Random and channeled implantation profiles and range parameters for P and Al in crystalline and amorphized Si

Abstract

We have measured implanted and annealed depth distributions for the two elements adjacent to Si, Al, an acceptor in Si, and P, a donor in Si, using secondary ion mass spectrometry for the atom depth distributions and differential capacitance-voltage profiling for the acceptor or donor depth distributions. Ions of Al or P were implanted into Si amorphized by Si implantation, into crystalline Si in a random orientation, and channeled into the three principal low index directions of the Si lattice, 〈100〉, 〈110〉, and 〈111〉. The ion energies were 25, 50, 75, 100, 150, 200, 300, 400, or 600 keV and the ion influences were 3×1013, 3×1014, and 3×1015 cm−2 for the atom depth distributions, and 1.5×1012 cm−2 for the acceptor and donor profiles. Pearson IV fitting was used to obtain the values of the first four moments of the random depth distributions, the projected range Rp or μ, the range straggle ΔRp or standard deviation σ, the skewness γ1, and the kurtosis β2. For the channeling orientations, the maximum channeling range or the depth of the channeled peak are plotted versus ion energy, and values of the energy exponent p are determined. The random ranges Rp and profiles are compared for amorphized and crystalline Si and compared with range calculations; the profiles in amorphized Si are modified Gaussians as predicted by theory, with no channeling tails, and the profiles in crystalline Si have significant channeling tails that are not easily fit to a modified Gaussian. The different channeling profiles for Al and P are illustrated and explained in terms of their different electronic stopping and ion size. The effects of 30-min furnace annealing at 550 and 800 °C are shown for implanted Al profiles; significant redistribution occurred, and in a manner that depends on Al atom density and whether the Si is amorphous or crystalline. Furnace annealing at 875 and 925 °C or rapid radiant annealing at 900 °C caused no redistribution of P profiles implanted at room temperature.