Browse Prior Art Database

ELO Alignment Marks for Dual Subcollector Processes

IP.com Disclosure Number: IPCOM000037162D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Burghartz, JN: AUTHOR

Abstract

Epitaxial Lateral Overgrowth (ELO) over an oxide stripe is proposed in order to leave a gap as a mark for subsequent mask alignment and to avoid pattern distortion during the growth of the collector flatzone in bipolar dual-subcollector processes.

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ELO Alignment Marks for Dual Subcollector Processes

Epitaxial Lateral Overgrowth (ELO) over an oxide stripe is proposed in order to leave a gap as a mark for subsequent mask alignment and to avoid pattern distortion during the growth of the collector flatzone in bipolar dual-subcollector processes.

The fabrication of a dual-subcollector structure for complementary bipolar or complementary BICMOS (C-BICMOS) includes an alignment of the patterned subcollectors to the subsequent mask levels. Since after subcollector formation a thick mid-temperature epitaxy (MTE) flatzone is grown, misalignment must be expected due to pattern distortion which is typical for such chlorine-based MTE systems *.

This problem can be avoided if a selective epitaxy process is used in order to leave a gap as an alignment mark while overgrowing over a thin oxide stripe. The oxide pattern should be aligned to the (100)- axis on a [100]-substrate because vertical and lateral growth rates are identical in this case and overgrowth will occur with steep sidewalls.

Reference: * C. M. Drum, C. A. Clark, "Geometrical Stability of Shallow Surface Depressions During Growth of (111) and (100) Epitaxial Silicon," J. Electrochem . Soc . 115, 664(1968).

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