Abstract:
An array of MEMS devices is formed on a planar substrate having in each of a plurality of annular regions or sectors a plurality of MEMS mirrors of substantially identical structure, wherein the MEMS mirrors in each region have an identical pre-tilt. The pre-tilt is achieved by embedding each dual-axis tiltable mirror within a pre-tilted microplatform or gimbal. In a specific embodiment, one microplatform of a preselected pre-tilt is provided for each micromirror and an underlying electrode is provided having a shape conforming with the pre-tilt. In a specific embodiment, the annular regions are contiguous elliptical or ovoidal regions. By pre-tilt, it is meant that the rest state or nonactuated state of the micro-mirror is such that a reflected beam from a fixed source is directed to the center of a target array.
Abstract:
One or more cavities are formed in the bonding surfaces of one, all, or some of the elements to be bonded. These cavities serve as receptacles for the bonding material and are where the bonds are localized. The cavities are of sufficient size and shape so that their volume is greater than the volume of bonding material forming the bond. This ensures that when the elements are brought into contact with one another to mate, the bonding material, which can flow prior to solidifying into a bond, will flow into the cavities and will not impede the separation of the parts. This allows the parts to be mated with nominally zero separation. Once solidified, the bonding material forms a localized bond inside each cavity. Different cavity shapes, such as, rectangular, circular, or any other shape that can be injected or filled with adhesive material may be used.
Abstract:
A MEMS-based mirror is provided with trenches between adjacent electrodes in order to be able to withstand relatively high applied voltages, and thus has a substantially reduced exposure to uncontrolled surface potentials. The MEMS-based mirror, thus avoids voltage drifts and has an improved mirror position stability. The trench dimensions are selected such that the voltage applied between each adjacent pair of electrodes stays within predefined limits. An insulating layer, such as silicon dioxide, electrically isolates each pair of adjacent electrodes. Each insulting layer extends partially above an associated trench and is characterized by the same height and width dimensions.
Abstract:
In an electrostatically controlled deflection apparatus, such as a MEMS array having cavities formed around electrodes and which is mounted directly on a dielectric or controllably resistive substrate in which are embedded electrostatic actuation electrodes disposed in alignment with the individual MEMS elements, a mechanism is provided to mitigate the effects of uncontrolled dielectric surface potentials between the MEMS elements and the electrostatic actuation electrodes, the mechanism being raised electrodes relative to the dielectric or controllably resistive surface of the substrate. The aspect ratio of the gaps between elements (element height to element separation ratio) is at least 0.1 and preferably at least 0.5 and preferably between 0.75 and 2.0 with a typical choice of about 1.0, assuming a surface fill factor of 50% or greater. Higher aspect ratios at these fill factors are believed not to provide more than marginal improvement.
Abstract:
A mirror (12) is mounted on a first pair of hinges (14, 16) to a gimble (18). The gimble (18) is connected by a second pair of hinges (20, 21) having one degree of freedom to a frame (24) wherein an oxide layer (25) is provided for bonding and etch stop during manufacturing.
Abstract:
Apparatus and methods are provided for driving a two-axis “X-Y” MEMS mirror using three (1, 2, 3) non-contact actuation elements or electrodes. A differential bi-directional mirror control uses unipolar drive voltages biased at a suitable value. Transformation functions map two-axis tip tilt commands to three actuation drive signals for selected electrode orientations and sizes.
Abstract:
In an electrostatically controlled apparatus (fig.1), such as a MEMS array (10) having cavities (44, 46, 48) formed around electrodes and which is mounted directly on a dielectric substrate (24) in which are embedded electrostatic actuation electrodes (26, 27) disposed in alignment with the individual MEMS elements, a mechanism is provided to controllably neutralize excess charge and establish a controlled potential between the MEMS elements and the electrostatic actuation electrodes.
Abstract:
Method for fabricating ultrathin gaps producing ultrashort standoffs (26) in array structures includes sandwiching a patterned device layer (12) between a silicon standoff layer (26) and a silicon support layer (38), providing that the back surfaces (46, 48) of the respective silicon support layer and the standoff layer are polished to a desired thickness corresponding to the desired standoff height on one side and to at least a minimum height for mechanical strength on the opposing side, as well as to a desired smoothness. Standoffs and mechanical supports are then fabricated by etching to produce voids with the dielectric oxides (20, 40) on both sides of the device layer serving as suitable etch stops. Thereafter, the exposed portions of the oxide layers are removed to release the pattern, and a package layer is mated with the standoff voids to produce a finished device. The standoff layer can be fabricated to counteract curvature.
Abstract:
Apparatus and methods are provided for driving a two-axis MEMS mirror using three non-contact actuation elements or electrodes. A differential bi-directional mirror control uses unipolar drive voltages biased at a suitable value. Transformation functions map two-axis tip-tilt commands to three actuation drive signals for selected electrode orientations and sizes.