Buried Mask Revelation in Silicon Dioxide for Double Gate MOS Fabrication

A new process for self-aligned double gate MOS fabrication is proposed. The milestone of this process in the revelation of a buried mask in the BOX of a SOI wafer and in a thermal oxide layer on top of active silicon film. The revelation of the buried mask makes use of the highly selective etching of implanted oxide in VHF. The etching mechanism of VHF etching of oxide is presented and the influence of the VHF etching parameters like temperature and etching time are discussed to prove the feasibility of this process step in order to integrate it in the whole process