External diffusion of phosphorus in tantalum silicide bilayer film structure

In VLSI, tantalum silicide can be used as gate, interconnect or contact material of devices. By properly controlling the deposition and annealing conditions of the film and choosing the appropriate thickness of the film, the resistance of the thin layer of the siliconized button can be controlled within 1/10 of the resistance of the doped polysilicon thin layer used in the general integrated circuit process, so that the R C loss of the device speed can be reduced. In many applications, it is more ideal to use silicide-supported/polysilicon bilayer film structure. One of the advantages is that silicon can be provided by polycrystalline silicon to form silicides. With this silicon source, it is easy to form a disilicide phase with good conductivity repeatedly, and silicon dioxide can be grown on the silicide without damaging its conductivity.

Another advantage is that the oxide/polycrystalline silicon interface in the double-layer structure is stable. The silicified support layer in the double-layer structure can be formed by solid reaction between a thin layer of button film and the polycrystalline silicon film on it, or by the button and silicon atoms deposited on the polycrystalline silicon at the same time. After deposition, annealing is needed to produce this reaction process and promote the growth of low resistivity grains. We find that it is during this annealing process that the resistance of the thin layer doped with polysilicon in the structure increases rapidly. Of course, high resistivity polysilicon is undesirable for device applications. It will also bring about dry etching process in the future. It is difficult because the corrosion rate of polycrystalline silicon in chlorine strongly depends on the resistivity of the material.

Tantalum silicide (TaSi2) has an attractive combination of properties, including a high melting point of 2200 °C, high thermal stability, low electrical contact resistance, a high modulus of elasticity, a high resistance to oxidation in air, and a good compatibility with silicon. Due to its low electrical resistance and oxidation resistance, TaSi2 has been utilized in switching devices as Schottky barriers, ohmic contacts, and connectors in integrated circuits. In the present work, JL particles with a metallic TaSi2 end and a semiconducting Si end were synthesized. This composition should lead to a spatial separation of electrons and the appearance of polarization charges, leading to the presence of a dipole moment. Thus, the spatial orientation of these JL nanoparticles should be controllable by the interaction of the dipole moment with an external electromagnetic field.

Amorphous tantalum–silicon–nitrogen films of about 500 nm thickness were, reactively, sputter deposited onto (100)Si substrate using d.c. magnetron sputtering from TaSi0.1, TaSi0.4, and TaSi0.6 target materials. The film properties were characterized by using sheet resistance measurements and X-ray diffraction. With increasing amounts of nitrogen in the sputtering gas, the resistivity of the film increased. The erosion surface of the multiphase target material was analyzed with SEM. Particulate emission is minimized with increasing density and refined microstructure of the target material.

External diffusion of phosphorus in tantalum silicide bilayer film structure