Arsenic segregation at Si(lO0) surfaces during annealing (890–970°C) has been studied by medium energy ion scattering (MEIS), Rutherford backscattering spectrometry (RBS), ion scattering spectrometry (ISS), and Auger electron spectroscopy (AES). The unique depth resolution of MEIS revealed that arsenic segregated in a two-dimensional layer at the clean Si surface during annealing. For a surface with a native oxide the arsenic piled up at the Si/oxide interface. This segregation peak was no longer present on the Si surface after conventional contact opening. By metallizing arsenic junctions with Al:Si, 1% it was found that a segregation annealing step inhibited Al/Si interdiffusion. Diodes as shallow as 180 nm could be metallized without spiking.

Smooth titanium silicide films have been deposited using a Low Pressure Chemical Vapor Deposition (LPCVD) process. A system has been designed and built for the LPCVD of titanium silicide. It is a cold wall reactor with the wafer being heated externally by infrared lamps. Sequential deposition of polycrystalline silicon (polysilicon) and titanium silicide films, and in-situ annealing of these films, if required, can be performed in this system. A turbomolecular pump is used to provide a contaminant free environment with a base pressure of <10−7 torr. SiH4 and TiCl4 are used as silicon and titanium sources, respectively.

Tithnium silicide films with resistivities ranging from 22 to 39 μΩ-cm have been obtained. At low deposition rates, these films have surface roughnesses ranging from 50 to 250 Å. From X-ray diffractometry, it was determined that the as-deposited titanium silicide films were polycrystalline, and TiSi2 was the predominant phase. Si/Ti ratios of 1.8 to 2.3 were obtained frog Rutherford Backscattering Spectroscopy (RBS). Auger analyses did not show any impurities such as oxygen, carbon or chlorine in these films.

We have studied the influence of a high-temperature pre-anneal on the barrier performance of TiN in Al metallization of Si. The results show that barrier failure is shifted towards a higher temperature by 20°C-40°C when the barrier is pre-annealed at 600°C-800°C. In addition, we studied the failure mechanism and found that the barrier breaks down by compound formation.

A crystalline interfacial bilayer, consisting of about 5nm each of RhSi and Rh2Si was found after E-beam deposition of 95nm of Rh onto either Si[100] or α-Si substrates. Cross sectional TEM of the as-deposited and annealed specimens showed no change occurred after 24hrs at 200° C. With infinite supply of Si, as on the Si[100] substrate, RhSi was found as a major growing phase, although Rh2Si also grew at a much slower rate. With a limited supply of Si, as in the α-Si case, RhSi first formed until all α-Si was consumed (2 hrs at 400°C) and then transformed partially to Rh2Si after 4 hrs at 400°C. This transformation could be confirmed by RBS since Rh2Si layer thickness exceeded 30nm

The microstructures of the silicide Ni5Si2, which formed in self-supporting Ni-Si lateral-diffusion couples has been studied using high-resolution electron microscopy. Two different polymorphs (or polytypes) for Ni5Si2 have been observed. The actual composition of one polytype is confirmed to be Ni31Si12, while the other one has not yet been identified. Variations in the distribution of the two polytypes, as observed in the present study, may account for the composition range of Ni5Si2 in the Ni-Si phase diagram.

Solid state reactions between Ni thin films and (100) GaAs were studied by transmission electron microscopy, X-ray diffraction, Auger electron spectroscopy and Rutherford backscattering. The hexagonal ternary phase Ni2GaAs is formed at the temperature range of 150 to 300°C with the following epitaxial relations to the substrate: (1011)//(001) and [1011]//[100]. The gradual decrease with temperature of the (1011)interplanar spacing of this phase may be related to strain relaxation associated with microtwins formation. At the temperature range of 350 to 550°C precipitation of NiAs in Ni2GaAs matrix and an increase of the twin size are observed. In this range the (1011) interplanar spacing of the ternary phase increases with temperature, possibly due to stoichiometric changes resulting from NiAs precipitation. At 600°C the ternary phase decomposes into NiGa and NiAs with average grain size of about 1 micron in lateral dimension. The cubic phase, NiGa, has simple epitaxial relations with GaAs: (001)//(001) and [010]//[010].Ni atoms are the dominant diffusing species during the ternary phase growth process as was observed in a marker experiment utilizing a very thin Ta Layer interposed between the Ni film and the substrate.