The influence of He addition on Cl-etching procedure for Si-nanoscale structure fabrication using reactive ion etching system

Chlorine-based plasma have been often used to etch several semiconducting m aterials including Si and III-V materials. The chlorine plasma etching is w ell suited for fabrication of Si-nanoscale structures due to its good contr ol of undercutting and etch profile. Due to some drawbacks such as trenches and damages on the etch mask from physical ion assisted etching, the Cl-2/ He gas mixture using a conventional reactive ion etching system was utilize d and the optimization procedures were performed. Therefore, the influence of the He flow rate was examined. As the He flow increases over 30% of the total inlet gas flow, the plasma state become stable and the etch rate star ts to increase. For high flow rate over 60%, the relationship between the e tch depth and the etch time was observed to be nearly linear. In addition, the etch rate has been turned out to be linearly increasing with the He flo w rate. With this result, the Cl-2/He mixture plasma has been utilized and tested for fabrication of the deep Si sidewall and nanosize Si pillar array . (C) 2001 Elsevier Science B.V. All rights reserved.