Atomic force microscopic imaging and wet etching of Bi2Ti2O7 thin films

Bi2Ti2O7 thin films were prepared by a sol–gel method using bismuth nitrate and titanium butoxide as precursors. Smooth films were successfully prepared on p-Si (1 1 1) substrates. The surface morphology of Bi2Ti2O7 thin films was studied by atomic force microscopy (AFM). Chemical wet etching of Bi2Ti2O7 thin films on Si substrates was performed with a total of six different etching solutions. The results show that the best etchant is neutral ammonium fluoride, hydrofluoric acid and pure water in a molar ratio of 2:1.2:3. The quality of Bi2Ti2O7 thin films and the etchant directly affect the etching of Bi2Ti2O7 thin films. As a high-K thin film, Bi2Ti2O7 can be widely used in storage capacitors, CMOS integrated devices and insulation gate field effect transistors.