Complex microdevices and apparatus and methods for fabricating such devices
Various embodiments of the invention are directed to various microdevices including sensors, actuators, valves, scanning mirrors, accelerometers, switches, and the like. In some embodiments the devices are formed via electrochemical fabrication (EFAB™).
1. A process for forming a multilayer microdevice, comprising:
(a) forming a layer comprising at least two materials on a substrate that may include one or more previously deposited layers, each comprising at least two materials, wherein one of the at least two materials is a structural material and another of the at least two materials is a sacrificial material;
(b) repeating the forming operation of “(a)” one or more times to form at least one subsequent layer, comprising at least two materials on at least one previously formed layer to build up a three-dimensional structure from a plurality layers;
wherein the forming of at least a plurity of layers, comprises:
(1) supplying a substrate;
(2) supplying a mask on a surface of the substrate having a desired pattern of openings through which a first material of the at least two materials can be effectively deposited or etched to yield a desired pattern of the first material;
(3) depositing the first material within the openings or etching the first material from the openings;
(4) removing the mask;
(5) depositing a second material of the at least two materials to fill the void in the deposited material; and
(6) planarizing the deposited first and second materials to provide a planarized layer; and
(c) after formation of the plurality of layers removing the sacrificial material from the deposited structural material, to reveal the three-dimensional structure,
wherein the microdevice includes a 3D tilt mirror.
2. The process of claim 1 wherein the depositing of the first material comprises electrodepositing the first material and the depositing of the second material comprises electrodepositing the second material.
3. The microdevice of claim 2 wherein the first and second deposited materials are metals.
4. The microdevice of claim 3 wherein the microdevice comprises a structure of overall dimension less than 1 centimeter with at least some design features having dimensions smaller than 500 microns.
5. The microdevice of claim 4 wherein at least some of the design features are smaller the 100 microns.
6. The microdevice of claim 5 wherein at least some of the design features are smaller than 25 microns.
7. The microdevice of claim 3 wherein the mirror comprises a rotatable structure with a reflective surface that is supported by at least one spring-like structure, wherein the spring-like structure is formed from the same material as that which forms the reflective surface.
8. The microdevice of claim 7 where the mirror can rotate around a first axis and about a second axis that is substantially perpendicular to the first axis, wherein the first axis is defined by first and second rod-like elements which produce a return force when twisted, wherein the first and second rod-like elements are supported by a loop shaped structure, which loop shaped structure is in turn supported by third and fourth rod-like elements which produce a return force when twisted, wherein the first and second rod-like elements are substantially co-linear along a first line and the third and fourth rod-like elements are substantially co-linear along a second line where-in the first and second lines are substantially perpendicular to one another.
9. The microdevice of claim 8 wherein the rotatable structure with the reflective surface has thickness dimension that is at least in part substantially thicker than the thickness dimension of the first and second rod-like elements, wherein portions of the rotatable structure may be thinner than a maximum thickness of the rotatable structure such that the moment of inertia of the rotatable structure is reduced.
10. The microdevice of claim 9 wherein the loop shaped structure has a thickness dimension that is substantially thicker than the thickness dimension of the third and forth rod-like elements.
11. The microdevice of claim 9 wherein the loop shaped structure has thickness dimension that is substantially thicker than the thickness dimension of the first and second rod-like elements.
12. The microdevice of claim 9 wherein the mirror is caused to rotate by activation of one or more of a plurality of electrodes located between the mirror and a substrate, wherein at least a plurality of the electrodes are separated from the substrate.
13. The microdevice of claim 12 wherein a parasitic capacitance of a circuit comprising the electrodes and the substrate is reduced from what the parasitic capacitance would have been if the electrodes were formed on the substrate.
14. The microdevice of claim 3 wherein the mirror is caused to rotate by activation of one or more of a plurity of electrodes located between a dielectric substrate and the mirror where each of the plurity of electrodes is formed from a plurality of layers with the configuration of structural material forming each electrode on each layer configured to provided closer proximity to the mirror when in an undeflected state in regions where tilting is less and further seperation in regions where the mirror tilts further during deflection such that the electrodes provide enhanced driving force without obstructing movement of the mirror.
15. The microdevice of claim 3 wherein a plane of a reflective surface of the mirror as formed is coincident with a boundary level of one of the layers.