Mobil Solar Energy Corporation

Massachusetts Institute of Technology

United States of America As Represented by the Secretary of the Air Force

James A Gregory

Jack I Hanoka

Bernard B Kosicki

Eugene D Savoye

Andrew H Loomis

Zinovy Y Vayman

Christopher W Leitz

Barry E Burke

Robert K Reich

James E Carrick

Donna-Ruth Webb Yost

Allen M Waxman

Vladimir Bolkhovsky

Douglas A Yates

Kevin Ryu

Alan N Gove

David A Fay

Renee D Lambert

William H McGonagle

Robert W Mountain

A new process that enables void-free direct-bonded MBE-passivated large-format image sensors is disclosed. This process can be used to produce thin large-area image sensors for UV and soft x-ray imaging. Such devices may be valuable in future astronomy missions or in the radiology field. Importantly, by controlling the hydrogen concentration in the silicon oxide layers of the image sensor and the support wafer, voids in the bonding interface can be significantly reduced or eliminated. This process can be applied to any wafer that includes active circuitry and requires a second wafer, such as a support wafer.

Semiconductor surface passivation

The wafer thickness of a CCD front illuminated silicon wafer is reduced to about ten to twenty microns, the Al substrate is removed and a 5-35 nanometer silicon oxide layer is produced on the thinned back of the silicon wafer followed by implanting boron ions within the back surface to a depth up to about ten nanometers. Furnace annealing the wafer is now carried out, and the Al substrate is redeposited to enable the formation of gate contacts.

Fabrication of UV-sensitive back illuminated CCD image sensors

An imaging system is provided for imaging a scene to produce a sequence of image frames of the scene at a frame rate, R, of at least about 25 image frames per second. The system includes an optical input port, a charge-coupled imaging device, an analog signal processor, and an analog-to-digital processor (A/D). The A/D digitizes the amplified pixel signal to produce a digital image signal formatted as a sequence of image frames each of a plurality of digital pixel values and having a dynamic range of digital pixel values represented by a number of digital bits, B, where B is greater than 8. A digital image processor is provided for processing digital pixel values in the sequence of image frames to produce an output image frame sequence at the frame rate, R, representative of the imaged scene, with a latency of no more than about 1/R and a dynamic range of image frame pixel values represented by a number of digital bits, D, where D is less than B. The output image frame sequence is characterized by noise-limited resolution of at least a minimum number, N.sub.M, of line pairs per millimeter, referred to the charge-coupled imaging device pixel array, in an imaged scene as a function of illuminance of the input light impinging the charge-coupled imaging device pixels.

Low-light-level imaging and image processing

A method of bulk passivating a crystalline or polycrystalline substrate made from silicon, germanium, gallium arsenide or other III-V compounds, and II-VI compounds by exposing the substrate to a fluorine ion beam created by a Kaufman ion source. The Kaufman ion source is controlled so that the intensity of and duration of exposure to the fluorine ion beam is sufficient to bulk passivate the substrate. Preferably, the substrate is preheated to a selected temperature prior to the ion beam exposure.

Method of passivating crystalline substrates

An improved optical match to a subsequently-formed antireflection overcoating is achieved by providing a silicon solar cell substrate with an altered surface layer that is formed by an ion-beam process, and has a refractive index between about 3.4 and about 3.6 at 633 nm and between about 3.6 and about 3.8 at 442 nm. The surface layer is formed by adding between about 2% and about 10% methane, by volume, to the hydrogen flow in a Kaufman type broad beam ion source.

Antireflection coatings for silicon solar cells

An improvement to the process of passivation of polycrystalline silicon using a broad beam ion source wherein a controlled flow, greater in volume than the background level, of a low molecular weight hydrocarbon vapor is introduced into the vacuum system of the Kaufman-type ion source used for passivation. The amount of hydrocarbon introduced is between about one third of one percent and about ten percent, relative to the hydrogen flow, depending on the hydrocarbon. The process is especially advantageous in producing a passivated layer that functions adequately as a mask for metal plating.

Method of fabricating solar cells

A solar cell fabrication procedure is described in which a hydrogen ion passivation step is used to form, inter alia, an altered silicon substrate surface layer to which immersion plated nickel will not readily adhere. The altered surface layer is formed by shadow casting an ion beam in a pattern corresponding to the desired front surface interelectrode configuration.

Growing community of inventors

Sudbury, MA, United States of America

James A Gregory