Self-Aligned Cobalt Disilicide/Silicon Schottky Barrier Diodes

Cobalt disilicide/n-type silicon Schottky barrier diodes have been formed on (100) and (111) oriented silicon substrates, using a self-aligned process and rapid thermal annealing The material characteristics of the CoSi²/silicon layers have been examined on control blanket silicide films, using Nuclear Reaction Analysis, Rutherford Backscattering Spectrometry and Cross-section Transmission Electron Microscopy. This analysis revealed that the layers comprised of polycrystalline silicon rich silicide wit large grains and low levels of oxygen and carbon contaminants. The electrical analysis of the of the diodes, indicated near ideal rectification characteristics, with ideality factors in the range 1.04 to 1.05; the excess in the value of the ideality factor has been attributed to field-enhanced image-force barrier lowering at the periphery of the contact. Cobalt disilicide/silicon Schottky diodes have also been fabricated at a one micron scale. The annealing temperature dependence of the I-V characteristics for the diodes annealed in the temperature range 700°C and 1100°C, revealed consistent ideality factors (~1.06) between 700°C and 900°C, but larger values at temperatures greater than 900°C. However, the consistency in the values of the ideality factor at the lower temperature range, favourably indicate a wide ´window´ of annealing temperature for the fabrication of cobalt disilicide/silicon Schottky barrier diodes.