Rapid low-resistance interconnects by selective tungsten deposition on laser-direct-written polysilicon

• Published in: IEEE electron device letters 1986-07, Vol.7 (7), p.422-424
• Main Authors: Black, J.G., Ehrlich, D.J., Sedlacek, J.H.C., Feinerman, A.D., Busta, H.H.
• Format: Article
• Language: English
• Subjects: Applied sciences; Backscatter; Conductive films; Conductivity; Contact resistance; Electronics; Exact sciences and technology; Integrated circuit interconnections; Integrated circuits; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductor films; Silicon; Testing; Thin film circuits; Tungsten
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/EDL.1986.26423

Polysilicon interconnections were locally deposited on oxide-covered silicon wafers by pyrolysis of silane using a scanned Ar+-laser spot. The 2-µm-wide interconnects, written at scan speeds of 2.5 mm/s, have a 500-µΩ.cm resistivity and exhibit low contact resistance to underlying Al and Al/Si structures. These films were subsequently reacted with WF 6 vapor to form a tungsten-silicon composite interconnect by the silicon reduction of WF 6 . Electrical tests show that the conductivity of 0.4-µm-thick conductors is enhanced up to 20-fold, by formation of a surface metallic layer having conductivity characteristic of pure thin-film tungsten. Auger and Rutherford backscattering spectra (RBS) confirm the purity and selectivity of the surface tungsten layer formed at temperatures compatible with preexisting aluminum metallization. The tungsten-polysilicon composite interconnects have applications as rapidly written discretionary metallization for prototyping and in situ analysis of integrated circuits.