Device for detecting radiation including an encapsulating structure having an improved mechanical strength

Patent metadata

Field	Value
Publication number	US-2016245701-A1
Application number	US-201615047966-A
Country	US
Kind code	A1
Filing date	Feb 19, 2016
Priority date	Feb 20, 2015
Publication date	Aug 25, 2016
Grant date	—

Abstract

The invention relates to a device for detecting electromagnetic radiation, comprising:
a substrate; a matrix of thermal detectors, which matrix is placed on the substrate; and a detector-encapsulating structure, including an encapsulating layer extending around and above the matrix of detectors so as to define with the substrate a cavity in which the matrix of detectors is located;

in which the encapsulating layer comprises at least one section, which is what is referred to as an internal bearing section, located between two adjacent detectors, and which bears directly against the substrate.

First claim

1 . Device for detecting electromagnetic radiation, comprising:
a substrate; a matrix of thermal detectors, which matrix is placed on the substrate; and a structure encapsulating the matrix of thermal detectors, including an encapsulating layer extending continuously around and above the matrix of thermal detectors so as to define with the substrate a cavity in which the matrix of thermal detectors is located; wherein the encapsulating layer comprises at least one section, which is what is referred to as an internal bearing section, located between two adjacent thermal detectors, and which bears directly against the substrate, said internal bearing section including a sidewall that is separate, in a plane parallel to the plane of the substrate, from a peripheral wall of the encapsulating layer which encircles the matrix of thermal detectors.

2 . Detecting device according to claim 1 , including a plurality of internal bearing sections each including a sidewall that delimits a profile of the internal bearing section in a plane parallel to the plane of the substrate, said profiles of the internal bearing sections being separate from one another.

3 . Detecting device according to claim 1 , in which the thermal detectors each include an absorbing membrane suitable for absorbing the radiation to be detected, which membrane is suspended above the substrate and thermally insulated therefrom by anchoring pins and thermally insulating arms, and in which at least one internal bearing section extends alongside the absorbing membranes of two adjacent thermal detectors along a longitudinal axis passing through two adjacent anchoring pins.

4 . Detecting device according to claim 3 , in which each of said anchoring pins participates in the holding above the substrate of the absorbing membranes of said two adjacent thermal detectors.

5 . Detecting device according to claim 1 , in which at least one internal bearing section has a profile, in a plane parallel to the plane of the substrate, formed from a plurality of pairwise inclined longitudinal portions and/or in which at least one internal bearing section has a profile, in a plane parallel to the plane of the substrate, extending along a longitudinal axis between two ends of said profile, said profile widening at at least one of said ends.

6 . Detecting device according to claim 1 , in which the internal bearing section has a profile, in a plane parallel to the plane of the substrate, of oblong shape, preferably with rounded longitudinal ends.

7 . Detecting device according to claim 1 , in which the encapsulating layer comprises a plurality of through-orifices, which are what are referred to as exhaust vents, placed so that at least some of the thermal detectors each have a single exhaust vent located facing the corresponding absorbing membrane, preferably plumb with the centre of said membrane.

8 . Detecting device according to claim 7 , in which each absorbing membrane includes a through-orifice facing the corresponding exhaust vent and of equal or larger size to that of said vent.

9 . Detecting device according to claim 8 , in which the suspended membrane includes a stack of a bolometric layer, a dielectric layer that is structured so as to form two separate sections, 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 sections of the dielectric layer.

10 . Detecting device according to claim 8 , in which the encapsulating structure furthermore includes a sealing layer covering the encapsulating layer so as to make the cavity hermetic, and in which the substrate comprises a tie layer placed facing the through-orifice of the corresponding membrane and suitable for ensuring the adhesion of the material of the sealing layer.

11 . Detecting device according to claim 10 , in which the tie 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.

12 . Detecting device according to claim 10 , in which the tie layer furthermore includes sections on which the holding pins rest, and/or sections on which the internal bearing sections rest, and is made of a material able to ensure the adhesion of the holding pins and/or the bearing sections.

13 . Detecting device according to claim 1 , in which 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.

14 . Method for producing a device for detecting electromagnetic radiation, including steps of:
realizing a matrix of detectors on a substrate by depositing a plurality of layers including two sacrificial layers that are stacked one on top of the other; etching the sacrificial layers locally as far as the substrate, so as to form on the one hand a continuous peripheral trench on the border of the matrix of detectors, and on the other hand at least one local trench located between two adjacent detectors; realizing an encapsulating structure by conformal deposition of an encapsulating layer on the unetched layers and in the trenches, such that the encapsulating layer extends continuously above and around the matrix of detectors and includes at least one internal bearing section in the local trench so that said internal bearing section includes a sidewall that is separate, in a plane parallel to the plane of the substrate, from a peripheral wall of the encapsulating layer which encircles the matrix of thermal detectors; and removing the sacrificial layers in order to form a cavity in which the matrix of detectors is located.

Assignees

• Commissariat Energie Atomique

Inventors

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

Classifications

• G01J5/20

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

• G01J5/0225

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

• G01J5/34

  using capacitors, e.g. pyroelectric capacitors · CPC title