Micro-mirror with electrode spacer
View Patent ↗A micro-mirror includes stiffer end sections for limiting curvature, and thin middle sections forming ground electrodes and a hinge. Spacers arc provided beneath the thin middle sections of the micro-mirror for supporting hot electrodes, which attract the ground electrodes for rotating the micro-mirror about a tilt axis. The spacers enable the gap between the hot electrode and the micro-mirror to be designed separately from the thickness of the micro-mirror, and the gap between the ends of the micro-mirror and the substrate.
1. A micro-mirror device comprising:
a substrate defining a lower level;
a first spacer extending upwardly from the substrate forming an upper level;
an anchor post extending upwardly from the substrate or the spacer;
a tilting platform, having a longitudinal central axis, and pivotally connected to the anchor post above the substrate via a hinge defining a lateral tilting axis, perpendicular to and shorter than the longitudinal central axis, the tilting platform including a first thin section adjacent to the tilting axis above the upper level of the substrate, and a stiffer section at each outer free end of the longitudinal central axis including stiffening ribs in a lower surface thereof above the lower level of the substrate beyond the first spacer for decreasing curvature of the outer free ends of the tilting platform defining a swing space therebetween; and
a first hot electrode on the first spacer below the first thin section only, the first hot electrode and the thin section of the tilting platform defining an electrode gap, separated from the swing space, for pivoting the tilting platform about the tilting axis,
whereby tolerance variations in hinge thickness are at least partially compensated for by a corresponding variation in electrode gap; and
whereby the swing space is wider than and independent of the electrode gap.
2. The micro-mirror device according to claim 1 , wherein the substrate and the first spacer are comprised in a single wafer.
3. The micro-mirror device according to claim 1 , wherein the first spacer is comprised of a different material bonded on top of the substrate.
4. The micro-mirror device according to claim 3 , wherein the first spacer comprises a conductive material, wherein the first spacer includes the first hot electrode.
5. The micro-mirror device according to claim 1 , wherein the first spacer comprises an insulator material; and further comprising a second hot electrode on the first spacer, below a second thin section in the tilting platform, on an opposite side of the titling axis than the first hot electrode.
6. The micro-mirror device according to claim 1 , further comprising a second spacer extending upwardly from the substrate to the upper level; and a second hot electrode of the second spacer below a second thin section of the tilting platform, on an opposite side of the tilting axis than the first hot electrode.
7. The micro-mirror device according to claim 1 , wherein the stiffening ribs include a bulkhead extending laterally from one side of the tilting platform to another parallel to the tilting axis.
8. The micro-mirror device according to claim 7 , wherein the stiffening ribs also include a plurality of elongated ribs extending from the bulkhead to the outer free end of the tilting platform perpendicular to the tilting axis.
9. The micro-mirror device according to claim 8 , wherein the tilting platform includes a mounting cap for bonding on top of the anchor post; and wherein the mounting cap, the bulkhead and the elongated ribs are formed in a single structure and have the same thickness.
10. The micro-mirror device according to claim 1 , wherein the stiffening ribs include a plurality of elongated ribs extending to the outer free end of the titling platform perpendicular to the tilting axis.
11. The micro-mirror device according to claim 1 , wherein the first spacer extends upwardly from the substrate to provide improved aerodynamic cross-talk by increased effective thickness of air gap underneath the tilting platform.
12. The micro-mirror device according to claim 1 , further comprising a reflective surface on the tilting platform only above one or both of the stiffer sections.