JP2007501404A - Infrared sensor utilizing optimized surface - Google Patents

Abstract

The present invention relates to a radiation sensor comprising a detector element, for example for non-contact temperature measurement or infrared spectroscopy, an absorber element (13-16, 51, 52) that absorbs radiation and is heated, and an absorber It comprises a support (2) provided with a support surface to accommodate the elements (13-16, 51, 52). The support surface has a recess, and the absorber element (13-16, 51, 52) is such that at least part of the absorber element (13-16, 51, 52) does not touch the support (2). Thus, it is arrange | positioned on the support body surface and above a recessed part. According to the invention, the recesses have a size corresponding to at least 45% of the support surface, so that a radiation sensor of the aforementioned type generates an amplified signal on the smallest possible chip surface, Small measurement points are possible and can be manufactured with conventional standardized techniques.

Description

The present invention relates to a radiation sensor for non-contact temperature measurement or infrared gas spectroscopy, for example.

Although there are many known techniques for measuring temperature, they technically exploit many qualities where physical or chemical material properties depend on temperature. Almost all of these methods are based on the heat transfer of the measuring sensor. In so-called contact thermometers, this heat transfer is carried out through heat conduction and convection, and in the case of non-contact thermometers (radiation thermometers), heat transfer is performed.

Even though contact thermometers are generally very reliable, simplest and cost effective to manufacture, their applications are still limited. Thus, for example, there is an upper temperature limit due to the material properties of the measurement sensor, beyond which the measurement sensor can no longer operate. Moreover, contact thermometers are not suitable for measuring the temperature of objects that move at high speed or are inaccessible.

Therefore, non-contact thermometers conforming to thermal radiation are used in many applications. Any surface with a temperature T> 0K emits electromagnetic waves, so-called thermal radiation. When radiation emitted from one surface touches another surface, it is partially reflected, absorbed or transmitted. Therefore, since the heating of the absorbing element serves as evidence of the emitted infrared radiation, the absorbing element is used in a radiation thermometer that is ideally capable of absorbing regardless of wavelength and is heated by the incidence of radiation. It is done.

Radiation thermometers or so-called radiation pyrometers generally have not only a lens and a detector element with an absorbing element, but also a housing that mechanically and thermally protects the lens and the detector. In the case of these sensors, the infrared radiation emitted from the object to be measured is marked on the absorbing surface via a suitable window or optical component, so that the surface rises in temperature due to absorption. It can be seen that the radiation thermometer can also be used to measure temperatures below the self-temperature of the thermometer. In this case, the absorbing surface radiates more than it absorbs so that the absorbing surface cools as a whole.

The increase (or decrease) in temperature can be measured in different ways. In the case of a thermistor bolometer, it is the change in measured electrical resistance, for a thermo element it is the voltage at the contact point between two metal wires, and in the case of a pyroelectric detector, a special insulating crystal. This is the displacement of charge that occurs when there is a change in temperature.

The thermo element uses a so-called Seebeck effect that causes a temperature rise. The junction of two different thermoelectric material thermocouples contacts the absorption region, and the reference junction is typically the temperature of the sensor housing. The sensor output voltage of such a thermo element is so small that often many such thermo elements are connected in series. Such a series connection of many thermo elements is also called a thermo-column or thermo-pile.

In recent years, many efforts have been made in many technical fields to miniaturize electrical and electronic components, but at the same time it should be possible to manufacture them cost-effectively with known standardizable processes It is. Further miniaturization, in the case of a radiation sensor, narrows the surface of the absorber, so that the temperature rise will be small, with which the signal will be small and the resolution will be small.
Therefore, especially in the case of miniaturized sensors, it is possible to increase the absorption of infrared radiation in the absorber system as much as possible, insulate the absorber surface from the environment, increase the temperature rise as much as possible, and increase the sensor output signal. is important.

Infrared sensors with detector elements are already known, but the detector elements consist of an absorber element that is heated as a result of absorbing radiation and a support with a surface for positioning the absorber element. Thus, there is a recess on the surface of the support, and the absorber element is arranged above the recess on the surface of the support so that a part of the absorber element does not touch the support. Usually there is a membrane with very little thermal conductivity placed above the recess, on which absorber elements are placed in order. This guarantees, to a large extent, thermal separation between one absorber element and the support acting as a heat sink, while creating a high temperature difference between the absorber element and the support. Resulting in greater signal strength.

Such a sensor is already described in DE 42 21 037. This sensor is manufactured with precision mechanical technology. The detector here has a silicon support bonded to the base plate of the sensor housing.

The sensor shown in DE 42 21 037 is manufactured with the so-called wet etching technique (KOH), which results in the formation of inclined side walls in the recesses. In other words, the fin of the support surrounding the recess is tapered. However, this means that the fins actually spread on the side facing the absorber element, resulting in inadequate insulation for the absorber element or a narrowing of the effective surface.

In almost all known infrared sensors, the size of the absorber element is relatively small compared to, for example, the overall size of a chip-shaped detector, resulting in low signal utilization.

In DE 100 09 593, a support is described which acts as a heat sink, in which case the wall surrounding the recess is substantially vertical on the base plate. However, this configuration results in a relatively long distance between the absorber element edge and the silicon heat sink. In this region, there is only one film that is an unsuitable heat conductor and it has only a low absorption for infrared radiation compared to the absorber element. Therefore, the infrared radiation incident on the film is not sufficient for signal generation, and the size of the measurement point increases only on the detector chip surface, so it is not particularly suitable for application to a pyrometer. Furthermore, the shape shown in DE 100 09 593 results in a smaller effective size of the absorber element compared to the overall size of the detector element due to the very large edge of the support.

Moreover, in the case of known infrared sensors, the distance between the end of the absorber element and the silicon heat sink is relatively long. Moreover, the absorber surface is relatively narrow compared to the overall detector surface.

The solution

Therefore, based on the state of the art, the object of the invention is to produce a radiation sensor of the type mentioned at the outset and to generate an amplified signal on a surface that is as small as possible. Moreover, it is an object of the present invention to provide an infrared sensor that allows small measurement points and can be manufactured with known standardization techniques.

In the present invention, this goal has been solved as follows. That is, the recess has a surface extension on at least its side facing the absorber element, corresponding to at least 45% of the support area. In other words, by introducing the recess into the support, at least 45% of the support surface is removed. The remainder of the support surface surrounding the recess thus has an overall surface extension of up to 55% of the entire support surface. As a result, the entire sensor surface is reduced while the signal intensity is kept constant, thereby reducing manufacturing costs. It is also effective to produce the support by a dry etching process.

In a particularly preferred design shape, the recess has an inflated portion that is in the range of 45-75% of the support surface, preferably in the range of 50-70%, particularly preferably about 65%. It has been found that particularly excellent signal elements can be realized by setting the shape of the recesses and that the satisfactory stability of the support is also guaranteed.

In a particularly useful design shape, the recess has a sidewall with an angle in the range of 80 to 100 degrees, preferably in the range of 85 to 95 degrees, particularly preferably about 90 degrees with respect to the upper support surface of the support. Yes. This measurement serves to increase the ratio of the surface of the absorber element to the overall detector surface or support surface.

It has been found that the recess should be conveniently manufactured so that it extends through the entire support. In other words, the support that can be mounted on the sensor base plate has a consistent opening. This is due to the thermal conductivity of the gas present between the absorber element or membrane and the recess floor or base as it maximizes the distance between the absorber element and the support or sensor ground plate. To mitigate signal degradation.

The support is conveniently manufactured in silicon technology. Furthermore, it is advantageous if the absorber element has at least one CMOS compatible covering layer which is arranged on the at least one radiation detection functional layer in a suitable design shape.

It has proven to be particularly effective if the covering layer has a surface area of at least 30% of the overall support surface, preferably in the range of 35-70%, particularly preferably in the range of 40-60%. It was. It has to be emphasized again here that the overall support surface means the surface area of the support including the recesses.

The absorber elements described here are not necessarily used in combination with thermo-elements or thermopiles, but can also be used in combination with, for example, pyroelectric elements or bolometers.

Furthermore, tests have shown that the signal element is further strengthened if at least the floor or base of the recess is made of a material that reflects infrared radiation. This can be achieved, for example, by a metal layer, for example a gold layer suitably having a thickness of less than 1 μm.

In addition, there is a particularly preferred design shape where the sensor has a housing made from a base plate and a cap joined thereto, with a detector element or support disposed on the base plate. Here, it is effective that the base plate is configured not to reflect at least infrared radiation to the region surrounding the support. This can be achieved, for example, by manufacturing a base plate of a suitable non-reflective material. Alternatively, the base plate can be applied to the area surrounding the support using a non-reflective material, preferably lacquer or photoresist.

Other particularly preferred design shapes also realize the features of the dependent claims.

Other advantages, features, and application examples of the present invention will become apparent from the following description of preferred design shapes as well as the accompanying drawings.

FIGS. 1A and 1B show two different basic structures of an infrared sensor according to the invention in an at least partly understandable manner from the state of the art. A detector element 2 and a reference element 3 are arranged on the base plate 1 and maintain good thermal contact with the base plate for measuring the ambient temperature.

Alternatively, the reference element can be integrated into the silicon circuit 11 as shown in the design shape of FIG. 1B. This can be done together in the first stage, for example, for signal condition setting and ambient temperature compensation.

The mechanical connection between the reference element 3 and the base plate 1 preferably uses a conductive epoxy resin, for example an epoxy resin supplemented with silver. Of course, other methods such as soldering with low melting solder are possible.

The detector element 2 and the reference element 3 or the silicon circuit 11 are connected to the connection pin 5 or the connection contact surface 6 of the base plate 1 via, for example, a wire 4 which is a thin bonding wire.

The detector element 2 has a recess 40 as will be described later. The bottom of the recess 40 has a thickness of, for example, less than 1 micrometer and is coated with a very highly reflective metal layer 7.

The area of the base plate 1 surrounding the detector element 2 can be covered with a non-reflective layer 8 as in the illustrated design shape. This layer may be, for example, a lacquer or a photoresist. It is advantageous to apply the entire surface during manufacture, except for contact points for the detector element 2, reference element 3 or silicon circuit. The infrared sensor further includes a metal cap 9 made of, for example, iron, nickel, brass, or copper. The metal cap 9 is joined to the base plate 1 as firmly as possible. The cap 9 can seal the base plate 1 by, for example, welding, soldering, or bonding. There is an opening in the metal cap 9 above the detector element, in which there is a filter 10 that passes infrared radiation.

As already described and shown in FIG. 1B, the temperature reference 3 is integrated as a silicon circuit 11, for example in the form of an application specific integrated circuit or so-called ASIC, as well as amplifiers and compensation circuits as required. It can be manufactured even at the specified temperature standard.

The base plate 1 can be made from a metal or metal alloy, such as used in a standard transistor housing, for example, as shown in FIG. 1A. Examples of preferred materials are iron, nickel, cobalt, or similar materials. Alternatively, as shown in FIG. 1B, the base plate 1 can be manufactured from a ceramic or organic material, such as a printed circuit board material FR4.

2A and 2B show a preferred design shape for a sensor structure with a non-metallic carrier substrate, eg, made from standard PCB material (FR3, FR4 or ceramic). FIG. 2A is a cross-sectional view taken along line A-A ′ of FIG. 2B showing a plan view of the sensor structure. A detector element 2 and a temperature reference 3 or signal preconditioning structural element (ASIC) 11 are mounted on the PCB. A metal layer 41 is placed on the non-metallic PCB. This layer should preferably have a thickness of 20-100 μm. This metal layer can be manufactured using, for example, a copper layer often used in commercially available PCBs. The metal layer 41 extends down to the contact surface of the cap 9 below the detector element, temperature reference or ASIC.

This metal layer 41 acts to ensure a good temperature connection between the filter 9 on one side and the cap 9 with the detector element 2 and the temperature reference 3 on the other side. Particular preference is given to having a metal layer 41 that runs all the way along the base plate 1 with the exception of the individual islands 42 for providing the contacts 48 and the through passages 44.

The cap 9 is fixed to the base plate 1 by using, for example, soldering, bonding, or welding. Based on the application, the electrical connection between the cap 9 and the metal layer 41 or the electrically insulated mounting portion is excellent.

In the illustrated design shape, the metal layer 41 is a point where the layer 7 that is more reflective and can be properly joined has a continuous recess in the lower area of the detector element, i.e. the detector element or support. And in the adjacent enclosure of the connection contact 48. Layer 7 is, for example, a thin gold layer.

Around the detector element 2 and all around the contact surface, in the design shape shown, the metal layers 7, 41 are coated with an absorption layer 43, for example solder resist lacquer.

The absorption layer 43 is used to avoid reflection of incident light that may affect the measurement results in an undesirable way.

A through hole 44 is also possible, often referred to as a via, and provides a connection to the underside of the base plate. The through holes 44 are covered with metal plating on the inner wall surfaces until the mounting is completed, and are sealed from the lower side so that the gas does not leak as much as possible. This can be done, for example, by adhesive dripping or by solder lock 45. This lock is necessary to seal the sensor housing from external sources such as moisture as well as aggressive gas. In some applications, it is effective when locked in a predetermined gas atmosphere, such as dry nitrogen or an inert gas, to set the sensor interior to a predetermined gas to moisture ratio.

Under the base plate 1, the metal part of the contact 44 is connected to the printed solder bead 46. These solder beads can be composed of, for example, tin solder. By subsequent melting of tin and solder, the sensor can be automatically installed on a standard PCB by a so-called reflow soldering process.

FIG. 3 shows a basic structure for the design shape of the sensor on the base plate according to the present invention. The operation of the sensor will be described next with reference to this drawing and the previous drawing.

Infrared radiation 53 originating from the object whose temperature is to be measured passes through a filter provided in the cap 9 and enters the detector element 2 having an absorber system.

In the absorber system 19, the thermal radiation is substantially completely absorbed, resulting in a temperature difference between the boundary of the support 12 of the detector element 2 above the silicon carrier and the absorber region 19. Many thermo elements are located on the absorber system so that one of their connections is located in the area of the absorber system where it is exposed to infrared radiation and the other connection is fixed at the detector element boundary. Is arranged. Due to the thermoelectric effect, a potential difference occurs across all thermocouples. This potential difference is proportional to the temperature difference between the area of the absorber system that is exposed to infrared radiation and the boundary of the detector element. The thermal voltage is usually very small, a few microvolts. In order to increase the signal voltage, many thermocouples are connected in series with a so-called thermopile. These may typically be tens or hundreds or more of thermocouples.

The two ends of the thermocouple connected in the above-described manner are connected to the bond island 21. From the bond island 21, the bond wire 4 sends a signal to the connection wire or connection contact.

Preferably, the detector element 2 is arranged together with a sensing element or absorber element on the ground plate 1 which should have good thermal conductivity. The detector element 2 is of the design shape shown, in the range of 250 to 650 μm, preferably about 400 μm thick silicon support 12, the membrane above it and the thin layers 13, 14, 15, 16 and. The thermally insulating thin film layers 13 and 14 of about 0.3 to 1 μm are made of dielectric layers (preferably silicon nitride and silicon oxide or silicon oxy-nitrite).

The layers of the membrane are sandwich structures with at least two layers. Here, it is effective to manufacture the lower limit layer 14 of silicon dioxide, also referred to as the base layer 14, and to have a thickness of 50 to 30 nm. Silicon dioxide has been selected to form certain etch barrier layers because it has a very low etch rate suitable for later reactive silicon etching processes. Above the base layer is a membrane layer 13 on which thermoelectrically active layers 15 and 16 are provided. P-conducting (hole conducting) polycrystalline silicon and n-conducting (electron conducting) polycrystalline silicon are suitably used here together. Both materials have high thermoelectric coefficients with opposite signs and can be easily used in CMOS standard processes.

Each thermocouple has one rim of n-conductive polysilicon and one of p-conductive polysilicon, respectively. Both of these rims are suitably placed one on the other and each connected at their ends to the front and back thermocouples. As a result, a so-called “heat” contact 18 is located in the center of the membrane. This area is exposed to infrared radiation on the edge of the chip 2 above the silicon carrier 2 acting as a heat sink, so-called “cold” contact 17. Contact can be made in one or more contact windows made of aluminum or aluminum alloy.

The insulation between the two polysilicon rims, one on top of the other, is realized in a preferred design using a CMOS standard method, for example using a thin layer of silicon dioxide or silicon nitride.

There is an absorber structure 19 placed above the hot junction 18. This coating layer, consisting of at least one layer and optionally several layers, must have a reflective function that is as low as possible and highly absorptive for the infrared radiation to be measured (eg 3 to 15 μm). I must.

Together with the membrane layers 13, 14, 15, 16 and the reflective layer 20, they form the absorber system of the present invention.

The sensor chip according to the present invention can be manufactured in a compound on a silicon wafer, usually 100-200 mm diameter. At that time, in general, 2,000 to 20,000 chips can be arranged on one wafer. Here, the detection layer is disposed on the upper side of the wafer. For this purpose, the dielectric layer 13, preferably silicon nitride and silicon oxide or silicon oxynitride, is deposited on the silicon by a CVD process standardized in CMOS technology. This results in a sandwich structure with several layers. The thickness of the layer is selected so that mechanical stresses due to different coefficients of thermal expansion are balanced as much as possible for cooling of the chip after deposition at an elevated temperature to room temperature. Thus, for example, silicon nitride is under tensile stress after cooling while silicon oxide is under compressive stress after cooling. It is advantageous to select the layer thickness so that the stress of the entire layer is more or less removed after cooling to room temperature, or in the worst case only a small amount of tensile stress remains.

FIG. 4 shows a further view of the sensor 2 including membranes and absorbers as well as contacts that help clarify the intensity ratio.

Here, since the support body 12 made of a silicon layer is substantially formed of only four walls having a thickness D that form a substantially right angle to each other, it is clear that the support body 12 has a recess 40. I understand. The thickness D of the remaining frame of the support is preferably at most 18%, particularly preferably in the range of 8 to 12%, with respect to the total length S of the side surfaces of the chip 2. Radiation exploration of temperature sensors has increased as a result. Furthermore, the distance A1 between the boundary of the absorber structure 19 and the membrane is less than 6%, preferably in the range of 2 to 5% of the total side length of the chip. For very small detector elements, for example, with side lengths of about 1 mm or less, the values of D and A1 are the upper limit specified, but low values are effective for detector elements with side lengths exceeding 2 mm It turns out that it is.

The width or length A2 of the absorber element is referred to as the side length of the chip and is preferably at least 52%, especially with a detector size of less than about 1 mm, with a side length in particular exceeding 1.5 mm. In the case of detector size, it is preferably in the range of 65-80%.

During the test, the size ratios listed in the following table proved them.

What can be realized by configuring the chip shape according to the present invention is that the realizable signal voltage, called the detector surface, is greatly increased compared to known sensors. Therefore, the signal voltage was measured during the test, which was 1.4 to 2 times the signal voltage of a known sensor chip with the same detector surface area.

In addition, since the support boundaries are greatly reduced compared to state-of-the-art sensors, the possibility of reflections leading to undesired enlargement of the measurement points is reduced. As a result, the measurement accuracy of the infrared radiation thermometer of the present invention for measuring an object to be measured limited in space is greatly increased.

Placing the cold junction 17 on the edge of the membrane near the edge of the silicon support 12 and placing the hot junction as far as possible below the absorber 19 is effective because the entire area of the absorber surface can be utilized. I understood that. As a result, certain contacts, for example all second or third contacts, are arranged in the vicinity of the absorber boundary, the rest being provided between the absorber boundary and the middle part of the absorber 19.

5A and 5B show the structure of an absorber system according to the present invention. There, the entire sensor including the bottom of the housing is designed so that all of the elements are involved in absorption. Infrared radiation incident on the non-detecting element 2 via the infrared filter 10 first reaches the absorber coating layer 52. This covering layer can be produced by a CMOS compatible process appropriately, has a reflection coefficient as small as possible, and has a high self-absorption property, for example, in the spectral range of 3-14 μm. Since CMOS and clean room compatible layers typically only have an absorption of up to about 50-70%, some of the infrared radiation necessarily penetrates the cover layer 52, and the cover layer The light is incident not only on the passivation layer 51 formed below 52 but also on the thermoelectric layers 15 and 16 and the film layers 13 and 14 below the passivation layer 51. These layers also exhibit specific absorption in the infrared region. The overall absorption of a layer-like structure depends on both the wavelength of the infrared radiation and the thickness of the dielectric layer used. Thus, some of the incident infrared radiation can penetrate the layer structure and reach the base plate 1. However, as described above, the highly reflective layer 7 having almost no self-reflection or propagation is provided in the concave portion on the base plate 1, and the radiation component is reflected back to the film. In addition, since the film layer 14 may also reflect a part of the radiation reflected by the layer 7, multiple reflections may occur until the radiation component penetrates almost completely and returns from below to the film layer. is there. The largest of the residual radiation, ie the radiation that first penetrates the absorber layer, is absorbed in the second pass through the layer system consisting of layers 13, 14, 15, 16, 51, 52. The

Alternatively, it is also possible to introduce a reflective layer in the dielectric layer system of the absorbing layer, since multiple reflections only occur in part of the layer system. Furthermore, for certain applications, the thickness of the dielectric layer can be effectively optimized with respect to interference effects because it absorbs incident light in the absorbing layer as completely as possible. Thus, for example, a dielectric layer with a silicon oxide thickness of 0.5-1 μm can be applied via a further reflective layer, for example. When actually used in a broadband sensor, it is effective to increase the overall thickness of the dielectric layer to 1.5 to 2.5 μm.

Experience has shown that a thermoelectric layer is substantially formed over the entire film in order to absorb as much incident radiation as possible. Furthermore, the absorber layer should preferably fill the surface of the free-standing membrane, i.e. the surface of the membrane not in contact with the support, to at least 70-85%.

The layer system consists of a basic oxide layer 14 made of, for example, thermal silicon oxide or CVD oxide, and a film sandwich 13 made of, for example, silicon nitride, silicon oxide or silicon nitride oxide. For example, the n- and p- conductive polycrystalline silicon or the thermoelectric layers 15 and 16 made of silicon and germanium can also be manufactured from the CVD separation process. Above the thermoelectric layers 15 and 16 is an inactive layer of silicon oxide or silicon nitride having a thickness of about 100 to 1,500 nm.

The absorber coating layer 52 can be manufactured in a single layer or multiple layer design. Tests have shown that two variants are particularly effective.

In the first modification, a thin reflection reducing metal layer made of titanium nitride is welded onto, for example, the passivation layer 51. The welding can be performed, for example, by sputtering or vapor deposition. The use of such a reflection-reducing thin layer is a known technique in principle for known layers, but due to oxidation and aging processes, the resistance of the layer, i.e. the absorption characteristics, over time. change. Therefore, the present invention proposes that a further passivation layer made of silicon oxide or silicon nitride is provided on the reflection reducing layer and the thickness of the second layer is preferably in the range of 10-50 nm. This layer can be produced, for example, using plasma-reduced CVD welding means at temperatures of about 350-400 ° C. A very thin passivation layer reduces the reflective properties of the metal layer to a minor extent, but provides excellent stability over a long period of time for the thin reflection-reducing layer.

In the second variant, a polymer layer is used as the absorber coating layer. The thickness of the polymer layer is about 2 to 10 μm. Photoimides such as polyamides or other polymers are suitably used as the polymer layer.

In addition, the two variants described for increasing the absorption can also be combined. Therefore, the reflection reducing metal layer is deposited on the polymer layer.

In order to further limit the measuring points, the silicon support of the detector element 2 has a very small width in the present invention because the usable absorber surface is very large compared to the total surface area of the detector element. Yes. If part of the infrared radiation 26 is nevertheless incident on the edge of the detector element 2, they are shielded from further reflections by an absorber layer generated on the film simultaneously with the absorber of the edge 25. be able to. Since the absorber layer 25 can cover the end of the entire support above the silicon carrier, the surface necessary to connect the wires must be excluded. Due to the high thermal conductivity of silicon, the good thermal coupling of the absorber layer to the silicon carrier and the silicon carrier on the housing, the absorption of the radiation incident on the edge region is the cold junction 17 which is of the stated value. Does not cause an increase in temperature.

If some of the infrared radiation 24 is incident on the base plate 1 in addition to the detector element 2, these can be absorbed by a further absorber layer 43. This is done to prevent these radiation components 24 from returning to the absorber under certain circumstances due to multiple reflections at the base plate, cap wall and cap cover.

Otherwise, the lens image generation function will be degraded.

FIG. 6 shows two design shapes with improved cap shapes according to the present invention. Due to the special cap shape shown in the figure, the dimensional accuracy is increased, especially when a so-called “thermal shock action” occurs. The so-called thermal shock effect results from the fact that a temperature gradient occurs between the cap and the base plate when the ambient temperature changes rapidly. This temperature difference necessarily results in an inappropriate signal that the temperature reference on the base plate cannot correct. This error signal only disappears after the cap and base plate are again at the exact same temperature. This effect is particularly noticeable when the detector element or the absorber system of the chip 2 has a filter sticker 27 that is commonly used to secure the filter 10 on the cap 9 in the “view”. . This is due to the self-absorption and release of the filter sticker used-often very high-compared to the metal cap 9. As a result, the temperature difference between the base body and the cap 9 or between the base body and the used sticker 27 is sent to the detector element 2 via the infrared radiation emitted by the sticker 27. This causes a measurement error when the cap 9 is at a different temperature than the detector element 2.

Thus, in the case of the design shape shown in FIG. 6a, a further screen 28, for example made of metal or plastic, allows the perforated screen 28 to send radiation from the filter 10 to the absorber and to detect the radiation component arriving from the outer cap wall. It is incorporated in the cap 6 above the detector element so as to be separated from the element 2. However, it is effective if the screen 28 is manufactured so as to reflect on both sides and is applied so that at least the upper side facing the infrared filter 10 is absorbent.

In the case of the second design shape having the cap shape shown in FIG. 6 b, the filter 10 is incorporated on the upper side of the recessed cap 9. This recess is formed so that the filter sticker 27 is not located in the “view” of the detector element 2. The depth of the recess is selected to make it slightly deeper than the thickness of the filter so that the filter does not protrude from the top surface of the cap.

FIGS. 7a and 7b show a more preferred cap shape using a thermopile sensor with a further increased spatial resolution.

Therefore, a rotationally symmetric mirror 30 is installed on the cap 29 shown in FIG. 7a. The mirror can be manufactured from a reflective coated metal or plastic part.

The upper part of the mirror 30 is formed so that the light beam passing through the infrared filter 10 is focused on the absorber surface of the detector element 2. This can be achieved, for example, by forming the upper part of the mirror 30 as a parabola or as a so-called Winstone cone.

The lower end 32 of the mirror is on the other hand made such that the wall area of the cap 29 does not belong to the visible range of the sensor absorber. For example, a metallic reflective layer on the mirror inner surface 31, 33, for example consisting of a thin gold, silver or aluminum layer, with a passivating coating of silicon oxide or polymer material, is further due to heating of the mirror or cap. Eliminate measurement errors. Both lower sides 32 of the mirror are curved as shown in FIG. 7a, and the surface is substantially parallel to, for example, the floor plate.

FIG. 7b shows another design shape with an optical focus setting function. The cap 29 has an insertion lens 34 that can be made from, for example, silicon, germanium, calcium fluoride, or similar materials. In some applications, the propagation range of lens 34 can be correspondingly limited with known non-reflective filter layers on the lens surface. The rotationally symmetric caliber body or open body 36 is made of a preferred plastic and is provided on the cap to prevent reflection on the cap wall. Therefore, the inner surface 35 of the opening body 36 is made absorbent. The lower side of the caliber body 36 is not only parallel to the base plate 1, but can be bent in any way, and can be reflective as required.

It can be seen that a plurality of detector elements 2, for example a row or array of sensor elements each having a single absorber system, as in the present invention, can be integrated on the detector element 2. The signal preprocessing of the individual signals can be performed consistently on both the detector element 2 as well as the application specific silicon circuit 11 next to the detector element 2 on the floor plate 1.

FIG. 7c shows another design shape for an absorber system such as the present invention. In principle, the chip shape and the layer sequence of this design shape correspond to the design shape described in relation to FIGS. Even in the multi-element arrangement, there is a highly reflective layer 7 arranged in the region below the film 7. The absorber structure 19 is placed below the membrane layers 13, 14 where it is likewise tuned to the surface of most elements between the remaining walls 54 of the silicon carrier 12. In contrast to the single element scheme, the lens 34 must be inserted. Further, the aperture opening of the aperture body 30 must match the size of the sensor element existing outside.

It can be seen that not only the mirror 30 but also the aperture body 36 can be manufactured as part of the cap 29. 8A and 8B show the corresponding design shapes.

For example, the cap 29, which can be made from deep drawn metal or injection molded plastic, has a recess 37 in the upper end surface for positioning the filter 10. In the depression, the mirror surface 30 is directly adjacent to the reflective coating 31. The mirror surface 31 and the cap 29 are thus formed from a single piece so that a particularly favorable thermal contact of the mirror, cap and filter or lens to the base plate can be achieved. Furthermore, this design shape reduces assembly costs. This is because it is not necessary to separately install a mirror and a corresponding arrangement is not necessary. In the design shape shown, the internal part of the mirror 30 with its reflective coating 31 is shaped to exhibit the focus setting action of radiation incident through the infrared filter 10. As a result, the radiation is mapped on the absorber surface of the detector element 2. For this purpose, the mirror is in the form of a parabola or a so-called Winstone-cone.

The reproducible optical image characteristics can be realized by the design shape shown in FIG. This is because the distance between the mirror and the detector element 2 is appropriately determined by setting the shape of the cap 29 as the deep drawing tool 20 or the injection molding tool. In a particularly preferred design shape, at least the entire inner surface of the cap is coated with a reflective coating.

Moreover, it is even more effective when the outer surface of the cap is coated with a reflective coating to avoid undesired heating of the cap 29 compared to the ground plate 1.

The design shape shown in FIG. 8b shows a lens 34, for example made of silicon, germanium, calcium fluoride or similar material, inserted into the cap 29. FIG. Here, the cap 29 is a metal deep-drawn part or a plastic injection-molded part, and has a recess 37 on the upper end of which the lens 34 is placed. Further, the depression 37 has a groove 38 that runs around the depression 37. The peripheral groove 38 can also be used with the design shape shown in FIG. 8a, but prevents the sticker that attaches the filter 10 or lens 34 from being pushed to the filter surface, mirror surface or lens surface visible from the sensor. Even in this design shape, the aperture surface 30 is directly adjacent to the absorbent coating 35 in the recess.

The further screen 28 can be suitably manufactured as a deep-drawn metal part, or the reflective coating can be plasticized, but the screen 28 allows radiation to pass from the filter to the absorber and for radiation coming from the outer cap wall. It is arranged above the chip 2 so as to keep the components away from the detector element. If the cap 29 is made of plastic, the perforated screen 28 is preferably made of metal and has a lower end 39 extending to and connected to the base plate 1 for good thermal contact. The perforated screen 28 functions to improve optical image creation conditions and reduce so-called thermal shock effects. Here, the entire inner and outer surfaces of the cap 29 are also appropriately reflective coated.

  It can also be used for radiation sensors other than radiation sensors for non-contact temperature measurement or infrared gas spectroscopy.

1A and 1B are two schematic diagrams depicting the structure of an infrared sensor. 2A and 2B are cross-sectional views of a thermopile sensor on a non-metallic carrier. FIG. 3 shows a schematic structure of the sensor of the present invention. FIG. 4 is a schematic diagram depicting the contacts on the sensor. 5A and 5B show two different design shapes with an absorber system according to the present invention. 6A and 6B show two different design shapes for the sensor housing. Figures 7A, 7B and 7C show three different design shapes for the sensor cap with image lens. 8A and 8B show two or more design shapes for a sensor cap with an integrated image lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base plate 2 Detector element 3 Temperature reference element 4 Connecting wire 5 Connecting pin 6 Contact surface 7 Reflective layer 8 Absorbing layer 9 Cap 10 Filter 11 Signal processing circuit 12 Support body 13 Film layer 14 Base layer / underlayer 15 16 Thermoelectric layer 17 Cold junction 18 Hot junction 19 Absorber structure 20 Reflective layer 21 Bonded island 24 Part of infrared radiation 25 Absorber layer boundary area 26 Part of infrared radiation 27 Filter sticker 28 Screen 29 Cap 30 Mirror 31 Mirror layer 32 Mirror lower side 33 Reflective layer 34 Lens 35 Surface 36 Diameter body 37 Dimple 38 Groove 39 Bottom of screen 49 Recess 41 Metal layer 42 Island 43 Absorbing layer 44 Passage 45 Solder lock 46 Solder bead 48 Contact 51 Not Activation layer 52 Absorber coating layer 53 Infrared radiation 54 Silicon Side length of thickness S detector elements of length D support frame distance A2 absorber elements between the wall A1 absorber boundaries and film lifting member

Claims (32)

Comprising a detector element, for example a radiation sensor for non-contact temperature measurement or infrared spectroscopy, wherein the detector element absorbs radiation and is consequently heated (13, 14, 15, 16, 51, 52) and a support (2) with a support surface for positioning the absorber elements (13, 14, 15, 16, 51, 52), There is a recess and the absorber element (13, 14, 15, 16, 51, 52) is such that at least part of the absorber element (13, 14, 15, 16, 51, 52) does not touch the support (2) The radiation sensor as described above, wherein the radiation sensor is disposed on the support surface above the recess, and the recess has an extension corresponding to at least 45% of the support surface. In the absorber element (13, 14, 15, 16, 51, 52), the recess takes the range of 45-75%, preferably in the range of 50-70%, particularly preferably about 65% of the surface of the support. Sensor according to claim 1, characterized in that it has a cross section on at least its side faces. The recess has a side wall (2) containing an angle in the range of 80 to 100 degrees, preferably in the range of 85 to 95 degrees, particularly preferably about 90 degrees, with respect to the upper surface of the support. The sensor according to claim 1 or 2. Sensor according to any one of claims 1 to 3, characterized in that the recess runs perpendicularly to the stationary surface via the entire support (2). Sensor according to any one of the preceding claims, characterized in that the support (2) is manufactured using silicon technology. Sensor according to any one of the preceding claims, characterized in that the base plate (1) is provided where the support is fixed. Sensor according to any one of the preceding claims, characterized in that the absorber element (13, 14, 15, 16, 51, 52) has at least one CMOS compatible covering layer (52). . The absorber element (13, 14, 15, 16, 51, 52) is multi-layered, and the CMOS compatible covering layer (52) is at least one radiation-sensitive or temperature-sensitive functional layer (13, 14, 15, 16) Sensor according to claim 7, characterized in that it is applied on top. 9. The coating according to claim 7 or 8, characterized in that the covering layer (52) has a surface area in the range of at least 30%, preferably in the range 35-70%, particularly preferably in the range 40-60% of the surface of the support. The sensor described. At least the bottom surface or ground of the recess is made of an infrared radiation reflecting material, preferably a metal layer (7), particularly preferably a gold layer, the layer (7) preferably having a thickness of less than 1 μm. 10. The sensor according to any one of claims 1 to 9. The base plate (1) is made of a material that does not reflect infrared radiation or a material that does not reflect infrared radiation, preferably a lacquer or photoresist, on the area (43) surrounding the support (2) The sensor according to claim 6, wherein at least the sensor is applied to the sensor. A membrane (13) for supporting an absorber element (13, 14, 15, 16, 51, 52) is provided, said membrane (13) comprising at least two layers. 11. The sensor according to any one of 11 above. Sensor according to claim 12, characterized in that the layer of membrane (13) is made of silicon dioxide, silicon nitride or silicon carbide. 14. A sensor according to any one of the preceding claims, characterized in that the absorber element (13, 14, 15, 16, 51, 52) has a multilayer structure. 15. Absorber element (13, 14, 15, 16, 51, 52), preferably configured as a CMOS-compatible metal absorber layer and having a covering layer (19, 52). Sensor. Sensor according to claim 15, characterized in that the covering layer (19, 52) is less than 50 nm thick. Sensor according to claim 15 or 16, characterized in that the covering layer (19, 52) consists of titanium nitride. 18. A sensor according to any one of claims 15 to 17, characterized in that the covering layer (19, 52) has a layer resistance in the range of approximately 180 to 400Ω. 19. The deactivation layer according to any one of claims 15 to 18, characterized in that a deactivation layer is placed on the covering layer (19, 52) and the deactivation layer is preferably made of silicon oxide or silicon nitride. Sensor described in. 17. A sensor according to claim 15 or 16, characterized in that the covering layer (19, 52) is preferably formed by a polymer layer having a thickness in the range of 2 to 10 [mu] m. The coating layer (19) is preferably a polymer layer having a thickness of 2 to 10 μm, a metal absorption layer having a thickness of preferably less than 50 nm disposed above the polymer layer, and a metal absorption layer having a thickness of preferably 10 to 50 nm 17. A sensor according to claim 15 or 16, characterized in that it comprises a passivating layer disposed above. 22. The at least one layer forming the covering layer (19, 52) extends at least partially to the upper end surface of the support (2) surrounding the recess. The sensor according to claim 1. 23. A sensor according to any one of the preceding claims, characterized in that a device for measuring the temperature of the absorber element is provided. 24. Sensor according to claim 23, characterized in that the temperature measuring device has at least one thermo element, preferably a thermopile. At least one thermo element or thermopile is formed from two layers of polycrystalline silicon, one layer is n-conducting and the other is p-conducting, both layers of silicon oxide or silicon nitride 25. Sensor according to claim 24, characterized in that they are separated from one another by insulating layers suitably formed by layers. 26. A sensor according to any one of the preceding claims, characterized in that the absorber element (13, 14, 15, 16, 51, 52) has a reflective layer for reflecting radiation. 27. Sensor according to claim 26, characterized in that a dielectric layer is provided on the reflective layer, preferably with a thickness in the range of 0.5 to 2.5 [mu] m. 28. Sensor according to claim 27, characterized in that the dielectric layer consists of polysilicon and silicon dioxide or silicon nitride, preferably silicon dioxide. 29. Any one of claims 23 to 28, characterized in that several thermopile elements are arranged in a column or matrix format and all thermopile elements are appropriately assigned to separate absorber elements. Sensor described in. 30. Sensor according to claim 29, characterized in that the support element has a number of recesses and a number of absorber elements, each absorber element being arranged above the recess. Each connection of one of the thermopile thermo-elements, so-called thermal contacts are arranged below the absorber element, advantageously all the second or third thermo-element thermal contacts extend to the middle region of the absorber element 31. A sensor according to any one of claims 24 to 30, characterized in that it extends and only the thermal contact of the other thermo-element extends to the edge region of the absorber element. Each connection of one of the thermopile thermo-elements has a so-called cold junction connected to the edge of the support surrounding the recess, and the point of connection of the cold junction to the support is on the inner edge of the frame of the support surrounding the recess. 32. A sensor according to any one of claims 24 to 31, characterized in that it is suitably in the area.

Images