Dry Etching Characteristics of Attenuated phase-shifting masks using C1-2 /CF_4/O_2/He Plasmas

摘要

The attenuated phase-shifting mask (Att. PSM) is one of the most useful technologies for sub-micron lithography. However, it is difficult to control the parameters such as phase or transmittance when a phase-shifting mask is applied to practical use. Also, to apply phase shift layer (MoSiON), it remains that affects several critical mask parameters including critical dimension (CD), sidewall slope and surface damage. So, in this paper, the effects of added C1_2 gas, DC bias voltage on the etch characteristics were studied using an inductively coupled CF_4-based plasma. The plasma characteristics and etch properties of inductively coupled CF _4/O_2/He and Cl_2/CF_4/O_2/He Plasmas were investigated on the etch properties of MoSiON. Each added gas had a unique property on the etch rate, anisotropy, surface roughness and sidewall morphology. As the results of experiment, the most vertical profile and smooth surface were obtained using the 10 sccm C1_2, -200V dc bias. By increasing the dc bias voltage, the undercut on MoSiON layer is not occurred. When plentiful C1_2 gas was added to the CF_4/O_2 /He plasma, surface roughness was decreased but the edge of Cr slope was damaged at 15 seem C1_2. It is suggested from the results of this experiment that the pattern profile and surface roughness on MoSiON layer can be controlled by both quantity of C1_2 gas and dc self-bias voltage.