At&t Bell Laboratories

Bell Telephone Laboratories

American Telephone & Telegraph Co., At&t Bell Laboratories

At+t Corp.

Martin L Green

Ya-Hong Xie

Richard C Sherwood

Roland A Levy

Daniel Brasen

Eugene A Fitzgerald, Jr

Michal Edith Gross

Donald Paul Monroe

Gilbert Y Chin

Ralph G Nuzzo

Patrick K Gallagher

Jack H Wernick

Paul J Silverman

Frank E Bader

A heterostructure includes a stained epitaxial layer of either silicon or germanium that is located overlying a silicon substrate, with a spatially graded Ge.sub.x Si.sub.1-x epitaxial layer overlain by a ungraded Ge.sub.x.sbsb.0 Si.sub.1-x.sbsb.0 intervening between the silicon substrate and the strained layer. Such a heterostructure can serve as a foundation for such devices as surface emitting LEDs, either n-channel or p-channel silicon-based MODFETs, and either n-channel or p-channel silicon-based MOSFETs.

Semiconductor heterostructure devices with strained semiconductor layers

The present invention is predicated upon the discovery by applicants that by growing germanium-silicon alloy at high temperatures in excess of about 850.degree. C. and increasing the germanium content at a gradient of less than about 25% per micrometer, one can grow on silicon large area heterostructures of graded Ge.sub.x Si.sub.1-x alloy having a low level of threading dislocation defects. With low concentrations of germanium 0.10.ltoreq..times..ltoreq.0.50), the heterolayer can be used as a substrate for growing strained layer silicon devices such as MODFETS. With high concentrations of Ge (0.65.ltoreq..times..ltoreq.1.00) the heterolayer can be used on silicon substrates as a buffer layer for indium gallium phosphide devices such as light emitting diodes and lasers. At concentrations of pure germanium (X=1.00), the heterolayer can be used for GaAs or GaAs/AlGaAs devices.

Method for making low defect density semiconductor heterostructure and

A method for fabricating a device, e.g., a semiconductor device, is disclosed which includes the step of reacting at least two reactive entities to form a metal-containing material on a region or regions of a processed or unprocessed substrate. Inherent in the method is the recognition that one of the reactive entities will often react with substrate material to produce previously unrecognized, and highly undesirable, results, e.g., the almost complete erosion of previously fabricated device components. Thus, and in accordance with the inventive method, any one of a variety of techniques is employed to reduce the reaction rate between the substrate material and the entity reacting with this material, while avoiding a substantial reduction in the reaction rate between the two entities.

Method for fabricating devices and devices formed thereby

Metallization of integrated devices using ruthenium as a metallization material results in well-adhering contacts to source and drain regions as well as to gate oxide. Ruthenium is similarly suited as a diffusion barrier metallization between, e.g., silicon and aluminum and as an interconnection metallization material. And, as a diffusion barrier material, ruthenium dioxide may be used.

Metallization for integrated devices

Chemical vapor deposition of an aluminum layer on a substrate is facilitated by surface activation prior to deposition. Surface activation is at relatively low temperature and results in a hydrated surface; low temperature surface activation is advantageous in the interest of keeping deposition apparatus free of additional chemicals, and substrates activated in this manner may be stored for considerable lengths of time prior to aluminum deposition. Among suitable activating agents are organochromium, organosilane, and organoaluminum compounds.

Chemical vapor deposition of aluminum on an activated surface

A composite contact material for light-duty electrical contacts is formed by combining, typically by powder-metallurgical techniques, a matrix metal and particles of a conductive material that is typically harder and more corrosion resistant than the matrix metal, and by removing, in a differential material removal step, some of the matrix metal from a surface of the composite, thereby producing a 'sandpaper' surface with a substantial number of the particles projecting by a substantial amount above the matrix metal surface. Typical matrix metals are copper, copper alloys, or nickel, and typical particle materials are metals such as Ru, Re, Os, and intermetallics, oxides, borides, nitrides, carbides, silicides, and phosphides of such metals as Al, Ti, Ni, Nb, Mo, Ru, Ta, W, Re, or Os. Particle size is typically between about 0.1 .mu.m and 100 .mu.m, preferably less than 10 .mu.m, and the particle volume fraction is typically between about 1% and 50%, preferably between 5% and 30%. Any appropriate differential material removal method, including chemical, plasma, sputter, thermal, and electrolytic etching, can be used.

Base metal composite electrical contact material

Fe--Cr--Co alloys have found application in the manufacture of permanent magnets on account of magnetic properties such as, high coercive force, remanent magnetization, and energy product. A method is disclosed for producing magnetic articles comprising Fe, Cr, and Co from powders comprising elemental or pre-alloyed particles. A powder is mixed with an essentially noncarbonizing organic binder, compressed, heated to remove binder, sintered, and aged. Heating results in essentially complete removal of binder prior to sintering. Magnetic bodies produced according to the disclosed method typically comprise less than 1 weight percent of undesirable nonmagnetic phases and have a maximum energy product of at least 1 million gauss oersted.

Fe--Cr--Co Magnets by powder metallurgy processing

In view of rising cobalt costs, low-cobalt alloys such as, e.g., Fe-Cr-Co alloys are finding increasing use in the manufacture of permanent magnets. Desired magnetic energy product of such magnets is typically at least 1 million gauss-oersted. In the interest of maximizing magnetic energy product per unit weight cobalt, low-cobalt Fe-Cr-Co alloys are processed by solidifying a bulk object from a melt, annealing, quenching, and aging by cooling at rates in a range of 0.1 to 2 degrees C. per hour in a magnetic field. Cold working prior to aging may be used to further enhance magnetic energy product. Resulting magnets have optimized maximum magnetic energy product (BH).sub.max per unit weight cobalt comprised in an alloy.

Growing community of inventors

New Providence, NJ, United States of America

Martin L Green