DE102008001885A1 - Sensor arrangement and method for operating a sensor arrangement - Google Patents

Abstract

A sensor arrangement with a substrate, a cavern arranged in the substrate, a membrane overlapping the cavern perpendicular to a main extension plane of the substrate and a plurality of sensor elements are proposed, the plurality of sensor elements being arranged in series on one membrane.

Description

State of the art

The The invention is based on a sensor arrangement according to the preamble of claim 1.

Such sensor arrangements are well known. For example, from the document DE 10 2006 028 435 A1 a sensor for spatially resolved detection, wherein the sensor comprises a substrate, a microstructured sensor element with a value dependent temperature-changing electrical property, in particular a diode, and above a cavern disposed in the substrate membrane and wherein the sensor element is disposed on a lower side of the membrane ,

Disclosure of the invention

The Sensor arrangement according to the invention and the inventive Method for operating a sensor arrangement according to the have sibling claims against the State of the art has the advantage that the signal-to-noise ratio when reading a sensor pixel significantly improved is, wherein a sensor pixel according to the present invention a membrane and arranged on this membrane sensor elements comprises. the improvement of the signal-to-noise ratio is achieved according to the invention achieves that on a sensor pixel a plurality of sensor elements is arranged, wherein the plurality of sensor elements with each other are connected in a series circuit, so that when reading of the sensor pixel, the plurality of sensor elements, in particular simultaneously be read out and the signal level per sensor pixel thus multiplied. The noise of a sensor pixel is essentially determined by the noise of an evaluation circuit reading out the sensor pixel, so that the noise of a sensor pixel increases the number of sensor elements connected in series per sensor pixel is essentially constant. The increase of the signal height a sensor pixel thus causes a significant improvement of Signal-to-noise ratio, so that in particular the Characteristics such as detectivity, sensitivity and measurement accuracy the sensor pixel or the sensor arrangement in comparison to the state the technology can be significantly improved.

advantageous Refinements and developments of the invention are the subclaims, and the description with reference to the drawings.

According to one preferred development is provided that the majority of Sensor elements at least partially electrically isolated from each other are. An electrical short circuit is thus particularly advantageous between the sensor elements, in particular by an electrical Current through the membrane, suppressed and a series connection of Sensor elements allows.

According to one Another preferred embodiment provides that the membrane at least one doping trough, wherein a sensor element in the doping trough is arranged. Is particularly advantageous the formation of doping wells in the membrane a realization from electrically separated areas on the membrane in a particularly simple Way with comparatively well controlled standard method allows. Particularly preferred is at least one sensor element or the entire Plurality of the sensor elements arranged in each case a doping trough, so that in each case one arranged in a doping sensor element is electrically isolated from adjacent sensor elements.

According to one Another preferred embodiment provides that the membrane has at least one trench, wherein at least two sensor elements are electrically isolated from each other by the trench. Especially advantageous is thus an electrical insulation of two adjacent Sensor elements realized in a comparatively simple manner.

According to one Another preferred embodiment provides that the trenches provided by etching, so that the electrical insulation of adjacent sensor elements by means of comparatively easy to control standard procedures particularly cost-effective to implement.

According to one Another preferred embodiment provides that the sensor elements Diodes comprise and / or that the membrane opposite to the Substrate is provided thermally decoupled. Especially advantageous the use of diodes as sensor elements a spatially resolved temperature sensing enabled by the sensor arrangement. By a thermal Decoupling of the sensor assembly from the substrate also becomes the sensitivity the sensor elements increases and the interference the temperature of the substrate on the sensing of the sensor elements and thus reduces the noise of the sensor elements.

According to one Another preferred embodiment provides that the membrane is provided fixed by means of spring elements to the substrate. Thus, a particularly simple manner becomes particularly advantageous elastic recording, as well as attachment of the membrane to the substrate and at the same time a comparatively good thermal decoupling allows the membrane from the substrate.

According to one Another preferred embodiment provides that the majority electrically contacted by sensor elements by means of conductor tracks are, wherein preferably the conductor tracks at least partially The spring elements are arranged so that in an advantageous manner an electrical contact of the sensor element can be realized and the corresponding contacts in a simple manner from the membrane can be transferred to the substrate. Preferably is provided that the evaluation circuit for reading the plurality of sensor elements of a sensor pixel, in particular as a semiconductor structure, is realized on the substrate or another substrate and electrically conductively connected by means of the conductor tracks with the sensor elements is.

According to one Another preferred development is provided on the Membrane four sensor elements, in particular in two lines and in two Columns are arranged so that in a particularly advantageous manner a sensor pixel is feasible, which due to its essentially square shape is particularly compact and also comparatively is easy to arrange in sensor pixel arrays. It is preferably provided on a membrane any plurality of sensor elements in a row-column structure to be arranged such that the number the rows are identical to the number of columns.

According to one Another preferred development is provided that the sensor arrangement a Sensor for spatially resolved detection, in particular of temperature, Radiation and / or a fingerprint, and / or a sensor for detecting a gas concentration.

One Another object of the present invention is a method for operating a sensor arrangement, wherein the signals of the plurality of series-connected sensor elements by means of an evaluation circuit be read out at the same time. In contrast to the prior art When reading a sensor pixel according to the inventive method for operating a Sensor arrangement by means of the evaluation circuit, the plurality of sensor elements read out at the same time. Through the interconnection of the plurality of Sensor elements in a series circuit thus becomes the signal level of the sensor pixel increases while the noise contribution the evaluation circuit remains essentially constant, so that in Sum the signal-to-noise ratio of a single sensor pixel or the sensor arrangement is improved considerably.

embodiments The invention are illustrated in the drawing and in the following description explained in more detail.

Brief description of the drawings

It demonstrate

1 a schematic side view of a sensor arrangement according to an exemplary embodiment of the present invention and

2 a schematic plan view of a sensor arrangement according to the exemplary embodiment of the present invention.

Embodiment of the invention

In 1 is a schematic side view and in 2 a schematic plan view of a sensor arrangement 1 according to an exemplary embodiment of the present invention, wherein the sensor assembly 1 a substrate 2 one in the substrate 2 arranged cavern 3 and one the cavern 3 perpendicular to a main extension plane 100 of the substrate 2 overlapping membrane 4 having. Furthermore, the sensor arrangement 1 a plurality of sensor elements 5 . 5 ' . 5 '' . 5 ''' on, which are connected in series on the one membrane 4 are arranged and which are electrically isolated from each other. The sensor elements 5 . 5 ' . 5 '' . 5 ''' comprise diodes each with a pn junction, in particular for spatially resolved temperature sensing. The membrane 4 is by means of spring elements 6 on the substrate 2 elastically fastened and over the spring elements 6 opposite the substrate 2 thermally decoupled. The plurality of sensor elements 5 . 5 ' . 5 '' . 5 ''' on the membrane 4 together form a sensor pixel, wherein the plurality of sensor elements 5 . 5 . 5 '' . 5 ''' in particular four sensor elements 5 . 5 ' . 5 '' . 5 ''' comprising, in a substantially square row-column structure on the membrane 4 of two sensor elements each 5 . 5 ''; 5 ' . 5 ''' per column and two sensor elements 5 . 5 '; 5 '' . 5 ''' are arranged per line. On the membrane 4 are a variety of tracks 7 for electrical contacting of the sensor elements 5 . 5 ' . 5 '' . 5 ''' arranged, further comprising further conductor tracks 7 ' for forming an electrically conductive connection between an evaluation unit, not shown, on the substrate 2 or on another substrate and the plurality of sensor elements 5 . 5 ' . 5 '' . 5 ''' on the spring elements 6 are arranged. The tracks 7 on the membrane 4 are formed such that the sensor elements 5 . 5 ' . 5 '' . 5 ''' are interconnected in a series circuit. That is, each sensor element 5 . 5 ' . 5 '' . 5 ''' has a first and a second contact 8th . 8th' on, with the second contact 81 a first sensor element 5 with the first contact 82 a second sensor element 5 '' is connected, wherein the second contact 83 of the second sensor element 5 '' with the first contact 84 a third sensor element 5 ' is connected, wherein the second contact 85 of the third sensor element 5 ' with the first contact 85 a fourth sensor element 5 ''' and further wherein the first contact 80 of the first sensor element 5 with a first further conductor track 90 and the second contact 86 of the fourth sensor element 5 ''' with a second further track 91 connected is.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 102006028435 A1 [0002]

Claims (11)

Sensor arrangement ( 1 ) with a substrate ( 2 ), one in the substrate ( 2 ) cavern ( 3 ), one the cavern ( 3 ) perpendicular to a main plane of extension ( 100 ) of the substrate ( 2 ) overlapping membrane ( 4 ) and a plurality of sensor elements ( 5 . 5 ' . 5 '' . 5 ''' ), characterized in that the plurality of sensor elements ( 5 . 5 ' . 5 '' . 5 ''' ) connected in series on the one membrane ( 4 ) are arranged Sensor arrangement according to claim 1, characterized in that the plurality of sensor elements ( 5 . 5 ' . 5 '' . 5 ''' ) are at least partially electrically separated from each other. Sensor arrangement according to one of the preceding claims, characterized in that the membrane ( 4 ) has at least one doping trough, wherein a sensor element ( 5 . 5 ' . 5 '' . 5 ''' ) is arranged in the doping trough. Sensor arrangement according to one of the preceding claims, characterized in that the membrane has at least one trench, wherein at least two sensor elements ( 5 . 5 ' . 5 '' . 5 ''' ) are electrically isolated from each other by the trench. Sensor arrangement ( 1 ) according to one of the preceding claims, characterized in that the trenches are provided by etching produced. Sensor arrangement according to one of the preceding claims, characterized in that the sensor elements ( 5 . 5 ' . 5 '' . 5 ''' ) Comprise diodes and / or that the membrane ( 4 ) relative to the substrate ( 2 ) is provided thermally decoupled. Sensor arrangement ( 1 ) according to one of the preceding claims, characterized in that the membrane ( 4 ) by means of spring elements ( 6 ) on the substrate ( 2 ) are provided fixed. Sensor arrangement ( 1 ) according to one of the preceding claims, characterized in that the plurality of sensor elements ( 5 . 5 ' . 5 '' . 5 ''' ) by means of conductor tracks ( 7 ) are electrically contacted, wherein preferably the conductor tracks ( 7 ) at least partially on the spring elements ( 6 ) are arranged. Sensor arrangement ( 1 ) according to one of the preceding claims, characterized in that on the membrane ( 4 ) four sensor elements ( 5 . 5 ' . 5 '' . 5 ''' ), in particular in two rows and in two columns. Sensor arrangement ( 1 ) according to one of the preceding claims, characterized in that the sensor arrangement ( 1 ) comprises a sensor for spatially resolved detection, in particular of temperature, radiation and / or a fingerprint, and / or a sensor for detecting a gas concentration. Method for operating a sensor arrangement according to one of claims 1 to 10, characterized in that the signals of the plurality of serially connected sensor elements be read out simultaneously by an evaluation circuit.