Micromechanical device with via strut

Patent metadata

Field	Value
Publication number	US-10775609-B2
Application number	US-201816125237-A
Country	US
Kind code	B2
Filing date	Sep 7, 2018
Priority date	Sep 7, 2018
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

Described examples include a micromechanical device including a substrate and a base formed on a surface of the substrate; and a first layer extending from the base to a plane separated from the base by a via. The first layer forms an outer layer of the via and has a portion lying in the plane and surrounding the via. A first fill is formed in a first portion of the via. A strut is in the via and on the first fill. A second fill is in a second portion of the via on the strut and extends from the strut to the plane. A second layer is over the second fill and at least a portion of the second layer is over the portion of the first layer lying in the plane.

First claim

What is claimed is:

1. A micromechanical device, comprising:
a substrate and a base formed on a surface of the substrate;
a first layer extending from the base to a plane separated from the base by a via, the first layer forming an outer layer of the via and having a portion lying in the plane and surrounding the via;
a first fill in a first portion of the via;
a strut in the via on the first fill;
a second fill in a second portion of the via, the second portion of the via extending from the strut to the plane, the second fill extending from the strut to a height less than 5% of a height of the via above the plane; and
a second layer over the second fill, at least a portion of the second layer being over the portion of the first layer lying in the plane.

2. The micromechanical device of claim 1 wherein the first layer is an aluminum alloy.

3. The micromechanical device of claim 1 wherein the strut contacts the outer layer over a circumference of the strut in the via.

4. The micromechanical device of claim 1 wherein the strut is between 1 and 50 nm thick.

5. The micromechanical device of claim 1 wherein the first fill is a polymer.

6. The micromechanical device of claim 1 wherein the first fill and the second fill are formed from a same material.

7. The micromechanical device of claim 1 wherein the strut is an aluminum alloy.

8. The micromechanical device of claim 1 , wherein the strut is one taken from a group consisting essentially of: silicon dioxide, silicon nitride, silicon oxynitride, and aluminum oxide.

9. The micromechanical device of claim 1 wherein the strut is a non-metal layer.

10. The micromechanical device of claim 1 , wherein the strut is a metal layer.

11. The micromechanical device of claim 1 wherein the via is an inverted conical frustum.

12. The micromechanical device of claim 1 wherein the base is a torsional hinge.

13. The micromechanical device of claim 1 wherein the base is a portion of the surface of the substrate.

14. A micromirror device, comprising:
a substrate and a base formed on a surface of the substrate;
a first metal layer extending from the base to a plane separated from the base by a via, the first metal layer forming an outer layer of the via and having a portion lying in the plane;
a first fill in a first portion of the via, the first fill including a polymer;
a strut in the via on the first fill, the strut including a metal;
a second fill in a second portion of the via, the second fill including the polymer, the second fill extending from the strut to a height less than 5% of a height of the via above the plane; and
a second metal layer over the second fill, at least a portion of the second metal layer being over the portion of the first metal layer lying in the plane.

15. The micromirror device of claim 14 wherein the first metal layer includes aluminum.

16. The micromirror device of claim 14 wherein the second metal layer includes aluminum.

17. The micromirror device of claim 16 wherein the second metal layer forms a mirror of the micromirror.

18. The micromirror device of claim 14 wherein the polymer is BARC.

19. The micromirror device of claim 14 wherein the strut includes aluminum.

20. A method comprising:
forming a sacrificial layer on a base formed on a surface of a substrate, the sacrificial layer having an upper surface away from the base;
forming an opening in the upper surface of the sacrificial layer, and exposing a portion of the base in the opening;
depositing a first layer on the upper surface of the sacrificial layer, extending into the opening and onto the exposed portion of the base;
depositing a first fill layer onto the first layer;
etching the first fill layer to remove the first fill layer from a surface of the first layer over the upper surface of the sacrificial layer and to form a first fill in the opening, the first fill having an upper surface closer to the base than to the upper surface of the sacrificial layer;
depositing a second layer on the first layer over the upper surface of the sacrificial layer and on the upper surface of the first fill, the second layer having an upper surface away from the sacrificial layer;
depositing a second fill layer on the upper surface of the second layer;
etching the second fill layer to remove the second fill layer from the upper surface of the second layer over the upper surface of the sacrificial layer, and forming a second fill filling a remainder of the opening, the second fill having an exposed upper surface;
depositing a third layer on the upper surface of the second layer over the upper surface of the sacrificial layer and on the exposed upper surface of the second fill;
patterning the first layer, the second layer and the third layer; and
removing the sacrificial layer.

21. The method of claim 20 wherein the first layer, the second layer and the third layer are metal.

22. The method of claim 21 wherein the metal includes aluminum.

23. The method of claim 20 wherein the first fill layer and the second fill layer include a polymer.

24. The method of claim 20 wherein depositing the first fill layer and depositing the second fill layer include depositing a spin-on coating.

25. The method of claim 20 wherein etching of the first fill layer and etching of the second fill layer include an anisotropic etching.

26. The method of claim 20 wherein depositing the first layer, depositing the second layer and depositing the third layer include depositing using physical vapor deposition.

27. The method of claim 20 , wherein the second layer is a non-metal.

28. The method of claim 20 , wherein depositing the second layer includes depositing one selected from a group consisting essentially of: silicon dioxide, silicon nitride, silicon oxynitride, and aluminum oxide.

29. The method of claim 28 , wherein the first and third layers are aluminum.

Assignees

• Texas Instruments Inc

Inventors

• Looney Stephen Howard
• Martinez Jose Antonio

Classifications

• G02B26/0841 Primary

  the reflecting element being moved or deformed by electrostatic means · CPC title

• B81B7/02

  containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS] (B81B7/04 takes precedence) · CPC title

• B81B2201/042

  Micromirrors, not used as optical switches · CPC title

• B81C1/00341

  Processes for manufacturing microsystems not provided for in groups B81C1/00023 - B81C1/00261 · CPC title

• B81B3/007 Primary

  For controlling stiffness, e.g. ribs · CPC title