Abstract
Abstract We developed two novel methods of Cu seed layer deposition for ULSI metallization. First, We deposited TaSiX film as a barrier layer on SiO2,and TaSiX was sputtered by Ta target with a half of Si wafer. A mixture solution of hydrofluoric acid and cupric sulfate saturated aqueous solution was used to form Cu nucleus on TaSiX. Through sequential electrochemical reaction, the Cu seed layer was grown to replace TaSiX layer. The rest of TaSiX film was regarded as barrier layer. The rapid thermal annealing at temperature 350oC in N2 ambient was adopted in order to improve the adhesion between Cu and TaSiX film. The copper film with thickness 5000A was then electroplated on the Cu seed layer. Furthermore, Four Probe Point, Auger,, XRD, and XPS were measured to understand resistivity, the composition profile of TaSiX, and texture of the grains. Second, we deposited Ta film as a barrier layer on SiO2. PECVD amorphous-Si films with various thickness were then coated on Ta. A mixture solution of hydrofluoric acid and cupric sulfate saturated aqueous solution was used to form Cu nucleus on amorphous -silicon surface. Through sequential electrochemical reaction, the Cu seed layer was grown to replace amorphous-silicon layer. The rapid thermal annealing at temperature 350oC in N2 ambient was adopted in order to improve the adhesion between Cu and Ta film. The copper film with thickness 5000A was then electroplated on the Cu seed layer. Furthermore, Four Probe Point, Auger, SEM cross section of via, XRD, and XPS were measured to understand resistivity, the composition profile near the Interface, step coverage on the via, and texture of the grains, and varied bonding of of Ta. The thermal stability was studied by the C-V measurement of the sample sintered at temperature from 350oC to 500 oC . We found the thermal stability temperature is up to 450 oC.