Reflow of Al-Cu by low-temperature germane reactions

R. V. Joshi

doi:10.1117/12.250872

13 September 1996 Reflow of Al-Cu by low-temperature germane reactions

R. V. Joshi

Proceedings Volume 2875, Microelectronic Device and Multilevel Interconnection Technology II; (1996) https://doi.org/10.1117/12.250872
Event: Microelectronic Manufacturing 1996, 1996, Austin, TX, United States

Abstract

This paper describes a low temperature reflow of Al-Cu using GeH₄ reactions. The Al-alloy reflow occurs due to formation of low melting point eutectic with Germanium. This technique results in a low cost process for filling high aspect ratio vias/lines with Al-based alloys with improved damascene capability. This is achieved at temperatures below 400 degree(s)C by reacting Germane (GeH₄) with Al-Cu alloys deposited by conventional techniques which result in voids, gaps and poor filling. Using such a process it is demonstrated that high aspect ratio vias with large undercuts can also be filled without voids. The low temperature provides capability to form multilevel homogeneous Al-alloy via/line structure without degrading the resistance of underlying interconnects. The reliability data shows that Al-Cu-Ge via/interconnect structure deposited by this method is at least `1.5X' better electromigration life time (t₅₀) to that of hot sputtered Al-Cu (deposited at 535 degree(s)C) and almost `2X' to that of conventionally used CVD W stud/Al-Cu interconnect structure. The improvement in the reliability may be attributed to filling without voids high aspect ratio sub- half micron vias with low resistivity metal such as Al-Cu-Ge at temperatures well below 400 degree(s)C. Since this technique does not rely on the wetting layer or diffusion barrier a lower sheet resistance of Al-Cu-Ge line is achieved compared to high temperature reflow processes. Also the reaction between Al and GeH₄ takes place uniformly resulting in reproducible contact resistance. Most importantly it is possible to achieve `high open-short yields' of comb- serpentine structures, and via chains of difficult to polish materials like Al-Cu using `damascene' process.

Citation Download Citation

R. V. Joshi "Reflow of Al-Cu by low-temperature germane reactions", Proc. SPIE 2875, Microelectronic Device and Multilevel Interconnection Technology II, (13 September 1996); https://doi.org/10.1117/12.250872

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KEYWORDS

Chemical vapor deposition

Resistance

Aluminum

Sputter deposition

Germanium

Polishing

Semiconducting wafers

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