Hermetically sealed MEMS mirror and method of manufacture

Patent metadata

Field	Value
Publication number	US-12078799-B2
Application number	US-202318206363-A
Country	US
Kind code	B2
Filing date	Jun 6, 2023
Priority date	Aug 24, 2016
Publication date	Sep 3, 2024
Grant date	Sep 3, 2024

Abstract

A method of making a MEMS device including forming a mirror stack on a handle layer, applying a first bonding layer to the mirror stack, and disposing a substrate on the first bonding layer. The handle layer is removed and a second bonding layer is applied. A cap layer is disposed on the second bonding layer. The mirror stack is formed by disposing a silicon layer on the handle layer, disposing a first insulating layer on the silicon layer, etching portions of the first insulating layer, and depositing a first conductive layer on the first insulating layer. The formation also includes depositing a second insulating layer on the first conductive layer, a portion of the second insulating layer to expose a portion of the first conductive layer exposed, and forming a conductive pad on the exposed portion of the first conductive layer.

First claim

The invention claimed is:

1. A method of making a micro-electro mechanical system (MEMS) device, comprising:
forming a MEMS mirror stack on a handle layer;
applying a first bonding layer to the MEMS mirror stack;
disposing a substrate on the first bonding layer to mechanically anchor the MEMS mirror stack to the substrate and seal against ingress of environmental contaminants;
removing the handle layer;
applying a second bonding layer to the MEMS mirror stack; and
disposing a cap layer on the second bonding layer to mechanically anchor the cap layer to the MEMS mirror stack and seal against ingress of environmental contaminants;
wherein forming the MEMS mirror stack comprises:
disposing a silicon layer on the handle layer;
disposing a first insulating layer on the silicon layer;
etching portions of the first insulating layer;
depositing a first conductive layer on the first insulating layer and into the etched portions thereof, the first conductive layer deposited so as to have a width greater than a width of the substrate in at least one direction;
depositing a second insulating layer on the first conductive layer;
removing at least one portion of the second insulating layer to expose at least one portion of the first conductive layer exposed due to the first conductive layer having a width greater than the width of the substrate in the at least one direction; and
forming a conductive pad on the at least one exposed portion of the first conductive layer and extending away from the MEMS mirror stack opposite the cap layer.

2. The method of claim 1 , wherein forming the MEMS mirror stack on the handle layer further comprises forming a lower chamber by removing at least one portion of the second insulating layer, first conductive layer, and first insulating layer.

3. The method of claim 2 , wherein the lower chamber is formed so as to have air pressure therein within a threshold of vacuum.

4. The method of claim 2 , wherein applying the first bonding layer to the MEMS mirror stack comprises applying the first bonding layer to the second insulating layer.

5. The method of claim 4 , further comprising processing the silicon layer so as to form a stator, and associating a rotor with the stator and configuring the rotor to rotate with respect to the stator.

6. The method of claim 1 , wherein the cap layer is disposed on the second bonding layer in an environment having pressure substantially at a vacuum.

7. The method of claim 1 , wherein the cap layer is formed to have a width less than a width of the MEMS mirror stack in at least one direction.

8. A method for creating a micro-electro mechanical system (MEMS) device, comprising:
forming a MEMS mirror stack on a handle layer by:
disposing a silicon layer on the handle layer;
disposing a first insulating layer on the silicon layer;
etching portions of the first insulating layer;
depositing a first conductive layer on the first insulating layer and into the etched portions thereof; and
depositing a second insulating layer on the first conductive layer;

anchoring and sealing the MEMS mirror stack to a substrate using first and second bonding layers;
removing the handle layer; and
forming a conductive pad on an exposed portion of the first conductive layer of the MEMS mirror stack.

9. The method of claim 8 , further comprising forming a lower chamber by removing portions of the first insulating layer and the first conductive layer.

10. The method of claim 9 , wherein the lower chamber is near vacuum.

11. The method of claim 9 , wherein the first bonding layer is applied to the second insulating layer.

12. The method of claim 11 , further comprising processing the silicon layer to form a stator, and associating a rotor with the stator.

13. The method of claim 8 , further comprising applying a cap layer on the MEMS mirror stack.

14. The method of claim 13 , wherein the applying of the cap layer is performed in an environment having pressure substantially at vacuum.

15. The method of claim 13 , wherein the cap layer is narrower than the MEMS mirror stack in one direction.

16. A method for making a MEMS device, comprising:
forming a MEMS mirror stack on a handle layer;
applying a first bonding layer to the MEMS mirror stack;
disposing a substrate on the first bonding layer to mechanically anchor the MEMS mirror stack to the substrate and seal against environmental contaminants;
removing the handle layer;
applying a second bonding layer to the MEMS mirror stack; and
disposing a cap layer on the second bonding layer to mechanically anchor the cap layer to the MEMS mirror stack and seal against environmental contaminants.

17. The method of claim 16 , wherein forming the MEMS mirror stack on the handle layer is performed so as to form a lower chamber.

18. The method of claim 17 , wherein the lower chamber is formed at vacuum.

19. The method of claim 16 , wherein the cap layer is disposed on the second bonding layer in an environment having pressure substantially at vacuum.

20. The method of claim 16 , wherein the cap layer is narrower than the MEMS mirror stack in at least one direction.

Assignees

• St Microelectronics Srl
• Stmicroelectron S R L

Inventors

• Allegato Giorgio
• Costantini Sonia
• Vercesi Federico
• Carminati Roberto

Classifications

• B81C1/00523

  Etching material · CPC title

• B81C2203/0109

  Bonding an individual cap on the substrate · CPC title

• B81C2203/019

  characterised by the material or arrangement of seals between parts · CPC title

• G02B26/0833

  the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B) · CPC title

• B81B2201/042

  Micromirrors, not used as optical switches · CPC title