Sensitive material for bolometric detection

Patent metadata

Field	Value
Publication number	US-9377364-B2
Application number	US-201514592659-A
Country	US
Kind code	B2
Filing date	Jan 8, 2015
Priority date	Jan 8, 2014
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

The present invention relates to the use, as a thin sensitive-material film for bolometric detection, of at least one material based on an alloy comprising at least one chalcogenide, said chalcogen element being chosen from sulfur, selenium, telluride and their mixtures, characterized in that said material furthermore contains a sufficient amount of carbon and/or boron to confer upon the material a temperature coefficient of resistivity value at 300° C. at least equal to 40% of the native value of the temperature coefficient of resistivity of said material at room temperature. The invention also relates to a bolometric device and its production process.

First claim

The invention claimed is:

1. A method of bolometric detection of infrared radiation comprising:
obtaining a thin sensitive-material film comprising an alloy comprising at least one chalcogenide, said chalcogen element being chosen from sulfur, selenium, and/or telluride and a sufficient amount of carbon and/or boron to confer upon the material a temperature coefficient of resistivity value at 300° C. at least equal to 40% of the native value of the temperature coefficient of resistivity of said material at room temperature; and
using the thin sensitive-material film for bolometric detection of infrared radiation.

2. The method according to claim 1 , wherein the value of the temperature coefficient of resistivity at 300° C. is at least equal to 60% of the native value of the temperature coefficient of resistivity of said material at room temperature.

3. The method according to claim 1 , wherein the alloy comprises at least telluride.

4. The method according to claim 1 , wherein said material contains at least a sufficient amount of carbon to confer upon the material a temperature coefficient of resistivity value at 300° C. at least equal to 40% of the native value of the temperature coefficient of resistivity of said material at room temperature.

5. The method according to claim 1 , wherein said material contains between 5 atomic % and 60 atomic % carbon relative to the atomic composition of said material.

6. The method according to claim 1 , wherein the alloy further comprises at least one element chosen from antimony, germanium, tin, and/or bismuth.

7. The method according to claim 1 , wherein the alloy further comprises at least germanium.

8. The method according to claim 1 , wherein the alloy comprises from 40 atomic % to 70 atomic % telluride, from 5 atomic % to 60 atomic % germanium, from 0 atomic % to 50 atomic % of an element X chosen from antimony, tin or bismuth and from 0% to 50% of an element Y, different from the element X, chosen from antimony, tin or bismuth.

9. The method according to claim 1 , wherein the alloy comprises from 40 atomic % to 60 atomic % telluride and 40 atomic % to 60 atomic % germanium.

10. The method according to claim 1 , wherein the alloy comprises from 48 atomic % to 64 atomic % telluride, from 18 atomic % to 26 atomic % germanium and from 18 atomic % to 26 atomic % antimony.

11. A bolometric device for detecting infrared radiation or for infrared imaging, comprising at least one sensor equipped with a sensitive element based on a thin sensitive-material film comprising an alloy comprising at least one chalcogenide, said chalcogen element being chosen from sulfur, selenium, and/or telluride and a sufficient amount of carbon and/or boron to confer upon the material a temperature coefficient of resistivity value at 300° C. at least equal to 40% of the native value of the temperature coefficient of resistivity of said material at room temperature.

12. The bolometric device according to claim 11 , wherein the sensitive element is implemented in the form of a thin film.

13. The bolometric device according to claim 12 , wherein the thin film has a thickness ranging from 10 nm to 500 nm.

14. The bolometric device according to claim 11 , wherein the sensor is inserted into a package containing an entrance window that is transparent in the infrared, and further comprises a membrane capable of absorbing infrared radiation and converting it into heat, said membrane being placed so as to be able to be exposed to incident infrared radiation having passed through the entrance window, and to transmit some of the heat thus produced to said sensitive element.

15. The bolometric device according to claim 11 , comprising a plurality of said sensors in the form of a matrix array of pixels.

16. The bolometric device according to claim 15 , wherein said array is connected to a CCD or CMOS read circuit.

17. A process for fabricating a bolometric device comprising at least the following steps:
i) providing a sensor equipped with a membrane capable of absorbing infrared radiation, said membrane being deposited on a carrier consisting of a sacrificial layer; and
ii) forming in contact with said membrane a thin film of a sensitive element from a thin sensitive-material film comprising an alloy comprising at least one chalcogenide, said chalcogen element being chosen from sulfur, selenium, and/or telluride and a sufficient amount of carbon and/or boron to confer upon the material a temperature coefficient of resistivity value at 300° C. at least equal to 40% of the native value of the temperature coefficient of resistivity of said material at room temperature.

18. The process according to claim 17 , wherein the said membrane consists of one or more dielectric films.

19. The process according to claim 18 , wherein the one or more dielectric films comprises SiO and/or SiN.

20. The process according to claim 17 , wherein step ii) is followed by a step iii) in which said thin film is encapsulated by what is called an encapsulation film.

21. The process according to claim 20 , wherein the step iii) is followed by a step iv) in which the sacrificial film is calcinated under oxidizing conditions.

22. The process according to claim 21 , wherein the oxidizing conditions is ozone plasma.

23. The process according to claim 20 , wherein the encapsulation film comprises SiN.

24. The process according to claim 17 , wherein the bolometric device is subjected, after step iv), to at least one annealing step at a temperature comprised between 300° C. and 400° C.

25. The process according to claim 24 , wherein the temperature of the annealing step is reached in stages.

26. The process according to claim 24 , wherein the annealing step comprises an isothermal anneal.

27. The process according to claim 24 , wherein the annealing step is carried out under vacuum or under an inert atmosphere.

Assignees

• Commissariat Energie Atomique

Inventors

• Pelenc Denis
• Armand Marie-Francoise
• Hyot Berangere
• Imperinetti Pierre
• Vialle Claire

Classifications

• G01J5/20 Primary

  using resistors, thermistors or semiconductors sensitive to radiation, e.g. photoconductive devices · CPC title

• G01J5/22

  Electrical features thereof · CPC title

• G01J5/046

  Materials; Selection of thermal materials · CPC title

• G01J5/24

  Use of specially adapted circuits, e.g. bridge circuits · CPC title

• G01J5/02

  Constructional details · CPC title