A need for analysis techniques, complementary to secondary ion mass spectrometry (SIMS), for depth profiling dopants in silicon for ultra shallow junction (USJ) applications in CMOS technologies has recently emerged following the difficulties SIMS is facing there. Grazing incidence X-ray fluorescence (GIXRF) analysis in the soft X-ray range is a high-potential tool for this purpose. It provides excellent conditions for the excitation of the B-K and the As-L(iii,ii) shells. The X-ray standing wave (XSW) field associated with GIXRF on flat samples is used here as a tunable sensor to obtain information about the implantation profile because the in-depth changes of the XSW intensity are dependent on the angle of incidence. This technique is very sensitive to near-surface layers and is therefore well suited for the analysis of USJ distributions. Si wafers implanted with either arsenic or boron at different fluences and implantation energies were used to compare SIMS with synchrotron radiation-induced GIXRF analysis. GIXRF measurements were carried out at the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the electron storage ring BESSY II using monochromatized undulator radiation of well-known radiant power and spectral purity. The use of an absolutely calibrated energy-dispersive detector for the acquisition of the B-Kalpha and As-Lalpha fluorescence radiation enabled the absolute determination of the total retained dose. The concentration profile was obtained by ab initio calculation and comparison with the angular measurements of the X-ray fluorescence.

The transient enhanced diffusion (TED) of As in silicon samples implanted at 35 keV with dose 5×1015 cm−2 has been investigated in the temperature range between 750 and 1030 °C by comparing experimental and simulated profiles. For temperatures higher than 900 °C the phenomenon is of modest entity and vanishes after a few seconds, whereas at lower temperatures diffusivity enhancements of some order of magnitude have been observed. The anomalous shift of the junction depth, evaluated at 2×1018 cm−3, is about 12 nm at 900 °C and increases up to 45 nm at 750 °C. It has been verified that the two are the contributions, that generate the interstitial excess responsible for the TED: (i) the implantation damage and (ii) the aggregation in clusters of the As atoms. From an experiment that allows us to separate the two contributions, we estimate that about one third of the TED observed in the first 20 min of annealing at 800 °C is due to the defects produced by clustering. The influence of clustering on the shape of the As profiles after diffusion at different temperatures is also discussed.

The diffusion of indium in silicon has been investigated in the temperature range of 800 to 1000 °C by using secondary ion mass spectroscopy and transmission electron microscopy. Our data indicate that, for implants at 150 keV through a thin oxide layer (19 nm), the amount of dopant that leaves the silicon is only controlled by the flow of indium that reaches the surface, being both the segregation coefficient at the interface SiO2/Si and the indium diffusion coefficient in the oxide favorable to the out-diffusion. Comparison between experimental and simulated profiles has evidenced that, besides the expected transient enhanced diffusion occurring in the early phases of the annealing, a heavy loss of dopant by out-diffusion was associated with a high In diffusivity near the surface. Measurements of the hole concentration in uniformly doped silicon on insulator samples performed in the temperature range of 700 to 1100 °C indicate that indium solubility is equal or greater than 1.8×1018 cm−3; this value is higher than those previously proposed in literature.

Electrical activation and redistribution of 500 eV boron implants in preamorphized silicon after nonmelt laser annealing at 1150°C and isochronal rapid thermal postannealing are reported. Under the thermal conditions used for a nonmelt laser at 1150°C, a substantial residue of end-of-range defects remained after one laser scan but these were mainly dissolved within ten scans. The authors find dramatic boron deactivation and transient enhanced diffusion after postannealing the one-scan samples, but very little in the five-and ten-scan samples. The results show that end-of-range defect removal during nonmelt laser annealing is an achievable method for the stabilization of highly activated boron profiles in preamorphized silicon. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2385215͔The continued downscaling of complementary metaloxide-semiconductor devices requires ultrashallow and abrupt source/drain extension regions with a low sheet resistance.1 Among the other processes nonmelt laser annealing has gained attention as a means of achieving these requirements by its short process time and high annealing temperature, and hence low thermal budget, resulting in high dopant solubility.2-5 A problem exists with creating highly active profiles when boron is implanted in conjunction with a preamorphizing germanium implant; deactivation occurs during postactivation thermal processes. [6][7][8][9][10][11][12] This deactivation is thought to be driven by the release of silicon interstitials from end-of-range ͑EOR͒ defects that evolve through nonconservative Ostwald ripening during annealing. 13 The interstitials flow towards the surface and decorate the boron profile, producing boron interstitial clusters. [14][15][16][17] In this letter, multiple laser scan annealing at 1150°C followed by isochronal rapid thermal postannealing at lower temperatures is used to investigate the role of end-of-range defects in the redistribution and deactivation of ultrashallow B profiles in preamorphized and nonmelt laser-annealed silicon.N-type ͑100͒ Czochralski-silicon wafers were preamorphized with 5 keV Ge + to a dose of 1 ϫ 10 15 cm −2 producing a surface amorphous layer to a depth of ϳ15 nm. 500 eV B + was implanted into the amorphous layer to a dose of 1 ϫ 10 15 cm −2 . Both implants were made using an Applied Materials Quantum X implanter. The wafers were exposed to a scanning diode laser source operated under nonmelting conditions, which was used to anneal three strips across the wafers, corresponding to one, five, or ten scans at a temperature of 1150°C. By using multiple laser scans to anneal the wafer, it allows a study of defect evolution as a function of increasing the thermal budget. The amorphous layer regrew by solid phase epitaxial regrowth during the annealing. Samples were taken from these strips and annealed in dry N 2 for 60 s at temperatures ranging from 700 to 1000°C using a Process Products Corporation rapid thermal annealing system operating with a 50°C/s heating ramp rate. The van der Pauw technique was use...

Hydrogen ͑or deuterium͒ incorporation in dilute nitride semiconductors modifies dramatically the electronic and structural properties of the crystal through the creation of nitrogen-hydrogen complexes. In this work, we investigate how the formation and dissociation of such complexes rule the diffusion of deuterium in GaAs 1−x N x . The concentration depth profile of deuterium is determined by secondary ion mass spectrometry under a wide range of experimental conditions that comprise different N concentrations ͑x = 0.09%, 0.40%, 0.70%, and 1.5%͒ and D irradiation temperatures ͑T D = 200, 250, 300 and 350°C͒. The experimental data are successfully reproduced by a diffusion model in the presence of strong D trapping. In particular, the deuterium diffusion and capture rate coefficients are determined, and a minimum decay length of the deuterium forefront is found at low T D ͑Ͻ250°C͒ and high x ͑Ͼ0.7%͒. These parameters set the experimental conditions within which a nanostructuring of the physical properties of GaAs 1−x N x is attainable.