Analog Devices,inc.

Jeffrey A Farash

Howard R Samuels

Richard S Payne

Robert W Tsang

A micromachined device is provided that establishes select dimensional relationships between micromachined structures to achieve correlation in dimensional variation among these structures.

Micromachined device with enhanced dimensional control

A micromachined device is provided that establishes select dimensional relationships between micromachined structures to achieve correlation in dimensional variation among these structures. Such dimensional relationships are achieved through consistent spacing between desired operating structures and by adding new structures (i.e., dimensional control structures) which provide additional consistent spacing at desired locations within the micromachined device.

A method for providing a conductive ground plane beneath a suspended microstructure. A conductive region is diffused into a substrate. Two dielectric layers are added: first a thermal silicon dioxide layer and then a silicon nitride layer. A first mask is used to etch a ring partially through the silicon nitride layer. Then, a second mask is used to etch a hole through both dielectric layers in a region having a perimeter that extends between the inner and outer edges of the ring. This leaves the conductive region exposed in an area surrounded by a ring that has the silicon dioxide layer and a narrow silicon nitride layer. The ring is surrounded by an area in which the silicon dioxide and silicon nitride layers have not been reduced. A spacer silicon dioxide layer is deposited over the dielectric and then a polysilicon layer is deposited and formed into the shape of a the suspended microstructure. When the spacer layer is etched away, the silicon dioxide under the narrow silicon nitride layer is removed, along with the narrow silicon nitride layer, leaving an exposed ground plane surrounded by a dielectric with minimal undercutting.

Growing community of inventors

Holbrook, MA, United States of America

Jeffrey A Farash