Development of 111 texture in Al films grown on SiO2/Si(001) by ultrahigh-vacuum primary-ion deposition

Abstract

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 SiO2 at 65 °C from highly ionized beams provided by an ultrahigh-vacuum primary-ion deposition (PID) source. Al+ ion energies EAl+ and ion/neutral ratios JAl+/JAl were independently varied from 10 to 120 eV and from 0% to 68%, respectively. All PID Al films exhibited very strong 111 preferred orientations, which increased with increasing EAl+ and/or JAl+/JAl, and azimuthally symmetric x-ray diffraction pole figures with no measurable tilt. The full width at half-maximum intensity Δω of 111 ω-rocking curves decreased continuously from 9.6° with EAl+=10 eV and JAl+/JAl=68% to 2.2° with JAl+/JAl=120 eV compared to 10.6° 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 EAl+=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. ω-rocking curves from a bilayer film consisting of a 20-nm-thick Al buffer layer grown by PID followed by a 280-nm-thick thermally evaporated Al overlayer were essentially identical to those obtained from 300-nm-thick single-layer PID Al films.

Low temperature growth of stress-free single phase α-W films using HiPIMS with synchronized pulsed substrate bias

“…64 Recrystallization during the coalescence of small clusters is also known to lead to the formation of highly textured grains more easily. 65 Moreover, by increasing the synchronized bias voltage to U s = 100 and 200 V, the ⟨110⟩ texture becomes stronger and columnar grains become larger, resulting in lattice relaxation with significant decrease of compressive stress as seen in Figs. 6 and 7.…”

Effect of Soil Amendments and Spraying with Antioxidants on Some Clay Soil Properties and Wheat Production under Climate Change Conditions

“…) was determined by sodium acetate (NaOAC) method [29]. Organic matter content was determined according to Bhattacharyya et al [30].…”