Low-temperature chemical vapor deposition of tantalum nitride from tantalum pentabromide for integrated circuitry copper
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Low-temperature chemical vapor deposition of tantalum nitride from tantalum pentabromide for integrated circuitry copper metallization applications Xiaomeng Chen, Gregory G. Peterson, Cindy Goldberg, Gerry Nuesca, Harry L. Frisch, and Alain E. Kaloyerosa) New York State Center for Advanced Thin Film Technology and Department of Physics, The University at Albany – State University of New York, Albany, New York 12222
Barry Arkles Gelest Inc., Tullytown, Pennsylvania 19007
John Sullivan MKS Instruments Inc., Andover, Massachusetts 01810 (Received 14 April 1998; accepted 6 November 1998)
A low-temperature (,450 ±C) thermal chemical vapor deposition (CVD) process was developed for the growth of TaNx from the reaction of tantalum pentabromide, ammonia, and hydrogen. Studies of process reaction kinetics yielded two sequential rate-controlling steps, with an activation energy of 0.45 eV for the kinetically limited reaction regime. Additionally, a systematic design of experiments approach examined the effects of key process parameters, namely, substrate temperature, source temperature, and hydrogen and ammonia flows, on film properties. A wide CVD process window was established for nitrogen-rich amorphous TaNx with contamination below 1 at.%. Film conformality was higher than 95% in nominally 0.30 mm, 4.5 : 1 aspect ratio, trench structures.
I. INTRODUCTION
Copper (Cu) is being evaluated and implemented as a highly viable interconnect material for ultra-largescale integration (ULSI), due to its lower resistivity and superior resistance to electromigration as compared to the more commonly used aluminum (Al) and its alloys.1 In this respect, a critical need exists for the identification and development of diffusion barrier liners for emerging Cu-based metallization schemes to isolate Cu from the dielectric and device regions of the chip. These liners are required to prevent undesirable diffusion and interaction phenomena, which could lead to reliability problems and device failure. They must also be able to withstand repeated thermal processing, and serve as strong adhesion promoters to ensure the integrity of the various metallization layers needed.2 Various material systems, such as refractory metals, their nitrides, and ternary metal-silicon-nitrogen compounds, have been examined for such applications.3 Of these materials, titanium and tantalum nitrides, and their ternary compounds, are among the most extensively investigated. TiN is widely used in current aluminum- and tungsten-based interconnections as a diffusion barrier. However, the effectiveness of TiN as a Cu diffusion barrier still needs to be documented. Additionally, when a)
Address all correspondence to this author. J. Mater. Res., Vol. 14, No. 5, May 1999
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using TiN as a diffusion barrier, it effectively requires TiyTiN bilayered structure. Adding a Ti layer underneath the TiN is necessary to lower contact resistance and improve adhesion between TiN and th
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