FREQUENCY NOISE-LEVEL OF AS ION-IMPLANTED TIN-TI-SI STRUCTURES

This paper presents a possibility of using frequency noise level measu rements to study the properties of Ti silicides. We have sputter depos ited sequentially a 100 nm thick titanium layer and a 50 nm TiN layer on p-type Si (111) wafers. The TiN/Ti/Si structures were implanted wit h As+ at 350 keV, to doses from 1 X 10(15) to 1 X 10(16) ions/cm(2). T he projected range of arsenic ions is near Si-Ti interface. The sample s were annealed in vacuum at temperatures up to 800 degrees C. Methods of characterization of samples include frequency noise level measurem ents, Rutherford backscattering, and electrical measurements. Annealin g induce the Ti-Si reaction, the top TiN layer remaining stable throug hout the processing. Silicidation depends on the annealing time and te mperature, and on the implanted dose. In samples implanted up to 5 X 1 0(15) ions/cm(2) the low resistivity TiSi phase is formed at 750 degre es C. For higher implanted doses silicidation is retarded. In this cas e TiSi is formed initially, transforming to the TiSi phase for longer annealing times. Noise spectra show that the noise level depend on the implanted As dose, and that for some frequencies, the implanted sampl es have higher noise level compared to the unimplanted samples.