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AssigneeInternational Business Machines Corporation
InventorsGregory G. Freeman, K. T. Schonenberg, Kenneth J. Stein, Seshadri Subbanna
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Bipolar transistors of different designs, particularly designs optimized for different high frequency applications are formed on the same substrate by separate base layer formation processes for epitaxial growth including different material concentration profiles of germanium, boron and/or carbon. Epitaxial growth of individual growth layers by low temperature processes is facilitated by avoiding etching of the silicon substrate including respective collector regions through use of an etch stop that can be etched selectively to silicon. Annealing processes can be performed between growth of respective base layers and/or performed collectively after all transistors are substantially completed.
A method of forming transistors of different designs on a single chip, said method including steps of
Dependencies are inferred from the claim text.