MEMS device with improved via support planarization

Patent metadata

Field	Value
Publication number	US-9335540-B2
Application number	US-201314109529-A
Country	US
Kind code	B2
Filing date	Dec 17, 2013
Priority date	Oct 15, 2013
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

A microelectromechanical (MEMS) device has a movable member supported above a substrate on a via support. The member and via support are fabricated integrally from first and second member forming layers. A first member forming layer forms a lower part of the member and supporting structure for the via support. First and second fill layers are deposited and patterned to form a plug that fills an inner cavity opening in the via structure. The plug is planarized to a planar part of the first member forming layer, and a second member forming layer is deposited over the first member forming layer and the planarized plug to form an upper part of the member. The via support may have a cavity filled by BARC layers.

First claim

What is claimed is:

1. A method of making a MEMS device, comprising:
forming a via opening within a sacrificial support layer formed over a substrate;
depositing a first member forming layer over the sacrificial support layer, including as a liner within and partially filling the via opening;
depositing a first fill layer over the first member forming layer, including over the first member forming layer within and further partially filling the via opening;
depositing a second fill layer over the first fill layer including within the via opening, the second fill layer filling the via opening to a level above a top surface of the first member forming layer;
depositing a masking material over the second fill layer, and patterning the masking material to form a mask covering the filled via opening and extending for a given lateral distance beyond a top of the via opening;
patterning the first and second fill layers using the mask to form a raised protrusion with a given step height and lateral width at the top of the via opening;
removing the mask following the patterning of the first and second fill layers;
depositing a third fill layer over the patterned first and second fill layers to fill an indentation in the raised protrusion;
removing the raised protrusion to planarize a top surface of the filled via opening with the top surface of the first member forming layer; and
depositing a second member forming layer over the first member forming layer and over the planarized top surface of the filled via opening.

2. The method of claim 1 , further comprising, after depositing the second member forming layer, patterning the first and second member forming layers to form a member.

3. The method of claim 2 , further comprising, after forming the member, removing the sacrificial support layer leaving the member supported above the substrate by the lined and filled via.

4. The method of claim 3 , wherein the MEMS device comprises a micromirror device, and the member comprises a mirror.

5. The method of claim 4 , wherein the first and second member forming layers comprise first and second metal layers.

6. The method of claim 1 , further comprising curing the first and second fill layers prior to depositing the masking material over the second fill layer.

7. The method of claim 6 , further comprising curing the first fill layer prior to depositing the second fill layer.

8. The method of claim 7 , further comprising curing the first and second fill layers after planarizing the top surface of the raised protrusion.

9. The method of claim 1 , wherein the first and second fill layers comprise layers of Bottom Anti-Reflective Coating (BARC) material.

10. The method of claim 9 , wherein the third fill layer comprises a layer of BARC material.

11. The method of claim 1 , wherein patterning the first and second fill layers patterns removes all of the second fill layer apart from the raised portion.

12. The method of claim 11 , wherein patterning the first and second fill layers leaves a reduced thickness of the first fill layer over the first member forming layer apart from the raised portion.

13. The method of claim 12 , wherein removing the raised protrusion includes removing the reduced thickness of the first fill layer.

14. A method of making a MEMS device, comprising:
forming a via opening within a sacrificial support layer formed over a substrate;
depositing a first metal layer over the sacrificial support layer, including as a liner within and partially filling the via opening;
depositing a first Bottom Anti-Reflective Coating (BARC) layer over the first metal layer, including over the first metal layer within and further partially filling the via opening;
curing the first BARC layer;
depositing a second BARC layer over the first metal layer including within the via opening, the second BARC layer filling the via opening to a level above a top surface of the first metal layer;
curing the second BARC layer;
depositing a masking material over the second BARC layer, and patterning the masking material to form a mask covering the filled via opening and extending for a given lateral distance beyond a top of the via opening;
patterning the first and second BARC layers using the mask to form a raised protrusion with a given step height and lateral width at the top of the via opening;
removing the mask following the patterning of the first and second BARC layers;
depositing a sacrificial fill layer over the patterned first and second BARC layers to fill an indentation in the raised protrusion;
after planarizing the filled indentation with the top surface of the raised protrusion, removing the raised protrusion to planarize a top surface of the filled via opening with the top surface of the first metal layer; and
depositing a second metal layer over the first metal layer and over the planarized top surface of the filled via opening.

15. The method of claim 14 , further comprising, after depositing the second metal layer, removing the sacrificial support layer.

16. The method of claim 15 , wherein the MEMS device comprises a micromirror, and further comprising patterning the first and second metal layers to form a mirror.

17. The method of claim 16 , wherein the first BARC layer is cured prior to depositing the second BARC layer.

18. The method of claim 17 , wherein the second BARC layer is cured prior to depositing the masking material.

19. The method of claim 18 , further comprising again curing the first and second BARC layers after planarizing the top surface of the raised protrusion.

20. A MEMS device comprising a micromirror, the micromirror including:
a substrate;
a first metal layer;
a second metal layer;
a first Bottom Anti-Reflective Coating (BARC) layer; and
a second BARC layer;
the first metal layer, second metal layer, first BARC layer and second BARC layer defining a mirror supported in elevated position above the substrate by a via support; the first metal layer having a planar portion configuring a lower part of the mirror and also having a depending portion configuring supporting structure of the via support and having an opening; the first BARC layer being formed over the depending portion of the first metal layer and partially filling the opening; the second BARC layer being formed over the first BARC layer and filling a remainder of the opening; the first and second BARC layers being planarized at top surfaces with the first metal layer planar portion; and the second metal layer being formed over the planar part of the first metal layer and over the planarized top surfaces of the first and second BARC layers; the second metal layer configuring an upper part of the mirror.

Assignees

• Texas Instruments Inc

Inventors

• Sherwin Lucius Marshall
• Martinez Jose Antonio
• Roth Ronald Charles
• O'Brien Sean Christopher

Classifications

• G02F1/167

  by electrophoresis · CPC title

• G02F2001/1678

  characterised by the composition or particle type · CPC title

• G02B26/0833 Primary

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

• G02F2001/1676

  Physics · mapped topic

• G02B26/005

  based on electrowetting · CPC title