Ncr Corporation

Paul A Sullivan

Gayle W Miller

George J Collins

Nicholas J Szluk

Daniel L Ellsworth

Werner A Metz, Jr

Michael J Drury

A fuse programmable ROM includes a wafer for a CMOS-type structure having an emitter, which emitter is overlain by a fuse pad of an undoped polysilicon and a conductive layer. There is a layer of barrier oxide disposed on the conductive top layer of the fuse pad and a sidewall oxide surrounding the periphery of the fuse pad both of which are overlain by the metallic electrical connection. The process of producing the fuse programmable ROM includes wide utilization of standard CMOS fabrication techniques with which are included the steps of depositing fuse material of undoped polysilicon, forming the fuse material into a fuse pad, and then making an electrical connection with the fuse pad.

Method of fabricating a high density, low power, merged vertical

A process for using selectively deposited tungsten in the making of ohmic contacts and contact/interconnect metallization patterns. In one form the process is employed to interconnect fully formed field effect devices using contacts through the dielectric layer. A thin layer of intrinsic polysilicon or amorphous silicon is conformally deposited, patterned and covered by selectively deposited tungsten, An anneal operation then forms self-aligned contacts or shunts, between the tungsten layer and the source/drain type diffusions exposed during the contact cut, by updiffusion through the thin intrinsic silicon, or by conversion of the thin intrinsic silicon to tungsten. Alternatively, contacts and shunts can be formed using polysilicon layers without regard to impurity type by making contact cuts through the dielectric to expose substrate regions, patterning a deposited polysilicon layer to cover only parts of such exposed regions, forming the field effect device source/drain regions, and then selectively depositing tungsten on all exposed surfaces of silicon. The tungsten thereby bridges the polysilicon layer to the adjacent, exposed substrate region and shunts all surface adjacent p-n junctions, including the polysilicon-to-substrate contact junction.

Use of selectively deposited tungsten for contact formation and shunting

A process for fabricating a bipolar transistor with a thin base and an abrupt base-collector junction includes the steps of depositing a thin layer of polycrystalline or amorphous silicon base material in a single crystal collector region, while in-situ doping the deposited silicon with boron atoms, and thereafter, recrystallizing the deposited silicon layer by thermal-pulse annealing at a temperature high enough to effect recrystallization and solid phase epitaxial regrowth while low enough to minimize interdiffusion of dopants between the base and collector. The process further includes providing the transistor fabricated by the aforedescribed steps with an abrupt base-emitter junction. This is accomplished by depositing n.sup.++ doped polysilicon with a LPCVD process and thereafter thermal annealing the polysilicon.

Process for fabricating a bipolar transistor with a thin base and an

A process for forming high performance npn bipolar transistors in an enhanced CMOS process using only one additional mask level. The bipolar transistor is formed using a low dose blanket implant to form the base in the substrate n-well, then applying arsenic-implanted polysilicon to form the emitter. The emitter formation involves forming a blanket polysilicon layer over the wafer, then using the additional photomask to confine the subsequent arsenic implant to the emitter, n.sup.+ and polysilicon contact regions, prior to application of aluminum metallization. The arsenic implanted polysilicon technique provides state-of-the-art bipolar processing as well as improved contact characteristics. The combined polysilicon-aluminum metallization improves step coverage, circuit reliability, and reduces the possibility of aluminum diffusion (spiking) through junctions. The n-type contact resistance is improved by virtue of being implanted with arsenic; the p-type contact resistance is controlled by the diffusion from the p.sup.+ regions which dope the polysilicon during the emitter drive-in cycle.

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Fort Collins, CO, United States of America

Paul A Sullivan