Etching Characteristic of Zr-silicate in Cl2-based plasma

초록

For future sub 70nm technology, high k materials for gate dielectric layer are essential and Zr-silicate is one of the properties of Zr-silicate itself but also to look into fabrication procedure in term of the process intergration. In this paper, etching characteristics of Zr-silicate in Cl2+CH4 plasma is studied, and possible plasma damage is investigated by fabricating MIS capacitors. Since most of Zr compound are not volatile, etch rate of Zr-silicate film is relatively small in a Cl2 plasma ( less than 100 nm/min ), and the selectivity of Zr-silicate to silicon substrate or masking photoresist is less than 1. By adding CH4 we could increase the selectivity to near 2 while keeping the etch rate of Zr-silicate to about 70 nm/min. leakage current and flat bend voltage shift of Pt/Zr-silicate/Si capacitors are measured before and after plasma etching. rate etching damage mechanisms and to optimize the process. The leakage current of 1.2X10^(-3) A/cm^2 and smaller capacitance variation of 0.2 nF at -2V are obtained in Ar/Cl2/CF4 plasma at 200 W RF power.