Northrop Corporation

Northrop Grumman Systems Corporation

Benedict B O'Brien

Brent E Burns

King L Hu

John W Tully

William Hant

John A Geen

Adrian C Ionescu

A planar masking process for multi-depth etching of a silicon wafer wherein more than one etch depth is photolithographically patterned prior to etching the wafer and while the wafer still has a planar surface. A plurality of layers of masking material are disposed on at least one of the top and bottom surfaces of the silicon wafer and various of these layers are patterned by selectively photolithographically patterning and removing regions of the layers to form masks for areas where different silicon etch depths are desired. After forming the masks, the wafer is etched to a first level and the outermost mask is removed by etching. The silicon wafer is then again etched to another level with the remaining masks in place. The uppermost mask of the remaining masks is removed and the silicon wafer is again etched to still another level. The process is repeated until the desired levels have been etched in the silicon wafer.

Planar masking for multi-depth silicon etching

An integrated rate and acceleration sensor includes at least one accelerometer formed from a substantially planar silicon body. The at least one micro-silicon accelerometer (MSA) includes a first frame and a proof mass suspended from the first frame by first flexures. The at least one accelerometer has an associated sensitive axis and an associated rate axis that is orthogonally disposed to the sensitive axis. The integrated sensor further includes structure for dithering or vibrating the proof mass along a dither axis that is disposed perpendicularly to both the rate and the sensitive axes. The dithering structure includes at least first and second interdigitated electrodes. Finger portions of the electrodes are disposed for exerting an electrostatic force upon a portion of the planar body in response to an oscillatory drive signal. The portion of the planar body has a plurality of linear grooves formed therein, the plurality of linear grooves being disposed in a parallel orientation with the finger portions. A vibrating accelerometer gyro (VAG) structure is constructed by micromachining techniques such that the linear momenta of two vibrating MSAs balance one another. A symmetrical disposition of the vibrating proof masses tends to balance the linear momenta of the MSAs, and increases the resonance amplification factor (Q).

Micromachined accelerometer gyroscope

A miniature accelerometer is fabricated using integrated circuit manufacturing and silicon micromachining techniques to form a closed loop, force balance sensor utilizing a silicon proofmass formed from and connected to a layer of silicon by a split flexure etched therein. The sensor circuitry detects AC signals coupled from the proofmass to a pair of electrodes formed on glass surfaces anodically bonded to the silicon layer. A DC restorative force is applied to the electrodes in response to the detected AC signals to balance acceleration forces applied to the proofmass. The sensor design is highly symmetrical.

Miniature silicon accelerometer and method

A spatial light modulator including a silicon backplate having an insulating layer and a standoff grid of insulating material deposited on the backplate to define an array of cells. An electrode is deposited in each cell on said backplate. A thin membrane of doped silicon is mounted to the standoff grid and over said array of cells and electrodes. Mirrors are laid on the membrane to create an array of reflective pixels over the array of cells. When an electrode is selectively charged the portion of the membrane overlying that cell is deflected by electrostatic attraction between the membrane and the electrode. Taken overall, a pattern is assumed by the array of pixels which corresponds to the state of the electrical signals placed on the electrodes. A vent hole formed in each cell from the electrode side of the backplate to the opposite side thereof for venting gas from the cell when said diaphragm is deflected, and grooves extend across the face of the backplate and over the cell to intersect the vent hole to assist in venting gas out of the cell and through the hole. The vent hole is preferably of a size and constructed for critical damping of the movement of the mass of the deflected diaphragm at said cell to control the movement caused by the electrostatic deflection. Flexures of reduced cross-section are formed in the diaphragm along a closed line extending around the inside perimeter of the stand off grid, so that said diaphragm moves more nearly in piston mode within the flexure.

Silicon spatial light modulator

A bipolar transistor is constructed to include a substrate, a collector layer epitaxial grown on the substrate and a base layer ion implanted in the collector layer. Next a further epitaxial layer is grown on the collector layer over the ion implanted base layer. A base contact region is ion implanted in this further epitaxial layer between the surface of this further layer and the base layer. The base contact region surrounds and defines an emitter in the further layer. A base ohmic contact is formed on the surface of the further layer in a location overlaying and contacting the base contact region. An emitter ohmic contact is also formed on the surface of the further layer in contact with the emitter. Additionally a collector ohmic contact is also formed on this same surface in a position isolated from the emitter by the base contact region. The collector ohmic makes an electrical contact with the collector by utilizing the further layer as a contact pathway.

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Manhattan Beach, CA, United States of America

Benedict B O'Brien