USA As Represented by Secretary of the Navy

Other

The Charles Stark Draper Laboratory, Inc.

Eugene A Imhoff

Francis J Kub

Karl D Hobart

Rachael L Myers-Ward

Marc Steven Weinberg

Jonathan Jay Bernstein

Marko J Tadjer

Eugene H Cook

Robert E Stahlbush

Nadeemullah A Mahadik

Boris N Feigelson

Jordan D Greenlee

Mario Ancona

A method of fabricating suspended beam silicon carbide microelectromechanical (MEMS) structure with low capacitance and good thermal expansion match. A suspended material structure is attached to an anchor material structure that is direct wafer bonded to a substrate. The anchor material structure and the suspended material structure are formed from either a hexagonal single-crystal SiC material, and the anchor material structure is bonded to the substrate while the suspended material structure does not have to be attached to the substrate. The substrate may be a semi-insulating or insulating SiC substrate. The substrate may have an etched recess region on the substrate first surface to facilitate the formation of the movable suspended material structures. The substrate may have patterned electrical electrodes on the substrate first surface, within recesses etched into the substrate.

Silicon carbide structure, device, and method

Electromechanical device structures are provided, as well as methods for forming them. The device structures incorporate at least a first and second substrate separated by an interface material layer, where the first substrate comprises an anchor material structure and at least one suspended material structure, optionally a spring material structure, and optionally an electrostatic sense electrode. The device structures may be formed by methods that include providing an interface material layer on one or both of the first and second substrates, bonding the interface materials to the opposing first or second substrate or to the other interface material layer, followed by forming the suspended material structure by etching.

Silicon carbide microelectromechanical structure, device, and method

A method for removing existing basal plane dislocations (BPDs) from silicon carbide epilayers by using a pulsed rapid thermal annealing process where the BPDs in the epilayers were eliminated while preserving the epitaxial surface. This high temperature, high pressure method uses silicon carbide epitaxial layers with a carbon cap to protect the surface. These capped epilayers are subjected to a plurality of rapid heating and cooling cycles.

Basal plane dislocation elimination in 4H&#x2014;SiC by pulsed rapid thermal annealing

Material structures and methods for etching hexagonal, single-crystal silicon carbide (SiC) materials are provided, which include selection of on-axis or near on-axis hexagonal single-crystal SiC material as the material to be etched. The methods include etching of SiC bulk substrate material, etching of SiC material layers bonded to a silicon oxide layer, etching of suspended SiC material layers, and etching of a SiC material layer anodically bonded to a glass layer. Plasma-etched hexagonal single-crystal SiC materials of the invention may be used to form structures that include, but are not limited to, microelectromechanical beams, microelectromechanical membranes, microelectromechanical cantilevers, microelectromechanical bridges, and microelectromechanical field effect transistor devices. The material structures and methods of the invention beneficially provide improved etch symmetry, improved etch straightness, improved sidewall straightness, improved sidewall smoothness, and reduced sidewall wander compared to etched four degree off-axis SiC materials.

Material structure and method for deep silicon carbide etching

According to one aspect, embodiments herein provide a gyroscope comprising an axially symmetric structure, and a plurality of transducers, each configured to perform at least one of driving and sensing motion of the axially symmetric structure, wherein the plurality of transducers is configured to drive the axially symmetric structure in at least a first vibratory mode and a second vibratory mode, and wherein the gyroscope is implemented on a hexagonal crystal-based substrate.

Whole angle MEMS gyroscope on hexagonal crystal substrate

A method and device including adding a protective layer on the surface of a substrate, annealing the substrate at a temperature approximately greater or equal to 1850&#xb0; C., removing the protective layer from the surface of the substrate after the annealing, and growing a first epilayer on the substrate after the removing of the protective layer, wherein the first epilayer is grown without attempting to prevent the basal plane dislocations to propagate in the first epilayer when growing the first epilayer, and wherein the first epilayer is free of the basal plane dislocations.

Removal of basal plane dislocations from silicon carbide substrate surface by high temperature annealing and preserving surface morphology

A method to remove basal plane dislocations in post growth silicon carbide epitaxial layers by capping post growth silicon carbide epilayers with a graphite cap and annealing the capped silicon carbon epilayers at a temperature of 1750&#xb0; C. or greater with a nitrogen overpressure of 60-110 psi, wherein basal plane dislocations in the epilayers are removed while surface morphology is preserved. Also disclosed is the related silicon carbide substrate material made by this method.

Elimination of basal plane dislocations in post growth silicon carbide epitaxial layers by high temperature annealing while preserving surface morphology

Silicon carbide PiN diodes are presented with reduced temperature coefficient crossover points by limited p type contact area to limit hole injection in the n type drift layer in order to provide a lower current at which the diode shifts from negative temperature coefficient to a positive temperature coefficient of forward voltage for mitigating thermal runaway.

Silicon carbide rectifier

Methods for producing a junction termination extension surrounding the edge of a cathode or anode junction in a semiconductor substrate, where the junction termination extension has a controlled arbitrary lateral doping profile and a controlled arbitrary lateral width, are provided. A photosensitive material is illuminated through a photomask having a pattern of opaque and clear spaces therein, the photomask being separated from the photosensitive material so that the light diffuses before striking the photosensitive material. After processing, the photosensitive material so exposed produces a laterally tapered implant mask. Dopants are introduced into the semiconductor material and follow a shape of the laterally tapered implant mask to create a controlled arbitrary lateral doping profile and a controlled lateral width in the junction termination extension in the semiconductor.

Method for fabricating junction termination extension with formation of photosensitive dopant mask to control doping profile and lateral width for high-voltage electronic devices

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Washington, DC, United States of America

Eugene A Imhoff