Reactive‐Ion Etching (RIE) of TaSi2 / n +  Polysilicon Bilayers

Dry etching of a binary layer of cosputtered 2900Å thick on 3900Å thick phosphorus doped polycrystalline silicon films in has been studied. The influence of oxygen concentration, RF power, and sample temperature, on etch rate was investigated. The surface of the etched silicide was examined using field emission scanning electron microscope (FESEM) and scanning Auger electron spectroscopy (AES). It is found that the etch rates of ( i ) increased with increasing oxygen percentage initially, reached a maximum value near 4% , then started to decrease with increasing oxygen in gas at applied power at 275W, sample temperature of 60°C, total gas flow rate of 20 sccm, and chamber pressure of 40 mtorr, and ( ii ) increased nonlinearly with the RF power in gas at chamber pressure of 40 mtorr and total gas flow rate of 20 sccm. Etch rates followed an Arrhenius‐type temperature dependence with activation energy of 0.08 eV. The etching in has been related to the large differences in the metal fluoride and silicon fluoride vapor pressures. Also, based on Auger electron spectroscopy data from the etched surface it is suggested that the tantalum enrichment on the surface during silicide etching is responsible for the reduced steady‐state etch rate.