Process for manufacturing a microbolometer containing vanadium oxide-based sensitive material

Patent metadata

Field	Value
Publication number	US-11193833-B2
Application number	US-201916969302-A
Country	US
Kind code	B2
Filing date	Feb 14, 2019
Priority date	Feb 15, 2018
Publication date	Dec 7, 2021
Grant date	Dec 7, 2021

Abstract

The invention relates to a process for manufacturing a microbolometer (10) comprising a sensitive material (15) based on vanadium oxide (VOx) comprising an additional chemical element chosen from among boron (B), carbon (C), with the exception of nitrogen (N), comprising the following steps:i. determining a non-zero effective amount of the additional chemical element (B, C) starting from which the sensitive material (15), having undergone exposure to a temperature Tr for a duration Δtr, has an electrical resistivity ρa|r at ambient temperature greater than or equal to 50% of the native value ρa of said sensitive material (15);ii. producing the sensitive material (15) in a thin layer having an amount of the additional chemical element (B, C) greater than or equal to the effective amount determined beforehand, the sensitive material being amorphous and having an electrical resistivity of between 1 and 30 Ω·cm;iii. exposing the sensitive material (15) to a temperature less than or equal to Tr for a duration less than or equal to Δtr.

First claim

The invention claimed is:

1. A process for manufacturing at least one microbolometer comprising a sensitive material suitable for at least limiting noise degradation of the sensitive material, the process comprising:
producing the sensitive material, comprising a first compound comprising vanadium oxide and boron and/or carbon as an additional element, but no nitrogen, in a thin layer;
exposing the sensitive material to a temperature T r greater than the ambient temperature, for a duration Δt r , as a thermal exposure performed after the producing the sensitive material, the temperature T r and the duration Δt r being such that the first compound, which is amorphous and has a native electrical resistivity value at ambient temperature in a range of from 1 to 30 Ω·cm, having undergone the exposing to the temperature T r for the duration Δt r , has an electrical resistivity at ambient temperature less than 50% of its native value;
determining a non-zero as an effective amount of the additional chemical element added to the first compound, thus forming a modified compound, starting from which the modified compound, having undergone the exposing to the temperature T r for the duration Δt r , has an electrical resistivity ρ a|r , at ambient temperature greater than or equal to 50% of its native value ρ a ;
wherein, in the producing the sensitive material in a thin layer, the latter is formed of the modified compound having an amount of the additional chemical element greater than or equal to the effective amount determined beforehand, the sensitive material being amorphous, having a native electrical resistivity value ρ a at ambient temperature in a range of from 1 to 30 Ω·cm, and a homogeneous chemical composition;
wherein, following the exposing the sensitive material to the temperature T r for the duration Δt r , the sensitive material then has a noise whose degradation has been at least limited.

2. The process of claim 1 , wherein the exposing the sensitive material comprises depositing a protective layer covering the sensitive material.

3. The process of claim 1 , wherein the exposing the sensitive material comprises depositing an encapsulation layer transparent to the electromagnetic radiation to be detected and intended to define a cavity in which the microbolometer is located.

4. The process of claim 1 , wherein the temperature T r is greater than or equal to 280° C.

5. The process of claim 1 , wherein the duration Δt r is greater than or equal to 90 min.

6. The process of claim 1 , wherein the sensitive material is produced at a temperature less than the temperature T r .

7. A microbolometer, comprising:
a sensitive material comprising a first compound comprising vanadium oxide and carbon and/or boron as an additional element, but excluding nitrogen, wherein the sensitive material:
is amorphous,
has an electrical resistivity at ambient temperature in a range of from 1 to 30 Ω·cm,
has been exposed, after deposition, to a temperature T r greater than or equal to 280° C., for a duration Δt r greater than or equal to 90 minutes,
a homogeneous chemical composition, and
an amount of boron, defined as the ratio of the number of boron atoms to that of vanadium, at least equal to 0.086, and/or an amount of carbon, defined as the ratio of the number of carbon atoms to that of vanadium, at least equal to 0.063.

8. The microbolometer of claim 7 , wherein the amount of oxygen, defined as the ratio of the number of oxygen atoms to that of vanadium, is in a range of from 1.42 to 1.94, to within plus or minus 0.05.

9. The microbolometer of claim 7 , wherein the sensitive material is covered by a protective layer of silicon nitride.

10. A device configured for detecting electromagnetic radiation, the device comprising:
an array of the microbolometer of claim 7 ,
wherein the microbolometers are arranged in at least one hermetic cavity delimited by an encapsulation structure transparent to the electromagnetic radiation to be detected, and
wherein the encapsulation structure comprises a layer comprising amorphous silicon.

11. The device of claim 10 , comprising a getter material located in the hermetic cavity.

12. The process of claim 1 , wherein the temperature T r is in a range of 310±5° C.

13. The process of claim 1 , wherein the sensitive material comprises the carbon.

14. The process of claim 1 , wherein the sensitive material comprises the boron.

15. The process of claim 1 , wherein the sensitive material comprises the carbon and the boron.

16. The microbolometer of claim 7 , wherein the sensitive material comprises the carbon.

17. The microbolometer of claim 7 , wherein the sensitive material comprises the boron.

18. The microbolometer of claim 7 , wherein the sensitive material comprises the carbon and the boron.

19. The device of claim 10 , wherein the sensitive material comprises the carbon.

20. The device of claim 10 , wherein the sensitive material comprises the boron.

Assignees

• Commissariat Energie Atomique

Inventors

• Pelenc Denis
• Zucchi Xavier
• Vialle Claire
• Goudon Valerie
• Aliane Abdelkader

Classifications

• G01J5/046 Primary

  Materials; Selection of thermal materials · CPC title

• G01J5/20 Primary

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