Growth and electrical characteristics of palladium silicide contacts on dry-etched silicon surfaces

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Abstract
Damage in silicon induced by dry etching processes is found to affect the kinetics of formation and the current-voltage characteristics of Pd2Si contacts formed in the 225–275 °C range. We show in this work that low-energy ion-beam etching (IBE) with Ar+ ions in the energy range 0.4–1.4 keV modifies the diffusivity controlling the silicide formation process. For the energy range and beam parameters studied, the diffusivity is found to increase approximately linearly with the IBE energy, while the activation energy of the silicide formation process does not change significantly. Although the depth of the damaged layer, prior to silicide formation, is not greater than 200 or 300 Å as detected by the Rutherford backscattering technique, the damage detected by the current-voltage characteristics of the Pd2Si/Si system is not removed by the silicide growth, particularly in the case of n-type silicon. A comparison of current-voltage characteristics for reactive-ion etched silicon and ion-beam etched Si demonstrates that the damage incurred in reactive-ion etching is also not consumed by low-temperature Pd2Si formation.