Process and structure for fabrication of MEMS device having isolated edge posts
View Patent ↗A method of fabricating an array of MEMS devices includes the formation of support structures located at the edge of upper strip electrodes. A support structure is etched to form a pair of individual support structures located at the edges of a pair of adjacent electrodes. The electrodes themselves may be used as a hard mask during the etching of these support structures. A resultant array of MEMS devices includes support structures having a face located at the edge of an overlying electrode and coincident with the edge of the overlying electrode.
1. A method of fabricating a microelectromechanical systems (MEMS) device, comprising:
forming an electrode layer over a substrate;
depositing a sacrificial layer over the electrode layer;
forming a plurality of support structures, said support structures extending through the sacrificial layer, wherein at least some of said plurality of support structures comprise edge support structures;
depositing a mechanical layer over the plurality of support structures;
patterning the mechanical layer to form strips, wherein said strips are separated by gaps, and wherein said gaps are located over a central portion of each of said edge support structures; and
after forming the plurality of support structures, etching a portion of each of said edge support structures underlying the gaps, thereby forming isolated edge support structures.
2. The method of claim 1 , wherein etching a portion of each of said edge support structures underlying the gaps comprises etching a central portion of each of said edge support structures to form two isolated edge support structures.
3. The method of claim 1 , wherein patterning the mechanical layer to form strips comprises using a mask, and wherein etching a portion of each of said edge support structures comprises using the same mask.
4. The method of claim 1 , wherein the patterned mechanical layer is used as a hard mask during the etching of a portion of each of said edge support structures.
5. The method of claim 1 , additionally comprising removing said sacrificial material.
6. The method of claim 1 , wherein forming a plurality of support structures comprises:
patterning the layer of sacrificial material to form apertures;
depositing a layer of support structure material over the patterned sacrificial layer and into the apertures; and
patterning the layer of support structure material to form support structures.
7. The method of claim 6 , wherein patterning the layer of sacrificial material to form apertures comprises patterning the layer of sacrificial material to form tapered apertures.
8. The method of claim 6 , additionally comprising depositing a reflective layer over the sacrificial layer prior to patterning the sacrificial layer.
9. The method of claim 6 , additionally comprising depositing a reflective layer over the sacrificial layer after patterning the sacrificial layer.
10. The method of claim 9 , wherein etching a portion of each of said edge support structures comprises using a plasma etch.
11. The method of claim 9 , wherein patterning the layer of support structure material to form support structures comprises using a plasma etch or wet etch.
12. The method of claim 6 , wherein patterning the layer of support structure material to form support structures comprises removing portions of the support structure layer located away from the apertures, thereby forming support structures having wing portions which extend horizontally along the sacrificial layer near the apertures.
13. The method of claim 1 , wherein the electrode layer comprises indium tin oxide.
14. The method of claim 1 , wherein the sacrificial layer comprises molybdenum, silicon, tungsten, or tantalum.
15. The method of claim 1 , wherein the support structures comprise a material selected from the group of: SiO 2 and SiN x .
16. The method of claim 1 , wherein the mechanical layer comprises a material selected from the group of: nickel and aluminum.
17. The method of claim 16 , wherein the mechanical layer is used as a hard mask during the etching of the portions of the edge support structures.
18. The method of claim 1 , additionally comprising depositing a partially reflective layer over the substrate.
19. The method of claim 18 , wherein the partially reflective layer is deposited over the electrode layer.
20. The method of claim 18 , wherein the partially reflective layer comprises chromium.
21. The method of claim 1 , additionally comprising depositing a dielectric layer over the electrode layer.
22. The method of claim 21 , wherein the dielectric layer comprises a material selected from the group of: SiO 2 and SiN x .
23. The method of claim 1 , additionally comprising depositing a reflective layer over the sacrificial layer.
24. The method of claim 23 , wherein the reflective layer comprises a material selected from the group of: aluminum, silver, gold, copper, palladium, platinum, and rhodium.
25. The method of claim 23 , additionally comprising etching the reflective layer to remove the portions of the reflective layer located under the gaps in the mechanical layer.
26. A microelectromechanical systems device fabricated by the method of claim 1 .