Detection arrangement and method for producing detection arrangements
11486819 · 2022-11-01
Assignee
Inventors
Cpc classification
G01J3/021
PHYSICS
G01J3/42
PHYSICS
G01N21/0303
PHYSICS
International classification
Abstract
A detection assembly and a method for producing a detection assemblies are disclosed. In an embodiment a detection arrangement includes an emitter configured to generate radiation having a peak wavelength in an infrared spectral range, a detector configured to receive the radiation, a mounting surface comprising at least a first contact surface and a second contact surface for external electrical connection of the detection arrangement, a form body adjoining the emitter and the detector at least in places and deflection optics, on which the radiation impinges during operation of the detection arrangement so that an optical path is formed between the emitter and the detector by the deflection optics, wherein the deflection optics include a scattering body into which the radiation enters during the operation through a surface of the scattering body facing the emitter.
Claims
1. A detection arrangement comprising: an emitter configured to generate radiation having a peak wavelength in an infrared spectral range; a detector configured to receive the radiation; a mounting surface comprising at least a first contact surface and a second contact surface for external electrical connection of the detection arrangement; a form body adjoining the emitter and the detector at least in places; and deflection optics configured to deflect the radiation during operation of the detection arrangement so that an optical path is formed between the emitter and the detector by the deflection optics, the deflection optics covering only a portion of the optical path, wherein the deflection optics comprise a scattering body having a first surface into which the radiation enters the scattering body and a second surface from which the radiation exits the scattering body during the operation, wherein the first surface faces the emitter and the second surface is non-parallel to the mounting surface, wherein the optical path extends parallel to the mounting surface in places, wherein the scattering body comprises a crystal structure, and wherein defects in the crystal structure are configured to cause scattering.
2. The detection arrangement according to claim 1, wherein each of the emitter and the detector is electrically conductively connected via a through-connection through the form body to the first contact surface and the second contact surface, respectively.
3. The detection arrangement according to claim 1, wherein the form body is the mounting surface.
4. The detection arrangement according to claim 1, wherein the form body is arranged on a connection carrier, and wherein a side of the connection carrier, facing away from the form body, is the mounting surface.
5. The detection arrangement according to claim 1, wherein the deflection optics delimit a gas volume above the emitter and the detector on a side facing away from the mounting surface.
6. The detection arrangement according to claim 1, wherein the detection arrangement is configured to detect a gas, and wherein the peak wavelength is adapted to an absorption range of the gas.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Further embodiments and expediencies result from the following description of the exemplary embodiments in conjunction with the figures.
(2) The figures show:
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(10) The same, similar or identically acting elements are provided in the figures with the same reference signs.
(11) The figures are schematic diagrams and therefore not necessarily true to scale. Rather, the illustration of comparatively small elements and in particular layer thicknesses may be excessively large for the sake of clarity.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
(12)
(13) The detection arrangement 1 comprises an emitter 2 for generating radiation having a peak wavelength in the infrared spectral range. In the illustrated exemplary embodiment, the emitter comprises a semiconductor chip 21 with an active region 210 provided for generating radiation and a radiation conversion element 25. The radiation conversion element is provided for generating primary radiation generated in the active region 210 into secondary radiation having the desired peak wavelength of the detection arrangement. The radiation conversion element 25 has a quantum structure 29, for example, a quantum well structure or a quantum dot structure.
(14) The semiconductor chip 21 thus optically pumps the radiation conversion element 25, in particular the quantum structure 29 of the radiation conversion element.
(15) The peak wavelength of the emitted secondary radiation can be adjusted via the material composition and/or the extent of the quantum structures.
(16) In deviation from the described exemplary embodiment, however, the active region 210 of the semiconductor chip 21 can itself already provide the radiation having the desired peak wavelength so that a downstream radiation conversion element is not required for this purpose.
(17) The active region 210 of the radiation-emitting semiconductor chip 21 is based, for example, on an arsenide compound semiconductor material, a phosphide compound semiconductor material or a nitride compound semiconductor material.
(18) “Based on nitride compound semiconductors” in the present context means that the active epitaxy layer sequence or at least one layer thereof comprises a nitride III/V compound semiconductor material, preferably Al.sub.nGa.sub.mIn.sub.1-n-mN, where 0≤n≤1, 0≤m≤1 and n+m≤1. This material does not necessarily have to have a mathematically exact composition according to the above formula. Rather, it may have one or more dopants as well as additional constituents, which do not substantially change the characteristic physical properties of the material. For the sake of simplicity, however, the above formula only includes the essential constituents of the crystal lattice (Al, GA, In, N), even if they can be replaced in part by small amounts of other substances.
(19) “Based on phosphide compound semiconductors” in this context means that the semiconductor body, in particular the active region, preferably comprises Al.sub.nGa.sub.mIn.sub.1-n-mP, where 0≤n≤1, 0≤m≤1 and n+m≤1, preferably with n≠0 and/or m≠0. This material does not necessarily have to have a mathematically exact composition according to the above formula. Rather, it may have one or more dopants as well as additional constituents, which do not substantially change the physical properties of the material. For the sake of simplicity, however, the above formula only includes the essential constituents of the crystal lattice (Al, GA, In, P), even if they can be replaced in part by small amounts of other substances.
(20) “Based on arsenide compound semiconductors” in this context means that the semiconductor body, in particular the active region, preferably comprises Al.sub.nGa.sub.mIn.sub.1-n-mAs, where 0≤n≤1, 0≤m≤1 and n+m≤1, preferably with n≠0 and/or m≠0. This material does not necessarily have to have a mathematically exact composition according to the above formula. Rather, it may have one or more dopants as well as additional constituents, which do not substantially change the physical properties of the material. For the sake of simplicity, however, the above formula only includes the essential constituents of the crystal lattice (Al, GA, In, As), even if they can be replaced in part by small amounts of other substances.
(21) “Based on antimonide compound semiconductors” in this context means that the semiconductor body, in particular the active region, preferably comprises Al.sub.nGa.sub.mIn.sub.1-n-mSb, where 0≤n≤1, 0≤m≤1 and n+m≤1, preferably with n≠0 and/or m≠0. This material does not necessarily have to have a mathematically exact composition according to the above formula. Rather, it may have one or more dopants as well as additional constituents, which do not substantially change the physical properties of the material. For the sake of simplicity, however, the above formula only includes the essential constituents of the crystal lattice (Al, GA, In, Sb), even if they can be replaced in part by small amounts of other substances.
(22) For example, a compound semiconductor material, whose band gaps correspond to a wavelength in the aforementioned spectral range, for example, an antimonide compound semiconductor material, is suitable for a semiconductor chip 21 which itself generates radiation in the infrared spectral range, in particular between 1 μm inclusively and 6 μm inclusively.
(23) Alternatively suitable is, for example, a quantum structure 29 of a compound semiconductor material in which the radiation emission is effected by radiative transitions between subbands of the conduction band or of the valence band. For example, an antimonide compound semiconductor material, an arsenide compound semiconductor material or a phosphide compound semiconductor material is suitable for this purpose.
(24) The semiconductor chip 21 can be designed to emit incoherent radiation, partially coherent or coherent radiation. For example, the semiconductor chip 21 can be designed as a light-emitting diode, a superluminescent diode or a laser, in particular a surface-emitting laser. For example, the semiconductor chip 21 is designed as a quantum cascade or interband cascade diode for generating coherent radiation.
(25) The detection arrangement 1 furthermore comprises a detector 3 which is provided to detect a portion of the radiation emitted by the emitter 2. For example, an active region based on mercury cadmium telluride (HgCdTe, also referred to as MCT) or indium antimonide (InSb) is suitable for the detector.
(26) The detector 3 can also be based on intersubband transitions and be designed, for example, as a quantum well infrared photodetector (QWIP). Such detectors can be characterized by a spectrally narrowband sensitivity distribution.
(27) For a narrowband sensitivity distribution, a filter 35 can optionally be arranged on the detector 3. For example, the filter alone or in conjunction with the band gap of the material of the detector 3 forms a bandpass filter.
(28) For example, the filter 35 is formed by dielectric layers arranged on a carrier, which is transparent in the infrared spectral range. As such carriers are suitable, for example, silicon, sapphire or zinc selenide. Alternatively, another material which is transparent in the mid-infrared range, in particular between 2 μm inclusively and 6 μm inclusively, can also be used.
(29) Alternatively or additionally, the filter 35 can, for example, have a plasmonic filter.
(30) The detection arrangement furthermore comprises a form body 4 which is molded onto the emitter 2 and the detector 3 and adjoins the emitter and the detector at least in places. For example, the form body 4 has the same or substantially the same extent in the vertical direction as the semiconductor chip 21 of the emitter and/or the detector 3. The form body 4 is non-transparent, for example, predominantly reflective or predominantly absorbing, to the radiation having the peak wavelength of the emitter 2.
(31) The form body 4 forms the mounting surface 10 of the detection arrangement. On a side facing away from the mounting surface, the emitter 2 and the detector 3 are free of material of the form body.
(32) A main emission direction 91 of the emitter 2 and a main detection direction 92 of the detector 3 extend perpendicularly to the mounting surface 10.
(33) The detection arrangement 1 furthermore comprises a deflection optics 6 on which radiation emitted by the emitter 2 during operation of the detection arrangement impinges. An optical path 9 is formed between the emitter and the detector 3 by means of the deflection optics. In the exemplary embodiment shown, the deflection optics is formed by a first deflection element 61 and a second deflection element 62. In a top view of the detection arrangement, the first deflection element 61 overlaps the emitter and the second deflection element 62 overlaps the detector. For example, the first deflection element and the second deflection element are each designed as a prism, wherein the radiation emitted by the emitter 2 along the main emission direction 91 in the vertical direction is deflected in a direction parallel to the mounting surface 10 and the radiation is subsequently directed along the main detection direction 92 onto the detector.
(34) In the vertical direction, an extent of the deflection optics is, for example, between to μm inclusively and 5 mm inclusively, in particular between to μm inclusively and 1 mm inclusively.
(35) A gas volume between the first deflection element 61 and the second deflection element 62 forms an interaction region 95.
(36) Although the main emission direction 91 and the main detection direction 92 thus extend perpendicularly to the mounting surface 10, the optical path 9 extends through the interaction region 95 parallelly to the mounting surface. A small vertical extent of the detection arrangement 1 can thus be achieved in a simplified manner.
(37) Gas present in the interaction region 95 may absorb radiation emitted by the emitter so that the presence and possibly the concentration of the gas to be detected can be determined on the basis of the signal detected by the detector 3. For this purpose, the peak wavelength of the radiation generated by the emitter 2 is expediently adapted to a characteristic absorption range of the gas to be detected.
(38) For example, the gas to be detected is a carbon oxide, for example, CO or CO.sub.2, a nitrogen oxide, for example, N.sub.2O or NOX, such as NO.sub.2, or methane. Said gases have characteristic absorption ranges in the wavelength range between 2 μm inclusively and 6 μm inclusively, in particular between 3 μm inclusively and 5.5 μm. Due to the comparatively low absorption by water, the spectral range between 3 μm inclusively and 5.5 μm inclusively is particularly suitable for gas detection.
(39) The form body 4 brings about a mechanically stable connection between the emitter 2 and the detector 3 so that no further element, such as a prefabricated housing, is required. In addition, the form body 4 can simultaneously form the mounting surface 10 of the detection arrangement. This results in a particularly compact design of the detection arrangement. Furthermore, the deflection optics 6 is already integrated [into] the detection arrangement 1. In other words, the detection arrangement 1 is a compact, in particular surface-mountable, design with integrated deflection optics. Furthermore, the interaction region 95 for efficient gas detection is limited by the deflection optics.
(40) In the exemplary embodiment shown, the emitter 2 and the detector 3 each have a rear-side connector facing the mounting surface 10 and a front-side connector facing away from the mounting side. The front-side connectors are electrically conductively connected via a connection track 55 and a through-connection 41 in the form body 4 to a first contact surface 51 and a second contact surface 52, respectively. In deviation therefrom, the emitter and/or the detector can, however, also have two front-side or two rear-side connectors.
(41) Another exemplary embodiment of a detection arrangement 1 is shown in
(42) The connection carrier 7 has openings 71, by means of which the first contact surfaces 51 are electrically conductively connected to the emitter and the second contact surfaces 52 are electrically conductively connected to the detector 3. The contact surfaces are thus arranged on the side of the connection carrier facing away from the emitter 2 and the detector 3.
(43)
(44) This exemplary embodiment substantially corresponds to the exemplary embodiment described in connection with
(45) Via the inlet opening 650 of the reflector element 65, the radiation is coupled into the interaction region 95 and can impinge on the detector 3 after reflection at the reflector element 65. Via the inlet opening, a gas exchange between the environment and the interaction region 95 can also take place. On the side of the reflector element facing away from the form body 4, the detection arrangement can have a cover. In order to avoid interference radiation, the cover is expediently non-transparent to the radiation having the peak wavelength emitted by the emitter 2. For ease of illustration, the cover is not shown in the figure.
(46) In
(47) In the exemplary embodiment shown in
(48) The detection arrangement according to the exemplary embodiment shown in
(49) Of course, such a reference detector can also be used in the exemplary embodiments described above and below.
(50) A further exemplary embodiment of a detection arrangement 1 is shown in
(51) This exemplary embodiment essentially corresponds to the exemplary embodiment described in connection with
(52) In contrast to the previous exemplary embodiments, the optical path extends within the interaction region 95, i.e., not predominantly parallelly to the mounting surface but obliquely or perpendicularly thereto.
(53) In particular, the deflection optics 6 can be formed by a single optical element, namely the reflector element 65. Deflection elements, which deflect the emitted radiation of a direction perpendicular to the mounting surface in a parallel direction and vice versa, can be dispensed with.
(54) The reflector element 65 may, for example, also have the basic shape of a segment of a cylinder surface or another complex shaped structure.
(55) On the side facing away from the mounting surface 10, the further form body 66 may be flat and parallel to the mounting surface 10. As a result of the further form body 66, the detection arrangement can be comparatively mechanically robust. In addition, the picking-up during assembly, for example, by a pick and place method, is simplified. The risk of damage to the detection arrangement is thus reduced.
(56) The exemplary embodiment shown in
(57) The exemplary embodiment shown in
(58) The exemplary embodiment shown in
(59) In contrast thereto, the deflection optics 6 is formed by a scattering body 67. The radiation emitted by the emitter 2 is coupled into the scattering body via a surface 670 of the scattering body facing the emitter. After scattering within the scattering body 67, the radiation can exit through a surface 671 facing the detector 3 and impinge on the detector 3. At least one other surface 675, preferably all other surfaces of the scattering body 67, which face neither the emitter nor the detector, can be provided with a mirror layer 68. This increases the radiation portion, which impinges on the detector 3 after scattering in the scattering body 67.
(60) A semiconductor material rich in defects, such as a silicon rich in defects, is suitable as scattering body 67, for example. For example, the scattering element has the basic shape of a cube which is provided on four sides with a mirror layer and is transparent to radiation on two sides.
(61) The interaction with the gas to be measured takes place in the half-space above the detector 3.
(62) Because of the compact design of the described detection arrangement, the above-described detection arrangements 1 are in particular also suitable for operation in a mobile electronic device, for example, a mobile electrical communication device, such as a smartphone or a smartwatch, or in a product worn on the body (wearable).
(63)
(64) As shown in
(65) For ease of illustration, only a partial region of the arrangement group 15 is shown, from which precisely one detection arrangement emerges during later separation.
(66) In the exemplary embodiment shown in
(67) A casting method is generally understood as a method with which a molding compound is formed according to a predetermined shape and can be cured, if necessary. In particular, the term “casting method” includes molding, film-assisted molding, injection molding, transfer molding and compression molding.
(68) After the curing of the molding compound 40, a radiation conversion element 25 is applied to the semiconductor chip 21 in order to form the emitter 2. A filter 35 is optionally applied to the detector 3.
(69) Through-connections 41 which extend in the vertical direction through the molding compound 40 are formed in the molding compound 40. The emitter 2 and the detector 3 are electrically conductively connected to a first contact 51 and a second contact 52, respectively, via the through-connections 41 and connection tracks 55 applied to the molding compound 40. The connection tracks can in particular be applied planarly to the molding compound 40. In comparison to connecting via bonding wires, a particularly compact design can thus be achieved.
(70) In order to produce a detection arrangement as described with reference to
(71) A plurality of deflection optics 6 is subsequently assigned to the arrangement group 15. For this purpose, as shown in
(72) A reflector element 65 in the form of a reflector layer 651, for example, a metallic coating, is applied to the sacrificial layer 86 (
(73) A further form body 66 is subsequently applied to the reflector element 65. A casting method can be used for this purpose. The further form body fills in particular intermediate spaces between adjacent reflector elements 65. The further form body 66 can adjoin the form body 4 in places in these intermediate spaces. On the side facing away from the form body 4, the further form body 66 is preferably designed to be flat (
(74) The sacrificial layer 86 is subsequently removed. For example, the sacrificial layer is removed by means of a solvent. For this purpose, the solvent can be introduced via openings in the further form body 66 (cf.
(75) The removal of the sacrificial layer 86 produces an interaction region 95, which is delimited in the vertical direction by the reflector element 65.
(76) The deflection element in the form of the reflector element 65 is thus formed directly on the arrangement group 15. A compact and cost-effective production is thus simplified.
(77) Lastly, the arrangement group 15 is separated into the detection arrangement 1 along separation lines 89. During separation, the molding compound 40 and the further form body 66 are severed. This can, for example, be done by means of a mechanical method, such as sawing, chemically, for example, by means of etching or by means of coherent radiation. The side surfaces of the form bodies produced from the molding compound 40 and the side surfaces of the further form body 66 may have marks characteristic of the separation process, for example, saw marks, marks of material removal by laser radiation or of chemical material removal.
(78) In deviation from the described exemplary embodiment, the deflection optics 6 may also be arranged in prefabricated form on the arrangement group. For this purpose, the deflection optics 6 can each be assigned individually to the associated emitters or the deflection optics are provided in an optics group which is severed when the arrangement group 15 is separated.
(79) With the described method, detection arrangements 1 can be produced with a high packing density in an arrangement group. The detection arrangements arising during separation already have a deflection optics with which an optical path through an interaction region with a gas is formed.
(80)
(81) Suitable for the optical compound is, for example, a polymer material, in particular an inorganic/organic hybrid polymer. Such materials are sold, for example, under the trademark “Ormocer” by the Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. in Munich (www.ormocere.de).
(82) The described method does not necessarily have to be carried out on the arrangement group 15. Alternatively, an auxiliary carrier can also be used, from which the deflection optics 6 produced is transferred to the arrangement group 15. In this case, the deflection optics 6 can be provided with a reflective coating, for example, a metal-containing coating, prior to the application to the arrangement group. Gold is distinguished in particular by high reflectivity in the infrared range. Alternatively, the more cost-effective aluminum may be used.
(83) The invention is not limited by the description based on the exemplary embodiments. Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly specified in the claims or the exemplary embodiments.