DE10339952A1 - Infra red contactless temperature sensor for laser power control has micropeltier elements in integrated construction between insulating substrates - Google Patents

Abstract

An infra red contactless temperature sensor (1) has micro peltier elements (10) and silicon, silicon carbide or diamond substrate layers (11, 15) enclosing two different types (131, 132) of electrically connected (14) thermoelectric cells (13) and a thin lead zirconium, radiation absorbing layer (20) on the outer side of the first layer. Independent claims are included for the use of a thermistor (30) to measure the substrate temperature,a peltier element (60) to control it and a focussing element to concentrate the radiation. A laser system using the detector to provide a power control signal is also claimed.

Description

The The present invention relates to a detection device for detection of infrared radiation and a detection device comprehensive Laser system.

A device for detecting infrared radiation is out DE 196 45 036 A1 known, which comprises a pyroelectric detector element. The pyroelectric detector element has a layer structure with a layer of pyroelectric material which is arranged between two electrodes.

A The object of the invention is an alternative detection device for detecting infrared radiation and and the detecting device comprehensive To provide laser system, which are particularly suitable to be miniaturized.

These Task is in accordance with the present invention by a detection device for the detection of infrared radiation having the features specified in claim 1 and a laser system solved with the features indicated in claim 14. Preferred embodiments are the subject of the dependent Claims.

• – zumindest ein Mikropeltierelement, welches einen Schichtaufbau mit folgenden im wesentlichen parallel zueinander angeordneten Schichten aufweist: – eine erste Substratschicht; – eine zweite Substratschicht; – eine thermoelektrische Schichtanordnung, welche zwischen der ersten und der zweiten Substratschicht angeordnet ist und zumindest eine Thermoelementzelle umfaßt, wobei die zumindest eine Thermoelementzelle ein erstes Element aus einem thermoelektrischen Material eines ersten Leitungstyps und ein zweites Element aus einem thermoelektrischen Material eines zweiten Leitungstyps aufweist, wobei die Elemente der zumindest einen Thermoelementzelle mittels einer Elementverbindungsbahn elektrisch miteinander verbunden sind; und
• – zumindest eine Absorptionsschicht, welche an der der thermoelektrischen Schichtanordnung abgewandten Seite der ersten Substratschicht angeordnet und ausgelegt ist, die auf die Absorptionsschicht einfallende Infrarotstrahlung zu absorbieren.

According to the invention, there is provided a detection device for detecting infrared radiation, comprising:

• At least one micropart element having a layer structure with the following layers arranged substantially parallel to each other: a first substrate layer; A second substrate layer; A thermoelectric layer assembly disposed between the first and second substrate layers and comprising at least one thermocouple cell, the at least one thermocouple cell comprising a first element of a thermoelectric material of a first conductivity type and a second element of a thermoelectric material of a second conductivity type the elements of the at least one thermocouple cell are electrically connected to each other by means of an element connecting track; and
• - At least one absorption layer, which is arranged on the side facing away from the thermoelectric layer assembly side of the first substrate layer and designed to absorb the infrared radiation incident on the absorption layer.

Preferably comprises the thermoelectric layer assembly comprises a plurality of the thermocouple cells the thermocouple cells, wherein the thermocouple cells with a Variety of cell interconnects electrically series with each other are connected. The absorption layer can be electromagnetic radiation absorb in the near, mid, and far infrared regions. This will a temperature difference between the temperature of the first substrate layer and the temperature of the second substrate layer depending the intensity the infrared radiation incident on the absorbing layer, wherein the temperature difference by means of the Mikropeltierelements in an electrical detection signal is converted. If appropriate Also, the first substrate layer can be the absorption layer itself form. The detection signal can be between two detector contacts of the micropelt element are picked up, the detector contacts are arranged such that between the two detector contacts preferably a plurality of serially interconnected thermocouple cells is located.

The micropart element has a layer structure, wherein the layers of the layer structure formed in a substantially planar manner are arranged parallel to one another or in a stack, so that they are in contact with each other in a substantially planar manner. Such a micropelt element is produced by means of planar lithography methods, such as in DE 198 45 104 A1 is described. With regard to the construction and the production of such micropelt elements is on the DE 198 45 104 A1 referred, which is to be understood as an integral part of the disclosure of the present application.

The thermoelectric layer arrangement is characterized by a planar, Layered arrangement of thermocouple cells. In this sense the thermoelectric layer assembly is not considered to be continuous continuous layer, but as a structured layer, which a plurality of preferably spatially separate structural elements, i.e. Thermocouple cells to understand.

The thermoelectric material of the first and second elements of the thermocouple cell may be, for example, Bi ₂ Te ₃ , Bi ₂ Se ₃ , PbTe, Si, Ge, etc. Preferably, the first and second elements are formed of different (n- or p-) doped silicon. However, the first and second elements of the thermocouple cell may also comprise multiple layers of different material composition, which are selected to allow increased performance of the micropart element chen.

The Cell and element interconnects are preferably metallic or formed as highly doped semiconductor printed conductors. you will be preferably formed as a structured electrically conductive layers.

The Thermoelectric layer arrangement can be in direct or indirect Contact (by means of at least one additional (intermediate) layer) stand with the first and the second substrate layer. Preferably is the extra Layer an electrically insulating layer, e.g. a silica or Silicon nitride layer. Preferably, the absorption layer is made Lead zirconate titanate (PZT) formed. More preferred is the first and / or the second substrate layer of silicon, silicon carbide or diamond.

The the absorption layer may have a thickness in the normal direction of Layer of the layer structure of less than 200 microns, preferably less than 20 μm, and most preferably less than 2 μm or even less than 1 μm.

The Normal direction is determined by the direction in which the layers of the layer structure on top of each other are stacked, i. e. the normal direction is the direction which is perpendicular to a layer plane of the layer structure runs.

The first substrate layer preferably has a thickness in the normal direction a layer plane of the layer structure of less than 100 microns, preferably less than 50 μm, and most preferably less than 10 microns.

Thereby becomes a good thermal contact between the absorption layer and the first substrate layer and thereby ensures the sensitivity the detection device increases.

More preferably, in a section running parallel to a layer plane of the layer structure, the micropart element has a sectional area with an area of less than 2 mm ² , preferably less than 1 mm ² , and most preferably less than 0.1 mm ² .

Of the Diameter of the micropelt element is preferably in a parallel less towards the layer plane of the layer structure than 1.5 mm, preferably less than 700 μm and most preferably less as 400 μm.

One Micro-vertebrate element comprises preferably 1 to 10 thermocouple cells. A thermocouple cell preferably has a diameter in a parallel to a Layer plane of the layer structure extending direction of less as 200 microns, preferably less than 150 μm, and most preferably less than 80 microns.

The Micro-element element preferably has a total thickness in Normal direction of a layer plane of the layer structure of less than 450 μm, preferably less than 250 μm, and most preferably less than 150 microns.

Further comprises the detection device preferably at least one thermistor, which is in thermal contact with the second substrate layer and adapted to the temperature of the second substrate layer or to measure the ambient temperature. In particular, the resistance of the Thermistors a predetermined dependence on the temperature of the second substrate layer.

There the detection signal of the temperature difference between the first and the second substrate layer depends, thus the point of use the detection device can be determined. Furthermore, a monitoring and optionally a correction of the detection signal for the temperature or for Temperature variations of the second substrate layer are made. Preferably, the thermistor is not on the absorption layer exposed to incident infrared radiation.

Prefers comprises the detection device further comprises at least one additional Peltier element, which is in thermal contact with the second substrate layer and adapted to the temperature of the second substrate layer to regulate and in particular to keep substantially constant. The Zusatzpeltierelement can preferably also a Mikropeltierelement be.

The Zusatzpeltierelement works as a thermogenerator, so that a temperature difference between the two sides of the Zusatzpeltierelements by applying a potential difference between the two electrical outputs of Zusatzpeltierelemes is generated. Thus, the temperature of the in thermal contact with the second substrate layer of the microparticulate element standing side of Zusatzpeltierelements to a predetermined or predeterminable temperature, preferably to a constant low temperature, regulated and thereby the sensitivity or the signal-to-noise ratio the detection device increases become.

Further preferably comprises the detection device at least one optical filter, which designed and arranged, the spectral range of the on the Absorption layer incident infrared radiation to a predetermined or narrowable pre-definable spectral range.

Consequently can be a selective detection in selected or for the respective Measurement relevant areas of the infrared spectrum done.

The optical filter is preferably in surface contact with that of the first substrate layer side facing away from the absorption layer and is preferably substantially parallel to the absorption layer arranged at a predetermined / suitable distance in the normal direction.

Preferably comprises the detection device at least one focusing element, which designed and arranged, the incident infrared radiation to focus on the absorption layer. The focusing element (e.g., a lens or a lens group) is in the normal direction at a predetermined distance from the absorption layer on the the thermoelectric arrangement opposite side of the absorption layer arranged. Thus, a larger detection signal generates and thus greater sensitivity opposite the Infrared radiation achieved. Preferably, the detection device a focusing element and an optical filter, wherein the focusing element also could simultaneously serve as a filter.

The Detection device may preferably comprise a plurality of micro-peltier elements, which are arranged in a chain or matrix manner. On every The micropelt elements is accordingly at least one absorption layer appropriate.

at an application of the detection device as a pixel detector (e.g. as a motion sensor) the detection device preferably at least 2 × 2, preferably 3 × 3 or 4 × 4 to 10 × 10 micropelt elements, which preferably matrix-shaped are arranged. If the detection device as a matrix of band filters be used for spectral analysis, the detection device comprises - depending on the desired Number of ribbons - a variety of micropeltic elements, the distance preferably 100 microns from each other is.

• – zumindest eine Lasereinrichtung, welche zur Erzeugung von Infrarotstrahlung ausgelegt ist;
• – zumindest eine erfindungsgemäße Detektionsvorrichtung, welche dazu ausgelegt und angeordnet ist, zumindest einen Teil der Infrarotstrahlung der Lasereinrichtung zu detektieren und entsprechend der detektierten Intensität der Infrarotstrahlung ein Detektionssignal zu erzeugen.

According to the invention there is further provided a laser system comprising:

• - At least one laser device which is designed to generate infrared radiation;
• At least one detection device according to the invention, which is designed and arranged to detect at least part of the infrared radiation of the laser device and to generate a detection signal in accordance with the detected intensity of the infrared radiation.

• – eine Regeleinrichtung, welche in Signalverbindung mit der Detektionsvorrichtung und der Lasereinrichtung steht und dazu ausgelegt ist, ein von dem erzeugten Detektionssignal abhängiges Regelsignal an die Lasereinrichtung auszugeben, um die Intensität der Infrarotstrahlung der Lasereinrichtung zu regeln. Vorzugsweise ist die Regeleinrichtung dazu ausgelegt, die Intensität der Infrarotstrahlung im wesentlichen konstant zu halten.

Preferably, the laser system further comprises

• - A control device which is in signal communication with the detection device and the laser device and is adapted to output a dependent of the generated detection signal control signal to the laser device to control the intensity of the infrared radiation of the laser device. Preferably, the control device is designed to keep the intensity of the infrared radiation substantially constant.

Preferably comprises the laser device comprises a laser diode and the control device at least one Peltier element which is in thermal contact with the laser diode stands and is designed and arranged, the temperature of Laser diode to regulate.

Especially Thus, the temperature of the laser diode can be kept constant and thereby stabilizes one or more parameters of the laser diode (e.g., intensity) become. But it can also be a direct feedback of the control signal to the laser diode, for example, a regulation of the current of a pump current flowing through the laser diode to accomplish.

The inventive detection device and the laser system are particularly suitable for miniaturization. Furthermore you can the detection device according to the invention and laser system with conventional Manufacturing processes of the semiconductor industry are realized, what among other benefits like higher Integration density, compatibility with other microelectronic elements, stable parameters and lower costs due to mass production.

The Invention will be more preferred in the following with reference to accompanying drawings embodiments described by way of example. It shows:

1 a schematic representation of a first embodiment of a detection device according to the invention;

2 a schematic representation of a second embodiment of the detection device according to the invention;

3 a schematic representation of a third embodiment of the detection device according to the invention;

4 a schematic representation of a fourth embodiment, which comprises a plurality of chain-like arranged Mikropeltierelementen;

5 a schematic representation of a preferred manufacturing method of a detection device according to the invention; and

6 a schematic representation of a laser system according to the invention.

A first embodiment of the detection device according to the invention 1 is related to 1 described. The micropelt element 10 has a layered construction with a first substrate layer 11 , a second substrate layer 15 and a thermoelectric layer assembly disposed between the first 11 and the second 15 Substrate layer is sandwiched, on. The thermoelectric layer arrangement can be directly or by means of other layers with the substrate layers 11 and 15 stay in contact. Preferably, an electrically insulating layer (not shown) is between the respective substrate layer 11 . 15 and the thermoelectric layer assembly arranged. The thermoelectric layer assembly comprises a plurality of thermocouple cells 13 , wherein the thermocouple cells 13 by means of a plurality of cell connection paths 14 electrically connected to each other in series. Each of the thermocouple cells 13 has a first element 131 of a thermoelectric material of a first conductivity type (eg n-type) and a second element 132 of a thermoelectric material of a second conductivity type (eg p-type). The first element 131 and the second elements 132 a thermocouple cell 13 are each by means of an element connecting track 12 electrically connected to each other.

The micropelt element 10 is preferably - as in DE 198 45 104 A1 described - produced using Planarlithographischen manufacturing processes. The thermoelectric material is preferably deposited on two substrate wafers, preferably of silicon wafer, and subsequently structured. The substrate wafers are subsequently soldered together so that a micropelt element 10 with a plurality of serially connected thermocouple cells 13 arises.

Furthermore, the detection device 1 at least one absorption layer 20 which on the side facing away from the thermoelectric layer assembly side of the first substrate layer 11 is arranged on. The absorption layer is laid on the absorption layer 20 to absorb incident infrared radiation. The absorption layer 20 can be before or after the production or completion of the micropelt element 10 attached or applied. The absorption layer 10 absorbs the incident infrared radiation or heat radiation and converts it into heat, so that a temperature difference between the temperature of the first 11 and the second 15 Substrate layer is formed. Due to the Seebeck effect, this temperature difference generates a potential difference between detector contacts 17 and 18 of the micropart element, which is output as a detection signal. The detection signal is dependent on the intensity of the infrared radiation incident on the absorption layer. The detection signal may be sent to an external detection system 19 (eg, a voltmeter) are output.

The thickness of the first substrate layer 11 is in this embodiment, for example, about 10 microns to 50 microns.

The micropelt element 10 In this embodiment, for example, it has a diameter in a direction parallel to the layer plane of the layer structure, for example 200 μm to 1 mm.

In this embodiment, a single thermocouple cell 13 the thermoelectric layer arrangement, for example, a diameter in a direction parallel to a layer plane of the layer structure extending direction of 100 microns.

A second embodiment of the invention will be described below with reference to FIG 2 described. The detection device 1 according to this embodiment differs from the in 1 shown embodiment in that the in 2 shown detection device 1 also a thermistor 30 which is in thermal contact with the second substrate layer 15 of the micropelt element 10 stands covered. The thermistor 30 is designed, the temperature of the second substrate layer 15 or to measure the ambient temperature and is preferably not on the absorption layer 20 exposed to incident infrared radiation. Furthermore, the in 2 shown embodiment, at least one optical filter 40 , which in particular in area investment with that of the first substrate layer 11 opposite side of the absorption layer 20 is or at a predetermined or suitable distance from the absorption layer 20 can be arranged in the normal direction N. The optical filter 40 narrows the spectral range of the absorption layer 20 incident infrared radiation to a relevant spectral range for each measurement.

The incident on the absorption layer infrared radiation is by means of a focusing element 50 (For example, a lens or a lens group) on the absorption layer 20 focused. Accordingly, the focusing element 50 preferably in the normal direction N at a predetermined distance from the absorption layer 20 on the opposite side of the thermoelectric arrangement of the absorption layer 20 arranged. The fil ter 40 is preferably between the focusing element 50 and the absorption layer.

A third embodiment of the invention will be described with reference to FIG 3 described. The detection device 1 according to this embodiment differs from the in 2 shown embodiment in that the in 3 shown detection device 1 Furthermore, a Zusatzpeltierelement 60 includes. The first page 61 the Zusatzpeltierelement 60 is in thermal contact with the second substrate layer 15 of the micropelt element 10 and is adapted to the temperature of the second substrate layer 15 of the micropelt element 10 to regulate and in particular to keep substantially constant. Preferably, the Zusatzpeltierelement is also 60 formed as a micropart element. The Zusatzpeltierelement 60 can also have a built-in thermistor 70 which is in thermal contact with the second side 62 , ie the side facing away from the micropart element, the Zusatzpeltierelement 60 stands and the point of use of Zusatzpeltierelements 60 certainly.

4 shows an array of a first one 10A and a second one 10B Micro Peltier elements. The micropelt elements 10A and 10B are arranged like a chain and each have - as described above - a first absorption layer 20A or a second absorption layer 20B on. Each of the micropelt elements 10A and 10B is always with a filter 40A and 40B assigned as above regarding 2 described. The incident infrared radiation is by means of a focusing element 50A on the absorption layer 20A and by means of a focusing element 50B on the absorption layer 20B fokkusiert.

Although in 4 an array with two micropelt elements 20A and 20B can be shown, the (linear) number of Mikropeltierelemente 20 preferably greater than 2, more preferably greater than 5, and most preferably greater than 10. The micropelt elements 10 with respective absorption layers 20 can also be arranged like a matrix - with linear numbers as just mentioned.

5 shows a preferred manufacturing method of one example in 1 shown detection device. In a first step S1, a dry or wet etching of the surface of the first substrate layer 11 of the micropelt element 10 made to the thickness of the first substrate layer 11 from about 200 microns to about a few tens of microns, as in the left picture of FIG 5 is shown. In a second step S2, an application of the absorption material by sputtering, CVD / PVD, spin-on techniques, etc. is performed, as in the middle figure of 5 is shown. The finished detection device 1 which is a micropelt element 10 and an absorption layer 20 is in the right picture 5 shown.

6 shows a preferred inventive laser system, which, for example, a in 1 to 5 shown detection device 1 and a laser device 2 , which is designed to generate infrared radiation IRS includes. In particular, the laser device comprises 2 a laser diode. Part of the infrared radiation IRS generated by the laser device is transmitted to the absorption layer by a beam splitter BS 20 the detection device 1 directed. The absorption layer 20 absorbs the incident infrared radiation IRS, which causes that by means of the micropelt element 10 A detection signal is generated in accordance with the detected intensity of the infrared radiation IRS. This detection signal is sent to the control device which is in signal communication with the detection device 1 and the laser device 20 stands, spent. The control device comprises in this embodiment a Peltier element 3 , A control signal dependent on the detection signal becomes a potential difference between the electrical outputs of the Peltier element 3 created, reducing the temperature of the laser device 2 in thermal contact side of the Peltier element 3 is regulated. In particular, the temperature of the laser device 2 in thermal contact side of the Peltier element 3 and thus also the temperature of the laser device 2 kept constant.

1

detection device

2

laser device

3

Peltier element

10

Micro Peltier element

10A, 10B

Micro Peltier element

11

first substrate layer

12

Cellular communication pathways

13

Thermocouple cell

131

first Element of a thermoelectric

material a first conductivity type

132

second Element of a thermoelectric

material a second conductivity type

14

Element Verbindungsbahn

15

second substrate layer

17

Contact detector

18

Contact detector

19

detection system

20

absorbing layer

20A, 20B

absorbing layer

30

thermistor

40

optical filter

40A, 40B

optical filter

50

focusing

50A, 50B

focusing

60

Additional Peltier element

61

first Side of Zusatzpeltierelements

62

second Side of Zusatzpeltierelements

70

thermistor

S1, S2

manufacturing steps

IRS

infrared radiation

Claims (16)

Detection device ( 1 ) for the detection of infrared radiation, comprising: - at least one micropelt element ( 10 ; 10A ; 10B ), which has a layer structure with the following layers arranged essentially parallel to one another: a first substrate layer ( 11 ); A second substrate layer ( 15 ); A thermoelectric layer arrangement which between the first 11 ) and the second substrate layer ( 15 ) and at least one thermocouple cell ( 13 ), wherein the at least one thermocouple cell ( 13 ) a first element ( 131 ) of a thermoelectric material of a first conductivity type and a second element ( 132 ) of a thermoelectric material of a second conductivity type, wherein the elements ( 131 . 132 ) of the at least one thermocouple cell ( 13 ) by means of an element connecting track ( 14 ) are electrically connected to each other; and at least one absorption layer ( 20 ; 20A ; 20B ), which on the side facing away from the thermoelectric layer assembly side of the first substrate layer ( 11 ) is arranged and designed in such a way that on the absorption layer ( 20 ; 20A ; 20B ) to absorb incident infrared radiation. Detection device ( 1 ) according to claim 1, wherein the absorption layer ( 20 ; 20A ; 20B ) Contains lead zirconate titanate. Detection device ( 1 ) according to any one of the preceding claims, wherein the first ( 11 ) and / or the second ( 15 ) Substrate layer of silicon, silicon carbide or diamond is. Detection device ( 1 ) according to any one of the preceding claims, wherein the absorption layer ( 20 ; 20A ; 20B ) has a thickness in the normal direction (N) of a layer plane of the layer structure of less than 200 μm, preferably less than 20 μm, and most preferably less than 2 μm. Detection device ( 1 ) according to one of the preceding claims, wherein the first substrate layer ( 11 ) has a thickness in the normal direction (N) of a layer plane of the layer structure of less than 100 μm, preferably less than 50 μm, and most preferably less than 10 μm. Detection device ( 1 ) according to one of the preceding claims, wherein the micropelt element ( 10 ; 10A ; 10B ) has a sectional area with an area of less than 2 mm ² , preferably less than 1 mm ² , and most preferably less than 0.1 mm ² , in a section running parallel to a layer plane of the layer structure. Detection device ( 1 ) according to one of the preceding claims, wherein the thermocouple cell ( 13 ) has a diameter in a direction parallel to a layer plane of the layer structure of less than 200 μm, preferably less than 150 μm, and most preferably less than 80 μm. Detection device ( 1 ) according to one of the preceding claims, wherein the micropelt element ( 10 ; 10A ; 10B ) has a thickness in the normal direction (N) of a layer plane of the layer structure of less than 450 μm, preferably less than 250 μm, and most preferably less than 150 μm. Detection device ( 1 ) according to any one of the preceding claims, further comprising at least one thermistor ( 30 ) which is in thermal contact with the second substrate layer ( 15 ) and is adapted to the temperature of the second substrate layer ( 15 ) to eat. Detection device ( 1 ) according to any one of the preceding claims, further comprising at least one Zusatzpeltierelement ( 60 ) which is in thermal contact with the second substrate layer ( 15 ) and is adapted to the temperature of the second substrate layer ( 15 ) and in particular to keep substantially constant. Detection device ( 1 ) according to one of the preceding claims, further comprising at least one optical filter ( 40 ; 40A ; 40B ), which is designed and arranged, the spectral range of the on the absorption layer ( 20 ; 20A ; 20B ) narrowing incident infrared radiation to a predetermined or predeterminable spectral range. Detection device ( 1 ) according to one of the preceding claims, further comprising at least one focusing element ( 50 ; 50A ; 50B ), which is designed and arranged, the incident infrared radiation on the absorption layer ( 20 ; 20A ; 20B ) to focus. Detection device ( 1 ) according to one of the preceding claims comprising a plurality of micropelt elements ( 10A ; 10B ), which are arranged in a chain or matrix. Laser system, comprising: - at least one laser device ( 2 ) which is designed to generate infrared radiation; At least one detection device ( 1 ) according to one of claims 1 to 13, which is designed and arranged, at least a part of the infrared radiation of the laser device ( 2 ) and to generate a detection signal in accordance with the detected intensity of the infrared radiation. A laser system according to claim 14, further comprising - a control device which is in signal communication with the detection device ( 1 ) and the laser device ( 2 ) and is adapted to supply a control signal dependent on the generated detection signal to the laser device ( 2 ) to reduce the intensity of the infrared radiation of the laser device ( 2 ). Laser system according to claim 15, wherein the laser device ( 2 ) comprises a laser diode and the control device at least one Peltier element ( 3 ) which is in thermal contact with the laser diode ( 2 ) and is arranged and arranged to control the temperature of the laser diode.