Hermetically sealed mems mirror and method of manufacture

Patent metadata

Field	Value
Publication number	US-2020033591-A1
Application number	US-201916591854-A
Country	US
Kind code	A1
Filing date	Oct 3, 2019
Priority date	Aug 24, 2016
Publication date	Jan 30, 2020
Grant date	—

Abstract

A method for making a micro-electro mechanical (MEMS) device includes forming a MEMS mirror stack on a handle layer, and applying a first bonding layer to the MEMS mirror stack. The method continues with disposing a substrate on the first bonding layer such that the MEMS mirror stack is mechanically anchored to the substrate and so as to seal against ingress of environmental contaminants, removing the handle layer, and applying a second bonding layer to the MEMS mirror stack. A cap layer is disposed on the second bonding layer such that the cap layer is mechanically anchored to the MEMS mirror stack and so as to seal against ingress of environmental contaminants.

First claim

1 . A method of making a micro-electro mechanical (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 such that the MEMS mirror stack is mechanically anchored to the substrate and so as to 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 such that the cap layer is mechanically anchored to the MEMS mirror stack and so as to seal against ingress of environmental contaminants.

2 . The method of claim 1 , wherein forming the MEMS mirror stack on the handle layer 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; and depositing a second insulating layer on the first conductive layer.

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

4 . The method of claim 3 , 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 3 , further comprising removing at least one portion of the second insulating layer so as to expose at least one portion of the first conductive layer, and forming a conductive pad on the at least one exposed portion of the first conductive layer.

7 . The method of claim 6 , wherein the MEMS mirror stack is formed to have a width greater than a width of the substrate in at least one direction; and wherein the conductive pad extends away from the MEMS mirror stack opposite the cap layer and is exposed by the MEMS mirror stack having the width greater than the width of the substrate in the at least one direction.

8 . The method of claim 2 , further comprising depositing a second conductive layer on the silicon layer.

9 . 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.

10 . 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 such that the MEMS mirror stack is mechanically anchored to the substrate and so as to 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 such that the cap layer is mechanically anchored to the MEMS mirror stack and so as to seal against ingress of environmental contaminants; wherein the MEMS 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;
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.

11 . The method of claim 10 , wherein forming the MEMS mirror stack on the handle layer further comprises removing at least one portion of the second insulating layer, first conductive layer, and first insulating layer so as to form a lower chamber.

12 . The method of claim 11 , wherein the lower chamber is formed so as to have air pressure therein within a threshold of vacuum.

13 . The method of claim 11 , wherein applying the first bonding layer to the MEMS mirror stack comprises applying the first bonding layer to the second insulating layer.

14 . The method of claim 13 , 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.

15 . The method of claim 10 , wherein the cap layer is disposed on the second bonding layer in an environment having pressure substantially at a vacuum.

16 . The method of claim 10 , wherein the transparent cap layer is formed to have a width less than a width of the MEMS mirror stack in at least one direction.

17 . A method of making a micro-electro mechanical (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;
applying a first bonding layer to the MEMS mirror stack; and disposing a substrate on the first bonding layer such that the MEMS mirror stack is mechanically anchored to the substrate and so as to seal against ingress of environmental contaminants.

18 . The method of claim 17 , wherein forming the MEMS mirror stack on the handle layer further comprises removing at least one portion of the second insulating layer, first conductive layer, and first insulating layer so as to form a lower chamber.

19 . The method of claim 18 , wherein applying the first bonding layer to the MEMS mirror stack comprises applying the first bonding layer to the second insulating layer.

Assignees

• St Microelectronics Srl

Inventors

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

Classifications

• G02B26/105 Primary

  with one or more pivoting mirrors or galvano-mirrors (G02B26/101 takes precedence) · CPC title

• B81C2203/0109

  Bonding an individual cap on the substrate · 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

• B81C2203/019

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

• B81B2201/042

  Micromirrors, not used as optical switches · CPC title