Device for detecting electromagnetic radiation possessing a hermetic encapsulating structure comprising an exhaust vent

Patent metadata

Field	Value
Publication number	US-2016245702-A1
Application number	US-201615048058-A
Country	US
Kind code	A1
Filing date	Feb 19, 2016
Priority date	Feb 20, 2015
Publication date	Aug 25, 2016
Grant date	—

Abstract

A device for detecting electromagnetic radiation, including a substrate; at least one thermal detector, placed on the substrate, including an absorbing membrane suspended above the substrate; and an encapsulating structure encapsulating the thermal detector, including an encapsulating layer extending around and above the thermal detector so as to define with the substrate a cavity in which the thermal detector is located; wherein the encapsulating layer includes at least one through-orifice that is what is referred to as an exhaust vent, each exhaust vent being placed so that at least one thermal detector has a single exhaust vent located facing the corresponding absorbing membrane, preferably plumb with the centre of said absorbing membrane.

First claim

1 . A device for detecting electromagnetic radiation, comprising:
a substrate; at least one thermal detector, placed on the substrate, including a membrane suitable for absorbing the radiation to be detected, which membrane is suspended above the substrate and thermally insulated therefrom by thermally insulating holding elements; and an encapsulating structure encapsulating said at least one thermal detector, including an encapsulating layer extending around and above said at least one thermal detector so as to define with the substrate a cavity wherein said at least one thermal detector is located; characterized in that wherein the encapsulating layer comprises at least one through-orifice that is what is referred to as an exhaust vent, each exhaust vent being placed so that at least one thermal detector has a single exhaust vent located facing the corresponding absorbing membrane, preferably plumb with the centre of said absorbing membrane.

2 . The detecting device according to claim 1 , wherein a plurality of thermal detectors is placed in said cavity, the encapsulating layer comprising a plurality of exhaust vents placed so that at least some of said thermal detectors each have a single exhaust vent located facing the corresponding absorbing membrane, or wherein a single thermal detector is placed in said cavity, the encapsulating layer then comprising a single exhaust vent located facing the absorbing membrane of the thermal detector.

3 . The detecting device according to claim 1 , wherein said absorbing membrane, facing which is located an exhaust vent, includes a through-orifice located plumb with said exhaust vent and of a size equal to or larger than that of said vent.

4 . The detecting device according to claim 3 , wherein the absorbing membrane includes a stack of a bolometric layer, a dielectric layer that is structured so as to form two separate portions, and an electrically conductive layer that is structured so as to form three electrodes, two of said electrodes, which are intended to be raised to the same electrical potential, flanking the third electrode, which is what is referred to as the central electrode and which is intended to be raised to a different electrical potential, each electrode making contact with the bolometric layer, the central electrode being electrically insulated from the other electrodes by the dielectric layer, the orifice passing through the central electrode and the bolometric layer in a zone located between the portions of the dielectric layer.

5 . The detecting device according to claim 3 wherein the encapsulating structure furthermore includes a sealing layer covering the encapsulating layer so as to make the cavity hermetic, and wherein the substrate comprises a fixing layer placed facing the through-orifice of the corresponding membrane and suitable for ensuring the adhesion of the material of the sealing layer.

6 . The detecting device according to claim 5 , wherein the fixing layer extends under the whole of the corresponding membrane and is made of a material suitable for furthermore reflecting the electromagnetic radiation to be detected.

7 . The detecting device according to claim 1 , wherein the exhaust vent has a transverse profile, in a plane orthogonal to the plane of the substrate, the width of which increases with distance from the substrate.

8 . The detecting device according to claim 7 , wherein the encapsulating structure furthermore includes a sealing layer covering the encapsulating layer so as to make the cavity hermetic, the sealing layer including a border that extends in the direction of the thickness of the sealing layer, from the border of the exhaust vent, with a non-zero angle α a relative to an axis orthogonal to the plane of the substrate, and in which wherein the transverse profile of the exhaust vent makes an angle β to the same orthogonal axis larger than the angle α.

9 . The detecting device according to claim 7 , wherein the longitudinal end of the exhaust vent has a circularly arcuate shape, or is formed from a succession of substantially rectilinear segments that are inclined relative to one another.

10 . The detecting device according to claim 1 , including a matrix of thermal detectors, wherein the encapsulating layer comprises at least one portion, which is what is referred to as an internal bearing portion, located between two adjacent detectors, and which bears directly against the substrate.

11 . The detecting device according to claim 10 , wherein the internal bearing portion has a profile, in a plane parallel to the plane of the substrate, of oblong shape, preferably with rounded longitudinal ends.

12 . The detecting device according to claim 10 , wherein the internal bearing portion includes a sidewall and a bottom portion, said sidewall extending in a plane substantially orthogonal to the plane of the substrate over the entire height of the cavity, and the bottom portion making contact with the substrate.

13 . The detecting device according to claim 10 , wherein at least one internal bearing portion is placed between two adjacent absorbing membranes and two adjacent holding pins, each of said holding pins participating in the holding of said adjacent membranes, and in which wherein the internal bearing portion is oriented longitudinally alongside said membranes.

14 . The detecting device according to claim 1 , wherein the encapsulating layer comprises a peripheral wall that encircles the matrix of detectors, and that has a cross section, in a plane parallel to the plane of the substrate, of square or rectangular shape the corners of which are rounded.

15 . The detecting device according to claim 10 , the thermally insulating holding elements including holding pins, wherein the fixing layer furthermore includes portions on which the holding pins rest, and/or portions on which internal bearing portions of the encapsulating layer rest, and is made from a material able to ensure the adhesion of the holding pins and/or the bearing portions.

Assignees

• Commissariat Energie Atomique

Inventors

• Dumont Geoffroy
• Carle Laurent
• Imperinetti Pierre
• Pocas Stephane
• Yon Jean-Jacques

Classifications

• G01J5/0225

  Shape of the cavity itself or of elements contained in or suspended over the cavity · CPC title

• G01J5/20

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

• G01J2005/0077

  Imaging · CPC title

• G01J5/10

  using electric radiation detectors · CPC title

• G01J5/045 Primary

  Sealings; Vacuum enclosures; Encapsulated packages; Wafer bonding structures; Getter arrangements (getter arrangements per se H10W76/48, H10P36/03) · CPC title