily removed by etching, preferably chemical etching. b) application, for example by deposition, a further second sacrificial layer 1 1.

This can be deposited, for example, by means of ALD or CVD. In this case, the further second layer of the sacrificial layer 1 1 can be both the inside of the second layer 25 of the electrically and thermally conductive layer 8 in the hole

7, which forms part of the electrical path, as well cover the upper side of the structure described so far. This comprises in particular the first sacrificial layer 9 and the outward-facing, d. H. from the metallization 2 m away side of the first and second layers 15, 25 of the electrically and thermally conductive layer 8, which was deposited above the first sacrificial layer 9. Furthermore, in this method step, the membrane 3 is applied, in particular deposited. This comprises a sensor layer 3a, which can be deposited on an optional, first deposited protective layer 3b. The protective layer 3b may comprise an oxide, and the sensor layer 3a may be made substantially of semiconductor material. c) ion etching of the structure. Thus, the further second sacrificial layer 11 is removed in the perforated floor 7. In this way, access to the second layer 25 of the electrically and thermally conductive layer 8 in the hole bottom 7 can be created and this can be contacted. By ion etching can be selectively etched in the hole bottom 7, so that the further second sacrificial layer 1 1 is removed only in the hole bottom 7. However, the further second sacrificial layer 1 1 can still remain on the inner edge of the cylinder. The second layer 25 of the electrically and thermally conductive layer 8 can be electrically contacted thereon (i.e., electrical insulation can exist) by means of now deposited layers. d) applying a third layer 35 of the electrically and thermally conductive layer

8. This is preferably done by deposition in particular by means of ALD. Subsequently, the third layer 35 of the electrically and thermally conductive layer 8 is patterned. The third layer 35 of the electrically and thermally conductive layer 8 can contact the membrane 3, in particular the sensor layer 3b of the membrane 3, electrically and thermally and connect it to the bottom of the pot. As already mentioned, in the bottom of the pot, a second layer 25 of the electrically and thermally conductive layer 8 are contacted. Thus, a continuous electrical path can form from the membrane 3 to the metallization 2m of the substrate 2. The electrical path can go in the electrical flow direction of the membrane 3 via the third layer 35, the second layer 25, the first layer 15 of the electrically and thermally conductive layer 8 to the metallization 2m. In contrast to the embodiment described in FIG. 7, the electrically conductive path in the sectional area passes through the axis z of the spacer 4. The axis z is formed or virtually present in the normal direction of the substrate 2 through the hole 7. In the embodiment described in FIG. 8, the electrical path in the described sectional plane can be formed on both sides of the axis z. In FIG. 8 d), the electrical path in the described sectional area through the axis z can initially form from the membrane 3 through the side of the third layer 35 of the electrically and thermally conductive layer 8 facing the membrane 3. Subsequently, in this sectional plane, it can flow through the bottom of the pot in the direction of the second layer 25 of the electrically and thermally conductive layer 8 on the side of the axis z of the hole 7 opposite the membrane 3. Then it can form on the side facing away from the metallization 2m side of the first sacrificial layer 9 in the first layer 15 of the electrically and thermally conductive layer 8, and can form at the end to the metallization 2m. Since the electrically conductive path in this sectional area can flow both on the side facing the membrane 3 and the side facing away from the membrane 3, this structure is also referred to as concentric vertical meander nanotube radiation meters with a broken symmetry. In contrast to this, the electric current in the described sectional area in FIG. 7 can only flow on one side, which is why the embodiment of the radiation meter shown in FIG. 7 is also referred to as a concentric vertical meander nanotube radiation meter with unbroken symmetry. With reference to FIGS. 7 and 8, radiation detectors with a substrate 2 and a membrane 3 have been described which comprise at least one spacer 14 for holding the membrane 3 away from the substrate 2, for making electrical contact with the membrane 3 with a contact located on the substrate and thermal insulation of the membrane 3 with respect to the substrate 2 have. In this case, the at least one spacer holder 14 has an electrically and thermally conductive layer 8, which is loop-shaped in a sectional area perpendicular to the substrate 2 through the at least one Spacer 14 extends. The cut surface can run bent, but also be a plane, namely the cutting plane of the figures shown. An electrical path through the at least one spacer 14 in the cut surface, ie the path resulting from the intersection of said cut surface with the layer 8, via which the membrane 3 is contacted with a contact or a circuit on or in the substrate, is longer than a distance between substrate 2 and membrane 3 (as an effect of the loop-shaped formation). The at least one spacer 14 is formed as a column, in the wall of which the electrically and thermally conductive layer 8 is arranged folded. In the wall of the column 45, the electrically and thermally conductive layer 8 is folded so arranged that in a sectional area running longitudinally and through the column, the electrically and thermally conductive layer forms two loops. In FIG. 8, in a cross section of the column 45, the electrically and thermally conductive layer 8 forms at least three rings 45r, wherein intermediate spaces 45zw between the rings 45r belong to cavities which are at least partially open at an end facing away from the substrate 2, via which opening the sacrificial material removal is facilitated as described.

In other words, in the fourth embodiment, which describes the unbroken symmetry vertical vertical meander nanotube bolometer (see FIGS. 7a to 7j), a plurality of concentric nanotubes of different diameters isolated from each other can be realized, which are nested one inside the other Nanotubes corresponds. One step in this form of realization is the occupation of the nanotube interior walls with a sacrificial layer, which can be removed during the later release. A possible embodiment for the production is described below by way of example with reference to FIGS. 7a to 7j:

• (Fig. 7a) deposition of a sacrificial layer

• (Fig. 7b) etching the holes whose walls can later be coated by, for example, atomic layer deposition, e.g. by means of the BOSCH process

• (Fig. 7c) deposition of a first conductive layer by means of, for example, atomic layer deposition and optionally subsequent structuring. Deposition of a sacrificial layer by atomic layer deposition

• (Fig. 7d) Chemically mechanical polishing • (Fig. 7e) deposition of another layer of an electrically conductive layer

Structuring of the electrically conductive layer by means of, for example, lithography and reactive ion etching (FIG. 7 g) deposition of a further layer of a sacrificial layer by means of

Atomic layer deposition and chemical vapor deposition. Deposition and structuring of a protective and sensor layer

• (Figure 7h) ion etching of the entire structure to remove the sacrificial layer in the hole bottom · (Figure 7i) deposition of another layer of an electrically conductive

layer

• (Fig. 7i) structuring of the electrically conductive layer

• (Fig. 7j) ion etching for removing the electrically conductive layer in the hole bottom (this step can also be performed together with the previous one).

A problem with the fourth embodiment just described may be the opening of the bottom plate in the last processing step to allow the release of the outer sacrificial layer wall.

Alternatively, therefore, the cylindrical symmetry of the nanotube can be broken in a separate step. This leads to the fifth embodiment, which correspondingly describes a vertical meander nanotube bolometer with a broken symmetry (see FIGS. 8a to 8d).

A possible embodiment for producing such a bolometer according to the fifth embodiment is described below by way of example with reference to FIGS. 7a to 7e and 8a to 8d:

• (Fig. 7a) deposition of a sacrificial layer

• (Fig. 7b) etching the holes whose walls later by means of, for example Atomic layer deposition can be coated, for example by means of the BOSCH process

• (Fig. 7d) Chemically mechanical polishing

• (Fig. 7e) deposition of another layer of an electrically conductive layer

Structuring of the electrically conductive layer, for example by means of lithography and reactive ion etching, the cylindrical

Symmetry of the structure is broken, that is only etched in a part of the nanotube.

• (Fig. 8b) deposition of a further layer of a sacrificial layer by means of atomic layer deposition and by means of chemical vapor deposition. Deposition and structuring of a protective and sensor layer

• (Figure 8c) ion etching the entire structure to remove the sacrificial layer in the hole bottom

(Fig. 8d) Deposition of a further layer of an electrically conductive layer. (Fig. 8d) Structuring of the electrically conductive layer

6. Submerged nanotube bolometer

FIGS. 9a-9e show a further exemplary embodiment. This illustrated embodiment of the radiation detector is also referred to as a buried nanotube bolometer. This embodiment can be combined in principle with the embodiments described so far. The embodiment shown in Fig. 9e) shows the finished product. However, the sacrificial layer 9 has not yet been removed. The spacer 4 is extended by an additional distance 62 which extends into the substrate 2. The total distance of the spacer 61 can therefore be composed of the distance in the normal direction of the spacer 4, starting from the upper edge of the substrate 2 to the diaphragm 3 and the additional path 62 which extends from the upper edge of the substrate 2 to the metallization 63, which is located in a recess 67 of the substrate 2. In this case, the edge of the substrate 2 is referred to as the upper edge, which may be facing the membrane 3. Thus, the electrical path may extend in the embodiment shown in FIG. 9. The thermal resistance can increase with it or the thermal conductivity of the electrical path can decrease.

In principle, a construction as finished in FIG. 9e) looks like a cross section in the sectional area as follows. A substrate 2 has at least one recess 67 which extends in the substrate 2 in a direction away from the membrane 3. At least the part of the surface of the substrate 2 which is to be facing the membrane 3 can advantageously have a metallization 64, which can serve to reflect incident electromagnetic radiation, in particular light or infrared light, back onto the membrane 3 in an advantageous development. In a development, the circuit elements of the readout circuit 6 (Engl .: Read Out Integrated Circuit, ROIC: short) may be arranged on a side facing away from the membrane of the substrate 2. In this case, at least one metallization layer 65 for contacting the circuit elements with one another is arranged at a height between the side of the substrate 2 facing the membrane 3 and the metallization 64 and the bottom of the depression of the substrate 2. With this metallization layer 65, the circuit elements can be electrically connected. Conversely, the circuit elements 6, e.g. Transistors, resistors and capacitances may be located at a level lower than the bottom of the well. The additional path 62 is also used to extend the spacer 4. Thus, a total distance 61 can be available for the spacer 4 in the normal direction, which can extend from the electrical contacting of the substrate 2 to the height at which the membrane 3 can be arranged. The entire electrical path from the membrane 3 to the contacting of the substrate 2 can thus be composed of a first layer 15 of an electrically and thermally conductive layer 8 and the spacer 4. Processually, such a structure can be produced in a process which is e.g. steps a) to e) and will now be described.

The starting point may consist in a substrate 2 on which a metallization 64 is located and in which an electrical contact for the ROIC 6 is buried. If not already present, an optional metallization 64 can be applied to a finished substrate 2, which already has a contact for the ROIC 6, on the surface of the substrate 2, in particular, deposited. This can be done by ALD or CVD. This can happen at least where later the membrane 3 is to be arranged above. In other words, the metallization 64 can now be located on the surface of the substrate 2 facing the membrane 3. With the optional metallization 64, the absorption of light by the membrane 3 is increased. In principle, the radiation detector is also functional without the optional metallization 64.

In this process step can (if not already present) etched a recess 67 in the substrate 2, so that the contact 63 of the substrate 2 is accessible. This can be done from the direction from which the spacer 4 can be attached. This can serve for contacting the metallization 63 of the substrate 2 and can thus be at least part of the connection between the membrane 3 and ROIC 6.

A first sacrificial layer 9, which covers both the electrical contacting of metal 67 of the substrate 2 and the reflector 64, is now deposited onto the structure described hitherto.

Now, a hole 7 is etched into the sacrificial layer 9. Thus, at least part of the electrical contacting surface 63 of the substrate 2 is accessible from outside. For example, the etching may be done by a DRIE process (eg, a Bosch or Gyro process) or by ion etching. In this case, the hole 7 should have a diameter, so that a spacer 4 applied in the hole 7, in particular, can be deposited. Furthermore, in this process step, before or after the etching of the hole 7, the membrane 3 is deposited. In order, an optional protective layer 3a is applied first, followed by a sensor layer 3b on the optional protective layer 3a. This can be done for example by deposition. The sensor layer 3a may comprise semiconductor material.

Finally, an electrically and thermally conductive layer 8, 15

deposited. Thus, the membrane 3, in particular the sensor layer 3b, is electrically and thermally connected to the metallic contact 63 of the substrate 2 connected. This electrically and thermally conductive layer 8,15 is now structured. This can be z. B. done by lithography or ion etching. Thus, an electrical path extending from the membrane 3 to the metallization 63 may be present. Since an additional path 62 for the entire path 61 can be added by the depression 67 in the substrate 2, the thermal resistance of the electrical path can thus increase or the thermal conductance of the electrical path can decrease. Thus, in FIG. 9, a radiation detector with a substrate 2, again with a depression and with a membrane 3, has been described, wherein the depression in the substrate 2 extends in a direction away from the membrane 3. The at least one spacer for holding the membrane 3 at a distance from the substrate 2, for electrically contacting the membrane 3 and for thermally insulating the membrane 3 with respect to the substrate 2, extends into the depression and is therefore the same membrane-to-substrate Distance longer than it would be without a depression to have a greater thermal resistance. The substrate 2 may include an integrated readout circuit 6 having circuit elements formed on a side of the substrate 2 remote from the membrane, such as on the surface, or on the surface, protected by a passivation or the like. In this case, a metallization layer 65 for contacting the circuit elements can be arranged at a height between the side of the substrate 2 facing the membrane 3 and the bottom of the depression of the substrate 2. The electrical contacting layer 65 connects or wires the circuit elements of the circuit 6.

In other words, in this embodiment, the nanotubes can not be anchored to the topmost metal layer of the ROIC but by means of an additional etch on the bottommost metal layer of the ROIC. In this way, the entire thickness of the back-end-of-line can be used for the length of the nanotubes, which can improve the thermal insulation so far.

A conceivable embodiment for producing such a buried nanotube bolometer is shown by way of example in FIGS. 9a to 9e.

For all embodiments described above, the at least one first spacer 4, 14, 14n can have a wall roughness or wall waviness, in order to promote phonon transport by means of surface scattering effects and / or a resulting surface roughness Complicate route extension. The wall ripple or wall roughness can be achieved by scallops. The curvature of the amplitude w of the scallops can be greater than 30 nm. In this case, the amplitude of the curvature of the scallops can be designed such that the resulting travel extension is greater than 5% or 10% or 20%.

A wall thickness of the at least one spacer 4, 14, 14n may be in a range between 0.1 nm and 1 μm or between 1 nm and 0.5 μm or between 10 nm and 100 nm. The respective electrically and thermally conductive layer 8 of the at least one spacer 4, 14, 14n may be coated by an etching protection layer. The radiation detector 1 may be a bolometer.

7. Scallop Nanotube Bolometer The exemplary embodiment shown in FIGS. 10a-10d teaches a radiation detector 1, in which a membrane 3 with the metallization 2m of the substrate 2 via a spacer 4 or a first layer 15 of an electrically and thermally conductive layer 8 combines. The substrate 2 may in turn include an integrated readout circuit (Engl .: Read Out Integrated Circuit, ROIC) 6. In this embodiment, which in principle can be combined with the other embodiments, the spacer 4 shown in Fig. 10d has scallops 4s. These have a preferably microscopic, arcuate configuration. As a result of this arcuate configuration of the scallop 4s on the edge of the spacer 4, phonon transport can be reduced or reduced by surface scattering effects and / or by a resulting path lengthening. In this case, the resulting path lengthening can amount to more than 5% or 10% or 20% of the direct distance d between ends of the at least one spacer 4.

A curvature of the scallops can be between 5 and 50 nm or between 10 and 35 nm or between 15 and 25 nm. Alternatively, a roughness or waviness of the at least one spacer 4 or the curvature of the scallop 4s may have an amplitude of greater than 30 nm. Thus, phonon transport can be reduced by surface scattering effects and / or by a resulting path lengthening. The scallops can be produced in a smooth sidewall process. Thus, the thermal conductance of the spacer 4 and thus also the thermal conductance of the electrical path from the diaphragm 3 to the metallization 2m of the substructure 2 are reduced. strats 2. The finished radiation meter 1, which is shown in Fig. 10 d, shows a substantially cuboidal substrate 2. On this is a metallization 2m. However, the first sacrificial layer 9 has not yet been etched, which can be done later. This metallization 2m can be brought into electrical contact with a membrane 3, which can be composed of an optional protective layer 3a and a sensor layer 3b arranged above it. The contacting can take place via the aforementioned spacer 4, which can extend in the direction of the normal of a surface of the metallization 2m and by means of a first layer 15 of an electrically and thermally conductive layer 8, which the first Ab- holder 4 with the membrane 3, in particular the sensor layer 3b, can connect.

Processually, such an embodiment can be made in a multi-step process. The starting point may consist of a substrate 2, from which, as shown in FIG. 10a, a metallization 2m is located. The possible steps will now be explained. a) applying, for example by deposition, a sacrificial layer 9 on the metallization 2m of the substrate 3 b) applying, in particular depositing, a membrane 3 on the sacrificial layer. 9

In this case, an optional protective layer 3a can be applied to the, for example, planar surface of the sacrificial layer 9, at least in a region of the exemplary planar surface, in particular, be deposited. This can preferably be done by ALD or CVD. On the optional protective layer 3a, a sensor layer 3b is applied during the application of the membrane 3. This can be done by depositing. In particular, the application or deposition takes place on the optional protective layer 3b and is preferably done by means of ALD or CVD. Thus, the sensor layer 3b is the layer which is farthest from the metallization 2m and the substrate 2. The optional protective layer 3b and the sensor layer 3a can also be structured in this process step. c) In this step, the first sacrificial layer 9 is structured. This can be done by etching a hole 7 in the first sacrificial layer 9. This happens at the point where the metallization 2m electrically and mechanically via an electrically and thermally conductive layer 15 and the spacer 4 kontak- should be. For example, the structuring of the first sacrificial layer 9 can take place by means of a DRIE (in particular a Bosch or gyro) process. In this case, the etching process is modified so that form at the edge of the normally substantially cylindrical hole 7 Scallops. Scallops are preferably called microscopic arcuate walls. This serves to significantly influence the transport of the phonons through surface scattering effects as well as through the resulting path lengthening. As a result, a small thermal conductance can be achieved. So there are in the finished hole 7 in the axial direction one behind the other rowed arcuate rings of the substantially cylindrical hole 7 available. These can be produced by chemically etching in a conventional Bosch etching process for a relatively long time, so that the preferably microscopic, arcuate rings can form through the non-directional etching direction on the edge of the hole 7. If the etching time of a conventional Bosch process in the individual steps is significantly increased in comparison to the conventional Bosch process and such etching processes are repeated several times, a substantially cylindrical hole 7 can form, which may have so-called scallop 4s on the walls. Alternatively, such a hole 7, the walls of which have scallops 4s, can be created by modifying a Bosch process by first etching in the normal direction of the metallization 2m by ion etching. This allows you to reach a certain depth (about ¹ Λ - ³ A of the length of an arc). Now it is again possible to chemically etch in order to be able to produce the arcuate structure at the edge of the previously etched hole 7 by the chemical etching. These two steps can now be repeated, so that a macroscopically substantially cylindrical hole 7 can form, which can extend from the outer surface, which can be arranged from the metallization 2m on the far side, to the metallization 2m of the substrate 2. Since, in this variant, it can additionally be ensured by the ion etching that the old, ie previously etched, arc is not chemically etched again in a renewed etching, clearer transitions between the individual arcs in the normal direction of the metallization 2m can be achieved.

In this process step, the deposition takes place, in particular by deposition, and the structuring of the electrically and thermally conductive layer 8. A first layer 15 of the electrically and thermally conductive layer 8 is separated. This can connect the membrane 3, in particular the sensor layer 3b of the membrane 3, electrically and thermally with the metallization 2m. In this case, the first layer 15 of the electrically and thermally conductive layer 8 extends at least partially over the outwardly facing surface of the first sacrificial layer 9 and over the cylindrical wall of the hole 7. The deposition can preferably take place by means of ALD, so that the walls of the Hole 7 including the arcs forming the scallop 4s, may be coated with the deposited metal of the first layer 15 of the electrically and thermally conductive layer 8. Thus, the preferably microscopic side wall roughness is formed. As a result, phonon transport is reduced by surface scattering effects and by the resulting path lengthening. The position of the electrically and thermally conductive layer 8 on the surface of the sacrificial layer 9, 10, which is 2 m away from the metallization, can be structured such that only a narrow electrical path is formed. Thus, the thermal conductance of the electrical path from the sensor layer 3b to the spacer 4 can be kept low according to Equation 4. By a small width of an electrically and thermally conductive layer 8, a small thermal conductance can be achieved. The end result is thus a spacer 4 as shown in FIG. 10d. Scallops 4s (as shown in the magnification) have a length p along the direction between the membrane and the substrate and an amplitude w of the scallop bulges measured in the lateral direction. The larger the quotient w / p, the greater the resulting path lengthening of the thermal and electrical path which the conductive material defines in the section surface perpendicular to the substrate. In other words, the higher the w / p, the more the length along which the wall of the spacer intersects the cross-sectional area, relative to the direct membrane-to-substrate distance d. According to the invention, the quotient w / p can be chosen and set by implementing, for example, the Bosch process, that the resulting travel extension is greater than 5% or 10% or 20%. In other words, in the electrically conductive layer in the wall of the spacer by the conformal deposition by means of, for example, ALD, the roughness in the wall of the sacrificial layer hole, as caused by, for example, the Bosch process, manifests in a corresponding ripple to that described Path extension leads - the Scallops. This embodiment, in which a lower thermal conductivity of the spacer 4 can be achieved by the scallop 4s, can be combined with all other embodiments. In other words, in this embodiment of a scallop nanotube bolometer, the Bosch process used to etch the sacrificial layer can be varied such that the process-related "scallops" significantly increase the sidewall roughness. In this case, the transport of the phonons is significantly affected by surface scattering effects, allowing a lower thermal conductance to be achieved. In addition, the effective nanotube length is increased, which further minimizes the thermal conductance.

A conceivable embodiment for producing such a scallop nanotube bolometer will be described below by way of example with reference to FIGS. 10a to 10d:

• (Fig. 10a) Deposition of the sacrificial layer

• (Fig. 10b) Deposition and structuring of a protective oxide and a sensor layer

• (Figure 10c) structuring of the sacrificial layer (e.g., by the Bosch process)

• (Fig. 10d) Deposition and structuring of an electrically conductive layer

In summary, all aspects, embodiments, developments and features, as far as technically feasible, can be combined with each other. It is Z. B. conceivable that Scallops 4s are also formed in the in Fig. 4 ad, 5 af, 6 ag, 7 aj, 8 ad and 9 ae embodiments shown. In particular, it is conceivable that the individual layers of the nested cylinders in the exemplary embodiments, which are shown in Fig. 7 aj or 8 ad, are formed with Scallops 4s. This is possible at least in the case of the first layer 15 of the metallization in FIGS. 7 aj and 8 ad. In Fig. 4 ad, this is possible both in the first section 4a and in the second section 4b of the spacer 4. In FIGS. 5 af and 6 ag, a configuration with scallops 4s is possible for all spacers. In the embodiment shown in Fig. 9 ae it is also possible with the spacer 4 to design this with arcuate scallops. Also, a combination with a recessed into the substrate spacers, as shown in Fig. 9 ae, with the other embodiments of Fig. 4 ad to Fig. 8 ad and Fig. 10 ad possible.

All aspects, embodiments, variants and developments are also possible according to the invention with a membrane 3, which comprises only one sensor layer 3b, but no protective layer 3a. The invention may be further realized in the form of the following embodiments:

1 . Radiation detector (1) comprising:

a substrate (2) and a membrane (3),

at least one spacer (4) for holding the membrane (3) at a distance from the substrate (2), for electrically contacting the membrane (3) and for thermally insulating the membrane (3) with respect to the substrate (2),

wherein in one direction between substrate (2) and membrane (3) the at least one spacer (4) is divided into a first section (4a) and a second section (4b) whose length is in each case less than a distance between substrate ( 2) and membrane (3) bridged,

wherein the first and second portions (4a, 4b) are laterally offset from each other and connected by a laterally extending member (5) so that the first and second portions (4a, 4b) are electrically connected in series via the laterally extending member (5) are switched,

and wherein the laterally extending element (5) contributes less than or equal to a thermal resistance of the at least one spacer (4) as a sum of the thermal resistances of the first and second sections (4a, 4b).

2. Radiation detector (1) according to embodiment 1, wherein a cross-section of electrically and thermally conductive material (8) of the first and second sections (4a, 4b) is less than or equal to 7 μηι ² or less than or equal to 3 μηι ² or less than or equal as 0.8 μηι ² .

3. A radiation detector (1) according to embodiment 1 or 2, wherein the laterally extending element (5) is more than 25% of the distance or more than 30% of the distance or more than 45% of the distance of both the substrate (2) also the membrane (3) is removed or arranged substantially centrally between substrate (2) and membrane (3), or wherein the laterally extending element (5) between the membrane (3) and the substrate (2) at a distance between 1 and 2.5 μηι of the membrane (3) and / or more than 2.5 μηι away from the substrate is arranged.

Radiation detector (1) according to one of the preceding embodiments, wherein the laterally extending element (5) is designed as a reflector (5a) for incident electromagnetic radiation.

Radiation detector (1) having

a substrate (2) and a membrane (3),

- At least one spacer (14) for holding the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermal insulation of the membrane (3) with respect to the substrate (2), wherein the at least one Spacer (14) has an electrically and thermally conductive layer (8) which extends in a cut surface perpendicular to the substrate (2) loop-shaped through the at least one spacer (14), so that an electrical path through the at least one spacer ( 14), over which the membrane (3) is contacted, is longer than a distance between the substrate (2) and membrane (3).

A radiation detector (1) according to embodiment 5, wherein the at least one spacer (14) is formed of a series of laterally spaced pillars connected in pairs at their upper ends or lower ends, at least two pillars extending over a laterally extending element (5). connected at its upper or lower end.

Radiation detector according to embodiment 6, wherein the laterally extending element (5) removes between 10% and 50% or between 20 and 40% or between 25 and 30% of the distance between membrane (3) and substrate (2) from the substrate (2) is arranged, or wherein the laterally extending element (5) between the membrane (3) and the substrate (2) at a distance between 1 and 2.5 μηι from the membrane (3) and / or from the substrate more than 2, 5 μηι is arranged away. A radiation detector (1) according to any one of embodiments 6 or 7, wherein the laterally extending member (5) extends at least partially under the diaphragm (3) to form a reflector. A radiation detector (1) according to embodiment 6, wherein the laterally extending element (5) is equidistant or farther from the substrate (2) than the membrane (3). Radiation detector (1) according to one of the embodiments 2 to 4 or 6 to 9, wherein the laterally extending element (5) is designed as a web whose length is at least 2 times its width or more than the 5 or 10 or 20 times the width is. Radiation detector (1) according to embodiment 5, wherein the at least one spacer (14) is formed as a column, in the wall of which the electrically and thermally conductive layer (8) is arranged folded. Radiation detector (1) according to embodiment 1 1, wherein in the wall of the column (45), the electrically and thermally conductive layer (8) folded is arranged so that in a sectional surface which extends longitudinally and through the column, the electrically and thermally mixed conductive layer forms two loops. Radiation detector (1) according to embodiment 1 1, wherein in a cross section of the column (45) the electrically and thermally conductive layer (8) at least three rings (45r) forms and spaces (45zw) between the rings (45r) to cavities, the are at least partially open at an end facing away from the substrate (2). Radiation detector (1), comprising:

a substrate (2) with a depression,

a membrane (3),

the depression in the substrate (2) extending in a direction away from the membrane (3),

and at least one spacer (4, 14) for holding the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermal insulation of the membrane (3) with respect to the substrate (2), wherein the at least one spacer (4, 14) extends into the recess.

15. Radiation detector according to embodiment 14, wherein the substrate (2) has an integrated read-out circuit (6) which has circuit elements which are formed on a side of the substrate (2) facing away from the membrane, wherein a metallization layer (65) for electrical connection the circuit elements are arranged at a height between the side of the substrate (2) facing the membrane (3) and the bottom of the recess of the substrate (2). 16. Radiation detector (1) according to one of the preceding embodiments, wherein the at least one spacer (4, 14, 14n) has a roughness or waviness with an amplitude of greater than 30 nm, phonon transport by surface scattering effects and / or by a resulting To reduce path lengthening. 17. Radiation detector (1) according to one of the preceding embodiments, wherein a wall thickness of the at least one spacer (4, 14, 14n) in a range between 0.1 nm and 1 μηι or between 1 nm and 0.5 μηι or between 10 nm and 100 nm. 18. Radiation detector (1) according to one of the preceding embodiments, wherein the electrically and thermally conductive layer (8) of the at least one spacer is coated by an etching protective layer.

19. A radiation detector (1) according to one of the preceding embodiments, wherein the radiation detector (1) is a bolometer.

20. Radiation detector (1) comprising:

a substrate (2) and a membrane (3),

- At least one spacer (14) for holding the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermal insulation of the membrane (3) with respect to the substrate (2), wherein the at least one Spacer (4, 14, 14n) has a roughness and / or waviness with an amplitude (w) of greater than 30 nm in order to reduce phonon transport by surface scattering effects and / or by the resulting path extension. 21. Radiation detector (1) according to embodiment 20, wherein the wall roughness or wall waviness is achieved by scallops. 22. A radiation detector according to embodiment 21, wherein an amplitude of the curvature of the scallop is greater than 30 nm.

23. A radiation detector according to embodiment 21 or 22, wherein an amplitude of the curvature of the scallop is formed so that the resulting path extension is greater than 5% or 10% or 20%.

24. A method for producing a radiation detector (1) according to one of embodiments 1 to 4, wherein the first and the second section (4a, 4b) are respectively produced by means of ALD in openings of a first and / or second sacrificial layer (9, 10). the.

25. The method of embodiment 24, wherein the first and second portions (4a, 4b) are made by etching a hole (7) in the first and / or second sacrificial layers (9, 10), wherein the etching is by a DRIE process happens, as a DRIE process a Bosch and / or Kyroprozess is used, so that in the first and / or second sacrificial layer (9, 10) Scallops are formed.

26. Method according to embodiment 24 or 25, comprising the following method steps:

-Strukturierung a first sacrificial layer (9) comprising the etching of a hole (7)

Depositing a first layer of conductive material to form a first conductive layer (15),

Structuring of the first layer of conductive material to produce a first conductive layer (15) for producing the laterally extending element (5), depositing a second sacrificial layer (10),

Etching a hole (7) into the second sacrificial layer (10) for access to the laterally extending element (5),

Depositing a second layer of conductive material to form a second conductive layer (25),

-Strukturierung the second layer of conductive material 27. A method of manufacturing a radiation detector (1) according to any one of Embodiments 5-13, wherein the electrically and thermally conductive loop-shaped layer (8) is produced by the first spacer (14) by ALD and a sacrificial layer method, wherein a first and at least a second sacrificial layer (9, 10, 1 1) are deposited, with which the shape of the loop-shaped electrically and thermally conductive layer (8) is produced.

28. A method for producing a radiation detector (1) according to embodiment 27, wherein the first and / or at least one second sacrificial layer (9, 10) are structured by etching at least one hole (7) in the first and / or at least one second Sacrificial layer (9, 10, 1 1), so that a first, second and / or third layer (15, 25, 35) of the electrically and thermally conductive layer (8) can be deposited. 29. A method for producing a radiation detector (1) according to embodiment 27 or 28, wherein the first and / or at least one further, second sacrificial layer (9, 10, 1 1) is deposited by ALD.

30. A method for producing a radiation detector (1) according to one of the embodiments 27-29, wherein the first and / or at least one further second sacrificial layer (9, 10, 1 1) are structured by means of a Bosch process and / or that the deposition the electrically and thermally conductive layer (8) by means of atomic layer deposition, chemical vapor deposition and / or physical vapor deposition happens. 31. Method for producing a radiation detector (1) according to one of the embodiments 27-30, wherein for electrically contacting the substrate (2) the at least one first spacer (14) is formed, which is composed of a series of laterally spaced columns which in pairs their upper ends or lower ends are connected, wherein at least two columns of the at least one spacer (14) are bounded by a laterally extending element (5) downwards during deposition.

32. A method for producing a radiation detector (1) according to any one of embodiments 27-31, wherein the membrane (3) by at least one of the laterally fenden elements (5) is electrically contacted by depositing a first layer of the electrically and thermally conductive layer (15) on the first sacrificial layer (9). A method for producing a radiation detector (1) according to one of the embodiments 27-32, wherein the at least one spacer (14) is produced in a multi-stage sacrificial layer method, wherein the at least one spacer (14) is deposited as a column in the multi-stage Method on a wall of the column, the electrically and thermally conductive layer (8) is deposited folded. A method of manufacturing a radiation detector (1) according to embodiment 33, comprising:

Depositing a first sacrificial layer (9) on the substrate (2),

Etching at least one hole (7) into the first sacrificial layer (9),

Depositing a first layer of the electrically and thermally conductive layer (15) to produce the first ring (45r) of the first spacer (14) and then depositing the second sacrificial layer (10),

Depositing a second layer of the electrically and thermally conductive layer (25) to produce the second ring (45r) of the column (45),

Deposition of a further, second sacrificial layer (11),

Depositing a third layer of electrically and thermally conductive layer (35), and structuring the third layer of the electrically and thermally conductive layer (35). Method for producing a radiation detector (1) according to embodiment 34, comprising: before, after or during structuring of the third layer of the electrically and thermally conductive layer (35) removing the third layer of the electrically and thermally conductive layer (35) in the hole bottom such that the electrical path can form in said sectional area on one side of an axis (z) of the first spacer (14). Method for producing a radiation detector (1) according to one of the embodiments 34 or 35, wherein the removal of the second and / or third layer of the electrically and thermally conductive layer (25, 35) takes place in the hole bottom by ion etching. 37. A method for producing a radiation detector (1) according to embodiment 34, wherein the second layer of the electrically and thermally conductive layer (25) in an additional step, which takes place directly after deposition, is selectively structured, for example by means of lithography and / or reactive ion etching, wherein the cylindrical symmetry of the structure is refracted by only a portion of the second layer of the electrically and thermally conductive layer (25) is removed during structuring.

38. A method for producing a radiation detector (1) according to one of the embodiments 34-37, wherein after depositing the first layer of the electrically and thermally conductive layer (15) and depositing the second sacrificial layer (10), but before depositing the second layer the electrically and thermally conductive layer (25), a chemical mechanical polishing of the surface of the radiation detector (1) takes place.

39. A method for producing a radiation detector (1) according to any one of embodiments 25-38, wherein the structuring of the layers of the electrically and thermally conductive layer (15, 25, 35) by means of lithography and / or reactive ion etching is done.

40. A method for producing a radiation detector (1) according to one of embodiments 25-39, wherein after the deposition of the first, second or further, second sacrificial layer (9,10, 1 1) one, preferably in order, protective and / or Sensor layer (3a, 3b), which form the membrane (3) are deposited.

41. Method for producing a radiation detector (1) according to one of embodiments 14 to 23, wherein an electrically and thermally conductive layer (8) which forms the at least one spacer (14) is deposited up to or into the recess.

42. A method for producing a radiation detector according to any one of embodiments 20 to 23, wherein during manufacture holes (7) for the deposition of Spacers (14) are thus etched into a sacrificial layer (9) on the substrate (2) so that the spacers (14) have a wall roughness or waviness after deposition into the holes (7) for phonon transport by surface scattering effects and / or reduce by a resulting path extension.

Method for producing a radiation detector (1) according to one of the embodiments 21 to 42, wherein an etching protection layer is deposited on the at least one spacer (14) and / or the individual layers of the electrically and thermally conductive layer (15, 25, 35).

Claims

claims

Radiation detector (1) having

a substrate (2) and a membrane (3)

at least one nanotube spacer (4) for supporting the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermally insulating the membrane (3) with respect to the substrate (2),

wherein in one direction between substrate (2) and membrane (3) the nanotube spacer (4) is divided into a first section (4a) and a second section (4b) whose length is less than a distance between substrate (2 ) and membrane (3) bridged,

wherein the first and second portions (4a, 4b) are laterally offset from each other and connected by a laterally extending member (5) so that the first and second portions (4a, 4b) are electrically connected in series via the laterally extending member (5) are switched, and

wherein the laterally extending element (5) contributes less than or equal to a thermal resistance of the nanotube spacer (4) as a sum of the thermal resistances of the first and second sections (4a, 4b).

Radiation detector (1) according to claim 1, wherein a cross-section of electrically and thermally conductive material (8) of the first and second sections (4a, 4b) is less than or equal to 7 μηι ² or less than or equal to 3 μηι ² or less than or equal to 0 , 8 μηι ² is.

A radiation detector (1) according to claim 1 or 2, wherein the laterally extending element (5) is more than 25% of the distance or more than 30% of the distance or more than 45% of the distance of both the substrate (2) and the membrane (Fig. 3) or substantially midway between the substrate (2) and membrane (3), or wherein the laterally extending element (5) between the membrane (3) and the substrate (2) is spaced between 1 and 2.5 μηι of the membrane (3) and / or more than 2.5 μηι away from the substrate is arranged.

Radiation detector (1) according to one of the preceding claims, wherein the laterally extending element (5) is designed as a reflector (5a) for incident electromagnetic radiation.

Radiation detector (1) having

a substrate (2) and a membrane (3)

- At least one spacer (14) for holding the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermal insulation of the membrane (3) with respect to the substrate (2), wherein the at least one Spacer (14) has an electrically and thermally conductive layer (8) which extends in a cut surface perpendicular to the substrate (2) loop-shaped through the at least one spacer (14), so that an electrical path through the at least one spacer ( 14) over which the membrane (3) is contacted is longer than a distance between substrate (2) and membrane (3), said spacer (14) being formed of a series of laterally spaced columns (14z) arranged in pairs are connected at their lower ends facing the substrate (2), wherein at least two columns (14z) are connected via a laterally extending element (5) at their lower end facing the substrate (2).

A radiation detector (1) according to claim 5, wherein the spacer (14) further comprises a continuous spacer portion (14d) extending continuously between the membrane (3) and the substrate (2).

A radiation detector according to claim 5 or 6, wherein one end of a structure (5, 14z) consisting of the two spacer sections (14z) and the lateral element (5) is connected to the membrane (3), and the other end of this structure (5 , 14z) is connected to the continuous spacer section (14d).

Radiation detector (1) according to one of claims 5 to 7, wherein the spacer sections (14z) and the continuous spacer section (14d) are designed as nanotubes.

Radiation detector according to one of claims 5 to 8, wherein the laterally extending element (5), between 10% and 50% or between 20 and 40% or between 25 and 30% of the distance between the membrane (3) and substrate (2) from the substrate (2) is arranged remotely, or wherein the laterally extending element (5) between the membrane (3) and the substrate (2) at a distance between 1 and 2.5 μηι from the membrane (3) and / or from the substrate more than 2 , 5 μηι is arranged away.

A radiation detector (1) according to any one of claims 5 to 9, wherein the laterally extending element (5) extends at least partially under the membrane (3) to form a reflector.

Radiation detector (1) comprising a substrate (2) and a membrane (3)

at least one spacer (14) for holding the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermal insulation of the membrane (3) relative to the substrate (2), wherein the at least one spacer (14) an electrically and thermally conductive layer (8) extending in a cut surface perpendicular to the substrate (2) looped through the at least one spacer (14), so that an electrical path through the at least one spacer (14), via which the membrane (3) is contacted, is longer than a distance between the substrate (2) and the membrane (3), the spacer (14) being formed of a series of laterally spaced columns (14z) arranged in pairs at their ends Substrate (2) facing lower ends are connected, wherein at least two columns (14z) via a laterally extending element (5) at its the substrate (2) facing the lower end are connected, and wherein the later al extending element (5) equidistant or further from the substrate (2) is spaced than the membrane (3).

Radiation detector (1) according to one of claims 2 to 1 1, wherein the laterally extending element (5) is formed as a web whose length is at least 2 times its width or more than 5 or 10 or 20 times the width is.

13. Radiation detector (1) having a substrate (2) and a membrane (3)

at least one spacer (14) for holding the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermal insulation of the membrane (3) relative to the substrate (2), wherein the at least one spacer (14) an electrically and thermally conductive layer (8) extending in a cut surface perpendicular to the substrate (2) looped through the at least one spacer (14), so that an electrical path through the at least one spacer (14), via which the membrane (3) is contacted, is longer than a distance between substrate (2) and membrane (3), and wherein the at least one spacer (14) is formed as a column, in whose wall the electrically and thermally conductive layer (8) is arranged folded.

A radiation detector (1) according to claim 13, wherein in the wall of the column (45) the electrically and thermally conductive layer (8) is folded so arranged that in a sectional area extending longitudinally and through the column, the electrically and thermally conductive layer forming two loops.

A radiation detector (1) according to claim 13, wherein in a cross section of the pillar (45) the electrically and thermally conductive layer (8) forms at least three rings (45r) and spaces (45zw) between the rings (45r) belong to cavities that abut an end facing away from the substrate (2) are at least partially open.

16. Radiation detector (1), comprising

- A substrate (2) with a recess

a membrane (3),

wherein the depression in the substrate (2) extends in a direction away from the membrane (3)

- And at least one spacer (4, 14) for supporting the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermal insulation of the membrane (3) with respect to the substrate (2) the at least one spacer (4, 14) extends into the recess, and wherein the at least one spacer (4, 14, 14n) has a roughness or waviness having an amplitude greater than 30 nm to reduce phonon transport by surface scattering effects and / or by a resulting path lengthening.

17. The radiation detector according to claim 16, wherein the substrate (2) has an integrated read-out circuit (6) which has circuit elements which are formed on a side of the substrate (2) facing away from the membrane, wherein a metallization layer (65) for electrical connection of the Circuit elements with each other at a height between the membrane (3) facing side of the substrate (2) and the bottom of the recess of the substrate (2) is arranged.

18. Radiation detector (1) according to one of the preceding claims, wherein a wall thickness of the at least one spacer (4, 14, 14n) in a range between 0.1 nm and 1 μηι or between 1 nm and 0.5 μηι or between 10 nm and 100 nm.

19. Radiation detector (1) according to one of the preceding claims, wherein the electrically and thermally conductive layer (8) of the at least one spacer is coated by an etching protective layer.

20. Radiation detector (1) according to one of the preceding claims, wherein the radiation detector (1) is a bolometer.

21. Radiation detector (1) having

a substrate (2) and a membrane (3)

- At least one spacer (14) for holding the membrane (3) spaced from the substrate (2), for electrically contacting the membrane (3) and for thermal insulation of the membrane (3) with respect to the substrate (2), wherein the at least one Spacer (4, 14, 14n) has a roughness and / or waviness with an amplitude (w) of greater than 30 nm in order to reduce phonon transport by surface scattering effects and / or by the resulting path extension.

22. Radiation detector (1) according to claim 21, wherein the wall roughness or wall ripple is achieved by scallops.

A radiation detector according to claim 22, wherein an amplitude of the curvature of the scallop is greater than 30 nm.

Radiation detector according to claim 22 or 23, wherein an amplitude of the curvature of the scallop is formed so that the resulting path extension is greater than 5% or 10% or 20%.

A method of manufacturing a radiation detector (1) according to any one of claims 1 to 4, wherein the first and second portions (4a, 4b) are each made by ALD in openings of a first and / or second sacrificial layer (9, 10).

26. A method according to claim 25, wherein the first and second portions (4a, 4b) are formed by etching a hole (7) in the first and / or second sacrificial layers (9, 10), wherein the etching is by a DRIE process happens, as a DRIE process a Bosch and / or Kyroprozess is used, so that in the first and / or second sacrificial layer (9, 10) Scallops are formed.

27. The method according to claim 25 or 26, comprising the following method steps:

- structuring a first sacrificial layer (9) comprising etching a hole (7), - depositing a first layer of conductive material to produce a first conductive layer (15) and forming the first section (4a) of the spacer ( 4)

- structuring the first layer of the conductive material to produce a first conductive layer (15) for producing the laterally extending element (5), - depositing a second sacrificial layer (10),

Etching a hole (7) in the second sacrificial layer (10) for access to the laterally extending element (5),

Depositing a second layer of conductive material to produce a second conductive layer (25) and forming a second portion (4b) of the second Nanotube running spacer (4),

- Structuring the second layer of the conductive material.

A method of manufacturing a radiation detector (1) according to any one of claims 5 to 15, wherein the electrically and thermally conductive loop-shaped layer (8) is produced by the first spacer (14) by ALD and a sacrificial layer method, wherein a first and at least a second Sacrificial layer (9, 10, 1 1) are deposited, with which the shape of the loop-shaped electrically and thermally conductive layer (8) is generated.

Method for producing a radiation detector (1) according to claim 28, wherein the first and / or at least one second sacrificial layer (9, 10) are structured by etching at least one hole (7) into the first and / or at least one second sacrificial layer (9, 10, 1 1), so that a first, second and / or third layer (15, 25, 35) of the electrically and thermally conductive layer (8) can be deposited.

Method for producing a radiation detector (1) according to claim 28 or 29, wherein the first and / or at least one further, second sacrificial layer (9, 10, 11) is deposited by ALD.

Method for producing a radiation detector (1) according to one of claims 28 to 30, wherein the first and / or at least one further second sacrificial layer (9, 10, 11) are structured by means of a Bosch process and / or that the deposition of the electrical and thermal conductive layer (8) by means of atomic layer deposition, chemical vapor deposition and / or physical vapor deposition happens.

A method of manufacturing a radiation detector (1) according to any one of claims 28 to 31, wherein for electrically contacting the substrate (2) the at least one first spacer (14) is formed, which is composed of a series of laterally spaced columns in pairs their lower ends facing the substrate (2) are connected, wherein At least two columns of the at least one spacer (14) via a laterally extending element (5) are limited downwards during deposition.

A method of manufacturing a radiation detector (1) according to any one of claims 28 to 32, wherein the membrane (3) is electrically contacted by at least one of the laterally extending elements (5) by depositing a first layer of the electrically and thermally conductive layer (15) the first sacrificial layer (9).

A method of manufacturing a radiation detector (1) according to any one of claims 28 to 33, wherein the at least one spacer (14) is produced in a multi-stage sacrificial layer process, wherein the at least one spacer (14) is deposited as a column in the multi-stage process a wall of the column, the electrically and thermally conductive layer (8) is deposited folded.

A method of manufacturing a radiation detector (1) according to claim 34, comprising

Depositing a first sacrificial layer (9) on the substrate (2),

Etching at least one hole (7) in the first sacrificial layer (9),

Depositing a first layer of the electrically and thermally conductive layer (15) to produce the first ring (45r) of the first spacer (14) and then depositing the second sacrificial layer (10)

Depositing a second layer of the electrically and thermally conductive layer (25) to produce the second ring (45r) of the column (45)

- depositing a further, second sacrificial layer (1 1)

Depositing a third layer of an electrically and thermally conductive layer (35)

- Structure of the third layer of the electrically and thermally conductive layer (35).

A method for producing a radiation detector (1) according to claim 35, comprising before, after or during structuring of the third layer of the electrically and thermally conductive layer (35), removing the third layer of the electrically and thermally conductive layer (35) in the hole bottom, so that in said sectional area on one side of an axis (z) of the first spacer (14) can form the electrical path.

A method for producing a radiation detector (1) according to one of claims 35 or 36, wherein the removal of the second and / or third layer of the electrically and thermally conductive layer (25, 35) takes place in the hole bottom by ion etching.

A method of making a radiation detector (1) according to claim 35, wherein the second layer of the electrically and thermally conductive layer (25) is selectively patterned in an additional step which occurs immediately after deposition, e.g. by means of lithography and / or reactive ion etching, wherein the cylindrical symmetry of the structure is refracted by removing only part of the second layer of the electrically and thermally conductive layer (25) during structuring.

A method of manufacturing a radiation detector (1) according to any one of claims 35 to 38, wherein after depositing the first layer of the electrically and thermally conductive layer (15) and depositing the second sacrificial layer (10) but before depositing the second layer, electrically and thermally conductive layer (25), a chemical mechanical polishing of the surface of the radiation detector (1) is performed.

Method for producing a radiation detector (1) according to one of Claims 26 to 39, wherein the structuring of the layers of the electrically and thermally conductive layer (15, 25, 35) is carried out by means of lithography and / or reactive ion etching.

A method for producing a radiation detector (1) according to any one of claims 26 to 40, wherein after the deposition of the first, second or further, second sacrificial layer (9,10, 1 1) one, preferably in order, protection, and / or sensor layer (3a, 3b) forming the membrane (3) are deposited.

A method of manufacturing a radiation detector (1) according to any one of claims 16 to 20, wherein an electrically and thermally conductive layer (8) forming the at least one spacer (14) is deposited up to or into the recess.

A method of manufacturing a radiation detector according to any one of claims 21 to 24, wherein during manufacture holes (7) for the deposition of spacers (14) are etched in a sacrificial layer (9) on the substrate (2) such that the spacers (14 ) after wall deposition into the holes (7) have wall roughness or waviness to reduce phonon transport by surface scattering effects and / or by resulting path lengthening.

Method for producing a radiation detector (1) according to one of claims 25 to 43, wherein an etching protection layer is deposited on the at least one spacer (14) and / or the individual layers of the electrically and thermally conductive layer (15, 25, 35).