Systems and methods for current density optimization in CMOS-integrated MEMS capacitive devices
The present subject matter relates to the use of current splitting and routing techniques to distribute current uniformly among the various layers of a device to achieve a high Q-factor. Such current splitting can allow the use of relatively narrow interconnects and feeds while maintaining a high Q. Specifically, for example a micro-electromechanical systems (MEMS) device can comprise a metal layer comprising a first portion and a second portion that is electrically separated from the first portion. A first terminus can be independently connected to each of the first portion and the second portion of the metal layer, wherein the first portion defines a first path between the metal layer and the first terminus, and the second portion defines a second path between the metal layer and the first terminus.
1. A micro-electromechanical systems (MEMS) device comprising:
a fixed metal layer positioned on a substrate;
a movable beam spaced apart from the fixed metal layer and movable with respect to the substrate, the movable beam comprising a first movable metal layer capacitively coupled to the fixed metal layer, the first movable metal layer comprising at least a first movable portion and a second movable portion that is electrically separated from the first movable portion; and
a terminus independently connected to each of the first movable portion and the second movable portion of the first movable metal layer;
wherein the first movable portion defines a first path between the first movable metal layer and the terminus, and the second movable portion defines a second path between the first movable metal layer and the terminus.
2. The device of claim 1 , wherein one or both of the fixed metal layer and the first movable metal layer comprises slots or other patterns.
3. The device of claim 1 , wherein the movable beam comprises:
a structural dielectric layer positioned on the first movable metal layer; and
a second movable metal layer positioned on the structural dielectric layer, the second movable metal layer being electrically connected to the first movable portion through a via in the structural dielectric layer, and the second movable metal layer being electrically connected to the terminus.
4. The device of claim 1 , wherein the first movable portion and the second movable portion are substantially equally sized.
5. The device of claim 1 , wherein the first movable portion and the second movable portion are different sizes.
6. The device of claim 1 , wherein a first capacitive portion of the first movable metal layer is positioned above a first segment of the fixed metal layer, and a second capacitive portion of the second movable metal layer is positioned above a second segment of the fixed metal layer; and
wherein the first movable portion and the second movable portion are configured such that an overlap of the first capacitive portion with the first segment and of the second capacitive portion with the second segment creates a first current fraction to be routed through the first path and a second current fraction to be routed through the second path, respectively.
7. The device of claim 6 , wherein the first path between the first movable metal layer and the terminus has a first resistance, and the second path between the first movable metal layer and the terminus has a second resistance; and
wherein the first movable portion and the second movable portion are configured such that the first resistance and the second resistance are inversely proportional to the first current fraction to be routed through the first path and the second current fraction to be routed through the second path, respectively.
8. A micro-electromechanical systems (MEMS) device comprising:
at least one fixed metal layer positioned on a substrate;
a first terminus independently connected to each of the at least one fixed metal layer;
a movable beam spaced apart from the fixed metal layer, the movable beam comprising at least one movable metal layer that is capacitively coupled to the at least one fixed metal layer; and
a second terminus independently connected to each of the at least one movable metal layer;
wherein one or both of the at least one fixed metal layer or the at least one movable metal layer defines at least a first path between the first terminus and the second terminus and a second path between the first terminus and the second terminus.