Spectroscopic Ellipsometry Studies of Thin Films Prepared by Glancing Angle Deposition

Abstract

When thin films show columnar growth, the column direction can be changed easily by tilting the substrate with respect to the flux of incoming vapor from the source. We prepared various thin films at glancing angle of incidence by magnetron sputtering and e-beam evaporation. We applied a newly-developed rotating sample and compensator spectroscopic transmission ellipsometer to measure the optical anisotropy of these films. With this instrument, the retardance over 350 to 800 nm could be measured without a calibration process, even for < 1 degrees. Also, the optic axes of these films could be determined with uncertainty < 0.5 degrees. We observed strong birefringence from both e-beam-evaporated and sputtered films. E-beam-evaporated films showed birefringence of similar to 0.016. Meanwhile, magnetron-sputtered film exhibited birefringence of similar to 0.003. Effective medium theory with screening effect revealed that the magnetron-sputtered films contained much less void, which was a possible indication of poorly developed columnar structure.