The effects of implantation temperature (Ti) on the chemical and physical structure of annealed high‐dose oxygen ion implanted layers were investigated by Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). At low Ti (∼400 °C) the buried oxide is bordered by layers of polycrystalline silicon (polysilicon) which, in the top silicon layer, is separated from damaged single crystal Si by a thin band of discontinuous oxide. These polysilicon layers are formed from amorphous regions during high‐temperature anneals. At high Ti (∼500 °C) polysilicon was not observed.

Effects of implantation temperature on the properties of buried oxide layers in silicon formed by oxygen ion implantation

Ion-induced electron emission as a means of studying energy- and angle-dependent compositional changes of solids bombarded with reactive ions: I. Oxygen bombardment of silicon

Raman scattering spectroscopy is applied to an evaluation of silicon‐on‐insulator substrates formed by high‐dose oxygen‐ion implantation. This implantation creates a superficial crystal silicon/buried oxide/substrate silicon structure. Two peaks are found in the Raman spectra of the substrates. Their intensity ratio varies with the exciting laser wavelength. One narrow peak at 521 cm−1 is assigned to optical phonons in the substrate silicon, and the other broader peak at lower frequency is assigned to the superficial silicon. With an increase in postimplantation annealing temperature, the Raman peak frequency of the superficial silicon increases and the linewidth becomes narrower, approaching the values of single‐crystal silicon. One possible interpretation for the Raman peak downshift is that the oxygen‐ion implantation causes structural deformations of the superficial silicon layer, mainly oxygen precipitation and defect generation.

Raman scattering measurement of silicon‐on‐insulator substrates formed by high‐dose oxygen‐ion implantation

The formation of buried SiO 2 layers by high dose oxygen implantation has been monitored by the implantation of 18O tracer atoms and subsequent analysis by negative ion SIMS. Exchange of 18O with matrix oxygen in the buried layer occurred for all experiments. Rapid redistribution of the implanted tracer trace to the edges of the SiO 2 layer was observed. The lower SiSiO 2 interface appears to be a barrier to further redistribution of the tracer oxygen.

SIMS and 18O tracer studies of the redistribution of oxygen in buried SiO 2 layers formed by high dose implantation

Recent progress in materials characterization by sputter profiling is discussed, with particular emphasis on a critical evaluation of the parameters that determine the depth resolution. The net effect of beam-induced material transport and sputtering can be studied in a straightforward manner using abrupt doping distributions embedded in the matrix of interest, parallel to its flat surface. It is shown that the quality of the data that can be obtained with modern instruments is sufficient to identify lack of sample quality in terms of either surface flatness or abruptness of the doping distributions

Towards the ultimate limits of depth resolution in sputter profiling: Beam-induced chemical changes and the importance of sample quality

SIMS analysis of silicon on insulator structures formed by high-dose O+ implantation into silicon

The segregation of Cu in Si under oxygen ion bombardment has been investigated using secondary ion mass spectrometry (SIMS). The decay length of the Cu signal observed when depth profiling a Cu implanted (100) n-type Si wafer has been measured as a function of the angle of incidence and the primary beam energy. The decay length at normal incidence is found to vary linearly as a function of energy, between 2.5 and 14 keV O 2 atom. The dependence with angle was measured at 14 keV O 2 atom and is found to be much stronger. From normal incidence to 20° the decay length decreases rapidly from 3000 to 311 nm. From 20 to 30° another order of magnitude drop in decay length is observed with most of the drop occurring between 20 and 25°. Past 30° the decay length is almost constant with a value of approximately 32 nm. These changes in decay length with energy and angle are discussed with reference to the nature of the altered layer formed under oxygen bombardment of Si.

S.D. Littlewood

Papers

SIMS analysis of silicon on insulator structures formed by high-dose O+ implantation into silicon

A quantitative study of copper segregation in silicon under oxygen ion beam bombardment using SIMS