Abstract
The effects of substrate heating and preamorphization on the formation of self-aligned TiSi2 on (001)Si in both large-area wafers and inside 0.1-0.6μm oxide openings of patterned wafers have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD) and sheet resistance measurement. Substrate heating and preamorphization were found to decrease the grainsize of high resistivity C49-TiSi2. The phase transformation of titanium silicide from C49 to C54 was significantly influenced by the presence of amorphous interlayer. From TEM observation, the C49-TiSi2 grain size was found to depend on the thickness of amorphous TixSiy interlayer in as-deposited samples. Substrate heating enhanced the growth of the TixSiy amorphous interlayer with substrate heating temperature. The nucleation sites of C49-TiSi2 were increased by the presence of amorphouis TixSiy interlayer. The thicker amorphous TixSiy interlayer, indicating a higher degree of intermixing between Ti and Si, provided more nucleation sites. Preamorphization implantation treatment also enhanced the formation of amorphous Si interlayer, which in turn led to smaller C49-TiSi2 grain size than that on large-arrea samples. Inside oxide openings, lower bottom coverage of as-sputter deposited Ti films increased the activation energy of TiSi2 transformation. The thinner amorphous TixSiy interlayers were observed to form inside higher aspect ratio oxide openings. The nucleation sites of C49-TiSi2 were reduced. Dou to the change of oxide opening profile in the substrate cleaning processes before metal deposition, non-uniform TiSi2 layers were formed in the preamorphization implantation treated samples.