Xerox Corporation

Roberto E Proano

Cathie J Burke

William G Hawkins

Igal E Klein

James F O'Neill

Robert V Lorenze, Jr

Daniel O Roll

Renato P Apollonio

Keith G Kamekona

Daniel S Brennan

The resistors of heater elements are formed by chemical vapor deposition of polycrystalline silicon at at least one of a flat temperature profile of 620.degree. C. and a ramped temperature profile of 620.degree. C. to 640.degree. C. in a first embodiment. Such method of forming the polysilicon result in a predominantly uniform grain size of approximately 1000 .ANG., where grain size can vary between 200 .ANG. to 1000 .ANG.. Alternatively, the resistors are formed by chemical vapor deposition of amorphous polysilicon at at least one of a flat temperature profile at a temperature below 580.degree. C. and a ramped temperature profile of 565.degree. C. to 575.degree. C. In the alternative embodiment, the polysilicon has a grain size of at least 1000 .ANG.. During the ion implantation of either p-type or n-type dopants into the polysilicon, a flood gun located in an ion implanter emits low energy electrons to neutralize the build-up of positive charges on the polysilicon surface. Because the low energy electrons prevent the build-up of electric charges on the surface of the polysilicon, the usual build-up of an electrical field on the surface of the polysilicon is eliminated, and the polysilicon can be uniformly doped by ion implantation of dopants. By using the flood gun during the fabrication of the heater elements of the printhead, the resistors of the heater elements and printheads have substantially uniform sheet resistances relative to each other. The sheet resistances of the resistors in the printhead vary less than 3% and preferably less than 1%. Such low variations in sheet resistance prevent undervoltage and overvoltage from being applied to the resistors and extend the lifetime of the heater element and thus, the printhead.

Increased threshold uniformity of thermal ink transducers

In a thermal ink jet printhead with a protective layer, the protective layer is made of a thin film material having a melting point not less than about 1000.degree. C. A deposition process for preparing the thin film material produces a thin film material having, at an operating temperature for the thermal ink jet printer, a thermal conductivity coefficient not less than about 10 W/m.K, a compressive yield strength not less than about 1400 MPa, and a compressive residual stress of not greater than about 1200 MPa. The protective layer is smooth, substantially free of pores and impervious to stress corrosion or hydrogen stress cracking at a hydrogen uptake rate of less than about 5 ppm. The protective layer may also contain an adhesion enhancing region between the protective layer and an underlying layer or an anodic region contiguous with an underlying thin film material of the protective layer. The adhesion enhancing region is a reaction product between an ambient gas and the thin film material of the protective layer and extends only to the grain boundaries of the protective layer. The contiguous anodic region is substantially free of pores, has a homogeneous composition, protects an underlying thin film material against corrosive species and hydrogen and is formed by anodization of the underlying thin film in an aqueous electrolytic process.

Thermal ink jet printhead protective layers

A thermal ink jet printhead has an outer, metallic hydrophobic coating on its front face to repel ink. Eliminating the accumulation of ink at the nozzles of the printhead allows an ink droplet to be accurately ejected and ensures the directionality of the ejected ink droplet onto the printing medium. The outer coating is formed of a metal selected from the group of noble metals, including gold, platinum, palladium, silver, rhodium and ruthenium. An adhesion layer is preferably deposited between the front face of the printhead and the outer ink-repellent coating. The metallic coating is preferably applied by electroplating, wet electroless plating, evaporation, sputtering, ion plating, CVD or plasma CVD.

Directionality of thermal ink jet transducers by front face metalization

In semiconductor technologies such as thermal ink jet printhead fabrication, there exists a need for the precise placement of channels in a substrate. Due to errors in plane alignment in semiconductor substrates, channel structures tend to widen dimensions, thus lowering precision. A one-step anisotropic etching process is disclosed for accurately making channel structures, as well as reservoir structures. Channel structures are formed by segmenting the channel, such that during the anisotropic etching, thin walls between the segments break down before the completion of the etch. Widening of channels is greatly reduced, thus increasing precision. During such a one-step process, larger structures, such as a reservoir, can be formed during the same step.

Growing community of inventors

Rochester, NY, United States of America

Roberto E Proano