Sensor system and manufacturing process as well as self-testing process

• US 6,294,787 B1
• Filed: 08/13/1998
• Issued: 09/25/2001
• Est. Priority Date: 08/14/1997
• Status: Expired due to Term

• Current Assignee: Excelitas Technologies Singapore Pte., Ltd., Robert Bosch GmbH
• Original Assignee: Heimannn Optoelectronics GmbH, Robert Bosch GmbH
• Inventors: Jähne, Rolf, Simon, Marion, Storck, Karlheinz, Zabler, Erich, Schieferdecker, Jörg, Rothley, Manfred
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): GAGLIARDI, ALBERT J
• Application Number:
  US09/133,802
• Time in Patent Office: 1,139 Days
• Field of Search: 250/349, 250/338.1, 250/338.3, 250/338.4, 250/339.02, 250/339.03, 250/339.04, 250/339.09, 250/339.14, 250/341.5, 250/341.6, 250/252, 250/252.1
• US Class Current: 250/349
• CPC Class Codes: B81C 99/0045 End test of the packaged device
• CPC Class Codes: G01J 5/02 Constructional details
• CPC Class Codes: G01J 5/026 Control of working procedures of a pyrometer, other than calibration; Bandwidth calculation; Gain control
• CPC Class Codes: G01J 5/061 by controlling the temperature of the apparatus or parts thereof, e.g. using cooling means or thermostats
• CPC Class Codes: G01J 5/064 Ambient temperature sensor; Housing temperature sensor; Constructional details thereof
• CPC Class Codes: G01J 5/10 using electric radiation detectors
• CPC Class Codes: G01J 5/12 using thermoelectric elements, e.g. thermocouples
• CPC Class Codes: G01J 5/22 Electrical features thereof

Abstract

Presented is a sensor system for the detection of thermal radiation, with a substrate (15) and several sensor elements (10) on the substrate (15), in which case at least one self-test device (53) is provided in order to generate heat which can be used for the heating of one or more sensor elements (10). The sensor elements (10) can be heated according to a typical time pattern during the self-testing process. Also presented is an advantageous process for the manufacture of the sensor system as well as an advantageous configuration of the total system, including signal processing.

Claims

1. A sensor system for detecting thermal radiation comprising:

a substrate,

several sensor elements which deliver an electrical signal representative of the thermal radiation striking each, the several sensor elements attached to a substrate, and

at least one self-test device for the generation of heat, whereby one or more sensor elements can be heated.

2. Sensor system according to claim 1, wherein several self-test devices are provided for the generation of heat, each assigned to a respective sensor element.

3. A sensor system according to claim 2, further comprising:

a depression in the material of the substrate, beneath at least one sensor element, wherein

the material depression is selected from one of a hole passing through the substrate and a recess set back from the front side of the substrate;

an insulating layer on the surface of the substrate, to which sensor elements are attached;

wherein the insulating layer spans the material depressions and the sensor elements are attached to the insulating layer in such a way that they lie entirely over, or in part over, the depressions in the material;

an insulating device provided between sensor elements, said insulating device formed from a thermally conductive material upon the insulating layer with part of its area over the depression in the material and a slot in the insulating layer, in the vicinity of the depression in the material;

wherein the self-test device is a device which generates a flow of heat, the self-test device has an elongated shape and is mounted in the vicinity of one edge of a sensor element.

4. The sensor system of claim 3 wherein the self-test device is mounted parallel to one edge of a sensor element.

5. Sensor system according to claim 1 wherein a depression in the material of the substrate is provided beneath at least one sensor element.

6. Sensor system according to claim 5, wherein the material depression is a hole passing through the substrate.

7. A sensor system according to claim 6 wherein the material depressions are the result of one of surface micromechanics process in porous silicon and reactive ion etching process.

8. Sensor system according to claim 5, wherein the material depression is a recess set back from the sensor side of the substrate.

9. Sensor system according to claim 5 including an insulating layer of the surface of the substrate, to which sensor elements aye attached.

10. Sensor system according to claim 9 wherein the insulating layer spans the material depressions and the sensor elements are attached to the insulating layer in such a way that they lie entirely over, or in part over, the depressions in the material.

11. Sensor system according to claim 9 further comprising an insulating device provided between sensor elements.

12. Sensor system according to claim 11 wherein the insulating device is formed from a thermally conductive material and attached upon the insulating layer with part of its area over the depression in the material.

13. Sensor system according to claim 11 wherein the insulating device is a slot in the insulating layer, in the vicinity of the depression in the material.

14. Sensor system according to claim 13, wherein a self-test device is provided between the slot provided as an insulating device and the sensor element.

15. Sensor system according to claim 1 wherein the self-test device is a device which generates a flow of heat, the self-test device has an elongated shape and is mounted in the vicinity of one edge of the sensor element.

16. The sensor system of claim 15 wherein the self-test device is mounted parallel to one edge of a sensor element.

17. A sensor system for the detection of thermal radiation, comprising:

a substrate,

several sensor elements in an array, each attached to the substrate and each of which generates an electrical signal representative of the thermal radiation striking it,

several self-test devices, said self-test devices formed differently from one another in such a way that they respectively heat several sensor elements to respectively different levels, and a signal-processing device which converts at least the simultaneous electrical output signals of a set of sensor elements into a serial signal and delivers this as an output.

18. A process of self-testing a device in a sensor system for detecting thermal radiation wherein at least one self-test device is heated and an output system of at least one sensor element is monitored.

19. Process according to claim 18, wherein a self-test device is driven with a characteristic electric signal.

20. Process according to claim 19, wherein the electrical signal exhibits two or more pulses and/or a signal which changes over time.

21. Process according to claim 19 further comprising:

monitoring the sensor system during the self-testing process,

extracting an anticipated characteristic signal from the output signal of the sensor system, said anticipated characteristic signal being the response of the self-test device to said characteristic electrical signal, and

monitoring the remaining output signals.

22. A sensor system for the detection of thermal radiation, with a substrate, several sensor elements, each attached to the substrate and each of which generates an electrical signal representative of the thermal radiation striking it, characterized by a signal-processing device which converts at least the electrical output signals of sensor elements lying parallel to one another into a serial signal and delivers this to an output;

a calibrating device for permanently setting the characteristic curve of at least one sensor element; and

several self-test devices which are formed differently from one another in such a way that they heat several sensor elements to different levels wherein;

the signal-processing device is formed either on the substrate or on its own substrate, in the immediate vicinity of the substrates of the sensor elements and is electrically connected to the said sensor elements;

the sensor system comprises a device for the measurement of temperature, which delivers a signal representative of the absolute temperature.

23. A method of operating a sensor system utilizing at least one sensor element for the detection of thermal radiation comprising;

providing at least one self-test device between a slot provided as an insulating device and the sensor element;

heating that at least one self-test device;

monitoring the electrical signal from at least one sensor element;

driving a self-test device with a characteristic electric signal that exhibits two or more pulses and/or a signal which changes over time; and

continuing monitoring the sensor system during the self-testing process, removing an anticipated characteristic signal determined on the basis of the operation of the self-test device, in order to serve as a signal for monitoring.

24. Process for the production of a sensor system for detecting thermal radiation using sensor elements which deliver an electrical signal representative of the thermal radiation striking each and several self-test devices provided for the generation of heat, each assigned to a respective sensor element on a substrate comprising:

producing porous silicon using an electrochemical process on a front side of said substrate;

forming depressions in the porous silicon using surface-micromechanics; and

applying several sensor elements to the substrate disposed over said depressions.

25. Process for the production of a sensor system for detecting thermal radiation using sensor elements which deliver an electrical signal representative of the thermal radiation striking each sensor and several self-test devices provided for the generation of heat, each assigned to a respective sensor element on a substrate comprising:

forming depressions in the substrate using plasma-etching process during reactive ion etching on the back side of said substrate wherein a hole is formed with a depth of up to between 90 and 99% of the total depth by reactive ion etching and is generated to the final depth by isotropic or anisotropic etching; and

applying several sensor elements to the substrate disposed over said depressions.