STRUCTURAL CHARACTERIZATION OF NITROGEN ION-IMPLANTATION INTO SILICON FOR SENSOR TECHNOLOGY

In this work buried etch-stop layers in silicon are formed by implantation of a substoichiometric dose of nitrogen and annealing at temperatures up to 1150-degrees-C. Transmission electron microscopy, secondary ion mass spectrometry, Raman spectroscopy and Fourier transform infrared spectroscopy are used to study the structure of the implanted material and its evolution with the thermal treatments. Results show that nitrogen is gettered around the implantation peak and that precipitation in the form of amorphous SiN and sometimes in alpha-Si3N4 occurs. Raman spectra suggest the presence of a remaining stress in the top Si layer, although the presence of a high density of amorphous SiN precipitates also contributes to the observed shifts.