Substrate wobble compensation for in situ spectroscopic ellipsometry measurements

摘要

Spectroscopic ellipsometry (SE) is an optical characterization technique that has been implemented on molecular beam epitaxy chambers for in situ characterization and growth control. SE measurements require collecting light reflected obliquely from the substrate. As the substrate is usually rotating during growth (to promote uniformity), acquiring accurate in situ SE data typically requires a substrate manipulator with low wobble (preferably \u3c0.1°). To overcome the low wobble manipulator requirement, the authors have designed and tested a return path SE configuration that compensates for the effects of substrate wobble. The prototype wobble compensation system demonstrated the near elimination of beam precession in the outgoing ellipsometer beam. The accuracy of the SE data acquired in the return path configuration during substrate rotation was also studied.