Etching Silicon Dioxide for CNT Field Emission Device
MEMS and Nanotechnology
Carbon nanotube (CNT) based electron field emission devices may have an advantage over metal Spindt tip style designs due to the ability to create a highly localized electric field at the extremely small diameter tip of the CNT. The primary objective for this work is to create a robust micro structure to support low voltage field emission from the CNTs in a gated device. This paper will discuss the micro fabrication techniques used to etch 2–4 μm thick thermal oxide layers on silicon substrates. A chrome layer is deposited by electron beam evaporation to make the gate layer of the triode device and act as an etch mask. The metal layer is then coated with photoresist, patterned with hole openings ranging from 8 to 12 μm in diameter and wet etched in acid through to the SiO2 layer. Different dry etch chemistries combined with wet etching are used to study the effect on the SiO2 sidewall. The shape and slope of the SiO2 sidewall and gate opening play a vital role in fabricating a robust triode device that doesn’t easily short out when the CNTs are grown later in the process.