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Browse Prior Art Database

Novel Process for Eliminating Salicide Bridging

IP.com Disclosure Number: IPCOM000040048D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Barber, JR: AUTHOR [+3]

Abstract

This article describes a process for eliminating shorting between a source or drain and the gate of an FET in a salicide process. Referring to Fig. 1, a substrate 10 has source and drain regions 12, 14 defined. Silicon oxide layer 16 overlies the substrate 10 and source and drain regions 12, 14. Polysilicon gate 18, interfacial oxide 19, and silicon nitride layer 20 are subsequently deposited and lithographically defined and etched. Following the gate definition steps, a thin conformal coating of silicon oxide is then deposited and unisotropically etched, leaving oxide spacers 22 (Fig. 2). The source and drain regions 12 and 14 are then ion implanted, as customary.

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Novel Process for Eliminating Salicide Bridging

This article describes a process for eliminating shorting between a source or drain and the gate of an FET in a salicide process. Referring to Fig. 1, a substrate 10 has source and drain regions 12, 14 defined. Silicon oxide layer 16 overlies the substrate 10 and source and drain regions 12, 14. Polysilicon gate 18, interfacial oxide 19, and silicon nitride layer 20 are subsequently deposited and lithographically defined and etched. Following the gate definition steps, a thin conformal coating of silicon oxide is then deposited and unisotropically etched, leaving oxide spacers 22 (Fig. 2). The source and drain regions 12 and 14 are then ion implanted, as customary.

(Image Omitted)

The nitride layer 20 and the interfacial oxide layer 19 are removed with hot phosphoric acid and 50:1 buffered hydrofluoric acid, respectively, leaving the structure seen in Fig. 3. A refractory metal is then evaporated in a highly directional evaporation system, insuring that the metal will not be deposited on the vertical walls 24 of spacers 22 (Fig. 4). This continuity in the metal layer 26 eliminates any shorting of the source or drain regions 12, 14 to the gate 18.

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