Resist-free patterned deposition of titanium dioxide thin films by light-induced chemical vapour deposition

摘要

Light-induced chemical vapour deposition of titanium dioxide thin films is realized from titanium tetra-isopropoxide and oxygen using a 308-nm excimer laser at low substrate temperature (<210℃). Complex shapes and multi-level deposits are obtained using a mask projection set up. This deposition technique is shown to be highly selective in several ways: (ⅰ) area selectivity: at substrate temperature below 150 ℃, the deposition takes place selectively in the irradiated area with a lateral resolution of 10 μm, still limited by the optical aberrations of the optical system, (ⅱ) thickness selectivity: an empirical relationship to the experimental parameters allows the control of the deposited thickness with a precision of 10 nm on films thinner than 300 nm and (ⅲ) crystallinity selectivity: the crystalline state of the material can be tailored between amorphous, anatase and rutile phase titanium dioxide. This paper presents a brief summary of the already reported advantages of the process (completed by new results on chemical area selectivity) and discusses the possibility and limitation to combine the advantages evidenced under different experimental conditions in a single deposit.