National Semiconductor Corporation

George E Ganschow

Ali A Iranmanesh

Christopher S Blair

Rick C Jerome

Bancherd DeLong

James L Bouknight

Vida Ilderem

Alan G Solheim

Frank Marazita

Brian McFarlane

Ronald P Kovacs

Madan Biswal

Rajeeva Lahri

Bamdad Bastani

Lawrence K Lam

Thomas S Crabb

Steve M Leibiger

Tad Davies

A method for improving the performance of a walled emitter bipolar-junction transistor and the improved walled emitter bipolar junction transistor resulting therefrom are disclosed. The method involves the incorporation of a p-type dopant, preferably boron, at the intersection of the isolation oxide and the emitter-base region. The selective implantation does not affect the transistor's function in any significant way, does not complicate the fabrication process to any significant degree and eliminates known problems of intrinsic base boron segregation and oxide charges in known walled emitter bipolar junction transistors.

Inversion implant isolation process

A vertical fuse structure including a lightly-doped shallow emitter 30 provides improved fusing characteristics. The structure includes a buried collector 14, an overlying base 30, and an emitter 44 above the base 30. In one preferred embodiment, the emitter 44 extends about 0.2 microns from the upper surface and has a dopant concentration of about 8.times.1019 atoms of arsenic per cubic centimeter at the surface. A lightly doped base region 30 extends for about 0.46 microns below the emitter 44 to the collector 14. The upper surface of emitter 44 includes a metal contact 60. Heating the metal 60/emitter 44 interface to its eutectic melting point using a current or voltage pulse causes the aluminum to short through the emitter 44 to the base 30. Shorting the emitter programs the fuse. A second preferred embodiment uses polysilicon as an interconnecting medium. Mass transport of aluminum atoms through the polysilicon allows aluminum to collect at an interface between the polysilicon and an underlying single crystal silicon layer. Aluminum atoms are supplied from a contact metal. A barrier metal between the contact metal and an underlying polysilicon contact to the emitter is not present. Inhibiting or replacing a TiSi.sub.2 layer over the fuse emitter contact provides better reproducible fusing action. PtSi replaces TiSi.sub.2 if formed over the fuse emitter contact. Separate fuse base implants for the vertical fuse change BJT parameters for improved fusing characteristics. In still another preferred embodiment, codiffusing N type and P type dopants from the polysilicon emitter contact drops a separate fuse mask. The P type codiffused dopants diffuse ahead of the N type emitter dopants into the single crystal to change the base parameters to provide a decreased gain.

Vertical fuse device

A bipolar transistor having a base intrinsic region, collector region, and emitter region. The emitter region, collector region, and base intrinsic region each having at least a portion thereof adjacent to an oxide isolation region. The base intrinsic region having a diffusion compensation region therein abutting the oxide isolation region. The diffusion compensation region compensates for the intrinsic concentrations segregating during oxidation, and also compensates for oxide charge contribution to the base region. The additional dopant in the compensation region results in only a small increase in the desired BJT performance and adds minimal complexity in manufacturing. The invention results in the controlled placement of dopants near the 'birds's beak' between the emitter and base providing I.sub.CEO leakage current reduction at the emitter edge without affecting the bulk of the active intrinsic base.

Bipolar transistor with diffusion compensation

An improved method for fabricating polysilicon Schottky clamped transistors and vertical fuse devices in the same semiconductor structure is disclosed. The resulting structure yields an improved Schottky clamped transistor and vertical fuse device. The improved Schottky transistor has a silicide rectifying contact between the base and collector of the transistor, the vertical fuse is provided with a direct contact between an aluminum contact metal and a polysilicon emitter contact.

Method of making polysilicon Schottky clamped transistor and vertical

Polysilicon Schottky clamped transistor and vertical fuse devices

A high performance bipolar transistor and a method of fabrication. Base resistance is reduced by a self-aligned silicide formed in the single-crystal region of the extrinsic base, thereby eliminating the polysilicon to single-crystal contact resistance as well as shunting the resistance of the single-crystal extrinsic base region. Oxide from the sidewall of the polysilicon local interconnection is selectively removed prior to silicide formation. Therefore, selected sidewalls of the poly interconnect layer also becomes silicided. This results in significant reductions in resistance of the interconnection, particularly for sub-micron geometries. Improved techniques for forming field oxide regions and for forming base regions of bipolar transistors are also disclosed.

Reducing base resistance of a BJT by forming a self aligned silicide in

A bipolar transistor and resistor are provided. Fabrication includes using a high temperature oxide to form sidewall spacers for the transistor contacts and/or to overlay the resistor portion of the device. Deposition of the HTO is combined with dopant drive-in so that fewer total steps are required. The process is compatible with MOS technology so that the bipolar transistor and resistor can be formed on a substrate along with MOS devices.

Self-aligned silicided base bipolar transistor and resistor and method

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Trabuco Canyon, CA, United States of America

George E Ganschow