New etching system with a large diameter using electron beam excited plasma

A new etching system using electron-beam-excited plasma (EBEP) has been developed. This EBEP system is able to steadily produce a high-density plasma with a large diameter by introducing a high-current low electron beam into the etching chamber. The nonuniformity of plasma density and floating potential in an 8-inch wafer are improved up to ±2.5% and ±2 V, respectively. Anisotropic etching of n+-poly-Si in a pure Cl2 plasma is achieved with a high etch rate of 360 nm/min. The etching selectivity is 40 for poly-Si/photoresist and 150 for poly-Si/SiO2. These experimental results show that the EBEP etching system is suitable for manufacturing advanced ULSI.