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ENCASING ALUMINUM LINES IN TUNGSTEN TO PREVENT Al ELECTROMIGRATION IN Al-W INTERCONNECT METALLURGIES

IP.com Disclosure Number: IPCOM000040314D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR

Abstract

A method of providing low impedance metallic interconnections without risk of electromigration problems, in which aluminum-copper (AlCu) lines are encased in refractory metals, such as tungsten (W), is disclosed. An AlCu line 12 is defined over an underlayer of W and/or titanium (Ti) 10 by conventional means, such as Reactive Ion Etch (RIE) or lift-off processes. Then tungsten 14 is chemically vapor deposited on all metallic surfaces. Using selective growth techniques, such as chemical vapor deposition (CVD), results in W forming on top of the AlCu-W sandwich 10 and 12, as shown in Fig. 1.

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ENCASING ALUMINUM LINES IN TUNGSTEN TO PREVENT Al ELECTROMIGRATION IN Al-W INTERCONNECT METALLURGIES

A method of providing low impedance metallic interconnections without risk of electromigration problems, in which aluminum-copper (AlCu) lines are encased in refractory metals, such as tungsten (W), is disclosed. An AlCu line 12 is defined over an underlayer of W and/or titanium (Ti) 10 by conventional means, such as Reactive Ion Etch (RIE) or lift-off processes. Then tungsten 14 is chemically vapor deposited on all metallic surfaces. Using selective growth techniques, such as chemical vapor deposition (CVD), results in W forming on top of the AlCu-W sandwich 10 and 12, as shown in Fig. 1. The encasement in CVD W will not only enhance the electromigration resistance of the metal line, but will also reduce line extrusion while enhancing line-to-stud contact area since tungsten vias 16 and the ends of the AlCu-W lines 10 and 12 are also encased in CVD W 14, as shown in Fig. 2.

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