Hafnium oxide (HfO2) was very advantageous for substitute material of gate on existing transistor. HfO2 has been widely studied due to high contact with polysilicon and thermal stability and also, it is easily etched by using HF solution. In this study, HfO2 and thermal oxide films were etched by wet etch method using chemical etchant. Etch rate of HfO2 and thermal oxide was linearly increased with increasing concentration of HF and temperature but etch rate of HfO2 was higher than thermal oxide due to H+, F-, and HF2- ions at below 0.5% concentration of HF. And also, etch selectivity was improved by adding Hydrazine as additive.
