Microelectromechanical system (MEMS) structure and method of formation

Patent metadata

Field	Value
Publication number	US-10928624-B2
Application number	US-201816008442-A
Country	US
Kind code	B2
Filing date	Jun 14, 2018
Priority date	Dec 29, 2017
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

A microelectromechanical system (MEMS) structure includes at least first and second metal vias. Each of the first and second metal vias includes a respective planar metal layer having a first thickness and a respective post formed from the planar metal layer. The post has a sidewall, and the sidewall has a second thickness greater than 14% of the first thickness.

First claim

What is claimed is:

1. A method of manufacturing a device, the method comprising:
forming a metal layer on a layer and in a cavity in the layer;
forming a polymer layer on the metal layer and in the cavity;
removing a first portion of the polymer layer to leave a second portion of the polymer layer in the cavity;
removing a first portion of the metal layer to leave a second portion of the metal layer in the cavity, after removing the first portion of the polymer layer; and
removing the second portion of the polymer layer from the cavity, after removing the first portion of the polymer layer.

2. The method of claim 1 , wherein the polymer layer is uncured.

3. The method of claim 1 , wherein removing the first portion of the metal layer comprises exposing the metal layer to a metal etching plasma while the polymer layer covers the second portion of the metal layer.

4. The method of claim 1 , wherein removing the first portion of the metal layer comprises wet etching the metal layer while the polymer layer covers the second portion of the metal layer.

5. The method of claim 1 , wherein the metal layer is a first metal layer, the method further comprising forming a second metal layer on the layer and in the cavity over the second portion of the first metal layer.

6. The method of claim 1 , wherein the layer is a first layer, the cavity is a first cavity, the polymer layer is a first polymer layer, and the method further comprises:
forming a second layer on a second metal layer;
forming a second cavity in the second layer;
forming a third metal layer on the second layer and in the second cavity;
forming a second polymer layer on the third metal layer and in the second cavity over the third metal layer in the second cavity;
removing a first portion of the second polymer layer to leave a second portion of the second polymer layer in the second cavity;
removing a first portion of the third metal layer to leave a second portion of the third metal layer in the second cavity;
removing the second portion of the second polymer layer from the second cavity; and
forming a fourth metal layer on the second layer and in the second cavity over the second portion of the third metal layer.

7. The method of claim 6 , wherein the second polymer layer is uncured.

8. The method of claim 6 , wherein removing the first portion of the third metal layer comprises exposing the third metal layer to a metal etching plasma while the second polymer layer covers the second portion of the third metal layer.

9. The method of claim 6 , wherein removing the first portion of the third metal layer comprises wet etching the third metal layer.

10. The method of claim 6 , further comprising cleaning the second portion of the third metal layer after removing the second portion of the second polymer layer and before forming the fourth metal layer on the second layer.

11. The method of claim 1 , further comprising:
forming the layer on a substrate; and
forming the cavity in the layer.

12. The method of claim 5 , further comprising cleaning the second portion of the metal layer in the cavity after removing the second portion of the layer and before forming the second metal layer on the layer.

13. The method of claim 1 , wherein the polymer layer comprises photoresist, a bottom antireflective coating, or a gap filler material.

14. The method of claim 1 , wherein removing the first portion of the polymer layer comprises ashing the polymer layer.

15. The method of claim 1 , wherein a top surface the second portion of the polymer layer is below a top surface of the first metal layer.

16. A method of manufacturing a device, the method comprising:
forming a first metal layer on a layer and in a cavity in the layer;
applying photoresist on the first metal layer and in the cavity over the first metal layer;
removing a first portion of the photoresist to leave a second portion of the photoresist in the cavity;
removing a first portion of the first metal layer to leave a second portion of the first metal layer in the cavity, after removing the first portion of the photoresist;
removing the second portion of the photoresist from the cavity, after removing the first portion of the first metal layer;
forming a second metal layer on the layer and in the cavity over the second portion of the first metal layer; and
removing the layer to form a metal via, the metal via having a sidewall;
a thickness of the sidewall of the metal via being least 20% of a thickness of the second metal layer outside the metal via.

17. The method of claim 16 , wherein the thickness of the sidewall of the metal via is least 28% of the thickness of the second metal layer outside the metal via.

18. The method of claim 16 , wherein removing the first portion of the first metal layer comprises exposing the first metal layer to a metal etching plasma.

19. The method of claim 16 , wherein removing the first portion of the first metal layer comprises wet etching the first metal layer.

20. The method of claim 16 , further comprising cleaning the second portion of the first metal layer in the cavity after removing the first portion of the photoresist and before forming the second metal layer on the layer.

Assignees

• Texas Instruments Inc

Inventors

• Martinez Jose A

Classifications

• B81C2201/0133

  Wet etching · CPC title

• B81B2201/042

  Micromirrors, not used as optical switches · 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

• G02B26/0841 Primary

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

• B81C1/00047

  Cavities · CPC title