Etch Characteristics of Gallium Indium Zinc Oxide Thin Films in a HBr/Ar Plasma

초록

Dry etching of gallium indium zinc oxide (GIZO) thin films needs to be developed with fine geometry in order to realize the devices such as a-GIZO TFTs, LCDs and solar cells. GIZO thin films are prepared on Si substrate by rf magnetron sputtering method and these films are patterned by lithography process using the photoresist of 950 nm in thickness. In this study, the etching of GIZO thin films patterned with photoresist (PR) are explored by using inductively coupled plasma reactive ion etching (ICPRIE) system (A-Tech, Korea) which can generate a high density plasma. The ICPRIE system consisted of main process chamber and load lock chamber. The etch rates and etch profiles of GIZO thin films are examined by varying HBr gas concentration. In addition, the effects of etch parameters on the etch rate and etch profile will be investigated and the main etch parameters used in this study are coil rf power, dc-bias voltage to substrate, and gas pressure. An alpha step (Tencor P-1) is used to measure the etch rates. The etch profiles are observed by field emission scanning electron microscopy (FESEM). The surface morphology and surface chemistry of etched films are observed using atomic force microscopy and x-ray photoelectron spectroscopy to understand the etch mechanism of GIZO films in a HBr/Ar plasma