Strain profile of (001) silicon implanted with nitrogen by plasma immersion

Abstract

In this work, we investigate the strain and defect state of silicon implanted with nitrogen by plasma immersion ion implantation, with doses between 4.5×1016 and 8.7×1016 cm−2. For this purpose, we have used Auger electron spectroscopy, x-ray reflectivity, and high-resolution x-ray diffraction. Auger spectra showed that nitrogen concentration profiles broaden and shift deeper into the substrate as the dose increases. High oxygen concentration in the first 20 nm suggested the presence of an amorphous oxide layer at the sample surface, which was confirmed by x-ray reflectivity measurements. Reciprocal space maps revealed a tensile strain perpendicular to the surface, while no in-plane strain was detected. Since no significant diffuse scattering was found, randomly distributed point defects must be predominant in the strained region compared to large displacement field defects such as clusters and dislocations. ω∕2θ scans around (004) Bragg reflection were fitted using dynamical theory of x-ray diffraction. The strain profiles obtained from the best fits correlated well with nitrogen concentration depth profiles, signaling interstitial nitrogen as the main source of strain.

Strain-profile determination in ion-implanted single crystals using generalized simulated annealing

“…Highresolution X-ray diffraction (XRD) is a widely employed technique for the determination of such strain profiles, especially in the case of implanted semiconductor materials, e.g. Si (Diaz et al, 2007;Emoto et al, 2006;Hironaka et al, 2000;Klappe & Fewster, 1994;Milita & Servidori, 1995;Sousbie et al, 2006), SiC (Leclerc et al, 2005) or GaAs (Wierzchowski et al, 2005). The determination of the strain profiles from XRD data is hindered by the 'phase problem', which arises because lattice displacements affect the phase of the diffracted amplitude, E, whereas the quantity actually measured is the intensity, I = EE*, so that the phase of the amplitude is lost in the diffraction experiment (Vartanyants et al, 2000).…”

“…Common to all these methods, which are local optimization algorithms, is that they require a good estimate of the strain profile prior to simulation in order to avoid the algorithm being trapped in a secondary minimum. Such guess strain profiles can be obtained by complementary techniques such as Rutherford backscattering spectrometry in channeling mode (RBS/C; , Auger electron spectroscopy (Diaz et al, 2007), secondary ion mass spectroscopy (Sousbie et al, 2006) or Monte Carlo simulations Emoto et al, 2006;Klappe & Fewster, 1994;Leclerc et al, 2005;Wierzchowski et al, 2005). There are cases, however, as in the present study, where the actual strain profile significantly differs from its initial estimate, or where there is no available guess strain profile.…”

A novel process for plasma immersion ion implantation and deposition with ions from vaporization of solid targets

“…4, for samples treated during 30 and 40 minutes after lithium vaporization, indicate clear distortion of the profile in comparison to the symmetrical curve seen for the sample treated just with argon plasma. Such distortions were previously measured and interpreted as an effect of ion implantation in PIII treatments [14][15][16]. Figure 4 High resolution X-ray diffraction measurements for Si samples before and after being submitted to PIII with lithium atoms.…”

Strain profiles in thin films: influence of a coherently diffracting substrate and thickness fluctuations

“…In the past three decades much effort has been devoted to recovering these strain profiles in a nondestructive way, especially using high-resolution X-ray diffraction (XRD). A well known example is the determination of strain profiles consecutive to ion implantation in semiconducting single crystals, such as, for instance, Si (Diaz et al, 2007;Klappe & Fewster, 1994;Milita & Servidori, 1995;Sousbie et al, 2006;Zaumseil et al, 1987), SiC (Leclerc et al, 2005) or GaAs (Wierzchowski et al, 2005). Strain profiles also occur in epitaxial films as a result of the film substrate lattice mismatch and the associated strain relaxation (Nicola et al, 2005).…”