ENCAPSULATION STRUCTURE INCLUDING A MECHANICALLY REINFORCED CAP AND WITH A GETTER EFFECT

• US 20150028433A1
• Filed: 07/15/2014
• Published: 01/29/2015
• Est. Priority Date: 07/26/2013
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: BAILLIN, Xavier, DIEM, Bernard, POLIZZI, Jean-Philippe, ROUZAUD, Andre
• Granted Patent: US 9,511,991 B2
• Time in Patent Office: Days
• US Class Current: 257/415
• CPC Class Codes: B81B 2201/0228 Inertial sensors
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81B 7/0077 Other packages not provided for in groups B81B7/0035 - B81B7/0074
• CPC Class Codes: B81C 1/00285 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: B81C 1/00682 Treatments for improving mechanical properties, not provided for in B81C1/00658 - B81C1/0065
• CPC Class Codes: B81C 2201/053 Depositing a protective layers
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• CPC Class Codes: B81C 2203/0163 Reinforcing a cap, e.g. with ribs
• CPC Class Codes: H01L 2224/16145 the bodies being stacked
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation

Abstract

A structure (100) for encapsulating at least one microdevice (104) produced on and/or in a substrate (102) and positioned in at least one cavity (110) formed between the substrate and a cap (106) rigidly attached to the substrate, in which the cap includes at least:

• • one layer (112) of a first material, one face of which (114) forms an inner wall of the cavity, and
  • mechanical reinforcement portions (116) rigidly attached at least to the said face of the layer of the first material, partly covering the said face of the layer of the first material, and having gas absorption and/or adsorption properties,
  • and in which the Young'"'"'s modulus of a second material of the mechanical reinforcement portions is higher than that of the first material.

Claims

1. The structure for encapsulating at least one microdevice produced on and/or in a substrate and positioned in at least one cavity formed between the substrate and a cap rigidly attached to the substrate, in which the cap includes at least:

one layer of a first material, one face of which forms an inner wall of the cavity, and

mechanical reinforcement portions rigidly connected to at least the said face of the layer of the first material, partly covering the said face of the layer of the first material, and having gas absorption and/or adsorption properties, where these mechanical reinforcement portions include at least one second material, the Young'"'"'s modulus of which is higher than that of the first material.

2. An encapsulation structure according to claim 1, in which the second material is a metallic getter material.

3. An encapsulation structure according to claim 1, in which each of the mechanical reinforcement portions includes at least one first layer of the second material, and at least one second layer of a third metallic getter material such that the first layer of the second material is positioned between the layer of the first material and the second layer of the third material and/or is covered by the second layer of the third material.

4. An encapsulation structure according to claim 1, in which each of the mechanical reinforcement portions includes a stack of layers of which at least two of the said layers form a bimetallic strip exerting on the cap a force directed to the exterior of the cavity.

5. An encapsulation structure according to claim 1, in which the material is made of Si and/or silica and/or silicon nitride, and the second material is made of Cr and/or Ti and/or Co and/or Fe and/or Mn and/or Mo and/or Ta and/or V and/or W and/or Pd and/or Rh and/or Pt and/or Ru and/or Zr.

6. An encapsulation structure according to claim 2, in which the metallic getter material(s) are made of Cr and/or Ti and/or Co and/or Fe and/or Mn and/or Mo and/or Ta and/or V and/or W and/or Pd and/or Rh and/or Pt and/or Ru and/or Zr.

7. An encapsulation structure according to claim 1, in which each of the mechanical reinforcement portions is of roughly rectangular parallelepipedic shape, and where the mechanical reinforcement portions are positioned roughly parallel to one another.

8. An encapsulation structure according to claim 1, in which the mechanical reinforcement portions form a mesh on the said face of the layer of the first material.

9. An encapsulation structure according to claim 1, in which a ratio r=h/H is between approximately 0.6 and 0.9, and a ratio R=b/t is greater than or equal to approximately 0.7, where:

h;

thickness of the layer of the first material;

H;

sum of h and of the thickness of one of the mechanical reinforcement portions;

b;

width of one of the mechanical reinforcement portions;

t;

period with which the mechanical reinforcement portions are positioned on the layer of the first material.

10. An encapsulation structure according to claim 1, also including electrically conductive vias produced all the way through the substrate and/or the layer of the first material, next to the cavity.

11. A microelectronic device including at least two encapsulation structures according to claim 10, positioned one above the other, in which at least one electrically conductive via of a first of the two encapsulation structures is electrically connected to at least one electrically conductive via of a second of the two encapsulation structures, directly or through an interposer.

12. A method of encapsulation of at least one microdevice, including at least the following steps:

production of the microdevice on and/or in a substrate;

production of mechanical reinforcement portions rigidly attached to at least one face of a layer of a first material, partly covering the said face of the layer of the first material, and having gas absorption and/or adsorption properties, where the layer of the first material and the mechanical reinforcement portions form a cap;

rigid attachment of the cap to the substrate such that the microdevice is encapsulated in a cavity formed between the cap and the substrate;

and in which the mechanical reinforcement portions include at least one second material, the Young'"'"'s modulus of which is higher than that of the first material.

14. A method according to claim 12, in which the second material is a metallic getter material.

15. A method according to claim 12, in which each of the mechanical reinforcement portions is produced at least by a deposition of a first layer of the second material, and of a second layer of a third metallic getter material such that the first layer of the second material is positioned between the layer of the first material and the second layer of the third material and/or is covered by the second layer of the third material.

16. A method according to claim 12, in which each of the mechanical reinforcement portions is produced by deposition of a stack of layers of which at least two of the said layers form a bimetallic strip exerting on the cap a force directed to the exterior of the cavity.

17. A method according to claim 12, also including, after rigid attachment of the cap to the substrate, or etching of the portion of sacrificial material, production of electrically conductive vias all the way through the substrate and/or the layer of the first material, next to the cavity.

18. A method for production of a microelectronic device, including implementation of a method of encapsulation according to claim 17 forming at least two encapsulation structures, where the said encapsulation structures are positioned one above the other, and where at least one electrically conductive via of a first of the two encapsulation structures is then electrically connected to a least one electrically conductive via of a second of the two encapsulation structures directly or through an interposer.

13. A method of encapsulation of at least one microdevice, including at least the following steps:

production of the microdevice on and/or in a substrate;

production of a portion of sacrificial material at least on the microdevice and such that the volume occupied by the portion of sacrificial material is equal to at least one part of a volume of a cavity in which the microdevice is intended to be encapsulated;

production of mechanical reinforcement portions on and/or in the portion of sacrificial material and having gas absorption and/or adsorption properties;

deposition of a layer of a first material covering at least the mechanical reinforcement portions and the portion of sacrificial material;

etching of the portion of sacrificial material, forming the cavity in which the microdevice is encapsulated;

and in which the mechanical reinforcement portions include at least one second material, the Young'"'"'s modulus of which is higher than that of the first material.