International Business Machines Corporation

Allen P Ho

Cheng Tzong Horng

Bernard M Kemlage

Shao-Fu S Chu

A method of forming a wide deep dielectric filled isolation trench in the surface of a silicon semiconductor substrate by forming a wide plug of chemical vapor deposited silicon dioxide in the trench, filling the remaining unfilled trench portions by chemical vapor depositing a layer of silicon dioxide over the substrate and etching back this layer. The method produces chemically pure, planar wide deep dielectric filled isolation trenches and may also be used to simultaneously produce narrow deep dielectric filled isolation trenches.

Method of forming wide, deep dielectric filled isolation trenches in the

Disclosed is a process for forming an improved bipolar transistor in a silicon substrate of a first conductivity type, said silicon substrate having a planar surface, a subcollector region of a second conductivity type formed in said substrate, an epitaxial layer of said second conductivity type formed on said planar surface of said substrate, and first, second and third spaced apart recessed oxide isolation regions extending from the planar surface of said epitaxial layer into said substrate, a subcollector reach-through region positioned between said second and third recessed oxide isolation regions, said subcollector reach-through region extending from said planar surface of said epitaxial layer to said subcollector region, said process including the following steps: deposit, using chemical vapor deposition techniques, a layer of doped polysilicon on the exposed surface of said substrate said dopant being of said first conductivity type; deposit, using chemical vapor deposition techniques a first layer of silicon dioxide on said polysilicon layer; deposit a layer of photoresist on said first layer of silicon dioxide; utilizing photolithography, mask off an intended intrinsic base region, said intended intrinsic base region being spaced between said first and second recessed oxide isolation regions; utilizing the resist layer as a mask employ reactive ion etching to remove the silicon dioxide and polysilicon superimposed over the intended intrinsic base region; ion implant the exposed intrinsic base region with ions of said first conductivity type; chemically vapor deposit a relatively thick silicon dioxide conformal coating on the exposed surface; reactive ion etch an emitter opening on the epitaxial surface above the implanted intrinsic base; ion implant the emitter region with ions of said second conductivity type; and utilize a single heat cycle to anneal the ion implantations and drive in the emitter, intrinsic base, extrinsic base and collector reach through.

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Sunnyvale, CA, United States of America

Allen P Ho