MEMS anchors
The invention relates to an improved apparatus and method for the design and manufacture of MEMS anchoring structures for light modulators in order to address the stresses of beams mounted on them.
1. A MEMS device comprising:
a substrate having a primary, horizontal face, upon which the MEMS device is formed;
a beam suspended over the substrate by an anchor having a shell structure, the shell structure comprising:
a non-horizontal elevating portion coupled to the primary face of the substrate;
a substantially horizontal shelf portion elevated over the substrate by the non-horizontal elevating portion; and
a non-horizontal shell stiffening portion, from which the beam extends, extending from the shelf portion.
2. The device of claim 1 , further comprising a shutter connected to said beam.
3. The device of claim 1 wherein said non-horizontal shell stiffening portion comprises at least two unit normal vectors that are substantially different.
4. The device of claim 1 wherein at least two non-horizontal shell stiffening portions are coupled to each other as well as to the substantially horizontal shelf portion; and wherein the normal vectors of said non-horizontal shell stiffening portions are substantially different.
5. The device of claim 1 wherein one or more substantially horizontal shelf portions are further coupled to one or more non-horizontal shell stiffening portions.
6. The device of claim 1 wherein the non-horizontal elevating portions form a closed space or a well.
7. The device of claim 1 wherein the suspended beam has a height that is at least 1.4 times its width.
8. The device of claim 1 wherein the non-horizontal stiffening portion is made from the same material as the horizontal shelf portion.
9. The device of claim 1 wherein the beam is made from a different material than the horizontal shelf portion.
10. The device of claim 1 wherein the beam is coupled to the horizontal portion.
11. The device of claim 1 wherein two or more beams extend from the anchor structure.
12. The device of claim 1 wherein the non-horizontal shell stiffening portion extends above the shelf.
13. The device of claim 1 wherein the non-horizontal shell stiffening portion extends below the shelf.
14. The device of claim 1 wherein the beam is situated on the side of the horizontal shelf opposite to the substrate.
15. The device of claim 1 wherein the non-horizontal shell stiffening portion is substantially perpendicular to the horizontal shelf portion.
16. A method of manufacturing a MEMS device using a shell structure made by a sidewall process comprising the steps of:
forming a mold on a substrate, wherein the mold includes a lower horizontal surface, an upper horizontal surface and a wall;
depositing a beam material on the lower horizontal surface and the wall of the mold;
removing the beam material deposited on the lower horizontal surface of the mold while leaving the majority of the beam material deposited on the wall of the mold in place to form the compliant beam;
forming the shutter coupled to the compliant beam; and
removing the mold, thereby releasing the shutter and remaining beam material.
17. The method of claim 16 wherein the non-horizontal elevating portion is manufactured from a first mold material.
18. The method of claim 16 wherein the non-horizontal shell stiffening portion is manufactured from a second mold material.
19. The method of claim 16 wherein the shell structure and the beam are manufactured from the same material.
20. The method of claim 16 wherein the shell structure and the beam are manufactured from at least two different materials.
21. The method of claim 16 wherein the shell structure and the beam are manufactured from a composite material.