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Process for Low Contact Resistance Shallow Junction Structures with Good Junction Integrity

IP.com Disclosure Number: IPCOM000052521D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Howard, JK: AUTHOR

Abstract

Described here is an approach to improve thermal stability of Al or Al Cu/Ti contact to Approximately > 500 Degrees C yielding low contact resistance a penetration.

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Process for Low Contact Resistance Shallow Junction Structures with Good Junction Integrity

Described here is an approach to improve thermal stability of Al or Al Cu/Ti contact to Approximately > 500 Degrees C yielding low contact resistance a penetration.

Shallow junction integrity and low contact resistance structures can be achieved using Al over Ti. However, these structures are limited to 450 Degrees C anneals, whereas approximately > 500 Degrees C is normally required to remove electron-beam (when used) induced damage, in processing. Various schemes using oxides and nitrides have been proposed to reduce Al-Ti reaction (which forms high resistance TiAl(3) phase) rates, and thus extend the anneal temperature to 500 Degrees C or beyond.

In this approach, proposed is an alternate diffusion barrier(s) to reduce Al-Ti reaction during 500 Degrees C anneals. The process requires deposition of Ti (500-2000 Angstrom) and a metal selected from Pt, Pd, Rh, Ir (thickness 200-800 Angstrom), as shown in Fig. 1; the deposition can be done in a single pump down at low pressures Approximately < 10/-6/ torr. Next, the composite film is annealed in an inert ambient (vacuum, argon, forming gas or nitrogen, with the preferred being underlined) to 400-500 Degrees C for short times (Appro hour). For these structures, interdiffusion leads to formation of intermetallic compound phases (TiPt, Ti(3)Pt, for instance). These phases are located at Pt grain boundaries (TiPt) or at Ti-Pt interface (Ti(3)Pt), as shown in Fig. 2.

The formation of Ti(3)Pt stops Ti from diffusing...