Development of 111 texture in Al films grown on SiO{sub 2}/Si(001) by ultrahigh-vacuum primary-ion deposition
- Materials Science Department, The Coordinated Science Laboratory and the Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)
- IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)
A high degree of 111 preferred orientation with minimal mosaic spread has been shown by many researchers to be essential for electromigration resistance in Al-based interconnects. We have found that 111 texture can be greatly enhanced through the use of low-energy self-ion irradiation during deposition. In these experiments, 300-nm-thick Al layers were grown on SiO{sub 2} at 65{degree}C from highly ionized beams provided by an ultrahigh-vacuum primary-ion deposition (PID) source. Al{sup +} ion energies {ital E}{sub Al{sup +}} and ion/neutral ratios {ital J}{sub Al{sup +}}/{ital J}{sub Al} were independently varied from 10 to 120 eV and from 0{percent} to 68{percent}, respectively. All PID Al films exhibited very strong 111 preferred orientations, which increased with increasing {ital E}{sub Al{sup +}} and/or {ital J}{sub Al{sup +}}/{ital J}{sub Al}, and azimuthally symmetric x-ray diffraction pole figures with no measurable tilt. The full width at half-maximum intensity {Delta}{omega} of 111 {omega}-rocking curves decreased continuously from 9.6{degree} with {ital E}{sub Al{sup +}}=10 eV and {ital J}{sub Al{sup +}}/{ital J}{sub Al}=68{percent} to 2.2{degree} with {ital J}{sub Al{sup +}}/{ital J}{sub Al}=120 eV compared to 10.6{degree} for films deposited by thermal evaporation. This was accompanied by a continuous decrease in the average grain size from 370 nm for thermal deposition to 90 nm with {ital E}{sub Al{sup +}}=120 eV. The PID Al films exhibited a columnar microstructure with weak competitive column growth. Changing the beam energy after the formation of a continuous layer had only a minor effect on film texture, indicating that the degree of ion-irradiation-induced preferred orientation is controlled during nucleation and/or coalescence while local pseudomorphic forces dominate thereafter. (Abstract Truncated)
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- DOE Contract Number:
- AC02-76ER01198
- OSTI ID:
- 278953
- Journal Information:
- Journal of Vacuum Science and Technology, A, Vol. 14, Issue 2; Other Information: PBD: Mar 1996
- Country of Publication:
- United States
- Language:
- English
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