A systemic process study on an electron beam nanolithography system operating at 100kV was pre-sent.The exposure conditions were optimized for resist ZEP520A.Grating structures with line/space of 50nm/50nm were obtained in a reasonably thick resist which is beneficial to the subsequent pattern transfer technique.The ICP etching process conditions was optimized.The role of etching parameters such as source power,gas pressure,and gas flow rate on the etching result was also discussed.A grating structure with line widths as small as 100nm,duty cycles of 0.5,depth of 900nm,and the side-wall scalloping as small as 5nm on a silicon substrate was obtained.The silicon deep etching technique for structure sizes smaller than 100nm is very important for the fabrication of nano-optical devices working in the visible regime. A systemic process study on an electron beam nanolithography system operating at 100 kV was pre-sent. The exposure conditions were optimized for resist ZEP 520A.Grating structures with line / space of 50 nm / 50 nm were obtained in a reasonably thick resist pattern transfer technique. The ICP etching process conditions was optimized. The role of etching parameters such as source power, gas pressure, and gas flow rate on the etching result was also discussed. A grating structure with line widths as small as 100 nm, duty cycles of 0.5, depth of 900 nm, and the side-wall scalloping as small as 5 nm on a silicon substrate was obtained. The silicon deep etching technique for structure sizes smaller than 100 nm is very important for the fabrication of nano-optical devices working in the visible regime.