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Browse Prior Art Database

Process for Making Contacts to Shallow Junctions

IP.com Disclosure Number: IPCOM000034910D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR [+4]

Abstract

Leakage and short circuits through shallow junctions is avoided in this process. Reactive ion etch (RIE) damage during contact hole formation in an inorganic insulator layer is eliminated by use of an organic etch stop. Consumption of shallow junction material during silicidation of contacts is eliminated by applying a layer of epitaxial silicon over the junction material. Referring to Fig. 1, a cross-section is shown of a bipolar device under construction. The device is comprised of a collector region 2 formed in substrate 4, a base region 6 formed in epitaxial layer 8, and three contact regions 10, 12, and 14 which are respectively for emitter, base and collector contacts. The emitter diffusion 16 is formed by doping through the same mask opening used to define etching of contact 10.

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Process for Making Contacts to Shallow Junctions

Leakage and short circuits through shallow junctions is avoided in this process. Reactive ion etch (RIE) damage during contact hole formation in an inorganic insulator layer is eliminated by use of an organic etch stop. Consumption of shallow junction material during silicidation of contacts is eliminated by applying a layer of epitaxial silicon over the junction material. Referring to Fig. 1, a cross- section is shown of a bipolar device under construction. The device is comprised of a collector region 2 formed in substrate 4, a base region 6 formed in epitaxial layer 8, and three contact regions 10, 12, and 14 which are respectively for emitter, base and collector contacts. The emitter diffusion 16 is formed by doping through the same mask opening used to define etching of contact 10. Emitter contacts are filled by conformally coating with an organic material 18 followed by RIE. Other contacts, e.g., base 12 and collector 14, do not require doping, but may also be filled with organic material 18. To form the cross-section shown in Fig. 2, an inorganic insulator 20 is deposited and contact hole openings are formed over contacts 10, 12, and 14 by RIE and etching stops at organic insulator 18 (shown in Fig. 1). Wet etching is then used to remove the organic insulator 18. Next, epitaxial silicon 22 is selectively deposited on exposed silicon and, finally, a transition metal 24 is conformally deposited. Thus, during s...