Active solid-state devices (e.g. – transistors – solid-state diode – Bipolar transistor structure
Reexamination Certificate
2007-10-30
2007-10-30
Doan, Theresa (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Bipolar transistor structure
C257S517000
Reexamination Certificate
active
10969718
ABSTRACT:
A self-aligned oxide mask is formed utilizing differential oxidation rates of different materials. The self-aligned oxide mask is formed on a CVD grown base NPN base layer which compromises single crystal Si (or Si/SiGe) at active area and polycrystal Si (or Si/SiGe) on the field. The self-aligned mask is fabricated by taking advantage of the fact that poly Si (or Si/SiGe) oxidizes faster than single crystal Si (or Si/SiGe). An oxide film is formed over both the poly Si (or Si/siGe) and the single crystal Si (or Si/siGe) by using an thermal oxidation process to form a thick oxidation layer over the poly Si (or Si/siGe) and a thin oxidation layer over the single crystal Si (or Si/siGe), followed by a controlled oxide etch to remove the thin oxidation layer over the single crystal Si (or Si/siGe) while leaving the self-aligned oxide mask layer over the poly Si (or Si/siGe). A raised extrinsic base is then formed following the self-aligned mask formation. This self-aligned oxide mask blocks B diffusion from the raised extrinsic base to the corner of collector.
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Method of forming a substrate contact for a bipolar memory cell (Apr. 1985) IBM Technical Disclosure Bulletin.
Chen Huajie
Freeman Gregory G.
Rieh Jae-Sung
Schonenberg Kathryn T.
Stricker Andreas D.
Abate Esq. Joseph P.
Doan Theresa
Scully Scott Murphy & Presser, PC
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