Other

The State University of New York

Airco, Inc.

Ohmcraft, Inc.

Franklyn M Collins

Quanxi Jia

Wayne K Anderson

Hoong J Lee

Timothy S Barge

Kaili Jiao

The present invention is directed to a thick film patterned resistor on a substrate and to a method of forming it. The method involves providing a substrate with opposed surfaces, where one surface is coated with a layer of a resistor composition. A photoresist is applied over the layer of the resistor composition, and a desired pattern in the photoresist is formed, where the pattern leaves certain regions of the resistor composition layer uncovered by the photoresist. The resistor composition layer which is uncovered by the photoresist is etched under conditions effective to leave a mass of loosely bound resistor particles at regions of the resistor composition which are not covered by photoresist. The mass of resistor particles is then removed from the substrate to produce a thick film patterned resistor on the substrate.

Fine line thick film resistors by photolithography

In a first embodiment of the invention a layer of ruthenium oxide is reactively deposited onto a substrate, then annealed for TCR adjustment and for stabilization. In a second, bi-layer embodiment of the invention, a layer of tantalum nitride is first reactively deposited onto a substrate, then annealed for stabilization. After a ruthenium oxide layer is reactively deposited onto the annealed tantalum nitride layer, the structure is annealed until a near-zero effective TCR for the bi-layer resistor is achieved. The ruthenium oxide capping layer serves as a barrier against chemical attack.

Thin film resistors comprising ruthenium oxide

Electrical resistors and resistor networks are provided on an insulative substrate with designated conductive terminations by direct and continuous writing of resistive lines in fine-line patterns between and over each two of neighboring terminations from heterogeneous resistive thick film compositions. The resistive lines of line width w and total length l between conductive terminations can be directly written by suitable writing apparatus to have a high aspect ratio n=l/w, thereby providing resistors and resistor networks of high resistance values on an overall substrate area significantly smaller than required for conventional thick film resistors of comparable resistance value and comparable operational characteristics.

Fine-line thick film resistors and resistor networks and method of

A composite thin film resistor is disclosed, including an electrically inert substrate upon which is deposited a nickel-chromium alloy thin film, and an overlying second thin film -- which is initially deposited as metallic tantalum. In the final product the tantalum is passivated, as by thermal oxidation, so that the said film is substantially tantalum oxide throughout, except where such film underlies a pair of conductive terminal pads. The terminal pads are spaced on the substrate, so that the resistive path therebetween is defined through the nickel-chromium thin film -- via the thin metallic tantalum film interfacing between the nickel-chromium film and conductive pads. The overlying tantalum oxide provides a very high degree of environmental protection with respect to the Ni--Cr film, whereby the product not only displays the desirably low TCR characteristics of Ni--Cr, but is also highly resistant to moisture and other environmental factors. The product also exhibits outstanding resistance to the adverse effects of electrolysis supported by the presence of moisture. The various films, including a gold film from which the terminal pads are derived, may be deposited upon the inert substrate by sequential sputtering during a single evacuation of a vacuum chamber. Desired resistive patterns may then be formed by photo-etching, subsequent to which oxidation of accessible portions of the tantalum film can be effected by heating in an appropriate atmosphere.

Growing community of inventors

Lewiston, NY, United States of America

Franklyn M Collins