Comparative study of annealed neon-, argon-, and krypton-ion implantation damage in silicon

Abstract

Comparative annealing studies were carried out upon Si layers implanted with Ne+, Ar+, and Kr+ ions. Ion doses were in the range 6×1014/cm2–6×1015/cm2, and ion energies were chosen so that the matrix damage had approximately the same depth for each ion type. Annealing was carried out in a N2/dilute O2 ambient or in vacuum at 600, 900, or 1100 °C. Implanted layer structures were studied using electron-microscope and ion-backscattering techniques. The orientation of the Si substrate and ion-beam heating effects were found to be important in determining layer-annealing behavior. The latter depended weakly, if at all, upon the nature of the annealing ambient. Layer recrystallization was studied as a function of implanted ion type and dose, and the effects of inert gases trapped in the Si lattice were examined. The suitability of implantations for device gettering applications were considered. Crystallographic defects produced by annealing ranged from polycrystals and microtwins to simple dislocation networks. Faceted gas bubbles invariably occurred in annealed layers, and their geometry gave information regarding low-energy planes in Si. Electron diffraction and He+-ion channeling effects produced by twins in recrystallized layers have also been examined.

Damage accumulation in neon implanted silicon

“…The beam flux was kept in the range of ͑3-6͒ ϫ 10 12 ions cm −2 s −1 , since it was shown that changes in the implantation flux can strongly affect the accumulation of defects. 35,42 Some implantations were carried out at room temperature while others were performed at temperatures ranging from 100 up to 600°C to avoid target amorphization. Anneals were performed in a vacuum of ϳ10 −7 torr at temperatures ranging from 400 to 1100°C for 30 min in a quartz tube within a tubular furnace.…”

“…In Ar-implanted silicon it has been suggested that the large quantity of Ar present in a damaged Si layer is able to suppress the recrystallization of the layer. 35,53 In SiC, the presence of a high concentration of helium leads to the formation of different polytypes in the recrystallized area. 54…”

“…Inert gas implantation ͑Ne, Kr, Ar, and Xe͒ in silicon has been already studied to some extent in the 1980s; [35][36][37] however, implantations were carried out at room temperature, leading to the amorphization of silicon samples. Under such conditions, neon implantation followed by annealing at 800°C created arrays of dislocation loops and dipolelike structures, 38 polycrystalline regions, or dislocation networks, depending on the implanted fluence 39 and bubbles and microtwins in an epitaxially regrown layer.…”

“…Under such conditions, neon implantation followed by annealing at 800°C created arrays of dislocation loops and dipolelike structures, 38 polycrystalline regions, or dislocation networks, depending on the implanted fluence 39 and bubbles and microtwins in an epitaxially regrown layer. 36 Cullis et al 35 reported the formation of bubbles after annealing together with a network of dislocations, with the bubbles often attached to dislocations. Elliman et al 37 investigated the damage induced by MeV neon implantation, using implantation temperatures ranging between 20 and 300°C.…”

Shallow BF2 implants in Xe-bombardment-preamorphized Si: The interaction between Xe and F

“…3,7 Previous studies of inert gas ion implantation into Si and metals and annealing have shown that implanted ions tend to agglomerate or form bubbles depending on the implant dose. [12][13][14][15] In particular Xe has been shown to form bubbles in Si during annealing. 12 Although BF 2 implantation is capable of amorphizing the Si matrix, deeper preamorphizing implants ͑PAI͒, using higher mass ions such as Ge, are preferred since they suppress channelling effects and enable the spatial separation of the end-of-range ͑EOR͒ defects and the junction depth.…”