Burroughs, Inc.

Rakesh Kumar

Merrill Hunt

Mark A Vinson

Norman W Jones

Michael R Gulett

In the disclosed method, dopant atoms of a first conductivity type are implanted into the surface of a semiconductor substrate to form a channel region of each transistor having a relatively high dopant density at a predetermined depth below the surface and a substantially lower dopant density at the surface. This eliminates reachthrough in the channel without adversely increasing the channels threshold voltage. Thereafter, dopant atoms of a second conductivity type are implanted into the substrate to form source and drain regions adjacent to the channels having a depth of less than 0.3 .mu.m below the surface. This minimizes the radius of curvature and corresponding depletion width at the respective junctions with the channel. Subsequently, a patterned insulating layer is formed on said surface at temperatures that are far below the insulating layer's flow point. This avoids diffusing the distribution of the implanted dopant atoms. Later, a layer of metallic contact is formed in an opening of the patterned insulating layer that exposes one of the source and drain regions. This layered metallic contact has a lower layer which is comprised of a material that prevents an upper layer from penetrating through the exposed source or drain region.

Method for mass producing miniature field effect transistors in high

This disclosure relates to a method of fabricating an integrated circuit wherein all dopant layers are formed by ion implantation. More specifically, the buried collector of a bipolar integrated circuit is formed by ion implantation which collector has a high density of dopant species and is formed relatively deep into the substrate on which the circuit is formed. In addition, in order to reduce the number of steps employed in the fabrication, certain of the implanted species can be activated during the same high temperature annealing step. A pre-aligned mask is employed for the formation of the base contact, collector contact, and emitters, which mask can be selectively opened with a reduced number of masking steps. With such a mask, the base contact, collector contact and emittor are self-aligned even though formed at different steps in the process.

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Escondido, CA, United States of America

Rakesh Kumar