Abstract: An ink jet printhead has improved resistance to the corrosive effects of ink by coating the surface of a photo-imageable polymer with an ink resistant film. In one described embodiment, a thermal ink jet element is formed by bonding together a channel plate and a heater plate. Resistors and electrical connections are formed in the heater plate. A polyimide layer is formed so as to overlie the heater plate to protect the electrical elements while providing pit structure for the heater and for ink flow bypass. A tantalum film is formed on the surface of the polyimide layer to protect the layer from the effects of corrosive ink. In another embodiment, the ink resistant film is amorphous carbon or silicon nitride.

Abstract: An ink jet printhead has improved resistance to the corrosive effects of ink by coating ink sensitive areas with a photo-imageable benzocyclobutene (BCB) polymer. The BCB can be patterned so as to provide a protective coating over selected areas while leaving other areas uncoated. In one described embodiment, a thermal ink jet printer is formed by bonding together a channel plate and a heater plate. Resistors and electrical connections are formed in the surface of the heater plate. A BCB layer is formed so as to overlie the heater plate to protect the electrical elements while providing pit structure for the heater and for ink flow bypass.

Abstract: An improved microelectromechanical device, such as a thermal ink jet die or printhead, is formed by the alignment of two planar substrates bonded together by an intermediate thick film layer of patterned polymeric material, such as polyimide. The improved device has a fully cured, patterned thick film layer which is planarized by chemical-mechanical polishing-to improve the bonding strength between the substrates. The planarization removes topographical formations generated during the deposition of the thick film layer and/or during the patterning of the recesses therein.

Abstract: 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.

Abstract: An electrostatic discharge protection device for a connector associated with an integrated circuit chip, particularly one associated with a thermal ink-jet printhead. AMOS field effect device extends along at least one edge of the connector on the chip. A bipolar transistor, parasitic to the field effect device, conducts current from the connector to ground in response to a voltage between the connector and ground in excess of a predetermined threshold. A zone of a predetermined electrical resistance is operatively disposed between the bipolar transistor and ground. The zone may substantially encircle the bonding pad of the connector to evenly distribute local incidences of high voltage. The invention enables integrated circuits to pass ESD requirements of office products, which is 15 kV by Human Body Model testing.

Abstract: 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.

Abstract: An electrostatic discharge protection device for a connector associated with an integrated circuit chip, particularly one associated with a thermal ink-jet printhead. A MOS field effect device extends along at least one edge of the connector on the chip. A bipolar transistor, parasitic to the field effect device, conducts current from the connector to ground in response to a voltage between the connector and ground in excess of a predetermined threshold. A zone of a predetermined electrical resistance is operatively disposed between the bipolar transistor and ground. The zone may substantially encircle the bonding pad of the connector to evenly distribute local incidences of high voltage. The invention enables integrated circuits to pass ESD requirements of office products, which is 15 kV by Human Body Model testing.

Abstract: 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.

Abstract: A transducer for a thermal ink jet printhead has a primary heating region having a tantalum layer, a silicon nitride layer and a polysilicon resistor layer. An n.sup.- drift layer resistor serves as a secondary heating region and a field layer of silicon dioxide acts as an insulator. The field layer is sandwiched between the primary heating region and the secondary heating region. The secondary heating region by heating the field layer causes the heat generated in the primary heating region to be directed toward ink which lies above the primary heating region. An electrical contact connects the polysilicon resistor layer of the primary heating region to a driving transistor located on the same silicon wafer as the transducer. The driving transistor has a field oxide layer sandwiched between an n.sup.- drift layer and a field plate layer, the field plate layer causing secondary pinch off of the n.sup.- drift layer thus enabling higher operating voltages.

Abstract: A thermal jet ink printing is provided with an improved printhead. The printhead is formed by monolithic integration of MOS logic elements and drivers onto the same silicon substrate containing the resistive elements using a more efficient manufacturing process. In a preferred embodiment, the logic switches, logic drivers and resistive elements are formed from a single layer of polysilicon with the resistive element formed on a thermally grown field oxide layer. The integrated circuit chips are formed by a MOS fabrication technology which uses fewer processing steps than used in existing chips, and the resulting chips are thermally stable and can be operated at higher logic voltages.

Abstract: An improved ink jet printhead is disclosed of the type having a plurality of parallel ink flow channels which terminate with an ink droplet emitting nozzle, a heating element with a cavitational protective layer thereover located in each channel, and MOS electronic circuitry monolithically integrated within the printhead for applying electrical pulses to the heating elements. The pulsed heating elements produce bubbles momentarily on the protective layer of the heating elements which expel ink droplets from the nozzles. The improvement is obtained by providing multi-layer ionic passivation of the MOS electronic circuitry which is exposable to the ink. This is accomplished through the deposition of a multi-layered, thin film insulative coating thereon consisting of a first layer of doped or undoped silicon dioxide having a thickness of 200 .ANG. to 2 .mu.m followed by a second layer of plasma nitride having a thickness of 1000 .ANG. to 3 .mu.m.

Abstract: A method for fabricating a coplanar full width scanning array from a plurality of relatively short scanning subunits for reading and writing images. The subunits are fixedly mounted in an end-to-end relationship on a flat structural member with the subunit surfaces containing the scanning elements all being coplanar even though at least some of the subunits have varying thickness. This is accomplished by forming from a photopatternable thick film layer one or more keys on the subunit surface having the scanning elements and associated circuitry and positioning the keys into keyways produced from a photopatternable thick film layer on a flat surface of an alignment fixture. A conformal adhesive bonds a structural member to the assembled subunits to form the full width scanning array.

Abstract: A thermal jet ink printing system is provided with an inproved printhead. The printhead is formed by monolithic integration of MOS transistors switches onto the same silicon substrate containing the resistive elements. In a preferred embodiment, the transistor switches and resistive elements are formed from a single layer of polysilicon with the resistive element formed on a thermally grown field oxide layer having a thickness ranging from about one to four microns. The integrated circuit chips are formed by MOS technology, are thermally stable and can be operated at higher voltages.