No abstract

In this study, we investigated the etching characteristics of Mo and HfO 2 single layers and Mo/HfO 2 stacked structure for metal electrode/high-k gate stack patterning in O 2 /Cl 2 inductively coupled plasmas and the effects of O 2 addition on the etch rates and etch selectivity of the Mo to the HfO 2 layer. By controlling the process parameters such as the O 2 /Cl 2 flow ratio, the top electrode power and the dc self-bias voltage (V dc ), the Mo/HfO 2 etch selectivity as high as ¼ $ 67 could be obtained. Addition of O 2 gas to the O 2 /Cl 2 chemistry improved the Mo/HfO 2 etch selectivity because the O 2 gas in a certain flow ratio range reduced the HfO 2 etching reactions due to less chlorination of Hf but enhanced the Mo etch rate presumably due to effective formation of highly volatile Mo-O-Cl etch by-products.

In this study, we investigated the etching characteristics and mechanism of an amorphous carbon (a-C) layer for a multi-level resist (MLR) structure. Chemical-vapor-deposited (CVD) a-C layers with a SiO 2 hard-mask were etched in an inductively coupled plasma (ICP) etcher by varying the process parameters such as top electrode power, bottom electrode power, and gas flow ratio in N 2 /O 2 /Ar plasmas. The etch rate and profile angle of the CVD a-C thin films were decreased with increasing N 2 flow ratio in the N 2 /O 2 /Ar plasmas. As the N 2 flow ratio increased, the etch rate and the profile angle were reduced due to the enhanced formation of CN x on the etched surface. The etch rate of the CVD a-C thin films was increased with increasing the top and bottom electrode powers.